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51.
52.
Vervoort R Lennon A Bird AC Tulloch B Axton R Miano MG Meindl A Meitinger T Ciccodicola A Wright AF 《Nature genetics》2000,25(4):462-466
The gene RPGR was previously identified in the RP3 region of Xp21.1 and shown to be mutated in 10-20% of patients with the progressive retinal degeneration X-linked retinitis pigmentosa (XLRP). The mutations predominantly affected a domain homologous to RCC1, a guanine nucleotide exchange factor for the small GTPase Ran, although they were present in fewer than the 70-75% of XLRP patients predicted from linkage studies. Mutations in the RP2 locus at Xp11.3 were found in a further 10-20% of XLRP patients, as predicted from linkage studies. Because the mutations in the remainder of the XLRP patients may reside in undiscovered exons of RPGR, we sequenced a 172-kb region containing the entire gene. Analysis of the sequence disclosed a new 3' terminal exon that was mutated in 60% of XLRP patients examined. This exon encodes 567 amino acids, with a repetitive domain rich in glutamic acid residues. The sequence is conserved in the mouse, bovine and Fugu rubripes genes. It is preferentially expressed in mouse and bovine retina, further supporting its importance for retinal function. Our results suggest that mutations in RPGR are the only cause of RP3 type XLRP and account for the disease in over 70% of XLRP patients and an estimated 11% of all retinitis pigmentosa patients. 相似文献
53.
Definition of cell fates along the dorso-ventral axis depends on an antagonistic relationship between ventralizing transforming growth factor-beta superfamily members, the bone morphogenetic proteins and factors secreted from the dorsal organizer, such as Noggin and Chordin. The extracellular binding of the last group to the bone morphogenetic proteins prevents them from activating their receptors, and the relative ventralizer:antagonist ratio is thought to specify different dorso-ventral cell fates. Here, by taking advantage of a non-genetic interference method using a specific competitive inhibitor, the Lefty-related gene product Antivin, we provide evidence that cell fate along the antero-posterior axis of the zebrafish embryo is controlled by the morphogenetic activity of another transforming growth factor-beta superfamily subgroup--the Activin and Nodal-related factors. Increasing antivin doses progressively deleted posterior fates within the ectoderm, eventually resulting in the removal of all fates except forebrain and eyes. In contrast, overexpression of activin or nodal-related factors converted ectoderm that was fated to be forebrain into more posterior ectodermal or mesendodermal fates. We propose that modulation of intercellular signalling by Antivin/Activin and Nodal-related factors provides a mechanism for the graded establishment of cell fates along the antero-posterior axis of the zebrafish embryo. 相似文献
54.
Pervasive density-dependent recruitment enhances seedling diversity in a tropical forest 总被引:2,自引:0,他引:2
Negative density-dependent recruitment of seedlings, that is, seeds of a given species are less likely to become established seedlings if the density of that species is high, has been proposed to be an important mechanism contributing to the extraordinary diversity of tropical tree communities because it can potentially prevent any particular species from usurping all available space, either in close proximity to seed sources or at relatively larger spatial scales. However, density-dependent recruitment does not necessarily enhance community diversity. Furthermore, although density-dependent effects have been found at some life stages in some species, no study has shown that density-dependent recruitment affects community diversity. Here we report the results of observations in a lowland, moist forest in the Republic of Panamá in which the species identities of 386,027 seeds that arrived at 200 seed traps were compared with the species identities of 13,068 seedlings that recruited into adjacent plots over a 4-year period. Across the 200 sites, recruit seedling diversity was significantly higher than seed diversity. Part of this difference was explained by interspecies differences in average recruitment success. Even after accounting for these differences, however, negative density-dependent recruitment contributes significantly to the increase in diversity from seeds to seedling recruits. 相似文献
55.
D. A. Wright M. J. Siciliano J. N. Baptist 《Cellular and molecular life sciences : CMLS》1972,28(8):888-889
Zusammenfassung Es wurden beiXiphophorus maculata undXiphophorus helleri zwei Isozyme von Glyceraldehyd-3-phosphat-Dehydrogenase nachgewiesen. Die biochemisch-genetischen U Untersuchungen deuten auf eine Tetrameren-Struktur. 相似文献
56.
57.
M. Slaytor J. N. Pennefather S. E. Wright 《Cellular and molecular life sciences : CMLS》1959,15(3):111-111
Zusammenfassung Vorläufige Untersuchungen über die Verwandlung von LSD und Ergometrin bei der Ratte zeigen, dass von beiden Substanzen zwei Hauptprodukte gewonnen werden. Beide Metaboliten von LSD antagonisieren 5-HT am isolierten Rattenuteruspräparat; es scheint sich um hydroxilierte und konjugierte Derivate des LSD zu handeln.
This work was supported by grants from Burroughs Wellcome, Aus. (M. S.) and Drug Houses of Australia (J. P.). 相似文献
This work was supported by grants from Burroughs Wellcome, Aus. (M. S.) and Drug Houses of Australia (J. P.). 相似文献
58.
Endothelial mitosis around aortic branches in normal guinea pigs 总被引:5,自引:0,他引:5
H P Wright 《Nature》1968,220(5162):78-79
59.
C M Dobson N J Hoyle C F Geraldes M Bruschi J LeGall P E Wright R J Williams 《Nature》1974,249(456):425-429
60.