Involvement of PLA2, COX and LOX in Rhinella arenarum oocyte maturation

Male-derived phospholipase A2 enhances WD46 expression and increases fertility in Ophraella communa

Successful bisexual reproduction requires interactions between males and females. Male-derived seminal fluid proteins (SFPs) transferred to females during mating profoundly affect females from pre- to post-mating, and the subsequent shift in female physiology enhances their fertility. SFPs have important evolutionary implications for the fitness of many insects. However, little is known about how females respond to male SFPs. In this study, we identified a male-derived SFP-phospholipase A2 (PLA2) in Ophraella communa. PLA2 is a vital enzyme in eicosanoid biosynthesis; however, it has not been identified as an insect SFP. We found that OcPLA2 is specifically expressed in males, especially in the male accessory glands (MAGs); it is transferred to the female during mating and functions as an SFP to enhance fertility. The expression of a female-derived gene encoding the WD repeat-containing protein 46 (WD46) was upregulated when OcPLA2 entered the female reproductive tract, and this contributed to female egg production by increasing triacylglycerol lipase (TGL) gene expression and the triglyceride (TG) content. This is the first study to identify PLA2 as an SFP in insects. Our findings also shed light on the regulatory role of OcPLA2 in beetle reproduction; the expression of OcPLA2 is initially correlated with female WD46 expression and later with the decline in TGL gene expression and the TG content. This represents a unique mechanism of reproductive regulation by an SFP.

Quinacrine pretreatment reduces microwave-induced neuronal damage by stabilizing the cell membrane

Quinacrine, widely used to treat parasitic diseases, binds to cell membranes. We previously found that quinacrine pretreatment reduced microwave radiation damage in rat hippocampal neurons, but the molecular mechanism remains poorly understood. Considering the thermal effects of microwave radiation and the protective effects of quinacrine on heat damage in cells, we hypothesized that quinacrine would prevent microwave radiation damage to cells in a mechanism associated with cell membrane stability. To test this, we used retinoic acid to induce PC12 cells to differentiate into neuron-like cells. We then pretreated the neurons with quinacrine (20 and 40 mM) and irradiated them with 50 mW/cm² microwaves for 3 or 6 hours. Flow cytometry, atomic force microscopy and western blot assays revealed that irradiated cells pretreated with quinacrine showed markedly less apoptosis, necrosis, and membrane damage, and greater expression of heat shock protein 70, than cells exposed to microwave irradiation alone. These results suggest that quinacrine stabilizes the neuronal membrane structure by upregulating the expression of heat shock protein 70, thus reducing neuronal injury caused by microwave radiation.

Evolutionary aspects of lipoxygenases and genetic diversity of human leukotriene signaling

Leukotrienes are pro-inflammatory lipid mediators, which are biosynthesized via the lipoxygenase pathway of the arachidonic acid cascade. Lipoxygenases form a family of lipid peroxidizing enzymes and human lipoxygenase isoforms have been implicated in the pathogenesis of inflammatory, hyperproliferative (cancer) and neurodegenerative diseases. Lipoxygenases are not restricted to humans but also occur in a large number of pro- and eucaryotic organisms. Lipoxygenase-like sequences have been identified in the three domains of life (bacteria, archaea, eucarya) but because of lacking functional data the occurrence of catalytically active lipoxygenases in archaea still remains an open question. Although the physiological and/or pathophysiological functions of various lipoxygenase isoforms have been studied throughout the last three decades there is no unifying concept for the biological importance of these enzymes. In this review we are summarizing the current knowledge on the distribution of lipoxygenases in living single and multicellular organisms with particular emphasis to higher vertebrates and will also focus on the genetic diversity of enzymes and receptors involved in human leukotriene signaling.