Effects of chromosome reconstruction of barley genome on tissue culture response using two different regeneration systems

Mature embryos and seedlings from mature embryos of one standard and five reconstructed karyotypes of barley (Hordeum vulgare L.) were cultured in vitro to study the influence of repositioning of particular chromosome segments of barley genome on the regeneration response. A comparative analysis of the regeneration response of a reconstructed karyotype having complete and well characterized rearrangement of the chromosome complement, and its four parental lines were used as experimental material. Depending on the source of explants two systems of in vitro culture were applied. The regeneration ability was found to be significantly influenced by both chromosome reconstruction and protocol applied. Possible reasons underlying the effects of chromosomal reconstruction on the regeneration response of karyotypes are briefly discussed.     

Short-term effect of elevated CO2 concentration and high irradiance on the antioxidant enzymes in bean plants

The effect of short-term exposure to elevated CO₂ concentration and high irradiance on the activity of superoxide dismutase (SOD), ascorbate peroxidase (APX), guaiacol peroxidases (GPX) and catalase (CAT), and on the extent of the lipid peroxidation was studied in bean (Phaseolus vulgaris L.) plants. Plants were exposed for 4 d (8 h a day) to irradiance of 100 (LI) or 1000 (HI) μmol m⁻² s⁻¹ at ambient (CA, 350 μmol mol⁻¹) or elevated (CE, 1300 μmol mol⁻¹) CO₂ concentration. Four-day exposure to CE increased the leaf dry mass in HI plants and RuBPC activity and chlorophyll content in LI plants. Total soluble protein content, leaf dry matter and RuBPC activity were higher in HI than in LI plants, although the HI and CE increased the contents of malonyldialdehyde and H₂O₂. Under CA, exposure to HI increased the activity of APX and decreased the total SOD activity. Under CE, HI treatment also activated APX and led to reduction of both, SOD and GPX, enzymes activities. CE considerably reduced the CAT activity at both irradiances, possibly due to suppressed rate of photorespiration under CE conditions.     

Electrically induced protoplast fusion using pulse electric fields for dielectrophoresis

The formation of protoplast chains in suspensions of isolated pea (Pisum sativum cv Ran 1) mesophyll protoplasts induced by electric fields was studied. The chain formation induced by a sine-wave field (2 V, peak to peak; 500-0.1 kHz) was compared to that induced by an alternating pulse field (1 V, amplitude; 0.1-0.4 kHz). An increased number of dielectrophoretically paired protoplasts, formation of protoplast chains in the presence of CaCl₂ up to 5 mm, and protoplast fusion in the presence of 3 mm CaCl₂ were found when the pulse field was applied. The present results suggest the possibility of electrically induced protoplast fusion at cation concentrations that prevent fusion when sine-wave fields are applied.     

Modification of the carbohydrate composition of sulfite pulp by purified and characterized beta-xylanase and beta-xylosidase of Aureobasidium pullulans

Both beta-xylanase and beta-xylosidase were purified to homogeneity from a xylose-grown culture of Aureobasidium pullulans. Cellular distribution studies of enzyme activities revealed that beta-xylanase was an extracellular enzyme, during both the exponential and stationary phases, whereas beta-xylosidase was mostly periplasmic associated. The beta-xylanase exhibited very high specificity for xylan extracted from Eucalyptus grandis dissolving pulp, whereas the beta-xylosidase was only active on p-nitrophenyl xyloside and xylobiose. Comparison of kcat/Km ratios showed that the beta-xylanase hydrolyzed xylan from dissolving pulp 1.3, 2.1, and 2. 3 times more efficiently than Eucalyptus hemicellulose B, Eucalyptus hemicellulose A, and larchwood xylan, respectively. The beta-xylosidase exhibited a transxylosylation reaction during the hydrolysis of xylobiose. When applied on acid sulfite pulp, both enzymes released xylose and hydrolyzed xylan to a different extent. Although beta-xylosidase (0.4 U/g pulp) liberated more xylose from pulp than beta-xylanase (4.7 U/g pulp), it was responsible for only 3% of xylan solubilization. Treatment of pulp with beta-xylanase liberated 51.7 microgram of xylose/g and hydrolyzed 10% of xylan. The two enzymes acted additively on pulp and removed 12% of pulp xylan. A synergistic effect in terms of release of xylose from pulp was observed when the enzyme mixture of beta-xylanase and beta-xylosidase was supplemented with beta-mannanase. However, this did not result in further enzymatic degradation of pulp xylan. Both beta-xylanase and beta-xylosidase altered the carbohydrate composition of sulfite pulp by increasing the relative cellulose content at the expense of reduced hemicellulose content of pulp.     

Prevalence of the Metabolic Syndrome in a Bulgarian Female Population Referred for Bone Density Testing

Objective: To investigate the prevalence of the metabolic syndrome in Bulgarian women referred for bone density screening. Research Methods and Procedures: This was a cross‐sectional clinical study. Subjects were 444 consecutive 30‐ to 75‐year‐old Bulgarian women recruited from the outpatients referred for bone density testing (mean age, 52.67 ± 15.19 years; mean BMI, 26.10 ± 5.71 kg/m²). Height (centimeters), weight (kilograms), and blood pressure were measured. BMI and waist‐to‐hip ratio were calculated. Fasting plasma glucose, blood lipids, and immunoreactive insulinemia (Bayer Corp.‐Diagnostics Div., Tarrytown, NY) were determined. Body composition was analyzed by bioimpedance on a leg‐to‐leg analyser (Tanita TBF‐215; Tanita Corporation, Tokyo, Japan). Results: Of all women, 56.76% had a BMI > 25 kg/m², 45.95% had a waist circumference > 88 cm, and 64.64% had a waist‐to‐hip ratio > 0.8; 59.90% had hypertension; 4.05% had fasting plasma glucose > 7.0 mM, and 42.79% had fasting morning immunoreactive insulinemia = 16 UI/liter; 23.65% had hypercholesterolemia; and 26.35% had hypertriglyceridemia. The prevalence of the metabolic syndrome in this sample, as defined by the National Cholesterol and Education Program‐Adult Treatment Panel III, was 34.91%, and by the modified World Health Organization definition was 37.16%. Discussion: We concluded that Bulgarian women 30 to 75 years old referred for bone density testing have a high prevalence of the metabolic syndrome. Therefore, large‐scale prevention programs are needed in this field.     

Cell population kinetics and DNA content during thyroid carcinogenesis

The proliferation kinetics and DNA content of thyroid follicular cells in rats were studied by autoradiography and cytophotometry. Continuous treatment of animals with methylthiouracil (MTU) results in hyperplasia followed by tumour growth in the thyroid gland. The mitotic index (MI) increases from 0.006 +/- 0.002% in controls to 0.13 +/- 0.06% in hyperplasia and to 0.09 +/- 0.03% in malignant cells. The same is true for the labelling index (LI) which rises from 0.08 +/- 0.003% in controls to 1.4 +/- 1.1% in hyperplasia and to 1.0 +/- 0.6% in follicular adenomas. The S-phase duration (TS) is shortened from 8.0 +/- 1.2 hr in controls to 6.0 +/- 1.4 hr in animals treated for 9 months with MTU and prolonged to 15.4 +/- 2.1 hr in papillary carcinomas. In all MTU-treated animals a decrease in the value of the potential population doubling time (TPD) and thyroid weight doubling time (TD) was observed. The cell loss factor (phi) decreases in animals treated for 3 months with MTU and increases during the stage of tumour growth in the gland (animals treated 12-15 months with MTU). DNA measurements in the nuclei of hyperplastic and neoplastic thyroid tissues reveal cells with values exceeding that in control animals. However, no difference was found in the DNA content between thyroid adenomas and carcinomas, nor between thyroid hyperplasia and neoplasia.     

Cell Population Kinetics and Dna Content During Thyroid Carcinogenesis

The proliferation kinetics and DNA content of thyroid follicular cells in rats were studied by autoradiography and cytophotometry. Continuous treatment of animals with methylthiouracil (MTU) results in hyperplasia followed by tumour growth in the thyroid gland. the mitotic index (MI) increases from 0.006 ± 0.002% in controls to 0.13 ± 0.06% in hyperplasia and to 0.09 ± 0.03% in malignant cells. the same is true for the labelling index (LI) which rises from 0.08 ± 0.003% in controls to 1.4 ± 1.1% in hyperplasia and to 1.0 ± 0.6% in follicular adenomas. the S-phase duration (T_s) is shortened from 8.0 ± 1.2 hr in controls to 6.0 ± 1.4 hr in animals treated for 9 months with MTU and prolonged to 15.4 ± 2.1 hr in papillary carcinomas. In all MTU-treated animals a decrease in the value of the potential population doubling time (T_PD) and thyroid weight doubling time (T_D) was observed. the cell loss factor (ø) decreases in animals treated for 3 months with MTU and increases during the stage of tumour growth in the gland (animals treated 12–15 months with MTU). DNA measurements in the nuclei of hyperplastic and neoplastic thyroid tissues reveal cells with values exceeding that in control animals. However, no difference was found in the DNA content between thyroid adenomas and carcinomas, nor between thyroid hyperplasia and neoplasia. During the last decade numerous autoradiographic studies have been performed on the cell population kinetics of benign and malignant tumours in animals and man (Steel, 1977; Tubiana & Malaise, 1977). It has been established that cell proliferation is an important parameter in both the initiation and promotion phases of carcinogenesis (Oehlert, 1973; Berenblum, 1979). Cell kinetic studies during carcinogenesis have predominantly dealt with the liver (Rajewsky, 1967; Chernozemski & Warwick, 1970), skin (Raick, 1974), the mammary gland (Bresciani, 1965; Nagasawa, Yanai & Nagigushi, 1976b), the uterine cervix (Nagasawa, Matsuura & Tojo, 1976a) and intestinal cells (Tutton & Barka, 1966; Pozharisski, Klimashewski & Gushin, 1977). Information on the changes in cell population kinetics during thyroid carcinogenesis is still incomplete. Data reported in the literature are mainly devoted to the short-term effects of goitrogens and radiation factors (Santler, 1957; Sheline, 1969; Philip, Crooks & MacGregor, 1969; Wynford-Stringer & Williams, 1982; Redmond & Tuffery, 1981). The present study was carried out to investigate if changes in the cell population kinetics and DNA content occur during thyroid carcinogenesis, as well as if thyroid adenomas and carcinomas differ in their proliferative potential and DNA content.     

Genomic analysis of the relationship between gene expression variation and DNA polymorphism in Drosophila simulans

Background

Understanding how DNA sequence polymorphism relates to variation in gene expression is essential to connecting genotypic differences with phenotypic differences among individuals. Addressing this question requires linking population genomic data with gene expression variation.

Results

Using whole genome expression data and recent light shotgun genome sequencing of six Drosophila simulans genotypes, we assessed the relationship between expression variation in males and females and nucleotide polymorphism across thousands of loci. By examining sequence polymorphism in gene features, such as untranslated regions and introns, we find that genes showing greater variation in gene expression between genotypes also have higher levels of sequence polymorphism in many gene features. Accordingly, X-linked genes, which have lower sequence polymorphism levels than autosomal genes, also show less expression variation than autosomal genes. We also find that sex-specifically expressed genes show higher local levels of polymorphism and divergence than both sex-biased and unbiased genes, and that they appear to have simpler regulatory regions.

Conclusion

The gene-feature-based analyses and the X-to-autosome comparisons suggest that sequence polymorphism in cis-acting elements is an important determinant of expression variation. However, this relationship varies among the different categories of sex-biased expression, and trans factors might contribute more to male-specific gene expression than cis effects. Our analysis of sex-specific gene expression also shows that female-specific genes have been overlooked in analyses that only point to male-biased genes as having unusual patterns of evolution and that studies of sexually dimorphic traits need to recognize that the relationship between genetic and expression variation at these traits is different from the genome as a whole.     

Degradation of keratin and collagen containing wastes by newly isolated thermoactinomycetes or by alkaline hydrolysis

AIMS: The aim of this study was to develop a method for microbial degradation of indigenous keratin wastes and to compare it with a method of alkaline hydrolysis. METHODS AND RESULTS: Native sheep skin and wool were chosen as a model mixture of collagen and keratin wastes discarded by the leather and fur industries. Suitable conditions were found for hydrolysis of this mixture by four newly isolated thermoactinomycete strains. Another set of experiments was carried out using alkaline hydrolysis of keratin wastes. It was shown that microbial hydrolysates contained predominantly low molecular peptides and amino acids, including essential ones, while the alkaline hydrolysis produced predominantly peptides of higher molecular weight. CONCLUSION: A simple and a low-cost method was proposed for rapid and effective biodegradation of keratin wastes using Thermoactinomyces strains. SIGNIFICANCE AND IMPACT OF THE STUDY: The proposed method could find application in agriculture for preparing mixtures containing valuable peptides and amino acids.     

A NuRD Complex from Xenopus laevis Eggs Is Essential for DNA Replication during Early Embryogenesis

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