[The temperature dependence of selection efficiency and the expression of the genes controlling the rate of embryonic development in Drosophila melanogaster].

We have already shown that selection of heterogeneous D. melanogaster populations for the rate of embryogenesis at 32 degrees C may produce populations, in which 50% of the larvae are hatched 20-40 min earlier, i.e.

[Properties of inbred Drosophila melanogaster lines obtained from a population selected for an increased rate of embryonic development].

Two heterogeneous Drosophila melanogaster populations were subjected to selection for an increased rate of embryonic development by picking out the first 10% of hatching larvae. After repeating this procedure in 15 generations, "fast" populations were obtained, in which the duration of embryonic development at high temperature (31-32 degrees C) was 30-40 min less than in nonselected control populations. The results of preliminary experiments on substituting the second and third chromosomes in the selected and control populations provide evidence that selected genes responsible for accelerated development are located on the second chromosome.

[The rate of development, temperature and genetic control].

The rate of poikilothermic animal development may be expressed quantitatively only with a specification of temperature at which this development occurs and on which this value depends. Therefore the species feature is not the rate of development itself but the character of its dependence upon the temperature and the range of temperature within which this development is possible. Obviously, the character of this dependence may be in principle expressed by an equation which functional form and parameters are inherited like all other features of the species.

[The nature of the dependence of the rate of development on temperature determines the greatest efficiency of metabolism at optimal temperatures].

Metabolism intensity and development rate have different pattern of dependence on temperature. Oxygen intake and several other metabolic processes bear an exponential relationship to temperature. The pattern of this relationship is similar in different poikilothermal species.

[The functioning of mammalian mitochondria injected into fish embryos].

The possibility of mammalian mitochondria functioning in fish embryos has been studied. Suspension of mitochondria isolated from the mouse fibroblast B-82/cap (chloramphenicol-resistant) and B-82 (chloramphenicol sensitive) cell cultures, were injected into the fertilized loach eggs. These embryos with an artificially increased number of mouse mitochondria developed and lived till the larval stages.

[Foreign DNA in developing embryos of the loach Misgurnus Fossilis L].

The fate of pAT153 DNA microinjected into the embryos of loach was examined. At the earliest stages of development (2 h) the high molecular weight transgenome consisting of pAT153 sequences is formed. The transgenome replicates intensively during the course of early development (until the blastula--early gastrula stages), but later the replication slows down which results in the elimination of the transgenome from the majority of embryos at more advanced stages.

[Cytophotometric and biochemical research on the amount of DNA in the nuclei of loach embryos injected with low-molecular RNA].

The cell cycle structure in the cells of loach embryos at the early blastula stage (5 h of development at 21 degrees) is markedly altered under the influence of injection of homologous low molecular weight nuclear RNA and, as a result, the number of cells in G2-phase. The DNA amount in the embryo increases by 20%. At the midblastula stage (7 h) no increase in the number of cells in G2-phase was found.

[Identification of cells with lowered sensitivity to cytostatic agents by the use of fluorescent dyes].

With a help of stepwise increase of vincristine concentrations in culture medium several lines of mouse myeloma X63 Ag 8.863 cells resistant to low concentrations of vincristine (6-35-fold) were selected. Rhodamine 123 stained resistant cells and wild-type cells with an equal intensity.

[Focal contacts and the cytoskeleton].

Cultured cells attach to the substratum by means of specialized domains of cell surface, called focal contacts. The inner side of the cell membrane is associated in these structures with cytoskeletal elements, while the outer side is connected with extracellular matrix. The present review describes both light and electron microscopic methods of studying the focal contacts and ultrastructure of adhesion plaque, that is the cytoskeletal domain of focal contact.

[Competition of solid and fluid liposomes for binding and metabolism with lipids from the cell surface].

The competitive behavior of solid vs. fluid liposomes in liposome-cell adsorption and cell-to-liposome lipid transfer processes was investigated with L cells and FBT epithelial sheets. Binding and transfer experiments have demonstrated that: solid liposomes adhere to the cell surface as integral vesicles retaining the entrapped substance; fluid liposomes are partly disintegrated at the cell surface with concomitant entry of entrapped substances into the cytoplasm, while their lipids remain on the cell surface; fluid liposomes that escape lysis dissociate from the cell taking away cell lipid molecules.

[Does DNA alone determine the development of the organism? (the information aspect of the problem)].

Two closely related controversial problems are discussed: whether the developmental processes can be reduced to the synthesis of polypeptides encoded in DNA, and whether the information in DNA is equivalent to that in the adult organism. Critically considered are the ideas that DNA is only responsible for the protein synthesis, whereas morphogenesis proceeds independently and according to epigenetic regularities of its own. It is stated that development is the realization of genetic information in which more elementary (molecular) processes unambiguously determine a more complex cellular level which in its turn determines morphogenesis of tissues and organs.

[Detection of complexes in the rat liver which contain lactate dehydrogenase, using centrifugation in a medium with a dissolved enzyme].

Liver and muscle extracts were fractionated by ultracentrifugation under conditions providing for the maintenance of the lactate dehydrogenase (LDH) containing complexes in the media with LDH. Under these conditions, part of the LDH activity (20-30%) was detected in the fractions corresponding to the particles with Mr 1 000 000-2 000 000. When LDH was substituted for by albumin, no LDH containing complexes were revealed.

[Regulation of the number and function of mitochondria during artificial increase of their mass in fish embryos].

The mechanisms of mitochondrial mass reduction were investigated by microinjection of mitochondria in developing loach embryos. This reduction can be due to the degradation of the injected mitochondria or to the triggering of regulatory mechanisms. In the latter case the decrease of mitochondrial excess should be caused by exogenous and endogenous mitochondria of the embryos.

[Distribution of solid liposomes on the surface of an epithelial cell layer].

A study was made of the adhesion of liposomes, composed of dipalmitoyl- or di-stearoylphosphatidycholine, on the surface of epithelial cells in culture. Sodium fluorescein was entrapped in liposomes for their visualization by fluorescence microscopy. It is found that sonicated unilamellar liposomes adhere predominantly along the sheet margins.

[Activation of RNA synthesis in loach embryos after injection of a nuclear extract obtained by using 0.35 M NaCl].

An extract mainly containing chromatin nonhistone proteins was obtained by means of 0.35 M NaCl from nuclei isolated from loach (Misgurnus fossilis L.) embryos at the 18 hour developmental stage (late gastrula).

[Injection of mitochondria into oocytes and fertilized eggs].

The suspension of mitochondria isolated from the loach embryos or the frog heart were injected in the oocytes or fertilized eggs of the loach, newt, toad and frog in the amount roughly equivalent to the content of mitochondria in the egg. After the injection the oocytes did not differ during several days from the normal ones and the fertilized eggs of the loach, newt and South Afican clawed toad developed normally. The activity of cytochrome oxidase in the injected oocytes was kept at a somewhat higher level (1.

[Expression of paternal genes controlling cytochrome oxidase activity in hybrid fish].

The heat resistance of the oxygen consumption by the mitochondria, temperature dependence of the Michaelis' constant (CM) and heat resistance of cytochrome oxidase were studied in the embryos and larvae of fish hybrids (Misgurnus X Brachydanio). The oxygen consumption by the mitochondria from the larvae of Misgurnus ceased (following the 10 min heating) at 50 degrees, from Brachydanio at 54 degrees and from the hybrids at 52 degress suggesting control of the respiratory function. CM of cytochrome oxidase has the same minimum in the larvae of Misgurnus and Brachydanio, therefore this criterion was not used to study the genetic control in their hybrids.

[Expression of genes controlling esterases during the embryonic development of hybrid fish].

The electrophoretic mobility of several enzymes was studied in the embryos and early larvae of the hybrids between the loach (Misgurnus fossilis) and the aquarial cyprinids and cobitids (Acanthophthalmus). The cytosol aspartate aminotransferase is represented by one protein with the same mobility at all developmental stages both in the loach and in the hybrids. Malate dehydrogenase manifests four bands of isozymes which suffer no changes during the development.