CONCEITO DA PROFUNDIDADE DE MISTURA GERADA PELA AÇÃO DE ONDAS APLICADO À LAGOA DA MANGUEIRA

O termo profundidade de mistura é definido como a profundidade máxima afetada pela onda ao se propagar. Esse conceito é aplicado à lagoa Mangueira, uma lagoa costeira rasa, fechada e sem efeito de maré. Como a profundidade máxima é de 6m e que vento de intensidade superior a 5m/s atingem profundidades superiores a 4,7m na direção mais desfavorável, conclui-se tratar-se de local que dificilmente atinge uma condição de estratificação térmica, devendo ser comum a ressuspensão de sedimentos do fundo

Biotic indicators for ecological state change in Amazonian floodplains

Riverine floodplains are biologically diverse and productive ecosystems. Although tropical floodplains remain relatively conserved and ecologically functional compared to those at higher latitudes, they face accelerated hydropower development, climate change, and deforestation. Alterations to the flood pulse could act synergistically with other drivers of change to promote profound ecological state change at a large spatial scale. State change occurs when an ecosystem reaches a critical threshold or tipping point, which leads to an alternative qualitative state for the ecosystem. Visualizing an alternative state for Amazonian floodplains is not straightforward. Yet, it is critical to recognize that changes to the flood pulse could push tropical floodplain ecosystems over a tipping point with cascading adverse effects on biodiversity and ecosystem services. We characterize the Amazonian flood pulse regime, summarize evidence of flood pulse change, assess potential ecological repercussions, and provide a monitoring framework for tracking flood pulse change and detecting biotic responses

ANÁLISE ENTRE MÉTODOS DE DETERMINAÇÃO DE FETCH APLICADOS AO RESERVATÓRIO DE CAPIVARI-CACHOEIRA

O conceito de campo de fetch é aplicado ao reservatório de Capivari-Cachoeira - PR, permitindo uma análise bidimensional comparativa entre métodos de obtenção do fetch: o de Saville e o oceânico. Através dos mapas de fetch, gerados pelo modelo computacional ONDACAD, foi verificado que a localização do maior fetch é condicionada pelo método adotado. O conhecimento dos desvios pode contribuir para o aproveitamento de estudos publicados e permitir a compreensão dos métodos no espaço bidimensional

MÉTODO RÁPIDO PARA DETERMINAÇÃO DO FETCH MÁXIMO APLICADO AO RESERVATÓRIO DE ITAIPU

A finalidade do método Rápido é determinar de modo objetivo e confiável o maior comprimento de fetch em um corpo de água continental. Constitui-se em um método gráfico que deve ser aplicado diretamente sobre um mapa ou imagem de satélite. Pelo presente estudo é verificada a validação do método pela aplicação ao reservatório de Itaipu

Decreased Cholinergic Stimulation Of Insulin Secretion By Islets From Rats Fed A Low Protein Diet Is Associated With Reduced Protein Kinase Cα Expression

Undernutrition has been shown to affect the autonomic nervous system, leading to permanent alterations in insulin secretion. To understand these interactions better, we investigated the effects of carbamylcholine (CCh) and phorbol 12-myristate 13-acetate (PMA) on insulin secretion in pancreatic islets from rats fed a normal (17%; NP) or low (6%; LP) protein diet for 8 wk. Isolated islets were incubated for 1 h in Krebs-bicarbonate solution containing 8.3 mmol glucose/L, with or without PMA (400 nmol/L) and CCh. Increasing concentrations of CCh (0.1-1000 μmol/L) dose dependently increased insulin secretion by islets from both groups of rats. However, insulin secretion by islets from rats fed the NP diet was significantly higher than that of rats fed the LP diet, and the dose-response curve to CCh was shifted to the right in islets from rats fed LP with a 50% effective concentration (EC50) of 2.15 ± 0.7 and 4.64 ± 0.1 μmol CCh/L in islets of rats fed NP and LP diets, respectively (P < 0.05). PMA-induced insulin secretion was higher in islets of rats fed NP compared with those fed LP. Western blotting revealed that the protein kinase (PK)Cα and phospholipase (PL)Cβ1 contents of islets of rats fed LP were 30% lower than those of islets of rats fed NP (P < 0.05). In addition, PKCα mRNA expression was reduced by 50% in islets from rats fed LP. In conclusion, a reduced expression of PKCα and PLCβ1, may be involved in the decreased insulin secretion by islets from LP rats after stimulation with CCh and PMA.1333695699Becker, D.J., The endocrine responses to protein calorie malnutrition (1983) Annu. Rev. Nutr., 3, pp. 187-212Escriva, F., Rodriguez, C., Cacho, J., Alvarez, C., Portha, B., Pascual-Leone, A.M., Glucose utilization and insulin action in adult rats submitted to prolonged food restriction (1992) Am. J. Physiol., 263, pp. E1-E7Heard, C.R., The effects of protein-energy malnutrition on blood glucose homeostasis (1978) World Rev. Nutr. Diet., 30, pp. 107-147Okitolonda, W., Brichard, S.M., Henquin, J.C., Repercussions of chronic protein-calorie malnutrition on glucose homeostasis in the rat (1987) Diabetologia, 30, pp. 946-951Picarel-Blanchot, F., Alvarez, C., Bailbe, D., Pascual-Leone, A.M., Portha, B., Changes in insulin action and insulin secretion in the rat after dietary restriction early in life: Influence of food restriction versus low-protein food restriction (1995) Metabolism, 44, pp. 1519-1526Escriva, F., Kergoat, M., Bailbe, D., Pascual-Leone, A.M., Portha, B., Increased insulin action in the rat after protein malnutrition early in life (1991) Diabetologia, 34, pp. 559-564Levine, L.S., Wright, P.G., Marcus, F., Failure to secrete immunoreactive insulin by rats fed a low protein diet (1983) Acta Endocrinol., 102, pp. 240-245Swenne, I., Crace, C.J., Milner, R.D., Persistent impairment of insulin secretory response to glucose in adult rats after limited period of protein-calorie malnutrition early in life (1987) Diabetes, 36, pp. 454-458Swenne, I., Crace, C.J., Jansson, L., Intermittent protein-calorie malnutrition in the young rat causes long-term impairment of the insulin secretory response to glucose in vitro (1988) J. Endocrinol., 118, pp. 295-302Swenne, I., Borg, L.A., Crace, C.J., Schnell-Landstrom, A., Persistent reduction of pancreatic beta-cell mass after a limited period of protein-energy malnutrition in the young rat (1992) Diabetologia, 35, pp. 939-945Leon-Quinto, T., Magnan, C., Portha, B., Altered activity of the autonomous nervous system as a determinant of the impaired beta-cell secretory response after protein-energy restriction in the rat (1998) Endocrinology, 139, pp. 3382-3389Kelley, G.G., Zawalich, K.C., Zawalich, W.S., Synergistic interaction of glucose and neurohumoral agonists to stimulate islet phosphoinositide hydrolysis (1995) Am. J. Physiol., 269, pp. E575-E582Verspohl, E.J., Herrmann, K., Involvement of G proteins in the effect of carbachol and cholecystokinin in rat pancreatic islets (1996) Am. J. Physiol., 271, pp. E65-E72Verspohl, E.J., Tacke, R., Mutschler, E., Lambrecht, G., Muscarinic receptor subtypes in rat pancreatic islets: Binding and functional studies (1990) Eur. J. Pharmacol., 178, pp. 303-311Persaud, S.J., Jones, P.M., Howell, S.L., Activation of protein kinase C is essential for sustained insulin secretion in response to cholinergic stimulation (1991) Biochim. Biophys. Acta, 1091, pp. 120-122Bansal, S.K., Jaiswal, A.S., Kathayat, R., Basir, S.F., Misra, U.K., Effect of dietary protein manipulation on translocation of protein kinase C activity in various tissues of rats (1996) Indian J. Exp. Biol., 34, pp. 197-200Reis, M.A.B., Carneiro, E.M., Mello, M.A.R., Boschero, A.C., Saad, M.A.J., Velloso, L.A., Glucose-induced insulin secretion is impaired and insulin-induced phosphorylation of the insulin receptor and insulin receptor substrate-1 are increased in protein-deficient rats (1997) J. Nutr., 127, pp. 403-410Doumus, B.T., Watson, W.A., Biggs, H.G., Albumin standards and measurements of serum albumin with bromocresol green (1971) Clin. Chim. Acta, 31, pp. 87-96Heard, C.R., Frangi, S.M., Wright, P.M., McCartney, P.R., Biochemical characteristics of different forms of protein-energy malnutrition: An experimental model using young rats (1997) Br. J. Nutr., 37, pp. 1-21Weinkove, C., Weinkove, E.A., Pimstone, B.L., Glucose tolerance and insulin release in malnourished rats (1976) Clin. Sci. Mol. Med., 50, pp. 153-163Bordin, S., Boschero, A.C., Carneiro, E.M., Atwater, I., Ionic mechanisms involved in the regulation of insulin secretion by muscarinic agonists (1995) J. Membr. Biol., 148, pp. 177-184Scott, A.M., Atwater, I., Rojas, E., A method for the simultaneous measurement of insulin release and B cell membrane potential in single mouse islets of Langerhans (1981) Diabetologia, 21, pp. 470-475Eickhoff, B., Korn, B., Schick, M., Poustka, A., Van der Bosch, J., Normalization of array hybridization experiments in differential gene expression analysis (1999) Nucleic Acids Res., 27, pp. e33Claeyssens, S., Lavoinne, A., Vaillant, C., Rakotomanga, J.A., Bois-Joyeux, B., Peret, J., Metabolic changes during early starvation in rats fed a low-protein diet in the postweaning growth period (1992) Metabolism, 41, pp. 722-727Davies, M.J., Rayman, G., Grenfell, A., Gray, I.P., Day, J.L., Hales, C.N., Loss of the first phase insulin response to intravenous glucose in subjects with persistent impaired glucose tolerance (1994) Diabetes Med., 11, pp. 432-436Del Prato, S., Tiengo, A., The importance of first-phase insulin secretion: Implications for the therapy of type 2 diabetes mellitus (2001) Diabetes Metab. Res. Rev., 17, pp. 164-174Kahn, S.E., Montgomery, B., Howel, W., Ligueros-Saylan, M., Hsu, C.H., Devineni, D., McLeod, J.F., Foley, J.E., Importance of early phase insulin secretion to intravenous glucose tolerance in subjects with type 2 diabetes mellitus (2001) J. Clin. Endocrinol. Metab., 86, pp. 5824-5829Boschero, A.C., Szpak-Glasman, M., Carneiro, E.M., Bordin, S., Paul, I., Rojas, E., Atwater, I., Oxotremorine-m potentiation of glucose-induced insulin release from rat islets involves M3 muscarinic receptors (1995) Am. J. Physiol., 268, pp. E336-E342Henquin, J.C., Nenquin, M., The muscarinic receptor subtype in mouse pancreatic B-cells (1988) FEBS Lett., 236, pp. 89-92Woods, S.C., Porte D., Jr., Neural control of the endocrine pancreas (1974) Physiol. Rev., 54, pp. 596-619Henquin, J.C., Jonas, J.C., Gilon, P., Functional significance of Ca2+ oscillations in pancreatic beta cells (1998) Diabetes Metab., 24, pp. 30-36Santos, R.M., Rojas, E., Muscarinic receptor modulation of glucose-induced electrical activity in mouse pancreatic B-cells (1989) FEBS Lett., 249, pp. 411-417Verchere, C.B., Kwok, Y.N., Brown, J.C., Modulation of acetylcholine-stimulated insulin release by glucose and gastric inhibitory polypeptide (1991) Pharmacology, 42, pp. 273-282Prentki, M., Matschinsky, F.M., Ca2+, cAMP, and phospholipid-derived messengers in coupling mechanisms of insulin secretion (1987) Physiol. Rev., 67, pp. 1185-1248Berggren, P.O., Arkhammar, P., Nilsson, T., Activation of protein kinase C assists insulin producing cells in recovery from raised cytoplasmic calcium by stimulating calcium efflux (1989) Biochem. Biophys. Res. Commun., 165, pp. 416-421Jones, P.M., Persaud, S.J., Howell, S.L., Protein kinase C and the regulation of insulin secretion from pancreatic B cells (1991) J. Mol. Endocrinol., 6, pp. 121-127Wollheim, C.B., Dunne, M.J., Peter-Riesch, B., Bruzzone, R., Pozzan, T., Petersen, O.H., Activators of protein kinase C depolarize insulin-secreting cells by closing K+ channels (1988) EMBO J., 7, pp. 2443-2449Yada, T., Russo, L.L., Sharp, G.W., Phorbol ester-stimulated insulin secretion by RINm5F insulinoma cells is linked with membrane depolarization and an increase in cytosolic free Ca2+ concentration (1989) J. Biol. Chem., 264, pp. 2455-2462Wei, Y., Tae, N., Tatsuya, F., Hiroyoshi, H., Takao, S., Yasuharu, S., Ighiro, N., Synergism of protein kinase A, protein kinase C, and myosin light-chain kinase in the secretory cascade of the pancreatic B-cell (2000) Diabetes, 49, pp. 945-952Easom, R.A., Hughes, J.H., Landt, M., Wolf, B.A., Turk, J., McDaniel, M.L., Comparison of effects of phorbol esters and glucose on protein kinase C activation and insulin secretion in pancreatic islets (1989) Biochem. J., 264, pp. 27-33Persaud, S.J., Jones, P.M., Sugden, D., Howell, S.L., Translocation of protein kinase C in rat islets of Langerhans. Effects of a phorbol ester, carbachol and glucose (1989) FEBS Lett., 245, pp. 80-84Arkhammar, P., Juntti-Berggren, L., Larsson, O., Welsh, M., Nanberg, E., Sjoholm, A., Kohler, M., Berggren, P.-O., Protein kinase C modulates the insulin secretory process by maintaining a proper function of the beta-cell voltage-activated Ca2+ channels (1994) J. Biol. Chem., 269, pp. 2743-2749Ganesan, S., Calle, R., Zawalich, K., Smallwood, J.I., Zawalich, W.S., Rasmussen, H., Glucose-induced translocation of protein kinase C in rat pancreatic islets (1990) Proc. Natl. Acad. Sci. U.S.A., 87, pp. 9893-9897Zaitsev, S.V., Efendic, S., Arkhammar, P., Bertorello, A.M., Berggren, P.-O., Dissociation between changes in cytoplasmic free Ca2+ concentration and insulin secretion as evidenced from measurements in mouse single pancreatic islets (1995) Proc. Natl. Acad. Sci. U.S.A., 92, pp. 9712-9716Nakamura, J., Suda, T., Ogawa, Y., Takeo, T., Suga, S., Wakui, M., Protein kinase C-dependent and -independent inhibition of Ca2+ influx by phorbol ester in rat pancreatic beta-cells (2001) Cell. Signalling, 13, pp. 199-20

Population Dynamics Modeling of Arapaima gigas Modelagem da dinâmica populacional de Arapaima gigas

Pirarucu (Arapaima gigas) has been of the most important natural fishing resources of the Amazon region. Due to its economic importance, and the necessity to preserve the species hand, field research concerning the habits and behavior of the pirarucu has been increasing for the last 20 years. The aim of this paper is to present a mathematical model for the pirarucu population dynamics considering the species peculiarities, particularly the male parental care over the offspring. The solution of the dynamical systems indicates three possible equilibrium points for the population. The first corresponds to extinction; the third corresponds to a stable population close to the environmental carrying capacity. The second corresponds to an unstable equilibrium located between extinction and full use of the carrying capacity. It is shown that lack of males&#8217; parental care closes the gap between the point corresponding to the unstable equilibrium and the point of stable non-trivial equilibrium. If guarding failure reaches a critical point the two points coincide and the population tends irreversibly to extinction. If some event tends to destabilize the population equilibrium, as for instance inadequate parental care, the model responds in such a way as to restore the trajectory towards the stable equilibrium point avoiding the route to extinction. The parameters introduced to solve the system of equations are partially derived from limited but reliable field data collected at the Mamirauá Sustainable Development Reserve (MSDR) in the Brazilian Amazonian Region.<br>Pirarucu (Arapaima gigas) tem sido um dos mais importantes recursos pesqueiros naturais da Amazônia. Devido à sua importância econômica, por um lado, e a necessidade de preservar a espécie, por outro lado, o domínio da investigação relativa a hábitos e comportamento do pirarucu tem sido crescente nos últimos 20 anos. O objetivo deste trabalho é apresentar um modelo matemático para a dinâmica populacional do pirarucu considerando as peculiaridades da espécie, particularmente o cuidado parental do macho sobre seus descendentes. A solução dos sistemas dinâmicos indicaram três possíveis pontos de equilíbrio para a população. O primeiro corresponde à extinção; o terceiro corresponde a uma população estável próxima da capacidade suporte do ambiente. O segundo corresponde a um equilíbrio instável localizado entre a extinção e a capacidade suporte do ambiente. Foi mostrado que a falta do cuidado parental de machos aproxima o ponto que corresponde ao equilíbrio instável e o ponto de equilíbrio estável não trivial. Se a falta de cuidado dos machos alcança um ponto crítico, os dois pontos coincidem e a população tende irreversivelmente à extinção. Os parâmetros introduzidos para resolver o sistema de equações foram derivados parcialmente de limitados, mas confiáveis dados de campo coletados na Reserva de Desenvolvimento Sustentável Mamirauá (RDSM) na Amazônia brasileira