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Yu Y.,Chongqing University of Technology | Cao Y.,Chongqing University | Cao Y.,Chongqing Engineering Research Center for Fungal Insecticides | Cao Y.,Key Laboratory of Functional Gene and Regulation Technology Under Chongqing Municipal Education Commission | And 4 more authors.
Journal of Invertebrate Pathology | Year: 2016

Hemocytes are the first line of defense in the invertebrate immune system. Understanding their roles in cellular immunity is important for developing more efficient mycoinsecticides. However, the exact classification of hemocytes has been inconsistent and the various types of phagocytes in Locusta migratoria are poorly defined. Herein, the Wright–Giemsa staining method and microscopy were employed to characterize the hemocytes of L. migratoria following infection by Metarhizium acridum. Hemocytes were classified into four types, including granulocytes, plasmatocytes, prohemocytes, and oenocytoids, based on size, morphology, and dye-staining properties. Each type of hemocyte was classified into several subtypes according to different ultrastructural features. At least four subtypes of granulocytes or plasmatocytes, including small-nucleus plasmatocytes, basophil vacuolated plasmatocytes, homogeneous plasmatocytes, and eosinophilic granulocytes, carried out phagocytosis. The percentage of total phagocytes increased two days after infection by M. acridum, then gradually declined during the next two days, and then increased sharply again at the fifth day. Our data suggested that plasmatocytes and granulocytes may be the major phagocytes that protect against invasion by a fungal pathogen in L. migratoria. Total hemocytes in locusts significantly increased in the initial days after infection and decreased in the late period of infection compared to controls. In the hemocoel, hyphal bodies were recognized, enwrapped, and digested by the phagocytes. Then, the broken hyphal pieces were packaged as vesicles to be secreted from the cell. Moreover, locusts might have a sensitive and efficient cellular immune system that can regulate phagocyte differentiation and proliferation before fungi colonize the host hemolymph. © 2016 Elsevier Inc.


Cao Y.,Chongqing University | Cao Y.,Chongqing Engineering Research Center for Fungal Insecticides | Cao Y.,Key Laboratory of Functional Gene and Regulation Technology Under Chongqing Municipal Education Commission | Du M.,Chongqing University | And 8 more authors.
Applied Microbiology and Biotechnology | Year: 2014

Calcineurin is highly conserved and regulates growth, conidiation, stress response, and pathogenicity in fungi. However, the functions of calcineurin and its regulatory network in entomopathogenic fungi are not clear. In this study, calcineurin was functionally analyzed by deleting the catalytic subunit MaCnA from the entomopathogenic fungus Metarhizium acridum. The ΔMaCnA mutant had aberrant, compact colonies and blunt, shortened hyphae. Conidia production was reduced, and phialide differentiation into conidiogenous cells was impaired in the ΔMaCnA mutant. ΔMaCnA had thinner cell walls and greatly reduced chitin and β-1,3-glucan content compared to the wild type. The ΔMaCnA mutant was more tolerant to cell wall-perturbing agents and elevated or decreased exogenous calcium but less tolerant to heat, ultraviolet irradiation, and caspofungin than the wild type. Bioassays showed that ΔMaCnA had decreased virulence. Digital gene expression profiling revealed that genes involved in cell wall construction, conidiation, stress tolerance, cell cycle control, and calcium transport were downregulated in ΔMaCnA. Calcineurin affected some components of small G proteins, mitogen-activated protein kinase, and cyclic AMP (cAMP)-protein kinase A signaling pathways in M. acridum. In conclusion, our results gave a global survey of the genes downstream of calcineurin in M. acridum, providing molecular explanations for the changes in phenotypes observed when calcineurin was deleted. © 2014, Springer-Verlag Berlin Heidelberg.

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