Terrestrial carbon‐cycle feedback to climate warming: experimental evidence on plant regulation and impacts of biofuel feedstock harvest

Feedback between global carbon (C) cycles and climate change is one of the major uncertainties in projecting future global warming. Coupled carbon–climate models all demonstrated a positive feedback between terrestrial C cycle and climate warming. The positive feedback results from decreased net primary production (NPP) in most models and increased respiratory C release by all the models under climate warming. Those modeling results present interesting hypotheses of future states of ecosystems and climate, which are yet to be tested against experimental results. In this study, we examined ecosystem C balance and its major components in a warming and clipping experiment in a North America tallgrass prairie. Infrared heaters have been used to elevate soil temperature by approximately 2 °C continuously since November 1999. Clipping once a year was to mimic hay or biofuel feedstock harvest. On average of data over 6 years from 2000 to 2005, estimated NPP under warming increased by 14% without clipping (P<0.05) and 26% with clipping (P<0.05) in comparison with that under control. Warming did not result in instantaneous increases in soil respiration in 1999 and 2000 but significantly increased it by approximately 8% without clipping (P<0.05) from 2001 to 2005. Soil respiration under warming increased by 15% with clipping (P<0.05) from 2000 to 2005. Warming‐stimulated plant biomass production, due to enhanced C₄ dominance, extended growing seasons, and increased nitrogen uptake and use efficiency, offset increased soil respiration, leading to no change in soil C storage at our site. However, biofuel feedstock harvest by biomass removal resulted in significant soil C loss in the clipping and control plots but was carbon negative in the clipping and warming plots largely because of positive interactions of warming and clipping in stimulating root growth. Our results demonstrate that plant production processes play a critical role in regulation of ecosystem carbon‐cycle feedback to climate change in both the current ambient and future warmed world.     

EB病毒潜伏膜蛋白LMP1编码基因沉默对NF—kB表达的影响

目的：探讨EBV阳性胃上皮细胞中潜伏膜蛋白1（latentmembraneprotein-1,LMP1）基因沉默对NF-kB转录表达的影响。方法：以稳定表达LMP1的EBV阳性胃上皮细胞系作为靶细胞,采用化学合成的siRNA特异性沉默LMP1,用RT-PCR和Westem-blotting分别检测其在不同时间段mRNA和蛋白水平特异性沉默效果;Westernblotting及免疫酶染色法检测LMP1基因沉默对NF—kB转录表达及核转移的影响。结果：siRNA在mRNA和蛋白水平可特异性沉默LMP1的表达,且有时间效应关系;Westem blotting及免疫酶染色法检测结果显示LMP1沉默可干扰NF—KB表达,导致靶细胞核内NF-kB水平下降,细胞浆内水平升高,而NF—kB总蛋白有下降趋势。结论：LMP1基因特异性沉默能够影响NF-kB表达,抑制其核转移。     

诸葛菜花柄切段和花托离体培养中直接长出小花

在ＭＳ附加ＢＡ的几种培养基上首次从诸葛菜花柄切段和花托部位直接诱导出小花及花枝开花。花发育不正常,无花粉。该花花茎、叶柄、子房等的切段培养仍能再生出小枝,说明成花诱导态是稳定的,不可逆的．     

漆树胚,胚乳发育及花果生长的相关性研究

漆树为倒生胚珠,双珠被,厚珠心,具承珠盘及拟珠孔塞,胚囊发育为蓼型,核型胚乳,胚发育为柳叶菜型,后历经棒状形胚、心形胚、鱼雷形胚和成熟胚各期。花和果实生长与胚及胚乳发育有密切的相关性,胚内具原始的乳汁道系统为重要特征。一些胚珠内无胚或胚乳早期退化引起胚败育是造成种子空籽原因之一。     

大蒜愈伤组织诱导条件初报

以白皮大蒜和大头蒜为材料,报道了大蒜品系、外植体的低温前处理、外植体大小及取材种类不同对愈伤组织诱导的影响。结果表明：（１）无论是４℃低温保藏或室温保存前处理,大头蒜的消毒效果均优于白皮大蒜,４℃低温前处理可降低外植体出愈污染;（２）只有带表皮的外植体才可诱导愈伤组织,外植体较大（０．５ｃｍ×０．３ｃｍ×０．２ｃｍ）,继代期愈伤组织产生量较多;外植体偏小（０．２ｃｍ×０．１ｃｍ×０．１ｃｍ）,极少产生愈伤组织;（３）４℃冷藏１８ｄ对大头蒜愈伤组织诱导有一定影响,但对白皮大蒜影响不大。冷藏可推迟出愈１～２ｄ。     

苎麻疫霉激发蛋白基因断裂现象初探

苎麻疫霉（PhytophthoraboehmeriaeSaw．）可分泌具有诱抗作用的激发蛋白（α－elicihn）,根据α－elicitin第24～30和56～63位保守区氨基酸推导的寡核苷酸引物序列,对苎麻疫霉基因组DNA进行特异PCR扩增反应,发现其扩增的DNA片段大于预计的片段。回收纯化的特异扩增DNA,并进行克隆和测序分析,结果表明特异扩增的elicihn基因亚克隆DNA为570hp,大于预计的117bp。在特异片段中,存在3个内含子将基因断裂成4个阅读框架,即ORF1、ORF2、ORF3和ORF4,其中ORF1和ORF4含有与引物相同的序列,但与其它序列与已克隆的elicihn基因无同源性。因此,芒麻疫霉基因组中的elicitin基因可能存在断裂现象。     

甲羟戊酸通路对细胞生长调控作用的研究进展

甲羟戊酸(MVA)通路对细胞生长具有重要的调节作用,MVA及其衍生物通过对蛋白质异戊烯化和N糖基化修饰而影响Ras蛋白、生长因子及受体的功能、细胞内信号转导和细胞的生长。MVA通路参与血管活性物质生成的调节是其调节细胞生长的另一机制。MVA生成的限速酶羟甲基戊二酸单酰辅酶A(HMGCoA)则受MVA通路衍生物的反馈抑制。HMGCoA还原酶抑制剂通过抑制MVA及其衍生物的生成而抑制细胞的生长和增殖。     

湖南汉族人群IL-1O启动子和IL-1ra基因多态性与SLE相关性研究

目的:研究湖南汉族人群IL-10启动子和IL-1受体拮抗剂(IL-1ra)的基因多态性,探讨IL-10启动子和IL-1ra基因多态性与SLE疾病的关系。方法:PCR和限制性内切酶酶切分析SLE患者(n=83)和正常对照人群(n=125)IL-10启动子和IL-1ra基因多态性,对基因频率进行分析。结果:湖南汉族人群IL-1ra及IL-10启动子基因具有多态性;SLE患者IL-1RN*1等位基因的频率显著高于正常对照组(P<0.05,RR=5);SLE患者IL-10启动子区-597位*A、-824位*T和ACC亚型的基因频率高于正常对照组(P<0.001)。结论:SLE患者IL-1RN*1的基因频率、IL-10启动子区-597位和-824位的基因多态性与正常人比较有显著差异,提示以上基因可能与SLE的发病有一定相关性。     

A Primary Study of the Subgroups of T Lymphocytes in MHV-3 Induced Chronic Viral Hepatitis

To study the contribution of T cell subsets in the pathogenesis of Murine hepatitis virus Type 3(MHV-3) induced chronic viral hepatitis in C3H/Hej mice,ninety C3H/Hej mice were chosen to individually receive 10 plaque forming units(PFU)of MHV-3 intraperitoneally.The changes of virus titer and pathology in liver tissue were examined by standard plaque assay and by the hematoxylin/eosin(HE) staining method from 2 days post MHV-3 infection.The ratios of T cell subsets including CD3 CD4 CD8-,CD3 CD4-CD8 ,CD3 CD4-CD8-,CD3 CD4 CD25 ,CD3 CD4 CD25-and CD3 CD4-CD25 T lymphocyte of total T lymphocytes in blood,spleen and liver were examined at 0,2,4,6,8,10,12,15,20,25,30,40 days post MHV-3 infection by flow cytosorting.We observed that the virus titer raised and showed persistent virus duplications and inflammatory changes in the livers of C3H/Hej mice from 2 days post MHV-3 infection.The double negative T cell(DN Treg cell) and CD4 CD25 T cell ratios increased significantly from 2 days post MHV-3 infection in C3H/Hej mice,and CD3 CD4 CD8-,CD3 CD4-CD8 ,CD3 CD4 CD25-and CD3 CD4-CD25 T cell ratios decreased accordingly.In conclusion,the changes of virus titer and pathology in the livers of C3H/Hej mice post MHV-3 suggest their contribution to viral persistence.Further characterizations of DN Treg cells are that infection indicates that MHV-3 could induce the chronic inflammation in livers of C3H/Hej mice.The increase of the DN Treg cell and CD4 CD25 T cell ratios in C3H/Hej mice post MHV-3 infection suggests that DN Treg cells and CD4 CD25 T cells may both have important suppressive immunomodulation functions in the development of chronic viral hepatitis and have important roles in the virus persistent infection.Further characterizations of DNT cell and CD4 CD25 T cell are under investigation.     

拟目乌贼精子发生和精子的超微结构

应用扫描电镜和透射电镜观察了拟目乌贼(Sepia lycidas)精子的发生过程和超微结构。结果表明,精子发生经历了精原细胞、初级精母细胞、次级精母细胞、精细胞和成熟精子5个阶段,其中精细胞可以分为Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ5个时期,精细胞Ⅱ期又可分为前期和后期。细胞核经历了一个横向收缩、纵向拉长的过程,由圆形或椭圆形,变为不规则的纺锤形、稍弯曲的长柱形;核内染色质由絮状,变为絮块状、致密颗粒状、细纤维状、粗纤维状和片层状,直至高电子密度均质状;顶体由圆形,变为头盔形、圆锥形、倒"U"字形,直至子弹头形;线粒体由空泡状经过融合和迁移,变为内嵴丰富的椭球形,形成不完全包围鞭毛的线粒体距。成熟精子全长101.28μm,由头部和尾部组成,头部呈长辣椒状,长7.73μm,宽1.51μm,由顶体和细胞核组成;尾部细长,为93.18μm,为典型的"9+2"结构,由中段、主段和末段三部分组成。