The modulating effect of vitellogenin on the synthesis of 17β-estradiol by rainbow trout (Oncorhynchus mykiss) ovary

In vivo induction of vitellogenin (VTG) in response to the administration of 17-estradiol (E₂) was achieved and the protein was isolated by gel filtration column chromatography of plasma samples. Adult female trout were injected with the vitellogenic fraction every ten days from July to November and levels were measured by RIA from September to December. The results showed a significant decrease (p<0.01) in plasma E₂ levels in injected females compared with the controls. In December, after finishing the treatment, the plasma E₂ concentration increased, in injected females to reach a level similar to that of control females at vitellogenesis. The in vitro study showed that in early vitellogenic oocyte (from September) the presence of the vitellogenic fraction in the incubation medium causes a significant decrease (p<0.01) in the synthesis of E₂ by the oocytes. These data suggest that the concentration of the VTG into the oocyte can alter VTG production by the liver, moderating the production of E₂ by the ovary.     

Identification of enzyme genes in the liver of the Bleeker’s squid Loligo bleekeri by expressed sequence tag analysis

Expressed sequence tag (EST) analyses were performed with the aim of identifying enzyme genes in the liver of the Bleeker’s squid Loligo bleekeri. Of the 768 ESTs identified and sequenced, 669 were grouped into 324 clusters. Of these clusters, 123 comprising 245 ESTs were found to be homologous to genes reported to date. Among these, 43 clusters were annotated as enzymes according to the Enzyme Commission (EC) numbering system. Two EC groups, oxidoreductases and hydrolases, possessed a large number of ESTs. A cluster homologous to the glutathione peroxidase, an enzyme in the oxidoreductase group, contained 16 ESTs, which accounted for 2.4% of the total ESTs sequenced. There are three serine proteases, three cathepsins, two triacylgricerol lipases, and two chitinases among the clusters homologous to the enzymes in the hydrolase group. Since the squid liver functions in the digestive process, these enzymes would be involved in food digestion. Our data provide information on the various types of enzymes expressed in the squid liver and may provide a useful basis for further characterization of these enzymes.     

Effect of enrofloxacin and emodin on heat-shock proteins’ expression in hepatic cells of grass carp (Ctenopharyngodon idellus)

The aim of the present study was to compare the expression pattern of heat-shock protein 60 (HSP60), 70 (HSP70), and 90 (HSP90) mRNA in hepatic cells of grass carp exposed to enrofloxacin and emodin concentrations. The expression pattern of different genes encoding heat-shock proteins in hepatic cells of grass carp was exposed to graded levels of enrofloxacin (12.5, 25, 50, 100, and 200 μg/ml) or emodin (0.04, 0.2, 1, 5, and 25 μg/ml) for 24 h and were investigated by real-time quantitative PCR. When cells were exposed to up 50 μg/ml enrofloxacin, both HSP60 and HSP70 mRNA levels firstly were increased and thereafter significantly dropped at high concentrations (P < 0.05), while HSP90 decreased with increasing enrofloxacin concentration. Besides, HSP60 and HSP70 expressions were significantly inhibited in the high-concentration groups. In addition, the HSP90 mRNA levels in the treatment exposed to 100 and 200 μg/ml enrofloxacin were significantly lower than those of the control group (P < 0.05). Furthermore, when cells were exposed to graded levels of emodin, HSPs (HSP60, 70, and 90) mRNA levels significantly increased in the groups exposed to 5 and 25 μg/ml of emodin. The different expression pattern of HSPs implied that enrofloxacin could inhibit the expression levels of HSPs, while optimal level of emodin could trigger higher expression levels of HSPs in hepatic cell of grass carp to protect against further damage.     

The potential for aquaculture of the bearded horse mussel (Modiolus barbatus) and Noah’s Ark shell (Arca noae) in southern Croatia

To assess the potential of the bearded horse mussel (Modiolus barbatus) and Noah’s Ark shell (Arca noae) for aquaculture in southern Croatia, we analyzed their survival and growth rates under two experimental conditions—suspended culture and on-bottom culture. Furthermore, we investigated feeding on zooplankton by these two species in suspended culture conditions and compared them with previously published results of their feeding on zooplankton in the natural benthic environment. Experimental studies were conducted in Mali Ston Bay (Adriatic Sea) from December 2009 to December 2010. Differences were observed in terms of survival of tagged M. barbatus and A. noae—specimens of M. barbatus exhibited much better survival rates both in suspended culture and in on-bottom cages than did A. noae. Growth of A. noae under both culture conditions was essentially negligible, while M. barbatus grew several times faster in suspended culture than on the bottom. Values for the growth constant K and L _inf for M. barbatus in suspended culture were 0.45 year^?1 and 55.9 mm, while corresponding values for on-bottom culture were 0.09 year^?1 and 58.6 mm, respectively. Zooplankters were present in the stomachs of 86.3 % of M. barbatus and 86.4 % of A. noae. Most abundant taxa were bivalve larvae followed by tintinnids, copepods, unidentified eggs and gastropod larvae. In conclusion, this study clearly shows that M. barbatus is a promising candidate for suspended aquaculture in southern Croatia.     

Antiparasitic efficacy of dietary administration of trichlorfon (Masoten®) in the control of Neoechinorhynchus buttnerae (Neochinorhynchidae) in Colossoma macropomum (Serrasalmidae)

Aquaculture International - This study investigated the efficacy of trichlorfon against Neoechinorhynchus buttnerae, as well as its palatability, residue analysis, and the blood parameters of...     

French consumers’ marginal willingness to pay for the pairing of Japan’s fall chum salmon and rice wine (sake)

The pairing of foods and beverages (especially alcoholic beverages) is an effective marketing approach to promote the value of Japanese gastronomy to overseas consumers because it requires little additional cost. In this study, the research target was French consumers, and the evaluation targets were grilled fall-season wild chum salmon from Japan (mainly from Hokkaido) and Japanese rice wine (sake). The difference in the consumers’ willingness to pay (WTP) was evaluated using the contingent valuation method. In addition, we analyzed the determinants by applying Tobit regression. Our results revealed that there was a higher WTP when Japan’s (Hokkaido’s) grilled fall salmon and sake were presented as a set than when they were presented individually. The geographical identity of the origin of food and beverages can engender a positive premium to consumers through the synergistic effect of the origin of the brand.

     

Recruitment of common sardine (Strangomera bentincki) and anchovy (Engraulis ringens) off central-south Chile in the 1990s and the impact of the 1997–1998 El Niño

The recruitment of Strangomera bentincki (common sardine) and Engraulis ringens (anchovy) and the relationships with oceanographic conditions in the upwelling ecosystem of central-south Chile were investigated from 1990 to 1998, with emphasis on the 1997–1998 El Niño. Time series of recruitment, biomass, local sea surface temperature, and a coastal upwelling index were used to explore relationships during the spawning (July–August) and pre-recruitment (August–December) periods. The 1997–1998 El Niño caused physical changes in the small pelagic fish habitat off central-south Chile. Anomalous sea surface temperatures (SST) and upwelling indexes began to be detected from May 1997 and persisted into 1998. Recruitment of common sardine showed significantly negative relationship with SST anomalies during the pre-recruitment period, as well as with the upwelling index during the peak of spawning. However, the recruitment of anchovy did not seem to be affected by the environmental changes observed in the 1990s. Instead, the recruitment rate of anchovy showed negative relationship with the recruitment rate of common sardine. We conclude that the conditions of the 1997–1998 El Niño off central-south Chile affected the survival of common sardine offspring, and that the recruitment success of anchovy could be determined by less-abundant cohorts of common sardine through a biological mechanism of interaction.     

The dynamics of in vitro 17 β-estradiol secretion by isolated ovarian follicles of the rainbow trout (Oncorhynchus mykiss)

This study investigated the effects of human chorionic gonadotropin (hCG), 17-hydroxyprogesterone (17P) and testosterone (T) on the in vitro production of 17-estradiol (E₂) by isolated ovarian follicles of the rainbow trout (Oncorhynchus mykiss). 17P at 100 ng ml^-1, and hCG at 100 IU ml^-1 stimulated E₂ production relative to controls, whereas lower doses were ineffective. T was the most effective in stimulating E₂ production, followed by 17P and hCG respectively. The timecourse of E₂ production was investigated for both static culture, and incubations with media replacement, with follicles being exposed to hormone treatment for 30 min, 1 or 3 h, or constantly. E₂ production was observed after 30 min, 3 and 3-6 h in response to T, 17P and hCG respectively. Under static culture, E₂ levels reached maximal levels in 6 h. Longer incubations resulted in further metabolism of E₂ to E₂-glucuronide, which resulted in the blurring of treatment effects after 18 h. Incubations with media replacement resulted in higher E₂ production than in static culture. The results indicate that a 6 h incubation period is sufficient to produce significant increases in E₂ production in response to hCG, 17P and T, and that incubations longer than 12 h result in losses E₂ from the incubation media. These findings have implications for the validity of using static cultures to examine the effects of hormone treatment on the activity of steroid converting enzymes in vitro.     

Immunomodulatory effect of dietary brewer’s yeast extract in Sander lucioperca juveniles against the challenge of Aeromonas salmonicida

The present study examined the influence of extract obtained from the interior of cells of yeast, Saccharomyces cerevisiae (NuPro^®), on the growth, proximate composition, nonspecific cellular and humoral defense mechanisms, and protection against furunculosis in pikeperch (Sander lucioperca). It was noted that eight weeks of supplementation with 40 g of NuPro^® kg^?1 feed (containing approximately 0.22 % exogenic nucleotides) enhanced pikeperch innate immunity. Increased serum lysozyme activity and total Ig levels (P < 0.05) were noted in the NuPro^®-fed group, which indicated the activation of nonspecific humoral defense mechanisms. Brewer’s yeast extract also stimulated nonspecific cellular defense mechanisms as indicated by the increased metabolic activity of blood phagocytes and pronephric macrophages, and in the increased intracellular killing activity of phagocytes and proliferative responses of T and B lymphocytes (P < 0.05). Additionally, reduced mortality (15 %) after the in vivo challenge with pathogenic Aeromonas salmonicida suggested that NuPro^® activated nonspecific protection against furunculosis in pikeperch. The experimental feed did not have a significant impact on the growth or proximate composition of the fish (P > 0.05).     

Effects of 17β-estradiol injection on the reproductive efficiency of freshwater crayfish,Astacus leptodactylus (Eschscholtz, 1823)

The effects of 17β-estradiol injection (10^?7mol/crayfish) in adult female Astacus leptodactylus on the reproductive efficiency (i.e., pleopodal egg and stage 1 juvenile numbers) were investigated. In addition, hepatosomatic index, gonodosomatic index, and 17β-estradiol (E2) levels of crayfish ovary, hepatopancreas, and heamolymph before and after injections were also determined. Results showed that E2 injection to females enhances the reproductive efficiency of A.leptodctylus. E2 injection significantly increased pleopodal egg and stage 1 juvenile numbers, GSI, HSI, and concentrations of E2 in heamolymph, ovary, and hepatopancreas. However, E2 injection did not accelerate time of mating and proportion of pleopodal egg-berried females at the first week of reproduction season in this species. This study highlights that to improve the reproductive efficiency of A.leptodctylus by using hormones to regulate the ovarian cycle, E2 should be used at least 1.5 months before the commencement of the breeding season.     

Recovery of Proteins from Squid By-Products with Enzymatic Hydrolysis and Increasing the Hydrolysate’s Bioactivity by Maillard Reaction

ABSTRACT

The Maillard reaction is an effective method for enhancing the activity of bioactive peptides. In this study, squid by-product hydrolytic peptides (SPHPs) were obtained. The effects of the Maillard reaction on the antioxidant and antibacterial activities of the SPHPs were explored. The results showed most of the peptides in the < 500 Da fraction of SPHPs reacted with D-arabinose to form the 500–1000 Da fraction (89.60%). The Maillard reaction products (MRPs) possessed more potent antioxidant activities, including free radical scavenging activity, ferrous chelating capacity, and reducing power, than the SPHPs. Although both the SPHPs and MRPs had broad-spectrum antibiotic activities and could inhibit the growth of both gram-negative and gram-positive bacteria, the antibacterial activities of the MRPs were higher than those of the SPHPs. Furthermore, the efficacy of the MRPs lasted significantly longer than that of ampicillin and could last for more than 30 days. In addition, both the SPHPs and MRPs had good functional properties and many potential applications. The results suggested that the Maillard reaction has potential to be used to improve the activities and physicochemical properties of bioactive peptides.     

Smoltification induced by a ‘skeleton’ photoperiod in underyearling coho salmon (Oncorhynchus kisutch)

Underyearling coho salmon fry were subjected to three initial photoperiod treatments (6L18D, 10L14D, 14L10D) for two months and subsequently to three final treatments (16L8D, 9L6D1L8D, 10L14D) in a factorial design. Growth rates and seawater adaptability were monitored regularly. The groups that were exposed initially to 6L18D or 10L14D and then to 16L8D grew faster and had lower plasma sodium ion levels after seawater challenge tests than any of the other groups. Fish which were initially exposed to 6 L or 10 L daylength and then to a 9L6D1L8D skeleton photoperiod, showed a slightly lower growth rate and seawater adaptability than those given the corresponding complete 16L8D photoperiod. However fish maintained on skeleton photoperiods had significantly greater growth rates and seawater adaptability than those kept on the 10L14D photoperiod. This indicates that it is not the accumulated number of hours of exposure to light that initiates smolting, but rather the time during the day when light is experienced. Fish exposed initially to 14L10D showed little or no response to subsequent changes in photoperiod, suggesting that responsiveness to inductive photoperiods depends on the initial photoperiod treatment.     

Effects of Culinary Methods on Nutritional Characteristics of the Edible Shellfish Noah’s Ark (Arca noae L., 1758) from Tunisian Coasts

Bivalves are known for their high nutritional value and are considered a healthy food for human consumption. The effect of different cooking methods (steaming, boiling, grilling, and frying) on proximate and fatty acid composition of Arca noae (Bivalvia: Linnaeus 1758) were determined. The comparison of raw and cooked Ark shell showed that the cooking had considerable effects on the nutritional quality of this species. Significant changes in moisture (%), protein (mg/g of flesh), total lipid (mg/g of flesh), and fatty acid composition (mg/g dry weight) were observed after cooking as compared to fresh Ark shell (p < 0.05). However, the analysis of malondialdehyde (MDA) and peroxide value (PV) showed that all cooking treatments led to lipid oxidation. Steaming, boiling, and grilling were found to be a suitable and healthier cooking processes for A. noae, since they conserve the amount of n-3 PUFA better as compared to frying.     

Suitability and optimization of FAO’s small-scale aquaponics systems for joint production of lettuce (Lactuca sativa) and fish (Carassius auratus)

Aquaponics is a developing technique that combines the simultaneous production of plants (hydroponics) and fish (aquaculture). With it, the use of resources (i.e., water, nutrients, land) is reduced whilst at the same time minimising residues’ discharge to the environment. Among its benefits, it allows the production of healthy vegetables and fish in reduced spaces by means of small-scale systems. In this work, three of them based on FAO models with different hydroponic subsystems (nutrient film technique -NFT-, floating raft, and vertical felt) are tested to produce lettuce (Lactuca sativa) and goldfish (Carassius auratus). Water parameters as well as the growth of plants and fishes were monitored in two different production cycles. The hydroponic subsystem that outperformed the best was the NFT, both in terms of crop production and water consumption. All systems showed similar results in fish production. Further research is needed to corroborate the outputs obtained when using other combinations of plants and fishes. Small-scale aquaponic systems are particularly interesting for self-production and even more so in urban environments with reduced available space.     

Assessing the diet of the endangered Beale’s eyed turtle (Sacalia bealei) using faecal content and stable isotope analyses: Implications for conservation

1. Turtles from Asia are on the brink of extinction with 53% of species considered endangered or critically endangered. Unfortunately, the ecology of many threatened species remains largely unknown.
2. In this study, the diet of the endangered Beale’s eyed turtle (Sacalia bealei) was investigated using two methods, visual faecal content analysis and stable isotope analysis.
3. Results from both methods indicated that S. bealei is highly reliant on riparian resources, especially fruits and terrestrial insects. Stable isotope data indicated that terrestrial resources made up around half (47–53%) of all assimilated food resources. These findings suggest that S. bealei facilitates energy flow from riparian forests to stream ecosystems. Moreover, S. bealei is likely to be a seed disperser for riparian plants.
4. This study represents the first application of stable isotope methods to examine the diet of Asian freshwater turtles and their resource use. We stress the importance of similar studies to improve our understanding of remnant turtle populations before they disappear as a result of human activities.

     

Habitat and prey selection of common minke,sei, and Bryde’s whales in mesoscale during summer in the subarctic and transition regions of the western North Pacific

This study represents the first quantitative analysis of the characteristics of the distribution areas and stomach contents of common minke whale Balaenoptera acutorostrata, sei whale B. borealis, and Bryde’s whale B. edeni in relation to oceanographic and prey environments in mid summer in the western North Pacific. Common minke whales were distributed within subarctic regions and the northernmost region of the transitional domain, coinciding with the main habitat of their preferred prey, Pacific saury Cololabis saira. Sei whales were mainly found in the northernmost part of the transition zone and showed prey preference for Japanese anchovy Engraulis japonica, which was significantly more abundant in the main distribution area of the whale than in its adjacent areas. “Hot spots” of Bryde’s whales were found in several regions of the transition zone between the subarctic boundary and the Kuroshio front. This whale species preferred Japanese anchovy as prey, for which the distribution density was significantly higher in the main distribution area of the whale than in the adjacent areas. These results indicate that the summer distributions of Pacific saury and Japanese anchovy greatly influence the distributions of these whale species, suggesting that the whales’ habitat selection is closely related to their prey selection.