中国刺蛾科幼虫的寄主植物多样性分析

刺蛾科Limacodidae是鳞翅目中1个相对较小的科,是果树、园林及经济作物的主要害虫。目前我国已知64属230种,其中89种有幼虫的寄主植物记录。文章列出了这89种刺蛾及其寄主植物,并对其食性多样性及特点进行了分析。结果表明:中国刺蛾科昆虫涉及到的寄主植物共有64科,其中以茶科上的刺蛾种类最多,达47种,占总数的52.8%。     

绘环棱螺肝中粗提物抗菌活性初步研究

越来越多的临床致病菌对传统抗生素产生了耐药性,对人类的生命健康构成了威胁,由此驱使人们开发新的抗菌药抑制这些致病菌。该试验通过Sephadex G-75凝胶层析和超滤离心制备绘环棱螺肝中粗提物,用琼脂糖弥散法初筛抗菌活性物质,研究该淡水螺的体外抗菌活性。结果表明:绘环棱螺肝中分子量在10 kDa的小分子部分的粗提物,对大肠埃希菌、白色念珠菌、绿脓杆菌和金黄色葡萄球菌有不同程度的抑菌活性,呈现一定的广谱抗菌活性。     

PCR仪法从林麝毛发中提取基因组DNA

采用PCR仪法从林麝(Moschus berezovskii)毛发中提取基因组DNA,并与酚/氯仿法进行比较.结果表明,采用PCR仪法提取所得的DNA浓度高、纯度好.以提取所得的DNA为模板扩增林麝雄性激素受体基因外显子1,获得的PCR产物务带清晰、位置正确.PCR仅法与酚/氯仿法相比操作简单,提取所得的DNA质量较高,值得推广.     

链烷技术检测蝗虫食性方法的研究

为验证链烷技术测定蝗虫食性的精确性,确定蝗虫粪便中链烷的回收率。于2007年夏季在内蒙古太仆寺旗天然草地,用优势植物羊草(Leymus chinensis)、糙隐子草(Cleistegenes squarrosa)和克氏针茅(Stipa kylovii)各500g,饲喂360只成虫的亚洲小车蝗(Oedaleus asiaticus)。试验期内每天记录蝗虫实际牧草采食量、采食成分和排粪量,利用气相色谱分析牧草和粪样的链烷含量,应用链烷技术测定蝗虫的牧草采食比例,并与实际值进行比较。结果表明,3种牧草链烷模式存在种间差异;蝗虫粪便中链烷的回收率随链烷长度的增加而线性增加;蝗虫采食羊草、糙隐子草和克氏针茅比例的测定值与实际值存在显著正相关(P<0.05),相关系数分别为0.925 5、0.956 6和0.978 2。因此链烷技术可以精确测定典型草原蝗虫的食物组成。     

Biochemical characterization of Siberian sturgeon Acipenser baeri and sterlet Acipenser ruthenus milt plasma and spermatozoa

This paper provides data concerning biochemical composition of milt of two sturgeon species, Siberian sturgeon bred in aquaculture facility of Inland Fisheries Institute in North Poland and sterlet (from two different populations from Danube and Odra). Milt plasma of Siberian sturgeon and sterlet, when compared to teleost fish, is characterized by much lower osmolality (up 70 to 96 mOsm kg⁻¹) and protein concentration (0.24–0.58 g l⁻¹). In spite of the presence of an acrosome and acrosin the antiproteinase activity of seminal plasma was low (12.79–25.40 U l⁻¹). Activities of arylsulfatase and β-N-acetylglucosaminidase were found in spermatozoa. This agrees with the presence of an acrosome in sturgeons sperm. Similarly to mammals, these enzymes are also present in milt plasma. We determined a range of enzymatic activities from the minimal (seminal plasma) to the maximal damage (supernatants obtained after freezing-thawing without cryoprotectant). Activities of arylsulfatase, β-N-acetylglucosaminidase, lactic dehydrogenase and acid phosphatase were released from spermatozoa after freezing-thawing. For this reason they are good potential candidates as a markers of cryoinjury to sperm acrosome and midpiece. This revised version was published online in July 2006 with corrections to the Cover Date.     

Cloning, tissue distribution and hormonal regulation of stearoyl-CoA desaturase in tilapia, Oreochromis mossambicus

The stearoyl-CoA desaturase cDNA in tilapia (Oreochromis mossambicus) was cloned by RT-PCR and RACE, and it was compared with those in grass carp, common carp and milkfish. Nucleotide sequence analysis revealed that the full length of cDNA (1172 bp) clone encompasses 1008 bp open reading frame (ORF) encoding 336 amino acid residues. The deduced amino acid sequence shares 78–82% identity with the teleosts and 64–66% with mammals compared, and like these fish, the cloned tilapia stearoyl-CoA desaturase amino acid sequence conserves three histidine cluster motifs (one HXXXXH and two HXXHH), which functioned as non-heme iron binding sites, essential for stearoyl-CoA desaturase activity. RT-PCR and Northern blot analysis reveal that tilapia stearoyl-CoA desaturase is expressed only in liver, but the stearoyl-CoA desaturase expression in multiple tissues was observed in milkfish, grass carp and carp. Further, the hormonal regulation of stearoyl-CoA desaturase gene expression was investigated by a single injection of 17β-estradiol and testosterone. The results showed that the administration of 17β-estradiol to tilapia led to a greater increase in desaturase activity than testosterone, and higher doses of steroids produced greater increases in enzyme activity. The comparative RT-PCR analysis showed that the stearoyl-CoA desaturase mRNA level increased significantly in 17β-estradiol treated animals, especially in the groups receiving a single injection of 50 mg 17β-estradiol. This was reflected in the decrease in the saturated fatty acids and the increase in the monounsaturated fatty acids. The proportion of the polyunsaturated fatty acids was not affected.     

Influence of pond fertilization and feeding rate on growth performance, economic returns and water quality in a small-scale cage-cum-pond integrated system for production of Nile tilapia (Oreochromis niloticus L.)

The effects of pond fertilization and feeding rate on growth, economic returns and water quality were investigated to develop a low‐cost cage‐cum‐pond integrated system for production of Oreochromis niloticus (L.). Hand‐sexed male fingerlings averaging 19±0.39 and 32±0.69 g were stocked in cages and open ponds at 150 fish cage^?1 and 2 fish m^?2 respectively. Fish were cultured for 114 days in five triplicate treatments. Cages were installed into ponds and caged fish were fed a 24% protein diet at 3% (T1) and 6% (T2) body weight day^?1 (BWD) without pond fertilization, and 6% BWD with pond fertilization (T3). The open water in the fourth treatment (T4) was not stocked but contained caged fish, which were fed 6% BWD for the first 57 days followed by 3% BWD for the remaining period. Ponds in the control (T5) had no cages and were neither fertilized nor open‐pond fish fed. Feeding rate and pond fertilization significantly (P<0.05) affected fish growth, profitability and water quality among treatments. Fish growth, feed utilization, fish yield, water quality and profits were significantly (P<0.05) better in T3 than the other treatments. It was concluded that fish production and economic returns were optimized at 6% BWD in fertilized ponds.     

Molecular characterization and pathogenicity of a grouper iridovirus (GIV) isolated from yellow grouper, Epinephelus awoara (Temminck & Schlegel)

Molecular characterization was carried out on an iridovirus isolated from yellow grouper, Epinephelus awoara . The major capsid protein (MCP) gene was located, sequenced and compared with homologous genes from other iridoviruses. The nucleotide sequence is 1392 bases long and contains a single open reading frame beginning at an ATG codon from the 5' end and terminating at a TAA codon at the 3' end. The open reading frame encodes a protein of 463 amino acids with a predicted molecular weight of 50 272 Da. Pairwise amino acid alignments detected a high degree of sequence identity between grouper iridovirus (GIV) MCP and the homologous genes of other iridoviruses. The MCP gene of GIV was most similar to the MCP gene from frog virus 3 (FV3) with 70% nucleotide and 73% amino acid sequence identity. The predicted molecular weight of the protein of this gene is comparable with the apparent weight obtained by SDS–PAGE. Pathogenicity of the GIV was investigated in yellow grouper by intraperitoneal injection of 10⁷ and 10⁴ TCID₅₀ virus. Cumulative mortalities reached 100% within 11 and 25 days post-infection, respectively, while no grouper died in the control group. The molecular studies demonstrated that GIV is a member of the genus Ranavirus .     

Heat shock protein 70 expression in different tissues of Cirrhinus mrigala (Ham.) following heat stress

Members of heat shock protein 70 (HSP70) are highly conserved proteins of about 70 kDa and play important roles in protein folding. Levels of these proteins increase when cells are under stress. Environmental temperature influences both the basal and induced levels of HSPs. However, studies on HSPs in fishes from a tropical country such as India are lacking. In the present study, Indian major carp (IMC) Cirrhinus mrigala (Ham.) acclimatized at 25±2°C had high levels of HSP70, viz., 1.2–1.3 ng μg^?1 total protein in kidney and gill and 4.2–5.3 ng μg^?1 total protein in liver and brain tissues, indicating the presence of biochemically significant levels of stress. However, maintenance of acclimatized fish at 17°C for up to 48 h did not lead to a significant decrease in stress protein levels. A heat shock at 37°C for up to 48 h resulted in only two to threefold increase in HSP70 levels in these organs. Although the increase in HSP70 levels was apparent from the first hour of heat stress in all these tissues, the increase was significant from the second hour in the brain, the sixth hour in liver and kidney and the 20th hour in the gills.