The ability of biocontrol agents to overcome the immune defense of pests is a crucial issue. This is the first study of lysozyme activity as an inducible humoral component of the defense of Schistocerca gregaria, which depends on the recognition of the elicitor molecules of pathogens and not on epidermal wounding or a spiking effect. The level of lysozyme activity in fat body, haemocytes and haemolymph plasma of naïve and immunologically challenged 5th instar S. gregaria was evaluated using the zone of inhibition test against Micrococcus lysodeikticus. Various Gram-positive and Gram-negative bacteria as well as peptidoglycans (PGN) and lipopolysacchrides (LPS) of bacterial cell walls induce and increase in the level of lysozyme activity. Escherichia coli induced an increase in the level of activity of lysozyme in the fat body, haemocytes and plasma, but not in mid gut epithelium, 6–12 h after an immunological challenge and then it decreased to the constitutive level after 72 h. This study revealed that in S. gregaria there is a constitutive and a bacteria-inducible level of lysozyme activity, which protects it against infection by both Gram-negative and Gram-positive bacteria., Amr A. Mohamed ... [et al.]., and Obsahuje seznam literatury
The aim of this study was to investigate whether haemocytes of Galleria mellonella (Lepidoptera: Pyralidae) larvae produce reactive oxygen species (ROS) like human blood phagocytes. The production of ROS was measured first using luminol-enhanced chemiluminescence of un-stimulated and stimulated (four activators with different modes of action) haemolymph or isolated haemocytes. However, spontaneous and activated production of ROS remained at the background level. In subsequent experiments an ultrasensitive fluorescence method using Amplex Red reagent to detect hydrogen peroxide (H2O2) was used. After optimization, Amplex Red was successfully used for determining H2O2 production by both un-stimulated and stimulated haemocytes. To determine the affect of pH and ions on the measurement, several diluent solutions were tested. This revealed that Ca2+ and Mg2+ ions are less important for the reaction in insect than mammalian cells. Among the activators tested, phorbol myristate acetate (PMA) and calcium ionophore (Ca-I) had the best stimulatory effect on insect samples, while opsonised zymosan particles (OZP) was the best activator for human phagocytes. In conclusion, the haemocytes of G. mellonella produce H2O2 as an important innate immunity factor, but under different conditions and in different amounts, which probably results in them being less effective in killing microbes than human phagocytes. and Ondřej Vašíček, Ivana Papežíková, Pavel Hyršl.
The microanatomy of several oribatid and one acaridid mite was studied to determine the role of free cells (haemocytes) in mites. Mites from the field as well as laboratory cultures were observed and analyzed histologically using Masson triple stain. The mites were offered various foods and kept in fluctuating moisture conditions. The presence of haemocytes was significantly correlated with the transport between internal organs of various substance. Three types of transport were recorded: (i) enzymes into the alimentary tract, including the incorporation of haemocytes into the gut walls. This process seemed to be correlated with the amount and type of food and frequently with the presence of internal extraintestinal bacteria associated with mesenchyma; (ii) metabolites, like guanine from mesenchyma into the alimentary tract followed by expulsion from the body via the gut. This process is correlated with food of high nitrogen content or dry conditions; (iii) resorption of nutrients from eggs during an induced quiescent state under unfavourable conditions by small haemocytes.