橡胶大丰95花药苗幼态无性系的优良性状初报

通过对广东国营奋勇华侨农场橡胶试种区的大丰95花药苗芽接幼态无性系和大丰95老态无性系的生长量、胶乳产量、干胶含量、抗寒性等性状进行比较,大丰95幼态无性系比大丰95老态无性系径围生长快23.9%、胶乳产量增加66.3%、寒害较轻。     

幼羔超早期繁殖技术研究

幼羔超早期繁殖技术是集幼羔超排、活体采卵、体外受精、胚胎移植等技术为一体的胚胎生物技术体系。诱导羔羊卵泡发育技术（简称“幼羔超排”）是根据性成熟前幼龄母羔（1～2月龄）卵巢对生殖激素敏感,卵泡发育很少发生闭锁的特殊生理特点而发明的一项高效率生产羊卵母细胞的新技术。本文从幼羔超早期利用的意义,幼羔超排、幼羔卵母细胞体外受精和胚胎移植等方面综述了目前幼羔超早期利用技术的现状及发展前景。     

饲料中不同磷水平对红螯螯虾幼虾生长和体组成的影响

以秘鲁鱼粉、豆粕为蛋白源,鱼油和豆油为脂肪源,通过调节饲料中不同磷酸二氢钙水平形成7种不同磷水平(0.72%、0.85%、1.00%、1.16%、1.32%、1.47%和1.74%)的等氮等能饲料,并以此饲料投喂红螯螯虾幼虾(2.25±0.12)g8周。试验结果显示:饲料中不同磷水平对红螯螯虾幼虾的增重率、特定生长率、饲料系数和成活率都有一定的影响,增重率和特定生长率均随着磷水平的升高而升高,当总磷含量为1.34%时获得最佳特定生长率,而过高(1.74%)或过低(0.72%)的磷水平会显著影响幼虾的生长;饲料系数随磷水平的升高呈下降趋势;在1.00%～1.74%的磷水平之间成活率均为100%;随着磷水平的升高,全虾和肝胰脏粗脂肪含量逐渐降低,全虾粗灰分和总磷含量均逐渐升高,并且肌肉粗蛋白含量也呈一定的增长趋势;适宜的磷水平可以提高血浆碱性磷酸酶活性,而肝胰脏碱性磷酸酶活性随磷水平的升高而降低。综合幼虾的生长性能、营养成分等分析得出,体重在(2.25±0.12)g的红螯螯虾幼虾适宜的饲料总磷含量在1.32%～1.47%之间。     

Canine paediatric oncology: retrospective assessment of 9522 tumours in dogs up to 12 months (1993-2008)

Little information is available on the occurrence of neoplasms in dogs up to the age of 12 months. This is a retrospective review of histopathological diagnoses of neoplasia in dogs up to the age of 12 months based on biopsy specimens submitted to a commercial veterinary diagnostic laboratory in the United Kingdom between 1993 and 2008. In 20 280 histological submissions, 9522 neoplasms were identified. Canine cutaneous histiocytoma (n = 8465; 89%) was the most common histological type. Neoplasms other than histiocytoma (n = 1057; 11%) were grouped as benign epithelial (n = 375; 4%), haematopoietic (n = 229; 2%), benign mesenchymal (n = 145; 2%), miscellaneous (n = 118; 1%), non-hematopoietic malignant mesenchymal (n = 118; 1%) or malignant epithelial tumours (n = 72; <1%). Excluding canine cutaneous histiocytoma, 52% of tumours (n = 547) were benign, and 66% were from the skin or soft tissues. These data provide valuable epidemiological information on neoplasms occurring in juvenile dogs in the United Kingdom.     

中华鳖对日本沼虾幼虾捕食作用的实验研究

以平均体重为(416.67±14.21)g的中华鳖(Trionyx sinensis)为捕食者,平均全长为(18.40±0.04)mm(A)、(27.77±0.07)mm(B)和(38.90±0.07)mm(C)三种规格的日本沼虾(Macrobrachium nipponensis)幼虾为猎物,采用种间捕食作用研究方法,开展了中华鳖对日本沼虾的捕食选择性和功能反应的研究,以期为进一步优化虾鳖混养模式参数和提高日本沼虾养殖效益提供理论依据。结果表明:(1)中华鳖的捕食活动时段为18:00~6:00,主要集中于0:00~4:00,该时间段中华鳖对日本沼虾幼虾的捕食量占总捕食量的80%;(2)当日本沼虾幼虾密度为30尾/m~2时,中华鳖表现出对B规格的日本沼虾幼虾更具捕食选择倾向,当密度为60尾/m2和90尾/m2时,中华鳖则表现出对A规格的日本沼虾幼虾更具捕食选择倾向;(3)中华鳖对日本沼虾幼虾的捕食功能反应属Holling-Ⅱ型,中华鳖对A、B和C三种规格日本沼虾幼虾理论上最大日捕食量分别为169、75和70尾。     

裸盖鱼幼鱼工厂化养殖试验

采用实验生态学的方法对裸盖鱼(Anoplopoma fimbria)幼鱼进行工厂化养殖试验,以了解和分析其生长特征。在地下海水温度(10.42±0.45)~(13.65±1.22)℃的条件下,经过210 d的养殖试验,裸盖鱼幼鱼由初始平均体重(33.27±5.82)g增长到(805.20±113.79)g,平均增重量最大值为(193.42±29.23)g/月,平均日增重量(3.68±0.61)g/d,最大日增重量(6.45±0.97)g/d。裸盖鱼幼鱼体长与体重呈幂函数关系,回归方程式为:W=0.017 4 L2.943 6(R2=0.973 1)。水温对裸盖鱼幼鱼的增重、存活率及饵料系数均有影响,结果显示,最适养殖水温为(11.32±0.75)~(12.68±0.92)℃,与1龄以上裸盖鱼的最适水温基本一致,在该水温范围内,裸盖鱼幼鱼生长迅速,饵料系数相对较低,存活率较高。研究表明,裸盖鱼喜低温,生长速度快,养殖效益显著,是极具开发前景的冷水性养殖鱼类。     

Spatial dynamics of juvenile anchovy in the Bay of Biscay

In autumn 2009, the implementation of two successive acoustic surveys targeting juvenile anchovy (Engraulis encrasicolus) in the Bay of Biscay allowed us to monitor the changes in the spatial distribution and aggregation patterns of juveniles of this species during 45 days under fairly stable meteorological conditions. Juvenile anchovy changed its biological condition and behavior in a different manner in two distinct areas. In the Spanish sector, the juveniles migrated 20 nautical miles (n.mi.) towards the coast, but they remained on the shelf and near the surface during the whole surveyed period. As the advance towards the shelf break progressed, their area of distribution decreased, their density increased and the juveniles spread in fewer but heavier shoals. In the French sector, the juveniles also migrated from slope waters towards the coast at a similar velocity, but they crossed the shelf break into the continental shelf, where they increased their mean depth significantly until gradually adopting the typical nyctemeral migrations of adult anchovy. The mean length of the juveniles that adopted the nyctemeral migrations was significantly higher than that of the juveniles remaining at the surface, suggesting that body size is relevant to accomplish this change. Besides, the stronger temperature gradients between the shelf and oceanic waters in the Spanish sector, favored by a narrow shelf, may have acted as a barrier influencing the distinct observed spatial patterns in the two areas.     

Mode of action of methoprene in affecting female reproduction in the African malaria mosquito,Anopheles gambiae

BACKGROUND: One of the most studied actions of juvenile hormone (JH) is its ability to modulate ecdysteroid signaling during insect development and metamorphosis. Previous studies in mosquitoes showed that 20‐hydroxyecdysone (20E) regulates vitellogenin synthesis. However, the action of JH and its mimics, e.g. methoprene, on female reproduction of mosquitoes remains unknown. RESULTS: Here, a major malaria vector, Anopheles gambiae Giles, was used as a model insect to study the action of methoprene on female reproduction. Ecdysteroid titers and expression profiles of ecdysone‐regulated genes were determined before and after a blood meal. An ecdysteroid peak was detected at 12 h post blood meal (PBM). The maximum expression of ecdysone‐regulated genes, such as ecdysone receptor (EcR), hormone receptor 3 (HR3) and vitellogenin (Vg) gene, coincided with the ecdysteroid peak. Interestingly, topical application of methoprene at 6 h PBM delayed ovarian development and egg maturation by suppressing the expression of ecdysone‐regulated genes in female mosquitoes. CONCLUSION: The data suggest that ecdysteroid titers are correlated with Vg synthesis, and methoprene affects vitellogenesis by modulating ecdysteroid action in A. gambiae. Copyright © 2010 Society of Chemical Industry     

Retinomotor responses of juvenile bluefin tuna Thunnus thynnus

SUMMARY: In bluefin tuna culture, a high mortality of juveniles is caused by bumping into the tank and net-pen walls at dawn. This bumping can possibly be attributed to visually disoriented behavior of the fish. To examine this possibility, the authors carried out retinomotor response experiments with juvenile bluefin tuna (50.7–96.8 mm total length, at which they were transferred from a indoor tank to a sea net-pen) and measured ambient light intensity at the culture site at dawn. The light intensity at which the transition from scotopic to photopic vision takes place was 7.52 lx and the time taken by the transition was 15 min. At dawn, the ambient light intensity rapidly increased from scotopic light intensity level and attained photopic light intensity level in 10 min. This incompatibility of the retinal adaptation with the change in the ambient light intensity could cause the visual disorientation of the fish. It is therefore possible that the visually disoriented juveniles cannot control their high power swimming and thus bump into the walls at dawn.     

New data on the ecology of kutum, Rutilus frisii (Nordmann, 1840) from the Caspian Sea

Abstract– In the anadromous cyprinid kutum, Rutilus frisii (Nordmann, 1840) from the Anzali Lagoon, Iran, the following hitherto unrecorded characters were found. The complex life-style of juvenile kutum is reflected directly in their body size and preferred habitat, and indirectly in their growth rate and the formation of scale annuli. The early juveniles did not move downstream to the feeding grounds in the sea as they are supposed to do in populations inhabiting the Caucasian coast of the Caspian sea, but most of them spend one or two years in fresh or brackish water. Moreover, most kutum scales carried one or two juvenile marks. It appears that the time spent in fresh water is inversely proportional to the age of the kutum. On average about 43% of fish 2 years old and older, spent their first year in fresh or brackish water, while 57% spent two years there. The rate of growth in length is substantially different in both groups. Fish that enter the sea in their second year of life grew faster but their life span seems to be shorter than those which spent two years in fresh or brackish water.