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121.
Survey of Malassezia sp and dermatophytes in the cutaneous microbiome of free‐ranging golden‐headed lion tamarins (Leontopithecus chrysomelas ‐ Kuhl, 1820) 下载免费PDF全文
122.
Selective DNA pooling is an efficient method to identify chromosomal regions that harbor quantitative trait loci (QTL) by comparing marker allele frequencies in pooled DNA from phenotypically extreme individuals. Currently used single marker analysis methods can detect linkage of markers to a QTL but do not provide separate estimates of QTL position and effect, nor do they utilize the joint information from multiple markers. In this study, two interval mapping methods for analysis of selective DNA pooling data were developed and evaluated. One was based on least squares regression (LS-pool) and the other on approximate maximum likelihood (ML-pool). Both methods simultaneously utilize information from multiple markers and multiple families and can be applied to different family structures (half-sib, F2 cross and backcross). The results from these two interval mapping methods were compared with results from single marker analysis by simulation. The results indicate that both LS-pool and ML-pool provided greater power to detect the QTL than single marker analysis. They also provide separate estimates of QTL location and effect. With large family sizes, both LS-pool and ML-pool provided similar power and estimates of QTL location and effect as selective genotyping. With small family sizes, however, the LS-pool method resulted in severely biased estimates of QTL location for distal QTL but this bias was reduced with the ML-pool. 相似文献
123.
Conservation of alternative splicing and genomic organization of the myosin alkali light-chain (Mlc1) gene among Drosophila species 总被引:3,自引:0,他引:3
The Mlc1 gene of Drosophila melanogaster encodes two MLC1 isoforms via
developmentally regulated alternative pre-mRNA splicing. In larval muscle
and tubular and abdominal muscles of adults, all of the six exons are
included in the spliced mRNA, whereas, in the fibrillar indirect flight
muscle of adult, exon 5 is excluded from the mRNA. We show that this
tissue-specific pattern of alternative splicing of the Mlc1 pre-mRNA is
conserved in D. simulans, D. pseudoobscura, and D. virilis. Isolation and
sequencing of the Mlc1 genes from these three other Drosophila species have
revealed that the overall organization of the genes is identical and that
the genes have maintained a very high level of sequence identity within the
coding region. Pairwise amino acid identities are 94%-99%, and there are no
charge changes among the proteins. Total nucleotide divergence within the
coding region of the four genes supports the accepted genealogy of these
species, but the data indicate a significantly higher rate of amino acid
replacement in the branch leading to D. pseudoobscura. A comparison of
nucleotide substitutions in the coding portions of exon 5 and exon 6, which
encode the alternative carboxyl termini of the two MLC1 isoforms, suggests
that exon 5 is subject to greater evolutionary constraints than is exon 6.
In addition to the coding sequences, there is significant sequence
conservation within the 5' and 3' noncoding DNA and two of the introns,
including one that flanks exon 5. These regions are candidates for cis-
regulatory elements. Our results suggest that evolutionary constraints are
acting on both the coding and noncoding sequences of the Mlc1 gene to
maintain proper expression and function of the two MLC1 polypeptides.
相似文献
124.
Talita?FA?Ribas Luis?RR?Rodrigues Cleusa?Y?Nagamachi Anderson?JB?Gomes Thayse?CM?Benathar Patricia?CM?O’Brien Fengtang?Yang Malcolm?A?Ferguson-Smith Julio?C?PieczarkaEmail author 《BMC genetics》2013,14(1):119
Background
The genus Micronycteris is a diverse group of phyllostomid bats currently comprising 11 species, with diploid number (2n) ranging from 26 to 40 chromosomes. The karyotypic relationships within Micronycteris and between Micronycteris and other phyllostomids remain poorly understood. The karyotype of Micronycteris hirsuta is of particular interest: three different diploid numbers were reported for this species in South and Central Americas with 2n?=?26, 28 and 30 chromosomes. Although current evidence suggests some geographic differentiation among populations of M. hirsuta based on chromosomal, morphological, and nuclear and mitochondrial DNA markers, the recognition of new species or subspecies has been avoided due to the need for additional data, mainly chromosomal data.Results
We describe two new cytotypes for Micronycteris hirsuta (MHI) (2n?=?26 and 25, NF?=?32), whose differences in diploid number are interpreted as the products of Robertsonian rearrangements. C-banding revealed a small amount of constitutive heterochromatin at the centromere and the NOR was located in the interstitial portion of the short arm of a second pair, confirmed by FISH. Telomeric probes hybridized to the centromeric regions and weakly to telomeric regions of most chromosomes. The G-banding analysis and chromosome painting with whole chromosome probes from Carollia brevicauda (CBR) and Phyllostomus hastatus (PHA) enabled the establishment of genome-wide homologies between MHI, CBR and PHA.Conclusions
The karyotypes of Brazilian specimens of Micronycteris hirsuta described here are new to Micronycteris and reinforce that M. hirsuta does not represent a monotypic taxon. Our results corroborate the hypothesis of karyotypic megaevolution within Micronycteris, and strong evidence for this is that the entire chromosome complement of M. hirsuta was shown to be derivative with respect to species compared in this study.125.
Sebastian A Baldauf Theo CM Bakker Fabian Herder Harald Kullmann Timo Thünken 《BMC evolutionary biology》2010,10(1):301
Background
Studies addressing the adaptive significance of female ornamentation have gained ground recently. However, the expression of female ornaments in relation to body size, known as trait allometry, still remains unexplored. Here, we investigated the allometry of a conspicuous female ornament in Pelvicachromis taeniatus, a biparental cichlid that shows mutual mate choice and ornamentation. Females feature an eye-catching pelvic fin greatly differing from that of males. 相似文献126.
Jonathan?CM?Clark Stuart?J?Galloway Stephen?M?Schlicht Ross?PV?McKellar Peter?FM?ChoongEmail author 《International Seminars in Surgical Oncology : ISSO》2009,6(1):15
Myoepitheliomas of the extremity are rare and usually benign, while a minority display malignant features. This case demonstrates the diagnosis and management of myoepithelioma within the carpal tunnel. Clinical and radiological tumour features were evaluated. Hematoxylin and eosin stained tumour sections were examined, and immunohistochemistry was performed. Histology revealed a nodular mass of epithelioid cells in clusters within a myxoid/chondroid stroma. No mitoses were noted. Cytokeratins, neuron-specific enolase, synaptophysin, glial fibrillary acidic protein, and S100 were positive on immunohistochemistry. A literature review revealed very few prior reports of myoepithelioma in the wrist, and limited data concerning any relationship between recurrence and quality of surgical margins. In this case, wide local excision would have significantly compromised dominant hand function, and therefore a marginal excision was deemed appropriate in the context of bland histological features. Surgical margins noted in future case reports will aid clinical decision making. 相似文献
127.
128.
An extract from rat brain has been shown to catalyze the transfer of ganglioside GM1 from sonicated vesicles to erythrocyte ghosts. It also enhanced the transfer of GM1 to a crude neuronal membrane preparation, whereas myelin took up only a very limited amount. The transfer activity was heat-labile. Similar transfer activities were found in extracts from bovine gray and white matter, that of the former being comparable to rat brain whereas the latter was greater per milligram protein. 相似文献
129.
The mutation rates of di-, tri- and tetranucleotide repeats in Drosophila melanogaster 总被引:3,自引:1,他引:3
Schug MD; Hutter CM; Wetterstrand KA; Gaudette MS; Mackay TF; Aquadro CF 《Molecular biology and evolution》1998,15(12):1751-1760
In a recent study, we reported that the combined average mutation rate of
10 di-, 6 tri-, and 8 tetranucleotide repeats in Drosophila melanogaster
was 6.3 x 10(-6) mutations per locus per generation, a rate substantially
below that of microsatellite repeat units in mammals studied to date (range
= 10(-2)-10(-5) per locus per generation). To obtain a more precise
estimate of mutation rate for dinucleotide repeat motifs alone, we assayed
39 new dinucleotide repeat microsatellite loci in the mutation accumulation
lines from our earlier study. Our estimate of mutation rate for a total of
49 dinucleotide repeats is 9.3 x 10(-6) per locus per generation, only
slightly higher than the estimate from our earlier study. We also estimated
the relative difference in microsatellite mutation rate among di-, tri-,
and tetranucleotide repeats in the genome of D. melanogaster using a method
based on population variation, and we found that tri- and tetranucleotide
repeats mutate at rates 6.4 and 8.4 times slower than that of dinucleotide
repeats, respectively. The slower mutation rates of tri- and
tetranucleotide repeats appear to be associated with a relatively short
repeat unit length of these repeat motifs in the genome of D. melanogaster.
A positive correlation between repeat unit length and allelic variation
suggests that mutation rate increases as the repeat unit lengths of
microsatellites increase.
相似文献
130.