Level of chromosome aberrations in peripheral blood lymphocytes in evacuees from the 30-kilometer zone of the Chernobyl Atomic Energy Station and residents of radioactively-polluted territories in the long term after the Chernobyl accident

Eighteen Ukrainian evacuees from the Chernobyl exclusive zone, twenty one inhabitants of radioactively contaminated areas of Belarus and twelve control donors age-matched to the exposed persons were investigated 14-15 years after the Chernobyl accident for chromosomal aberration yields detected in blood lymphocytes by fluorescence in situ hybridisation technique. Unstable aberration yields measured in both Chernobyl cohorts were close to the background frequencies. Positive age-dependence trends in control donors were determined for the all type stable aberration levels. In evacuees the tendency for diminishing the difference between them and controls for stable aberration levels with persons' age increasing was found. The total stable chromosome exchange yields in evacuees 46-55 years old and inhabitants of areas with low contamination level didn't exceed the control values, but for younger evacuees and inhabitants of sufficiently contaminated regions the statistical increase above the age relevant background meanings was detected for this end-point. The advantages of using the FISH-detectable stable aberrations and particularly the total level of stable chromosome exchanges as the end-points for retrospective biological indication of past radiation exposure in Chernobyl cohorts were discussed.     

An Examination of the Association between 5-HTTLPR,Combat Exposure,and PTSD Diagnosis among U.S. Veterans

Objective

To examine the association between the 5-HTTLPR polymorphism of the serotonin transporter (SLC6A4) gene, combat exposure, and posttraumatic stress disorder (PTSD) diagnosis and among two samples of combat-exposed veterans.

Method

The first sample included 550 non-Hispanic Black (NHB) combat-exposed veterans. The second sample included 555 non-Hispanic White (NHW) combat-exposed veterans. Participants were genotyped for the 5-HTTLPR/rs25531 variants of the SLC6A4 gene. A structured clinical interview was used to diagnose PTSD. Combat and civilian trauma exposure were assessed with validated self-report instruments. Logistic regression was used to test for main effects of 5-HTTLPR on PTSD diagnosis as well as gene x environment (GxE) interactions after adjusting for sex, ancestry proportion scores, civilian trauma exposure, and combat exposure.

Results

Within the NHB sample, a significant additive effect was observed for 5-HTTLPR (OR = 1.502, p = .0025), such that the odds of having a current diagnosis of PTSD increased by 1.502 for each additional S’ allele. No evidence for an association between 5-HTTLPR and PTSD was observed in the NHW sample. In addition, no evidence for combat x 5-HTTLPR effects were observed in either sample.

Conclusion

The present study suggests that there may be an association between 5-HTTLPR genotype and PTSD diagnosis among NHB veterans; however, no evidence for the hypothesized 5-HTTLPR x combat interaction was found.     

Sequential colonization by river periphyton analysed by microscopy and molecular fingerprinting

1. An artificial glass substratum was incubated in the River Danube for a period of 28 days in order to detect the sequential colonization of microorganisms.
2. Light and fluorescent microscopy showed that microalgae and the picoalgal fraction on the slides increased rapidly over the first 2 weeks of colonization. Diatoms were numerically the most abundant component of the periphyton and their species richness and diversity increased rapidly in the early phase of colonization whereas diversity subsequently increased moderately.
3. Evenness of the diatom community was initially high, lower in the intermediate phase and again higher later on. Succession involving early, intermediate and late colonizer species was observed. Community composition during the first 5 days of colonization was very different from later stages whereas there were only minor changes subsequently.
4. Molecular community analysis by means of terminal restriction fragment length polymorphism analysis of PCR amplified 16S rRNA and 18S rRNA genes pointed to even larger differences between the composition of samples obtained early and late in the period.
5. The number of 18S rRNA and 16S rRNA terminal restriction fragments (T-RF-s) was variable over the colonization period and the fragment patterns of both the bacterial and eukaryotic portion of the microbial community were variable, with most T-RF-s unique to a single sample, suggesting a wide diversity and dynamic properties of periphytic organisms.     

Possibilities and limitations of fluorescence in situ hybridization technique in retrospective detection of low dose radiation exposure in post-chernobyl human cohorts

Cytogenetic analysis using the fluorescence in situ hybridisation (FISH) technique was performed late time after the Chernobyl accident in groups of liquidators, evacuees from 30 km exclusive zone, residents of radioactively contaminated areas and control donors age-matched to exposed persons. Stable and unstable chromosome type exchanges were recorded using a hybrid conventional-PAINT nomenclature. The mean yield of stable chromosome exchanges in liquidators did not correlate with registered radiation doses but had a clear negative dependence on the duration of liquidators' staying in Chernobyl zone, that was in a good agreement with early data based on conventional dicentrics plus rings analysis. The overspontaneous excess for stable chromosome exchange level appeared to be higher in evacuees 16-40 years old than that of senior persons, whereas no age-dependent difference occurred for initially induced dicentrics plus rings yields in this cohort. The stable chromosome exchange yield, as well as combined yield of dicentrics plus rings and potentially unstable incomplete translocations in residents of radioactively contaminated areas showed a reasonable positive correlation with levels of 137Cs contamination. The observed yields of stable chromosome exchanges in all three exposed groups appeared to be somewhat lower than those of expected from unstable exchange-based doses which were referred to an in vitro dose response of stable exchanges outcome in human lymphocytes. Thus, FISH analysis can be successfully applied for qualitative cytogenetic indication of past and chronic radiation exposure to low doses but further refinement of FISH-based system for quantitative dose assessment is still required. Some practical approaches of solving this task are discussed.     

The retrospective cytogenetic dosimetry using the results of conventional chromosomal analysis in Chernobyl clean-up workers

The paper presents the results of the cohortal biodosimetry carried out in 435 Chernobyl clean-up workers, who were surveyed with the conventional cytogenetic technique in terms from several days to 10 years after the end of their duties in the Chernobyl accident exclusive zone. An empirical model of the aberrant cell dynamics was utilized for the calculation of mean initial yields of dicentrics and centric rings in groups with different terms and duration of staying in the Chernobyl zone. Corresponding protracted irradiation doses estimated from aberration levels ranged from 79 to 670 mGy. The probabilistic distribution of the radiation doses was constructed by the applying the Bayesian analysis to initial individual chromosome exchange yields extrapolated to the exposure termination moment. This distribution was characterized by the mean dose about 460 mGy and maximum of probability density in the interval of 50-300 mGy. For the late somatic risk assessment in clean-up workers the probabilistic distribution of equivalentally-acute radiation doses was proposed; that had the mean value about 270 mGy, modal classes of 250-350 mGy and 99.8% of the probability density concentrated within the dose range from 0 to 1000 mGy.     

Time-effect relationship for unstable chromosome exchange levels in Chernobyl clean-up workers

The post-irradiation changes of dicentric and centric ring levels were studied in Chernobyl liquidators using the data of 507 individual chromosomal surveys of persons sampled at different time after their activities at Chernobyl NPP accident zone. The time-effect relationship within 0-10.5 years after exposure was displayed as exponential decline of the mean chromosome exchange frequency with average decay half-time 2.2 y. During 10.5-13 years after exposure the increasing and stabilization of chromosome exchange yield on the level 2-3-times higher than control was observed. In the first few months after irradiation the dicentric and centric ring frequency in liquidators had the clear reverse correlation with the duration of person's duties at the Chernobyl zone. The parameters of unstable chromosome exchange elimination were independent on the initially induced aberration yield, that resulted in earlier reaching the subcontrol level in persons who had more protracted duration of duties at the Chernobyl accident zone.     

Concerted transpositions of mobile genetic elements coupled with fitness changes in Drosophila melanogaster

In an inbred low-activity (LA) strain of Drosophila melanogaster with a low level of fitness and a complex of inadaptive characters, in situ hybridization reveals an invariant pattern of distribution of three copia-like elements (mdg-1, mdg-3, and copia). Rare, spontaneous, multiple transpositions of mobile elements in the LA strain were shown to be coupled with a drastic increase of fitness. A changed pattern of various types of mobile elements was also observed on selecting the LA strain for higher fitness. High-fitness strains show transpositions of mobile elements to definite chromosomal sites ("hot spots"). Concerted changes in the location of three different mobile elements were found to be coupled with an increase of fitness. The mdg-1 distribution patterns were also examined in two low-fitness strains independently selected from the high-fitness ones. Fitness decrease was accompanied by mdg-1 excision from the hot spots of their location usually detected in the high-fitness strains. The results suggest the existence of a system of adaptive transpositions of mobile elements that takes part in fitness control.