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41.
Bolinopsis vitrea is a warm water lobate ctenophore which doesnot overlap in its distribution with Mnemiopsis mccradyi incontiguous waters. We examined its feeding ecology on a seriesof cruises. B. virrea ingested increasingly more prey at higherfood concentrations (2100 prey l1) but feedingeffort (clearance rate) decreased with increasing food availability.On a dry weight basis, smaller tentaculate Bolinopsis ingestedseveral times more than larger lobates, but based on carbonweight, specific ingestion was fairly uniform over the entiresize range investigated (660 mm total length). Bolinopsiscollected during the daytime in the Bahamas rarely had morethan three prey items in their guts. These results and laboratorymeasurements of digestion times (av. = 1.9 h) allowed computationof daily rations, which could not account for the metabolicrequirement as measured on the same cruises. Results of feedingexperiments, however, implied that prey densities in excessof 111 were sufficient to sustain a growing populationof Bolinopsis. Prey concentrations about an order of magnitudehigher were required for M. mccradyi based on similar experiments.These results were in general agreement with observed densitiesand distributions of ctenophores and their zooplankton preyin the Bahamas and coastal South Florida. 相似文献
42.
Health care attitudes reflect the basic world view and values of a culture, such as how we relate to nature, other people, time, being, society versus community, children versus elders and independence versus dependence. Illness behavior determines who is vulnerable to illness and who agrees to become a patient—since only about one third of the ill will see a physician. Cultural values determine how one will behave as a patient and what it means to be ill and especially to be a hospital patient. They affect decisions about a patient''s treatment and who makes the decisions. Cultural differences create problems in communication, rapport, physical examination and treatment compliance and follow through. The special meaning of medicines and diet requires particular attention. The perception of physical pain and psychologic distress varies from culture to culture and affects the attitudes and effectiveness of care-givers as much as of patients. Religious beliefs and attitudes about death, which have many cultural variations, are especially relevant to hospital-based treatment. Linguistic and cultural interpreters can be essential; they are more available than realized, though there are pitfalls in their use. Finally, one must recognize that individual characteristics may outweigh the ethnic and that a good caring relationship can compensate for many cultural missteps. 相似文献
43.
Linear, Single-Stranded Deoxyribonucleic Acid Isolated from Kilham Rat Virus 总被引:9,自引:9,他引:0 下载免费PDF全文
Kilham rat virus (KRV) was grown in a rat nephroma cell line and was purified by two isopycnic centrifugations in cesium chloride. The virus contains single-stranded deoxyribonucleic acid (DNA) with a molecular weight of approximately 1.6 x 10(6). The DNA was extracted from the virion by both phenol extraction and by 2% sodium dodecyl sulfate at 50 C. KRV DNA, extracted by both procedures, was observed in an electron microscope by using a cytochrome c or diethylaminoethyldextran monolayer. The DNA was also exposed to exonuclease I, an enzyme which hydrolyzes specifically linear, single-stranded DNA. Hydrolysis of 70 to 80% of the DNA was observed. Both the enzymatic and the electron microscope studies support the conclusion that extracted KRV DNA is a single-stranded, linear molecule. The length of the DNA was measured in the electron microscope and determined to be 1.505 +/- 0.206 mum. 相似文献
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A mathematical analysis of branched pathway regulation has led to the prediction of a novel homoserine control in Escherichia coli B. Experimental support for such control is presented in this paper. Homoserine, the precursor of both threonine and methionine, inhibits nicotinamide adenine dinucleotide phosphate (NADP(+))-specific glutamate dehydrogenase (EC 1.4.1.4), the enzyme catalyzing the first reaction in ammonia assimilation. Physiological and biochemical evidence for this effect are offered. Homoserine depresses the growth rate of the organism, and glutamate, the product of the inhibited reaction, reverses this effect. The NADP(+)-specific glutamate dehydrogenase activity in cell-free extracts is inhibited by homoserine, and this inhibition parallels the restriction of growth rate. These effects are found in other enteric bacteria which share a similar overall pattern of control for the amino acids derived from aspartate. On the other hand, a sampling of more distantly related species which have different pathways and/or regulatory patterns provides no evidence for homoserine inhibition of the glutamate dehydrogenase reaction. 相似文献
46.
The Fertility of Melanesian Girls, Laboratory Mice, and Prostitutes: A Comment on the "Bruce Effect"
Ann Chowning 《American anthropologist》1969,71(6):1122-1125
Greenfield has recently proposed that low fertility in both prostitutes and unmarried Trobriand girls may be explained by the "Bruce effect": the inhibition of pregnancy in female mice that have had intercourse with different males within a short period. An examination of Malinowski's data indicates that a Trobriand girl usually had intercourse with only one man over a fairly long period and her sex life was not at all comparable to that of a prostitute or one of Bruce's mice. Low fertility in unmarried girls has been well documented for several Melanesian societies that differ notably in the behavior permitted to girls. The existence of so-called adolescent sterility still seems to be the best explanation to cover all of these cases. [fertility, sexual behavior, Melanesia] 相似文献
47.
E. Edward Peeples Ann Geisler Carol J. Whitcraft Clarence P. Oliver 《Biochemical genetics》1969,3(6):563-569
Phenol oxidase activity of activated A1 and A2 (A3) electrophoretic components from 19 lozenge mutant and three lozenge double mutant strains was compared to that of wild type flies. Melanin production by the activated A components with tyrosine as substrate was compared to activity in the same acrylamide gels with dopa as substrate. Melanin production decreased, first in the A1 band and then in the A2 (A3) band, with increased morphological expression of the mutant genes. No melanin bands were obtained with either substrate in five of the more severely affected mutants. A possible correlation between phenol oxidase activity and quinone production necessary for normal development of eyes, female accessory sex organs, and claws is discussed.Supported by PHS grant AM-08331-05. 相似文献
48.
In 1967 we admitted 339 cases of infantile gastroenteritis; one-third of these were dehydrated, and in this group the commonest biochemical abnormality found was hypernatraemia, sometimes with metabolic acidosis. A higher incidence of dehydration was found in the patients who had received oral glucose fluids before admission. Enteropathic Escherichia coli were isolated from the faeces of 16% of the cases. Associated infections, especially of the respiratory tract, were common. Treatment was aimed at the restoration of fluid and electrolyte balance. Usually this was achieved with oral fluids, though intravenous fluids were used in the most severely dehydrated cases. Recovery was complete in 320 cases and a further 14 cases were discharged as carriers of enteropathic E. coli. There were five deaths (1·5%) in the series; three occurred immediately after admission. 相似文献
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