AFLP markers distinguishing an early mutant of Flame Seedless grape

Molecular markers have been frequently used to differentiate grape species and cultivars. There are fewer cases where molecular markers have been used to differentiate grape clones within a cultivar, or for the demarcation of somatic mutants from parental clones. This study reports the first successful utility of AFLPs for the differentiation of somatic mutants from their parental grapevine line, and discusses the potential for similar AFLP applications. The somatic mutant analysed demonstrates earlier budburst characteristics than the Flame Seedless line from which is arose. Analysis of 64 AFLP primer combinations in silver stained polyacrylamide produced in excess of 3000 markers in Vitis vinifera, and provided two markers which differentiated the somatic mutant, from its parental line. One marker was 440 bpin length and was produced with primer combinationEcoR1-AT and Mse1-CTT. The second marker was 340 bp in length and generated with primer combination EcoR1-TC and Mse1-CAC. This revised version was published online in July 2006 with corrections to the Cover Date.     

Induction of precocious maturation in masculinized Atlantic salmon by treatment with sustained-release LHRHa and testosterone

The effect of treating immature, masculinized, Atlantic salmon, Salmo salar, with testosterone or [Des-Gly10] D-Ala6-LHRH ethylamide (LHRHa), either alone or in combination, over an 81 day period was evaluated as a method for accelerating maturation. Two sustained-release LHRHa implants were compared: ethylene vinyl acetate copolymer (EVAC) and silicone elastomer. Animals primed with testosterone did not express advanced spermatogenesis when compared against control salmon (p > 0.05). However, fish primed with testosterone, followed by sham, LHRHa EVAC, or LHRHa silicone elastomer implants expressed increased (p < 0.05) gonadosomatic index (GSI) when compared with values derived from day 0 of the study. Neither spermatogenesis nor GSI were affected when salmon were treated with LHRHa alone, irrespective of the vehicle employed. In contrast, spermatogenesis was significantly (p < 0.05) advanced in testosterone-treated fish, which were administered LHRHa by EVAC, when compared with groups that received individual treatment only. © Rapid Science Ltd. 1998     

Fatty Acid Profiles and Lipid Oxidation Status of Sun Dried,Deep Fried,and Smoked Sardine (Rastrineobola argentea) from Lake Victoria,Tanzania

Freshwater fishes contain long chain omega-3 and omega-6 polyunsaturated fatty acids (PUFAs) of highest nutritional value. PUFAs in fish are susceptible to oxidative damage during processing and subsequent storage. Sardines (Rastrineobola argentea) are an important fish species of Lake Victoria, constituting 72.3% of the total landings by weight on the Tanzanian side of the lake. Fatty acid profiles and lipid oxidation status of sun-dried, deep-fried, and smoked sardines were investigated. Lipid oxidation was assessed by peroxide value, thiobarbituric acid reactive substances (TBARS), and free fatty acids. Fatty acids were analyzed by gas chromatography with flame ionization detector. The three omega-3 PUFAs: docosahexaenoic acid (C22:6n-3), docosapentaenoic acid (C22:5n-3), and eicosapentaenoic acid (C20: 5n-3) contributed 57–60, 63, and 38% of PUFAs in sun-dried, smoked, and deep-fried sardines, respectively. Lipid oxidation reactions were more pronounced in sardines dried on sand and rocks, with TBARS values 97.87 and 84.18 µmolMDA/kg, respectively. The polyene index was significantly lower (p < 0.05) in deep-fried sardines, indicating lower retention of PUFAs in the product. Lake Victoria sardines are a rich source of omega-3 PUFAs. PUFAs in sun-dried sardines are prone to oxidative damage. Smoking resulted in relatively higher retention of omega-3 fatty acids in products.     

Optimum protein‐to‐lipid ratio requirement of the juvenile shi drum (Umbrina cirrosa) as estimated by nutritional and histological parameters

The shi drum is an emerging Mediterranean aquaculture species that has gained increasing interest in recent years. However, the nutrient requirements of this species remain to be determined to optimize its culture. The present study evaluated the effects of dietary protein (470g/kg or 520g/kg) to lipid ratios (100g/kg, 150 or 200g/kg) on the growth performance, nutrient utilization and tissue morphology of the shi drum (7 g average initial weight). Dietary protein levels positively correlated with weight gain, showing high protein demands (>470g/kg) for this species. Nonetheless, dietary lipid levels negatively affected growth rate, feed intake and efficiency, and protein utilization, suggesting that this macronutrient cannot be efficiently utilized in high concentrations (>100g/kg). Histological evaluation revealed fat accumulation within the hepatocytes and the enterocytes with increasing dietary lipid levels, starting from 150g/kg lipid inclusion. Overall, our results confirm the high dietary protein requirements of the shi drum (>470g/kg for fish of 7 g initial weight) and suggest that lipid levels should not exceed 100g/kg of inclusion in the diets as this species has a low tolerance to this macronutrient.     

Mitigating sea turtle by-catch in coastal passive net fisheries

There is growing evidence that small-scale, coastal, passive net fisheries may be the largest single threat to some sea turtle populations. We review assessments of turtle interactions in these fisheries, and experiments on gear-technology approaches (modifying gear designs, materials and fishing methods) to mitigate turtle by-catch, available from a small number of studies and fisheries. Additional assessments are needed to improve the limited understanding of the relative degree of risk coastal net fisheries pose to turtle populations, to prioritize limited conservation resources and identify suitable mitigation opportunities. Whether gear technology provides effective and commercially viable solutions, alone or in combination with other approaches, is not well-understood. Fishery-specific assessments and trials are needed, as differences between fisheries, including in gear designs; turtle and target species, sizes and abundance; socioeconomic context; and practicality affect efficacy and suitability of by-catch mitigation methods. Promising gear-technology approaches for gillnets and trammel nets include: increasing gear visibility to turtles but not target species, through illumination and line materials; reducing net vertical height; increasing tiedown length or eliminating tiedowns; incorporating shark-shaped silhouettes; and modifying float characteristics, the number of floats or eliminating floats. Promising gear-technology approaches for pound nets and other trap gear include: replacing mesh with ropes in the upper portion of leaders; incorporating a turtle releasing device into traps; modifying the shape of the trap roof to direct turtles towards the location of an escapement device; using an open trap; and incorporating a device to prevent sea turtle entrance into traps.     

Consequences of fishing lure retention on the behaviour and physiology of free-swimming smallmouth bass during the reproductive period

When break-offs occur during recreational angling, lures may be retained by the fish. To date, there have been few studies on the consequences of lure retention on sportfish. This study evaluated how the retention of three different types of lures (i.e., crankbait, jig and plastic worm—all with barbed hooks) influenced the behaviour, physiology and reproductive success of nesting, male smallmouth bass (Micropterus dolomieu) relative to controls released after lure removal. Bass were angled from their nests and subjected to a simulated lure retention scenario in which one of three lure types was placed in the upper middle jaw. Males were subsequently released and their behaviour (time to return to nest, parental care behaviour) was monitored. Immediately after release, fish with retained lures exhibited altered behaviour relative to control fish, attempting to expel the lure. However, these differences in behaviour were no longer apparent after 24 h even for those fish that retained the lures. Rates of nest abandonment did not differ between treatment and control fish in the short term. Fish were rarely able to liberate themselves from the retained lure in the several days post-treatment. Physiological sampling conducted on jig treatment fish and angled controls revealed elevated blood glucose concentrations in fish that had retained lures for 24 h, while lactate concentrations and hematocrit did not differ between treatment and control fish. These results demonstrate that lure retention in the short-term influences both the behaviour and physiology of smallmouth bass. Given that lures were generally retained throughout the study period, there may be merit in anglers using barbless hooks that may be more readily shed by fish that break the line, reducing the welfare impacts associated with lure break-offs on wild fish. Additional studies are needed to understand the longer term consequences of lure retention in free-swimming fish.