Insect hemolymph clotting

Abstract

The clot's appearance in different large-bodied insects has been described, but until recently, little was known about any insect clot's molecular makeup, and few experiments could directly test its function. Techniques have been developed in Drosophila (fruit fly) larvae to identify clotting factors that can then be tested for effects on hemostasis, healing, and immunity. This has revealed unanticipated complexity in the hemostatic mechanisms in these larvae. While the clot's molecular structure is not yet fully understood, progress is being made, and the loss of clotting factors has been shown to cause subtle immune defects. The few similarities between coagulation in different insect species and life stages, and the current state of knowledge about coagulation in insects are discussed.

A mutualistic symbiosis between a parasitic mite and a pathogenic virus undermines honey bee immunity and health

“…Moreover, although the processes of clotting and of nodule and capsule formation differ in their final appearance, they share some molecular steps, and both involve melanin biosynthesis (24)(25)(26). Among the immune genes involved in these reactions is a sequence of key importance codes for a protein generating amyloid fibers that mediate encapsulation and strictly localized melanization of nonself material in Lepidoptera (27,28).…”

The peripheral nervous system supports blood cell homing and survival in theDrosophilalarva

“…Drosophila blood cells, or hemocytes, mediate innate immunity, removal of apoptotic cells, wound healing and secretion of extracellular matrix Lemaitre and Hoffmann, 2007;Wood and Jacinto, 2007;Brock et al, 2008;Dushay, 2009). Many molecular and cellular aspects of hemocyte development and responses are well conserved between Drosophila and vertebrates Hartenstein, 2006;Lemaitre and Hoffmann, 2007;Martinez-Agosto et al, 2007).…”

The Primary Role of Fibrinogen-Related Proteins in Invertebrates Is Defense, Not Coagulation

“…In these organisms, pathogen-associated molecules stimulate the rapid production of a gel formed by the cleavage of coagulogen into coagulin, which then interacts with proxins to form a matrix that immobilizes the pathogen in a network of hemocytes and coagulin polymers [9] . Although the cascade that leads to gel formation differs slightly between the horseshoe crab and other arthropods, some molecules such as transglutaminase [10] , which is dependant on calcium for protein cross-linking that occurs during coagulation [11] are conserved. Other molecules, such as lipophorin and lipophorin-like lipoproteins have also been identified as clotting factors common to insect and non-insect arthropods respectively [11] .…”

“…Although the cascade that leads to gel formation differs slightly between the horseshoe crab and other arthropods, some molecules such as transglutaminase [10] , which is dependant on calcium for protein cross-linking that occurs during coagulation [11] are conserved. Other molecules, such as lipophorin and lipophorin-like lipoproteins have also been identified as clotting factors common to insect and non-insect arthropods respectively [11] . For example, lipophorin was identified as one of the molecules prominently found in hemolymph clots of the American cockroach Periplaneta americana [11] (the specific mechanisms underlying arthropod coagulation are reviewed elsewhere in this issue and in [11] ).…”