Abstract

The study was designed to depict the seasonal dynamic in relative abundance of macrophyte species, nutrient availability and their content in macrophytes to assess the capability of different species to store nutrients in nutrient rich lake Velenjsko jezero. The concentrations of total nitrogen and total phosphorus in the lake sediment, water and aboveground biomass of macrophytes ( Nuphar luteum , Najas marina , Najas minor , Potamogeton lucens and Potamogeton pectinatus ) were measured at three locations monthly from June to September 2004 . Seasonal variability in the contents of total phosphorus in macrophyte tissues was high, but all examined species reached similar maximal concentration in the beginning of their growth. Later in the season, concentrations declined to a high degree. Seasonal variability in the contents of total nitrogen was smaller. F loating-leaved species Nuphar luteum was present in a low amounts and contained much more total nitrogen in its above-ground tissues than the submersed species. Because of different species life spans, differences in the content of nutrients among species were very high in particular month. Nuphar luteum, Najas minor and Potamogeton lucens were rarely present in the lake and they contributed less to storing nutrients in their biomass. Potamogeton pectinatus was commonly present in the early summer, but in August Najas marina prevailed by far and its growth had high effect on the concentration of nutrients in sediment and water. Therefore removing of 1 t dry weight of Najas marina biomass from the lake would contribute to removal of 2.7 kg of phosphorus and 28.2 kg of nitrogen from the lake.

Keywords

lake, total nitrogen, total phosphorus, Nuphar luteum (L.) Sibth et Sm. , Najas marina L., Najas minor All., Potamogeton lucens L. and Potamogeton pectinatus L.

Abstract

Najas marina L. is the dominant macrophyte species in Velenjsko jezero. It appeared in the lake in 1997 and soon prevailed over the species Myriophyllum spicatum L. and Potamogeton crispus L., which used to be the two most abundant species in the lake in the past. The physico-chemical and geomorphological characteristics of the lake are discussed in relation to the attributes of Najas marina , presenting competitive advantages in this environment. Conditions in the lake such as warm water and unstable sediment enabled successful growth and life strategy of Najas marina , which is a summer-annual plant with short life cycle, quick propagation from seeds and a very extensive root system.

Keywords

artificial lake, physico-chemical and geomorphological characteristics of the lake, plant invasion, aquatic macrophytes, Najas marina L.

Abstract

110 uropathogenic Escherichia coli (UPEC) strains obtained from the Institute of Microbiology and Immunology of the Medical Faculty in Ljubljana, Slovenia were screened with molecular biology methods for the well characterized adhesin gene sequences: fimH (Type 1 fimbriae), papC , papGII and papGIII (P-fimbriae), sfa (S-fimbriae) and afa/dra (Afa/Dr adhesins). The fimH gene nucleotide sequences were detected in 97% of the isolates, papC in 49%, papGII in 34%, papGIII in 13%, sfa/foc in 24% and afa/dra sequences were harbored by 2% of the tested isolates. FimH sequences were found with similar prevalence in E. coli strains of all four phylogenetic groups A, B1, B2 and D. papC sequences were also found in all phylogenetic groups, but they were the most prevalent (64%) in the B2 group. The papGII showed the highest prevalence in the D group (48%), but papGIII adhesin sequences were exclusively found in the B2 group. A very high prevalence of S-fimbriae in the B2 group was detected. The analysis of co-associations of adhesin gene sequences and some other traits revealed that papC gene sequences were co-associated with P-fimbriae adhesin gene sequences papGII and papGIII and with S-fimbriae sfa/foc sequences. A negative association was found between papGIII and traT and between papGIII and RepFIB sequence. Interestingly, a negative association was also visible between integrons and P- and S-fimbriae, albeit the association was not statistically significant.

Keywords

uropathogenic Escherichia coli , UPEC, adhesin, fimbriae

Abstract

The article examines attitude towards plants and animals in a population of 210 pupils aged 9 to 18. The results support the proposition that animals are generally more interesting to pupils than plants. Their interest was strongly influenced by age, while gender-based difference was only one.

Keywords

plants, animals, age, gender, attitudes, plant blindenss

Abstract

In the present study, we investigated how direct experience of certain amphibian species may affect a change in 7th grade science students’ attitude to, and knowledge about them. For this purpose, we devised a 45-minute lesson in which we used live amphibian species, and one lesson in which lifeless animals were used. The results show that students with prior direct experiences of amphibians generally report a more positive attitude toward them and, on average, achieve higher pre-test scores. Using live animals in the classroom had a major effect on the students' attitudes to individual species, regardless of whether they had any previous experience with them. Students who have done both practical work with live animals in the classroom and had previous direct experience with them showed the highest level of knowledge and knowledge retention. Implications of the findings are discussed.

Keywords

amphibians, direct experience, attitude change, knowledge