Nutritional status response of Daphnia laevis and Moina micura from a tropical reservoir to different algal diets: Scenedesmus quadricauda and Ankistrodesmus gracilis

The accumulation of lipid reserves was investigated in two common cladoceran species typical of neotropical freshwaters. Experiments were performed in order to measure differential accumulation of lipid reserves in response to two algal diets, S. quadricauda and A. gracilis. The larger D. laevis fed with the Ankistrodesmus diet accumulated a higher amount of total lipids. The average lipid content for both diets was 11.1 percent and 22.1 percent dry weight for Scenedesmus and Ankistrodemsus, respectively. This difference was found to be highly significant. The superior nutritional quality of A. gracilis was confirmed by the experiments using the smaller Moina micrura. This cladoceran accumulated 11.4 percent and 19.9 percent of the average dry weight of lipids from Scenedesmus and Ankistrodesmus, respectively. The study also found that most lipid reserves are concentrated as triacylglycerols in both cladocerans. The relative contribution of this class of lipids also varied according to the diet. For Daphnia, for instance, the average triacylglycerol levels varied from 6.2 to 11.0 with the Scenedesmus and Ankistrodesmus diets, respectively

Nutritional status response of daphnia laevis and Moina micrura from a tropical reservoir to different algal diets: Scenedesmus quadricauda and Ankistrodesmus gracilis.

The accumulation of lipid reserves was investigated in two common cladoceran species typical of neotropical freshwaters. Experiments were performed in order to measure differential accumulation of lipid reserves in response to two algal diets, S. quadricauda and A. gracilis. The larger D. laevis fed with the Ankistrodesmus diet accumulated a higher amount of total lipids. The average lipid content for both diets was 1.1% and 22.1% dry weight for Scenedesmus and Ankistrodemsus, respectively. This difference was found to be highly significant. The superior nutritional quality of A. gracilis was confirmed by the experiments using the smaller Moina micrura. This cladoceran accumulated 11.4% and 19.9% of the average dry weight of lipids from Scenedesmus and Ankistrodesmus, respectively. The study also found that most lipid reserves are concentrated as triacylglycerols in both cladocerans. The relative contribution of this class of lipids also varied according to the diet. For Daphnia, for instance, the average triacylglycerol levels varied from 6.2 to 11.0 with the Scenedesmus and Ankistrodesnus diets, respectively.

Diel variations in respiration, excretion rates, and nutritional status of zooplankton from the Pampulha Reservoir, Belo Horizonte, MG.

This investigation is focused on the experimental determination of diel cycles of metabolic activity of zooplankton in a tropical reservoir. Water and zooplankton used in laboratory experiments were collected from the Pampulha reservoir. The experimental units were incubated in the light (1500 Lux) and in the dark at 25.0 +/- 1.0 degrees C during different periods of the diel cycle. At the end of each experiment, the following variables were measured: temperature, dissolved oxygen, ammonia, and orthophosphate as well as the composition, abundance and dry weight of the zooplankton. The specific respiration and excretion rates were determined considering the differences in concentration between experimental and control units. The effect of diurnal cycle on respiration rates was clearly more intense than the effect of light. The average values of respiration rates obtained in the morning hours oscillated between 0. 015 and 0.016 mgO(2)mgDW. hr(-1) (light and dark incubations). At night, these rates were higher and ranged from 0.020 to 0.035 mgO(2)mgDW. hr(-1). Increased biomass of zooplankton and longer incubation times produced lower respiration rates. The excretion rates of ammonia were higher at night, reaching a mean value of 4.2 microgN-NH(4)/mg DW. hr(-1) in illuminated units. The phosphate excretion rates were more elevated in the morning, reaching 0.58 microgP-PO(4)/mg/DW. hr(-1) illuminated vessels. The nanoplankton was able to actively absorb ammonia as well as phosphate. The highest ammonia absorption rates were measured at night, whereas the nanoplankton absorbed phosphorus only in the morning hours. The nutritional status of zooplankton also showed short-term variations. The mean phosphorus content of zooplankton biomass also varied between day and night as well as with incubation time. It ranged from 0.58-2.17%, whereas organic matter variation was more conservative, oscillating around 70-92% in all occasions.

Leiomyosarcoma of the esophagus in a patient with chagasic megaesophagus: case report and literature review.

Leiomyosarcoma constitutes approximately 0.5% of the malignant neoplasias of the esophagus and its association with megaesophagus has not been described. We report on a case of a woman with dysphagia that was slowly progressive from the age of 19 due to chagasic megaesophagus. The woman was subjected to cardiomyotomy at the age of 49. She presented a rapid worsening of the dysphagia due to leiomyosarcoma at the age of 61, and was subjected to subtotal esophagectomy with cervical esophagogastroplasty. She developed pulmonary and hepatic metastases 14 months after surgery and died six months later.

Water maze learning in rats with neocortical and hippocampal lesions.

Experiments were carried out in order to determine whether groups of rats (N = 7) with unilateral or bilateral ablation of the neocortex or with removal of the neocortex plus the hippocampus of either hemisphere could learn to escape from a tank of water (57 cm in diameter) climbing a visible platform when trained for 6 consecutive days. Comparison of the swimming escape latencies among groups showed no statistically significant differences, although over the first four trial blocks the decorticate group was slower (77.19 +/- 39.31, 52.45 +/- 32.37, 31.18 +/- 13.62 and 15.74 +/- 10.94 s, respectively) than the other groups, whose latencies ranged from about 70 s (the longest in the first trial block) to 8 s (the longest in the fourth trial block). Nevertheless, hemi- and bilaterally decorticate rats were still able to learn the water maze task. The same was observed for hemidecorticate plus hemihippocampectomized rats. These results indicate that the neocortex, and the hippocampus in the absence of the neocortex, is not essential for spatial localization using a cue-learning strategy.

Water maze learning in rats with neocortical and hippocampal lesions

Experiments were carried out in oreder to determine whether groups of rats (N+7) with unilateral or bilateral ablation of the neocortex or with removal of the neocortex plus the hippocampus of either hemisphere could learn to escape from a tank of water (57 cm in diameter) by climbing a visible platform when trained for 6 consecutive days. Comparison of the swimming escape latencies among groups showed no statistically significant differences, although over the first four trial blocks the decorticate group was slower (77.19 ñ 39.31, 52.45 ñ 32.37, 31.18 ñ 13.62 and 15.74 ñ 10.94 s, respectively) than the other groups, whose latencies ranged from abouth 70 s (the longest in the first trial block) to 8 s (the longest in the fourth trial block). Nevertheless, hemi-and bilateral decoricate rats were still able to learn the water maze task. The same was observed for hemidecorticate plus hemihippocampectomized rats. These results indicate that the neocortex and the hippocampus in the absence of the neocortex, is essential for spatial localization using a cue-learning strategy