Effect of Heat Stress on Expression of DILP2 and DILP3 Insulin-Like Peptide Genes in <Emphasis Type="Italic">Drosophila melanogaster</Emphasis> Adults

In a number of works, it was demonstrated that insulin/insulin-like growth factor signaling pathway in the Drosophila melanogaster can be involved in the control of the organism reaction to stress. However, it remains unclear which of eight insulin-like peptides (ligands of insulin/insulin-like growth factor signaling pathway) known in the D. melanogaster are involved in the response to different types of stress. We conducted immunohistochemical analysis of the expression of two insulin-like peptide genes (DILP2 and DILP3) in insulin-producing cells of the brain in adult D. melanogaster females after heat stress. We for the first time found that the DILP3 is one of the components of the response to heat stress, while the DILP2 is apparently not involved in the organism response to heat stress.     

Divergence across diet,time and populations rules out parallel evolution in the gut microbiomes of Trinidadian guppies

Diverse microbial consortia profoundly influence animal biology, necessitating an understanding of microbiome variation in studies of animal adaptation. Yet, little is known about such variability among fish, in spite of their importance in aquatic ecosystems. The Trinidadian guppy, Poecilia reticulata, is an intriguing candidate to test microbiome-related hypotheses on the drivers and consequences of animal adaptation, given the recent parallel origins of a similar ecotype across streams. To assess the relationships between the microbiome and host adaptation, we used 16S rRNA amplicon sequencing to characterize gut bacteria of two guppy ecotypes with known divergence in diet, life history, physiology and morphology collected from low-predation (LP) and high-predation (HP) habitats in four Trinidadian streams. Guts were populated by several recurring, core bacteria that are related to other fish associates and rarely detected in the environment. Although gut communities of lab-reared guppies differed from those in the wild, microbiome divergence between ecotypes from the same stream was evident under identical rearing conditions, suggesting host genetic divergence can affect associations with gut bacteria. In the field, gut communities varied over time, across streams and between ecotypes in a stream-specific manner. This latter finding, along with PICRUSt predictions of metagenome function, argues against strong parallelism of the gut microbiome in association with LP ecotype evolution. Thus, bacteria cannot be invoked in facilitating the heightened reliance of LP guppies on lower-quality diets. We argue that the macroevolutionary microbiome convergence seen across animals with similar diets may be a signature of secondary microbial shifts arising some time after host-driven adaptation.     

Use of high-density tiling microarrays to identify mutations globally and elucidate mechanisms of drug resistance in Plasmodium falciparum

Background

The identification of genetic changes that confer drug resistance or other phenotypic changes in pathogens can help optimize treatment strategies, support the development of new therapeutic agents, and provide information about the likely function of genes. Elucidating mechanisms of phenotypic drug resistance can also assist in identifying the mode of action of uncharacterized but potent antimalarial compounds identified in high-throughput chemical screening campaigns against Plasmodium falciparum.

Results

Here we show that tiling microarrays can detect de novo a large proportion of the genetic changes that differentiate one genome from another. We show that we detect most single nucleotide polymorphisms or small insertion deletion events and all known copy number variations that distinguish three laboratory isolates using readily accessible methods. We used the approach to discover mutations that occur during the selection process after transfection. We also elucidated a mechanism by which parasites acquire resistance to the antimalarial fosmidomycin, which targets the parasite isoprenoid synthesis pathway. Our microarray-based approach allowed us to attribute in vitro derived fosmidomycin resistance to a copy number variation event in the pfdxr gene, which enables the parasite to overcome fosmidomycin-mediated inhibition of isoprenoid biosynthesis.

Conclusions

We show that newly emerged single nucleotide polymorphisms can readily be detected and that malaria parasites can rapidly acquire gene amplifications in response to in vitro drug pressure. The ability to define comprehensively genetic variability in P. falciparum with a single overnight hybridization creates new opportunities to study parasite evolution and improve the treatment and control of malaria.     

Effects of light on cyanide‐resistant respiration and alternative oxidase function in Arabidopsis seedlings

Mitochondrial alternative oxidase (AOX), the unique respiratory terminal oxidase in plants, catalyzes the energy wasteful cyanide (CN)‐resistant respiration and plays a role in optimizing photosynthesis. Although it has been demonstrated that leaf AOX is upregulated after illumination, the in vivo mechanism of AOX upregulation by light and its physiological significance are still unknown. In this report, red light and blue light‐induced AOX (especially AOX1a) expressions were characterized. Phytochromes, phototropins and cryptochromes, all these photoreceptors mediate the light‐response of AOX1a gene. When aox1a mutant seedlings were grown under a high‐light (HL) condition, photobleaching was more evident in the mutant than the wild‐type plants. More reactive oxygen species (ROS) accumulation and inefficient dissipation of chloroplast reducing‐equivalents in aox1a mutant may account for its worse adaptation to HL stress. When etiolated seedlings were exposed to illumination for 4 h, chlorophyll accumulation was largely delayed in aox1a plants. We first suggest that more reduction of the photosynthetic electron transport chain and more accumulation of reducing‐equivalents in the mutant during de‐etiolation might be the main reasons.     

Mechanism of action of 2-aryloxy-2-thio-1,3,2-oxazaphosphorinane pesticides

The interaction of 2-aryloxy-2-thio-1,3,2-oxazaphosphorinanes exhibiting nematocide, insecticide/acaricide, and synergetic activities with monoamine oxidases and the interaction of the corresponding oxones, 2-aryloxy-2-oxo-1,3,2-oxazaphosphorinanes, with various cholinesterases, carboxyl esterases, and monoamine oxidases were studied. We showed that the thioderivatives inhibited monoamine oxidases, whereas oxones, which are, as a rule, weak cholinesterase inhibitors, strongly inhibited carboxyl esterases of the American cockroach and were transformed with monoamine oxidases into the strong cholinesterase inhibitors, acyclic phosphamidates. This allowed us to explain the low toxicity of the thioderivatives, the high toxicity of the oxoderivatives, and the great difference in toxicities of thio- and oxocompounds in the 1,3,2-oxazaphosphorinane series. The capacity of thioderivatives to inhibit monoamine oxidases and of oxoderivatives and their further activation products to inhibit carboxyl esterases, i.e., both enzymes responsible for pyrethroid detoxication in insects, explains the synergetic activity of the 1,3,2-oxazaphosphorinane series.     

The results and characteristics of the mupirocin (Bactroban) sanative treatment of intranasal Staphylococcus carriers in a large hospital]

The action of mupirocin as a nasal ointment (Bactroban) was studied on intranasal carriers of the hospital staphylococcal strains. The study included 37 medical workers from different and mainly problem units of the large general hospital. The tolerability of the ointment was good. After the Bactroban use no complications of the patients were recorded. The efficacy of Bacroban by the microbiological criteria in total amounted to 100 per cent. The eradication of methicillin resistant Staphylococcus aureus (MRSA) was observed in 93 per cent of the cases. A decrease of the level of the nasal passages dissemination by MRSA and methicillin resistant coagulase-negative staphylococci (MRSC) up to such low titers as 100 and 90 per cent was stated. No difference in the action of Bactroban on MRSA, MSSA and MRSC was noted. The bacteriological monitoring for 3 to 4 months revealed a change of the staphylococcal strains in 94 per cent of the cases, recolonization by the same staphylococcal strain in 19 per cent, recolonization by some another staphylococcal strains in 33 per cent and no recolonization in 14 per cent. A stable decrease of staphylococcal strains was possible with simultaneous Bactroban sanitation of all the bacterial carriers of the hospital or its isolated unit.     

Specific Interaction between Esterases and 2-Butylthio-2-thio-1,3,2-oxazaphosphorynane and Its Cyclic and Acyclic Analogs

We studied the anticholinesterase and anticarboxylesterase effects of 1,3,2-oxazaphosphorynane derivatives and certain cyclic and acyclic analogs on the two enzymes of homoiotherms (ACE from human erythrocytes and BuCE from horse serum) as well as the enzymes from insect tissues (the nerve cord of the American cockroach and the cephalic region of the domestic fly). The differences in in vitro antiesterase activity of cyclic thionic and the corresponding oxo derivatives of phosphorinane were revealed. The mechanism of the esterase active center phosphorylation not only splitting off the outgoing group (in vivo) but also opening the cycle by P–O bond (in vitro and possibly in vivo) is usually proposed to explain the higher inhibiting activity of the thionic compounds compared to the oxonic ones. The possible involvement of this phosphorylation mechanism in the synergistic activity of the studied compounds is discussed.