Frequency Of Dominant Lethal Mutations Research Articles

Genotoxic and mutational potential of monocyclic terpenoids (carvacrol, carvone and thymol) in Drosophila melanogaster.

Genotoxicity and mutagenicity of monoterpene carvone along with the related monoterpene alcohols - carvacrol and thymol have been studied using Drosophila melanogaster as model system. The viability, pre-imaginal stage duration, level of dominant lethal mutations, unequal crossover in the Bar mutant of D. melanogaster and the influence of monocyclic terpenoids on the multiplication of the nuclear genome in salivary gland cells were investigated. The compounds tested after oral administration (0.02% in 1,2-propylene glycol) influence the degree of chromosome polyteny in salivary gland cells of D. melanogaster larvae. Among the terpenoids examined, carvacrol exhibited the most significant impact on imago lifespan, frequency of dominant lethal mutations, unequal crossover in the Bar mutant when added to the culture medium. Oral administration of terpenoids increases the average level of chromosome polyteny with the highest value for carvacrol - 1178C compared to control (776C). The conceivable mechanism of action for monocyclic terpenoids associated with the impact on juvenile hormone activity is debated.

Inbreeding effects in Drosophila congenic strains: the influence of genetic background of different origin

Aim. To compare reproductive indices and stress resistance of Drosophila at outbreeding and inbreeding. Methods. Drosophila melanogaster congenic strains with incomplete development of the radial wing vein – radius incompletus – were used: the laboratory one and the strain, in which the mutation was placed into the genetic background of wild type strain, which originates from the natural population from radiation contaminated territory. Before the experiment strains have passed 65 generations of inbreeding. Viability (number of individuals, pupa stage mortality), dominant lethal mutations frequency and life span of imago at starvation were analysed. Results. After inbreeding, there was a decrease in the frequency of dominant lethal mutations and an increase in viability of the strain, which originates from the natural population, and a decrease of mortality at the pupal stage in both strains. Decreased life span of imago at starvation has been shown only for the inbred strain, which originates from the natural population. Conclusions. Inbreeding for 65 generations has no significant negative effect on reproductive indices; reduction of stress resistance during inbreeding has been shown only for the strain, which originates from the radiation contaminated territory. 
 Keywords: Drosophila, viability, dominant lethal mutations, life span of imago at starvation, inbreeding.

Involvement of DNA Repair Genes and System of Radiation-Induced Activation of Transposons in Formation of Transgenerational Effects.

The study of the genetic basis of the manifestation of radiation-induced effects and their transgenerational inheritance makes it possible to identify the mechanisms of adaptation and possible effective strategies for the survival of organisms in response to chronic radioactive stress. One persistent hypothesis is that the activation of certain genes involved in cellular defense is a specific response of the cell to irradiation. There is also data indicating the important role of transposable elements in the formation of radiosensitivity/radioresistance of biological systems. In this work, we studied the interaction of the systems of hobo transposon activity and DNA repair in the cell under conditions of chronic low-dose irradiation and its participation in the inheritance of radiation-induced transgenerational instability in Drosophila. Our results showed a significant increase of sterility and locus-specific mutability, a decrease of survival, fertility and genome stability (an increase the frequency of dominant lethal mutations and DNA damage) in non-irradiated F1/F2 offspring of irradiated parents with dysfunction of the mus304 gene which is responsible for excision and post-replicative recombination repair and repair of double-stranded DNA breaks. The combined action of dysfunction of the mus309 gene and transpositional activity of hobo elements also led to the transgenerational effects of irradiation but only in the F1 offspring. Dysfunction of the genes of other DNA repair systems (mus101 and mus210) showed no visible effects inherited from irradiated parents subjected to hobo transpositions. The mei-41 gene showed specificity in this type of interaction, which consists in its higher efficiency in sensing events induced by transpositional activity rather than irradiation.

Toxic effect and genotoxicity of carvacrol ethers in Drosophila melanogaster

The present study investigated the effect of four carvacrol ethers (propyl-, butyl, octyl- and benzyl) on the viability, level of dominant lethal mutations of Drosophila melanogaster and their influence on the multiplication of the nuclear genome in salivary gland cells. The fertility and viability of fruit flies were assessed after oral administration (0.05 % to culture medium) and inhalation exposure (5 mg per 1 cm2 of polyvinyl alcohol film) of compounds 1‒4 and initial carvacrol. The influence of terpenoid and its ethers on the degree of chromosomes polyteny in salivary gland cells of D. melanogaster larvae has been revealed. Among all tested compounds, carvacrol exhibited the most significant impact on frequency of dominant lethal mutations, fecundity and insect survival when inhaled or adding to the culture medium. Oral administration of ethers 1‒4 was found to decrease the average level of chromosome polyteny degree (366 C–500 C) while pure carvacrol adding to culture medium had the opposite effect (763 C) compared to control (695 C). The possible mechanism of action for carvacrol and its ethers is discussed.

Mutations rate in different lines of drosophila melanogaster after the treatment with caffeine and He-Ne laser radiation

The frequency of dominant lethal mutations (DLM) after combined effect of caffeine (1,3,7-trimethylxan- thine) and helium-neon laser radiation in Drosophila has been studied. Caffeine is a natural substance which is presented in many drinks, widely applied in medicine and reveals moderately toxic action and some mutagen- icity/genotoxicity effects; red laser radiation is applied in medicine and can disrupt the processes of DNA and RNA biosynthesis. The aim of this work was to study the characteristics of the mutation process in Drosophila melanogaster under the influence of caffeine and red laser radiation, depending on the genotype. We used wild type Drosophila melanogaster stocks Canton-S (C-S) and Oregon (Or), carrying an ebony mutation, respectively: ebonyC-S and ebonyOr; and mutant stock ebony. Control flies were grown in standard conditions, and in experiments with caffeine it was added in culture medium in concentration 0.5 mg/ml. Vir- gin flies were exposed to a helium-neon laser light (wavelength of 632,8 nm) with a surface power density of 0.03 mW/cm2, the exposure time was 5 minutes. The influence of caffeine causes an increase in the frequency of early DLM on 40 % in mutant line ebony, and on 70.5 % in the line ebonyC-S. Irradiation by light of helium-neon laser either reduces the incidence DLM, or has no effect in all lines used in this work. The simultaneous effect of two external factors induces diverse answers in different genotypes: it increases early DLM in line C-S and early and late DLM in line ebony; but has no effect in lines ebonyOr and ebonyC-S. The two-way analysis ANOVA F-test showed that the DLM frequency dependence impact of external factors is characterized by F= 3.87; of genotype F= 5.14; of the combined effects of genotype and external factors F = 5.69. The power of influence of external factors — 8.1 %; of genotype 6.9 %; and of the combined effects of the genotype and two external factors studied — 31.4 %. Conclusions. Irradiation with laser light had no mutagenic effect on Drosophila, and even revealed anti- mutagenic effect. Caffeine induced the DLM increase, but the combined caffeine and laser light impact increased DLM rate in line ebony and not influenced it in lines: ebonyOr and ebonyC-S.

Analysis of embryonic mortality frequency in Drosophila melanogaster stocks with radius incompletus mutation under inbreeding conditions

It is known that inbreeding leads to homozygotization of alleles of the most genes. The rate of this process is determined by the degree of kinship between crossed individuals. In addition, inbred breeding is accompanied by a change in the structure and functioning of the genome of cells of females’ generative system: mutational level increases and oogenetic segregation may be violated. This leads to a decrease in the number of laid eggs and an increase in the level of embryonic mortality. This process, described as "the effect of resistance to selection," is aimed at adapting to external conditions and associated with the selection of viable offspring. The character of manifestations of mutational variability is determined to a large extent by the direction of selection. However, up to now our knowledge of the role of the genotype in controlling the level of embryonic mortality in Drosophila melanogaster stocks in conditions of inbred breeding is not deep enough. The purpose of our work was to analyze the frequency of dominant lethal mutations in Drosophila stocks from radiation-contaminated regions of Ukraine (Polesskoe and Ozero), carrying radius incompletus mutation, depending on the degree of inbreeding. It is shown that under conditions of severe inbreeding (without selection) changes in the total frequency of dominant lethal mutations have a cyclic character, which depends on the genotype of the stocks. So, in radius incompletus stock, the indicator studied increases after 10 generations of selection and remains at enough high level for 20 generations. For the stocks from radiation-contaminated territories of Ukraine with radius incompletus mutation, which are contrasting in the level of embryonic mortality, two decrease peaks are shown (for the stock ri(Oz) – after 5 and 65 generations of inbreeding) and an increase (for the line ri(Pol) – after 5 and 32 generations of inbreeding) of the total frequency of dominant lethal mutations. The main factor influencing the change in the mortality level at the stage of early embryogenesis in Drosophila carrying radius incompletus mutation is the genotype of the stocks that are used in the work. It’s contribution increases after 10 (h2gen=44.78), 15 (h2gen=45.86) and 100 (h2gen=46.36) generations of inbreeding. The effect of inbred breeding was observed after 32 (h2inbr=22.61) and 65 (h2inbr=11.89) generations. The combined effect of both factors on the total frequency of dominant lethal mutations is shown for each of the generations studied. The highest values were shown after the 5th (h2comb=53.86) and the 65th (h2comb =40.63) generations of inbred breeding.

Effects of microwaves on the puffing pattern of D. melanogaster

Abstract The influence of electromagnetic field exposure on puffing pattern of salivary gland polythene chromosomes, viability and fertility of Drosophila melanogaster of the wild type Canton-S line was studied. Experimental conditions: Electromagnetic field characteristics: frequency — 36.64 GHz, power density — 0.4 W/m2, exposure time −10 seconds. Electromagnetic field exposure was conducted on the egg stage. Results: in larvae developed from the exposed eggs 3 of 8 chromosomal puffs tested (71CE, 82EF, and 83E) had significantly smaller dimensions than these in control at the prepupal stage. Viability of Drosophila estimated by the number of adult flies hatched from exposed eggs decreased, while the number of dominant lethal mutations increased. Conclusion: the exposure to a low-level microwave irradiation suppressed puffing activity at ecdysone-inducible loci of Drosophila polythene chromosomes, increased frequency of dominant lethal mutations and decreased Drosophila viability but did not influence Drosophila fertility.

Genetic Effects Induced by Nickel Sulfate in Germline and Somatic Cells of WR Mice

We examined the effects of nickel sulfate at doses 0.5 to 5.0 mg/kg (LD50) on the frequency of dominant lethal mutations and two-strand DNA breaks (TSBs) in germline cells and on an increase in frequency in gene mutations W(y) in pigment cells of first-generation mice. The results indicated that spermatogenesis stages most sensitive to nickel sulfate (at a dose of 1.0 mg/kg) are spermatozoids, early spermatids, late spermatocytes, and stem spermatogonia. No statistically significant increase in the total TSB level was detected in spermatozoids 4 weeks after exposure. At the same time, a significant (P < 0.05) increase in percentage of cells with an extremely high level of DNA fragmentation (supposedly apoptotic cells) was observed upon exposure at a dose of 0.5 mg/kg. Nickel sulfate at doses of 5.0 and 1.0 mg/kg induced a marked increase in the c-kit gene expression in pigment cells of heterozygous first-generation WR mice as compared to control (P < 0.001). It was shown that the nonobservable adverse effect level (NOAEL) of nickel sulfate on the dominant lethal mutation frequency and gene mutations was 1/200 LD50, while the lowest observable adverse effect level (LOAEL) was 1/100 LD50.

Indraline Radioprotective Effect against Genetic Damage in Mice

The effect of indraline on frequency of dominant lethal mutations induced by radiation in germ cells, reciprocal translocations, and testicle weight of male mice. The level of protective effect against genetic damage varied depending on the radiation dose and spermatogenesis stage. The values of the defense coefficient ranged from 0.15 to 0.35.

Sperm head abnormalities and dominant lethal effects of formaldehyde in albino rats

The effects of formaldehyde exposure have been investigated in rats by two short-term in vivo mutagenicity tests (sperm head abnormality and dominant lethal mutation assays). Five daily interperitonial injections of formaldehyde resulted in a statistically significant increase in induction of sperm head abnormalities at 0.125 to 0.500 mg/kg. The frequency of dominant lethal mutations in female rats sired by males exposed to formaldehyde was significantly higher than the control group. There was also a reduction of fertile matings in females mated 1–7 days after treatment of males with formaldehyde. The genetic and environmental health implications of the results are discussed.

Genotoxicity assessment of the antifungal antibiotic aureofungin in Salmonella typhimurium and Swiss albino mice

The widely used agricultural antifungal agent aureofungin (ARF) was subjected to genotoxicity assessment using the Ames Salmonella assay as well as the in vivo micronucleus test and dominant lethal test in Swiss mice. In the Ames Salmonella spot test, ARF slightly elevated the number of histidine revertants after metabolic activation over a wide dose range (1–1000 μg/plate) in TA102 but not in TA97a, TA98 or TA100. In the preincubation plate incorporation assay with TA102, ARF increased the number of revertants in a dose-dependent manner only after metabolic activation. ARF failed to significantly elevate the frequency of micronucleated polychromatic erythrocytes (PE) in the bone marrow of Swiss mice. It elevated the frequency of dominant lethal mutations in the 7th and 8th weeks at 30 mg/kg body weight, a concentration much higher than the actual concentration used in the field. We conclude that ARF is non-mutagenic in somatic cells in vivo at doses used in the present study, probably mutagenic in stem-cell spermatogonia and may be classified as an equivocal promutagen, possibly acting as a cross-linker.

Tritium radiobiological effects in mammals: review of experiments of the last decade in Russia.

This review briefly describes techniques and basic results of experimental investigations in mice and rats on metabolism, dosimetry, and radiobiological effects of tritium oxide and some tritiated biogenic compounds (glucose, amino acids, and nucleosides) during the last 10 to 15 years in Russia. The content of water in tissue cells of mammals is shown to be 15 to 40% less than in whole tissue. The kinetics of tritium incorporation from oxide (HTO) and its retention in DNA of hemopoietic tissues were studied. The contribution of bound tritium to dose strongly depends on the chemical form of tritium and reaches 90% when labeled L-lysine is injected. Specific features of the action of HTO on hemopoietic tissue were investigated in tests of damage and repair of DNA, induction of chromosome aberrations in cells, content of nucleic acids, kinetics of cell populations, immunity parameters, carcinogenesis, decrease of life span, induction of dominant lethal mutations in germ cells in male mice, and reciprocal translocations in mouse spermatogonia. According to these tests, the radiobiological effects of tritium beta radiation in the form of oxide is 2 to 6 times higher than for gamma radiation of 137Cs. The frequency of dominant lethal mutations induced by labeled lysine, thymidine, and deoxycytidine is 3 to 12 times higher than those induced by equal HTO activity. The results of these investigations are used to standardize HTO and the various biogenic compounds of tritium, improve techniques of indirect dosimetry, provide medical aid to personnel, and estimate population risk.

Evaluation of the co-mutagenicity of ethanol and Δ 9-tetrahydrocannabinol with Trenimon

The mutagenic potential of chronic treatments of male CF-1 mice with ethanol and Δ 9-tetrahydrocannibinol (THC), and their comutagenic potential with a known mutagenic agent, Trenimon, were examined. This was accomplished by measuring the frequency of dominant lethal mutations arising from mating of treated males with nontreated females. Adult male mice were treated with 5% (v/v) ethanol as part of a liquid diet (28% ethanol-derived calories) for five weeks; 10 mg/kg body weight (p.o.) THC every two days for five weeks; a single injection of Trenimon (0.125 mg/kg, i.p.) on day 28 of diet treatment; and all combinations of treatments. The control group was pair-fed a liquid diet in which isocaloric sucrose replaced ethanol; these males were also given sesame oil (vehicle for THC) and saline (vehicle for Trenimon) on the same schedule as that for the treated males. Neither body weights nor hematocrits were adversely affected by any treatment. Both ethanol and Trenimon treatments resulted in a small (8–9%; p < 0.05) decrease in testicular weight. The effect of combined treatment with ethanol and Trenimon was roughly additive. Treatment with THC had no effect on testicular weight. Seminal vesicle weights were not affected by any treatment. Treatments were without significant effect on fertility, as measured by the frequency of males producing pregnancies. Ethanol and Trenimon treatments produced approximately 3- and 7-fold increases, respectively in the frequencies of preimplantational loss over that seen for the control group (7.3%), resulting in significant ethanol and Trenimon effects ( p < 0.001). No interactive effects of ethanol and Trenimon treatments were noted. Frequencies of dead fetuses per pregnancy in the ethanol- and Trenimon-treated groups were increased approximately 2.5- and 4-fold, respectively, over the control value of approximately 16%. However, the effect of combined treatments was not greater than that due to Trenimon alone, resulting in Trenimon and ethanol effects (p < 0.001) and ethanol-Trenimon interaction (p < 0.001). The calculated mutation index resulting from each treatment yielded significant ( p < 0.001) ethanol- and Trenimon-induced effects. In contrast to effects of ethanol and Trenimon treatments, THC, given alone, or in combination with ethanol and/or Trenimon. had no effect on either preimplantational loss, fetal mortality or the resulting mutation index. The data suggest that chronic ethanol treatment, at levels resulting in minimal fertility impairment, increases the frequency of dominant lethal mutations. In contrast, chronic treatment with THC. as administered in the present study, appears to be without effect. Neither ethanol nor THC was comutagenic with Trenimon.

Induction of specific-locus mutations in male mice by ethyl methanesulfonate (EMS)

Using a sequential mating procedure, the induction of specific-locus mutations by ethyl methanesulfonate (EMS) was reinvestigated in male mice. Doses of 175 mg/kg b.w. and 250 mg/kg b.w. of EMS induce gene mutations in the mating intervals 5–8 and 9–12 days post treatment. However, only the frequency of dominant lethal mutations increases with the dose, not the frequency of specific-locus mutations. This observation implies that with a higher dose of EMS a larger fraction of mutagenized spermatozoa and spermatids are selectively eliminated, leading to underestimation of the specific-locus mutation yield at high doses. EMS does not induce specific-locus mutations in spermatogonia.

Genetic effects of 131I in reproductive cells of male mice

A study was made of the frequencies of dominant lethal mutations (DLM) in pre- and post-meiotic germ cells, reciprocal translocations (RT) in spermatogonia and abnormal sperm heads (ASH) induced by a single intraperitoneal administration of Na 131I with an activity of 1.48–740 kBq/g to male mice. The frequency of DLM was shown to increase only when postmeiotic cells were exposed to the radionucleide. The RT frequency increased insignificantly with increases in the dose of 131I. The ASH frequency increased only when maximal doses of 131I were administered. The relative biological efficiency (RBE) of 131I with reference to the indices under study is less than 1.

Effect of total doses and dose rates of γ-rays on the frequency of dominant lethal mutations (DLM) induced in mouse stem spermatogonia

Effect of total doses and dose rates of γ-rays on the frequency of dominant lethal mutations (DLM) induced in mouse stem spermatogonia

Studies on the mutagenic effect of contraceptive drugs I. Induction of dominant lethal mutations in female mice

30 adult virgin female mice (2 strains) received either high or low doses of Anovlar or Lyndiol oral contraceptives and were tested for induction of dominant lethal mutations. The pregnant mice were dissected on Day 14 of pregnancy and total implantations, early deaths, late deaths, and corpora lutea were counted in each pregnancy. A significant reduction in fertile mating (p .025) was found in 1 strain of those who received the high dose of Lyndiol (10 times that of the low dose, which is physiologically equivalent to the human dose). This dose also increased the number of dead implants in both strains which resulted in higher estimates of dominant lethal mutations. It is concluded that when Lyndiol and Anovlar were given at the physiological dose level to control ovulation in mice, the frequency of dominant lethal mutations was not increased above the control level.

Comparison of radiation- and chemically-induced dominant lethal mutations in male mice

Ionizing radiation-induced dominant lethal mutations in all spermatogenic stages. After irradiation of male mice with 200 R the yield of induced mutations in early spermatids was twice the yield in spermatozoa, late spermatids, and spermatocytes. After irradiation with 400 R or 800 R the spermatocytes were the most sensitive stage for the induction of dominant lethal mutations. The frequency of radiation-induced dominant lethal mutations in postspermatogonial stages was dose-dependent. The yield of dominant lethal mutations in spermatogonia was independent of the dose. Pretreatment with chloramphenicol enhanced the frequency of radiation-induced dominant lethal mutations only in spermatozoa. Pretreatment with S,2-aminoethylisothiuronium · Br · HBr (AET) reduced the frequency of radiation-induced dominant lethal mutations in early spermatids. Chemically mutagens can be characterized by their stage-specific induction of mutations. The straight chain alkyl methanesulfonates ethyl methanesulfonate (EMS), methyl methanesulfonate (MMS) and n-propyl methanesulfonate (PMS) induced a high frequency of dominant lethal mutations in spermatozoa and late spermatids. The induced dominant lethal mutation rate decreased to the control level of embryonic lethality in early spermatids. No mutations were induced in spermatocytes. The absence of induced mutations in spermatozoa and late spermatids was typical for the spermatogenic response after treatment with mytomycin C. Mutations were induced in early spermatids. Spermatocytes were the most sensitive germ-cell stage for the induction of dominant lethal mutations with mitomycin C. Possible explanations for the differential spermatogenic response to radiation- and chemically-induced dominant lethal mutations are discussed.

Induction of dominant lethal mutations by alkylating agents in male mice

Methyl methanesulfonate (MMS) and ethyl methanesulfonate (EMS) induced a high frequency of dominant lethal mutations in mouse spermatozoa of vas and epididymis, testicular sperm, and late spermatids, and a low frequency in early spermatids. In an equimolar dosage, MMS is about 4 times more effective than EMS in inducing dominant lethal mutations in these cell stages. Neither N-methyl- N′-nitro- N-nitrosoguanidine (MNNG) nor 2-methoxy-6-chloro-9-[3-ethyl-2-chloroethyl)amino propylamino]acridine dihydrochloride (ICR-170) induced dominant lethal mutations in spermatozoa of vas and epididymis, testicular sperm, or spermatids. These results are in good agreement with the expected effect of the chemicals based on work with microorganisms.

Embryonic Lethality of Various Mouse Strains as a Consequence of X-Irradiation-Induced Injuries of the Father's Spermatozoa

It would also be of interest to investigate whether there is a difference between strains with regard to the induction of mutations. The simplest method of determining this would be to study the frequency of dominant lethal mutations caused by irradiation in the spermatozoa. The present investigation has therefore been limited to a study of this type of mutation, expressed as an increased mortality among F1 fetuses.