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21.
22.
MacArthur DG Seto JT Raftery JM Quinlan KG Huttley GA Hook JW Lemckert FA Kee AJ Edwards MR Berman Y Hardeman EC Gunning PW Easteal S Yang N North KN 《Nature genetics》2007,39(10):1261-1265
More than a billion humans worldwide are predicted to be completely deficient in the fast skeletal muscle fiber protein alpha-actinin-3 owing to homozygosity for a premature stop codon polymorphism, R577X, in the ACTN3 gene. The R577X polymorphism is associated with elite athlete status and human muscle performance, suggesting that alpha-actinin-3 deficiency influences the function of fast muscle fibers. Here we show that loss of alpha-actinin-3 expression in a knockout mouse model results in a shift in muscle metabolism toward the more efficient aerobic pathway and an increase in intrinsic endurance performance. In addition, we demonstrate that the genomic region surrounding the 577X null allele shows low levels of genetic variation and recombination in individuals of European and East Asian descent, consistent with strong, recent positive selection. We propose that the 577X allele has been positively selected in some human populations owing to its effect on skeletal muscle metabolism. 相似文献
23.
In 1987 the effects of arthropods on root:shoot ratios and biomass production were examined in southeastern Wyoming mountain shrub habitats that were undisturbed or had undergone conventional shrub management by mowing, burning, or herbicide application during the previous year. In habitats with and without shrub canopy, treatment with insecticides generally increased foliage biomass and consistently decreased root biomass, regardless of the shrub management practice. In open areas the effects of insecticide treatments on the root and shoot biomass were relatively greater in undisturbed plots than in any of the managed plots. With only one exception, the root:shoot ratio increased following application of insecticide. 相似文献
24.
Mutations in myosin heavy chain 11 cause a syndrome associating thoracic aortic aneurysm/aortic dissection and patent ductus arteriosus 总被引:1,自引:0,他引:1
Zhu L Vranckx R Khau Van Kien P Lalande A Boisset N Mathieu F Wegman M Glancy L Gasc JM Brunotte F Bruneval P Wolf JE Michel JB Jeunemaitre X 《Nature genetics》2006,38(3):343-349
We have recently described two kindreds presenting thoracic aortic aneurysm and/or aortic dissection (TAAD) and patent ductus arteriosus (PDA) and mapped the disease locus to 16p12.2-p13.13 (ref. 3). We now demonstrate that the disease is caused by mutations in the MYH11 gene affecting the C-terminal coiled-coil region of the smooth muscle myosin heavy chain, a specific contractile protein of smooth muscle cells (SMC). All individuals bearing the heterozygous mutations, even if asymptomatic, showed marked aortic stiffness. Examination of pathological aortas showed large areas of medial degeneration with very low SMC content. Abnormal immunological recognition of SM-MHC and the colocalization of wild-type and mutant rod proteins in SMC, in conjunction with differences in their coimmunoprecipitation capacities, strongly suggest a dominant-negative effect. Human MYH11 gene mutations provide the first example of a direct change in a specific SMC protein leading to an inherited arterial disease. 相似文献
25.
Mark C. Hove Bernard E. Sietman Matthew S. Berg Erika C. Frost Kiru Wolf Tony R. Brady 《Journal of Natural History》2016,50(9-10):523-542
Managing a rare species can be improved with knowledge of its natural history. The sheepnose (Plethobasus cyphyus) is a freshwater mussel recently listed by the US as federally endangered. We used standard methods to study P. cyphyus brooding behaviour, host fishes in the laboratory and under natural conditions, and glochidial morphology. We monitored a population of P. cyphyus in the Chippewa River, WI during spring and summer 2007–2009 and 2011 and found brooding animals between mid-May and early August. Gravid individuals ranged between 5 and 27 yr (mean age ± 1 s.d. = 13 ± 4 yr). Plethobasus cyphyus brooded glochidia in outer gills, which varied in colour from red, orange, pink, cream, or white. We observed mature glochidia more commonly in individuals with cream or white gills and these glochidia were released in a clear, adhesive, mucus matrix. In laboratory trials we found several minnow and topminnow species (29 spp.) served as productive suitable native hosts. The mean number of juvenile mussels released per cyprinid per day was significantly higher for trials conducted at 22–25°C compared with those at 18–20°C, and 83% of trials conducted at 18–20°C using suitable host species produced no juveniles. Glochidia had a unique outline and shell morphometrics that distinguished P. cyphyus from seven other Chippewa River mussel species that produce similar sized glochidia. Using morphometrics we determined that mimic shiners (Notropis volucellus) were natural hosts for P. cyphyus, round pigtoe (Pleurobema sintoxia), and Wabash pigtoe (Fusconaia flava). Releasing mucus-bound glochidia has evolved in a variety of mussel species and may be more common than is currently realized. Our data show that P. cyphyus is a cyprinid host specialist, and propagation efforts for this species can be strengthened through improved access to mature glochidia by using females with cream-coloured gills and increased juvenile production through warmer fish holding temperatures. 相似文献
26.
Superoxide activates mitochondrial uncoupling proteins. 总被引:64,自引:0,他引:64
Karim S Echtay Damien Roussel Julie St-Pierre Mika B Jekabsons Susana Cadenas Jeff A Stuart James A Harper Stephen J Roebuck Alastair Morrison Susan Pickering John C Clapham Martin D Brand 《Nature》2002,415(6867):96-99
Uncoupling protein 1 (UCP1) diverts energy from ATP synthesis to thermogenesis in the mitochondria of brown adipose tissue by catalysing a regulated leak of protons across the inner membrane. The functions of its homologues, UCP2 and UCP3, in other tissues are debated. UCP2 and UCP3 are present at much lower abundance than UCP1, and the uncoupling with which they are associated is not significantly thermogenic. Mild uncoupling would, however, decrease the mitochondrial production of reactive oxygen species, which are important mediators of oxidative damage. Here we show that superoxide increases mitochondrial proton conductance through effects on UCP1, UCP2 and UCP3. Superoxide-induced uncoupling requires fatty acids and is inhibited by purine nucleotides. It correlates with the tissue expression of UCPs, appears in mitochondria from yeast expressing UCP1, and is absent in skeletal muscle mitochondria from UCP3 knockout mice. Our findings indicate that the interaction of superoxide with UCPs may be a mechanism for decreasing the concentrations of reactive oxygen species inside mitochondria. 相似文献
27.
At the end of mitosis, daughter cells are separated from each other by cytokinesis. This process involves equal partitioning
and segregation of cytoplasm between the two cells. Despite years of study, the mechanism driving cytokinesis in animal cells
is not fully understood. Actin and myosin are major components of the contractile ring, the structure at the equator between
the dividing cells that provides the force necessary to constrict the cytoplasm. Despite this, there are also tantalizing
results suggesting that cytokinesis can occur in the absence of myosin. It is unclear what the roles are of the few other
contractile ring components identified to date. While it has been difficult to identify important proteins involved in cytokinesis,
it has been even more challenging to pinpoint the regulatory mechanisms that govern this vital process. Cytokinesis must be
precisely controlled both spatially and temporally; potential regulators of these parameters are just beginning to be identified.
This review discusses the recent progress in our understanding of cytokinesis in animal cells and the mechanisms that may
regulate it.
Received 24 August 1998; received after revision 9 October 1998; accepted 9 October 1998 相似文献
28.
Zusammenfassung Es wird gezeigt, dass Knochenentwicklung junger Ratten durch Behandlung mit Polyethylen-Polyphosphonat ohne toxische Wirkung verhindert wird. Die Polyphosphonate wirken direkt auf den Knochen und können eventuell verschiedene klinische Anwendungen finden.
Supported by Public Health Grant No. GM 17367-01. 相似文献
Supported by Public Health Grant No. GM 17367-01. 相似文献
29.
30.
N. Radoiu F. A. Zydeck E. T. Konno P. L. Wolf 《Cellular and molecular life sciences : CMLS》1968,24(11):1170-1171
Zusammenfassung Durch ein immunologisches Dreieck-System (Hund-Kaninchen-Hund) wurde ein Anti-Antikörper bei Hunden erzeugt und seine Wirkung in vitro und in vivo demonstriert. Die Anti-Antikörper-Methode bietet neue Möglichkeiten, dem Problem der Transplantat-Abstossung und der Therapie der Krankheiten immunologischen Ursprungs näherzukommen.
This investigation was supported by Public Health Service grant No. CA 02624 and the Detroit General Hospital Research Corp. and Metropolitan Hospital Research grant NO. 208-12. 相似文献
This investigation was supported by Public Health Service grant No. CA 02624 and the Detroit General Hospital Research Corp. and Metropolitan Hospital Research grant NO. 208-12. 相似文献