Mutagenic Factors Research Articles

Mutation Breeding and Its Importance in Modern Plant Breeding: A Review

A mutation is an abrupt, heritable alteration in a living cell's DNA that is not brought about by genetic recombination or segregation. The deliberate use of mutations in plant breeding is known as "mutation breeding." Mutation breeding provides the advantage of improving a fault in an otherwise excellent cultivar without sacrificing its agronomic and qualitative features, in contrast to hybridization and selection. There is no simpler solution than mutation breeding to enhance seedless crops. These benefits have led to the development of a market for mutation breeding in plant breeding since the initial release of mutant cultivars derived from fundamental mutation research in Europe. Both physical and chemical mutagens have improved methods for inducing mutations in major crops, and strategies for selecting mutant populations have been detailed. A broad range of mutations that have not been previously documented have been detected, and new mutagenic factors like cosmic rays and ion beam radiation are being studied. However, ionising radiation and alkylating chemicals continue to be widely used. The efficiency of mutant breeding has increased as a result of the advent of reliable in vitro methods for numerous crop species. In vitro methods are particularly effective because they can manage sizable mutagenized populations in a small area, have a quicker progeny turnover rate in vegetatively propagated species, and can screen for a variety of biotic and abiotic stress factors in the culture environment. Over the last ten years, there have been significant advancements in mutant screening, with reverse genetic methods now being prioritised. Thus, the combination of molecular methods and mutation techniques is opening up new and intriguing possibilities for contemporary plant breeding.

CRISPR/Cas9 as a Mutagenic Factor.

The discovery of the CRISPR/Cas9 microbial adaptive immune system has revolutionized the field of genetics, by greatly enhancing the capacity for genome editing. CRISPR/Cas9-based editing starts with DNA breaks (or other lesions) predominantly at target sites and, unfortunately, at off-target genome sites. DNA repair systems differing in accuracy participate in establishing desired genetic changes but also introduce unwanted mutations, that may lead to hereditary, oncological, and other diseases. New approaches to alleviate the risks associated with genome editing include attenuating the off-target activity of editing complex through the use of modified forms of Cas9 nuclease and single guide RNA (sgRNA), improving delivery methods for sgRNA/Cas9 complex, and directing DNA lesions caused by the sgRNA/Cas9 to non-mutagenic repair pathways. Here, we have described CRISPR/Cas9 as a new powerful mutagenic factor, discussed its mutagenic properties, and reviewed factors influencing the mutagenic activity of CRISPR/Cas9.

Study of antimutagenic activity of medicinal plant infusions Crataegus sanguinea Pall. family Rosaceae in plant test systems

Medicinal plants, integral to traditional medicine systems, are rich sources of biologically active substances that benefit physiological and biochemical processes within living organisms. Amongst these activities, antimutagenic and genoprotective properties stand out, offering mitigation against genotoxic effects induced by adverse environmental factors on genetic material. This study delves into the mutagenic and antimutagenic capacities of aqueous and alcoholic infusions derived from Crataegus sanguinea Pall. (Rosaceae family), utilising Hordeum vulgare L. as a plant-based test subject. The assessment employed the metaphase chromosome analysis technique. Results indicate that these infusions exhibit no mutagenic activity, with the level of chromosomal aberrations in barley seeds treated with these infusions not exceeding the natural mutation rate in a statistically significant manner. When infusions were combined with Methyl methanesulfonate (positive control) exposure – irrespective of exposure sequence – a statistically significant attenuation in MMS-induced mutagenesis was observed (p<0.01). A 56-60% reduction quantified the antimutagenic efficacy of C.sanguinea infusions. This metric underscores the infusions’ capability to inhibit MMS-induced mutagenesis by 50–60%, positioning these water and alcohol-based extracts of common hawthorn as viable candidates for safeguarding against chemically induced mutagenic factors.

Prediction of the breeding value of leaf lettuce mutant lines according to the correlation between the manifestation of qualitative and quantitative traits

Aim. To establish the effect of mutagenic factors on the formation of qualitative traits, defining the phenotype of the leaf blade, and to investigate the correlation between the manifestation of these factors and the variation of quantitative traits of breeding value in mutant lines of leaf lettuce. Methods. Non-parametric statistical and criteria of difference for biological specimens, computational and analytical calculations, correlation analysis. Results. The comparative analysis was conducted on the qualitative characteristics of the original leaf blade form of leaf lettuce, Zhnych variety, alongside 14 mutant lines derived from it through the application of mutagenic agents, including dimethyl sulfate (DMS) and its derivatives (D3MU, DMU-10А, and DMU-9) in two varying concentrations. Notably, the derivatives of DMS exhibited superior mutagenic efficiency, leading to a four to fivefold increase in the number of mutant plant forms compared to the reference compound DMS. Among the derivatives, D3MU proved the most effective, generat- ing five mutant lines. In contrast, DMU-10A and DMU-9 yielded four mutant lines, while DMS produced only one mutant line. All mutant lines exhibited distinct variations from the initial form across 17 qualitative characteristics determining leaf blade phenotype. The analysis of Spearman’s rank correlation coefficient (rs) demonstrated weak to moderate correlation (rs = –0.08...0.62) between the original form and mutant lines. It was determined that three lettuce lines, namely B-7, B-22, and B-38, exhibited the most significant deviations from the initial form in term of leaf blade qualitative traits. Furthermore, it was established that non-parametric indicators of qualitative traits expression exhibited moderate or high correlation (rs = 0.57...0.74) with an essential quantitative trait – the duration from the emergence of mass shoots to plant stem development in mutant lines. Conclusions. The identified correlations between quantitative and qualitative traits provide the opportunity to predictably select mutant genotypes with extended growth period during the early stages of lettuce plant ontogenesis in future breeding work.

Cytogenetic activity of a mutagenic factor with high damaging capacity in winter wheat

The analysis of cytological abnormalities is an important method for identifying the potential of a chemical as a mutagen for future heritable genetic changes, the level of genotype-mutagen interaction and site-specific activity for the nature and/or different concentrations of the mutagen. The research aims to determine the limits of the variability of genotypes of different origins, especially those with wide ecological and genetic variability, and to show the interaction between the variety and the mutagen. Winter wheat grains of several varieties (Balaton, Borovytsia, Zelenyi Hai, Zoloto Ukrainy, Kalancha, Niva Odeska, Polianka, Pochayna) were treated with dimethyl sulphate at concentrations of 0.0125%, 0.025%, 0.05%, and exposure was 24 hours. The cytogenetic activity was studied by the frequency and spectrum of chromosomal rearrangements in the corresponding phases of cell division, depending on the variety and concentration of the mutagen as the main factors affecting these parameters, as well as the main features of the spectrum, such as the overall rate of chromosomal rearrangements, the number of fragments and double fragments, bridges, micronuclei, and lagging chromosomes. The studied concentrations of the supermutagen were found to have a significant effect on all analysed parameters and can be classified as optimal and high concentration levels in terms of the effect on cytological activity and mitotic problems for the factor, despite previous studies. The variety factor has a much greater impact on the nature and frequency of certain types of aberrations than an increase in the mutagen concentration, it was characterised by a much greater site-specific effect than other chemical agents, and various variants in mutagenic effects were identified according to the subject’s genotype. It was generalised that the features that reproduced the effect of the mutagen, according to the discriminant analysis, were the total frequency, the frequency of fragments and double fragments, and bridges. In practical use in the genetic improvement of plants and for obtaining valuable traits, the optimal concentrations are 0.0125%, and 0.025%, which is planned to be further confirmed on a wider range of genotypes and by mutation studies for the next (second or third) generations

Genotype-mutagenic interaction in the cytogenetic variability of winter wheat for a new ecogenetic factor

The study of cytogenetic parameters of the activity of new mutagenic factors aims to reliably establish the possibilities of these factors in terms of variability depending on the subject of mutagenic action, the optimal use of certain factor sizes, the combination of the selected protocol with optimization of the yield of mutant forms in the future. Seeds of eight varieties of winter wheat (Balaton, Borovytsia, Zeleny Gai, Zoloto Ukrainy, Kalancha, Niva Odeska, Polyanka, Pochayna) were treated by SA (sodium azide) at concentrations of 0.010%, 0.025%, 0.05%, 0.10%. They were soaked in water solution for 24 hours. Cytogenetic activity was evaluated by pollen sterility, evaluation of general rates and indicators of spectra of chromosomal abnormalities at medium phases of cell mitosis according to wheat variety and chemical agent concentrations. As a result of the study, the key importance of the genotype-mutagenic interaction was demonstrated within the limits of variability of the main indicators of the frequency and spectrum of chromosomal aberrations. It has been established that in the future it will be more optimal to use two varieties whose genotype-mutagenic specificity indicators are significantly higher and one should expect a more significant yield of promising mutant forms from them in the future, especially in combination with SA concentrations in the range of 0.025% and 0.05%. It is demonstrated that the main parameters that reflect genetically determined possibilities in susceptibility to the ecogenetic factor are pollen fertility, the overall frequency of chromosome aberrations, and the number of induced fragments. The use of other parameters displays the trend only partially or does not display it at all, as is the case with the use of rarer types of chromosomal rearrangements. The least promising forms have also been identified for use as starting material in treatments with this substance. It is demonstrated that, in general, this agent is characterized by the same patterns in the induction of cytogenetic activity as for other chemical supermutagens, with some variations depending on the starting material. In the future, it is planned to link the obtained data with the frequency and quality of the resulting hereditary changes, primarily complex biochemical and physiological ones, in order to improve the quality of plant products and various types of plant tolerance to adverse environmental conditions.

Mechanisms of action of plant polyphenols on the initiation of carcinogenesis

Genetic apparatus of human cells is constantly affected by a broad spectrum of mutagenic factors, both exogenous and endogenous. Genetic and epigenetic disorders, which emerge as a result of this influence, become the main cause of the majority of malignant neoplasias. Several different approaches were proposed to prevent these disorders, including the suppression of the activity of mutagenic factors by treatment with certain chemical compounds. Plant polyphenols are promising candidates for the development of chemopreventive drugs, as they exert the ability to regulate the metabolic activation of procarcinogens and modulate the cellular oxidative stress. In the present review, classification of plant phenolic compounds and their interactions with biological macromolecules are described, along with the molecular mechanisms of their influence on the enzymes and regulatory pathways of phase I xenobiotic metabolism, and the prevention of oxidative stress. Interactions between natural polyphenols and patient’s microbiota is also described.

A non-mutated TROP2 fingerprint in cancer genetics.

The advent of high throughput DNA sequencing is providing massive amounts of tumor-associated mutation data. Implicit in these analyses is the assumption that, by acquiring a series of hallmark changes, normal cells evolve along a neoplastic path. However, the lack of correlation between cancer risk and global exposure to mutagenic factors provides arguments against this model. This suggested that additional, non-mutagenic factors are at work in cancer development. A candidate determinant is TROP2, that stands out for its expression in the majority of solid tumors in human, for its impact on the prognosis of most solid cancers and for its role as driver of cancer growth and metastatic diffusion, through overexpression as a wild-type form. The Trop-2 signaling network encompasses CREB1, Jun, NF-κB, Rb, STAT1 and STAT3, through induction of cyclin D1 and MAPK/ERK. Notably, Trop-2-driven pathways vastly overlap with those activated by most functionally relevant/most frequently mutated RAS and TP53, and are co-expressed in a large fraction of individual tumor cases, suggesting functional overlap. Mutated Ras was shown to synergize with the TROP2-CYCLIND1 mRNA chimera in transforming primary cells into tumorigenic ones. Genomic loss of TROP2 was found to promote carcinogenesis in squamous cell carcinomas through modulation of Src and mutated Ras pathways. DNA methylation and TP53 status were shown to cause genome instability and TROP gene amplification, together with Trop-2 protein overexpression. These findings suggest that mutagenic and the TROP2 non-mutagenic pathways deeply intertwine in driving transformed cell growth and malignant progression of solid cancers.

REVIEW ON BIO-DETOXIFICATION OF AFLATOXINS BASED ON LACTIC ACID BACTERIA: MECHANISM AND APPLICATIONS

Access to healthy food, without any undesirable contamination, is one of fundamental human right. Some of mycotoxins, especially aflatoxins (AFs), contamination feed and food that cause problems such as acute damage liver, irritation, and cancer of the liver and teratogenic complications. Among the physical, chemical and biological methods used to prevent the production, reduction, elimination and deactivation of AF in contaminated food, biological methods have been considered, due to maximum efficiency, low cost, eco-friendly and non-degradation of nutritional quality. The protective effect of lactic acid bacteria as probiotic microorganisms against mutagenic factors, such as polycyclic amines, N-nitrosamine compounds, and mycotoxins has been proven. Therefore, in addition to the beneficial properties using these probiotic bacteria with the ability to remove AF can help to enhance food safety. Although some naturally-occurring bacteria in the intestine can be attached to harmful components such as toxins and prevent them from binding to the intestinal layer, but probiotics have the potential to inactivate toxins through surface binding, due to high adhesion properties in their cell wall proteins. Polysaccharides and peptidoglycans in the cell wall are two of the main ingredients for decomposition, bonding and binding of AFs to lactic acid bacteria. Therefore, this review examines the economic and health impacts of AF contamination in foods. Further, this review discusses how lactic acid bacteria are able to detoxify common food AFs.

Investigation of Congo Red Toxicity towards Different Living Organisms: A Review

The use of dyes is widespread across almost all industries. Consequently, these dyes are found in various sources of water and food that humans, animals, and plants consume directly or indirectly. Most of these dyes are comprised of complex aromatic structures that have proven harmful. Congo red dye, a complex aromatic azo dye based on benzidine, is most commonly used in these dyes; its metabolites (benzidine and analogs) can be toxic, but Congo red dye itself is not always harmful. The present review summarizes the toxicity of Congo red dye towards different living forms. Herein, the primary emphasis has been given to the mutagenic, teratogenic, and carcinogenic consequences of Congo red and its metabolites. The mechanisms of azo dyes’ carcinogenicity have also been discussed. This review will undoubtedly be beneficial for researchers to understand the harmful effects of Congo red in genotoxic, teratogenic, mutagenic, and carcinogenic factors.

KARYOTYPAL VARIABILITY OF UKRAINIAN BROWN DAIRY BREED COWS

KARYOTYPAL VARIABILITY OF UKRAINIAN BROWN DAIRY BREED COWS

Studies on mutagenic effect of phosphemide in barley

Background. The method of induced mutagenesis is used to temporarily increase the frequency of mutations, allowing a higher probability of obtaining plants with new alleles and traits valuable for breeding. The search for new agents with high mutagenic activity is of particular interest for the development of mutational breeding. A new mutagen for barley is phosphemide.Materials and methods. Field and laboratory studies were conducted in 2016–2018. Three barley genotypes were treated with an aqueous solution of phosphemide at two concentrations: 0.002% and 0.01%, exposure: 3 hours. Experimental data were statistically processed by the analysis of variance (ANOVA) using Statistica 7. The error of the mean (Sx) was calculated for the mean values. Significance of differences (P < 0.05) was determined by Student’s t-test. Mutation frequency (Mf), mutagenic effectiveness (ME), and efficiency (Me) were assessed.Results and conclusion. It was found that the greatest contribution to formation of field seed germination of mutant populations in M1 and M2 generations was made by the mutagenic factor (20,36%) and interaction of the genotype × environment (18,55%) and mutagen × environment factors (14,93%). The concentration of 0.01% was recognized as semi-lethal for two accessions. In the M2 generation, the mutagenic effectiveness of the 0.002% phosphemide concentration exceeded that of 0.01% more than 4 times. The low concentration was more effective for cv. ‘Zernogradsky 813’ (17.43%) and accession Dz02- 129 (12.04%). For C.I. 10995, a higher concentration of phosphemide had greater effect (29.66%) providing a high mutation frequency (9.79%) against a relatively low lethality (33.00%). Nine different types were identified in the mutation spectrum. In M3 generation, distinct inheritance of the changes was confirmed in 46.43% of families. The highest number of families with confirmed changes was recorded for C.I. 10995 in the experiment with a higher concentration.

Studies on mutagenic effect of phosphemide in barley

Background. The method of induced mutagenesis is used to temporarily increase the frequency of mutations, allowing a higher probability of obtaining plants with new alleles and traits valuable for breeding. The search for new agents with high mutagenic activity is of particular interest for the development of mutational breeding. A new mutagen for barley is phosphemide.Materials and methods. Field and laboratory studies were conducted in 2016–2018. Three barley genotypes were treated with an aqueous solution of phosphemide at two concentrations: 0.002% and 0.01%, exposure: 3 hours. Experimental data were statistically processed by the analysis of variance (ANOVA) using Statistica 7. The error of the mean (Sx) was calculated for the mean values. Significance of differences (P < 0.05) was determined by Student’s t-test. Mutation frequency (Mf), mutagenic effectiveness (ME), and efficiency (Me) were assessed.Results and conclusion. It was found that the greatest contribution to formation of field seed germination of mutant populations in M1 and M2 generations was made by the mutagenic factor (20,36%) and interaction of the genotype × environment (18,55%) and mutagen × environment factors (14,93%). The concentration of 0.01% was recognized as semi-lethal for two accessions. In the M2 generation, the mutagenic effectiveness of the 0.002% phosphemide concentration exceeded that of 0.01% more than 4 times. The low concentration was more effective for cv. ‘Zernogradsky 813’ (17.43%) and accession Dz02- 129 (12.04%). For C.I. 10995, a higher concentration of phosphemide had greater effect (29.66%) providing a high mutation frequency (9.79%) against a relatively low lethality (33.00%). Nine different types were identified in the mutation spectrum. In M3 generation, distinct inheritance of the changes was confirmed in 46.43% of families. The highest number of families with confirmed changes was recorded for C.I. 10995 in the experiment with a higher concentration.

Plant genome modification: from induced mutagenesis to genome editing.

The snowballing growth of scientif ic data obtained using modern techniques of genome editing (GE) calls for their critical evaluation and comparison against previously applied methods such as induced mutagenesis, which was a leading method of genome modif ication for many decades of the past century, and its application has resulted in a huge diversity of cultivars. However, this method was relatively long and included a number of stages from inducing multiple mutations using different mutagenic factors to crossing and selecting the most valuable cultivars for several generations. A new technology of genetic engineering and transgenesis enabled us to radically reduce the time required to obtain a new genetically-modif ied cultivar to one generation and make the modif ication process more effective and targeted. The main drawback of this approach was that an introduced transgene might uncontrollably affect the other genes of a recipient plant, which led to the limitations imposed on transgenesis application in many countries. These limitations have been effectively surmounted thanks to the development of GE techniques allowing for a precise modif ication within a single gene that in many characteristics make it similar to a natural allele (especially when it comes to ribonucleoprotein complexes), which has paved the way for wide application of GE in routine breeding. The paper reviews the main stages of GE development in its application in plants. It provides short descriptions of different GE techniques, including those using protein editors such as zinc-f inger and transcription activator-like effector nucleases (TALEN), and the CRISPR/Cas9 technology. It lists a number of achievements in using GE to produce new cultivars of higher yield that are resistant to unfavorable factors and have good nutritional properties. The review also considers the de novo domestication approach, which allows for faster obtaining of new cultivars from natural varieties. In the conclusion, the future ways of GE development are discussed.

Quercetin and Isorhamnetin Reduce Benzo[a]pyrene-Induced Genotoxicity by Inducing RAD51 Expression through Downregulation of miR−34a

Benzo[a]pyrene (B[a]P) is metabolized in the liver into highly reactive mutagenic and genotoxic metabolites, which induce carcinogenesis. The mutagenic factors, including B[a]P-7,8-dihydrodiol-9,10-epoxide (BPDE) and reactive oxygen species, generated during B[a]P metabolism can cause DNA damage, such as BPDE-DNA adducts, 8-oxo-dG, and double-strand breaks (DSBs). In this study, we mechanistically investigated the effects of quercetin and its major metabolite isorhamnetin on the repair of B[a]P-induced DNA DSBs. Whole-transcriptome analysis showed that quercetin and isorhamnetin each modulate the expression levels of genes involved in DNA repair, especially those in homologous recombination. RAD51 was identified as a key gene whose expression level was decreased in B[a]P-treated cells and increased by quercetin or isorhamnetin treatment. Furthermore, the number of γH2AX foci induced by B[a]P was significantly decreased by quercetin or isorhamnetin, whereas RAD51 mRNA and protein levels were increased. Additionally, among the five microRNAs (miRs) known to downregulate RAD51, miR-34a level was significantly downregulated by quercetin or isorhamnetin. The protective effect of quercetin or isorhamnetin was lower in cells transfected with a miR-34a mimic than in non-transfected cells, and the B[a]P-induced DNA DSBs remained unrepaired. Our results show that quercetin and isorhamnetin each upregulates RAD51 by downregulating miR-34a and thereby suppresses B[a]P-induced DNA damage.

THE EFFECT OF MUTAGENS ON CALLUS REGENERATION

in this work were studied the characteristics of the development of F. tataricum and F. esculentum callus cultures in vitro when they were treated with chemical mutagen solutions - MH, MNU (0.05; 0.1; 0.2; 0.5; 1; 2 mM). When compared to the control on RX medium, the calli treated with the MNU mutagen died more often at higher concentrations (0.5; 1; 2 mM), indicating the effectiveness of the mutagenic effect. The survival rate of callus cultures subcultivated on a medium containing lower concentrations of mutagens (0.05; 0.1; 0.2 mM) was quite high when compared to higher concentrations, but low when compared to the control. The role of mutagenic factors in increasing genotypic variability, as well as the method of obtaining a new source material for various aspects of the buckwheat breeding process, have not been studied.

Winter wheat cytogenetic variability under the action of a chemical supermutagen

The analysis of cytogenetic activity is a key component in determining prospects of future hereditary variability after, subject to a certain mutagenic factor, primarily identifying the significance of the genotype-mutagenic interaction, the correctness of the selected concentrations for more thorough screening of some development parameters. Winter wheat seeds of eight varieties (Balaton, Borovytsia, Zeleny Gai, Zoloto Ukrainy, Kalancha, Niva Odeska, Polyanka, Pochayna) were subjected to ЕМS (ethylmethansulfonate) at the concentrations of 0.025%, 0.05%, 0.10% The exposure lasted for 24 hours. Cytogenetic analysis was carried out for pollen fertility; we also examined the rates and spectras of chromosomal rebuildings in proper cell devision phases in relation to plant gcnotype and concentration of the mutagen. The experiment was aimed at identification of interrection between geotype, concentration of mutagen and mutagen nature, determining genome response to mutagen action. Such indicators of cytogenetic activity as the total rate of chromosomal abnormalities, fragments and double fragments, single and double bridges, micronucleus and lagging chromosomes were studied. The selected concentrations of the mutagen significantly influenced all the analyzed parameters, they can be attributed to the optimal and high range of concentrations according to the nature of the impact on bread wheat. We determined that in the case of the mutagenic action, the genotype had a significantly lesser effect on the nature and rate of individual aberrations than an increase in the concentration, while having a significant effect on the rate of increase in pollen sterility. The mutagen was characterized by a significantly lower site-specificity at the cellular level than other chemical supermutagens, manifesting only in the correlation between individual types of aberrations, but not in the character of the increase in their number. The key parameter to identify the activity of this agent was the frequency of fragments and double fragments, their ratio with bridges.

The accumulation of polycyclic aromatic hydrocarbons in snails and soil in Igbekebo, Ondo State, Nigeria

Polycyclic Aromatic Hydrocarbons (PAHs) are harmful to human health and can cause cancer. The PAHs concentration in soil and snail samples collected from the Igbekebo region of Ondo state was measured in this study. Using metal spoons, soil samples were taken from five separate sites and placed in foil paper bags at a depth of 10 cm. For each type of snail under study, eight (8) samples were randomly taken from five distinct locations. Gas chromatography flame ionization detector (GC-FID) was used to analyze the samples. The estimated daily intake (EDI) and bioaccumulation factor (BAF) in the snail samples, as well as the toxic equivalence quotient (TEQ) and mutagenicity equivalence quotient (MEQ) in the soil samples, were calculated. This study showed that concentration levels of PAHs in soil, freshwater snail (Bulinus globosus), and land snail (Achatina marginata) samples were within the range of 0.1894–48.8063 μgkg−1, 0.15–40.14 μgkg−1, and 0.56–60.79 μgkg−1 respectively. Dibenzo(a,h)anthracene, anthracene, and Dibenzo(a,h)anthracene, respectively, were the most common PAHs found in soil, freshwater snails, and land snails. The total PAHs concentration in freshwater snail sample was lower when compared to other studies. The toxicity of each PAH in the soil sample was determined using Toxic Equivalent Factor (TEF) and Mutagenic Equivalent Factor (MEF) values, and the results were compared to the National Institute for Public Health and the Environment’s (Dutch: Rijksinstuut voor Volksgezondheid en Milieu (RIVM)) toxicity limits. It is advised to restrict crop and land snail consumption in Igbekebo since the soil samples from Igbekebo had a higher PAH toxicity value than the RIVM toxicity limit.

Реакция образцов озимого ячменя на обработку семян химическими мутагенами

In nature, a huge variety of traits is created in the systems of living organisms due to the occurrence of mutations. The use of ionizing radiation, ultraviolet rays, and many chemical compounds makes it possible to significantly increase the frequency of gene mutations, the genotypic and phenotypic variability of traits, and to achieve a sharp increase in the efficiency of artificial selection and the intensity of the selection process. The genotypic flexibility of the population and selection ensure adaptation to long-term changes in environmental factors. In the present work, the specificity of the mutagenic effect of some chemical mutagens on the winter barley variety Ardak on the variability of population and individual traits was studied for the first time. Our goal was to study the effect of carbolite and N-nitrosomethylurea in different concentrations on the agrobiological characteristics of winter barley. The scientific novelty of the conducted research lies in the study of the effect of carbolite and N-nmm in different concentrations on the agrobiological characteristics of winter barley, as well as on the content of total nitrogen and proteins in barley grains at previously unused or little studied doses. The object of the study was the seeds of barley variety Ardak. Carbolite compounds, N-nitrosomethyl urea were used as mutagenic factors. Carbolite was used at a concentration of 2n, the seeds were treated with carbolite solution for 6, 12, 18 and 24 hours. In the present studies, N-nitrosomethyl urea was used at concentrations of 0.012% and 0.025%. Barley seeds were treated with aqueous solutions of the mutagen for three hours, and then washed in running water at a temperature of 22 °C for 30 minutes. Control seeds were soaked in water. After treatment, the seeds were dried on filter paper and sown in the soil after 10 days. Each option contains 250 seeds. Seed germination was counted after two weeks. Subsequently, the linear parameters of plants were measured every 10 days. After harvesting, the plants were analyzed for morphological changes and the total percentage of changed plants was calculated. In addition, the sign was studied — the weight of 1000 grains. Seeds of the first generation for the next year were sown in the soil according to the treatment options (250 pieces). Second generation plants were analyzed in the same way as M1 plants. Next, a biochemical analysis of the seeds was carried out to determine the total amount of nitrogen and protein according to the treatment options. The Kjeldahl micro-method was used to determine total nitrogen. As a result of the research, it was found that carbolite at a concentration of 2n in 6- and 18-hour exposures stimulates the content of total nitrogen and protein in the first generation in grains of barley variety Ardak. It has an overwhelming effect on the biochemical processes of barley seeds in the second generation. At the same time, carbolite inhibits the development of barley and causes the appearance of a large number of speltoid and sterile plants. But at the same time, it should be emphasized that a large number of speltoids and sterile plants in the variants treated with carbolite decreases in the second generation. N-nmm at concentrations of 0.012% and 0.025% contribute to an increase in the content of total nitrogen and protein in barley grains. The increased content of nitrogen and protein in the treated N-nmm variant is preserved in the second generation. It should be noted that N-nmm at a concentration of 0.012% is more effective for this variety than at a concentration of 0.025%. Also, N-nmm inhibits the development of barley and causes a large number of morphological changes. In a comparative study of the effect of mutagens N-nmm and carbolite on the content of the total amount of nitrogen and protein, it was found that N-nmm contributes to an increase in the amount of nitrogen and protein, while carbolite decreases.

Update on classification of melanocytic tumors and the role of immunohistochemistry and molecular techniques.

The nine pathways to melanoma outlined in the most recent WHO classification of skin tumors attempt to capture the typical evolution of different subtypes of melanoma as governed by cell of origin, mutagenic factors and oncogenic drivers. This pathway-based classification will continue to be refined as we learn more about melanocytic tumor biology. I review the practical application of immunohistochemistry and molecular techniques in the diagnosis of melanocytic tumors in the context of this classification.