Characterization of digestive protease activity in the bluefin tuna Thunnus thynnus (Linnaeus, 1758)

The digestive proteases of bluefin tuna Thunnus thynnus (Linnaeus, 1758) were studied. Protease activity in stomach extracts showed two optima, at pH 2.0 and 3.5. Optimum activity for intestinal proteases was found at pH 10.0 and 12.0. Protease activity in stomach extracts was found to be stable at several pH, except for pH 12.0. Alkaline protease activity of intestine extracts was highly sensitive to acidic pH. Optimal temperatures found were 50 ºC for acid proteases and 60 ºC for alkaline proteases. The use of specific protease inhibitors indicated that the main presence of acid proteases was in stomach extracts, and serine proteases in intestine extracts. Active fractions in extracts were identified with SDS-PAGE.Se estudió la actividad proteasa digestiva de Thunnus thynnus (Linnaeus, 1758). Se encontraron dos óptimos de pH, tanto para la actividad proteasa ácida de los extractos estomacales (2,0 y 3,5) como para la actividad proteasa alcalina de los intestinales (10,0 y 12,0). La primera se mantuvo muy estable en un rango amplio de pH, a excepción de pH muy alcalinos (12,0). Por su parte, la actividad proteasa alcalina se vio afectada por pH muy ácidos. Los óptimos de temperatura se determinaron en 50 y 60 ºC para la actividad proteasa ácida y alcalina, respectivamente. Mediante el uso de inhibidores de proteasa se comprobó la presencia de proteasas aspárticas en los extractos estomacales y de serin-proteasas en los intestinales. La realización de zimogramas permitió identificar las distintas fracciones con actividad proteolítica presentes en cada extracto.Instituto Español de Oceanografí

Effect of phytase supplements on in vitro hydrolysis of proteins by rainbow trout Oncorhynchus mykiss (Walbaum, 1792)

The present paper evaluates the impact on plant meal and on an experimental feed product of supplementing them with four levels of phytase (0, 2 000, 4 000 and 6 000 FTU/kg), by assessing in vitro hydrolysis of protein in rainbow trout Oncorhynchus mykiss (Walbaum, 1792) using a pH-stat system. The effect on fish meal's digestibility of adding phytic acid was also evaluated. The highest degree of hydrolysis (DH) was obtained when phytase was added at 4 000 FTU/kg. The experimental diet's DH diminished when phytase was added at 6 000 FTU/kg. However, protein hydrolysis dropped as the percentage of phytic acid in the in vitro reaction mixture increased.En este trabajo se evaluó el efecto de la suplementación con 4 niveles de fitasa (0, 2 000, 4 000 y 6 000 FTU/kg) en un pienso experimental y sobre una harina vegetal, evaluando la hidrólisis in vitro de la proteína por pH-stat con extractos enzimáticos de trucha arcoiris Oncorhynchus mykiss (Walbaum, 1792). Además, se evaluó el efecto que ejerce la adición de ácido fítico sobre la digestibilidad de una harina de pescado. Se observó que, para el pienso experimental, el mayor grado de hidrólisis se obtiene cuando la inclusión de fitasa es de 4 000 FTU/kg, disminuyendo ligeramente cuando la inclusión es de 6 000 FTU/kg. En cambio, se observó una disminución de la hidrólisis proteica a medida que se incrementaba el porcentaje de ácido fítico en la mezcla de reacción in vitro.Instituto Español de Oceanografí

Benefits of probiotic administration on growth and performance along metamorphosis and weaning of Senegalese sole (Solea senegalensis)

Suitable nutrition at first feeding in marine fish larvae is an important factor for successful larval and juvenile rearing. In this way probiotic supplementation may contribute to better face the habitual stress of metamorphosis and weaning at early sole stages. The aimof this study was to optimize Shewanella putrefaciens Pdp11 administration to Senegalese sole (Solea senegalensis) at early stages of development. For this purpose, we studied the influence of a short pulse of S. putrefaciens Pdp11 (10–30 dah) on growth performance, gut microbiota modulation, digestive enzymes activities and body composition. These probiotic bacteria were incorporated using Artemia as live vector (2.5 × 10 7 cfu mL −1 ) and supplied to sole specimens in a co-feeding regime (Gemma, Skretting) by triplicate. S. putrefaciens Pdp11 colonized larval gut being present from23 to 119 dah. Probiotic supply significantly modulated larval and fry gut microbiota. A PCA analysis including all the parameters analyzed strongly associated S. putrefaciens Pdp11 presence with a higher fish growth, a higher digestive proteolytic activity level and a fish body composition modulation along S. senegalensis rearing. In addition less size variability was obtained frommetamorphosis until the end of weaning. In conclusion a short pulse of S. putrefaciens Pdp11 (10– 30 dah) seems sufficient to obtain a suitable microbial modulation involved in a better growth performance and body composition that suggests a great potential for sole aquaculture production.En prens

In vitro assessment of antagonistic activities of isolates from gilthead seabream (Sparus aurata) gastrointestinal tract fed microalgae supplemented diet

The use of probiotics has emerged as a sustainable alternative to antibiotics in the control of infectious diseases, favouring fish health management, growth performance and feed utilisation, among others. microalgae represent an interesting source of nutrients and functional ingredients for aquafeeds. However, their digestibility is often limited by the presence of anti-nutritional factors or absence of appropriate enzymatic activities in the fish gastrointestinal tract (GIT). The aims of the present work were to isolate potential probiotics from the GIT of Sparus aurata fed with a diet containing 25 % microalgae and characterize their antagonism against fish pathogens. Altogether, 117 strains were isolated from juvenile seabream (146.8 ± 16.4 g) and screened for hydrolytic enzyme activities. Results showed that 48 %, 41 %, 77 % and 30 % of isolates were able to hydrolyse protein, lipids, collagen and starch, respectively. Moreover, 46 %, 8 % and 57 % of isolates exhibited the ability to degrade phytate, tannins and cellulose, respectively. Based on these results, a total of 32 isolates were selected for inhibitory activity against several fish pathogens assessment. Inhibition against Aeromonas hydrophila and Vibrio anguillarum was detected in 38 % of the isolates, whilst 44 % and 47 % inhibited P damselae subsp. damselae and P. damselae subsp. piscicida, respectively. Inhibition abilities were detected in the isolates when tested against Tenacibaculum species. Thus, 56 % inhibited Tenacibaculum maritimum; 63 % T. soleae and 22 % T. gallaecium. Overall, results showed that three strains display ability to hydrolyse 4 of the assayed substrates and produce inhibition against 8 fish pathogens, and two strains are capable to hydrolyse 5 substrates and inhibit 8 fish pathogens. Selected strains show characteristics to be considered for further characterization as potential probiotics in gilthead seabream aquaculture and microalgae-supplemented aquafeeds.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Influence of Low Dietary Inclusion of the Microalga Nannochloropsis gaditana (Lubián 1982) on Performance, Fish Morphology, and Muscle Growth in Juvenile Gilthead Seabream (Sparus aurata)

A 90-d feeding trial was conducted in which five groups of gilthead seabream (11.96 g initial body weight) were fed with a microalgae-free diet (control group, C) or four diets containing the microalgae Nannochloropsis gaditana at two inclusion levels (2.5% or 5%), either raw (R2.5 and R5 batches) or cellulose-hydrolyzed (H2.5 and H5 batches), to study their effect on the body and muscle growth. At 40 days, the highest values of body length and weight were reached in R5 group, but at 64 and 90 days, these were reached in R2.5. However, feed conversion rate, specific growth, daily intake, and survival (100%) were similar in all the groups. The acquisition of a discoid body shape was accelerated depending on the inclusion level of N. gaditana in the diets. Moreover, H5 diet affected the fish geometric morphology compared to R5 diet. The white muscle transverse area was similar in all groups at 40 days, with the exception of H2.5 group, which showed the lowest area. At day 90, C and R2.5 displayed the highest muscle growth, attributable to increased hyperplasia in C, and higher hypertrophy in R2.5. However, the highest proportion of small and medium fibers was observed in R5 and H5Versión del edito

Do Religious Factors Influence the Attitude Toward Organ Donation Among Medical Students? A Spanish Multicenter Study

Introduction Religious factors have conditioned the attitude toward organ donation and transplantation (ODT) since the beginning of transplantation, despite the fact that most religions are in favor of transplantation. Objective To assess the impact of religious beliefs of medical students on their attitude toward ODT. Method Population under study: Medical students in Spanish universities. Study sample: Stratified by geographical area and academic course. Assessment instrument: Attitude ODT questionnaire PCID-DTO-Ríos, anonymous and self-administered. Results Of all students, 42% (n = 3907) declare themselves atheists or agnostics. The remaining 58% (n = 5368) declare themselves to be religious, the majority being Catholic (55%, n = 5102). Of the rest, 0.2% are Muslims (n = 8), 0.1% Protestants (n = 1), and the remaining 2.7% (n = 257) indicate other religious doctrines but do not want to specify it. Regarding their attitude toward ODT, those who consider themselves atheists or agnostics have a more favorable attitude than those who consider themselves religious (84% versus 76%; P < .001). Among those who follow some kind of religion, Catholics are more in favor of ODT than non-Catholics (77% vs 64%, P < .001). Note that among the religious, only 57% (n = 3050) know which religion is in favor of transplantation, while 22% (n = 1,152) consider that it has not been pronounced on the matter, 13% (n = 723) think the religion is against donation, and the remaining 8% (n = 443) do not know. Conclusion The religion professed by medical students conditions their attitude toward donation, with the atheists and agnostics being more in favor of donation.Sin financiación0.784 JCR (2019) Q4, 155/158 Immunology, 191/210 Surgery, 24/24 Transplantation0.363 SJR (2019) Q3, 254/451 Surgery, 27/41 TransplantationNo data IDR 2019UE