Photoperiod-temperature interaction-a new form of seasonal control of growth and development in insects and in particular a Carabid Beetle, <Emphasis Type="Italic">Amara communis</Emphasis> (Coleoptera: Carabidae)

Amara communis larvae were found to develop significantly faster and to have higher growth rate at short-day (12 h) as compared to long-day (22 h) photoperiods at all used temperatures (16, 18, 20, and 22°C). The coefficient of linear regression of larval development rate on temperature was significantly higher at the short day than at the long day. The thermal developmental thresholds appeared similar at both photoperiods. Body weight of young beetles reared under different photoperiods was almost the same. Thus, photoperiod does not simply accelerate or decelerate insect development, but modifies the thermal reaction norm. At short days, larval development becomes faster and more temperature-dependent, which provides a timely completion of development at the end of summer. The analysis of literature data has allowed us to find the photoperiodic modification of thermal requirements for development in 5 insect orders: Orthoptera, Heteroptera, Coleoptera, Lepidoptera, and Diptera. Modification may result in significant changes in the slope of the regression line, and hence the sum of degree-days, and in the thermal developmental threshold. Consequently, the thermal requirements for development in many insects gradually vary during summer under the effect of changing day-length, which may have adaptive significance. Thus, the photoperiodic modification of thermal reaction norms acts as a specific form of seasonal control of insect development.     

Development of a 3D finite element model of lens microcirculation

Background

It has been proposed that in the absence of a blood supply, the ocular lens operates an internal microcirculation system. This system delivers nutrients, removes waste products and maintains ionic homeostasis in the lens. The microcirculation is generated by spatial differences in membrane transport properties; and previously has been modelled by an equivalent electrical circuit and solved analytically. While effective, this approach did not fully account for all the anatomical and functional complexities of the lens. To encapsulate these complexities we have created a 3D finite element computer model of the lens.

Methods

Initially, we created an anatomically-correct representative mesh of the lens. We then implemented the Stokes and advective Nernst-Plank equations, in order to model the water and ion fluxes respectively. Next we complemented the model with experimentally-measured surface ionic concentrations as boundary conditions and solved it.

Results

Our model calculated the standing ionic concentrations and electrical potential gradients in the lens. Furthermore, it generated vector maps of intra- and extracellular space ion and water fluxes that are proposed to circulate throughout the lens. These fields have only been measured on the surface of the lens and our calculations are the first 3D representation of their direction and magnitude in the lens.

Conclusion

Values for steady state standing fields for concentration and electrical potential plus ionic and fluid fluxes calculated by our model exhibited broad agreement with observed experimental values. Our model of lens function represents a platform to integrate new experimental data as they emerge and assist us to understand how the integrated structure and function of the lens contributes to the maintenance of its transparency.     

Synthesis of triterpenoid acylates: Effective reproduction inhibitors of influenza A (H1N1) and papilloma viruses

The synthesis of a new group of triterpenoid acylates has been conducted on the basis of oleanolic, glycyrrhetic, and ursolic acids and betulin. 28-ortho-Methoxycynnamoylbetulin has been demonstrated to possess high activity against the influenza type A (H1N1) virus with the selectivity index SI > 100 while studying the activity of the synthesized compounds in relation to the reproduction of viral pathogens of respiratory infections. The high activity of 3,28-dinicotinoylbetulin against the papilloma virus (strain HPV-11) was detected with the selectivity index SI 35.     

Synthesis and cytotoxicity of triterpene seven-membered cyclic amines

3-Deoxy-3a-homo-3a-aza derivatives of betulin and erythrodiol have been synthesized from betulonic and oleanonic acids. 3-Deoxy-3a-homo-3a-aza-28-hydroxy-12(13)-oleanene showed the highest antineoplastic activity of the broad spectrum in vitro; the results of an extensive examination of the derivative in vitro enable one to recommend it for in vivo tests. The modification of the compound in the position C28 by the introduction of a methoxycinnamoyl fragment led to the loss of the antineoplastic activity. As a whole, 3-deoxy-3a-homo-3a-aza derivatives of betulin [3-(aminopropyl)-, 28-(2-carboxyethyl)carboxy-, and 28-cinamoyloxy-] exhibited a moderate antineoplastic activity toward large intestine cancer, breast cancer, and leukemia cells.     

The influence of late pleistocene mountain glaciations on the genetic differentiation of long-tailed ground squirrel (<Emphasis Type="Italic">Urocitellus undulatus</Emphasis>)

Long-tailed ground squirrel (Urocitellus undulatus) is a polytypic species with a wide distribution from the Tien Shan to the Amur River region. Previously, considerable genetic differentiation between eastern and western populations of this species was demonstrated. Moreover, the greatest differences were observed in the western part of the range located in Central Asia, the region that was subjected to repeated glaciations in the past and represents one of the centers of the ground squirrel secondary diversification. The analysis of polymorphism of the mitochondrial DNA control region was carried out on long-tailed ground squirrels living in the northern part of Central Asia, on the territory of the Altai Mountains (45 individuals from 23 localities). The presence of two genetically differentiated (7.7% differences) and geographically separated lineages (western and eastern) was revealed. The data obtained disprove the hypothesis on unidirectional, from west to east, colonization of the Altai Mountains after the end of the last glacial maximum and show the two pathways of the ground squirrel colonization of the Altai, from both western and eastern refugia.     

Effect of Na(+), K(+)-pump inhibitors on the sensory ganglia neurite growth

Inhibitors of Na(+), K(+)-pump belonging to the class of cardiac glycosides were investigated in organotypic tissue culture of dorsal root ganglia cells of 10-12 days old chicken embryos. The data obtained show that the application of cardiac glycosides (strophantin K and digoxin) in a wide range of concentrations controls the neurite growth in sensory neurons in the dose-dependent manner. It was shown, that at the concentrations of cardiac glycoside exceeding 1 x 10(-6) M the growth of neurites was totally inhibited. Our data indicate that cardiac glycoside have the down-regulation effect on the neurite growth. The data obtained indicate that the Na(+), K(+)-ATPase is involved in the control of the process of neurite growth as a signal transducer.