ARC-1, a sequence element complementary to an internal 18S rRNA segment, enhances translation efficiency in plants when present in the leader or intercistronic region of mRNAs

The sequences of different plant viral leaders with known translation enhancer ability show partial complementarity to the central region of 18S rRNA. Such complementarity might serve as a means to attract 40S ribosomal subunits and explain in part the translation-enhancing property of these sequences. To verify this notion, we designed β-glucuronidase (GUS) mRNAs differing only in the nature of 10 nt inserts in the center of their 41 base leaders. These were complementary to consecutive domains of plant 18S rRNA. Sucrose gradient analysis revealed that leaders with inserts complementary to regions 1105–1114 and 1115–1124 (‘ARC-1’) of plant 18S rRNA bound most efficiently to the 40S ribosomal subunit after dissociation from 80S ribosomes under conditions of high ionic strength, a treatment known to remove translation initiation factors. Using wheat germ cell-free extracts, we could demonstrate that mRNAs with these leaders were translated more than three times more efficiently than a control lacking such a complementarity. Three linked copies of the insert enhanced translation of reporter mRNA to levels comparable with those directed by the natural translation enhancing leaders of tobacco mosaic virus and potato virus Y RNAs. Moreover, inserting the same leaders as intercistronic sequences in dicistronic mRNAs substantially increased translation of the second cistron, thereby revealing internal ribosome entry site activity. Thus, for plant systems, the complementary interaction between mRNA leader and the central region of 18S rRNA allows cap-independent binding of mRNA to the 43S pre-initiation complex without assistance of translation initiation factors.     

Sensitivity of Mycoplasma hominis cultures isolated from clinical material to certain antibiotics]

Sensitivity to II antibiotics of 80 strains of M. hominis isolated from patients with various inflammatory processes of the urogenital tract was studied by the method of suppressing the metabolic activity. Inhibition of the arginine metabolism of mycoplasma was used as a test for determination of the growth suppression. All the strains tested were highly sensitive to tetracycline and lincomycin. Kanamycin and neomycin were less active against M. hominis. All the strains tested were resistant to erythromycin, oleandomycin, ristomycin, novobiocin and streptomycin. The inhibitory effect of tetracycline and lincomycin on M. hominis decreased by the 5th day.     

The Role of Oxidative Stress in the Longevity and Insecticide Resistance Phenotype of the Major Malaria Vectors Anopheles arabiensis and Anopheles funestus

Oxidative stress plays numerous biological roles, both functional and pathological. The role of oxidative stress in various epidemiologically relevant biological traits in Anopheles mosquitoes is not well established. In this study, the effects of oxidative stress on the longevity and insecticide resistance phenotype in the major malaria vector species An. arabiensis and An. funestus were examined. Responses to dietary copper sulphate and hydrogen peroxide were used as proxies for the oxidative stress phenotype by determining the effect of copper on longevity and hydrogen peroxide lethal dose. Glutathione peroxidase and catalase activities were determined colorimetrically. Oxidative burden was quantified as protein carbonyl content. Changes in insecticide resistance phenotype were monitored by WHO bioassay. Insecticide resistant individuals showed an increased capacity for coping with oxidative stress, mediated by increased glutathione peroxidase and catalase activity. This effect was observed in both species, as well as in laboratory strains and F₁ individuals derived from wild-caught An. funestus mothers. Phenotypic capacity for coping with oxidative stress was greatest in strains with elevated Cytochrome P450 activity. Synergism of oxidative stress defence enzymes by dietary supplementation with haematin, 3-Amino-1, 2, 4-triazole and Sodium diethyldithiocarbamate significantly increased pyrethroid-induced mortality in An. arabiensis and An. funestus. It is therefore concluded that defence against oxidative stress underlies the augmentation of the insecticide resistance phenotype associated with multiple blood-feeding. This is because multiple blood-feeding ultimately leads to a reduction of oxidative stress in insecticide resistant females, and also reduces the oxidative burden induced by DDT and pyrethroids, by inducing increased glutathione peroxidase activity. This study highlights the importance of oxidative stress in the longevity and insecticide resistance phenotype in malaria vectors.     

Adaptive changes in the myocardium of patients with ischemic heart disease

Changes in the human heart muscle resulting from chronic coronary insufficiency have been analyzed using biopsies taken during surgery from nine patients with ischemic heart disease (IHD) and six patients with the WPW syndrome (without IHD). Histochemical analysis have shown that the atrial myocardium in IHD patients is characterized by an increased density of the microvascular network, increased phosphorylase activity, and decreased succinate dehydrogenase activity. Virtually the same changes have proved to occur in the myocardium of rats adapted to hypoxia by means of repeated exposure in a low-pressure chamber. According to the results of two-dimensional electrophoresis and immunoblotting, acid (but not alkaline) isoforms of inducible HSP70 proteins appear in the myocardium of IHD patients. It is concluded that the myocardium of IHD patients undergoes adaptive changes at the tissue level in response to repeated exposure to ischemia in the course of development of this disease. It is proposed that activation of the synthesis of alkaline HSP70 isoforms in the myocardium of cardiological patients may provide the possibility of improving its resistance to the impact of ischemia and reperfusion (this possibility is not realized under conditions of IHD).     

Microbiota of the Kinderlinskaya cave (South Urals,Russia)

The mesophilic and psychrotolerant microbiota of the air, soil, water, and bottom sediments of the Kinderlinskaya cave (South Urals, Russia) and the factors affecting the structure of microbial communities were investigated. The pattern of microbial distribution in soils was shown to depend on both the configuration of the cave and the level of recreational load. The lowest numbers of bacteria and micromycetes were found in the poorly visited, difficult-to-access sites. Coliform bacteria were revealed in all soil and sediment samples and in some water samples. Micromycetes belonged to 19 genera, with Geomyces pannorum as the dominant species. Air movement was shown to be the main factor affecting the density of the aerial microbiota.     

Variability of a set of hemodynamic parameters in young female and male athletes and nonathletes

Regulation of hemodynamics in young subjects was studied via estimating the variability of circulatory parameters. Slow-wave hemodynamic parameters and heart rate variability were shown to be individual-specific.     

Involvement of Boiling Stable Antioxidant Enzymes in Adaptation of Invasive Alien Plant Lantana to Abiotic Stress under Natural Conditions

Russian Journal of Plant Physiology - Lantana camara L. is noxious weed affecting ecosystem and biodiversity worldwide. However, the biochemical basis of invasiveness and adaptation to abiotic...