Previous behavioural tests indicated that strain recognition and aggregation behaviour could be induced by cuticular hydrocarbons. The aim of this study was to document and to compare cuticular hydrocarbon profiles between different strains of Blattella germanica (L.) (Dictyoptera: Blattellidae) and to relate variations in the general profile of cuticular hydrocarbons with strain discrimination during behavioural tests. Profiles of different strains were remarkably similar qualitatively but presented slight quantitative differences over the 25 identified components. Important differences were observed in dimethylalkane components and these allowed separation of the strains into two groups using multivariate methods. Although we were not able to demonstrate a relationship between strain discrimination ability and differences in cuticular hydrocarbon profiles, we assumed that cuticular hydrocarbons could play two major roles in B. germanica strains. Less variable hydrocarbon profiles could play a role in species recognition and aggregation behaviour and the more variable part could play a role in strain discrimination.
The use of Continuously Operating Reference Stations, both singly and as part of an active network, is widely employed in surveying, engineering and other geomatics applications, achieving high accuracy positioning even in real time. With an active network the measurements of the reference stations are processed jointly in order to model the errors and compute network RTK corrections. Due to distance dependent errors (ionospheric and tropospheric delays), single base RTK positioning accuracy decreases with increased baseline length. However, the network solution (NRTK) retains the accuracy and the time to fix ambiguities (TTFA) at a constant level. This study aims to contribute to the scientific research on real time positioning based on active networks. In Southern Spain, ERGNSS, a national CORS network that provides GNSS data for post-processing and real time single- b ased reference station corrections, shares territory with the Andalusian Positioning Network (RAP), a local active network. RAP provides network an d single-based RTK corrections. In order to analyze the quality of real time positioning based on both networks, several tests have been performed on a sample of test points. The reference frame, the time to fix ambiguity resolution, precision, accuracy and repeatability of RTK positioning are considered as the evaluation parameters. The results confirm that the RAP network complements the precise positioning services provided by the ERGNSS network, ensuring accurate real time positioning, full cove rage and reliable positioning services in the Andalusian Community., Mª Selmira Garrido, Antonio J. Gil and Rafael Gaitán., and Obsahuje bibliografické odkazy
In this study we evaluate how variations in taxonomic composition and physical structure of macrophyte stands affect plant-dwelling chironomid assemblages in highly variable macrophyte assemblages in two densely vegetated backwaters. By using multivariate explanatory techniques we found that similar vegetation composition did not unequivocally relate to similar chironomid assemblages, moreover the diversity of macrophyte stands did not correlate with the taxonomic diversity of chironomid assemblages in the backwaters investigated. Taxonomic composition and structural characteristics of the vegetation had little influence on the taxonomic or functional (i.e. feeding groups) composition of chironomid assemblages inhabiting them. Similarly, there are only weak relationships between the distribution of certain chironomid species or functional feeding groups and the environmental variables investigated. In general, the structure of the vegetation was more closely associated with the distribution of dominant chironomid taxa than compositional variables (i.e. density of specific macrophyte taxa). In summary, the structure of aquatic vegetation (i.e. position, size of a stand of vegetation, total plant density) and characteristics of the environment where it develops may be more important in shaping plant-dwelling chironomid assemblages than the taxonomic composition of the vegetation., Mónika Tóth ... [et al.]., and Obsahuje seznam literatury
There has been increasing evidence in recent years for the hypothesis of bones as endocrine organs. Osteocalcin, long considered just a marker of new bone formation, is now seen as the first hormone produced by bones, and seems to be associated with regulating glucose metabolism and reproduction. The aim of this work was to monitor changes of osteocalcin in reaction to hypoglycemia, and determine if there are differences in such reactions between the sexes. The study included 61 healthy probands with physiological calciophosphate metabolism (30 men and 31 women). We applied to each of them an insulin tolerance test, and then monitored levels of undercarboxylated osteocalcin and reactions to hypoglycemia at regular time intervals. We found differences in the reaction to hypoglycemia between the sexes. In men there was a significant decline in undercarboxylated osteocalcin between the 30 and 40 min (p<0.0015), which reflects a reaction to a glycemic decline between 25-30 min, followed by reversal. Low undercarboxylated osteocalcin in men lasted up to 90 min, after which they returned to levels before the test. In women we did not find any significant changes in undercarboxylated osteocalcin levels. Changes in undercarboxylated osteocalcin induced by hypoglycemia indicate a relationship between bones and glucose metabolism. There was an interesting difference between the sexes. However, a definitive conclusion about the role of osteocalcin in human metabolism will require numerous future studies., Michaela Dušková, Lucie Kolátorová, Hana Jandíková, Hana Pospíšilová, Luboslav Stárka., and Obsahuje bibliografii
Many areas of biology employ standard model organisms on which a majority of research effort is concentrated. However, there is invariably a danger associated with the use of too few or atypical models for studies of particular taxonomic groups, guilds or biological phenomena. Using aphidophagous ladybirds, I show that in this group, in the last ten years, 69% of research has been concentrated on just five species, all generalist ecotypes. Much research is now concentrated on invasive species, originally biocontrol agents, and over half the aphidophagous ladybird work on intraguild interactions is centred on two of the five predominant species, Coccinella septempunctata and Harmonia axyridis. Using examples from differing areas of research, I show that studies of more unusual, non-commercial specialists can enhance our understanding of the commonly studied groups. I suggest further areas where a similar approach may lead to equally illuminating results.