Survival of human enteroviruses in the Hawaiian ocean environment: evidence for virus-inactivating microorganisms.

The stability of certain human enteroviruses in the Hawaiian ocean environment was examined. The present data indicated that the time for 90% reduction of poliovirus type 1 at 24 +/- 1 degree C in seawater samples obtained from different sites in Hawaii ranged from 24 to 48 h, and complete inactivation occurred within 72 to 96 h. The accumulated evidence also strongly indicated that a virus-inactivating agent(s) of a microbiological nature was present in both clean and sewage-polluted seawaters, but not in fresh, mountain stream waters. The antiviral activity was lost when the seawater samples were subjected to boiling, autoclaving, or filtration through a 0.22- or 0.45-micrometer, but not a 1.0-micrometer, membrane filter. That the antiviral activity of the seawater was related to the growth activities of microorganisms was corroborated by the observed effects of added nutrients, a lower temperature of incubation, and the presence of certain antibiotics. Other enteric viruses, such as coxsackie virus B-4 and echo virus-7, were also shown to be similarly inactivated in seawater.     

Auxin, Cytokinin and Ethylene Differentially Regulate Specific Developmental States Associated with Shoot Bud Morphogenesis in Leaf Tissues of Mangosteen (Garcinia mangostana L.) Cultured in Vitro

Hormonal regulation of de novo shoot bud formation in leaf explantsof mangosteen has been studied from a developmental perspective.This analysis indicates that at least three discrete, experimentallydistinguishable developmental states, namely, morphogenic competence,caulogenic determination and organ differentiation, were expressedduring shoot bud morphogenesis. The state of morphogenic competencein leaf tissues was expressed maximally between days 10 and12 of leaf development. Competent cells in explants requireda minimum of 6 days of BA treatment (20 µM) to becomecaulogenically determined. Such determined cells would continueshoot organogenesis on medium devoid of growth regulators. Delayingof BA exposure for as short as 2 days caused a dramatic declinein tissue competence. The state of competence and the processof caulogenic determination were adversely affected by IAA,but were insensitive to ethylene or its precursor, ACC. Shootbud differentiation was greatly enhanced by BA, but selectivelydelayed by ethylene. IAA also showed an inhibitory effect onshoot bud differentiation, but not mediated through ethylene.The distinct roles of auxin, cytokinin and ethylene on the regulationof shoot bud development in mangosteen leaf explants have beendiscussed on the basis of the current understanding of the conceptof tissue competence, determination and differentiation. (Received August 12, 1996; Accepted October 31, 1996)     

Ablation of phosphoinositide-3-kinase class II alpha suppresses hepatoma cell proliferation

Cancer such as hepatocellular carcinoma (HCC) is characterized by complex perturbations in multiple signaling pathways, including the phosphoinositide-3-kinase (PI3K/AKT) pathways. Herein we investigated the role of PI3K catalytic isoforms, particularly class II isoforms in HCC proliferation. Among the siRNAs tested against the eight known catalytic PI3K isoforms, specific ablation of class II PI3K alpha (PIK3C2α) was the most effective in impairing cell growth and this was accompanied by concomitant decrease in PIK3C2α mRNA and protein levels. Colony formation ability of cells deficient for PIK3C2α was markedly reduced and growth arrest was associated with increased caspase 3 levels. A small but significant difference in gene dosage and expression levels was detected between tumor and non-tumor tissues in a cohort of 19 HCC patients. Taken together, these data suggest for the first time that in addition to class I PI3Ks in cancer, class II PIK3C2α can modulate HCC cell growth.     

Intracellular acetylation of desacetyl alpha MSH in the Xenopus laevis neurointermediate lobe

High performance liquid chromatography (HPLC) followed by radioimmunoassay (RIA) of the chromatographic fractions were used to separate and quantify, respectively, the alpha MSH-like peptides stored in the neurointermediate lobe (NIL) of the Xenopus laevis (X. laevis) pituitary gland and released from the X. laevis NIL, in vitro. Immunoreactive (IR) material eluting with a similar HPLC retention time as desacetyl alpha MSH was the major IR peptide in the NIL. Material with a retention time similar to alpha MSH and immunological properties equivalent to alpha MSH was also present in the NIL. However, the retention times of the X. laevis and mammalian alpha MSH-like peptides were not identical, suggesting species difference in these peptides. Following incubation of NILs in the presence of [3H]-acetyl CoA, the X. laevis variant of alpha MSH was the major [3H]-labeled, immunoprecipitable material present. Following an incubation of NILs in the presence of [3H]-amino acids for 21 hours, immunoprecipitable [3H]-alpha MSH was detected in the NILs and the ratio of [3H]-desacetyl alpha MSH to [3H]-alpha MSH was similar to the ratio of IR-desacetyl alpha MSH to IR-alpha MSH. The X. laevis variant of alpha MSH was the major alpha MSH-like peptide released from the NILs into the incubation medium. Dopamine (50 microM) significantly inhibited the release of IR-alpha MSH but not IR-desacetyl alpha MSH. No net increase in total alpha MSH (sum of release and NIL content) was observed in the actively secreting (control) NIL group versus the dopamine-treated group. These results indicate that acetylation of desacetyl alpha MSH occurs intracellularly.