滩涂湿地中全程硝化菌随季节和深度变化的分布特性

采集不同季节和深度的崇明东滩沉积物土壤样品,结合部分巢式PCR扩增和高通量测序方法,分析全程硝化菌在滩涂湿地中的群落结构,并结合相关理化参数进行冗余（RDA）分析,研究全程硝化菌不同类型的生态分布特点。结果显示,在所有沉积物样品中,全程硝化菌clade A.1和clade A.2比例明显高于clade B。全程硝化菌clade A.1在夏季所有沉积物样品中,占比最高;在夏冬两季浅表层沉积物(1～5 cm)和春秋深层沉积物(5～10 cm)中,比例相对偏高;全程硝化菌clade A.2情况与其相反。全程硝化菌clade B在秋冬两季比例相对其它季节偏高。RDA分析证实,相对于clade A.2,clade A.1与铵浓度呈正相关,而clade B则与总碳（TC）更密切相关。结果表明,长江口崇明东滩滩涂沉积物中全程硝化菌分布广泛,其分布特点和群落结构随季节和深度的变化而变化。滩涂环境因子与全程硝化菌群落结构的相关性研究有助于了解全程硝化菌对滩涂生态系统的贡献。     

Isolation and characterization of microsatellite markers from Pacific white shrimp (Litopenaeus vannamei)

We report the development of 11 polymorphic microsatellite loci in pacific white shrimp (Litopenaeus vannamei) using an unenriched genomic library. The number of the alleles ranged from two to 18 and observed hererozygosity ranged from 0.0286 to 0.9429, indicating that these markers will be useful for population studies and mapping in pacific white shrimp. Seven loci were detected deviated from Hardy–Weinberg, caused by deficiency of heterozygote, suggesting population genetic structure across the sampled population. No evidence for linkage disequilibrium was found.     

应用SSR标记分析大豆种质资源的遗传多样性

利用SSR分子标记分析了119个大豆品种的遗传多样性,结果表明：30对SSR引物在119份材料中共检测出159个等位变异,平均每对引物检测到5．30个等位变异;河北省农家品种中平均每对引物检测到5．17个等住变异,育成品种4．87个,省外品种4．93个,表明地方品种的遗传多样性高于育成品种。河北省农家品种、育成品种和省外育成品种依据SSR数据获得的品种间相似系数总体平均值相近,分别为0．698、0．698、0．672,但河北省农家品种较育成品种具有较大的变化幅度。119个品种可被划分为3个类群,在一定程度上能把育成品种和农家品种分开,并反映了一定的品种地域来源。     

南方沿海地区城市水土流失类型及特征—以珠海市三灶区为例

通过野外实地考察结合遥感技术手段开展珠海市三灶区城市水土流失重点调查。三灶区水土流失类型以人为侵蚀为主,主要是由开发平台建设、取土采石和修筑公路造成,侵蚀类型复杂多样,多沿交通道路两侧以及城市建成区周遍地带分布,侵蚀模数相差很大,最大侵蚀模数和最小侵蚀模数之间相差3个数量级,充分反映了城市水土流失的特点。     

南方沿海地区城市水土流失类型及特征——以珠海市三灶区为例

通过野外实地考察结合遥感技术手段开展珠海市三灶区城市水土流失重点调查。三灶区水土流失类型以人为侵蚀为主 ,主要是由于开发平台建设、取土采石和修筑公路造成 ,侵蚀类型复杂多样 ,多沿交通道路两侧以及城市建成区周遍地带分布 ,侵蚀模数相差很大 ,最大侵蚀模数和最小侵蚀模数之间相差 3个数量级 ,充分反映了城市水土流失的特点。     

植物光合CO2响应模型对光下(暗)呼吸速率拟合的探讨

运用LI-6400便携式光合作用系统测定了不同光强(2000、1500、1000和500 μmol·m^-2·s^-1)和两种O₂浓度(21%和2%的O₂)下冬小麦(Triticum aestivum)灌浆期旗叶的CO₂响应曲线, 比较了现有CO₂响应模型(生化模型、直角双曲线模型和直角双曲线修正模型)拟合给出光下(暗)呼吸与测量值之间的差异。结果显示, 直角双曲线修正模型所给出的光下呼吸速率拟合值与测量值最为接近。植物光合作用对大气CO₂响应(A/C_a)的拟合结果优于光合作用对胞间CO₂浓度(A/C_i)的拟合。然而, 所有模型基于A/C_a拟合的光下(暗)呼吸在整体上与测量值存在显著差异(p < 0.05), 推测与现有模型没有考虑CO₂浓度对光呼吸和光下暗呼吸速率的影响有关。对小麦的试验结果表明, CO₂浓度对光呼吸和光下暗呼吸均有显著影响: 随着CO₂浓度的增加(0-1400 μmol·mol^-1), 不同光强下的表观光呼吸变化范围分别为5.035-11.670、4.222-11.650、4.330-10.999和3.263-9.094 μmol CO_2·m^-2·s^-1; 光下暗呼吸的变化范围分别为0.491-2.987、0.457-2.955、0.545-3.139和0.448-3.139 μmol CO₂·m^-2·s^-1。回归分析发现, 表观光呼吸和光下暗呼吸与CO₂浓度之间均存在较好的相关性。然而, 将该回归关系整合到现有模型中, 是否会优化模型, 从而提高模型对相关光合参数估算的准确性尚有待于进一步研究。     

The youngest split in sympatric schizothoracine fish (Cyprinidae) is shaped by ecological adaptations in a Tibetan Plateau glacier lake

Although new empirical evidence shows that sympatric speciation has occurred in some species, there are few indisputable model organisms for this process of speciation. The two subspecies ( Gymnocypris eckloni eckloni and G . e . scoliostomus ) of the schizothoracine Gymnocypris fish species complex from a small glacier lake in the Tibetan Plateau, Lake Sunmcuo, fit several of the key characteristics of the sympatric speciation model. We used combined mitochondrial control region sequences and the cytochrome b gene (1894 bp) to address the phylogenetics and population genetics of 232 specimens of G . e . eckloni and G . e . scoliostomus , as well as all of its closely related sister species. We found that: (i) a total of four old lineages were uncovered in the widespread G . e . eckloni , of which only one was shown to be shared with all G . e . scoliostomus individuals and (ii) the new subspecies ( G . e . scoliostomus ) evolved in Lake Sunmcuo from the ancestral G . e . eckloni population within approximately 0.057 Ma. These two taxa of the species complex are morphologically distinct, and reproductive isolation is further suggested. Ecological disruptive selection based on morphological traits (e.g. mouth cleft characters) and food utilization may be a mechanism of incipient speciation of two sympatric populations within Lake Sunmcuo. This study provides the first genetic evidence for sympatric speciation in the schizothoracine fish.