Transcriptome analysis of reproductive tract tissues of male river prawn Macrobrachium americanum.

BACKGROUND: The river prawn, Macrobrachium americanum (M. americanum), is one of the largest prawns of the genus in Latin America and is an amphidromous species distributed along the Pacific coast of America. This prawn has commercial value due to its size and taste, making it a good option for aquaculture production. Its culture has been attempted in ponds and concrete tanks, but no successful technique can still support commercial production. Understanding the mechanisms that regulate reproduction at the molecular level is very important. This knowledge can provide tools for manipulating transcripts, which could increase the number or size of animals in the culture. Our understanding of the mechanism that regulates the reproduction of M. americanum at the molecular level is limited. AIM: Perform and analyze the transcriptome assembly of the testes, vas deferens, and terminal ampulla of M. americanum. to provide new molecular information about its reproduction. METHODS AND RESULTS: The cDNA library was constructed and sequenced for each tissue to identify novel transcripts. A combined transcriptome with the three tissues was assembled using Trinity software. Unigenes were annotated using BLASTx and BLAST2GO. The transcriptome assembly generated 1,059,447 unigenes, of which 7222 genes had significant hits (e-value < 1 × 10-5) when compared against the Swiss-Prot database. Around 75 genes were related to sex determination, testis development, spermatogenesis, spermiogenesis, fertilization, maturation of testicular cells, neuropeptides, hormones, hormone receptors, and/or embryogenesis. CONCLUSIONS: These results provide new molecular information about M. americanum reproduction, representing a reference point for further genetic studies of this species.

Combined administration routes of marine yeasts enhanced immune-related genes and protection of white shrimp (Penaeus vannamei) against Vibrio parahaemolyticus.

Antibiotic usage to control infectious diseases in shrimp aquaculture has led to serious problems on antimicrobial resistance. An alternative to mitigate this issue is the use of probiotics, which can be easily administered by feed and water. This study examines immunomodulatory and protective effects of the marine yeasts Debaryomyces hansenii CBS8339 (Dh) and Yarrowia lipolytica Yl-N6 (Yl) -alone and mixed-in white shrimp Penaeus vannamei post-larvae. Administration routes (fed and water alone or in combination), supplementation frequency and time elapsed after the last dietary supplement were tested on growth and gene expression of penaeidin, lectin, lysozyme, superoxide dismutase, catalase, and peroxidase, as well as survival upon Vibrio parahaemolyticus IPNGS16 challenge. Penaeidin and lectin genes were upregulated in post-larvae fed orally with Yl or combined Dh + Yl. Higher growth and survival for yeast supplementation treatments were observed compared to the control group, mainly when yeasts (Dh + Yl) and administration routes (feed and water) were combined. In conclusion, mixed yeast and combined administration routes improved growth and immunity against V. parahaemolyticus.

Physiological and antioxidant response of Litopenaeus vannamei against Vibrio parahaemolyticus infection after feeding supplemented diets containing Dunaliella sp. flour and ß-glucans.

The presence of pathogen agents in shrimp farming is the main obstacle for successful aquaculture. Vibrio species are naturally part of water because they play an important role as opportunistic bacteria. Vibrio parahaemolyticus was identified as the causative agent of the Early Mortality Syndrome in 2009, causing the loss of shrimp farming worldwide. Dunaliella sp. flour has been tested against Vibrio infection proving to be an effective prophylactic method that decreases mortality and improves physiological and immune response in Litopenaeus vannamei. Juvenile shrimp were exposed to 2% Dunaliella sp. flour and commercial 1.1% ß -glucan diet provided every other day for 15 days and a posterior infection with V. parahaemolyticus (1 × 106 CFU/mL). To evaluate shrimp stress status, some parameters as glucose, lactate, cholesterol, triglycerides, relative superoxide dismutase (SOD) gene expression and circulating hemocytes were analyzed in hemolymph at zero and seven days before infection and at 0, 24, and 48 h post-infection. L. vannamei fed with Dunaliella sp. showed 93% and ß -glucan 87% survival, compared with 79% in the infected control group. Additionally, Dunaliella sp. improved hemocyte and lipid concentrations compared to ß -glucan while both immunostimulants showed an increase in SOD response against bacteria. The addition of 2% Dunaliella sp. every other day in L. vannamei diet enhanced stress response against V. parahaemolyticus infection.

Dry matter, protein, and energy digestibility of diets for juvenile Pacific white leg shrimps (Litopenaeus vannamei) reared at different salinity levels / Digestibilidade da matéria seca, proteína e energia de dietas para camarão juvenil do Pacífico (Litopenaeus vannamei) cultivadas em diferentes níveis de salinidades

ABSTRACT: This study evaluated the effect of low, medium, and high-water salinity (5, 35, and 50 ppt) on the apparent dry matter, protein, and energy digestibility of two formulated and six commercial diets for juvenile whiteleg shrimp, Litopenaeus vannamei, in a 120-day trial. Digestibility was determined in vivo using chromic oxide as an inert diet marker. Hydrostability in pellets varied from 86.8% to 99.9%; dry matter digestibility varied from 49.1% to 64.1%; protein digestibility showed greater variations at all salinities (56.9%-85.8%); and energy digestibility ranged from 70.1 to 86.4%. Salinity had a significant effect on dry matter, protein, and energy digestibility. Using a principal component analysis (PCA) with a covariance matrix, our findings suggested that the E2 (fishmeal-based formulation) diet and 35 ppt salinity provided optimum hydrostability and digestibility to Pacific white leg shrimp juveniles.

RESUMO: Nós medimos o efeito de baixa, normal e alta salinidade (5, 35 e 50ppt) na digestibilidade aparente da matéria seca, proteína e energia em duas dietas formuladas e seis comerciais para camarão juvenil do Pacífico, Litopenaeus vannamei. Os coeficientes de digestibilidade aparente da matéria seca, proteína e energia foram determinados in vivo utilizando o óxido crômico como marcador inerte nas dietas (peso inicial médio de 4g), em um teste de 120 dias. Hidrostabilidade na dieta de 86,8% a 99,9%, os coeficientes de digestibilidade da matéria seca variaram de 49,1 a 64,1%, os coeficientes de digestibilidade da proteína apresentaram maiores variações em todas as salinidades (56,9-85,8%), enquanto os coeficientes de digestibilidade da energia variaram de 70,1 a 86,4%. Efeito significativo da salinidade na digestibilidade da matéria seca, proteína e energia foi encontrado. Esses resultados, usando a análise de componentes principais (PCA) com a matriz de covariância, sugerem que a dieta E2 (fórmula à base de farinha de peixe) e salinidade a 35 ppt é ideal para a hidrostabilidade e digestibilidade das dietas para juvenis de camarão-branco-do-Pacífico.

Dosage and frequency effects of the microalgae Dunaliella sp. on the diet of Litopenaeus vannamei challenged with Vibrio parahaemolyticus.

Carotenoid sources in shrimp diets have shown to be effective for improving survival, growth, reproductive capacity, stress resistance, and also for diminishing disease. Dunaliella sp. is known to have high levels of ß-carotenes, which works as pro-vitamin A, enhancing the immune response in shrimp. However, the administration of Dunaliella sp. in shrimp diet needs to be evaluated to determine the appropriate dose and frequency of administration needed to optimize performance in cultured white shrimp. Diets with three different concentrations of Dunaliella sp. flour (1.5, 2 and 3%) were tested, and each one was administered at three different time frequencies: daily, and at 3- and 7-days intervals. Shrimp fed for 20 days were then infected with Vibrio parahaemolyticus (1 × 106 CFU/mL). Hemolymph parameters including protein, glucose, lactate, cholesterol and triglycerides were analyzed to evaluate shrimp stress status. Additionally, L. vannamei innate non-specific immune response was examined by evaluating the activity of prophenoloxidase (proPO), phenoloxidase (PO) and superoxide dismutase (SOD) in hemolymph; shrimp survival was also recorded. Survival after infection with V. parahaemolyticus was higher for shrimp fed with diets consisting of 2% Dunaliella sp. administered every 3 and 7 days. Shrimp fed a diet consisting of 2% or 3% Dunaliella sp. administered every third day showed positive physiological and immune responses to infection. A decrease in lipid oxidation in plasma triglycerides was observed at 48 h post inoculation in shrimp fed at all diets regimes due to Dunaliella sp. antioxidant action. Experimental results suggest the importance of Dunaliella sp. dosage and feeding frequency in L. vannamei diet to improve the survival and immune response.

Survival of Litopenaeus vannamei shrimp fed on diets supplemented with Dunaliella sp. is improved after challenges by Vibrio parahaemolyticus.

Survival of Litopenaeus vannamei was evaluated during a Vibrio parahaemolyticus infection. This bacteria has been causing significant economic losses in the shrimp industry due to the appearance of early mortality syndrome (EMS), also known as acute hepatopancreatic necrosis disease (AHPND). Control of bacteria in ponds is difficult to achieve with antibiotics due to environmental infections and antibiotic resistance. New methods have been proposed to control and prevent the impact of bacterial infections. The physiological response indicated by plasma biochemical parameters in shrimp can determine their health and stress status. Meanwhile, shrimp immunology is the key factor in establishing strategies to control diseases. Immunostimulants are the best alternative to antibiotics to prevent or minimize disease damage, and at the same time, these stimulants improve the immune system in shrimp. Four diets containing 1.5, 2, 2.5 and 3% of Dunaliella sp. with high ß-carotene content were tested in the present study. After 20days of feeding, organisms were infected with V. parahaemolyticus. Protein, glucose, lactate, triglyceride and cholesterol levels, as well as activity of prophenoloxidase and phenoloxidase, were determined 48 h post-infection (hpi). Shrimp fed a diet with 3% Dunaliella sp. showed the highest survival. Glucose, cholesterol, and triglyceride levels, as well as prophenoloxidase and phenoloxidase activity, were not observed to be suitable indicators during this bacterial infection. The results indicated that the inclusion of Dunaliella sp. in diet increases survival in L. vannamei infected with V. parahaemolyticus.

Apparent carbohydrate and lipid digestibility of feeds for whiteleg shrimp, Litopenaeus vannamei (Decapoda: Penaeidae), cultivated at different salinities.

Whiteleg shrimp, Litopenaeus vannamei is one of the most commercially farmed species worldwide because of its fast growth, good survival rate at high farming densities, and osmoregulatory capacity, which makes it an excellent candidate for cultures at different salinities. The knowledge of shrimp nutritional requirements is critical in the formulation of diets to allow optimal growth at different environmental conditions and development stages. The effect of salinity on apparent digestibility of shrimp feed is not well known, and this information is required in shrimp diet formulation. For this purpose, the apparent digestibility coefficients of carbohydrates (ACD) and lipids (ALD) were determined for juvenile whiteleg shrimps under controlled culture conditions. We evaluated the apparent digestibility of six commercial (D1:37CP, D2:38CP, D3:39CP, D4:34CP, D5:35CP, and D6:37CP) and two experimental (E1:33CP and E2:33CP) diets for juvenile whiteleg shrimp cultivated at three salinities (5, 35 and 50 psu) in 60 L aquariums. ACD and ALD were determined in vivo using chromic oxide as an inert marker. Our results showed that ALD in most cases was over 80%, independent of salinity, except the E1:33CP diet which had 74.0% at 50 psu. Diet D3:39CP showed the highest ALD coefficient (90.1 and 90.6% at 5 and 35 psu, respectively). For ACD, differences were detected between commercial and experimental diets at every salinity level, although salinity effect on ACD was not significant. Diet D4:34CP had the highest coefficient (92.4%) at 5 psu, and E2:33CP at 35 and 50 psu (97.3 and 94.7%). This study demonstrated that there is no significant effect of saline variations on carbohydrate and lipid digestibility by juvenile whiteleg shrimp, under the experimental conditions.

Apparent carbohydrate and lipid digestibility of feeds for whiteleg shrimp, Litopenaeus vannamei (Decapoda: Penaeidae), cultivated at different salinities / Digestibilidad aparente de carbohidratos y lípidos en alimentos para camarón blanco, Litopenaeus vannamei (Decapoda: Penaeidae), cultivados en diferentes salinidades

Whiteleg shrimp, Litopenaeus vannamei is one of the most commercially farmed species worldwide because of its fast growth, good survival rate at high farming densities, and osmoregulatory capacity, which makes it an excellent candidate for cultures at different salinities. The knowledge of shrimp nutritional requirements is critical in the formulation of diets to allow optimal growth at different environmental conditions and development stages. The effect of salinity on apparent digestibility of shrimp feed is not well known, and this information is required in shrimp diet formulation. For this purpose, the apparent digestibility coefficients of carbohydrates (ACD) and lipids (ALD) were determined for juvenile whiteleg shrimps under controlled culture conditions. We evaluated the apparent digestibility of six commercial (D1:37CP, D2:38CP, D3:39CP, D4:34CP, D5:35CP, and D6:37CP) and two experimental (E1:33CP and E2:33CP) diets for juvenile whiteleg shrimp cultivated at three salinities (5, 35 and 50psu) in 60L aquariums. ACD and ALD were determined in vivo using chromic oxide as an inert marker. Our results showed that ALD in most cases was over 80%, independent of salinity, except the E1:33CPdiet which had 74.0% at 50psu. Diet D3:39CP showed the highest ALD coefficient (90.1 and 90.6% at 5 and 35psu, respectively). For ACD, differences were detected between commercial and experimental diets at every salinity level, although salinity effect on ACD was not significant. Diet D4:34CP had the highest coefficient (92.4%) at 5psu, and E2:33CP at 35 and 50psu (97.3 and 94.7%). This study demonstrated that there is no significant effect of saline variations on carbohydrate and lipid digestibility by juvenile whiteleg shrimp, under the experimental conditions. Rev. Biol. Trop. 61 (3): 1201-1213. Epub 2013 September 01.

El camarón blanco, Litopenaeus vannamei, es una de las especies más cultivadas comercialmente en el mundo, debido a su velocidad de crecimiento y tasa de supervivencia en altas densidades de cultivo, y su capacidad de osmoregulación, que lo hacen un excelente candidato para cultivo en diferente salinidades. El conocimiento de los requerimientos nutricionales del camarón es fundamental en la formulación de dietas que permita el crecimiento óptimo en diferentes condiciones ambientales y fases de desarrollo del animal. El efecto de la salinidad sobre la digestibilidad aparente de alimentos comerciales para camarones no está documentado. Esta información es necesaria en el cultivo de camarón para la formulación de los alimentos comerciales. Se determinó la digestibilidad aparente de los carbohidratos (ACD) y lípidos (ALD), en juveniles del camarón blanco L. vannamei cultivado en condiciones controladas. Los tratamientos fueron seis dietas comerciales (D1:37CP, D2:38CP, D3:39CP, D4:34CP, D5:35CP y D6:37CP) y dos dietas experimentales (E1:33CP y E2:33CP) para juveniles de camarón blanco en cultivo, a tres salinidades (5, 35 y 50ups) en acuarios de 60L. Los coeficientes de digestibilidad aparente de los carbohidratos (ACD) y los lípidos (ALD) fueron determinados in vivo utilizando óxido crómico como marcador inerte en la dieta. ALD en la mayoría de los tratamientos fue superior al 80%, independientemente de la salinidad, con excepción de la dieta E1:33CP que presentó 74.0% a salinidad de 50ups. La dieta D3:39CP presentó el mayor coeficiente ALD (90.1 y 90.6 en 5 y 35ups, respectivamente). En ACD, se presentaron diferencias entre dietas comerciales y experimentales en cada nivel de salinidad, aunque la salinidad no presentó un efecto significativo. La dieta D4:34CP presentó el coeficiente de digestibilidad más alto (92.4%) en la salinidad de 5ups, mientras que E2:33CP en salinidades de 35 y 50ups fue de 97.3 y 94.7%, respectivamente. En general, el presente estudio demuestra que en juveniles de camarón blanco la variación de salinidad no afecta significativamente la digestibilidad de lípidos y carbohidratos en las condiciones experimentales de este estudio.