MALDI-TOF mass spectrometric identification of novel intercellular space peptides

We performed the matrix-assisted laser desorption/ionisation, time-of-flight mass spectrometry (MALDI-TOF) analysis of the peptides entering into the composition of not yet explored bioregulators derived from the extracellular matrix of the tissues of the various organs of the mammals, and also plants and fungi. The study included 15 different mammalian tissues, 13 species of plants, and 2 species of fungi. Exploring the bioregulators derived from eye tissues, we demonstrated that their composition includes peptide components with the same values of the molecular weight. The composition of the bioregulators derived from the tissues of various organs of mammals or different species of plants and fungi includes the peptides with different values of molecular weight. Obtained data indicate the growing evidence of the assumptions about the major function of the bioregulators of this group—their involvement in the regulation of tissue-organ homeostasis in the biological systems.     

Male hosts drive infracommunity structure of ectoparasites

We studied the co-occurrence of flea species in infracommunities of 16 rodents from four regions (South Africa, Tanzania, central Europe and western Siberia) using null models, and predicted that flea co-occurrences will be expressed more strongly in male than in female hosts. We examined patterns of co-occurrence (measured as the C score) in infracommunities of fleas that are parasitic on male and female hosts by comparing co-occurrence frequencies with those expected by chance. When a significant degree of nonrandomness in flea co-occurrences was detected, it indicated aggregative infracommunity structure. In Tanzanian rodents, no significant flea co-occurrences were detected in either male or female hosts. In a South African rodent, significant flea co-occurrences were not detected in males, but were found in females in some localities. In Palaearctic rodents, significant nonrandomness was detected either equally for males and females or more frequently in males than in females. Meta-analyses demonstrated that the frequency of the detection of nonrandomness in flea co-occurrences was significantly higher in male than in female hosts. The values of the standardized effect size (SES) for the C score differed significantly among host species, but not between host genders. When the Palaearctic hosts were analyzed separately, the effects of both host gender and species appeared to be significant, with the SES values for the C score in males being smaller than those in females. The strength of the gender difference in the manifestation of flea community structure increased with increasing gender difference in flea species richness, and with decreasing gender difference in flea prevalence for the Palaearctic hosts. We conclude that male hosts are the main drivers of flea infracommunity structure. However, the manifestation of gender bias in flea community structure varies among host species, and is likely determined by the pattern of species-specific spatial behavior.     

A novel method for preparation of HAMLET-like protein complexes

Some natural proteins induce tumor-selective apoptosis. α-Lactalbumin (α-LA), a milk calcium-binding protein, is converted into an antitumor form, called HAMLET/BAMLET, via partial unfolding and association with oleic acid (OA). Besides triggering multiple cell death mechanisms in tumor cells, HAMLET exhibits bactericidal activity against Streptococcus pneumoniae. The existing methods for preparation of active complexes of α-LA with OA employ neutral pH solutions, which greatly limit water solubility of OA. Therefore these methods suffer from low scalability and/or heterogeneity of the resulting α-LA - OA samples. In this study we present a novel method for preparation of α-LA - OA complexes using alkaline conditions that favor aqueous solubility of OA. The unbound OA is removed by precipitation under acidic conditions. The resulting sample, bLA-OA-45, bears 11 OA molecules and exhibits physico-chemical properties similar to those of BAMLET. Cytotoxic activities of bLA-OA-45 against human epidermoid larynx carcinoma and S. pneumoniae D39 cells are close to those of HAMLET. Treatment of S. pneumoniae with bLA-OA-45 or HAMLET induces depolarization and rupture of the membrane. The cells are markedly rescued from death upon pretreatment with an inhibitor of Ca²⁺ transport. Hence, the activation mechanisms of S. pneumoniae death are analogous for these two complexes. The developed express method for preparation of active α-LA - OA complex is high-throughput and suited for development of other protein complexes with low-molecular-weight amphiphilic substances possessing valuable cytotoxic properties.     

Study of a new group of bioregulators isolated from the greater plantain (Plantago major L.)

Proteins with physicochemical properties and biological activity similar to those of membrano-tropic homeostatic tissue-specific bioregulators that had been found earlier in various animal tissues were discovered in leaves of the common plantain (Plantago major L.). To study the specific activity of these plant proteins, we developed an experimental model for organotypic roller cultivation of newt (Pleurodeles waltl) skin tissue in vitro. We showed that the plant proteins of interest exert the wound-healing effect, which is characteristic of this plant, on the skin of vertebrates both in vitro and in vivo.     

Comparison of the Metabolic Syndrome Risk in Valproate-Treated Patients with Epilepsy and the General Population in Estonia

Background

No study has explored the risk of metabolic syndrome (MS) in patients with epilepsy treated with valproate (VPA) at the population level. The aim of this study was to compare the risk of MS in VPA-treated patients in Estonia to the risk in the general population.

Methods

This study involved 118 patients with epilepsy (63 men, 55 women) who received VPA monotherapy. MS was diagnosed according to the National Cholesterol Education Program Adult Treatment Panel III criteria. Data were compared with the results of a population-based study of the prevalence of MS in the same geographic region (N = 493; 213 men, 280 women).

Results

In the multiple logistic regression analysis, after adjustment for age and sex, the risk of MS in VPA-treated patients was not increased compared to the control subjects (odds ratio [OR] = 1.00; 95% confidence interval [CI], 0.59–1.68). VPA-treated patients had higher serum insulin concentrations than control subjects, independent of body mass index (BMI). A positive association was found between MS development and BMI (OR = 1.47; 95% CI, 1.25–1.73) in VPA-treated patients, but there were no associations with the VPA dosage or the homeostasis model assessment-estimated insulin resistance (HOMA-IR) index. In control subjects, BMI and HOMA-IR had similar predictive abilities for MS occurrence. In VPA-treated patients, the predictive ability of the HOMA-IR index was significantly lower than that of BMI, with areas under the receiver operating characteristic curves of 0.808 and 0.897 (P = 0.05), respectively.

Conclusions

The risk of MS is not increased among VPA-treated patients with epilepsy in Estonia compared to the general population. The HOMA-IR index likely has a lower predictive ability for MS in VPA-treated patients compared to its predictive ability in the general population.     

Functional Cross-talk between Distant Domains of Chikungunya Virus Non-structural Protein 2 Is Decisive for Its RNA-modulating Activity

Chikungunya virus (CHIKV) non-structural protein 2 (nsP2) is a multifunctional protein that is considered a master regulator of the viral life cycle and a main viral factor responsible for cytopathic effects and subversion of antiviral defense. The C-terminal part of nsP2 possesses protease activity, whereas the N-terminal part exhibits NTPase and RNA triphosphatase activity and is proposed to have helicase activity. Bioinformatics analysis classified CHIKV nsP2 into helicase superfamily 1. However, the biochemical significance of a coexistence of two functionally unrelated modules in this single protein remains unknown. In this study, recombinant nsP2 demonstrated unwinding of double-stranded RNA in a 5′–3′ directionally biased manner and RNA strand annealing activity. Comparative analysis of NTPase and helicase activities of wild type nsP2 with enzymatic capabilities of different truncated or N-terminally extended variants of nsP2 revealed that the C-terminal part of the protein is indispensable for helicase functionality and presumably provides a platform for RNA binding, whereas the N-terminal-most region is apparently involved in obtaining a conformation of nsP2 that allows for its maximal enzymatic activities. The establishment of the protocols for the production of biochemically active CHIKV nsP2 and optimization of the parameters for helicase and NTPase assays are expected to provide the starting point for a further search of possibilities for therapeutic interventions to suppress alphaviral infections.     

Sex-biased parasitism is not universal: evidence from rodent–flea associations from three biomes

The distribution of parasites among individual hosts is characterised by high variability that is believed to be a result of variations in host traits. To find general patterns of host traits affecting parasite abundance, we studied flea infestation of nine rodent species from three different biomes (temperate zone of central Europe, desert of Middle East and tropics of East Africa). We tested for independent and interactive effects of host sex and body mass on the number of fleas harboured by an individual host while accounting for spatial clustering of host and parasite sampling and temporal variation. We found no consistent patterns of the effect of host sex and body mass on flea abundance either among species within a biome or among biomes. We found evidence for sex-biased flea infestation in just five host species (Apodemus agrarius, Myodes glareolus, Microtus arvalis, Gerbillus andersoni, Mastomys natalensis). In six rodent species, we found an effect of body mass on flea abundance (all species mentioned above and Meriones crassus). This effect was positive in five species and negative in one species (Microtus arvalis). In M. glareolus, G. andersoni, M. natalensis, and M. arvalis, the relationship between body mass and flea abundance was mediated by host sex. This was manifested in steeper change in flea abundance with increasing body mass in male than female individuals (M. glareolus, G. andersoni, M. natalensis), whereas the opposite pattern was found in M. arvalis. Our findings suggest that sex and body mass are common determinants of parasite infestation in mammalian hosts, but neither of them follows universal rules. This implies that the effect of host individual characteristics on mechanisms responsible for flea acquisition may be manifested differently in different host species.