Mammalian Genes (mammalian + gene)

Distribution by Scientific Domains


Selected Abstracts


Helicase homologues maintain cytosine methylation in plants and mammals

BIOESSAYS, Issue 4 2002
Déborah Bourc'his
The Arabidopsis DDM1 gene is required for the maintenance of genomic methylation patterns but is a helicase homolog of the SWI2/SNF2 family rather than a DNA methyltransferase.(1) Dennis et al.(2) have shown that disruption of the mouse Lsh gene, the mammalian gene most closely related to DDM1, causes demethylation of the mouse genome. This result suggests that the mechanisms that maintain methylation patterns in the genomes of mammals and flowering plants are more conserved than previously suspected. BioEssays 24:297,299, 2002. ©2002 Wiley Periodicals, Inc. [source]


Spermatogenesis-defective (spe) mutants of the nematode Caenorhabditis elegans provide clues to solve the puzzle of male germline functions during reproduction

DEVELOPMENTAL DYNAMICS, Issue 5 2010
Hitoshi Nishimura
Abstract In most species, each sex produces gametes, usually either sperm or oocytes, from its germline during gametogenesis. The sperm and oocyte subsequently fuse together during fertilization to create the next generation. This review focuses on spermatogenesis and the roles of sperm during fertilization in the nematode Caenorhabditis elegans, where suitable mutants are readily obtained. So far, 186 mutants defective in the C. elegans male germline functions have been isolated, and many of these mutations are alleles for one of the ,60 spermatogenesis-defective (spe) genes. Many cloned spe genes are expressed specifically in the male germline, where they play roles during spermatogenesis (spermatid production), spermiogenesis (spermatid activation into spermatozoa), and/or fertilization. Moreover, several spe genes are orthologs of mammalian genes, suggesting that the reproductive processes of the C. elegans and the mammalian male germlines might share common pathways at the molecular level. Developmental Dynamics 239:1502,1514, 2010. © 2010 Wiley-Liss, Inc. [source]


DNA methylation of Sleeping Beauty with transposition into the mouse genome

GENES TO CELLS, Issue 8 2005
Chang Won Park
The Sleeping Beauty transposon is a recently developed non-viral vector that can mediate insertion of transgenes into the mammalian genome. Foreign DNA elements that are introduced tend to invoke a host-defense mechanism resulting in epigenetic changes, such as DNA methylation, which may induce transcriptional inactivation of mammalian genes. To assess potential epigenetic modifications associated with Sleeping Beauty transposition, we investigated the DNA methylation pattern of transgenes inserted into the mouse genome as well as genomic regions flanking the insertion sites with bisulfite-mediated genomic sequencing. Transgenic mouse lines were created with two different Sleeping Beauty transposons carrying either the Agouti or eGFP transgene. Our results showed that DNA methylation in the keratin-14 promoter and Agouti transgene were negligible. In addition, two different genomic loci flanking the Agouti insertion site exhibited patterns of DNA methylation similar to wild-type mice. In contrast, high levels of DNA methylation were observed in the eGFP transgene and its ROSA26 promoter. These results indicate that transposition via Sleeping Beauty into the mouse genome may result in a significant level of de novo DNA methylation. This may depend on a number of different factors including the cargo DNA sequence, chromosomal context of the insertion site, and/or host genetic background. [source]


The math of making mutant mice

GENES, BRAIN AND BEHAVIOR, Issue 4 2003
R. W. Williams
More than ten large-scale mutagenesis projects are now generating hundreds of novel mouse mutants. Projects employ a wide variety of strategies and screens: targeting as much as the whole genome, part of a chromosome or just single genes. In this commentary, we consider the pros and cons of different tactics. We highlight issues of cost, efficiency and defend the impact of this mutagenesis program in an era of sophisticated conditional knockouts and advanced transgenic lines. Given the significant difficulties of adequately phenotyping and mapping randomly generated mutations that cover the whole genome, we tend to favor regional and gene-targeted screens. Whatever the choice of method, whole genome sequence data combined with detailed transcriptome and proteome surveys promise to significantly improve the efficiency with which series of mutations in a large subset of mammalian genes can be generated and cloned. [source]


Physiological functions of imprinted genes

JOURNAL OF CELLULAR PHYSIOLOGY, Issue 3 2002
Benjamin Tycko
Genomic imprinting in gametogenesis marks a subset of mammalian genes for parent-of-origin-dependent monoallelic expression in the offspring. Embryological and classical genetic experiments in mice that uncovered the existence of genomic imprinting nearly two decades ago produced abnormalities of growth or behavior, without severe developmental malformations. Since then, the identification and manipulation of individual imprinted genes has continued to suggest that the diverse products of these genes are largely devoted to controlling pre- and post-natal growth, as well as brain function and behavior. Here, we review this evidence, and link our discussion to a website (http://www.otago.ac.nz/IGC) containing a comprehensive database of imprinted genes. Ultimately, these data will answer the long-debated question of whether there is a coherent biological rationale for imprinting. © 2002 Wiley-Liss, Inc. [source]


Linkage Analysis of Affected Sib Pairs Allowing for Parent-of-Origin Effects

ANNALS OF HUMAN GENETICS, Issue 1 2005
Chih-Chieh Wu
Summary Parent-of-origin effects, also known as genomic imprinting, exist for many mammalian genes. For imprinted genes the expression of an allele depends upon the sex of the transmitting parent. Here we have developed a method based on alleles that are shared identical by descent by affected sib pairs, that allows for parent-of-origin effects. Our method allows for sex-specific recombination rates, an important consideration in studying imprinted genes. We have also derived a tetrahedron for the true identical-by-descent frequencies accounting for parent-of-origin effects. Using this tetrahedron, we propose a robust generalized minmax test for linkage and discuss its properties in the presence of genomic imprinting. We have also performed power comparisons of various allele sharing tests and provide regions of the tetrahedron in which the different tests are optimal. We also provide useful strategies to determine the optimal tests to use while performing a genome scan. [source]