Pepsinogen is one kind of gastric digestive proteinases belonging to a family of aspartic proteinases,which is synthesized in the gastric mucosa of vertebrates and converted to pepsins in the acidic environment of gas...
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Pepsinogen is one kind of gastric digestive proteinases belonging to a family of aspartic proteinases,which is synthesized in the gastric mucosa of vertebrates and converted to pepsins in the acidic environment of gastric *** mandarin fish(Siniperca chuatsi) is a typical carnivorous fish which only prey on small live fishes after *** order to understand the molecular characters of pepsinogen in fish,the full-length cDNA of pepsinogen gene of *** was cloned by means of RT-PCR and rapid amplification of cDNA ends(RACE) and *** result reveals a 1 367 bp cDNA full-length sequence containing 43 bp 5′-untranslated region,187 bp 3′-untranslated region and 1 137 bp open reading frame(ORF),which encodes 378 amino acids with characteristic signal peptides and activation *** pepsinogen of *** also has highly conserved amino acid residues essential for catalytic activity and conformational maintenance,which are two essential aspartyl residues in the active site and six cysteine residues involved in forming three disulphide *** homology of amino acid sequences between pepsinogen of *** and other vertebrate pepsinogens ranges from 59.9% to 91.2%,which indicates the pepsinogen gene is highly conserved in *** NJ phylogenetic tree of vertebrates from the amino acids sequences of pepsinogen showed all fish were clustered as a group,the pepsinogen of *** was the closest to pepsinogen A form Ⅱa of winter *** successful cloning of pepsinogen gene from *** not only lays the foundation for further study of its temporal and spatial expression,but also provides new material for the molecular characteristics and evolution of fish pepsinogen.
2006年8～9月,在浙江象山港花鲈（Lateolabrax japonicus）养殖网箱中吊养真江蓠（Gracilaria verrucosa）对网箱养殖造成的水体富营养化进行生态修复研究。通过45d内的平面监测、定点跟踪监测和断面监测,结果表明：该网箱养殖区水体呈严重富营养化状态,营养状态指数（E）为32.00,其营养盐分布由高浓度的中心区向周围150m非养殖水域扩散;真江蓠对养殖区的富营养化海水具有较好的修复效果：江蓠生态修复区及其相邻网箱中水体PO4-P、NO2-N、NH4-N和NO3-N含量显著低于非修复区（P〈0.01）,修复区海水PO4-P、NO2-N、NH4-N和NO3-N浓度比非修复区分别降低22%～58%、24%～48%、22%～61%和24%～47%。养殖真江蓠45d后,修复区水体DO浓度和透明度显著高于非修复区（P〈0.05）,DO平均提高28%,透明度平均提高30%;而修复区水体Chl-a浓度显著低于非修复区（P〈0.05）,平均降低49%。通过建立基于N平衡的鱼藻生态养殖模式,每收获1kg花鲈至少需要匹配江蓠4.7 kg wetwt才可实现对鱼类排放N的完全吸收。因此网箱内栽培江蓠的混合生态养殖模式,可平衡因经济动物养殖所带来的额外营养负荷,有利于实现动物养殖环境的自我修复。
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