Search results for "Genome"

Suppression of oncogenic lethality by reintegration oflethal (2) giant larvae DNA sequence into thedrosophila genome

1986

Genome instability ofChironomus ripariusMg. andChironomus pigerStrenzke (Diptera, Chironomidae)

2007

Intra and interspecific variation was evaluated in two Bulgarian populations (Pancharevo and Koka- lijane) of the two sibling and homosequential species Chironomus riparius Mg. and Chironomus piger Strenzke, by analyzing structural and functional alterations in salivary gland polytene chromosomes. In both species genome in- stability was demonstrated, which was expressed by structural and functional somatic chromosomal alterations. In the C. riparius population from Pancharevo, living in sediments containing high concentrations of Cu, Pb and Zn, salivary gland cells containing somatic rearrangements appeared at a significantly higher frequency (51.92%) than in the Kokalijane C. piger popula…

Structural and functional characterization of a transcription-enhancing sequence element in the rbcL gene of the Chlamydomonas chloroplast genome.

2002

The structure and function of a transcription-enhancing sequence element in the coding region of the Chlamydomonas reinhardtii rbcL gene was analyzed in Chlamydomonas chloroplast transformants in vivo. The enhancer sequence is contained within a DNA segment extending from position +108 to position +143, relative to the start site of rbcL gene transcription. The sequence remains functional when inverted or when placed 34 bp closer to or 87 bp further downstream of the basic rbcL promoter. However, it does not function from a site about 250 bp downstream of its original location. Besides promoting transcription initiation from the rbcL promoter, the element is able to augment transcription fr…

Conventional karyotype, nucleolar organizer regions and genome size in five Mediterranean species of Syngnathidae (Pisces, Syngnathiformes)

1998

Conventional karyotypes, NOR-bearing chromosomes by means of silver impregnation and genome size were investigated in five Mediterranean species in three genera of the Syngnathidae. A karyotype of 48 subtelocentric-acrocentric chromosomes was found in the seahorse Hippocampus hippocampus (FN=48) while a diploid value of 44 occurred in H. guttulatus (2 sm-m+42 a; FN=46) and the pipefish Syngnathus abaster (44 a; FN=44) and S. typhle (44 a; FN=44). The pipefish Nerophis ophidion, possessing a diploid chromosomal set of 58 made up of 50 meta-submetacentric and eight subteloacrocentric elements (FN=108) and a genome size three to four times larger than those known to date, differs cytogenetical…

Evolution of small prokaryotic genomes

2015

As revealed by genome sequencing, the biology of prokaryotes with reduced genomes is strikingly diverse. These include free-living prokaryotes with ∼800 genes as well as endosymbiotic bacteria with as few as ∼140 genes. Comparative genomics is revealing the evolutionary mechanisms that led to these small genomes. In the case of free-living prokaryotes, natural selection directly favored genome reduction, while in the case of endosymbiotic prokaryotes neutral processes played a more prominent role. However, new experimental data suggest that selective processes may be at operation as well for endosymbiotic prokaryotes at least during the first stages of genome reduction. Endosymbiotic prokar…

Structural analyses of a hypothetical minimal metabolism

2007

By integrating data from comparative genomics and large-scale deletion studies, we previously proposed a minimal gene set comprising 206 protein-coding genes. To evaluate the consistency of the metabolism encoded by such a minimal genome, we have carried out a series of computational analyses. Firstly, the topology of the minimal metabolism was compared with that of the reconstructed networks from natural bacterial genomes. Secondly, the robustness of the metabolic network was evaluated by simulated mutagenesis and, finally, the stoichiometric consistency was assessed by automatically deriving the steady-state solutions from the reaction set. The results indicated that the proposed minimal …

Genetics in restless legs syndrome

2004

Several studies on Restless leas syndrome (RLS) have suggested a substantial genetic contribution in the etiology of this sleep disorder. Clinical surveys of idiopathic RLS patients have shown that up to 60% report a positive family history. Investigations of single families with RLS have suggested an autosomal dominant mode of inheritance with variable expressivity, and some families show possible anticipation. At present, only one twin study is available, showing a high concordance rate (83.3%) between identical twins. Despite several reports suggesting a genetic contribution to the etiology of idiopathic RLS, few molecular genetic studies have been carried out attempting to identify gene…

SARS-CoV-2 genome surveillance in Mainz, Germany, reveals convergent origin of the N501Y spike mutation in a hospital setting

2021

AbstractWhile establishing a regional SARS-Cov-2 variant surveillance by genome sequencing, we have identified three infected individuals in a clinical setting (two long-term hospitalized patients and a nurse) that shared the spike N501Y mutation within a genotype background distinct from the current viral variants of concern. We suggest that the adaptive N501Y mutation, known to increase SARS-CoV-2 transmissibility, arose by convergent evolution around December in Mainz, Germany. Hospitalized patients with a compromised immune system may be a potential source of novel viral variants, which calls for monitoring viral evolution by genome sequencing in clinical settings.

The impact of next-generation sequencing technology on preimplantation genetic diagnosis and screening.

2013

Largely because of efforts required to complete the Human Genome Project, DNA sequencing has undergone a steady transformation with still-ongoing developments of high-throughput sequencing machines for which the cost per reaction is falling drastically. Similarly, the fast-changing landscape of reproductive technologies has been improved by genetic approaches. Preimplantation genetic diagnosis and screening were established more than two decades ago for selecting genetically normal embryos to avoid inherited diseases and to give the highest potential to achieve stable pregnancies. Most recent additions to the IVF practices (blastocyst/trophectoderm biopsy, embryo vitrification) and adoption…

Chicken orthologues of mammalian imprinted genes are clustered on macrochromosomes and replicate asynchronously.

2005

In the chicken genome, most orthologues of mouse imprinted genes are clustered on macrochromosomes. Only a few orthologues are located in the microchromosome complement. Macrochromosomal and, to a lesser extent, microchromosomal regions containing imprinted gene orthologues exhibit asynchronous DNA replication. We conclude that highly conserved arrays of imprinted gene orthologues were selected during vertebrate evolution, long before these genes were recruited for parent-specific gene expression by genomic imprinting mechanisms. Evidently, the macrochromosome complement provides a better chromatin environment for the establishment of asynchronous DNA replication and imprinted gene expressi…