Myrmica rubra is a northern, temperate Palaearctic ant species with a geographical range that extends from the Atlantic coast of Europe to central Asia. In Europe, its range covers > 25° of latitude where it lives under a variety of climates that vary from extreme oceanic in the west, to continental in the east. Colonies nest in the soil and their life cycles are known to be highly dependent on ambient temperature and soil moisture. We hypothesised that the brood-rearing behaviour of populations might be focally adapted to climate and that we might detect differences when the ants were reared under \"common-garden\" conditions. Brood-rearing behaviour was compared for 38 colonies of M. rubra drawn from 13 populations representing a range of 6 latitudes: all 6 were represented in eastern Europe and 2 in western Europe. A sample of ants from each colony was used to estimate respiration rate, body mass and fat content at the start of the experiment in spring (immediately post hibernation) and at the end of the experiment (mid summer). Respiration had a linear relationship with latitude, with northern populations having greater respiration rate in spring compared to southern populations. It is suggested that this is an adaptation to different seasonality over the species' range that results in the \"more active\" northern workers rearing fewer brood to maturity more quickly than southern workers. Fat content, a measure of worker \"quality\", had a parabolic relationship with latitude with mid latitude colonies having the fattest workers. Fatter workers appeared to rear heavier brood. This probably represented a functional response to environment with populations living at \"edge of range\" sites being physiologically more stressed and performing brood-rearing tasks less well than centre of range populations. We believe that this is the first demonstration of a consistent, intra-specific trend for Variation in the social physiology of an ant species over its geographic range., Graham W. Elmes, Judith C. Wardlaw, Mogens G. Nielsen, Vladilen E. Kipyatko, Elena B. Lopatina, Alexander G. Radchenko, Boyd Barr, and Lit
There is much current discussion about the factors that control the distribution and abundance of animal species, particularly at the edges of their range. The significance of temperature for survival and development is compared in two closely related psyllid species (Craspedolepta nebulosa and C. subpunctata) living on the same host plant (Chamerion angustifolium) (Onagraceae) but displaying different distributions along latitudinal and altitudinal gradients. The following measurements were made at critical periods during the life cycle (a) winter supercooling points (SCPs), (b) tolerance of short (1 min) and long term (1-25) days exposure to sub-zero temperatures above the SCP, (c) tolerance of short term exposure to high spring/summer temperatures and (d) comparative field development rates among species and sites during the early critical part of the growing season. Successful completion of the life cycle is related to heat availability during the growing season. This appears to limit the distribution of the Craspedolepta species, rather than their survival response to thermal extremes. No significant differences were found between the two species in the supercooling point or in their long and short term survival responses at low or high temperatures., Jeremy M. Bird, Ian D. Hodkinson, and Lit
In order to manage the risks posed to domestic crop production by quarantine pests such as Thrips palmi, their potential to establish in a new environment must be assessed. The thermal requirements for development of T. palmi were determined and compared with UK temperatures, to estimate its potential for development under UK conditions. Temperature and rate of development of T. palmi from egg to adult were linearly related between 15 and 30°C, allowing calculation of an overall threshold of 10.1°C, and a sum of effective temperatures of 194 degree-days. In the UK, development of T. palmi would be possible outdoors during the summer when a maximum of up to four or five generations could occur. Comparison of these data with those of the recently established and biologically similar pest, Frankliniella occidentalis, shows that establishment of T. palmi in the UK is unlikely to be limited by an inability to complete the life cycle during the favourable season., Jamie R. McDonald, Jeffrey S. Bale, Keith F.A. Walters, and Lit
C-type natriuretic peptides (CNP) play an inhibitory role in smooth muscle motility of the gastrointestinal tract, but the effect of CNP on delayed rectifier potassium currents is still unclear. This study was designed to investigate the effect of CNP on delayed rectifier potassium currents and its mechanism by using conventional whole-cell patch- clamp technique in guinea-pig gastric myocytes isolated by collagenase. CNP significantly inhibited delayed rectifier potassium currents [IK (V)] in dose-dependent manner, and CNP inhibited the peak current elicited by depolarized step pulse to 86.1±1.6 % (n=7, P<0.05), 78.4±2.6 % (n=10, P< 0.01) and 67.7±2.3 % (n=14, P<0.01), at concentrations of 0.01 μmol/l, 0.1 μmol/l and 1 μmol/l, respectively, at +60 mV. When the cells were preincubated with 0.1 μmol/l LY83583, a guanylate cyclase inhibitor, the 1 μmol/l CNP-induced inhibition of IK (V) was significantly impaired but when the cells were preincubated with 0.1 μmol/l zaprinast, a cGMP-sensitive phosphodiesterase inhibitor, the 0.01 μmol/l CNP-induced inhibition of IK (V) was significantly potentiated. 8-Br-cGMP, a membrane permeable cGMP analogue mimicked inhibitory effect of CNP on IK (V). CNP-induced inhibition of IK (V) was completely blocked by KT5823, an inhibitor of cGMP-dependent protein kinase (PKG). The results suggest that CNP inhibites the delayed rectifier potassium currents via cGMP-PKG signal pathway in the gastric antral circular myocytes of the guinea-pig., H. Y. Xu, X. Huang, M. Yang, J.-B. Sun, L.-H. Piao, Y. Zhang, L. Gao, W.-X. Xu., and Obsahuje bibliografii a bibliografické odkazy
The aim of our study was to test the in fluence of short exposure (6 h) of preimplantation rabbit embryos to elevated temperatures (41.5 ºC or 42.5 ºC) in vitro on their developmental capacity. Fertilized eggs recovered from female oviducts at the pronuclear stage (19 hpc) were cultured at standard temperature (37.5 ºC) until the morula stage (72 hpc). Afterwards, the embryos were divided into two groups, cultured for 6 h either at hyperthermic (41.5 ºC or 42.5 ºC) or standard temperature (control 37.5 ºC), post-incubated overnight (16-20 h) at 37.5 ºC and then evaluated for developmental stages, apoptosis (TUNEL), proliferation (cell number), actin cytoskeleton and presence of heat-shock proteins Hsp70. It was observed that hyperthermia at 41.5 ºC did not alter progression of embryos to higher preimplantation stages (expanded and hatching/hatched blastocysts), rate of apoptosis, total cell number of blastocysts and structure of actin filament compared to 37.5 ºC. We stern-blotting revealed the presence of heat stress-induced 72 kDa fraction of Hsp70 proteins in granulosa cells (exposed to 41 ºC) and embryos (exposed to 41.5 ºC). Following the elevation of temperature to 42.5 ºC embryo development was dramati cally compromised. The embryos were arrested at the morula or early blastocyst stage, showed an increased rate of apoptosis and decreased total cell number compared to control. The structure of actin filaments in most of blastomeres was damaged and such blastomeres often contained apoptotic nuclei. In this group a presence of heat-stress-induced fraction of Hsp70 proteins had not been confirmed. This is the first report demonstrating a threshold of thermotolerance of rabbit preimplantation embryos to hyperthermic exposure in vitro. A detrimental effect of higher temperature on the embryo is probably associated with the loss of their ability to produce Hsp70 de novo, which leads to cytoskeleton alterations and enhanced apoptosis., A. V. Makarevich, L. Olexiková, P. Chrenek, E. Kubovičová, K. Fréharová, J. Pivko., and Obsahuje bibliografii a bibliografické odkazy
To evaluate whether the response of hematopoietic cells to interleukin-17 (IL-17) depends on the tissue microenvironment in which hematopoiesis occurs, the influence of recombinant mouse IL-17 on spleen hematopoietic cells and cytokine release was assessed in normal mice in vitro and in vivo. In vitro, IL-17 did not significantly affect the growth of granulocyte-macrophage (CFU-GM) and erythroid (BFU-E and CFU-E) derived colonies. A single injection of IL-17 in vivo exhibited stimulatory effects on hematopoietic cells from both granulocytic and erythroid lineages. The increased number of metamyelocytes 48 h after treatment imply to the IL-17-induced stimulation of granulopoiesis. The number of BFU-E was increased at 24 h, while the number of CFU-E increased 6 h and 24 h after treatment. Since the same treatment in the bone marrow decreased the number of CFU-E, it may be concluded that the local microenvironment plays an important role in IL-17-mediated effects on CFU-E. IL-17 increased the release of IL-6 both in vitro and in vivo, but showed tendency to suppress the constitutive secretion of IL-10 by spleen cells. Our results suggest the complexity of target cell response and interplay of secondary induced cytokines by IL-17 in different hematopoietic organs., G. Jovčić, D. Bugarski, A. Krstić, M. Vlaški, M. Petakov, S. Mojsilović, N. Stojanović, P. Milenković., and Obsahuje bibliografii a bibliografické odkazy
The oribatid mite Galumna elimata was reared under laboratory conditions on algae (Protacoccus spp.) at different temperatures (5, 15 and 20°C). Higher weight-specific amylolytic activity was found in the whole body homogenates of mites exposed to cold acclimation (5°C, 21 days) in comparison with individuals acclimated to 15 and 20°C. Accompanying parameters (live body weight, content of total soluble proteins in the body, protein-specific amylolytic activity, presence and composition of food boluses, activity of mesenteric and caecal wall cells, gregarinid parasitisation, number of glycogen granulae and guanine deposits in mesenchymal tissue, presence of proventricular glands) were investigated at all three acclimation temperatures to explain mechanisms of this change. The acclimation response of weight-specific amylolytic activity was accompanied by elevation of protein-specific amy lolytic activity. Microanatomical features did not confirm any increased secretion activity of mesenteric and caecal cells in cold acclimated animals. Granulation and apocrine secretion of these cells increased with increasing temperature as with food ingestion. The food boluses contained algae or algae mixed with unknown fungal hyphae in individuals acclimated to 15 and 20°C. The concentrated mucoid substances prevailed in animals exposed to cold, indicating lower feeding activity at 5°C. Based on these findigs, Lye hypothesised that specific amylolytic activity reflected passively the different changes in protein composition of the body at different temperatures and its elevation is without direct adaptive importance., Vladimír Šustr, Jan Hubert, and Lit