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61.
62.
A comparative account of the microbiological characteristics of soils under natural forest,grassland and cropfield from Eastern India 总被引:4,自引:0,他引:4
Microbiological and physico-chemical characteristics of tropical forest, grassland and cropfield soils from India were investigated.
The study revealed that the conversion of natural forest led to a reduction of soil organic C (26–36%), total N (26–35%),
total P (33–44%), microfungal biomass (44–66%) and total microbial biomass C, N and P (25–60%) over a period of 30–50 years.
Comparative analysis of microbial activity in terms of basal soil respiration revealed maximum activity in the forest and
minimum in the cropfield soil. Analysis of microbial metabolic respiratory activity (qCO2) indicated relatively greater respiratory loss of CO2-C per unit microbial biomass in cropfield and grassland than in forest soil. Considering the importance of the microbial
component in soil, we conclude that the conversion of the tropical forest to different land uses leads to the loss of biological
stability of the soil. 相似文献
63.
S.K. AHMAD AND J.S. PRASAD. 1995. The inhibitory potential of aqueous foliar extracts of Adhatoda vasica, Azadirachta indica, Catharanthes roseus, Datura fistulosa, Lantana camara, Muraya exotica, Ocimum sanctum, Ricinus communis and Strychnos nux-vomica were evaluated against soft rot diseases of sponge-gourd fruits caused by Helminthosporium spiciferum and Fusarium scirpi. Conidial germination of F. scirpi and H. spiciferum were reduced to about 75% when their spores were treated with A. indica, C. roseus, D. fistulosa, L. camara, M. exotica and O. sanctum. Considerable reductions (50%) in mycelial dry weights and colony diameters were recorded in liquid media containing (20%) aqueous extracts of C. roseus, D. fistulosa and M. exotica . Other extracts reduced the mycelial growth but to a lesser extent. Post-infection treatment of sponge-gourd fruits with the extracts of A. indica, L. camara, M. exotica, O. sanctum, D. fistulosa and C. roseus almost fully inhibited the spread of disease. Treatment of fruits with A. indica and C. roseus before fungal infection reduced the spread of disease caused by both the pathogens, whereas M. exotica, O. sanctum and D. fistulosa reduced the spread of soft-rot caused by F. scirpi but not by H. spiciferum . 相似文献
64.
Minakshi Basu K. Pal A. S. Malhotra R. Prasad R. C. Sawhney 《International journal of biometeorology》1995,39(1):17-21
Alterations in circulatory levels of total T4 (TT4), total T3 (TT3), free T4 (FT4), free T3 (FT3), thyrotropin (TSH) and T3 uptake (T3U) were studied in male and female sea-level residents (SLR) at sea level, in Armed forces personnel staying at high altitude (3750 m) for prolonged duration (acclimatized lowlanders, ALL) and in high-altitude natives (HAN). Identical studies were also performed on male ALL who trekked to an extreme altitude of 5080 m and stayed at an altitude of more than 6300 m for about 6 months. The total as well as free thyroid hormones were found to be significantly higher in ALL and HAN as compared to SLR values. Both male as well as female HAN had higher levels of thyroid hormones. The rise in hormone levels in different ALL ethnic groups drawn from amongst the southern and northern parts of the country was more or less identical. In both HAN and ALL a decline in FT3 and FT4 occurred when these subjects trekked at subzero temperatures to extreme altitude of 5080 m but the levels were found to be higher in ALL who stayed at 6300 m for a prolonged duration. Plasma TSH did not show any appreciable change at lower altitudes but was found to be decreased at extreme altitude. The increase in thyroid hormones at high altitude was not due to an increase in hormone binding proteins, since T3U was found to be higher at high altitudes. A decline in TSH and hormone binding proteins and an increase in the free moiety of the hormones is indicative of a subtle degree of tissue hyperthyroidism which may be playing an important role in combating the extreme cold and hypoxic environment of high altitudes. 相似文献
65.
M. R. N. Prasad 《Journal of biosciences》1984,6(2):107-119
The importance of developing of drugs which could be taken post-coitally or used once-a-month in the case of a delay in the onset of the menses is well recognized. The availability of such technology would limit exposure to fertility regulating agents to such occasions where there is coital exposure or possibility of pregnancy.Methods of post-coital contraception used so far include IUD’s inserted post-coitally, estrogens, and combinations of estrogens and gestagens. These are reserved primarily for emergency situations to protect women from unwanted pregnancy resulting from rape or unprotected coitus. Levonorgestrel has shown satisfactory results in terms of contraceptive efficacy and is being further evaluated clinically. A number of problems inherent in the development of post-coital contraception are discussed.Menstrual regulation could be achieved by a number of approaches: (a) block progesterone receptors and interfere with the preparation of the endometrium for implantation; (b) luteolysis leading to decreased progesterone levels and interruption of implantation; and (c) termination of early pregnancy by prostaglandins. A number of progesterone antagonists have been evaluated. One of the compounds, RU38486 is being evaluated clinically for termination of very early pregnancy.Deglycosylated derivatives of human chorionic gonadotropin have been shown to antagonize the action of human chorionic gonadotropin and interfere with established pregnancy in rats. Appropriate methods of delivery, immunogenicity and alternate methods for production of human chorionic gonadotropin need to be considered before evaluation of the derivatives for clinical use. In vitro and invivo models need to be developed for evaluation of the teratogenicity and embryotoxicity of post-coital and menses inducing agents.There are a number of gaps in the knowledge of the processes regulating implantation which should be investigated in rodents and in different non-human primate species. 相似文献
66.
A. Alfsen C. de Paillerets K. Prasad P. K. Nandi R. E. Lippoldt H. Edelhoch 《European biophysics journal : EBJ》1984,11(2):129-136
Three characteristics have been demonstrated by the chemical analysis of bovine brain coated vesicles following removal of the coat proteins: a high protein content, a high cholesterol/lipid ratio and a high percentage of phosphatidylethanolamine amongst the phospholipids.The study of lipid bilayer organization and dynamics has been performed using the fluorescent probes pyrene and parinaric acid (cis and trans). This has allowed the study of both lateral mobility and rotational motion in the lipid bilayer of the coated and uncoated vesicles.Lateral mobility in the fluid phase of the lipid is slightly reduced by the presence of the clathrin coat, as indicated by the lower diffusion coefficient of pyrene in coated compared with uncoated vesicles.At all temperatures from 6° to 30°C, solid-phase domains, probed by trans parinaric acid, coexist with fluid-phase domains in the lipid bilayer. The temperature dependence of the parinaric acid lifetimes and of their amplitudes strongly suggests that the solid phase domains decrease in size with temperature, both in coated and uncoated vesicles.However, the difference in the value of the anisotropy at long times (r
), between coated and uncoated vesicles (a difference which is more pronounced for cis than for trans parinaric acid), indicates that the presence of the clathrin coat introduces disorder in the surrounding lipids, thus suggesting a possible role of the clathrin in the formation of the pits on the plasma membrane.Abbreviations CVs
coated vesicles
- UVs
uncoated vesicles
- TLC
thin layer chromatography
- DMSO
dimethylsulfoxide
- DPPC
dipalmitoylphosphatidylcholine
-
cis Pna
cis parinaric acid
- (9,11,13,15-cis-trans-trans-cis)
octadecatetraenoic acid
-
Trans Pna
Trans parinaric acid
- (9,11,13,15-all-trans)
octadecatetraenoic acid 相似文献
67.
The response of the epididymis, ductus deferens, and accessory glands of the castrated prepubertal rhesus monkey to exogenous administration of testosterone or 5alpha-dihydrotestosterone (DHT) was investigated. 200 or 800 mcg of either steroid/day were administered for 60 days beginning on the day after castration. Castration caused a marked regression of the weight of and secretory function of the reproductive organs; testosterone/DHT stimulated their growth and secretory activity which were maintained at the level of the controls. The weight of the caput epididymides however, was unaffected by testosterone but was stimulated by DHT. DHT caused a greater stimulation of the growth and secretory activity of the reproductive organs than testosterone and also caused a hyperstimulation of secretion by the seminal vesicles. The data, analyzed statistically, show that the accessory organs of the prepubertal rhesus monkey are affected by castration and vary in their response to stimulation by exogenous androgens. 相似文献
68.
69.
Regional differences in the metabolism of testosterone in vitro in the epididymis (1.5 cm segments) and ductus deferens (2 cm segments) were investigated in the adult rhesus monkey, Macaca mulatta. The conversion of tritiated testosterone to its 5alpha-reduced derivatives increased from the proximal to the distal regions of the epididymis. The total amount of 5alpha-reduced products in the subsequent segments of the epididymis was highest in the intact monkey and on the intact side of the unilaterally castrated monkey and was followed in decreasing order by the castrated side of the hemiscastrate and least in the bilateral castrate. Hormonal requirements for maintenance of the biological functions of the epididymis and maturation of spermatozoa in the epididymis are discussed. 相似文献
70.