Loss of pathogenicity in the blue-stain fungus Ceratocystis polonica

The pathogenicity and growth of six cultures of the bark-beetle-associated blue-stain fungus Ceratocystis polonica were compared. Four were subcultures, established at different times, of the same isolate (80–53/7), and at least one of these was suspected to have lost its pathogenicity to Norway spruce ( Picea abies ) during subculturing. Two other cultures (93–208/115 and 94–169/13) were pathogenic. The pathogenicity of all cultures to Norway spruce was compared in three inoculation experiments, using (i) massive inoculation (≈144 inoculations per tree), (ii) low-density inoculation (14 inoculations per tree) of larger trees and (iii) single inoculation of 2-year-old seedlings. Fungal growth rates were tested in vitro on malt agar, and on malt agar under oxygen-deficient conditions. Isolates 93–208/115 and 94–169/13 and one of the subcultures of isolate 80–53/7 were pathogenic in all three inoculation experiments. Two other subcultures were nonpathogenic, while the last subculture was intermediate. The pathogenic cultures had higher growth rates on malt agar than the nonpathogenic and intermediate cultures, and they also grew better under oxygen-deficient conditions. These results demonstrate that blue-stain fungi may lose their pathogenicity after serial vegetative transfers on artificial substrates. The results are also consistent with the hypothesis that rapid growth and the ability to grow in oxygen-poor environments are important pathogenicity factors in blue-stain fungi.     

An historical perspective of the ‘Blandford Fly’ (Simulium posticatum Meigen) problem and attempted control of the pest species using Bacillus thuringiensis var. israelensis

This review deals with the biology and control of a biting pest species, Simulium posticatum, which has been responsible for a considerable degree of distress to the human population in the vicinity of the River Stour in Dorset. Each phase of the life cycle of the insect is considered in relation to possible control measures. An account is given of how this information has been combined with the use of Bacillus thuringiensis in a successful, precisely targeted attack on the pest.     

小麦根腐镰刀菌鉴定及其生物学特性

１９９１－１９９４年对山东省１１县市的小麦根腐病标样进行病原分离培养及致病性测定，鉴定出６种镰刀菌，有黄色镰刀菌（Ｆｕｓａｒｉｕｍ ｃｕｌｍｏｒｕｍ（Ｓｍｉｔｈ Ｓａｃｃ）、禾谷镰刀苏（Ｆ ｇｒａｍｉｎｅａｒｕｍ Ｓｃｈｗ）、尖孢镰刀苏（Ｆ ｏｘｙｓｐｏｒｕｍ Ｓｃｈｌ）、串珠镰刀苏（Ｆ ｍｏｎｉｌｉｆｏｒｍｅ Ｓｈｅｌｄ）茄病镰刀苏（Ｆ ｓｏｌａｎｉ（Ｍａｒｔ） Ｓａｃｃ）及木贼镰刀菌（Ｆ ｅｑ     

应用Taylors指数法则进行种间与种内分布格局的分析与数据转换

Taylor＇s指数法则中的b值因种而有不同,表现十分稳定。但在有些情况下,在生活习性相近的不同种之间,b值却相同。另外,Taylor＇s参数b值尚因种在不同时期和虫态的种群而表现差异。     

Efficacy of Different Control Methods Applied Separately and in Combination in Managing Root-knot Nematodes (Meloidogyne spp.) in Common Beans

Investigations on the efficacy of various methods of managing root-knot nematodes in microplots and under field conditions revealed that soil solarization, Furadan 5G and Tagetes erecta applied separately or in combination with other control methods, were the most effective in reducing the numbers of three root-knot nematodes, and root gall and egg mass indices. These management methods also resulted in significant increases (P0.05) in number of pods per plant, number of seeds per pod and 100-seed weight, and increased seed yield by up to 96.7 percent. Farmyard manure and Crotalaria ochroleuca were the least effective treatments. The use of T. erecta was the most economical root-knot nematode control method.     

氧气对低地鸡蛋胚胎死亡和孵化率的影响

通过模拟常压低氧和高海拔增氧孵化试验，研究了氧气浓度对低地良种鸡蛋胚胎死亡率和孵化率的影响。死亡胚胎的分布用2阶段增长模型分析。模拟2900m海拔常压低氧孵化增加了胚胎后期死亡率，使孵化率降低到接近2900m海拔实际孵化率水平；2900m海拔全期增氧孵化可以有效降低前期和后期胚胎死亡率，大大提高孵化率；阶段增氧孵化也能不同程度提高孵化率，改变胚胎死亡分布，其中效果最好的为前期增氧组。结果说明低氧是影响2900m海拔鸡蛋孵化的最主要因素。     

扁穗牛鞭草组织浸出液对潜在混生种萌发及幼苗的影响

采用生物检测的方法研究了扁穗牛鞭草根、茎、叶水浸液对潜在混生种的化感作用。结果表明,扁穗牛鞭草根、茎、叶水浸液对牧草种子萌发的化感作用大体包括延迟和抑制萌发2种方式;不同浓度的化感物质对幼根和幼苗伸长的影响表现为促进、抑制或多种作用并存,0.100%和0.200%浓度的茎、叶水浸液使白三叶幼根扭曲畸变,0.200%浓度根水浸液使紫花苜蓿叶片变小皱缩。经初步试验表明,扁穗牛鞭草较理想的混生种是红三叶。     

Partial pressure of end-tidal CO2 sampled via an intranasal catheter as a substitute for partial pressure of arterial CO2 in dogs

Objective: To demonstrate correlation and clinical usefulness of the partial pressure of end‐tidal CO₂ (ETCO₂) measurement by nasal catheter placement in sedated dogs with and without concurrent nasal oxygen administration as a substitute for partial pressure of arterial CO₂ (PaCO₂). Design: Prospective, cross‐over trial. Setting: University of Saskatchewan veterinary research laboratory. Animals: Six cross‐breed dogs with a mean (±SD) weight of 29.1±4.03 kg. Interventions: All dogs were sedated with 5 μg/kg medetomidine intravenously (IV) and an arterial catheter was placed in a dorsal pedal artery for removal of blood for gas analysis. A nasal catheter was placed in the ventral meatus and connected to a capnometer for ETCO₂ measurements in all dogs. Dogs receiving supplemental nasal oxygen had a second nasal catheter placed in the contralateral naris. Measurements and main results: In the group without nasal oxygen supplementation, the ETCO₂ measurement underestimated (negative bias) the PaCO₂ by ?2.20 mmHg with limits of agreement (95% confidence interval) of ?5.79, 1.39 mmHg. In the group receiving oxygen supplementation, ETCO₂ measurement underestimated (negative bias) the PaCO₂ by ?2.46 mmHg with limits of agreement (95% confidence interval) of ?8.42, 3.50 mmHg. Conclusions: The results of this study demonstrate that ETCO₂ monitoring via a nasal catheter provides a clinically acceptable substitute to arterial blood gas analysis as a means of monitoring ventilation in healthy, sedated dogs. The limits of agreement were within acceptable limits with and without concurrent insufflation of oxygen.     

活性氧(ROS)对小鼠早期胚胎胚细胞分裂的影响

在体外CZB培养的不同时期添加过氧化氢(2.1μmol/L),发育至囊胚阶段,制作胚胎标本,观察其囊胚发育率、胚细胞数和分裂相数。结果显示:0~12 h组和0~72 h组的胚胎发育率显著低于其他几组(P<0.05),对照组、12~24 h组、24~36 h组、36~48 h组之间均差异不显著(P>0.05);各组之间的胚细胞数和分裂指数均无显著差异。说明胚胎在体外培养时,2细胞期胚胎对外源性H2O2最敏感,也最容易发生发育阻滞。但是经H2O2处理之后,度过2细胞期发育阻滞的胚胎能在以后的发育中发生补偿性生长,其胚细胞数和分裂指数都和体外正常发育的胚胎没有差异。     

云南中亚热带禾本科高产饲草引种试验

在云南中亚热带试验点,对8个禾本科饲草栽培种进行引种栽培试验,结果表明:墨西哥类玉米、8493墨西哥类玉米、大力士甜高粱、先锋高丹草和M-8IE甜高粱5个栽培种干物质产量高,适应性强,适宜在相似气候条件地区推广种植。