Risk screening of the potential invasiveness of non-native aquatic species in Vietnam

Biological Invasions - The impact of non-native species, together with their pervasiveness, necessitates a means of identifying which species are most likely to pose an elevated risk of becoming...     

Classical cumulant dynamics for statistical chemical physics

Abstract

We developed classical cumulant dynamics for statistical mechanics in order to evaluate thermal equilibrium properties of a given system. The equations of motion (EOMs) for momentum and position were formulated together with those for second-order cumulant variables, which are functions of second-order moments. From the Kramers equation, and simplified EOMs were obtained by assuming a stationary state limit. The present method combined with the umbrella integration method was applied to evaluate free energy surface of a seven-particle Morse cluster. With low computational costs, the present approach gave almost equivalent free energy barrier those by conventional classical molecular dynamics.     

Carotenoid pigments in GAC fruit (Momordica cochinchinensis SPRENG)

The carotenoids in Gac fruit (Momordica Cochinchinensis spreng) were analysed by high-performance liquid chromatography (HPLC), and the concentrations of beta-carotene, lycopene, zeaxanthin and beta-cryptoxanthin were measured. Lycopene was found to be predominantly present in the Gac seed membrane at a concentration of up to 380 microg/g of seed membrane. The concentration of lycopene in the Gac seed membrane was about ten-fold higher than that in known lycopene-rich fruit and vegetables, indicating that Gac fruit could be a new and potentially valuable source of lycopene.     

Reproductive biology of the unique mudskipper Periophthalmodon septemradiatus living from estuary to upstream of the Hau River

This study provided new knowledge on reproductive traits of the unique mudskipper Periophthalmodon septemradiatus that is also a potential aquarium pet. Fish specimens were obtained by using fishing rods at the muddy flat in tributaries of the Hau River from August 2017 to July 2018. Data analysis of a collection of 1,504 individuals (930 males and 674 females) showed that the sex ratio of this species was significantly different from the ratio 1:1. As mature gonads were found monthly during the study period, it is suggested that P. septemradiatus is an iteroparous species releasing eggs for a year-round cycle. The fish length at first mature (L_m) showed an increase from estuary to upstream areas. Male P. septemradiatus had higher L_m values than that of females. Likely, the batch fecundity increased from estuary region (5,916 ± 312 SEM eggs) towards upstream area (11,451 ± 953 SEM eggs). The fish total length and weight values had strong positive relationships with batch fecundity, as shown by high determination values (r²), suggesting that batch fecundity increased with fish size. This study provided more information on reproductive biology of P. septemradiatus, which can be utilized for fish population conservation and artificial reproductive study.     

Rhizobium inoculant for soybean [Glycine max (L.) Merrill] in Mekong Delta

Summary Rhizobial inoculation trials were conducted in an acid heavy clay soil in Mekong Delta, Viet Nam, using peat based inoculants produced locally and the commercial granular product of Nitragin CCo., Wisconsin, USA. The pH of these soils ranged from 4.5 to 5.1. Two soybean cultivars, MTD₆ and MTD₁₀, were tested as host plants. There were no significant differences between locally made inoculant treated plants and the uninoculated controls in both cultivars. But, the Nitragin inoculation improved all plant characteristics examined in both cultivars. Grain yields of Nitragin inoculated plants of cultivar MTD₆ and cultivar MTD₁₀ were 6.5 and 5.5 times as much as those of the controls; protein content of grain increased 11 and 16 percent, respectively. Well nodulated plants had shorter life cycles, flowering durations, and days to flowering. The Rhizobium symbiosis resulted in an additional 153 kg grain-N/ha. These studies show that a surface coated commercial multistrain inoculant can be used to successfully grow soybeans in the acid, heavy clay soils of the Mekong Delta.     

Ant and silkworm pupae as convenient diets for the development and reproduction of big-eyed bug Geocoris ochropterus (Hemiptera: Geocoridae)

We investigated the influence of convenient diets on big-eyed bug Geocoris ochropterus. Development and reproduction of G. ochropterus fed on convenient diets of ant pupae Oecophylla smaragdina and silkworm pupae Bombyx mori were examined using aphids Aphis gossypii as the control diet. Results showed that Geocoris ochropterus nymphs completed development to adults on all diets. Total average development period was 35.1 days fed on ant pupae, 35.9 days fed on silkworm pupae, and 36.0 days fed on aphids. Head width, body length, forewing length, and fresh body weight of adults were not affected by diets, except for females reared on ant pupae that were significantly heavier than those fed on aphids. There was no significant difference in offspring sex ratio. Total number of eggs deposited per female fed on ant pupae was significantly larger than when fed on aphids, while eggs laid by females fed on silkworm pupae were significantly longer than eggs laid by females fed on aphids. Results suggest that ant pupae and silkworm pupae could be effectively used for mass rearing of G. ochropterus.     

Identification of orally bioavailable,non-amidine inhibitors of Urokinase Plasminogen Activator (uPA)

In this Letter we report the synthesis and evaluation of a series of non-amidine inhibitors of Urokinase Plasminogen Activator (uPA). Starting from compound 1, a significant change provided compounds in which the amidine, binding in the S1 pocket, was replaced with a primary amine. Further modifications led to the identification of potent, selective, and orally bioavailable uPA inhibitors.     

A rice gene encoding glycosyl hydrolase plays contrasting roles in immunity depending on the type of pathogens

Because pathogens use diverse infection strategies, plants cannot use one-size-fits-all defence and modulate defence responses based on the nature of pathogens and pathogenicity mechanism. Here, we report that a rice glycoside hydrolase (GH) plays contrasting roles in defence depending on whether a pathogen is hemibiotrophic or necrotrophic. The Arabidopsis thaliana MORE1 (M agnaporthe o ryzae re sistance 1) gene, encoding a member of the GH10 family, is needed for resistance against M. oryzae and Alternaria brassicicola, a fungal pathogen infecting A. thaliana as a necrotroph. Among 13 rice genes homologous to MORE1, 11 genes were induced during the biotrophic or necrotrophic stage of infection by M. oryzae. CRISPR/Cas9-assisted disruption of one of them (OsMORE1a) enhanced resistance against hemibiotrophic pathogens M. oryzae and Xanthomonas oryzae pv. oryzae but increased susceptibility to Cochliobolus miyabeanus, a necrotrophic fungus, suggesting that OsMORE1a acts as a double-edged sword depending on the mode of infection (hemibiotrophic vs. necrotrophic). We characterized molecular and cellular changes caused by the loss of MORE1 and OsMORE1a to understand how these genes participate in modulating defence responses. Although the underlying mechanism of action remains unknown, both genes appear to affect the expression of many defence-related genes. Expression patterns of the GH10 family genes in A. thaliana and rice suggest that other members also participate in pathogen defence.     

Integrin Engagement by the Helical RGD Motif of the Helicobacter pylori CagL Protein Is Regulated by pH-induced Displacement of a Neighboring Helix

Arginine-aspartate-glycine (RGD) motifs are recognized by integrins to bridge cells to one another and the extracellular matrix. RGD motifs typically reside in exposed loop conformations. X-ray crystal structures of the Helicobacter pylori protein CagL revealed that RGD motifs can also exist in helical regions of proteins. Interactions between CagL and host gastric epithelial cell via integrins are required for the translocation of the bacterial oncoprotein CagA. Here, we have investigated the molecular basis of the CagL-host cell interactions using structural, biophysical, and functional analyses. We solved an x-ray crystal structure of CagL that revealed conformational changes induced by low pH not present in previous structures. Using analytical ultracentrifugation, we found that pH-induced conformational changes in CagL occur in solution and not just in the crystalline environment. By designing numerous CagL mutants based on all available crystal structures, we probed the functional roles of CagL conformational changes on cell surface integrin engagement. Together, our data indicate that the helical RGD motif in CagL is buried by a neighboring helix at low pH to inhibit CagL binding to integrin, whereas at neutral pH the neighboring helix is displaced to allow integrin access to the CagL RGD motif. This novel molecular mechanism of regulating integrin-RGD motif interactions by changes in the chemical environment provides new insight to H. pylori-mediated oncogenesis.