Inhibitory effects of the androgenic gland on ovarian development in the mud crab Scylla paramamosain

Isolation and characterization of androgenic hormone in decapod crustaceans depend on an effective bioassay of its action. In the present study, the effect of androgenic gland on ovarian development in the mud crab Scylla paramamosain was investigated with a view to develop a bioassay for androgenic hormone. Ovarian regression with degeneration of oocytes occurred in some female crabs implanted with androgenic gland in vivo. In vitro incubation of ovarian tissues at secondary vitellogenesis in extract of androgenic gland resulted in a significant decrease in amino acid uptake by the tissues. We propose that this inhibitory effect could be established as an effective bioassay for the isolation of androgenic hormone in the mud crab. (c) 2005 Published by Elsevier Inc.

Isolation and characterization of venom from nematocysts of jellyfish Rhopilema esculentum Kishinouye

The present work is the first report of the biochemical characterization of the venom from nematocysts of the jellyfish Rhopilema esculentum Kishinouye. The nematocysts were isolated by autolysis and centrifugation and separated by flow cytometry. Four types of nematocysts were identified: mastigophores, euryteles, and atrichous and holotrichous isorhiza. SDS-PAGE and amino acid analyses demonstrated that most of the proteins in the nematocyst extract were between 10 kDa and 40 kDa, and that glutamic acid was the main amino acid. A hemolytic activity assay showed that the activity of the nematocyst venom (RNV) was strongest in Tris-HCl buffer (50 mmol/L, pH 7.8, 5% glycerol, 0.5 mmol/L EDTA, 0.1 mol/L NaCl). The hemolytic activity was related to protein concentration and the HU50 against chicken erythrocytes was 0.91 A mu g/mL.

Comparative analysis of methods for concentrating venom from jellyfish Rhopilema esculentum Kishinouye

In this study, several methods were compared for the efficiency to concentrate venom from the tentacles of jellyfish Rhopilema esculentum Kishinouye. The results show that the methods using either freezing-dry or gel absorption to remove water to concentrate venom are not applicable due to the low concentration of the compounds dissolved. Although the recovery efficiency and the total venom obtained using the dialysis dehydration method are high, some proteins can be lost during the concentrating process. Comparing to the lyophilization method, ultrafiltration is a simple way to concentrate the compounds at high percentage but the hemolytic activities of the proteins obtained by ultrafiltration appear to be lower. Our results suggest that overall lyophilization is the best and recommended method to concentrate venom from the tentacles of jellyfish. It shows not only the high recovery efficiency for the venoms but high hemolytic activities as well.

Factors affecting the protease activity of venom from jellyfish Rhopilema esculentum Kishinouye

In this paper, the effects of some chemical and physical factors such as temperature, pH values, glycerol, and divalent metal cations on the protease activity of venom from jellyfish, Rhopilema esculentum Kishinouye, were assayed. Protease activity was dependent on temperature and pH values. Zn2+, Mg2+, and Mn2+ in sodium phosphate buffer (0.02 M, pH 8.0) could increase protease activity. Mn2+ had the best effects among the three metal cations and the effect was about 20 times of that of Zn2+ or Mg2+ and its maximal protease activity was 2.3 x 10(5) U/mL. EDTA could increase protease activity. PMSF had hardly affected protease activity. O-Phenanthroline and glycerol played an important part in inhibiting protease activity and their maximal inhibiting rates were 87.5% and 82.1%, respectively. (c) 2005 Elsevier Ltd. All rights reserved.

Insecticidal activity of proteinous venom from tentacle of jellyfish Rhopilema esculentum Kishinouye

Insecticidal activity of proteinous venom from tentacle of jellyfish Rhopilema esculentum Kishinouye was determined against three pest species, Stephanitis pyri Fabriciusa, Aphis medicaginis Koch, and Myzus persicae Sulzer. R. esculentum full proteinous venom had different insecticidal activity against S. pyri Fabriciusa, A. niedicaginis Koch, and M. persicae Sulzer. The 48 It LC50 values were 123.1, 581.6, and 716.3 mu g/mL, respectively. Of the three pests, R. esculentuin full proteinous venom had the most potent toxicity against S. pyri Fabriciusa, and the corrected mortality recorded at 48 It was 97.86%. So, S. pyri Fabriciusa could be a potential target pest of R. esculentum full proteinous venom. (c) 2005 Elsevier Ltd. All rights reserved.

Factors influencing hemolytic activity of venom from the jellyfish Rhopilema esculentum Kishinouye

In this study, hemolytic activity of venom from the jellyfish Rhopilema esculentum Kishinouye and some factors affecting it were assayed. The HU50 of R. esculentum full venom (RFV) against chicken erythrocytes was 3.40 mu g/ml and a Hill coefficient value was 1.73 suggesting at least two molecules participated in hemolytic activity. The hemolytic activity of RFV was affected by some chemical and physical factors such as divalent cations, EDTA, (NH4)(2)SO4, pH and temperature. In the presence of Mg2+, Cu2+, Zn2+, Fe2+, Ca2+ ( >= 2 mM), Mn2+ (>= 1 mM), EDTA (>= 2 mM) and (NH4)(2)SO4, the hemolytic activity of RFV was reduced. RFV had strong hemolytic activity at the pH 6-10 and the hemolytic ratios were 0.95-1.19. Hemolytic activity was temperature-sensitive and when RFV was pre-incubated at temperatures over 40 degrees C, it was sharply reduced. (c) 2007 Elsevier Ltd. All rights reserved.

Partial characterization of the hemolytic activity of the nematocyst venom from the jellyfish Cyanea nozakii Kishinouye

Using a recently developed technique to extract jellyfish venom from nematocysts, the present study investigated the hemolytic activity of Cyanea nozakii Kishinouye nematocyst venom on chicken erythrocytes. Venom extract caused a significant concentration-dependent hemolytic effect. The extract could retain its activity at -80 degrees C but was unstable when kept at 4 degrees C and -20 degrees C for 2 days. The hemolytic activity was inhibited by heating within the range of 37-100 degrees C. The extract was active over a pH range of 5.0-8.63 and the pH optima for the extract was 7.8. Incubation of the venom with sphingomyelin specially inhibited hemolytic activity by up to 70%. Cu2+ and Mn2+ greatly reduced the hemolytic activity while Mg2+, Sr2+ and Ba2+ produced a relatively low inhibiting effect on the hemolytic activity. Treatment with Ca2+ induced a concentration-dependent increase in the hemolytic activity. In the presence of 5 mM EDTA, all the hemolytic activity was lost, however, the venom containing 1.5 mM EDTA was stable in the long-term storage. PLA(2) activity was also found in the nematocyst venom of C. nozakii. These characteristics provide us a fundamental knowledge in the C. nozakii nematocyst venom which would benefit future research. (C) 2010 Published by Elsevier Ltd.