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191.
Jesse M. Meik Sarah Schaack Oscar Flores-Villela Jeffrey W. Streicher 《Journal of Natural History》2018,52(13-16):989-1016
ABSTRACTWe describe two diminutive species of rattlesnakes (genus Crotalus) from small nearshore islands off the coast of Baja California in the western Gulf of California, Mexico. In order to test the hypothesis that some island populations represent cohesive species entities, we applied linear discriminant analysis and uniform validation procedures to multiple classes of intrinsic trait data. By using previously recognised species to establish a threshold for species recognition, we found that assignment of specimens to either new species was as probable as with other established rattlesnake species within the speckled rattlesnake (Crotalus mitchellii) complex. We also found that assignment of specimens from other island populations was not as probable as for the established species, and these populations are referable to C. pyrrhus. The species endemic to Piojo Island is most closely related to other island and mainland populations of C. pyrrhus whereas the species endemic to Cabeza de Caballo Island is apparently most closely related to C. angelensis, a nearby island endemic of large body size. However, patterns from both mitochondrial and nuclear phylogenies, and phenotypic variation, indicate that evolutionary trajectories of both of these species have been influenced by introgression from C. angelensis. We speculate that collective evidence based on contrasting patterns of nuclear and mitochondrial evolution supports a hybrid origin of the species from Cabeza de Caballo Island followed by exceptionally rapid mitochondrial evolution. Consistent with small body size, both species show a reduction in various scale counts relative to other species of the C. mitchellii species complex, suggesting that dwarfism is not simply a plastic response to insular conditions.http://www.zoobank.org/urn.lsid:zoobank.org:pub:FBC8A11B-04A3-4231-85CA-3972DF5A42FF 相似文献
192.
Z. Campos F. Muniz A. L. J Desbiez W. E. Magnusson 《Journal of Natural History》2016,50(25-26):1543-1548
Nests of Schneider’s dwarf caiman, Paleosuchus trigonatus, were located in the forests around three streams that drain into the Xingu River, Brazilian Amazonia, in October 2014. Camera traps were installed at the edge of four nests to document predators and female parental care. At two nests, females unsuccessfully defended their nests against one or more giant armadillos, Priodontes maximus, and nine-banded armadillos, Dasypus novemcinctus. Both armadillo species responded to the attack by fleeing and returning on the opposite side of the nest by going around the tree under which the nest was located. Giant armadillos have never before been recorded consuming caiman eggs and their diet has been described as consisting mostly of ants and termites. Another species of armadillo, Cabassous unicinctus, was also registered digging into a nest and probably consuming eggs, though it is generally considered to be primarily insectivorous. A tayra (Eira barbara), lizard (Tupinambis teguixin) and coati (Nasua nasua) were also registered taking eggs from nests during the day, but we obtained no registers of nest defence by caimans during the day. The three nests were attacked after 60 days of incubation, when the eggs were well developed. 相似文献
193.
Common loss-of-function variants of the epidermal barrier protein filaggrin are a major predisposing factor for atopic dermatitis 总被引:21,自引:0,他引:21
Palmer CN Irvine AD Terron-Kwiatkowski A Zhao Y Liao H Lee SP Goudie DR Sandilands A Campbell LE Smith FJ O'Regan GM Watson RM Cecil JE Bale SJ Compton JG DiGiovanna JJ Fleckman P Lewis-Jones S Arseculeratne G Sergeant A Munro CS El Houate B McElreavey K Halkjaer LB Bisgaard H Mukhopadhyay S McLean WH 《Nature genetics》2006,38(4):441-446
Atopic disease, including atopic dermatitis (eczema), allergy and asthma, has increased in frequency in recent decades and now affects approximately 20% of the population in the developed world. Twin and family studies have shown that predisposition to atopic disease is highly heritable. Although most genetic studies have focused on immunological mechanisms, a primary epithelial barrier defect has been anticipated. Filaggrin is a key protein that facilitates terminal differentiation of the epidermis and formation of the skin barrier. Here we show that two independent loss-of-function genetic variants (R510X and 2282del4) in the gene encoding filaggrin (FLG) are very strong predisposing factors for atopic dermatitis. These variants are carried by approximately 9% of people of European origin. These variants also show highly significant association with asthma occurring in the context of atopic dermatitis. This work establishes a key role for impaired skin barrier function in the development of atopic disease. 相似文献
194.
195.
Chan TL Yuen ST Kong CK Chan YW Chan AS Ng WF Tsui WY Lo MW Tam WY Li VS Leung SY 《Nature genetics》2006,38(10):1178-1183
Epimutations in the germline, such as methylation of the MLH1 gene, may contribute to hereditary cancer syndrome in human, but their transmission to offspring has never been documented. Here we report a family with inheritance, in three successive generations, of germline allele-specific and mosaic hypermethylation of the MSH2 gene, without evidence of DNA mismatch repair gene mutation. Three siblings carrying the germline methylation developed early-onset colorectal or endometrial cancers, all with microsatellite instability and MSH2 protein loss. Clonal bisulfite sequencing and pyrosequencing showed different methylation levels in different somatic tissues, with the highest level recorded in rectal mucosa and colon cancer tissue, and the lowest in blood leukocytes. This mosaic state of germline methylation with different tissue distribution could act as the first hit and provide a mechanism for genetic disease inheritance that may deviate from the mendelian pattern and be overlooked in conventional leukocyte-based genetic diagnosis strategy. 相似文献
196.
Foser S Redwanz I Ebeling M Heizmann CW Certa U 《Cellular and molecular life sciences : CMLS》2006,63(19-20):2387-2396
A hallmark of resistance to type I interferons (IFNs) is the lack of antiproliferative responses. We show here that costimulation with IFN-alpha and transforming growth factor beta-1 (TGF-beta) potentiates antiproliferative activity in a sensitive (ME15) and resistant (D10) human melanoma cell line. A DNA microarray-based search for proliferation control genes involved that are cooperatively activated by IFN-alpha and TGF-beta, yielded 28 genes. Among these are the insulin-like growth factor-binding protein 3 (IGFBP3) and the calcium-binding protein S100A2; we demonstrate, that recombinant IGFBP3 protein is a potent growth inhibitor requiring TGF-beta activity. The antiproliferative activity of S100A2 is significantly enhanced by IFN-alpha in stably transfected ME15 or D10 cell lines. We show for the first time that IFN-alpha is a potent inducer of intracellular calcium release required for activation of S100A2. Our study provides a functional link between IFN-alpha and TGF-beta signaling and extends the function of IFN signaling to calcium-sensitive processes. 相似文献
197.
Kraytsberg Y Kudryavtseva E McKee AC Geula C Kowall NW Khrapko K 《Nature genetics》2006,38(5):518-520
Using a novel single-molecule PCR approach to quantify the total burden of mitochondrial DNA (mtDNA) molecules with deletions, we show that a high proportion of individual pigmented neurons in the aged human substantia nigra contain very high levels of mtDNA deletions. Molecules with deletions are largely clonal within each neuron; that is, they originate from a single deleted mtDNA molecule that has expanded clonally. The fraction of mtDNA deletions is significantly higher in cytochrome c oxidase (COX)-deficient neurons than in COX-positive neurons, suggesting that mtDNA deletions may be directly responsible for impaired cellular respiration. 相似文献
198.
Scorpio A Blank TE Day WA Chabot DJ 《Cellular and molecular life sciences : CMLS》2006,63(19-20):2237-2248
Anthrax has been a major cause of death in grazing animals and an occasional cause of death in humans for thousands of years. Since the late 1800s there has been an exceptional international history of anthrax vaccine development. Due to animal vaccinations, the rate of infection has dropped dramatically. Anthrax vaccines have progressed from uncharacterized whole-cell vaccines in 1881, to pXO2-negative spores in the 1930s, to culture filtrates absorbed to aluminum hydroxide in 1970, and likely to recombinant protective antigen in the near future. Each of these refinements has increased safety without significant loss of efficacy. The threat of genetically engineered, antibiotic and vaccine resistant strains of Bacillus anthracis is fueling hypothesis-driven research and global techniques--including genomics, proteomics and transposon site hybridization--to facilitate the discovery of novel vaccine targets. This review highlights historical achievements and new developments in anthrax vaccine research. 相似文献
199.
200.
Molecular and Cellular Basis of Regeneration and Tissue Repair 总被引:2,自引:0,他引:2
The Xenopus tadpole is a favourable organism for regeneration research because it is suitable for a wide range of micromanipulative procedures and for a wide range of transgenic methods. Combination of these techniques enables genes to be activated or inhibited at specific times and in specific tissue types to a much higher degree than in any other organism capable of regeneration. Regenerating systems include the tail, the limb buds and the lens. The study of tail regeneration has shown that each tissue type supplies the cells for its own replacement: there is no detectable de-differentiation or metaplasia. Signalling systems needed for regeneration include the BMP and Notch signalling pathways, and perhaps also the Wnt and FGF pathways. The limb buds will regenerate completely at early stages, but not once they are fully differentiated. This provides a good opportunity to study the loss of regenerative ability using transgenic methods. 相似文献