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.     

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 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.     

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.     

Growth,absorption and assimilation efficiency by mature cuttlefish (<Emphasis Type="Italic">Sepia officinalis</Emphasis>) fed with alternative and artificial diets

The effects of feeding three natural frozen diets, grass shrimp (Palaemonetes sp.), crayfish (Procambarus clarkii) and fish (Sardina pilchardus) and two semi-humid artificial diets (based on fish powder) to mature cuttlefish, Sepia officinalis, were analysed. Growth and feeding rates (GR and FR, % BW day⁻¹), food conversions (FC, %), and total protein and lipid composition of the diets were determined. Digestive gland to body weight ratio and absorption efficiency were calculated for each diet. Cuttlefish fed shrimp and crayfish grew larger (1.5 and 1.1% BW day⁻¹, respectively) compared to the other diets. Shrimp promoted the highest FC, followed by crayfish, and sardine. The highest FR was obtained for cuttlefish fed crayfish (8.4% BW day⁻¹). Although both artificial diets were accepted, none produced growth. A positive correlation (r = 0.96) between cuttlefish ingestion rate and digestive gland weight was obtained. Some cannibalism occurred among cuttlefish fed the artificial diets during the last week of the experiment. According to the results obtained, P. clarkii could be used as an alternative prey to shrimp for rearing adult mature (>50 g) S. officinalis.     

Effect of starvation on survival and biochemical profile of newborn juvenile lined seahorses,Hippocampus erectus (Perry, 1810)

This study assessed the effect of starvation on survival and nutritional status of newborn juveniles H. erectus (<10 days) to optimize rearing protocols, thereby helping to reduce wildlife exploitation. Maximum starvation time (MST) was estimated through the survival of juveniles continuously starved from birth. Resistance to starvation and the effect of food re‐introduction after 1, 2, 4 and 6 days of starvation on survival and metabolite concentrations (total proteins, total lipids, acylglycerides, cholesterol, glucose) were also determined. Survival amongst continuously starved animals decreased from 6.6 ± 0.5 to 0% from days 9 to 10 of starvation. Seahorses under different starvation–refeeding treatments all had 100% survival up to day 5 of experiments. After 10 days, however, a 4‐day starvation period followed by refeeding showed negative effects with <50% survival. During continuous starvation, lipids were the first energy reserve used to maintain basal metabolism, followed by proteins. Except for cholesterol, all metabolite concentrations differed between continuous starvations and feeding. Despite high seahorse survival after 5 days in the absence of food, the recovery of the metabolic status is possible after a starvation period of no more than 2 days, since irreversible physiological changes compromising the ultimate survival of the organisms take place after this time.     

Soybean molasses as an organic carbon source in the farming of Litopenaeus vannamei (Boone, 1931) in a biofloc system

Soybean molasses was evaluated as a partial replacement for sugarcane molasses as a carbon source for biofloc development in the superintensive culture of Pacific white shrimp (Litopenaeus vannamei). A 50‐day study was conducted with juvenile (3.2 g) shrimp stocked in 16 800 L tanks at a stocking density of 250 shrimp m^?3. Control of total ammonia concentration was performed by the addition of combined mixtures of soybean and sugarcane molasses to the culture water. Three different molasses treatments were evaluated using different soybean‐to‐sugarcane molasses ratios: 15–85%, 38–62% and 60–40% respectively. The control group was treated only with sugarcane molasses. Water quality, chlorophyll a concentration, heterotrophic bacterial load, Vibrio spp. concentration and zootechnical indexes were all evaluated. Total ammonia concentration was controlled by heterotrophic and chemotrophic pathways. Biofloc formation, as quantified by measuring the total suspended solids, was not altered. The Vibrio spp. concentration showed a significant reduction in treatments with soybean‐to‐sugarcane molasses ratios of 38–62% and 60–40%. All combined mixtures of soybean and sugarcane molasses could maintain water quality and productivity in the superintensive culture of L. vannamei using the biofloc system. Thus, the potential use of a residue from agroindustry as a carbon source in a biofloc culture is demonstrated.