Agr2‐interacting Prod1‐like protein Tfp4 from Xenopus laevis is necessary for early forebrain and eye development as well as for the tadpole appendage regeneration

The Agr family genes, Ag1, Agr2, and Agr3, encode for the thioredoxin domain containing secreted proteins and are specific only for vertebrates. These proteins are attracting increasing attention due to their involvement in many physiological and pathological processes, including exocrine secretion, cancer, regeneration of the body appendages, and the early brain development. At the same time, the mode by which Agrs regulate intracellular processes are poorly understood. Despite that the receptor to Agr2, the membrane anchored protein Prod1, has been firstly discovered in Urodeles, and it has been shown to interact with Agr2 in the regenerating limb, no functional homologs of Prod1 were identified in other vertebrates. This raises the question of the mechanisms by which Agrs can regulate regeneration in other lower vertebrates. Recently, we have identified that Tfp4 (three‐fingers Protein 4), the structural and functional homolog of Prod1 in Anurans, interacts with Agr2 in Xenopus laevis embryos. In the present work we show by several methods that the activity of Tfp4 is essential for the tadpole tail regeneration as well as for the early eye and forebrain development during embryogenesis. These data show for the first time the common molecular mechanism of regeneration regulation in amphibians by interaction of Prod1 and Agr2 proteins.     

Effect of potassium phenosan on structure of plasma membranes of mice liver cells in vitro

The effect of synthetic anti-oxidant potassium phenosan (PP, potassium salt of β-(4-hydroxy-3,5-ditretbutil-phenyl)-propionic acid) on the structural state of the surface (8 Å) and deep (20–22 Å) lipid regions of plasma membranes of mice liver cells was studied by spin probes method in vitro in a wide range of concentrations (10^?5–10^?21 M). Two stable free radicals, 5- and 16-doxyl-stearic acids (C₅ and C₁₆), were used as spin probes. The nonlinear polymodal dose-effect dependences were obtained for parameters that characterize the microviscosity of the lipid bilayer (τ_c) in the site of localization of the probe C₁₆, and the order parameter (S), which characterizes the stiffness of the surface layers of lipids in the site of localization of the probe C₅. Statistically a reliable increase was observed for parameter τ_c after addition of PP at concentrations 10^?5–10^?7 M and 10^?18–10^?19 M, and for parameter S after addition of PP at concentrations 10^?6–10^?7 M and 10^?13–10^?15 M. Peaks on both dose-effect curves were separated by the intervals of concentrations where PP had no effect on the studied physico-chemical characteristics of biomembranes. For PP concentrations which caused maximal changes in τ_c and S, we investigated thermal dependence of these parameters and determined the thermally induced structural transitions. Comparing with control, ultra-low doses of PP (10^?13–10^?15 M) and (10^?18–10^?19 M) caused an appearance of additional thermally induced structural transition in the surface and deep regions of plasma membrane lipids. The possible role of the interaction of PP molecules with specific binding sites on plasma membranes and formation of nanoparticles of PP in very dilute aqueous solutions are discussed.     

Rapid hyperthyroidism-induced adaptation of salmonid fish in response to environmental pollution

The streams draining volcanic landscapes are often characterized by a complex series of factors that negatively affect hydrobionts and lead to declines in their populations. However, in a number of cases, a range of rapid adaptive changes ensure the resilience of hydrobiont populations. Here, we present both field and experimental data shedding light on the physiological basis of adaptation to heavy metal contamination in populations of Dolly Varden charr (Salvelinus malma) differing in duration of isolation in volcanic streams. The study reveals that isolated populations have a physiological phenotype that distinguishes them from populations inhabiting clean waters. They are characterized by a hyperthyroid status accompanied by an increased metabolic rate, elevated activity of antioxidant enzymes, decreased ionic conductivity of tissues and reduced stored energy reserves. Our experimental data reveal that hyperthyroidism is an adaptive characteristic enhancing the resistance to heavy metal contamination and shaping the evolution of these populations. The similarity of physiological, developmental and morphological changes in isolated populations suggests a common source and mechanisms underpinning this case of ‘evolutionary rescue’. Thus, populations of S. malma trapped in volcanic streams represent a genuine case of rapid endocrine-driven adaptation to changing environmental stimuli.     

A biometric method for determining the sex of acipenserids, including the Russian sturgeon Acipenser gueldenstaedtii (Acipenseridae) of the Azov Population

With reference to the Russian sturgeon Acipenser gueldenstaedtii of the Azov Population, it is demonstrated that the sex of acipenserids may be determined biometrically. A measurement scheme of the head is suggested, which gives the possibility to determine gender in live sturgeons. A discriminate equation is composed for the identification of the sex of individuals of the Russian sturgeon in a sufficiently wide size-age range, irrespective of the maturity stage of the gonads.