基于C、N同位素技术的河流食物网基础碳源研究进展

基础碳源是河流生态系统最重要的特征之一,它通过生物间能量传递,影响着河流生态系统生物多样性、群落结构及其稳定性。本文基于稳定性同位素技术综述了河流基础碳源类型、食物网能量贡献率估算模型、食物网基础碳源理论模型(河流生产力模型RPM、河流连续模型RCC和河流脉冲模型FPC)及其交互作用以及它们在实际应用上的利弊,介绍了能较好平衡各种模型利弊、适应于多样化水文特征的河流生态系统综合体(RES)新假说,并展望了稳定性同位素技术与非致命取样方法相结合建立长期河流同位素数据库的重要意义,旨在推动对河流生态系统中不同生物之间营养关系的理解,为河流生态系统的修复与保护提供理论依据。     

基于演化博弈的农产品供应链信息共享行为研究

运用演化博弈理论,建立了一个农产品供应商和生产加工商的两级供应链的信息共享动态演化博弈模型,并对系统长期的动态演化过程进行分析。结果表明,农产品供应链上各企业进行信息共享的行为与博弈双方的支付矩阵及初始值有关。博弈双方的信息吸收能力、共享量和协同效应系数越大,信息共享概率越大;信息共享成本和风险越大,信息共享概率越小;初始值的增大有利于信息共享,但到一定程度后,各企业会逐渐趋于信息不共享。     

马铃薯块茎花色素苷合成相关R2R3 MYB蛋白基因的克隆和功能 分析

植物花色素苷的合成代谢受转录因子的调控, 其中R2R3 MYB为最主要的转录调控因子。本研究以彩色四倍体马铃薯为试材, 克隆了R2R3 MYB基因家族里调控马铃薯块茎花色素苷合成R2R3 MYB-StAN1的3个同源基因, 并利用生物信息学分析、稳定烟草遗传转化、qPCR等方法对这3个同源基因的结构和功能进行分析和鉴定, 结果表明, 这3个同源基因均含有R2和R3保守结构域, 其主要差别在于C端由10个氨基酸序列组成的重复结构(R)数目不同, 根据R数目将其分别命名为StAN1-R0、StAN1-R1和StAN1-R3, 其蛋白分子量分别为28 047.91、29 458.35和31 527.60 Da, 等电点(pI)分别为6.14、6.90和8.39, 均为亲水蛋白。通过转化烟草发现, 转入StAN1-R0、StAN1-R1和StAN1-R3后, 烟草叶片叶色变化明显, 其中转StAN1-R1烟草叶色呈深红色, 其叶片花色素苷含量最高。进一步利用qPCR分析表明, 外源StAN1使烟草叶片花色素苷合成代谢途径的关键基因(NtCHS、NtCHI、NtF3H、NtF3’H、NtDFR、NtANS、NtUFGT)上调表达, 同时烟草内源NtbHLH基因的表达显著上升; StAN1-R1可以高效地调控烟草内源NtbHLH基因和结构基因NtDFR和NtANS的表达。结果表明, StAN1的3个同源蛋白均可以调控花色素苷的合成, 而只含一个重复序列R的StAN1调控花色素苷合成的能力最强。     

凹凸棒土对土壤团粒结构及水力参数的影响

向粉砂质壤土中均匀添加不同含量(0、10、20、30、40 g·kg~(-1))凹凸棒土(简称ATP)进行土壤水分特征曲线试验、土壤颗分试验及土壤团聚体试验,研究不同ATP施加量对土壤团粒结构及土壤水力参数的影响。结果表明:土壤中的黏粒(0.002 mm)从9.28%减小至7.06%,粉粒(0.002~0.02 mm)从50.21%减小至26.8%,砂粒(0.02~2 mm)比例从40.52%增加至41.49%;随着ATP含量增大,土壤水分特征曲线分形维数从2.859增加至2.876,土壤粒径分形维数从2.645减小至2.628,在ATP含量为30 g·kg~(-1)时两者的分形维数均出现拐点;试验结束自然风干后的土壤大颗粒含量增加,0.25 mm的土壤团粒随着ATP含量的增加从0增加至2;利用土壤水分特征曲线分形模型对土壤含水率进行模拟后,其模拟计算值与实测值的均方根误差RMSE在10%以内;利用非饱和土壤水力传导度分形模型对不同含量ATP非饱和水力传导度进行预测,其预测值随着ATP含量的增加整体呈减小趋势。综合分析可知,加入ATP后的土壤持水能力增强,具有改良土壤的作用,且当ATP含量为30 g·kg~(-1)时的改良效果最佳。     

渔船用生物柴油减排的进化博弈分析

渔船污染排放是空气污染的一个重要来源,引起国际社会的广泛关注。生物柴油作为一种清洁的可再生能源,具有显著的减排效果。研究从进化博弈论的角度探讨了渔船应用生物柴油的减排策略,分析了有限理性的渔民之间、渔民和企业之间采取不同策略群体比例的动态变化,以及进行稳定策略的条件。研究认为,政府的补贴政策、渔业部门的监督检验和碳交易的有效实施,可以改变渔民的得益矩阵,引导渔民使用替代能源进行减排。对我国捕捞渔船进行了减排成本估算,结果表明,渔船发动机掺混5%的生物柴油将导致每船每年平均增加燃油成本近3 000元。如果政府能够制定生物柴油补贴政策,并建立有效的碳交易制度,在不增加成本的前提下,渔民会逐渐倾向采用生物柴油进行渔船减排。     

应用氮稳定同位素技术研究辽东湾海域主要渔业生物的营养级

应用氮稳定同位素技术分析了2010年6月和8月辽东湾海域主要渔业生物的氮稳定同位素比值,研究了28种鱼类和26种无脊椎动物的营养位置。结果表明,辽东湾海域主要渔业生物的营养级处于2.98～4.84,集中在3.70～4.56;相比6月δ15N值的分析结果,8月有50%的鱼类δ15N值增加,孔鳐(Raja porosa)增幅最大,增加了1.06‰;9种鱼类δ15N值减少,鯒(Platycephalus indicus)减幅最大,减少了1.84‰,可见鱼类样品的δ15N值随季节的变化因种类而各异;8月有87.5%的无脊椎动物δ15N值减少,其中,减少幅度大于1‰的有6种,占37.5%,可见无脊椎动物的δ15N值随季节的变化较明显。通过对不同采样点同种生物δ15N值的比较发现,辽东湾近岸海域的10种无脊椎动物的δ15N值均高于远岸海域,差值范围为0.05‰～1.49‰,差异极显著(P<0.01),说明人类活动引起的陆源污水排放使近岸海洋生物的δ15N值升高。     

Efficacy of a Fructus mume Extract Combination with Stable Chlorine in Preventing Bacterial Contamination in Frozen Mackerel (Scomber japonicus) Fillets

ABSTRACT

A combination composed of Fructus mume extract and stable chlorine dioxide was investigated for its antibacterial activity, mechanism of action, and its application against Escherichia coli and Staphylococcus aureus in mackerel (Scomber japonicus) fillets. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values against E. coli and S. aureus ranged from 0.9–1.2 and 1.3–1.6 mg/mL for F. mume extract and 0.004–0.006 and 0.007–0.010 mg/mL for stable chlorine dioxide, respectively. We observed a mechanism of action against E. coli that involved a pore-formation role that led to cell membrane damage. In the case of S. aureus, the mechanism of action is believed to be mediated by the combination’s activity as a metabolite disrupting agent. Here, the amount of bacteria was greatly reduced in mackerel fillets treated with the combination. Moreover, the flavor and texture properties of fillets were not significantly affected by this treatment (p < 0.05). These findings suggested that the combination has promise in being used as an additive to a broader class of foodstuffs.     

Stable resistance against the leaf miner <Emphasis Type="Italic">Leucoptera coffeella</Emphasis> expressed by genetically transformed <Emphasis Type="Italic">Coffea canephora</Emphasis> in a pluriannual field experiment in French Guiana

Summary A pluriannual field trial of transgenic clones of Coffea canephora (the Robusta coffee tree) transformed for resistance to the lepidopteran coffee leaf miner Leucoptera coffeella was installed in French Guiana. Fifty-eight transformed clones produced by transformation of the C. canephora clone 126 were planted. They were harbouring the pEF1α constitutive promoter of Arabidopsis thaliana controlling either the Bacillus thuringiensis native gene for the cry1Ac insecticidal protein (eight clones) or a synthetic cry1Ac gene (53 clones). The vectors for the transformation were a strain of the bacterium Agrobacterium tumefaciens and one of Agrobacterium rhizogenes. The transformed clones were generally independent, presenting different integration patterns of the genetic construct. Four randomly distributed groups of five plants per transformed clone were planted along with 60 untransformed control trees. Over a 4-year period after plantation six releases of L. coffeella were performed. Mines on the leaves are the marks of larvae development and were counted on plants. A majority of the independent transformed clones harbouring the synthetic gene and transformed by the strain of A. tumefaciens displayed constantly much less mines than the control, therefore expressing a stable resistance. The need for complementary research is presented.     

The dietary regime of detritivorous fish from the River Jacaré Pepira, Brazil

The diet of detritivorous fish was analysed at four distinct habitats in a tropical river during the wet and dry seasons. Two methodologies were used to determine the diet of the fish: (1) the direct analysis of the stomach contents; and (2) the use of stable carbon isotopes. Both methods indicated food partitioning among the fish. The stomach contents showed what the fish had ingested when captured and the ¹³C isotope indicated what it had assimilated over a long period of time. The ¹³C isotope suggested the existence of sectional differences in the feeding of the detritivorous fish along the river. Plants employing the C₄ photosynthesis pathways seem to have little influence on the diet of these fish. This method proved to be more appropriate for the detection of the main food sources of the captured fish.