Stress-related hormones affect carbohydrate metabolism in Drosophila females.

A highly conservative insulin signaling pathway, stable work of which is indicated by carbohydrates metabolism, is also known to play an important role in the control of stress resistance. Here we demonstrate that exposure to heat stress leads to a rise in the levels of trehalose and glucose in females of Drosophila melanogaster, but does not affect the expression level of the trehalase (Treh) gene. We have shown that the rise in juvenile hormone (JH) and dopamine decreases levels of both carbohydrates under the normal conditions but brings them to values close to normal following the stress exposure. The data obtained suggest that (a) dopamine and JH involved in the neuroendocrine stress reaction in D. melanogaster also take part in the regulation of carbohydrates metabolism, tending to normalize it after stress; (b) the regulation of trehalose content under stress does not occur at the level of transcription of the degrading enzyme.

ABC transporters in the liver fluke Opisthorchis felineus.

ATP-binding cassette transporters (ABC transporters) are essential components of normal cellular physiological machinery in all eukaryotic and prokaryotic species, including parasites. Some ABC transporters, e.g., P-glycoproteins, are involved in the efflux of toxins and xenobiotics from the cell. At present, nothing is known about ABC transporter genes in epidemiologically important liver flukes from the Opisthorchiidae family, including European liver fluke Opisthorchis felineus. Opisthorchiasis caused by O. felineus is a serious public health problem on the territory of Russia and other Eastern European countries. ABC drug transporters are attractive objects of research on molecular markers of resistance and on ways to potentiate sensitivity to anthelmintics through suppression of the transporters themselves with specific inhibitors. Here we aimed at the identification of ABC transporters in the O. felineus transcriptome and identification of P-glycoproteins. In addition, our aim was to assess ABC transcript abundance in the RNA-seq data, to study the mRNA expression of P-glycoprotein genes by Droplet Digital PCR throughout the life cycle of O. felineus, and to test the gene induction in response to xenobiotics or anthelminthic agents. We found 23 nucleotide sequences encoding ABC transporters belonging to different subfamilies, including four sequences of P-glycoproteins. According to the transcript abundance in the RNA-seq data, one of P-glycoproteins (P4) has the highest expression among all ABC genes in the adult worm. P-glycoproteins showed substantially differential mRNA expression throughout the fluke life cycle, with high expression in the adult worms. Putative activity of P-glycoproteins as xenobiotic efflux pumps was found to be linked to the excretory system of O. felineus and to be inhibited by verapamil or tariquidar. Thus, ABC drug transporters in the liver fluke O. felineus are functionally active, indicating that ABC drug transporters are likely to be molecular targets for a combination therapy aimed at prevention of a xenobiotic removal from helminth tissues and at increasing the drug concentration in the tissues.

The first comprehensive study of praziquantel effects in vivo and in vitro on European liver fluke Opisthorchis felineus (Trematoda).

The European liver fluke Opisthorchis felineus (Rivolta, 1884) is an epidemiologically important parasite infecting mammals, including humans. Opisthorchis felineus is widespread in Russia, Kazakhstan and Eastern European countries. Praziquantel (PZQ) is the drug of choice for the treatment of opisthorchiasis, but the effects of this drug on O. felineus are poorly studied. The aims of this work were (i) to perform a study of PZQ effects in vitro, (ii) to identify morphological markers of PZQ action on O. felineus, (iii) to analyse damage to the worm surface and (iv) to assess the efficacy of PZQ in vivo in a hamster model. Light microscopy, optical sectioning and fluorescence microscopy were used to study morphological changes. In vivo, PZQ at a dose of 400mg/kg reduced the rate of infection in experimental acute and chronic opisthorchiasis in hamsters by 70% and 79%, respectively. In vitro, the drug caused destruction and vacuolisation of the tegument of O. felineus, contractions of the worm musculature, paralysis, and irreversible changes in morphology (IC50=0.14µg/mL). Differences in susceptibility to the drug between adult and newly excysted metacercariae were also observed. Qualitative effects of PZQ in vivo and in vitro were similar to the drug's effects on other trematodes, including epidemiologically important liver flukes. Nevertheless, high heterogeneity of O. felineus specimens in terms of susceptibility to the drug was observed. In addition, we describe for the first time the high rate of recovery of O. felineus following the destructive action of PZQ.