108 research outputs found
Hybridization and recurrent evolution of left–right reversal in the land snail genus Schileykula (Orculidae, Pulmonata)
Eyes in the dark.. Shedding light on the antlion phylogeny and the enigmatic genus Pseudimares Kimmins (Neuropterida: Neuroptera: Myrmeleontidae)
The systematic position of the antlion Pseudimares Kimmins has been disputed since description of the genus. Pseudimares is one of the
most enigmatic and unusual members of Myrmeleontidae and probably of all Neuroptera. The taxon has been usually tied to the antlion
subfamily Palparinae, although its phylogenetic affinities have never been thoroughly investigated and the monophyly of the subfamily as a
whole has never been corroborated. We reconstruct for the first time the phylogenetic affinities of Pseudimares based on both morphological and molecular genetic data. The widely accepted subfamily level subdivision of antlions (Stilbopteryginae, Palparinae, Myrmeleontinae) is refuted in all our analyses, since Stilbopteryginae in the traditional sense are recovered as deeply nested within Myrmeleontidae
forming a monophylum with Palparinae, while Myrmeleontinae are poorly supported by the parsimony analysis. In our morphology-based
parsimony analysis, Pseudimares is the sister taxon of Stilbopteryx and Aeropteryx, which makes the traditional Palparinae paraphyletic.
This result is further supported by our phylogenetic reconstruction based on molecular data, which found a clade including Pseudimares
and Stilbopteryx, which is nested within the traditional Palparinae. The high genetic distances measured among the analysed taxa suggest
that these groups quickly diverged in ancient times, although they remained morphologically homogeneous. In conformity with the results
of the phylogenetic analyses, we propose a new classification scheme for antlions, one that merges Stilbopteryx and Aeropteryx into an
expanded concept of the subfamily Palparinae
PCR diagnostics of Mycobacterium tuberculosis in historic human long bone remains from 18th century burials in Kaiserebersdorf, Austria
<p>Abstract</p> <p>Background</p> <p>In the present pilot study we applied recently published protocols for detecting <it>Mycobacterium tuberculosis </it>in human remains. We screened long bones from an 18<sup>th </sup>century cemetery and skulls from the anatomical "Weisbach collection" (19<sup>th </sup>century). In addition, besides the study of abundance of tuberculosis in inmates of the poorhouse itself, we were interested to test whether in this particular instance tuberculosis can be identified from cortical bones, which are rarely affected by tuberculosis, but mostly better preserved than the vertebral bodies or epiphyses.</p> <p>Method</p> <p>The DNA extractions from the bone samples were obtained following established ancient DNA protocols. Subsequently extracts were subjected to a series of PCR amplifications using primer pairs published previously <abbrgrp><abbr bid="B1">1</abbr><abbr bid="B2">2</abbr></abbrgrp>. PCR products of the expected size were subsequently sequenced.</p> <p>Results</p> <p>Only primers targeting the repetitive IS<it>6110 </it>insertion sequence yielded PCR products of appropriate size. In one sample only (skull sample WB354 of the "Weisbach collection") sequence analysis revealed an authentic <it>M. tuberculosis </it>sequence that matched to a reference sequence from GenBank.</p> <p>Conclusion</p> <p>With a variety of established PCR approaches we failed to detect <it>M. tuberculosis </it>DNA in historic human femurs from an 18<sup>th </sup>century cemetery relating to a poor house in Kaiserebersdorf, Austria. Our data may indicate that in this particular case, thoracic or lumbar vertebrae, i.e. bones that are severely affected by the disease, would be more suitable for molecular diagnostics than long bones. However, the unpredictable state of DNA preservation in bones from museum collections does not allow any general recommendation of any type of bone.</p
Tiny Bird, Huge Mystery - The Possibly Extinct Hooded Seedeater (Sporophila melanops) Is a Capuchino with a Melanistic Cap
Known with certainty solely from a unique male specimen collected in central Brazil in the first quarter of the 19th century, the Critically Endangered (Possibly Extinct) Hooded Seedeater Sporophila melanops has been one of the great enigmas of Neotropical ornithology, arguably the only one of a host of long-lost species from Brazil to remain obstinately undiscovered. We reanalysed the morphology of the type specimen, as well as a female specimen postulated to represent the same taxon, and sequenced mitochondrial DNA (COI and Cyt-b) from both individuals. Furthermore, we visited the type locality, at the border between Goiás and Mato Grosso, and its environs on multiple occasions at different seasons, searching for birds with similar morphology to the type, without success. Novel genetic and morphological evidence clearly demonstrates that the type of S. melanops is not closely related to Yellow-bellied Seedeater S. nigricollis, as has been frequently postulated in the literature, but is in fact a representative of one of the so-called capuchinos, a clade of attractively plumaged seedeaters that breed mostly in the Southern Cone of South America. Our morphological analysis indicates that S. melanops has a hitherto unreported dark-coffee throat and that it is probably a Dark-throated Seedeater S. ruficollis collected within its wintering range, acquiring breeding plumage and showing melanism on the cap feathers. Alternatively, it may be a melanistic-capped individual of a local population of seedeaters known to breed in the Esteros del Iberá, Corrientes, Argentina, to which the name S. ruficollis might be applicable, whilst the name S. plumbeiceps might be available for what is currently known as S. ruficollis. A hybrid origin for S. melanops cannot be ruled out from the available data, but seems unlikely. The purported female specimen of S. melanops pertains either to S. nigricollis or to Double-collared Seedeater S. caerulescens based on genetic and morphological data, and thus cannot be a female of S. melanops. We conclude that Sporophila melanops is not typical of any natural population of seedeaters, appears to have been collected far from its breeding grounds while overwintering in central Brazil, and should not be afforded any conservation status.Fil: Areta, Juan Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Bio y Geociencias del NOA. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Museo de Ciencias Naturales. Instituto de Bio y Geociencias del NOA; ArgentinaFil: Piacentini, Vítor de Q. Universidade de Sao Paulo; BrasilFil: Haring, Elisabeth. Universidad de Viena; AustriaFil: Gamauf, Anita. Universidad de Viena; AustriaFil: Silveira, Luís Fábio. Universidad de Viena; AustriaFil: Machado, Erika. Universidade de Sao Paulo; BrasilFil: Kirwan, Guy M.. The Field Museum; Estados Unido
Range‐constrained co‐occurrence simulation reveals little niche partitioning among rock‐dwelling Montenegrina land snails (Gastropoda: Clausiliidae)
Utility of arsenic-treated bird skins for DNA extraction
Background: Natural history museums receive a rapidly growing number of requests for tissue samples from preserved specimens for DNA-based studies. Traditionally, dried vertebrate specimens were treated with arsenic because of its toxicity and insect-repellent effect. Arsenic has negative effects on in vivo DNA repair enzymes and consequently may inhibit PCR performance. In bird collections, foot pad samples are often requested since the feet were not regularly treated with arsenic and because they are assumed to provide substantial amounts of DNA. However, the actual influence of arsenic on DNA analyses has never been tested. Findings: PCR success of both foot pad and body skin samples was significantly lower in arsenic-treated samples. In general, foot pads performed better than body skin samples. Moreover, PCR success depends on collection date in which younger samples yielded better results. While the addition of arsenic solution to the PCR mixture had a clear negative effect on PCR performance after the threshold of 5.4 μg/μl, such high doses of arsenic are highly unlikely to occur in dried zoological specimens. Conclusions: While lower PCR success in older samples might be due to age effects and/or DNA damage through arsenic treatment, our results show no inhibiting effect on DNA polymerase. We assume that DNA degradation proceeds more rapidly in thin tissue layers with low cell numbers that are susceptible to external abiotic influences. In contrast, in thicker parts of a specimen, such as foot pads, the outermost horny skin may act as an additional barrier. Since foot pads often performed better than body skin samples, the intention to preserve morphologically important structures of a specimen still conflicts with the aim to obtain optimal PCR success. Thus, body skin samples from recently collected specimens should be considered as alternative sources of DNA
Parent-of-origin-specific allelic associations among 106 genomic loci for age at menarche.
Age at menarche is a marker of timing of puberty in females. It varies widely between individuals, is a heritable trait and is associated with risks for obesity, type 2 diabetes, cardiovascular disease, breast cancer and all-cause mortality. Studies of rare human disorders of puberty and animal models point to a complex hypothalamic-pituitary-hormonal regulation, but the mechanisms that determine pubertal timing and underlie its links to disease risk remain unclear. Here, using genome-wide and custom-genotyping arrays in up to 182,416 women of European descent from 57 studies, we found robust evidence (P < 5 × 10(-8)) for 123 signals at 106 genomic loci associated with age at menarche. Many loci were associated with other pubertal traits in both sexes, and there was substantial overlap with genes implicated in body mass index and various diseases, including rare disorders of puberty. Menarche signals were enriched in imprinted regions, with three loci (DLK1-WDR25, MKRN3-MAGEL2 and KCNK9) demonstrating parent-of-origin-specific associations concordant with known parental expression patterns. Pathway analyses implicated nuclear hormone receptors, particularly retinoic acid and γ-aminobutyric acid-B2 receptor signalling, among novel mechanisms that regulate pubertal timing in humans. Our findings suggest a genetic architecture involving at least hundreds of common variants in the coordinated timing of the pubertal transition
New loci for body fat percentage reveal link between adiposity and cardiometabolic disease risk
To increase our understanding of the genetic basis of adiposity and its links to cardiometabolic disease risk, we conducted a genome-wide association meta-analysis of body fat percentage (BF%) in up to 100,716 individuals. Twelve loci reached genome-wide significance (P<5 × 10−8), of which eight were previously associated with increased overall adiposity (BMI, BF%) and four (in or near COBLL1/GRB14, IGF2BP1, PLA2G6, CRTC1) were novel associations with BF%. Seven loci showed a larger effect on BF% than on BMI, suggestive of a primary association with adiposity, while five loci showed larger effects on BMI than on BF%, suggesting association with both fat and lean mass. In particular, the loci more strongly associated with BF% showed distinct cross-phenotype association signatures with a range of cardiometabolic traits revealing new insights in the link between adiposity and disease risk
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