RESUMO
The study of digestive physiology is an important issue in species that have been introduced in aquaculture like the spotted rose snapper (Lutjanus guttatus). The aims of this study were to describe the expression of digestive enzymes (trypsinogen, chymotrypsinogen, α-amylase, lipoprotein lipase, phospholipase A and pepsinogen) and their relation with orexigenic (neuropeptide Y, NPY) and anorexigenic (cholecystokinin, CCK) factors during the larval development and to evaluate the effect of weaning in their expression. The results showed that the transcripts of all the assayed digestive enzymes, with the exception of pepsinogen, and NPY and CCK were already present in L. guttatus from the hatching stage. The expression of all the enzymes was low during the yolk-sac stage (0-2 days after hatching, DAH), whereas after the onset of exogenous feeding at 2 DAH, their expression increased and fluctuated throughout larval development, which followed a similar pattern as in other marine fish species and reflected changes in different types of food items and the progressive maturation of the digestive system. On the other hand, weaning of L. guttatus larvae from live prey onto a microdiet between 25 and 35 DAH significantly affected the relative expression of most pancreatic digestive enzymes during the first weaning days, whereas chymotrypsinogen 2 and lipoprotein lipase remained stable during this period. At the end of co-feeding, larvae showed similar levels of gene expression regardless of the diet (live prey vs. microdiet), which indicated that larvae of L. guttatus were able to adapt their digestive capacities to the microdiet. In contrast, feeding L. guttatus larvae with live feed or microdiet did not affect the expression of CCK and NPY. The relevance of these findings with regard to current larval rearing procedures of L. guttatus is discussed.
Assuntos
Digestão/genética , Perciformes/genética , Animais , Colecistocinina/genética , Quimotripsinogênio/genética , Feminino , Expressão Gênica , Larva/genética , Larva/crescimento & desenvolvimento , Lipase Lipoproteica/genética , Masculino , Neuropeptídeo Y/genética , Pepsinogênio A/genética , Perciformes/crescimento & desenvolvimento , Perciformes/metabolismo , Fosfolipases A2/genética , RNA Mensageiro/metabolismo , Tripsinogênio/genética , alfa-Amilases/genéticaRESUMO
We describe digestive enzyme activity during the larval development of spotted rose snapper, Lutjanus guttatus. Trypsin, chymotrypsin, leucine aminopeptidase, pepsin, amylase, lipase, and acid and alkaline phosphatase activities were evaluated using spectrophotometric techniques from hatching through 30 days. The spotted rose snapper larvae present the same pattern of digestive enzyme activity previously reported for other species in which pancreatic (i.e., trypsin, chymotrypsin, amylase, and lipase) and intestinal (i.e., acid and alkaline phosphatases and leucine aminopeptidase) enzymatic activities are present from hatching allowing the larvae to digest and absorb nutrients in the yolk-sac and live prey by the time of first feeding. The digestive and absorption capacity of the spotted rose snapper increases during the larval development. A significant increase in individual activity of all enzymes occurs at 20 DAH, and around 25 DAH, the juvenile-type of digestion is observed with the appearance of pepsin secreted by the stomach, suggesting that maturation of the digestive function occurs around 20-25 DAH. Our results are in agreement with a previous suggestion that early weaning may be possible from 20 DAH. However, the patterns of enzymatic activities reported in our study should be considered during the formulation of an artificial diet for early weaning of the spotted rose snapper.
Assuntos
Proteínas de Peixes/metabolismo , Trato Gastrointestinal/enzimologia , Perciformes/metabolismo , Animais , Digestão , Larva/enzimologia , Perciformes/crescimento & desenvolvimentoRESUMO
In this study, chitinolytic enzymes produced by Trichoderma asperellum were immobilized on a biodegradable film manufactured with a blend of cashew gum polysaccharide (CGP) and polyvinyl alcohol (PVA), and tested as a fungal growth inhibitor. The film was produced by casting a blend of CGP and PVA solution on glass molds. The CGP/PVA film showed 68% water solubility, tensile strength of 23.7 MPa, 187.2% elongation and 52% of mass loss after 90 days in soil. The presence of T-CWD enzymes immobilized by adsorption or covalent attachment resulted in effective inhibition of fungal growth. Sclerotinia sclerotiorum was the most sensitive organism, followed by Aspergillus niger and Penicillium sp. SEM micrograph showed that the presence of immobilized T-CWD enzymes on CGP/PVA film produced morphological modifications on vegetative and germinative structures of the microorganisms, particularly hyphae disruption and changes of spores shape.
Assuntos
Antifúngicos/farmacologia , Ascomicetos/efeitos dos fármacos , Aspergillus niger/efeitos dos fármacos , Penicillium/efeitos dos fármacos , Polissacarídeos/farmacologia , Álcool de Polivinil/farmacologia , Antifúngicos/metabolismo , Ascomicetos/crescimento & desenvolvimento , Aspergillus niger/crescimento & desenvolvimento , Biodegradação Ambiental , Enzimas Imobilizadas/metabolismo , Testes de Sensibilidade Microbiana , Microscopia Eletrônica de Varredura , Penicillium/crescimento & desenvolvimento , Polissacarídeos/administração & dosagem , Polissacarídeos/metabolismo , Álcool de Polivinil/administração & dosagem , Álcool de Polivinil/metabolismo , Solubilidade , Espectroscopia de Infravermelho com Transformada de Fourier , TermogravimetriaRESUMO
The use of cell wall degrading enzymes from Trichoderma asperellum immobilized on biodegradable support is an alternative for food packaging. In this study, hydrolytic enzymes produced by T. asperellum were tested as a fungal growth inhibitor, in free form or immobilized on a biodegradable film composed of cassava starch and poly(butylene adipate-co-terephtalate) (PBAT). The inhibitory activity was tested against Aspergillus niger , Penicillium sp., and Sclerotinia sclerotiorum , microorganisms that frequently degrade food packaging. The use of chitin as carbon source in liquid medium induced T. asperellun to produce N-acetylglucosaminidase, ß-1,3-glucanase, chitinase, and protease. The presence of T. asperellun cell wall degradating enzymes (T-CWD) immobilized by adsorption or covalent attachment resulted in effective inhibition of fungal growth. The enzymatic activity of T-CWD was stronger on S. sclerotiorum than on the Aspergillus or Penicillum isolates tested. These results suggest that T-CWD can be used in a free or immobilized form to suppress fungi that degrade food packaging.
Assuntos
Acetilglucosaminidase/farmacologia , Antifúngicos/farmacologia , Quitinases/farmacologia , Enzimas Imobilizadas/farmacologia , Proteínas Fúngicas/farmacologia , Fungos/efeitos dos fármacos , Glucana 1,3-beta-Glucosidase/farmacologia , Trichoderma/enzimologia , Acetilglucosaminidase/química , Antifúngicos/química , Parede Celular/efeitos dos fármacos , Quitinases/química , Enzimas Imobilizadas/química , Embalagem de Alimentos , Conservação de Alimentos , Proteínas Fúngicas/química , Fungos/crescimento & desenvolvimento , Glucana 1,3-beta-Glucosidase/química , Hidrólise , Trichoderma/químicaRESUMO
The activities of several digestive enzymes during larval development of the spotted sand bass (Paralabrax maculatofasciatus) were evaluated using electrophoretic techniques. The results show the presence of three isoforms of alkaline protease from day 2 after hatching (ah) and the early appearance of one pepsin-like band from day 12 ah onwards. In addition, two lipase bands first appeared on day 2 ah, and there was a change in the molecular weight of one band from day 15 ah onwards. Several alpha-amylase isoforms were observed from hatching up to day 5 ah. These results indicate that the important digestive enzymes develop rapidly in these larvae, supporting the possibility of early weaning at day 12 ah using artificial diets.
Assuntos
Bass/crescimento & desenvolvimento , Digestão/fisiologia , Trato Gastrointestinal/enzimologia , Lipase/metabolismo , Peptídeo Hidrolases/metabolismo , alfa-Amilases/metabolismo , Animais , Eletroforese em Gel de Poliacrilamida , Larva/enzimologia , Fenômenos Fisiológicos da NutriçãoRESUMO
Spotted sand bass Paralabrax maculatofasciatus is a potential aquaculture species in Northwest Mexico. In the last few years it has been possible to close its life cycle and to develop larviculture technology at on pilot scale using live food, however survival values are low (11%) and improvements in growth and survival requires the study of the morpho-physiological development during the initial ontogeny. In this research digestive activity of several enzymes were evaluated in larvae, from hatching to 30 days after hatching (dah), and in live prey (rotifers and Artemia), by use of biochemical and electrophoretic techniques. This paper, is the first of two parts, and covers only the biochemical analysis. All digestive enzyme activities were detected from mouth opening; however the, maximum activities varied among different digestive enzymes. For alkaline protease and trypsin the maximum activities were detected from 12 to 18 dah. Acid protease activity was observed from day 12 onwards. The other digestive enzymes appear between days 4 and 18 after hatching, with marked fluctuations. These activities indicate the beginning of the juvenile stage and the maturation of the digestive system, in agreement with changes that occur during morpho-physiological development and food changes from rotifers to Artemia. All enzymatic activities were detected in rotifers and Artemia, and their contribution to enhancement the digestion capacity of the larvae appears to be low, but cannot be minimised. We concluded that the enzymatic equipment of P. maculatofasciatus larvae is similar to that of other marine fish species, that it becomes complete between days 12 and 18 after hatching, and that it is totally efficient up to 25 dah.
Assuntos
Bass/fisiologia , Digestão/fisiologia , Enzimas/metabolismo , Larva/enzimologia , Animais , Artemia/enzimologia , Bass/crescimento & desenvolvimento , Larva/crescimento & desenvolvimento , Rotíferos/enzimologiaRESUMO
The level and the spatial organization of chloroplast DNA polymorphism were investigated in Dicorynia guianensis Hamshoff (Caesalpiniaceae) at different spatial and temporal scales. D. guianensis is a canopy tree of the rain forest that is distributed throughout the Guiana plateau in small aggregates. Twelve different haplotypes were identified using restriction analysis of polymerase chain reaction (PCR) amplified fragments of the chloroplast genome. When populations from different areas of French Guiana were compared, a clear geographical pattern of haplotype frequencies was identified along the Atlantic coast. This pattern is most likely the result of the restriction-expansion dynamics of the tropical forest during the Quaternary. At the local level, D. guianensis was characterized by a high level of within population diversity. Maintenance of within population diversity results from the dynamics of the aggregates; stochastic demography associated with the turnover of aggregates generates genetic differentiation among them. At the stand level, a strong spatial aggregation of haplotypes persisted from the adult to the seedling cohort indicating limited seed flow. There was also a strong difference in levels of diversity between the cohorts which suggested that recruitment over several years is needed in order to maintain genetic diversity during regeneration.