A Connectivity-Based Eco-Regionalization Method of the Mediterranean Sea

Ecoregionalization of the ocean is a necessary step for spatial management of marine resources. Previous ecoregionalization efforts were based either on the distribution of species or on the distribution of physical and biogeochemical properties. These approaches ignore the dispersal of species by oceanic circulation that can connect regions and isolates others. This dispersal effect can be quantified through connectivity that is the probability, or time of transport between distinct regions. Here a new regionalization method based on a connectivity approach is described and applied to the Mediterranean Sea. This method is based on an ensemble of Lagrangian particle numerical simulations using ocean model outputs at 1/12° resolution. The domain is divided into square subregions of 50 km size. Then particle trajectories are used to quantify the oceanographic distance between each subregions, here defined as the mean connection time. Finally the oceanographic distance matrix is used as a basis for a hierarchical clustering. 22 regions are retained and discussed together with a quantification of the stability of boundaries between regions. Identified regions are generally consistent with the general circulation with boundaries located along current jets or surrounding gyres patterns. Regions are discussed in the light of existing ecoregionalizations and available knowledge on plankton distributions. This objective method complements static regionalization approaches based on the environmental niche concept and can be applied to any oceanic region at any scale.     

Isolation of rat hepatocytes by a nonenzymatic method: detoxifying and respiratory activity]

A procedure for isolation of rat hepatocytes involving perfusion by EDTA, mechanical disaggregation of the liver and separation of intact cells from damaged ones by low-velocity centrifugation in isotonic sucrose media is described. A layer of a darker colour formed after separation contains hepatocytes with native plasma membrane characterized by respiratory activity and rate of biotransformation being close to the values obtained with cells isolated with the application of collagenase.     

Inactivation and mutagenesis of lambda phage by O-methylhydroxylamine and O-delta-aminooxybutylhydroxylamine

The inactivation and the mutagenesis of lambda phage Cl 857 virR by O-methylhydroxylamine (OMHA) and O-delta-aminooxybuthylhydroxylamine (delta-HA) were studied. The inactivation of OMHA-treated phage was shown to be stronger in E. coli polA cells defective in DNA-polymerase I as compared to wild-type host E. coli W3350. In contrast delta-HA caused similar phage inactivation in these two strains. Wave-type kinetics of the inactivation and the mutagenesis of phage by OMHA and delta-HA was observed. delta-HA appeared to be a more effective mutagen than OMHA: it induced higher mutant yield at a given level of inactivation.     

Estrous Cycle,Folliculogenesis, and Brain Catecholamines after Stimulation of the Sexual System by Choriogonadotropin in Female Minks Selected for Behavior

The content of hypothalamic dopamine (DA) and noradrenaline (NA) is determined and ovary function (folliculogenesis) in various states of estrous cycle is studied in non-selected (control) immature (7-month old) standard female minks and in similar females of aggressive and quiet behavioral types (the 18th generation of selection) in norm and at the 7th day after single intramuscular injections of chorionic gonadotropin (CG). At the 7th day after the CG administrations, the control females were distributed by their estrous cycle state as follows: anestrus (A)— 47.2%, anestrus-proestrus (AP)—10.0%, proestrus (P)—8.5%, proestrus-estrus (PE)—14.3%, and estrus (E)— 20.0%. In the female minks selected for behavior, there was a significant increase of percentage of estrous females: to 84.6% in the aggressive ( p < 0.001) and to 58.4% in the quiet type animals ( p < 0.01). The number of growing and maturing (at the early stage) follicles in intact females of aggressive behavior was lower than in control and in females of the quiet type. However, the number of Graafian vesicles in ovaries of aggressive and quiet females did not differ and exceeded control. The stimulation by CG enhanced the differences between the ovaries of selected animals. In control females at the 7th day after CG injections there was a tendency for a decrease of the DA and NA content with development of estrus (A→AP→P). The hypothalamic DA concentration was higher in intact females of the aggressive type than in the quiet females ( p < 0.05). In animals of the aggressive type, stimulation of the sex system decreased the DA level. No correlation between sexual function and DA and NA levels was found in females of the quiet type. However, differential analysis of NA in these females with different reactions of vaginal epithelium to CG stimulation (A, AP vs P, PE, E) indicates correlation of catecholamine level with sexual function. Thus, selection of minks for aggressive behavioral type produces an increase of the hypothalamic catecholamine level, which, in turn, is one of factors inhibiting sexual function.__________Translated from Zhurnal Evolyutsionnoi Biokhimii i Fiziologii, Vol. 41, No. 3, 2005, pp. 266–271.Original Russian Text Copyright © 2005 by Klochkov, Alekhina, Trapezov, Petrenko.     

Isolation of mutant genes for human leukocyte alpha2-interferon by a method of localized mutagenesis

An efficient method to obtain the mutant genes for human leucocyte alpha 2-interferon (IFN) has been elaborated.The technique includes the following main stages: cloning of interferon gene in M13mp8 DNA; isolation of double-stranded hybrid DNA complex, containing IFN gene as a single-stranded fragment; selective modification of a single-stranded hybrid DNA by sodium bisulphite; the repair of hybrid DNA by DNA polymerase I from Escherichia coli, transformation of Escherichia coli JN103 cells by double-stranded circular DNA, containing the selectively modified gene IFN. The technique is based on the protection of bacteriophage M13 genome from mutagen induced damage by means of converting phage DNA into the double-stranded structure leaving the single-stranded fragment to be mutagenized prone to mutagen action. This is achieved by reannealing of single-stranded M13mpB DNA hydrolyzed by restriction endonuclease BamHI. The technique preserves the infectiousness of vector DNA under the conditions permitting modification of up to 10% cytosine residues in IFN gene. Every clone resulting from transformation of Escherichia coli by modified DNA carried mutations in IFN gene, identified by sequencing after Sanger.     

Exogenous NADPH restores the detoxication function of isolated hepatocytes lost in the process of freezing-thawing]

Freezing and thawing have been studied for their effect on the rat hepatocyte detoxication system. Freezing-thawing of hepatocytes in the medium without cryoprotectors is to impair functioning of the biotransformation system of biphenyl, a hydrophobic xenobiotic. It is found that inhibition of the first stage of xenobiotics biotransformation is a result of the loss of pyridine nucleotides and substrates necessary for NADP+ reduction.     

The anlage of the duodenal lymphatic bed: morphogenetic prerequisites, structure and importance

The anlage of the duodenal lymphatic bed takes place on the 3d month of the human intrauterine life. In the intestinal villi there are chyle sinuses, that fuse into presumptive lymphatic vessels, having capillary structure, when they get out of the villi. Intraorganic vessels turn into extraorganic ones, they flow into the pancreatoduodenal lymphatic vessels. In their lumens stromal anlage of the lymphatic nodes are formed as a result of invagination of the blood vessels. Development of the lymphatic bed in the duodenum preceded with formation of intestinal villi (this contributes to absorption of the intestinal content) and deformity of the superior mesenteric vein (this probably makes difficult the organ's drainage). The situation is solved owing to the lymphatic bed anlage. It is, evidently, formed by means of switching off a part of embryonal veins from the blood stream.