Immobilization of fungal spores on synthetic polymers

Adsorption of fungal spores on a synthetic polymer - High Density Polyethylene was successfully achieved using different pretreatments. Sonication of beads followed by ferric nitrate treatment or use of 0.1% tributyrin gave adsorption upto 46%. Use of dichloromethane as a solvent for sonication is recommended for its better performance in reuse studies (upto 5 times without much decrease in activity). 100 g of immobilized biocatabyst in a 7 L Fluidized Bed Bioreactor was found to perform better than shaker flask at a much lower power input.     

Peroxidase activity in the mouse uterus, placenta and fetus during pregnancy

Changes in peroxidase activity during pregnancy were examined in CD-1 mice. Peroxidase activity was measured with guaiacol as the substrate in uterine extracts of nonpregnant mice and in uterine, placental, and fetal extracts of pregnant mice on days 9, 12, 14, 16, and 18 of gestation. Uterine peroxidase activity in nonpregnant mice was high, but declined logarithmically to only 0.2% by day 18 of pregnancy. In contrast to this decline, a concomitant 50-fold logarithmic increase in fetal peroxidase activity was observed between day 12 and 18. Activity in placental extracts did not change significantly throughout the gestational period examined. These results suggest that membrane bound peroxidase in mouse uterus and fetus undergoes major shifts during pregnancy.     

Insulin-mediated phosphorylation of ribosomal protein S6 in mouse melanoma cells and melanoma x fibroblast hybrid cells in relation to cell proliferation

The possible role of insulin-mediated phosphorylation of ribosomal protein S6 in the control of cell proliferation was examined in insulin-unresponsive mouse melanoma calls (PG19) and insulin-responsive melanoma x fibroblast clone 100A. In the hybrid cells, under conditions of growth arrest in medium with low serum, ribosomal protein S6 was rapidly phosphorylated in response to insulin or serum. The phosphorylation of the S6 protein increased over a wide range of insulin concentrations, suggesting that insulin stimulated the phosphorylation by interacting with both high- and low-affinity receptors. In contrast, in growth-arrested melanoma cells, an intermediate level of S6 phosphorylation was observed. Insulin caused only a marginal increase and serum caused a small but consistent increase in the level of S6 phosphorylation in the melanoma cells. Cell cycle analysis revealed that both cell lines arrested growth to a similar degree in the G1 phase of the cell cycle; thus, the higher baseline level of S6 phosphorylation observed in the melanoma cells was not attributable to less complete growth arrest of these cells in medium with low serum. The S6 phosphorylation results correlate well with previous results suggesting that the hybrid cells, but not the parental melanoma cells, can become growth-limited for processes regulated by insulin.     

DETERMINATION OF GUSTATORY SUCROSE THRESHOLD IN WATER BY USE OF A LINEAR SUCROSE GRADIENT

A novel experimental method was developed which allows the determination of the threshold concentration of sucrose by use of a linear sucrose gradient in water. With this method a continuous tasting of the test-liquid is possible. A panel of 15 persons experienced in taste-testing was used. Three gradients of different steepness were applied: 0 to 1.5% (w/w) sucrose in 2 min (I), 3 min (II) and 4 min (III). The results of the new method were compared with those of the standard method (DIN). With gradients I and II we found values which were significantly higher than those of the standard method (I: 0.49% (w/w); II: 0.46% (w/w); DIN: 0.31% (w/w)), whereas with gradient III the same threshold value was found as with the DIN-Method (III: 0.32% (w/w)).     

Age related changes in ovarian follicular kinetics in the Indian skipper frogRana cyanophlyctis (Schn.)

Changes in ovarian follicular kinetics were studied in relation to aging in the Indian skipper frog Rana cyanophlyctis.Age was determined by skeletochronology, by counting the number of growth rings and lines of arrest of growth from the cross sections of 4th phalange of 4th toe. For follicular kinetics study oocytes were counted under binocular using 10% of Bouin’s fixed ovary and they were classified into first growth phase, medium-sized second growth phase, large-sized second growth phase and atretic follicles. Analysis of phalangeal cross sections indicated that frogs ranging 14–54 g in body weight and 4.9–8.9 cm in body size showed 1–7 year rings. Frogs that weighed 14–16 g showed 1 year ring, and contained immature ovaries; those with 18 g body weight had one to two year rings, in which second growth phase oocytes appeared for the first time in the primiparous ovary. Frogs with 20–54 g body weight showed 2–5 year rings in which ovary contained 5–24% of second growth phase oocytes. Further, body weight, body size, ovarian weight, number and size of second growth phase oocytes and total number of oocytes showed a significant (P < 0.05) positive correlation, while, the number of first growth phase and atretic follicles showed a poor correlation with age. The results suggest that in nature, the age of Rana cyanophlyctis ranges between 1–7 years. Phalangeal growth rings are formed annually. Females attain sexual maturity in 2nd year. Frogs with 2–5 years of age may constitute breeding females. Body weight, body size, ovarian mass, number of second growth phase and total oocytes, and egg size increase with age up to 5 years.     

The cytolytic activity of pulmonary CD8+ lymphocytes, induced by infection with a vaccinia virus recombinant expressing the M2 protein of respiratory syncytial virus (RSV), correlates with resistance to RSV infection in mice.

Previous studies demonstrated that the pulmonary resistance to respiratory syncytial virus (RSV) challenge induced by immunization with a recombinant vaccinia virus expressing the M2 protein of RSV (vac-M2) was significantly greater 9 days after immunization than at 28 days and was mediated predominantly by CD8+ T cells. In this study, we have extended these findings and sought to determine whether the level of CD8+ cytotoxic T-lymphocyte (CTL) activity measured in vitro correlates with the resistance to RSV challenge in vivo. Three lines of evidence documented an association between the presence of pulmonary CTL activity and resistance to RSV challenge. First, vac-M2 immunization induced pulmonary CD8+ CTL activity and pulmonary resistance to RSV infection in BALB/c (H-2d) mice, whereas significant levels of pulmonary CTL activity and resistance to RSV infection were not seen in BALB.K (H-2k) or BALB.B (H-2b) mice. Second, pulmonary CD8+ CTL activity was not induced by infection with other vaccinia virus-RSV recombinants that did not induce resistance to RSV challenge. Third, the peak of pulmonary CTL activity correlated with the peak of resistance to RSV replication (day 6), with little resistance being observed 45 days after immunization. An accelerated clearance of virus was not observed when mice were challenged with RSV 45 days after immunization with vac-M2. The results indicate that resistance to RSV induced by immunization with vac-M2 is mainly mediated by primary pulmonary CTLs and that this resistance decreases to very low levels within 2 months following immunization. The implications for inclusion of CTL epitopes into RSV vaccines are discussed in the context of these observations.     

Some aspects of osmotic biology of the freshwater leech,Poecilobdella viridis (Blanchard)

Ability of the freshwater leech, Poecilobdella viridis to withstand osmotic changes was investigated by following the fluctuations of the body weight in tap-water and in different salt concentrations. The salinity tolerance limit (lethal salt concentration) of this leech was found to be 1.54% NaCl which equilibrates approximately 51.359% sea-water. There was a significant weight loss in P. viridis when kept in both, hypo- and hypertonic media. It is concluded that volume regulation (through weight changes) was slight in hypotonic media whereas in hypertonic media there was an incessant decline in body weight. Adaptive significance of these findings is discussed.