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151.
152.
Summary
Spirillum bengal is unable to grow on sugars, but can utilize different organic acids as carbon sources. Dehydrogenase activities were tested with different substrates and were found highest with lactate, glutamate, acetate, succinate and malate. A low aldolase activity was also detectable. 相似文献
153.
Zusammenfassung Bei verschiedenen Pflanzenarten werden die Variationen der Chromosomenzahlen im Vegetationspunkt des Stammes untersucht. Für Blattzellen ist eine konstante Zahl charakteristisch. Die Resultate weisen darauf hin, dass in der Wachstumsspitze spezifische Chromosomenzahlen in die einzelnen Organe übergehen und so die Differenzierung gesteuert wird. Die normale2n-Zahl kommt in den meisten Zellen vor. 相似文献
154.
155.
Summary The 2 phosphomonoesterases of the root-knot nematode were colorimetrically determined. Alkaline phosphatase activity was observed to be lower than the acid phosphatase activity. Sex related trends were clearly seen in the enzyme levels of the 2 sexes of thenematode. Alkaline phosphatase level differed 28.76%, while acid phosphatase level differed 60.36% in the 2 sexes.The authors are grateful to the Council of Science and Technology U.P. for the grant of a Research Scheme for these studies. 相似文献
156.
Tagliaferri G Goad M Chincarini G Moretti A Campana S Burrows DN Perri M Barthelmy SD Gehrels N Krimm H Sakamoto T Kumar P Mészáros PI Kobayashi S Zhang B Angelini L Banat P Beardmore AP Capalbi M Covino S Cusumano G Giommi P Godet O Hill JE Kennea JA Mangano V Morris DC Nousek JA O'Brien PT Osborne JP Pagani C Page KL Romano P Stella L Wells A 《Nature》2005,436(7053):985-988
'Long' gamma-ray bursts (GRBs) are commonly accepted to originate in the explosion of particularly massive stars, which give rise to highly relativistic jets. Inhomogeneities in the expanding flow result in internal shock waves that are believed to produce the gamma-rays we see. As the jet travels further outward into the surrounding circumstellar medium, 'external' shocks create the afterglow emission seen in the X-ray, optical and radio bands. Here we report observations of the early phases of the X-ray emission of five GRBs. Their X-ray light curves are characterised by a surprisingly rapid fall-off for the first few hundred seconds, followed by a less rapid decline lasting several hours. This steep decline, together with detailed spectral properties of two particular bursts, shows that violent shock interactions take place in the early jet outflows. 相似文献
157.
158.
BubR1 insufficiency causes early onset of aging-associated phenotypes and infertility in mice 总被引:17,自引:0,他引:17
Baker DJ Jeganathan KB Cameron JD Thompson M Juneja S Kopecka A Kumar R Jenkins RB de Groen PC Roche P van Deursen JM 《Nature genetics》2004,36(7):744-749
Faithful segregation of replicated chromosomes is essential for maintenance of genetic stability and seems to be monitored by several mitotic checkpoints. Various components of these checkpoints have been identified in mammals, but their physiological relevance is largely unknown. Here we show that mutant mice with low levels of the spindle assembly checkpoint protein BubR1 develop progressive aneuploidy along with a variety of progeroid features, including short lifespan, cachectic dwarfism, lordokyphosis, cataracts, loss of subcutaneous fat and impaired wound healing. Graded reduction of BubR1 expression in mouse embryonic fibroblasts causes increased aneuploidy and senescence. Male and female mutant mice have defects in meiotic chromosome segregation and are infertile. Natural aging of wild-type mice is marked by decreased expression of BubR1 in multiple tissues, including testis and ovary. These results suggest a role for BubR1 in regulating aging and infertility. 相似文献
159.
LMNA, encoding lamin A/C, is mutated in partial lipodystrophy 总被引:23,自引:0,他引:23
Shackleton S Lloyd DJ Jackson SN Evans R Niermeijer MF Singh BM Schmidt H Brabant G Kumar S Durrington PN Gregory S O'Rahilly S Trembath RC 《Nature genetics》2000,24(2):153-156
The lipodystrophies are a group of disorders characterized by the absence or reduction of subcutaneous adipose tissue. Partial lipodystrophy (PLD; MIM 151660) is an inherited condition in which a regional (trunk and limbs) loss of fat occurs during the peri-pubertal phase. Additionally, variable degrees of resistance to insulin action, together with a hyperlipidaemic state, may occur and simulate the metabolic features commonly associated with predisposition to atherosclerotic disease. The PLD locus has been mapped to chromosome 1q with no evidence of genetic heterogeneity. We, and others, have refined the location to a 5.3-cM interval between markers D1S305 and D1S1600 (refs 5, 6). Through a positional cloning approach we have identified five different missense mutations in LMNA among ten kindreds and three individuals with PLD. The protein product of LMNA is lamin A/C, which is a component of the nuclear envelope. Heterozygous mutations in LMNA have recently been identified in kindreds with the variant form of muscular dystrophy (MD) known as autosomal dominant Emery-Dreifuss MD (EDMD-AD; ref. 7) and dilated cardiomyopathy and conduction-system disease (CMD1A). As LMNA is ubiquitously expressed, the finding of site-specific amino acid substitutions in PLD, EDMD-AD and CMD1A reveals distinct functional domains of the lamin A/C protein required for the maintenance and integrity of different cell types. 相似文献
160.
An alternating combinatorial optimization approach to fitting the INDCLUS and generalized INDCLUS models 总被引:1,自引:1,他引:0
This paper presents a general approach for fitting the ADCLUS (Shepard and Arabie 1979; Arabie, Carroll, DeSarbo, and Wind 1981), INDCLUS (Carroll and Arabie 1983), and potentially a special case of the GENNCLUS (DeSarbo 1982) models. The proposed approach, based largely on a separability property observed for the least squares loss function being optimized, offers increased efficiency and other advantages over existing approaches like MAPCLUS (Arabie and Carroll 1980) for fitting the ADCLUS model, and the INDCLUS method for fitting the INDCLUS model. The new procedure (called SINDCLUS) is applied to three sets of empirical data to demonstrate the effectiveness of the SINDCLUS methodology. Finally, some potentially useful extensions are discussed. 相似文献