Recent expansion of Northeast Atlantic and Mediterranean populations of <Emphasis Type="Italic">Melicertus</Emphasis> (<Emphasis Type="Italic">Penaeus</Emphasis>) <Emphasis Type="Italic">kerathurus</Emphasis> (Crustacea: Decapoda)

We analysed the genetic diversity of Melicertus kerathurus (Penaeidae), a commercially valuable penaeid shrimp that is distributed in the Mediterranean Sea and eastern Atlantic Ocean. We examined the polymorphism of a 494 bp DNA segment of the mitochondrial COI region in 173 individuals, sampled in nine Mediterranean and two Atlantic samples, covering the whole range of the species from the tropical waters of the Gulf of Guinea to the eastern part of the Mediterranean Sea. The mean nucleotide and haplotype diversities were π = 0.00275 and h = 0.718, respectively, for the global data set, with the highest values occurring in the African samples and the lowest in the Adriatic Sea. A clear sample differentiation was found (F _st = 0.194), but this did not reflect a geographical pattern and there were only faint traces of an Atlantic–Mediterranean subdivision. Mismatch analysis and a high significant negative value of Tajima’s D suggested that M. kerathurus is not at mutation drift-equilibrium, but underwent a recent expansion after a period of low effective sample size. A postglacial recolonisation of the Mediterranean from an Atlantic refuge could be hypothesised based on these data.     

阻止病原体的传入

防止病原体入侵是搞好生物安全、保持猪群健康的核心任务。养猪生产中的生物安全包括了一系列能够防止猪群污染和减少疾病传播的措施。每个猪场经理都需要认真考虑病原体在猪场之间传播的最重要途径     

东喜马拉雅地区高山栎类 (Quercus Sec.suber)种群变异和环境异质性研究(英文)

该文研究分布在我国东喜马拉雅地区 (云南和西藏 )及四川的高山栎类种群间的形态变异和遗传距离 .在自然条件下 ,这些栎类的生长形态随纬度的增加和降水的减少从高大的乔木变成矮小的灌木 .该地区多样的气候和复杂的地形条件为高山栎类提供了各种形态、生长和遗传变异的可能性 .种群内和种群间的遗传距离随生境条件、山地地形和主风方向的变化明显 ,但与水平距离关系不大 .西藏地区以地势险峻和气候多变为特色 ,云南地区以高山峡谷为特色 ,二地区高山栎的种群遗传距离分别为 0 396和 0 36 5,前者显著高于后者 (P <5% ) ,但却都高于四川地区的高山栎种群遗传距离 ,并达到极显著水平 (P <1% ) .环境的异质性越高 ,高山栎类的变异越大 ,种群变异和物种进化与气候、生境、地形地貌和土壤等环境的异质性密切相关 .尽管东喜马拉雅地区是以大陆性季风为主气候特征 ,但高山栎类的叶片、直径和根系对环境异质性的适应变异与分布在地中海地区的、冬雨夏旱气候条件下的冬青栎类 (Q .ilex)十分相似 .不同地区的环境异质性必然导致物种进化和种群变异的差异 ,然而 ,高山栎类种群在两个截然不同气候区内的高度相似性恰恰说明了它们可能来自于一个共同的祖先或从同一个地区演化而来 ,所以它们才有相同的适应策略     

Rainbow trout silage as immune stimulant and feed ingredient in diets for Mozambique tilapia (Oreochromis mossambicus)

Peptides and free amino acids resulting from protein hydrolysis could act as stimulants of fish non‐specific immunity. The study aimed to determine the potential of rainbow trout viscera silage as immune stimulant and feed ingredient for Mozambique tilapia, and to establish whether formic acid used during silage preparation contributed to any effects. Four diets were evaluated: a reference diet (R), one containing 6.5 g kg^?1 formic acid (FA) and two silage diets containing 160 g kg^?1 (SL, low inclusion) and 285 g kg^?1 (SH, high inclusion) silage. Low silage inclusion improved phagocytic activity of leucocytes compared with the reference, while high inclusion showed no improvement. No other non‐specific immunity parameters or haematology were affected by any treatments. High silage inclusion significantly decreased growth and led to higher mortality, while formic acid had no effect on growth. It is concluded that rainbow trout viscera silage can stimulate the cellular non‐specific immunity of Oreochromis mossambicus, and that protein hydrolysis products (and not formic acid) is responsible for the stimulation. The silage can also serve as source of dietary protein and essential amino acids in tilapia diets. However, both fish growth performance and improvement in cellular immunity are dependent on silage inclusion level.     

Effects of formic acid in abalone diets that contain ingredients derived from fish processing by-products

The study aimed to investigate the effects of formic acid inclusion in abalone diets, which contained ingredients produced from fish processing by-products, and to quantify effects on production performance. Four diets (a commercial reference and iso-nutrient diets containing fish silage oil, unprocessed rainbow trout viscera or shrimp protein hydrolysate) were evaluated both with and without addition of 2 g kg^?1 dietary formic acid, thus yielding a total of eight treatments, in feeding trials with cultured South African abalone Haliotis midae. Results indicated that inclusion of unprocessed rainbow trout viscera without formic acid decreased production performance of experimental animals, as evidenced by significantly decreased final animal weight and daily weight gain, and significantly increased feed conversion ratio compared to the iso-nutrient control. The decreased production performance was attributed to decreased feed water stability of the diet incorporating untreated trout viscera. Dietary formic acid supplementation partially mitigated the negative impacts of viscera inclusion on production performance of the experimental animals, as seen in significantly higher final animal weight and daily weight gain, and lower feed conversion ratio when compared to non-formic acid-supplemented, viscera-containing diet. However, no beneficial effects on production performance or water stability were found upon formic acid inclusion in diets not containing trout viscera. In conclusion, dietary formic acid can partially mitigate negative impacts on production performance when unprocessed trout viscera are included in formulated abalone diets by improving feed water stability, but the exact mechanism by which this is achieved was not established.     

Estimates of genetic parameters and genetic gains for growth traits of two Eucalyptus urophylla populations in Zululand,South Africa

In South Africa, Eucalyptus urophylla is an important species due to its disease tolerance to fungal diseases such as Crysoporthe austroafricana and the Coniothyrium sp. cankers. It is mainly planted as a parental species in a hybrid combination with E. grandis. Generally, the E. grandis × E. urophylla hybrid has better disease tolerance and higher wood density than pure E. grandis. The current strategy is to maintain large breeding populations of both parental species in order to provide improved elite selections for hybrid crosses on a regular basis. With this in mind, two E. urophylla populations, consisting of five provenance/progeny trials, were established in the subtropical region of Zululand. The aims of this study were, firstly, to determine the magnitude of genotype × environment interaction of E. urophylla in Zululand; secondly, to estimate genetic parameters and correlations for diameter at breast height (DBH), height and volume; and thirdly, to identify selections to advance the current breeding population as well as to hybridise with E. grandis. Results indicated that genotype × environment interaction effects would be practically negligible for growth in Zululand and therefore a single breeding population will be appropriate. In general, all growth traits were under low to moderate genetic control, with narrow-sense heritabilities ranging between 0.14 and 0.48 for volume. The genetic correlations between growth traits were high (0.98 and 0.99 for DBH– volume). This is an indication that DBH is a sufficient growth measure to use in E. urophylla breeding programmes. Best linear unbiased prediction estimates indicated that aa selection scenario of 200 individuals will generate genetic gains of 44.7% over the population mean. The estimated gains for the top 50 individuals that could potentially be used as hybrid parents to cross with E. grandis was 59.8% over the population mean.     

Temporal spore dispersal patterns of grapevine trunk pathogens in South Africa

Trunk disease pathogens of grapevines, viz. Phaeomoniella chlamydospora, Eutypa lata and several species in Botryosphaeriaceae, Phaeoacremonium and Phomopsis are known to infect fresh pruning wounds by means of air-borne inoculum released after rainfall or prolonged periods of high relative humidity. Recent surveys have demonstrated that most or all of these pathogens are present in climatically diverse grape growing regions of South Africa. However, the factors controlling spore dispersal of these pathogens in vineyards were largely unknown. To address this question, spore trapping was done in a Chenin Blanc vineyard in the Stellenbosch area, South Africa, for 14 weeks during the grapevine pruning period from June to mid-September of 2004 and 2005. Hourly recordings of weather data were done by a weather station in the row adjacent to the spore trap. Spores of E. lata and Phomopsis and species in Botryosphaeriaceae were trapped throughout the trapping periods of 2004 and 2005, with higher levels of trapped spores recorded in 2005. The spores of all three pathogens were trapped during or after periods of rainfall and/or high relative humidity. In neither of the 2 years were spores of Pa. chlamydospora or Phaeoacremonium spp. trapped. Results indicated that spore event incidence, as well as the amount of spores released during a spore event of above-mentioned pathogens, were governed by rainfall, relative humidity, temperature and wind speed prior to and during the spore events.     

Realised genetic gains and estimated genetic parameters of two Eucalyptus grandis × E. urophylla hybrid breeding strategies

Conventionally, Eucalyptus grandis × E. urophylla (GU) hybrid material is first tested as seedlings in progeny trials for at least four years before ortets are selected and ramets of the selected ortets are propagated to test in clonal trials. The primary constraint with this ‘conventional hybrid breeding strategy’ (CHBS) is the time required to first test the hybrid material as seedlings. In order to address this, an ‘accelerated hybrid breeding strategy’ (AHBS) was investigated to reduce the time spent on testing GU hybrid material as seedlings. However, it is of utmost importance to quantify the impact the AHBS might have on genetic gains and genetic information. With this in mind, two clonal populations have been established with genetic material that derived from the CHBS and the AHBS. The main purpose of this study was to do a comparative study between the CHBS and AHBS, firstly to quantify the genetic gains per unit time for GU hybrid clonal populations that have been derived from the CHBS and AHBS respectively, and secondly to obtain genetic parameters such as heritabilities, the ratio of dominance, clonal within family variance, and the proportion of additive and non-additive genetic variance. The results indicated that the percentage realised volume gains per year was higher for the AHBS (3.7%) than for the CHBS (1.9%) when compared with the GU commercial clone. Thus, shortening the testing time of GU seedlings had a positive impact on volume gains per year. With regard to genetic parameters, both the AHBS and CHBS clonal populations indicated that non-additive genetic variation explained the majority (88% and 71%, respectively) of the genetic variation. Due to the pre-eminence of non-additive genetic variation, the narrow-sense heritabilties for the female and male effects were negligible for both clonal populations. Overall, the majority of the non-additive genetic variation was explained by the proportion of dominance variance, and less by the clone within family effect. These results suggest that, firstly, the time spent on testing GU hybrid material as seedlings should be minimised and, secondly, a hybrid breeding strategy to capture non-additive genetic variation should be adopted.     

Accuracy of computed tomographic arthrography for assessment of articular cartilage defects in the ovine stifle

Articular cartilage defects are one of the features of osteoarthritis in animals and humans. Early detection of cartilage defects is a challenge in clinical veterinary practice and also in translational research studies. An accurate, diagnostic imaging method would be desirable for detecting and following up lesions in specific anatomical regions of the articular surface. The current prospective experimental study aimed to describe the accuracy of computed tomographic arthrography (CTA) for detecting cartilage defects in a common animal model used for osteoarthritis research, the ovine stifle (knee, femoropatellar/femorotibial) joint. Joints in cadaver limbs (n = 42) and in living animals under anesthesia (n = 13) were injected with a contrast medium and imaged using a standardized CT protocol. Gross anatomy and histological assessment of specific anatomic regions were used as a gold standard for the evaluation of sensitivity, specificity, negative predictive value, and positive predictive value for CTA identification of articular cartilage defects in those regions. Pooled estimated sensitivity and specificity were 90.32% and 97.30%, respectively, in cadaver limbs, and 81.82% and 95.24%, respectively, in living animals. Pooled estimated positive predictive value and negative predictive values were 98.25% and 85.71%, respectively, in cadaver limbs, and 81.82% and 95.24%, respectively, in living animals. The delineation of cartilage surface was good for anatomical regions most frequently affected by cartilage defects in the ovine stifle: medial femoral condyle, medial tibial condyle, and patella. This study supported the use of CTA as an imaging technique for detecting and monitoring articular cartilage defects in the ovine stifle joint.