Polyunsaturated fatty acids modulate the properties of the sex steroid binding protein in goldfish

This study examines the effects of nonesterified fatty acids on the properties of the sex steroid binding protein (SSBP) in the plasma of goldfish (Carassius auratus). Scatchard analysis revealed a single class of high affinity (Kd 1.89±0.20 nM), low capacity (Bmax 302±17 nM) binding sites for [3H]17-estradiol in female goldfish plasma. The SSBP bound 17-estradiol and testosterone with similar affinity but had much lower affinity for estriol, 17,20-dihydroxy-4-pregnen-3-one and cholesterol. Nonesterified fatty acids inhibit the binding of [3H]17-estradiol to the SSBP as a function of dose, degree of unsaturation and fatty acid chain length. Polyunsaturated fatty acids (PUFAs) such as arachidonic acid (C20:4), eicosapentaenoic acid (C20:5) and docosahexaenoic acid (C22:6) strongly inhibit the binding of [3H]17-estradiol to the SSBP. By comparison, saturated fatty acids such as heptadecanoic acid (C17:0), palmitic acid (C16:0) and stearic acid (C18:0) were without effect. Scatchard analysis and Lineweaver-Burk plots showed that PUFAs act through a competitive mechanism whereby they reduce the affinity but have no effect on the binding capacity of the SSBP. Collectively, these studies suggest that in addition to their roles as metabolic energy sources and as precursors to eicosanoids, PUFAs can be potent modulators of steroid hormone interactions with the SSBP in goldfish plasma.     

Analysis of bacterial community and bacterial nutritional enzyme activity associated with the digestive tract of wild Chilean octopus (Octopus mimus Gould, 1852)

Information on the bacterial community associated with octopus is very scarce, unlike fish and other molluscs. This study revealed the bacterial community associated with digestive tract of wild Chilean octopus Octopus mimus using a culture‐dependent method and 16S rDNA clone library. Moreover, we analysed the bacterial nutritional enzyme activity of culturable bacteria. A culture‐dependent method showed that the composition of the culturable bacterial community was substantially different between female and male octopus. The predominant species in female octopus were Vibrionaceae and Streptococcaceae, whereas only Vibrionaceae was dominated in male octopus. Bacterial nutritional enzyme activities of culturable bacteria from male octopus were much higher than female octopus. The 16S rDNA clone library analysis showed that the bacterial community of male octopus exhibited a higher diversity than that of female octopus. The genus Mycoplasma was the predominant bacteria in the digestive tract of all octopus samples. The results obtained in this study raise the possibility that each octopus has different food consumption due to different bacterial community and nutritional enzyme activity, although Mycoplasma sp. is one of the predominant bacteria in the digestive tract. Moreover, our results are useful for the future of microbiological investigation associated with the octopus and for probiotics in the octopus aquaculture.     

Effect of carbon/nitrogen ratio manipulation in feed supplements on Artemia production and water quality in solar salt ponds in the Mekong Delta,Vietnam

The effect of carbon/nitrogen (C/N) ratio manipulation in feed supplements on Artemia production and water quality was investigated in solar salt ponds in the Mekong Delta, Vietnam. It was assumed that development of bacterial bioflocs through C/N manipulation would improve Artemia production and water quality as demonstrated in freshwater and marine aquaculture. Twelve ponds were used for three treatments and the control, in triplicates. Green water (GW) was supplied to all ponds, with the standard Vietnamese procedure of supplying GW and chicken manure (CM) as the control (C/N 1.8). Treatment ponds were supplemented with tapioca (TAP) as carbon source, combined with either CM, pig manure (PM) or rice bran (RB), with C/N ratios of 7.4, 10.5 or 20.1 respectively. After 6 weeks of culture, no single treatment supported both improved water quality and enhanced Artemia production. Overall, improved water quality was observed at C/N 20.1 and higher Artemia production at C/N 7.4. Although external field factors could have interfered with the set‐up, this is the first study on the effect of C/N manipulation in feed supplements in Artemia pond production systems and provides the basis for development of bacterial bioflocs as a technology to improve water quality and Artemia production.     

Developments in the nutrition of Menidia estor Jordan 1880

The Mexican silverside, Menidia estor, is a species with great regional importance and with very high prices in local markets. Unfortunately, due to high fisheries pressure, environmental degradation and pollution, the species has become endangered. Recently, there has been much progress in the biotechnology of this species, aimed at its culture, and the present paper describes the advances in feeding and nutrition of those important fish. M. estor is a stomachless, zooplantophagous fish, which also occasionally feeds on small fish and crustaceans in the adult stage. Studies on the digestive enzymatic activities show high proteolytic capacity and a late or different model of digestive maturation from that described for marine stomach fish. Nutritional studies on M. estor have shown that juveniles have dietary requirements of about 400 g kg^?1 protein and 80 mg kg^?1 vitamin C. The upper level of dietary carbohydrate for good growth and survival for juveniles is about 150 g kg^?1. Based on the high docosahexaenoic acid (DHA) content in flesh when fed on diets low in DHA, it is believed that the species has the capacity to biosynthetize >20‐carbon fatty acids from 18‐carbon fatty acids. The high levels of DHA in flesh makes this fish a very significant potential component of human nutrition. Using these findings the first practical diets for commercial culture of the species have been developed.     

A practical and reliable procedure for in vitro induction of tetraploid tomato

A relatively rapid, practical and reliable procedure for in vitro production of tetraploid tomato using colchicine is described. Using this procedure 11.11% generation of tetraploids was obtained after exposure of seedling shoot meristem explants with 8 mM colchicine for 96 h. Confirmation of tetraploid production (2n = 48), was determined by flow cytometry and verified by cytogenetic analysis of root tip preparations. The results indicate that the procedure is adequate for induction and screening of tetraploid tomato plantlets.     

Genetic divergence among gerbera accessions evaluated by RAPD

Genetic diversity was evaluated by RAPD markers and morpho-agronomic characters for a total of 42 accessions of Barberton daisy (Gerbera jamesonii) consisting of 29 commercial and 13 wild accessions. A total of 74 polymorphic bands were obtained employing a set of 12 primer pairs. The average genetic similarity coefficient for the 42 accessions, evaluated by Jaccard index was 0.55 ranging from 0.28 to 1.00. The genetic structure found among Barberton daisy accessions was evaluated by hierarchic classification analyses and UPGMA modeling, revealing six clusters of genotypes where two of them include the wild accessions and the remaining four including commercial material, except for wild genotype number 9. Shannon (H′) index was calculated using the molecular markers to investigate the genetic variation among the Gerbera accessions and showed higher values for the commercial cluster in comparison to the values obtained for the individuals from the non-commercial cluster, namely 0.34 versus 0.27, respectively. Therefore, both calculated indices (Jaccard and Shannon) indicated the presence of higher genetic variation among commercial accessions in comparison to the cluster representing non-commercial accessions, suggesting that genetic breeding programs may focus on commercial accessions to recombine interesting genotypes with commercially important and marketing-desired characteristics.     

The Pelagos Sanctuary for Mediterranean marine mammals

• 1. In February 2002, France, Italy and Monaco agreed to establish an international sanctuary for Mediterranean marine mammals. The resulting Pelagos Sanctuary encompasses over 87500 km² of the north‐western Mediterranean Sea, extending between south‐eastern France, Monaco, north‐western Italy and northern Sardinia, and surrounding Corsica and the Tuscan Archipelago.
• 2. The Pelagos Sanctuary illustrates how the tenets of Marine Protected Area (MPA) design can be reconciled with the dynamic nature of oceanic systems, because its spatial scale was defined by oceanographic and ecological considerations, specifically the location of the Ligurian permanent frontal system.
• 3. By expanding protective measures beyond national waters, the Pelagos Sanctuary also sets a precedent for the implementation of pelagic protected areas in the high seas. The Pelagos Sanctuary will contribute to the conservation of the Mediterranean Sea at two scales: (i) locally, by protecting important cetacean foraging and breeding grounds in the Ligurian Sea, and by providing ‘umbrella’ protection to other marine predators in this area; and (ii) regionally, by empowering other conservation measures, such as the Specially Protected Areas Protocol of the Barcelona Convention and the wider goals of the Agreement on the Conservation of Cetaceans of the Black and Mediterranean Seas (ACCOBAMS).
• 4. However, because few cetacean species are resident within the Sanctuary, their effective long‐term conservation will require large‐scale management and coordinated monitoring throughout the Mediterranean basin.

Copyright © 2007 John Wiley & Sons, Ltd.     

The pond's shape matters: differential growth,physiological condition and survival of epibenthic Farfantepenaeus aztecus postlarvae

As a function of the water quality provided by square, circular and oval experimental ponds, the growth, survival and oxygen requirements in epibenthic postlarvae of Farfantepenaeus aztecus were analysed in relation to their routine metabolism and apparent heat increment. Temperature, oxygen concentration, pH and salinity were measured daily in two experimental ponds of each shape. The postlarvae oxygen consumption during two 24‐h cycles, their growth, physiological condition and survival and the productivity in the ponds were estimated. Low values of pH, oxygen concentration and phytobenthos productivity, and reduced postlarvae relative growth and survival were observed in the square ponds. We suggest that the latter results from a deficient water circulation related to the effect of the pond's shape on dissolved oxygen levels and, consequently, on growth and survival. The postlarvae routine metabolism, including feeding, varied between 1.91 and 2.25 mg O₂ h^?1 g^?1 wet weight, whereas the minimum oxygen concentration needed in the ponds is approximately 4.25 mg O₂ L^?1. These conditions were achieved in the oval ponds concurrent with higher survival and growth values, in which individuals distributed randomly, for which we suggest that oval‐shaped ponds could be the most adequate for the culture of this and other penaeid species.     

Implementation of two high through-put techniques in a novel application: detecting point mutations in large EMS mutated plant populations

Background  

The establishment of mutant populations together with the strategies for targeted mutation detection has been applied successfully to a large number of organisms including many species in the plant kingdom. Considerable efforts have been invested into research on tomato as a model for berry-fruit plants. With the progress of the tomato sequencing project, reverse genetics becomes an obvious and achievable goal.     

Estimation of actual evapotranspiration for a drip-irrigated Merlot vineyard using a three-source model

A study was performed in order to evaluate the three-source model (Clumped model) for direct estimation of actual evapotranspiration (ET_a) and latent heat flux (LE) over a drip-irrigated Merlot vineyard trained on a vertical shoot positioned system (VSP) under semi-arid conditions. The vineyard, with an average fractional cover of 30%, is located in the Talca Valley, Region del Maule, Chile. The performance of the Clumped model was evaluated using an eddy covariance system during the 2006/2007 and 2007/2008 growing seasons. Results indicate that the Clumped model was able to predict ET_a with a root mean square error (RMSE), mean bias error (MBE), and model efficiency (EF) of 0.33, −0.15 mm day⁻¹ and 74%, respectively. Also, the Clumped model simulated the daytime variation of LE with a RMSE of 36 W m⁻², MBE of −8 W m⁻², and EF of 83%. Major disagreement (underestimated values) between observed and estimated values of ET_a was found for clear days after rainfall or foggy days, but underestimated values were less than 10% of the data analysis. The results obtained in this study indicate that the Clumped model could be used to directly estimate vine water requirements for a drip-irrigated vineyard trained on a VSP. However, application of the Clumped model requires a good characterization of the drip-irrigated vineyard architecture.