小麦叶锈菌生理分化研究中的问题和改进意见

Stakman建立的用鉴别寄主鉴定锈菌生理小种的方法对抗病育种曾起了很大的作用,然而实践证明还存在不少问题。(1)生物间遗传学指出,Stakman建立的方法。其观点偏重于锈菌分类,而忽视寄主和病原物的相互作用。所以所用的鉴别寄主仅注意其鉴别作用,可与生产毫无关系,可以鉴定出许多小种,而不知道它们与生产有关的品种有什么关系。(2)在自然间寄主和病原物是以群体对群体起相互作用的,而传统研究是研究个体与个体的关系。此外,小种内存在变异性,被鉴定为同一小种的不同菌株的毒性不一定相同,任意选择一个菌株来测定品种的抗病性未必有代表性,用这种方法测出的抗病品种推广出去就容易引起抗病性丧失问题。(3)在不同生态条件下形成的锈菌的群体毒性不一定相同,这种毒性不同的类群我们称为生态类群。过去的小麦品种抗病性测定工作多在局限的条件下用人工接种进行。把用这种方法测出的抗病品种推广到广大的锈菌群体中去,也容易引起抗病性丧失问题。我们赞成今后研究小麦锈病应有群体观点,用毒力频率,毒力组合,抗性组合等方法来研究小麦群体和锈病群体的关系。应有生态观点,用异地鉴定来监测锈菌毒性和品种抗性的变异。应有进化观点,以基因鉴定来代替小种鉴定,把寄主的病原物相互作用研究放在遗传学基础上。在利用已知基因作鉴别寄主方面,虽然抗原的抗性基因可与Lr近等基因系的相同,但由于表现型相同基因型不一定相同,所以这两种材料都得同时采用,不能互相代替。抗性基因鉴定是复杂的。一般认为阿芙乐尔会有Lr26基因。Bastos认为除Lr26外,还有Lr3。杨文香认为除Lr26和Lr3外,还有Lrl4a。又Bastos认为洛夫林13含有Lr26和Lr3,相文香认为只含有Lr24,检查不到Lr3。     

Anaesthesia with ketamine/medetomidine in the rabbit: influence of route of administration and the effect of combination with butorphanol

Objective To compare the characteristics of anaesthesia induced with ketamine/medetomidine administered by the subcutaneous and intramuscular routes and to assess the effects of the addition of butorphanol to this combination. Study design Prospective randomised study. Animals Six female New Zealand White rabbits. Methods Rabbits were given one of four combinations of ketamine and medetomidine (K/M) either subcutaneously (SC) or intramuscularly (IM) on four successive occasions with a 7‐day interval between treatments. The dose combinations were; 15/0.25 mg kg^?1 SC; 15/0.25 mg kg^?1 IM; 15/0.5 mg kg^?1 SC, and 15/0.25 mg kg^?1 together with 0.4 mg kg^?1 butorphanol (K/M/B) SC. The effects of anaesthesia on arterial blood gas values and cardiovascular variables were recorded at predetermined time points. Toe and ear pinch reflexes were judged to determine the duration of surgical anaesthesia. Loss of the righting reflex was used to measure the duration of sleep time. Analyses used repeated measures analysis of variance. Results All groups lost the righting reflex and ear pinch response. Three animals in the groups that received K/M alone lost their toe pinch reflex, whereas four lost this reflex when given K/M/B. Time of onset of loss of the righting, toe and ear pinch reflexes did not differ significantly among the groups. The higher dose combination of medetomidine with ketamine and the combination of K/M/B produced a greater duration of loss of the ear pinch response than the lower dose of K/M administered by either route. No significant differences were found among the groups in the duration of loss of the toe pinch reflex. All animals developed a moderate bradycardia (mean heart rate <166 beats minute^?1) and moderate hypoxaemia (mean P_aO₂ < 6.0 kPa). Animals given butorphanol showed the greatest reduction in respiratory rate (31 ± 13 breaths minute^?1, p < 0.05) but this was not reflected in any significant differences in arterial PCO₂, PO₂ or pH among the groups. Conclusions Administration of K/M by the SC route produced equivalent effects in comparison to intramuscular administration. The addition of butorphanol increased the duration of anaesthesia, but produced a slight increase in the degree of respiratory depression. All dose rates resulted in hypoxaemia so oxygen should be administered when these combinations are used in rabbits. Clinical relevance Subcutaneous administration is both technically simpler and may cause less discomfort to the animal than IM injection, and so is preferred. The combination of K/M with butorphanol has relatively minor effects on the depth and duration of anaesthesia, so offers little advantage to the use of K/M alone.     

Pesticidal seed coats based on azadirachtin‐A: release kinetics,storage life and performance

BACKGROUND: Infestation of seeds by pests during storage leads to deterioration in quality. Seed coating is an effective option to overcome the menace. Unlike synthetic fungicidal seed coats, little is known of those based on botanicals. This study aims at developing azadirachtin‐A‐based pesticidal seed coats to maintain seed quality during storage. RESULTS: Polymer‐ and clay‐based coats containing azadirachtin‐A were prepared and evaluated for quality maintenance of soybean seed during storage. Gum acacia, gum tragacanth, rosin, ethyl cellulose, hydroxyethyl cellulose, polyethyl methacrylate, methyl cellulose, polyethylene glycol, polyvinyl chloride, polyvinyl acetate, polyvinyl pyrrolidone and Agrimer VA 6 polymers and the clay bentonite were used as carriers. The time for 50% release (t_1/2) of azadirachtin‐A into water from the seeds coated with the different coats ranged from 8.02 to 21.36 h. The half‐life (T_1/2) of azadirachtin‐A in the coats on seed ranged from 4.37 to 11.22 months, as compared with 3.45 months in azadirachtin‐A WP, showing an increase by a factor of nearly 1.3–3.3 over the latter. The coats apparently acted as a barrier to moisture to reduce azadirachtin‐A degradation and prevented proliferation of storage fungi. Polyethyl methacrylate, polyvinyl acetate and polyvinyl pyrrolidone were significantly superior to the other polymers. Azadirachtin‐A showed a significant positive correlation with seed germination and vigour, and negative correlation with moisture content. CONCLUSION: Effective polymeric carriers for seed coats based on azadirachtin‐A are reported. These checked seed deterioration during storage by acting as a barrier to moisture and reduced the degradation of azadirachtin‐A. Copyright © 2008 Society of Chemical Industry     

Abundance and origins of plasma lipids in sexually maturing female coho salmon Oncorhynchus kisutch (Walbaum) in culture

Coho salmon Oncorhynchus kisutch are semelparous spawners with highly synchronized oocyte growth. Plasma was collected from maturing female fish and plasma lipids were quantified by lipoprotein class. Stable ¹³C isotopes were employed to investigate the origins of plasma lipids. Plasma lipoproteins were partitioned into the very low density (VLDL), low density (LDL), high density (HDL) and very high density (VHDL) lipoprotein classes. Lipids from all lipoprotein classes increased between the lipid droplet and early vitellogenesis stages of oocyte growth and VHDL lipids continued to increase through mid vitellogenesis (P < 0.05). During vitellogenesis, total plasma lipid concentrations were similar to the sum of lipoprotein lipids (P = 0.51). Plasma vitellogenin determined by an ELISA method was very well correlated with VHDL lipid during vitellogenesis (R² = 0.91, n = 15). In general, the δ¹³C values of plasma lipids reflected that of feed (exogenous) and muscle (endogenous) lipids when feed and muscle δ¹³C values were similar, and were intermediate when differences existed between the two lipid sources. With one exception, the δ¹³C values of lipids from all lipoprotein classes within a plasma sample were similar. Results indicate that during sexual maturity, lipids from all plasma lipoprotein classes originate from a common pool of exogenous and endogenous lipids.     

Serum testosterone,sperm quality,cytological, physicochemical and biochemical characteristics of the prostatic fraction of dogs with prostatomegaly

Prostatomegaly is a common finding in older non‐neutered dogs. This study compared the serum testosterone, sperm quality and characteristics of the prostatic fraction between healthy dogs and dogs with prostatomegaly. Blood samples of ten dogs (five dogs from each group) were taken for serum testosterone measurement. Sperm motility, vigour, concentration, viability, membrane functionality and morphology were analysed in sperm‐rich fraction. Osmolality, pH, cell types, and albumin, haemoglobin, acid phosphatase, alkaline phosphatase, glucose, triglycerides, cholesterol, calcium, phosphorus, magnesium and chloride were analysed in prostatic fraction. Dogs with prostatomegaly have the lowest sperm motility, vigour, concentration and functional membrane. Dogs with prostatomegaly have the highest glucose, triglycerides and cholesterol. Glucose was the only constituent positively correlated with serum testosterone and prostate volume. It can be concluded that dogs with prostatomegaly have poorer sperm quality, and glucose, triglycerides and cholesterol in prostatic fraction can be used as prostatomegaly biomarkers.