Interactions of spodoptera littoralis haemocytes following injection with the entomopathogenic fungi: Beauveria Bassiana and Nomuraea Rileyi

This study compared the cellular interactions of Spodopteralittoralis haemocytes with two virulence-different entomopathogenic fungi: Beauveriabassiana and Nomuraearileyi. Using light and transmission microscopy, five types of haemocytes namely, prohaemocytes [PRs], plasmatocytes [PLs], granulocytes [GRs], spherule cells [SPs] and oenocytoids [OEs] were identified in the 6[th] instar larvae. PRs and PLs were found in the haemopoietic tissue.Intra-haemocoelic injection of blastospores induced ultrastructural alterations in the cytoplasm and nucleiof circulating haemocytes of treated larvae. Different responses were observed in the populations of haemocyte types following injection with the tested fungi. The most important changes were the decrease of the numbers of GRs aiccompanied with increase inSPs at 12-48h following injection with B. bassiana, whereas,a decrease of PLs with a commitment increase inSPs and OEs were observed at most time intervals after injection with N. rileyi. Both fungi provoked a decrease of the total number of haemocytes at 48h followed by an increase at 72h post-injection. In vivo assay showed that the GRs and PLs actively phagocytised fungal blastospores. There was a time-dependent decrease and increase in the phagocytosis activity after injection of B. bassiana and N. Rileyi, respectively .In B. bassiana-injected insects, the numbers nodules increased significantly at 6-48h in comparison with the controls post-injection. In N. rileyi-injected insects, nodules increased significantly only at 72h post-injection.No cellular encapsulation was observed in any of the examined insects

A contribution to the pathobiology of Biomphalaria glabrata hemocytes

This study attempts to investigate the relationship between the hemocytes in the two compartments: circulating peripheral lymph and the connective tissues. The hemocytes are compared with the vertebrate macrophages and constitute the principal line of defense against external aggression. The hemocytes were counted in circulating hemolymph and their phagocytic capability was evaluated in Schistosoma mansoni-infected Biomphalaria glabrata and the results were compared with those obtained from normal intact control snails. Although the number of circulating hemocytes revealed a mild increase in snails at the 6th week of infection, the overall findings were similar and pointed out that the cells in the two compartments are not functionally connected. However, the hemocytes found within the connective tissues of infected snails showed definite ultrastructural differences in the number and disposition of cytoplasmic prolongations and organelles in comparison with the hemocytes from non-infected snails. Histochemically, the staining for acid phosphatase activity served as a marker to hemocytes, sometimes being found in extracellular material at the foci of parasite-hemocyte interactions.

Defense reactions of Dermatobia hominis (Diptera: Cuterebridae) larval hemocytes

The defense reactions against biological (Histoplasma capsulatum and Escherichia coli) and non-biological materials (China ink and nylon thread) were tested in vivo in third instar larvae of Dermatobia hominis. The cellular defense performed by larval hemocytes was observed under electron microscopy. China ink particles were phagocytosed by granular cells 5 h after injection. E. coli cells were internalized by granular cells as early as 5 min after injection and totally cleared 180 min post-injection, when many hemocytes appeared disintegrated and others in process of recovering. H. capsulatum yeasts provoked, 24 h after being injected, the beginning of nodule formation. Nylon thread was encapsulated 24 h after the introduction into the hemocoel. Our results suggest that granular cells were the phagocytic cells and also the responsible for the triggering of nodule and capsule formation. In the presence of yeasts cells and nylon thread, they released their granules that chemotactically attracted the plasmatocytes that on their turn, flattened to surround and isolate the foreign material.

Aspects of classification of Hemiptera hemocytes from six triatomine species

The objective of this work was to characterize, and compare different morphological types of hemocytes of Rhodnius prolixus, Rhodnius, Rhodnius neglectus, Triatoma infestans, Panstrongylus megistus, and Dipetalogaster maximus. This information provides the basis for studying the cellular immune systems of these insects. Seven morphological hemocyte types wereidentified by phase-contrast microscopy: prohemocytes, plasmatocytes, granular cells, cytocytes, oenocytoids, adipohemocytes and giant cells. All seven types of hemocytes are not present in every species. For example, adipohemocytes and oenocytoids were not observed in P. megistus and P. infestans, and giant cells were rarely found in any of the species studied. The hemocytes of rhodnius and Dipetalogaster are more similar to each other than those from Triatoma and Panstrongylus which in turn closely resemble each other. Emphasis is placed on methodological problems arising in this work wicah are discussed in detail

Ultrastructural studies of the hemocytes of Panstrongylus megistus (Hemiptera: Reduvidae)

Estudos ao microscópio eletrônico de transmissäo revelaram a presença de seis tipos de hemócitos na hemolinfa de Panstrongylus megistus. Estes resultados confirmam parcialmente os obtidos anteriormente através da microscopia de luz. Pró-hemócitos: células pequenas e arredondadas, cuja delgada faixa citoplasmática é especialmente rica em ribossomos livres e pobre em sistemas membranosos. Plasmatócitos: células polimórficas, cujo citoplasma caracteriza-se por um retículo endoplasmático rugoso (RER) bem desenvolvido e principalmente pela sua abundância em lisossomos. Säo células tipicamente fagocitárias. Algumas vezes, seu citoplasma mostra-se extremamente vacuolizado. Granulócitos: hemócitos granulares, cujos grânulos mostram diferentes graus de eletrondensidade e podem ou näo apresentar estruturaçäo interna. Coagulócitos: hemócitos ovalados ou fusiformes que se caracterizam pela presença de acentuadas cisternas perinucleares. O citoplasma é geralmente eletrondenso, pobre em organelas membranosas e contêm grânulos frágeis. Enocitóides: hemócitos grandes e muito estáveis em sua morfologia. Seu citoplasma é homogêneo, rico em ribossomos livres e pobre em sistemas membranosos. Adipo-hemócitos: células grandes que apresentam inclusöes lipídicas características. Seu citoplasma é também rico em glicogênio RER e mitocôndrias grandes. As contagens totais (THC) e diferenciais (DHC) de hemócitos foram também calculadas. A THC cresce de 2.900 hemócitos/mm3 de hemolinfa em ninfas de 4§ estágio para 4.350 em ninfas de 5§ estágio. Há, no entanto, um decréscimo significativo nos adultos, onde a THC passa para 1.950 hemócitos/mm3 de hemolinfa. Plasmatócitos e coagulócitos säo os hemócitos hemolinfa. Plasmatócitos e coagulócitos säo os hemócitos predominantes em P. megistus