Concentrations Of Mutagens Research Articles

Micronucleus Assay with Tetrad Cells of Tradescantia.

The Tradescantia micronucleus assay has been used since 50years for the detection of genotoxins (including carcinogens) in the environment. A large database concerning the effects of individual chemicals and complex environmental mixtures (soil, airand waters) has accumulated. In contrast to other mutagenicity test systems, the effects of low concentrations of heavy metals, radionuclides, certain herbicides, pesticides and gaseous mutagens can be detected and it is also possible to conduct in situ biomonitoring studies with plant. The test system has been validated and standardized protocols have been developed for laboratory experiments and for field studies which are described in this chapter.

The influence of mutagenic factors on agronomic traits of spring barley varieties in М1 and emergence of modified forms in М2

Purpose. To determine response of spring barley varieties to action of different concentrations of mutagens in M1. To study effect of the mutagens on the formation of agronomic traits in M1, M2 spring barley varieties. Methods. The experiments with the varieties of Myronivka breeding Virazh and Talisman Myronivskyi were carried out in 2016, 2017 in the conditions of the experimental field of the Scientific-Research Center of Bila Tserkva National Agrarian University as well as in laboratory. The seeds were soaked in solutions of mutagen hydroxylamine (HA) at concentrations 1.0 % (high); 0.5 % (medium), and 0.1 % (low) and mutagen nitrosomethylurea (NMU) at concentrations 0.1 % (high), 0.01 % (medium) and 0.001 % (low). Seeds soaked in water were as the control. The exposition was 18 hours. In M1 seed vigor in laboratory conditions and field germination were evaluated. In M2 plant height, main spike length, grain number and grain weight per main spike were determined. Seeds harvested from the control variants in M1 were used as the control in M2. Results. As compared with HA the mutagen NMU at high-concentration caused high level of depression in spring barley seedlings resulted in decrease of field germination for the variety Vіrazh to 24.0 %, for the variety Talisman Myronivskyi to 51.0 %. When treating seeds with NMU at high concentration, in M1 of the variety Vіrаzh the plants with loose and long (12.7 cm) spike were obtained, whereas 10.0 cm in control. In М2 the variety Vіrazh families were obtained (10/4, 11/2б and 11/4) with significant decrease in plant height (53.0–53.3 cm, control 60.2 cm) which were obtained by the action of mutagen NMU at medium and low concentrations. When mutagen HA in low concentration and mutagen HMM in high concentration acting on seeds of the variety Vіrazh, families (5/1 and 9/2) were obtained which significantly exceeded control in main spike length and grains number per main spike. Conclusions. The indices seed vigor, field germination and main spike length were the most informative ones for mutagenic action in spring barley M1. The action of mutagen NMU in high concentrations caused higher level of depression than mutagen HA. Seed germination was influenced by mutagen concentration, mutagen nature and genotype. In M2 of the varieties Virazh and Talisman Myronivskyi the appearance of modified forms in terms of plant height, main spike length, grain number and grain weight per main spike have been marked. The best results were achieved by the action of high concentration of NMU and high and low concentration of HA The genotype, mutagen concentration and the nature of the mutagen influenced on the formation of yield components in M2. Studies on mutant generations will continue in M3 and M4 to search valuable mutations.

Mutagenic Effectiveness and Efficiency of EMS and Sodium Azide in Mungbean [Vigna radiata (L.) Wilczek

The present experiment assesses the relative effectiveness and efficiency of two widely used chemical mutagens on two well adapted varieties of Mungbean namely Pusa Vishal and SML-668 which was treated with 3 different doses each of EMS (0.2, 0.4, and 0.6%) and Sodium azide (0.06, 0.08, and 0.1%). The relative effectiveness and efficiency was assessed from the data on biological damage in M1 generation and frequency of chlorophyll mutants in M2 generation. The mutagenic effectiveness was inversely proportional to the increasing concentrations or doses of mutagens in Sodium azide. Low concentrations were found to be most effective and had promotary effect on plant height, pods per plant, 100 seed weight, seed yield per plant, branches per plant and pod length while both promotary and inhibitory effect were observed for seeds per pod, days to flowering and days to maturity. Sodium azide (SA) was found to be more effective mutagen to produce high frequency of chlorophyll mutations followed by EMS. It was also found that the lower concentrations of both mutagens were most effective in both the varieties. The decrease in effectiveness with increasing concentrations of mutagen could be attributed to the biological damage (like seedling injury, lethality, and sterility) which increased with increase in dose at faster rate than the mutations. Mutagenic efficiency is referred to the frequency of chlorophyll mutations in relation to M1 damage. Both the mutagens viz. EMS and Sodium azide exhibited gradual decrease in mutagenic efficiency with the increasing concentration or doses with respect to seedling injury and lethality.

Cyclic di-GMP Positively Regulates DNA Repair in Vibrio cholerae.

In Vibrio cholerae, high intracellular cyclic di-GMP (c-di-GMP) concentration are associated with a biofilm lifestyle, while low intracellular c-di-GMP concentrations are associated with a motile lifestyle. c-di-GMP also regulates other behaviors, such as acetoin production and type II secretion; however, the extent of phenotypes regulated by c-di-GMP is not fully understood. We recently determined that the sequence upstream of the DNA repair gene encoding 3-methyladenine glycosylase (tag) was positively induced by c-di-GMP, suggesting that this signaling system might impact DNA repair pathways. We identified a DNA region upstream of tag that is required for transcriptional induction by c-di-GMP. We further showed that c-di-GMP induction of tag expression was dependent on the c-di-GMP-dependent biofilm regulators VpsT and VpsR. In vitro binding assays and heterologous host expression studies show that VpsT acts directly at the tag promoter in response to c-di-GMP to induce tag expression. Last, we determined that strains with high c-di-GMP concentrations are more tolerant of the DNA-damaging agent methyl methanesulfonate. Our results indicate that the regulatory network of c-di-GMP in V. cholerae extends beyond biofilm formation and motility to regulate DNA repair through the VpsR/VpsT c-di-GMP-dependent cascade.IMPORTANCEVibrio cholerae is a prominent human pathogen that is currently causing a pandemic outbreak in Haiti, Yemen, and Ethiopia. The second messenger molecule cyclic di-GMP (c-di-GMP) mediates the transitions in V. cholerae between a sessile biofilm-forming state and a motile lifestyle, both of which are important during V. cholerae environmental persistence and human infections. Here, we report that in V. cholerae c-di-GMP also controls DNA repair. We elucidate the regulatory pathway by which c-di-GMP increases DNA repair, allowing this bacterium to tolerate high concentrations of mutagens at high intracellular levels of c-di-GMP. Our work suggests that DNA repair and biofilm formation may be linked in V. cholerae.

Ethyl methane sulphonate induced changes in cyto-morphological and biochemical aspects of Coriandrum sativum L.

Abstract Induced mutagenesis plays a pivotal role in inducing variability among crops where hybridization is too hectic. However, efficiency of mutagen can be estimated by determining its effectiveness in inducing desirable characteristics in a short period in crops having narrow genetic base. Hence, present study has been done to assess the mutagenic impact of Ethyl Methane Sulphonate (EMS) on cytological, morphological and biochemical constituents of Coriandrum sativum L. The results revealed that the higher concentration and treatment duration are toxic in nature whereas lower concentrations of mutagen were quite beneficial in inducing positive characteristics with less toxicity. There was a progressive elevation in the chromosomal aberrations along with variations in morphological traits. The biochemical constituents (photosynthetic pigments and proline) are greatly affected by higher concentrations and durations of EMS treatment. The prominent chromosomal aberrations were stickiness and precocious movement at metaphase and bridges at anaphase while unorientation, scattering, c-metaphase laggards and disturbed polarity were also reported.

Local Acetaldehyde-An Essential Role in Alcohol-Related Upper Gastrointestinal Tract Carcinogenesis.

The resident microbiome plays a key role in exposure of the upper gastrointestinal (GI) tract mucosa to acetaldehyde (ACH), a carcinogenic metabolite of ethanol. Poor oral health is a significant risk factor for oral and esophageal carcinogenesis and is characterized by a dysbiotic microbiome. Dysbiosis leads to increased growth of opportunistic pathogens (such as Candida yeasts) and may cause an up to 100% increase in the local ACH production, which is further modified by organ-specific expression and gene polymorphisms of ethanol-metabolizing and ACH-metabolizing enzymes. A point mutation in the aldehyde dehydrogenase 2 gene has randomized millions of alcohol consumers to markedly increased local ACH exposure via saliva and gastric juice, which is associated with a manifold risk for upper GI tract cancers. This human cancer model proves conclusively the causal relationship between ACH and upper GI tract carcinogenesis and provides novel possibilities for the quantitative assessment of ACH carcinogenicity in the human oropharynx. ACH formed from ethanol present in “non-alcoholic” beverages, fermented food, or added during food preparation forms a significant epidemiologic bias in cancer epidemiology. The same also concerns “free” ACH present in mutagenic concentrations in multiple beverages and foodstuffs. Local exposure to ACH is cumulative and can be reduced markedly both at the population and individual level. At best, a person would never consume tobacco, alcohol, or both. However, even smoking cessation and moderation of alcohol consumption are associated with a marked decrease in local ACH exposure and cancer risk, especially among established risk groups.

Adduction to arginine detoxifies aflatoxin B1 by eliminating genotoxicity and altering in vitro toxicokinetic profiles.

Aflatoxin B1 (AFB1), a class 1 carcinogen and prominent food contaminant, is highly linked to the development of hepatocellular carcinoma (HCC) and plays a causative role in a large portion of global HCC cases. We have demonstrated that a mixture of common organic acids (citric and phosphoric acid) along with arginine can eliminate >99% of AFB1 in solution as well as on corn kernels and convert it to the AFB2a-Arg adduct, acting as a potential detoxification process for contaminated foods. Evaluation of toxicokinetic changes after AFB2a-Arg formation show that the product is highly stable in biological fluids, is not metabolized by P450 enzymes, is highly plasma protein bound, has low lipid solubility, and has poor intestinal permeability/high intestinal efflux compared to AFB1. Ames’ test results show that at mutagenic concentrations of AFB1, AFB2a-Arg does not have any measurable mutagenic effect which was confirmed by DNA adduct identification by liquid chromatography-mass spectrometry. Evaluation in HepG2 and HepaRG cells showed that AFB2a-Arg did not cause any significant decreases in cell viability nor did it increase micronuclei formation when administered at toxic concentrations of AFB1. These results show that conversion of AFB1 to AFB2a-Arg is a potential strategy to detoxify contaminated foods.

EFFECT OF SOME AZOSPIRILLUM STRAINS AS A PARTIAL REPLACEMENT OF INORGANIC N FERTILIZERS ON YIELD AND QUALITY OF SUPERIOR GRAPEVINES

About 91 mutants were obtained from exposing Azospirillum brasilense to different concentrations of Acriflavine mutagen and different time exposure. Out of those three new N microbial strains namely Methionineless, Threonineless and Tyrosineless were tested on Superior grapevines after their showed highest growth on artificial media. Superior grapevines were supplied with these microbial strains at 5 to 20 ml/vine and three slow release fertilizers (Methylene urea, Sulphur coated urea and urea formaldehyde) at 25 to 75% as partial replacement of the fast release N fertilizer namely ammonium nitrate during 2015 and 2016 seasons. Supplying Superior grapevines with N through 50 to 75 % inorganic N + 25 to 50% slow release N fertilizers (Methylene urea, Sulphur coated urea and urea formaldehyde) + bacteria strains (Methionineless, Threonineless and Tyrosineless) at 5 to 10 ml/vine proved to be very effective in stimulating all growth traits, leaf pigments and nutrients , berry setting %, yield and quality of the berries relative to using N as 100 % mineral N or when mineral N was added at 25%. An obvious reduction was observed on both nitrate and nitrite in the juice, with reducing percentages of mineral N from 100 to 25% as well as increasing percentages of the three release N fertilizers from 25 to 75% and the three bacterial strains from 5 to 20 ml/vine. The best bacterial strains in this respect were Methionineless, Theronineless and Tyrosineless, in ascending order. The best slow release fertilizer was methylene urea followed by sulphur coated urea. Amending Superior grapevines with N as 50% inorganic N (ammonium nitrate) + 50% slow release N fertilizer (methylene urea) + Tyrosineless at 10 ml/vine was responsible for promoting yield and fruit quality.

Gamma rays and EMS induced Flower Color Mutation in Grasspea (Lathyrus sativus Linn.)

To induce flower color mutants in Grasspea ( Lathyrus sativus Linn.) variety “Pusa-24“, the fresh seeds were exposed to 4 different doses of gamma radiation as physical mutagens (100, 200, 300 and 400 Gy) and treated with 4 different concentration of Ethyl Methanesulphonate as chemical mutagen (5, 10, 15 and 20 mM ) and also combination of both mutagens. Due to mutagenesis broad range of flower color mutants in M 2 , M 3 and M 4 were obtained. Various unique and different flower color mutations like pink, purple, white and yellow detected against blue which is natural color in control progenies. Maximum flower color frequency was recorded in EMS treated seeds (20 mM) in 4th generation and lowest mutation frequency in 2nd generation was obtained in gamma rays (100 Gy) treated seeds. The results showed more flower color mutations happened in more dose /concentration of mutagens in every generation

STUDY OF EFFECT OF EMS, MMS AND GR ON YIELD CONTRIBUTING TRAITS IN URDBEAN, VIGNA MUNGO

The study of the effect of three well known mutagens, ethyl methane sulphonate (EMS), methyl methane sulphonate (MMS) and gamma rays (GR) on the yield contributing traits of the urdbean variety TPU-4 were carried out in the M3 generation. Effect of selected mutagenic treatments/doses of EMS (0.02, 0.03 and 0.04 M), MMS (0.0025, 0.05 and 0.01 M) and (GR) (30, 40 and 50 KR) on different yield contributing traits like plant height, plant spread, number of pods per plant, pod length, number of seeds per pod, seed yield per plant and 100 seed weight were analyzed in the M3 populations of the variety TPU-4. Seeds of M2 plants and control were harvested separately and sown to raise M3 population.. Genetic variabilty in the mutagen administered M3 progeny of the urdbean variety TPU-4 was analyzed by employing statistical methods. Data on mean values and shift in the mean of seven quantitative traits was evaluated on individual plant basis. The experimental findings revealed that concentrations / dose of the all these mutagens showed inhibitory effect on plant height, number of pods per plant, pod length and number of seeds per pod. Lower concentrations of mutagens exerted a promotory effect on plant spread, 100 seed weight and seed yield per plant while higher concentrations of these mutagens inhibited them to different extent.

Ethyl Methanesulfonate Mutagenesis and In Vitro Polyethylene Glycol Selection for Drought Tolerance in Sugarcane (Saccharum spp.)

Drought is a serious agronomic problem, and urgent attention to overcome drought stress is vital to eradicate or minimize its effects on crop production. Random induction of genomic mutation is a technique that can enhance genetic diversity leading to useful traits such as enhanced drought tolerance. In this study, sugarcane callus was exposed to different concentrations of the chemical mutagen, ethyl methanesulfonate (EMS). Concentrations of 20 mM and lower were identified as useful to induce genomic mutations without compromising in vitro sugarcane plant regeneration abilities. Furthermore, sugarcane callus was exposed to varying concentrations of polyethylene glycol (PEG) for different time periods in order to identify a suitable in vitro osmotic selection regime to simulate drought stress in vitro. The optimal in vitro osmotic selection treatment was identified as callus exposed to 20% (w/v) PEG6000 for 8 weeks, followed by a 2 weeks osmotic recovery period without PEG and ending with a further 8 week PEG selection period during somatic embryo regenerations. Sugarcane callus from the NCo310 cultivar was subsequently mutagenized with 16 mM EMS and in vitro selected on 20% (w/v) PEG6000, which resulted in the survival of 18 plantlets. These in vitro selected lines were subjected to preliminary greenhouse pot trials to confirm drought tolerance. Pot trials identified seven lines that outlived NCo310 control plants. In addition, when re-watered after the drought stress period, plants from one mutant line recovered and were able to form new shoots. The results from this study indicate, therefore, that EMS mutagenesis and in vitro selection for osmotic pressure using PEG can be successfully applied to cultivate sugarcane plants with improved morphological and physiological responses to water stress.

Induce Physical and Chemical Mutagenesis for Improvement of Yield Attributing Traits and their Correlation Analysis in Chickpea

In the current scenario of sky high population and widespread food insecurity, there is an urgent need for productivity improvement of major crops like pulses, one of the most climate friendly and accessible foods for the large poor population of the world. Chickpea is an important pulse crop, having high percentage of nutritional content and is widely used as food across the world. Induced mutagenesis has proved over time as a coherent tool for modern plant breeders to improve the productivity for combating the food insecurity and malnutrition across the globe. Dry and healthy seeds of Cicer arietinum L. var. C-235 were treated with individual and combination doses of gamma rays, sodium azide and hydrazine hydrate to raise the M1 generation. M2 seeds harvested from M1 plants were sown in the nest season.Bio-physiological study in M1 generation showed growth inhibition in the order viz. combination treatment>hydrazine hydrate>gamma rays>sodium azide. In M2 generation, comparative observations were recorded for morphological variation and quantitative traits to assess the genetic response of the chickpea variety C-235 toward the different concentrations of mutagens. Observations on isolated mutants in M2 generation revealed that 0.3% HZ + 0.02% SA was most mutagenic while 200 Gy, 0.03% SA and 0.2% HZ were highest in their individual treatment groups. In context to the frequency of morphological mutants studied in M2 generation, dwarf mutants were found to be highest followed by tall and branching pattern mutants. Highly significant correlation coefficient between yield and other traits showed that the selection for high yielding mutants can be done on the basis of these traits undoubtedly.

Induce Physical and Chemical Mutagenesis for Improvement of Yield Attributing Traits and their Correlation Analysis in Chickpea

In the current scenario of sky high population and widespread food insecurity, there is an urgent need for productivity improvement of major crops like pulses, one of the most climate friendly and accessible foods for the large poor population of the world. Chickpea is an important pulse crop, having high percentage of nutritional content and is widely used as food across the world. Induced mutagenesis has proved over time as a coherent tool for modern plant breeders to improve the productivity for combating the food insecurity and malnutrition across the globe. Dry and healthy seeds of Cicer arietinum L. var. C-235 were treated with individual and combination doses of gamma rays, sodium azide and hydrazine hydrate to raise the M1 generation. M2 seeds harvested from M1 plants were sown in the nest season.Bio-physiological study in M1 generation showed growth inhibition in the order viz. combination treatment>hydrazine hydrate>gamma rays>sodium azide. In M2 generation, comparative observations were recorded for morphological variation and quantitative traits to assess the genetic response of the chickpea variety C-235 toward the different concentrations of mutagens. Observations on isolated mutants in M2 generation revealed that 0.3% HZ + 0.02% SA was most mutagenic while 200 Gy, 0.03% SA and 0.2% HZ were highest in their individual treatment groups. In context to the frequency of morphological mutants studied in M2 generation, dwarf mutants were found to be highest followed by tall and branching pattern mutants. Highly significant correlation coefficient between yield and other traits showed that the selection for high yielding mutants can be done on the basis of these traits undoubtedly.

P1.02-084 Polo-Like Kinase 1 (PLK1) Inhibition Decreases Mutational Activity in Bronchial Epithelial Cells Exposed to Tobacco Carcinogens

Persistence of bronchial dysplasia (BD) is associated with increased risk for the development of squamous cell carcinoma (SCC) of the lung. A comparison of persistent and regressive BD demonstrated that alterations in gene expression can distinguish these types of lesions. Using the genes that differentiate persistent and regressive BD we have identified PLK1 as a key mediator of persistence and have hypothesized that the role it plays in abrogating G2-M cell cycle arrest in the presence of mutational alterations may be central to progression of premalignant airway lesions to invasive SCC. Cultures of the bronchial epithelium derived BEAS-2B (B2B) cell line were exposed to airway mutagens (cigarette smoke condensate [CSC, Kentucky Reference Cigarette 3R4F] or Benzo[A]pyrene, [BaP]) alone or in the presence of 100 nM PLK1 inhibitor Volasertib. Following treatment, clones were selected by ring isolation and DNA was collected to assess mutational events as compared to untreated controls using the TruSightOne targeted next generation sequencing panel (12 megabase coverage, >4800 genes, Illumina, San Diego, CA). Modal distribution of mutation frequencies indicated that ring clones were composed of between 1 - 3 distinct clones. Mutation rates were calculated using these adjusted clone counts for standardization. Using the untreated B2B cultures as reference sequence, CSC or BaP alone induced mean incidences of mutations of 15.7 and 60.9 per clone, respectively, although the induction of fewer mutations by CSC made accurate estimates of clonal numbers more difficult. B2B cultures treated with the same concentration and duration of mutagen in the presence of Volasertib showed mean mutational incidences of 13 and 17 per clone, respectively. The ratio of mutation rate for the CSC and BaP treated groups with versus without Volasertib were 0.83 and 0.28, respectively. All mutations detected were single nucleotide variants and characteristic patterns of base changes were noted between mutagen groups with C>A and G>T transversions being more prominent in BaP treated cultures. Ongoing analyses using whole genome sequencing will allow for more accurate enumeration of clones represented and a richer assessment of mutation rates including rearrangements and copy number variants in mutagen treated cells in the presence and absence of PLK1 inhibition. Preliminary analyses of bronchial epithelial cell cultures treated with mutagens show reduction of BaP induced mutations in the presence of PLK1 inhibition. The results suggest PLK1 overexpression in BD may promote genomic instability.

Mutagenesis and TILLING to Dissect Gene Function in Plants.

Mutagenesis can be random or targeted and occur by nature or artificially by humans. However, the bulk of mutagenesis employed in plants are random and caused by physical agents such as x-ray and gamma-ray or chemicals such as ethyl-methane sulfonate (EMS). Researchers are interested in first identifying these mutations and/or polymorphisms in the genome followed by investigating their effects in the plant function as well as their application in crop improvement. The high-throughput technique called TILLING (Targeting Induced Local Lesion IN Genomes) has been already established and become popular for identifying candidate mutant individuals harboring mutations in the gene of interest. TILLING is a non-transgenic and reverse genetics method of identifying a single nucleotide changes. The procedure of TILLING comprises traditional mutagenesis using optimum type and concentration of mutagen, development of a non-chimeric population, DNA extraction and pooling, mutation detection as well as validation of results. In general, TILLING has proved to be robust in identifying useful mutant lines in diverse economically important crops of the world. The main goal of the current mini-review is to show the significance role played by mutagenesis and TILLING in the discovery of DNA lesions which are to be used in the improvement of crops for the trait of interest.

Development of Mutants in Sugarcane through Callus Culture

The effects of different concentrations (0.0 M, 0.01 M, 0.02 M and 0.03 M for 24 hours treatment) of chemical mutagen like, ethyl methanesulfphonate (EMS) on callus derived from sugarcane var. Isd 37, Isd 39 and Isd 40 were investigated for in vitro plant regeneration. The highest number of shoots (58.33%) was reduced over control of Isd 40 followed by Isd 37 (57.62%) and Isd 39 (the lowest 56.06%), respectively due to the use of EMS for treating calli. The regeneration of mutant plantlets was achieved from EMS (0.01 M) treated calli obtained from leaf sheath explants on MS supplemented with 2, 4?D (3 mg/l) and 10% coconut water. Most of the mutant plants were developed from Isd 37. The developed mutant plants showed variation in tiller number, internode, green leaf, millable cane and stalk colour from the source variety of Isd 37.Plant Tissue Cult. & Biotech. 26(1): 123-130, 2016 (June)

Estimation of genetic variability, mutagenic effectiveness and efficiency in M2 flower mutant lines of Capsicum annuum L. treated with caffeine and their analysis through RAPD markers

In the present investigation healthy and certified seeds of Capsicum annuum were treated with five concentrations of caffeine i.e. 0.10%, 0.25%, 0.50%, 0.75% and 1.0%. Germination percentage, plants survival and pollen fertility were decreased with the increase of caffeine concentrations. Similarly root length and shoot length were decreased as the concentrations increased in M1 generation. Different mutants were isolated in M1 generation. In M2 generation, various flower mutants with changes in number of sepals, petals, anther size colour i.e. Trimerous, tetramerous, pentamerous with fused petals, hexamerous etc were segregated. Heptamerous and anther change was not observed in lower concentration viz. 0.1%. All these mutants showed significant changes in morphological characters and good breeding values at lower and intermediate concentrations. Mutagenic effectiveness and efficiency was observed on the basis of M2 flower mutant frequency. It was generally decreased with the increase of mutagen concentrations. Cytological aberrations in mutants showed the decreasing trend at meiotic final stages. These mutants were further analysed through RAPD method and on the basis of appearance of polymorphic DNA bands, they distinguished these flower mutants genotypically. Among 93 bands 44 bands were polymorphic which showed great genetic variation produced by caffeine. As an outcome of that the above caffeine concentrations are good for the induction of genetic variability in Capsicum genotype.

Major Anaerobic Bacteria Responsible for the Production of Carcinogenic Acetaldehyde from Ethanol in the Colon and Rectum.

The importance of ethanol oxidation by intestinal aerobes and facultative anaerobes under aerobic conditions in the pathogenesis of ethanol-related colorectal cancer has been proposed. However, the role of obligate anaerobes therein remains to be established, and it is still unclear which bacterial species, if any, are most important in the production and/or elimination of carcinogenic acetaldehyde under such conditions. This study was undertaken to address these issues. More than 500 bacterial strains were isolated from the faeces of Japanese alcoholics and phylogenetically characterized, and their aerobic ethanol metabolism was studied in vitro to examine their ability to accumulate acetaldehyde beyond the minimum mutagenic concentration (MMC, 50 µM). Bacterial strains that were considered to potentially accumulate acetaldehyde beyond the MMC under aerobic conditions in the colon and rectum were identified and referred to as 'potential acetaldehyde accumulators' (PAAs). Ruminococcus, an obligate anaerobe, was identified as a genus that includes a large number of PAAs. Other obligate anaerobes were also found to include PAAs. The accumulation of acetaldehyde by PAAs colonizing the colorectal mucosal surface could be described, at least in part, as the response of PAAs to oxidative stress. Ethanol oxidation by intestinal obligate anaerobes under aerobic conditions in the colon and rectum could also play an important role in the pathogenesis of ethanol-related colorectal cancer.

Induction of mutagenized tomato populations for investigation on agronomic traits and mutant phenotyping

Global demand for tomato production increased tremendously due to its diverse utility in raw, cooked and processed form of food. This necessitates the continued supply of highly nutritious and better yielding improved cultivars to the producers, considering the rapid changing agro-climatic condition. In this study, induced mutant tomato populations of widely recommended tomato genotype Arka Vikas (Sel-22) were generated using chemical mutagen ethyl methane sulfonate (EMS), hydrazine hydrates (HZ) and their combined treatments. In the in vitro study, a gradual reduction in germination percentage and seedling height occurred with the increasing concentrations of mutagens. Combination of EMS and HZ caused maximum biological inhibition followed by EMS and HZ treatments alone in M1 generation. The rate of survival and fertility in M1 plants of tomato was found highly affected due to mutagenic treatment, in which sensitivity toward combined treatment was found highest followed by EMS and HZ. Inspection on induced phenotypic variations in individual plants of M2 population resulted in identification and isolation of wide range of mutants with altered phenotypes. Highest mutation frequency was resulted by combined mutagens followed by the EMS and HZ treatment. Agronomic trait analyses showed intra and inter treatment variations in three quantitative traits (Plant height, fertile branch per plant and fruits per plant) of M2 mutagenized population. Assessment on rate of mutant recovery in M2 population showed highest mutant recovery is possible with combination treatments and then 0.02% HZ followed by 0.02% EMS. In the present study, phenotyping of the mutants revealed that vegetative organs (‘plant size’, ‘plant habit’ and ‘leaf morphology’) was the most sensitive category (69.33%) to which most of the mutant belongs, followed by ‘fruit color and size’ (20.27%) and ‘germination’ (9.79%). Comparative investigation on number of mutants and phenotype category in M2 mutant plants confirmed that the number of pleiotropic mutants was more than the non-pleiotropic mutants in all the treatment conditions. Heritability and reproducibility of the 30 putative mutants were checked in M3 generation based on the observed agro-economical traits; results showed 17 complete and 5 partial heritable mutants.

Phenotypic and biochemical profile changes in calendula (Calendula officinalis L.) plants treated with two chemical mutagenesis

Chemical mutagenesis is an efficient tool used in mutation-breeding programs to improve the vital characters of the floricultural crops. This study aimed to estimate the effects of different concentrations of two chemical mutagens; sodium azide (SA) and diethyl sulfate (DES). The vegetative growth and flowering characteristics in two generations (M1 and M2) of calendula plants were investigated. Seeds were treated with five different concentrations of SA and DES (at the same rates) of 1000, 2000, 3000, 4000, and 5000 ppm, in addition to a control treatment of 0 ppm. Results showed that lower concentrations of SA mutagen had significant effects on seed germination percentage, plant height, leaf area, plant fresh weight, flowering date, inflorescence diameter, and gas-exchange measurements in plants of both generations. Calendula plants tended to flower earlier under low mutagen concentrations (1000 ppm), whereas higher concentrations delayed flowering significantly. Positive results on seed germination, plant height, number of branches, plant fresh weight, and leaf area were observed in the M2-generation at lower concentrations of SA (1000 ppm), as well as at 4000 ppm DES on number of leaves and inflorescences. The highest total soluble protein was detected at the concentrations of 1000 ppm SA and 2000 ppm DES. DES showed higher average of acid phosphatase activity than SA. Results indicated that lower concentrations of SA and DES mutagens had positive effects on seed germination percentage, plant height, leaf area, plant fresh weight, flowering date, inflorescence diameter, and gas-exchange measurements. Thus, lower mutagen concentrations could be recommended for better floral and physio-chemical performance.