“A cleaner break”: Genetic divergence between geographic groups and sympatric phenotypes revealed in ballan wrasse (Labrus bergylta)

Capture and long‐distance translocation of cleaner fish to control lice infestations on marine salmonid farms has the potential to influence wild populations via overexploitation in source regions, and introgression in recipient regions. Knowledge of population genetic structure is therefore required. We studied the genetic structure of ballan wrasse, a phenotypically diverse and extensively used cleaner fish, from 18 locations in Norway and Sweden, and from Galicia, Spain, using 82 SNP markers. We detected two very distinct genetic groups in Scandinavia, northwestern and southeastern. These groups were split by a stretch of sandy beaches in southwest Norway, representing a habitat discontinuity for this rocky shore associated benthic egg‐laying species. Wrasse from Galicia were highly differentiated from all Scandinavian locations, but more similar to northwestern than southeastern locations. Distinct genetic differences were observed between sympatric spotty and plain phenotypes in Galicia, but not in Scandinavia. The mechanisms underlying the geographic patterns between phenotypes are discussed, but not identified. We conclude that extensive aquaculture‐mediated translocation of ballan wrasse from Sweden and southern Norway to western and middle Norway has the potential to mix genetically distinct populations. These results question the sustainability of the current cleaner fish practice.     

ATP(GTP)-dependent conversion of MVM parvovirus single-stranded DNA to its replicative form by a purified 10 S species of mouse DNA polymerase alpha

A species of DNA polymerase alpha that is active in the ATP(GTP)-dependent conversion of MVM parvovirus single-stranded linear DNA to the duplex replicative form has been purified 4300-fold from Ehrlich ascites mouse tumour cells. The single-stranded----replicative form activity is maintained throughout ammonium sulfate precipitation, DEAE-cellulose, phosphocellulose and hydroxyapatite column chromatography and glycerol gradient sedimentation. Polypeptides with Mr = 230 000, 220 000, 183 000, 157 000, 125 000, 70 000, 65 000, 62 000, 57 000, 53 000 and 48 000 copurify with the single-stranded----replicative form activity, which sediments at approx. 10 S. The Mr = 183 000, 157 000 and 125 000 polypeptides exhibit catalytic activity when assayed in situ following SDS-polyacrylamide gel electrophoresis. The 10 S form of DNA polymerase alpha is functionally distinguishable from an 8.4 S form of the enzyme obtained from the same cells on the basis of single-stranded----replicative form activity. The single-stranded----replicative form activity of the 10 S enzyme is stable at 22 degrees C for up to 3 h, but exhibits a half life of only 5 min at 45 degrees C.     

Metabolic changes associated with bud break induced by thidiazuron

Bud break in apple (Golden Delicious,Malus domestica Borkh) was induced by thidiazuron (N-phenyl-N-1,2,3-thidiazol-5-ylurea). In control and thidiazuron-treated shoots, higher amounts of soluble carbohydrates (sorbitol, fructose, glucose, sucrose) and galacturonic acid were found in the phloem, but higher amounts of starch and cell wall polysaccharides, including cellulose and xylose, were found in the xylem. A decrease in soluble carbohydrates and starch in both phloem and xylem was associated with induction of bud break by thidiazuron. However, little change in cell wall polysaccharides was found. Total carbohydrates were higher in the upper than in the lower portion of shoots. The breaking of dormancy by thidiazuron was also associated with an increase in organic acid content and respiration in buds. KCN inhibited bud respiration during all stages of development. Organic acid content was inversely related to carbohydrate content in developing buds. Axes contained more carbohydrates and organic acids than did scales.     

The biotechnology of Bacillus thuringiensis

One of the challenges in the application of biotechnology to pest control is the identification of agents found in nature which can be used effectively. Biotechnology offers the potential of developing pesticides based on such agents which will provide environmentally sound and economically feasible insect control alternatives. Such an agent, the insect pathogen Bacillus thuringiensis, is the subject of intense investigations in several laboratories. Insecticides which use the entomocidal properties of B. thuringiensis are currently produced and sold worldwide; new products are currently in the development stage. Herein, the biology and genetics of B. thuringiensis and the problems associated with current products are critically reviewed with respect to biotechnology. Moreover, the economic and regulatory implications of technologically advanced products are evaluated.     

Effect of prostaglandin F3 alpha on gastric mucosal injury by ethanol in rats: comparison with prostaglandin F2 alpha

In humans eicosapentaenoic acid can be converted to 3-series prostaglandins (PGF3 alpha, PGI3, and PGE3). Whether 3-series prostaglandins can protect the gastric mucosa from injury as effectively as their 2-series analogs is unknown. Therefore, we compared the protective effects of PGF3 alpha and PGF2 alpha against gross and microscopic gastric mucosal injury in rats. Animals received a subcutaneous injection of either PGF3 alpha or PGF2 alpha in doses ranging from 0 (vehicle) to 16.8 mumol/kg and 30 min later they received intragastric administration of 1 ml of absolute ethanol. Whether mucosal injury was assessed 60 min or 5 min after ethanol, PGF3 alpha was significantly less protective against ethanol-induced damage than PGF2 alpha. These findings indicate that the presence of a third double bond in the prostaglandin F molecule between carbons 17 and 18 markedly reduces the protective effects of this prostaglandin on the gastric mucosa.     

A novel primase-free form of murine DNA polymerase alpha induced by infection with minute virus of mice

Two species of DNA polymerase alpha free of primase activity were identified in extracts of Ehrlich mouse cells that had been infected with minute virus of mice. Primase-free forms of DNA polymerase alpha eluted with 150 and 180 mM NaCl during ion-exchange chromatography on DEAE-cellulose columns, exhibited sedimentation coefficients of 11 S and 8.2 S, respectively, and were inhibited by aphidicolin, N2-(p-n-butylphenyl)-9-(2-deoxy-beta-D-ribofuranosyl)guanine 5'-triphosphate, and 2-(p-n-butylanilino)-9-(2-deoxy-beta-D-ribofuranosyl)adenine 5'-triphosphate. The ratio of primase-free DNA polymerase alpha to the DNA polymerase alpha-primase complex increased from 1.5 to greater than 100 during the course of infection, and free primase was produced during the MVM replicative cycle.     

广东哺乳类及两栖类寄生吸虫四新种的记述（吸虫纲：蹲茎科,蛙蠕科）

作者在广东省梅县市发现四个吸虫新种:1.鼠丽色吸虫,新种Reesella ratta sp. nov., 2.后囊蛙蠕吸虫,新种Batrachotrema optstosacca sp. nov., 3.梅县后平睾吸虫,新种Opisthioparorchis meixianensis sp. nov., 4.大卵后平睾吸虫,新种Opisthioparorchis megaloonos sp. nov.,它们分别归隶于蹲茎科Cathaemasiidae及蛙蠕科Bstrachotrematidae。模式标本保存于中山医科大学寄生虫学研究所。     

Extended investigation of the substrate specificity of dipeptidyl peptidase IV from pig kidney.

The substrate specificity of dipeptidyl peptidase IV (dipeptidyl peptide hydrolase, EC 3.4.14.5) from pig kidney was investigated, using a series of substrates, in which the amino-acid residue in position P1, a structural derivative of proline, was altered with respect to ring size and substituents. It was demonstrated that dipeptidyl peptidase IV hydrolyses substrates of the type Ala-X-pNA, where X is proline (Pro), (R)-thiazolidine-4-carboxylic acid (Thz), (S)-pipecolic acid (Pip), (S)-oxazolidine-4-carboxylic acid (Oxa), or (S)-azetidine-2-carboxylic acid (Aze). The ring size and ring structure of the residue in the P1 position influence the rate of enzyme-catalysed hydrolysis of the substrate. The highest kcat value (814 s-1) was found for Ala-Aze-pNA. In contrast, the kcat value for Ala-Pro-pNA is nearly 55 s-1. With all substrates of this series, the rate-limiting step of the hydrolysis by dipeptidyl peptidase IV is the deacylation reaction. Compounds of substrate-like structure, in which the P2 residue has an R-configuration, are not hydrolysed by dipeptidyl peptidase IV.     

Secretion of a lipid transfer protein by human monocyte-derived macrophages

Human monocyte-derived macrophages in culture were shown to synthesize and secrete a lipid transfer protein. The human monocyte-derived macrophage transfer protein showed the following characteristics: (i) linear secretion rate over a 24-h period, which was blocked completely by cycloheximide and stimulated by phorbol myristate acetate (67% increase over nonstimulated values); (ii) apparent Mr = approximately 62,000 off Sephacryl S-200; (iii) isoelectric point of 5.0; (iv) binding to phenyl-Sepharose, but not to heparin-Sepharose; (v) facilitation of the transfer of both neutral lipids (cholesteryl esters and triglycerides) and phosphatidylcholine between high density lipoproteins and d less than 1.063 g/ml lipoproteins; and (vi) thermal stability (stable for 1 h at 56 degrees C). The last five of these properties are similar to those of the plasma lipid transfer protein. Thus, macrophages secrete a lipid transfer protein that closely resembles the neutral lipid transfer protein found in human plasma and may be a source of this plasma protein in vivo.