Ephrin‐A5 regulates the formation of the ascending midbrain dopaminergic pathways

Dopaminergic neurons from the substantia nigra and the ventral tegmental area of the midbrain project to the caudate/putamen and nucleus accumbens, respectively, establishing the mesostriatal and the mesolimbic pathways. However, the mechanisms underlying the development of these pathways are not well understood. In the current study, the EphA5 receptor and its corresponding ligand, ephrin‐A5, were shown to regulate dopaminergic axon outgrowth and influence the formation of the midbrain dopaminergic pathways. Using a strain of mutant mice in which the EphA5 cytoplasmic domain was replaced with β‐galactosidase, EphA5 protein expression was detected in both the ventral tegmental area and the substantia nigra of the midbrain. Ephrin‐A5 was found in both the dorsolateral and the ventromedial regions of the striatum, suggesting a role in mediating dopaminergic axon‐target interactions. In the presence of ephrin‐A5, dopaminergic neurons extended longer neurites in in vitro coculture assays. Furthermore, in mice lacking ephrin‐A5, retrograde tracing studies revealed that fewer neurons sent axons to the striatum. These observations indicate that the interactions between ephrin‐A ligands and EphA receptors promote growth and targeting of the midbrain dopaminergic axons to the striatum. © 2008 Wiley Periodicals, Inc. Develop Neurobiol, 2009     

Impacts of cascaded small hydropower plants on microzooplankton in Xiangxi River, China

The impacts of small hydropower plants (SHPs) on zooplankton assemblages were investigated in six cascaded SHPs along the Xiangxi River in October 2005. Five sites were sampled at each SHP. Fifty-six rotifer species which belong to 21 genera of 13 families and a nauplius species were identified in this study. Most rotifers were benthic species. The dominant rotifer species were Rotaria tardigrada, R. rotatoria, Philodina erythrophthalma, Colurella adriati, C. uncinata, Cephalodella catellina, Euchlanus dilatata, Lecane crenata and Keratella cochlearis. The Jaccard similarity index among these sections was very low, ranging from 24.33 to 58.54. The chlorophyll a (Chl a) of phytoplankton ranged from 0.37 to 1.22 ug/l, and the highest appeared in Xiaodangyang SHP. The richness, Simpson, Shannon–Wiener and Margalef diversity indices of zooplankton ranged in 4.8–21.4, 0.53–0.89, 1.12–2.58 and 0.42–1.64, respectively. In Xiangxi River, zooplankton density was low, no more than 9000 ind./m3, and the highest was observed at the down section of the river, while the lowest was at the up section of the river. Nevertheless, the richness and density in Xiaodangyang SHP were very high, only second to those in Zhaojun SHP. Apart from Xiaodangyang SHP, richness and diversity indices of zooplankton increased gradually from the upstream to the downstream. Xiangxi River was disturbed by human activities due to the cascaded development of SHPs. From Xiaodangyang SHP to Cangpinghe SHP, the richness and diversity indices of zooplankton were relatively higher at Site 3, whereas in Houzibao SHP and Zhaojun SHP, the lowest were at Site 3. The dam of SHP had significant effects on the zooplankton community. The outlet of SHP had no effect on the zooplankton community.     

Landscape pattern MACRS analysis and the optimal utilization of Shiyang River Basin based on RS and GIS approach

Chose the arid interior district Shiyang River basin four issues of Landsat/TM images from 1986 to 2006 to visually interpret, and analyze the natural succession of ecological environment and the landscape pattern characteristic under the human activity interference. The results showed that in past 20 years, the number of landscape patch has increased, but the average patch size was decreasing, which explained that the landscape fragmentation degree was increasing, the landscape integrity was declining. The edge density of landscape remained invariable basically, which explained its stability maintained good. The diversity and evenness index continually enhanced, the diversity increased from 0.73 in 1986 to 0.84 in 2006. The mean core patch area of study area reduced from134.47 hm² in 1994 to 127.67 hm² in 2006, which indicated that the landscape core area was decreasing. On the one hand, it accelerated circulatory speed of species and reduced resistance of the energy flux. On the other hand it destroyed the integrity of the original landscape, easily caused the core area reducing continually, and led to vicious circle of the landscape separation. Seen from the whole study area, The utilization of landscape developed to the heterogeneous direction, indicated the proportional difference between various landscapes types was increasing, this kind of change has reflected the human activity’s influence to the whole landscape to a certain extent. It is believed that there are a series of landscape ecological problems such as low landscape ecological connectivity, simplified landscape structure and the more oasis fragmentation. In order to solve these problems, according to the principle that the movements of flow, energy and material in a landscape are related to some factors such as distance, time, impedance, etc., this study adopts the minimum accumulative resistance surface (MARS), the minimum cost resistance (MCR) model, and uses the surface diffusion technology to analyze compactness of landscape structure and the spatial difference of ecological function in Shiyang River basin. Then constructs some landscape components such as source, corridor and ecological node to strengthen the spatial connection of ecological network, and further discusses the landscape pattern optimization proposal.     

Engineering tocopherol biosynthetic pathway in lettuce

In order to increase tocopherol content, genes encoding Arabidopsis homogentisate phytyltransferase (HPT) and γ-tocopherol methyltransferase (γ-TMT) were constitutively over-expressed in lettuce (Lactuca sativa L. var. logifolia), alone or in combination. Over-expression of hpt could increase total tocopherol content, while over-expression of γ-tmt could shift tocopherol composition in favor of α-tocopherol. Transgenic lettuce lines expressing both hpt and γ-tmt produced significantly higher amount of tocopherol and elevated α-/γ-tocopherol ratio compared with non-transgenic control and transgenic lines harboring a single gene (hpt or γ-tmt). The best line produced eight times more tocopherol than the non-transgenic control and more than twice than hpt single-gene transgenic line.     

Ultrastructure changes of seedlings of <Emphasis Type="Italic">Kosteletzkya virginica</Emphasis> under waterlogging conditions

The changes in ultrastructure of leaf cell in waterlogged Kosteletzkya virginica seedlings were observed by transmission electron microscope. During waterlogging, the chloroplasts turned into a round shape and their volume was gradually reduced. Furthermore, the lamellae of thylakoids swelled, and the inclusions in chloroplast decreased. The shape of starch grains slightly changed, but their number and volume decreased, and they even disappeared in the end. On the other hand, plastoglobules enlarged and their amount enhanced gradually. The membrane and inner cristea of mitochondria gradually became unclear, while the mitochondria firstly enlarged but disappeared at the end. Similar to chloroplast, cell nucleus dwindled gradually, concentrated and tended to a round shape. Additionally, the annulate lamellae and multivesicular body occurred on the 20th day of experiment, and the cell wall distorted and twisted at the late stage of waterlogging. Consequently, these changes of organelles are the typical characteristics of the complete cell disintegration or death for Kosteletzkya virginica under long-term waterlogging.     

脂多糖快速银染检测方法的改良

为了建立一种快速、高效的脂多糖(LPS)银染检测方法,利用大肠杆菌(Escherichia coli 0111:B4)制备的LPS为研究对象,在传统LPS银染检测方法的基础上,通过调整凝胶的固定氧化试剂和银染试剂等措施,对LPS经SDS-PAGE电泳后的结果进行银染检测.结果表明,改良的LPS快速银染检测方法在保持传统方法灵敏度的基础上,操作过程更为简单,安全性、经济性和染色效果等方面也比传统的方法均有明显提高,是一种快速高效的LPS银染检测方法.     

奶牛结核病诊断方法的比较研究

旨在比较目前实验室用于检测牛结核方法及PPD皮内变态反应检测牛结核的敏感性和特异性.对145头进行了PPD结核菌素实验的牛进行了IFN-γ体外释放试验,ELISA方法检测ESAT-6,CFP-10,MPB70,MPB83四个蛋白的抗体,胶体金检测两种相似蛋白MPB70和MPB83.结果表明,IFN-γ体外释放试验的敏感性和特异性最高,与PPD皮内变态反应有较高的符合性.在抗体检测方面,iELISA的敏感性高于胶体金方法.虽然抗体检测(iELISA和胶体金方法)比细胞介导的免疫方法(IFN-γ和PPD)敏感性要低,前者更适合于检测处于结核病程发展后期的样本,并且可以有效降低假阳性反应.     

口腔鳞癌中D2-40表达的特点及临床意义

目的探讨口腔鳞癌组织中淋巴管分布、密度及其与临床病理因素之间的关系。方法应用免疫组化SP法检测口腔癌D2-40的表达情况,计数淋巴管密度（lymphatic vessel density,LVD）,分析其与临床病理特征间的关系。结果口腔鳞癌中的淋巴管形态及分布在不同区域具有异质性。与肿瘤中心（肿瘤实质）及癌旁正常组织比较,肿瘤边缘区（肿瘤间质）的淋巴管LVD为（11.09±2.958）,显著高于肿瘤中心（5.81±1.334）及癌旁正常组织（4.96±1.716）,且形态多呈扩张状态。结论口腔鳞癌中的淋巴管主要位于肿瘤边缘区,肿瘤边缘区LVD与淋巴结转移状态相关,检测口腔癌边缘区的LVD对预测是否发生淋巴结转移可能具有重要意义。