RESUMO

Environmental stressors in aquatic organisms can be assessed using a bioenergetic approach based on the evaluation of changes in their physiological parameters. We evaluated the chronic effects of cadmium (Cd2+) on the energy balance as well as the survival, growth, metabolism, nitrogen excretion, hepatosomatic index, oxidized energy substrate, and osmoregulation of the shrimp Penaeus vannamei with the hypothesis that the high energy demand related to the homeostatic regulation of Cd2+could disrupt the energy balance and as a consequence, their physiological functions. The shrimp exposed to Cd2+ had higher mortality (30%), directed more energy into growth (33% of energy intake), ingested 10% more energy, and defecated less than control animals. Cd2+ exposure caused a tendency to decrease metabolism and ammonia excretion but did not alter the hepatosomatic index, type of energy substrate oxidized, and the hyperosmorregulatory pattern of the species. The Cd+2 exposure may have induced a trade-off response because there was a growth rate increase accompanied by increased mortality.

Assuntos

RESUMO

Blood glucose is widely used as a physiological parameter for vertebrates and invertebrates. However, its measurement in the field is often difficult due to the need for expensive and non-portable equipment. Point-of-care (POC) devices, originally intended for human use, are increasingly being used for measuring blood parameters of animals in the field. In this regard, POC glucose meters are becoming valuable tools for conservation physiologists, as glucose can be a useful indicator of stress response. In invertebrates, the use of POC glucose meters is still scarce, and no study yet has evaluated their usability in crustaceans and molluscs. We tested if a POC device can be used to measure haemolymph glucose in two widely used models, Leptuca thayeri and Perna perna, compared with a standard laboratory method. The device was unable to measure glucose in P. perna haemolymph due to equipment inaccuracy and low glucose concentration in this species (10.13 ± 6.25 mg/dL). Additionally, despite the device being capable of measuring glucose in L. thayeri haemolymph, Bland-Altman plots showed a strong bias and wide limits of agreement, and Lin's concordance correlation coefficient showed a weak concordance between methods. When simulating experimental conditions, POC results differed from those found using the standard method. We conclude that POC glucose meters are unsuitable for assessing glucose in mussels and should not be used in crabs as results are inaccurate.

RESUMO

Survival, osmoregulatory pattern, oxygen consumption, energy spent on metabolism, ammonia excretion, type of oxidized energy substrate, and hepatosomatic index were evaluated in decapods (an osmoregulating crab, Callinectes danae, and an osmoconforming seabob shrimp, Xiphopenaeus kroyeri) exposed to carbon dioxide-induced water acidification (pH 7.3, control pH 8.0) and different salinities (20, 25, 30, 35, and 40‰) for 3 days. Compared to the animals kept at controlled pH, exposure to reduced pH resulted in the loss of osmoregulatory capacity in C. danae at all salinities, except for some hyporegulation at 40‰, and reduced oxygen consumption and ammonia excretion at 20 and 40‰. Xiphopenaeus kroyeri remained an osmoconformer in all evaluated conditions, except for some hyporegulation at 40‰, and when exposed to the reduced pH, it presented changes in oxygen consumption at all salinities and reductions in ammonia excretion at 20 and 35‰ compared to the control animals. Both species use protein as the main energy substrate and decrease the hepatosomatic index when exposed to reduced pH relative to the control. The observed changes may be associated with changes in the activity of enzymes related to osmoregulation, the use of amino acids as osmotic effectors of cell volume control and recovery, and the Bohr effect, and, because the gills are multifunctional organs related to osmoregulation, the changes may be related to acid-base control, nitrogen excretion, and respiration, with a change in one of these functions bringing about changes in the others.

Assuntos

RESUMO

We investigated the effect of three commercial feeds containing 32%, 35% (control), and 38% of crude protein on the physiology (metabolism, ammonia excretion, energy substrate and hepatosomatic index) of Macrobrachium amazonicum. The energetic content and energy/protein ratio of the feeds were quantified. The physiological aspects did not show differences among the animals fed with the three types of feeds concerning metabolism, ammonia excretion and energy substrate, which was kept as a proteins. However, we observed 120% higher hepatosomatic index in the animals fed with 38% of protein. This feed has also higher energetic value (4,700 ± 10.6 kcal kg-1) and an energy/protein ratio (12.2:1). It is possible that these characteristics of the feed have contributed to higher hepatosomatic index. In this sense, the feed containing 38% of protein seems to be more appropriate because it may promote better storage of reserves in the hepatopancreas, a beneficial condition to reproduction and growth.

Investigou-se o efeito de três diferentes rações comerciais contendo 32%, 35% (controle) e 38% de proteína bruta sobre a fisiologia (metabolismo, excreção de amônia, substrato energético utilizado e índice hepatossomático) do camarão Macrobrachium amazonicum. O conteúdo energético e a relação energia/proteína das rações foram quantificados. Não houve diferenças entre os animais alimentados com os três tipos de rações no que tange ao metabolismo, excreção de amônia e substrato energético utilizado, que se manteve como proteínas. No entanto, foi observado índice hepatossomático 120% maior nos animais alimentados com a ração contendo 38% de proteína bruta. Essa ração também possui maior valor energético (4700 ± 10.6 kcal/kg) e relação energia:proteína de 12.2:1. É possível que essas características da ração possam ter contribuído para um maior índice hepatossomático e, consequentemente, melhor armazenamento de reservas no hepatopâncreas, condição benéfica para a reprodução, crescimento.

Assuntos

RESUMO

We investigated the effect of three commercial feeds containing 32%, 35% (control), and 38% of crude protein on the physiology (metabolism, ammonia excretion, energy substrate and hepatosomatic index) of Macrobrachium amazonicum. The energetic content and energy/protein ratio of the feeds were quantified. The physiological aspects did not show differences among the animals fed with the three types of feeds concerning metabolism, ammonia excretion and energy substrate, which was kept as a proteins. However, we observed 120% higher hepatosomatic index in the animals fed with 38% of protein. This feed has also higher energetic value (4,700 ± 10.6 kcal kg-1) and an energy/protein ratio (12.2:1). It is possible that these characteristics of the feed have contributed to higher hepatosomatic index. In this sense, the feed containing 38% of protein seems to be more appropriate because it may promote better storage of reserves in the hepatopancreas, a beneficial condition to reproduction and growth.(AU)

Investigou-se o efeito de três diferentes rações comerciais contendo 32%, 35% (controle) e 38% de proteína bruta sobre a fisiologia (metabolismo, excreção de amônia, substrato energético utilizado e índice hepatossomático) do camarão Macrobrachium amazonicum. O conteúdo energético e a relação energia/proteína das rações foram quantificados. Não houve diferenças entre os animais alimentados com os três tipos de rações no que tange ao metabolismo, excreção de amônia e substrato energético utilizado, que se manteve como proteínas. No entanto, foi observado índice hepatossomático 120% maior nos animais alimentados com a ração contendo 38% de proteína bruta. Essa ração também possui maior valor energético (4700 ± 10.6 kcal/kg) e relação energia:proteína de 12.2:1. É possível que essas características da ração possam ter contribuído para um maior índice hepatossomático e, consequentemente, melhor armazenamento de reservas no hepatopâncreas, condição benéfica para a reprodução, crescimento.(AU)

Assuntos

RESUMO

We investigated modulation by ATP, Mg²âº, Na⁺, K⁺ and NH4⁺ and inhibition by ouabain of (Na⁺,K⁺)-ATPase activity in microsomal homogenates of whole zoeae I and decapodid III (formerly zoea IX) and whole-body and gill homogenates of juvenile and adult Amazon River shrimps, Macrobrachium amazonicum. (Na⁺,K⁺)-ATPase-specific activity was increased twofold in decapodid III compared to zoea I, juveniles and adults, suggesting an important role in this ontogenetic stage. The apparent affinity for ATP (K(M) = 0.09 ± 0.01 mmol L⁻¹) of the decapodid III (Na⁺,K⁺)-ATPase, about twofold greater than the other stages, further highlights this relevance. Modulation of (Na⁺,K⁺-ATPase activity by K⁺ also revealed a threefold greater affinity for K⁺ (K0.5 = 0.91 ± 0.04 mmol L⁻¹) in decapodid III than in other stages; NH4⁺ had no modulatory effect. The affinity for Na⁺ (K0.5 = 13.2 ± 0.6 mmol L⁻¹) of zoea I (Na⁺,K⁺)-ATPase was fourfold less than other stages. Modulation by Na⁺, Mg²âº and NH4⁺ obeyed cooperative kinetics, while K⁺ modulation exhibited Michaelis-Menten behavior. Rates of maximal Mg²âº stimulation of ouabain-insensitive ATPase activity differed in each ontogenetic stage, suggesting that Mg²âº-stimulated ATPases other than (Na⁺,K⁺)-ATPase are present. Ouabain inhibition suggests that, among the various ATPase activities present in the different stages, Na⁺-ATPase may be involved in the ontogeny of osmoregulation in larval M. amazonicum. The NH4⁺-stimulated, ouabain-insensitive ATPase activity seen in zoea I and decapodid III may reflect a stage-specific means of ammonia excretion since functional gills are absent in the early larval stages.

Assuntos

RESUMO

We investigate extra- and intracellular osmoregulatory capability in two species of hololimnetic Caridea and Anomura: Macrobrachium brasiliense, a palaemonid shrimp, and Aegla franca, an aeglid anomuran, both restricted to continental waters. We also appraise the sharing of physiological characteristics by the hololimnetic Decapoda, and their origins and role in the conquest of fresh water. Both species survive salinity exposure well. While overall hyperosmoregulatory capability is weak in A. franca and moderate in M. brasiliense, both species strongly hyporegulate hemolymph [Cl(-)] but not osmolality. Muscle total free amino acids (FAA) increase slowly but markedly in response to the rapid rise in hemolymph osmolality consequent to hyperosmotic challenge: 3.5-fold in A. franca and 1.9-fold in M. brasiliense. Glycine, taurine, arginine, alanine and proline constitute ≈85% of muscle FAA pools in fresh water; taurine, arginine, alanine each contribute ≈22% in A. franca, while glycine predominates (70%) in M. brasiliense. These FAA also show the greatest increases on salinity challenge. Muscle FAA titers correlate strongly (R = 0.82) with hemolymph osmolalities across the main decapod sub/infraorders, revealing that marine species with high hemolymph osmolalities achieve isosmoticity of the intra- and extracellular fluids partly through elevated intracellular FAA concentrations; freshwater species show low hemolymph osmolalities and exhibit reduced intracellular FAA titers, consistent with isosmoticity at a far lower external osmolality. Given the decapod phylogeny adopted here and their multiple, independent invasions of fresh water, particularly by the Caridea and Anomura, our findings suggest that homoplastic strategies underlie osmotic and ionic homeostasis in the extant freshwater Decapoda.

Assuntos

RESUMO

To evaluate putative adaptive changes underpinning the invasion of freshwater by the Brachyura, this investigation examines anisosmotic extra and isosmotic intracellular osmoregulatory capabilities in Dilocarcinus pagei, a neotropical, hololimnetic crab, including its embryonic and juvenile phases. All ontogenetic stages show a remarkable ability to survive a high salinity medium (25 per thousand, 750 mOsm/kg H2O, 350 mm Na+, 400 mM Cl-). Adults hyper-regulate hemolymph osmolality up to isosmoticity at 744 mOsm kg/H2O (24 per thousand), [Na+] and [Cl-] becoming isoionic at 449 (22 per thousand) and 256 mM (16 per thousand), respectively. Hemolymph (420+/-39 mOsm/kg H2O) and urine (384+/-44 mOsm/kg H2O) are isosmotic in adults held in freshwater, and after 5-days exposure to 25 per thousand (787+/-9 mOsm/kg H2O and 777+/-43 mOs/kg H2O, respectively); D. pagei does not produce dilute urine. Total free amino acid (FAA) concentrations in embryos (14.9+/-1.2), juveniles (32.8+/-0.1) and adult muscle (10.9+/-2.1 mmol/kg wet weight) in freshwater are 30-fold less than in brackish/marine Crustacea, suggesting that FAA constitute a useful parameter to evaluate adaptation to freshwater. On acclimation to 25 per thousand, total FAA increase by approximately 100% in embryos and in adult muscle and nerve tissue and hemolymph, owing to large increases in proline, arginine and/or alanine. However, effective FAA contribution to intracellular osmolality increases only in embryos, from 3 to 4.5%. These findings suggest that gill-based, anisosmotic extracellular regulation has supplanted isosmotic intracellular regulatory mechanisms during the conquest of freshwater by the Brachyura, and indicate that D. pagei may be an old, well-adapted inhabitant of this biotope.

Assuntos

RESUMO

Ao exame ultra-sonográfico o parênquima normal dos órgãos e tecidos é visualizado em vários tons de cinza, com pouca variação de animal para animal. Os termos que são utilizados para descrever as imagens ultra-sonográficas estão relacionados com a intensidade dos ecos que retronam dos órgãos e tecidos atingidos pelas ondas de ultra-som. A correta descrição das imagens ultra-sonográficas depende de conhecimento terminológico, bem como da identificação dos artefatos de técnica que podem ser formados durante o exame. O presente artigo tem por objetivo apresentar uma breve revisão dos ternos mais utilizados e dos artefatos de técnica mais comumente observados, visando uma correta descrição das imagens observadas na ultra-sonografia.

RESUMO

Ao exame ultra-sonográfico o parênquima normal dos órgãos e tecidos é visualizado em vários tons de cinza, com pouca variação de animal para animal. Os termos que são utilizados para descrever as imagens ultra-sonográficas estão relacionados com a intensidade dos ecos que retronam dos órgãos e tecidos atingidos pelas ondas de ultra-som. A correta descrição das imagens ultra-sonográficas depende de conhecimento terminológico, bem como da identificação dos artefatos de técnica que podem ser formados durante o exame. O presente artigo tem por objetivo apresentar uma breve revisão dos ternos mais utilizados e dos artefatos de técnica mais comumente observados, visando uma correta descrição das imagens observadas na ultra-sonografia.