Abstract

The claim that β-lactam antibiotics induce the SOS response, allowing E. coli survival in the presence of low antibiotic concentrations, was evaluated. No association between the recA gene and antibiotic survival rate was found. Disagreements with published observations are attributed to discrepancy in minimum inhibitory concentrations and growth characteristics of various strains carrying the recA mutation. Moreover, β-lactam antibiotics do not induce expression of the SOS regulated gene cka , encoding colicin K in wild-type strains.

Keywords

SOS response, E. coli , β-lactam antibiotics, antibiotic resistance

Abstract

The article discusses the occurrence, distribution and phytosociological affinity of Laserpitium krapfii in Slovenia. According to some literature sources (Tutin 1968, Fischer et al. 2008) and the distribution patterns, two subspecies of L. krapfii are be expected in Slovenia: L. krapfii subsp. krapfii and L. krapfii subsp. gaudinii. The revision of the Slovene herbarium material in LJU and LJS herbaria confirmed only the occurrence of its type subspecies . It has a Dinaric pattern of distribution (NW-SE) in the Alpine, Prealpine, Dinaric and Predinaric phytogeographical regions, with most of its known localities in the hills south of Ljubljana, in the Snežnik mountains, in the Kočevje region with the Kolpa Valley and in the Gorjanci mountains. Since the species mostly thrives in the mountain beech forests, it can be considered as a diagnostic (differential) species of the Illyrian alliance Aremonio-Fagion .

Keywords

Laserpitium krapfii subsp. krapfii , taxonomy, phytogeography, Aremonio-Fagion , Slovenia

Abstract

Fallopia japonica and Fallopia × bohemica are two very invasive plant species in Europe and North America. Their main mode of spread is vegetative reproduction. In spring new shoots emerge from the overwintering rhizome, grow rapidly and develop broad leaves which shade undergrowth plants. We studied cell size and starch accumulation in three stem regions at five sampling times during one growth season to determine possible differences in growth dynamics of both Fallopia species. On average F. × bohemica had somewhat larger cells than F. japonica but the differences were not significant, except in the internodes of the middle stem region with differentiating cells. Also, cell growth dynamics of both species was similar and the only difference was detected at the 2 nd sampling when cells of F. × bohemica were more elongated. F. × bohemica also accumulated starch earlier in the growth season and in younger tissues than F. japonica .

Keywords

Fallopia japonica , Fallopia × bohemica , cell size, starch, growth

Abstract

There is little data about possible interactions between selenium and iodine on plants. Se is essential for I metabolism in the thyroid in mammals. Thus, it is of great importance to carry out the research with simultaneous application of

both elements in plant cultivation that are used for human consumption. Seeds of common buckwheat and pumpkins were soaked in solutions: 10 mgSe/L in the form of selenite or selenate, and 1000 mgI/L in the form of iodide or iodate and their combinations. The content of chlorophyll a and b , and carotenoids were measured. Further, the measurements of fluorescence of chlorophyll a were performed. Control buckwheat sprouts and sprouts from seeds soaked in Se(VI) and Se(VI)+I(-1), had the lowest and similar amount of chlorophyll a and carotenoids. There was little effect of different treatments on potential photochemical efficiency of photosystem II (PS II) in common buckwheat sprouts. In pumpkin sprouts neither of treatment affected the amount of photosynthetic pigments, as well as potential photochemical efficiency of (PS II) which was around 0.8.

Keywords

sprouts, common buckwheat, pumpkins, selenium, iodine

Abstract

The Aral sea used to be the fourth largest lake in the world. Its catchment area is huge, two main rivers (Amu Darya and Syr Darya) feed the lake. The balance of hydrological regime changed drastically after 1960 due to regulation of both main rivers and diversion of water for agricultural irrigation and intense cotton production. Salinity increased and most of invertebrate and fish species disappeared. A significant drop of water level has been recorded in the past 20 years and Aral Lake is presently divided into a small northern lake basin and a larger south basin. Kokaral dam construction resulted in increased water level and decreased salinity. Many invertebrate species reappeared in Small Aral and fish returned from Syr Darya river. Ecological situation in Large Aral is different, eastern part of this basin is completely dried out. The data on salinity levels, some chemical characteristics and above all the data about zooplankton, zoobenthos and fish in Small Aral have been recorded and presented in the article. Salinity ranges between 1 and 8 g/L, the lowest is near the river inlet. Five species of zooplankton ( Keratella quadrata , Brachionus plicatilis , Evadne anonyx , Calanipeda aquaedulcis , Cyclops vicinus ) and rotifers from the genus Synchaeta are very abundant, ten species are less numerous and seven summer species very rare. Different zoobenthos species are present, but only four abundant ( Hediste diversicolor , Chironomus plumosus , Syndosmya segmentum and Cyprideis torosa ). Zoobenthos mainly consist of Polychaeta, Mollusca, Crustacea and Diptera. The highest diversity was found near the Kokaral dam. Many fish species are commercially important: 14 of them are abundant, including endemic bream Abramis brama orientalis , Chalcalburnus

chalcoides aralensis , carp Cyprinus carpio aralensis , and Aral roach Rutilus rutilus aralensis . White-eye bream Abramis sapa aralensis , silver carp Hypophtalmichthys molitrix , orfe Leuciscus idus oxianus , and snakehead Channa argus warpachowskii are less numerous. Aral barbel Barbus brachycephalus brachycephalus and Turkestan barbel Barbus capito conocephalus remain very rare. It can be concluded that significant positive changes occurred after Kokaral dam construction. Particularly, biocenoses and the Aral lake environment have been improved and fisheries returned. Today Kazakhstan Government is discussing an idea to improve this dam and dike and we support this discussion and advise to make it higher. All can lead to improve ecological state of the Small Aral.

Keywords

Aral Sea, biodiversity, ecological state, zooplankton, zoobenthos, fish