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61.
Walter W. Ferguson 《Primates; journal of primatology》1989,30(3):383-387
A partial mandible with two molars intact was recovered between 1981 and 1984 from deposits of the Middle Pliocene at Tabarin,
in Kenya. It has been described and assigned toAustralopithecus cf.afarensis
Johanson, White, andCoppens, 1978, with the condition that if ‘A. afarensis’ is revised, then the attribution may change. The taxon ‘A. afarensis’ was found to be invalid and was revised. The smaller specimens of ‘A. afarensis,’ to which the Tabarin mandible was said to be similar, were redescribed asHomo antiquus
Ferguson, 1984. Since the Tabarin mandible andH. antiquus are successive transients of the same gens and are allopatric, the Tabarin hominid population is described as an earlier
chronosubspecies,Homo antiquus praegens ssp. n. 相似文献
62.
Cecilia PC Soh Alastair SR Donald James Feeney Walter TJ Morgan Winifred M Watkins 《Glycoconjugate journal》1989,6(3):319-332
The tetrasaccharides GalNAcß1-4[NeuAc2-3]Galß1-4Glc and GalNAcß1-4[NeuAc2-3]Galß1-4GlcNAc were synthesised by enzymic transfer of GalNAc from UDP-GalNAc to 3-sialyllactose (NeuAc2-3Galß1-4Glc) and 3-sialyl-N-acetyllactosamine (NeuAc2-3Galß1-4GlcNAc). The structures of the products were established by methylation and1H-500 MHz NMR spectroscopy. In Sda serological tests the product formed with 3-sialyl-N-acetyllactosamine was highly active whereas that formed with 3-sialyllactose had only weak activity. 相似文献
63.
Elizabeth Knyihár-Csillik Pasko Rakic Prof. Dr. Bert Csillik 《Cell and tissue research》1989,258(3):515-525
Summary Transection of the sciatic nerve in Rhesus monkeys and the consequent transganglionic degenerative atrophy (TDA) of central terminals of primary afferents result in transneuronal degeneration of substantia gelatinosa (SG) cells. Severe degeneration is characterized by an increased electron density of the nucleus and by conspicuous shrinkage of the cytoplasm, mitochondrial swelling, dilation of cisterns of the rough-surfaced endoplasmic reticulum, accumulation of free ribosomes and an electron-dense material in the cytoplasm. In the mild form, dilation of cisternal elements of the endoplasmic reticulum, swollen mitochondria and accumulation of free ribosomes takes place. About 10% of SG cells in segment L5 undergo the severe form whereas the rest shows signs of the mild form. Cytoplasmic alterations that occur during transneuronal degeneration seem to start at the level of subsurface cisterns. Dendrites and axons of transneuronally degenerating SG cells also show a conspicuous electron density. By analyzing the synaptic relationships of such darkened dendrites, connections in the upper dorsal horn can be deciphered. Modular units of the primary nociceptive analyzer that evaluate noxious and innocuous inputs on the basis of thin versus thick (AC/A) afferent activity and subjecting them to descending control appear to be recruited from structurally dispersed elements of synaptic glomeruli. These are arranged alongside dendritic processes of large antenna cells which relay impulses to projection cells of the spinothalamic tract. 相似文献
64.
Citrobacter freundii, Paracoccus denitrificans and Pseudomonas stutzeri were grown either singly or in mixed culture in anaerobic nitrate or nitrite limited chemostats with formate and/or succinate as electron donors and carbon sources. C. freundii reduced nitrate or nitrite stoichiometrically to ammonia. Maximum molar growth yields for nitrate (nitrite) were 15.3 (9.9) g/mol for C. freundii on formate with succinate as carbon source, 15.3 (9.5) g/mol for Ps. stutzeri on succinate and 32.3 (20.4) g/mol for Pa. denitrificans on succinate. The almost identical growth yields indicate that the ATP output of the anaerobic processes in the nitrate (nitrite) ammonifying organism and Ps. stutzeri are nearly the same. In mixed cultures with either Ps. stutzeri or Pa. denitrificans, C. freundii was the best competitor for nitrate. These results show that in anaerobic environments C. freundii may compete successfully with denitrifying organisms. 相似文献
65.
Pedro J. N. Silva Richard K. Koehn Walter J. Diehl III Robin P. Ertl Elaine B. Winshell Mauro Santos 《Biochemical genetics》1989,27(7-8):451-467
Four samples of the musselMytilus edulis were taken between 1984 and 1987 from Stony Brook, New York, and used to study the glucose-6-phosphate isomerase (GPI) polymorphism
in this species.In vitro specific activity andin vivo flux measured in the same animals were found to be significantly correlated. A significant effect of GPI genotype on flux
was observed in one of the samples; overall, significant evidence of effect of genotype on enzyme activity was also obtained.
GPI activities of common genotypes tend to deviate less from the population mean than those of rare (frequency less than 5%)
genotypes. This suggests the possibility that rare GPI genotypes are rare as a consequence of having biochemical properties
that deviate from an optimum level and, therefore, having a lower fitness. In support of this hypothesis, we found in one
of our samples that shell length is a concave function of GPI activity with an intermediate optimum activity level.
The financial support provided to P.J.N.S. by the Luso-American Educational Commission (Fulbright Program), the Instituto
Nacional de Investigacao Científica (Portugal), and the Faculdade de Ciências da Universidade de Lisboa during several stages
of this research is gratefully acknowledged. Financial support from the Ministerio de Educatión y Ciencia (Spain) in the form
of a postdoctoral Fulbright/MEC fellowship to M.S. is also gratefully acknowledged. Research was supported by National Science
Foundation Grant BSR-8415060 to R.K.K. This is contribution No. 736 from the Program in Ecology and Evolution, State University
of New York at Stony Brook.
On leave from Departamento de Biologia Vegetal, Faculdade de Ciências, Universidade de Lisboa, Campo Grande C2, Lisboa, Portugal. 相似文献
66.
Walter L. Davis James L. Matthews K. Shibata M. Kipnis G. R. Farmer Elma Cortinas John C. Meiyr D. B. P. Goodman 《The Histochemical journal》1989,21(4):194-202
Summary Both light microscopical and electron microscopical immunocytochemical techniques were utilized to localize CuZnsuperoxide dismutase (SOD) in the duodenum of normal, rachitic and vitamin-D3-replete chicks. This enzyme catalyses the dismutation of the superoxide anion, a toxic free radical generated during the normal aerobic metabolism of most respiring cells. Light microscopy showed no SOD activity associated with the duodenal enterocytes of normal and rachitic chicks. However, in rachitic animals subsequently treated with vitamin D, i.e. vitamin-D-replete chicks, intense immunoreactivity for the enzyme was seen in association with the apical border of the duodenal absorptive cells. Immunostaining for SOD was not seen in goblet cells. With electron microscopy, immunostaining for SOD activity was identified in association with the apical microvilli and, to a lesser degree, with the terminal web, a well as in association with both lysosomes and peroxisomes. From this report it appears that there is a physiological relationship between vitamin D, SOD and the intestinal absorptive cell. However, the precise relationship must await further clarification. 相似文献
67.
Lampert Winfried Fleckner Walter Pott Eckart Schober Ursula Störkel Karl-Ulrich 《Hydrobiologia》1989,(1):415-424
Bioassays of different complexity were compared with respect to their capability to predict the environmental impact of the herbicide atrazine in aquatic systems. Acute toxicity tests with Daphnia did not yield meaningful results. Sublethal tests with Daphnia (feeding inhibition, reduction of growth and reproduction) were more sensitive, but effective concentrations of atrazine were still rather high (2 mg/L). A relatively complicated artificial food chain system that incorporated direct and indirect effects on Daphnia yielded significant reduction of daphnid population growth at 0.1 mg/L. Enclosure experiments with natural communities were by far the most sensitive tools. Community responses could be measured at concentrations as low as 1 µg/L and 0.1 µg atrazine/L. At the lowest concentration, however, communities recovered after three weeks. We conclude that in complex systems indirect effects can be more important than direct effects, so that, contrary to the conditions in simple tests, non-target organisms may be the better indicators of herbicide stress to natural communities. 相似文献
68.
Walter A. Heidmann Annegret Büthe Martin Beyerbach Reinhard Löhmer und Harald A. Rüssel-Sinn 《Journal of Ornithology》1989,130(3):311-320
Zusammenfassung Rückstände chlorierter Kohlenwasserstoffe in Eiern und Lebern von im Binnenland Niedersachsens brütenden Vogelarten — Feldsperling, Mehlschwalbe, Weißstorch, Graureiher, Saatkrähe, Stockente und andere Arten — werden angegeben und deren Abhängigkeit von Brutort, Nahrung und Zugverhalten diskutiert.
Chlorinated hydrocarbons of some bird species breeding in the inland of Lower Saxony (FRG)
Summary Residues of chlorinated hydrocarbons in eggs and livers of some bird species — Tree Sparrow, House Martin, White Stork, Heron, Rook, Mallard, and further species — are presented. The dependence on place of breeding, food web, and migration is discussed.相似文献
69.
Abstract 3-Chlorobiphenyl-degrading bacteria were obtained from the mating between Pseudomonas putida strain BN10 and Pseudomonas sp. strain B13. Strains such as BN210 resulted from the transfer of the genes coding the enzyme sequence for the degradation of chlorocatechols from B13 into BN10, whereas B13 derivatives such as B131 have acquired the biphenyl degradation sequence from BN10. During growth of the hybrid strains on 3-chlorobiphenyl 90% chloride was released. Activities of phenylcatechol 2,3-dioxygenase, benzoate dioxygenase, catechol 1,2-dioxygenase, chloromuconate cyloisomerase and 4-carboxymethyl-enebut-2-en-4-olide hydrolase were found in 3-chlorobiphenyl-grown cells. The hybrid strains were found to convert some congeners of the Aroclor 1221 mixture such as mono- and dichloro-substituted biphenyls. 相似文献
70.
A procedure for the regeneration of Vitis rootstocks plantlets by organogenesis from foliar tissues is described. Leaves from mature plants grown in growth chambers or from plantlets grown in tubes were wounded with a scalpel and cultured on a modified Murashige and Skoog liquid medium containing different concentrations of benzyl-aminopurine. The presence of benzyl-aminopurine is required for shoot formation. The age of the source explant, the composition of the culture medium and the culture temperature are important parameters of the regeneration process.Abbreviations BA
6-benzyl-aminopurine
- MS
Murashige and Skoog medium
- MM
modified Murashige and Skoog medium 相似文献