从黑茶中分离和筛选产单宁酶菌株

茶叶中富含单宁化合物。从分离自黑茶的真菌菌株中,筛选高产单宁酶的菌株;进而分离纯化单宁酶,分析单宁酶对茶汤的转溶效果。从不同产地的3个黑茶样品中,共分离获得44个真菌分离物;经初步鉴定,这些真菌分离物以曲霉属（Aspergillus）、青霉属（Penicillium）和散囊菌属（Eurotium）的真菌居多。以单宁酸为底物的鉴别培养基初筛表明,其中26个真菌分离物在鉴别平板上产生透明圈,显示单宁水解酶活性;通过固体发酵复筛,筛选到1株产单宁酶活性较高的菌株,初步鉴定为青霉属（Penicillium）菌株,命名为青霉MP-24菌株。青霉MP-24可以以茶叶、茶梗和麸皮等农副产品作为原料固体发酵产生单宁酶。以麸皮为原料的发酵产物经过硫酸铵分级沉淀、DEAE阴离子交换层析和葡聚糖G-150凝胶层析等分离纯化步骤,得到分子量为70 kDa的单一蛋白质条带,单宁酶活力达到603.68 U/mg。纯化获得的单宁酶对茶汤有良好的转溶效果。研究结果表明,在黑茶相关微生物中含有丰富的产单宁酶菌株,是工业酶制剂的重要资源。     

会同杉木人工林不同生长阶段植物固碳特征

为了探讨杉木人工林不同生长阶段的固碳功能,以会同杉木林为研究对象,在定位连续测定林分生物量和碳素含量的基础上,研究了杉木林不同年龄阶段的储存碳量及在各组分的分配和植物固碳能力。结果表明:杉木各器官碳素含量树叶树皮树根树干树枝,且随着林龄增加而增大;杉木林植被储存碳量为22.93—86.98 t/hm2,各个层次储存碳量乔木层林下植被层枯死物层;乔木层碳素在器官间的相对分配大小依次为树干树根树叶树皮树枝;树干碳素分配比随着年龄增长而增大,树枝、树叶随年龄增长而减少,树根和树皮虽有波动,但变化较平稳;树枝、树叶、树干、树皮和树根碳积累年均变化都呈单峰形曲线,但波峰出现林龄各有不同;杉木林固碳动态特征可分为固碳功能建立、固碳能力迅速增长、固碳能力最大、固碳能力相对平稳和固碳能力下降等5个阶段;杉木林的固碳能力,不仅受不同生长阶段生长发育生物学特性的制约,而且还受林分冠层结构特征以及土壤肥力条件的影响。     

气温和降雨量对中国湿地生态系统CO2交换的影响

湿地由于具有较高的初级生产力以及较低的有机质降解速率而成为缓解全球变暖的潜在有效碳汇.虽然近年来中国湿地生态系统CO₂交换过程及其影响机制研究取得了一系列进展,但尚缺乏对数据进行系统性整合分析.基于29篇文献的数据,对中国21个典型湿地植被净生态系统CO₂交换(NEE)、生态系统呼吸(R_eco)、总初级生产力(GPP)、NEE的光响应参数以及R_eco的温度响应参数进行整合分析,并探讨了这些指标对温度与降雨的响应.结果表明： 年尺度上,气温和降雨量对NEE(R²=50%,R²=57% )、GPP(R²=60%,R²=50%)和R_eco(R²=44%,R²=50%)均有显著影响(P<0.05).生长季尺度上,NEE (R²=50%)、GPP (R²=36%)和R_eco(R²=19%)与气温呈显著相关(P<0.05);同时NEE(R²=33%)和GPP(R²=25%)也与降雨量呈显著相关(P<0.05),但R_eco与降雨量的相关关系不显著(P>0.05).生长季降雨量与最大光合速率(A_max)之间呈显著相关 (P<0.01),但与表观量子产率(α)、白天生态系统呼吸速率(R_eco,day)无显著相关(P>0.05).生长季气温对α、A_max和R_{eco, day}均无显著影响(P>0.05).生态系统基础呼吸速率(R_ref)与降雨量无显著相关(P>0.05),但是生态系统呼吸的温度敏感系数(Q₁₀)与降雨量呈显著的线性负相关(P<0.05),同时气温对Q₁₀(R²=0.35)、R_ref(R²=0.46)均产生显著影响(P<0.05).     

花椒(Zanthoxylum bungeamun)种植对喀斯特山区土壤水稳性团聚体分布及有机碳周转的影响

以贵州西南部喀斯特山区35年生和14年生花椒林为研究对象,并以未退耕旱地为对照,研究表层土壤(0~20 cm)水稳性团聚体分布及有机碳矿化特征,探讨土壤有机碳周转对不同花椒种植年限的响应。结果表明:随团聚体粒径的降低,两种年龄花椒林土壤水稳性团聚体含量呈现先增加后减少的倒"V"形分布,土壤水稳性团聚体分布主要出现在5~2、2~1和1~0.5 mm 3个粒级中;与旱地相比,花椒种植明显增加了全土和团聚体中有机碳和活性有机碳含量,并以14年生花椒林较高,而35年生花椒林存在较明显的衰减;随花椒种植年限的增加,土壤有机碳矿化累积量呈递减趋势,但土壤有机碳周转半衰期以14年生花椒林较长,显著高于旱地和35年生花椒林,表明14年生花椒林土壤有机碳更易累积,表现出较好的土壤碳固存能力;喀斯特山区种植花椒后,土壤有机碳存在"汇-源"的转换过程,因此花椒种植应注重长期维护管理,防止土壤质量的衰退。     

东乡野生稻BILs群体耐低氮性表型性状指标筛选及其综合评价

为了鉴定东乡野生稻及其后代群体的耐低氮性,研究低氮和正常氮2种处理下“协青早B//东乡野生稻/协青早B”BC₁-F₁₂回交重组自交系株高、抽穗期、穗长、有效穗数、穗实粒数、穗总粒数、着粒密度、结实率、千粒重和单株产量等10个表型性状,利用主成分分析和模糊隶属函数对BILs群体的耐低氮性进行综合评价.结果表明： 株系116、143和157的耐低氮性强,可作为东乡野生稻耐低氮性遗传研究和水稻耐低氮性育种的中间材料.采用逐步回归分析法建立了耐低氮性最优回归方程,筛选到株高、穗总粒数、结实率、千粒重和单株产量等5个性状相对值可作为水稻全生育期耐低氮性的综合评价指标.因此,在水稻耐低氮性遗传改良中,应注重对这5个性状,尤其是穗总粒数和单株产量相对值的选择.
     

钾肥类型对菜心(菜薹)生长、细胞保护酶和内源激素的影响

为探讨钾肥类型对菜心(Brassica campestris L. ssp. chinensis var. utilis Tsen et Lee)的作用效应,研究了不同钾肥类型和水平对菜心生长、细胞保护酶和内源激素的影响。结果表明,氯化钾或硫酸钾处理可提高菜心叶片的POD 和CAT 活性、IAA 和GA₃ 含量,降低MDA 含量,提高菜薹产量。随着钾水平的提高,叶片IAA 和GA₃ 含量、POD 和CAT 活性以及菜薹质量明显提高,MDA 含量降低。当施钾90 kg hm^-2 时,叶片的GA₃ 和IAA 含量显著下降,而POD 活性和菜薹产量没有显著变化。在相同水平下,氯化钾与硫酸钾对植株生长、菜薹产量、叶片GA₃ 含量的影响不显著。当施钾0~90 kg hm^-2 时,氯化钾处理的叶片POD 活性显著高于硫酸钾处理;而施钾135~180 kg hm^-2 时,氯化钾处理的叶片POD 活性则显著低于硫酸钾处理。除了90 kg hm^-2 氯化钾处理的CAT 活性和45 kg hm^-2 氯化钾处理的MDA 含量低于硫酸钾处理以及90 kg hm^-2 和180 kg hm^-2 氯化钾处理的IAA 含量高于硫酸钾处理的外,相同水平氯化钾和硫酸钾处理的CAT 活性、MDA 含量和IAA 含量没有显著差异。可见,钾肥类型对菜心的活性氧代谢系统及内源激素含量有一定的影响,但氯化钾与硫酸钾对菜心的施用效果相当,生产上可采用氯化钾代替硫酸钾以节约肥料成本,K₂O 施用量以90 kg hm^-2 为宜。     

Transient transfection of CHO cells using linear polyethylenimine is a simple and effective means of producing rainbow trout recombinant IFN-γ protein

A practical method was developed for the transient transfection of Chinese hamster ovary (CHO) cells with 25 kDa linear polyethylenimine (PEI) then optimal culture conditions determined for the production of rainbow trout (Oncorhynchus mykiss) IFN-γ recombinant protein. We found that culture temperature had a significant impact upon recombinant protein yield, with best results being obtained at 32 °C. However the amount of serum added to the culture medium had no effect upon recombinant IFN-γ (rIFN-γ) production. In this study maximal rIFN-γ yields and minimal PEI toxicity were achieved using a DNA/PEI ratio of 1:8, where the amount of PEI did not exceed 10 µg per 5 ml of RPMI1640 culture medium, with cells subsequently cultured at 32 °C for 7 days. Thus, linear PEI is a technically simple and cost-efficient method for the transient transfection of CHO cells and is compatible with serum-free operations.     

First Report of Cucumber mosaic virus Infecting Chinese Mallow in China

The virus in naturally infected, stunted Chinese mallow plants and mosaic leaves was identified as Cucumber mosaic virus (CMV). Six symptomatic plants and one symptomless plant were collected in Chongqing, China. DAS‐ELISA suggested CMV was likely associated with the diseased Chinese mallow. Double‐stranded RNA was extracted from the samples, analysed by RT‐PCR, and the coding sequences of their coat proteins (CPs) were sequenced. The results further confirmed CMV was the pathogen causing Chinese mallow stunted, mosaic disease. The isolate was named CMV‐DXC. The full sequence of CMV‐DXC CP was determined, and it had the highest nucleotide identity (99.4%) of those of CMV‐lily, CMV‐WSJ and CMV‐Hnt, respectively. Phylogenetic analysis shows that CMV‐DXC belongs to CMV subgroup II. To our knowledge, this is the first report of CMV infecting Chinese mallow in China.     

First Report of Greeneria uvicola Causing Bitter Rot of Grape in China

In 2013, bitter rot of grape was observed in Changbei Vineyard located in Nanchang City, Jiangxi Province, China. Greeneria species was consistently isolated from the diseased grape berries (Vitis labruscana cv. Kyoho) at approximately 91% of isolation rate in three independent experiments. The species was identified as Greeneria uvicola based on the morphological characteristics, cultural appearance and sequence analysis. Koch's postulates were fulfilled through pathogenicity tests on detached healthy Kyoho grape berries. To our knowledge, this is the first report of G. uvicola causing bitter rot of grape in China.