Widespread formation of intracellular calcium carbonates by the bloom-forming cyanobacterium Microcystis

The formation of intracellular amorphous calcium carbonates (iACC) has been recently observed in a few cultured strains of Microcystis, a potentially toxic bloom-forming cyanobacterium found worldwide in freshwater ecosystems. If iACC-forming Microcystis are abundant within blooms, they may represent a significant amount of particulate Ca. Here, we investigate the significance of iACC biomineralization by Microcystis. First, the presence of iACC-forming Microcystis cells has been detected in several eutrophic lakes, indicating that this phenomenon occurs under environmental conditions. Second, some genotypic (presence/absence of ccyA, a marker gene of iACC biomineralization) and phenotypic (presence/absence of iACC) diversity have been detected within a collection of strains isolated from one single lake. This illustrates that this trait is frequent but also variable within Microcystis even at a single locality. Finally, one-third of publicly available genomes of Microcystis were shown to contain the ccyA gene, revealing a wide geographic and phylogenetic distribution within the genus. Overall, the present work shows that the formation of iACC by Microcystis is common under environmental conditions. While its biological function remains undetermined, this process should be further considered regarding the biology of Microcystis and implications on the Ca geochemical cycle in freshwater environments.     

Species differences in the effect of isoproterenol and pindolol on renin release in vitro.

The effects of selective beta adrenergic receptor stimulation with isoproterenol (3 X 10(-8) M) and of beta adrenergic blockade with pindolol (3 X 10(-5) M) on the renin release in vitro were investigated in incubated canine and rat kidney slices. Bioassay was used to measure the renin content of the tissue samples and incubation media; renin content in the canine incubation medium was measured also by radioimmunoassay. Isoproterenol in a concentration of 3 X 10(-8) M brought about a significant increase in the renin content of the incubation media as well as the tissue slices obtained from canine kidney, however, there was no change in these parameters under similar conditions if rat kidneys were incubated. Pindolol, on the other hand, in a concentration of 3 X 10(-5) M caused a significant decrease in the renin release from as well as in the renin content of the rat kidney slices, while canine kidney slices failed to respond to the same dose of the drug. The differences between the two species is suggested to be due to the differences in basal renin levels.     

The UDP-Glc:glycoprotein glucosyltransferase is a soluble protein of the endoplasmic reticulum.

N-linked oligosaccharides devoid of glucose residues are transiently glucosylated directly from UDP-Glc in the endoplasmic reticulum. The reaction products have been identified, depending on the organisms, as protein-linked Glc1Man5-9GlcNAc2. Incubation of right side-sealed vesicles from rat liver with UDP-[14C]Glc, Ca2+ ions and denatured thyroglobulin led to the glucosylation of the macromolecule only when the vesicles had been disrupted previously by sonication or by the addition of detergents to the glucosylation mixture. Similarly, maximal glucosylation of denatured thyroglobulin required disruption of microsomal vesicles isolated from the protozoan Crithidia fasciculata. Treatment of the rat liver vesicles with trypsin led to the inactivation of the UDP-Glc:glycoprotein glucosyltransferase only when proteolysis was performed in the presence of detergents. The glycoprotein glucosylating activity could be solubilized upon sonication of right side-sealed vesicles in an isotonic medium, upon passage of them through a French press or by suspending the vesicles in an hypotonic medium. Moreover, the enzyme appeared in the aqueous phase when the vesicles were submitted to a Triton X-114/water partition. Solubilization was not due to proteolysis of a membrane-bound enzyme. The enzyme could also be solubilized from C. fasciculata microsomal vesicles by procedures not involving membrane disassembly. About 30% of endogenous glycoproteins glucosylated upon incubation of intact rat liver microsomal vesicles with UDP-[14C]GLc could be solubilized by sonication or by suspending the vesicles in 0.1 M Na2CO3. These and previous results show that the UDP-Glc:glycoprotein glucosyltransferase is a soluble protein present in the lumen of the endoplasmic reticulum. In addition, both soluble and membrane-bound glycoproteins may be glucosylated by the glycoprotein glucosylating activity.     

Effect of gamma-irradiation on the enzyme activity of cerebrospinal fluid lymphocytes in dogs

Cytochemical activity of succinate dehydrogenase (SDG), L-glycerophosphate dehydrogenase (L-GPDG), lactate dehydrogenase (LDG), and glutamate dehydrogenase (GDG) increased immediately after total-body irradiation with a dose of 129 mC/kg. After 2 h, LDG activity only returned to the control level. Irradiation of the head with the same dose caused less pronounced changes. Changes caused by lethal irradiation (1290 mC/kg) were different: there was an increase after exposure of the abdomen and a decrease in the activity of SDG and L-GPDG after irradiation of the head.     

A correlation between BCL-2 modifying factor,p53 and livin gene expressions in cancer colon patients

Accumulating evidence has revealed that livin gene and BCL-2 modifying factor (BMF) gene are closely associated with the initiation and progression of colon carcinoma by activating or suppressing multiple malignant processes. Those genes that can detect colon - cancer are a promising approach for cancer screening and diagnosis. This study aimed to evaluate correlation between livin, BMF and p53 genes expression in colon cancer tissues of patients included in the study, and their relationship with clinicopathological features and survival outcome in those patients. In this study, 50 pathologically diagnosed early cancer colon patients included and their tissue biopsy with 50 matched adjacent normal tissue, and 50 adenoma tissue specimens were analyzed for livin gene and BMF gene expressions using real time PCR. The relationship of those genes expressions with clinicopathological features, tumor markers, Time to Progression and overall survival for those patients were correlated in cancer colon group. In this study, there was a significant a reciprocal relationship between over expression of livin gene and down regulation of BMF and p53 genes in colon cancer cells. Livin mRNA was significantly higher, while BMF and p53 mRNA were significantly lower in colorectal cancer tissue compared to benign and normal colon tissue specimens (P < 0.001), however, this finding was absent between colon adenomas and normal mucosa. There was a significant association between up regulation of livin and down regulation of BMF and p53 expressions with more aggressive tumor (advanced TNM stage), rapid progression with metastasis and decreased overall survival in cancer colon patients, hence these genes can serve as significant prognostic markers of poor outcome in colon cancer patients. This work highlights the role of livin, BMF and p53 genes in colorectal tumorigenesis and the applicability of using those genes as a diagnostic and prognostic markers in patients with colon carcinoma and as a good target for cancer colon treatment in the future.