The effect of zwitterion buffers on the freezability of Boer goat semen

Twenty semen samples with mass activity greater than +3 were collected from six healthy, mature Boer goat bucks. Each ejaculate was divided into four equal parts and extended at 37 degrees C in Tris, Test, Tes and Bes buffers containing egg yolk and glycerol. Semen was placed into medium size French strawsand after 2 hours of equilibration at 5 degrees C, frozen in the vapour phase and stored in liquid nitrogen for 7 days at -196 degrees C. Progressive motility, the number of live spermatozoa and glutamic oxaloacetic transaminase (GOT) release were studied after the initial extension, after equilibration and after 15 minutes and 7 days of freezing of semen. Semen samples when extended with Tris yolk glycerol showed significantly (P<0.01) higher progressive motility and live spermatozoa than when extended with the other zwitterion buffer-based extenders. The change of extenders did not influence the release of GOT at various stages of freezing of semen (P>0.05).     

In vivo regulation of glutamine synthetase by ammonium in the cyanobacterium Anabaena L-31

In cell-free preparations of NH₄⁺-grown cultures of the cyanobacterium Anabaena L-31 the glutamine synthetase activity is only half as much as in N₂-grown cultures. Using a procedure which enables quantitative purification of the enzyme to homogeneity it has been shown that the decrease in the enzyme activity is caused by NH₄⁺-mediated repression. Glutamine synthetase activity in both N₂-grown and NH₄⁺-grown Anabaena remains stable for more than 24 h in the presence of chloramphenicol suggesting low enzyme turnover and an enzyme half-life greater than the generation time (16–18 h) of the cyanobacterium. In N₂-grown cultures, a drastic decrease in the enzyme activity by exogenous NH₄⁺ can be discerned when fresh protein synthesis is prevented by chloramphenicol. The enzyme purified from such cultures has K_m values for NH₄⁺, glutamate Mg²⁺, and ATP similar to those observed for the enzyme from N₂- and NH₄⁺-grown Anabaena, but shows depression in V for all the substrates, leading to drastic decrease in specific activity. The modified enzyme also shows a sharper thermal denaturation profile. These results indicate that NH₄⁺-mediated modification to a less active form may be a means of regulation of glutamine synthetase in N₂-fixing cultures of Anabaena.     

Arsenic affects mineral nutrients in grains of various Indian rice (Oryza sativa L.) genotypes grown on arsenic-contaminated soils of West Bengal

The exposure of paddy fields to arsenic (As) through groundwater irrigation is a serious concern that may not only lead to As accumulation to unacceptable levels but also interfere with mineral nutrients in rice grains. In the present field study, profiling of the mineral nutrients (iron (Fe), phosphorous, zinc, and selenium (Se)) was done in various rice genotypes with respect to As accumulation. A significant genotypic variation was observed in elemental retention on root Fe plaque and their accumulation in various plant parts including grains, specific As uptake (29–167 mg kg^?1 dw), as well as As transfer factor (4–45%). Grains retained the least level of As (0.7–3%) with inorganic As species being the dominant forms, while organic As species, viz., dimethylarsinic acid and monomethylarsonic acid, were non-detectable. In all tested varieties, the level of Se was low (0.05–0.12 mg kg^?1 dw), whereas that of As was high (0.4–1.68 mg kg^?1 dw), considering their safe/recommended daily intake limits, which may not warrant their human consumption. Hence, their utilization may increase the risk of arsenicosis, when grown in As-contaminated areas.     

Combination of Ascorbate and α-Tocopherol as a Preventive Therapy against Structural and Functional Defects of Erythrocytes in Visceral Leishmaniasis

The redox unbalance in erythrocytes has been found to contribute significantly in the development of anemia in visceral leishmaniasis (VL). The present study revealed enhanced production of reactive oxygen species (ROS) and gradual depletion of α-tocopherol and ascorbate in the erythrocytes of infected animals. The response of erythrocytes to chronic treatment with antioxidants was studied in hamsters during leishmanial infection. Treatment with a combination of α-tocopherol and ascorbate proved to be the most effective preventive for the proteolytic degradation of erythrocyte membrane. Erythrocytes from infected animals were thermally more sensitive compared to the control ones. Combination of both antioxidants was most successful in resisting heat induced structural defects in the cells. Cross-linking of membrane proteins subsequent to oxidative damage in the red cells was accompanied by the formation of high molecular weight protein band at the top of the resolving gel in the presence of the cross-linking agent dimethyladepimidate (DMA). Marked inhibition of cross-linking was observed with combination of both antioxidants. Treatment with α-tocopherol and ascorbate together could withstand osmotic lysis of erythrocytes in the infected animals very efficiently. Decreased hemoglobin (Hb) level was successfully replenished and was coupled with significant increase in the life span of red cells after treating the animals with both antioxidants. Results indicate better efficacy of the combination therapy with α-tocopherol and ascorbate in protecting the erythrocytes from structural and functional damages during leishmanial infection.     

On the relationships among diversity,productivity and climate from an Indian tropical ecosystem: a preliminary investigation

The relationships among diversity, productivity and climate are complex, especially in tropical ecosystems; and are less studied. We studied here the bi- and tri-partite relationships between and among the plant diversity, productivity and climate variables (i.e., temperature, precipitation and moisture) in a tropical ecosystem in India by analyzing three forest types for the year 2010. Comparison of productivity (Carnegie–Ames–Stanford Approach model derived-net primary productivity, NPP) and climate condition with respect to 2001 showed significant increase in NPP and temperature and overall decrease in precipitation and moisture condition in last decade. The NPP for sal forest ranged from 579.4 to 1,142 for the year 2001 and 557.2 to 1231.6 g Cm⁻² year⁻¹ for the year 2010. The mean monthly temperature varied from 18 to 21.8°C and 26 to 27°C; and the annual precipitation varied from 15 to 45 and 32 to 76 cm/year for the year 2001 and 2010 respectively. Strong correlation was observed between monthly mean temperature and productivity during 2001, while a decrease was observed during the year 2010. The ecosystem has shown a trend of rapid drying in last decade, triggering more detail studies for understanding of the eco-climatology. In general, sal forest, a natural forest sowed higher diversity and productivity followed by mixed deciduous (MD) forest and teak plantation. Though, areas with higher NPP are well correlated with higher temperature, precipitation and moisture; they seem to be related to species density rather than diversity. However, there is a need to have year-on-year assessments in order to ascertain if this difference represents a real phenomenon rather than an artefact of sampling. The pilot study helps in understanding the complex relationships and is very useful in the fast changing climate.     

Effect of Erythropoietin on the interaction of Concanavalin A with rat erythrocytes

Effect of Erythropoietin (Ep) on the interaction of Concanavalin A (Con A) with rat erythrocytes was studied using ¹²⁵I-labelled Con A. Binding of Con A to erythrocytes was dependent on time and cell concentration. Starvation caused an elevation of the lectin binding capacity of red cells which again came down towards the normal level on Ep administration to starved rats. Binding of Con A to erythrocytes decreased linearly with increasing concentration of Ep. Specificity of binding was confirmed by inhibition studies with -methyl-D-mannopyranoside (Me Man) Cells from the starved rats compared to those from normal and Ep treated animals were less prone to inhibition by this sugar analog. Positive cooperative binding of Con A to rat erythrocyte was observed at low concentration of Con A but was absent at higher lectin concentrations. Starvation caused an increase in the number of binding sites per cell which returned to normal level after Ep treatment. Under identical conditions, binding affinities were not much changed in these cells. Cells from the starved animals were more susceptible to agglutination compared to those from normal and Ep-treated rats. Microviscosity and cholesterol/phospholipid ratio of red cell membrane decreased in the starved animals which retraced its way back towards the normal level after Ep treatment.     

Mechanistic Studies on Metal-pyrophosphate Hydrolysis. Structure of Tetraammine(chloroaquo)cobait(III) dichloride ([CO(NH3)4ClH20]2+•-2Cl−), an Acid Hydrolysis Product of Co(NH3)4HP2O7 and Co(NH3)4PO4

Abstract

The octahedral complex tetraammine(chloroaquo)cobalt(III) dichloride is shown to be the HCl hydrolysis product of both P¹,^2-bidentate tetraammine(pyrophosphato)cobalt(III) [CO(NH₃)₄HP₂0₇ or CoPP] and bidentate tetraammine(phosphato)cobalt(III) [Co(NH₃)₄P0₄or CoP]. The complex crystallizes in the orthorhombic space group Pna2¹ with cell dimensions α=13.033(2)Å, b=6.710(1) Å, and c=10.318(2)Å; the crystal structure was refined to a final disagreement index of 0.033. The average of the four Co-N distances is 1.944±6Å. The Co-Cl distance is 2.257(2)Å and the Co-O(W) distance is 1.971(4)Å. Both protons of the coordinated water molecule are engaged in strong hydrogen bonds to the two nonbonded chloride counterions with 0(W)-C1 distances of 3.087(6)Å and 3.123(6)Å. Each nonbonded chloride is engaged in seven hydrogen bonding interactions resulting from the high ratio of hydrogen bond donors to acceptors in the CoP structure. Cobalt bisphosphate (CoP₂) is the final enzyme hydrolysis product when CoPP is used as substrate in the yeast inorganic pyrophosphatase reaction. The bridge oxygen atom is the site of initial CoPP cleavage both, for HCl catalyzed hydrolysis as well as for enzyme catalyzed hydrolysis.     

Combination of ascorbate and alpha-tocopherol as a preventive therapy against structural and functional defects of erythrocytes in visceral leishmaniasis

The redox unbalance in erythrocytes has been found to contribute significantly in the development of anemia in visceral leishmaniasis (VL). The present study revealed enhanced production of reactive oxygen species (ROS) and gradual depletion of alpha-tocopherol and ascorbate in the erythrocytes of infected animals. The response of erythrocytes to chronic treatment with antioxidants was studied in hamsters during leishmanial infection. Treatment with a combination of alpha-tocopherol and ascorbate proved to be the most effective preventive for the proteolytic degradation of erythrocyte membrane. Erythrocytes from infected animals were thermally more sensitive compared to the control ones. Combination of both antioxidants was most successful in resisting heat induced structural defects in the cells. Cross-linking of membrane proteins subsequent to oxidative damage in the red cells was accompanied by the formation of high molecular weight protein band at the top of the resolving gel in the presence of the cross-linking agent dimethyladepimidate (DMA). Marked inhibition of cross-linking was observed with combination of both antioxidants. Treatment with alpha-tocopherol and ascorbate together could withstand osmotic lysis of erythrocytes in the infected animals very efficiently. Decreased hemoglobin (Hb) level was successfully replenished and was coupled with significant increase in the life span of red cells after treating the animals with both antioxidants. Results indicate better efficacy of the combination therapy with alpha-tocopherol and ascorbate in protecting the erythrocytes from structural and functional damages during leishmanial infection.