Intermediates in plasmid pT181 DNA replication.

Staphylococcus aureus plasmid pT181 is thought to replicate via an asymmetric rolling-circle mechanism. By studying pulse labeled replicative intermediates, here we report that pT181 replication involves: (1) a post-replicative hypersupercoiled monomer and (2) a partially replicated intermediate which lacks superhelicity but is unlike a typical rolling-circle intermediate in that only nascent strands of less than unit length are released by alkali denaturation. A model for pT181 replication is proposed to accommodate this apparent discrepancy.     

Maternal factors and infant and child mortality in Bangladesh

Using data from The World Fertility Survey, this study shows that the length of the preceding birth interval was the most important maternal factor influencing infant and child mortality risks in Bangladesh. This was such a crucial factor that its effects remain unaltered whether or not the influences of mother's age at birth and birth order are controlled. Infant and child mortality in Bangladesh can be expected to decline considerably if successive births can be spaced by an interval of at least 1.5 years. Child spacing seems to be the major factor requiring program attention. The effects of mother's education and place of residence on infant and child mortality are independent of the effects of maternal age at birth, birth order, and the preceding birth interval. The higher survival chances of children of educated mothers resulted neither through the age at which childbearing started nor through birth spacing but are likely to be related to their smaller family size and to other non-maternal proximate determinants of early mortality.     

Fungal assisted bio-treatment of environmental pollutants with comprehensive emphasis on noxious heavy metals: Recent updates

In the present time of speedy developments and industrialization, heavy metals are being uncovered in aquatic environment and soil via refining, electroplating, processing, mining, metallurgical activities, dyeing and other several metallic and metal based industrial and synthetic activities. Heavy metals like lead (Pb), mercury (Hg), cadmium (Cd), arsenic (As), Zinc (Zn), Cobalt (Co), Iron (Fe), and many other are considered as seriously noxious and toxic for the aquatic environment, human, and other aquatic lives and have damaging influences. Such heavy metals, which are very tough to be degraded, can be managed by reducing their potential through various processes like removal, precipitation, oxidation–reduction, bio-sorption, recovery, bioaccumulation, bio-mineralization etc. Microbes are known as talented bio-agents for the heavy metals detoxification process and fungi are one of the cherished bio-sources that show noteworthy aptitude of heavy metal sorption and metal tolerance. Thus, the main objective of the authors was to come with a comprehensive review having methodological insights on the novel and recent results in the field of mycoremediation of heavy metals. This review significantly assesses the potential talent of fungi in heavy metal detoxification and thus, in environmental restoration. Many reported works, methodologies and mechanistic sights have been evaluated to explore the fungal-assisted heavy metal remediation. Herein, a compact and effectual discussion on the recent mycoremediation studies of organic pollutants like dyes, petroleum, pesticides, insecticides, herbicides, and pharmaceutical wastes have also been presented.     

An overview of synthetic methods and applications of photoluminescence properties of carbon quantum dots

Carbon quantum dots (CQDs) are promising carbonaceous nanomaterials fortuitously discovered in 2004. CQDs are the rising stars in the nanotechnology ensemble because of their unique properties and widespread applications in sensing, imaging, medicine, catalysis, and optoelectronics. CQDs are notable for their excellent solubility and effective luminescence and, as a result, they are also known as carbon nanolights. Many strategies are used for the efficient and economical preparation of CQDs; however, CQDs prepared from waste or green sustainable methods have greater requirements due to their safety and ease of synthesis. Sustainable chemical strategies for CQDs have been developed, emphasizing green synthetic methodologies based on ‘top-down’ and ‘bottom-up’ approaches. This review summarizes many such studies relevant to the development of sustainable methods for photoluminescent CQDs. Furthermore, we have emphasized recent advances in CQDs' photoluminescence applications in chemical and biological fields. Finally, a brief overview of synthetic processes using the green source and their associated applications are tabulated, providing a clear understanding of the new optoelectronic materials.     

Maturation-dependent goat epididymal sperm autoagglutination and its inhibition by a glycoprotein factor.

The maturing goat epididymal spermatozoa were isolated from different segments of epididymis and these cells dispersed in a modified Ringer's solution, were incubated at 37 degrees C for 60 min to evaluate their autoagglutination efficacy. Distal corpus-epididymal spermatozoa specifically showed high order of head-to-head autoagglutination property whereas all other sperm cells did not show any detectable aggregation. The goat epididymal plasma has been shown to possess an anti-agglutinin that markedly inhibits sperm agglutination phenomenon and also dissociates the cells from the sperm clusters. Epididymal plasma is the most potent source of the anti-agglutinin which is a heat-stable specific glycoprotein. Like the autoagglutination phenomenon, the initiation of sperm forward progression also starts in the distal-corpus epididymis. The temporal correlation of these two events suggests that sperm autoagglutination may be a prerequisite for the induction of flagellar motility during the epididymal maturity of male gametes.     

Goat sperm membrane: lectin-binding sites of sperm surface and lectin affinity chromatography of the mature sperm membrane antigens.

The cell surface glycoproteins of goat epididymal maturing spermatozoa have been investigated using lectins as surface probes that interact with specific sugars with high affinity. Concanavalin A (ConA) and wheat-germ agglutinin (WGA) showed high affinity for mature cauda epididymal sperm agglutination, whereas RCA2, kidney beans lectin and peanut agglutinin caused much lower or little agglutination of the cells. The mature sperm exhibited markedly higher efficacy than the immature caput epididymal sperm for binding both ConA and WGA, as evidenced by sperm agglutination and the binding of the fluorescence isothiocyanate (FITC)-labelled lectins. FITC-ConA binds uniformly to the entire mature sperm surface whereas FITC-WGA binds to the acrosomal cap region of the head. The FITC-RCA2 mainly labelled the posterior head of mature cauda sperm. However, no WGA-specific glycoprotein receptors could be detected in sperm plasma membrane (PM) by WGA-Sepharose affinity chromatography. The data implied that the epididymal sperm maturation is associated with a marked increase in the ConA/WGA receptors and that WGA receptors may be glycolipids rather than glycoproteins. Analysis of the ConA receptors of cauda sperm PM identified by ConA-Sepharose affinity chromatography and subsequent resolution in SDS-PAGE demonstrated the presence of five glycopolypeptides of different concentrations (98, 96, 43, 27 and 17 kDa) of goat sperm membrane. The immunoblot of these ConA-specific glycopeptides with anti-sperm membrane antiserum showed that 98- and 96-kDa receptors are immunoresponsive.     

Molecular and morphologic changes during the epithelial-mesenchymal transformation of palatal shelf medial edge epithelium in vitro.

The fate of the medial edge epithelial (MEE) cells during palatal fusion has been proposed to be either programmed cell death or epithelial-mesenchymal transformation. Vital cell labeling techniques were used to mark the MEE and observe their fate during palatal fusion in vitro. Fetal mouse palatal shelves were labeled with Dil and allowed to proceed through fusion while maintained in an organ culture system. The tissues were examined at several stages of palatal fusion for the distribution of Dil, presence of specific antigens and ultrastructural appearance of the cells. The MEE labeled with Dil occupied a midline position at all stages of palatal fusion. Initially the cells had keratin intermediate filaments and were separated from the underlying mesenchyme by an intact basement membrane. During the process of fusion the basement membrane was degraded and the Dil-labeled MEE were in contact with the mesenchymal-derived extracellular matrix. In the late stages of fusion the Dil-labeled MEE altered their cellular morphology, had vimentin intermediate filaments, and were not associated with an identifiable basement membrane. Dil-labeled cells, without an epithelial phenotype, remained present in the midline of the completely fused palate. The data indicate that the MEE did not die but underwent a phenotypic transformation to viable mesenchymal cell types, which were retained in the palatal mesenchyme.     

Inhibition of cardiac phosphatidylethanolamine N-methylation by oxygen free radicals

This study was undertaken to examine the effects of oxygen free radicals on phosphatidylethanolamine (PE) N-methylation in rat heart sarcolemmal (SL) and sarcoplasmic reticular (SR) membranes. Three catalytic sites involved in the sequential methyl transfer reaction were studied by assaying the incorporation of radiolabeled methyl groups from S-adenosyl-L-methionine (0.055, 10, and 150 microM) into SL or SR PE molecules under optimal conditions. In the presence of xanthine + xanthine oxidase (superoxide anion radicals generating system), PE N-methylation was inhibited at site I and III in the heavy SL fraction isolated by the hypotonic shock-LiBr treatment method. In the light SL fraction isolated by sucrose-density gradient, a significant inhibition of PE N-methylation was seen at all three sites. These inhibitory effects of xanthine + xanthine oxidase on PE N-methylation were prevented by the addition of superoxide dismutase. Hydrogen peroxide showed a significant inhibition of PE N-methylation at site I in the heavy SL fraction, and at site I and II in the light SL fraction. Catalase blocked the inhibitory effects of hydrogen peroxide. The effects of both xanthine + xanthine oxidase and hydrogen peroxide on the SR membranes were similar to those seen for the heavy SL fraction. These results suggest that, in addition to lipid peroxidation, the oxygen free radicals may affect the function of cardiac membranes by decreasing the phospholipid N-methylation activity.     

Genetic studies of human apolipoproteins. XIII. Quantitative polymorphism of apolipoprotein C-III in the Mayans of the Yucatán Peninsula

Apolipoprotein C-III (APO C-III) is a structural component of very-low-density and high-density lipoprotein particles and is an inhibitor of lipoprotein lipase. In a study of genetic variation of apolipoproteins in the Mayan population of the Yucatán peninsula, we observed a quantitative polymorphism in APO C-III levels. This polymorphism is expressed as variation in immunoblot staining intensity following isoelectric focusing and as variation in plasma levels of APO C-III determined by radial immunodiffusion. This variation is consistent with the presence in Mayans of an allele associated with low levels of plasma APO C-III which we have designated APO C-III*D. Analysis of the distribution of APO C-III levels yields a gene frequency estimate for the deficiency allele of 0.59. There is a significant positive correlation between total plasma APO C-III levels and total plasma cholesterol and triglyceride levels, the lowest levels of cholesterol and triglycerides being seen in individuals homozygous for the deficiency allele. This observation is consistent with the proposed role of APO C-III in lipoprotein metabolism. Family data to determine whether this deficiency allele is due to mutation at the APO C-III structural locus were not available. However, molecular analysis using cloned probes from the APO A-I/C-III/A-IV gene cluster revealed no gross DNA rearrangement or deletion of sequences in this region in homozygous deficient individuals.     

Genetic epidemiological study of blood pressure in a sedentary rural agricultural population of West Bengal, India

To study the genetic epidemiology of blood pressure (BP), data on 78 families were collected from a sedentary agricultural population of eastern India. The general levels of both systolic (SBP) and diastolic (DBP) blood pressures are found to be low (mean SBP = 106.41 mm Hg; mean DBP = 63.94 mm Hg). Trends of blood pressures with age are similar to those reported earlier (e.g., in the Framingham study). Environmental variables--e.g., occupation and tobacco use--do not have any direct significant effect on blood pressure variability in this population. Path analysis of family data shows a highly significant familial aggregation and yields a genetic heritability (maximum) estimate of 0.3 for both SBP and DBP. Sib-sib and mother-child correlation estimates are, respectively, 0.3 and 0.25. Father-child correlation estimates are 0.13 for SBP and near zero for DBP. A pseudopolygenic model yields the best fit to the data on SBP, while for DBP a proper resolution of various models considered could not be obtained.