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During the early ontogeny, the transition from endogenous (yolk protein) to exogenous feeding (artificial diets) represents a critical period linked to the undifferentiated digestive system, with low digestibility of food protein. The objectives of this work were to characterize the morphology of the early Nile tilapia (Oreochromis niloticus) developmental stages and determine the activity of alkaline and acid peptidase enzymes during the ontogenesis from hatching to 20 days post-hatching (DPH). Also, the in vitro effect that exogenous enzymes from Argentine red shrimp (Pleoticus muelleri) waste have on the alkaline peptidases of larvae from 6 to 20 DPH (which correspond to the age at which fish eat exogenous food) was studied. Both acid and alkaline peptidase activities varied throughout early ontogeny development (from 0.1 to 1, and from 0.1 to 7.1 UE mg protein−1, respectively). The patterns of both enzyme activity variation would be related with changes in endogenous, mixed and exogenous feeding. Our studies show that the additions of the enzyme extract of shrimp have a synergistic effect (from 3 to 6 times) on endogenous in vitro activity. Moreover, the zymogram analysis demonstrates that the bands corresponding to the activity of each species (tilapia and red shrimp) remain active when they are mixed. The increase in peptidase digestive capacity by addition of exogenous enzymes would maximize the assimilation of nutrients from artificial food during early development. [ABSTRACT FROM AUTHOR]

Aquaculture is the fastest-growing food production area in the world and this productive activity requires nutrients that fit the needs of cultured species, as well as additives or supplements that help keep organisms healthy. The use of probiotics, prebiotics, synbiotics and parabiotics as an alternative to regular feed has been proved to stimulate good health, safeguard the gut against pathogenic microorganisms, and reduce inflammation. In turn, these compounds have improved the growth, immunity, and gut health of cultured species. Yeasts are a noble product to use in aquaculture (as a whole or as components/pieces) as supplements in animal feed because they are an emerging alternative ingredient because of their nutritional value and some of the bioactive compounds that they contain. Saccharomyces cerevisiae has been the most commonly used yeast in aquaculture, particularly for its health stimulating effects in various cultured species. Most of the research carried out in fishes and crustaceans have confirmed that S. cerevisiae and its cellular components (β-glucan, mannaoligosaccharides, glucooligosaccharides, enzymes) improve growth, morphology and physiology of the host digestive system and also immune responses. However, the different works on yeast S. cerevisiae applied to aquaculture has not been fully integrated. This scientific knowledge is needed to be subsequently transferred to aquaculture mainly to seafood industrial production. The use of S. cerevisiae allows to replace the use of antibiotics, generating an eco-friendly methodology to control pathogens. Therefore, this review aims to integrate the effects of S. cerevisiae as probiotic, prebiotic, synbiotic, and parabiotic-postbiotics on aquaculture of fishes and crustaceans, and open a new insight to future investigations. • Probiotics, prebiotics and parabiotics are an alternative to aquaculture feed. • S. cerevisiae is a good immunostimulant for it heightens defensive responses. • Yeast constitutes an emerging ingredient because it contains bioactive compounds. [ABSTRACT FROM AUTHOR]

No studies are available about biochemical characteristics and modulation (i.e. by endogenous and/or environmental cues) of trypsin (a key digestive endoprotease) in hepatopancreas of intertidal euryhaline crabs neither on the possible concomitant modulation of key ectoproteases such as aminopeptidase-N (APN) involved in final steps of protein digestion. Furthermore, nothing is still known in decapods crustaceans about the role of histamine as primary chemical messenger for modulation of main components of digestive process (i.e. proteases). We determined biochemical characteristics and investigated the effect of histamine injections; of histamine in vitro and of acclimation of individuals to low and high salinity on trypsin and aminopeptidase-N (APN) activities in the hepatopancreas of the euryhaline crab Cyrtograpsus angulatus (Dana 1851). Trypsin activity was maximal at pH 7.4 and at 45 °C. APN activity increased from pH 6.6 to 7.6–9.0 and was maintained high at 37–45 °C. Both activities exhibited Michaelis-Menten kinetics (apparent Km: trypsin = 0.36 mM; APN = 0.07 mM). The injection of 10 − 4 M histamine decreased trypsin activity (about 40%) in hepatopancreas while did not affect APN activity. Similarly, in vitro 10 -4 M histamine decreased trypsin activity (about 52%) in hepatopancreas but not APN activity. Trypsin activity in the hepatopancreas was not affected by acclimation of crabs to low (10 psu) or high (40 psu) environmental salinity while APN activity was increased (about 200%) in 10 psu. The results show the differential modulation of trypsin and APN by distinct cues and point to histamine as modulator of intracellular trypsin by direct action on the hepatopancreas. [ABSTRACT FROM AUTHOR]

In spite of their ecological importance in tidal pools, studies on digestive flexibility in non-symbiotic anemones (i.e., without symbiosis throughout their life) upon changes in key environmental factors are lacking. This study constitutes the first work to investigate the response of digestive enzymes in relation to high environmental salinity and temperature in a non-symbiotic sea anemone. We determined the occurrence and biochemical characteristics of maltase activity and compared maltase and proteolytic activities in mesenterial filaments in Bunodosoma zamponii from the intertidal area of Punta Cantera, Mar del Plata, Argentina (38°05′S, 57°32′W) acclimated to 35 and 40 psu and after an acute enhancement (15 min) of temperature from 20° to 30°C. Maltase activity was higher in 40 psu and upon the increase in temperature (about 80 and 99%, respectively). Proteolytic activity was not affected in any case. The results suggest the occurrence of specific digestive adjustments in relation to high salinity and temperature. The fact that differential modulation of maltase activity could be associated with a higher digestive capacity for glycogenic substrates is discussed. [ABSTRACT FROM AUTHOR]

We studied the biochemical characteristics and modulation by dopamine, glucagon and cAMP of lipase activity in hepatopancreas of the euryhaline crab Neohelice granulata (Dana, 1851), considered to be an emergent model for biochemical, physiological and ecological research. Lipase activity was maximum at pH 8.5; it exhibited Michaelis-Menten kinetics (apparent Km = 0.018 mM), was highest at 37°C but appeared to be cold- and heat-tolerant, since it was high at 4°C and at 45°C. Lipase activity was enhanced upon incubation of hepatopancreas with 10-4 M dopamine (about 100%), 2 × 10-3 M glucagon (about 250%) and 10-3 M cAMP (about 150%) suggesting a role of these chemical messengers in mechanisms of regulation of lipolytic activities and its direct effect on the hepatopancreas. The concomitant decrease in triglycerides content upon dopamine and cAMP treatment suggests a link between enhanced lipase activity by these messengers and triglycerides catabolism. [ABSTRACT FROM AUTHOR]

We studied the existence, biochemical characteristics and response to different environmental salinities of amylase, maltase and sucrase activity in the intertidal euryhaline crab Cyrtograpsus angulatus (Dana, 1852) along with the response to distinct salinities of glycogen and free glucose content in storage organs. Amylase, maltase and sucrase activities were kept over a broad range of pH and temperature and exhibited Michaelis–Menten kinetics. Zymography showed the existence of two amylase forms in crabs exposed to 35 (osmoconformation) and low (6–10 psu; hyper-regulation) or high (40 psu) (hypo-regulation) salinities. Carbohydrases activity in the hepatopancreas and glycemia were not affected in crab exposed to different environmental salinities. In 6 and 40 psu, the glycogen content in anterior gills was lower than in 35 psu. In 6, 10 and 40 psu, glycogen concentration in hepatopancreas, muscle and posterior gills were similar to that in 35 psu. Free glucose concentration in chela muscle was higher in 6 and 40 psu than in 35 psu. The existence and biochemical characteristics of carbohydrases activity and the adjustments in concentration of glycogen in anterior gills and free glucose in chela muscle suggests the ability to perform complete hydrolysis of glycogenic substrates and to keep glucose homeostasis in relation to acclimation to different salinity conditions. [ABSTRACT FROM AUTHOR]

Summary: The application of metabarcoding to study animal‐associated microeukaryotes has been restricted because the universal barcode used to study microeukaryotic ecology and distribution in the environment, the Small Subunit of the Ribosomal RNA gene (18S rRNA), is also present in the host. As a result, when host‐associated microbial eukaryotes are analysed by metabarcoding, the reads tend to be dominated by host sequences. We have done an in silico validation against the SILVA 18S rRNA database of a non‐metazoan primer set (primers that are biased against the metazoan 18S rRNA) that recovers only 2.6% of all the metazoan sequences, while recovering most of the other eukaryotes (80.4%). Among metazoans, the non‐metazoan primers are predicted to amplify 74% of Porifera sequences, 4% of Ctenophora, and 15% of Cnidaria, while amplifying almost no sequences within Bilateria. In vivo, these non‐metazoan primers reduce significantly the animal signal from coral and human samples, and when compared against universal primers provide at worst a 2‐fold decrease in the number of metazoan reads and at best a 2800‐fold decrease. This easy, inexpensive, and near‐universal method for the study of animal‐associated microeukaryotes diversity will contribute to a better understanding of the microbiome. [ABSTRACT FROM AUTHOR]

Background: The lack of an effective diagnostic tool for Carrion’s disease leads to misdiagnosis, wrong treatments and perpetuation of asymptomatic carriers living in endemic areas. Conventional PCR approaches have been reported as a diagnostic technique. However, the detection limit of these techniques is not clear as well as if its usefulness in low bacteriemia cases. The aim of this study was to evaluate the detection limit of 3 PCR approaches. Methodology/Principal Findings: We determined the detection limit of 3 different PCR approaches: Bartonella-specific 16S rRNA, fla and its genes. We also evaluated the viability of dry blood spots to be used as a sample transport system. Our results show that 16S rRNA PCR is the approach with a lowest detection limit, 5 CFU/μL, and thus, the best diagnostic PCR tool studied. Dry blood spots diminish the sensitivity of the assay. Conclusions/Significance: From the tested PCRs, the 16S rRNA PCR-approach is the best to be used in the direct blood detection of acute cases of Carrion’s disease. However its use in samples from dry blood spots results in easier management of transport samples in rural areas, a slight decrease in the sensitivity was observed. The usefulness to detect by PCR the presence of low-bacteriemic or asymptomatic carriers is doubtful, showing the need to search for new more sensible techniques. [ABSTRACT FROM AUTHOR]