The rice OsDIL gene plays a role in drought tolerance at vegetative and reproductive stages

Drought is one of the critical factors limiting reproductive yields of rice and other crops globally. However, little is known about the molecular mechanism underlying reproductive development under drought stress in rice. To explore the potential gene function for improving rice reproductive development under drought, a drought induced gene, Oryza sativa Drought-Induced LTP (OsDIL) encoding a lipid transfer protein, was identified from our microarray data and selected for further study. OsDIL was primarily expressed in the anther and mainly responsive to abiotic stresses, including drought, cold, NaCl, and stress-related plant hormone abscisic acid (ABA). Compared with wild type, the OsDIL-overexpressing transgenic rice plants were more tolerant to drought stress during vegetative development and showed less severe tapetal defects and fewer defective anther sacs when treated with drought at the reproductive stage. The expression levels of the drought-responsive genes RD22, SODA1, bZIP46 and POD, as well as the ABA synthetic gene ZEP1 were up-regulated in the OsDIL-overexpression lines but the ABA degradation gene ABAOX3 was down-regulated. Moreover, overexpression of OsDIL lessened the down-regulation by drought of anther developmental genes (OsC4, CYP704B2 and OsCP1), providing a mechanism supporting pollen fertility under drought. Overexpression of OsDIL significantly enhanced drought resistance in transgenic rice during reproductive development, while showing no phenotypic changes or yield penalty under normal conditions. Therefore, OsDIL is an excellent candidate gene for genetic improvement of crop yield in adaption to unfavorable environments.     

Development of a novel recombinant strain Zygosacharomyces rouxii JL2011 for 1,3-propanediol production from glucose

1,3-propanediol (1,3-PDO) is one of the most important industrial chemicals due to its highly desired properties and its wide applications as a key component of the emerging polymer industry. Biotechnology route has been one of the most interesting methods for 1,3-PDO production, whereas, the dha genes were essential to 1,3-PDO biosynthesis. In this study, we cloned and placed the dha cassettes under the control of a glyceraldehyde 3-phosphate dehydrogenase gene promoter pGAP and homologous ZrFPS1 gene promoter pZrfps1; these two promoters were further integrated into the chromosome of Z. rouxii JL2011 to generate recombinant strain JL2011-GZ and JL2011-ZZ, respectively. The results showed that the two strains could produce 1,3-PDO from glucose with a final yield of 6.9 and 10.3 g/l, respectively. The engineered strain JL2011-ZZ showed a 2.3- and 1.5-fold increase in the specific activities and final concentration of 1,3-PDO, respectively, with respect to JL2011-GZ. Batch fermentation with aerobic/micro-aerobic combined strategy of JL2011-ZZ resulted a titer of 17.1 g/l and a yield from glucose of 8.6 %. These results demonstrated that JL2011-ZZ would be a potential strain for 1,3-PDO production from glucose.     

Overexpression of acetyl-CoA synthetase increased the biomass and fatty acid proportion in microalga Schizochytrium

High acetate accumulation was produced during glucose fermentation in high cell density cultures, which is harmful to cell growth. In order to reduce the negative impact of acetate accumulation on the fermentation products, we introduced the Escherichia coli acetyl-CoA synthetase (ACS) gene into the marine microalga Schizochytrium sp. TIO1101, generating genetically modified ACS transformants. The results of PCR and blotting analyses showed that the exogenous ACS gene was incorporated into the genome and successfully expressed. The engineered Schizochytrium increased the pH value and reduced the acetate concentration in the final fermentation medium significantly. Furthermore, the ACS transformants exhibited faster growth and glucose consumption rates than the wild-type strain. The biomass and fatty acid proportion of ACS transformants increased by 29.9 and 11.3 %, respectively. Taken together, the data suggest that ACS overexpression in Schizochytrium might improve the utilization of carbon resource and decrease the production of acetate byproduct. These results demonstrate that application of ACS in metabolic genetic engineering could improve the properties of Schizochytrium significantly.     

Expression of integrins α3β1 and α5β1 and GlcNAc β1,6 glycan branching influences metastatic melanoma cell migration on fibronectin

Acquisition of metastatic potential is accompanied by changes in cell surface N-glycosylation. One of the best-studied changes is increased expression of N-acetylglucosaminyltransferase V enzyme (GnT-V) and its products, β1,6-branched N-linked oligosaccharides, observed in the tumorigenesis of many cancers. In this study we demonstrate that during the transition from the vertical growth phase (VGP) (WM793 cell line) to the metastatic stage (WM1205Lu line), β1,6 glycosylation of melanoma cell surface proteins increases as a consequence of elevated expression of the GnT-V-encoding Mgat-5 gene. Treatment with swainsonine led to reduced cell motility on fibronectin in both cell lines; the effect was stronger in metastatic cells, probably due to the higher content of GlcNAc β1,6-branched glycans on the main fibronectin receptors – integrins α5β1 and α3β1. Our results show that GlcNAc β1,6 N-glycosylation of cell surface receptors, which increases with the aggressiveness of melanoma cells, is an important factor influencing melanoma cell migration.     

Highly enantioselective oxidation of phenyl methyl sulfide and its derivatives into optically pure (S)-sulfoxides with Rhodococcus sp. CCZU10-1 in an n-octane–water biphasic system

Enantiopure sulfoxides can be prepared via the asymmetric oxidation of sulfides using sulfide monooxygenases. The n-octane–water biphasic system was chosen for the bio-oxidation of a water-insoluble phenyl methyl sulfide (PMS) by Rhodococcus sp. CCZU10-1. In this n-octane–water system, the optimum reaction conditions were obtained. (S)-phenyl methyl sulfoxide ((S)-PMSO) with >99.9 % enantiomeric excess formed at 55.3 mM in the n-octane–water biphasic system. Using fed-batch method, a total of 118 mM (S)-PMSO accumulated in 1-L reaction mixture after the 7th feed, and no (R)-PMSO and sulfone were detected. Moreover, Rhodococcus sp. CCZU10-1 displayed fairly good activity and enantioselectivity toward other sulfides. In conclusion, Rhodococcus sp. CCZU10-1 is a promising biocatalyst for synthesizing highly optically active sulfoxides.     

Sex steroid changes during temperature‐induced gonadal differentiation in Paralichthys olivaceus (Temminck & Schegel, 1846)

Sex steroid changes during temperature‐induced gonadal differentiation were evaluated in the olive flounder, Paralichthys olivaceus. Larvae were reared at 21 ± 0.5°C, 24 ± 0.5°C and 28 ± 0.5°C from day 40 post‐hatching (dph) to 90 dph. The proportion of males was 61.1, 76.7, 87.8 and 47.8% in 21°C, 24°C, 28°C and in control groups, respectively. Gonadal differentiation was circa 65 dph, when fishes were a mean 39 mm total length (TL). The gonads developed faster when fishes were reared in higher temperatures. Radioimmunoassay (RIA) analyses indicated that the level of estradiol‐17β (E2) changed during the period of gonadal differentiation and peaked at an onset of ovarian differentiation in all groups. Compared with fish in control groups, the levels of E2 were lower in thermal‐treated groups, especially in the highest temperature groups. The present results indicate that E2 plays a major role in the process of ovarian differentiation, and suggest that temperature‐induced masculinization in P. olivaceus is mainly due to a decrease in the E2 level during the period of ovarian differentiation.     

Length‐weight relationships of flatfish species caught by bottom trawl in the Yellow Sea and the Bohai Sea,China

This study determined the length–weight relationships of five flatfish species from the Yellow Sea and the Bohai Sea in China. Two of the species (Cynoglossus semilaevis and Verasper variegatus) had no previous length‐weight estimates.     

Protective effects of EphB2 on Aβ1–42 oligomer-induced neurotoxicity and synaptic NMDA receptor signaling in hippocampal neurons

Alzheimer’s disease (AD) is a neurodegenerative disorder characterized pathologically by the abnormal deposition of extracellular amyloid-β (Aβ) oligomers. However, the nature and precise mechanism of the toxicity of Aβ oligomers are not clearly understood. Aβ oligomers have been previously shown to cause a major loss of EphB2, a member of the EphB family of receptor tyrosine kinases. To determine the effect of EphB2 on Aβ oligomer-induced neurotoxicity and the underlying molecular mechanisms, we examined the EphB2 gene in cultured hippocampal neurons. Using a cellular model of AD, Aβ_1–42 oligomers were confirmed to induce neurotoxicity in a time-dependent manner and result in a major decrease of EphB2. EphB2 overexpression could prevent the neurotoxicity of hippocampal neurons from exposure to Aβ_1–42 oligomers for 1 h. Further analysis revealed that EphB2 overexpression increased synaptic NR1 and NR2B expression in Aβ_1–42 oligomer-treated neurons. Moreover, EphB2 overexpression prevented Aβ_1–42 oligomer-induced downregulation of dephosphorylated p38 MAPK and phosphorylated CREB. Together, these results suggest that EphB2 is a factor which protects hippocampal neurons against the toxicity of Aβ_1–42 oligomers, and we infer that the protection of EphB2 is achieved by increasing the synaptic NMDA receptor level and downstream p38 MAPK and CREB signaling in hippocampal neurons. This study provides new molecular insights into the neuroprotective effect of EphB2 and highlights its potential therapeutic role in the management of AD.