Transforming growth factor-beta1 enhanced vascular endothelial growth factor synthesis in mesenchymal stem cells

Angiogenesis is essential for transplantation of mesenchymal stem cells (MSCs). Vascular endothelial growth factor (VEGF) is one of the most potent angiogenic factors identified to date. Elevated VEGF levels in MSCs correlate with the potential of MSCs transplantation. As an indirect angiogenic agent, transforming growth factor-β1 (TGF-β1) plays a pivotal role in the regulation of vasculogenesis and angiogenesis. However, the effect of TGF-β1 on VEGF synthesis in MSCs is still unknown. Besides, the intracellular signaling mechanism by which TGF-β1 stimulates this process remains poorly understood. In this article, we demonstrated that exposure of MSCs to TGF-β1 stimulated the synthesis of VEGF. Meanwhile, TGF-β1 stimulated the phosphorylation of Akt and extracellular signal-regulated kinase 1/2 (ERK1/2). Moreover, Ly 294002, a specific inhibitor of phosphatidylinositol-3-kinase (PI3K)/Akt significantly attenuated the VEGF synthesis stimulated by TGF-β1. Additionally, U0126, a specific inhibitor of ERK1/2, also significantly attenuated the TGF-β1-stimulated VEGF synthesis. These results indicated that TGF-β1 enhanced VEGF synthesis in MSCs, and the Akt and ERK1/2 activation were involved in this process.     

Hedgehog-mediated paracrine interaction between hepatic stellate cells and marrow-derived mesenchymal stem cells

During liver injury, bone marrow-derived mesenchymal stem cells (MSCs) can migrate and differentiate into hepatocytes. Hepatic stellate cell (SC) activation is a pivotal event in the development of liver fibrosis. Therefore, we hypothesized that SCs may play an important role in regulating MSC proliferation and differentiation through the paracrine signaling pathway. We demonstrate that MSCs and SCs both express hedgehog (Hh) pathway components, including its ligands, receptors, and target genes. Transwell co-cultures of SCs and MSCs showed that the SCs produced sonic hedgehog (Shh), which enhanced the proliferation and differentiation of MSCs. These findings demonstrate that SCs indirectly modulate the activity of MSCs in vitro via the Hh pathway, and provide a plausible explanation for the mechanisms of transplanted MSCs in the treatment of liver fibrosis.     

Purification and characterization of a type III photolyase from Caulobacter crescentus

The photolyase/cryptochrome family is a large family of flavoproteins that encompasses DNA repair proteins, photolyases, and cryptochromes that regulate blue-light-dependent growth and development in plants, and light-dependent and light-independent circadian clock setting in animals. Phylogenetic analysis has revealed a new class of the family, named type III photolyase, which cosegregates with plant cryptochromes. Here we describe the isolation and characterization of a type III photolyase from Caulobacter crescentus. Spectroscopic analysis shows that the enzyme contains both the methenyl tetrahydrofolate photoantenna and the FAD catalytic cofactor. Biochemical analysis shows that it is a bona fide photolyase that repairs cyclobutane pyrimidine dimers. Mutation of an active site Trp to Arg disrupts FAD binding with no measurable effect on MTHF binding. Using enzyme preparations that contain either both chromophores or only folate, we were able to determine the efficiency and rate of transfer of energy from MTHF to FAD.     

罗氏沼虾肌肉白浊病病原研究

从患白浊病的罗氏沼虾虾苗病灶分离到10多株菌株,其中一株经人工感染证实为病原菌,经ATB Expression自动细菌鉴定仪测试,为木糖葡萄球菌,其主要特性为拟球状（直径0.8-1.1μm）,革兰氏阳性,无鞭毛,无荚膜,不产生芽孢,发酵葡萄糖、果糖、麦芽糖、乳糖、海藻糖、阿拉伯糖、蔗糖及甘露醇产酸,β-半乳糖甘酶、过氧化氢酶及脲酶阳性,氧化酶,血浆凝固醇、V-P反应,精氨酸双水解酶、鸟氨酸脱羧酶均为阴性。最适生长温度、盐度和pH值范围分别为28-37℃、0%-2%、6-9,对红霉素、卡那毒素、头孢氨苄及庆大霉素等药物敏感。     

UV—B辐射增强对植物光合作用的影响及植物的相关适应性研究

综述了UV－B辐射增强对植物光合作用的影响,植物对光破坏的响应与适应性方面的国内外研究进展,许多研究表明UV－B辐射增强对植物具有破坏作用能引起植物光抑制,光氧化和光损伤,植物依靠自身修复系统而对其破坏又具有一定的适应性。     

布氏田鼠摄食量、累积摄食量与日龄的关系

布氏田鼠 (Ｍｉｃｒｏｔｕｓｂｒａｎｄｔｉ)是内蒙古典型草原区的主要害鼠 ,其危害方式主要表现之一为与牲畜争夺牧草资源[1,4 ,11,12 ] 。准确地测定其日食量(ＤＦＣ)与累积摄食量 (ＣＦＣ) ,对于定量地衡量该鼠的危害程度 ,进一步推算鼠害防治的经济阈值有着重要的意义。一些学者着手有关该鼠食性与食量 ,以及非取食性牧草消耗量的研究工作[3 ,7～ 9] 。但由于受实验手段的限制 ,一直未能解决布氏田鼠日食量、累积摄食量与田鼠年龄的关系等难题。本文以测定典型草原区布氏田鼠日食量与体重的关系 ,结合布氏田鼠体重与年龄的数学关系方程 …     

布氏田鼠对主要贮草种类的选储嗜好

布氏田鼠 (Ｍｉｃｒｏｔｕｓｂｒａｎｄｔｉ)为内蒙古典型草原区的主要害鼠 ,其危害主要表现在与牲畜争夺牧草资源[1,3 ,5,6,9] 。该鼠属不冬眠种类 ,冬季主要以洞群贮草仓库中的贮草为食 ,因此 ,研究其秋季集群的贮草习性 ,对于分析和了解该鼠的越冬生态特征具有一定的意义。有关布氏田鼠的贮草习性 ,已有一些报道[4 ,7] 。研究表明 ,在羊草 冷蒿 隐子草草场 ,布氏田鼠的越冬贮草以蒿属 (Ａｒｔｅｍｉｓｉａ)植物为主 ,其中冷蒿 (Ａ .ｆｒｉｇｉｄａ)与黄蒿 (Ａ .ｓｃｏｐａｒｉａ)占贮草比例超过 90 % [2 ] ,但上述研究均未涉及布氏田鼠…     

Organic carbon content and distribution in soils under different land uses in tropical and subtropical China

Tropical and subtropical China comprises a land area of about 215 Mha, but reports on its soil C storage and contents are limited. The objective of this study was to investigate the C density, stocks and distribution in soils of this region under different land uses by using soil species data from the Second National Soil Survey and the Vegetation Map of the People's Republic of China (1:4 M). It was estimated that there is a total of about 28.7±8.2 Pg organic C stored in the upper 1 m of soils of the entire region. Changes of C content (C) with depth (D) were observed following a relationship of C = (c + D)/ (a + bD), or C = 1/(a + bD). Of the various patterns of land uses in the region, soil C density was generally higher in the west than in the east, and while small differences were found in croplands, there were large variations in natural soils. In the west, the C density of meadow and herbaceous swamp soil was the highest (about 40 kg C/m²), followed by coniferous and broad-leaf forest soils (19.6 and 19.2 kg C/m², respectively). The C density of paddy, bush and coppice forest soils showed a density of 12.6 and 14.6 kg C/m², respectively. Upland and grass-savanah soils ranked the lowest (9.4 and 10.5 kg C/m², respectively). In the east, meadow and herbaceous swamp soil had the highest C density (25.2 kg C/m²), but differences in C density among soils under coniferous forest, broad-leaf forest, bush and coppice forest, and rice were small, varying from 10.2 to 11.4 kg C/m². The C density of upland soil (7.2 kg C/m²), appeared a little higher than that of grass-savanah soil (6.3 kg C/m²). For the various land uses in the region, the C density estimation is accompanied by relatively large variations.