The temporal pattern of interphase prolongation and nuclear activities during early embryogenesis in teleostei

Summary Temporal relationship between the beginning of the increase of interphase duration, RNA synthesis in the nuclei and morphogenetic function of nuclei have been studied using dimensionless criteria of development duration. Experiments were performed in the trout (Salmo trutta m.fario andSalmo irideus), the whitefish (Coregonus lavaretus), the pike (Esox lucius) and the carp (Cyprinus caprio). In all these species interphase begins to lengthen approximately at the same developmental stages. The onset of morphogenetic nuclear function in the pike and whitefish coincides with the onset of interphase prolongation; in the carp RNA synthesis in the nuclei and morphogenetic nuclear function were revealed by 2 ₀ earlier than onset of interphase prolongation, and in the trout, by 5 and 13 ₀ later, respectively. Thus, a temporal disconnection between the onset of interphase prolongation, RNA synthesis in the nuclei and morphogenetic nuclear function was established for the first time. It can be suggested that the character of temporal relationship between these processes depends on the relative quantity of yolk in the eggs.

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Zusammenfassung In der Embryogenese von Forelle, Weißfisch, Hecht und Karpfen ist untersucht worden, welche zeitlichen Beziehungen bestehen zwischen dem Beginn der Zunahme der Interphasedauer, der RNS-Synthese in den Kernen und der morphogenetischen Funktion der Kerne. Bei allen genannten Arten verlängert sich die Interphase etwa in dem gleichen Entwicklungsstadium. Beim Hecht und beim Weißfisch beginnt die morphogenetische Funktion der Kerne gleichzeitig mit der Verlängerung der Interphasedauer; beim Karpfen setzen RNS-Synthese und morphogenetische Funktion der Kerne zwei Zeiteinheiten ( ₀) früher ein als der Beginn der Interphaseverlängerung, bei der Forelle dagegen 5 bzw. 13 Zeiteinheiten später. Damit ist erstmals gezeigt worden, daß kein zeitlicher Zusammenhang besteht zwischen dem Beginn von Interphaseverlängerung, RNS-Synthese in den Kernen und morphogenetischer Funktion der Kerne. Vermutlich hängt die zeitliche Beziehung zwischen diesen Vorgängen vom relativen Dottergehalt der Eier ab.

     

Integrated computer system for regulating eukaryotic gene expression

The review describes several modules of the GeneExpress integrated computer system concerning the regulation of gene expression in eukaryotes. Approaches to the presentation of experimental data in databases are considered. The employment of GeneExpress in computer analysis and modeling of the organization and function of genetic systems is illustrated with examples. GeneExpress is available at http://wwwmgs.bionet.nsc.ru/mgs/gnw/.     

Planning and design of ecological networks in urban areas

Urban ecological networks are defined differently in ecology, urban planning and landscape ecology, but they all have linearity and linkage in common. Early urban representations evolved from the constraints of deep ecological structure in the landscape to built elements that must work around natural linear obstacles—rivers, coastlines, dunes, cliffs, hills and valley swamps. Village commons were linked by roads. The Industrial Revolution led to accelerating urban growth, where the role of open space focussed on public health and transport. The Renaissance, Baroque and Picturesque movements accentuated networks in wooded parks, boulevards and sweeping riverine vistas. These provided a new aesthetic and sense of grandeur in the urban centres of European empires and later their colonies. Grafted onto this visual connectivity has been an awakened ecological understanding of spatial dynamics. The emergent notion of ecological corridor functionality provided support for green linear features, although initially this was based on untested theory. The idea of organisms moving along green highways seemed logical, but only recently has unequivocal empirical evidence emerged that demonstrates this functionality. Nevertheless, the main role of corridors may be to provide habitat rather than to act as connectors of nodal habitats. Most organisms can utilise stepping stones, and these may accommodate desired meta-populations while deterring pest movement. Swale drains and treatment wetlands provide riparian services and serve as biodiversity corridors. However, to most people the obvious function is visual—providing green fingers through what would otherwise be urban grey. The health benefits of these are have been demonstrated to be psychological as much as biophysical.     

Transformation of the dermal collagen framework under laser heating

The aim of this study was to compare between the changes undergone by the dermal collagen framework when heated by IR laser radiation and by traditional means and to reveal the specific features of the dermal matrix modification under moderate IR laser irradiation. Rabbit skin specimens were heated to 50°C, 55°C, 60°C and 65°C in a calorimeter furnace and with a 1.68‐μm fiber Raman laser. The proportion of the degraded collagen macromolecules was determined by differential scanning calorimetry. Changes in the architectonics of the collagen framework were revealed by using standard, phase‐contrast, polarization optical and scanning electron microscopy techniques. The collagen denaturation and dermal matrix amorphization temperature in the case of laser heating proved to be lower by 10°C than that for heating in the calorimeter furnace. The IR laser treatment of the skin was found to cause a specific low‐temperature (45°C‐50°C) transformation of its collagen framework, with some collagen macromolecules remaining intact. The transformation reduces to the splitting of collagen bundles and distortion of the course of collagen fibers. The denaturation of collagen macromolecules in the case of traditional heating takes its course in a threshold manner, so that their pre‐denaturation morphological changes are insignificant.