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1

The electrophysiological studies of mammals circadian clock mechanism

100%
Lewandowski M. H.
|
|
issue 3
331-339
EN
The mammalian circadian time-keeping system is established by two major neural structure: the suprachiasmatic nucleus (SCN) of the anterior hypothalamus and the intergeniculate leaflet (IGL) of the thalamus. Both these structures display the ultradian isoperiodic oscillation of the level of neuronal firing which probably constitute a basic activity necessary to generate circadian rhythms. In the present study we discuss the nature, pharmacology and the serotonergic influences on this oscillation in IGL.
2

Genetic mechanisms underlying male sex determination in mammals

80%
Piprek R. P.
Journal of Applied Genetics
|
2009
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vol. 50
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issue 4
347-360
EN
Genetic control of gonadal development proceeds through either the male or female molecular pathways, driving bipotential gonadal anlage differentiation into a testis or ovary. Antagonistic interactions between the 2 pathways determine the gonadal sex. Essentially sex determination is the enhancement of one of the 2 pathways according to genetic sex. Initially, Sry with other factors upregulates Sox9 expression in XY individuals. Afterwards the expression of Sox9 is maintained by a positive feedback loop with Fgf9 and prostaglandin D2 as well as by autoregulative ability of Sox9. If these factors reach high concentrations, then Sox9 and/or Fgf9 may inhibit the female pathway. Surprisingly, splicing, nuclear transport, and extramatrix proteins may be involved in sex determination. The male sex determination pathway switches on the expression of genes driving Sertoli cell differentiation. Sertoli cells orchestrate testicular differentiation. In the absence of Sry, the predomination of the female pathway results in the realization of a robust genetic program that drives ovarian differentiation.
3

The possible role of cell cycle stage in mammalian cloning

80%
Modlinski J. A., Grabarek J., Plusa B., Karasiewicz J.
Journal of Applied Genetics
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2001
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vol. 42
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issue 2
153-176
EN
Progress in mammalian cloning started from cloning embryos (of mice, rats, rabbits, sheep, goats, pigs, cattle and rhesus monkeys) and culminated in obtaining clones of sheep, cattle, pigs and mice from adult somatic cells. Knowing the relationship between the cell cycles of the recipient and the donor of cell nucleus in embryonic cloning by nuclear transfer one can adjust the phases of the cell cycle properly. Metaphase II recipients accept G1 (in most species) or G2 donors (in the mouse). Interphase recipients can harbour nuclei in all stages of cell cycle. Relatively little is known about somatic cloning. Two attitudes are applied: either the donor is in the G0 phase or the recipient is in a prolonged MII phase.
4

The role of iron regulatory proteins in the control of iron metabolism in mammals

80%
Stys A., Starzynski R. R., Lipinski P.
Biotechnologia
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2011
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issue 1
66-75
EN
The iron regulatory proteins (IRP1 and IRP2) are two cytoplasmic RNA-binding proteins involved in the mechanisms that control iron metabolism in mammalian cells. They modulate the expression of iron-related proteins at a post-transcriptional level by binding to specific iron regulatory elements (IREs) on their mRNAs. IRP-IRE interaction can block protein synthesis or stabilize the mRNA. At low intracellular iron concentration, IRPs bind to the IRE of ferritin or ferroportin mRNAs and block their translation. Direct interactions between IRPs and several IRE motifs stabilize transferrin receptor mRNA. The converse regulation of ferritin and TfR synthesis, being a consequence of the lack of binding of IRPs to IRE, occurs in cells with high iron level. Thus, IRP-mediated regulation rapidly restores the physiological level of iron during its deficiency as well as excess. The role of IRPs in maintaining the intracelluar iron balance has been relatively well characterized in numerous types of mammalian cells. However, the importance of IRPs in the regulation of systemic iron metabolism in mammals, particularly, in signaling between the cells which play major roles in body iron metabolism, such as duodenal enterocytes, reticuloendothelial macrophages, hepatocytes, and bone marrow precursors of red blood cells, is only beginning to be investigated. Several studies have shown that IRP2 is a predominant regulator of iron homeostasis in mice housed under standard conditions, thus limiting the impact of IRP1 on this metabolic pathway. Although IRP1-deficient mice do not display a strong pathological phenotype, a deletion of both IRPs is embryonic lethal. In addition, in vitro and in vivo studies have reported that nitric oxide (NO) and hydrogen peroxide (H2O2), which are produced during inflammation, are potent IRP1 regulators that mediate the disassembly of Fe-S cluster of IRP1. There is also an increasing evidence that NO and superoxide anion (O2 @!) may induce a strong down-regulation of IRP1 at the protein level and thus have an impact on the binding of IRP1 to IREs. All these data suggest a predominant role of IRP1 in the regulation of iron homeostasis under specific physiopathological conditions.
5

Bcl-2 proteins in ovarian apoptosis

80%
Opiela J., Katska-Ksiazkiewicz L.
Biotechnologia
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2006
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issue 1
90-96
EN
Members of the Bcl-2 family are considered principal players in the cascade of events that activate or inhibit apoptosis. Recent evidence strongly supports fundamental role of Bcl-2 and related proteins in regulating ovarian cell death. This article will provide an overview of the current knowledge regarding Bcl-2 proteins in programmed cell death in development of the ovary and the postnatal ovarian cycles.
6

Vanilloid receptors - comparison of structure and functions in Mammals and Invertebrates

70%
Olszewska J.
Folia Biologica
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2010
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vol. 58
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issue 1-2
1-7
EN
The vanilliod receptor subfamily belongs to the transient receptor potential family of ion channels. Vanilloid receptors are calcium-permeable channels highly expressed in many different cells, both excitable and nonexcitable, in invertebrates (nematodes, insects) and vertebrates (mammals). These receptors are sensitive to a wide range of stimuli (chemical, mechanical, osmotic and temperature) that often activate the same channel. This review focuses on recent information, both bibliographic and experimental evidence of the author, concerning the structure and functions of vanilloid receptors, especially those connected with thermoregulation.
7

The production and use of mammalian chimeric embryos

70%
Piliszek A.
Biotechnologia
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2004
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issue 1
142-155
EN
Chimera is a composite organism, consisting of cells derived from more than one embryo. The first experimental chimera was produced in 1961 and until today, chimeric animals have been widely used in mammalian experimental embryology. Numerous aggregation and injection techniques have been used to produce chimeras. Although most experimental chimeras were made of murine embryos, chimeric animals have been also produced in such species as: rat, hamster, deer mouse, rabbit, pig, sheep and in cattle. Some successful attempts to produce interspecific chimeras have been also made. Pigmentation is still widely used as a marker of chimerism, but new transgenic markers are now available. New methods emplying chimeric technique, like blastocyst complementation assay and lethal phenotypes rescue, provide new insights into developmental genetics. Nowadays, chimeric embryos are also likely to play a major role in the production of transgenic animals with the help of chimeric cloning technique.
8

Metabolism of nicotine - mechanism and clinic aspects of toxic effects of nicotine

61%
Szajerka G., Kwiatkowska G.
Postępy Higieny i Medycyny Doświadczalnej
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1997
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vol. 51
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issue 1
23-38
EN
Nicotine is a major constituent of tobacco and exerts a number of physiological effects. Metabolism of nicotine in animal and human tissues is reviewed. Clinical considerations regarding the problems of toxic effects of nicotine in human and molecular basis of carcinogen mechanism of nicotine derivatives are discussed.
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