Crystal structure of the extracellular segment of integrin alpha Vbeta3 in complex with an Arg-Gly-Asp ligand

The structural basis for the divalent cation-dependent binding of heterodimeric alphabeta integrins to their ligands, which contain the prototypical Arg-Gly-Asp sequence, is unknown. Interaction with ligands triggers tertiary and quaternary structural rearrangements in integrins that are needed for cell signaling. Here we report the crystal structure of the extracellular segment of integrin alphaVbeta3 in complex with a cyclic peptide presenting the Arg-Gly-Asp sequence. The ligand binds at the major interface between the alphaV and beta3 subunits and makes extensive contacts with both. Both tertiary and quaternary changes are observed in the presence of ligand. The tertiary rearrangements take place in betaA, the ligand-binding domain of beta3; in the complex, betaA acquires two cations, one of which contacts the ligand Asp directly and the other stabilizes the ligand-binding surface. Ligand binding induces small changes in the orientation of alphaV relative to beta3.     

Nanotubular highways for intercellular organelle transport

Cell-to-cell communication is a crucial prerequisite for the development and maintenance of multicellular organisms. To date, diverse mechanisms of intercellular exchange of information have been documented, including chemical synapses, gap junctions, and plasmodesmata. Here, we describe highly sensitive nanotubular structures formed de novo between cells that create complex networks. These structures facilitate the selective transfer of membrane vesicles and organelles but seem to impede the flow of small molecules. Accordingly, we propose a novel biological principle of cell-to-cell interaction based on membrane continuity and intercellular transfer of organelles.     

Effect of water temperature on the physiology of fish spermatozoon function: a brief review

Motility is a key factor in function of the spermatozoon and determines semen quality and fertilizing capacity. Effective motility occurs when sperm is diluted in a swimming solution, the adequacy of which is determined by factors varying according to fish species. Spermatozoon motility rate and velocity, as well as duration of the motility period, are influenced by the temperature of the water in which broodfish are held. Increase in temperature of swimming medium beyond the optimal increases cell metabolism, leading to an increase in velocity with rapid depletion of energy resources, promoting early cessation of movement. The aim of this review was to discuss current information on the influence of temperature on quantitative spermatozoon properties, which could affect sperm function. Our findings provide a greater understanding of fish sperm physiology and a biological foundation for the further development of spermatozoon motility investigations as well as reproduction technologies.     

Evaluation of HYDRUS-2D model to simulate the loss of nitrate in subsurface controlled drainage in a physical model scale of paddy fields

Agriculture is a major source of nitrogen usage and release to environment. Due to the effect of water movement on solute transport, investigating the effect of different management scenarios of irrigation and drainage could be useful for reducing nitrate loss and environmental pollution. This study is a scientific attempt to assess the ability of HYDRUS-2D model to simulate the effect of subsurface controlled drainage on nitrate loss of paddy fields. So, two physical models with difference in depth of subsurface controlled drainage (40 and 60 cm) were constructed. The tanks were filled with loam silty soil texture and then transplanted rice. 90 kg/ha potassium nitrate fertilizer was added in two stages of rice growth. Mid-season drainage was applied 26 days after transplantation. After 17 days, drains were closed again and applied flooded irrigation with 5-cm water stagnant layer above soil surface. During experiment, nitrate concentration of drain water was measured. HYDRUS-2D was calibrated with measured data in 60 cm drain depth and validated with 40 cm drain depth. HYDRUS-2D could simulate nitrate concentration with the coefficient of determination 0.95 and 0.89 in calibration and validation stages, respectively. The comparison between the volume of drain water and nitrate concentration from the drains in the depths of 40 and 60 cm indicated lower nitrate load in depth of 40 cm. The results obtained proved that the presence of hardpan layer in depth of 25 cm rather than the absence of it causes increase in 3 % of average nitrate concentration and reduce in 17 % of water discharge.     

Cultivated emmer wheat (Triticum dicoccon Schrank), an old crop with promising future: a review

Cultivated emmer wheat, Triticum dicoccon Schrank, a tetraploid species with hulled grain, has been largely cultivated during seven millennia in the Middle-East, Central and West Asia, and Europe. It has been largely replaced by hulless species and is now a minor crop, with the exception of some countries like India, Ethiopia and Yemen, where its grain is used for preparing traditional foods. Nutritional qualities and specific taste and flavor of emmer wheat products have led to a recent development of the cultivation in some European countries. Emmer wheat also possesses valuable traits of resistance to pests and diseases and tolerance to abiotic stresses and is increasingly used as a reservoir of useful genes in wheat breeding. In the present article, a review concerning taxonomy, diversity and history of cultivation of emmer wheat is reported. Grain characteristics and valuable agronomic traits are described. Some successful examples of emmer wheat utilization for the development of durum or bread wheat cultivars are examined, and the perspectives in using emmer wheat as health food and for the development of new breeding germplasm are discussed.     

Technical efficiency of cage fish farming in Peninsular Malaysia: a stochastic frontier production approach

The study estimates technical efficiency and investigates the factors affecting the technical inefficiency of cage fish farming in Peninsular Malaysia. The study employs the stochastic frontier function to estimate a production frontier and technical inefficiency model. The data were collected using standard structured questionnaires completed by sample cage fish farmers in the study area. The result reveals an estimated mean technical efficiency score of 0.79, implying that the sample fish farmers are operating 21% below the production frontier and thus, there is room for improvement. The production function involves the use of one output and four inputs, which are stocking density, feed, labour and other relevant production costs. The coefficients of all the inputs have positive signs and statistically significant impacts on the output. The output elasticity associated with stocking density is the highest (0.634), followed by feed (0.317). The null hypotheses that the technical inefficiency effects are absent from the model and that the combined exogenous variables do not influence inefficiency are strongly rejected. The individual's null hypotheses of no age effect, no experience effect, no education effect, no species effect, no extension services effect, no workshop attended effect and no diseases effect on technical inefficiency are all rejected at different levels of statistical significance.     

Vertical transmission of sublethal granulovirus infection in the tobacco caterpillar <Emphasis Type="Italic">Spodoptera litura</Emphasis>

Larvae that survived sublethal infection of Spodoptera litura granulovirus (SlGV) as 4th and 5th instars led to an increase in the larval period of treated larvae when compared with control. While pupal period and pupal weight remained unaffected, a significant alteration in sex ratio was observed. Although survivor moths could mate successfully, there was a significant reduction in the proportion of ovipositing females in treated larvae as compared with control. A significant reduction in fecundity of moths emerging from treated larvae was also noticed, but the egg viability was never influenced by the treatment. However, there was a significant increase in progeny mortality in treated larvae over control. The offspring mortality in survivors increased up to three subsequent generations but not thereafter. Hence, repeated field applications of inoculum are required. The implication of the present findings in terms of reduced fecundity coupled with increased larval development indicates that vertical transmission can lead to increased virus dispersal, both of which would reduce the host's innate capacity for population increase. This is particularly important in S. litura, which is a migratory species and occurs sporadically in a particular agro-ecosystem.