气候变化对木本植物光合产物分配与果实品质的影响

大气CO_2浓度升高引起的温室效应导致全球地表平均气温升高,引起全球降水格局发生变化,对农林业生产与生态系统产生重要影响。木本植物对气候变化的生理生态响应机制受到极大关注。该文综述了CO_2浓度升高、气温升高及干旱胁迫对木本植物光合产物分配与果实品质影响的研究进展。模拟试验表明,随着大气CO_2浓度升高,植物的光合能力会增大,但长期生长在高CO_2浓度下的植物会出现光合能力下降的光适应现象;气温升高会降低植株光合酶活性和叶绿素含量等,从而导致光合速率下降;干旱胁迫通过减小气孔导度和光合活性来降低光合作用。CO_2浓度升高或干旱胁迫下,光合产物向根系分配的比例增加,温度升高则会降低植物的根冠比。在果实品质方面,CO_2浓度升高增加了果实中的可溶性固形物含量;气温升高会影响果实生长,部分糖含量及有机酸含量增加;干旱胁迫对果实生长有一定抑制作用,但增加了可溶性糖、维生素C含量等;同时认为气温升高减缓干旱胁迫对果实品质的抑制作用,提高果实品质。因此,气候变化引起的环境胁迫有助于果实糖分的累积。     

Effects of Intrauterine Devices in Mares: A Histomorphological and Immunohistochemical Evaluation of the Endometrium

Oestrous suppression by intrauterine devices (IUDs) is caused by prolongation of luteal function, but the biological mechanism is unknown. The aim of the study was to investigate mechanisms which could explain the action of IUDs. Thirty mares were age‐matched and either inseminated (AI, n = 15) or fitted with an IUD (IUD, n = 15) and subsequently divided into four groups: AI‐P, pregnant (n = 8); AI‐N, non‐pregnant (n = 7); IUD‐P, prolonged luteal phase (n = 7); and IUD‐N, normal luteal phase (n = 8). The median ages were 5.5 and 7 years in AI‐P and IUD‐P groups and 14 and 11 years in AI‐N and IUD‐N groups, respectively. On Day 15 after ovulation, an endometrial biopsy was obtained to study histomorphological and immunohistochemical expression patterns of uterine proteins (uteroferrin, UF; uterocalin, UC; uteroglobin, UG), oestrogen and progesterone receptors (ER, PR), proliferation marker Ki‐67 and content of inflammatory cells. Expression of UF was higher in IUD mares; the difference between pregnant and IUD‐P mares was significant. Mares exhibiting a prolonged luteal phase (AI‐P, IUD‐P) showed only mild angiosclerosis and lower expression of both ER and PR than mares with a normal luteal phase (AI‐N, IUD‐N). No significant differences were detected in the numbers of inflammatory cells, with the exception of macrophages, which were more numerous in AI‐P than AI‐N mares. Although inflammatory cells were not detected in IUD mares, increased UF levels may indicate chronic inflammation. Young age and normality of the endometrial blood vessels may improve the efficacy of IUDs.     

Transmission studies of Hendra virus (equine morbilli-virus) in fruit bats, horses and cats

Objective To determine the infectivity and transmissibility of Hendra virus (HeV). Design A disease transmission study using fruit bats, horses and cats. Procedure Eight grey-headed fruit bats (Pteropus poliocephalus) were inoculated and housed in contact with three uninfected bats and two uninfected horses. In a second exper iment, four horses were inoculated by subcutaneous injection and intranasal inoculation and housed in contact with three uninfected horses and six uninfected cats. In a third experi ment, 12 cats were inoculated and housed in contact with three uninfected horses. Two surviving horses were inoculated at the conclusion of the third experiment: the first orally and the second by nasal swabbing. All animals were necropsied and examined by gross and microscopic pathological methods, immunoperoxidase to detect viral antigen in formalin-fixed tissues, virus isolation was attempted on tissues and SNT and ELISA methods were used to detect HeV-specific antibody. Results Clinical disease was not observed in the fruit bats, although six of eight inoculated bats developed antibody against HeV, and two of six developed vascular lesions which contained viral antigen. The in-contact bats and horses did not seroconvert. Three of four horses that were inoculated devel oped acute disease, but in-contact horses and cats were not infected. In the third experiment, one of three in-contact horses contracted disease. At the time of necropsy, high titres of HeV were detected in the kidneys of six acutely infected horses, in the urine of four horses and the mouth of two, but not in the nasal cavities or tracheas. Conclusions Grey-headed fruit bats seroconvert and develop subclinical disease when inoculated with HeV. Horses can be infected by oronasal routes and can excrete HeV in urine and saliva. It is possible to transmit HeV from cats to horses. Transmission from P poliocephalus t o horses could not be proven and neither could transmission from horses to horses or horses to cats. Under the experimental conditions of the study the virus is not highly contagious.     

松香催化酯化反应研究进展

综述了30年来松香催化酯化反应的研究进展,重点考察了反应使用的催化剂、反应条件以及产品性能,对进一步研究松香酯化改性具有指导意义,并有利于我国松香资源的充分利用。     

新的玉米矮秆突变基因的鉴定与遗传分析

Dt基因是玉米显性矮秆基因,被定位于玉米的第10条染色体长臂,目前报道的显性矮秆基因只有D8(Mpl1)和D9,它们分别位于染色体1的长臂和染色体5的短臂;Dt矮秆突变体属于赤霉素敏感型,含有D8,D9基因的材料对赤霉素不敏感;Dt基因与D8,D9基因的等位性分析表明,Dt与D8,D9为非等位基因,进一步证明了Dt基因是一个新发现的玉米显性矮秆基因.     

聚合松香基环氧树脂的合成与表征

以聚合松香为原料,与环氧氯丙烷进行酯化反应、闭环反应,合成了聚合松香基环氧树脂,并对产物的红外光谱和核磁共振谱进行了解析.重点讨论了酯化反应、闭环反应影响因素对产物性能的影响.当适宜的反应条件为:聚合松香与环氧氯丙烷物质的量比约为1∶ 8,反应温度75℃,反应总时间8h,合成的环氧树脂的环氧值为0.19mol/100g,黏度(30℃)为30.8Pa · s,酸值为0.2mg/g.     

人参浸提液对桔梗种子萌发的影响

为了促进桔梗与人参轮作的应用推广,采用培养皿滤纸法研究了人参浸提液对桔梗种子萌发的影响,同时研究了赤霉素对高浓度人参浸提液抑制桔梗种子萌发的缓解作用.结果表明:人参浸提液浓度较低时对桔梗种子萌发并无显著影响,但人参浸提液浓度较高时却抑制了桔梗种子的萌发;赤霉素处理有助于改善高浓度人参浸提液对桔梗种子萌发的抑制,但赤霉素...     

中草药饲料添加剂对奶牛产奶量及牛奶品质影响初探

试验选用黄芪、王不流行等15味中草药添加剂,研究其对奶牛产奶量及牛奶品质的影响.结果显示:在不同泌乳时期,添加中草药使得不同泌乳期奶牛产奶量都有所提高,泌乳初期、泌乳盛期和泌乳中期各试验组的日均泌乳量均比其相应对照组日均泌乳量提高12.2%、24.5%和3.4%.对试验牛及其牛奶理化指标测试结果显示:饲喂中草药添加剂后各泌乳期乳脂含量和游离脂肪酸含量降低、蛋白质含量和非脂类干物质含量提高,但变化不大,其物理指标也没有大的波动.由此可见,饲喂中草药添加剂后奶牛的理化指标均正常,既保证了奶牛的健康又保证了牛奶的安全性、无污染性和天然性.