Phase behaviour of DNA in presence of DNA-binding proteins

To characterize the thermodynamical equilibrium of DNA chains interacting with a solution of non-specific binding proteins, a Flory-Huggins free energy model was implemented. We explored the dependence on DNA and protein concentrations of the DNA collapse. For physiologically relevant values of the DNA-protein affinity, this collapse gives rise to a biphasic regime with a dense and a dilute phase; the corresponding phase diagram was computed. Using an approach based on Hamiltonian paths, we show that the dense phase has either a molten globule or a crystalline structure, depending on the DNA bending rigidity, which is influenced by the ionic strength. These results are valid at the thermodynamical equilibrium and should therefore be consistent with many biological processes, whose characteristic timescales range typically from 1 ms to 10 s. Our model may thus be applied to biological phenomena that involve DNA-binding proteins, such as DNA condensation with crystalline order, which occurs in some bacteria to protect their chromosome from detrimental factors; or transcription initiation, which occurs in clusters called transcription factories that are reminiscent of the dense phase characterized in this study.Comment: 20 pages, 9 figures, accepted for publication at The Biophysical Journa

Enhancing opportunistic polychaete communities under fish farms: an alternative concept for integrated aquaculture

This note presents the development of benthic integrated aquaculture, addressing a novel cultivation concept for open-water aquaculture. We introduce an approach that supports the colonization of indigenous polychaete communities on benthic cultivation trays deployed in the vicinity of fish-farming cages. Enhancement and subsequent harvest of polychaetes that naturally dominate the local benthic response is essentially different from the classical IMTA approach wherein juveniles and/or seedlings of the extractive species are introduced to the farm site. Results of a field trial showed quick and massive colonization of cultivation trays by polychaetes (predominantly Ophryotrocha craigsmithi) and large spatial variability within the salmon farm site. Our results suggest that enhancing indigenous opportunistic polychaetes is a promising cultivation concept making use of the deposition of organic wastes such as fish faeces and uneaten feed. The methods and results presented here contribute to solutions for technical optimization of benthic IMTA techniques. We expect that further advances in benthic IMTA production will contribute to the expansion of open-water finfish aquaculture within environmentally sustainable boundaries

Vaccination-induced systemic autoimmunity in farmed atlantic salmon

Over half of the salmon consumed globally are farm-raised. The introduction of oil-adjuvanted vaccines into salmon aquaculture made large-scale production feasible by preventing infections. The vaccines that are given i.p. contain oil adjuvant such as mineral oil. However, in rodents, a single i.p. injection of adjuvant hydrocarbon oil induces lupus-like systemic autoimmune syndrome, characterized by autoantibodies, immune complex glomerulonephritis, and arthritis. In the present study, whether the farmed salmon that received oil-adjuvanted vaccine have autoimmune syndrome similar to adjuvant oil-injected rodents was examined. Sera and tissues were collected from vaccinated or unvaccinated Atlantic salmon (experimental, seven farms) and wild salmon. Autoantibodies (immunofluorescence, ELISA, and immunoprecipitation) and IgM levels (ELISA) in sera were measured. Kidneys and livers were examined for pathology. Autoantibodies were common in vaccinated fish vs unvaccinated controls and they reacted with salmon cells/Ags in addition to their reactivity with mammalian Ags. Diffuse nuclear/cytoplasmic staining was common in immunofluorescence but some had more specific patterns. Serum total IgM levels were also increased in vaccinated fish; however, the fold increase of autoantibodies was much more than that of total IgM. Sera from vaccinated fish immunoprecipitated ferritin and similar to 50% also reacted with other unique proteins. Thrombosis and granulomatous inflammation in liver, and immune-complex glomerulonephritis were common in vaccinated fish. Autoimmunity similar to the mouse model of adjuvant oil-induced lupus is common in vaccinated farmed Atlantic salmon. This may have a significant impact on production loss, disease of previously unknown etiology, and future strategies of vaccines and salmon farming

Efeito da granulometria do milho no desempenho de juvenis de pacu, Piaractus mesopotamicus (Holmberg, 1887)

Avaliou-se o efeito de diferentes granulometrias do milho da ração no desempenho de juvenis de pacu, Piaractus mesopotamicus. Foram utilizados 120 juvenis com peso inicial de 8,42±0,89, comprimento total de 7,03±0,20cm, comprimento padrão de 6,32±0,13cm e altura de 3,21±0,11cm, distribuídos em 20 aquários (300L), na densidade de seis peixes por unidade experimental (aquário), em delineamento inteiramente ao acaso, com cinco tratamentos constituídos por diferentes granulometrias - 850, 710, 500, 300, 150µm - do milho na composição da ração. Cada tratamento tinha quatro repetições. O tratamento que proporcionou melhor desempenho dos animais foi o com granulometria do milho de 150µm, destacando-se a conversão alimentar de 1,38, enquanto no tratamento com maior granulometria a conversão alimentar foi de 1,61. Assim, recomenda-se usar a granulometria de 150µm

Effect of dietary protein level and source on digestive proteolytic enzyme activity of juvenile Senegalese sole, Solea senegalensis Kaup 1850

The effect of dietary protein level and protein source on growth and proteolytic activity of juvenile Solea senegalensis was studied. In Experiment 1, fish were fed on four experimental diets containing increased protein levels (36, 46, 56 and 67%). In Experiment 2, Senegalese soles were fed on five diets with partial substitution of fish meal by soybean meal, soybean protein concentrate, soybean protein isolate, wheat gluten meal or pea protein concentrate. Results prove that growth and proteolytic activity in the distal intestine of fish were affected by the quantitative increase in dietary protein. The origin of protein source used in the elaboration of experimental diets affected both the amount and composition of the alkaline proteases secreted into the intestinal lumen; however, it did not decrease animal growth. Juvenile Senegalese sole showed capability to modulate digestive protease secretion when the concentration and/or source of dietary protein were modified. Quantity and quality of dietary protein affected protein hydrolysis in Senegalese sole intestine. This study establishes that 30% fish meal protein can be replaced by soybean derivatives without affecting intestinal proteases. Replacement with wheat gluten meal or pea protein concentrate should be taken cautiously, but further research is needed to establish whether growth performance and digestive enzyme physiology of Senegalese sole are affected by plant protein-supplemented diets in a long-term trial.This work was supported by Projects INIA RTA-2007-00026-C02-01 and 02, and the European Regional Development Fund. Ana Rodiles Guerrero was financially supported by the grant "Technology in the Larval Rearing of New Species of Fish" (IFAPA, Andalusian Regional Government, Spain). The authors thank Jose I. Navas Triano, Sean Tibbetts, Joyce Milley, Toni Barros and Andres Monino for their technical assistance. The authors are grateful to Francisco Trujillo for the revision of the English language text. Part of experimental work was carried out at CEIA3 facilities.Rodiles, A.; Santigosa, E.; Herrera, M.; Hachero Cruzado, I.; Cordero, ML.; Martínez-Llorens, S.; Lall, SP.... (2012). Effect of dietary protein level and source on digestive proteolytic enzyme activity of juvenile Senegalese sole, Solea senegalensis Kaup 1850. Aquaculture International. 20(6):1053-1070. https://doi.org/10.1007/s10499-012-9508-6S10531070206Alarcón FJ, Díaz M, Moyano FJ, Abellán E (1998) Characterization and functional properties of digestive proteases in two sparids; gilthead sea bream (Sparus aurata) and common dentex (Dentex dentex). Fish Physiol Biochem 19:257–267Alarcón FJ, García-Carreño FL, Navarrete del Toro MA (2001) Effect of plant protease inhibitors on digestive proteases in two fish species, Lutjanus argentiventris and L. novemfasciatus. 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