Oncogenic point mutations in the Myb DNA-binding domain alter the DNA-binding properties of Myb at a physiological target gene

The oncoprotein v-Myb of avian myeloblastosis virus (AMV) transforms myelomonocytic cells by deregulating specific target genes. Previous work has shown that the oncogenic potential of v-Myb was activated by truncation of N- and C-terminal sequences of c-Myb and was further increased by amino acid substitutions in the DNA-binding domain and other parts of the protein. We have analyzed the activation of the chicken lysozyme gene which is strongly activated by c-Myb but not by its oncogenic counterpart v-Myb. We report that Myb acts on two different cis-regulatory elements, the promoter and an enhancer located upstream of the gene. Interestingly, the activation of the enhancer was abolished by the oncogenic amino acid substitutions. We demonstrated that a single Myb-binding site is responsible for the activation of the lysozyme enhancer by Myb and showed that the v-Myb protein of AMV was unable to bind to this site. Our data demonstrate for the first time that oncogenic activation of Myb alters its DNA-binding specificity at a physiological Myb target gene.     

Application of machine learning to identify predators of stocked fish in Lake Ontario: using acoustic telemetry predation tags to inform management

Understanding predator–prey interactions and food web dynamics is important for ecosystem-based management in aquatic environments, as they experience increasing rates of human-induced changes, such as the addition and removal of fishes. To quantify the post-stocking survival and predation of a prey fish in Lake Ontario, 48 bloater Coregonus hoyi were tagged with acoustic telemetry predation tags and were tracked on an array of 105 acoustic receivers from November 2018 to June 2019. Putative predators of tagged bloater were identified by comparing movement patterns of six species of salmonids (i.e., predators) in Lake Ontario with the post-predated movements of bloater (i.e., prey) using a random forests algorithm, a type of supervised machine learning. A total of 25 bloater (53% of all detected) were consumed by predators on average (± S.D. ) 3.1 ± 2.1 days after release. Post-predation detections of predators occurred for an average (± S.D. ) of 78.9 ± 76.9 days, providing sufficient detection data to classify movement patterns. Tagged lake trout Salvelinus namaycush provided the most reliable classification from behavioural predictor variables (89% success rate) and was identified as the main consumer of bloater (consumed 50%). Movement networks between predicted and tagged lake trout were significantly correlated over a 6 month period, supporting the classification of lake trout as a common bloater predator. This study demonstrated the ability of supervised learning techniques to provide greater insight into the fate of stocked fishes and predator–prey dynamics, and this technique is widely applicable to inform future stocking and other management efforts.     

Peculiarities of brain mechanisms of regulation of level of wakefulness and of cognitive activity in children with retardation of psychic development and in healthy children of the same age

The work opens possibilities of the of modifications of the developed at the Laboratory systemic-integrative psychophysiological approach to study of the age-related organization or of deviation from norm in formation of superslow informational-controlling brain systems participating in mechanisms of regulation of the wakefulness level and of cognitive activity in the 5–7-year old healthy children and in children of the same age group with retardation of psychic and speech development of the cerebral-organic genesis. There are disclosed peculiarities of organization of: (a) cortical-brainstem and limbic-reticular mechanisms of regulation of the level of wakefulness; (b) suprasegmentary mechanisms of autonomic, hemodynamic, and oxygen-dependent energy supply of the wakefulness level in the examined children’s contingent. There are substantiated concepts about interrelations of peculiarities of the level of actual development of emotional and cognitive spheres with age-related peculiarities or disturbances of formation of mechanisms of regulation of the wakefulness level, its autonomic and hemodynamic provision as well as of the oxygen-dependent energetic potential.     

Effects of dehydroepiandrosterone sulfate on induced apoptosis of lymphocytes in healthy persons

The effect of dehydroepiandrosterone sulfate on oxidative stress- and ethanol-induced morphological changes and the level of apoptotic enzymes (Bcl-2 and caspase-3) of lymphocytes in six healthy persons were studied. It was shown that hydroperoxide induced apoptotic changes in lymphocytes. The addition of ethanol to the culture medium caused no significant changes in the parameters studied. Dehydroepiandrosterone sulfate had a marked antiapoptotic effect on the peripheral blood lymphocytes of healthy subjects, protecting them from the harmful effects of reactive oxygen species.     

An Alteration in ELMOD3, an Arl2 GTPase-Activating Protein,Is Associated with Hearing Impairment in Humans

Exome sequencing coupled with homozygosity mapping was used to identify a transition mutation (c.794T>C; p.Leu265Ser) in ELMOD3 at the DFNB88 locus that is associated with nonsyndromic deafness in a large Pakistani family, PKDF468. The affected individuals of this family exhibited pre-lingual, severe-to-profound degrees of mixed hearing loss. ELMOD3 belongs to the engulfment and cell motility (ELMO) family, which consists of six paralogs in mammals. Several members of the ELMO family have been shown to regulate a subset of GTPases within the Ras superfamily. However, ELMOD3 is a largely uncharacterized protein that has no previously known biochemical activities. We found that in rodents, within the sensory epithelia of the inner ear, ELMOD3 appears most pronounced in the stereocilia of cochlear hair cells. Fluorescently tagged ELMOD3 co-localized with the actin cytoskeleton in MDCK cells and actin-based microvilli of LLC-PK1-CL4 epithelial cells. The p.Leu265Ser mutation in the ELMO domain impaired each of these activities. Super-resolution imaging revealed instances of close association of ELMOD3 with actin at the plasma membrane of MDCK cells. Furthermore, recombinant human GST-ELMOD3 exhibited GTPase activating protein (GAP) activity against the Arl2 GTPase, which was completely abolished by the p.Leu265Ser mutation. Collectively, our data provide the first insights into the expression and biochemical properties of ELMOD3 and highlight its functional links to sound perception and actin cytoskeleton.     

Effects of noradrenaline on neuronal response induced in the motor cortex by conditioned stimuli

In chronic experiments on cats, the effects were investigated of iontophoretic application of the adrenomimetic ephedrine and the -blocker obsidan (propranolol) on neuronal response induced in the motor cortex by conditioned stimulus presentation during performances of instrumental lever-pressing response. Inhibition of background firing activity and response in most neurons induced by conditioned stimuli was produced by ephedrine, whereas obsidan application enhanced this activity. It was concluded that steady, tonic inhibitory action of the noradrenergic system on background and induced firing activity in cortical neurons takes place during free-ranging behavior. Temporary reinforcement of noradrenergic influences could be an important element in mechanisms of external inhibition during stressful situations, aversive effects, and distractive stimuli.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 22, No. 5, pp. 680–688, September–October, 1990.     

A physiological analysis of dissociative learning against a background of physostigmine and pentobarbital

Physostigmine (0.7-0.8 mg/kg, i.p.) decreased and pentobarbital (13.4-14.6 mg/kg) increased the locomotor and emotional activity of rats in the "open field". Both drugs induced the reversible amnesia to a conditioned reaction in a double T-maze with positive (nutritional) reinforcement. These changes in behavioral activity were correlated with dissociated learning of rats after the injection of the drugs: physostigmine largely decreased the number of errors during learning as compared with pentobarbital. However, in both cases rats reached the learning criterion sooner than the control animals due to the shorter reaction latency (physostigmine) and increase in general motor activity (pentobarbital).     

Fibronectins: Structural-functional relationships

This review summarized current data on the structure of fibronectin (FN), a multifunctional glycoprotein of vertebrates. FN is not only a permanent component of the extracellular matrix (ECM) but also an important regulator of cell functions via transformation of the ECM composition and organization and/or interaction with receptor and other membranebound cell proteins. Multifunctionality of FN owes hierarchical relationships between its structuralfunctional determinants, which comprise the linear ones (FN peptide fragments), association zones (surface contacts between the FN molecule and a FN-associated protein) and functional domains (those binding fibrin, heparin, gelatin and integrins). The modular architectonic principle of FN organization is pivotal to intrinsic adaptation of this glycoprotein to changing microenvironmental conditions. We also discuss the issue of key stages of FN fibrillogenesis with a special focus on the molecular mechanisms that underlie polymerization of FN molecules.     

G(i) proteins in regulation of water permeability of the rat kidney collecting tube epithelium cell membrane

Principal mechanism of the transepithelial water permeability increase in the kidney collecting ducts in response to vasopressin involves insertion of aquaporin 2 (AQP2) into the apical membrane. Previously we have shown that water permeability of the basolateral membrane also may be increased with stimulation of V2-receptors. It is known that inhibition of G(i)-proteins with pertussis toxin blocks redistribution of AQP2 into the apical membrane following the application of vasopressin or forskolin. The aim of the present study was to investigate potential involvement of G(i)-proteins in regulation of basolateral membrane water permeability. Effect of pertussis toxin on the ability of desmopressin to increase the basolateral membrane osmotic water permeability was investigated, and the expression of Galpha(i)2 and Galpha(i)3 genes under normal conditions and after 2 days of water deprivation were evaluated. We demonstrated that dehydration leds to a 30% increase of Galpha(i)3 mRNA content while the Galpha(i)2 mRNA level remains unchanged. In control experiments, basolateral membrane water permeability increased in response to desmopressin from 59.2 +/- 6.61 to 70.6 +/- 9.2 microm/s (p < 0.05, paired t-test). Pertussis toxin completely blocked this reaction (53.5 +/- 5.18 vs 50.1 +/- 6.50 microm/s, respectively). We conclude that G(i)-proteins participate in the mechanism of the basolateral membrane water permeability increase in response to stimulation of V2-receptors. Clarification of the G(i)-proteins role in this process requires further investigation, but most likely they are involved in regulation of aquaporin transport and insertion into the cell membrane.