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141.
Ordean J. Oyen Robert W. Rice Donald H. Enlow 《American journal of physical anthropology》1981,54(3):415-419
An analysis of skulls from several primate species shows that a “worm-track” surface pattern, first identified in the brow region in fossil adult hominids and subsequently in olive baboons, chimpanzees, and macaques, is also present in numerous other species. Fine cancellous bone and its attendant vermiculate surface pattern have been observed in subadult and adult gelada baboons, gibbons, gorillas, and orangutans as well as in modern Homo sapiens and several Plio-Pleistocene fossil hominids. In contemporary primates, fine cancellous bone has been identified not only in the brow region, but also along the zygomatic arch, on the pterygoid plates, on the maxilla, along the temporal line, on the mastoid process, and in the region of inion. Given the widespread distribution of this trait, caution is advised when using it as a diagnostic indicator of the evolutionary or functional significance of craniofacial morphology. 相似文献
142.
Abstract: This paper reports on the electrophoretic protein/polypeptide pattern of a rat brain primary culture. For comparison, the polypeptide pattern of neuronal and glial enriched fractions from adult rat brain and cerebral hemispheres from newborn and adult rat have been analysed. Water-soluble and SDS-extractable polypeptide fractions appeared and/or increased in amount in the cultures until confluency. The polypeptide pattern of the cultures most resembled that of the glial cell fractions, showing some of this fraction's specificity. Removal of fetal calf serum and addition of 0.1 mM dibutyryl cyclic adenosine monophosphate (dB-cAMP) produced few changes in the electrophoretic pattern. The study thus provides evidence in favour of the astroglial nature of the brain primary culture. It also shows that the cells undergo some maturation in the culture. 相似文献
143.
A mass spectral fragmentation pattern of permethyl 6-C-glycosylflavones is proposed from the MS data of permethyl derivatives mono-O-deuteriomethylated in the 2″-, 3″-, 4″- or 6″-positions. The synthesis of these compounds via O″-glycosyl-6-C-glucosylflavones is described. 相似文献
144.
Addition of the arginine analogue, canavanine, to cultures of nitrogen-fixing Anabaena cylindrica at the onset of akinete formation, resulted in the development of akinetes randomly distributed within the filament, in addition to those adjacent to heterocysts. The total frequency of akinetes increased up to five-fold. A feature of akinetes is their increased content of cyanophycin granules (an arginine-aspartic acid polymer) and addition of canavanine to cultures at an earlier stage resulted in entire filaments becoming agranular and containing agranular akinetes. The effects on akinete pattern appeared to be specific for canavanine since other amino acid analogues, although increasing the frequency of akinetes (approximately two-fold), had no effect on their position relative to heterocysts. In ammonia-grown, stationary phase cultures of A. cylindrica, akinetes were observed adjacent to proheterocysts and in positions more than 20 cells from any heterocyst. These observations indicate that nitrogen fixation and heterocysts are not essential for akinete formation in A. cylindrica, although the availability of a source of fixed nitrogen does appear to be a requirement.These results suggest that during exponential growth some aspect of the physiology of vegetative cells suppresses their development into akinetes and that the role of the heterocyst may not be one of direct stimulation of adjacent vegetative cells to form akinetes, but the removal or negation of the inhibition within them. A model for akinete formation and the involvement of canavanine is given. 相似文献
145.
146.
Amino acids, salts, and vitamins were combined with dextrose to test their effect on growth and sporulation of Entomophthora virulenta in liquid shake culture. The addition of a vitamin solution to the tested media did not enhance growth or sporulation. MgSO4·7H2O was the only salt individually tested that allowed for good growth and sporulation. MgSO4·7H2O concentrations exceeding 250 mg/liter in media lacking other salts inhibited sporulation. A simple medium of l-arginine, l-leucine, glycine, and mineral salts allowed high growth and sporulation. 相似文献
147.
Characterization of an inhibitor of the intracellular protease from Bacillus subtilis. 总被引:4,自引:0,他引:4
A specific inhibitor of intracellular serylprotease from Bacillus subtilis has been isolated from both growing and sporulating cells. Like other protease inhibitors isolated from eukaryotic cells, the inhibitor from B. subtilis is a thermostable protein. A purification method is described. The molecular weight estimated by Biogel filtration and SDS gel electrophoresis is about 15,500. Both proteolytic and esterolytic activities of intracellular protease are equally sensitive to inhibition. With azocoll or Z-tyrosine p-nitrophenylester as substrates, noncompetitive inhibition patterns are observed. The inhibitor has no effect on the proteolytic or esterolytic activities of the extracellular serylprotease. A similar thermostable inhibitor is also present in Bacillus megaterium. 相似文献
148.
149.
Spatial patterns of the future elongation of cells exist in the early embroyo. In the newt, such a pattern of changers of cell shape contributes to the formation of the neural plate. Regardless of where neural plate. Regardless of where neural plte cells are transplanted, they change shape as prescribed by tge pattern. Embryonic induction has a role in establishing this pattern. 相似文献
150.
Beth Okamura 《Journal of experimental marine biology and ecology》1984,83(2):179-193
The effects of ambient flow velocity, colony size, and the presence of upstream colonies on the feeding success of the arborescent bryozoan, Bugula stolonifera (Ryland), were studied. Faster ambient flow velocities were found to reduce feeding of zooids of small colonies but not of large colonies. Zooids from different regions of colonies dominated in feeding at different ambient flow velocities: upstream zooids dominated in feeding from slow ambient flow: zooids from central regions dominated in feeding from fast ambient flow. These results are interpreted with respect to the branching morphology of colonies. Finally, evidence that upstream colonies interfere with the feeding success of zooids of colonies downstream was obtained. 相似文献