Vanadium compounds

The direct effect of different vanadium compounds upon alkaline phosphatase (ALP) activity was investigated. Vanadate and vanadyl inhibited both the soluble and particulate ALP activity from UMR.106 cells and from bovine intestinal ALP. We have also shown the inhibition of ALP activity in the soluble fraction of osteoblasts by peroxo and hydroperoxo vanadium compounds. ALP activity in the particulate fraction was not inhibited by these species; nor was the bovine intestinal ALP. Using inhibitors of Tyr-phosphatase (PTPases), the soluble ALP was partially characterized as a PTPase. The major activity in the particulate fraction represents the bone-specific ALP-activity. This study demonstrates that different forms of vanadium are direct inhibitors of ALP activity. This effect is dependent on the enzymatic activity investigated and on the origin of the ALP.     

Larval development of three blenniid species Aidablennius sphynx, Coryphoblennius galerita and Lipophrys canevai (Pisces: Blenniidae: Blenniini) in the western Mediterranean

The early stages of development of three blenniid species, Aidablennius sphynx (6.7–15.8 mm BL), Coryphoblennius galerita (4.3–13.9mm BL), and Lipophrys canevai (3.5–10.4 mm BL) are described from specimens collected in the western Mediterranean. The characteristics used for identification included meristic, developmental, morphological and pigmentation characters. Distinguishing characters of these species useful in differentiating them from other species of blenniids for which early stages are known in the Mediterranean are presented. Information on the occurrence of larvae and juveniles of these species off the Catalan coast (north-western Mediterranean) is also given.     

Alzheimer's disease-like phosphorylation of the microtubule-associated protein tau by glycogen synthase kinase-3 in transfected mammalian cells

Background: Paired helical filaments (PHFs) are a characteristic pathological feature of Alzheimer's disease; their principal component is the microtubule-associated protein tau. The tau in PHFs (PHF-tau) is hyperphosphorylated, but the cellular mechanisms responsible for this hyperphosphorylation have yet to be elucidated. A number of kinases, including mitogen-activated protein (MAP) kinase, glycogen synthase kinase (GSK)-3α, GSK-3β and cyclin-dependent kinase-5, phosphorylate recombinant tau in vitro so that it resembles PHF-tau as judged by its reactivity with a panel of antibodies capable of discriminating between normal tau and PHF-tau, and by a reduced electrophoretic mobility that is characteristic of PHF-tau. To determine whether MAP kinase, GSK-3α and GSK-3β can also induce Alzheimer's disease-like phosphorylation of tau in mammalian cells, we studied the phosphorylation status of tau in primary neuronal cultures and transfected COS cells following changes in the activities of MAP kinase and GSK-3.Results Activating MAP kinase in cultures of primary neurons or transfected COS cells expressing tau isoforms did not increase the level of phosphorylation for any PHF-tau epitope investigated. But elevating GSK-3 activity in the COS cells by co-transfection with GSK-3α or GSK-3β decreased the electrophoretic mobility of tau so that it resembled that of PHF-tau, and induced reactivity with eight PHF-tau-selective monoclonal antibodies.Conclusion Our data indicate that GSK-3α and/or GSK-3β, but not MAP kinase, are good candidates for generating PHF-type phosphorylation of tau in Alzheimer's disease. The involvement of other kinases in the generation of PHFs cannot, however, be eliminated. Our results suggest that aberrant regulation of GSK-3 may be a pathogenic mechanism in Alzheimer's disease.     

Effect of bovine somatotropin on reproductive function in lactating dairy cows

Several recent experiments have reported that chronic treatment with bovine somatotropin (bST) increased the number of days open without affecting the services per conception. The physiological basis for these effects was examined. Eleven lactating Holstein cows received daily injections of bST (40 mg) and 10 received daily injections of vehicle. Treatment was initiated between 32 and 85 d post partum and continued for up to 180 d. Eight of 11 bST-treated cows experienced at least one period of extended ovarian acyclicity during treatment. Only 3 of 10 control cows did so (P = 0.05). Concentrations of progesterone during luteal phases were lower in bST-treated cows than in controls (P = 0.06). Baseline concentrations of LH were suppressed in bST-treated cows compared with those of controls (P < 0.04). Neither the pulse frequency of LH nor the expression of estrous behavior was affected by bST (P > 0.30). These results indicate that chronic administration of a high dose of bST can reduce reproduction performance by promoting ovarian acyclicity.     

Cold-induced Chromosome Regions and Karyosystematics in Sambucus and Viburnum

The genera Viburnum, Sambucus and Lonicera have been investigated for chromosome number and karyomorphology including Giemsa-C-banding, fluorochrome (DAPI/CMA) banding and cold treatment. Cold-induced undercontracted chromosome regions (CIRs) are found in Viburnum and Sambucus for the first time and are apparently identical with larger hc regions, shown by Giemsa C-banding. Certain narrow C-bands are not cold-sensitive. CIRs frequently react brightly CMA-positive in Viburnum and Sambucus, while DAPI fluorescence is virtually ineffective. The occurrence of CIRs within plants is possibly linked to certain nuclear characters such as large chromosomes and continuous condensation behaviour. Cold-induction has possibly also some influence on euchromatin condensation characteristics in prophasic chromosomes. Several karyological characters point to a closer relationship between Viburnum, Sambucus and Adoxa: Relatively large chromosomes, continuous condensation behaviour, reticulate to semireticulate interphase nuclei and presence of CIRs. These genera appear isolated from Lonicera and the Caprifoliaceae s.str., which differ remarkably in karyomorphology.     

Single-cell investigation by laser scanning confocal microscopy of cytochemical alterations resulting from extracellular oxidant challenge

Confocal laser scanning fluorescence microscopy coupled to image analysis was employed in order to develop and evaluate procedures for the appraisal at the single-cell level of: (1) protein-bound 4-hydroxynonenal, the specific product of membrane peroxidation (by means of immunocytochemistry with biotin-avidin revelation); (2) protein oxidation (by reaction of protein carbonyls with 2,4-dinitrophenyl-hydrazine followed by immunocytochemistry of dinitrophenyl moieties); and (3) cellular protein thiols (by direct alkylation of sulfhydryl groups with thiol-specific fluorescent reagents possessing different cell permeabilities). The procedures proved able to reveal the subcellular distribution of cytochemical parameters useful as indices of oxidative stress conditions, and may allow redox phenotyping of isolated cells, which would provide an efficient tool in selected experimental models.