Female preference for blue in Japan blue guppies (Poecilia reticulata)

Guppies (Poecilia reticulata) are widely used as a model species in mate choice studies. Although native to South America, guppies have been introduced to natural water bodies in disparate regions of the globe. Here, for the first time, we examine guppies from one such introduced population in Japan where males have evolved a predominantly blue color pattern. Previous studies of wild-type guppies have shown blue to play a relatively minor role in the mate choice decisions of females compared to other traits, such as orange, and the importance of blue is not universally supported by all studies. The Japanese population therefore presents an ideal opportunity to re-examine the potential significance of blue as a mate choice cue in guppies. Mate choice experiments, in which female Japan blue guppies were given a choice between pairs of males that differed in their area of blue coloration but were matched for other traits, revealed that females prefer males with proportionately larger amounts of blue in their color patterns. We discuss possible factors, including sexual and ecological selection, which may have led to the evolution of unusually large areas of blue at the expense of other colors in Japan blue guppies. However, further studies are needed to distinguish between these scenarios.     

Biosensors for the Detection of Organophosphorous Pesticides

Cytokinins are master regulators of plant growth and development. They are involved in the regulation of many important physiological and metabolic processes. Recent progress in cytokinin research at the molecular level, including identification of related genes and cytokinin receptors, plus elucidation of signal transduction, has greatly increased our understanding of cytokinin actions. Although still in its infant stage, molecular breeding of crops with altered cytokinin metabolism, when combined with the transgenic approach, has shown very promising potential for application to agriculture. In this review we briefly introduce recent progress in cytokinin molecular biology, discuss applications of cytokinin genetic engineering to agriculture, and present implications and future research directions.     

Serum albumin acts as a shuttle to enhance cholesterol efflux from cells

An important mechanism contributing to cell cholesterol efflux is aqueous transfer in which cholesterol diffuses from cells into the aqueous phase and becomes incorporated into an acceptor particle. Some compounds can enhance diffusion by acting as shuttles transferring cholesterol to cholesterol acceptors, which act as cholesterol sinks. We have examined whether particles in serum can enhance cholesterol efflux by acting as shuttles. This task was accomplished by incubating radiolabeled J774 cells with increasing concentrations of lipoprotein-depleted sera (LPDS) or components present in serum as shuttles and a constant amount of LDL, small unilamellar vesicles, or red blood cells (RBC) as sinks. Synergistic efflux was measured as the difference in fractional efflux in excess of that predicted by the addition of the individual efflux values of sink and shuttle alone. Synergistic efflux was obtained when LPDS was incubated with cells and LDL. When different components of LPDS were used as shuttles, albumin produced synergistic efflux, while apoA-I did not. A synergistic effect was also obtained when RBC was used as the sink and albumin as shuttle. The previously observed negative association of albumin with coronary artery disease might be linked to reduced cholesterol shuttling that would occur when serum albumin levels are low.     

Unravelling the beneficial role of microbial contributors in reducing the allelopathic effects of weeds

The field of allelopathy is one of the most fascinating but controversial processes in plant ecology that offers an exciting, interdisciplinary, complex, and challenging study. In spite of the established role of soil microbes in plant health, their role has also been consolidated in studies of allelopathy. Moreover, allelopathy can be better understood by incorporating soil microbial ecology that determines the relevance of allelopathy phenomenon. Therefore, while discussing the role of allelochemicals in plant–plant interactions, the dynamic nature of soil microbes should not be overlooked. The occurrence and toxicity of allelochemicals in soil depend on various factors, but the type of microflora in the surroundings plays a crucial role because it can interfere with its allelopathic nature. Such microbes could be of prime importance for biological control management of weeds reducing the cost and ill effects of chemical herbicides. Among microbes, our main focus is on bacteria—as they are dominant among other microbes and are being used for enhancing crop production for decades—and fungi. Hence, to refer to both bacteria and fungi, we have used the term microbes. This review discusses the beneficial role of microbes in reducing the allelopathic effects of weeds. The review is mainly focused on various functions of bacteria in (1) reducing allelopathic inhibition caused by weeds to reduce crop yield loss, (2) building inherent defense capacity in plants against allelopathic weed, and (3) deciphering beneficial rhizospheric process such as chemotaxis/biofilm, degradation of toxic allelochemicals, and induced gene expression.     

Deciphering the role of charge,hydration, and hydrophobicity for cytotoxic activities and membrane interactions of bile acid based facial amphiphiles

We synthesized four cationic bile acid based facial amphiphiles featuring trimethyl ammonium head groups. We evaluated the role of these amphiphiles for cytotoxic activities against colon cancer cells and their membrane interactions by varying charge, hydration and hydrophobicity. The singly charged cationic Lithocholic acid based amphiphile (LCA-TMA₁) is most cytotoxic, whereas the triply charged cationic Cholic acid based amphiphile (CA-TMA₃) is least cytotoxic. Light microscopy and Annexin-FITC assay revealed that these facial amphiphiles caused late apoptosis. In addition, we studied the interactions of these amphiphiles with model membrane systems by Prodan-based hydration, DPH-based anisotropy, and differential scanning calorimetry. LCA-TMA₁ is most hydrophobic with a hard charge causing efficient dehydration and maximum perturbations of membranes thereby facilitating translocation and high cytotoxicity against colon cancer cells. In contrast, the highly hydrated and multiple charged CA-TMA₃ caused least membrane perturbations leading to low translocation and less cytotoxicity. As expected, Chenodeoxycholic acid and Deoxycholic acid based amphiphiles (CDCA-TMA₂, DCA-TMA₂) featuring two charged head groups showed intermediate behavior. Thus, we deciphered that charge, hydration, and hydrophobicity of these amphiphiles govern membrane interactions, translocation, and resulting cytoxicity against colon cancer cells.     

Increase in Nitrate Reductase Activity in Bean Leaves by Light Involves a Regulator Protein

Nitrate reductase activity, assayed either in vivo or in vitro was considerably higher in bean (Phaseolus vulgaris L.) leaves from 7-day-old light grown seedlings than those from dark grown, both in the absence as well as presence of nitrate. Cytochrome c reductase activity was however similar in both regimes, while peroxidase was lower in light than in dark. The light stimulated increase in nitrate reductase activity in leaf segments from dark grown seedlings was inhibited by cycloheximide, DNP, chloramphenicol, and sodium tungstate and was unaffected by lincomycin and DCMU. Under similar conditions, the increase in total chlorophyll was inhibited completely by cycloheximide and DNP, partially by chloramphenicol and lincomycin, and was unaffected by tungstate and DCMU. A supply of 1~5 mm reduced glutathione increased enzyme activity in the dark and also to some extent in light. The substrate induction of enzyme activity started after a lag of one hr in light or dark and continued for either 5 hr in the dark or 8 hr in light. Two proteinaceous inhibitors (Factors I and II) of nitrate reductase were isolated by ammonium sulfate precipitation and Sephadex gel filtration. The amount of Factor I was higher in the dark than in light. The amount and activity of Factor II was however, almost equal in light and dark. The inhibition of enzyme activity by these inhibitors increased with their concentration. It is proposed that light increases nitrate reductase activity by decreasing the amount of a nitrate reductase inhibitor.