Chromium removal from solution by five photosynthetic bacteria isolates

Applied Microbiology and Biotechnology - Biological method has been recognized as a low-cost and ecofriendly approach for removing heavy metals from aqueous wastes. In this study, the ability of...     

Dephosphorylation of photosystem II proteins and phosphorylation of CP29 in barley photosynthetic membranes as a response to water stress

Kinetic studies of protein dephosphorylation in barley thylakoid membranes revealed accelerated dephosphorylation of photosystem II (PSII) proteins, and meanwhile rapidly induced phosphorylation of a light-harvesting complex (LHCII) b4, CP29 under water stress. Inhibition of dephosphorylation aggravates stress damages and hampers photosystem recovery after rewatering. This increased dephosphorylation is catalyzed by both intrinsic and extrinsic membrane protein phosphatase. Water stress did not cause any thylakoid destacking, and the lateral migration from granum membranes to stroma-exposed lamellae was only found to CP29, but not other PSII proteins. Activation of plastid proteases and release of TLP40, an inhibitor of the membrane phosphatases, were also enhanced during water stress. Phosphorylation of CP29 may facilitate disassociation of LHCII from PSII complex, disassembly of the LHCII trimer and its subsequent degradation, while general dephosphorylation of PSII proteins may be involved in repair cycle of PSII proteins and stress-response-signaling.     

Phenotyping of isogenic chlorophyll-less bread and durum wheat mutant lines in relation to photoprotection and photosynthetic capacity

Photosynthesis Research - In our experiments, we examined high light responses and photosynthetic capacity of chlorophyll-less isogenic mutant lines of hexaploid bread wheat (Triticum aestivum L.)...     

Red blood cell extrudes nucleus and mitochondria against oxidative stress

Mammal red blood cells (erythrocytes) contain neither nucleus nor mitochondria. Traditional theory suggests that the presence of a nucleus would prevent big nucleated erythrocytes to squeeze through these small capillaries. However, nucleus is too small to hinder erythrocyte deformation. And, there is no sound reason to abandon mitochondria for the living cells. Here, we found that mammal erythrocyte reactive oxygen species (ROS) levels kept stable under diabetes, ischemia reperfusion, and malaria conditions or in vitro sugar/heme treatments, whereas bird erythrocyte ROS levels increased dramatically in these circumstances. Nuclear and mitochondrial extrusion may help mammal erythrocytes to better adapt to high-sugar and high-heme conditions by limiting ROS generation.     

Assembly of NADPH:protochlorophyllide oxidoreductase complex is needed for effective greening of barley seedlings

NADPH:protochlorophyllide (Pchlide) oxidoreductase (POR) is the key enzyme in the light-induced greening of higher plants. A unique light-harvesting POR:Pchlide complexes (LHPP) has been found in barley etioplasts, but not in other plant species. Why PORs from barley, but not from other plants, can form LHPP? And its function is not well understood. We modeled the barley and Arabidopsis POR proteins and compared molecular surface. The results confirm the idea that barley PORA can form a five-unit oligomer that interacts with a single PORB. Chemical treatment experiments indicated that POR complex may be formed by dithiol oxidation of cysteines of two adjacent proteins. We further showed that LHPP assembly was needed for barley POR functions and seedling greening. On the contrary, Arabidopsis POR proteins only formed dimers, which were not related to the functions or the greening. Finally, POR complex assembly (including LHPP and POR dimers) did not affect the formation of prolamellar bodies (PLBs) that function for efficient capture of light energy for photo conversion in etioplasts.     

光下叶绿素缺乏的大麦突变体NYB中叶绿素合成再探

研究一种原叶绿素酯还原酶（POR）的大麦突变体Ⅳ阳光下合成叶绿素的结果表明,NYB中PORB的含量比野生型低。NYB前质体中原片层体的大小和数量与野生型差不多,但其结构比野生型的松散。暗中生长的突变体内POR蛋白复合物LHPP比野生型少。不同光照强度下叶绿素积累的结果显示,光照度越强,突变体与野生型的叶绿素差异越显著。由于porB是单拷贝的,所以推测突变体中部分porB mRNA可能产生错误的剪切拼接,以致光下突变体Ⅳ阳仍然能合成叶绿素。