Lipoxygenase-generated hydroperoxides account for the nonphysiological features of ethylene formation from 1-aminocyclopropane-1-carboxylic acid by microsomal membranes of carnations

Several lines of evidence indicate that the conversion of 1-aminocyclopropane-1-carboxylic acid (ACC) to ethylene by microsomal membranes from carnation flowers is attributable to hydroperoxides generated by membrane-associated lipoxygenase (EC 1.13.11.12). As the flowers senesce, the capability of isolated microsomal membranes to convert ACC to ethylene changes. This pattern of change, which is distinguishable from that for senescing intact flowers, shows a close temporal correlation with levels of lipid hydroperoxides formed by lipoxygenase in the same membranes. Specific inhibitors of lipoxygenase curtail the formation of lipid hydroperoxides and the production of ethylene from ACC to much the same extent, whereas treatment of microsomes with phospholipase A₂, which generates fatty-acid substrates for lipoxygenase, enhances the production of hydroperoxides as well as the conversion of ACC to ethylene. Lipoxygenase-generated lipid hydroperoxides mediate the conversion of ACC to ethylene in a strictly chemical system and also enhance ethylene production by microsomal membranes. The data collectively indicate that the in-vitro conversion ACC to ethylene by microsomal membranes of carnation flowers is not reflective of the reaction mediated by the native in-situ ethylene-forming enzyme.Abbreviations ACC 1-aminocyclopropane-1-carboxylic acid - EDTA ethylenediaminetetraacetic acid     

Regulation of DNA replication by homopurine/homopyrimidine sequences

The simple repeating homopurine/homopyrimidine sequences dispersed throughout many eukaryotic genomes are known to form triple helical structures comprising three-stranded and single-stranded DNA. Several lines of evidence suggest that these structures influence DNA replication in cells. Homopurine/homopyrimidine sequences cloned into simian virus 40 (SV40) or SV40 origin-containing plasmids caused a reduced rate of DNA synthesis due to the pausing of replication forks. More prominent arrests were observed in in vitro experiments using single-stranded and double-stranded DNA with triplex-forming sequences. Nucleotides unable to form triplexes when present in the template DNA or when incorporated into the nascent strand prevented termination. Similarly, mutations destroying the triplex potential did not cause arrest while compensatory mutations restoring triplex potential restored it. These and other observations from a number of laboratories indicating that homopurine/homopyrimidine sequences act as arrest signals in vitro and as pause sites in vivo during replication fork movement suggest that these naturally occurring sequences play a regulatory role in DNA replication and gene amplification.     

Phospholipid vesicle aggregation induced by human myelin basic protein

Human myelin basic protein isolated from the brains of individuals who died with multiple sclerosis was more potent in inducing the aggregation of egg phosphatidylcholine vesicles than was the basic protein isolated from the brains of normal individuals. The portion of myelin basic protein which bound to egg phosphatidylcholine vesicles was separated from the free protein by sucrose density gradient centrifugation. Similar amounts of basic protein from normal or from multiple sclerosis brains are bound to the lipid and no consistent differences in the N^G, N^G dimethyl-arginine content of the protein fractions have been found.     

Influence of sowing windows and genotypes on growth,radiation interception,conversion efficiency and yield of guar

Crop growth largely depends on radiation. Radiation is the main impetus for photosynthesis and movement of photosynthates from source to sink. Therefore, identification of the optimum sowing windows and suitable cultivars for efficient utilization of radiation is of prime importance. A field study was conducted in red clay soil during 2014 and 2015 Kharif season and the treatments consisted of three genotypes and three sowing windows by using randomized complete block design with three replications. The effect of genotypes and sowing windows was found significant with respect to number of trifoliate leaves, leaf area ratio, dry matter production, grain numbers, pod length, test weight, grain yield, and stover yield of guar during 2014 as compared to 2015 sown crop. Statistically significant plant height, number of trifoliate leaves, number of branches, leaf area ratio, absolute growth rate, leaf area index, dry matter, grain number, pod length, grain yield, stover yield and a higher cumulative radiation interception were recorded with 15th August sown crop as compared to other sowing windows. The plant height, number of trifoliate leaves, number of branches, leaf area ratio, absolute growth rate, leaf area index, dry matter, grain number, pod length, grain yield, stover yield and maximum cumulative interception of radiation were significant with RGC-1003 as compared to RGC-936 and HG-365. It is observed that the incident PAR to dry matter accumulation conversion efficiency was varied with cultivars and different sowing windows which ranges from 0.74 g MJ⁻¹ to 0.79 g MJ⁻¹.     

Quantitative structure-activity relationship study of novel rhinacanthins and related naphthoquinone esters as anticancer agents

Abstract

GPR119 is a promising target for discovery of anti-type 2 diabetes mellitus agents. We described the optimisation of a novel series of pyrimido[5,4-b][1,4]oxazine derivatives as GPR119 agonists. Most designed compounds exhibited good agonistic activities. Among them, compound 10 and 15 demonstrated the potent EC₅₀ values (13 and 12?nM, respectively) and strong inherent activities. Moreover, significant hypoglycaemic effect of compound 15 was observed by reducing the blood glucose AUC_0–2h at the dose of 30?mg/kg, which is stronger than Vildagliptin (23.4% reduction vs. 17.9% reduction).     

Tebufenozide disrupts ovarian development and function in silkmoths

Adult development and production of up to 400 eggs within the pupal case of female silkmoths are both dependent on 20-hydroxyecdysone (20E), the steroid hormone of insects. When adult development was initiated with tebufenozide, the non-steroidal ecdysteroid agonist, instead of 20E, full development of all epidermal tissues like the wing was witnessed, but ovarian growth and egg formation was minimal. Administration of tebufenozide to female pharate adults caused disruption of the follicular epithelium, produced nurse cell damage, and inhibited oogenesis. Reduced ability to synthesize RNA and protein accompanied these tebufenozide induced morphological disturbances of the follicles. In vivo accumulation of vitellogenin (Vg) from the hemolymph was reduced in tebufenozide treated female ovaries as well as their ability to accumulate Vg in vitro. Determination of protein staining intensity and antibody reactivity of Vg pointed out that hemolymph Vg level remained fairly constant all through adult development whether induced by 20E or tebufenozide. Measurement of hemolymph volumes and hemolymph Vg levels of control and experimental animals allowed us to conclude that egg development involves the uptake of all the hemolymph proteins and not Vg alone. The loss of hemolymph that accompanies egg maturation was considerably reduced in tebufenozide initiated female pharate adults. 20E could not overcome ovarian growth inhibitory effects of tebufenozide. Dual mechanisms, one involving ecdysteroid antagonist action at the beginning of development, and the other unrelated to that function during heightened egg formation, are needed explain the biphasic inhibitory actions of tebufenozide on silkmoth ovaries.     

Understorey structure and refuges from predators influence habitat use by a small ungulate, the Indian chevrotain (Moschiola indica) in Western Ghats, India

The availability of refuges from predators and high quality food are thought to determine habitat use in small ungulates. We tested this hypothesis on habitat use by the Indian chevrotain in a tropical rainforest in the Western Ghats, using pellet-groups to infer habitat use. Between December 2009 and April 2010, we sampled 204 grids of 50 m × 50 m with four spatial replicates in each, using occupancy framework. We quantified refuges such as fallen logs and boulders, understorey complexity, and noted the presence of fruiting trees in the grid. Detection probability, p, of pellet-groups was estimated at 0.61. The naive estimate of occupancy was 0.52, which increased to 0.73 when p was accounted for. Out of eight candidate models compared using AIC_C, the one with the number of refuges and understorey complexity was the best model. Both covariates had non-zero positive slopes. Fruiting trees occurred very infrequently and did not influence habitat use, perhaps because the chevrotain fed more on buds, shoots and young leaves during the dry period covered by this study. The strong influence of understorey complexity on habitat use was perhaps also due to the abundance of these food items. These results highlight the need to control human use that adversely impacts the availability of refuges and understorey complexity such as removal of fallen logs and rattans. This study also demonstrates the application of the occupancy approach in the study of small and elusive ungulates.