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At least 19 recordsLinked to original sources
PubMed2026

Radiation-resistant and desiccation-tolerant bacteria from the Chavara-Neendakara high background radiation area, india: phenotypic characterisation and genomic insights.

Radiation-resistant microorganisms that survive high doses of ionising radiation serve as valuable models for understanding stress adaptation; however, the genomic determinants underlying extreme radiation tolerance in bacteria from natural environments with high background radiation remain insufficiently characterised. Bacterial isolates from the Chavara-Neendakara HBRA (Kerala, India) were evaluated for desiccation tolerance, and the desiccation-resistant isolates were subsequently exposed to gamma irradiation (1-10 kGy) using a 60Co source. Isolates were identified through 16S rRNA sequencing, morphologically characterised by FE-SEM, and screened for antibiotic susceptibility. The highly radiation-resistant strain underwent whole-genome sequencing via Oxford Nanopore Technology, with De novo assembly, polishing, and genome annotation. Four bacterial isolates (Micrococcaceae and Paenibacillaceae) exhibited D10 values of 1-7 kGy, including one multidrug-resistant strain; no endospores were observed in the Paenibacillus isolate under the tested conditions. Paenibacillus sp. HBRA004 survived 10 kGy gamma radiation, exceeding all previously reported HBRA isolates by over fourfold. Its 5.0 Mbp genome (GC = 48.27%, ≥ 99% completeness) encodes five mechanistically independent DNA repair pathways; homologous recombination (recA, recN, radA), base excision repair (mutM, mutY, mutT), mismatch repair (mutL, mutS), nucleotide excision repair (uvrA, uvrB, uvrD), and non-homologous end joining (ku, ligD), alongside a redundant antioxidant network comprising triple-copy Fe/Mn-family superoxide dismutases and ahpC peroxiredoxin. A thioredoxin system (trxA, trxB, msrA) and manganese uptake via mntH may contribute to further layers of ROS defence. Their specific contribution to the HBRA004 phenotype remains to be experimentally and comparatively validated. These findings represent the first genomically characterised 10 kGy-resistant bacterial isolate from the Chavara-Neendakara HBRA, establishing a new benchmark for radiation tolerance within this ecologically significant environment. Pathway depth, gene copy amplification, and Mn/Fe homeostasis appear to be candidate mechanisms contributing to high-level radiation tolerance, consistent with patterns in other radiation-resistant taxa, though their contribution requires functional validation.

India↗
PubMed1991

Chromosome aberration, cancer mortality and hormetic phenomena among inhabitants in areas of high background radiation in China.

The respective average annual doses are about 330 and 110 mR/yr, in the high background radiation areas (HBRA) in Yangjiang County and the control areas (CA) in Enping and Taishan Counties. Both the HBRA and CA are in Guangdong Province which borders the South China Sea. The frequencies of chromosome aberration in circulating lymphocytes were examined for persons residing in the HBRA and CA. Those in the HBRA had increased frequencies of detectable abnormalities in stable aberrations (translocations and inversions) and unstable aberrations (dicentrics and rings). Previous reports have shown that when samples of circulating lymphocytes taken from inhabitants were tested in vitro for mitotic responses to phytohemagglutinin (PHA) and for the degree of unscheduled DNA synthesis (UDS) induced by UV-irradiation, there were higher responsiveness and UDS rates for those in the HBRA than in the CA. In contrast, mortality from all cancers and those from leukemia, breast and lung cancers that are inducible by radiation was not higher in the HBRA. Although the differences in the cancer mortality rates for the HBRA and CA are not significant, the findings are compatible with the assumption that the lower mortality from cancer in the HBRA is the result of the hormetic effects of the three-fold higher dose rate of background radiation in that areas. This assumption requires further study.

Adolescent↗
PubMed1975

Radioresistance in natural populations of Drosophila nebulosa from a Brazilian area of high background radiation.

D. nebulosa, collected in two woods of a high background radiation area (both in Iron Hills, State of Minas Gerais, Brazil), were compared to and found to be more resistant than flies collected as controls in two other woods of an adjacent area. This was the second time that average differences in radioresistance between natural populations were established. Previous experiments were carried out with D. willistoni, in the same area and in comparable fashion. In spite of their higher radiation resistance the flies from the radiation area carried a higher expressed load than the controls. The following tests were performed to estimate the differences: (a) survival, after whole body exposure to 90 000 R of 60Co-gamma-rays on 120 strains set up from single inseminated females and (b) reproductive performance, in 240 duplicate croses, measured in terms of the difference between irradiated series (males received 3000 R of 60Co-gamma-rays) and their unirradiated counterparts. The data are based on an offspring of 293784 individuals. Futhermore, two diallel crosses between sensitive and resistant strains have shown that the differences probably are due mainly to additive genes.

Animals↗
PubMed1992

[The reproductive potential of the bank vole (Clethrionomys glareolus Schreb) and of the tundra vole (Microtus oeconomus Pall.) under the conditions of the elevated radiation background of Bryansk Province].

The continuous irradiation (connected with the accident on the Chernobyl atomic power plant) by cesium-137 of the dominant species of rodents (Clethrionomys glareolus, Microtus oeconomus) in the forests of Bryansk Province had a deteriorating effect on the state of reproductive organs and on the course of embryogenesis, stimulated the reproduction cycle but inhibited the rate of sexual maturation and increased the death-rate of young animals. These effects resulted in significant ageing of the population. But all these phenomena provoked by radiation are within the limits of rodents adaptive capacities.

Accidents↗
PubMed1992

The mutation frequency of Drosophila melanogaster populations living under conditions of increased background radiation due to the Chernobyl accident.

One of the problems facing the program in the wake of the Chernobyl accident is the estimation of genetic damage to plants and animals. Special attention was directed to studying the influence of radioactive pollutants at the accident site by means of an appropriate test system, using standard genetic subjects. The present study describes such investigations. Levels of persistent genetic damage in natural populations of Drosophila melanogaster found in the vicinity of the Chernobyl accident site were examined from August 1986 to September 1989. Evidence is presented which indicates a relationship between the levels of radioactive pollution resulting from the Chernobyl accident and increasing genetic damage to exposed populations. The possible reasons for the decrease of mutation frequency observed in 1988 and 1989 are also discussed. Furthermore, evidence is presented which suggests that radiosensitive Drosophila mutants may be particularly sensitive indicators of radioactive pollution.

Accidents↗