Muscle delta C-13 change in Nile tilapia (Oreochromis niloticus): Effects of growth and carbon turnover

The contribution of growth and turnover to the muscle delta C-13 change process was investigated using mathematical models which associate delta C-13 change to time of intake of a new diet or increase in body mass. Two groups of Nile tilapia (Oreochromis niloticus) were fed on diets based on C3 (sigma C-13 = - 25.64 +/- 0.06 parts per thousand) or C4 (delta C-13= -16.01 +/- 0.06 parts per thousand) photosynthetic cycle plants to standardize the muscle delta C-13. After establishing the carbon isotopic equilibrium, fish (mean mass 24.12 +/- 6.79 g) then received the other treatment diet until a new carbon isotopic equilibrium could be established, characterizing T1 (C3-C4) and T2 (C4-C3) treatments. No significant differences were observed in fish productive performance. Good fits were obtained for the models that associated the delta C-13 change to time, resulting in carbon half-life values of 23.33 days for T1 and 25.96 days for T2. Based on values found for the muscle delta C-13 change rate from growth (0.0263 day(-1) and 0.0254 day(-1)) and turnover (0.0034 day(-1) and 0.0013 day(-1)), our results indicate that most of the delta C-13 change could be attributed to growth. The application of model that associated the delta C-13 change to body mass increase seems to produce results with no apparent biological explanation. The delta C-13 change rate could directly reflect the daily ration and growth rate, and consequently the isotopic change rates of carbon and other tissue elements can be properly used to assess different factors that may interfere in nutrient utilization and growth. (c) 2006 Published by Elsevier B.V.

Phototrophic growth of Rubrivivax gelatinosus in poultry slaughterhouse wastewater

Rubrivivax gelatinosus was grown in Pfennig's synthetic medium (PM) and in treated wastewater from poultry slaughterhouse (TW) to assess growth profiles for biomass production. Cultures inoculated at 1% (v/v) were grown under anaerobiosis at 30 +/- 2 degrees C and 1400 200 lux for 12 days. Regular absorbance curves for R. gelatinosus were found both on PM and TW. on PM, the highest dry weight of biomass, 0.39 g L-1. was achieved in the 216-h culture and the highest specific growth rate of 0.2960 h(-1) occurred in the 24-h culture. on TW, the highest biomass of 0.57 g L-1 was also obtained in the 216-h culture and the highest specific growth rate, 0.1970 h(-1), was achieved in the 48-h culture. For productivity and chemical oxygen demand investigations, the cultivation was accomplished in the TW under anaerobiosis at 32 +/- 2 degrees C and 4000 +/- 500 lux, for 10 days. Productivity was 0.085 g biomass (d.w.) L-1 day(-1), with a COD decrease of 91%. (c) 2007 Elsevier Ltd. All rights reserved.

Morphological and histochemical study of the myotomal muscle in pacu (Piaractus mesopotamicus Holmberg, 1887) during the initial growth phases

Morphological and histochemical methods were used to evaluate the myotomal muscle characteristics of pacu (Piaractus mesopotamicus) from hatching to 40 days old. During the larval period, the musculature consisted predominantly of white muscle. White and red muscle mass increased at 10, 20, 30 and 40 days after hatching. The larvae had round muscle fibers with a moderate degree of maturation and central nuclei. In subsequent phases, small and immature fibers were visible near larger and more differentiated fibers. Undifferentiated cells or presumptive myoblasts located in embryogenic zones were visible in the dorsal and ventral regions, and were more evident at 30 and 40 days. The red muscle fibers located in the subdermal region, had oxidative metabolism and slow contraction, whereas the more predominant white muscle fibers had glycolytic metabolism and fast contraction. Our findings indicate that during the initial phases, myotomal muscle growth in pacu occurs by both, muscle fiber hypertrophy and hyperplasia. The analysis of frequency of red and white muscle fibers shows that hyperplastic growth is intense in this period. As the growth rate in adult fish is related to the number of muscle fibers in young fish, extrinsic factors could change the muscle fiber phenotype and influence their ultimate size.

Correlations Between Pre- and Post-Fasting Growth in Nile Tilapia

We tested the correlation between growth rate before and after a food deprivation phase in twelve single held Nile tilapias, Oreochromis niloticus. The experiment was divided into three phases: before food deprivation (phase 1: 15 d), food deprivation (phase 2: 12 d) and refeeding (phase 3: 15 d). The specific growth rate - SGR, food conversion efficiency - FCE and feed ingestion increased significantly during phase 3. Positive and significant correlations were found either to SGR or to feed ingestion between Phase 1 and 3 but not for FCE. The SGR on phase 3, moreover, were positively correlated to FCE and feed ingestion, while on phase 1 SGR was positively correlated to FCE only. Thus, high pre-fasting SGR or feed ingestion reflects in likewise high post-fasting SGR or feed ingestion values. Moreover, since SGR and FCE are correlated to each other in both phase 1 and 3, but phase 3 SGR is also correlated to feed ingestion; we could suppose that hyperphagic behaviour could be the main compensatory mechanism. Accordingly, we suggest that a fish with an elevated growth performance shall display a proportionally raised post-fasting growth response in order to normalize its predetermined growth trajectory and resume its normal growth rate.

Sex-specific compensatory growth in food-deprived Nile tilapia

Female Nile tilapia incubate fertilized eggs in their mouth until they are released as alevins. Consequently, the female may not eat during this period. Thus, it would be expected that female Nile tilapia are more adapted to recovering from fasting than males, which do not display this behavior. To test this hypothesis we conducted an experiment with two groups of fish consisting of 7 males and 7 females each, with one fish per aquarium. The experiment was divided into three phases involving adjustment of the animals to experimental aquaria (0-15th day), fasting (16th-27th day), and refeeding (27th-42nd day). Compensatory growth performance was assessed by specific growth rate, weight, food conversion efficiency and food intake. Food conversion efficiency increased after fasting with a similar rate for both sexes. However, specific growth rate, food intake and weight gain (%) were significantly higher in males than in females in the refeeding phase. Thus, we conclude that male Nile tilapia can compensate for a fasting period more efficiently than females, refuting our hypothesis. A possible mechanism involved in the greater male compensation is that they presented greater hyperphagia than females, concomitantly with a similar rate of food conversion efficiency for both sexes during refeeding, which would probably be provoking greater growth in males.

The influence of initial feeding on muscle development and growth in pacu Piaractus mesopotamicus larvae

The effects of different feeding schemes on pacu Piaractus mesopotamicus early development were evaluated with respect to growth, survival, muscle development, and differential gene expression of MyoD and myogenin. The pacu larvae (4 days post hatch-dph, 0.77 mg wet weight) were given six feeding treatments intentionally designed to cause variations in the larvae growth rate: (A) only artemia nauplii; (CD) only a commercial diet; (ED) only a semi-purified experimental diet; (ACD) and (AED) two treatments that involved weaning; and (S) starvation. Early weaning from artemia nauplii to the formulated diets (ACD and AED) affected growth and survival of the pacu larvae compared with the exclusive use of artemia (A). Starvation (S) and the commercial diet (CD) caused total mortality in pacu larvae at 18 dph. The experimental diet (ED) assured low fish survival and growth. The skeletal muscle morphology was not affected by the delay in somatic growth from early weaning onto the formulated diets. Three distinct muscle compartments were observed throughout the larval development in treatments A, ACD and AED: superficial, deep and intermediate, accompanied by muscle thickening. Severe undernourishment caused drastic differences in growth and in the morphology of the muscle fibers. Pacu larvae fed only formulated diets (CD and ED) showed muscle characteristics similar to the larvae in starvation (S) during the first 15 dph. At 27 and 35 dph, a slight increase in epaxial muscle mass was noted in larvae fed only the experimental diet (ED). At 35 dph, we observed a high frequency of fibers >= 40 mu m in the larvae that were weaned onto the formulated diets (ACD and AED), indicative of hypertrophy. In contrast, the larvae fed only artemia nauplii (A) displayed a larger number of fibers with diameters <= 20 mu m, which is indicative of hyperplasia. The expression of the MyoD and myogenin genes in pacu larvae at 35 dph was not affected by initial feeding (p>0.05). In conclusion, the formulated diets used impaired pacu larvae growth and survival; therefore, they were inadequate for pacu, at least at the times they were introduced. Artemia nauplii were the most adequate food source during first feeding of the pacu, and they produced bigger fish upon completion of the experiment. Moreover, the contribution of hyperplasia to the skeletal muscle growth appeared higher in fast- than in slow-growing pacu larvae. (C) 2011 Elsevier By. All rights reserved.

Relative growth of Petrochirus diogenes (Linnaeus, 1758) (Crustacea, Anomura, Diogenidae) in the Ubatuba region, São Paulo, Brazil

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

Growth of free-floating aquatic macrophytes in different concentrations of nutrients

The objective of the study was to evaluate the effect of different concentrations of nitrogen and phosphorus on the growth of the free-floating aquatic macrophytes Eichhornia crassipes, Pistia stratiotes, and Salvinia molesta. The plants were cultured in 2,000-l outdoor concrete tanks. Triplicate tanks, with a continuous flow of effluent from culture ponds containing Nile tilapia, were used for each plant type (n = 3). The plant material was collected monthly from 0.25 m(2) floating quadrats, at the two ends of the tanks (higher nutrient concentrations near the inflow and lower nutrient concentrations near the outflow). In low nutrient concentrations, the maximum relative growth rates (RGRs) for E. crassipes (0.016/day) and P. stratiotes (0.016/day) were significantly lower (P <= 0.05) than for S. molesta (0.029/day). There were no significant differences between the RGRs of S. molesta in the different nutrient concentrations. Eichhornia crassipes and P. stratiotes had their growth limited by nitrogen and phosphorus concentrations. The increase in plant density during the experiment probably also affected the growth of these species. In this context, E. crassipes and P. stratiotes can cause problems in nutrient-rich waterbodies, but under these experimental conditions their growth was limited by nitrogen and/or phosphorus concentrations. The growth of S. molesta was not influenced by the different nutrient concentrations.

Demographic aspects of Chrysomya megracephala (Diptera, Calliphoridae) adults maintained under experimental conditions: Reproductive rate estimates

The objective of this work was to evaluate some aspects of the populational ecology of Chrysomya megacephala, analyzing demographic aspects of adults kept under experimental conditions. Cages of C. megacephala adults were prepared with four different larval densities (100, 200, 400 and 800). For each cage, two tables were made: one with demographic parameters for the life expectancy estimate at the initial age (eo), and another with the reproductive rate and average reproduction age estimates. Populational parameters such as the intrinsic growth rate (i) and thefinite growth rate (lambda) were calculated as well.

Growth and mortality of Cichla spp. (Perciformes, Cichlidae) introduced in Volta Grande Reservoir (Grande River) and in a small artificial lake in Southeastern Brazil

Os parâmetros de crescimento e mortalidade foram estimados indiretamente pelas distribuições das frequências de comprimento para espécies de Cichla spp. introduzidas em um lago em Leme (SP) e no reservatório de Volta Grande (SP-MG). em Leme, Cichla kelberi apresentou maior frequência nas classes de comprimentos inferiores, maior taxa instantânea de mortalidade natural e menor número de coortes do que C. kelberi e C. piquiti em Volta Grande. Os valores de performance de crescimento obtidos para as espécies foram próximos, corroborando a validade dos parâmetros estimados de crescimento e de mortalidade. A pressão em crescer rapidamente, devido à predação, aumenta quanto menor e menos diverso for o ambiente. O gênero Cichla adapta-se bem nos locais em que é introduzido, entretanto essa adaptação mostra-se fortemente ajustada a cada ambiente em particular, determinando com isso grande plasticidade e capacidade de estabelecimento.

Growth rates in modern speleothems from Santana Cave, Brazil, by the Pb-210-method

The Santana Cave is located at the Upper Ribeira Touristic State Park (PETAR-Parque Estadual Turistico do Alto Ribeira) in southern São Paulo State, Brazil. This paper describes Pb-210 activity concentration data in soda straw stalactites samples collected at Salao das Flores in Santana Cave that is a fossil tributary of the cave river. Non-expensive alpha counting following some analytical steps for extracting and depositing Pb-210 were used for providing the Pb-210 data. In the analyzed samples, Pb-210 values of increasingly older samples fitted an exponential curve, thus suggesting that the production of Pb-210 has been constant with time. Also, the near-ideal fit indicated that the growth was uniform and there was no break in the continuous growth. The soda straw growth rates were determined from the best fit to the exponential curve through the Pb-210 activity concentration. The results of the measurements allowed estimate a longitudinal rate corresponding to 1.3 mm/yr and a lateral rate of 0.01 mm/yr, which permitted calculate times of 70 years and 317-498 years for their formation, respectively. The lateral growth rate is compatible with values from studies of chemical weathering rates held under laboratory and natural conditions. (C) 2011 Elsevier Ltd. All rights reserved.

Demographic aspects of Chrysomya megacephala (Diptera, Calliphoridae) adults maintained under experimental conditions: reproductive rate estimates

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

Non-linear growth models for bullfrog tadpoles

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

Postweaning growth of the non-carcass components of Texel crossbred lambs

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

GROWTH OF OOCYTE AND NURSE CHAMBER DURING OOGENESIS IN QUEENS OF THE LEAF-CUTTING ANT ATTA SEXDENS RUBROPILOSA FOREL, 1908 (HYM, FORMICIDAE)

Volume changes of the vitellarium components of the leaf-cutting ant Atta sexdens rubropilosa are reported. The oocyte grew to approximately 409 times of its initial volume and reached a maximum value of 1.2 x 10(7) mu m(3). The follicle increase in size at a more or less constant rate up to the 12(th), showing an elevated growth rate thereafter. The mean number of follicles per ovariole was 16.42 +/- 3.58.