Physiological responses of Nile tilapia, Oreochromis niloticus, fed vitamin C- and lipid-supplemented diets and submitted to low-temperature stress

Water temperature alterations can determine harmful physiological modifications in fish, which should be prepared to cope with this, and nutrition strategies seem to be essential. This study evaluated the effects of different levels of vitamin C and lipids on physiological responses of Nile tilapia, Oreochromis niloticus, submitted to temperature stress. There were two phases: Phase I - preparing fish to store vitamin C and lipid at appropriate temperature, and Phase II - evaluating the contributions these reserves make to fish physiology under low-temperature stress. The experiment used a 3 x 2 factorial design with three vitamin C levels (300, 600, and 1200 mg/kg diet) and two lipid levels (8.0 and 12.0%), plus absence of nutrient test and a diet of 6.0% lipids and 125.0 mg/kg vitamin C. In Phase I, 192 fish were kept at 26.0 +/- 1.0 C for 112 d, and in Phase II, 48 fish were kept at 18.0 +/- 0.5 C for 32 d and at 15.0 +/- 0.5 C for 11 d. Fish fed C0L0 diet showed lower erythrocytes values in both phases; higher vitamin C supplement determined higher red blood cell (RBC) number and higher hematocrit (Htc) (Phase II); Htc was significantly lower in Phase II; after temperature stress, fish fed C0L0 diet had higher mean corpuscular volume, lower hemoglobin corpuscular concentration, and significantly lower vitamin C concentration in the liver; and higher supplementation determined a higher concentration in the liver (Phases I and II). Higher plasmatic cortisol concentration was seen in fish fed C0L0 diet. In conclusion, our results show that the absence of vitamin C in diets impairs RBC formation and does not enable fish to cope with stress; excess vitamin C is efficient in mitigating stress and 600 mg/kg diet is economic and physiologically sufficient to prepare fish for coping with low-temperature stress. Lipid supplementation does not determine alterations in stress biochemical parameters.

Effect of the type of environmental stress on the emergence of sunflower (Helianthus annus L.), soybean (Glycine max (L.) Merril) and maize (Zea mays L.) seeds with different levels of vigor

Sowing is a critical time in the cycle of a crop and the seeds are frequently exposed to adverse conditions that may compromise the establishment of seedlings in the field. on this basis, the objective of the present study was to determine the effect of types of environmental stress on the emergence of sunflower, maize and soybean seeds with different levels of vigor. High vigor seeds were artificially aged in order to obtain medium and low vigor seeds and then they were sown in clay soil in plastic boxes and submitted to the following types of environmental stress during the germination process : 1) high temperature (35degreesC), 2) low temperature (15 or 18degreesC), 3) water excess (Psi > -0.0001 MPa), 4) water deficiency (Psi approximately equal to -1.1; -1.2 and -0.6 MPa for sunflower, maize and soybean, respectively), 5) sowing at a depth of 7 cm and 6) pathogenic infection of sunflower seeds with Alternaria helianthi, of maize seeds with Fusarium moniliforme and of soybean seeds with Colletotrichum dematium, var. truncata. The results were compared to those obtained with controls sown under optimal condition. It was concluded that: 1) the effect of seed vigor on emergence depends on the type of enviromental stress to which the seeds are exposed, 2) the stress to which the the seeds demonstrated highest sensitivity varied with species and 3) high temperature stress was the one that most impaired the emergence of the three species.

Resposta hemática de tilápias-do-nilo alimentadas com dietas suplementadas com colina e submetidas a estímulo por baixa temperatura

Esta pesquisa foi realizada com o objetivo de avaliar a resposta hemática de tilápias-do-nilo (Oreochromis niloticus) arraçoadas com dietas suplementadas com colina e submetidas a estímulo por baixa temperatura. O período experimental foi realizado em duas etapas: a primeira, de 109 dias, e a segunda, de 7 dias. Durante a primeira etapa, foram utilizados 192 alevinos com peso médio inicial de 4 g, distribuídos em 32 tanques-rede de 200 L instalados em aquários de mil litros. As rações foram formuladas de modo a apresentar 28,0% de proteína digestível e 3.100,0 kcal ED/kg e mesma concentração de aminoácidos. O delineamento experimental foi inteiramente casualizado com oito tratamentos e quatro repetições. As rações foram suplementadas com colina (cloreto de colina 60,0%), de modo a apresentar 100,0; 200,0; 400,0; 600,0; 800,0; 1.000,0 e 1.200,0 mg/kg de ração, e avaliadas em comparação a uma ração sem suplementação. Após o período de 109 dias, foram efetuadas as análises hematológicas dos peixes. Após as análises, os peixes foram transferidos para a sala de desafio e distribuídos em 24 aquários, onde foram mantidos a 17ºC durante sete dias. Após esse período, foram feitas as mesmas análises do período anterior ao desafio. A suplementação de colina não influenciou a eritropoiese ao estímulo pelo frio. A suplementação dietética de colina não interfere na síntese de eritrócitos e leucócitos e a temperatura de 17,0ºC determina linfopenia e neutrofilia.

Haematological response and growth performance of Nile tilapia (Oreochromis niloticus L.) fed diets containing folic acid

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Lipídeo e vitamina C em dietas preparatórias de inverno para tilápias-do-nilo

Foram avaliados o desempenho produtivo e os parâmetros fisiológicos de tilápias-do-nilo alimentadas, durante 112 dias, com dietas preparatórias para o inverno, formuladas com diferentes níveis de lipídeo e vitamina C. Utilizaram-se 192 alevinos (5,57 ± 0,50 g) distribuídos em 32 tanques-rede. O experimento foi conduzido em esquema fatorial 2 ´ 3, composto de dois níveis (8,0 e 12,0%) de lipídeo e três níveis (300,0; 600,0 e 1.200,0 mg/kg de ração) de vitamina C, em comparação a duas dietas (uma isenta dos nutrientes-teste e outra com 6,0% de lipídeo e 125,0 mg de vitamina C), totalizando oito dietas isoprotéicas (32,0% de proteína digestível). A energia adicional proveniente do lipídeo é depositada na cavidade abdominal em forma de gordura visceral; a deposição desta gordura como reserva de energia foi obtida nos níveis de suplementação de lipídeo testados; a concentração hepática de vitamina C é proporcional à sua concentração na dieta; a ausência desta vitamina na dieta prejudica a eritropoiese e a síntese de colágeno.

Microsatellite marker-based assessment of the biodiversity of native bioethanol yeast strains

Although many Brazilian sugar mills initiate the fermentation process by inoculating selected commercial Saccharomyces cerevisiae strains, the unsterile conditions of the industrial sugar cane ethanol fermentation process permit the constant entry of native yeast strains. Certain of those native strains are better adapted and tend to predominate over the initial strain, which may cause problems during fermentation. In the industrial fermentation process, yeast cells are often exposed to stressful environmental conditions, including prolonged cell recycling, ethanol toxicity and osmotic, oxidative or temperature stress. Little is known about these S. cerevisiae strains, although recent studies have demonstrated that heterogeneous genome architecture is exhibited by some selected well-adapted Brazilian indigenous yeast strains that display high performance in bioethanol fermentation. In this study, 11 microsatellite markers were used to assess the genetic diversity and population structure of the native autochthonous S. cerevisiae strains in various Brazilian sugar mills. The resulting multilocus data were used to build a similarity-based phenetic tree and to perform a Bayesian population structure analysis. The tree revealed the presence of great genetic diversity among the strains, which were arranged according to the place of origin and the collection year. The population structure analysis revealed genotypic differences among populations; in certain populations, these genotypic differences are combined to yield notably genotypically diverse individuals. The high yeast diversity observed among native S. cerevisiae strains provides new insights on the use of autochthonous high-fitness strains with industrial characteristics as starter cultures at bioethanol plants. © 2013 John Wiley & Sons, Ltd.

Variação genética e adaptabilidade evolutiva de Rhizoctonia solani AG-1 da soja sob condições de estresse

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Suplementação dietária de cobre no desempenho produtivo da tilápia-do-Nilo e resposta hemática sob estresse térmico

Pós-graduação em Zootecnia - FMVZ

Lipídeo e vitamina C em dietas práticas para a Tilápia no Nilo (Oreochromis niloticus)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Estresse térmico no conteudo de prolina de plântulas de guandu oriundas de sementes tratadas com poliaminas

Pós-graduação em Agronomia (Produção Vegetal) - FCAV

Estresse térmico no acúmulo de prolina livre de plântulas de guandu oriundas de sementes tratadas com poliaminas

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Incubation and rearing temperature effects on Hsp70 levels and heat stress response in broilers

Incubation temperature (IT) was changed to evaluate if 6-wk-old birds become more tolerant to heat stress. After 13 d of incubation, 470 eggs were submitted to low (36.8degreesC), normal (37.8degreesC) and high (38.8degreesC) temperatures. At day 7 post-hatching, 144 birds were allocated to three rearing temperatures (48 birds/treatment): control/thermoneutral (35-24degreesC), high (33-30degreesC) or low (27-18degreesC) according to the age of the birds. Hsp70 levels in tissues of birds (1 d and 42 d), stress response (42 d) and performance were evaluated. High IT decreased brain (P < 0.01) and liver (P < 0.01) Hsp70 levels, whereas low IT decreased brain (P < 0.01) but increased heart (P < 0.01) Hsp70 levels in 1-d-old chicks. Birds incubated at a low temperature had higher (P < 0.05) feed intake (1-42d). High rearing temperature decreased feed intake (P<0.01) and liveweight (P<0.01). Colonic temperature was lower in birds incubated at a low temperature (P < 0.05) and higher in birds reared in a high temperature (P < 0.05) before heat stress. Birds reared in low temperature had higher increase in colonic temperature after heat stress (P < 0.05). Tissue Hsp70 levels were differently affected by rearing temperature, which affected broiler performance more than IT. Lower IT seemed to increase the sensitivity of birds to heat stress at market age.

Germination of Jacaranda mimosifolia (D. Don - Bignoniaceae) seeds: effects of light, temperature and water stress

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Estimating mortality in laying hens as the environmental temperature increases

Layer mortality due to heat stress is an important economic loss for the producer. The aim of this study was to determine the mortality pattern of layers reared in the region of Bastos, SP, Brazil, according to external environment and bird age. Data mining technique were used based on monthly mortality records of hens in production, 135 poultry houses, from January 2004 to August 2008. The external environment was characterized according maximum and minimum temperatures, obtained monthly at the meteorological station CATI in the city of Tupa, SP, Brazil. Mortality was classified as normal (<= 1.2%) or high (> 1.2%), considering the mortality limits mentioned in literature. Data mining technique produced a decision tree with nine levels and 23 leaves, with 62.6% of overall accuracy. The hit rate for the High class was 64.1% and 59.9% for Normal class. The decision tree allowed finding a pattern in the mortality data, generating a model for estimating mortality based on the thermal environment and bird age.

Photosynthesis in eucalyptus studied by the open photoacoustic technique: Effects of irradiance and temperature

This work demonstrates the usefulness of the Open Photoacoustic Cell Technique to study the effects of irradiance and temperature on photosynthesis. bl vivo and ill situ photosynthetic induction measurements were performed in three different species of eucalyptus plants (E. grandis, E. urophylla, and E, urograndis) previously dark-adapted at different temperatures. Photosynthetic activity curves were built as a function of light intensity, indicating the occurrence of photosynthesis saturation. E. urograndis presented higher photosynthetic activity than the other species, especially at low temperature, indicating its tolerance to stress conditions. The incidence of background saturation light of various intensities allowed the irt situ study of photoinhibition in eucalyptus plants through open photoacoustics. (C) 2001 MAIK Nauka/Interperiodica.