Sex ratio trajectory in mouse

Skewing of the sex ratio towards males occurs in humans. The possible explanation for excess male births could be a preference for Y-bearing sperm at fertilization and/or selective elimination of female embryos during pregnancy. In this study, we have tested the sex ratio in the preimplantation embryo (2–3 cells stage/closest possible primary sex ratio), the post-implantation embryo (day E7.5), and at birth (secondary sex ratio) on a homogenous (genetic, environmental, and dietary) population of mice to ascertain the biological reason i.e., male preference at fertilization or female elimination during pregnancy or both. Primary sex ratio on early preimplantation embryos (2–3 cells stage) was studied on 598 embryos and secondary sex ratio (at birth) on 721 pups using PCR-based sexing (both X & Y chromosome-specific) besides sex ratio of 80 post-implantation embryos (day E7.5). We have also investigated whether the fat content (high & low) of the diet affects the sex ratio. We observed a skewed sex ratio (more female) in preimplantation embryos (0.436; 95 % CI 0.39, 0.48), and post-implantation embryos (0.462; 95 % CI 0.35, 0.57) but reverse skewing (more male) at birth (0.539; 95 % CI 0.5, 0.58). We also observed that high-fat diet promoted male sex ratio at birth (0.657; 95 % CI 0.57, 0.74) whereas a low-fat diet had the opposite effect (0.46; 95 % CI 0.36, 0.56) but no effect at fertilization (2–3 cells stage embryos). This indicates selective elimination of female embryo and fetus throughout pregnancy in mice, more so with a high-fat diet.     

Penta- and hexa-coordinate ferric hemoglobins display distinct pH titration profiles measured by Soret peak shifts

Hemoglobins with diverse characteristics have been identified in all kingdoms of life. Their ubiquitous presence indicates that these proteins play important roles in physiology, though function for all hemoglobins are not yet established with certainty. Their physiological role may depend on their ability to bind ligands, which in turn is dictated by their heme chemistry. However, we have an incomplete understanding of the mechanism of ligand binding for these newly discovered hemoglobins and the measurement of their kinetic parameters depend on their coordination at the heme iron. To gain insights into their functional role, it is important to categorize the new hemoglobins into either penta- or hexa-coordinated varieties. We demonstrate that simple pH titration and absorbance measurements can determine the coordination state of heme iron atom in ferric hemoglobins, thus providing unambiguous information about the classification of new globins. This method is rapid, sensitive and requires low concentration of protein. Penta- and hexa-coordinate hemoglobins displayed distinct pH titration profiles as observed in a variety of hemoglobins. The pentacoordinate distal histidine mutant proteins of hexacoordinate hemoglobins and ligand-bound hexacoordinate forms of pentacoordinate hemoglobins reverse the pH titration profiles, thus validating the sensitivity of this spectroscopic technique.     

Comparative evaluation of the metabolic potentials of different strains of Peptostreptococcus productus: utilization and transformation of aromatic compounds

Three strains of Peptostreptococcus productus were tested for growth at the expense of methoxylated aromatic compounds. Strain M8A-18 (human fecal isolate) was unable to utilize methoxylated aromatic compounds. While the type strain ATCC 27340 (human septicemia isolate) was capable of minimal growth with methoxylated aromatic compounds, ATCC 35244 (sewage sludge isolate) displayed significant growth on methoxylated aromatic compounds. Methoxylated phenols, benzoates, benzyl alcohol and phenylacrylates supported the growth of ATCC 35244 and were O-demethylated to their respective hydroxylated derivatives. During O-methyl- or CO-dependent growth, the double bond of the acrylate side chain of certain methoxylated and non-methoxylated phenylacrylates was reduced. Although other aromatic substituent groups (-COOH and -CH3) were transformed during CO-dependent growth, in short-term growth studies, the aromatic ring was not subject to reduction or degradation. Of the three strains tested, only strain M8A-18 failed to grow at the expense of carbon monoxide (CO).     

Effects of β-Cyclodextrin on the Structure of Sphingomyelin/Cholesterol Model Membranes

The interaction of β-cyclodextrin (β-CD) with mixed bilayers composed of sphingomylein and cholesterol (Chol) above and below the accepted stable complexation ratio (67:33) was investigated. Membranes with the same (symmetric) and different (asymmetric) compositions in their inner and outer leaflets were deposited at surface pressures of 20, 30, and 40 mN/m at the solid-liquid interface. Using neutron reflectometry, membranes of various global molar ratios (defined as the sum of the molar ratios of the inner and outer leaflets), were characterized before and after β-CD was added to the subphase. The structure of bilayers with global molar ratios at or above the stable complexation ratio was unchanged by β-CD, indicating that β-CD is unable to remove sphingomyelin or complexed Chol. However, β-CD removed all uncomplexed Chol from bilayers composed of global molar ratios below the stable complexation ratio. The removal of Chol by β-CD was independent of the initial structure of the membranes as deposited, suggesting that asymmetric membranes homogenize by the exchange of molecules between leaflets. The interaction of β-CD with the aforementioned membranes was independent of the deposition surface pressure except for a symmetric 50:50 membrane deposited at 40 mN/m. The scattering from 50:50 bilayers with higher packing densities (deposited at 40 mN/m) was unaffected by β-CD, suggesting that the removal of Chol can depend on both the composition and packing density of the membrane.     

Effect of Non-removal of the Macrophytic Biomass on the Characteristics of Water and Plant Community in Lake Naini Tal,U.P., India

In the most productive macrophytes stand lying within the littoral zone of Lake Naini Tal (a Kumaun Himalayan Lake, located 1937 m above sea level) the macrophytic biomass was removed at the time of peak biomass one year, but not during the next. The effect of non-removal of the macrophytes was apparent in the physical and chemical parameters of the water, viz: thermal stratification, pH, dissolved oxygen, calcium and nitrogen content. The removal of macrophytes increased the plant diversity. Seasonal patterns of ash, calcium and nitrogen content in plant tissues were different for the two years of study.