The supramolecular architecture, function, and regulation of thylakoid membranes in red algae: an overview

Red algae are a group of eukaryotic photosynthetic organisms. Phycobilisomes (PBSs), which are composed of various types of phycobiliproteins and linker polypeptides, are the main light-harvesting antennae in red algae, as in cyanobacteria. Two morphological types of PBSs, hemispherical- and hemidiscoidal-shaped, are found in different red algae species. PBSs harvest solar energy and efficiently transfer it to photosystem II (PS II) and finally to photosystem I (PS I). The PS I of red algae uses light-harvesting complex of PS I (LHC I) as a light-harvesting antennae, which is phylogenetically related to the LHC I found in higher plants. PBSs, PS II, and PS I are all distributed throughout the entire thylakoid membrane, a pattern that is different from the one found in higher plants. Photosynthesis processes, especially those of the light reactions, are carried out by the supramolecular complexes located in/on the thylakoid membranes. Here, the supramolecular architecture, function and regulation of thylakoid membranes in red algal are reviewed.     

Stable isotope probing identifies anthracene degraders under methanogenic conditions

Polycyclic aromatic hydrocarbons (PAHs) are common contaminants in groundwater. The remediation of PAH-contaminated groundwater often involves anaerobic biodegradation. The knowledge about the microorganisms responsible for PAH degradation in anaerobic subsurface environment is still lacking. DNA-based stable isotope probing (SIP) was applied to discover the microorganisms responsible for anaerobic anthracene degradation within microcosms inoculated with aquifer sediment from landfill leachate-contaminated site. Three phylotypes were identified as the degraders, all falling within the phylum Proteobacteria. Two anthracene degraders were classified within the genera Methylibium and Legionella, while another one was an unclassified Rhizobiales species. They all were first linked to PAH degradation. These findings also provide an illustration of the utility of SIP to discover the roles of uncultured microorganisms in PAH-degrading processes.     

全球中华鲎资源保护现状及对策建议

鲎是古老的海洋节肢动物。中华鲎(Tachypleus tridentatus)是世界现存4种鲎中体型最大的一种, 是河口生态系统的标志物种, 同时其血液被用于生产医用检验试剂――鲎试剂。中华鲎的自然地理分布范围相当狭窄, 仅局限于日本濑户内海向南延伸至印度尼西亚爪哇岛北岸以北的太平洋西岸海域, 其中在中国东岸和日本南部海域的历史产量较高。自20世纪50年代以来中华鲎种群数量出现了显著减少, 2019年中华鲎在IUCN红色名录中的濒危等级正式更新为濒危(EN), 明确了中华鲎资源呈现全球性衰退的状态, 究其原因可归纳为鲎生境破坏和过度捕捞两个方面。在开展鲎资源保护的实践工作中, 作者深刻反思当前鲎资源保护在海洋保护区划定、增殖放流及科普和野生动物保护法宣传中存在的问题并提出相应建议, 包括加快完善种群基线数据, 制定标准化种群和生境基线监测指南, 构建科学放流体系等, 以期推进全球范围内的中华鲎资源保护与科学管理。     

Construction of two regulatory networks related to salt stress and lignocellulosic synthesis under salt stress based on a Populus davidiana × P. bolleana transcriptome analysis

Plant Molecular Biology - Construction of ML-hGRN for the salt pathway in Populus davidiana?×?P. bolleana. Construction of ML-hGRN for the lignocellulosic pathway in Populus...     

In vitro anti-influenza virus activities of sulfated polysaccharide fractions from <Emphasis Type=Italic>Gracilaria lemaneiformis</Emphasis>

In this paper, in vitro anti-influenza virus activities of sulfated polysaccharide fractions from Gracilaria lemaneiformis were investigated. Cytotoxicities and antiviral activities of Gracilaria lemaneiformis polysaccharides (PGL), Gracilaria lemaneiformis polysaccharide fraction-1 (GL-1), Gracilaria lemaneiformis polysaccharide fraction-2 (GL-2) and Gracilaria lemaneiformis polysaccharide fraction-3 (GL-3) were studied by the Methyl thiazolyl tetrazolium (MTT) method, and the inhibitory effect against Human influenza virus H1-364 induced cytopathic effect (CPE) on MDCK cells were observed by the CPE method. In addition, the antiviral mechanism of PGL was explored by Plaque forming unit (PFU), MTT and CPE methods. The results showed: i) Cytotoxicities were not significantly revealed, and H1-364 induced CPE was also reduced treated with sulfated polysaccharide fractions from Gracilaria lemaneiformis; ii) Antiviral activities were associated with the mass percentage content of sulfate groups in polysaccharide fractions, which was about 13%, in polysaccharides (PGL and GL-2) both of which exhibited higher antiviral activity; iii) A potential antiviral mechanism to explain these observations is that viral adsorption and replication on host cells were inhibited by sulfated polysaccharides from Gracilaria lemaneiformis. In conclusion, Anti-influenza virus activities of sulfated polysaccharide fractions from Gracilaria lemaneiformis were revealed, and the antiviral activities were associated with content of sulfate groups in polysaccharide fractions.     

Altering microtubule stability affects microtubule clearance and nuclear extrusion during erythropoiesis

Mammalian erythrocytes are highly specialized cells that have adapted to lose their nuclei and cellular components during maturation to ensure oxygen delivery. Nuclear extrusion, the most critical event during erythropoiesis, represents an extreme case of asymmetric partitioning that requires a dramatic reorganization of the cytoskeleton. However, the precise role of the microtubule cytoskeleton in the enucleation process remains controversial. In this study, we show that microtubule reorganization is critical for microtubule clearance and nuclear extrusion during erythropoiesis. Using a rodent anemia model, we found that microtubules were present in erythroblasts and reticulocytes but were undetectable in erythrocytes. Further analysis demonstrated that microtubules became disordered in reticulocytes and revealed that microtubule stabilization was critical for tubulin degradation. Disruption of microtubule dynamics using the microtubule-stabilizing agent paclitaxel or the microtubule-destabilizing agent nocodazole did not affect the efficiency of erythroblast enucleation. However, paclitaxel treatment resulted in the retention of tubulin in mature erythrocytes, and nocodazole treatment led to a defect in pyrenocyte morphology. Taken together, our data reveals a critical role for microtubules in erythrocyte development. Our findings also implicate the disruption of microtubule dynamics in the pathogenesis of anemia-associated diseases, providing new insight into the pathogenesis of the microtubule-targeted agent-associated anemia frequently observed during cancer chemotherapy.     

Expression of Retinoid X Receptors in Human Dermal Fibroblasts

Retinoic acid (RA) is known to exert profound effects on growth and differentiation in human dermal fibroblasts. In the observations presented here, we examined the regulation of expression of members of the RXR multigene family in human dermal fibroblasts. We showed that the messenger RNAs for both RXRα and RXRβ are expressed in human fibroblasts, but that the messenger RNA for RXRγ is not detectable in these cells. Electrophoretic mobility shift studies of binding to the β2RARE in human dermal fibroblasts demonstrated that a single complex binds to β2RARE in the absence of RA. Stimulating cells with all-transRA induced a second complex. An antibody to the RXRβ protein supershifted both complexes, while an antibody to the RXRα S/B protein had no effect on the binding. These data demonstrate that RXRβ plays an important role in retinoid-regulated signal transduction pathways in human dermal fibroblasts and the regulation of expression of the RXR gene family is different from that of the RAR gene family.     

Triphala and its active constituent chebulinic Acid are natural inhibitors of vascular endothelial growth factor-a mediated angiogenesis

Triphala churna (THL) is a combination of three fruits that has been used for many years in India for the treatment of various diseases. There are now reports which indicate that THL can inhibit growth of malignant tumors in animals. However, the mechanisms by which THL mediates its anti-tumor actions are still being explored. Because vascular endothelial growth factor-A (VEGF) induced angiogenesis plays a critical role in the pathogenesis of cancer, we therefore investigated whether tumor inhibitory effects of THL or its active constituents are through suppression of VEGF actions. We herein report that THL and chebulinic (CI) present in THL can significantly and specifically inhibit VEGF induced angiogenesis by suppressing VEGF receptor-2 (VEGFR-2) phosphorylation. These results are of clinical significance as these inexpensive and non-toxic natural products can be used for the prevention and treatment of diseases where VEGF induced angiogenesis has an important role.