Approach of white box mathematical modelling was used to develop dynamic mathematical model of glycerol cycle in baker's yeast Saccharomyces cerevisiae and by deterministic simulations explore an interaction between glycerol cycle and glycolysis. The key process in research was reaction of artificially expressed glycerol-2-dehydrogenase (Gld2) which catalyses glycerol transition into dihydroxyacetone and reduced nicotinamide adenine dinucleotide phosphate (NADPH). We put forward hypothesis that expression of Gld2 in S. cerevisiae could increase concentration of reduced cytosolic NADPH. Michaelis-Menten equation was used to describe a rate law of reactions of the model of glycerol cycle. Kinetic parameters Km (Michaelis - Menten constant) and Vmax (maximal velocity of reaction) were taken from BRENDA database and publications. To perform deterministic simulations of the model of glycerol cycle and glycolysis, an accomplished model of glycerol cycle was introduced into the mathematical model of glycolysis of Nielsen et al. (1998). Results suggested that Gld2 reaction could run even without glycolysis as long as glycerol and oxidized nicotinamide adenine dinucleotide phosphate (NADP+) was present in the system. Intracellular concentration of glycerol had a direct impact on formation and acumulation of dihydroxyacetone. Reduced nicotinamide adenine dinucleotide (NADH) concentration decreased significantly and rapidly when glycerol cycle was switched on suggesting that it could be a limiting factor of the system.

Informatics is profoundly reshaping social relations and changing pupils’ education. A goal was set to offer the pupils an integrated informatics learning content, orientated to develop an emotionally and intellectually equilibrated and harmonic personality. The aim of the paper is to characterize the integration in the content of the subject of informatics and research the realisation of integrated learning material in educational practice. Subjects in the school curricula provide concrete guidelines on knowledge, skills and attitudes that should be taught and what goals and purposes their education program follows. To establish the understanding of pupils on development of taste in integrated informatics subject, an educational experimentation was conducted. The data are obtained by using a pretest-post-test design and analysis of teaching-learning informatics in classroom. Pupils at Lielvarde secondary school were asked to involve for learning a new integrated informatics material for developing their understanding of taste. The method of analysis of aesthetic and pedagogical literature and data processing and analysis by Wilcoxon signed-rank Test and Chi-square test are used. Pupils undertook independent practical tasks at the computer with the aim of developing their knowledge and cognitive skills (understanding, selection, reflection). Learning integrated informatics material is a pedagogical condition for fostering the development of pupils’ understanding of taste. Learning integrated informatics material executed diverse practical tasks with choice of color match, ethnographic characters and making a portfolio which enriched pupils' experience of taste and effectuated as acquisition of their cognitive skills.

Grain after enzymatic treatment, which is a starch-containing raw material, is used for ethanol production. Bioethanol production in Latvia began in 2006. Extraction of biofuels is a clean process, because the byproduct is used in various sectors of the economy. The bioethanol in Latvia was derived primarily from winter wheat, winter rye, and winter triticale. The objective of the research is to determine the different nitrogen fertiliser rates required for winter cereal crop yields and bioethanol outcome. The trials were carried out from 2005 to 2008 in Agricultural Science Centre of Latgale (Latvia). The method (ethanol outcome) is based on fermentation of saccharified cereal samples by yeast Saccharomyces cerevisiae followed by the calculation of ethanol outcome and speed of fermentation. The highest starch content was in winter wheat and winter triticale grain, but the lowest - in winter rye grains. A close negative correlation (p is less than 0.05) was found for winter triticale and winter wheat between the ethanol outcome and thousand grain weight. Production of bioethanol from rye starch content is used with full utilisation of grain. The winter wheat has the largest ethanol outcome from one hectare.

Maize (Zea mays L.) is one of the agricultural plants that is suitable substrate for biogas production. Fresh as well as ensiled maize can be used as biogas substrate. Practically, mainly maize silage is used because fresh maize is available only for short term during the vegetative period. The paper is aimed to determine the impact of ensiling on substrate composition of maize hybrids. A field trial was carried out in the Research and Study farm ''Vecauce'' of the Latvia University of Agriculture (LLU) in 2008 and 2009. Ten (in 2008) to eleven (2009) maize hybrids with different maturity rating according to FAO numbers (FAO 180 – 340) were harvested at three different times beginning on 5 September at fourteen-day intervals. Chopped maize samples of 1-3 kg were ensiled in plastic silos. Samples of fresh and ensiled (for at least 90 days) maize were analyzed detecting 14 parameters in the Scientific Laboratory of Agronomy Research of LLU using standard methods. Our results showed that ensilaging influence on organic dry matter and hemi-cellulose content was not substantial. High (p is less than 0.05) correlation between organic dry matter content of fresh and ensiled samples was noted. The crude protein, crude fibre, ash and cellulose concentration was greater in the ensiled samples if compared with fresh maize samples in 2008 and 2009. After ensilaging process neutral detergent fibre (NDF) concentration was higher compared with fresh samples in 2009 but lower in 2008.

The investigation was done at the Latvia State Institute of Fruit-Growing in Dobele in 2009, on the basis of an established field experiment planted in 1997 with apple (Malus domestica Borh.) cultivar 'Melba' (rootstock B9) trees spaced at 1.5 × 4 m distances. Three different treatments of soil moisture management were compared: control, sawdust mulch and fertigation. Soil of the experimental plot was Haplic Luvisol (Hypereutric), sandy loam, interspaced with Cutanic Luvisol, sandy loam. Organic matter – 25 g kgE-1, soil reaction pH – 6.5. Plant available P was 130.9, K – 157.7, and Mg – 102.2 mg kgE-1. The aim of the investigation was to determine nitrogen removal with fruit yield taking into consideration the used soil moisture regulation method – sawdust mulch or fertigation. The applied soil moisture regulation methods (mulch and fertigation) had significant influence on the content of dry matter in apple fruits (p is less than 0.05). The highest content of dry matter was found in the control treatment. A significantly higher nitrogen concentration (47 g kgE-1) in apple dry matter was in the control treatment, whereas in mulch and fertigation treatments nitrogen concentrations were lower (36 and 42 g kgE-1). The highest nitrogen concentration in dry matter was found in fruits with the biggest mass (r=0.61). A negative significant (p is less than 0.05) correlation was found between nitrogen concentration and trunk diameter (r=–0.85), and between nitrogen concentration and yield (r=–0.84). Removal of N was 24.4 kg haE-1 in the control, 22.3 kg haE-1 in the mulch, and 25.0 kg haE-1 in the fertigation treatment.

The lily (Lilium L.), a vegetative propagated perennial crop, is one of the economically most important flower bulb plants. It is cultivated worldwide as a cut flower, garden plant and pot plant. Lilies, 'the aristocrats of the garden', are very popular for their elegant flowers and stately habit, and offer the gardener an enormous range of colours, forms, and fragrances. The aim of this research was to evaluate the parent plants with the hybrids according to their morphological characteristics: plant height, flower diameter and inflorescence: number of flowers. In a trial, fourteen cross combinations were analyzed in 2006 – 2007. The evaluation was conducted in a lily breeding and growing farm 'Puķulejas', located in Saulkrasti, region of Riga, Latvia. The results showed that, if there were no significant differences in plant height between the parent plants, the hybrids were shorter than their parents. Male parents with short stems produced hybrids with shorter stems. Parental selections of medium and large number of flowers produced hybrids with comparatively large numbers of flowers on a stem, but if parents of different number of flowers were selected, in hybrids the smaller count dominated or prevailed.

Genotypes of CSN3 gene were detected in 71 individuals of Latvian Blue breed and in 30 individuals of Latvian Brown breed using a PCR-RFLP method. Animals were chosen at random from each heard. This study investigated the alleles A and B of CSN3 gene, while determining the allele and genotype frequencies and Hardy-Weinberg equilibrium proportions in both populations. The results showed that in our analyzed samples from 71 Latvian Blue breed only 7 animals (10%) had the genotype BB, and in analyzed samples from 30 Latvian Brown breed only 3 had the genotype BB (10%). Frequencies of CSN3 genotypes AA, AB, and BB correspond to Hardy-Weinberg equilibrium proportions and populations in genetic equilibrium. A wide variation in the B allele frequency among Latvian Blue and Latvian Brown breeds was found suggesting that molecular selection for animals carrying the allele B of CSN3 could impact breeding programs for dairy production in Latvia.

Barley is a key ingredient in beer production. The aim of the current research was to study the dynamics of vitamin C and vitamin E in flaky and hull-less barley grains during steeping, germinating, and kilning. The research was accomplished on hull-less barley (two lines – '3528' and '3537') and flaky barley selected in Latvia in 2009 with a germination capacity above 95%. The grains were steeped, germinated and kilned using traditional malt production technology. During research the vitamin content was analysed using standard methods: vitamin C by EN 14130:2003, and vitamin E by AOAC 971.30. The content of vitamin C increased during steeping in flaky barley grains till 0.23 mg 100 gE-1, but in hull-less barley grains: line '3537' till 0.47 mg 100 gE-1, and line '3528' till 0.30 mg 100 gE-1. During germination vitamin C content in flaky barley increased by 68%, in hull-less barley: line '3528' – by 82%, and line '3537' – by 57%. The content of vitamin C in the analysed malt samples was 0.35-0.38 mg 100 gE-1. The content of vitamin E in all barley samples was similar after grain steeping. The content of vitamin E was 3.9 times higher in flaky barley, but in hull-less barley lines: '3528' – 4.1, and '3537' – 4.5 times higher compared with its initial content after germination. After grain kilning, the content of vitamin E decreased in all barley grain samples. The results show that using some cultivars of hull-less barley for malt production, it is possible to obtain a higher content of vitamins C and E in the end-product.

Nowadays one of most urgent problems is the production of healthy food which ensures normal maintenance of the human body. Rye bread is one of the bases of wholesome food. Every year scientists in Europe and other countries carry out investigations on the nutritional impact of processing rye. Interesting questions arise regarding changes in the biologically active compounds in rye bread as a result of processed. Connate antiradical activity (ARA) of rye bread affects free radicals by scavenging or donating electrons, which suggests that the ARA of rye bread averts attacks of free radicals on human cells. Therefore it is important to use antioxidants containing products with antiradical activity in human diets. The aim of this study was to analyse the impact of baking processing on rye bread antiradical activity. The object of the study was Latvian traditional rye bread baked in a commercial bakery, made with scald, and baked in a clay-floor firewood oven. The antiradical activity of rye bread crumb and crust was measured by using free radical 2.2-diphenyl-1-picrylhydrazyl (DPPH). It was concluded in the research that rye flour type 1740 has antiradical activity by scavenging 67 μmol·100gE-1 DM of the stable free radical DPPH, which is 13% more than the dough antiradical activity of the same flour. The antiradical activity of the crust is 49.6% more than the antiradical activity of the crumb. Baking time has no significant impact on changes in the antiradical activity of rye bread crumb.

The content of carbohydrates (fructose, glucose, and sucrose) and organic acids (citric acid, succinic acid, malic acid, sorbic acid, and ascorbic acid (vitamin C)) in organically grown vegetables (carrots, parsnips, celeriacs, and red beets) and dried vegetable products were analyzed by the HPLC reverse phase and ion exchange methods. The main carbohydrate detected in fresh vegetables invariably was sucrose (1.29 – 11.17 g 100 gE-1). Fructose and glucose were found in similar ranges (0.09 – 2.47 g 100 gE-1, 0.14 – 3.02 g 100 gE-1 respectively). A similar distribution of carbohydrates was determined in dried products. The highest fructose and glucose contents were found in fresh carrots - 2.47 g 100 gE-1 and 3.02 g 100 gE-1 respectively; but in dried carrot products – 14.53 g 100 gE-1 and 15.43 g 100 gE-1. High amounts of sucrose were found in red beets: 11.17 g 100 gE-1 in fresh samples, and 48.50 g 100 gE-1 in dried products. Malic and citric acids were detected as the main acids of fresh vegetables. Highest citric acid amount was in red beets (266.19 mg 100 gE-1), whereas celeriacs and parsnips had a high malic acid content. The results from this study demonstrated variability and concentration range of carbohydrates and organic acids, wherewith the organoleptic profile of the products. Dried products are considered as a good source of energy.