The microRNA pathway controls germ cell proliferation and differentiation in C. elegans

The discovery of the miRNA pathway revealed a new layer of molecular control of biological processes. To uncover new functions of this gene regulatory pathway, we undertook the characterization of the two miRNA-specific Argonaute proteins in Caenorhabditis elegans, ALG-1 and ALG-2. We first observed that the loss-of-function of alg-1 and alg-2 genes resulted in reduced progeny number. An extensive analysis of the germline of these mutants revealed a reduced mitotic region, indicating fewer proliferating germ cells. We also observed an early entry into meiosis in alg-1 and alg-2 mutant animals. We detected ALG-1 and ALG-2 protein expressions in the distal tip cell (DTC), a specialized cell located at the tip of both C. elegans gonadal arms that regulates mitosis-meiosis transition. Re-establishing the expression of alg-1 specifically in the DTC of mutant animals partially rescued the observed germline defects. Further analyses also support the implication of the miRNA pathway in gametogenesis. Interestingly, we observed that disruption of five miRNAs expressed in the DTC led to similar phenotypes. Finally, gene expression analysis of alg-1 mutant gonads suggests that the miRNA pathway is involved in the regulation of different pathways important for germline proliferation and differentiation. Collectively, our data indicate that the miRNA pathway plays a crucial role in the control of germ cell biogenesis in C. elegans.     

Salicylic acids: Local,systemic or inter-systemic regulators?

Salicylic acid is well known phytohormone, emerging recently as a new paradigm of an array of manifestations of growth regulators. The area unleashed yet encompassed the applied agriculture sector to find the roles to strengthen the crops against plethora of abiotic and biotic stresses. The skipped part of integrated picture, however, was the evolutionary insight of salicylic acid to either allow or discard the microbial invasion depending upon various internal factors of two interactants under the prevailing external conditions. The metabolic status that allows the host invasion either as pathogenesis or symbiosis with possible intermediary stages in close systems has been tried to underpin here.     

Quantum chemical study in the direction to design efficient donor-bridge-acceptor triphenylamine sensitizers with improved electron injection

The ground state geometries have been computed by using density functional theory. The excitation energies for dye sensitizers were performed by using time dependant density functional theory. The polarizable continuum model (PCM) has been used for evaluating bulk solvent effects at all stages. The calculations have been carried out in methanol according to the experimental set up. The long-range-corrected functional (PCM-TD-LC-BLYP) underestimate the absorption spectrum of parent molecule while PCM-TDBHandHLYP is in good agreement with the experimental data. The highest occupied molecular orbital (HOMO) is delocalized on TPA moiety while lowest unoccupied molecular orbital (LUMO) is localized on anchoring group, conjugated chain and the benzene ring near to the anchoring group. The LUMO energies of all the investigated dyes are above the conduction band of TiO(2), HOMOs are below the redox couple and HOMO-LUMO energy gaps of studied dyes are smaller compared to TC4. The 1 and 3 are 7 and 12?nm blue shifted while 2 and 4 are 25 and 22?nm red shifted, respectively compared to TC4. The trend of electron injection (ΔG(inject)), relative electron injection (ΔG (r) (inject) ()), and electronic coupling constant (|VRP|) has been observed as 3?>?1?>?4?>?2?>?TC4. The improved ΔG(inject), |VRP| and light harvesting efficiency (LHE) of new designed sensitizers revealed that these materials would be excellent sensitizers. The broken coplanarity between the benzene near anchoring group having LUMO and the last benzene attached to TPA unit in 1-4 consequently would hamper the recombination reaction.     

Expression and identification of folate-sensitive fragile sites in British Suffolk sheep (<Emphasis Type="Italic">Ovis aries</Emphasis>)

An investigation to understand the dynamics and biological significance of fragile site expression, and identification of 5-fluorodeoxyuridine (FUdR) induced chromosomal gaps/breaks, were carried out in an experimental flock of 45 Suffolk sheep. The statistical comparison revealed, highly significant variation in the frequency of chromosomal fragile site expression between control and FUdR cultures. Mean (± S.D.) values for cells with gaps and breaks, or aberrant cell count (AC), and the number of aberrations (NoA) per animal were 2.02 ± 0.34, 2.42 ± 0.48, 13.26 ± 0.85 and 21.87 ± 1.88 (P < 0.01) in control and FUdR cultures, respectively. The comparison of age revealed nonsignificant variation between control and FUdR cultures. The G-band analysis of fragile site data revealed gaps in 29 autosomal and two X-chromosomal bands in the control cultures, whereas FUdR treated cultures scored 78 unstable bands in autosomes of which 56 were significantly fragile. X-chromosomes expressed breaks and gaps in six G-negative bands and five of them (Xq13, Xq15, Xq17, Xq24 and Xq26) were significantly fragile. The distribution comparison of autosomal fragile sites between sex groups did not reveal any significant variation. Female X-chromosomes were significantly more fragile than the male X-chromosomes. The distribution comparison for age groups (lambs versus adults) revealed significantly higher number of fragile bands in adults. Comparison of published data on reciprocal translocations in sheep with the fragile-site data obtained in this study indicated that the break sites of both phenomena were correlated. Similarities were also found between fragile sites and breakpoints of evolutionary significance in family Bovidae.     

Binding of bilirubin with albumin-coupled liposomes: implications in the treatment of jaundice

In the present study, we demonstrated the suitability of liposomes as a method of removing plasma bilirubin in hyperbilirubinemic rats. The liposomes have innate tendency to bind with bilirubin through hydrophobic interaction. Among different types of liposomes, the positively charged liposomes were found to have maximum affinity to free bilirubin. However, the entrapment or coupling of serum albumin on the surface of egg phosphatidylcholine liposomes can render a several-fold increase in their bilirubin binding capacity. The proteoliposomes were able to preferentially bind with bilirubin even in the presence of erythrocytes. Interestingly, these liposomes were found to displace bilirubin bound on the surface of erythrocytes as well. The results of the present study further demonstrate that albumin-bearing liposomes were equally effective in removing plasma bilirubin in experimental jaundiced animals. These observations indicate that liposome-mediated selective homing of excess plasma bilirubin to the liver cells (cf. hepatocytes) may help in the development of safer strategy for the treatment of hyperbilirubinemic conditions in the model animals.     

Glutathione and p53 independently mediate responses against oxidative stress in ES cells.

We have investigated the roles of the antioxidant glutathione and p53 in the response of embryonic stem (ES) cells to oxidative stress. ES cells express gammaGCS, a critical enzyme in glutathione (GSH) biosynthesis. Treatment with the pro-oxidant menadione led to elevation of GSH, a strong apoptotic response and reduced clonogenic survival. Addition of BSO, a specific gammaGCS inhibitor depleted GSH pools and prevented the menadione-induced increase in GSH, sensitizing cells to oxidative insult. Although p53 status had no bearing on either the basal levels of GSH or the menadione-induced GSH response, the levels of menadione-induced apoptosis were reduced in the absence of p53. We conclude that the pathways involving p53 and GSH act independently to protect against the deleterious effects of oxidative damage. Furthermore, the presence of an intact p53 pathway confers a long-term growth advantage post oxidative stress. Thus, in the absence of p53 ES cells bearing genotoxic damage are less likely to be propagated, suggesting that p53-dependent apoptosis acts to limit the deleterious effects of oxidative stress during early development.     

Salinity tolerance in some mangrove species from Pakistan

Growth, ionic and water relations of three mangrove species viz. Avicennia marina, Ceriops tagal and Rhizophora mucronata werestudied in different seawater concentrations (0, 25, 50, 75 and 100%).All mangrove species showed optimal growth at 50% seawater. Relativelymore biomass was accumulated by R. mucronata while C. tagalhad the tallest individuals. Tissue water potential became more negativewith the increase in salinity and stomatal conductance was decreased in allplants. Higher stomatal conductance was noted in R. mucronata,followed by A. marina and C. tagal. Sodium and chloride ionsincreased with the increase in salinity and this accumulation was muchhigher in A. marina.     

The energy budget of Porcellio spinicornis Say (Porcellionidae, Isopoda) under laboratory conditions

The rate of energy flow in Porcellio spinicornis was investigated in a select group of a laboratory population. The consumption, assimilation and production were calculated to be 1 233, 1 002 and 304 cal/year, respectively, in the male, and 1 261, 1 198 and 429 cal/year, respectively, in the female. Ignoring loss due to mortality, and applying the population density of 2 295 m2 in the laboratory colony, the isopod population should consume 2 861.8 kcal m-2 year-1, resulting in an assimilation of 2 524.5 kcal m-2 year-1 and a total productivity of 841.1 kcal m-2 year-1.