Kurilosides A1, A2, C1, D,E and F—Triterpene Glycosides from the Far Eastern Sea Cucumber Thyonidium (= Duasmodactyla) kurilensis (Levin): Structures with Unusual Non-Holostane Aglycones and Cytotoxicities

Six new monosulfated triterpene tetra-, penta- and hexaosides, namely, the kurilosides A₁ (1), A₂ (2), C₁ (3), D (4), E (5) and F (6), as well as the known earlier kuriloside A (7), having unusual non-holostane aglycones without lactone, have been isolated from the sea cucumber Thyonidium (= Duasmodactyla) kurilensis (Levin) (Cucumariidae, Dendrochirotida), collected in the Sea of Okhotsk near Onekotan Island from a depth of 100 m. Structures of the glycosides were established by 2D NMR spectroscopy and HR-ESI mass spectrometry. Kurilosides of the groups A and E contain carbohydrate moieties with a rare architecture (a pentasaccharide branched by C(4) Xyl1), differing from each other in the second monosaccharide residue (quinovose or glucose, correspondingly); kurilosides of the group C are characterized by a unique tetrasaccharide branched by a C(4) Xyl1 sugar chain; and kurilosides of the groups D and F are hexaosides differing from each other in the presence of an O-methyl group in the fourth (terminal) sugar unit. All these glycosides contain a sulfate group at C-6 of the glucose residue attached to C-4 Xyl1 and the non-holostane aglycones have a 9(11) double bond and lack γ-lactone. The cytotoxic activities of compounds 1–7 against mouse neuroblastoma Neuro 2a, normal epithelial JB-6 cells and erythrocytes were studied. Kuriloside A₁ (1) was the most active compound in the series, demonstrating strong cytotoxicity against the erythrocytes and JB-6 cells and a moderate effect against Neuro 2a cells.     

Neuroprotective Metabolites from Vietnamese Marine Derived Fungi of Aspergillus and Penicillium Genera

Low molecular weight secondary metabolites of marine fungi Aspergillus flocculosus, Aspergillus terreus and Penicillium sp. from Van Phong and Nha Trang Bays (Vietnam) were studied and a number of polyketides, bis-indole quinones and terpenoids were isolated. The structures of the isolated compounds were determined by 1D and 2D NMR and HR-ESI-MS techniques. Stereochemistry of some compounds was established based on ECD data. A chemical structure of asterriquinone F (6) was thoroughly described for the first time. Anthraquinone (13) was firstly obtained from a natural source. Neuroprotective influences of the isolated compounds against 6-OHDA, paraquat and rotenone toxicity were investigated. 4-Hydroxyscytalone (1), 4-hydroxy-6-dehydroxyscytalone (2) and demethylcitreoviranol (3) have shown significant increasing of paraquat- and rotenone-treated Neuro-2a cell viability and anti-ROS activity.     

Novel technique for definite blastomere inhibition and distribution of maternal RNA in sterlet Acipenser ruthenus embryo

Fisheries Science - The cleavage pattern of a vertebrate’s embryo is either holoblastic (complete) or meroblastic (partial). Sturgeon and other basal bony fishes represent a transition of the...     

Comparative study on the embryonic development of three mud crabs Scylla spp.

Morphological changes in the embryos, egg size and development, incubation period and morphological structures of newly hatched zoea of three mud crab Scylla species were determined. The three species exhibited similar embryonic development composed of 10 stages. The mean egg diameter of Scylla serrata was significantly larger (P<0.05) at the prehatch stage. The mean egg diameters of Scylla tranquebarica and Scylla olivacea were similar (P>0.05). The incubation period was the longest in S. serrata and the shortest in S. olivacea. There was a positive relationship between egg size and larval size, as S. serrata exhibited the largest egg size and first zoea. However, no correlation was detected between egg size at prehatch and lengths of the morphological structures of the newly hatched zoea. The three species exhibited similar lengths of cephalic structures, but S. olivacea had significantly shorter (P<0.05) abdominal structures. The duration of spawning from ablation was the shortest in S. tranquebarica and the longest in S. olivacea. The study is relevant to aquaculture and fisheries management of Scylla species.     

Effect of temperature on growth and survival of maraena whitefish Coregonus maraena (Bloch 1779) larvae in controlled conditions

This 28‐day study investigated the effect of three rearing temperatures, 11, 15 and 19°C, on survival and growth of maraena whitefish fry in a recirculating aquaculture system. Three groups of larvae in three repetitions were reared in recirculating system. Each group comprised 200 larvae. Feeding level was fixed at 500–700 Artemia sp. metanauplii per fish per day. Larvae were fed fresh live brine shrimp at 10 ml/tank every 3 hr. Significantly higher body weight (p = 0.00), total length (p = 0.00), larval yield (p = 0.00) and condition factor (p = 0.00) were obtained at 19°C compared to 15 and 11°C, as well as at 15°C compared to 11°C. Significantly higher survival (p = 0.00) was observed in larvae reared at 11 and 15°C compare to 19°C and no significant differences were observed between 11°C compared to 15°C. No significant differences in size heterogeneity among treatments were found (p = 0.46). In larviculture, the optimal assessed temperature for growth of maraena whitefish was 19°C, with highest survival observed at 11°C, at the end of this 28 days trial. The findings in this study apply to the particular study location and may not be applicable more broadly.     

Dipole moments of highly vibrationally excited water

The intensity of water absorption in the region of the solar spectrum plays a dominant role in atmospheric energy balance and hence strongly influences climate. Significant controversy exists over how to model this absorption accurately. We report dipole moment measurements of highly vibrationally excited water, which provide stringent tests of intensities determined by other means. Our measurements and accompanying calculations suggest that the best currently available potential and dipole surfaces do not accurately model intensities in the optical spectrum of water.     

Effect of pH on Structural Changes in Perch Hemoglobin that Can Alter Redox Stability and Heme Affinity

pH can be manipulated to alter the oxidative stability of fish-based foods during storage. X-ray diffraction was used to investigate the ability of reduced pH to cause structural changes in fish hemoglobins that lead to enhanced oxidative degradation. Decreasing pH from 8.0 to 6.3 and 5.7 created a large channel for solvent entry into the heme crevice of perch hemoglobin beta chains. The proton-induced opening of this channel occurred between site CD3 and the heme-6-propionate. Solvent entry into the heme crevice can enhance metHb formation and hemin loss, processes that accelerate lipid oxidation. Reduced pH also decreased the distance between Ile at E11 in one of the alpha chains and the ligand above the heme iron atom. This sterically displaces O₂ and protonated O₂ which increases metHb formation. These studies demonstrate that pH reduction causes structural changes in perch hemoglobin which increase oxidative degradation of the heme pigment.     

The effect of timing of extended photoperiod on growth and maturity of brook trout (Salvelinus fontinalis)

The influence of timing of extended photoperiods on growth and maturity of brook trout was investigated in a 112‐day experiment. The fish with mean initial weight of ~192 g were reared under four light regimes: one control group with natural ambient photoperiod and three groups exposed to an 18L:6D regime initiated at days 1, 23 or 46 of the growth trial. Light‐emitting diodes, with intensity of 250–1000 lux, depending on the distance from the light source, were used for extending light periods. There was a positive effect of prolonged day length on fish growth (p < 0.05), and a delay in gonad development and sexual maturity. Significantly higher numbers of sexually mature fish were found among controls groups, regardless of sex. Survival rate was not affected by light regime. This study demonstrated that the short‐term expansion of the photo period delayed maturation and increased the growth rate of brook trout.     

Reproduction of chub, Leuciscus cephalus L., under controlled conditions

Research into artificial reproduction of chub was studied during three subsequent reproductive seasons. Chub reproduction was conducted in two different variations. In the first experiment different hormonal agents were given to fish, such as CPE, hCG, or an analogue of GnRH with dopamine antagonist (ovopel). In the second one, the optimum moment of applying of artificial reproduction was sought and the fish were only obtained an analogue of GnRH in different periods. The results obtained in two first seasons indicated that ovopel is the most effective agent for the artificial reproduction of chub. Consequently, it was decided that the fish would obtain only this agent in the final year of research. In last year (experiment II), chub spawners were taken to the hatchery under controlled conditions every few weeks from February to the beginning of June. Periodically, the maturity of oocytes was checked. As soon as the oocytes had achieved stage 2–3 of maturity, fish were obtained ovopel. It was noted that there was no problem with collecting semen. Obtaining oocytes was much more difficult. Most frequently, they were not obtained at all or obtained in very small amounts. It was also observed that the administration of hormones caused a very quick maturation of gonads and their over-maturation.