Mechanisms of peroxisome proliferator-induced DNA hypomethylation in rat liver

Genomic hypomethylation is a consistent finding in both human and animal tumors and mounting experimental evidence suggests a key role for epigenetic events in tumorigenesis. Furthermore, it has been suggested that early changes in DNA methylation and histone modifications may serve as sensitive predictive markers in animal testing for carcinogenic potency of environmental agents. Alterations in metabolism of methyl donors, disturbances in activity and/or expression of DNA methyltransferases, and presence of DNA single-strand breaks could contribute to the loss of cytosine methylation during carcinogenesis; however, the precise mechanisms of genomic hypomethylation induced by chemical carcinogens remain largely unknown. This study examined the mechanism of DNA hypomethylation during hepatocarcinogenesis induced by peroxisome proliferators WY-14,643 (4-chloro-6-(2,3-xylidino)-pyrimidynylthioacetic acid) and DEHP (di-(2-ethylhexyl)phthalate), agents acting through non-genotoxic mode of action. In the liver of male Fisher 344 rats exposed to WY-14,643 (0.1% (w/w), 5 months), the level of genomic hypomethylation increased by approximately 2-fold, as compared to age-matched controls, while in the DEHP group (1.2% (w/w), 5 months) DNA methylation did not change. Global DNA hypomethylation in livers from WY-14,643 group was accompanied by the accumulation of DNA single-strand breaks, increased cell proliferation, and diminished expression of DNA methyltransferase 1, while the metabolism of methyl donors was not affected. In contrast, none of these parameters changed significantly in rats fed DEHP. Since WY-14,643 is much more potent carcinogen than DEHP, we conclude that the extent of loss of DNA methylation may be related to the carcinogenic potential of the chemical agent, and that accumulation of DNA single-strand breaks coupled to the increase in cell proliferation and altered DNA methyltransferase expression may explain genomic hypomethylation during peroxisome proliferator-induced carcinogenesis.     

Starter culture of <Emphasis Type="Italic">Pseudomonas veronii</Emphasis> strain B for aerobic granulation

Aggregation of bacterial cells is used in formation of microbial granules. Aerobically grown microbial granules can be used as the bio-agents in the treatment of wastewater. However, there are problems with start up of microbial granulation and biosafety of this process. Aim of this research was selection and testing of safe microbial strain with high cell aggregation ability to shorten period of microbial granules formation. Five bacterial strains with cell aggregation index higher than 50% have been isolated from the granules. Strain of Pseudomonas veronii species was considered as most probably safe starter culture for granulation because other strains belonged to the species known as human pathogens. The microbial granules were formed after 3 days of cultivation in case when P. veronii strain B was applied to start-up aerobic granulation process using model wastewater. The granules were produced from activated sludge after 9 days of cultivation. Microbial aggregates produced from starter culture of P. veronii strain B were more compact (sludge volume index was 70 ml/g) than those produced from activated sludge (sludge volume index was 106 ml/g). It is a first proof that application of selected safe starter pure culture with high cell aggregation ability can accelerate and enhance formation of microbial granules.     

Functional divergence of the circadian clock proteins in prokaryotes

Cyanobacteria are only prokaryotes known so far to have a circadian system. It may be based either on two (kaiB and kaiC) or three (kaiA, kaiB and kaiC) circadian genes. The homologs of two circadian proteins, KaiB and KaiC, form four major subfamilies (K1–K4) and also occur in some other prokaryotes. Using the likelihood-ratio tests, we studied a rate shift at the functional divergence of the proteins from the different subfamilies. It appears that only two of the subfamilies (K1 and K2) perform circadian functions. We identified in total 92 sites that have significantly different rates of evolution between the clades K1/K2 and K3/K4; 67 sites (15 in KaiB and 52 in KaiC) been evolving significantly slower in K1/K2 than the overall average for the entire sequence. Many critical sites are located in the identified functionally important motifs and regions, e.g. one of the Walker’s motif As, DXXG motif, and two KaiA-binding domains of KaiC. There are also 36 sites (~5%) with rate shift between K1 and K2. The rate shift at these sites may be related to the interaction with KaiA. Rate shift analyses have identified residues whose manipulation in the Kai proteins may lead to better understanding of their functions in the two different types of the cyanobacterial circadian system.     

Development of neuron-capillary interrelationships in the nuclei of the anterior portion of the human hypothalamus during ontogenesis

Three periods in the formation of the spatial arrangement of the neuronal nuclei have been stated: 1) from the prenatal period, infancy including--pronounced decrease in the density of the neuronal cells arrangement; 2) from the childhood up to adolescence--relative stabilization in the hypothalamic cellular composition; 3) mature and old age--secondary decrease in the dencity of the neuronal cells arrangement. Certain peculiarities in the nuclear capillary composition and in their neuronal-capillary relationships have been revealed: during the prenatal ontogenesis, the dencity of the neuronal cells arrangement decreases and their size increases that is followed by decrease in their capillary loops. In postnatal ontogenesis no proportional relationship between the dencity of neuronal cells arrangement and that of capillary network in the nuclei of the anterior hypothalamus was noted.     

Effect of linker length on the photomodification process of tyrosine residues in N-(tyrosyl)-N'-(5-azido-2-nitrobenzoyl)diaminoalkanes]

N-(Tyrosyl)-N'-(5-azido-2-nitrobenzoyl)-1,4-diaminobutane, containing a Tyr residue connected with the photoreactive aryl azide group through the diaminobutylene linker, was synthesized as a model for studying the photomodification of Tyr residues in proteins. This compound and the compound with a shorter, 1,2-diaminoethylene linker, obtained previously, were subjected to computer modeling to find their minimal-energy conformations. The aromatic rings of Tyr and 5-azido-2-nitrobenzoic acid residues in the latter compound were localized in parallel planes at a distance of approximately 0.3 nm between them and were shown to be implicated in stacking interactions. On the contrary, the planes of aromatic rings of the former compound with a longer, diaminobutylene linker were found to be situated perpendicularly to each other, with the distance between the centers of the rings being approximately 0.6 nm. The computer analysis was confirmed by experimental results: when studying the photomodification of the compound with the diaminobutylene linker, neither stable products of the Tyr photomodification nor unstable products capable of transformation into stable products in the dark were found. On the contrary, such products were previously identified in the case of the compound with diaminoethylene linker. The formation of amino, nitro, azoxy, and azo derivatives was common for the photomodification of both compounds.     

Diversification by host switching and dispersal shaped the diversity and distribution of avian malaria parasites in Amazonia

Understanding how pathogens and parasites diversify through time and space is fundamental to predicting emerging infectious diseases. Here, we use biogeographic, coevolutionary and phylogenetic analyses to describe the origin, diversity, and distribution of avian malaria parasites in the most diverse avifauna on Earth. We first performed phylogenetic analyses using the mitochondrial cytochrome b (cyt b) gene to determine relationships among parasite lineages. Then, we estimated divergence times and reconstructed ancestral areas to uncover how landscape evolution has shaped the diversification of Parahaemoproteus and Plasmodium in Amazonia. Finally, we assessed the coevolutionary patterns of diversification in this host–parasite system to determine how coevolution may have influenced the contemporary diversity of avian malaria parasites and their distribution among Amazonian birds. Biogeographic analysis of 324 haemosporidian parasite lineages recovered from 4178 individual birds provided strong evidence that these parasites readily disperse across major Amazonian rivers and this has occurred with increasing frequency over the last five million years. We also recovered many duplication events within areas of endemism in Amazonia. Cophylogenetic analyses of these blood parasites and their avian hosts support a diversification history dominated by host switching. The ability of avian malaria parasites to disperse geographically and shift among avian hosts has played a major role in their radiation and has shaped the current distribution and diversity of these parasites across Amazonia.     

New structural–optical effect in LiF–Li2B4O7 thin-film structures in the crystallization

The effect of optical radiation during the phase transition from the amorphous to the crystalline state of matter was investigated for the first time. The results were obtained on nanoscale films of (LiF)_x(Li₂B₄O₇)_1-x compositions by sputtering on cold Ni substrates. The starting materials for films were chosen due to their wide use for tissue-equivalent ionizing radiation dosimetry. It is shown that the detected thermoluminescence effect is sensitive to the thickness of the films. The paper compares the results of these studies with the study of the thermoluminescence characteristics of films irradiated by an M-30 microtron with bremsstrahlung radiation with a maximum energy of 6 MeV. The absorbed radiation dose was 1 kGy. Differences in the luminescence characteristics of irradiated and nonirradiated films were revealed. The nature of the demonstrated structural–optical effect is discussed.     

Cytokine profiles of HIV patients with pulmonary tuberculosis resulting from adjunct immunotherapy with herbal phytoconcentrates Dzherelo and Anemin

Dzherelo (Immunoxel) and Anemin when combined with standard anti-tuberculosis therapy (ATT) were shown to produce better clinical outcome than chemotherapy alone. Sixty HIV-positive patients with active pulmonary TB were equally divided into three matched groups to receive either ATT, ATT + Dzherelo, or ATT + Dzherelo + Anemin. Peripheral blood samples were measured by ELISA for plasma levels of IL-2, IL-6, TNF-α, IFN-γ, and IFN-α. After 6 months of follow-up Dzherelo and Dzherelo + Anemin combinations produced 61% (P = 0.005) and 44.4% (P = 0.06) higher levels of IL-2, whereas in ATT group they were reduced by 33.1% (P = 0.002). The levels of IL-6 increased by 17% (P = 0.15) in ATT group, but declined in both immune intervention groups by 26.2% (P = 0.007) and 21.3% (P = 0.22). TNF-α was suppressed in two immunotherapy groups by 19.1% (P = 0.06) and 76.3% (P = 0.02), respectively, but had risen by 14% (P = 0.42) in ATT patients. The pattern of production of IFN-γ was opposite to that of TNF-α, but statistical significance was stronger in patients receiving ATT and Dzherelo + Anemin than in Dzherelo group: −34% (P = 0.004), +31.9% (P = 0.008), and +17.3% (P = 0.33), respectively. Moderately decreased levels of IFN-α were observed in all treatment arms (range 0.9–16.6%) but differences were not significant. Despite considerable intra-group variation in cytokine production, the baseline inter-group averages were not statistically different indicating that the results were not biased by sample heterogeneity. Immunomodulators used in this study possibly act by enhancing natural immune response against TB. Expanded study of other cytokines and correlates relevant to control and protection from TB and HIV is needed in order to identify biomarkers of favorable treatment outcome, which may aid design of better immune interventions and vaccines.