Proteolytic processes in lung tissue of rat posterity after whole-body chronic irradiation with low doses

Intensification of proteolytic processes accompanied by inhibited antiprotease activity in lung tissue of first generation posterity of rats irradiated with a total dose of 0.25 Gy (0.01 Gy per day) before gestation was shown. The obtained data satisfied to imbalance in functioning of regulation systems, tension of adaptation mechanisms with possible rapider reduction of adaptation resistance of broncho-lung system of irradiated parents' posterity. Vector changes in correlation of indexes in the proteinase-antiproteinase system were analogous in all experimental series (irradiated male x irradiated female, irradiated male x intact female, intact male x irradiated female) with maximal expression in the group obtained from parents both irradiated before gestation. It could be possible to propose a presence of non-stable genome in posterity of irradiated parents, that satisfied to role of genetic aspects in development of the late functional disorders.     

Consequences for posterity of two generations of an irradiation pregnant from females rats Wistar in small doses during a bookmark of reproduction system of fetuses development of posterity of the second generation and it reproduction function

With the purpose of study of consequences for development and reproduction functions of posterity of the second generation from females rats Wistar of a total unitary gamma-irradiation in dozes 0.25; 0.5 and 1 Gy (capacity of a doze 0.03 sGy/s) on 10th day of pregnancy (the period of the onset of fetuses reproduction system development) is investigated more than 630 females, 1400 with the age of 19th days, and about 3200 young rats. The revealed deviations(rejections) in development of posterity of two generations parents, antenatal irradiated in not sterilizing dozes, in he period of a beginning of formation of reproduction system, them a variety at different dozes of radiating influence, shown as at posterity of the irradiated mothers, and fathers, testify about instability genoms in a line of generations requiring the account and acceptance of necessary measures for preservation normal genofund.     

Genome instability in the F1-progeny of mice irradiated by ionizing radiation as determined by micronucleus assay

The F1-progeny of BALB/c male mice chronically exposed to low-dose gamma-radiation (0.1; 0.25 and 0.5 Gy; dose rate 0.01 Gy/day) as well as the F1-progeny of females exposed to acute X-radiation (0.5; 1.0 and 2.0 Gy; dose rate 0.1 Gy/min) shown the significant elevated micronuclei frequencies in bone marrow erythrocytes, as compared to the F1-progeny of unirradiated males and females. The increase in the micronuclei frequency in the F1-progeny was determined by the dose of irradiation of parents. The values of elevated micronuclei frequency in the F1-progeny of chronically irradiated males and acutely irradiated females for a dose of 0.5 Gy were comparable. The micronuclei frequencies in the F1-progeny of irradiated females and males for this dose were in 1.5 and in 1.6 times higher than ones in the F1-progeny of unirradiated mice correspondingly. The results suggest the possibility of transfer of genome instability from irradiated parents to the somatic cells of the F1-progeny via non-lethally damaged germ cells of parents.     

Embryogenesis and early postnatal ontogenesis of posterity of two generations of female Wistar rats,depending on the time of their fertilization after low dose radiation exposure

On the first day and 3-10 or 40-60 days after a single whole-body gamma-irradiation with doses of 0.25, 0.5 and 1 Gy, the pubertal female Wistar rats coupled with intact males. The embryogenesis and early postnatal ontogenesis of posterity of two generations from these parents were investigated. A raised mutation rate and physiological inferiority of the progeny was found, depending both on a dose and on the degree of oocyte maturity at the moment of the irradiation. The obtained data showed the instability of the irradiated genome in a number of generations.     

Genetic consequences of irradiation of one or both parents (results of experiments on Wistar rats) Exitus lethalis in Wistar rat's progeny after irradiation of one or both parents

Examination of 2563 offsprings of Wistar rats after irradiation of one or both parents with doses of 0.25, 0.5, 1, 2, 3 and 4 Gy was carried out; the manifestation of lethal effects in the progeny of the first generation in ontogenesis was studied. The level of embryonic death was the highest after irradiation of germ cells of parents at stages of spermatids, spermatozoids and matured oocytes. Following irradiation of both parents with doses of 0.25, 0.5 and 1 Gy at these stages of gametogenesis and 4 Gy at the stage of spermatids and matured oocytes there was a trend of increasing radiation effects caused by the participation of two irradiated germ cells. After irradiation of both parents with doses of 2, 3 and 4 Gy the embryonic death F1 was essentially the same as rates for irradiated females and non-irradiated males. The F1 death rate in early postnatal development exceeded the control only after irradiation with doses of 2, 3 and 4 Gy. The increase in radiation effects in the F1 due to the mating of two irradiated parents appears to be associated with a mechanism demonstrating additivity or synergism.     

Deoxyribonucleic Acid Transferred from Ultraviolet-Irradiated Excision-Defective Hfr Cells of Escherichia coli K-12

Deoxyribonucleic acid (DNA) transfer from (3)H-thymine-labeled Hfr cells has been measured by determining the amount of radioactivity remaining after selective lysis of the donor cells in the mating mixture. DNA transfer was less effectively reduced by ultraviolet irradiation of excision-defective Hfr cells than was the yield of recombinants. The buoyant density of DNA transferred from unirradiated and irradiated Hfr cells was equivalent to that of double-stranded DNA. Mating-dependent DNA synthesis in the recipient has been measured by mating Hfr cells deficient in thymidine kinase with irradiated thymine-requiring F(-) cells in the presence of (3)H-thymine. The extent of such DNA synthesis approximated the amount of DNA transferred from unirradiated donors. Neither DNA transfer nor mating-dependent DNA synthesis could be reliably measured when both parents were irradiated. It is proposed that transferred Hfr DNA is replicated in the recipient and that this replication still occurs when the Hfr DNA contains dimers.     

Effect of Rec− Mutations on the Activity of Colicinogenic Factors

The effect of two Rec(-) mutations (AB2463 and JC1553) on the ability of a cell to accept, maintain, and express the colicinogenic factors ColE(1), ColE(2), and ColV was examined in Escherichia coli. These mutations had no observable effect on the colicinogenic properties of the ColV factor, but prevented the spontaneous and induced production of colicins E(1) and E(2) which are determined by the ColE(1) and ColE(2) factors, respectively. The two Rec(-) mutations had no apparent effect on the ability of the cells to acquire, maintain, or transfer the ColE(1) and ColE(2) factors. These mutations did not affect the expression of immunity by any of the three Col factors. ColE(1) and ColE(2) were also shown to be indirectly induced by mating F(-) cells carrying these Col factors with ultraviolet-irradiated, non-colicinogenic, Hfr and F(+) cells. Indirect induction of colicin production occurred when either an irradiated F(+) Rec(+) or F(+) Rec(-) strain was employed as the donor strain.     

Embryonic mortality of the root vole as an index of the effect of small doses of natural radioactivity on genetic processes in populations

A study was made of the pre- and post-implantation death of (F2--F4) Microtus oeconomus progeny whose parents lived in territories where natural radiation background was increased (an exposition dose-rate of 3.6-144.0 pC/kg X s). The spontaneous rate of pre- and post-implantation death of progeny of irradiated (experimental) animals was higher than that of intact ones (control). The animals kept in conditions of chronic irradiation (46.2 pC/kg X s) exhibited a more pronounced discrepancy in embryonal death rate. It is suggested that genetic differences in the populations were responsible for different rate of embryonal death of the control and experimental animals.     

The reproductive capacity of male mice protected against the superlethal action of gamma radiation by the administration of a mixture of Archangelica officinalis and Ledum palustre extracts]

Thirty-day old albino mongrel male mice were exposed to gamma radiation (LD90/30) after preventive single injection of a mixture of extracts from Archangelica officinalis and Ledum palustre. One month after irradiation, the survivors were mated to nonirradiated females. Healthy offspring were obtained from 11 out 12 experimental males. The number of mouse pups was 10.2 +/- 0.6 and 7.4 +/- 0.7 in the experimental and nonirradiated groups respectively. The number of both sexes in the posterity of nonirradiated parents was equal, whereas in offspring of experimental groups, the number of female pups was 2.3 times larger than that of males. The experimental posterity was found to be resistant to supralethal radiation doses.     

Transmission of genome damage from irradiated male rats to their progeny

The effect of gamma-radiation (3Gy) on slowly proliferating liver tissue of male rats and their progeny was investigated with respect to induction and duration of latent damage. The irradiation caused latent cytogenetic damage in the liver in irradiated males of the F(0) generation, which manifested itself in different ways during proliferation of hepatocytes induced by partial hepatectomy: a reduced proliferating activity, a higher frequency of chromosomal aberrations and a higher proportion of cells with apoptotic DNA fragments were observed, compared with non-irradiated rats. In the progeny of irradiated males (F(1) and F(2) generation), the latent genome damage manifested itself during regeneration of the liver after partial hepatectomy by similar, but less pronounced changes compared with those seen in irradiated males of the parental generation. This finding gave evidence of the transfer of part of the radiation-induced genome damage from parents to their offspring. Irradiation of F(1) and F(2) progeny of irradiated males (their total radiation load being 3 + 3 and 3 + 0 + 3 Gy, respectively) caused less change as irradiation of progeny of non-irradiated control males (their total radiation load being 0 + 3 and 0 + 0 + 3 Gy, respectively).     

The phenomenon of the single-strand DNA breaks level decrease in blood system cells in first generation chronically irradiated mice

For the first time has been shown experimentally that chronic low dose-rate gamma-radiation (0.04 mGy/hr) exposure leads to decrease of the single-strand DNA breaks level in spleen cells in 2.3 times (p < 0.001) and blood leukocytes in 6.1 times (p < 0.01), a decrease of the apoptotic cells frequency in 1.3 times (p < 0.05) and an increase in the spleen relative mass ratio B 1.2 times (p < 0.001) in CBA mice offspings (F1) from the chronically irradiated parents and exposed to chronic irradiation during the embryonic and postembryonic periods. A hypothesis about the more compact chromatin structure of blood system cells in the individuals of the first generation from chronically irradiated mice is proposed.     

The effect of chronic exposure to 835.62 MHz FDMA or 847.74 MHz CDMA radiofrequency radiation on the incidence of spontaneous tumors in rats

This study was designed to determine whether chronic exposure to radiofrequency (RF) radiation from cellular phones increased the incidence of spontaneous tumors in F344 rats. Eighty male and 80 female rats were randomly placed in each of three irradiation groups. The sham group received no irradiation; the Frequency Division Multiple Access (FDMA) group was exposed to 835.62 MHz FDMA RF radiation; and the Code Division Multiple Access (CDMA) group was exposed to 847.74 MHz CDMA RF radiation. Rats were irradiated 4 h per day, 5 days per week over 2 years. The nominal time-averaged specific absorption rate (SAR) in the brain for the irradiated animals was 0.85 +/- 0.34 W/kg (mean +/- SD) per time-averaged watt of antenna power. Antennas were driven with a time-averaged power of 1.50 +/- 0.25 W (range). That is, the nominal time-averaged brain SAR was 1.3 +/- 0.5 W/kg (mean +/- SD). This number was an average from several measurement locations inside the brain, and it takes into account changes in animal weight and head position during irradiation. All major organs were evaluated grossly and histologically. The number of tumors, tumor types and incidence of hyperplasia for each organ were recorded. There were no significant differences among final body weights or survival days for either males or females in any group. No significant differences were found between treated and sham-exposed animals for any tumor in any organ. We conclude that chronic exposure to 835.62 MHz FDMA or 847.74 MHz CDMA RF radiation had no significant effect on the incidence of spontaneous tumors in F344 rats.     

Study of genome instability using DNA fingerprinting of the offspring of male mice subjected to chronic low dose gamma irradiation

By a polymerase chain reaction with an arbitrary primer (AP-PCR), the possibility of transmission of genome instability to somatic cells of the offspring (F1 generation) from male parents of mice exposed to chronic low-level gamma-radiation was studied. Male BALB/c mice 15 days after exposure to 10-50 cGy were mated with unirradiated females. Biopsies were taken from tale tips of two month-old offspring mice and DNA was isolated. The primer in the AP-PCR was a 20-mer oligonucleotide flanking the microsatellite locus Atp1b2 on chromosome 11 of the mouse. A comparative analysis of individual fingerprints of AP-PCR products on DNA-templates from the offspring of irradiated and unirradiated male mice revealed an increased variability of microsatellite-associated sequences in the genome of the offspring of the males exposed to 25 and 50 cGy. The DNA-fingerprints of the offspring of male mice exposed to chronic irradiation with the doses 10 and 25 cGy 15 days before fertilization (at the post-meiotic stage of spermatogenesis) showed an increased frequency of "non-parent bands". The results of the study point to the possibility of transmission to the offspring somatic cells of changes increasing genome instability from male parents exposed to chronic low-level radiation prior to fertilization.     

Persistent induction of somatic reversions of the pink-eyed unstable mutation in F1 mice born to fathers irradiated at the spermatozoa stage

Untargeted mutation and delayed mutation are features of radiation-induced genomic instability and have been studied extensively in tissue culture cells. The mouse pink-eyed unstable (p(un)) mutation is due to an intragenic duplication of the pink-eyed dilution locus and frequently reverts back to the wild type in germ cells as well as in somatic cells. The reversion event can be detected in the retinal pigment epithelium as a cluster of pigmented cells (eye spot). We have investigated the reversion p(um) in F1 mice born to irradiated males. Spermatogonia-stage irradiation did not affect the frequency of the reversion in F1 mice. However, 6 Gy irradiation at the spermatozoa stage resulted in an approximately twofold increase in the number of eye spots in the retinal pigment epithelium of F1 mice. Somatic reversion occurred for the paternally derived p(un) alleles. In addition, the reversion also occurred for the maternally derived, unirradiated p(un) alleles at a frequency equal to that for the paternally derived allele. Detailed analyses of the number of pigmented cells per eye spot indicated that the frequency of reversion was persistently elevated during the proliferation cycle of the cells in the retinal pigment epithelium when the male parents were irradiated at the spermatozoa stage. The present study demonstrates the presence of a long-lasting memory of DNA damage and the persistent up-regulation of recombinogenic activity in the retinal pigment epithelium of the developing fetus.     

The adaptive response of first generation offsprings irradiated parents

In offspring's of first generation irradiated inhabitants of Techa river (fathers, mothers and both parents) the spontaneous level of damaged blood lymphocytes, sensitivity of lymphocytes to the additional acute irradiation in dose 1.0 Gy and radioinduced adaptive response after adaptive (5 cGy) and challenge (1.0 Gy) irradiation 5 h after was studied. The micronuclei test with cytochalasin B as a criteria of the effect have been used. It was shown, that descendents of irradiated parents differ from the control group. The main difference is the significant decrease of the adaptive response frequency in the progeny. In the offspring's of the irradiated fathers and mothers there is no one individuals with the adaptive response; in the offspring's of both irradiated parents the frequency of individuals with adaptive response decreases in control from 19.5% to 6.8%. The distribution of descendents according to response on adaptive irradiation differ significantly from the control distribution and from the each other. And the tendency to the radiosensitivity increase after adaptive irradiation was observed. In the whole joint group of progeny the mean spontaneous cell frequency with micronuclei decreased, but the sensitivity of lymphocytes to the additional acute irradiation doesn't differ from the control. The results of the paper permit to suppose that transgenerational genome instability in human can be determined. Earlier discovered decrease of the adaptive response frequency in the Techa river livings is observed in the offspring's of irradiated fathers, mothers and both parents.     

Elevated Micronucleus Frequency in Bone Marrow Erythrocytes in the Progeny of Male Mice Exposed to Chronic Low-Dose Gamma Irradiation

The micronucleus frequency in bone marrow erythrocytes from the F1 progeny of male mice exposed to chronic low-dose -irradiation was determined. Male BALB/c mice were irradiated with 10, 25 and 50 cGy at dose rates of 1, 5, and 15 cGy/day and mated with unirradiated females on day 15 after irradiation. The obtained offspring had an elevated micronucleus frequency in bone marrow erythrocytes at the age of 2 months. This suggests the transmission of genome instability from damaged germ-line cells of irradiated male parents to somatic cells of the progeny.     

Radiation-induced and embryotoxic effects in experimental hyperthyroidism

The purpose of this article was investigation the development of the posterity rat (line Wistar) in the postnatal ontogenesis after combined and separate action of gamma-radiation (1.25 Gy at 20 days) and hyperthyroidism, provoked by toxic thyroid doses of 100 mg thyroidin per rat. It was shown that hyperthyroidism did not affect physical development of the irradiated posterity, but in a long-time period (7 month) it was revealed a decrease in ability to the training of posterity rats after the combined action of the factors.     

Influence of the age of the recipient on the manifestation of the effect of allogeneic inhibition]

The expression of allogenic inhibition was studied when transplanting 10(5) cells of bone marrow of C57BL mice to the lethally irradiated recipients (CBA X C57BL) F1 of different age (2 to 11 months). In the control experiments the bone marrow cells at the same dose were introduced to the lethally irradiated syngenic (C57BL) mice. The most pronounced inhibition of the parental stem cells proliferation was registered in 2 months old recipients F1 (4.7 times), it was somewhat weakened in 3 months old and animal in 4--11 months old recipients (1.1 to 1.8 times). The thymectomy of adult recipients F1 did not eliminate the expression of allogenic inhibition.     

Interactions between B lymphocyte subpopulations. Augmentation of the responses of resting B lymphocytes by activated B lymphocytes

Mouse B lymphocytes were fractionated from normal T lymphocyte-depleted spleen cell populations using discontinuous percoll gradients and were stimulated with rabbit F(ab')2 anti-mouse mu-specific antibodies (anti-mu) plus the supernatant of Con A-stimulated rat spleen cells (SN) as a source of lymphokines. The responses of small (mean volume 120 mu 3), dense (greater than 1.087 specific gravity), resting (least spontaneous thymidine incorporation) B lymphocytes were augmented by irradiated (4000 rad), larger (mean volume greater than 170 mu 3), less dense (less than 1.081 specific gravity), activated (greater spontaneous thymidine incorporation) B lymphocytes. Proliferation was augmented 2- to 4-fold and polyclonal antibody-forming cell responses three- to sixfold. Maximal augmentation of the responses of 5 X 10(4) resting B cells was obtained with 10(4) activated B cells. Augmenting activity was specific for activated B lymphocytes in that responses were not augmented by irradiated thymocytes, T lymphoblasts, macrophages, or additional supernatant. B lymphocytes activated in vitro by LPS or anti-mu also had augmenting activity. Augmentation of responses was maximal only when activated B lymphocytes were added simultaneously with anti-mu. The interaction between activated and resting B lymphocytes did not appear to be genetically restricted. Interestingly, the augmenting activity of activated B cells could be reconstituted by a combination of supernatant and cell membranes from these cells but not by either alone, suggesting that two components are required, one soluble and the other membrane-bound. Thus, a functional interaction has been demonstrated between B lymphocyte subpopulations which differ in their state of activation, and this interaction appears to involve a novel mechanism of action.     

Thiamine prevents X-ray induction of genetic changes in human lymphocytes in vitro

The effects of thiamine (vitamin B1) on the level of spontaneous or radiation-induced genetic changes in human lymphocytes in vitro were studied. Cultured lymphocytes were exposed to increasing concentrations of thiamine (0-500 microg/ml) and irradiated with X-rays. The DNA damage was estimated as the frequency of micronuclei and apoptotic or necrotic morphological changes in fixed cells. The results show that thiamine alone did not induce genetic changes. A significant decrease in the fraction of apoptotic and necrotic cells was observed in lymphocytes irradiated in the presence of vitamin B1 at concentrations between 1-100 microg/ml compared to those irradiated in the absence of thiamine. Vitamin B1 at 1 and 10 microg/ml decreased also the extent of radiation-induced formation of micronuclei. Vitamin B1 had no effect on radiation-induced cytotoxicity as measured by nuclear division index. The results indicate that vitamin B1 protects human cells from radiation-induced genetic changes.