盐度和营养对凡纳滨对虾谷氨酸脱氢酶和丙酮酸羧激酶活性的影响

研究了盐度和饲料营养水平与凡纳滨对虾谷氨酸脱氢酶和磷酸烯醇式丙酮酸羧激酶活性间的关系。结果表明：随着盐度的上升,凡纳滨对虾鳃组织中谷氨酸脱氢酶活性逐渐上升：肝胰脏中磷酸烯醇式丙酮酸羧激酶活性逐渐下降。同一盐度水平下,谷氨酸脱氢酶活性随饲料蛋白质水平升高而升高,差异显著（P〈0．05）。方差分析表明,盐度和饲料蛋白质水平单因素对凡纳滨对虾谷氨酸脱氢酶和磷酸烯醇式丙酮酸羧激酶活性影响差异显著（P〈0．05）;器因子交互作用对凡纳滨对虾的谷氨酸脱氢酶活性影响差异不显著（P〉0．05）,对磷酸烯醇式丙酮酸羧激酶活性影响差异显著（P〈0．05）。     

Molecular characterization and inheritance of resistance to ACCase-inhibiting herbicides in Lolium rigidum

The molecular basis and mode of inheritance of resistance to ACCase-inhibiting herbicides were investigated in a biotype of Lolium rigidum Gaud that has been discovered in Israel. Dose-response experiments at the whole-plant level have revealed that the resistant biotype was more resistant (6.3- to 40-fold) than the susceptible wild-type to ACCase-inhibiting herbicides. A 276-bp genomic DNA encoding the carboxyltransferase domain within the chloroplastic ACCase from resistant and susceptible biotypes were amplified by PCR and analyzed. Sequence comparison revealed that a single isoleucine-to-leucine substitution differentiated ACCases from susceptible and resistant biotypes (corresponds to residue 1769 of wheat ACCase, Acc No AF029895). A PCR amplification of specific alleles (PASA) method was developed to detect the allele composition leading to isoleucine-leucine mutation. ACCase extracted from homozygote resistant, heterozygote and homozygote susceptible plants showed IC50 values of 25.8, 5.6 and 0.6 microM, respectively, suggesting that alteration in the ACCase is governed by a co-dominant gene. The inheritance studies confirmed that the resistance of L rigidum to ACCase-inhibiting herbicides is governed by a single, nuclear and co-dominant gene.     

Effect of Water Stress on Pyruvaté, Pi Dikinase and Phosphoenol Pyruvate Carboxylase Activities in the Leaves of Two Cultivars of Sorghum (Sorghum bicolor L.)

The effect of withholding water on the specific activities of pyruvate, orthophosphate dikinase (PPDK EC 2.7.9.1.) and phosphoenol pyruvate carboxylase (PEPC, EC 4.1.1.31) was studied in two cultivars of Sorghum bicolor L. different in their sensitivity to water deficit. The drought sensitive cultivar ICSV 1063 and the more resistant cultivar MIGSOR were subjected to water deficit in controlled conditions. The results showed a decrease in both enzyme specific activities, higher for drought sensitive cultivar ICSV 1063, when leaf water potential (Ψ) was lowered to -2.3 MPa. Following rewatering, enzyme specific activities increased in both cultivars, with the increase being more significant in MIGSOR. Relative water content (RWC) decreased significantly for water-stressed ICSV 1063 cultivar, lower for MIGSOR and returned quickly to that of control plants upon rehydration. Net photosynthesis showed a decrease for water-stressed plants, higher for ICSV 1063. At minimal Ψ, net photosynthesis was completely inhibited, with the stomata being closed After rehydration, MIGSOR showed a better recovery in photosynthesis but never reached the initial values of day 0. Water stress had a striking effect, both on net photosynthesis by regulation of stomatal aperture and on PPDK and PEPC activities, although the enzymes were still active when photosynthesis ceased. Therefore the level of PPDK and PEPC activities may contribute to the limitation of photosynthetic carbon dioxide fixation.     

瘦蛋白对犊牛肝细胞PEPCK mRNA表达及其活性的影响

取单层培养36 h生长良好的犊牛肝细胞,采用单因素重复试验,分别添加0、2.5、5、10、50、100 ng/mL的牛重组牛瘦蛋白(leptin),每个处理3个重复(每重复2孔),再培养12 h后分别提取RNA和制备细胞上清液.应用荧光定量PCR方法检测外源NPY 对肝细胞糖异生关键酶磷酸烯醇式丙酮酸羧激酶(Phosphoenolpyruvate carboxykinase,PEPCK)基因表达的影响,同时用比色法检测其对肝细胞PEPCK活性的影响.结果表明:一定浓度的leptin显著抑制了肝细胞PEPCK mRNA表达,降低了PEPCK活性.     

杂交水稻(F_1)光合作用的优势及其与氮素营养的关系

在低N和高N条件下,比较研究了杂交水稻F_1代在生殖生长期功能叶的一些光合作用代谢特性与其亲本的差异。结果指出,杂交稻功能叶的叶绿素含量,光合磷酸化活力和ATP含量在高N条件下的杂种优势比低N条件的大。同样,杂交稻功能叶中~(14)CO_2同化率,RuBP羧化酶的活力及其酶蛋白含量在低N处理中无杂交优势,而高N处理却具有明显的正优势。这表明杂交水稻功能叶的光合作用的杂种优势随N营养水平提高而增大。因此,在预测杂交水稻光合作用优势时必须考虑氮素营养状况。     

巴西橡胶两品系叶片RuBP羧化酶的免疫荧光定位

巴西橡胶树的 2个品系即 RRIM60 0和 IAN873的维管束鞘细胞富含叶绿体 ,但没有“Kranz”结构 .用从烟草提纯的Ru BP羧化酶制备兔抗 Ru BP羧化酶抗体 ,并以 FITC荧光素标记抗体 .采用直接免疫荧光法对典型的 C3植物水稻、C4 植物甘蔗和巴西橡胶树等进行了 Ru BP羧化酶的定位 .结果表明 :C3和 C4 植物叶切片中 Ru BP羧化酶的分布明显不同 ,C3植物的特异荧光存在于叶肉细胞 ,而 C4 植物的特异荧光绝大部分存在于维管束鞘细胞 .巴西橡胶树 IAN873和 RRIM60 0品系的叶肉细胞和维管束鞘细胞均存在 Ru BP羧化酶 .上述结果表明 ,巴西橡胶的一些品系 (如 IAN873、RRIM60 0 )可能属于C3-C4 中间型植物     

Development of rice (Oryza sativa) lines resistant to aryloxyphenoxypropionate herbicides through induced mutation with gamma rays

The aryloxyphenoxypropionate herbicides (APPs) are graminicides with excellent control of many grass weeds species, including weedy rice (Oryza sativa L.). These herbicides block the fatty acid biosynthesis by inhibiting the enzyme acetyl‐CoA carboxylase (ACCase), resulting in the death of susceptible plants. Inducing mutation with gamma rays to rice seeds, two lines resistant to APPs herbicides were developed. Plant dose–response assays confirmed the resistance to the APPS herbicides quizalofop‐p‐ethyl and haloxyfop‐p‐methyl. The carboxyltransferase domain fragments of ACCase from the resistant biotype and susceptible control were sequenced and compared. A point mutation was detected in the amino acid position 2,027 (Rice Genome Annotation Project: Os05g22940.1). Results indicated that resistance to APPs is a consequence of an altered ACCase enzyme that confers resistance. The use of APPs herbicide‐resistant rice lines represents an innovative and promising alternative for weedy rice control in paddy rice systems.     

乙酰辅酶A羧化酶抑制剂对肥胖小鼠的减肥效果

[目的]研究乙酰辅酶A羧化酶抑制剂对肥胖小鼠肥胖程度的影响。[方法]建立肥胖动物模型,然后随机分组,试验组以乙酰辅酶A羧化酶抑制剂按照50mg/(kg.bw.d)的剂量灌胃,对照组小鼠以去离子水灌胃。给药过程中,记录小鼠采食量和饮水量的变化情况。给药3周后,测定体重和体长,进行李氏指数的计算;称量脂肪,计算性器官周围脂肪占小鼠体重的比重;测定血清中胆固醇和甘油三酯的相对含量。[结果]乙酰辅酶A羧化酶抑制剂能抑制小鼠体重的增加,可减少肥胖小鼠的肥胖程度;能降低肥胖小鼠血清中的甘油三酯和胆固醇含量。[结论]乙酰辅酶A羧化酶抑制剂对肥胖小鼠有减肥作用,对小鼠的正常饮食没有明显影响。