排序方式: 共有12条查询结果,搜索用时 0 毫秒
1.
Andrius Kaselis Rimantas Treinys Rūta Vosyliūtė Saulius Šatkauskas 《Cellular and molecular neurobiology》2014,34(2):289-296
Regeneration of embryonic and adult dorsal root ganglion (DRG) sensory axons is highly impeded when they encounter neuronal growth cone-collapsing factor semaphorin3A (Sema3A). On the other hand, increasing evidence shows that DRG axon’s regeneration can be stimulated by nerve growth factor (NGF). In this study, we aimed to evaluate whether increased NGF concentrations can counterweight Sema3A-induced inhibitory responses in 15-day-old mouse embryo (E15) DRG axons. The DRG explants were grown in Neurobasal-based medium with different NGF concentrations ranging from 0 to 100 ng/mL and then treated with Sema3A at constant 10 ng/mL concentration. To evaluate interplay between NGF and Sema3A number of DRG axons, axon outgrowth distance and collapse rate were measured. We found that the increased NGF concentrations abolish Sema3A-induced inhibitory effect on axon outgrowth, while they have no effect on Sema3A-induced collapse rate. 相似文献
2.
Rimgaudas Treinys Deivis Dementavičius Gintautas Mozgeris Saulis Skuja Saulius Rumbutis Darius Stončius 《European Journal of Wildlife Research》2011,57(6):1165-1174
The processes of competition and predation determine the degree to which species can coexist; the importance of competition
in particular has been emphasized at high trophic levels. Competition exclusion will occur when habitat overlap between sympatric
species is high. In this study, we investigated nesting habitat overlap between internationally protected diurnal tree-nesting
avian predators of central Europe, namely, White-tailed Eagle (Haliaeetus albicilla), Lesser Spotted Eagle (Aquila pomarina), Black Stork (Ciconia nigra), and Osprey (Pandion haliaetus). We found significantly different nesting habitats among the study species and suggest that this could be a consequence
of the resource-based segregation, but not a consequence of asymmetrical interspecific competition. The results also show
that habitat of the recovering populations of White-tailed Eagle overlapped with the habitat used by the Lesser Spotted Eagle,
Black Stork, and Osprey to varying extents with a niche overlap values being below the competition exclusion threshold. Nevertheless,
we suggest that competition by White-tailed Eagle at a population level may limit Osprey, though not Lesser Spotted Eagle
or Black Stork. 相似文献
3.
Geographical variation in wildlife–habitat relationships has seldom been studied. We explored macrohabitat use and geographically distinct responses to habitat availability in the Lesser Spotted Eagle Aquila pomarina near the centre (Lithuania) and on the edge (Estonia) of its European distribution range, and in different zones within Estonia. Land cover types and distances to landscape elements, as well as landscape diversity, were measured around 198 Eagle nests and random forest points. Out of six macrohabitat characteristics, two (landscape diversity, area of optimal foraging habitat) showed no geographical variation in use, or preferences by the Eagle. Whereas variation in the use of suboptimal foraging habitats and forests could be attributed to regional differences in their availability, there were geographically distinct preferences for distances between nests and landscape elements. The species avoided anthropogenic edges in Lithuania but tended even to prefer their proximity in Estonia; Eagles selected nest-sites near remote waterbodies throughout Estonia but there was no such preference in Lithuania. The results did not support the hypothesis that latitudinal or range centre-to-periphery gradients existed in habitat relationships of the species; the main factor behind the geographical variation was probably land-use history. In general, the diversity of geographical effects indicated that extrapolating local habitat relationships to other areas may give erroneous results, and large-scale conservation planning regarding species' habitat may be ineffective. 相似文献
4.
Ülo Väli Pauli Saag Valery Dombrovski Bernd‐Ulrich Meyburg Grzegorz Maciorowski Tadeusz Mizera Rimgaudas Treinys Sofie Fagerberg 《Journal of avian biology》2010,41(1):34-49
The correct identification of hybrids is essential in avian hybridisation studies, but selection of the appropriate set of genetic markers for this purpose is at times complicated. Microsatellites and single nucleotide polymorphisms (SNPs) are currently the most commonly used markers in this field. We compare the efficiency of these two marker types, and their combination, in the identification of the threatened avian species, the greater spotted eagle and the lesser spotted eagle, as well as hybrids between the two species. We developed novel SNP markers from genome-wide distributed 122 candidate introns using only sympatric samples, and tested these markers successfully in 60 sympatric and allopatric spotted eagles using Bayesian model-based approaches. Comparatively, only one out of twelve previously described avian nuclear intron markers showed significant species-specific allele frequency difference, thus stressing the importance of selecting the proper markers. Twenty microsatellites outperformed selected nine SNPs in species identification, but were poorer in hybrid detection, whereas the resolution power of ten microsatellites remained too low for correct assignment. A combination of SNPs and microsatellites resulted in the most efficient and accurate identification of all individuals. Our study shows that the use of various sets of markers could lead to strikingly different assignment results, hybridisation studies may have been affected by too low a resolution power of used markers, and that an appropriate set of markers is essential for successful hybrid identification. 相似文献
5.
Rimantas Treinys Andrius Kaselis Emmanuel Jover Dominique Bagnard Saulius ?atkauskas 《PloS one》2014,9(7)
Semaphorin 3A (Sema3A) is a secreted protein involved in axon path-finding during nervous system development. Calcium signaling plays an important role during axonal growth in response to different guidance cues; however it remains unclear whether this is also the case for Sema3A. In this study we used intracellular calcium imaging to figure out whether Sema3A-induced growth cone collapse is a Ca2+ dependent process. Intracellular Ca2+ imaging results using Fura-2 AM showed Ca2+ increase in E15 mice dorsal root ganglia neurons upon Sema3A treatment. Consequently we analyzed Sema3A effect on growth cones after blocking or modifying intracellular and extracellular Ca2+ channels that are expressed in E15 mouse embryos. Our results demonstrate that Sema3A increased growth cone collapse rate is blocked by the non-selective R- and T- type Ca2+ channel blocker NiCl2 and by the selective R-type Ca2+ channel blocker SNX482. These Ca2+ channel blockers consistently decreased the Sema3A-induced intracellular Ca2+ concentration elevation. Overall, our results demonstrate that Sema3A-induced growth cone collapses are intimately related with increase in intracellular calcium concentration mediated by R-type calcium channels. 相似文献
6.
Rimgaudas Treinys Asko L?hmus Darius Stonius Saulis Skuja Eugenijus Drobelis Bronius ableviius Saulius Rumbutis Deivis Dementaviius Vladas Narueviius Antanas Petraka Danas Augutis 《Journal of Ornithology》2008,149(1):75-81
Recent trends in the European Black Stork Ciconia nigra population are geographically distinct: range expansion and adaptation to human activity dominate in western and central
Europe, while declines—probably induced by landscape change—are reported in the east. We studied the large Lithuanian Black
Stork population in the transition zone to explore whether, and how, the detrimental influences of recent Baltic landscape
changes are balanced by the West European tendency of behavioural adaptation to human activity. Based on monitoring in sample
plots, the current population was estimated at 650–950 pairs, indicating a significant decrease (possibly over 20%) during
the last two decades. In comparison to the Latvian and Estonian populations, however, this decline is smaller, and the reproductive
success remains at a high level [66% breeding success and 2.99 ± 0.97 (SD) fledglings per successful attempt, 2000–2006];
this north–south gradient suggests a climate-mediated impact of habitat degradation in the Baltic countries. The storks are
also nesting closer to forest edges and in younger stands than 15–30 years ago, which has probably reduced the nest-tree limitation,
as indicated by an increased use of large oaks. Thus, habitat degradation and adaptation seem to be taking place simultaneously
in the Lithuanian Black Stork population, as was expected from its geographical location. In general, our study supports the
view that, whenever possible, species conservation strategies and the use of indicator species should be geographically explicit. 相似文献
7.
Karolina Čepurnienė Paulius Ruzgys Rimantas Treinys Ingrida Šatkauskienė Saulius Šatkauskas 《The Journal of membrane biology》2010,236(1):81-85
DNA electrotransfer in vivo for gene therapy is a promising method. For further clinical developments, the efficiency of the
method should be increased. It has been shown previously that high efficiency of gene electrotransfer in vivo can be achieved
using high-voltage (HV) and low-voltage (LV) pulses. In this study we evaluated whether HV and LV pulses could be optimized
in vitro for efficient DNA electrotransfer. Experiments were performed using Chinese hamster ovary (CHO) cells. To evaluate
the efficiency of DNA electrotransfer, two different plasmids coding for GFP and luciferase were used. For DNA electrotransfer
experiments 50 μl of CHO cell suspension containing 100, 10 or 1 μg/ml of the plasmid were placed between plate electrodes
and subjected to various combinations of HV and LV pulses. The results showed that at 100 μg/ml plasmid concentration LV pulse
delivered after HV pulse increased neither the percentage of transfected cells nor the total transfection efficiency (luciferase
activity). The contribution of the LV pulse was evident only at reduced concentration (10 and 1 μg/ml) of the plasmid. In
comparison to HV (1,200 V/cm, 100 μs) pulse, addition of LV (100 V/cm, 100 ms) pulse increased transfection efficiency severalfold
at 10 μg/ml and fivefold at 1 μg/ml. At 10 μg/ml concentration of plasmid, application of four LV pulses after HV pulse increased
transfection efficiency by almost 10-fold. Thus, these results show that contribution of electrophoretic forces to DNA electrotransfer
can be investigated in vitro using HV and LV pulses. 相似文献
8.
Bogdelis A Treinys R Stankevičius E Jurevičius J Skeberdis VA 《Biochemical and biophysical research communications》2011,(1):116-121
In the heart, L-type voltage dependent calcium channels (L-VDCC) provide Ca2+ for the activation of contractile apparatus. The best described pathway for L-type Ca2+ current (ICa,L) modulation is the phosphorylation of calcium channels by cAMP-dependent protein kinase A (PKA), the activity of which is predominantly regulated in opposite manner by β-adrenergic (β-ARs) and muscarinic receptors. The role of other kinases is controversial and often depends on tissues and species used in the studies. In different studies the inhibitors of tyrosine kinases have been shown either to stimulate or inhibit, or even have a biphasic effect on ICa,L. Moreover, there is no clear picture about the route of activation and the site of action of cardiac Src family nonreceptor tyrosine kinases (Src-nPTKs). In the present study we used PP1, a selective inhibitor of Src-nPTKs, alone and together with different activators of ICa,L, and demonstrated that in human atrial myocytes (HAMs): (i) Src-nPTKs are activated concomitantly with activation of cAMP-signaling cascade; (ii) Src-nPTKs attenuate PKA-dependent stimulation of ICa,L by inhibiting PKA activity; (iii) Gαs are not involved in the direct activation of Src-nPTKs. In this way, Src-nPTKs may provide a protecting mechanism against myocardial overload under conditions of increased sympathetic activity. 相似文献
9.
Strong territoriality and weak density‐dependent reproduction in Lesser Spotted Eagles Clanga pomarina 下载免费PDF全文
We assessed whether populations of the migratory, philopatric, territorial Lesser Spotted Eagle Clanga pomarina are regulated through territoriality and density‐dependent reproduction rates. In the north‐western part of the distribution to the east of the Baltic Sea, territories were spaced regularly and consistently between years. We did not find strong support for an improvement of reproductive output with an increase in distance to the nearest neighbour or with a decrease of the number of conspecifics within a 2‐km radius around nest‐sites. Eagles differed greatly in territory spacing across three studied geographical areas, but breeding performance did not follow the same pattern. Performance of birds at the northern limit of their distribution did not differ from that in an adjacent southern area. Moreover, breeding performance fluctuated synchronously across different geographical areas, perhaps indicating climatic spatial autocorrelation or trophic interactions with synchronous vole population fluctuations over large areas. Our data suggest population regulation through territoriality but do not identify density‐dependent breeding performance in this internationally protected raptor. Population density may be a good criterion for the selection of priority sites for conservation, but synchronous fluctuations in reproductive success over large geographical areas suggest that habitat conservation should similarly be focused at large scales. 相似文献
10.
Regina Ma?ianskien? Irma Marti?ien? Antanas Navalinskas Rūta Vosyliūt? Rimantas Treinys Birut? Vaidelyt? Rimantas Benetis Jonas Jurevi?ius 《PloS one》2015,10(4)