Effect of temporal thermal stress on Penaeus vannamei: Growth performance and physiological plasticity.

The present study evaluated the effect of temporal periods of hypothermia and hyperthermia, followed by an optimal temperature recovery phase on the growth, survival, and physiological response of Penaeus vannamei. Post-larvae were exposed to stress periods for 7 and 14 days at 22 °C and 32 °C each, followed by a recovery phase at 28 °C to complete seven experimental weeks, and were compared with a control group maintained at 28 °C. Weight gain, specific growth rate, feed intake, feed conversion ratio, and survival were weekly determined. Muscle, hepatopancreas, and hemolymph were sampled on the 14th day of the recovery phase for biochemical composition, and antioxidant and digestive enzyme activities determination. The shrimp presented a higher growth rate during short-term hyperthermia in contrast to shrimp under hypothermia that presented compensatory growth after thermal stress when the temperature was restored at 28 °C. Hyperthermia increased 12-13% the feed intake while this was diminished 21-29% by the hypothermia periods. Shrimp undergo metabolic adjustments following thermal stress, with short hypothermia increasing the lipase activity and lipid storage in the hepatopancreas, while short hyperthermia also enhances chymotrypsin activity and leads to higher protein and lipid accumulation. Conversely, prolonged hyperthermia induces greater energy consumption, depleting lipid and glycogen stores, while hypothermia causes scarce mobilization of energy reserves during recovery phase. Antioxidant enzyme activities were not affected by short-thermal stress (7d), while prolonged thermal stress (14d) significantly affected SOD, CAT, and GPx activities. The present study provides important insights into the physiological plasticity of P. vannamei during recovery from thermal stress.

Effect of functional diets on intestinal microbiota and resistance to Vibrio parahaemolyticus causing acute hepatopancreatic necrosis disease (AHPND) of Pacific white shrimp (Penaeus vannamei).

AIMS: The present study evaluated the effect of four functional diets and a reference diet on the survival and intestinal bacterial community of shrimp Penaeus vannamei infected with acute hepatopancreatic necrosis disease (AHPND). METHODS AND RESULTS: After 42 days of feeding trail, shrimp were inoculated with a Vibrio parahaemolyticus (CIB-0018-3) carrying the plasmid encoding for the PirAB toxins responsible for AHPND. After 120 h postinfection (hpi), shrimp fed with a diet containing 2% of a mix with Curcuma longa and Lepidium meyenii (TuMa) and a diet containing 0.2% of vitamin C (VitC) showed a significantly higher survival (85%) compared to the remaining treatments (50%-55%) (p < 0.05). Infected shrimp fed with TuMa diet, showed a significant reduction of Vibrionales, and VitC diet promoted an increase of Alteromonadales. CONCLUSIONS: Our findings suggest that the TuMa diet conferred protection against AHPND and could be attributed to a combined effect of antibacterial properties against Vibrionales, and promoting a desirable bacterial community in the shrimp intestine, while the VitC diet protection could be attributed to their antioxidant capacity and in a lower proportion to a bacterial modulation in shrimp gut. SIGNIFICANCE AND IMPACT OF THE STUDY: Acute hepatopancreatic necrosis disease is a devastating disease that significantly affects aquaculture production of shrimps. Therefore, the use of functional diets that promote resistance to AHPND represents a valuable tool to reduce the mortality of farmed shrimp.

The white spot syndrome virus hijacks the expression of the Penaeus vannamei Toll signaling pathway to evade host immunity and facilitate its replication.

The white spot syndrome virus (WSSV), the most lethal pathogen of shrimp, is a dsDNA virus with approximately a 300,000 base pairs and contains approximately 180-500 predicted open reading frames (ORFs), of which only 6% show homology to any known protein from other viruses or organisms. Although most of its ORFs encode enzymes for nucleotide metabolism, DNA replication, and protein modification, the WSSV uses some of its encoded proteins successfully to take control of the metabolism of the host and avoid immune responses. The contribution of the shrimp innate immune response to prevent viral invasions is recognized but yet not fully understood. Thus, the role of several components of Toll pathway of the shrimp Penaeus vannamei against WSSV has been previously described, and the consequential effects occurring through the cascade remain unknown. In the current study the effects of WSSV over various components of the shrimp Toll pathway were studied. The gene expression of Spätzle, Toll, Tube, Cactus and Dorsal was altered after 6-12 h post inoculation. The expression of LvToll3, LvCactus, LvDorsal, decreased ~4.4-, ~3.7- and ~7.3-fold at 48, 24 and 48 hpi, respectively. Furthermore, a remarkable reduction (~18-fold) in the expression of the gene encoding LvCactus in WSSV infected specimens was observed at 6 hpi. This may be a sophisticated strategy exploited by WSSV to evade the Toll-mediated immune action, and to promote its replication, thereby contributing to viral fitness.

White spot syndrome virus down-regulates expression of histones H2A and H4 of Penaeus vannamei to promote viral replication.

The white spot syndrome virus (WSSV) is a highly lethal and contagious pathogen to most cultivated shrimp species. The WSSV genome contains the ICP11 gene and its encoded protein acts as a multifunctinal DNA mimic protein that disrupts the nucleosome assembly by binding to the histone proteins H2A and H3. In addition, WSSV provokes severe nuclear hypertrophy and DNA damage. However, little is known about the influence of WSSV on the expression of the host's genes encoding for histones. Therefore, we investigated the effect of WSSV infection on the expression of the genes encoding histones in shrimp Penaeus vannamei. An RT-qPCR assay was performed to evaluate the temporal expression of H2A and H4 transcripts in the shrimp. Significant changes were observed in the expression of these genes, which coincided with the dynamics of replication of the virus. H2A reached its maximum expression levels at 12 hpi. Thus, it may be suggested that this is a viral strategy to evade the host's immune response in order to promote viral replication.

Metabolic turnover rate, digestive enzyme activities, and bacterial communities in the white shrimp Litopenaeus vannamei under compensatory growth.

The present work aimed to evaluate the effects promoted by a phase of compensatory growth on metabolic turnover rate, digestive enzyme activity, and bacterial biota of the Pacific white shrimp Litopenaeus vannamei kept under different feeding regimes. Three treatments were evaluated as follows: 70% feed restriction during 3 (T3) and 6 (T6) days, followed by a period of feeding to satiety, and a control treatment without restriction periods. The results showed a full compensatory growth in treatments T3 and T6 by day 35 of the bioassay. A significant increase in trypsin and lipase (T6) activities was observed during compensatory growth, whereas specific amylase activity was significantly lower in treatment T6 compared to T3 but not significantly different from the control group. To determine the metabolic turnover rate of nitrogen in muscle tissue, an analysis of nitrogen isotope values (δ15N) at natural abundance levels was performed. At the end of the experimental period, shrimp under feed restriction had lower metabolic turnover rates and longer nitrogen residence times (t 50) in muscle tissue, as compared to individuals in the control treatment. Regarding the changes in the bacterial communities in shrimp gut, no significant differences were observed at the phylum level, with Proteobacteria being the most abundant bacteria, followed by Actinobacteria. At family taxa level, Rhodobacteraceae presented the highest relative abundance in all treatments, whereas a decrease in Vibrionaceae was observed in treatments T3 and T6 when compared to control shrimps during compensatory growth. At the genus level, a decrease in Celeribacter, Catenococcus, and Epibacterium, and an increase in Ruegeria and Shimia, were identified in shrimp subjected to feed restriction when compared to control organisms during compensatory growth (day 14). At the end of the experimental period, the evaluated parameters showed similar results as those observed in the control treatment, suggesting a normalization of the metabolism and the physiological state. The present findings contribute to a better understanding on the physiological effects produced during compensatory growth in shrimp, which in turn could assist in the development of improved feeding strategies in benefit of the aquaculture industry.

Use of seaweed Ulva lactuca for water bioremediation and as feed additive for white shrimp Litopenaeus vannamei.

Two experimental feeding trials were conducted during four weeks to evaluate the use of Ulva lactuca in shrimp culture: (1) for wastewater bioremediation, and (2) using different inclusion levels of U. lactuca meal in shrimp feed. In feeding trial 1, shrimp reared under seaweed U. lactuca water exchange in a re-circulation system (SWE) resulted in similar growth and feed utilization as shrimp reared with clean water exchange (CWE). Shrimp under no water exchange (NWE) resulted in significant lower growth and higher feed conversion rate (FCR) compared to the other treatments (p < 0.05). Nitrogen compounds and phosphate in water from SWE and CWE treatments did not present significant differences during the experimental trial (p > 0.05). In feeding trial 2, U. lactuca biomass produced by wastewater bioremediation in SWE treatment were dried and ground to formulate diets containing 0, 1, 2, and 3% U. lactuca meal (0UL, 1UL, 2UL, and 3UL). Shrimp fed the 3 UL diet resulted in a significant (p < 0.05) improvement of growth and FCR, and enhanced whole shrimp lipid and carotenoid content by 30 and 60%, respectively, compared to control diet. Seaweed U. lactuca is suggested as a desirable species for wastewater bioremediation in integrated aquaculture systems, and its meal as a good feed additive for farmed shrimp.

Chemical composition of cultivated seaweed Ulva clathrata (Roth) C. Agardh.

Samples of cultivated Ulva clathrata were collected from a medium scale system (MSS, 1.5×1.5m tank), or from a large scale system (LSS, 0.8ha earthen pond). MSS samples were dried directly while the LSS sample was washed in freshwater and pressed before drying. Crude protein content ranged 20-26%, essential amino acids accounting for 32-36% of crude protein. The main analysed monosaccharides were rhamnose (36-40%), uronic acids (27-29%), xylose (10-13%) and glucose (10-16%). Some notable variations between MSS and LSS samples were observed for total dietary fibre (26% vs 41%), saturated fatty acids (31% vs 51%), PUFAS (33% vs 13%), carotenoids (358 vs 169mgkg-1dw) and for Ca (9 vs 19gkg-1), Fe (0.6 vs 4.2gkg-1), Cu (44 vs 14mgkg-1), Zn (93 vs 17mgkg-1) and As (2 vs 9mgkg-1). The chemical composition of U. clathrata indicates that it has a good potential for its use in human and animal food.

Colon tóxico amibiano con y sin perforación: conducta quirúrgica / Amoebic toxic colon with and without perfuration: surgical management

Se trataron quirúrgicamente 47 pacientes de colon tóxico amibiano en el Instituto Nacional de Pediatría, 27 con perforación del colon y 20 sin perforación durante un período de 12 años (enero de 1972 a diciembre de 1984). En los 27 pacientes perforados, las zonas más afectadas fueron el colon ascendente, transverso y descendente; en 4 pacientes estuvo afectada la totalidad del colon. A 18 se les practicó colectomía subtotal, a 4 hemicolectomía, a otros 4 colectomía total y en 1 caso colostomia. A los pacientes no perforados sólo se les practicó derivación fecal mediante ileostomía. En ambos grupos hubo un número importante de complicaciones posoperatorias, de todas ellas una de las más frecuentes fue la estenosis en el colon desfuncionalizado (40% de los pacientes que sobrevivieron). La reintervención quirúrgica que ocupó el primer lugar fue el cierre de la ileostomía; otro grupo importante fue la resolución quirúrgica de las zonas de estenosis incluyendo 3 pacientes a quienes se practicó rectoplastía sagital posterior sin que se alterara la continencia fecal. La mortalidad global fue de 47%

Quiste del colédoco: doce años de experiencia; revisión de 29 casos / Commonbile duct cyst: 12 years of experience; review of 29 cases

De 29 pacientes con quiste del colédoco admitidos en el Instituto Nacional de Pediatría, durante los últimos 12 años, ls variedad tipo I de Afonso fue la única observada; otras anomalías asociadas frecuentemente fueron las dilataciones de las vías biliares intra y extrahepática, además de disposición anómala de la unión del colédoco-Wirsung. El pronóstico depende del grado de lesión hepática al momento de la corrección quirúrgica. Los autores recomiendan la resección del quiste como el tratamiento más eficaz

Enfermedad isquémica intestinal: enterocolitis necrosante; indicaciones quirúrgicas / Ischemic intestinal disease: necrotising enterocolitis; surgical indications

Se operaron 100 pacientes por enfermedad isquémica intestinal (enterocolitis necrosante) en el Instituto Nacional de Pediatria desde enero de 1974 a diciembre de 1983). Se dividieron en dos grupos, el de recién nacidos, 47 pacientes, y el de pacientes mayores 53. En el primero, 67% fueron de término y 33% de pretérmino; en el segundo la edad fue de 2 a 12 meses; hubo 4 mayores de 1 año. Sólo 21 pacientes fueron operados dentro del tiempo óptimo quirúrgico; en 59 la operación se indicó tardiamente y en 20 fue prematura. En el grupo operado tardiamente, en 25 la tardanza fue por ingreso al hospital tardiamente. En otros 34 pacientes el retraso se debió a nuestro personal médico quirúrgico. La mortalidad en el grupo operado a tiempo fue de 71%. En los pacientes con gangrena generalizada la mortalidad fue de 100%. En el grupo de pacientes recuperables fue de 61%. La mortalidad global fue de 77%. El 31,5% de los pacientes perforados, no presentaron imagen radiológica de neumoperitoneo. En el 75% de los pacientes con gangrena, había datos de neumatosis intestinal pero el 35% de los pacientes sin gangrena también tenían neumatosis. De todos los pacientes con neumatosis hepática, el 24% tenía gangrena intestinal por lo que consideramos que esta es una información nueva y por si sola obliga a una exploración quirúrgica

Reflujo gastroesofágico en niños: experiencia en 100 casos tratados con funduplicación de Nissen / Gastroesophageal reflux in children: experience in 100 cases treated with Nissen's funduplication

Se analizan retrospectivamente 100 casos de enfermedad por reflujo gastroesofágico estudiados y tratados dentro de un protocolo previamente establecido. El diagnóstico se fundamentó en la presencia de reflujo gastroesofágico patológico observado durante la fase dinámica de la serie esofagogastroduodenal, asociado o no a hernia hiatal y/o estenosis esofágica. La edad promedio en la serie fue de 3.7 años. Los pacientes fueron referidos por vómito persistente y disfagia en el 40% de los casos, por vómito persistente en el 30%, por neumopatia crónica en el 23% y por cuerpo extraño en el tercio inferior del esófago en el 7%. Las indicaciones para tratamiento quirúrgico fueron: estenosis esofágica, falla del tratamiento médico, reflujo patológico asociado a hernias hiatales con 20% o más de estómago intratorácico y hemorragia gastroesofágica aguda asociada a reflujo patológico. Los tiempos fundamentales de la técnica quirúrgica fueron: descenso intraperitoneal de la unión esofagogástrica, reconstrucción anatómica del hiato esofágico, funduplicación de Nissen y gastrostomía. El 94% de los casos presentó molestia digestiva postprandial en los primeros seis meses postoperatorios; cuatro pacientes presentaron dilatación gástrica aguda con perforación del fundus, dos de ellos fallecieron; la estenosis esofágica desapareció en el primer mes postoperatorio, sin necesidad de dilataciones, en 13 (21%) de los 63 casos complicados con estenosis. La evolución postoperatoria después de uno a 12 años de seguimiento mostró: curación en el 92%, mortalidad operatoria 4%, mortalidad no operatoria 2% y recidiva de la enfermedad en el 2%. Se concluye que es necesario aumentar la información a pediatras y médicos generales en relación con enfermedad por reflujo gastroesofágico, porque la edad promedio de la serie y la elevada incidencia de estenosis esofágica sugiere retraso extrahospitalario en el diagnóstico y tratamiento. La funduplicación de Nissen es una excelente operación antirreflujo; sin embargo, es necesario evaluar otras opciones de procedimientos antirreflujo de manera de evitar la morbiletalidad informada en esta serie

Repercusiones psicológicas de la ausencia testicular y el uso de prótesis / Psychological repercussions of the absence of testis and the use of prosthesis

Se presenta la experiencia con 17 niños en quienes se implantó una prótesis testicular por diversas causas y la repercusión psicológica de esta intervención que tienen los pacientes, sobre todo los mayores de 12 años y los padres