Translation of a small subset of Caenorhabditis elegans mRNAs is dependent on a specific eukaryotic translation initiation factor 4E isoform

The mRNA cap-binding protein eukaryotic translation initiation factor 4E (eIF4E) participates in protein synthesis initiation, translational repression of specific mRNAs, and nucleocytoplasmic shuttling. Multiple isoforms of eIF4E are expressed in a variety of organisms, but their specific roles are poorly understood. We investigated one Caenorhabditis elegans isoform, IFE-4, which has homologues in plants and mammals. IFE-4::green fluorescent protein (GFP) was expressed in pharyngeal and tail neurons, body wall muscle, spermatheca, and vulva. Knockout of ife-4 by RNA interference (RNAi) or a null mutation produced a pleiotropic phenotype that included egg-laying defects. Sedimentation analysis demonstrated that IFE-4, but not IFE-1, was present in 48S initiation complexes, indicating that it participates in protein synthesis initiation. mRNAs affected by ife-4 knockout were determined by DNA microarray analysis of polysomal distribution. Polysome shifts, in the absence of total mRNA changes, were observed for only 33 of the 18,967 C. elegans mRNAs tested, of which a disproportionate number were related to egg laying and were expressed in neurons and/or muscle. Translational regulation was confirmed by reduced levels of DAF-12, EGL-15, and KIN-29. The functions of these proteins can explain some phenotypes observed in ife-4 knockout mutants. These results indicate that translation of a limited subset of mRNAs is dependent on a specific isoform of eIF4E.     

Comparative analysis of the cardiac glycosides action on the growth of the cardiac tissue explants

The method of organotypical cell culture was used. The long-term cell culture of cardiac embryonic tissue of 10-12-days old chicken was investigated. The effects of ouabaine, strophantin K and digoxin on the growth of cardiac tissue explant were measured. The ouabain concentration which stimulates activity of Na+, K+-ATPase as the signal transducer, was determined. It was equal to 10(-10) M. Strophantin K and digoxin stimulate growth of cardiac tissue in concentration equal to 10(-16) M and 10(-18) M, resp. The data obtained show that application of cardiac glycosides led to control of cardiac tissue growth in dose-dependent manner. We hypothesize that alpha3 isoform of Na+, K+-ATPase is a signal transducer that controls the cardiac cell metabolism and growth.     

Mechanisms of gene therapy for tolerance: B7 signaling is required for peptide-IgG gene-transferred tolerance induction

LPS-activated B cells, transduced with IgG fusion proteins, are highly tolerogenic APCs. To analyze the mechanisms for this B cell-delivered gene therapy, we first followed the fate of CFSE-labeled B cell blasts. These cells primarily localized to the spleen, where a small population persisted for at least 1 mo after injection. By day 7 after injection, approximately 95% of the transduced cells had divided at least once, presumably an effect of the in vitro LPS activation into the cycle, because resting cells did not divide. B cells from gld donors were not tolerogenic, initially suggesting a role for Fas ligand (FasL) in tolerance. Because transduced normal B cells expressed only low levels of FasL and did not kill Fas-expressing Jurkat or A20 B lymphoma cells in vitro, these data suggest that gld B cells are not tolerogenic due to unique characteristics of these B cells rather than the lack of functional FasL expression. The transduced B cell blasts displayed significant up-regulation of both B7 costimulatory molecules, and B7.2 up-regulation was maintained through day 7 in vivo. When B cells from B7 knockout donors were transduced to express Ig fusion proteins, they were not tolerogenic in two different mouse strains and Ag models. Moreover, anti-B7 Ab blocked tolerance induction in this model, a result consistent with a role for B7 in tolerance induction. We propose that tolerance may be induced in this model by B7-driven negative regulatory signaling, but tolerance is maintained by a lack of signal 2, because expression of B7 is eventually lost in vivo.     

Single-strand DNA breaks in brain cells of different rat strains under normal condition and during exposure to stress

This study was aimed to characterize pattern of occurrence of spontaneous single-strand breaks in situ in glial and neuronal nuclei of the cortex, middle brain and hyppocapmi (CA3 field) of rats selected for a threshold of nervous system excitability, and to study the influence of stress of various modality on such breaks. The results obtained evidence that: 1) intact animals possess a subpopulation of glial and neuronal cells revealed following gap filling in situ in opposite to other types of terminally differentiated non-proliferating cells; 2) the size of such a subpopulation differs depending on the lines of examined rats, parts of brain, and the type of stress.     

Effect of Temperature on Rearing of the First Brood by the Founder Females of the Ant Lasius niger (Hymenoptera, Formicidae) : Latitude-Dependent Variability of the Response Norm

It has been established that duration of brood development and success of rearing of the first worker individuals by founder females of the ant Lasius niger from the northern population (St. Petersburg) depend on temperature conditions to a larger extent than of individuals from the southern areal (Borisovka Village, Belgorod Region) The development rate of individuals from the northern population is lower as compared with individuals from the southern population in the low temperature range (17–20°C), but is higher at elevated temperatures (22–27°C). This leads to a greater slope of the temperature regression line of the development rate on the temperature, to lower values of the sum of effective temperatures, and to a higher temperature threshold of development in the northern population. Lower temperatures have a stronger effect on development of larvae from the northern population by inducing diapause in the greater number of individuals as compared with larvae from the southern population. The L. niger founder females require, on average, higher temperatures than the females from the southern populations of this species for rearing the first worker ants during the same summer season (i.e., without winter diapause). Thus, ants of the southern populations, when rearing the first brood, use a strategy of faster development at higher temperatures, while low temperatures restrict to the greater extent the development of their brood as compared with ants from the southern populations. It is concluded that one of the ways of physiological adaptation of ants for inhabitance on the North is such change of the norm of response to temperature, at which development becomes more temperature-dependent, the physiological response to higher temperatures increasing at the cost of its decrease at lower temperatures.     

Listeria monocytogenes Multidrug Resistance Transporters and Cyclic Di-AMP,Which Contribute to Type I Interferon Induction,Play a Role in Cell Wall Stress

The intracellular bacterial pathogen Listeria monocytogenes activates a robust type I interferon response upon infection. This response is partially dependent on the multidrug resistance (MDR) transporter MdrM and relies on cyclic-di-AMP (c-di-AMP) secretion, yet the functions of MdrM and cyclic-di-AMP that lead to this response are unknown. Here we report that it is not MdrM alone but a cohort of MDR transporters that together contribute to type I interferon induction during infection. In a search for a physiological function of these transporters, we revealed that they play a role in cell wall stress responses. A mutant with deletion of four transporter genes (ΔmdrMTAC) was found to be sensitive to sublethal concentrations of vancomycin due to an inability to produce and shed peptidoglycan under this stress. Remarkably, c-di-AMP is involved in this phenotype, as overexpression of the c-di-AMP phosphodiesterase (PdeA) resulted in increased susceptibility of the ΔmdrMTAC mutant to vancomycin, whereas overexpression of the c-di-AMP diadenylate cyclase (DacA) reduced susceptibility to this drug. These observations suggest a physiological association between c-di-AMP and the MDR transporters and support the model that MDR transporters mediate c-di-AMP secretion to regulate peptidoglycan synthesis in response to cell wall stress.     

No Genetic Tradeoffs between Hygienic Behaviour and Individual Innate Immunity in the Honey Bee,Apis mellifera

Many animals have individual and social mechanisms for combating pathogens. Animals may exhibit short-term physiological tradeoffs between social and individual immunity because the latter is often energetically costly. Genetic tradeoffs between these two traits can also occur if mutations that enhance social immunity diminish individual immunity, or vice versa. Physiological tradeoffs between individual and social immunity have been previously documented in insects, but there has been no study of genetic tradeoffs involving these traits. There is strong evidence that some genes influence both innate immunity and behaviour in social insects – a prerequisite for genetic tradeoffs. Quantifying genetic tradeoffs is critical for understanding the evolution of immunity in social insects and for devising effective strategies for breeding disease-resistant pollinator populations. We conducted two experiments to test the hypothesis of a genetic tradeoff between social and individual immunity in the honey bee, Apis mellifera. First, we estimated the relative contribution of genetics to individual variation in innate immunity of honey bee workers, as only heritable traits can experience genetic tradeoffs. Second, we examined if worker bees with hygienic sisters have reduced individual innate immune response. We genotyped several hundred workers from two colonies and found that patriline genotype does not significantly influence the antimicrobial activity of a worker’s hemolymph. Further, we did not find a negative correlation between hygienic behaviour and the average antimicrobial activity of a worker’s hemolymph across 30 honey bee colonies. Taken together, our work indicates no genetic tradeoffs between hygienic behaviour and innate immunity in honey bees. Our work suggests that using artificial selection to increase hygienic behaviour of honey bee colonies is not expected to concurrently compromise individual innate immunity of worker bees.     

Silicon: The key element in early stages of biocalcification

Biocalcification is a widespread process of forming hard tissues like bone and teeth in vertebrates. It is also a topic connecting life sciences and earth sciences: calcified skeletons and shells deposited as sediments represent the earth's fossil record and are of paramount interest for biogeochemists trying to get an insight into the past of our planet. This study reports on the role of silicon in the early biocalcification steps, where silicon and calcium were detected on the surface of cyanobacteria (initial stage of lacustrine calcite precipitation) and in crustacean cuticles. By using innovative methodological approaches of correlative microscopy (AFM in combination with analytical TEM: EFTEM, EELS) the chemical form of silicon in biocalcifying matrices and organic-inorganic particles is determined. Previously, silicon was reported to be localized in active growth areas in the young bone of vertebrates. We have found evidence that biocalcification in evolutionarily distant organisms involves very similar initial phases with silicon as a key element at the organic-inorganic interface.