不同土壤基质对峨眉假俭草抗寒性的影响

以峨眉假俭草为材料,种植在石骨质土、紫色土、垃圾、河滩土、粗砂5种不同的基质上.采用随机区组设计,研究不同基质对峨眉假俭草抗寒性的影响.结果表明,以河滩土为土壤基质种植的峨眉假俭草抗寒性最强,采用电导率法测得半致死温度(LT50)最低,9月为-2.74℃,1月下旬为-5.65℃.抗寒性与田间绿色期的观测相一致.     

优良暖季型观赏草抗寒性研究

为了解暖季型观赏草材料的抗寒性,以暖季型观赏草的叶片为试验材料,用改良电导法配合Logistic方程求拐点温度的方法测定了8份暖季型观赏草材料的半致死温度（LT50）,结合供试材料物候期的观测,对材料的抗寒性进行分析和评价。结果表明,经过等梯度的低温（10、5、0、-5、-10、-15、-20 和-25 ℃）处理后,供试材料叶片细胞伤害率和温度之间呈现明显的S形曲线,符合Logistic方程,拟合度较好。8份材料的抗寒性强弱顺序依次是紫田根（Saccharum arundinaceum）＞甜茅（S.ravennae）＞劲芒（Miscanthus sinensis ‘Strictus’）＞矮蒲苇（Cortaderia selloana）＞歌舞芒（M.sinensis ‘Cabaret’）＞遍生芒（M.sinensis ‘Cosmopolitan’）＞狼尾草（Pennisetum alopecuroides）＞柳枝稷(Panicum virgatum)。而LT50与物候期的相关分析表明,抗寒性与青绿期之间没有显著相关性,表明青绿期和抗寒性是可以同时得到改良的。     

低温胁迫对5种园林常绿灌木膜透性的影响

采用逐级降温程序模拟冰冻处理技术测定洒金桃叶珊瑚、无刺枸骨、南天竹、红花榷木和金边黄杨5种园林常绿灌木离体叶片的相对电导率,并用Logistic方程计算它们的半致死温度（LT50）。结果表明：5种园林常绿灌木的耐低温能力存在显著差异,且随着温度的降低,叶片电导率总体上呈S形曲线变化;计算得5种常绿灌木的LT50强弱次序为金边黄杨（-17．34℃）〉红花橙木（-12．34℃）〉南天竹（-11．35℃）〉无刺构骨（-8．91℃）〉洒金桃叶珊瑚（-7．42℃）。     

Comparison of G6PDH Activity and LT50 Between P.tomentosa and P.suaveolens During Freezing Acclimation

The differences of glucose-6P dehydrogenase(G6PDH) activity and freezing resistance induced by freezing acclima-tion between cuttings of freezing-sensitive P.tomentosa and freezing-resistant P.suaveolens were compared for exploring the role of G6PDH on the enhancement of freezing resistance induced by freezing acclimation.After 5d of freezing acclimation at -3℃ ,the LT50 of P.tomentosa has deereased from -6.2℃ incontrol cuttings to -14.3℃ in freezing acclimated ones,and the increase of LT50 of P.tomentosa has decreased from -6.2℃ in control cutting to -14.3℃ in freezing acclimated ones,and the increase of G6PDH activity was observed in freezing acclimated cuttings as compared with control ones.Whereas,when P.suaveolens was freezing acclimated at -20℃ for 5d,the LT50 has decreased from -27.1℃ in control cuttings to -43.5℃ in freezing acclimated ones,and the activity of G6PDH increased considerably.In addition,the increase of LT50 and the decrease of G6PDH activity resulting from 2d of deacclimation at 25℃ were found in two kinds of freezing acclimated cuttings.It is concluded that the increase in the activity of G6PDH may associate with the inherited freezing resistance of species and the enhancemen of freezing resistance of cuttings,and may play an important role in the antifreeze process under freezing temperature,which would provide the basis for the study on the molecular mechanism of freezing resistance in P.suaveolens and the cloning of gene associated with freezing resistance.     

日本厚朴抗寒生理研究

研究日本厚朴的越冬期生理变化规律;探求日本厚朴的安全越冬能力。以日本厚朴引种实生苗为试材,于越冬期不同阶段设置温度梯度,系统分析低温胁迫下其植株的生理生化变化,并以白玉兰为对照。结果表明:休眠初期组织内SOD,MDA,游离脯氨酸和可溶性糖的含量均比较低,休眠中期温度降低,各种物质含量增加,其中可溶性糖含量变化明显,休眠末期各种物质含量减少;低温处理过程中各种物质含量也有不同程度增加,其中游离脯氨酸含量变化显著;日本厚朴的半致死温度略低于白玉兰。越冬过程中,日本厚朴组织中可溶性糖含量变化显著,可以作为鉴定日本厚朴抗寒性的生理指标,在沈阳地区背风向阳处可以安全越冬。     

用电导法配合Logistic方程确定杏花期的抗寒性

用电导法配以Ｌｏｇｉｓｔｉｃ方程，测定了６个不同生态地区杏（ａｐｒｉｃｏｔ）品种花蕾和盛开花朵的半致死温度（ＬＴ５０）。实验结果表明，杏花器官不同部位的抗寒性大小，雌蕊＜雄蕊＜花瓣，并证明了北方品种较南方品种耐寒。杏花蕾的ＬＴ５０在－６～－９℃，盛开花朵的ＬＴ５０在－４～－６℃．     

猪源大肠杆菌志贺样毒素2型突变体B亚基与LTB基因的融合与表达

猪水肿病的主要毒力因子是志贺样毒素的2型突变体(Stx2e),毒素的A亚基是有毒的酶活性单位,B亚基无毒,介导毒素与受体的结合。为了增加B亚基的免疫原性,采用重叠PCR将猪源志贺样毒素Ⅱ型突变体B亚单位(Stx2e B)连接至热敏肠毒素的B亚单位(LTB)成熟肽N末端,获得Stx2e B与LTB相连的融合蛋白基因Stx2e B-LTB。融合基因克隆到表达载体pQE30中,在IPTG的诱导下,融合基因在大肠杆菌中获得表达,表达量占细菌总蛋白的8%。融合蛋白的获得为猪水肿病基因工程亚单位疫苗的制备、猪水肿病的预防奠定了基础。     

Adipose tissue and muscle fatty acid profiles of steers fed red clover silage with and without flaxseed

The current study examined the effects of inclusion of flaxseed in a red clover silage diet on growth, carcass quality, adipose tissue and muscle fatty acid (FA) profiles of beef steers. Twelve British×Continental crossbred steers (363±26.5 kg) were randomly assigned to two pens and fed diets containing 70% red clover silage, 15% steam rolled barley/vitamin–mineral supplement and either additional 15% steam rolled barley or 15% triple rolled flaxseed (all DM basis) for 215 d. Diet had no effect (P>0.05) on average daily gain or carcass quality atributes. Overall, FA profiles in all tissues followed similar trends when flaxseed was added to the diet but intramuscular fat had the highest proportions of n-3 and n-6 polyunsaturated FA (PUFA) while subcutaneous fat had largest proportions of conjugated linoleic acids (CLA) and perirenal fat had the highest proportions of trans-18:1 isomers, particularly vaccenic acid (VA). Feeding flaxseed increased (P<0.05) percentages of α-linolenic acid (ALA; 1.1–1.6% of total FA), total n-3 PUFA, conjugated linolenic acids, non-conjugated linoleic acids (mostly t11,c15-18:2), and led to unprecedented increases in CLA (mainly rumenic acid, RA; 1.1–2.9%), and trans-18:1 isomers (chiefly VA; 5.9–9.5%) in muscle and adipose tissues. Flaxseed also reduced individual and total n-6 PUFA, cis-monounsaturated FA, branched-chain FA and saturated FA (mainly 16:0) in beef lipids. Overall, feeding flaxseed in a red clover silage diet enhanced the levels of FA with a positive health image (ALA, 2-fold; RA, 3 to 4-fold and VA, 4 to 5-fold) and reduced the levels of less desirable FA (n-6 PUFA; 14:0, 16:0) in muscle and adipose tissues without adverse effects on growth and carcass quality. Differences in tissue FA composition were also noted, and high levels of VA in perirenal fat in particular have potential for use in testing for health effects and development of value added beef and other food products.     

密叶杨×胡杨6个杂交种抗寒性的初步鉴定

[目的]评价几个优良密叶杨(Populus talassica Kom.)×胡杨(Populus euphratica Oliv)杂交种的抗寒能力.[方法]对其一年生休眠枝条进行了低温胁迫试验,采用电导法拟合Logistic方程得出半致死温度(LT50),用恢复生长法进行验证.[结果]8个供试树种中,胡杨的抗寒性最强,6个密叶杨×胡杨杂交种中,胡杂-1和胡杂-2的抗寒性较强,胡杂-35最弱.恢复生长法得到的出芽率排序与半致死温度排序具有一致性.[结论]胡杂-1和胡杂-2具有较好的抗寒性.     

3种园林植物耐寒性的研究

[目的]测定西鹃、小蜡、南洋杉3种植物的半致死温度,为各地园林应用提供理论参考。[方法]电导法配合Logistic方程,通过DPS9.5统计软件进行非线性回归分析确定半致死温度;采用茚三酮比色法,测定叶片游离脯氨酸含量。[结果]用电导法配合Logistic方程计算小蜡、西鹃、南洋杉半致死温度,分别为-7.12、-8.61、-6.03℃。[结论]自然生长的成年小蜡、西鹃、南洋杉在不同休眠时期耐寒能力有一定差异。