21 research outputs found
Hemograma e sobrevivência de camarões marinhos após silenciamento do WSSV por RNA de interferência
The objective of this work was to evaluate the specific antiviral protection via RNA interference (RNAi) against the white spot syndrome virus (WSSV) in marine shrimp (Litopenaeus vannamei). Shrimp were injected with a dsRNA specific sequence (vp28 from the viral envelope), followed by challenge, with WSSV after 48 hours. The hemogram was evaluated at 0, 3, 6, 24, 48, and 72 hours after challenge and the mortality rate during 30 days. In animals treated with vp28 dsRNA the viral infection was limited, and survival (73%) and viral clearance (80%) were higher than in infected, not treated shrimp, which showed 100% mortality within five days. In shrimp treated with dsRNA, the hemogram decreased until 6 hours after viral challenge, followed by an increase, reaching normal levels at 72 hours. The treatment with vp28 dsRNA limits WSSV infection in shrimp, restores their immune conditions, and promotes viral clearance in most survivors. These results indicate that vp28 dsRNA can serve as a molecular tool for combating WSSV, and that RNAi represents a promising approach for the control of viral diseases in cultured shrimp.O objetivo deste trabalho foi avaliar a proteção antiviral especĂfica via RNA de interferĂŞncia (RNAi) contra o vĂrus da sĂndrome da mancha‑branca (WSSV), em camarões marinhos (Litopenaeus vannamei). Os camarões foram injetados com uma sequĂŞncia dsRNA especĂfica (vp28 do envelope viral), seguida por desafio com WSSV apĂłs 48 horas. Avaliaram-se o hemograma Ă s 0, 3, 6, 24, 48 e 72 horas apĂłs o desafio, e a taxa de mortalidade durante 30 dias. Nos animais tratados com dsRNA vp28, a infecção viral foi limitada, e a sobrevivĂŞncia (73%) e a “clearance” viral (80%) foram maiores do que nos camarões infectados, nĂŁo tratados, que apresentaram 100% de mortalidade em cinco dias. Nos camarões tratados com dsRNA, o hemograma diminuiu atĂ© 6 horas apĂłs o desafio, seguido por aumento, tendo atingido o nĂvel normal em 72 horas. O tratamento com dsRNA vp28 limita a infecção nos camarões por WSSV, restaura as suas condições imunolĂłgicas e promove “clearance” viral na maioria dos sobreviventes. Esses resultados sĂŁo indicativos de que dsRNA vp28 pode servir como ferramenta molecular para combater o WSSV e que o RNAi representa abordagem promissora para controlar doenças virais em camarões cultivados
Time-related action of Lactobacillus plantarum in the bacterial microbiota of shrimp digestive tract and its action as immunostimulant
O objetivo deste trabalho foi avaliar o tempo de atuação de Lactobacillus plantarum, na microbiota bacteriana intestinal de Litopenaeus vannamei, e sua relação com a contagem total de hemĂłcitos e a atividade da fenoloxidase apĂłs a exposição a Vibrio harveyi. Os camarões foram alimentados com dieta suplementada com probiĂłticos por oito dias e, depois, substituĂda por dieta comercial. Os camarões alimentados com dieta comercial constituĂram o controle. As avaliações foram realizadas no oitavo dia de experimento e repetidas dois, quatro, seis e oito dias depois. A contagem total de bactĂ©rias lácticas no intestino foi maior atĂ© o quarto dia de avaliação, no grupo alimentado com probiĂłticos. A contagem de Vibrio spp. foi superior no grupo controle nos dias zero e dois. AtĂ© o quarto dia, a contagem total de hemĂłcitos dos camarões apĂłs a inoculação de V. harveyi foi superior no grupo alimentado com probiĂłtico em relação ao grupo controle. NĂŁo foi observada diferença na atividade da fenoloxidase. No sexto dia, apĂłs a substituição da dieta suplementada com probiĂłticos por dieta controle, todos os parâmetros avaliados foram iguais nos dois grupos, o que indica que o tempo de atuação de L. plantarum em camarões Ă© curto.The objective of this work was to assess the time-related action of probiotic Lactobacillus plantarum in the bacterial microbiota of the digestive tract of Litopenaeus vannamei, and the relation of total haemocyte count and serum phenol oxidase activity of shrimp challenged with Vibrio harveyi. Shrimps were fed with a probiotic-supplemented diet, for eight days, then shifted to a commercial diet. Shrimps fed only with the commercial diet served as control. Evaluations were made on the 8th day of experiment and repeated two, four, six and eight days later. Total lactic bacteria in the digestive tract was higher until the 4th day of evaluation in the probiotic-supplemented group. Vibrio spp. counts were higher in the control at days zero and two. Until the 4th day of evaluation, the total haemocyte counts in shrimps after challenge with V. harveyi were higher in probiotic-supplemented group than in control group. Significant difference was not observed in phenol oxidase activity. On the 6th day after shifting from supplemented to control diet, all parameters were equal in both groups, suggesting that the time-related action of L. plantarum in shrimp is short
Cellular and Transcriptional Responses of Crassostrea gigas Hemocytes Exposed in Vitro to Brevetoxin (PbTx-2)
Hemocytes mediate a series of immune reactions essential for bivalve survival in the environment, however, the impact of harmful algal species and their associated phycotoxins upon bivalve immune system is under debate. To better understand the possible toxic effects of these toxins, Crassostrea gigas hemocytes were exposed to brevetoxin (PbTx-2). Hemocyte viability, monitored through the neutral red retention and MTT reduction assays, and apoptosis (Hoechst staining) remained unchanged during 12 h of exposure to PbTx-2 in concentrations up to 1000 µg/L. Despite cell viability and apoptosis remained stable, hemocytes incubated for 4 h with 1000 µg/L of PbTx-2 revealed higher expression levels of Hsp70 (p < 0.01) and CYP356A1 (p < 0.05) transcripts and a tendency to increase FABP expression, as evaluated by Real-Time quantitative PCR. The expression of other studied genes (BPI, IL-17, GSTO, EcSOD, Prx6, SOD and GPx) remained unchanged. The results suggest that the absence of cytotoxic effects of PbTx-2 in Crassostrea gigas hemocytes, even at high concentrations, allow early defense responses to be produced by activating protective mechanisms associated to detoxification (CYP356A1 and possibly FABP) and stress (Hsp70), but not to immune or to antioxidant (BPI, IL-17, EcSOD, Prx6, GPx and SOD) related genes
Estudo dos hemocitos e hemolinfa de trichosia pubescens (Diptera: sciaridae)
Tese (Doutorado) - Universidade de SĂŁo Paulo, Instituto de Biociencia
Evaluation of some hemato-immunological parameters in the mangrove oyster
The main purpose of this study was to establish the pattern of variability
of some hemato-immunological parameters in the mangrove oyster, Crassostrea rhizophorae, from 3Â different environmental conditions in Santa Catarina Island: two natural
habitats (mangrove and rocks of the coastal bay) and one oyster culture
station. The water quality was adequate in all localities. The animals were
collected seasonally over a period of one year (n = 30, per locality). The
oyster hemolymph comprised two basic cell populations, hyaline (HH) and
granular hemocytes (GH). Both cell populations contained carbohydrates and
glycogen in their cytoplasm (periodic acid Schiff reaction, PAS staining)
and the occurrence of lysosomes was suggested by the detection of acid
phosphatase (Gomori's method). Both hemocyte populations were able of
phagocytosis of zymosan particles in vitro and producing cytotoxic
molecules, such as the superoxide anions (nitroblue-tetrazolium, NBT
reduction). The oyster hemograms significantly differed in the different
habitats and also among seasons. The total circulating hemocyte counts (THC)
and the percentage of GH in the mangrove and rock oysters always differed
from each other, but not from those of the cultured oysters. The highest THC
and the lowest percentage of GH were always found in summer. The total
plasma protein concentration (PC) exhibited a similar seasonal pattern in
all oyster populations, with a marked decrease in spring. The PC of the
cultured oysters was almost always significantly lower than that of the
other oyster populations. The plasma agglutinating titer was higher in the
cultured oysters regardless of season. The histological organization of the
oyster digestive gland and gills was basically similar to that of other
oyster species. Their structural aspect did not show any detectable
alteration, corroborating that the oysters were in good health. The results
of this study will serve as a basis for further analyses on the monitoring
of C. rhizophorae health status and environmental quality in different aquatic habitats
Morphological characterization of the hemocytes of the pulmonate snail Biomphalaria tenagophila
The blood cells of the pulmonate snail Biomphalaria tenagophila, an important transmiter of the trematode Schistosoma mansoni in Brazil, were examined by ligth and transmission electron microscopy (TEM). Two hemocyte types were identified: hyalinocytes and granulocytes. Hyalinocytes are small young (immature), poorly spreading cells, which have a high nucleocytoplasmic ratio and are especially rich in free ribosomes. They do not appear to contain lysosome-like bodies and represent less than 10% of the circulating hemocytes. Granulocytes are larger hemocytes which readily spread on glass surface and which strongly react to the Gomori substrate, indicating the enzyme acid phosphatase usually found in lysosomes. Ultra-structurally, they contain a well-developed rough endoplasmic reticulum, dictyosomes and some some lysosome-like dense bodies. Granulocytes do not exhibit a characteristic granular aspect and the few granules observed in the cytoplasm should correspond to a lysosome system. They were named granulocytes instead of amoebocytes to use the same terminology adopted for Biomphalaria glabrata in order to make easier comparative studies. This is a preface study for more specific investigations on the functional activities of the blood cells of B. tenagophila and their interactions with the trematode parasite
The hemocytes of Panstrogyllus Megistus (Hemiptera: Reduviidae) Os hemĂłcitos de Panstrongylus megistus (Hemiptera: Reduviidae)
Five hemocyte types were identified in the hemolymph of Panstrongylus megistus by phase contrast and common light microscopy using some histochemical methods. These are: Prohemocytes, small cells presenting a great nucleus/cytoplasm ratio; Plasmatocytes, the most numerous hemocytes, are polymorphic cells mainly characterized by a large amount of lysosomes; Granulocytes, hemocytes very similar to plasmatocytes which contain cytoplasmic granules and are especially rich in polysaccharides; Oenocytoids, cells presenting a small nucleus and a thick cytoplasm; they show many small round vacuoles when observed in Giemsa smears and many cytoplasmic granules under phase microscopy; Adipohemocytes, very large hemocytes, presenting many fat droplet inclusions which could correspond to free fat bodies which entered the hemolymph. Only prohemocytes and plasmatocytes can be clearly classified; all the other hemocyte types have a more ambiguous classification.<br>Cinco tipos de hemĂłcitos foram identificados na hemolinfa de Panstrongylus megistus atravĂ©s da microscopia de constraste de fase e de luz, usando alguns testes histoquĂmicos: PrĂł-hemĂłcitos-cĂ©lulas pequenas que mostram uma grande relação nĂşcleocitoplasmática; PlasmotĂłcitos-cĂ©lulas polimporficas, que se caracterizam principalmente pela sua grande abundância em lisossomos - sĂŁo os hemĂłcitos mais numerosos; GranulĂłcitos-cĂ©lulas muito semelhantes aos plasmatĂłcitos que contĂŞm grânulos citoplasmáticos particularmente ricos em polissacarĂdeos; EnocitĂłides-hemĂłcitos que apresentam um nĂşcleo pequeno e cujo citoplasma basofĂlico revela-se muito denso e homogĂŞnio - mostram uma sĂ©rie de pequenos vacĂşolos esfĂ©ricos quando observados nos esfregaços corados pelo Giemsa, mas a microscopia de fase revela uma grande quantidade de pequenos grânulo ao invĂ©s de vacĂşolos; Adipo-hemĂłcitos-hemĂłcitos muito grandes que contĂŞm uma grande quantidade de inclusões lĂpicas - poderiam corresponder a cĂ©lulas do corpo gorduroso que, destacando-se, penetram na hemolinfa. Somente os p´r-hemĂłcitos e os plasmatĂłcitos podem ser classificados com precisĂŁo; os outros tipos podem gerar ambiguidade de classificação