Browse

1 - 10 of 2,066 items :

  • General Interest x
Clear All
Application of Metabolomic Analysis in Exploration of Plant Genetic Resources

Abstract

The article addresses the issues of using metabolomic analysis to study genetic resources of cereal crops in order to (1) determine phylogenetic linkages between species (the degree of domestication); (2) within species to describe genetic diversity according to its responses to biotic and abiotic stressors and biochemical characteristics (chemical compounds) determining food, feed and technological quality indicators; and (3) select the most resistant and highest-quality geno-types for complex breeding use.

Open access
Content of Phenolic Compounds and Antioxidant Activity in Fresh Apple, Pomace and Pomace Water Extract — Effect of Cultivar

Abstract

The study aimed to evaluate the chemical composition (total phenol, flavonoid, and tannin content and the antioxidant activity) of 11 apple (Malus domestica) cultivars in fresh apples and their processing by-products — apple pomace and its water extract. In addition, the proportion of chemical compounds and antioxidant activity in fresh apples and pomace transferred to the resulting water extract was calculated. Three different season’s cultivars (autumn–winter, winter and late winter) were selected in the research, and significant differences between chemical parameters within groups were found. Cultivars ‘Zarja Alatau’, ‘Belorusskoje Malinovoje’, ‘Sinap Orlovskij’ and ‘Antej’ are characterised by a higher content of determined compounds in fresh apples, pomace and po-mace water extract. The results showed that the water extract in relation to fresh apples and apple pomace still contains an appropriate amount of total phenols, flavonoids and tannins in the range 2.5–9.6%. These results indicated that apple pomace water extracts could be recommended for use in food as well as in the pharmaceutical industry.

Open access
Editors’ Note
Open access
Effect of Soil Properties on the Spread of Heterobasidion Root Rot

Abstract

The literature review focuses on the effect of forest soil properties on infection of coniferous trees and stumps by Heterobasidion spores and further growth of mycelium from tree to tree. Spread of the fungus is greater in alkaline soil. Forest plantations on former agricultural lands have an increased risk of infection, due to lack of antagonistic soil microorganisms. In Latvia, severe infection of spruce stands by Heterobasidion root rot has been observed on peat soils.

Open access
Extension of Critical Difference for Product Comparison. Application to Tobacco Products

Summary

The differences or equivalence of products depend on various sources of variability like analytical methods, manufacturing processes, agricultural practices and environmental conditions. In addition, the capacity to compare and discriminate accurately two products is impacted by the number of characteristics considered for the comparison. Previously, it has been shown that a comparison of two products can be performed using the critical difference (CD), because it takes into consideration both the variability of measurements and laboratories. However, some additional sources of variability need to be added in the comparison when products were not manufactured at the same period of time or in the same factory. Here, an extended critical difference is proposed including manufacturing process variability according to the number of samples and batches collected for each product. The general formula and specific cases corresponding to different situations (one vs two labs, short vs long periods of time, same vs different periods of time, one vs several batches) are given.

Open access
Gas Chromatography-Tandem Mass Spectrometry Method for Selective Detection of 2-Nitropropane in Mainstream Cigarette Smoke

Summary

Although 2-nitropropane is a potentially harmful compound present in cigarette smoke, there are few fully-validated, modern methods to quantitate it in mainstream cigarette smoke. We developed an isotope dilution gas chromatography-tandem mass spectrometry (ID-GC-MS/MS) method for the detection of 2-nitropropane in mainstream cigarette smoke. The vapor fraction of mainstream cigarette smoke was collected in inert polyvinyl fluoride gas sampling bags and extracted with hexanes containing isotopically labeled internal standard, then purified and concentrated via solid-phase extraction using a normal phase silica adsorbent and a 100% dichloromethane eluant. This method is sensitive enough to measure vapor phase 2-nitro-propane concentrations in the nanogram range, with a 19 ng per cigarette method limit of detection. Product variability estimated from the analysis of 15 cigarette products yielded relative standard deviations ranging from 5.4% to 15.7%, and estimates of precision from two quality control products yielded relative standard deviations of 9.49% and 14.9%. Under the Health Canada Intense smoking regimen, 2-nitropropane in machine-generated mainstream smoke from 15 cigarette products ranged from 98.3 to 363 ng per cigarette.

Open access
Genetic and Agronomic Analysis of Latvian Fescue (Festuca Spp.), Ryegrass (Lolium Spp.) Accessions and their Hybrids

Abstract

The development of ecologically adaptable fodder crop varieties is of increasing importance, particularly in the context of climate change. New varieties should be phenotypically and ecologically plastic and able to adapt to differing climactic and soil conditions, ensuring high yields and persistence. Combining Festuca and Lolium species and the development of hybrid (Festulolium) cultivars can be a promising method of combining high yield, high feed quality, persistence, as well as cold, frost and drought tolerance. Breeders at the Institute of Agriculture of Latvia University of Life Sciences and Technologies have been utilizing Festulolium germplasm for several decades. Currently, in cooperation with the molecular genetics laboratory and Latvian gene bank at the Latvian State Forest Research Institute “Silava”, analysis of Festuca, Lolium and their hybrids with DNA markers has been initiated, in order to gain additional knowledge about the breeding material and to increase the efficiency of the breeding process. Results of the assessment of morphological and agronomic traits in long-term field trials are combined with DNA markers analyses in order to determine the correlation of genetic and phenotypic traits.

Open access
High-Temperature X-Ray Diffraction and Fluorescence Spectra of SnSe Single Crystal

Abstract

The temperature dependence of unit cell parameters was studied using high-temperature X-ray diffraction and the coefficient of thermal expansion of SnSe single crystal was determined. Fluorescence spectra of SnSe single crystal grown by the Bridgman-Stockbarger method were examined using a Cary Eclipse spectrophotometer at room temperature in the wavelength range 200–900 nm. When the samples were irradiated by a pulse at a wavelength of 230 nm, the fluorescence spectra exhibited maxima at wavelengths 313.07, 423.03, 458.93, 495.07, and 530.00 nm.

Open access
Jānis Oļģerts Ērenpreiss and his School of Cancer Research: Commemorating the 90th Anniversary

Abstract

Jānis Olģerts Ērenpreiss (1929–1996) was a prominent Latvian cancer researcher and theoretician. Starting out as a student, he contributed to the embryonal theory of cancer, experimentally proving the differentiation and regenerative normalisation capabilities of tumour cells. His theoretical work, presented in its most complete form in his final monograph Current Concepts of Malignant Growth (Zinātne Publ., Rīga, 1993), postulates that oncogenes are abnormally activated genes that are involved in gametogenesis and embryogenesis, and that carcinogenesis and senescence are mutually linked processes arising when the cell is exposed to stressful conditions. This article demonstrates how advancements in cancer research over the last decade have confirmed these core concepts, which were far ahead of their time, and how J. O. Ērenpreiss’ legacy continues both under the guidance of the author and in foreign laboratories, expanding understanding of the nature of malignant tumours and the perspectives of cancer treatment.

Open access