The evolutionarily conserved genomic organization of the Hox genes has been a puzzle ever since it was discovered that their order along the chromosome is similar to the order of their functional domains along the antero‐posterior axis. Why has this colinearity been maintained throughout evolution? A close look at regulatory sequences from the mouse Hox clusters(1,2) suggests that enhancer sharing between adjacent Hox genes may be one reason. Moreover, characterizing the activity of one of these mouse enhancers in Drosophila(2) illustrates (...) that despite many similarities, not all Hox clusters are built in the same way. (shrink)

A central feature of the Covid-19 pandemic is state differences. Some state Governors closed all but essential businesses, others did not. In some states, most of the population wore face coverings when in public; in other states, <50% wore face coverings. According to journalists, these differences were symptomatic of a politically polarized America. The Big 5 personality factors also cluster at the state level. For example, residents of Utah score high on Conscientiousness and low on Neuroticism, whereas residents of Massachusetts (...) and Connecticut show the opposite pattern. In state-level regressions that controlled for partisan political allegiances, Conscientiousness was a significant predictor of the stringency of state Covid-19 restrictions, whereas Openness was a significant predictor of mask wearing. A number of the predictors were strongly correlated with each other. For example, the correlation coefficient linking Openness with the percentage of Democratic state legislators was r = 0.53. Commonality regression partitions the explained variance between the amount that is unique to each predictor and the amount that is shared among subsets of correlated predictors. This approach revealed that the common variance shared by Conscientiousness, Openness and partisan politics accounted for 34% of the state differences in Covid-19 policy and 35% of the state differences in mask wearing. The results reflect the importance of personality in how Americans have responded to the Covid-19 pandemic. (shrink)

Gene clustering is a useful exploratory technique to group together genes with similar expression levels under distinct cell cycle phases or distinct conditions. It helps the biologist to identify potentially meaningful relationships between genes. In this study, we propose a clustering method based on multivariate normal mixture models, where the number of clusters is predicted via sequential hypothesis tests: at each step, the method considers a mixture model of m components (m = 2 in the first step) (...) and tests if in fact it should be m - 1. If the hypothesis is rejected, m is increased and a new test is carried out. The method continues (increasing m) until the hypothesis is accepted. The theoretical core of the method is the full Bayesian significance test, an intuitive Bayesian approach, which needs no model complexity penalization nor positive probabilities for sharp hypotheses. Numerical experiments were based on a cDNA microarray dataset consisting of expression levels of 205 genes belonging to four functional categories, for 10 distinct strains of Saccharomyces cerevisiae. To analyze the method’s sensitivity to data dimension, we performed principal components analysis on the original dataset and predicted the number of classes using 2 to 10 principal components. Compared to Mclust (model-based clustering), our method shows more consistent results. (shrink)

An anthology of contemporary readings in analytic aesthetics, this reference reflects the relationships among the central aesthetic concerns of recent years. Providing a new perspective on the contemporary philosophy of art, this volume examines the challenge of Postmodernism and how it may or may not affect the future of analytic aesthetics... offers a case study of the progress that has been made in handling the problem of expression in the arts... reconceptualizes the concepts of the art work, its properties, and (...) our experience and evaluation of it -- to take into account an expanding cultural, sociological contextualization, i.e., art as a culturally emergent product of social institutions and conventions... features several readings organized around clusters of writers discussing each other's ideas and proposals, including: Beardsley, Dickie, and Blizek -- Wolterstorff, Levinson, and Bender -- Stolnitz and Dickie -- Beardsley, Margolis, and Novitz -- and Sibley and Dickie. Suitable for professionals in the art industry and anyone interested in the philosophy or aesthetics of art. (shrink)

Familial clustering of a disease is defined as the occurrence of the disease within some families in excess of what would be expected from the occurrence in the population. It has been demonstrated for several cancer types, ranging from rare cancers as the adenomatosis-coli-associated colon cancer or the Li-Fraumeni syndrome to more common cancers as breast cancer and colon cancer. Familial clustering, however, is merely an epidemiological pattern, and it does not tell whether genetic or environmental causes or (...) both in combination are responsible for the familial clustering. Familial clustering may be due to genetic predisposition to the disease, but exposure to environmental factors — shared by members of some families, but not by members of other families — may also cause familial clustering and hence mimic genetic inheritance in the study of nuclear families. Based on assumptions regarding the individual steps in the biological process starting with exposure to carcinogens and ending with death from disseminated cancer we suggest that genetic and environmental factors may both be involved in most of these steps. The present paper focuses on research methodologies necessary to discriminate between the effect of genes and family environment in the development of cancer. (shrink)

A model is proposed that deals with the observed collinearities (spatial, temporal and quantitative) of Hox gene expression during pattern formation along the primary and secondary axes of vertebrates. In particular, in the proximodistal axis of the developing limb, it is assumed that a morphogen gradient is laid down with its source at the distal tip of the bud. The extracellular signals in every cell of the morphogenetic field are transduced and uniformly amplified so that molecules are produced in (...) the nucleus with appropriate physicochemical properties. These molecules can exert a concentration‐dependent force on the Hox cluster. It is assumed that, before activation, the Hox cluster is packaged as an elongated rigid body inside the chromatin and is covered by a coat that prevents the transcription factors reaching the genes of the cluster. The transcription factors are confined to the interchromatin domain and their density decreases with their distance from the chromatin surface. A gradual increase in the extracellular morphogen concentration causes a corresponding increase in the number of the nuclear molecules and the resulting bigger force pushes the Hox cluster toward the interchromatin domain. The step‐by‐step translocations of the Hox cluster initiate the consecutive exposure of genes to their transcription factors. The model explains how gene activation is triggered and it describes spatial, temporal and quantitative collinearities at the initial stages of gene expression. Some recent experiments of Hox deletions and duplications are accounted for by the model. BioEssays 26:189–195, 2004. © 2004 Wiley Periodicals, Inc. (shrink)

The explosion of multiomics data poses new challenges to existing data mining methods. Joint analysis of multiomics data can make the best of the complementary information that is provided by different types of data. Therefore, they can more accurately explore the biological mechanism of diseases. In this article, two forms of joint nonnegative matrix factorization based on the sparse and graph Laplacian regularization method are proposed. In the method, the graph regularization constraint can preserve the local geometric structure of data. (...) L 2,1 -norm regularization can enhance the sparsity among the rows and remove redundant features in the data. First, SG-jNMF1 projects multiomics data into a common subspace and applies the multiomics fusion characteristic matrix to mine the important information closely related to diseases. Second, multiomics data of the same disease are mapped into the common sample space by SG-jNMF2, and the cluster structures are detected clearly. Experimental results show that SG-jNMF can achieve significant improvement in sample clustering compared with existing joint analysis frameworks. SG-jNMF also effectively integrates multiomics data to identify co-differentially expressed genes. SG-jNMF provides an efficient integrative analysis method for mining the biological information hidden in heterogeneous multiomics data. (shrink)

A recent report by Blumenthal et al.1 provides convincing evidence that at least 15% of Caenorhabditis elegans genes are co‐transcribed within over a thousand operons. Polycistronic transcription of gene clusters is very rare in eukaryotes. The widespread occurrence of operons in C. elegans thus raises some interesting questions about the origin and function of these multigenic transcriptional units. BioEssays 24:983–987, 2002. © 2002 Wiley‐Periodicals, Inc.

The chorion genes of Drosophila are amplified in response to developmental signals in the follicle cells of the ovary prior to their transcription. Their expression is regulated both temporally and spatially within this tissue. They thus serve as models both for the regulation of DNA replication and of developmental transcription. The regulatory elements for DNA amplification have been delineated. Their analysis reveals that amplification is mediated by several regulatory regions and initiates at defined origins within the chorion cluster. Proteins involved (...) in amplification are being identified both by mutations affecting amplification and by DNA binding studies. Regulatory elements for temporal as well as spatial control of chorion gene, expression have been characterized, and two candidate transcription factor genes have been cloned. (shrink)

The Hox genes play a role in anteroposterior axis specification of bilaterian animals that has been conserved for more than 600 million years. However, some of these genes have occasionally changed their roles in evolution. For example, the insect gene fushi tarazu (ftz), although localised in the Hox cluster, no longer acts as a Hox gene, but is involved in segmentation and nervous system development. Recent data of Mouchel‐Vielh et al.,1 and Hughes and Kaufman2 on ftz homologues in (...) a crustacean and a myriapod, respectively, shed new light onto the evolution of this gene. BioEssays 24:992–995, 2002. © 2002 Wiley‐Periodicals, Inc. (shrink)

Epigenetics impacts gene–culture coevolution by amplifying phenotypic variation, including clustering, and bridging the difference in timescales between genetic and cultural evolution. The dual inheritance model described by Uchiyama et al. could be modified to provide greater explanatory power by incorporating epigenetic effects.

The Affymetrix GeneChip is a popular microarray platform for genome‐wide expression profiling and has been widely used in functional genomics especially in the classification of cancers. Due to the updating of genome data, much of the genome information with which the chips were designed is out‐of‐date and it has been reported that many of the genes/transcripts on the chips differ from their original definition when mapping the probes to the new genome information. Dai et al. have reported that the updated (...) definition can cause as much as 30–50% discrepancy in the genes selected as differentially expressed on a heart tissue expression profiling dataset. Understanding the nature of this difference is therefore very important for the utilization of the data. In this work, with a large cancer dataset as an example, we compared two major definitions and investigated their effects on classification, clustering, discovery of differentially expressed genes and gene‐set‐based analysis. Results show that the two definitions agree well on clustering and classification results but genes and gene sets discovered as differentially expressed or enriched can be very different. Discoveries based on the Affymetrix definition can cover most of those based on the new definition, but tend to have more false positives. BioEssays 28: 739–746, 2006. © 2006 Wiley Periodicals, Inc. (shrink)

The history of research on pseudoalleles, closely linked genes that have similar functions, is rich and complex. Because pseudoalleles’ proximity on the chromosome makes their distinction by the complementation tests traditionally used by geneticists difficult, and because they have similar functions, they were initially often considered as allelic forms of the same gene, hence their name. The Hox cluster is an emblematic example of a pseudoallelic gene complex. The first observations of pseudoalleles were made very early but remained (...) puzzling until a simple model explaining their formation and characteristics emerged in the middle of the 1930s. This model suggested that pseudoalleles originated by gene.. (shrink)

Data mining’s primary clustering method has several uses, including gene analysis. A set of unlabeled data is divided into clusters using data features in a clustering study, which is an unsupervised learning problem. Data in a cluster are more comparable to one another than to those in other groups. However, the number of clusters has a direct impact on how well the K-means algorithm performs. In order to find the best solutions for these real-world optimization issues, it (...) is necessary to use techniques that properly explore the search spaces. In this research, an enhancement of K-means clustering is proposed by applying an equilibrium optimization approach. The suggested approach adjusts the number of clusters while simultaneously choosing the best attributes to find the optimal answer. The findings establish the usefulness of the suggested method in comparison to existing algorithms in terms of intra-cluster distances and Rand index based on five datasets. Through the results shown and a comparison of the proposed method with the rest of the traditional methods, it was found that the proposal is better in terms of the internal dimension of the elements within the same cluster, as well as the Rand index. In conclusion, the suggested technique can be successfully employed for data clustering and can offer significant support. (shrink)

Genomes of higher eukaryotes contain abundant non‐coding repeated sequences whose overall biological impact is unclear. They comprise two categories. The first consists of retrotransposon‐derived elements. These are three major families of retroelements (LINEs, SINEs and LTRs). SINEs are clustered in gene‐rich regions and are found in promoters of genes while LINEs are concentrated in gene‐poor regions and are depleted from promoters. The second class consists of non‐coding tandem repeats (satellite DNAs and TTAGGG arrays), which are associated with mammalian (...) centromeres, heterochromatin and telomeres. Terminal TTAGGG arrays are involved in telomere capping and satellite DNAs are located in heterochromatin, which is implicated in transcription silencing by gene repositioning (relocalization). It is unknown whether interstitial TTAGGG sequences, which are present in many vertebrates, have a function. Here, evidence will be presented that retroelements and TTAGGG arrays are involved in regulation of gene expression. Retroelements can provide binding sites for transcription factors and protect promoter CpG islands from repressive chromatin modifications, and may be also involved in nuclear compartmentalization of transcriptionally active and inactive domains. Interstitial telomere‐like sequences can form dynamically maintained three‐dimensional nuclear networks of transcriptionally inactive domains, which may be involved in transcription silencing like classic heterochromatin. BioEssays 30:338–348, 2008. © 2008 Wiley Periodicals, Inc. (shrink)

Gene expression network is also a type of complex network. It is challenging to analyze the gene expression network through relevant knowledge and algorithms of a complex network. In this paper, the existing characteristics of genes are analyzed from various indexes of the gene expression network to analyze key genes and TOP genes. Firstly, gene chip data are screened, gene data with obvious characteristics are selected, and relevant clustering characteristics are analyzed. Then, the complex (...) gene network structure is established, and gene networks with different threshold shapes and different sizes are selected. Finally, the relevant indexes and PR values after the PageRank algorithm are analyzed for complex networks under different thresholds, thus establishing the TOP gene and PR sequence. (shrink)

Gene drives are selfish genetic elements that use a variety of mechanisms to ensure they are transmitted to subsequent generations at greater than expected frequencies. Synthetic gene drives based on the clustered regularly interspersed palindromic repeats genome editing system have been proposed as a way to alter the genetic characteristics of natural populations of organisms relevant to the goals of public health, conservation, and agriculture. Here, we review the principles and potential applications of CRISPR drives, as well as (...) means proposed to prevent their uncontrolled spread. We also focus on recent work suggesting that factors such as natural genetic variation and inbreeding may represent substantial impediments to the propagation of CRISPR drives. CRISPR-based synthetic selfish genetic elements, or gene drives, have been proposed as a means by which to genetically alter natural populations to address issues in agriculture, conservation, and public health. We describe key concepts of CRISPR gene drives and limitations that must be addressed before their use in the wild. (shrink)

Recent research with human embryos, in different parts of the world, has sparked a new debate on the ethics of genetic human enhancement. This debate, however, has mainly focused on gene-editing technologies, especially CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats). Less attention has been given to the prospect of pursuing genetic human enhancement by means of IVF (In Vitro Fertilisation) in conjunction with in vitro gametogenesis, genome-wide association studies, and embryo selection. This article examines the different ethical implications of (...) the quest for cognitive enhancement by means of gene-editing on the one hand, and embryo selection on the other. The article focuses on the ethics of cognitive enhancement by means of embryo selection, as this technology is more likely to become commercially available before cognitive enhancement by means of gene-editing. This article argues that the philosophical debate on the ethics of enhancement should take into consideration public attitudes to research on human genomics and human enhancement technologies. The article discusses, then, some of the recent findings of the SIENNA Project, which in 2019 conducted a survey on public attitudes to human genomics and human enhancement technologies in 11 countries (France, Germany, Greece, the Netherlands, Poland, Spain, Sweden, Brazil, South Africa, South Korea, and United States). (shrink)

In the wake of the advent of genome editing technology CRISPR-Cas9 (clustered regularly interspaced palindromic repeat (CRISPR)-associated protein 9), there has been a global debate around the implications of manipulating the human genome. While CRISPR-based germline gene editing is new, the debate about the ethics of gene editing is not – for several decades now, scholars have debated the ethics of making heritable changes to the human genome. The arguments that have been raised both for and against the (...) use of genetic technologies in human reproduction reiterate much of the arguments made in the pre-CRISPR debate. As such, it is instructive for South Africa to reflect on these arguments now, in considering our position on the regulation of the use of this novel biotechnology. There are two dominant schools of thought in this area, bioliberalism and bioconservatism. Bioconservatives raise concerns about the risks of genetic manipulation, and argue that it ought to be limited or prohibited to avert these risks to human health and human nature. Bioliberal scholars are more open to the prospect of genetic manipulation, because of its potential utility. In this article, I conclude that in liberal democracies such as our own, bioliberal arguments ought to be seriously considered when formulating policy on human genome editing because of the extent to which they resonate with our Constitutional values and human rights. I further suggest that there is a need for an enquiry into the relevance of African perspectives on the ethical questions that arise concerning germline genome editing. (shrink)

International uproar followed the recent announcement of the birth of twin girls whose genomes had been edited with a breakthrough DNA editing-technology. This technology, called clustered regularly interspaced short palindrome repeats or CRISPR-Cas9, can alter any DNA, including DNA in embryos, meaning that changes can be passed to the offspring of the person that embryo becomes. Should we use gene editing technologies to change ourselves, our children, and future generations to come? The potential uses of CRISPR-Cas9 and other (...) class='Hi'>gene editing technologies are unprecedented in human history. By using these technologies, we eradicate certain dreadful diseases. Altering human DNA, however, raises enormously difficult questions. Some of these questions are about safety: Can these technologies be deployed without posing an unreasonable risk of physical harm to current and future generations? Can all physical risks be adequately assessed, and responsibly managed? But gene editing technologies also raise other moral questions, which touch on deeply held, personal, cultural, and societal values: Might such technologies redefine what it means to be healthy, or normal, or cherished? Might they undermine relationships between parents and children, or exacerbate the gap between the haves and have-nots? The broadest form of this second kind of question is the focus of this book: What might gene editing--and related technologies--mean for human flourishing? In the new essays collected here, an interdisciplinary group of scholars asks age--old questions about the nature and well-being of humans in the context of a revolutionary new biotechnology--one that has the potential to change the genetic make-up of both existing people and future generations. Welcoming readers who study related issues and those not yet familiar with the formal study of bioethics, the authors of these essays open up a conversation about the ethics of gene editing. It is through this conversation that citizens can influence laws and the distribution of funding for science and medicine, that professional leaders can shape understanding and use of gene editing and related technologies by scientists, patients, and practitioners, and that individuals can make decisions about their own lives and the lives of their families. (shrink)

The development of the CRISPR/Cas9 gene editing system has generated new possibilities for the use of gene drive constructs to reduce or suppress mosquito populations to levels that do not support disease transmission. Despite this prospect, social resistance to genetically modified organisms remains high. Gene drive open field research thus raises important questions regarding what is owed to those who may not consent to such research, or those could be affected by the proposed research, but whose consent (...) is not solicited. The precise circumstances under which informed consent must be obtained, and from whom, requires careful consideration. Furthermore, appropriate engagement processes should be central to any introduction of genetically modified mosquitos in proposed target settings. In this work, international guidance documents on informed consent and engagement are reviewed and applied to the genetically modified mosquito research context. Five analogous research endeavours that involve area-wide / open field experiments are reviewed. The approach of each in respect to the solicitation of individual informed consent and community engagement are highlighted. While the solicitation of individual informed consent in host settings of gene drive field trials may not be possible or feasible in some instances, local community and stakeholder engagement will be key to building trust towards the proposed conduct of such research. In this regard, the approaches taken by investigators and sponsors of political science field research and weather modification field research should be avoided. Rather, proponents of gene drive field research should look to the Eliminate Dengue field trials, cluster randomised trials, and pragmatic clinical trials for guidance regarding how the solicitation of individual informed consent of host communities ought to be managed, and how these communities ought to be engaged. (shrink)

A similarity index allowing comparisons of human populations has been defined as the common “Percentage of Isoactive Genes” or PIG, which can be calculated from any gene frequency distribution characterizing two populations. The complement to one of this value has been proved to be a distance, a measure which can be used in most techniques of cluster analysis as well as in usual representations of multivariated data (dendrograms, etc...). Furthermore, the formula can be generalized to a set of populations. (...) From a biological point of vue, PIG values are particularly meaningful, whereas other previously defined indices which tend to measure similarity or difference between populations neither have such an advantage, nor can they be expressed by a single and clear number like a percentage. Moreover,comparisons using PIG indices depend at first on the fluctuations of the most frequent genes of a distribution; on the other hand, different measures principally reflect the variations of low frequency genes, which unfortunately are nearly always poorly estimated, due to weak samples of populations.Interestingly, PIG values can be applied to any frequency distribution of any kind of objects. They can also extend to a whole set of distributions by using a mean value. When applying these measures to a series of polymorphic genetical systems such as ABO, Rhesus, MNSs, Gm and HLA, one can account for the variability or the homogeneity particular to the different human groups, with simple and objective criteria. (shrink)

Mechanisms involved in the regulation of development and its genetic control are receiving ever‐increasing attention in studies of mammalian developmental genetics. The potential success of such studies is strongly enhanced by the availability of suitable systems of analysis. Such a system was identified in a series of radiation‐induced chromosomal deletions at and around the albino (c) locus of the mouse associated with cell type‐specific effects on liver differentiation. Their detailed study has aided the analysis of possible machanisms of cell type‐specific (...) gene expression. As summarized in this review, the experimental results strongly suggest that specific trans‐acting developmental regulatory genes are concerned with the differentiation of hormone‐inducible expression of a cluster of hepatocyte specific structural genes mapping in different parts of the genome. (shrink)

The basic premise of the host‐defense theory is that genomic imprinting, the parent‐of‐origin expression of a subset of mammalian genes, derives from mechanisms originally dedicated to silencing repeated and retroviral‐like sequences that deeply colonized mammalian genomes. We propose that large clusters of tandemly‐repeated C/D‐box small nucleolar RNAs (snoRNAs) or microRNAs represent a novel category of sequences recognized as “genomic parasites”, contributing to the emergence of genomic imprinting in a subset of chromosomal regions that contain them. Such a view is supported (...) by evidence derived from studies of the imprinted snoRNA‐ and/or miRNA‐encoding Dlk1‐Dio3, Snurf‐Snrpn, Sfbmt2, and C19MC domains. While adding a new piece to the challenging puzzle of mammalian genome history, this hypothesis also reinforces the notion that dissecting the features and molecular mechanisms that discriminate between “foreign” and “endogenous” sequences is of crucial importance in the field of mammalian epigenetics. (shrink)

Expression patterns of Antennapedia‐like homeogenes in the mouse embryo show many similarities to those of their homologues in Drosophila. It is argued here that homeogenes may regulate development of the body plan in mouse by mechanisms similar to those used in Drosophila. In particular, they may differentially specify positional address of cell groups within lineage compartments along the body axes. In vertebrates, a single ancestral homeogene cluster has become duplicated to give four separate clusters. Comparisons of homeogene expression patterns between (...) different clusters of the mouse suggest ways in which duplication has permitted development of a more complex body plan. Cluster duplication may therefore have provided a selective advantage during vertebrate evolution. (shrink)

Despite ever‐increasing accumulation of genomic data, the fundamental question of how individual genes are switched on during development, lineage‐specification and differentiation is not fully answered. It is widely accepted that this involves the interaction between at least three fundamental regulatory elements: enhancers, promoters and insulators. Enhancers contain transcription factor binding sites which are bound by transcription factors (TFs) and co‐factors expressed during cell fate decisions and maintain imposed patterns of activation, at least in part, via their epigenetic modification. This information (...) is transferred from enhancers to their cognate promoters often by coming into close physical proximity to form a ‘transcriptional hub’ containing a high concentration of TFs and co‐factors. The mechanisms underlying these stages of transcriptional activation are not fully explained. This review focuses on how enhancers and promoters are activated during differentiation and how multiple enhancers work together to regulate gene expression. We illustrate the currently understood principles of how mammalian enhancers work and how they may be perturbed in enhanceropathies using expression of the α‐globin gene cluster during erythropoiesis, as a model. (shrink)

Investigation of the evolution of the DNA sequences that comprise a small gene cluster in five closely related species of Drosophila shows that it evolves as a mosaic, with adjacent subregions displaying very different rates and types of evolution. It appears that local differences in the influence of selectional and mutational forces result in the formation of these distinct subregions.

A circadian clock, with physiological characteristics similar to those of eukaryotes, functions in the photosynthetic prokaryote, cyanobacteria. The molecular mechanism of this clock has been efficiently dissected using a luciferase reporter gene that reports the status of the clock. A circadian clock gene cluster, kaiABC, has been cloned via rhythm mutants of cyanobacterium, Synechococcus, and many clock mutations mapped to the three kai genes. Although kai genes do not share any homology with clock genes so far identified in (...) eukaryotes, analysis of their expression suggests that a negative feedback control of kaiC expression by KaiC generates the circadian oscillation and that KaiA functions as a positive factor to sustain this oscillation. BioEssays 22:10–15, 2000. ©2000 John Wiley & Sons, Inc. (shrink)

In vertebrates it is often found that if one considers a group of genes clustered on a certain chromosome, then the homologues of those genes often form another cluster on a different chromosome. There are four explanations, not necessarily mutually exclusive, to explain how such homologous clusters appeared. Homologous clusters are expected at a low probability even if genes are distributed at random. The duplication of a subset of the genome might create homologous clusters, as would a duplication of the (...) entire genome. Alternatively, it may be adaptive for certain combinations of genes to cluster, although clearly the genes must have duplicated prior to rearrangement into clusters. Molecular phylogenetics provides a means to examine the origins of homologous clusters, although it is difficult to discriminate between the different explanations using current data. However, with more extensive sequencing and mapping of vertebrate genomes, especially those of the early diverging chordates, it should soon become possible to resolve the origins of homologous clusters. BioEssays 21:697–703, 1999. © 1999 John Wiley & Sons, Inc. (shrink)

The vertebrate immune system provides a remarkable showcase of the different ways the genome can be used to specify cellular identity and to mediate cellular function. It is arguably the leading mammalian system in which gene regulation programs that drive the acquisition of specific cell-type identities have been elucidated at the single cell level. More broadly for molecular genomics, the activation-induced gene expression pathways used in immune effector responses have provided textbook cases for fundamental elements of transcription factor (...) assembly at enhancers ; and immune system genes and gene clusters have provided key paradigms for the roles of long-range.. (shrink)

Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)‐based “active genetic” elements developed in 2015 bypassed the fundamental rules of traditional genetics. Inherited in a super‐Mendelian fashion, such selfish genetic entities offered a variety of potential applications including: gene‐drives to disseminate gene cassettes carrying desired traits throughout insect populations to control disease vectors or pest species, allelic drives biasing inheritance of preferred allelic variants, neutralizing genetic elements to delete and replace or to halt the spread of gene‐drives, split‐drives with (...) the core constituent Cas9 endonuclease and guide RNA (gRNA) components inserted at separate genomic locations to accelerate assembly of complex arrays of genetic traits or to gain genetic entry into novel organisms (vertebrates, plants, bacteria), and interhomolog based copying systems in somatic cells to develop tools for treating inherited or infectious diseases. Here, we summarize the substantial advances that have been made on all of these fronts and look forward to the next phase of this rapidly expanding and impactful field. (shrink)

Clustered, regularly interspaced, short palindromic repeat (CRISPR)/CRISPR‐associated protein (CRISPR/Cas) system has revolutionized genetic research in the life sciences. Four classes of CRISPR/Cas‐derived genome editing agents, such as nuclease, base editor, recombinase, and prime editor have been introduced for engineering the genomes of diverse organisms. The recently introduced prime editing system offers precise editing without many off‐target effects than traditional CRISPR‐based systems. Many researchers have successfully applied this gene‐editing toolbox in diverse systems for various genome‐editing applications. This review presents the (...) mechanism of prime editing and summarizes the details of the prime editing system applied in plants and mammalian cells for precise genome editing. We also discuss the advantages, limitations, and potential future applications of prime editing in these systems. This review enables the researcher to gain knowledge on prime editing tools and their potential applications in plants and mammalian cells. (shrink)

Autism Spectrum Disorder (ASD) is extremely heterogeneous clinically and genetically. There is a pressing need for a better understanding of the heterogeneity of ASD based on scientifically rigorous approaches centered on systematic evaluation of the clinical and research utility of both phenotype and genotype markers. This paper presents a holistic PheWAS-inspired method to identify meaningful associations between ASD phenotypes and genotypes. We generate two types of phenotype-phenotype (p-p) graphs: a direct graph that utilizes only phenotype data, and an indirect graph (...) that incorporates genotype as well as phenotype data. We introduce a novel methodology for fusing the direct and indirect p-p networks in which the genotype data is incorporated into the phenotype data in varying degrees. The hypothesis is that the heterogeneity of ASD can be distinguished by clustering the p-p graph. The obtained graphs are clustered using network-oriented clustering techniques, and results are evaluated. The most promising clusterings are subsequently analyzed for biological and domain-based relevance. Clusters obtained delineated different aspects of ASD, including differentiating ASD-specific symptoms, cognitive, adaptive, language and communication functions, and behavioral problems. Some of the important genes associated with the clusters have previous known associations to ASD. We found that clusters based on integrated genetic and phenotype data were more effective at identifying relevant genes than clusters constructed from phenotype information alone. These genes included five with suggestive evidence of ASD association and one known to be a strong candidate. (shrink)

Cis‐regulatory elements govern gene expression programs to determine cell identity during development. Recently, the possibility that multiple enhancers are orchestrated in clusters of enhancers has been suggested. How these elements are arranged in the 3D space to control the activation of a specific promoter remains unclear. Our recent work revealed that the TGFβ pathway drives the assembly of enhancer clusters and precise gene activation during neurogenesis. We discovered that the TGFβ pathway coactivator JMJD3 was essential in maintaining these (...) structures in the 3D space. To do that, JMJD3 required an intrinsically disordered region involved in forming phase‐separated biomolecular condensates found in the enhancer clusters. Our data support the existence of a relationship between 3D‐conformation of the chromatin, biomolecular condensates, and TGFβ‐driven response during mammalian neurogenesis. In this review, we discuss how signaling (TGFβ), epigenetics (JMJD3), and biochemical properties (biomolecular condensates nucleation) are coordinated to modulate the genome structure to guarantee proper neural development. Moreover, we comment on the potential underlying mechanisms and implications of the enhancer‐mediated regulation. Finally, we point out the knowledge gaps that still need to be addressed. (shrink)

Most current techniques to deal with invasive species are ineffective or have highly damaging side effects. To this end suppression-drives based on clustered regularly inter-spaced short palindromic repeats (CRISPR/Cas9) have been touted as a potential silver bullet for the problem, allowing for a highly focused, humane and cost-effective means of removing a target species from an environment. Suppression-drives come with serious risks, however, such that the precautionary principle seems to warrant us not deploying this technology. The focus of this paper (...) is on one such risk – the danger of a suppression-drive escaping containment and wiping out the target species globally. Here, I argue that in most cases this risk is significant enough to warrant not using a gene-drive. In some cases, however, we can bypass the precautionary principle by using an approach that hinges on what I term the ‘Worst-Case Clause’. This clause, in turn, provides us with a litmus test that can be fruitfully used to determine what species are viable targets for suppression-drives in the wild. Using this metric in concert with other considerations, I suggest that only three species are currently possible viable targets – the European rabbit, ship rat and Caribbean Tree Frog. (shrink)

This paper seeks to expand our appreciation of the gene editing tool, clustered regularly interspaced short palindromic repeats‐associated protein 9 (CRISPR‐Cas9), its function, its benefits and risks, and the challenges of regulating its use. I frame CRISPR's emergence and its current use in the context of 150 years of formal exploration of heredity and genetics. I describe CRISPR's structure and explain how it functions as a useful engineering tool. The contemporary international and domestic regulatory environment governing human genetic interventions (...) is reviewed and shown to be increasingly ineffective in its ability to restrain, guide, and optimize the emerging use of CRISPR. Several reasons for this lack of consensus are discussed. In conclusion, I suggest a number of public policy recommendations that might allow us to simultaneously embrace our most important moral values and manage the inevitable power CRISPR will come to have in our lives. (shrink)

Co‐expression of two or more genes at the single‐cell level is usually associated with functional co‐regulation. While mRNA co‐expression—measured as the correlation in mRNA levels—can be influenced by both transcriptional and post‐transcriptional events, transcriptional regulation is typically considered dominant. We review and connect the literature describing transcriptional and post‐transcriptional regulation of co‐expression. To enhance our understanding, we integrate four datasets spanning single‐cell gene expression data, single‐cell promoter activity data and individual transcript half‐lives. Confirming expectations, we find that positive co‐expression (...) necessitates promoter coordination and similar mRNA half‐lives. Surprisingly, negative co‐expression is favored by differences in mRNA half‐lives, contrary to initial predictions from stochastic simulations. Notably, this association manifests specifically within clusters of genes. We further observe a striking compensation between promoter coordination and mRNA half‐lives, which additional stochastic simulations suggest might give rise to the observed co‐expression patterns. These findings raise intriguing questions about the functional advantages conferred by this compensation between distal kinetic steps. (shrink)

Metallothioneins (MTs) are ubiquitous proteins with the capacity to bind heavy metal ions (mainly Cd, Zn or Cu), and they have been found in animals, plants, eukaryotic and prokaryotic micro‐organisms. We have carried out a comparative analysis of ciliate MTs (Tetrahymena species) to well‐known MTs from other organisms, discussing their exclusive features, such as the presence of aromatic amino acid residues and almost exclusive cysteine clusters (CCC) present in cadmium‐binding metallothioneins (CdMTs), higher heavy metal‐MT stoichiometry values, and a strictly conserved (...) modular–submodular structure. Based on this last feature and an extensive gene duplication, we propose a possible model for the evolutionary history of T. thermophila MTs. We also suggest possible functions for these MTs from consideration of their differential gene expressions and discuss the potential use of these proteins and/or their gene promoters for designing molecular or whole‐cell biosensors for a fast detection of heavy metals in diverse polluted ecosystems. (shrink)

This focus issue considers the normative implications of the recent emergence in genome editing technology known as CRISPR (clustered regularly interspaced short palindromic repeats) or CRISPR‐associated protein 9. Originally discovered in the adaptive immune systems of bacteria and archaea, CRISPR enables researchers to make efficient and site‐specific modifications to the genomes of cells and organisms. More accessible, precise, and economic than previous gene editing technologies, CRISPR holds the promise of not only transforming the fields of genetics, agriculture, and human (...) medicine, but also heralding a new era of democratized biotechnology. However, the speed with which developments in the field have progressed threatens to overwhelm our normative sensibilities about the long‐term practical and ethical implications. The contributors to this focus issue attempt to think through some of the more salient moral and practical consequences of CRISPR in the context of religious ethics, particularly as they relate to themes of autonomy, human flourishing, social justice, and the ethics of enhancement. (shrink)

Talk of different types of cells is commonplace in the biological sciences. We know a great deal, for example, about human muscle cells by studying the same type of cells in mice. Information about cell type is apparently largely projectible across species boundaries. But what defines cell type? Do cells come pre-packaged into different natural kinds? Philosophical attention to these questions has been extremely limited [see e.g., Wilson (Species: New Interdisciplinary Essays, pp 187–207, 1999; Genes and the Agents of Life, (...) 2005; Wilson et al. Philos Top 35(1/2):189–215, 2007)]. On the face of it, the problems we face in individuating cellular kinds resemble those biologists and philosophers of biology encountered in thinking about species: there are apparently many different (and interconnected) bases on which we might legitimately classify cells. We could, for example, focus on their developmental history (a sort of analogue to a species’ evolutionary history); or we might divide on the basis of certain structural features, functional role, location within larger systems, and so on. In this paper, I sketch an approach to cellular kinds inspired by Boyd’s Homeostatic Property Cluster Theory, applying some lessons from this application back to general questions about the nature of natural kinds. (shrink)

CRISPR (clustered regularly interspaced short palindromic repeats) activation (CRISPRa) in bacteria is an attractive method for programmable gene activation. Recently, a eukaryote‐like, σ54‐dependent CRISPRa system has been reported. It exhibits high dynamic ranges and permits flexible target site selection. Here, an overview of the existing strategies of CRISPRa in bacteria is presented, and the characteristics and design principles of the CRISPRa system are introduced. Possible scenarios for applying the eukaryote‐like CRISPRa system is discussed with corresponding suggestions for performance optimization (...) and future functional expansion. The authors envision the new eukaryote‐like CRISPRa system enabling novel designs in multiplexed gene regulation and promoting research in the σ54‐dependent gene regulatory networks among a variety of biotechnology relevant or disease‐associated bacterial species. (shrink)

Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) has been the buzzword for genome editing in the past few years, especially with the birth of Lulu and Nana, twin girls who were genetically edited using the CRISPR/Cas system. To discuss this, a group of scientists, theologians, and ethicists gathered at the 2019 Institute on Religion in the Age of Science (IRAS) conference to discuss the implications of CRISPR gene editing. It became quickly apparent through our discussions that this CRISPR revolution (...) will impact not only human medicine, but any application that involves DNA in every organism from bacteria to plants and animals. Moreover, there are multiple stakeholders in this technology—not only the scientific community, but also the business, legal, and religious communities, to name a few. As a scientist myself, I am providing a brief overview of the scientific hopes and concerns about this powerful technology. (shrink)

Individuals are a prominent part of the biological world. Although biologists and philosophers of biology draw freely on the concept of an individual in articulating both widely accepted and more controversial claims, there has been little explicit work devoted to the biological notion of an individual itself. How should we think about biological individuals? What are the roles that biological individuals play in processes such as natural selection (are genes and groups also units of selection?), speciation (are species individuals?), and (...) organismic development (do genomes code for organisms)? Much of our discussion here will focus on organisms as a central kind of biological individual, and that discussion will raise broader questions about the nature of the biological world, for example, about its complexity, its organization, and its relation to human thought. (shrink)

The largest group of transcription factors in higher eukaryotes are C2H2 proteins, which contain C2H2‐type zinc finger domains that specifically bind to DNA. Few well‐studied C2H2 proteins, however, demonstrate their key role in the control of gene expression and chromosome architecture. Here we review the features of the domain architecture of C2H2 proteins and the likely origin of C2H2 zinc fingers. A comprehensive investigation of proteomes for the presence of proteins with multiple clustered C2H2 domains has revealed a key (...) difference between groups of organisms. Unlike plants, transcription factors in metazoans contain clusters of C2H2 domains typically separated by a linker with the TGEKP consensus sequence. The average size of C2H2 clusters varies substantially, even between genomes of higher metazoans, and with a tendency to increase in combination with SCAN, and especially KRAB domains, reflecting the increasing complexity of gene regulatory networks. (shrink)

Emerging evidence suggests that microRNA (miRNA)‐mediated post‐transcriptional gene regulation plays an essential role in modulating embryonic stem (ES) cell pluripotency maintenance, differentiation, and reprogramming of somatic cells to an ES cell‐like state. Investigations from ES cell‐enriched miRNAs, such as mouse miR‐290 cluster and human miR‐302 cluster, and ES cell‐depleted miRNAs such as let‐7 family miRNAs, revealed a common theme that miRNAs target diverse cellular processes including cell cycle regulators, signaling pathway effectors, transcription factors, and epigenetic modifiers and shape their (...) protein output. The combinatorial effects downstream of miRNA action allow miRNAs to modulate cell‐fate decisions effectively. Furthermore, the transcription and biogenesis of miRNAs are also tightly regulated. Thus, elucidating the interplay between miRNAs and other modes of gene regulation will shed new light on the biology of pluripotent stem cells and somatic cell reprogramming. (shrink)