Cyclic nucleotide levels in regenerating liver

Cyclic AMP and cyclic GMP levels were measured in rat liver at various times following partial hepatectomy. Cyclic AMP levels show an initial rapid dropfollowed by a biphasic increase while cyclic GMP remains at an almost constant level throughout the time period examined.     

Molecular and karyological aspects of Batoidea (Chondrichthyes, Elasmobranchi) phylogeny

Although considerable progress has been made in elucidating the relationships within the Chondrichthyes, there is no agreement as it concerns the systematics of Batoidea, the most derived superorder among cartilaginous fishes, and many different interpretations exist. Our investigation provides the first assessment of relationships among the described batoid species using sequences from both mtDNA and nuclear genes as well as karyological morphology. Our work consists primarily in reconstructing the phylogenetic relationships of Batoidea by examining the mtDNA (16S) and nuclear gene (18S) sequences from 11 batoid species. The three analytical methods (NJ, MP and Bayesian analysis) grouped Rajiformes, Myliobatiformes and Rhinobatiformes. In these trees the two torpedoes diverge from the other batoid fishes. We also compare the molecular data with the available karyological evidence, which consist of the diploid number and the karyotype morphology of eight species belonging to the four orders examined. The results show that the karyological structure in the different species is generally consistent with the various phylogenetical trees, and that Torpediniformes confirm their unique genome organization.     

Morphology and ultrastructure of spiracles in phlebotomine sandfly larvae

The morphology and ultrastructure of the larval spiracle system of three phlebotomine sandfly species, Phlebotomus perniciosus, P. perfiliewi and P. papatasi, were examined by scanning (SEM) and transmission (TEM) electron microscopy and by confocal scanning laser microscopy (CSLM). During larval development, thoracic and abdominal spiracles show considerable modifications. In fourth instar larvae, the spiracles consist of a plate with a sclerotized central portion and a peripheral circle of papillae. The latter is distinctive in the larvae of P. papatasi, which are readily distinguished from the other species. Opening clefts across the papillae communicate with an internal chamber that encircles an electrondense plug. Many cylindrical projections cross the chamber, uniting the central plug with the larval body, forming an air filter. Spiracular development in successive larval instars has both a taxonomic and adaptive value.     

Multiple phosphorylation of rat liver 3-hydroxy 3-methylglutaryl coenzyme a reductase

Rat liver homogeneous ³²P-labeled hydroxy methylglutaryl coenzyme A reductase, was treated independently with CNBr and trypsin and the resulting [³²P]phosphopeptides were analyzed by disc gel electrophoresis. CNBr treatment produced only one ³²P-fragment of Mr 18,000. The time course of trypsin hydrolysis initially showed the appearance of some phosphopeptides, which were lately converted in two phosphopeptides of low Mr. These results provide direct support for the concept that hydroxy methyl glutaryl coenzyme A reductase kinase solubilized from microsomes phosphorylates only two sites or set of sites in the reductase molecule.     

Cytogenetic Analysis of A- and B-Chromosomes of Prochilodus Lineatus (Teleostei, Prochilodontidae) Using Different Restriction Enzyme Banding and Staining Methods

Different cytogenetic techniques were used to analyse the chromosomes of Prochilodus lineatus with the main objective of comparing the base composition of A- and B-chromosomes. The results of digestion of chromosomes with 10 different restriction endonucleases (REs), silver staining, CMA₃ staining and C-banding indicated the existence of different classes of highly repetitive DNA in the A-set and also suggested the existence of compositional differences between the chromatin of A- and B-chromosomes. The 5-BrdU incorporation technique showed a late replicating pattern in all B-chromosomes and in some heterochromatic pericentromeric regions of A-chromosomes. The cleavage with RE BamHI produced a band pattern in all chromosomes of P. lineatus which permitted the tentative pairing of homologues in the karyotype of this species. We concluded that the combined use of the above techniques can contribute to the correct identification of chromosomes and the karyotypic analysis in fishes. On the basis of the results, some aspects of chromosome structure and the origin of the B-chromosomes in P. lineatus are discussed. This revised version was published online in August 2006 with corrections to the Cover Date.     

Sperm quality and reproductive traits in male offspring of female rabbits exposed to lindane (gamma-HCH) during pregnancy and lactation

Fifteen Grimaud female hybrid rabbits, 135 days old and weighting an average of 3.74+/-0.01 kg each, were administered an oral dose of 1 mg x kg(-1) body weight of Lindane during gestation and lactation period. Fertility rate, libido, volume of ejaculate, concentration and morphology of spermatozoa were investigated to test the effects of the treatment on reproductive traits of first generation male rabbits. Ultrastructure of abnormal spermatozoa was described by Transmission Electron Microscopy and the different abnormalities were quantified. The results obtained indicate that low dose exposure of Lindane has effects on spermatozoa ultrastructure that proved to be susceptible to the treatment with the pesticide (cytoplasmic droplets: 5.3% in control group and 10.3% in Lindane group, P < or = 0.05; coiled tails: 1.3% in control group and 4.3% in Lindane group, P < or = 0.05) and could be utilised as a good marker of toxicity.     

Trypanosoma cruzi glycoprotein of Mr 56000: characterization and assessment of its potential to protect against fatal parasite infections

A ∼ 56 000 Da membrane glycoprotein purified from epimastigotes of Trypanosoma cruzi was characterized biochemically and tested for its efficacy to induce protection in mice from a lethal challenge with this protozoan parasite. Immunofluorescence assays with live and formalin-fixed epimastigotes and trypomastigotes localized the glycoprotein to the flagellum, the body of the parasite, and the cell membrane. Immunoblotting demonstrated the glyco-protein's presence in nearly equal amounts in all developmental stages of several T. cruzi isolates. Mice immunized with the purified glycoprotein and challenged with 10000 infectious trypomastigote forms of isolate Y survived the controls by up to four days. This significant protection makes this antigen a potential candidate for a multi-subunit vaccine against 7. cruzi.