鄱阳湖流域植被总初级生产力时空变化特征及其气候驱动因子分析

植被总初级生产力(GPP)在陆地生态系统和全球气候变化研究中占有重要地位。基于MODIS GPP遥感数据产品、土地覆盖数据和气象观测数据,对2000–2013年鄱阳湖流域GPP的时空变化及其与气候因素的关系进行了分析。结果表明,鄱阳湖流域GPP的年总量变化介于88–2 493 g C·m~(–2)·a~(–1)之间,平均值为1 361 g C·m~(–2)·a~(–1);GPP年总量最小值出现在2002年,最大值出现在2004年。GPP年际变化呈现明显的上下波动现象,并呈缓慢增长趋势。近14年植被GPP年均值在空间分布上表现出由湖区中心向四周散射递增的特点,GPP显著增加的区域占全区总面积的40%,主要分布在研究区东北部。相关性分析显示,气温对GPP年际变化的影响程度强于降水。此外,火灾对GPP的年际变化也具有一定的影响。该研究可为了解研究区的植被生长状况和生态环境质量提供参考。     

Maternal Antibody-Mediated Disease Enhancement in Type I Interferon-Deficient Mice Leads to Lethal Disease Associated with Liver Damage

Epidemiological studies have reported that most of the severe dengue cases occur upon a secondary heterologous infection. Furthermore, babies born to dengue immune mothers are at greater risk of developing severe disease upon primary infection with a heterologous or homologous dengue virus (DENV) serotype when maternal antibodies reach sub-neutralizing concentrations. These observations have been explained by the antibody mediated disease enhancement (ADE) phenomenon whereby heterologous antibodies or sub-neutralizing homologous antibodies bind to but fail to neutralize DENV particles, allowing Fc-receptor mediated entry of the virus-antibody complexes into host cells. This eventually results in enhanced viral replication and heightened inflammatory responses. In an attempt to replicate this ADE phenomenon in a mouse model, we previously reported that upon DENV2 infection 5-week old type I and II interferon (IFN) receptors-deficient mice (AG129) born to DENV1-immune mothers displayed enhancement of disease severity characterized by increased virus titers and extensive vascular leakage which eventually led to the animals’ death. However, as dengue occurs in immune competent individuals, we sought to reproduce this mouse model in a less immunocompromised background. Here, we report an ADE model that is mediated by maternal antibodies in type I IFN receptor-deficient A129 mice. We show that 5-week old A129 mice born to DENV1-immune mothers succumbed to a DENV2 infection within 4 days that was sub-lethal in mice born to naïve mothers. Clinical manifestations included extensive hepatocyte vacuolation, moderate vascular leakage, lymphopenia, and thrombocytopenia. Anti-TNFα therapy totally protected the mice and correlated with healthy hepatocytes. In contrast, blocking IL-6 did not impact the virus titers or disease outcome. This A129 mouse model of ADE may help dissecting the mechanisms involved in dengue pathogenesis and evaluate the efficacy of vaccine and therapeutic candidates.     

Genome mapping in halobacteria

The goal of our research is to produce an ordered set of cosmid clones for each of several species of halobacteria for use in physical and genetic mapping. These maps will answer questions about genome evolution and about gene organization and regulation in this archaebacterial lineage. Progress in cloning and mapping the genome of Halobacterium volcanii DS2 (synonym Haloferax volcanii DS2) is reported. Overlapping cosmids are recognized by a strategy which makes use of the distinctive restriction fragments around relatively rare restriction sites. Each site recognized by the infrequently cutting restriction enzymes is a landmark from which to identify different regions of the genome. The main advantage of this strategy is that only a small overlap (10-20%) between cosmid clones is required, resulting in a correspondingly small number of cosmid clones to be analyzed. The certainty of overlap is high, and computation is simple. The final 5-10% of each genome is cloned, linked, and identified by chromosome walking methods. Hybridization of cloned homologous or heterologous genes and of stable RNAs to the minimal cosmid set localizes these genes on the physical map. Additional genes have been and will be cloned by complementation of auxotrophic mutants, or as determinants of resistance to antibiotics.     

垄作稻田和垄作养鱼稻田土壤结构与肥力特征研究

水稻半旱式垄作栽培技术(又称水田自然免耕技术)的推广运用为稻田资源的综合开发利用,尤其是稻田高产养鱼奠定了物质和技术基础。它比较合理地解决了传统淹水平作水稻和传统稻田养鱼中存在的种稻与蓄水,种稻与养鱼,养鱼与晒田,养鱼与化肥、农药施用,水稻与杂草,水稻与病虫等方面的问题,水稻增产显著,成鱼产量大幅度提高,一般可达750—2250kg·ha~(-1),高者3750kg·ha~(-1)以上。物质循环和能量转化的成倍增加,势必对稻田生境和土壤肥力产生影响。因此,搞清楚传统淹水平作稻田起垄后的垄作稻田和垄作养鱼稻田的土壤结构和土壤肥力的变化规律,对指导开发稻田资源,实现稻鱼双丰收具有重要的意义。     

Kinetics and morphology of chemically induced popliteal lymph node reactions compared with antigen-, mitogen-, and graft-versus-host-reaction-induced responses

Changes in the popliteal lymph node (PLN) in mice evoked by a local graft-versus-host (GVH) reaction and by a single injection of various agents into the hind footpad were compared. The drug diphenylhydantoin induced similar weight changes in time as the GVH reaction. More vigorous and protracted reactions were induced by the drug nitrofurantoin and the contact sensitizer dinitrochlorobenzene, whereas the antigens lipopolysaccharide and sheep erythrocytes caused very moderate and short-lasting weight changes. Alterations of lymph node architecture upon injection of diphenylhydantoin resembled those observed during the GVH response. Some quantitative and qualitative differences were noted for nitrofurantoin, but clearly deviant morphological alterations were seen in response to lipopolysaccharide and sheep erythrocytes. The PLN reaction to dinitrochlorobenzene had features of both the GVH reaction and the antigen-induced responses. These findings support the concept that some drugs and chemicals may induce or exacerbate lymphoproliferative disorders by GVH-like mechanisms.     

Species specificities of l-glutamic acid decarboxylase: Immunochemical comparisons

The relationship of catfish brain l-glutamic acid decarboxylase (GAD) with those from other species were examined by comparing the extent of their interactions with antibodies against catfish brain GAD. Several immunochemical methods, such as immunodiffusion, inhibition of enzyme activity and microcomplement fixation tests were employed for these studies. Antibodies against GAD from catfish brain were observed to cross-react with the enzymes from goldfish, frog, chick and turtle. Rabbit and bovine GAD did not cross-react with these antibodies. In the presence of the antibodies, enzymes from goldfish, frog. Drosophila, chick and crayfish were inhibited 27, 46, 32, 38 and 57% respectively. Enzymes from all the other species examined were not affected at all. Microcomplement fixation tests showed that goldfish, frog and chick GAD were quite similar in immunoreactivities. These immunochemical studies demonstrated that GAD from lower vertebrates such as chick, goldfish and frog and some invertebrates such as Drosophila and crayfish are closely related to catfish GAD. In contrast, mammalian GAD shows little or no cross-reactivity with antibodies against catfish GAD.