Dynamics of numbers of commercial fish in early ontogenesis in different areas of the Central-Eastern Atlantic

Changes in the quantitative composition of mass fish species at early stages of ontogenesis in different areas of the Central-Eastern Atlantic (CEA) in warm and cold seasons in 1994–2008 were analyzed in the paper. The most widespread representatives of ichthyocenosis of CEA were: European pilchard (Sardina pilchardus), common scad (Trachurus trachurus), round sardinella (Sardinella aurita), and West-African scad (Trachrus trecae). The data obtained indicate that, within the economic zone of Morocco, fluctuations of numbers at early stages of development in European pilchard and common scad are close over the entire water area under consideration (36°–21° N). The regularities of fluctuations of the numbers of ichthyoplankton are similar to the interannual changes in the biomass of fish in the area of Morocco. In the area of Mauritania (21°–16° N), fluctuations of numbers of the early stages of development of commercial fish cannot be unambiguously correlated with changes in the biomass of adult fish. It is known that, in the economic zone of Mauritania, there are Senegal-Mauritanian populations of round sardinella and West-African scad that inhabit waters of different states and are not completely assessed by our surveys. Therefore, no obvious relation was observed between the considered data.     

Species composition and distributional pattern of ichthyoplankton of the Southern Pacific Ocean

Distributional pattern and qualitative composition of ichthyoplankton in waters of the Southern Pacific in September 2002?CJanuary 2003 and in August?CNovember 2009 are analyzed. We noted approximately 70 species of fish pelagic eggs and larvae of fishes belonging to 34 families in this region. Change in distribution of the basic object of commercial fishery of this region, i.e., Peruvian-Chilean jack mackerel Trachurus murphyi, in early ontogenesis are considered in detail. The obtained data on the species composition, distribution, and abundance of ichthyoplankton in this region are compared with the results of investigations in the past years. The spawning biomass of jack mackerel is also estimated in the work by the amount of the eggs spawned by females in the places of their greatest concentrations.     

Four-scale description of membrane sculpting by BAR domains

BAR domains are proteins that sense and sculpt curved membranes in cells, furnishing a relatively well-studied example of mechanisms employed in cellular morphogenesis. We report a computational study of membrane bending by BAR domains at four levels of resolution, described by 1), all-atom molecular dynamics; 2), residue-based coarse-graining (resolving single amino acids and lipid molecules); 3), shape-based coarse-graining (resolving overall protein and membrane shapes); and 4), a continuum elastic membrane model. Membrane sculpting performed by BAR domains collectively is observed in agreement with experiments. Different arrangements of BAR domains on the membrane surface are found to lead to distinct membrane curvatures and bending dynamics.     

An Experimental and Computational Study of Effects of Microtubule Stabilization on T-Cell Polarity

T-killer cells eliminate infected and cancerous cells with precision by positioning their centrosome near the interface (immunological synapse) with the target cell. The mechanism of centrosome positioning has remained controversial, in particular the role of microtubule dynamics in it. We re-examined the issue in the experimental model of Jurkat cells presented with a T cell receptor-binding artificial substrate, which permits controlled stimulation and reproducible measurements. Neither 1-µM taxol nor 100-nM nocodazole inhibited the centrosome positioning at the “synapse” with the biomimetic substrate. At the same time, in micromolar taxol but not in nanomolar nocodazole the centrosome adopted a distinct peripheral rather than the normally central position within the synapse. This effect was reproduced in a computational energy-minimization model that assumed no microtubule dynamics, but only a taxol-induced increase in the length of the microtubules. Together, the experimental and computational results indicate that microtubule dynamics are not essential for the centrosome positioning, but that the fit of the microtubule array in the deformed body of the conjugated T cell is a major factor. The possibility of modulating the T-cell centrosome position with well-studied drugs and of predicting their effects in silico appears attractive for designing anti-cancer and antiviral therapies.     

Plants experiencing chronic internal exposure to ionizing radiation exhibit higher frequency of homologous recombination than acutely irradiated plants

Ionizing radiation (IR) is a known mutagen responsible for causing DNA strand breaks in all living organisms. Strand breaks thus created can be repaired by different mechanisms, including homologous recombination (HR), one of the key mechanisms maintaining genome stability [A. Britt, DNA damage and repair in plants, Annu. Rev. Plant. Phys. Plant Mol. Biol., 45 (1996) 75-100; H. Puchta, B. Hohn, From centiMorgans to basepairs: homologous recombination in plants, Trends Plant Sci., 1 (1996) 340-348.]. Acute or chronic exposure to IR may have different influences on the genome integrity. Although in a radioactively contaminated environment plants are mostly exposed to chronic pollution, evaluation of both kinds of influences is important. Estimation of the frequency of HR in the exposed plants may serve as an indication of genome stability.We used previously generated Arabidopsis thaliana and Nicotiana tabacum plants, transgenic for non-active versions of the beta-glucoronidase gene (uidA) [P. Swoboda, S. Gal, B. Hohn, H. Puchta, Intrachromosomal homologous recombination in whole plants, EMBO J., 13 (1994) 484-489; H. Puchta, P. Swoboda, B. Hohn, Induction of homologous DNA recombination in whole plants, Plant, 7 (1995) 203-210.] serving as a recombination substrate, to study the influence of acute and chronic exposure to IR on the level of HR as example of genome stability in plants. Exposure of seeds and seedlings to 0.1 to 10.0 Gy 60Co resulted in increased HR frequency, although the effect was more pronounced in seedlings. For the study of the influence of chronic exposure to IR, plants were grown on two chemically different types of soils, each artificially contaminated with equal amounts of 137Cs. We observed a strong and significant correlation between the frequency of HR in plants, the radioactivity of the soil samples and the doses of radiation absorbed by plants (in all cases r0.9, n=6, P<0.05). In addition, we noted that plants grown in soils with different chemical composition, but equal radioactivity, exhibited different levels of HR, dependent upon the absorbed dose of radiation. Remarkably, we observed a much higher frequency of HR in plants exposed to chronic irradiation when compared to acutely irradiated plants. Although acute application of 0.1-0.5 Gy did not lead to an increase of frequency of HR, the chronic exposure of the plants to several orders of magnitude lower dose of 200 muGy led to a 5-6-fold induction of the frequency of HR as compared to the control.     

First Philippine record of the parasitoid,Comperiella sp. (Hymenoptera: Encyrtidae): a potential biocontrol agent against Aspidiotus rigidus (Hemiptera: Diaspididae)

The encyrtid genus Comperiella Howard has so far not been reported in the Philippines, where there is currently an outbreak of the coconut scale insect Aspidiotus rigidus Reyne particularly in the southern parts of the island of Luzon and in some areas in Mindanao. Among Comperiella species, only C. unifasciata Ishii has been reported as a parasitoid of A. rigidus. We report not only new sightings of this parasitoid genus in the Philippines from surveys conducted in parts of the provinces of Laguna and Batangas, but also the discovery of a possibly new species that, like C. unifasciata, has been found to parasitize A. rigidus at a high rate. These findings have presented a potential of biological control against the coconut scale insect problem that has threatened the coconut industry in the country.