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Detalles de la revista
Formato
Revista
eISSN
2719-9509
Publicado por primera vez
01 Jan 1992
Periodo de publicación
4 veces al año
Idiomas
Inglés

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Volumen 19 (2000): Edición 1 (April 2000)

Detalles de la revista
Formato
Revista
eISSN
2719-9509
Publicado por primera vez
01 Jan 1992
Periodo de publicación
4 veces al año
Idiomas
Inglés

Buscar

4 Artículos
Acceso abierto

Genetic Variability in Nicotianatabacum and Nicotiana Species as Revealed by RAPD Markers: 1. Development of the RAPD Procedure

Publicado en línea: 30 Dec 2014
Páginas: 1 - 15

Resumen

Abstract

At present there is no information about the level of genetic variability in N. tabacum and in the Nicotiana genus as revealed by random amplified polymorphic DNA (RAPD). Such knowledge could be useful for taxonomic and breeding purposes. The aim of this paper is to assess the potential application of the DNA polymorphisms generated by RAPD markers within this genus and in tobacco. As rigorously standardized reaction conditions are required to obtain a reproducible RAPD marker, four rapid DNA extraction methods were compared and several parameters of the reaction conditions for the random polymorphic DNA amplification were analysed and optimized. The DNA of six-week-old leaves of N. tabacum var. Samsun was obtained with the following methods differing in the strategy of purification: the cetyltrimethylammonium bromide (CTAB) method, that of Edwards, nucleon phytopure system and the method of Goring. Reproducible amplification profiles were obtained with all the methods except for Edwards'. As regards amplification conditions, the effects of primer-template annealing temperature, of a final extension step, of the number of cycles and of the length of extension time in each cycle were analysed. Moreover, the effects on amplification reaction of the DNA amount, of MgCl2, primer and deoxynucleotide triphosphate (dNTP) concentration were evaluated. Then DNA of 12 Nicotiana species and Nicotianatabacum was amplified with primers OPA-01 and OPA-13 which revealed a considerable polymorphism. The same primers used to analyse 36 var. of N. tabacum belonging to different types, showed identical amplification profiles. Further amplification experiments were carried out with only 12 of the tobacco lines; three primers among the 12 assayed revealed one polymorphic fragment each.

Acceso abierto

Investigations on the Genetics of Resistance to Root-knot Nematodes (Meloidogyne incognita) in Tobacco (Nicotianatabacum)

Publicado en línea: 30 Dec 2014
Páginas: 17 - 23

Resumen

Abstract

The analysis of a full diallel cross of ten tobacco varieties showed that genetic control of resistance to root-knot nematodes (Meloidogyne incognita) in tobacco was governed by partial dominance. When measuring the overall genetic variance, the portion of additive variance was found to be very substantial. This property may well be inherited by progenies and with a high degree of heritability (0.60-0.63). Partitioning the total sums of squares of the genotypes into the sum of squares for general (GCA) and specific combining ability (SCA) of parents and hybrids points to additive and non-additive gene activities in generating resistance to root-knot nematodes in tobacco. Because of significant reciprocal differences, the maternal cytoplasm plays an important role in the inheritance of resistance to root-knot nematodes. The proportion of additive and heritable variance was significant and to such an extent (60 %) that a selection for resistant lines might be a promising project. Since some varieties show a high GCA for resistance, they could be regarded as donors for resistance for progenies. In addition, the significantly high SCA and resistance of several hybrids would suggest successful selection of lines with resistance to root-knot nematodes in tobacco.

Acceso abierto

Determination of Dibenzacridines in the Particulate Phase of Cigarette Smoke

Publicado en línea: 30 Dec 2014
Páginas: 25 - 31

Resumen

Abstract

This study attempted to resolve a controversy related to the presence of dibenz[a,j]acridine and dibenz[a,h]acridine in the particulate phase of cigarette smoke. Smoking was performed using FTC conditions (35 mL puff volume, 2 sec. puff, 1 min. interval) on a Borgwaldt RM 20/CS smoking machine. The particulate phase of forty cigarettes was collected on 92 mm Cambridge filter pads. Pads were combined to analyze the particulate phase of the mainstream smoke from between 120 and 320 cigarettes. In an initial scheme of analysis, the pads were extracted with an acidic aqueous solution. This aqueous solution was then washed with CH2Cl2 and the organic phase discarded. The aqueous solution was then changed to basic and extracted with CH2Cl2, which was concentrated and analyzed via GC/MS. The dibenzacridine could not be detected utilizing this scheme, even when the pads had been spiked with a few thousand nanograms of dibenzacridine. After using several other organic solvents (cyclohexane, CHCl3, and benzene) to eliminate the possibility that the extraction efficiency of CH2Cl2 was poor, it was determined that dibenzacridine was being discarded with the first CH2Cl2 wash. A successful separation scheme was developed by extracting the smoked pad with an aqueous acidic solution, followed by extraction of the aqueous phase with CH2Cl2without pH change. The CH2Cl2 extract was concentrated under nitrogen and 1 µL injected for GC/MS analysis. Quantification was achieved by spiking the pads with dibenz[a,j]acridine-d13 as an internal standard at a level equal to 1.7-2.5 ng/cig. The limit of detection for this technique was approximately 0.5 ng/cig. The chromatographic separation was performed with a 30 m BPX-5 column (0.25 mm i.d., 0.25 µm film thickness). Mass spectral data were acquired in selected ion monitoring (SIM) mode with m/z = 279 for the two dibenzacridine isomers and m/z = 292 for the deuterated internal standard. Three commercial cigarettes were analyzed: two commercial Full Flavor cigarettes, one commercial Light cigarette, and a 1R4F reference cigarette. Neither dibenzacridine isomer was detected in any of the samples analyzed.

Acceso abierto

A Simple Technique for Determining the pH of Whole Cigarette Smoke

Publicado en línea: 30 Dec 2014
Páginas: 33 - 48

Resumen

Abstract

A new technique has been developed to determine the pH of whole cigarette smoke. In this technique, whole smoke from ten cigarettes was trapped in 300 mL water containing 1% (w/v) sodium chloride and the pH was determined on the resulting aqueous suspension of cigarette smoke. Two impingers with an extra coarse porosity fritted disc were used to dispense the smoke in the aqueous trapping medium. Cigarettes were smoked on a 20-port Borgwaldt RM 20/CS smoking machine using modified FTC (Federal Trade Commission) conditions. The puff volume was adjusted to take a 35 mL puff as measured through the cigarette and the collection traps. This new technique accounts for the contributions to smoke pH from both the vapor phase and the particulate phase of smoke. The repeatability of this new technique was determined on eighteen replicates of a commercially available non-menthol, filter cigarette. Each measurement was done on a different day to check for a possible drift in pH with time. The mean pH value for the chosen sample was found to be 4.97 with a standard deviation of 0.07 pH units. The smoke pH values for over 150 commercially available cigarette brands with a variety of “tar” levels were determined. The smoke pH values had a range from 4.6 to 5.5, with an average of 4.79 and a maximum standard deviation of 0.10 pH units. An experimental flue cured cigarette had a smoke pH of around 5.0, while an experimental Burley cigarette had a smoke pH of 5.4. No correlation between smoke pH and “tar” or total particulate matter (TPM) and between pH and nicotine levels was found. The purpose of the present study was to develop a practical, relatively simple laboratory method to measure the pH of a water solution of whole smoke, and was not intended to reflect, or have direct relevance for any biochemical or biological phenomena such as inhalability of smoke, flavor perception, nicotine ab-sorption, etc.”

4 Artículos
Acceso abierto

Genetic Variability in Nicotianatabacum and Nicotiana Species as Revealed by RAPD Markers: 1. Development of the RAPD Procedure

Publicado en línea: 30 Dec 2014
Páginas: 1 - 15

Resumen

Abstract

At present there is no information about the level of genetic variability in N. tabacum and in the Nicotiana genus as revealed by random amplified polymorphic DNA (RAPD). Such knowledge could be useful for taxonomic and breeding purposes. The aim of this paper is to assess the potential application of the DNA polymorphisms generated by RAPD markers within this genus and in tobacco. As rigorously standardized reaction conditions are required to obtain a reproducible RAPD marker, four rapid DNA extraction methods were compared and several parameters of the reaction conditions for the random polymorphic DNA amplification were analysed and optimized. The DNA of six-week-old leaves of N. tabacum var. Samsun was obtained with the following methods differing in the strategy of purification: the cetyltrimethylammonium bromide (CTAB) method, that of Edwards, nucleon phytopure system and the method of Goring. Reproducible amplification profiles were obtained with all the methods except for Edwards'. As regards amplification conditions, the effects of primer-template annealing temperature, of a final extension step, of the number of cycles and of the length of extension time in each cycle were analysed. Moreover, the effects on amplification reaction of the DNA amount, of MgCl2, primer and deoxynucleotide triphosphate (dNTP) concentration were evaluated. Then DNA of 12 Nicotiana species and Nicotianatabacum was amplified with primers OPA-01 and OPA-13 which revealed a considerable polymorphism. The same primers used to analyse 36 var. of N. tabacum belonging to different types, showed identical amplification profiles. Further amplification experiments were carried out with only 12 of the tobacco lines; three primers among the 12 assayed revealed one polymorphic fragment each.

Acceso abierto

Investigations on the Genetics of Resistance to Root-knot Nematodes (Meloidogyne incognita) in Tobacco (Nicotianatabacum)

Publicado en línea: 30 Dec 2014
Páginas: 17 - 23

Resumen

Abstract

The analysis of a full diallel cross of ten tobacco varieties showed that genetic control of resistance to root-knot nematodes (Meloidogyne incognita) in tobacco was governed by partial dominance. When measuring the overall genetic variance, the portion of additive variance was found to be very substantial. This property may well be inherited by progenies and with a high degree of heritability (0.60-0.63). Partitioning the total sums of squares of the genotypes into the sum of squares for general (GCA) and specific combining ability (SCA) of parents and hybrids points to additive and non-additive gene activities in generating resistance to root-knot nematodes in tobacco. Because of significant reciprocal differences, the maternal cytoplasm plays an important role in the inheritance of resistance to root-knot nematodes. The proportion of additive and heritable variance was significant and to such an extent (60 %) that a selection for resistant lines might be a promising project. Since some varieties show a high GCA for resistance, they could be regarded as donors for resistance for progenies. In addition, the significantly high SCA and resistance of several hybrids would suggest successful selection of lines with resistance to root-knot nematodes in tobacco.

Acceso abierto

Determination of Dibenzacridines in the Particulate Phase of Cigarette Smoke

Publicado en línea: 30 Dec 2014
Páginas: 25 - 31

Resumen

Abstract

This study attempted to resolve a controversy related to the presence of dibenz[a,j]acridine and dibenz[a,h]acridine in the particulate phase of cigarette smoke. Smoking was performed using FTC conditions (35 mL puff volume, 2 sec. puff, 1 min. interval) on a Borgwaldt RM 20/CS smoking machine. The particulate phase of forty cigarettes was collected on 92 mm Cambridge filter pads. Pads were combined to analyze the particulate phase of the mainstream smoke from between 120 and 320 cigarettes. In an initial scheme of analysis, the pads were extracted with an acidic aqueous solution. This aqueous solution was then washed with CH2Cl2 and the organic phase discarded. The aqueous solution was then changed to basic and extracted with CH2Cl2, which was concentrated and analyzed via GC/MS. The dibenzacridine could not be detected utilizing this scheme, even when the pads had been spiked with a few thousand nanograms of dibenzacridine. After using several other organic solvents (cyclohexane, CHCl3, and benzene) to eliminate the possibility that the extraction efficiency of CH2Cl2 was poor, it was determined that dibenzacridine was being discarded with the first CH2Cl2 wash. A successful separation scheme was developed by extracting the smoked pad with an aqueous acidic solution, followed by extraction of the aqueous phase with CH2Cl2without pH change. The CH2Cl2 extract was concentrated under nitrogen and 1 µL injected for GC/MS analysis. Quantification was achieved by spiking the pads with dibenz[a,j]acridine-d13 as an internal standard at a level equal to 1.7-2.5 ng/cig. The limit of detection for this technique was approximately 0.5 ng/cig. The chromatographic separation was performed with a 30 m BPX-5 column (0.25 mm i.d., 0.25 µm film thickness). Mass spectral data were acquired in selected ion monitoring (SIM) mode with m/z = 279 for the two dibenzacridine isomers and m/z = 292 for the deuterated internal standard. Three commercial cigarettes were analyzed: two commercial Full Flavor cigarettes, one commercial Light cigarette, and a 1R4F reference cigarette. Neither dibenzacridine isomer was detected in any of the samples analyzed.

Acceso abierto

A Simple Technique for Determining the pH of Whole Cigarette Smoke

Publicado en línea: 30 Dec 2014
Páginas: 33 - 48

Resumen

Abstract

A new technique has been developed to determine the pH of whole cigarette smoke. In this technique, whole smoke from ten cigarettes was trapped in 300 mL water containing 1% (w/v) sodium chloride and the pH was determined on the resulting aqueous suspension of cigarette smoke. Two impingers with an extra coarse porosity fritted disc were used to dispense the smoke in the aqueous trapping medium. Cigarettes were smoked on a 20-port Borgwaldt RM 20/CS smoking machine using modified FTC (Federal Trade Commission) conditions. The puff volume was adjusted to take a 35 mL puff as measured through the cigarette and the collection traps. This new technique accounts for the contributions to smoke pH from both the vapor phase and the particulate phase of smoke. The repeatability of this new technique was determined on eighteen replicates of a commercially available non-menthol, filter cigarette. Each measurement was done on a different day to check for a possible drift in pH with time. The mean pH value for the chosen sample was found to be 4.97 with a standard deviation of 0.07 pH units. The smoke pH values for over 150 commercially available cigarette brands with a variety of “tar” levels were determined. The smoke pH values had a range from 4.6 to 5.5, with an average of 4.79 and a maximum standard deviation of 0.10 pH units. An experimental flue cured cigarette had a smoke pH of around 5.0, while an experimental Burley cigarette had a smoke pH of 5.4. No correlation between smoke pH and “tar” or total particulate matter (TPM) and between pH and nicotine levels was found. The purpose of the present study was to develop a practical, relatively simple laboratory method to measure the pH of a water solution of whole smoke, and was not intended to reflect, or have direct relevance for any biochemical or biological phenomena such as inhalability of smoke, flavor perception, nicotine ab-sorption, etc.”

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