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排序方式: 共有353条查询结果,搜索用时 15 毫秒
1.
Usdin K; Chevret P; Catzeflis FM; Verona R; Furano AV 《Molecular biology and evolution》1995,12(1):73-82
The single most difficult problem in phylogenetic analysis is deciding
whether a shared taxonomic character is due to common ancestry or one that
appeared independently due to convergence, parallelism, or reversion to an
ancestral state. Mammalian L1 retrotransposons undergo periodic
amplifications in which multiple copies of the elements are interspersed in
the genome. Because these elements apparently are transmitted only by
inheritance and are retained in the genome, a shared L1 amplification event
can only be an inherited ancestral character. We propose that L1
amplification events can be an excellent tool for analyzing mammalian
evolution and demonstrate here how we addressed several refractory problems
in rodent systematics using L1 DNA as a taxonomic character.
相似文献
2.
Cooling and lubrication agents like triethanolamine (TEA) are essential for many purposes in industry. Due to biodegradation, they need continuous replacement, and byproducts of degradation may be toxic. This study investigates an industrial (1,200 m³) cooling-lubrication circuit (CLC) that has been in operation for 20 years and is supposedly in an ecological equilibrium, thus offering a unique habitat. Next-generation (Illumina Miseq 16S rRNA amplicon) sequencing was used to profile the CLC-based microbiota and relate it to TEA and bicine dynamics at the sampling sites, influent, machine rooms, biofilms and effluent. Pseudomonas pseudoalcaligenes dominated the effluent and influent sites, while Alcaligenes faecalis dominated biofilms, and both species were identified as the major TEA degrading bacteria. It was shown that a 15 min heat treatment at 50°C was able to slow down the growth of both species, a promising option to control TEA degradation at large scale. 相似文献
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Patricia Geesink Carl-Eric Wegner Alexander J. Probst Martina Herrmann Hang T. Dam Anne-Kristin Kaster Kirsten Küsel 《Environmental microbiology》2020,22(2):726-737
Subsurface ecosystems like groundwater harbour diverse microbial communities, including small-sized, putatively symbiotic organisms of the Candidate Phyla Radiation, yet little is known about their ecological preferences and potential microbial partners. Here, we investigated a member of the superphylum Microgenomates (Cand. Roizmanbacterium ADI133) from oligotrophic groundwater using mini-metagenomics and monitored its spatio-temporal distribution using 16S rRNA gene analyses. A Roizmanbacteria-specific quantitative PCR assay allowed us to track its abundance over the course of 1 year within eight groundwater wells along a 5.4 km hillslope transect, where Roizmanbacteria reached maximum relative abundances of 2.3%. In-depth genomic analyses suggested that Cand. Roizmanbacterium ADI133 is a lactic acid fermenter, potentially able to utilize a range of complex carbon substrates, including cellulose. We hypothesize that it attaches to host cells using a trimeric autotransporter adhesin and inhibits their cell wall biosynthesis using a toxin–antitoxin system. Network analyses based on correlating Cand. Roizmanbacterium ADI133 abundances with amplicon sequencing-derived microbial community profiles suggested one potential host organism, classified as a member of the class Thermodesulfovibrionia (Nitrospirae). By providing lactate as an electron donor Cand. Roizmanbacterium ADI133 potentially mediates the transfer of carbon to other microorganisms and thereby is an important connector in the microbial community. 相似文献
8.
Melissa K. Boles Bonney M. Wilkinson Laurens G. Wilming Bin Liu Frank J. Probst Jennifer Harrow Darren Grafham Kathryn E. Hentges Lanette P. Woodward Andrea Maxwell Karen Mitchell Michael D. Risley Randy Johnson Karen Hirschi James R. Lupski Yosuke Funato Hiroaki Miki Pablo Marin-Garcia Lucy Matthews Alison J. Coffey Anne Parker Tim J. Hubbard Jane Rogers Allan Bradley David J. Adams Monica J. Justice 《PLoS genetics》2009,5(12)
An accurate and precisely annotated genome assembly is a fundamental requirement for functional genomic analysis. Here, the complete DNA sequence and gene annotation of mouse Chromosome 11 was used to test the efficacy of large-scale sequencing for mutation identification. We re-sequenced the 14,000 annotated exons and boundaries from over 900 genes in 41 recessive mutant mouse lines that were isolated in an N-ethyl-N-nitrosourea (ENU) mutation screen targeted to mouse Chromosome 11. Fifty-nine sequence variants were identified in 55 genes from 31 mutant lines. 39% of the lesions lie in coding sequences and create primarily missense mutations. The other 61% lie in noncoding regions, many of them in highly conserved sequences. A lesion in the perinatal lethal line l11Jus13 alters a consensus splice site of nucleoredoxin (Nxn), inserting 10 amino acids into the resulting protein. We conclude that point mutations can be accurately and sensitively recovered by large-scale sequencing, and that conserved noncoding regions should be included for disease mutation identification. Only seven of the candidate genes we report have been previously targeted by mutation in mice or rats, showing that despite ongoing efforts to functionally annotate genes in the mammalian genome, an enormous gap remains between phenotype and function. Our data show that the classical positional mapping approach of disease mutation identification can be extended to large target regions using high-throughput sequencing. 相似文献
9.
Wolfgang Nikolaus Probst Stefan Stoll Lars Peters Philipp Fischer Reiner Eckmann 《Hydrobiologia》2009,632(1):211-224
In Lake Constance, Eurasian bream Abramis brama (L.) spawn in very shallow littoral areas by the beginning of May. They attach their adhesive eggs to pebble and cobble substratum
at <40 cm depth. Increasing water levels before spawning inundate bare substratum to which bream eggs may attach better than
to deeper substratum covered by epilithon. Consequently, the water level increase prior to spawning should determine the amount
of pristine spawning substratum available to bream and thus influence their breeding success. In order to test this hypothesis,
the influence of hydrology and climate on the abundance of age-0 bream was combined with the results from field investigations
on the egg survival and abundance of age-0 bream. A strong positive correlation between the mean water level increase during
the spawning season of bream (April–May) and the abundance of juvenile bream was found. In contrast, the absolute water level
during spawning and during the nursery stage in summer, the cumulative temperature during the egg, larval and juvenile stages
and two North Atlantic Oscillation (NAO) indices did not affect the abundance of juvenile bream. The field investigations
confirmed that bream eggs attach better to and have higher survival rates on bare substratum than on substratum with epilithon
cover. Accordingly, eggs within a spawning habitat of bream were most abundant between 10 and 20 cm depth, where the epilithon
cover was lower than at depths exceeding 30 cm. The results of this study confirm an adverse influence of epilithon cover
on the attachment and subsequent survival of bream eggs and emphasize the importance of spring inundations for the successful
breeding of the bream.
Handling editor: J. A. Cambray 相似文献
10.
Rafael Luis Kessler Maurilio José Soares Christian Macagnan Probst Marco Aurélio Krieger 《PloS one》2013,8(1)
The protozoan parasite Trypanosoma cruzi displays similarities to fungi in terms of its sterol lipid biosynthesis, as ergosterol and other 24-alkylated sterols are its principal endogenous sterols. The sterol pathway is thus a potential drug target for the treatment of Chagas disease. We describe here a comparative study of the growth inhibition, ultrastructural and physiological changes leading to the death of T. cruzi cells following treatment with the sterol biosynthesis inhibitors (SBIs) ketoconazole and lovastatin. We first calculated the drug concentration inhibiting epimastigote growth by 50% (EC50/72 h) or killing all cells within 24 hours (EC100/24 h). Incubation with inhibitors at the EC50/72 h resulted in interesting morphological changes: intense proliferation of the inner mitochondrial membrane, which was corroborated by flow cytometry and confocal microscopy of the parasites stained with rhodamine 123, and strong swelling of the reservosomes, which was confirmed by acridine orange staining. These changes to the mitochondria and reservosomes may reflect the involvement of these organelles in ergosterol biosynthesis or the progressive autophagic process culminating in cell lysis after 6 to 7 days of treatment with SBIs at the EC50/72 h. By contrast, treatment with SBIs at the EC100/24 h resulted in rapid cell death with a necrotic phenotype: time-dependent cytosolic calcium overload, mitochondrial depolarization and reservosome membrane permeabilization (RMP), culminating in cell lysis after a few hours of drug exposure. We provide the first demonstration that RMP constitutes the “point of no return” in the cell death cascade, and propose a model for the necrotic cell death of T. cruzi. Thus, SBIs trigger cell death by different mechanisms, depending on the dose used, in T. cruzi. These findings shed new light on ergosterol biosynthesis and the mechanisms of programmed cell death in this ancient protozoan parasite. 相似文献