Characteristics of the distribution of ticks Ixodes persulcatus and Ixodes pavlovskyi at the border between the forest and forest-steppe zones in the territory near Ob River

Field investigations performed in 2009 and 2010 in the Novosibirskiy, Toguchinskiy, and Sovetskiy districts of Novosibirsk Province showed, that at present, Ixodes persulcatus, I. pavlovskyi (subspecies I. pavlovskyi occidentals Filippova et Panova, 1998), and Dermacentor reticulatus (Fabricius, 1794) permanently cohabitate in the woodland park of the Novosibirsk Akademgorodok, and I. pavlovskyi is the dominating species there. The highest abundance of I. pavlovskyi was recorded in pine forests subjected to intensive recreational load. At the same time, I. pavlovskyi was not found in the Novosibirskiy District and in the plane part of Toguchinskiy District, while the abundance of I. persulcatus is almost three times higher in the above mentioned territories, than in the Akademgorodok.     

RNA polymerase I-specific subunits promote polymerase clustering to enhance the rRNA gene transcription cycle

RNA polymerase I (Pol I) produces large ribosomal RNAs (rRNAs). In this study, we show that the Rpa49 and Rpa34 Pol I subunits, which do not have counterparts in Pol II and Pol III complexes, are functionally conserved using heterospecific complementation of the human and Schizosaccharomyces pombe orthologues in Saccharomyces cerevisiae. Deletion of RPA49 leads to the disappearance of nucleolar structure, but nucleolar assembly can be restored by decreasing ribosomal gene copy number from 190 to 25. Statistical analysis of Miller spreads in the absence of Rpa49 demonstrates a fourfold decrease in Pol I loading rate per gene and decreased contact between adjacent Pol I complexes. Therefore, the Rpa34 and Rpa49 Pol I-specific subunits are essential for nucleolar assembly and for the high polymerase loading rate associated with frequent contact between adjacent enzymes. Together our data suggest that localized rRNA production results in spatially constrained rRNA production, which is instrumental for nucleolar assembly.     

Bacteria and algae in stream periphyton along a nutrient gradient

1. Stream riffles in southern Ontario and western Quèbec were sampled for biomass (58 stations from 51 streams) and production (22 stations from 21 streams) of algae and bacteria in periphyton to test the hypothesis that bacteria in benthic biofilms compete with algae for nutrients. 2. Algal and bacterial biomass were positively correlated, as were algal and bacterial production. Bacterial production was also positively correlated to algal and bacterial biomass, but the relationship was not significant. The ratio of algal to bacterial biomass did not vary with nutrients whereas algal production tended to increase with nutrients more rapidly than bacterial production. 3. Instream nitrogen concentrations explained 38–58% of the variability in algal biomass and production. Bacterial abundance explained an additional 9–29% of the residual variance in algal production and biomass. However, the relationship between bacterial abundance and algal production and biomass, once nutrients were taken into account, was positive, in contrast to the predicted effect of competition. 4. Hence, we reject our original hypothesis that bacteria in biofilms compete with algae for nutrients and instead suggest that bacteria and algae in biofilms coexist in an association that offers space and resources to sustain production of both groups of organisms.     

Diversity in neuroblast number forming mushroom bodies of the higher dipterans (Insecta,Diptera, Brachycera Cyclorrhapha)

Neurogenesis in mushroom bodies is studied in 12 species of the higher dipterans. A significant difference in the number of neuroblasts forming mushroom bodies is found. In the majority of species studied, Kenyon cells are formed by four solitary neuroblasts. Among six calliphorid species, the number of neuroblasts increases up to 10–15 (mean 12.6) in each mushroom body in Calliphora vicina only. In young pupae of Muscina stabulans and M. livida, four polyneuroblastic prolipherative centers occur instead of solitary neuroblasts. These centers disintegrate later into numerous solitary neuroblasts. A hypothesis on the origin of the polyneuroblastic structure of mushroom bodies found in C. vicina and, earlier, in Musca domestica, is proposed.     

Histological structure of the mouthparts,clypeo-cibarial system,and cephalic foregut in <Emphasis Type="Italic">Philoliche rondani</Emphasis> (Diptera,Tabanidae, Pangoniinae)

The leading factor responsible for the evolution of Philoliche rondani mouthparts, as well as those of the other long-proboscid Pangoniinae, appears to be adaptation to the intake of nectar from concealed sources (flowers with elongated floral tube). Adaptations to blood-sucking, inherent only in females, have morphogenetic and behavioral aspects. Philoliche rondani males, as compared to males of Tabanus-like species, have better developed clypeus, labrum, and labium. The presence of a long proboscis has led to transformation of the labial musculature and complication of the food canal structure. During the intake of nectar, the distalmost portion of this canal is formed only by the labium. The lateral labial folds form a peculiar closing apparatus. The cibarial and pharyngeal pumps of Philoliche rondani are similar to those of other tabanids investigated.     

Embryonic development of mushroom bodies in <Emphasis Type="Italic">Pterostichus niger</Emphasis> schall. (Coleoptera: Carabidae)

This study demonstrates that the number of stem cells in mushroom bodies of the ground beetle Pterostichus niger increases already in the first half of embryogenesis and that this timing allows for an intensive increase of the number of neurons that compose the mushroom bodies during the second half of embryonic development. The degree of development of the mushroom bodies in new-born P. niger larvae was shown to be higher than that in new-born larvae of any other holometabolous insect investigated previously.     

Slow-wave fluctuations in craniosacral space: hemo-liquorodynamic conception of origin

In the paper, the mechanism of forming of rhythmic slow-wave fluctuations in craniospinal cavity was investigated. In five young healthy persons, at rest and under voluntary respiration arrest test, the bioimpedansograms of head and lumbosacral part of vertebral column were synchronously registered as these recordings reflect the changes of relationships between blood/CSF volumes in cranial and lumbosacral regions, respectively. The recordings were subjected to frequency and spectral computer analysis (PC Macintosh G-4, Chart 5.2. software). The rapid (pulsatile) as well as slow and counter-directed waves (frequency 6-10 cycles/min) of these processes were revealed in cranial and lumbosacral regions. The data obtained suggest the CSF dynamic concept of origin of the craniosacral rhythm. The pulse and slow-frequency oscillations of the cerebral vessels tone initiate corresponding intracranial pressure waves, and the latter are the motivating forces for to-and-fro CSF shifts in caudal direction. This mechanism is accompanied by tonic contractions of lumbar muscles and sacrum movements, and it is manually perceptible as a craniosacral rhythm.     

The influence of wind conditions in Europe on the advance in timing of the spring migration of the song thrush (<Emphasis Type="Italic">Turdus philomelos</Emphasis>) in the south-east Baltic region

Some of the factors that could influence changes in phenology of the song thrush (Turdus philomelos) during spring migration have been analyzed in relation to the timing of their return to the south-east Baltic region over the last 40 years. These include wind direction and velocity, temperature and precipitation in the wintering areas and along the migratory route. In March, a significant correlation was found between the timing of passage in the Baltic region and both the air temperatures in wintering area and winds over the migratory route. In April, when mass migration of thrushes occurs, the timing of passage was correlated with temperature, winds and, partly, precipitation over the route of migration. In this month, the frequency of tailwinds increased significantly along the route of migration from south-west France to the Baltic region over the last 40 years. The tailwind frequency was correlated with the beginning, middle and end of spring passage, accounting for 51% of the variance of median dates of the passage. The higher ambient temperatures over the migratory route explain nearly 20% of the variance in the timing of passage. Our results suggest that the advance in the timing of spring migration is primarily due to (1) the increased frequency of tailwinds favorable for migratory flights over the migratory route, and (2) the earlier emergence of the conditions enhancing migration due to higher spring temperatures in the winter quarters and on the migratory route.