Anabolism,catabolism and proteomic analysis in the slow‐twitch muscle of pacu (Piaractus mesopotamicus) submitted to prolonged fasting followed by refeeding

Here, we aimed to study the slow muscle of the fish Piaractus mesopotamicus submitted to 30 days of fasting (D30) followed by 1 day (D31) or 30 days of refeeding (D60). Histological analysis of fibre diameter was performed in D30 and D60. The gene expression of parvalbumin (pvalb), atrogenes (murf1a, murf1b, mafbx) and anabolic genes (igf‐1, mtor) was analysed using RT‐qPCR in D30, D31 and D60. The proteome was obtained by shotgun proteomics at D30 and D60, and the set of differentially expressed proteins was analysed by bioinformatics. In all experiments, the control was regularly fed fish. The histological analysis showed no changes in muscle fibre diameter. The expression of catabolic and anabolic genes was not changed, except for the downregulation of igf‐1 in D30 and of mafbx in D31. The expression of pvalb was not changed in D30 and D60 but was decreased in D31. The proteomic analysis identified 169 proteins in D30 (24 upregulated and 18 downregulated) and 170 proteins in D60 (17 upregulated and 21 downregulated); many of them were related to energetic metabolism and intracellular Ca²⁺ homoeostasis. Overall, our results indicate that the slow‐twitch muscle presented few changes upon prolonged fasting and refeeding condition.     

Evaluation of the Microalgae Paste Viability Produced in a Mollusk Hatchery in Southern Brazil

The present study was conducted to define a methodology to produce and store small‐scale microalgae paste to be used in a mollusk hatchery. Microalgae were cultured in 500 L fiberglass tanks, under temperature of 20 ± 2 C, Guillard f/2 culture medium, and continuous light intensity of 203–226 μmol photons/m²/sec. Cultures were centrifuged at 2000 g at the exponential growth phase. Microalgae cell quality after centrifugation and during storage was determined by analyses with Evan’s blue stain and by counting the number of total marine bacteria. Treatments with and without additive were applied to the microalgae paste produced, which was distributed into 100 mL plastic containers, capped, and stored under refrigeration at 4 ± 1 C. Results indicated that in the Chaetoceros muelleri paste, centrifugation did not damage the cells and the number of total marine bacteria reduced significantly from 2.9 × 10⁶ to 8.3 × 10⁵ colony‐forming units per milliliter. Chaetoceros muelleri and Chaetoceros calcitrans pastes stored with addition of 0.1% ascorbic acid had a shelf life shorter than 2 wk. For the treatment without additive, results with Evan’s blue stain showed that cells (99%) remained viable until the sixth week of storage for C. muelleri and seventh week of storage for Skeletonema sp. and C. calcitrans. The number of bacteria did not increase during storage for C. calcitrans and Skeletonema (P > 0.05). For C. muelleri, an increase in bacteria (P < 0.05) was observed after the sixth week of storage. This study demonstrated the feasibility to produce and store microalgae paste for a period of 2–8 wk, which allows it to be used as food source and also optimizes the use of microalgae cultured in laboratory.     

Bactericidal and fungicidal activity of Aspergillus ochraceus metabolites and some derivatives

The bactericidal and fungicidal activities of aspyrone and asperlactone, secondary metabolites of Aspergillus ochraceus, and some aspyrone derivatives were studied. In general, aspyrone exhibited better activity than asperlactone or aspyrone derivatives. The inhibition patterns of the assayed compounds were different. Helminthosporium monoceras was the tested mould most inhibited by the studied compounds. The comparative study of the activity of the different compounds showed that the epoxy group seems to be necessary for activity against some micro-organisms. © 1998 SCI     

Search for <Emphasis Type="Italic">Salmonella</Emphasis> spp. in ostrich productive chain of Brazilian southeast region

We analyzed ostriches from an equipped farm located in the Brazilian southeast region for the presence of Salmonella spp. This bacterium was investigated in 80 samples of ostrich droppings, 90 eggs, 30 samples of feed and 30 samples of droppings from rodents. Additionally, at slaughter-house this bacterium was investigated in droppings, caecal content, spleen, liver and carcasses from 90 slaughtered ostriches from the studied farm. Also, blood serum of those animals were harvested and submitted to serum plate agglutination using commercial Salmonella Pullorum antigen. No Salmonella spp. was detected in any eggs, caecal content, liver, spleen, carcass and droppings from ostriches and rodents. However, Salmonella Javiana and Salmonella enterica subsp. enterica 4, 12: i:- were isolated from some samples of feed. The serologic test was negative for all samples. Good sanitary farming management and the application of HACCP principles and GMP during the slaughtering process could explain the absence of Salmonella spp. in the tested samples.