羊草种群的热值及其能量贮藏特点

为了获得有关中国东北羊草草原生态系统能量学方面的基础数据,作者对该草原的建群植被——羊草种群进行了热值含量的测定,在此基础上,对单位面积上的羊草种群热值含量进行了计算,以便分析在自然条件下,羊草种群的能量贮藏特点。研究结果表明,羊草(Leymus Chinensis)种群的果穗与其各器官相比,具有最高的热值含量,为4898.28cal/gDW,其活枝条与羊草种群的各部分相比,具有最高的热值含量,为4711.86cal/gDW。羊草种群将其截获的绝大部分太阳辐射能贮藏在地下部分以便为种群的安全越冬和第二年生长季节开始对其地上部分的萌发提供充足的能量。     

高山红景天（Rhodiola sachalinensis）遗传变异及其濒危机制的探讨

采用淀粉凝胶电泳手段,等位酶分析技术对分布于黑龙江大海林林业局高山红景天天然分布区内３个亚种群及吉林长白山１个亚种群的９种酶系统１８个位点进行了遗传分析,结果表明种群内存在一定的遗传变异（从态位点百分比为３０．５５％,等位基因平均数为１．３３３）但不是很丰富,主要是该种类狭窄的分布区致使生境单一及人为破坏其本身的生物学特性长期的进化过程中相互适应相互选择的结果。在黑龙江的分布区内各亚种群之间一致度     

MOLECULAR CHARACTERIZATION OF AUTOPHAGY‐RELATED GENE 5 FROM Spodoptera exigua AND EXPRESSION ANALYSIS UNDER VARIOUS STRESS CONDITIONS

Autophagy is not only involved in development, but also has been proved to attend immune response against invading pathogens. Autophagy protein 5 (ATG5) is an important autophagic protein, which plays a crucial role in autophagosome elongation. Although ATG5 has been well studied in mammal, yeast, and Drosophila, little is known about ATG5 in lepidopteran insects. We cloned putative SeAtg5 gene from Spodoptera exigua larvae by the rapid amplification of cDNA ends method, and its characteristics and the influences of multiple exogenous factors on its expression levels were then investigated. The results showed that the putative S. exigua SeATG5 protein is highly homologous to other insect ATG5 proteins, which has a conserved Pfm domain and multiple phosphorylation sites. Next, fluorescence microscope observation showed that mCherry‐SeATG5 was distributed in both nucleus and cytoplasm of Spodoptera litura Sl‐HP cells and partially co‐localized with BmATG6‐GFP, but it almost has no significant co‐localization with GFP‐HaATG8. Then, the Western blot analysis demonstrated that GFP‐SeATG5 conjugated with ATG12. Moreover, real‐time PCR revealed that its expression levels significantly increased at the initiation of pupation and the stage of adult. In addition, the expression levels of SeAtg5 can be enhanced by the starvation, UV radiation, and infection of baculovirus and bacterium. However, the expression levels of SeAtg5 decreased at 24 h post treatments in all these treatments except in starvation. These results suggested that SeATG5 might be involved in response of S. exigua under various stress conditions.     

Characterization of five fungal endophytes producing Cajaninstilbene acid isolated from pigeon pea [Cajanus cajan (L.) Millsp

Five fungal endophytes (K4, K5, K6, K9, K14) producing Cajaninstilbene acid (CSA, 3-hydroxy-4-prenyl-5-methoxystilbene-2-carboxylic acid) were isolated from the roots of pigeon pea [Cajanus cajan (L.) Millsp.]. CSA is responsible for the prominent pharmacological activities in pigeon pea. The amount of CSA in culture solution varied among the five fungal endophytes. K4 produced the highest levels of CSA (1037.13 μg/L) among the endophytes tested after incubation for five days. Both morphological characteristics and molecular methods were used for species identification of fungal endophytes. The five endophytic isolates were characterized by analyzing the internal transcribed spacer (ITS) rRNA and β-tubulin genes. The K4, K5, K9 and K14 strains isolated from pigeon pea roots were found to be closely related to the species Fusarium oxysporum. K6 was identified as Neonectria macrodidym. The present study is the first report on the isolation and identification of fungal endophytes producing CSA in pigeon pea. The study also provides a scientific base for large scale production of CSA.     

Overexpression of <Emphasis Type="Italic">Zm-HINT1</Emphasis> Confers Salt and Drought Tolerance in <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis>

Histidine triad nucleotide-binding protein 1 (HINT1) is highly conserved in many species and plays important roles in various biological processes. However, little is known about the responses of HINT1 to abiotic stress in plants. Salt and drought stress are major limiting factors for plant growth and development, and their negative effects on crop productivity may threaten the world’s food supply. Previously, we identified a maize gene, Zm-HINT1, which encodes a 138-amino-acid protein containing conserved domains including the HIT motif, helical regions, and β-strands. Here, we demonstrate that overexpression of Zm-HINT1 in Arabidopsis confers salt and drought tolerance to plants. Zm-HINT1 significantly regulated Na⁺ and K⁺ accumulation in plants under salt stress. The improve tolerance characteristics of Arabidopsis plants that were overexpressing Zm-HINT1 led to increased survival rates after salt and drought treatments. Compared with control plants, those plants that overexpressed Zm-HINT1 showed increased proline content and superoxide dismutase activity, as well as lower malondialdehyde and hydrogen peroxide accumulation under salt and drought treatments. The expression patterns of stress-responsive genes in Arabidopsis plants that overexpressed Zm-HINT1 significantly differed from those in control lines. Taken together, these results suggest that Zm-HINT1 has potential applications in breeding and genetic engineering strategies that are designed to produce new crop varieties with improved salt and drought tolerance.     

Characterization of activity and expression of isocitrate lyase in Mycobacterium avium and Mycobacterium tuberculosis

Analysis by two-dimensional gel electrophoresis revealed that Mycobacterium avium expresses several proteins unique to an intracellular infection. One abundant protein with an apparent molecular mass of 50 kDa was isolated, and the N-terminal sequence was determined. It matches a sequence in the M. tuberculosis database (Sanger) with similarity to the enzyme isocitrate lyase of both Corynebacterium glutamicum and Rhodococcus fascians. Only marginal similarity was observed between this open reading frame (ORF) (termed icl) and a second distinct ORF (named aceA) which exhibits a low similarity to other isocitrate lyases. Both ORFs can be found as distinct genes in the various mycobacterial databases recently published. Isocitrate lyase is a key enzyme in the glyoxylate cycle and is essential as an anapleurotic enzyme for growth on acetate and certain fatty acids as carbon source. In this study we express and purify Icl, as well as AceA proteins, and show that both exhibit isocitrate lyase activity. Various known inhibitors for isocitrate lyase were effective. Furthermore, we present evidence that in both M. avium and M. tuberculosis the production and activity of the isocitrate lyase is enhanced under minimal growth conditions when supplemented with acetate or palmitate.     

免疫毒素Luffin B-Ng76对人黑色素瘤细胞的体外抑制作用

用ＢｌｕｅＳｅｐｈａｒｏｓｅＣＬ－６Ｂ凝胶亲和层析法从丝瓜籽中分离纯化了单链致核糖体失活蛋白（ｒｉｂｏｓｏｍｅｉｎａｃ－ｔｉｖａｔｉｎｇｐｒｏｔｅｉｎ,ＲＩＰ）——ｌｕｆｉｎＢ。并将ｌｕｆｉｎＢ与抗人黑色素瘤细胞单抗Ｎｇ７６制成了免疫毒素,命名为ｌｕｆｉｎＢ－Ｎｇ７６,它对体外培养的黑色素瘤细胞Ｍ２１有很强的抑制作用,ＩＣ５０为２．５×１０－１１ｍｏｌ／Ｌ,毒性比游离的ｌｕｆｉｎＢ提高４０００倍,而它对非靶的ＨｅＬａ细胞的毒性较Ｍ２１细胞低１２００倍。结果提示ｌｕｆｉｎＢ用于制备免疫毒素具有良好的应用前景。     

不同杂种优势类群玉米幼胚愈伤组织的诱导及植株再生特性的评价

以Reid、唐四平头和其他种质等3个杂种优势类群共30份玉米自交系为实验材料,以玉米幼胚作为外植体,研究基因型、培养基、激素、继代培养次数对玉米幼胚愈伤组织诱导及植株再生的影响.研究结果表明供试材料均能进行愈伤组织诱导,但是只有部分自交系能再生植株.通过对不同杂种优势类群自交系玉米幼胚培养特性的分析,从Reid、唐四平头和其他种质类群的供试自交系中,筛选出了胚性愈伤组织诱导频率和绿苗分化率均较高、适合于遗传转化的受体材料,如黄野四/京24//C108/黄野四选系、黄早四/先早17//吉853选系、R43//黄野四/711选系、京7、京7黄、3189/4380选系、4380/陕综5选系、8103、先早17、18-599红、501、178和冀53.     

piRNA-Triggered MIWI Ubiquitination and Removal by APC/C in Late Spermatogenesis

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Highlights? MIWI is a substrate of APC/C, and piRNA loading is essential for MIWI ubiquitination ? piRNA loading promotes MIWI binding to the APC/C substrate-binding subunit ? MIWI and piRNAs are coordinately eliminated in late spermatids ? Inhibition of MIWI destruction in late spermatids prevents sperm maturation