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41.
P.J. Thornalley A. Stern 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》1984,804(3):308-323
Glyceraldehyde induces changes in the flux of glucose oxidised through the hexose monophosphate pathway, the concentrations of intermediates in the Embden-Meyerhoff pathway, the oxidative status of haemoglobin and levels of reduced and oxidised pyridine nucleotides and glutathione in red cells. Glyceraldehyde autoxidises in the cellular incubations, consuming oxygen and producing glyoxalase I- and II-reactive materials. Major fates of glyceraldehyde in red cells appear to be: (i) adduct formation with reduced glutathione and cellular protein; (ii) autoxidation and reaction with oxyhaemoglobin and pyridine nucleotides, and (iii) phosphorylation of d-glyceraldehyde and entry into the glycolytic pathway as glyceraldehyde 3-phosphate. The production of glycerol from glyceraldehyde by red cell l-hexonate dehydrogenase appears not to be a major reaction of glyceraldehyde in red cells. These results indicate that high concentrations of glyceraldehyde (1–50 mM) may induce oxidative stress in red cells by virtue of the spontaneous autoxidation of glyceraldehyde, forming hydrogen peroxide and α-ketoaldehydes (glyoxalase substrates). The implications of glyceraldehyde-induced oxidative stress for the in vitro anti-sickling effect of dl-glyceraldehyde and for the polyol pathway metabolism of glyceraldehyde are discussed. 相似文献
42.
Agonistic behavior was observed in five captive groups of the monogamous monkey Callithrix jacchus jacchus,which normally produces twin offspring every 5 months. Fighting is first recorded when twins are aged 5–10 months. These “twin
fights” determine differences in status between combatants that can be detected 5 months later. From what is known of the
social behavior of the species, it is postulated that an individual’s twin is its most serious rival and that early fighting
is advantageous because injury is minimal while the animal retains its milk dentition. In contrast to twin fights, aggression
between same-sex juveniles and adults does not involve long fights and probably serves to reinforce preexisting differences
in status. It often results in forcing a group member to the periphery, and therefore, its main function may be to drive mature,
same-sexed individuals out of the group. Apart from the relationship between twins, status within the family group is age
related and not normally determined by aggression. 相似文献
43.
Wayne Chris Hawkes Calvin C. Willhite Kimberly A. Craig Stanley T. Omaye Douglas N. Cox Wai Nang Choy Andrew G. Hendrickx 《Biological trace element research》1992,35(3):281-297
Forty pregnant long-tailed macaques were treated daily for 30 d with 0, 25, 150 or 300 μg selenium as L-selenomethionine/kg
body weight. Erythrocyte and plasma selenium and glutathione peroxidase specific activities, hair and fecal selenium, and
urinary selenium excretion were increased by and were linearly related to L-selenomethionine dose. Hair selenium was most
sensitive to L-selenomethionine dose, with an 84-fold increase in the 300 μg selenium/(kg-d) group relative to controls (r=0.917). Daily urinary selenium excretion (80-fold,r=0.958), plasma selenium (22-fold,r=0.885), erythrocyte selenium (24-fold,r=0.920), and fecal selenium (18-fold,r=0.911) also responded strongly to L-selenomethionine. Erythrocyte and plasma glutathione peroxidase specific activities increased
154% and 69% over controls, respectively. Toxicity was associated with erythrocyte selenium >2.3 μg/mL, plasma selenium >2.8
μg/mL, and hair selenium >27 μg/g. Plasma, erythrocyte, and hair selenium concentrations may be useful for monitoring and
preventing the toxicity of L-selenomethionine administered to humans in cancer chemoprevention trials. 相似文献
44.
Pilar Galan Helene Thibault Paul Preziosi Serge Hercberg 《Biological trace element research》1992,32(1-3):421-426
The relationship between iron status and capacity for IL-2 production by lymphocytes was assessed in 81 children from 6 mo
to 3 yr of age selected at random from a population with low socioeconomic status, undergoing free systematic examination
in four children's health centers in the Paris area. Iron deficiency was defined by the existence of at least two abnormal
values among the three indicators of iron status: serum ferritin level ≤12 μg/L, transferrin saturation <12%, and erythrocyte
protoporphyrin concentration >3 μg/g hemoglobin. According to this definition, 53 children were classified as iron deficient
and 28 as iron sufficient. No differences were observed between the iron-deficient and iron-sufficient groups in terms of
the IL-2 concentration without stimulation by PHA. IL-2 production by lymphocytes stimulated with PHA, as well as the stimulation
index (ratio of IL-2 concentration following stimulation by PHA to that of IL-2 concentration without stimulation by PHA)
were significantly lower in iron-deficient children. The reduction in IL-2 production by activated lymphocytes observed in
our study of iron-deficient children may be responsible for impairments in immunity found by other authors, particularly in
cell-mediated immunity. 相似文献
45.
This paper reports measurements of weight and recumbent length for a cross-sectional sample of 149 Shipibo infants and children between birth and 35.99 months of age from eight villages in the Peruvian Amazon Basin. The Shipibo are an Amerindian population experiencing a period of local environmental disruption and rapid cultural change. Compared with the National Center for Health Statistics (NCHS) references values, Shipibo children are smaller and shorter than American children. The differences are least at birth. Deficits in linear growth begin between 3 and 6 months of age and continue through 35.99 months of age. Weight-for-length ratios are generally adequate compared to the NCHS values in all age groups. This pattern of growth is similar to that reported for non-Amerindians in many developing countries and is assumed to represent a pattern of growth under mild-to-moderate undernutrition. High infant mortality rates suggest that an interaction of suboptimal nutrition and infectious diseases is contributing to the pattern of growth retardation seen; however, genetic differences cannot yet be discounted. 相似文献
46.
Records of crop damage caused by Bibionidae are reviewed together with evidence for their beneficial activities, natural enemies and control methods. Bibionids are sporadic and infrequent pests. Although grass and cereals are most vulnerable, a wide range of crops is attacked. Damage is most severe after grass or when plants are under stress. The presence of organic matter during oviposition increases the likelihood of damaging populations. Many natural enemies exist but their impact on adult or larval populations has not been quantified. Given the pattern of attacks and lack of approved insecticides, cultural control methods are more appropriate than chemical. The role of adult bibionids in pollination and of larvae involved in soil processes could be of greater importance than any damage caused by the group. 相似文献
47.
The zooplankton-phytoplankton interface in lakes of contrasting trophic status: an experimental comparison 总被引:4,自引:4,他引:0
We report here the results of an experimental study designed to compare algal responses to short-term manipulations of zooplankton
in three California lakes which encompass a broad range of productivity (ultra-oligotrophic Lake Tahoe, mesotrophic Castle
Lake, and strongly eutrophic Clear Lake). To assess the potential strength of grazing in each lake, we evaluated algal responses
to a 16-fold range of zooplankton biomass. To better compare algal responses among lakes, we determined algal responses to
grazing by a common grazer (Daphnia sp.) over a range ofDaphnia densities from 1 to 16 animals per liter. Effects of both ambient grazers andDaphnia were strong in Castle Lake. However, neither ambient zooplankton norDaphnia had much impact on phytoplankton in Clear Lake. In Lake Tahoe, no grazing impacts could be demonstrated for the ambient zooplankton
butDaphnia grazing had dramatic effects. These results indicate weak coupling between phytoplankton and zooplankton in Clear Lake and
Lake Tahoe, two lakes which lie near opposite extremes of lake trophic status for most lakes. These observations, along with
work reported by other researchers, suggest that linkages between zooplankton and phytoplankton may be weak in lakes with
either extremely low or high productivity. Biomanipulation approaches to recover hypereutrophic lakes which aim only to alter
zooplankton size structure may be less effective if algal communities are dominated by large, inedible phytoplankton taxa. 相似文献
48.
Bente Christiansen Jens Pete Lomholt Kjell Johansen 《Environmental Biology of Fishes》1982,7(3):291-296
Synopsis Oxygen uptake (Vo
2) was measured in carp of approximately 40 cm length swimming at controlled variable oxygen tensions (Po
2). At Po
2> 120 mm Hg Vo
2 increased with an increase in swimming speed from 5.6 to 11.3 cm · sec–1. Extrapolation of Vo
2 to zero activity at Po
2 = 140 mm Hg revealed a standard O2 uptake of 36.7 ml O2 · kg–1 · h–1 at 20° C. At the lowest swimming speed (5.6 cm · s–1) the oxygen uptake increased when the water Po
2 was reduced. A near doubling in Vo
2 was seen at Po
2 = 70 mm Hg compared to 140 mm Hg. At higher swimming speeds in hypoxic water Vo
2 decreased relative to the values at low swimming speeds. As a result the slope of the lines expressing log Vo
2 as a function of swimming speed decreased from positive to negative values with decreasing Po
2 of the water. pH of blood from the caudal vein drawn before and at termination of swimming at Po
2 = 70 mm Hg and 100 mm Hg did not show any decrease in relation to rest values at Po
2 = 140 mm Hg. Blood lactate concentration did not increase during swimming at these tensions. 相似文献
49.
Paul Jensén 《Physiologia plantarum》1981,52(4):437-441
Uptake of Rb+ from a complete nutrient solution with 2.0 mM Rb+ was studied in roots of spring wheat seedlings ( Triticum aestivum L. cv. Svenno) with different K+ levels. The relationship between Rb+ uptake and concentration of K+ in the roots indicated a negative feedback mechanism operating through allosteric control. The Rb+ uptake process in root cells was divided into two steps: (1) binding of the ion in the free space, and (ii) transmembrane transport into the cytoplasm. Metabolic and non-metabolic components of uptake were separated by addition of the metabolic inhibitor 2,4-dinitrophenol (DNP) to the nutrient solution. It is suggested that metabolic Rb+ uptake requires energy in two uptake steps (for binding to the carrier entity in the free space and for transmembrane transport) or in one step only (for transmembrane transport), dependent on the K+ status of the roots. The change from metabolic to non-metabolic binding in the free space is accomplished by changing the conformational state of the carrier (slow/fast transitions). There may be a hysteretic effect on metabolic Rb+ uptake through a slow transition between carrier states. This is superimposed on the negative cooperativity, strengthening further cooperativity at intermediate K+ levels in the roots. Non-metabolic Rb+ uptake probably consists of two components, a carrier-mediated (facilitated diffusion) and a parallel diffusive component. 相似文献
50.
S. A. BARNETT RHONDDA G. DICKSON KATHY G. WARTH 《Zoological Journal of the Linnean Society》1980,70(4):421-430
Scent marking by deposition of urine, and the preputial glands, of adult, male, wild house mice, Mus mmmlus L., were studied and compared with those of an outbred domestic strain. The preputial glands of dominant wild mice were always heavier than those of subordinates. No dominance relationships could be established among the domestic mice. For study of scent marking each mouse was observed singly in a residential maze. Dominant wild mice marked more than the subordinates. The domestic mice scent-marked much less even than the subordinate wild mice. Subordinate wild mice spent less time than the dominant wild mice outside the nest; but the number of excursions outside the nest made by the subordinates resembled that of the dominants. Hence social status influenced the pattern of movements in a structured environment. 相似文献