scholarly journals Proline-Rich Peptide from the Coral PathogenVibrio shiloi That Inhibits Photosynthesis of Zooxanthellae

2001 ◽  
Vol 67 (4) ◽  
pp. 1536-1541 ◽  
Author(s):  
Ehud Banin ◽  
Sanjay K. Khare ◽  
Fred Naider ◽  
Eugene Rosenberg
Keyword(s):  
Molecular Weight ◽  
Coral Bleaching ◽  
Rapid Decrease ◽  
Bulk Liquid ◽  
Symbiotic Algae ◽  
P Concentration ◽  
Vibrio Shiloi ◽  
Casamino Acids ◽  
Proline Rich Peptide ◽  
Subsequent Addition

ABSTRACT The coral-bleaching bacterium Vibrio shiloibiosynthesizes and secretes an extracellular peptide, referred to as toxin P, which inhibits photosynthesis of coral symbiotic algae (zooxanthellae). Toxin P was produced during the stationary phase when the bacterium was grown on peptone or Casamino Acids media at 29°C. Glycerol inhibited the production of toxin P. Toxin P was purified to homogeneity, yielding the following 12-residue peptide: PYPVYAPPPVVP (molecular weight, 1,295.54). The structure of toxin P was confirmed by chemical synthesis. In the presence of 12.5 mM NH4Cl, pure natural or synthetic toxin P (10 μM) caused a 64% decrease in the photosynthetic quantum yield of zooxanthellae within 5 min. The inhibition was proportional to the toxin P concentration. Toxin P bound avidly to zooxanthellae, such that subsequent addition of NH4Cl resulted in rapid inhibition of photosynthesis. When zooxanthellae were incubated in the presence of NH4Cl and toxin P, there was a rapid decrease in the pH (pH 7.8 to 7.2) of the bulk liquid, suggesting that toxin P facilitates transport of NH3 into the cell. It is known that uptake of NH3 into cells can destroy the pH gradient and block photosynthesis. This mode of action of toxin P can help explain the mechanism of coral bleaching by V. shiloi.

Biophysical Studies of a Proline-Rich Peptide from the Coral Bleach Pathogen Vibrio shiloi

2001 ◽  
pp. 375-376
Author(s):  
Sanjay K. Khare ◽  
Boris Arshava ◽  
Ehud Banin ◽  
Eugene Rosenberg ◽  
Fred Naider
Keyword(s):  
Biophysical Studies ◽  
Vibrio Shiloi ◽  
Proline Rich Peptide

Polydispersity Effects in Evaporation of Perfluoropolyether Thin Films

2001 ◽  
Author(s):  
Michael Stirniman ◽  
Jing Gui
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Molecular Weight ◽  
Weight Distribution ◽  
Evaporation Rate ◽  
Surface Interactions ◽  
Bulk Liquid ◽  
Vapor Pressures ◽  
Thin Film Evaporation ◽  
Film Evaporation

Abstract The evaporation rates of bulk liquid and thin films of an alcohol-derivatized perfluoropolyether have been studied experimentally and computationally. We find that the time dependence of the evaporation rate in both cases is dominated by the polydispersity, and can be described very well by a model that incorporates the molecular weight distribution, molecular-weight-dependent Arrhenius parameters of evaporation, and Raoult’s law of vapor pressures. Minor corrections to the model that account for surface interactions are necessary in the case of thin film evaporation.

scholarly journals Penetration of the Coral-Bleaching BacteriumVibrio shiloi into Oculina patagonica

2000 ◽  
Vol 66 (7) ◽  
pp. 3031-3036 ◽  
Author(s):  
E. Banin ◽  
T. Israely ◽  
A. Kushmaro ◽  
Y. Loya ◽  
E. Orr ◽  
...  
Keyword(s):  
Coral Bleaching ◽  
Agar Medium ◽  
Viable Count ◽  
Coral Tissue ◽  
Intracellular Bacteria ◽  
Initial Inoculum ◽  
A Value ◽  
Vibrio Shiloi ◽  
High Concentrations

ABSTRACT Inoculation of the coral-bleaching bacterium Vibrio shiloi into seawater containing its host Oculina patagonica led to adhesion of the bacteria to the coral surface via a β-d-galactose receptor, followed by penetration of the bacteria into the coral tissue. The internalized V. shiloi cells were observed inside the exodermal layer of the coral by electron microscopy and fluorescence microscopy using specific anti-V. shiloi antibodies to stain the intracellular bacteria. At 29�C, 80% of the bacteria bound to the coral within 8 h. Penetration, measured by the viable count (gentamicin invasion assay) inside the coral tissue, was 5.6, 20.9, and 21.7% of the initial inoculum at 8, 12, and 24 h, respectively. The viable count in the coral tissue decreased to 5.3% at 48 h, and none could be detected at 72 h. Determination of V. shiloi total counts (using the anti-V. shiloiantibodies) in the coral tissue showed results similar to viable counts for the first 12 h of infection. After 12 h, however, the total count more than doubled from 12 to 24 h and continued to rise, reaching a value 6 times that of the initial inoculum at 72 h. Thus, the intracellular V. shiloi organisms were transformed into a form that could multiply inside the coral tissue but did not form colonies on agar medium. Internalization of the bacteria was accompanied by the production of high concentrations of V. shiloi toxin P activity in the coral tissue. Internalization and multiplication of V. shiloi are discussed in terms of the mechanism of bacterial bleaching of corals.

Concentrations and Kinetics of Phosphorus Fractions in Water from Streams Entering Lake Memphremagog

1978 ◽  
Vol 35 (3) ◽  
pp. 315-328 ◽  
Author(s):  
Robert Henry Peters
Keyword(s):  
Molecular Weight ◽  
River Water ◽  
Weight Fraction ◽  
Water Soluble ◽  
Organic P ◽  
P Fractions ◽  
P Concentration ◽  
Large Molecular Weight ◽  
Soluble P ◽  
Total P

This study examines the possibility that the proportions of different P fractions may vary among rivers, and hence, that the P supplied to lakes may differ in its availability for algae regardless of any similarities in the total P concentration of river waters. Surface water from eight streams and groundwater was collected at roughly monthly intervals from June 1975 to September 1976 and analyzed to determine the concentrations of P fractions and the interrelations between these forms and orthophosphate. Despite differences in total P concentration, (18–64 μg/L) the proportions of P in different fractions were relatively constant seasonally and geographically. Soluble P formed about one third and PO4 < 10% of the total P. These values were not greatly affected by urban drainage but both were increased in small headwater streams during periods of low water. Soluble P was divided into two roughly equal fractions by gel filtration: a large molecular weight fraction (> 5000 mol wt) which eluted at void volume and a small molecular weight fraction (< 400 mol wt) which eluted with 32P-PO4. This latter fraction also included some small organic phosphates. Soluble reactive phosphate consistently overestimated PO4. The exchange of P between PO4 and suspended material was slow in winter and more rapid in summer, although only rivers draining lakes, embayments, or bogs reached the very rapid values reported from lakes. As in lakes, soluble organic P entered into the short-term P dynamics of streams as indicated by the labeling of large molecular weight P during equilibration of river water with radioactive phosphate. This exchange shows that at least a portion of the soluble organic and particulate P is available to the plankton once the river water enters a lake. The uncertainty as to the size of this portion leads to uncertainty in predicting the impact of P loading on lakes. Key words: nutrient budget, P loading, orthophosphate, soluble organic P, drainage basins

Genome analysis of the coral bleaching pathogen Vibrio shiloi

2008 ◽  
Vol 190 (2) ◽  
pp. 185-194 ◽  
Author(s):  
Leah Reshef ◽  
Eliora Ron ◽  
Eugene Rosenberg
Keyword(s):  
Coral Bleaching ◽  
Genome Analysis ◽  
Vibrio Shiloi

Induction et repression de la synthèse de collagénase chez Acinetobacter sp.

1979 ◽  
Vol 25 (5) ◽  
pp. 611-617 ◽  
Author(s):  
Jean-Claude Monboisse ◽  
Jean Labadie ◽  
Philippe Gouet
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Catabolite Repression ◽  
Tertiary Structure ◽  
Protein Hydrolysate ◽  
The Other ◽  
Similar Composition ◽  
Acid Hydrolysate ◽  
Acinetobacter Sp ◽  
Casamino Acids

The synthesis of collagenase in Acinetobacter sp. was found to be inducible by denatured collagen and by its high molecular weight fragments. The presence in the inducer of part of the tertiary structure appear to be indispensable. On the other hand, an addition of Casamino acids, meat protein hydrolysate, or a mixture of amino acids with a similar composition to gelatin does not stimulate collagenase synthesis.Enzyme production was severely repressed in the early phase of growth by glucose, arabinose, and ribose, single amino acids, proline, hydroxyproline, alanine, glutamic acid, or casein acid hydrolysate. A mechanism of repression similar to catabolite repression was involved in the phenomenon caused by carbohydrates. However, the fact that cyclic adenosine 3′5′-mono-phosphate did not overcome the repression caused by amino acids or Casamino acids, in contrast to classical catabolite repression, suggests that these two forms of repression may be distinct. [Traduit par le journal]

Small and Middle Molecular Weight Solute Clearance in Nocturnal Intermittent Peritoneal Dialysis

1999 ◽  
Vol 19 (6) ◽  
pp. 534-539 ◽  
Author(s):  
Donald F. Brophy ◽  
Kevin M. Sowinski ◽  
Michael A. Kraus ◽  
Sharon M. Moe ◽  
James E. Klaunig ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Peritoneal Dialysis ◽  
Repeated Measures ◽  
Open Label ◽  
Small Molecular Weight ◽  
Single Dose Study ◽  
P Concentration ◽  
Wide Range ◽  
Stage Renal Disease ◽  
Concentration Ratios

Objectives To determine the dialysate-to-plasma (D/P) concentration ratios and peritoneal dialytic clearance (ClD) of substances with a wide range of molecular weights in subjects receiving a simulated nocturnal intermittent peritoneal dialysis (NIPD) session. Design Open-label single-dose study. Subjects Six end-stage renal disease patients undergoing peritoneal dialysis (PD). Setting Clinical research center of a university-affiliated hospital. Interventions Subjects received intravenous gentamicin and vancomycin on the first day of the study. Subjects received no PD until their return on the following day, when subjects underwent a simulated NIPD session utilizing four 2- to 2.5-L peritoneal dialysate dwells of 2 hours. Blood and dialysate samples were collected immediately before the session and after each dialysate dwell for determination of urea, creatinine, gentamicin, vancomycin, and β2-microglobulin (β2M) concentrations. Each solute's D/P concentration ratio and peritoneal ClD were calculated. Measurements and Main Results The (mean ±SD) 2-hour D/P concentration ratios were 0.78 ± 0.05 (urea), 0.49 ± 0.11 (creatinine), 0.38 ± 0.08 (gentamicin), 0.11 ± 0.06 (vancomycin), and 0.07 ± 0.03 (β2M). Peritoneal ClD values (mL/min of dialysis) were 19.0 ± 2.8 (urea), 12.1 ± 3.5 (creatinine), 8.4 ± 2.8 (gentamicin), 2.7 ± 1.5 (vancomycin), and 1.7 ± 0.8 (β2M). The D/P concentration ratios and peritoneal ClD values for urea, creatinine, and gentamicin were significantly different from vancomycin and β2M (repeated measures ANOVA, p < 0.05). β2-Micro-globulin peritoneal ClD was strongly related to gentamicin peritoneal ClD ( r = 0.96, p < 0.05). Conclusion Small molecular weight solutes have significantly greater D/P and peritoneal ClD than middle molecular weight solutes in NIPD. In NIPD, daily peritoneal ClD of β2M is lower than that reported in continuous ambulatory PD. NIPD also results in lower drug ClD than that reported in continuous ambulatory PD studies.

Sign in / Sign up

Export Citation Format

Share Document