Structure-physicochemical function relationships of soybean beta-conglycinin constituent subunits

Beta-conglycinin, one of the dominant storage proteins of soybean, has a trimeric structure, being composed of three subunits alpha, alpha', and beta. The alpha and alpha' subunits contain the extension regions in addition to the core regions common to all subunits, which are N-glycosylated. Physicochemical functions of recombinant nonglycosylated individual subunits and deletion mutants (alpha(c) and alpha'(c)) lacking the extension regions of the alpha and alpha' subunits were examined at pH 7.6 and 3.7 at low (mu = 0.08) and high (mu = 0.5) ionic strengths. Although individual recombinant subunits exhibited different properties at all conditions, there were some consistencies. Surface hydrophobicities and thermal stabilities of the individual subunits were likely to be conferred by their core regions, and the carbohydrate moieties did not contribute to these properties at any conditions examined here. Solubility at mu = 0.08, heat-induced association, and emulsifying ability remarkably depended on the extension regions and the carbohydrate moieties in addition to the structural features of the core regions. These findings indicate that various end products could be produced by the selection of soybean varieties containing beta-conglycinin with different subunit compositions and suggest a direction for a principle of soybean breeding.     

The effect of magmatic activity on hydrothermal venting along the superfast-spreading East pacific rise

A survey of hydrothermal activity along the superfast-spreading (approximately 150 millimeters per year) East Pacific Rise shows that hydrothermal plumes overlay approximately 60 percent of the ridge crest between 13 degrees 50' and 18 degrees 40'S, a plume abundance nearly twice that known from any other rige portion of comparable length. Plumes were most abundant where the axial cross section is inflated and an axial magma chamber is present. Plumes with high ratios of volatile ((3)He, CH(4), and H(2)S) to nonvolatile (Mn and Fe) species marked where hydrothermal circulation has been perturbed by recent magmatic activity. The high proportion of volatile-rich plumes observed implies that such episodes are more frequent here than on slower spreading ridges.     

Tradeoff between shade adaptation and mitigation of photoinhibition in leaves of Quercus mongolica and Acer mono acclimated to deep shade

We investigated susceptibility to photoinhibition in leaves acclimated to different light regimes in intermediately shade-tolerant Japanese oak (Quercus mongolica Fisch. ex Turcz. var. crispula (Blume) Ohashi) and shade-tolerant Japanese maple (Acer mono Maxim. var. glabrum (Lév. et Van't.) Hara), to elucidate adaptability to gap formation in leaves differing in shade acclimation. We hypothesized that there is a tradeoff between shade adaptation and capacity to mitigate photoinhibition associated with leaf morphology. We simultaneously measured chlorophyll fluorescence and gas exchange in seedlings that had been grown in full sunlight (open), 10% of full sun (moderate shade) and 5% of full sun (deep shade). Shade-tolerant A. mono adapted to deep shade through changes in leaf morphology, lowering its leaf mass per area (LMA), but Q. mongolica showed little change in LMA between moderate and deep shade. Photochemical quenching (qP) did not differ between species in full sunlight and moderate shade; however, in deep shade, qP of Q. mongolica was higher than that of A. mono, suggesting that Q. mongolica grown in deep shade is less susceptible to photoinhibition at gap formation. This is consistent with the finding that chronic photoinhibition 3 days after the transfer to full sunlight, indicated by the decrease in maximum photochemical efficiency, Fv/Fm, at predawn, was less in deep-shade-grown Q. mongolica than in deep shade-grown A. mono. In deep shade, the electron transport rate (ETR) of Q. mongolica was higher than that of A. mono, whereas thermal energy dissipation through photosystem II antennae, indicated by non-photochemical quenching, was lower in Q. mongolica than in A. mono. In deep shade, the greater ETR capacity in Q. mongolica in association with higher LMA and higher leaf N content could contribute to maintaining high qP and mitigating photoinhibition. These results indicate that, by maintaining a high electron transport capacity even in deep shade, the gap-dependent and intermediate-shade-tolerant Q. mongolica trades improved shade adaptation for higher growth potential when a gap event occurs.     

Arsenic immobilization in anaerobic soils by the application of by-product iron materials obtained from the casting industry

ABSTRACT

Reducing the arsenic (As) concentration in rice grains is of great interest from a human health perspective. Iron (Fe) materials immobilize As in soils, thereby effectively reducing the As concentration in rice grains. We investigated the effect of by-product Fe materials obtained from the casting industry on the As mobility in two soils (soil A and soil B) by a long-term (approximately 100 days) flooded soil incubation experiment. The examined Fe materials were spent steel shot (SSS), fine spent casting sand (SCS) containing steel shot, and two kinds of residual Fe materials (RIMs) from steel shot production. Commercial Fe materials used to immobilize As (zero-valent Fe and ferrihydrite) were tested for comparison. The dissolved As in soil solution of controls for soil A and soil B reached approximately 100 and 800 μg L^?1, respectively. The effect on As immobilization of all the by-product Fe materials increased with time and was comparable to or greater than that of commercial ferrihydrite, except for SCS. The additions of SSS and RIMs decreased by more than 90% of the dissolved As in soil A and decreased by more than 50% in soil B after 100 days incubation. Overall, the effect of the by-product Fe materials on the solubility of silicon and phosphorus was much less than that of the commercial Fe materials. Considering the cost advantage over commercial Fe materials, the Fe materials obtained from the casting industry as by-products are promising amendments for the immobilization of As in paddy soils.