Arsenic Accumulation in Rice: Sources,Human Health Impact and Probable Mitigation Approaches

The human body loading with arsenic (As) through rice consumption is a global health concern. There is a crucial need to limit As build-up in rice, either by remediating As accumulation in soils or reducing As levels in irrigation water. Several conventional approaches have been utilized to alleviate the As accumulation in rice. However, except for some irrigation practices, those approaches success and the adoption rate are not remarkable. This review presents human health risks posed due to consumption of As contaminated rice, evaluates different biomarkers for tracing As loading in the human body, and discusses the latest advancement in As reducing technologies emphasizing the application of seed priming, nanotechnology, and biochar application for limiting As loading in rice grains. We also evaluate different irrigation techniques to reduce As accumulation in rice. Altering water management regimes significantly reduces grain As accumulation. Bio- and nano-priming of rice seeds improve germination and minimize As translocation in rice tissues by protecting cell membrane, building pool around seed coat, methylation and volatilization, or quenching harmful effects of reactive oxygen species. Nanoparticle application in the form of nano-adsorbents or nano-fertilizers facilitates nano-remediation of As through the formation of Fe plaque or sorption or oxidation process. Incorporating biochar in the rice fields significantly reduces As through immobilization, physical adsorption, or surface complexation. In conclusion, As content in cooked rice depends on irrigation source and raw rice As level.     

Reduced fertility in triploids of <Emphasis Type="Italic">Acacia auriculiformis</Emphasis> and its hybrid with <Emphasis Type="Italic">A. mangium</Emphasis>

Polyploid breeding offers the possibility of increased variability in the search for improved growth, site adaptation and disease resistance in tropical acacias. A key focus of breeding in Vietnam has been the production and testing of vigorous triploid clones which are expected to have the added advantage of being sterile. Triploids obtained by manual crosses between diploid and tetraploid trees or by bulk screening of seedlings derived from open-pollinated seedlots were verified using flow cytometry. Thirteen clones are under field testing for growth rate, tree form and fertility. Six of these are now reproductively mature and flowered as prolifically as diploids. However no pollen germinated, either on agar or on their own stigmas under controlled pollination. Only one clone (X01—F₁ hybrid of tetraploid A. mangium and diploid A. auriculiformis) produced open pollinated pods on 0.05% of hermaphrodite flowers and these contained an average of 1.3 filled seeds per pod, about one-fifth the number observed in diploids. Less than 25% of germinated progeny from this triploid clone survived at 3 months after sowing and survivors were severely stunted with arrested growth. Ploidy and genotype analysis revealed them to be predominantly aneuploids, ranging from hyperdiploid to hypotetraploid with 95% being selfs. We are confident that we can select triploid clones which will be effectively infertile if deployed in plantations and may be of particular value in situations where the normal prolific natural regeneration of tropical acacias is highly undesirable.     

The prospects of silver fir (Abies alba Mill.) and Norway spruce (Picea abies (L.) Karst) in mixed mountain forests under various management strategies,climate change and high browsing pressure

European Journal of Forest Research - In the Dinaric Mountains, the future of silver fir and Norway spruce appears to be uncertain, especially given the threat of climate change to both species and...     

Novel α-Amylase Inhibitor Hemi-Pyocyanin Produced by Microbial Conversion of Chitinous Discards

α-Amylase inhibitors (aAIs) have been applied for the efficient management of type 2 diabetes. The aim of this study was to search for potential aAIs produced by microbial fermentation. Among various bacterial strains, Pseudomonas aeruginosa TUN03 was found to be a potential aAI-producing strain, and shrimp heads powder (SHP) was screened as the most suitable C/N source for fermentation. P. aeruginosa TUN03 exhibited the highest aAIs productivity (3100 U/mL) in the medium containing 1.5% SHP with an initial pH of 7–7.5, and fermentation was performed at 27.5 °C for two days. Further, aAI compounds were investigated for scaled-up production in a 14 L-bioreactor system. The results revealed a high yield (4200 U/mL) in a much shorter fermentation time (12 h) compared to fermentation in flasks. Bioactivity-guided purification resulted in the isolation of one major target compound, identified as hemi-pyocyanin (HPC) via gas chromatography-mass spectrometry and nuclear magnetic resonance. Its purity was analyzed by high-performance liquid chromatography. HPC demonstrated potent α-amylase inhibitory activity comparable to that of acarbose, a commercial antidiabetic drug. Notably, HPC was determined as a new aAI. The docking study indicated that HPC inhibits α-amylase by binding to amino acid Arg421 at the biding site on enzyme α-amylase with good binding energy (−9.3 kcal/mol) and creating two linkages of H-acceptors.