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  • Author: J Liu x
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Partial Purification and Characterization of Proteases in Tobacco Leaf and Callus

Abstract

Ammonium sulfate fra.ctionation, gel permeation and cation-exchange column chromatography were employed for panial purification of proteases from leaf laminae and callus tissues of Samsun NN tobacco (Nicotiana tabacum L). The predominant proteases in the leaf and callus are acidic sulfhydryl proteases which are activated by 2-mercaptoethanol and ethylenediamine tetraacetic acid, completely inhibited- by iodoacetic acid, and partially inhibited by phenylmethane sulfonyl fluoride and pepstatin A. With hemoglobin and tobaccl:l Fraction I protein as substrates, leaf and callus proteases showed a pH optimum of 5. However, specific activity was significandy higher in the callus than in the leaf. Tobacco proteases digested hemoglobin more effectively than Fraction I protein and showed the least activity with casein. Gel permeation resolved three -protease variants in leaf extracts but only two in callus samples. Rechromatography of the large molecular weight fraction in a cation-exchange column produced three and two variants for leaf and callus, respectively. The present results suggest that there are at least five variants of sulfhydryl protease in tobacco leaf and three in callus tissue and that tobacco Fraction I protein can be metabolized by both leaf and callus proteases.

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Gradients analyses of forests ground vegetation and its relationships to environmental variables in five subtropical forest areas, S and SW China

Gradients analyses of forests ground vegetation and its relationships to environmental variables in five subtropical forest areas, S and SW China

Monitoring of ground vegetation and environmental variables in subtropical forests in China was initiated in 1999 as part of the "Integrated Monitoring Programme of Acidification of Chinese Terrestrial Systems". The study areas were selected to span regional gradients, in deposition of airborne pollutants and climatic conditions. All five study areas are located in the southern and south-western parts of China and consist of subtropical forests. In each study area 50 1-m2 plots were randomly chosen within each of ten 10×10 m macro plots, each in turn positioned in the centre of 30×30 m extended macro plot. All 250 1-m2 plots were subjected to vegetation analysis, using frequency in subplots as measure of species abundance. A total of 33 environmental variables were recorded for 1-m2 plots as well as 10×10 m macro plots. A major objective of this study is to identify the environmental variables that are most strongly related to the species composition of ground vegetation in S and SW Chinese subtropical forests, as a basis for future monitoring.

Comparison among DCA, LNMDS and GNMDS ordination methods, an additional objective of the study, was achieved by using a set of different techniques: calculation of pair-wise correlation coefficients between corresponding ordination axes, Procrustes comparison, assessment of outlier influence, and split-plot GLM analysis between environmental variables and ordination axes. LNMDS and GNMDS consistently produce very similar ordinations. GNMDS ordinations are generally more similar to DCA than LNMDS to DCA. In most cases DCA, LNMDS and GNMDS extract the same main ground vegetation compositional gradients and the choice of LNMDS or GNMDS is therefore hardly decisive for the results. GNMDS was chosen for interpretation and presentation of vegetation-environment relationships. The dimensionality of GNMDS (number of reliable axes) was decided by demanding high correspondence of all axes with DCA and LNMDS axes. Three dimensions were needed to describe the variation in vegetation in two of the areas (TSP and LXH), two dimensions in the other three areas (LCG, LGS and CJT).

Environmental interpretation of ordinations (identification of ecoclines; gradients in species composition and the environment) was made by split-plot GLM analysis and non-parametric correlation analysis. Plexus diagrams and PCA ordination were used to visualize correlations between environmental variables. Several graphical means were used to aid interpretation.

Complex gradients in litter-layer depth, topography, soil pH/soil nutrient, and tree density/crown cover were found to be most strongly related to vegetation gradients. However, the five study areas differed somewhat with respect to which of the environmental variables that were most strongly related to the vegetation gradients (ordination axes). Litter-layer depth was related to vegetation gradients in four areas (TSP, LCG, CJT and LXH); topography in four study areas (TSP, LGS, CJT and LXH); soil pH in three areas (LCG, LGS and CJT); soil nutrients in one area (LGS); and tree density/crown cover in one area (LCG).

The ecological processes involved in relationships between vegetation and main complex-gradi-ents in litter-layer depth, topography, soil pH/soil nutrient, and tree density/crown cover, in subtropical forests, are discussed. We find that gradient relationships of subtropical forests are complex, and that heavy pollution may increase this complexity. Furthermore, our results suggest that better knowledge of vegetation-environment relationships has potential for enhancing our understanding of subtropical forests that occupy vast areas of the S and SW China.

Open access
Cigarette Mouth Insertion Depths Among Chinese Smokers

Abstract

Vent blocking - where filter ventilation holes are intentionally or unintentionally, partly or completely covered by smokers’ lips during smoking - is an aspect of smoking behavior which can alter mainstream smoke yields. This study was designed to determine if, and to what extent ventilation holes were blocked by smokers’ lips in two cohorts of Chinese smokers. In this study, two groups of samples were collected. One group (1742 butts) was collected randomly from public places in six chosen cities. Another (1037 butts) was obtained by collecting the butts from identified smokers in Kunming. In this paper, the mouth insertion depth among Chinese smokers was studied for the first time by a staining method employing ninhydrin in ethanol. The results indicate that Chinese smokers exhibit a mouth insertion depth ranging from 1 to 17 mm with an average value of 7.5 AA± 2 mm. In this study, 95% of the ventilated filters examined showed that the vent zone was neither completely nor partially covered by smokers’ lips.

Open access
Arsenic Speciation in Tobacco and Cigarette Smoke

Abstract

Arsenic is one of the metals found in cured tobacco and mainstream cigarette smoke. Levels of arsenic in modern filtered cigarette smoke range from sub-ppm to a few tens of ppms. To enable accurate smoke toxicity assessment on arsenic in cigarette smoke, it is desirable to establish its chemical forms in addition to total quantities because different arsenic compounds possess different toxicological potentials.

Progress has been made on measuring the arsenic speciation in tobacco and mainstream cigarette smoke by using a combination of synchrotron-based X-ray absorption spectroscopy and high-performance liquid chromatography- inductively coupled plasma mass spectrometry (HPLC-ICP-MS). In this paper, we describe the experimental procedures developed together with the main findings. A transient redox transformation between As(V) and As(III) was confirmed in freshly generated mainstream smoke. Potential areas for future research are highlighted in order to further our understanding of the speciation mechanism for arsenic in tobacco products.

Open access
Synthesis of 3-Oxo-α-ionol Ethyl Carbonate and its Conversion to Megastigmatrienones in Tobacco Smoke

Abstract

3-Oxo-α-ionol ethyl carbonate, a precursor of megastigmatrienones was prepared by reduction of α-ionone to α-ionol, followed by esterification with ethyl chloroformate and then by oxidation with t-butyl chromate. The total yield was about 23%. Infrared (IR) and mass spectra of this compound were determined. Upon smoking, cigarettes to which 0.002% by weight of the titled compound was added had an improved and more harmonious flavor. The smoke was sweeter and had a cleaner after taste. Experimental results suggest that the title compound added to the tobacco pyrolyzes to form megastigmatrienones during smoking.

Open access
Genetic and clinical analysis of nonsyndromic hearing impairment in pediatric and adult cases

Abstract

Previous studies have linked GJB2 gene and mitochondrial DNA (mtDNA) mutations to nonsyndromic hearing impairment (NSHI), but no study in China has yet investigated these mutations across all age groups. To fill the gap, this study ascertained 263 patients with NSHI between ages 2 months and 60 years and analyzed the presence of GJB2 gene and mtDNA A1555G/C1494T mutations by polymerase chain reaction (PCR) and DNA sequencing. A total of 20 types of mutations were detected for the GJB2 gene. The GJB2 gene and mtDNA A1555G/C1494T mutations were detected in 18.63 and 11.41% cases, respectively. At the first hospital visit, GJB2 gene mutations were detected in 5.97% of adult patients (>18 years) and 22.96% pediatric patients (<18 years) (χ2 =9.506, p = 0.002), and mtDNA A1555G/C1494T mutations were detected in 31.34% of adult patients and 4.59% of pediatric patients (χ2 = 35.359, p <0.001). When patients were classified by age at onset of deafness, significantly more (20.68%) pediatric patients had GJB2 gene mutations than did adult patients (0.0%) (χ2 = 4.685; p = 0.006). Mitochondrial DNA A1555G/C1494T mutations were detected in 15.38% of adult-onset and 8.86% pediatric-onset patients, respectively. Interestingly, most GJB2 gene mutation carriers experienced NSHI onset within the first year of life (65.31%), while mtDNA A1555G/C1494T mutation carriers experienced onset at any age. Therefore, GJB2 gene mutations appear to contribute to congenital deafness, while mtDNAA1555G/C1494T mutations contribute mainly to acquired deafness in Chinese individuals. Both newborn hearing screening and genetic testing are important to diagnose and treat deafness.

Open access
Detection of circulating antigens in serum samples of mice experimentally infected with Trichinella spiralis by a sandwich ELISA based on IgY

Abstract

In the present study, a sandwich ELISA based on IgY (egg yolk immunoglobulin) was developed for detection of circulating antigens (CAg) in sere of mice experimentally infected with Trichinella spiralis. The IgY-sandwich ELISA assay involved the use of chicken antibody IgY against excretory-secretory (ES) antigens of Trichinella spiralis muscle larvae as a capture antibody and mouse polyclonal antibody IgG to ES antigens as a detecting antibody. This method was able to detect as little as 3 ng/ml of ES antigens added to normal mouse serum. A group of sixteen mice was orally inoculated with 500 T. spiralis muscle larvae per animal. The serum samples from the infected mice were taken during 1–35 days post-infection (dpi). The CAg was detectable as early as 8 dpi in the sera of infected mice. The level of CAg increased dramatically during 13–15 dpi and reached a peak at 22 dpi and remained a plateau for 3 days, then declined gradually. Another peak of CAg occurred at 31 dpi. The anti-Trichinella antibodies was first detected in 14.3 % of the infected mice at 2 weeks post-infection (wpi), and reached a peak positive rate of 100 % at 5 wpi. Moreover, the infected mice were treated with abendazole at 5 wpi and the serum CAg levels increased significantly during 2–6 days posttreatment (dpt) and then declined rapidly during 8–14 dpt. By 42 dpt, the CAg levels decreased to the undetected level, but the detection rate of antibodies was still 100 %. The IgY-sandwich ELISA appears to be a sensitive for detection of antigenemia of T. spiralis and valuable to judge the efficacy of chemotherapy in trichinellosis.

Open access
Analysis of meiotic segregation patterns and interchromosomal effects in sperm from 13 robertsonian translocations

Abstract

The frequency of the Robertonian (ROB) translocation in newborn babies is approximately one in 1000. Robertsonian translocation is an unusual type of chromosome rearrangement caused by two particular chromosomes joining together. The aim of the study was to analyze the segregation of the ROB translocations in 13 male carriers, and to verify a possible inter-chromosomal effect (ICE) of the ROB translocation on chromosomes 18, X, and Y. Thirteen male patients were included in the study. Multicolor fluorescent in situ hybridization (FISH) was used to analyze chromosomes 13, 14, 15, 21, 22, 18, X and Y in sperm. Among the heterozygous ROB translocation carriers, the frequency of normal/balanced spermatozoa resulting from alternate segregation varied between 70.4 and 85.2%. The frequency of unbalanced spermatozoa resulting from adjacent segregation varied between 14.8 and 29.6%. Increased frequencies of aneuploidy for a sex chromosome were found in 10 ROB translocation carriers (P2-P8, P10-P12). Increased frequencies of aneuploidy for chromosome 18 were found in10 ROB translocation carriers (P3-P9, P11-P13). In addition, increased frequencies of diploid were found in 11 ROB translocation carriers (P2-P9, P11-P13). Among the homozygous ROB translocation carriers, the rate of balanced spermatozoa was 99.7% and the frequency of unbalanced spermatozoa was 0.3%. However, the frequencies of aneuploidy for a sex chromosome and chromosome 18 were normal. Despite the high number of normal/balanced frequencies, there remained many unbalanced spermatozoa resulting from alternate segregation. The ROB translocation carriers may be at an increased risk for ICE. Robertsonian translocation homozygosity could be seen as a potential speciation in humans with 44 chromosomes.

Open access
Genetic Variation in the Qinghai-Tibetan Plateau Endemic and Endangered Conifer Cupressus gigantea, Detected Using RAPD and ISSR Markers

Abstract

Assessing the level and distribution of genetic diversity of rare tree species is essential for their management and the development of effective conservation strategies. Cupressus gigantea is a long-lived endemic cypress of the west Qinghai-Tibetan Plateau and the tallest tree in its genus. The current populations of this species are fragmented and highly disturbed. We used RAPD (Random Amplified Polymorphic DNA) and ISSR (Inter-Simple Sequence Repeat amplification) markers to assess the genetic variation and population structure of this endangered cypress. The 15 RAPD primers used in this study amplified 108 reproducible bands, 49 (45.4%) of which were polymorphic, while the 12 ISSR primers amplified 94 bands, 65 (69.2%) of which were polymorphic. Analysis of Molecular Variance (AMOVA) indicated that 49.7% and 38.3% of the variation was attributable to differences between populations for the RAPD and ISSR markers, respectively; relatively high compared to values reported for other conifer species. These estimates were also similar to Gst values obtained from Nei’s gene diversity analyses (RAPD = 0.41 and ISSR = 0.36), and suggest that there is a high degree of population differentiation in this narrowly-distributed conifer. The genetic structure of this species has probably been shaped by its long life cycle and climatic changes during the Quaternary. The high degree of population differentiation in this species highlights the need for additional conservation measures, including measures to protect of all of the remaining populations. The substantial similarities between the results of the RAPD and ISSR analyses of samples from the same individuals indicate that they can be interpreted with high levels of confidence.

Open access
A facile synthesizing method of vanadium dioxide by pyrolyzing ammonium metavanadate

Abstract

A facile process was developed for synthesizing vanadium dioxide (VO2) by pyrolyzing ammonium metavanadate (NH4VO3) in nitrogen flow. The process was designed on the base of thermodynamic modeling of chemical reaction and thermal analyzing of NH4VO3 pyrogenation in N2 gas, and optimized by experiments. X-ray diffraction (XRD), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) were applied to characterizing the product VO2. Thermo-gravimetric analysis (TG) and DSC were used for analyzing the process of NH4VO3 pyrogenation. The experimental results indicated that VO2 microcrystal particles were successfully synthesized. The product VO2 presents two kinds of micro morphologies, torispherical and pentagonal prism. The phase transition mainly takes place at 338.4 K and 341.9 K. The average enthalpy of the phase transition is 28.82 J/g.

Open access