Interspecific and intraspecific variation of the duration and thermal requirements for egg development in carabid beetles (Coleoptera,Carabidae) in the North-West of Russia

The thermal norms of egg development were studied in the ground beetles Amara communis, A. nitida, Carabus granulatus, Platynus assimilis, Poecilus versicolor, Pterostichus oblongopunctatus (spring breeding species), P. melanarius, and P. niger (autumn breeding species). The adults were collected in soil traps near Arkhangelsk, St. Petersburg, Moscow, and Bryansk in May–June. Females and males were kept in pairs at 20°C and 22 h light per day. The eggs laid by females were kept at constant temperatures (12, 14, 16, 18, 20, and 22 ± 0.1°C). The development time for each egg was determined accurate to 0.5 day. From the values of the individual development rate (a reciprocal of development time) at all the temperatures, the thermal constants for development were calculated: the coefficient of linear regression (CLR) of the development rate on temperature, the sum of degree-days, and the thermal threshold for development (TTD). The egg development time was found to vary significantly between the species, except for A. communis, A. nitida, and C. granulatus. The values of CLR (i.e., the slopes of the regression lines) and TTD varied rather distinctly between the species and populations that revealed differences in the thermal requirements for egg development. In the spring breeding species the mean egg development time was significantly shorter, and the CLR and TTD values were on average higher than those of the autumn breeding species. Intraspecific latitudinal variation of the development time and the thermal requirements for egg development was revealed. The eggs laid by beetles from the Arkhangelsk population developed faster than those of the same species from the southern populations at all experimental temperatures. These differences were not great but statistically significant. At the same time, the differences between the CLR and TTD values for the northern and southern populations of the same species were non-significant in most cases. Thus, the main ecophysiological adaptation of carabid beetles during their northward expansion was the shortening of development time within the entire range of favorable temperatures, while the CLR and TTD values only insignificantly changed.     

Genetic diversity of flat-headed vole (Alticola strelzowi (Kastschenko, 1899)) inferred from cytochrome b variation

Variation of the cytochrome b gene fragment was examined in 27 flat-headed voles Alticola strelzowi from different parts of the species range. A total of 15 haplotypes were described, while the species as a whole was characterized by low levels of genetic differentiation and polymorphism. The haplotypes fell into three haplogroups, one of which corresponded to the subspecies A. s. strelzowi, and the other two, to A. s. desertorum. Based on different index values, the level of genetic polymorphism in the later subspecies was considered to be higher than in the first one. Phylogeographic analysis suggested post-glacial dispersal of flat-headed voles from a single refugium located in Western Altai. Using different techniques, relatively recent colonization of the Central Altai territory was demonstrated (subspecies A. s. strelzowi), which determined low level of genetic variation in this territory.     

Differential Participation of Central L-Glutamate Receptors of non-NMDA-Subtype in Associative Learning of the Honeybee Apis mellifera

Participation of non-NMDA-receptors in associative learning in the honeybee was analyzed using a complex approach. There were studied effects of systemic and intracerebral AMPA injections on retention of the elaborated conditional reflex in short-term memory, on dynamics of the bioelectrical activity of neurons of calyx of the mushroom bodies, and on the limb locomotor activity. It has been shown that the systemic and intracerebral AMPA injections stimulate processes of short-term memory and activate bioelectrical activity of neurons of the mushroom body medial calyx. Antagonist of AMPA-receptors NS-257 HCl suppressed spontaneous activity of these neurons. The observed processes did not depend on the character of locomotor activity. These results confirm the hypothesis proposed earlier about involvement of non-NMDA-receptors in the process of associative learning.     

Determination of the adenine-specific methylase recognition site of Shigella sonnei 47, using hydrazinolysis with subsequent separation of purine oligonucleotides by thin layer chromatography on DEAE- cellulose

A procedure for separation of oligopurine blocks of different length and composition by two-dimensional thin layer chromatography on DEAE-cellulose plates has been developed. This method allows a comparative analysis of the purine isostich content in the DNAs of various origin. In case of methylated DNA, the method permits to compare the substrate specificity of different enzymes responsible for the adenine residue methylation in the DNA. In combination with enzymatic treatment of labeled methylated isostichs, the method described can be used for the deciphering of the methylated sequences as well as for constructing, in a number of cases, the recognition site of adenine-specific methylases. Thus, it was demonstrated that methylase SsoI recognizes the 5...G-A-A-T-T-C ... 3' sequence and methylates its adenine residue nearest to the 5'-end.     

Temperature and Photoperiodic Control of Development in the Green Shield Bug Palomena prasina (L.) (Heteroptera,Pentatomidae) in Leningrad Province

Thermal reaction norms for development (the lower temperature threshold, temperature sensitivity, and sum of degree-days) can show phenotypic plasticity in response to a combination of ecological factors. The goal of this study was to evaluate the degree of plasticity of the thermal reaction norms for development under different photoperiodic conditions in the green shield bug Palomena prasina. Experiments were conducted in 2015 and 2016. In 2015, two photoperiodic regimens (12 and 22 h of light per day) and five constant temperatures (20, 22, 24, 26, and 28°C) were used; a lower temperature of 16°C was added in 2016. There were no differences in the egg developmental time between the two photoperiodic conditions and across the two experiments. Under the short-day photoperiodic regimen, nymphal development was faster at all the temperatures and was characterized by greater thermal sensitivity and a higher temperature threshold than under the long-day photoperiod. Besides, the relationship between the developmental rate and temperature deviated from linearity at 26 and 28°C under short-day conditions. The adaptive nature of the observed nymphal response to photoperiodic conditions was confirmed by our phenological observations and an outdoor cage experiment. The adult body mass slightly increased with rising temperature under short-day conditions but did not depend on the temperature under long-day ones. Females were larger than males, and both sexes had a greater body mass under long-day conditions than under short-day ones. In 2015, the eggs for experiments were collected before mid-July, almost a month later than in 2016. Nymphs that hatched from the later eggs (in 2015) had significantly higher relative growth rates than the early-season nymphs (in 2016) at 20, 22, and 24°C under both photoperiods. This discrepancy between years was probably related to the maternal effect, namely, the difference in the female physiological age.

     

Proliferative activity and structure-functional organization of chromosomes in cells from the developing brain in respect to genetically determined excitability of the rat nervous system]

Neuroblasts of developing hippocampus of 16-17-day old rat embryo of the line with high threshold excitability are characterised by a high level of proliferative activity and chromosome aberration, as well as high degree of brain chromatin concentration as compared with embryos of a line with low threshold excitability.     

The influence of temperature transfers on subsequent growth of the European peacock butterfly <Emphasis Type="Italic">Inachis io</Emphasis> (Lepidoptera,Nymphalidae)

The study addresses the effects of higher and lower temperatures experienced during the early stages of ontogeny on the parameters of the subsequent growth and development of the butterfly Inachis io. The caterpillars reared at a temperature of 22°С during instars I–III and then transferred to lower temperatures (16, 18, and 20°C) had higher instantaneous growth rates, larger body mass, and shorter duration of instars IV and V than the caterpillars that developed permanently at these lower temperatures. Vice versa, the caterpillars reared at 16°С during instars I–III and transferred to higher temperatures (18, 20, and 22°C) developed and grew slower than the caterpillars reared at these higher temperatures from the beginning. Possible physiological mechanisms underlying the observed phenomena and their ecological consequences are discussed. Our results are compared with the previously published data on fish—another group of ectothermic organisms, on which similar experiments have been carried out.