European checkerspots (Melitaeini: Lepidoptera,Nymphalidae) are not aposematic – the point of view of great tits (Parus major)

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The road will be mastered by the walker

Anonymous questioning by the distribution of questionnaires among 1,600 young people (68.9% of them were city dwellers, 31.1% were villagers) was carried out. The questioning covered 1,079 adolescents aged 12-16 years (67.3%), 501 young people aged 16-19 years (31.3%) and 20 respondents aged 19-23 years (1.4%). The analysis of answers to questionnaires indicated that all respondents had the same level of knowledge on the subject, but the information they possessed was not duly analyzed and had no influence on their own behavior. It should be pointed out that 1% of persons aged 12-19 years took drugs by intravenous injection. These data, as well as other materials, gave grounds for the development of a new educational program on the prophylaxis of HIV/AIDS/STD and its introduction in 1997. The program is intended for a school course of 6 years (forms 6-11) and must provide adolescents with reliable and comprehensible information, conductive to the formation of a healthy mode of life.     

Ribosomal genes in inbred mouse strains: interstrain and intrastrain variations of copy number and extent of methylation

Quantitative dot hybridization was used to estimate the rDNA copy number in brain tissues of five inbred mouse strains (AKR/JY, NZB/B1OrlY, CBA/CaLacY, 101/HY, and 129/JY), which were obtained from the collection of the Research Center of Biomedical Technologies (Y). In each strain, 9-12 mice aged 1-2 months were examined. The rDNA copy number per diploid genome in strains AKR (range 105-181, mean +/- SD 136 +/- 27) and NZB (129-169, 148 +/- 12) was significantly lower than in strains CBA (172-267, 209 +/- 31), 101 (179-270, 217 +/- 30), and 129 (215-310, 264 +/- 33). Mice of strain NZB were relatively homogeneous in this trait (CV = 8.1%). Strains AKR, CBA, 101, and 129 displayed significant between-group differences, CV varying from 12.5 to 19.9%. The same DNA specimens were digested with MspI or HpaII and used to estimate the extent of methylation of the 28S rDNA region. Regardless of the strain, all mice could be classed into two groups. One group (20 mice) had a methylated fraction accounting for less than 8% of rDNA and included all nine mice of strain NZB, seven out of nine mice of strain 101, and three out of ten mice of strain 129. In the other group (29 mice), the methylated fraction varied from 18 to 38%. A possible role of methylation and the genome dosage of ribosomal genes in phenotypic variation (quantitative trait variation) of inbred mouse strains is discussed.     

Ribosomal genes in inbred mouse strains: Interstrain and intrastrain variation of copy number and extent of methylation

Quantitative dot hybridization was used to estimate the rDNA copy number in brain tissues of five inbred mouse strains (AKR/JY, NZB/B1OrlY, CBA/CaLacY, 101/HY, and 129/JY), which were obtained from the collection of the Research Center of Biomedical Technologies (Y). In each strain, 9–12 mice aged 1–2 months were examined. The rDNA copy number per diploid genome in strains AKR (range 105–181, mean ± SD 136 ± 27) and NZB (129–169, 148 ± 12) was significantly lower than in strains CBA (172–267, 209 ± 31), 101 (179–270, 217 ± 30), and 129 (215–310, 264 ± 33). Mice of strain NZB were relatively homogeneous in this trait (CV = 8.1%). Strains AKR, CBA, 101, and 129 displayed significant between-group differences, CV varying from 12.5 to 19.9%. The same DNA specimens were digested with MspI or HpaII and used to estimate the extent of methylation of the 28S rDNA region. Regardless of the strain, all mice could be classed into two groups. One group (20 mice) had a methylated fraction accounting for less than 8% of rDNA and included all nine mice of strain NZB, seven out of nine mice of strain 101, and three out of ten mice of strain 129. In the other group (29 mice of strains AKR, CBA, 101, and 109), the methylated fraction varied from 18 to 38%. A possible role of methylation and the genome dosage of ribosomal genes in phenotypic variation (quantitative trait variation) of inbred mouse strains is discussed.     

ABCB1 identifies a subpopulation of uveal melanoma cells with high metastatic propensity

Metastasis of tumor cells to distant organs is the leading cause of death in melanoma. Yet, the mechanisms of metastasis remain poorly understood. One key question is whether all cells in a primary tumor are equally likely to metastasize or whether subpopulations of cells preferentially give rise to metastases. Here, we identified a subpopulation of uveal melanoma cells expressing the multidrug resistance transporter ABCB1 that are highly metastatic compared to ABCB1(-) bulk tumor cells. ABCB1(+) cells also exhibited enhanced clonogenicity, anchorage-independent growth, tumorigenicity and mitochondrial activity compared to ABCB1(-) cells. A375 cutaneous melanoma cells contained a similar subpopulation of highly metastatic ABCB1(+) cells. These findings suggest that some uveal melanoma cells have greater potential for metastasis than others and that a better understanding of such cells may be necessary for more successful therapies for metastatic melanoma.     

The antioxidant function of the p53 tumor suppressor

It is widely accepted that the p53 tumor suppressor restricts abnormal cells by induction of growth arrest or by triggering apoptosis. Here we show that, in addition, p53 protects the genome from oxidation by reactive oxygen species (ROS), a major cause of DNA damage and genetic instability. In the absence of severe stresses, relatively low levels of p53 are sufficient for upregulation of several genes with antioxidant products, which is associated with a decrease in intracellular ROS. Downregulation of p53 results in excessive oxidation of DNA, increased mutation rate and karyotype instability, which are prevented by incubation with the antioxidant N-acetylcysteine (NAC). Dietary supplementation with NAC prevented frequent lymphomas characteristic of Trp53-knockout mice, and slowed the growth of lung cancer xenografts deficient in p53. Our results provide a new paradigm for a nonrestrictive tumor suppressor function of p53 and highlight the potential importance of antioxidants in the prophylaxis and treatment of cancer.     

The changing of cell-free DNA properties of peripheral blood and TCR-mutant cell frequency in individuals exposed to ionizing radiation

Some properties of the cell-free DNA (cfDNA) of peripheral blood plasma were assessed in 153 employees of atomic industry enterprises. The contents of ribosomal repeat (rDNA) and its concentration in plasma increased in cfDNA of the group of persons in comparison with non-irradiated individuals. The contents of satellite III in cfDNA of donors and of irradiated persons do not differ and less than in DNA nucleus. The correlation between cumulative dose of radiation, contents of rDNA in cfDNA and the frequency of lymphocytes bearing mutations at T-cell receptor (TCR) locus was obtained. The definition of three indications in irradiated persons: the contents of ribosomal genes in cfDNA, TCR-mutant cell frequency and concentration of ribosomal genes in blood plasma--may be useful for revealing individuals in organism of which an intensive cell apoptosis takes place and there is an increased probability of carcinogenesis and of progress of disease of immune system.     

ONTOGENETIC NICHE SHIFT IN THE BRACHIOPOD TEREBRATALIA TRANSVERSA: RELATIONSHIP BETWEEN THE LOSS OF ROTATION ABILITY AND ALLOMETRIC GROWTH

Abstract: Many articulated brachiopods experience marked life habit variations during ontogeny because they experience their fluid environment at successively higher Reynolds numbers, and they can change the configuration of their inhalant and exhalant flows as body size increases. We show that the extant brachiopod Terebratalia transversa undergoes a substantial ontogenetic change in reorientation governed by rotation around the pedicle. T. transversa′s reorientation angle (maximum ability to rotate on the pedicle) decreases during ontogeny, from 180 degrees in juveniles to 10–20 degrees in individuals exceeding 5 mm, to complete cessation of rotation in individuals larger than 10 mm. Rotation ability is substantially reduced after T. transversa achieves the adult lophophore configuration and preferred orientation with respect to ambient water currents at a length of 2.5–5 mm. We hypothesize that the rotation angle of T. transversa is determined mainly by the position of ventral and dorsal points of attachment of dorsal pedicle muscles relative to the pedicle. T. transversa shows a close correlation between the ontogenetic change in reorientation angle and ontogeny of morphological traits that are related to points of attachment of dorsal pedicle muscles, although other morphological features can also limit rotation in the adult stage. The major morphological change in cardinalia shape and the observed reduction of rotation affect individuals 2.5–10 mm in length. The position of ventral insertions of dorsal pedicle muscles remains constant, but contraction of dorsal pedicle muscles is functionally handicapped because dorsal insertions shift away from the valve midline, rise above the dorsal valve floor, and become limited by a wide cardinal process early in ontogeny (<5 mm). The rate of increase of cardinal process width and of distance between dorsal pedicle muscle scars substantially decreases in the subadult stage (5–10 mm), and most of the cardinalia shell traits grow nearly isometrically in the adult stage (>10 mm). T. transversa attains smaller shell length in crevices than on exposed substrates. The proportion of small‐sized individuals and population density is lower on exposed substrates than in crevices, indicating higher juvenile mortality on substrates prone to grazing and physical disturbance. The loss of reorientation ability can be a consequence of morphological changes that strengthen substrate attachment and maximize protection against biotic or physical disturbance (1) by minimizing torques around the pedicle axis and/or (2) by shifting energy investments into attachment strength at the expense of the cost involved in reorientation.     

Human parthenogenetic stem cells produce enriched populations of definitive endoderm cells after trichostatin A pretreatment

Human parthenogenetic stem cells (hpSC) hold great promise as a source of pluripotent stem cells for cell-based transplantation therapy due to their ethical method of derivation as well as the enhanced capacity for immunomatching with significant segments of the human population. We report here the directed differentiation of hpSC to produce enriched populations of definitive endoderm. Moreover, we find that treatment of undifferentiated hpSC by trichostatin A (TSA) before applying the directed differentiation protocol significantly increases the proportion of definitive endoderm cells in the final population. TSA-pretreated as well as non-TSA-treated hpSC undergoing differentiation toward definitive endoderm demonstrate a similar temporal sequence of gene expression to that which occurs in the course of definitive endoderm differentiation during vertebrate gastrulation and for differentiation of hESCs to definitive endoderm. Creation of the definitive endoderm lineages from hpSC represents the critical first step toward the development of hpSC-based cellular therapies for diseases of the liver or pancreas.