Exploring the Impact of the Biofloc Rearing System and an Oral WSSV Challenge on the Intestinal Bacteriome of Litopenaeus vannamei.

We provide a global overview of the intestinal bacteriome of Litopenaeus vannamei in two rearing systems and after an oral challenge by the White spot syndrome virus (WSSV). By using a high-throughput 16S rRNA gene sequencing technology, we identified and compared the composition and abundance of bacterial communities from the midgut of shrimp reared in the super-intensive biofloc technology (BFT) and clear seawater system (CWS). The predominant bacterial group belonged to the phylum Proteobacteria, followed by the phyla Bacteroidetes, Actinobacteria, and Firmicutes. Within Proteobacteria, the family Vibrionaceae, which includes opportunistic shrimp pathogens, was more abundant in CWS than in BFT-reared shrimp. Whereas the families Rhodobacteraceae and Enterobacteriaceae accounted for almost 20% of the bacterial communities of shrimp cultured in BFT, they corresponded to less than 3% in CWS-reared animals. Interestingly, the WSSV challenge dramatically changed the bacterial communities in terms of composition and abundance in comparison to its related unchallenged group. Proteobacteria remained the dominant phylum. Vibrionaceae was the most affected in BFT-reared shrimp (from 11.35 to 20.80%). By contrast, in CWS-reared animals the abundance of this family decreased from 68.23 to 23.38%. Our results provide new evidence on the influence of both abiotic and biotic factors on the gut bacteriome of aquatic species of commercial interest.

Effects of dietary replacement of fishmeal by mealworm meal on muscle quality of farmed shrimp Litopenaeus vannamei.

This study investigated the muscle quality of the shrimp Litopenaeus vannamei fed on a diet containing different proportions of mealworm meal (MW) (0, 25, 50, 75 and 100%) as a substitute for fishmeal, which is the normal diet used in shrimp commercial production. The proximate composition, fatty acid profile, colour and texture of the shrimps were evaluated. Moisture, protein, and ash content of shrimp muscle were not significantly altered when fishmeal was replaced by MW (p>0.05). However, the replacement resulted in a linear increase in lipid content (p<0.05). The fatty acid composition of the experimental diets directly mirrored the fatty acid composition of shrimp muscle. The absence of long-chain polyunsaturated fatty acids in MW composition resulted in a linear decrease in eicosapentaenoic and docosahexaenoic fatty acids in shrimp muscle with increasing levels of MW in the diet. The n-3/n-6 ratio ranged from 0.50 to 0.67. Colour and firmness were unchanged between the treatments. Although the use of MW as a fishmeal substitute in L. vannamei diets has affected the lipid and fatty acid composition of shrimp muscle, from a human nutritional perspective, the lipid content of the shrimps is considered low and the n-3/n-6 ratio remained within the human dietary requirements. Therefore the use of a mealworm diet for shrimp production is a viable alternative to increasingly expensive fishmeal based diets.

Transcriptional profiling of immune-related genes in Pacific white shrimp (Litopenaeus vannamei) during ontogenesis.

We have performed here a gene expression analysis to determine the developmental stage at the main genes involved in crustacean immune response begin to be expressed and their changes in mRNA abundance during shrimp development. By using a quantitative PCR-based approach, we have measured the mRNA abundance of 24 immune-related genes from different functional categories in twelve developmental stages ranging from fertilized eggs to larval and postlarval stages and also in juveniles. We showed for the first time that the main genes from the RNAi-based post-transcriptional pathway involved in shrimp antiviral immunity are transcribed in all developmental stages, but exhibit a diverse pattern of gene expression during shrimp ontogenesis. On the other hand, hemocyte-expressed genes mainly involved in antimicrobial defenses appeared to be transcribed in larval stages, indicating that hematopoiesis initiates early in development. Moreover, transcript levels of some genes were early detected in fertilized eggs at 0-4 h post-spawning, suggesting a maternal contribution of immune-related transcripts to shrimp progeny. Altogether, our results provide important clues regarding the ontogenesis of hemocytes as well the establishment of antiviral and antimicrobial defenses in shrimp.

Ultra-low temperature conservation of Brazilian pine embryogenic cultures.

This study aimed to establish a cryopreservation protocol for embryogenic cultures of A. angustifolia, enabling the ex situ conservation of the species. Embryogenic cultures were established from immature seeds and treated with variations of the cryoprotectant solutions SuDG, SoD and PVS2 prior to immersion in liquid nitrogen. Cell viability was evaluated after 30, 60 and 90 days of re-growth. The highest re-growth without morphological alterations and with normal biochemical composition was obtained with the PVS2 solution with 40 min immersion in ethanol (-20 °C). This procedure opens new horizons for the ex situ conservation of the species genetic.

Hematological and immunological responses of Nile tilapia after polyvalent vaccine administration by different routes / Resposta hematológica e imunológica de tilápia do Nilo após administração de vacina polivalente por diferentes vias

The efficacy of a polyvalent bacterin vaccine against Aeromonas hydrophila, Pseudomonas aeroginosa and Enterococcus durans administered by different routes in Nile tilapia was assessed by analyzing hematological and immunological parameters 7 and 21 days after vaccination. Treatments consisted of: non-vaccinated tilapia; tilapia vaccinated by intraperitoneal injection with 2x10(8) formalin-inactivated bacteriaÀmL-1; tilapia vaccinated orally with 2x10(7) formalin-inactivated bacteriaÀg-1, feed for 5 days; tilapia vaccinated by immersion bath in 2x10(7) formalin-inactivated bacteriaÀmL-1, for 20 minutes. Vaccinated fish groups presented higher hematocrit, number of erythrocytes and leukocytes than the non-vaccinated group. Serum agglutination titer of intraperitoneally vaccinated fish was higher on both evaluation periods for the three bacteria strains. Only on day 21 post-vaccination fish from the oral and immersion vaccination groups presented higher serum agglutination titer than the non-vaccinated fish for A. hidrophyla and E. durans. Serum antimicrobial activity in vaccinated fish was higher for P. aeroginosa and E. coli than in non-vaccinated fish on both evaluation periods. The different vaccine administration routes stimulated hematological and immunological responses in Nile tilapia 21 days post-vaccination, but intraperitoneal vaccination presented higher total number of leukocytes, lymphocytes and serum agglutination titer.

Este estudo avaliou a eficácia da administração de vacina polivalente (bacterina), contra Aeromonas hydrophila, Pseudomonas aeroginosa e Enterococcus durans, por diferentes vias de aplicação em tilápia do Nilo, analisando parâmetros hematológicos e imunológicos no 7º e 21º dia após vacinação. Os tratamentos consistiram de: tilápias não vacinadas; tilápias vacinadas via injeção intraperitoneal (i.p.) contendo 2x10(8) bactérias inativadasÀmL-1; tilápias alimentadas com ração contendo vacina na proporção de 2x10(7) bactérias inativadasÀg-1, durante 5 dias; tilápias vacinadas por banho de imersão em 2x10(7) bactérias inativadasÀmL-1, durante 20 minutos. Os peixes vacinados apresentaram maior porcentagem de hematócrito, número de eritrócitos e leucócitos durante o período do experimento, em relação aos não vacinados. O título de aglutinação do soro dos peixes vacinados intraperitonealmente foi superior nos dois períodos de avaliação para todas as bactérias. Apenas no 21º dia os peixes vacinados oralmente e por imersão apresentaram título de aglutinação superior aos peixes não vacinados para A. hidrophyla e E. durans. O soro dos peixes vacinados apresentou maior atividade antimicrobiana para P. aeroginosa e E. coli, do que os peixes não vacinados, nos dois períodos. As diferentes vias de administração da vacina estimularam a resposta hematológica e imunológica da tilápia do Nilo após 21 dias de vacinadas, sendo que o número total de leucócitos, linfócitos, título aglutinante do soro dos vacinados i.p. foi maior do que os demais.

Leukocyte response and phagocytic activity in Nile tilapia experimentally infected with Enterococcus sp.

This study evaluated the total and differential leukocyte counting and the phagocytic activity in Nile tilapia Oreochromis niloticus experimentally injected with Enterococcus sp. in the swim bladder. Fish were distributed in four treatments in triplicates of non-injected fish, fish injected with 1 ml of sterile saline solution 0.65%, and fish injected with 1 x 10(3) and 1 x 10(6) colony-forming units (CFU) of Enterococcus diluted in 1 ml sterile saline. Twenty-four hours after injection, the fish were anesthetized and the blood collected for white blood cell (WBC) counts, differential counting of WBC, and phagocytic activity of blood leukocytes. The increased numbers of WBC and lymphocytes were followed by decreased number of monocyte after infection. The percentages of phagocytic activities in the blood were 55.3 and 55.9%, respectively, in tilapia injected with 1 x 10(3) and 1 x 10(6) CFU/ml.