Concentrations Of EMS Research Articles

Differential response of biochemical parameters to EMS and MMS treatments and their dose effect relationship on chromosomes in induced diabetic mouse

AimTo study the effect of alkylating agents such as EMS and MMS on chromosomes and biochemical parameters in induced diabetic mouse. MethodsChromosome preparations from bone marrow was made using the method of Evans et al. (1964) and biochemical estimations from the liver was done by the method of Sinha (1972) for catalase, Van der Vies (1954) for glycogen and Uchiyama and Mihara (1978) for MDA. ResultsThe study has revealed that EMS and MMS induced a dose dependent increase in chromosomal aberrations of chromatid type in the diabetic mouse. Nonetheless, it is interesting to note that, there is significant reduction in the frequency of chromosomal aberrations in diabetic compared to non diabetic mice at all tested doses of EMS or MMS and at different recovery times [RTs]. On the other hand biochemical parameters showed a variable degree of reactivity: (1) catalase activity was significantly elevated in non diabetics whereas in diabetics it is significantly decreased with increasing concentrations of EMS. Contrary to this, the catalase activity in the case of MMS treatment is significantly reduced in non diabetics compared to diabetic mice. (2) However glycogen level is significantly reduced in both the diabetic and non diabetic with increasing concentrations of EMS or MMS, but MDA levels were significantly increased. Conclusion(1) Even though alkylating agents induce chromosomal aberrations in diabetic mice, MMS, a methylating agent is a more potent inducer of chromatid type of aberrations than EMS, an ethylating agent. (2) Diabetic mouse is more resistant than the non diabetic to alkylating agents and (3) the tested agents altered the analyzed biochemical parameters.

Assay reproducibility and interindividual variation for 15 serum estrogens and estrogen metabolites measured by liquid chromatography-tandem mass spectrometry.

Interindividual differences in estrogen metabolism may partially account for differences in risks of estrogen-responsive cancers. We conducted a proof-of-performance study to assess the reproducibility of a LC/MS-MS method for measurement of 15 serum estrogens and metabolites (all 15 termed EM) in total (conjugated+unconjugated) and unconjugated forms and describe interindividual variation. Interindividual variation in serum EM profiles was evaluated for 20 premenopausal women, 15 postmenopausal women, and 10 men. Replicate aliquots from 10 premenopausal women, 5 postmenopausal women, and 5 men were assayed eight times over 4 weeks. Components of variance were used to calculate coefficients of variation (CV) and intraclass correlation coefficients (ICC). In postmenopausal women and men, median EM concentrations were similar and substantially lower than that in premenopausal women. Within each sex/menopausal group, the sum of all EM varied 5- to 7-fold across extreme deciles. Some EM had greater variation; total estrone varied approximately 12-fold in premenopausal and postmenopausal women. Unconjugated estradiol varied 17-fold in postmenopausal women but only 5-fold in premenopausal women and men. CVs reflecting variation across replicate measures for individuals were <5% for most EM, but higher in some individuals with a low EM concentration. Overall laboratory CVs for all but one EM were <2% and ICCs were >99% for all EM in each group. The serum EM assay has excellent laboratory reproducibility. In premenopausal women, postmenopausal women, and men, interindividual variation in EM measures is substantially greater than laboratory variation. The serum EM assay is suitable for epidemiologic application. See all the articles in this CEBP Focus section, "Biomarkers, Biospecimens, and New Technologies in Molecular Epidemiology."

Analysis of physiobiochemical attributes, some key antioxidants and esculin content through HPLC in in vitro grown Cichorium intybus L. treated with ethylmethane sulfonate

This work covers studies on the effects of different concentrations of EMS (ES0, ES1, ES2, ES3, ES4, and ES5) on biochemical attributes, antioxidant enzymes and esculin content in in vitro grown Chicorium intybus. The bioactive compound esculin in in vitro raised shoots of C. intybus was determined by using high performance liquid chromatography-HPLC. EMS was used to induce in vitro mutagenesis for increase in the production of esculin content. The proline and lipid peroxidation increases with an increase in the concentration of EMS. The soluble protein, sugar content, antioxidant enzymes: superoxide dismutase, ascorbate peroxidase and glutathione reductase increase at lower concentrations of EMS and decrease at higher concentrations. EMS mutagenesis was found to be effective method for inducing increase in secondary metabolite production in C. intybus.

Alteration in anti-oxidant defense system and protein expression in response to varied concentrations of EMS in Psoralea corylifolia

Germplasm of Psoralea corylifolia L., one of the most important endangered medicinal plants of Chinese and Indian Pharmacopeia were treated with ethyl methane sulphonate (0, 0.1, 0.25, 0.50, 0.75 and 1 %) and sampled for observations in the form of growth, non enzymatic systems and stress proteins at pre-and post-flowering stages of development. Higher concentrations of EMS showed significant (P < 0.001) inhibition in the germination percentage from 3.88 to 35.46 % at pre-flowering stage and from 4.90 to 35.97 % at post-flowering stage when compared to control. Other growth related parameters viz shoot growth and root growth also declined within increase in the dose as compared to control plants. Root growth was severely affected as compared to shoot growth. Roots showed a significant correlation with tolerance index as increasing concentration of EMS progressively inhibited the root growth. Plants developed from treated germplasm at higher doses exhibit higher activity of ascorbate peroxidase (APX), up to flowering and after that declined. Contrast to that, total soluble protein (TSP) content decreased in age and dose wise manner. The EMS dose applied and oxidative stress was correlated and derived from the increased antioxidant activities and decrease in total glutathione content from 122.75 % (GSH) and 103.29 % (GSSG) in plants raised from treated germplasm towards the post-flowering stage. Pronounced accumulation of psoralen from 10.74 to 93.24 % was observed following higher doses of EMS at post-flowering stage, where EMS induced oxidative stress-enhanced proline accumulation and lipid peroxidation. In addition, the prevalence of maximum antioxidant activity, psoralen accumulation was an efficient process in acclimatizing P. corylifolia to stress. 2-Dimensional gel electrophoresis (2D-GE) of the protein expression profile and MALDI TOF–MS revealed an expression of 20 different proteins which are associated with such functions as cellular detoxification, stress defense, psoralen production, photosynthesis, signal transduction, and cell cycle. The increase in the psoralen pool after EMS treatment proved to be a best protective antioxidant to counterbalance EMS-induced ROS detoxification and can be used as a biomarker and a scavenger in stress physiology.

Studies on the Effect of EMS and Colchicine in M&lt;sub&gt;1&lt;/sub&gt; Generation of Sesame (&lt;i&gt;Sesamum indicum&lt;/i&gt; L.) Var. TMV3

Seeds of sesame (Sesamum indicum L), genotypeTMV3 were treated with various concentrations of EMS and Colchicine like 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8 and 2.0 % and the LD50 values observed at 1.0 % of EMS and 0.6 % of Colchicine. Based on their LD50 values appreciable concentrations only selected for further study and their effects on various morphological characters such as plant height per plant, number of branches per plant, number of leaves per plant, days to first flowering, number of capsules per plant, number of seeds per capsule and seed yield per plant (g) were measured quantitatively and the results showed that all the characters were consequently or significantly reduced when compared to control and also EMS showed more effective than colchicine.

Development of a Cucumis sativus TILLinG platform for forward and reverse genetics.

BackgroundCucumber (Cucumis sativus) belongs to the Cucurbitaceae family that includes more than 800 species. The cucumber genome has been recently sequenced and annotated. Transcriptomics and genome sequencing of many plant genomes are providing information on candidate genes potentially related to agronomically important traits. To accelerate functional characterization of these genes in cucumber we have generated an EMS mutant population that can be used as a TILLinG platform for reverse genetics.Principal FindingsA population of 3,331 M2 mutant seed families was generated using two EMS concentrations (0.5% and 0.75%). Genomic DNA was extracted from M2 families and eight-fold pooled for mutation detection by ENDO1 nuclease. To assess the quality of the mutant collection, we screened for induced mutations in five genes and identified 26 mutations. The average mutation rate was calculated as 1/1147 Kb giving rise to approximately 320 mutations per genome. We focused our characterization on three missense mutations, G33C, S238F and S249F identified in the CsACS2 sex determination gene. Protein modeling and crystallography studies predicted that mutation at G33 may affect the protein function, whereas mutations at S238 and S249 may not impair the protein function. As predicted, detailed phenotypic evaluation showed that the S238F and the S249F mutant lines had no sexual phenotype. In contrast, plants homozygous for the G33C mutation showed a complete sexual transition from monoecy to andromonoecy. This result demonstrates that TILLinG is a valuable tool for functional validation of gene function in crops recalcitrant to transgenic transformation.ConclusionsWe have developed a cucumber mutant population that can be used as an efficient reverse genetics tool. The cucumber TILLinG collection as well as the previously described melon TILLinG collection will prove to be a valuable resource for both fundamental research and the identification of agronomically-important genes for crop improvement in cucurbits in general.

Studies on the Effect of EMS and Colchicine in M&lt;sub&gt;1&lt;/sub&gt; Generation of Sesame (&lt;i&gt;Sesamum indicum&lt;/i&gt; L.) Var. TMV3

Seeds of sesame (Sesamum indicum L), genotypeTMV3 were treated with various concentrations of EMS and Colchicine like 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8 and 2.0 % and the LD50 values observed at 1.0 % of EMS and 0.6 % of Colchicine. Based on their LD50 values appreciable concentrations only selected for further study and their effects on various morphological characters such as plant height per plant, number of branches per plant, number of leaves per plant, days to first flowering, number of capsules per plant, number of seeds per capsule and seed yield per plant (g) were measured quantitatively and the results showed that all the characters were consequently or significantly reduced when compared to control and also EMS showed more effective than colchicine.

Longitudinal monitoring of sex steroid hormones in excrement of spectacled eiders (Somateria fischeri)

From the 1970s to the 1990s, the breeding population of spectacled eiders (Somateria fischeri) in western Alaska declined by 96%, which led to the listing of this species as threatened under the Endangered Species Act in 1993. Since then, the population has stabilized, but has not recovered to pre-decline numbers. While little is known about reproductive endocrinology in spectacled eiders, in other avian species, estrogen and testosterone are known to initiate and modulate various reproductive processes including yolk protein synthesis, reproductive behaviors and secondary sex characteristics. Measurement of the metabolites of estrogen and testosterone (EM and TM, respectively) in excrement reflect circulating hormone concentrations and provide a non-invasive method to monitor reproductive physiology. We measured concentrations of excreted EM in captive females and TM in males to (1) determine the efficacy of commercially available radioimmunoassay kits to detect EM and TM, (2) describe annual profiles of EM and TM concentrations, and (3) define the reproductive season of captive spectacled eiders using endocrine status. Excrement samples were collected from captive female and male spectacled eiders three times per week throughout 1year. Female EM and male TM levels were quantified using radioimmunoassay. Mean female EM profile exhibited values exceeding the threshold for “peak” values (EM>193.3ng/g) from mid-February to early July, and again in September. Additionally, the highest average concentrations of EM were seen in March, May and September. Elevated TM concentrations occurred in mid March, mid May and late June. These data suggest that levels of excreted sex steroids reflect patterns predicted by breeding landmarks in the annual cycle and will assist in field monitoring and captive breeding programs for spectacled eiders.

Chemo and Radio sensitivity to mutagens in Chilli (Capsicum annuumL.).

The effect of gamma rays, EMS mutagens and their combination on chilli genotypes Kashi anmol (KA-2) and VR-338 (Kashi Gaurav) were investigated in M1 generation to assess the radio and/or chemo sensitivity of different doses. Seeds were irradiated with different concentration of Gamma rays, EMS and combinations. With an increase in doses of Gamma rays, EMS and their combinations, substantial increase in pollen sterility and ovule sterility was reported. Gamma rays were more effective for germination percentage as compared to EMS and their combination in both varieties. Seedling height reduction was predominantly observed in EMS as compared to gamma rays and their combination.

PT-Flax (phenotyping and TILLinG of flax): development of a flax (Linum usitatissimumL.) mutant population and TILLinG platform for forward and reverse genetics

BackgroundFlax (Linum usitatissimum L.) is an economically important fiber and oil crop that has been grown for thousands of years. The genome has been recently sequenced and transcriptomics are providing information on candidate genes potentially related to agronomically-important traits. In order to accelerate functional characterization of these genes we have generated a flax EMS mutant population that can be used as a TILLinG (Targeting Induced Local Lesions in Genomes) platform for forward and reverse genetics.ResultsA population of 4,894 M2 mutant seed families was generated using 3 different EMS concentrations (0.3%, 0.6% and 0.75%) and used to produce M2 plants for subsequent phenotyping and DNA extraction. 10,839 viable M2 plants (4,033 families) were obtained and 1,552 families (38.5%) showed a visual developmental phenotype (stem size and diameter, plant architecture, flower-related). The majority of these families showed more than one phenotype. Mutant phenotype data are organised in a database and can be accessed and searched at UTILLdb (http://urgv.evry.inra.fr/UTILLdb). Preliminary screens were also performed for atypical fiber and seed phenotypes. Genomic DNA was extracted from 3,515 M2 families and eight-fold pooled for subsequent mutant detection by ENDO1 nuclease mis-match cleavage. In order to validate the collection for reverse genetics, DNA pools were screened for two genes coding enzymes of the lignin biosynthesis pathway: Coumarate-3-Hydroxylase (C3H) and Cinnamyl Alcohol Dehydrogenase (CAD). We identified 79 and 76 mutations in the C3H and CAD genes, respectively. The average mutation rate was calculated as 1/41 Kb giving rise to approximately 9,000 mutations per genome. Thirty-five out of the 52 flax cad mutant families containing missense or codon stop mutations showed the typical orange-brown xylem phenotype observed in CAD down-regulated/mutant plants in other species.ConclusionsWe have developed a flax mutant population that can be used as an efficient forward and reverse genetics tool. The collection has an extremely high mutation rate that enables the detection of large numbers of independant mutant families by screening a comparatively low number of M2 families. The population will prove to be a valuable resource for both fundamental research and the identification of agronomically-important genes for crop improvement in flax.

Green tea intake is associated with urinary estrogen profiles in Japanese-American women

ScopeIntake of green tea may reduce the risk of breast cancer; polyphenols in this drink can influence enzymes that metabolize estrogens, known causal factors in breast cancer etiology.Methods and resultsWe examined the associations of green tea intake (<1 time/week, 1-6 times weekly, or 7+ times weekly) with urinary estrogens and estrogen metabolites (jointly EM) in a cross-sectional sample of healthy Japanese American women, including 119 premenopausal women in luteal phase and 72 postmenopausal women. We fit robust regression models to each log-transformed EM concentration (picomoles per mg creatinine), adjusting for age and study center. In premenopausal women, intake of green tea was associated with lower luteal total EM (P trend = 0.01) and lower urinary 16-pathway EM (P trend = 0.01). In postmenopausal women, urinary estrone and estradiol were approximately 20% and 40% lower (P trend = 0.01 and 0.05, respectively) in women drinking green tea daily compared to those drinking <1 time/week. Adjustment for potential confounders (age at menarche, parity/age at first birth, body mass index, Asian birthplace, soy) did not change these associations.ConclusionsFindings suggest that intake of green tea may modify estrogen metabolism or conjugation and in this way may influence breast cancer risk.

Comparison of serum and lithium‐heparinate plasma for the accurate measurements of endogenous and exogenous morphine concentrations

Comparison of serum and lithium‐heparinate plasma for the accurate measurements of endogenous and exogenous morphine concentrations

EMS mutation of suspension cells and selection of high temperature tolerant mutants from Pinellia ternata

To determine the optimal concentration and processing time of EMS mutation for suspension cells from Pinellia ternata. Under four EMS concentration gradients (0.1% , 0.2%, 0.4%, 0.6%) and three processing time gradients (0.5, 1.0, 2.0 h), the suspension cells of P. ternata were mutagenized. The results showed that the survival rate was significantly different under the different concentrations of EMS and the different processing time. In the same processing time, the EMS concentrations were increased, but the suspension cells survival rate decreased gradually. The optimum EMS concentration for the mutagenesis was 0.4% and the best processing time was 1 hour.

Abstract A8: Estrogen metabolism and mammographic density in postmenopausal women

Abstract Estrogens play important roles in the pathophysiology of breast tumors and are recognized causal factors in the etiology of breast cancer. Parent estrogens (estrone and estradiol) can be hydroxylated at the 2, 4, or 16 position of the steroid ring, resulting in metabolites with different biological activity and availability. Estrogen metabolism shows great inter-individual variation, is modifiable, and may contribute to differences among women at risk of breast cancer. We conducted a cross-sectional study to investigate whether urinary estrogens and estrogen metabolites (jointly referred to as EM) are associated with mammographic density (MD), the strongest predictor of sporadic breast cancer risk among women apart from age. Methods: Postmenopausal women without breast cancer, aged 48–82 y, and reporting no current use of exogenous hormones were recruited and interviewed at a mammography clinic in Western NY in 2005. Concentrations of 15 EM were measured in first morning urine samples from 195 participants using liquid chromatography-tandem mass spectrometry. MD (%) was measured using computer-assisted analyses of digitized films. Linear models were used to assess associations of log-transformed EM concentrations and ratios with MD while adjusting for age, body mass index (BMI, kg/m2), and history of combination menopausal hormone therapy. We assessed effect modification by these factors and by years since menopause. Results: The median age of participants was 58, and median time since menopause was 8 years; 35% of participants were obese (BMI ≥30), and 33% had previously used combination menopausal hormones. Among all participants, urinary concentrations of parent estrogens were not associated with MD while some individual 2-pathway and 4-pathway EM had significant inverse associations with MD. Associations between EM profiles and MD were modified by years since menopause (≤8 or &amp;gt;8 y) and by obesity. Among women with a recent menopause, MD was positively associated with parent estrogens (p=0.02), and inversely associated with 2- and 4-hydroxylation pathway EM (p=0.03 and 0.02); these associations were not observed in women with a more distant menopause (pinteraction=0.02, 0.18, 0.16, respectively). Similarly, parent estrogens were directly associated with MD (p=0.003) among women who were obese but not among thinner counterparts (pinteraction=0.08). Conclusion: This is the first study to examine the relations between 15 EM and MD in postmenopausal women. EM profiles were most strongly associated with MD in subgroups with higher estrogen levels including obese women and those with a more recent menopause. In these groups, more extensive 2- and 4-hydroxylation of parent estrogens was associated with reduced MD. This pattern of metabolism may influence MD by facilitating clearance of estrogens from breast tissues. Citation Information: Cancer Prev Res 2011;4(10 Suppl):A8.

Improved production of astaxanthin of the Paracoccus haeundaensis by mutagenesis

Carotenoids are a widely distributed group of naturally occurring pigments and used extensively for natural colorants for food supplements and pharmaceutical applications. Astaxanthin has attracted commercial interest not only as a pigmentation source but also as a potent anti‐oxidative reagent that can delay aging and the onset of degenerative diseases. In addition its anti‐oxidative activity, astaxanthin has been shown to have biological functions as diverse as serving as a vitamin A precursor and modulating the immune system. We have previously reported the isolation of the Paracoccus haeundaensis, which produces astaxanthin. Cultures of Paracoccus haeundaensis were exposed to mutagens. The results showed that the survival rate decreased with the increase in UV exposure time and increase in EMS concentration. The hyper‐production mutant of astaxanthin was produced by UV irradiation (20 min exposure) with EMS treatment (0.4 M concentration). The isolated mutants exhibited an increase of 3.82 folds in astaxanthin production compared to untreated initial strain. This genetically stable mutant strain may be a suitable candidate for the industrial production of astaxanthin.

A comparison of the effects of physical and chemical mutagens in sesame (Sesamum indicum L.)

Three sesame genotypes (Rama, SI 1666 and IC 21706) were treated with physical (γ-rays: 200 Gy, 400 Gy or 600 Gy) or chemical (ethyl methane sulphonate, EMS: 0.5%, 1.0%, 1.5% or 2.0%) mutagens and their mutagenic effectiveness and efficiency were estimated in the M 2 generation. The M 3 generation was used to identify the most effective mutagen and dose for induction of mutations. The average effectiveness of EMS was much higher than γ-rays. The lowest dose of γ-rays (200 Gy) and the lowest concentration of EMS (0.5%) showed the highest mutagenic efficiency in all genotypes. Analysis of the M 3 generation data based on parameters such as the variance ratio and the difference in residual variances derived from the model of Montalván and Ando indicated that 0.5% concentration of EMS was the most effective treatment for inducing mutations.

Dominance of mutations affecting viability in Drosophila melanogaster.

There have been several attempts to estimate the average dominance (ratio of heterozygous to homozygous effects) of spontaneous deleterious mutations in Drosophila melanogaster, but these have given inconsistent results. We investigated whether transposable element (TE) insertions have higher average dominance for egg-to-adult viability than do point mutations, a possibility suggested by the types of fitness-depressing effects that TEs are believed to have. If so, then variation in dominance estimates among strains and crosses would be expected as a consequence of variation in TE activity. As a first test, we estimated the average dominance of all mutations and of copia insertions in a set of lines that had accumulated spontaneous mutations for 33 generations. A traditional regression method gave a dominance estimate for all mutations of 0.17, whereas average dominance of copia insertions was 0.51; the difference between these two estimates approached significance (P = 0.08). As a second test, we reanalyzed Ohnishi 1974 data on dominance of spontaneous and EMS-induced mutations. Because a considerable fraction of spontaneous mutations are caused by TE insertions, whereas EMS induces mainly point mutations, we predicted that average dominance would decline with increasing EMS concentration. This pattern was observed, but again fell short of formal significance (P = 0.07). Taken together, however, the two results give modest support for the hypothesis that TE insertions have greater average dominance in their viability effects than do point mutations, possibly as a result of deleterious effects of expression of TE-encoded genes.

Development of a photofragmentation laser-induced-fluorescence laser sensor for detection of 2,4,6-trinitrotoluene in soil and groundwater

Laser photofragmentation (PF) and subsequent nitric oxide (NO) laser-induced fluorescence (LIF) have been developed to measure the concentration of energetic materials (EM's), such as 2, 4, 6-trinitrotoluene (TNT), in soil and other media. Gas-phase EM's photodissociate, releasing NO(2), when exposed to laser radiation near 226 nm. Laser-excited NO(2) predissociates to form NO that gives an intense fluorescence when excited near 226 nm. The EM concentration is inferred from the intensity of the NO fluorescence. A PF-LIF laser-based sensor is being developed to be used with the U.S. Army Corps of Engineers' Waterways Experiment Station's cone penetrometer to measure in situ the concentration of subsurface TNT. Several factors that affect the PF-LIF signal waveforms, such as sample temperature, laser power, and heating time, were investigated. Also, effects on the PF-LIF signal of adding water and fertilizer to the TNT mixtures were studied. Decay times were determined by least-squares fitting of the exponential PF-LIF signal waveforms. The use of PF-LIF waveforms promises to enable diagnostics of the sample's characteristics that would otherwise not be possible in situ.

Eficiência de utilização da energia metabolizável para ganho de peso e exigências de energia metabolizável, nutrientes digestíveis totais e proteína metabolizável de bezerros da raça holandesa

Este trabalho visou avaliar os efeitos de diferentes níveis de volumoso nas dietas, sobre a eficiência de utilização de energia metabolizável (EM) para mantença e ganho de peso e as exigências de EM, nutrientes digestíveis totais (NDT) e proteína metabolizável (PM). Quarenta e quatro bezerros Holandeses, puros por cruzamento, não-castrados, com idade média de 60 dias e peso vivo inicial de 78 kg foram usados. Oito animais foram abatidos ao início do experimento, como referência. Os 36 animais restantes foram distribuídos nos tratamentos, em delineamento inteiramente casualizado, em quatro grupos de nove animais, de acordo com o nível de volumoso nas dietas: 10, 25, 40, e 55%, na base da MS, usando-se feno de capim coast-cross (Cynodon dactylon), fubá de milho e farelo de soja, os quais constituíram dietas com aproximadamente 16% de PB. Cinco animais de cada tratamento foram abatidos quando atingiram 190 ± 10 kg e quatro, quando atingiram 300 ± 10 kg. As concentrações de energia líquida das dietas e as eficiências de utilização da EM para mantença e ganho de peso foram calculadas. As eficiências de utilização de EM para ganho de peso foram estimadas, por meio de análise de regressão, entre a energia líquida para ganho (ELg), em função da EM das dietas. As exigências médias diárias de EM, nutrientes digestíveis totais (NDT) e proteína metabolizável (PM) foram estimadas. As exigências de EM para ganho de 1 kg de peso corporal vazio aumentaram, à medida que se elevou o PCVZ dos animais. As eficiências de utilização da energia metabolizável para ganho de peso em: 0,45; 0,40; 0,40 e 0,39, respectivamente, para as concentrações de 2,98; 2,76; 2,64 e 2,53 Mcal/kg de MS, obtidas para os níveis de 10; 25; 40 e 55% de volumoso nas dietas foram estimadas. As exigências médias totais de EM e de NDT para animais de 100, 200 e 300 kg de peso vivo foram de 10,06; 14,45 e 18,12 Mcal/dia e 2,79; 4,00 e 5,02 kg/dia, respectivamente. A eficiência de utilização da EM para ganho foi maior para dietas com menor nível de volumoso.

2,4,6-Trinitrotoluene detection by laser-photofragmentation–laser-induced fluorescence

Photofragmentation (PF) and subsequent nitric oxide (NO) laser-induced fluorescence (LIF) is being developed to measure the concentration of energetic materials (EM's) in soil and other media. Laser radiation near 226 nm photodissociates gas-phase EM to NO(2), which predissociates into NO that gives an intense luminescence. The EM concentration is inferred from the intensity of the NO fluorescence. We have studied the factors that affect the PF-LIF signal intensity, including the effect of buffer gas on the LIF spectrum of pure NO, the effect of 2,4,6-trinitrotoluene (TNT) pressure on the PF-LIF spectrum, the effect of buffer-gas pressure on the PF-LIF signal intensity of pure TNT, and the effect of temperature on the PF-LIF spectra of pure TNT and of TNT in simulated soil. Heating of the TNT sample above 343 K was found to increase the magnitude of the PF-LIF signal intensity significantly, but also was found to cause physical and chemical changes in the TNT sample. The effects of heating and evacuating on the TNT sample were investigated. TNT concentration calibration curves were obtained for TNT in simulated soil mixtures. The limit of detection of TNT in soil was estimated to be 40 parts in 10(9).