Assessment of radiosensitivity from the germination of jute seeds

Irradiation with X-rays and gamma rays reduced the speed of germination of seeds of jute cultivars,viz., JRO 632, JRO 620, Sudan Green ofCorchorus olitorius and JRC 212, Fanduk, D 154 ofC. capsularis. Though the first phase of germination(i.e. seed variability) remained apparently unaffected, the second phase (i.e. the sprouting ability) and the third phase(i.e. the attainment of autotrophic status) were found to be the best indicators of radiation injury and provided dependable data for the assessment of radiosensitivity. The jute cultivars have not shown accountable intervarietal differences in radiosensitivity in respect of LD 50 and LD 100 for the second and the third phases of germination.     

Content of low-molecular-weight thiols during the imbibition of Pea seeds

The metabolism of low-molecular-weight thiols was investigated in seeds of Pisum sativum L. cv. Kleine Rheinländerin during imbibition in water for 14 h. The amount of oxidized glutathione (GSSG) decreased from 319 nmol (g dry weight)⁻¹ in dry seeds to 38 nmol (g dry weight)⁻¹ within the first 14 h of imbibition. The decrease may have been due to the reduction of GSSG to reduced glutathione (GSH), catalyzed by the enzyme glutathione reductase (GR; EC 1.6.4.2). The enzyme activity was high in dry seeds [25 nkat (g dry weight)⁻¹] and decreased to 20 nkat (g dry weight)⁻¹ within 14 h of imbibition. The activity of glucose-6-phosphate dehydrogenase (EC 1.1.1.49) decreased from 100 nkat (g dry weight)⁻¹ in dry seeds to 67 nkat (g dry weight)⁻¹ after 14 h of imbibition. Within 14 h the amount of γ-glutamyl-cysteine (γ-GC) decreased from 135 to 38 nmol (g dry weight)⁻¹, whereas the cysteine content rose from 81 nmol (g dry weight)⁻¹ in dry seeds to a maximum of 170 nmol (g dry weight)⁻¹ after 12 h of imbibition, which may be due to the degradation of γ-GC into cysteine.     

An in vitro micronucleus assay for determining the radiosensitivity of hepatocytes

An in vitro micronucleus assay was developed for primary cultures of rat hepatocytes and utilized to determine the oxygen enhancement ratio (OER). Freshly isolated Fischer 344 female rat hepatocytes were irradiated in suspension either in air or in anoxia, cultured for 60 h to allow for the maximum expression of micronuclei, fixed with methanol-glacial acetic acid, stained with the fluorescent dye 4',6-diamidino-2-phenylindole (DAPI), and scored with a fluorescent microscope for the presence of micronuclei. The percentage of cells with micronuclei increased linearly with dose, and the slopes of the relationships were 0.044 +/- 0.001 Gy-1 and 0.015 +/- 0.001 Gy-1 in air and anoxia, respectively. The calculated OER of 2.9 +/- 0.5 is similar to that previously obtained for hepatocyte cell survival. Our data demonstrate that this in vitro hepatocyte micronucleus assay is a rapid and sensitive method to further investigate those factors which influence the radiosensitivity of hepatocytes.     

小麦种子内携真菌多样性研究

为揭示小麦种子所携带真菌的种类和多样性,丰富小麦相关微生物的可利用资源,我们对来自俄罗斯、澳大利亚、哈萨克斯坦、加拿大以及中国的57份小麦种子样品进行内携真菌分离并对其中的21份种子利用高通量测序进行多样性分析.结果显示,分离获得564株真菌,经ITS序列分析结合形态观察鉴定为31属69种,其中菌株数量相对多度最高的5...     

Monitoring the seeds of chronically irradiated native populations of Plantago lanceolata L. The radiosensitivity of seeds

The method of provocative gamma-irradiation was used to study the radiosensitivity of seeds of three first post-accident reproductions of Plantago lanceolata L. within the thirty kilometer zone of Chernobyl. The radiation injury was severer among seeds taken in 1987-1988 from the areas with a higher level of radioactive contamination.     

Nomograms for determining the parameters for a probabilistic model of radiosensitivity

Nomograms are introduced for the determination, from the experimental survival curves, of a and b parameters of the probabilistic model of cell radiosensitivity (proposed by Kapul'tsevich, 1978). The parameter errors are estimated too. Some examples of using these nomograms for bacteria, yeast and mammalian cells are considered.     

Dehydration tolerance in spring wheat seeds

Studies performed on seeds of several cultivars of spring wheat (Triticum aestivum L. var.lutescens) revealed differences in the studied seed dehydration tolerance affecting seed germination and seedling emergence. Among the cultivars studied, seeds of Kolibri showed capability to maintain both high germination energy and high emergence rate at diminished water potential of the environment. Seed dehydration tolerance was increased when the parent plants were subjected to drought. This work was supported by Project No. 9.1.1. coordinated by the Plant Breeding and Acclimatization Institute.     

Polyamine accumulation in aged wheat seeds

The present work was conducted to evaluate the content of the main polyamines (Spm, Spd, Put) in a series of naturally aged durum-wheat seeds as well as the activities of the enzymes ODC and ADC involved in their biosynthesis. In dry seeds the content of polyamines, especially that of Spd, rose during ageing till 6 years and then declined sharply. However, an increase of PA content upon imbibition was observed only with the youngest seeds, while a decrease was found in the older ones. The activities of ODC and ADC differed in aged seeds, the ODC activity being constant and lower than the ADC in the course of seed ageing. The ADC increased till the early ageing and decreased then in the very old, ungerminating seeds. Imbibition increased both enzyme activities in the youngest seeds only, in the older ones rather a decrease and changed ADC/ODC ration was found. The obtained results are discussed in relation to the participation of these enzymes in the biosynthesis of polyamines during seed ageing and in the course of plant senescence or stress.     

Interaction of factors modifying the radiosensitivity of dormant seeds: a review

A review is presented on modification of radiation-induced effects in dormant plant seeds. Possible sources of discrepancy of data in the earlier literature are analysed. Approaches to the correct experimental study of mechanisms of interaction of environmental factors in the modification of radiobiological reactions are discussed. Progress in the radiation biology of plant seeds, achieved by precise control of experimental conditions, is considered.