TBT effects on the development of intersex (ovotestis) in female fresh water prawn Macrobrachium rosenbergii.

The impact of tributyltin (TBT) on the female gonad and the endocrine system in Macrobrachium rosenbergii was studied. Prawns were exposed to environmentally realistic concentrations of 10, 100, and 1000 ng/L of TBT for 6 months. Dose dependent effects were noticed in TBT exposed prawns. At 1000 ng/L TBT caused ovotestis formation (formation of male germ cells in ovary). Presence immature oocytes, fusion of developing oocytes, increase in interstitial connective tissues, and its modification into tubular like structure and abundance of spermatogonia in the ovary of TBT treated prawns. The control prawn ovary showed normal architecture of cellular organelles such as mature oocytes with type 2 yolk globules, lipid droplets, normal appearance of yolk envelop, and uniformly arranged microvilli. On the other hand, type 1 yolk globules, reduced size of microvilli, spermatogonial cells in ovary, spermatogonia with centrally located nucleus, and chromatin distribution throughout the nucleoplasm were present in the TBT treated group. Immunofluorescence staining indicated a reduction in vitellin content in ovary of TBT treated prawn. Moreover, TBT had inhibited the vitellogenesis by causing hormonal imbalance in M. rosenbergii. Thus, the present investigation demonstrates that TBT substantially affects sexual differentiation and gonadal development in M. rosenbergii.

Antioxidant activity of seagrasses of the Mandapam coast, India.

CONTEXT: In the search for new sources of safe and inexpensive antioxidants, the leaves of eight species of seagrasses were screened for antioxidant properties. OBJECTIVE: Most of the seagrasses were evaluated for the first time for their antioxidant activities. MATERIALS AND METHODS: Total phenolic content and in vitro antioxidant activity using, 2,2-diphenyl-1-picrylhydrozyl (DPPH) radical scavenging capacity and FRAP assay. RESULTS: The leaves of Halophila stipulacea (Forssk.) Aschers showed high levels of phenols (1.398 ± 0.055 mg GAE/g) and high reducing power (46.289 ± 1.002) in terms of mg GAE/g. Similarly, H. pinifolia exhibited high total antioxidant activity (132.38, 75.027 mg AscAE/g) and a high percentage of DPPH radical scavenging activity (68.14%). The TAA and FRAP assays showed positive and significantly high correlation (R2 = 0.646). The total phenolic content in the seagrass extracts showed a better correlation with reducing power (R2 = 0.597) than the DPPH radical-scavenging activity (R2 = 0.495). DISCUSSION AND CONCLUSIONS: The antioxidant capacities of the seagrasses showed potential rich sources of natural antioxidants. Further studies are necessary for isolation and characterization of the active antioxidant compounds, which can be used to treat various oxidative stress-related diseases.

Effect of Temperature on the Growth of Marine Diatom, Chaetoceros simplex (Ostenfeld, 1901) with Different Nitrate：Silicate Concentrations

Objective: To study the combined effect of temperature, nitrate and silicate on the growth, of the marine diatom, Chaetoceros simplex (Ostenfeld, 1901). Methods: Samples were analysed for the effect of temperature, nitrate and silicate on the growth, chlorophyll ‘a’, protein and carbohydrate contents. Totally fifteen experiments were conducted for 12 days under three different temperature (20, 25 and 29 ℃), 68 μmol photon m-2 s-1 light intensity and at five concentrations of nitrate: silicate propositions (882 μM [NO3-] -106 μM [SiO32-], 1323 μM [NO3] -159 μM [SiO32-], 1764 μM [NO3-] -212 μM [SiO32-], 2205 μM [NO3-]-265 μM [SiO32-] and 2646 μM [NO3-]-318 μM [SiO32-] respectively). Result:The maximum cell density reached 23.5 × 105 cells ml-1 with 1764 μM [NO3-] and 212 μM [SiO32-] concentrations at 29 ℃, in 10th day of culture. The high chlorophyll ‘a’ content of 1.57 ± 0.05 pg/cell at 20℃ and 2205 μM [NO3-]-265 μM [SiO32-]. The high protein content of 4.48 ± 0.17 pg/cell was found in 2205 μM [NO3-]-265 μM [SiO32-] at 25℃. The high carbohydrate contents of 0.78 ± 0.03 pg/cell were found in 1764 μM [NO3-]-212 μM [SiO32-] at the temperature of 25oC. Conclusions: The growth rate was directly proportional to nutrient concentration and temperature whereas chlorophyll ‘a’ and biochemical concentration was directly proportional to nutrient concentration. Based on the present results, furture work on growth optimization with the other physical and nutritional factors will yield noteworthy information on the mass cultivation of C. simplex for aquaculture purposes.

In vitro antioxidant activities of selected seaweeds from Southeast coast of India

OBJECTIVE@#In vitro antioxidant activities of three selected Indian seaweeds viz., Halimeda tuna (H. tuna), Turbinaria conoides (T. conoides) and Gracilaria foliifera (G. foliifera) were evaluated.@*METHODS@#Total antioxidant activity, total phenolic content, and reducing power of crude methanol and diethyl ether extracts were determined.@*RESULTS@#Total phenolic content and total antioxidant activity were higher (1.231±0.173 mg GAE/g, 1.675± 0.361 mg GAE/g) in T. conoides respectively. Reducing power of crude methanol extract increased with concentrations of the extract. The Fourier transform-infra red spectrum analysis revealed the presence of polyphenolic signals. The seaweed extracts displayed moderate antioxidant activity compared to gallic acid standard.@*CONCLUSIONS@#The seaweeds could be considered for curing diseases from oxidative deteriorations.