SOCIAL-CONTROL OF GROWTH IN FISH

This review concerns the phenomenon of heterogeneous growth (Het-G) in fish. Het-G is characterized by different growth rates between conspecifics. Although genetic determination on Het-G is recognized, grouping increases the difference in size between conspecifics. This review focuses on population factors and the mechanisms underlying the socially mediated Het-G are summarized and discussed. The aim of this paper is to arrive at a general statement explaining why grouping decreases mean growth and why it suppresses growth only in some individuals. The mechanisms described are: a) food competition, b) chemical factors released by conspecifics, and c) social stress. Social stress is analyzed in terms of the effect on appetite, digestive processes and metabolism. It is proposed that the predominant mechanism promoting socially mediated growth suppression is related to the social habit of the species. The biological significance of growth heterogeneity in fish is also discussed. Growth variability is suggested as an adaptative strategy to optimize survival of the population in a restricted space.

Growth responses and photosynthetic characteristics of wild and phycoerythrin-deficient strains of Hypnea musciformis (Rhodophyta)

The phycoerythrin-deficient strain (green phenotype) of Hypnea musciformis (Rhodophyta) originated from a green branch, which had arisen as a spontaneous mutation in a wild plant (brown phenotype) collected from the Brazilian coast. The present study describes the growth responses to irradiance, photoperiod and temperature variations, pigment contents, and photosynthetic characteristics of the brown and green strains of H. musciformis. The results showed that growth rates increased as a function of irradiance (up to 40 mu mol photons m(-2) s(-1)) but, with further increase in irradiance (from 40 to 120 mu mol photons m(-2) s(-1)), became light-saturated and remained almost unchanged. The highest growth rates of the brown and green strains were observed in temperatures of 20-25 degrees C under long (14:10 h LD) and short (10:14 h LD) photoperiods. The brown strain had higher growth rates than the green strain in the short photoperiod, which could be related to the high concentrations of phycobiliproteins. Phycoerythrin was not detected in the green strain. The brown strain had higher concentrations of allophycocyanin and phycoerythrin in the short photoperiod while the green strain had higher concentrations of phycocyanin. The brown strain presented higher photosynthetic efficiency (alpha), and lower saturation parameter (I-k) and compensation irradiance (I-c) than the green strain. The brown strain exhibited the characteristics of shade-adapted plants, and its higher value of photosynthetic efficiency could be attributed to the higher phycoerythrin concentrations. Results of the present study indicate that both colour strains of H. musciformis could be selected for aquaculture, since growth rates were similar (although in different optimal light conditions), as the green strain seems to be adapted to higher light levels than the brown strain. Furthermore, these colour strains could be a useful experimental system to understand the regulation of biochemical processes of photosynthesis and metabolism of light-harvesting pigments in red algae.

INFLUENCE OF DIETARY-PROTEIN INTAKE AND RECOMBINANT HUMAN SOMATOTROPIN ADMINISTRATION ON GROWTH AND BODY-COMPOSITION OF JUVENILE TAMBACU (A PIARACTUS-MESOPOTAMICUS X COLOSSOMA-MACROPOMUM CROSS)

This experiment was undertaken to study the interaction between level of dietary protein and recombinant human somatotropin (rhGH) administration on performance and body composition of juvenile tambacu (a crossbred Brazilian fish). A total of 72 juvenile tambacu, initially weighing and measuring (mean +/- s.e.m.) 23 +/- 2 g and 9 +/- 0.5 cm, respectively, were randomly divided into 18 groups of 4 fish each. Water temperature was 28 degrees C. Triplicate groups received one of two levels of dietary protein (15 and 30% as fed basis) and one of 3 doses of rhGH (0, 2 and 4 mu g/g) via intraperitoneal injection twice a week for 6 weeks, using a randomized complete block design. Somatotropin was noted to stimulate linear and body weight gain. The higher protein level supported increased growth in weight and length, but there was no interaction between protein level and rhGH dose for either parameter. Protein efficiency ratio and percentage protein deposited showed higher values on diets containing 15% protein. Somatotropin treatment did not significantly affect body composition, but there was a trend towards improved protein retention and reduced carcass lipid. In conclusion, the results of this experiment suggest that rhGH is able to stimulate linear gain in tambacu.

Comparative population biology of Uca rapax (Smith, 1870) (Brachyura, Ocypodidae) from two subtropical mangrove habitats on the Brazilian coast

The structure of two populations of the fiddler crab Uca rapax in two subtropical mangrove habitats near Ubatuba, State of São Paulo, Brazil were compared. The size - frequency distribution, sex ratio, and recruitment were evaluated. Sampling was performed monthly from April 2001 to March 2002 in the Itamambuca and Ubatumirim habitats. Crabs were caught manually for 15 min by two collectors during low tide. The carapace width of each crab was measured with a digital caliper, and the sex and ovigerous state were recorded. The median size of the carapace width of males was greater than that of females at both sites (P<0.05). The median size of the crabs from Itamambuca was larger than at Ubatumirim (P<0.05). Only 28 ovigerous females were obtained from both mangroves, which suggested that females might remain in their burrows during the incubation period. The highest recruitment pulse occurred in winter for both populations, probably as a consequence of high reproductive activity during summer. The sex ratio in the size classes showed an anomalous pattern, with a higher frequency of females in the intermediate size classes. This may be related to a greater energy requirement for reproduction in females, thus delaying growth. The variable environmental conditions to which Uca rapax populations are subject appear to act directly or indirectly on the population, causing variations in growth and reproductive processes in the different populations investigated here.

Stem anatomy of Lycopersicon esculentum Mill. treated with different plant growth regulators

The effects of plant growth regulators GA(3) 50 mg. L-1, NAA 100 mg. L-1, CCC 1500 mg.L-1 and SADH 3000 mg.L-1 on stem anatomy of Lycopersicon esculentum Mill cv. Angela Gigante were studied. Two sets of experiments were carried out in greenhouse during two separte periods. Anatomical studies,revealed that growth promoters induced increased xylem thickness and increased the number of tracheary elements while the growth retardants decreased xylem thickness and induced fiber formation.

EFFECT OF EXERCISE DURING PREGNANCY AND DAM AGE ON MATERNAL BLOOD-CHEMISTRY AND FETAL GROWTH

In order to determine the effect of maternal exercise on maternal nutritional status and fetal growth, young (Y = 45-50 days old) Wistar rats were divided into 4 groups of 5 to 8 animals: control pregnant (CP), control non-pregnant (CNP), exercise-trained (swimming 1 h/day, 5 days/week, for 19 days) pregnant (TP) and exercise-trained non-pregnant (TNP). Four equivalent groups of adult rats (A - 90-100 days old) were also formed. Serum glucose, total protein, albumin, hematocrit and liver glycogen were determined in female rats and pups. There were no statistical differences in serum glucose, total protein and albumin levels, litter size ot birth weight among exercise-trained animals, controls and their respective pups. Hematocrit was significantly lower in pups of exercise-trained young rats than in all other groups (YCP = 38.6 +/- 3.0; YTP = 32.6 +/- 2.1; ACP = 39.0 +/- 2.5; ATP = 39.2 +/- 2.9%). Liver glycogen levels were lower in pregnant than in non-pregnant rats but similar in exercise-trained and control rats of the same age and physiological status (YCNP = 4.1 +/- 0.2; YCP = 2.7 +/- 0.9; YTNP = 4.9 +/- 0.8; YTP = 2.7 +/-0.4; ACNP = 6.1 +/- 0.6; ACP = 3.1 +/- 0.8; ATNP = 6.6 +/- 0.8; ATP = 2.2 +/- 0.9 mg/100 mg). We conclude that pups of adult female rats are spared from the effects of this kind of exercise training during pregnancy. on the other hand, it appears that maternal adaptations to exercise training in young rats are able to preserve only some aspects of pup metabolism.

EFFECT OF ASCORBIC-ACID DEFICIENCY ON THE GROWTH, GILL FILAMENT LESIONS AND BEHAVIOR OF PACU FRY (PIARACTUS-MESOPOTAMICUS HOLMBERG, 1887)

The effect of ascorbic acid deficiency was determined in Piaractus mesopotamicus Holmberg, 1887, fish (pacu) under laboratory conditions. A total of 120 fish with an average body weight of 8.64 +/- 1.62 g and measuring 6.15 +/- 0.33 cm in length at the beginning of the experiment were fed diets containing 0, 50, 100 or 200 mg palmitate-coated ascorbic acid/kg dry ration for a period of 24 weeks with measurements every 4 weeks. The experiment was conducted in 20 fiber-cement aquaria of 81-liter capacity. Each aquarium was supplied with dechlorinated water at a flow rate of 1 l/min. Water temperature was measured daily and pH, dissolved oxygen, alkalinity and water conductivity were determined weekly. A fully randomized experimental design was utilized, with 5 replicates of each treatment and 6 fish per aquarium. Ascorbic acid-supplemented fish presented significantly increased growth when compared to unsupplemented fish. Furthermore, unsupplemented fish presented a higher incidence of hyperplasia, hypertrophy and dysplasia of the bone cartilage of gill filaments. The gill lamellae of unsupplemented fish had twisted cartilage and an inflammatory infiltrate at the ends. Anorexia and increased handling stress were also observed in fish fed the unsupplemented diet. The present study suggests that 50 mg ascorbic acid/kg dry ration is sufficient to improve development of pacu fingerlings but the optimum level under aquarium conditions, determined by regression analysis, is 139 mg ascorbic acid/kg dry ration.

Reproductive biology of the southern Brazilian pitviper Bothrops neuwiedi pubescens (Serpentes, Viperidae)

Dissection of 286 specimens of the Bothrops neuwiedi pubescens, combined with data on captive individuals, provided information on the reproductive biology of this viperid snake from southern Brazil. Females attained larger body sizes than males, and reproduction was seasonal with mating taking place in autumn when males were more frequently encountered. Vitellogenesis occurred from summer to spring (January-September), sperm storage during autumn and winter (May-September), ovulation and fertilization in early spring (September), embryonic development during middle spring and summer (October-March), and parturition in the summer (January-March). Embryonic development was estimated to last from three to five months, a shorter time than was previously reported. The number of offspring of Bothrops neuwiedi pubescens born in one litter can vary from four to 25 ((x) over bar = 11). Fecundity is correlated with maternal body size. Neonates measure 17-25 cm SVL. Inferred growth rate of juveniles was low (10 mm/month in first year), with males attaining sexual maturity at about 16 months, but maturity is delayed in females for at least two additional years.

Multivariated variance analysis applied to biological experiments: An analysis with curves of rats teeth growth as influenced by colchicine

The evaluation of the growth of incisor teeth of rats as influenced by colchicine (doses of 25, 50, 100 and 200 μg/kg) injected during 10 and 18 days is performed using a multivariated variance analysis, which allowed a global view of the results, showing that: there are differences in the growth of teeth of control group (untreated rats) and those treated with colchicine, in the measurements made at the 4th, 7th and 10th days of experiment); there is no difference in the growth of the teeth between the groups treated during 10 and 18 days, except in the measurements made at the 7th day; there is no influence of the doses of colchicine in the group treated during 10 days and in the group treated during 18 days - only at the 7th day is observed an influence of the doses used; and there was no significant interaction between treatment and days of measurement, showing the similarity of the groups during the experiment.

Inflation and relative prices: the Brazilian experience, 1970/79.

Based on behaviour of output growth and industrial sector prices, it tries to define the several stages comprising the cyclic trends of the Brazilian economy. Analyzes the behaviour of inflation rates and of relative prices, and shows that there is a positive association between the measures of inflation rates and of their variables as well as between both these measures and dispersion of relative price changes. Demonstrates the assymetric behaviour of relative price changes and differentiated behaviour in relative prices of farm produce and industrial products. -from Authors

Nutritional management and weight changes during hospitalization of Brazilian infants with diarrhoea: Primary reliance on oral feeding or continuous nasogastric drip with locally made, modulated minced chicken formula

The nutritional management of infants admitted with diarrhoea to the University Hospital of Botucatu includes a change from bolus feeding of a modulated minced-chicken formula to a continuous nasogastric drip (NGD) feeding, whenever the required calorie intake is not achieved or the diarrhoea does not subside. To evaluate this approach, the clinical course and weight changes of 63 children, aged 1-20 months, were reviewed; most (81 per cent) were below the third percentile for weight at admission and 76 per cent had a total duration of diarrhoea ≥10 days. Associated infections, mainly systemic, were present at or after admission in 70 per cent of them. Twenty-five survivors needed nutritional support (NS), predominantly NGD, for a median duration of 30 per cent of their admission time, and were compared to 31 survivors managed without NS. Those who necessitated NS lost weight for a significantly longer median time (12x4 days, p<0.005), but their total weight loss was similar (5x4 per cent) as well as diarrhoea's duration (8x7 days). There was a tendency for a longer hospitalization (21x16 days 0.05growth quotient and daily weight gain during admission were similar for both groups. Both groups of survivors received similar amounts of energy, although the initial increase was delayed for those who needed the NGD. Seven infants (11 per cent) died, most of overwhelming infection, and presented a high total weight loss, albeit receiving NS for 71 per cent of their admission's time. It was concluded that feeding diarrhoeic infants with a NGD when necessary, possibly prevented a greater nutritional insult for the survivors. The NGD can be safely employed and should be valued, provided weight losses are carefully monitored in order to detect infants at highest risk.