网箱养殖条件下黄鳝初次性成熟的年龄

对网箱养殖条件下黄鳝性腺指数进行测定并观察性腺组织切片,结果发现:网箱养殖条件下黄鳝在1周年内可以达到雌性性成熟,即网箱养殖条件下雌性黄鳝初次性成熟年龄为1龄;网箱养殖条件下1周年内黄鳝的性腺指数大致呈增长趋势,在6月,性腺发育成熟时,性腺指数达最大值,其值为14.33±2.07;网箱养殖黄鳝在1周年内血清雌二醇质量浓度在6月达到最大值,即(1 233.52±126.07)pg/mL,血清睾酮质量浓度在5月已经达到最大值,即(13.99±1.54)pg/mL。     

Digestible energy content of pasture species in growing European wild boar (Sus scrofa L.)

The objectives were to determine the apparent energy digestibility of six pasture species frequently grazed by European wild boar (Sus scrofa L.) and to estimate the digestible energy (DE) consumption from pasture by grazing wild boar. Seven diets were prepared; a base diet (BD) which did not contain any pasture species, diets D1 to D5 which included 75% of the BD and 25% of the dried pasture species Lolium perenne (D1), Festuca arundinacea (D2), Agrostis capillaris (D3), Bromus staminius (D4) or Trifolium repens (D5) and D6 which contained 85% BD and 15% dried Plantago lanceolata. Seven purebred European wild boar (initial liveweight 24.4 ± 0.8 kg, average ± SEM) were given access to the diets following a Latin Square design. The animals received each diet for eight days, with faecal sampling on days 6, 7 and 8. The total apparent DE consumption from pasture by grazing wild boar was estimated using previously collected pasture consumption data from wild boar. The digestibility coefficients and DE contents of the pasture species ranged from 0.29 to 0.65, and 5.8 to 12.6 MJ/kg DM respectively, with L. perenne and P. lanceolata having the greatest digestibility coefficients and DE contents. The wild boar were estimated to satisfy between 52% and 142% of their maintenance energy requirements through pasture consumption. Grazing wild boar are able to utilise an important proportion of the energy present in pasture species.     

欧盟尽职调查法案对我国木质家具贸易的影响及对策分析

近年来,非法采伐及相关木材贸易问题引起了国际社会的广泛关注.木质家具是中国木质林产品出口中最重要的产品,同时出口欧洲的份额正呈现出不断增长的趋势,尽职调查法案的实施必将对我国木质家具贸易产生重大影响.笔者简述了欧盟尽职调查法案的出台背景、历史沿革和主要内容,分析了我国与欧洲联盟的木质家具贸易现状,探讨了尽职调查法案实施后对我国木质家具贸易的消极影响和积极影响,从政府和企业两个层面提出相应政策,在应对当前困境的同时以促进我国木质家具贸易的可持续发展.     

Effects of a 10-year conservation programme on the genetic diversity of the Pottoka pony--new clues regarding their origin

Here, we present the results of a genetic analysis of 463 Pottoka ponies corresponding to four generations, using 17 microsatellite markers. Ten years after the beginning of the Pottoka conservation programme, the values for the genetic diversity of the breed are still high and stable, indicating the success of the programme. We found null alleles in Pottoka for the ASB23, HMS3 and HTG10 microsatellites. Together with information obtained from other pony breeds from the Iberian Peninsula, this finding indicates that these microsatellites should not be used for phylogenetic analyses or parentage tests, at least for these breeds. The high heterozygosity exhibited by this breed in comparison to other ponies, together with its genetic proximity to the centroid of the allele frequencies, suggest that Pottoka allele frequencies are close to those initially exhibited by the ancestors of current European ponies. The results obtained in the current work, together with results from previous studies of ponies and horses from the Iberian Peninsula, corroborate the idea of a unique origin of all ponies from the European Atlantic Area. In contrast, our results do not corroborate the idea that these are derived from a domestication event in the Iberian Peninsula, nor that they have incorporated ancient Iberian horse genes into their genetic pool to a larger extent than other horse breeds.     

Interacting effects of irradiance and water stress on dry weight and biomass partitioning in Fagus sylvatica seedlings

Abstract

Actual climate models for central Europe predict prolonged summer droughts. Knowledge on how the interaction between light and water availability affects regeneration will hence be of major importance. In an experiment carried out under controlled conditions, newly emerged beech seedlings were grown in pots with sand during 54 days. Three treatments applying three different light levels (2, 9 and 43% relative light intensity) were combined with two soil water treatments (control and drought). At the end of the experiment, seedlings were separated into leaves, stem and root and the seedlings’ dry mass, leaf area and stem length was determined. Low irradiance (2%) had a strong negative effect on dry weights of seedling components, leaf area and specific leaf mass. Drought clearly affected biomass partitioning for seedlings at high irradiance levels (43%). An interaction between irradiance and drought on biomass partitioning in beech seedlings was observed at medium irradiance level (9%). Within a wide range of light levels in the forests, both light and drought may affect biomass partitioning in young seedlings.     

A statistics-based method for cluster analysis of the forest sector at the national and subnational level in Germany

Abstract

The cluster concept in economics contributes to new research on the forest sector's role in national and regional economies, yet incompatible cluster definitions and a variety of methodologies impede an objective comparison of findings. However, governmental statistical reporting systems are not well suited for a direct assessment of the forest sector due to classificatory and methodological shortcomings. This research presents a more standardized approach in the form of a statistics-based method for forest sector benchmarking and monitoring. The specification of the method included an extended cluster definition based on the Classification of Economic Activities in the European Union (NACE) and the validation of two suitable national statistical reporting systems. Testing the method in a case study for Germany demonstrates its capacity to provide consistent socioeconomic information on forest and wood-based industries in a sectoral, spatial and temporal dimension. In 2004, the German forest cluster accounted for 100,000 companies, 150 billion Euro gross turnover and over 900,000 employees (approximately 3.5% of the national economy) and ranked among the strongest manufacturing sectors. Individual wood-based industries indicated regional concentrations in federal states of Germany. Over the past decade, the forest sector was marked by considerable losses in turnover and employment, which increasingly deviated from the overall economic development of Germany. The research contributes to a more standardized, empirical understanding of the forest sector's role in national and regional economies, supporting rational decision making in cluster policy and management.     

Distribution of red-spotted grouper nervous necrosis virus (RGNNV) antigens in nervous and non-nervous organs of European seabass (Dicentrarchus labrax) during the course of an experimental challenge

The distribution of red-spotted grouper nervous necrosis virus (RGNNV) antigens was examined by immunohistochemistry in the nervous and non-nervous organs of juvenile European seabass (Dicentrarchus labrax) during the course of an intramuscular infection. Histological changes resulting from the infection were evaluated from 3 days to 2 months post-infection. The specific antibody response was also studied 2 months post-challenge. Viral proteins were present throughout the experimental period in the retina (inner nuclear layer, ganglion layer, outer limiting membrane, and outer plexiform layer), brain (cerebellum and tectum opticum), and liver (hepatocytes and endothelial cells). These proteins were also observed in the renal tubular cells, white pulp of spleen, and in fibroblasts and cartilage of caudal fin. This is the first report of RGNNV proteins appearing in these organs, where the immunostaining was only detected at certain sampling times after the onset of mortality. Brain and retina of virus-exposed fish showed high levels of vacuolation, while accumulation of fat vacuoles was observed in the liver. RGNNV infection also induced a specific antibody response as measured by an ELISA. In summary, this is the first study demonstrating the presence of viral proteins in cells of caudal fin, kidney and spleen of European seabass.     

孟加拉进口黄鳝中致病性嗜水气单胞菌的分离与鉴定

[目的]了解致病性睹水气单胞菌的存在状况和风险水平.[方法]采用分离培养、生化鉴定、序列测定和动物试验等方法,对2批孟加拉进口黄鳝进行致病性睹水气单胞菌检测.[结果]从孟加拉进口黄鳝体内分离出4株高度致病性的嗜水气单胞菌.嗜水气单胞菌对孟加拉黄鳝本身致病性不明显,但是对小鼠的致病性却高达10 000～ 100 000 CFU/ml.[结论]孟加拉进口黄鳝存在致病性睹水气单胞菌的感染,且对我国的食品和卫生安全存在一定的风险.     

Fungal colonization patterns in necrotic rootstocks and stem bases of dieback‐affected Fraxinus excelsior L.

European ash (Fraxinus excelsior) trees currently face the major threat of ash dieback caused by an invasive fungus, Hymenoscyphus fraxineus. Collar rots in F. excelsior have been increasingly associated with infections by this pathogen. However, the aetiology of the collar rots is still unclear and remains heavily debated. In contrast to most studies of this kind, entire rootstocks of four diseased ash trees were dug out to examine necrotic tissues in these rootstocks and stem bases in detail and to sample necrotic wood for fungal isolation. With the aid of morphological and molecular identification techniques, five to twelve fungal taxa were detected per tree. Members of the Nectriaceae family and Botryosphaeria stevensii, the causal agent of stem and branch cankers on many tree species, were frequently isolated from outer xylem. In contrast, H. fraxineus was the dominating species in interior wood layers. Microsatellite genotyping of 77 H. fraxineus isolates helped to identify up to six different genotypes per tree. The role of H. fraxineus and other isolated fungi in the aetiology of ash collar rots are discussed.