Food habits of wolvesCanis lupus in Latvia

Diet of wolvesCanis lupus Linnaeus, 1758 in Latvia was studied from 1997 to 2001 based on 302 scats and 107 stomachs. Wild ungulates (cervids and wild boarSus scrofa) and beaverCastor fiber were the dominant prey. Cervids were found in 50% of samples (62% biomass), wild boar in 25% (21% biomass), beavers in 14% (12% biomass). Wolves selected for wild boar, especially in winter when its ratio in the diet increased to 34% from 20% in summer. It was a more common prey species in the east of the country. The ratio of beavers, small rodents and plant food was higher in summer, which resulted in a broader food niche in summer than in winter (B = 2.53 versus 1.81, respectively). The role of domestic animals in the wolf diet was minimal except for winter when they were consumed as carrion (13%). More than 1/3of all stomachs investigated were empty. The average weight of stomach contents was 972.8 g. The importance of the beaver as an alternative prey is discussed. We conclude that wolves in Latvia prey mainly on wild animals and conflicts with livestock owners are only occasional and/or local.     

Hexokinases of Tobacco Leaves: Changes in the Cytosolic and Non-Cytosolic Isozyme Complexes Induced by Tobacco Mosaic Virus Infection

Changes in the cytosotic (soluble) and the non-cytosolic (particulate) isozyme composition of hexokinases and in their properties were studied by ion exchange chromatography on DEAE cellulose after the subcellular fractionation both in the healthy and the tobacco mosaic virus (TMV) infected tobacco leaves. Three main isozyme complexes were obtained: one particulate fraction (the particulate hexokinase phosphorylating both glucose and fructose, EC 2.7.1.1), and two soluble fractions (the soluble hexokinase phosphorylating both the glucose and the fructose, and the soluble fructokinase, which phosphorylates primarily fructose, EC 2.7.1.4). The total fructokinase activities were nearly twice higher than the total glucokinase activities (188.6 % of glucokinase activity in healthy plants and 181.3 % in infected plants). The total particulate glucokinase activity was increased to 120.6 % and the fructokinase to 118.9 % in TMV infected tissue when compared with healthy control. The similar pattern of activity was observed for soluble hexokinase isozymes - the sum of soluble glucokinase activity was increased to 175.4 % and of fructokinase activity to 131.2 % in TMV infected tissue. The isozymes isolated both from the healthy control and TMV-infected leaves had the similar elution profiles, displayed Michaelis-Menten kinetics, showed the identical profiles of pH optima and were Mg²⁺ dependent with the highest enzyme activity at equimolar Mg²⁺ and ATP concentration. This revised version was published online in July 2006 with corrections to the Cover Date.     

Plant resources used for subsistence in tsehlanyane and bokong in lesotho

The communities of Tsehlanyane and Bokong depend on subsistence agriculture and harvesting natural resources for a variety of needs, mainly firewood, handcrafts, medicine, food, construction, and socio-cultural amenities. They have done so since time immemorial and are singularly responsible for the good conservation value that the area represents. The area has the longest history of conservation championed by a local traditional authority in Lesotho. From December 1999 to March 2000 we conducted a survey that was aimed at making an inventory of resources, on which people rely, that will be affected by the establishment of a biosphere reserve linking the Tsehlanyane National Park and the Bokong Nature Reserve. In the survey, 149 households were sampled representing a sampling intensity of 19% in both communities. One hundred forty-seven species of plants were mentioned, falling into 51 families with the most commonly used families being Asteraceae, Liliaceae sens. lat. and Poaceae. The study also revealed that tenurial rights on these resources are communal and usufructuary and are increasingly being undermined by commercialization that relegate resources to an open access system. The study identified six main use categories, namely, firewood, handcrafts, medicinals, wild fruits, wild vegetables, and miscellaneous uses. Finally, the study demonstrated that ethnobotanical knowledge is widely held in Lesotho with the traditional doctors being the major repositories     

Changes in Ribonuclease and Glucose-6-Phosphate Dehydrogenase Activities Induced by Beet Necrotic Yellow Vein Virus in Sugar Beet

Activities of host ribonucleases and glucose-6-phosphate dehydrogenase were studied in three cultivars (Monosvalof, Steffi and Rimini) of sugar beet differing in their resistance to beet necrotic yellow vein virus (BNYVV). No differences were found in the susceptibility of cultivars to BNYVV between mechanically inoculated and Polymyxa betae (a natural fungal vector of the virus) infected plants, but the culmination of reproduction curves of BNYVV in mechanically inoculated plants was observed one week earlier than in plants inoculated by means of P. betae. The activities of ribonucleases corresponded with virus multiplication. In roots, activities of ribonucleases reached a maximum at day 7; in leaves, maximum activity was found at day 21 in cv. Monosvalof, and at day 14 in cv. Steffi. The relatively resistant cultivar Rimini showed much lower activities. The activity of glucose-6-phosphate dehydrogenase was only slightly increased at the time of culmination of the BNYVV reproduction curve in cvs. Monosvalof and Steffi. This revised version was published online in June 2006 with corrections to the Cover Date.     

Similarity of QTLs detected for in vitro and greenhouse development of potato plants

A relationship between quantitative trait loci (QTLs) detected for in vitro and greenhouse growing conditions was studied in a backcross population of 155 genotypes derived from a haploid potato (Solanum tuberosum) and a diploid wild species (S. berthaultii). Both plant height and tuberization earliness were characterized under two growing conditions. Main-effect QTLs and QTLs identified only through interaction were detected for each of the traits. For traits associated with plant height as well as for traits associated with early tuberization, the most significant QTL detected for greenhouse cultivated plants was also found when the population was grown in vitro. The most significant QTL for earliness of tuberization in vitro, which was located on chromosome 8, coincides with that detected for sucrose concentration in leaf exudate. The absence of a S. berthaultii allele was associated both with a higher amount of sucrose in the exudate and with earlier in vitro tuber formation. Epistasis was found to have a significant effect on all traits investigated. The QTL model that included main-effect QTLs and all significant interactions explained 83–88% of the total genetic variance for each of the developmental traits. The possibility of using an in vitro system combined with marker-assisted selection for preliminary selection of early tuberizing clones is discussed.     

Carbon Balance of a Winter Wheat-Root Microbiota System Under Elevated CO2

We examined the carbon budget of young winter wheat plants and their associated microorganisms as affected by a doubling of the atmospheric CO₂ concentration (700 μmol mol^-1). Plants were grown hydroponically in pre-sterilised sand at a controlled irradiance and temperature regime. Net photosynthesis (P_N) and respiration (R_D) rates of roots and shoots were measured continuously, plant growth and carbon distribution in the plant-root medium-associated microorganism system were determined destructively in interval-based analyses. P_N in elevated CO₂ grown plants (EC) was 123% of that in the control (AC) plants when averaged over the whole life span (39-d-old plants, 34 d in EC), but the percentage varied with the developmental stage being 115, 88, and 167% in the pretillering, tillering, and posttillering phase, respectively. There was a transient depression of P_N, higher amplitude of day/night fluctuations of the chloroplast starch content, and depression of carbon content in rhizosphere of EC plants during the period of tillering. After 34 d in EC, carbon content in shoots, roots, and in rhizodepositions was enhanced by the factors 1.05, 1.28, and 1.96, respectively. Carbon partitioning between above and belowground biomass was not affected by EC, however, proportionally more C in the belowground partitioning was allocated into the root biomass. Carbon flow from roots to rhizodepositions and rhizosphere microflora was proportional to P_N; its fraction in daily assimilated carbon decreased from young (17%) to order (3-4%) plants. This revised version was published online in June 2006 with corrections to the Cover Date.     

Extracellular matrix surface network of embryogenic units of friable maize callus contains arabinogalactan-proteins recognized by monoclonal antibody JIM4

Embryogenic units of friable maize callus are formed as globular or oblong packets of tightly associated meristematic cells. These units are surrounded by conspicuous cell walls visible in light microscopy after staining with basic fuchsin. Transmission electron microscopy revealed that embryogenic cells are rich in endoplasmic reticulum, polysomes and small protein bodies, and that the outermost layer of their cell walls is composed of fibrillar material. Electron microscopy has also shown that this material covers the surface of embryogenic cells as a distinct layer which we denote as extracellular matrix surface network (ECMSN). Employing histochemical staining with β-glucosyl Yariv phenylglycoside, we localized arabinogalactan-proteins (AGPs) to the outer cell walls of embryogenic units including ECMSN. The most prominent staining was found in cell-cell junction domains. Large non-embryogenic callus cells were not stained with this AGP-specific dye. Immunofluorescence and silver-enhanced immunogold labelling using monoclonal antibody JIM4 has shown that the ECMSN of embryogenic cells is equipped with JIM4 epitope, while non-embryogenic callus cells are devoid of this epitope. We propose that some specific AGPs of the ECMSN might be relevant for cell-cell adhesion and recognition of embryogenic cells during early embryogenic stages, and that the JIM4 antibody can serve as an early marker of embryogenic competence in maize callus culture. Received: 13 March 1998 / Revision received: 6 June 1998 / Accepted: 1 July 1998