Biomaterial Database

Stage-dependent variation in the radiosensitivity of DNA in developing male germ cells. 1990

D S Joshi, and J Yick, and D Murray, and M L Meistrich

Department of Experimental Radiotherapy, University of Texas M. D. Anderson Cancer Center, Houston 77030.

The induction and rejoining of gamma-ray-induced DNA single-strand breaks (SSBs) were measured in the spermatogenic cells of mice using the alkaline elution technique. The animals were injected with [3H]thymidine and sacrificed on subsequent days to examine selectively cohorts of radiolabeled cells in the successive stages of maturation. A significantly increased frequency of SSB was observed in the unirradiated early spermatocytes and late spermatids, associated with genetic recombination and chromatin compaction, respectively. The frequency of SSBs induced by irradiation of animals in vivo remained constant from the early spermatocyte through mid-spermatid stages and decreased significantly only after the cells matured to the late spermatid stage. The frequency of SSBs after in vitro irradiation of testicular cell suspensions also decreased as round spermatids matured to late spermatids. Such decreases for both modes of irradiation may result from maturation-dependent alterations in chromatin in late spermatids, such as condensation and replacement of histones with protamines, rather than from changes in oxygen tension. Rejoining of SSBs in vivo was efficient in the spermatocytes and early spermatids but declined in late spermatids. Possible reasons for the discrepancy between the greater number of unrepaired lesions and lower susceptibility to mutation induction in late spermatids than in round spermatids are discussed.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D008809	Mice, Inbred C3H	An inbred strain of mouse that is used as a general purpose strain in a wide variety of RESEARCH areas including CANCER; INFECTIOUS DISEASES; sensorineural, and cardiovascular biology research.	Mice, C3H,Mouse, C3H,Mouse, Inbred C3H,C3H Mice,C3H Mice, Inbred,C3H Mouse,C3H Mouse, Inbred,Inbred C3H Mice,Inbred C3H Mouse
D011836	Radiation Tolerance	The ability of some cells or tissues to survive lethal doses of IONIZING RADIATION. Tolerance depends on the species, cell type, and physical and chemical variables, including RADIATION-PROTECTIVE AGENTS and RADIATION-SENSITIZING AGENTS.	Radiation Sensitivity,Radiosensitivity,Sensitivity, Radiation,Tolerance, Radiation,Radiation Sensitivities,Radiation Tolerances,Radiosensitivities,Sensitivities, Radiation,Tolerances, Radiation
D004249	DNA Damage	Injuries to DNA that introduce deviations from its normal, intact structure and which may, if left unrepaired, result in a MUTATION or a block of DNA REPLICATION. These deviations may be caused by physical or chemical agents and occur by natural or unnatural, introduced circumstances. They include the introduction of illegitimate bases during replication or by deamination or other modification of bases; the loss of a base from the DNA backbone leaving an abasic site; single-strand breaks; double strand breaks; and intrastrand (PYRIMIDINE DIMERS) or interstrand crosslinking. Damage can often be repaired (DNA REPAIR). If the damage is extensive, it can induce APOPTOSIS.	DNA Injury,DNA Lesion,DNA Lesions,Genotoxic Stress,Stress, Genotoxic,Injury, DNA,DNA Injuries
D004260	DNA Repair	The removal of DNA LESIONS and/or restoration of intact DNA strands without BASE PAIR MISMATCHES, intrastrand or interstrand crosslinks, or discontinuities in the DNA sugar-phosphate backbones.	DNA Damage Response
D004277	DNA, Single-Stranded	A single chain of deoxyribonucleotides that occurs in some bacteria and viruses. It usually exists as a covalently closed circle.	Single-Stranded DNA,DNA, Single Stranded,Single Stranded DNA
D004307	Dose-Response Relationship, Radiation	The relationship between the dose of administered radiation and the response of the organism or tissue to the radiation.	Dose Response Relationship, Radiation,Dose-Response Relationships, Radiation,Radiation Dose-Response Relationship,Radiation Dose-Response Relationships,Relationship, Radiation Dose-Response,Relationships, Radiation Dose-Response
D005720	Gamma Rays	Penetrating, high-energy electromagnetic radiation emitted from atomic nuclei during NUCLEAR DECAY. The range of wavelengths of emitted radiation is between 0.1 - 100 pm which overlaps the shorter, more energetic hard X-RAYS wavelengths. The distinction between gamma rays and X-rays is based on their radiation source.	Gamma Wave,Gamma Radiation,Nuclear X-Rays,Radiation, Gamma,X-Rays, Nuclear,Gamma Radiations,Gamma Ray,Gamma Waves,Nuclear X Rays,Nuclear X-Ray,Ray, Gamma,Wave, Gamma,Waves, Gamma,X Rays, Nuclear,X-Ray, Nuclear
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D013087	Spermatids	Male germ cells derived from the haploid secondary SPERMATOCYTES. Without further division, spermatids undergo structural changes and give rise to SPERMATOZOA.	Spermatoblasts,Spermatid,Spermatoblast