Том 47, № 4 (2016)

Published data and the results of the authors’ own studies on the role of intracellular proteolytic enzymes and the metabolic and signaling processes regulated by these enzymes at certain stages of growth and development of salmonid fishes are analyzed in the present review. The major pathways of intracellular proteolysis relying on autophagy, proteasome activity, and calpain activity are considered, as well as the relative contribution of these pathways to proteolysis in skeletal muscle of the fish. Skeletal muscle accounts for more than half of the weight of the fish and undergoes the most significant changes due to the action of anabolic and catabolic signals. Special attention is paid to the intensity of protein degradation during the active growth period characterized by a high rate of protein synthesis and metabolism in fish, as well as to protein degradation during the reproductive period characterized by predomination of catabolic processes in contrast to the growth period. Skeletal muscle plays a unique role as a source of plastic and energy substrates in fish, and, therefore, the process of muscle protein degradation is regarded as a key mechanism for the regulation of growth intensity in juvenile salmon and for maintenance of viability and reproductive capacity of salmonid fish during the maturation of gametes, starvation, and migration related to spawning. The possibility of using a set of parameters of intracellular proteolysis to characterize the early development of salmonids is demonstrated in the review.

This review deals with the recent studies expanding the idea of positional information in the early embryogenesis of Drosophila melanogaster. Previous studies showed that, in the course of segment determination in Drosophila, information created by gradients of products of maternal coordinate genes is not “read” statically, being interpreted by their zygotic target genes via regulatory interactions. This leads to spatial shifts in the expression of target genes relative to the original positions as well as to dynamic reduction in the zygotic expression variability. However, according to recent data, interpretation of positional information includes the interaction between not only zygotic target genes but also the maternal coordinate genes themselves. Different systems of maternal coordinate genes (maternal systems)—the posterior-anterior, terminal, and dorsoventral—can interact with each other. This is usually expressed in the regulation of zygotic target genes of one maternal system by other maternal systems. The concept of a “morphogenetic network” was introduced to define the interaction of maternal systems during determination of spatial gene expression in the early Drosophila embryo.

Phospholipase A₂ (PLA2; EC 3.1.1.4) is a lipolytic enzyme and is one of the important components of the honeybee venom. Total RNA was extracted from four native honeybees in Thailand: Apis andreniformis, A. florea, A. cerana indica and A. dorsata. In each species, pupae’s whole body, house bees’ and foragers’ abdomen were used for RNA source. Reverse transcriptase polymerase chain reaction (RT-PCR) revealed PLA2 transcript expression levels were highest in house bees in all four tested species and were also highly expressed in foragers of A. florea and A. dorsata. However, there was no detectable PLA2 transcript expression in pupae. Furthermore, the crude protein extracts were isolated from the whole bodies of black-eyed pupae and abdomen of house bees. The PLA2 activity and specific activity levels in crude protein extracts mirrored the transcript pattern, being very low in the black-eyed pupae (0.01 to 0.05 μmol min^–1 mL^–1 and 0 Units (U)/mg) and higher in the house bees (1.46 to 5.64 μmol min^–1 mL^–1 and 1.78 to 2.26 U/mg in A. andreniformis, A. cerana indica and A. dorsata but only 0.29 μmol min^–1 mL^–1 and 0.72 U/mg in A. florea). DNA methylation in PLA2, investigated by bisulfite treatment and pyrosequencing, revealed a higher percentage of DNA methylation in A. florea and A. dorsata pupae (27.5 and 12%) than in house bees (9.4 and 7.0%). On the contrary, this was not the case in A. andreniformis or A. cerana indica, where no marked differences in the net DNA methylation level were found between developmental stadia. However, the percentage of DNA methylation was studied in about 120-bp fragment corresponding to the gene body. Thus, if DNA methylation is involved in the control of PLA2 expression in all four honeybee species, it may involve methylation of other sites outside of the investigated fragment and/or more specific localized CG islands.

Noggin proteins are important regulators of the early development of the vertebrate neural system. Previously, it has been traditionally thought that vertebrates have only one noggin gene (Noggin1), whose main function is the inhibition of BMP signaling pathway during the formation of dorsoventral polarity in embryos. Then other proteins of this family were discovered, and the studies of Noggin2 protein showed that noggin proteins also participate in the modulation of Nodal/Activin and Wnt/beta-catenin signaling pathways in the early development of amphibian head structures. The purpose of this study is to investigate the properties of another noggin protein, Noggin4. We proved that Noggin4 plays an important role in the formation of head structure in clawed frog, since it inhibits the activity of Wnt/beta-catenin signaling pathway. At the same time, unlike Noggin1 and Noggin2, Noggin4 does not inhibit the activity of TGF-beta signaling pathways (BMP and Nodal/Activin).

An increase in the proliferative activity of a shoot apical meristem (SAM) and the further accumulation of a pool of undifferentiated cells (fasciation) results in phyllotaxis changes. In the case of Arabidopsis thaliana, a typical spiral leaf arrangement is replaced by an opposite or verticillate one (depending on the level of a fasciation manifestation). Pistil development in mutant plants is accompanied by the appearance of a group of undifferentiated meristematic cells in its central part. The addition of N-1-naphthylphthalamic acid (NPA) causes an increase in the meristem volume and number of stipules in both mutant and control plants. The NPA effect on the floral morphogenesis results in a significant growth of meristemic cell pool. The interaction of different mechanisms of a meristem volume control is discussed.

The surface of Xenopus laevis embryos was marked with carbon particles, after which the location of mark groups was recorded by time-lapse video imaging and subsequent image analysis until their disappearance in the depth of gastric invagination. Measuring the distances between individually identifiable marks whose size is smaller than the size of a single cell makes it possible to quantitatively analyze the geometry of collective cell movement without any external coordinate system. During the dorsal blastopore lip (DBL) formation, the invagination of surface cells fundamentally differs from the preceding and subsequent lateromedial (LM) intercalation, being associated with a decrease in the meridional distance and an increase in the latitudinal distance between the marked surface sites. The sites that began to move towards the DBL later overtake the areas that started movement earlier, which leads to a “plug” in the movement of cells. Pushing the “plug” into the inner layers by changing the DBL shape becomes the rate-limiting stage of gastrulation; then, the directed cell movement is replaced by epiboly based on LM intercalation when the marks remaining on the outer surface of the marginal zone diverge along its meridians without directed migration towards the blastopore. As a result, directional movement of cells and LM intercalation become successive phases of collective cell movement, and the entire morphogenesis of DBL is the direct consequence of epiboly deceleration occurring upon gastric invagination.