Search results for " chromosome"
showing 10 items of 336 documents
A sequence motif enriched in regions bound by the Drosophila dosage compensation complex
2010
Abstract Background In Drosophila melanogaster, dosage compensation is mediated by the action of the dosage compensation complex (DCC). How the DCC recognizes the fly X chromosome is still poorly understood. Characteristic sequence signatures at all DCC binding sites have not hitherto been found. Results In this study, we compare the known binding sites of the DCC with oligonucleotide profiles that measure the specificity of the sequences of the D. melanogaster X chromosome. We show that the X chromosome regions bound by the DCC are enriched for a particular type of short, repetitive sequences. Their distribution suggests that these sequences contribute to chromosome recognition, the genera…
Global patterns of sequence evolution in Drosophila.
2007
This article is available from: http://www.biomedcentral.com/1471-2164/8/408
Genetic sex determination and sex-specific lifespan in tetrapods – evidence of a toxic Y effect
2020
ABSTRACTSex-specific lifespans are ubiquitous across the tree of life and exhibit broad taxonomic patterns that remain a puzzle, such as males living longer than females in birds and vice versa in mammals. The prevailing “unguarded-X” hypothesis (UXh) explains this by differential expression of recessive mutations in the X/Z chromosome of the heterogametic sex (e.g., females in birds and males in mammals), but has only received indirect support to date. An alternative hypothesis is that the accumulation of deleterious mutations and repetitive elements on the Y/W chromosome might lower the survival of the heterogametic sex (“toxic Y” hypothesis). Here, we report lower survival of the heterog…
Chromosomes and the origins of Apes and Australopithecines
1996
International audience; Comparison of molecular data suggests that the higher apes (Gorilla, Pan) and humankind (Homo) are closely related and that they diverged from the common ancestor through two speciation events situated very closely together in time. Examination of the chromosomal formulas of the living species reveals a paradox on the distribution of mutated chromosomes which can only be re-solved by a model of trichotomic diversification. This new model of divergence from the common ancestor is characterized by the transition from (1) a monotypic phase to (2) a polytypic phase of three sub-species - pre-gorilla, pre-chimpanzee and pre-australopithecine. The quadruped ancestors of Au…
Patterns of Puffing Activity in the Polytene Chromosomes of Drosophila Subobscura
1982
The puffs and Balbiani rings are the visible expression of sites of genetic activity (Beerman, 1952). Since Beermann’s original hypothesis, puffing patterns for several species of Diptera have been described. Thus for the genus Drosophila, Ashburner (1967, 1969a and 1969b) has reported the puffing pattern of Drosophila melanogaster and Drosophila simulans, Beredens (1965) of Drosophila hydei, and Moriwaki and Ito (1969) of Drosophila ananassae. In a previous paper Frutos and Latorre (1981) have determined puffing patterns of the J and U chromosomes of Drosophila subobscura. This species shows a rich chromosomal polymorphism and the puffing pattern of several chromosomal rearrangements of th…
The Putative Metal Coordination Motif in the Endonuclease Domain of Human Parvovirus B19 NS1 Is Critical for NS1 Induced S Phase Arrest and DNA Damage
2011
The non-structural proteins (NS) of the parvovirus family are highly conserved multi-functional molecules that have been extensively characterized and shown to be integral to viral replication. Along with NTP-dependent helicase activity, these proteins carry within their sequences domains that allow them to bind DNA and act as nucleases in order to resolve the concatameric intermediates developed during viral replication. The parvovirus B19 NS1 protein contains sequence domains highly similar to those previously implicated in the above-described functions of NS proteins from adeno-associated virus (AAV), minute virus of mice (MVM) and other non-human parvoviruses. Previous studies have show…
Pheromone-binding proteins of scarab beetles.
1998
: We have characterized Pheromone binding proteins (PBPs) present in the antennae of several species of scarab beetles. In most cases there was only one class of PBP, which was expressed in both sexes. Both Anomala osakana and Popillia japonica possess a single PBP, highly homologous to each other. In each species the same PBP seems to recognize both enantiomers of japonilure, which have opposite biological functions, i.e., the sex Pheromone and the behavioral antagonist (stop signal). The purified PBP of A. osakana binds both enantiomers apparently with the same low affinity. Unexpectedly, these ligands were bound by moth PBPs, which utilize Pheromones with unrelated structures. These find…
Biochemistry and Molecular Biology of DNA Replication in Yeast
1985
For the past two decades, the study of the mechanism of DNA replication has been focused mainly on the chromosomes of the simple prokaryotes and their viruses (1). The complexity of the eukaryotic genome and multiple levels of control during the replication of eukaryotic chromosomes have until recently prevented similar studies. In recent years, a lower eukaryote, the yeast Saccharomyces cerevisiae, has become a major focus of efforts in molecular biology. In this chapter, I will briefly review accomplishments in this area. Yeast is an ideal model system for studies on the structure and replication of the eukaryotic chromosome. Yeast cells are easy to grow and study biochemically. Genetic a…
Cellul�re Immunreaktionen gegen�ber homologen leberspezifischen Antigenen (HLP) bei chronischen Leberentz�ndungen
1974
Es wird eine Zweiphasentechnik des Leukocyten-Migrations-Inhibitionstestes beschrieben und zum Nachweis einer cellularen Immunreaktion gegenuber Leberantigenen bei chronisch-entzundlichen Lebererkrankungen eingesetzt. Mit dieser Technik wurde bei 85% der Patienten mit hypergammaglobulinamischer Verlaufsform einer chronisch-aktiven Hepatitis und 42% der Patienten mit aktiv fortschreitenden kryptogenen Lebercirrhosen eine Migrationshemmung nachgewiesen. Lebergesunde Kontrollen zeigten keine, Patienten mit dem Zustand nach Hepatitis und chronisch-persistierender Hepatitis selten eine Leukocytenmigrationsinhibition gegenuber leberspezifischen Antigenen. 17% der Patienten mit chronisch-aktiver H…