The Changes in Mitochondrial Morphology and Physiology Accompanying Apoptosis in Galleria mellonella (Lepidoptera) Immunocompetent Cells during Conidiobolus coronatus (Entomophthorales) Infection

The multifunctional role of IFN-γ in Galleria mellonella (Lepidoptera) immunocompetent cells

Cytokines are highly conserved between mammals and insects. The present study examines the multiple effects of interferon-gamma (IFN-γ) application on the immunological defence mechanisms of Galleria mellonella larvae, invertebrates which are gaining popularity as a replacement for mammalian research models in immunological studies. G. mellonella hemolymph is known to contain an IFN-γ homolog that shares 33 % similarity with its mammalian analogue, and its level in insect hemocytes increases during exposition to entomopathogenic fungus Conidiobolus coronatus. The present research examines the impact of IFN-γ on larval development, the effectiveness of fungal infection, and the morphology and physiology of wax moth immunocompetent cells. Treatment with IFN-γ enhanced wound healing, chemotaxis activity and hemocyte impedance, while reducing hemocyte phagocytosis and oxidative stress in cultured immunocompetent cells; it also appears to increase the levels of Jak-2- and NF-κB-like molecules in hemocytes. Our findings suggest that IFN-γ demonstrated considerable similarity between mammals and humans, thus further demonstrating the evolutionary conservatism of cytokines.

Octanoic acid kills Lucilia sericata (Diptera: Calliphoridae) by affecting two major defence systems: cuticular free fatty acids and immunocompetent cells

This work examines the insecticidal activity of octanoic acid (C8:0), a short-chain fatty acid detected in entomopathogenic fungus - Conidiobolus coronatus medium, against Lucilia sericata larvae and adults. The LD50 value was calculated as 3.04±0.26 µg/mg (3040 mg/kg) of insect body mass, which places the compound in category 5 of acute toxicity (slightly hazardous). The presented research also describes its probable mechanism, with a particular focus on changes in two main insect defense mechanisms: (1) the composition of the cuticle (GC-MS analysis) and (2) immunocompetent cells (microscopic analysis of cultured hemocytes). More precisely, octanoic acid application resulted in changes in cuticular free fatty acid (FFA) profiles in both adults and larvae; generally, treatment increased short-chain FFAs, and a decrease of middle- and long-chain FFAs. Both in vivo and in vitro applications of octanoic acid resulted in vacuolisation, disintegration, and destruction of nets formed by plasmatocytes. As the compound has also previously been found to be toxic against Galleria mellonella, it appears to have lethal potential against insects in both the Orders Diptera and Lepidoptera, indicating it may have strong entomopathogenic potential. It is worth noting that octanoic acid is approved as a food additive with well-documented insecticidal activity, and hence may be a valuable component in the design of new insecticides that are safe for both humans and the environment.

Mitochondrial Melatonin: Beneficial Effects in Protecting against Heart Failure

Cardiovascular disease is the cause of physical infirmity and thousands of deaths annually. Typically, during heart failure, cardiomyocyte mitochondria falter in terms of energy production and metabolic processing. Additionally, inflammation and the accumulation of non-contractile fibrous tissue contribute to cardiac malfunction. Melatonin, an endogenously produced molecule, experimentally reduces the initiation and progression of atherosclerotic lesions, which are often the basis of coronary artery disease. The current review critically analyzes published data related to the experimental use of melatonin to forestall coronary artery pathologies. Collectively, these studies document melatonin's anti-atherosclerotic actions in reducing LDL oxidation and triglyceride levels, lowering endothelial malfunction, limiting adhesion molecule formation, preventing macrophage polarization to the M1 pro-inflammatory phenotype, changing cellular metabolism, scavenging destructive reactive oxygen species, preventing the proliferation and invasion of arterial smooth muscle cells into the lesioned area, restricting the ingrowth of blood vessels from the vasa vasorum, and solidifying the plaque cap to reduce the chance of its rupture. Diabetic hyperglycemia, which aggravates atherosclerotic plaque formation, is also inhibited by melatonin supplementation in experimental animals. The potential value of non-toxic melatonin as a possible inhibitor of cardiac pathology in humans should be seriously considered by performing clinical trials using this multifunctional molecule.

The Entomopathogenic Fungus Conidiobolus coronatus Has Similar Effects on the Cuticular Free Fatty Acid Profile of Sensitive and Resistant Insects

The mechanisms underlying the recognition of a susceptible host by a fungus and the role of cuticular compounds (CCs) in this process remain unclear; however, accumulated data suggest that this is influenced to a great degree by cuticular lipids. Two insect species differing in their sensitivity to fungal infection, viz. the highly sensitive Galleria mellonella Linnaeus (Lepidoptera: Pyralidae) and the resistant Calliphora vicina Robineau-Desvoidy (Diptera: Calliphoridae), exhibited significant qualitative and quantitative changes in cuticular free fatty acid (FFA) profiles after exposure to Conidiobolus coronatus (Constantin) Batko (Entomopthorales). Despite being systematically distant, leading different lifestyles in different habitats, both insect species demonstrated similar changes in the same FFAs following exposure to the fungus (C12:0, C13:0, C14:0, C15:0, C16:1, C16:0, C18:1, C18:0), suggesting that these are involved in a contact-induced defense response. As it was not possible to distinguish the share of FFAs present in the conidia that were attached to the cuticle from the FFAs of the cuticle itself in the total number of extracted FFAs, further research is necessary.