Propagation of Asian isolates of canine distemper virus (CDV) in hamster cell lines

Backgrounds

The aim of this study was to confirm the propagation of various canine distemper viruses (CDV) in hamster cell lines of HmLu and BHK, since only a little is known about the possibility of propagation of CDV in rodent cells irrespective of their epidemiological importance.

Methods

The growth of CDV in hamster cell lines was monitored by titration using Vero.dogSLAMtag (Vero-DST) cells that had been proven to be susceptible to almost all field isolates of CDV, with the preparations of cell-free and cell-associated virus from the cultures infected with recent Asian isolates of CDV (13 strains) and by observing the development of cytopathic effect (CPE) in infected cultures of hamster cell lines.

Results

Eleven of 13 strains grew in HmLu cells, and 12 of 13 strains grew in BHK cells with apparent CPE of cell fusion in the late stage of infection. Two strains and a strain of Asia 1 group could not grow in HmLu cells and BHK cells, respectively.

Conclusion

The present study demonstrates at the first time that hamster cell lines can propagate the majority of Asian field isolates of CDV. The usage of two hamster cell lines suggested to be useful to characterize the field isolates biologically.     

Simulation study to assess the efficiency of a test-and-cull scheme to control the spread of the bovine viral-diarrhoea virus in a dairy herd

To control the spread of bovine viral-diarrhoea virus (BVDV), test-and-cull schemes have been used in Scandinavian countries, with success, when combined with strict control of new animal introductions into herds. In situations where BVDV reintroduction is likely to occur, it is necessary to assess precisely the expected efficiency of test-and-cull schemes. The objective of this study was to compare, by simulation, the persistence and consequences of BVDV infection in a fully susceptible dairy herd with either a test-and-cull scheme or no control action. We used a stochastic individual-based model representing the herd structure as groups of animals, herd dynamics, the contact structure within the herd and virus transmission. After an initial introduction of the virus into a fully susceptible herd, the frequency of purchases of animals that introduced the virus was simulated as high, intermediate or null. Virus persistence and epidemic size (total number of animals infected) were simulated over 10 years. The test-and-cull reduced the epidemic size and the number of days the virus was present except in herds with complete prevention of contact between groups of animals. Where no virus was reintroduced, virus persistence did not exceed 6 years with a test-and-cull scheme, whereas the virus was still present 10 years after the virus introduction in some replications with no control action (<2%). Where frequent purchases were made that led to virus introduction (6 within 10 years), with an intermediate virus transmission between groups, the probability of virus persistence 10 years after the first virus introduction fell from 31% to 8% with the test-and-cull scheme (compared to the do-nothing strategy). Within the newly infected herd, the test-and-cull scheme had no effect, on inspection, on the number of PI births, embryonic deaths or abortions over 10 years. Given this, the economic efficiency of the test-and-cull scheme should be further investigated.     

Water Deficit Reduced Fertility of Young Microspores Resulting in a Decline of Viable Mature Pollen and Grain Set in Rice

Pollen formation in rice ( Oryza sativa L.) is highly vulnerable to environmental stresses such as heat, chilling and drought. In rice plants exposed to drought during male reproductive development, the most obvious damage often observed is a decline in the number of engorged pollen and grain set. This has been well characterized in rice under chilling and to a lesser extent under drought stress. Moreover, detailed literature on the immediate effects of drought on developing young microspores in rice is still limited. Here, we report findings from experiments on rice plants exposed to water deficit for three consecutive days during early stages of anther development. When the osmotic potential of the growing medium was equal to or less than −0.5 MPa, as induced by polyethylene glycol, the leaf water potential was significantly lowered and grain set was reduced. A strong correlation between grain set and viable young microspores (P < 0.001, r² = 0.8223) indicates that water deficit immediately reduced fertility of rice plants at the time of exposure. This result suggests a new underlying mechanism of water deficit-induced pollen abortion in rice.     

Cellulose content as a selection trait in breeding for kraft pulp yield in Eucalyptus urophylla

? The aim of this study was to investigate the effectiveness of using cellulose content, measured by the diglyme-HCl method, as a selection trait in breeding programs for kraft pulp yield in Eucalyptus urophylla.

? A total of 275 trees from sixty-two families were sampled from a thinned progeny trial of E. urophylla in northern Vietnam to evaluate cellulose content from breast-height increment cores. Among those, twenty unrelated trees were felled to evaluate cellulose content and pulp yield from breast-height disk samples.

? The regression of pulp yield of disk samples on cellulose content was strong either from disks (R ² = 0.83) or increment cores (R ² = 0.69). There was no significant difference in cellulose content between the provenances. The narrow-sense within-provenance heritability of cellulose content was 0.50 and the coefficient of additive genetic variation was 3.9%. Genetic correlations between cellulose content and growth (0.28–0.45) or wood basic density (?0.02) were not significantly different from zero.

? Breast-height increment core cellulose content measured by diglyme-HCl method is under strong genetic control and can be used to rank trees for pulp yield in E. urophylla plantations. Selection for increased cellulose content would have only minor effects on growth and wood basic density.

     

吡喹酮对鲤鱼感染台湾棘带吸虫后期囊幼虫的防治效果

[目的]探讨3种不同药物处理方式对台湾棘带吸虫引起的鲤鱼幼鱼急性鱼鳃传染病(开放性鳃病)的防治效果.[方法]在试验初期,将1620条鲤鱼幼鱼(70日龄)鱼鳃自然感染台湾棘带吸虫,随后分成4组,分别采用CuSO4、福尔马林和吡喹酮不同方式处理6周,与对照(自然喂食、不使用任何化学药剂)比较防治鲤鱼幼鱼急性鳃传染病的效果.[结果]感染台湾棘带吸虫的幼鱼生长缓慢,其身长和体重增长均较慢.施药后,幼鱼台湾棘带吸虫后期囊幼虫感染强度减少.在每千克饲料中分别添加50和75 mg吡喹酮喂食幼鱼5d,可以杀死鱼鳃中所有的台湾棘带吸虫后期囊幼虫,且鱼鳃恢复正常;面使用25 mg吡喹酮,仅有35%的后期囊幼虫死亡.所有不同浓度CuSO4处理(0.3、0.4和0.5mg/kg冲洗浸泡24 h及以3.0、4.0和5.0 mg/kg冲洗浸泡10m)和福尔马林处理(20、25和30 mg/kg冲洗浸泡及200、250和300 mg/kg短时间冲洗浸泡)均不能杀死台湾棘带吸虫后期囊幼虫.[结论]经普通化学药剂CuSO4或福尔马林冲洗浸泡,不能防治由台湾棘带吸虫后期囊幼虫引起的鲤鱼开放性鳃病,但50~75 mg吡喹酮/kg饲料可以在5d内治疗该病.     

越南南定省交水县交善乡对海平面上升的家庭和社区应对经验和对策

【目的】通过收集社会经济学数据,评估居民和社区对海平面上升的适应能力,评估海平面上升的负面影响及其对策,确定应对海平面上升备用对策。【方法】在越南南定省交水县交善乡选择99户居民,分成3组,采用半问卷调查、面谈、家庭群组讨论、重要人物访谈以及当地居民非正式会谈等方法进行调查。【结果】海平面上升已对当地社区造成了极大的负面影响,如作物产量降低、土地流失、盐碱地面积增加、基础设施损坏等。当地社区和居民已经意识到海平面上升的负面影响,并采取了各种应对方法。改变经济结构、选择适宜的作物品种、把水产养殖地转给家庭、鼓励渔民成立渔业合作社并建立早期预警系统是应对海平面上升的主要对策。【结论】应根据潮汐节律和台风、暴风雨发生等所确定的水面上升规律,采取不同的应对策略和方法,以减少海平面上升造成的破坏和损失。     

Evaluation of the microbiological safety and quality of Vietnamese <Emphasis Type="Italic">Pangasius hypophthalmus</Emphasis> during processing by a microbial assessment scheme in combination with a self-assessment questionnaire

Pangasius hypophthalmus (referred to as Pangasius or tra fish in Vietnam) has become highly appreciated by consumers in the European Union, USA, Japan, etc. and is of worldwide economic importance. Therefore, the microbial quality and safety of Pangasius fish processed for export was assessed by means of a microbial assessment scheme throughout the entire production process. A total of 144 samples were collected from various processing steps and analyzed. It was determined that the microbial safety and quality of the products was not guaranteed as the contamination levels remained high throughout processing. Escherichia coli, Staphylococcus aureus and Vibrio cholerae were present on the hands of food operators, particularly those in the packaging area. Moreover, the presence of Listeria monocytogenes (1 positive out of 9 samples) and V. cholerae (4/9) on the final products was likely a result of inadequate hygiene practices in the processing environment. Also discussed in this paper are the results of a self-assessment questionnaire, which provide insight into the performance of the food safety management system currently implemented at the company. These data are of major importance in order to contribute valuable information to the local and international trade point of view in general and to the intended customers in particular.     

Shrinkage and swelling behavior of archaeological waterlogged wood preserved with slightly crosslinked sodium polyacrylate

In this article, the conservation of archaeological waterlogged wood (WW) of Afzelia sp. (medium degraded: U_max = 385%) was impregnated in vacuum with an aqueous solution of acrylic acid (AA), sodium acrylate monomer (AANa), crosslinking agent (MBA) and catalyst (V-501). The simultaneous in situ polymerization and crosslinking resulted in slightly crosslinked sodium polyacrylate (PAANa) in the wood structure. The results showed that untreated WW had only a very limited ability to re-swell to recover its original dimensions from a collapsed condition, while WW protected by crosslinked PAANa could almost fully recover its original shape and size even after several drying–rewetting cycles. From microscopic observations, treated wood was found to maintain its original cell structure, form and shape even after repeated drying–rewetting cycles. PAANa was observed to be densely localized near the middle lamella, the cell corners, and the cell lumina by transmission electron microscopy observation. These observations suggest that our PAANa treatment provides reasonable strength as well as favorable hydrophilicity to avoid hornification of the cell wall upon drying, thus providing unique shape recovery properties.     

Effects of polyethylene glycol and a synthetic ice blocker during vitrification of immature porcine oocytes on survival and subsequent embryo development

We evaluated the effects of polyethylene glycol (PEG) and Supercool X‐1000 (SC) as supplements during the vitrification of immature cumulus‐enclosed porcine oocytes in a solution based on 17.5% ethylene glycol + 17.5% propylene glycol. After warming, the oocytes were subjected to in vitro maturation, fertilization and embryo culture. In Experiment 1, equilibration and vitrification solutions were supplemented with or without 2% (w/v) PEG (PEG+ and PEG‐, respectively). The survival rate, cleavage and blastocyst development were similar between PEG+ and PEG‐ groups; however, all values were lower than those in the non‐vitrified control. In Experiment 2, vitrification solution was supplemented with or without 1% (v/v) SC (SC+ and SC‐, respectively). The percentages of survival and blastocyst development were similar between SC+ and SC‐ groups but lower than those in the non‐vitrified control. The percentage of cleavage in the SC‐ group was significantly lower than the control and the SC+ groups, which were in turn similar to one another. In both experiments, the cell numbers in blastocysts were not significantly different among the non‐vitrified and vitrified groups. In conclusion, PEG did not improve oocyte survival and embryo development, whereas SC improved the ability of surviving oocytes to cleave but not to develop into blastocysts.