Boosting the suppressive effects of Ascaris suum components in IFN-γ-deficient mice

High molecular weight components from Ascaris suum extract suppress ovalbumin-specific immunity in mice. In IFN-γ-deficient mice, ovalbumin-specific delayed-type hypersensitivity reactions are more strongly downregulated by these suppressive components. Here, the cellularity of the delayed-type hypersensitivity reaction in IFN-γ-deficient mice and the increased downregulation induced by Ascaris suum components were analyzed. IL-12p40-dependent neutrophilic influx was predominant. Suboptimal doses of the suppressive fraction from this nematode completely inhibited the hypersensitivity reaction, thus indicating intensification of the immunosuppression under conditions of intense recruitment of IFN-γ-independent neutrophils.

The effects of a diet formulation with oats, soybeans, and flax on lipid profiles and uricemia in patients with AIDS and dyslipidemia

Introduction Although the initiation of highly active antiretroviral therapy (HAART) is accompanied by an attenuation of viral load, metabolic disorders characterized by hyperglycemia, dyslipidemia, and lipodystrophy are often observed in patients under this treatment. Certain foods, such as oat bran, soy protein, and flaxseed, have been shown to improve a patient's lipid profile despite possible increases in uricemia. Thus, a bioactive compound was formulated using these foods to help patients with HIV/AIDS control metabolic disorders resulting from HAART. Methods An uncontrolled before and after study was performed. The total cholesterol, HDL-cholesterol, LDL-cholesterol, triglycerides, and uric acid before and after 3 months of consuming the formulation were compared in patients. The compound was formulated such that 40g (the recommended daily intake) contained approximately 10g of flaxseed, 20g of oat bran, and 10g of textured soy protein. Results The study population consisted of 139 patients, 31 of whom were included in the final analysis. There were no significant variations between the laboratory results obtained before and after consumption of the compound. Conclusions The regular consumption of the formulation together with individualized dietary guidance did not reduce lipid levels and did not contribute to an increase in uricemia in the study group. However, new studies with higher doses of the foods that compose the formulation should be encouraged to investigate whether these foods can positively influence the lipid profiles of these patients.

The effects of glutamine-supplemented diet on the intestinal mucosa of the malnourished growing rat

Glutamine is the most abundant amino acid in the blood and plays a key role in the response of the small intestine to systemic injuries. Mucosal atrophy is an important phenomenon that occurs in some types of clinical injury, such as states of severe undernutrition. Glutamine has been shown to exert powerful trophic effects on the gastrointestinal mucosa after small bowel resection or transplant, radiation injury, surgical trauma, ischemic injury and administration of cytotoxic drugs. Since no study has been performed on the malnourished animal, we examined whether glutamine exerts a trophic effect on the intestinal mucosa of the malnourished growing rat. Thirty-five growing female rats (aged 21 days) were divided into 4 groups: control - chow diet; malnutrition diet; malnutrition+chow diet; and malnutrition+glutamine-enriched chow diet (2%). For the first 15 days of the experiment, animals in the test groups received a malnutrition diet, which was a lactose-enriched diet designed to induce diarrhea and malnutrition. For the next 15 days, these animals received either the lactose-enriched diet, a regular chow diet or a glutamine-enriched chow diet. After 30 days, the animals were weighed, sacrificed, and a section of the jejunum was taken and prepared for histological examination. All the animals had similar weights on day 1 of experiment, and feeding with the lactose-enriched diet promoted a significant decrease in body weight in comparison to the control group. Feeding with both experimental chow-based diets promoted significant body weight gains, although the glutamine-enriched diet was more effective. RESULTS: The morphological and morphometric analyses demonstrated that small intestinal villous height was significantly decreased in the malnourished group, and this change was partially corrected by the two types of chow-based diet. Crypt depth was significantly increased by malnutrition, and this parameter was partially corrected by the two types of chow-based diet. The glutamine-enriched diet resulted in the greatest reduction of crypt depth, and this reduction was also statistically significant when compared with control animals. CONCLUSIONS: Enteral glutamine has some positive effects on body weight gain and trophism of the jejunal mucosa in the malnourished growing rat.

The role of s-nitrosothiols and rho-kinase 1 in glucose and lipid metabolism

RESUMO: Na sociedade contemporânea a diabetes tipo 2 e a obesidade estão a aumentar exponencialmente, representando um grave problema de saúde pública. De acordo com a IDF “A diabetes e a obesidade são o principal problema de saúde pública do século XXI’. Para além destas duas patologias, a prevalência de esteatose hepática não-alcoólica (NAFLD), entre a população obesa e diabética, é de cerca de 90%. O aumento da obesidade, diabetes e NAFLD tem uma forte correlação com o aumento do consumo de gorduras e açúcares, acompanhado de um decréscimo acentuado da actividade física. A obesidade, diabetes e NAFLD tem sido escrupolosamente investigada mas as terapêuticas disponíveis continuam a ser muito limitadas. Tendo em conta o número crescente e alarmante de obesos e diabéticos o conhecimento detalhado da patofisiologia da obesidade, diabetes e NAFLD, tendo em vista a necessidade extrema de desenvolvimento de novas estratégias terapêuticas, é da mais elevada urgência. O fígado é reconhecido como um orgão primordial no controlo da homeostase. No estado pós-prandial, o fígado converte a glucose em glicogénio e lípidos. Em contraste, no estado de jejum, o fígado promove a produção de glucose. Sistemas neuronais e hormonais, bem como o estado metabólico do fígado, controlam de forma muito precisa a alternância entre os diferentes substratos metabólicos, dependente do estado prandial. A insulina tem um papel central no controlo do metabolismo energético no fígado; se, por um lado, inibe a produção hepática de glucose e corpos cetónicos, por outro, promove a glicólise e a lipogénese. O metabolismo energético no fígado é também regulado por vários factores de transcrição e co-reguladores que, por sua vez, são regulados pela insulina, glucagina e outras hormonas metabólicas. Em conjunto, todos estes factores e reguladores vão controlar de forma muito estreita a gluconeogénese, a β-oxidação e a lipogénese, no fígado. Para além dos já conhecidos reguladores do metabolismo hepático, novas moléculas têm sido estudadas como tendo um papel fundamental na regulação do metabolismo energético no fígado. Qualquer desequilíbrio no metabolismo hepático vai contribuir para a insulino-resistência, NAFLD e diabetes tipo 2. O principal objectivo do trabalho de investigação aqui apresentado é o contributo para o estudo detalhado da patogénese da diabetes e obesidade, num contexto de dietas ricas em açúcares e gorduras, e com a perspectiva de explorar novas estratégias terapêuticas. Os objectivos específicos deste trabalho eram: primeiro, determinar se o tratamento com glutationo (GSH) e óxido nítrico (NO) era suficiente para melhorar a insulino-resistência associada ao elevado consumo de sacarose; segundo, determinar o papel da Rho-kinase 1 (ROCK1) na regulação do metabolismo hepático da glucose e dos lípidos; e terceiro, estudar o efeito do metilsulfonilmetano (MSM) em doenças metabólicas associadas à obesidade. Na primeira parte deste trabalho de investigação foram utilizados ratos Wistar machos sujeitos a uma dieta rica em sacarose (HS). Tal como esperado, estes animais apresentavam insulino-resistência e hiperinsulinémia. A dieta HS levou ao aumento dos níveis hepáticos de NO e ao decréscimo dos níveis de GSH no fígado. Em jejum, a administração intraportal de GSH e NO, a animais saudáveis promoveu um aumento significativo da sensibilidade à insulina. Também nestes animais, a administração intravenosa de S-nitrosotióis, compostos orgânicos que contém um grupo nitroso acoplado a um átomo de enxofre de um tiol, promoveu o aumento significativo da sensibilidade à insulina. Pelo contrário, em animais sujeitos à dieta HS, as doses padrão de GSH + NO e de S-nitrosotióis não conseguiram promover o aumento da sensibilidade à insulina. No entanto, ao aumentar a dose de S-nitrosotióis administrados por via intravenosa, foi possível observar o aumento da sensibilidade à insulina dependente da dose, indicando um possível papel dos S-nitrosotióis como sensibilizadores de insulina. O estudo detalhado do papel dos S-nitrosotióis na via de sinalização da insulina revelou que há um aumento da fosforilação do receptor da insulina (IR) e da proteína cinase B (Akt), sugerindo um efeito dos S-nitrosotióis nesta via de sinalização. Os resultados apresentados nesta primeira parte sugerem que os S-nitrosotióis promovem a correcta acção da insulina, podendo vir a ser importantes alvos terapêuticos. Na segunda parte deste trabalho de investigação utilizámos murganhos, com uma delecção específica da ROCK1 no fígado, e sujeitos a uma dieta rica em lípidos (HFD). Foi possível concluir que a ausência da ROCK1 no fígado previne a obesidade, melhora a sensibilidade à insulina e protege contra a esteatose hepática. A ausência de ROCK1 no fígado levou a um decréscimo significativo da expressão génica de genes associados à lipogénese, com uma diminuição acentuada do fluxo metabólico associado a esta via. Pelo contrário, a sobreexpressão de ROCK1, exclusivamente no fígado, promove a insulino-resistência e a esteatose hepática no contexto de obesidade induzida pela dieta. Para além disto, a delecção da ROCK1 no fígado de animais obesos e diabéticos, os murganhos deficientes em leptina, corroborou os dados obtidos no primeiro modelo animal, com a franca melhoria da hiperglicémia, hiperinsulinémia e esteatose hepática. Os dados que compõem esta parte do trabalho de investigação sugerem que a ROCK1 tem um papel crucial na regulação do metabolismo lipídico. Na terceira e última parte deste trabalho de investigação foi investigado o efeito do composto metilsulfunilmetano (MSM), um composto organosulfúrico naturalmente presente em plantas e utilizado também como suplemento dietético, em murganhos obesos e insulino-resistentes, por exposição a uma dieta rica em lípidos (DIO). O tratamento com MSM melhorou a insulino-resistência e protegeu contra a esteatose hepática. O conteúdo hepático em triglicéridos e colesterol também diminuíu de forma significativa nos animais DIO sujeitos ao tratamento com MSM, bem como a expressão génica associada à lipogénese. Para além disto, o tratamento com MSM levou a uma diminuição da expressão génica associada à inflamação. De realçar que o tratamento com MSM levou a uma melhoria do perfil hematopoiético destes animais, tanto na medula óssea como no sangue. Para comprovar o efeito benéfico do MSM na obesidade e insulino-resistência utilizámos murganhos deficientes no receptor da leptina, e por isso obesos e diabéticos, tendo observado um perfil semelhante ao obtido para murganhos sujeitos a uma dieta rica em lípidos e tratados com MSM. Concluímos, através dos dados recolhidos, que o MSM como suplemento pode ter efeitos benéficos na hiperinsulinémia, insulino-resistência e inflamação que caracterizam a diabetes tipo 2. Em resumo, os dados obtidos neste trabalho de investigação mostram que os S-nitrosotióis podem ter um papel importante como sensibilizadores da insulina, promovendo um aumento da sensibilidade à insulina num contexto de dietas ricas em sacarose. Para além disto, estudos in vitro, sugerem que os S-nitrosotióis regulam, especificamente, a via de sinalização da insulina. Este trabalho teve também como objectivo o estudo da ROCK1 como regulador do metabolismo da glucose e dos lípidos no fígado. Através do estudo de animais com uma delecção ou uma sobreexpressão da ROCK1 no fígado mostrou-se que esta tem um papel crucial na patogénese da obesidade e diabetes tipo 2, especificamente através do controlo da lipogénese de novo. Finalmente, foi também objectivo deste trabalho, explorar o efeito do MSM em animais DIO e deficientes em leptina. O tratamento com MSM protege de forma evidente contra a obesidade e insulino-resistência, com especial enfâse para a capacidade que esta molécula demonstrou ter na protecção contra a inflamação. Em conjunto os vários estudos aqui apresentados mostram que tanto os S-nitrosotióis como a ROCK1 têm um papel na patogénese da obesidade e diabetes tipo 2 e que a utilização de MSM como suplemento às terapêuticas convencionais pode ter um papel no tratamentos de doenças metabólicas.-------------------------------ABSTRACT: In modern western societies type 2 diabetes and obesity are increasing exponentially, representing a somber public concern. According to the International Diabetes Federation (IDF) ‘Diabetes and Obesity are the biggest public health challenges of the 21st century’. Aside from these the prevalence of nonalcoholic fatty liver disease (NAFLD), among the diabetic and obese population, is as high as 90%. It is now well established that the increase in obesity, diabetes and NAFLD strongly correlates with an increase in fat and sugar intake in our diet, alongside physical inactivity. The pathogenesis of obesity, diabetes and NAFLD has been thoroughly studied but the treatment options available are still narrow. Considering the alarming number in the obese and diabetic population the complete understanding of the pathogenesis, keeping in mind that new therapeutic strategies need to be attained, is of the highest urgency. The liver has been well established as a fundamental organ in regulating whole-body homeostasis. In the fed state the liver converts the glucose into glycogen and lipids. Conversely, in the fasted state, glucose will be produced in the liver. Neuronal and hormonal systems, as well as the hepatic metabolic states, tightly control the fast to fed switch in metabolic fuels. Insulin has a central role in controlling hepatic energy metabolism, by suppressing glucose production and ketogenesis, while stimulating glycolysis and lipogenesis. Liver energy metabolism is also regulated by various transcription factors and coregulators that are, in turn, regulated by insulin, glucagon and other metabolic hormones. Together, these regulators will act to control gluconeogenesis, β-oxidation and lipogenesis in the liver. Aside from the well-established regulators of liver energy metabolism new molecules are being studied has having a role in regulating hepatic metabolism. Any imbalance in the liver energy metabolism is a major contributor to insulin resistance, NAFLD and type 2 diabetes. The overall goal of this research work was to contribute to the understanding of the pathogenesis of diabetes and obesity, on a setting of high-sucrose and high-fat diets, and to explore potential therapeutic options. The specific aims were: first, to determine if treatment with glutathione (GSH) and nitric oxide (NO) was sufficient to ameliorate insulin resistance induced by high-sucrose feeding; second, to determine the physiological role of rho-kinase 1 (ROCK1) in regulating hepatic and lipid metabolism; and third, to study the effect of methylsulfonylmethane (MSM) on obesity-linked metabolic disorders. In the first part of this research work we used male Wistar rats fed a high-sucrose (HS) diet. As expected, rats fed a HS diet were insulin resistant and hyperinsulinemic. HS feeding increased hepatic levels of NO, while decreasing GSH. In fasted healthy animals administration of both GSH and NO, to the liver, was able to increase insulin sensitivity. Intravenous administration of S-nitrosothiols, organic compounds containing a nitroso group attached to the sulfur atom of a thiol, in fasted control animals also increased insulin sensitivity. Under HS feeding the standard doses of GSH + NO and S-nitrosothiols were unable to promote an increase in insulin sensitivity. However, the intravenous administration of increasing concentrations of S-nitrosothiols was able to restore insulin sensitivity, suggesting that S-nitrosothiols have an insulin sensitizing effect. Investigation of the effect of S-nitrosothiols on the insulin signaling pathway showed increased phosphorylation of the insulin receptor (IR) and protein kinase B (Akt), suggesting that S-nitrosothiols may have an effect on the insulin signaling pathway. Together, these data showed that S-nitrosothiols promote normal insulin action, suggesting that they may act as potential pharmacological tools. In the second part of this research work we used liver-specific ROCK1 knockout mice fed a high-fat (HF) diet. Liver-specific deletion of ROCK1 prevented obesity, improved insulin sensitivity and protected against hepatic steatosis. Deficiency of ROCK1 in the liver caused a significant decrease in the gene expression of lipogenesis associated gene, ultimately leading to decreased lipogenesis. Contrariwise, ROCK1 overexpression in the liver promoted insulin resistance and hepatic steatosis in diet-induced obesity. Furthermore, liver-specific deletion of ROCK1 in obese and diabetic mice, the leptin-deficient mice, improved the typical hyperglycemia, hyperinsulinemia and liver steatosis. Together, these data identify ROCK1 as a crucial regulator of lipid metabolism. In the third and final part of this research work we investigated the effect of MSM, an organosulfur compound naturally found in plants and used as a dietary supplement, on diet-induced obese (DIO) and insulin resistant mice. MSM treatment ameliorated insulin resistance and protected against hepatosteatosis. Hepatic content in triglycerides and cholesterol was significantly decreased by MSM treatment, as well as lipogenesis associated gene expression. Furthermore, MSM treated mice had decreased inflammation associated gene expression in the liver. Importantly, FACS analysis showed that MSM treatment rescued the inflammatory hematopoietic phenotype of DIO mice in the bone marrow and the peripheral blood. Moreover, MSM treatment of the obese and diabetic mice, the leptin-deficient mice, resulted in similar effects as the ones observed for DIO mice. Collectively, these data suggest that MSM supplementation has a beneficial effect on hyperinsulinemia, insulin resistance and inflammation, which are often found in type 2 diabetes. In conclusion, this research work showed that S-nitrosothiols may play a role as insulin sensitizers, restoring insulin sensitivity in a setting of high-sucrose induced insulin resistance. Furthermore, in vitro studies suggest that S-nitrosothiols specifically regulate the insulin signaling pathway. This research work also investigated the role of hepatic ROCK1 in regulation of glucose and lipid metabolism. Using liver-specific ROCK 1 knockout and ROCK1 overexpressing mice it was shown that ROCK1 plays a role in the pathogenesis of obesity and type 2 diabetes, specifically through regulation of the de novo lipogenesis pathway. Finally, this research work aimed to explore the effect of MSM in DIO and leptin receptor-deficient mice. MSM strongly protects against obesity and insulin resistance, moreover showed a robust ability to decrease inflammation. Together, the individual studies that compose this dissertation showed that S-nitrosothiols and ROCK1 play a role in the pathogenesis of obesity and type 2 diabetes and that MSM supplementation may have a role in the treatment of metabolic disorders.

Weight loss and morphometric study of intestinal mucosa in rats after massive intestinal resection: influence of a glutamine-enriched diet

Short-bowel syndrome is responsible for significant metabolic alterations that compromise nutritional status. Glutamine is considered an essential nutrient for enterocytes, so beneficial effects from supplementation of the diet with glutamine are hypothesized. PURPOSE: In this study, the effect of a diet enriched with glutamine was evaluated in rats undergoing extensive small bowel resection, with analysis of postoperative weight loss and intestinal morphometrics of villi height, crypt depth, and thickness of the duodenal and remnant jejunal mucosa. METHODS: Three groups of male Wistar rats were established receiving the following diets: with glutamine, without glutamine, and the standard diet of laboratory ration. All animals underwent an extensive small bowel resection, including the ileocecal valve, leaving a remnant jejunum of only 25 cm from the pylorus that was anastomosed lateral-laterally to the ascendant colon. The animals were weighed at the beginning and end of the experiment (20th postoperative day). Then they were killed and the remnant intestine was removed. Fragments of duodenal and jejunal mucosa were collected from the remnant intestine and submitted to histopathologic exam. The morphometric study of the intestinal mucosa was accomplished using a digital system (KS 300) connected to an optic microscope. Morphometrics included villi height, crypt depth, and the total thickness of intestinal mucosa. RESULTS: The weight loss comparison among the 3 groups showed no significant loss difference. The morphometric studies showed significantly taller duodenal villi in the glutamine group in comparison to the without glutamine group, but not different from the standard diet group. The measurements obtained comparing the 3 groups for villi height, crypt depth, and thickness of the remnant jejunum mucosa were greater in the glutamine-enriched diet group than for the without-glutamine diet group, though not significantly different from with standard-diet group. CONCLUSIONS: In rats with experimentally produced short-bowel syndrome, glutamine-enrichment of an isonitrogenous test diet was associated with an improved adaptation response by the intestinal mucosa but not reduced weight loss. However, the adaptation response in the group receiving the glutamine-enriched diet was not improved over that for the group fed regular chow.

Habitat preferences, diet, feeding strategy and social organization of the black spider monkey [Ateles paniscus paniscus Linnaeus 1758] in Surinam

A Socioecological Field Study.This monograph reports on a 26 month socioecological study of black spider monkeys (Ateles paniscus paniscus)in the Raleigh-vallen — Voltzberg Nature Reserve, Surinam. It recognizes the fundamental importance of food to the behavior and the regulation of population density fox this primate. It clarifies the complex temporal and spatial effects of tropical rain forest food sources on the behavior of a group of spider monkeys, concentrating on food category, food plant identity and phenology, and quantity, density and dispersion of the most important food sources. In addition, the present study describes habitat choice, optimal feeding strategy and sexual behavior of the spider monkey, and discusses implications of diet for social behavior. This study is also fundamental to conservation. Specialized in eating mature fruits, the spider monkey is a very important dispersal agent for many trees and lianes, particularly canopy species. However, the spider monkey is probably the most vulnerable monkey species in Surinam and it is disappearing rapidly throughout the remainder of its range. Unfortunately, it is large and noisy and can be easily tracked and hunted. It is largely restricted to undisturbed high forest, and consequently habitat destruction has more effect on it than on most other species. Together with its slow reproductive rate (a female gives birth only once every four or five years), this means that the species is poorly adapted to recover from exploitation. In order to implement proper measures for conservation, data on forest type preferences, diet and social behavior of the species, or on closely related species, in undisturbed areas, such as the one described in this monograph, are essential tools for assessing the potential of proposed protected areas.

Cross-presentation by WASp deficient B cells and dendritic cells

The immune system comprises of different cell types whose role is to protect us against pathogens. This thesis investigates a very important mechanism for our organism protection in a specific disorder: cross-presentation in Wiskott-Aldrich Syndrome (WAS). WAS is caused by loss-of-function mutations in the cytoskeletal regulator WASp and WAS patients suffer from eczema, thrombocytopenia, and immunodeficiency. X-linked neutropenia (XLN) is caused by gain-of-function mutations in WASp and XLN patients suffer from severe congenital neutropenia and immunodeficiency. This thesis was focused on the role of B and T lymphocytes and dendritic cells (DCs). This work will be divided into two main topics: 1) In the first part I studied the capacity of B cells to take up, degrade and present antigen. Moreover I studied the capacity of B cells to induce T cell proliferation. 2) In the second part, I studied T cell proliferation induced by dendritic cells. To increase our understanding about this mechanism, additional experiments were performed, including acidification capacity of CD8+ and CD8- DCs, reactive oxygen species (ROS) production since it is directly connected to acidification. These assays were measured by flow cytometry. Localization of Rac1 and Rac2 GTPases was assessed by confocal microscopy. Proliferation, acidification and ROS production assays were performed also with cells from X-linked neutropenia (XLN) mice. From this study we concluded that B cells cannot induce CD8+ T cell proliferation however they take up and present antigen. Moreover I have shown that increased cross-presentation by WASp KO DCs with ovalbumin is associated with decreased capacity to acidify endosomal compartment; and WASp KO CD8- DCs have increased Rac2 localization to the phagosome. XLN dendritic cells have similar acidification and ROS production capacity than wildtype cells. In conclusion, our data suggests that WASp regulates antigen processing and presentation in DCs.

Omnivory and resource - sharing in nutrient - deficient Rio Negro waters: stabilization of biodiversity?

Amazonian biodiversity is notorious, this is also valid for the fauna of the mineral-deficient waters of the Rio Negro System. Some 25 years of research on the benthic fauna of Central Amazonian streams resulted in species-rich foodwebs with a high degree of omnivory within dense animal communities. To exemplify the taxonomic range of omnivorous consumers, the detailed resource spectra of 18 consumer species, including Protozoa (2 species), Platyhelminthes (1 species), insects (2 species), fish (6 species) and shrimps (Decapoda, 7 species), associated primarily with the benthic habitats of Rio Negro tributaries, are presented. Special features of omnivory are characterized, and the importance of litter-decomposing fungi as essential energy input into the foodwebs is documented. It is shown that general omnivory -diverse omnivore consumers sharing most of the resource types- is a prevalent feature. The relevance of this general omnivory for the maintenance of biodiversity is discussed.

Spousal support and satisfaction with healthcare services as moderators between psychological morbidity and adherence to diet in Type 2 Diabetes patients

Objectives: This study analyzed the moderating role of partners’ support and satisfaction with healthcare services in the relationship between psychological morbidity and adherence to diet in patients with type 2 diabetes (T2DM). Methods: Participants were 387 recently diagnosed T2DM patients that answered the following instruments: Revised Summary of Diabetes Self- Care Activities Measure, Hospital Anxiety and Depression Scales, Multidimensional Diabetes Questionnaire and Patient Satisfaction Questionnaire. Results: Partners’ positive and negative support moderated the relationship between psychological morbidity and adherence to diet. Satisfaction with healthcare services also moderated the relationship between psychological morbidity and adherence to diet. Conclusions: Intervention programs to promote adherence to diet in patients with type 2 diabetes should focus on partners’ support and patient satisfaction with healthcare services.

Natural diet and feeding habits of a freshwater prawn (Macrobrachium carcinus: Crustacea, Decapoda) in the estuary of the Amazon River

Macrobrachium carcinus is a Brazilian native prawn with recognized potential for use in aquaculture activities. However, there is little information about the natural diet and feeding habits of this species. The aim of this study was the identification of the diet items of M. carcinus based on the analysis of the stomach contents. Specimens were collected in the Amazon River estuary between January 2009 and January 2010. The stomach analysis was carried out by using the frequency of occurrence (FO), methods of points (MP) and feeding index (FI). It was observed that prawns fed on detritus, animals and plant fragments as the most important food items. Sediment accounted for the main stomach content, accounting for 43.2% by the MP, 44.9% by FI and 100% by the FO. Sexual differences in feeding preferences were not found in this study, and seasonal differences in the frequency of items ingested by M. carcinus were not observed. The results indicated that M. carcinus can be considered omnivorous species, but with an important carnivorous component, similar to that found in other Macrobrachium species.

The seasonal diet of Aequidens tetramerus (Cichlidae) in a small forest stream in the Machado River basin, Rondônia, Brazil

Trophic relationships in fish communities are affected by the availability of resources, which in turn is affected by spatial and temporal variations throughout the year. The aims of this study were to characterize the diet of A. tetramerus in a streamlet in the north of Brazil and compare its composition in different hydrological seasons (wet and dry seasons). Collections were performed every two months from October 2011 to September 2012 with the aid of seine nets, hand net and fishing traps in the streamlet located in the Machado River drainage basin in the Rondônia state. Most of the specimens collected were quite small (< 40 mm) and had empty stomachs. Our results showed that A. tetramerus feeds on a wide variety of items of plant origin, such as algae, seeds and leaves, as well as items of animal origin, including bryozoans, crustaceans, fish scales, terrestrial insects and detritus. The data also indicated higher consumption of aquatic insects than other food items, suggesting a primarily insect-based diet. Items of plant and allochthonous origin were consumed more in the wet season than in the dry season, but there were no seasonal differences in the consumption of animal and autochthonous items.

Diet and ecomorphology of Leporinus reticulatus (Characiformes: Anostomidae) from the upper Rio Juruena, MT, Brazil: ontogenetic shifts related to the feeding ecology

The conservation of diverse and well-distributed fish taxa, as the genus Leporinus, relies intrinsically on the knowledge of the ecological attributes of its representatives. Aiming to increase this knowledge, studies on diet and ecomorphology are ideal to provide important information about species ecology. Thus, this study aimed to analyze aspects of feeding ecology of L. reticulatus, from the upper Rio Juruena, Mato Grosso State, Brazil. The diet of specimens in different ontogenetic stages was compared, as well as their teeth morphology and ecomorphological attributes. Leporinus reticulatus presented omnivorous diet, with higher consumption of invertebrates by smaller specimens (younger ones), and gradual introduction of plant items in larger specimens (older ones). The items consumed by the individuals and the ecomorphological attributes indicated that the species is generalist and opportunistic, besides its association with the river bottom, evidencing a benthic feeding behavior. This species presents a gradual ontogenetic modification in teeth shape and mouth positioning, ranging from a terminal mouth with tricuspid teeth, in smaller specimens, to an inferior mouth with spatula shaped teeth with no cusps, in larger specimens.The ecomorphological attributes indicate an increasing swimming efficiency, and ability for performing vertical displacements, along the ontogenetic development, which in addition to the morphological ontogenetic alterations in the buccal apparatus, contributes to a better ability to explore another niches.

The effect of high-fat diet on rat’s mood, feeding behavior and response to stress

An association between obesity and depression has been indicated in studies addressing common physical (metabolic) and psychological (anxiety, low self-esteem) outcomes. Of consideration in both obesity and depression are chronic mild stressors to which individuals are exposed to on a daily basis. However, the response to stress is remarkably variable depending on numerous factors, such as the physical health and the mental state at the time of exposure. Here a chronic mild stress (CMS) protocol was used to assess the effect of high-fat diet (HFD)-induced obesity on response to stress in a rat model. In addition to the development of metabolic complications, such as glucose intolerance, diet-induced obesity caused behavioral alterations. Specifically, animals fed on HFD displayed depressive- and anxious-like behaviors that were only present in the normal diet (ND) group upon exposure to CMS. Of notice, these mood impairments were not further aggravated when the HFD animals were exposed to CMS, which suggest a ceiling effect. Moreover, although there was a sudden drop of food consumption in the first 3 weeks of the CMS protocol in both ND and HFD groups, only the CMS-HFD displayed an overall noticeable decrease in total food intake during the 6 weeks of the CMS protocol. Altogether, the study suggests that HFD impacts on the response to CMS, which should be considered when addressing the consequences of obesity in behavior.