Highly reactive oxygen species: detection, formation, and possible functions

The so-called reactive oxygen species (ROS) are defined as oxygen-containing species that are more reactive than O(2) itself, which include hydrogen peroxide and superoxide. Although these are quite stable, they may be converted in the presence of transition metal ions, such as Fe(II), to the highly reactive oxygen species (hROS). hROS may exist as free hydroxyl radicals (HO·), as bound ("crypto") radicals or as Fe(IV)-oxo (ferryl) species and the somewhat less reactive, non-radical species, singlet oxygen. This review outlines the processes by which hROS may be formed, their damaging potential, and the evidence that they might have signaling functions. Since our understanding of the formation and actions of hROS depends on reliable procedures for their detection, particular attention is given to procedures for hROS detection and quantitation and their applicability to in vivo studies.     

Chromatin structure contribution to the synaptonemal complex formation

Meiosis is a key cellular and molecular process for sexual reproduction contributing to the genetic variability of organisms. This process takes place after DNA replication and consists in a double cellular division, giving rise to four haploid daughter cells or gametes. Meiotic recombination between homologous chromosomes, in the meiotic prophase I, is mediated by a tripartite structure named Synaptonemal Complex (SC). The SC is a peptidic scaffold in which the chromatin of homologous chromosomes is organized during the pachytene stage, holding chromosomes together until the meiotic recombination and genetic exchange have taken place. The role of chromatin structure in formation of the SC and the meiotic recombination at meiotic prophase I remain largely unknown. In this review we address the epigenome contribution to the SC formation at meiotic prophase I, with particular attention on the chromatin structure modifications occurring during the sub-stages of meiotic prophase I. Received 18 September 2008; received after revision 10 October 2008; accepted 24 October 2008     

Influence of nystatine, a polyene antibiotic, on the formation of complex-bound sterols and the formation of conidia by Coprinus cinereus (author's transl)

In contrary to the wild strain, a monocaryotic mutant of Coprinus cinereus (basidiomycete) does not contain hydrosoluble, complex-bound sterols. Under nystatine-treatment, however, the mutant is induced to produce this kind of stereols in abundance. Furthermore, nystatine highly increases sporulation of the mutant and decreases sporulation of the wild strain.     

Biochemistry,evolution and physiological function of the Rnf complex,a novel ion-motive electron transport complex in prokaryotes

Microbes have a fascinating repertoire of bioenergetic enzymes and a huge variety of electron transport chains to cope with very different environmental conditions, such as different oxygen concentrations, different electron acceptors, pH and salinity. However, all these electron transport chains cover the redox span from NADH + H⁺ as the most negative donor to oxygen/H₂O as the most positive acceptor or increments thereof. The redox range more negative than −320 mV has been largely ignored. Here, we have summarized the recent data that unraveled a novel ion-motive electron transport chain, the Rnf complex, that energetically couples the cellular ferredoxin to the pyridine nucleotide pool. The energetics of the complex and its biochemistry, as well as its evolution and cellular function in different microbes, is discussed.     

In vitro formation of a MSH-releasing agent by hypothalamic extracts

Résumé La fraction mitochondriale d'extraits du noyau paraventriculaire du rat incubée avec de l'oxytocine produit la formation d'un agent capable de libérer MSH de l'hypophyse. Les résultats suggèrent que la formation de l'agent qui libère la MSH hypophysaire résulte de la dégradation enzymatique des hormones neurohypophysaires.

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This work was supported by the Consejo Nacional de Investigaciones Cientificas y Técnicas of Argentina.     

A possible preferential inhibition of chemotaxis of polymorphonuclear neutrophils by a chemical modification

Summary The modification of neutrophils with amino group blocking reagents of different chemical specificities showed that dansyl chloride caused inhibition of chemotaxis without suppression of random movement. Dansylated neutrophils, like control cells, ingested bacteria. Neither the stimulated cyanide-insensitive respiration, nor lactate production during phagocytosis, was affected significantly by dansylation as compared with the inhibition of directed movement.     

A possible preferential inhibition of chemotaxis of polymorphonuclear neutrophils by a chemical modification.

The modification of neutrophils with amino group blocking reagents of different chemical specificities showed that dansyl chloride caused inhibition of chemotaxis without suppression of random movement. Dansylated neutrophils, like control cells, ingested bacteria. Neither the stimulated cyanide-insensitive respiration, nor lactate production during phagocytosis, was affected significantly by dansylation as compared with the inhibition of directed movement.     

Induction of the formation of a coli-bacterio-phage and colicin by hydroperoxide

Zusammenfassung Die Arbeit gibt die Resultate der Induktion der Lysogenie und der Colicinogenie im selben StammeE. coli (L II-18) mit Wasserstoffperoxid an. Der Phagentiter wurde 35mal, der Colicintiter 7mal erhöht. Die optimale Konzentration des H₂O₂ für Phagenbildung warM/500, die für ColicinbildungM/2000. Im Vergleich mit der Induktion desselben Stammes mit UV-Licht ist die Wirkung des H₂O₂ verhältnismässig schwach.     

Retropulsion,GABA, and possible hallucinatory behavior in mice

Zusammenfassung Amino-oxyacetsäure, eine Substanz welche das endogene Gehirnniveau anGABA erhöht, führte in 16 Tage alten Mäusen zu LSD-ähnlichen Verhaltensweisen wie Hypothermie: zu Krämpfen und Rückwärtslaufen.     

Inhibition of large distal tooth formation in male medaka,Oryzias latipes,by estradiol

Zusammenfassung Junge Männchen vonOryzias latipes haben im Ober- und Unterkiefer grosse Eckzähne, die den weiblichen Tieren fehlen. Verfütterung von 50µg Östradiol/g Normalfutter hemmt die Bildung dieser Zähne völlig, 10µg nur unvollständig.     

Metabolism of a pharmacologically active pyrrolidine derivative (prolintane) by lactam formation

Zusammenfassung Prolintan, N-1-(-Benzylbutyl)-Pyrrolidin, wurde in Kaninchen durch ein Mikrosomensystem der Leber in das entsprechende Laktam, N-1-(-Benzylbutyl)-Pyrrolidin-2-on, umgebaut. Das gleiche Stoffwechselprodukt fand sich auch im Gewebe von Ratten, denen das Medikament gegeben wurde; allenfalls Spuren davon wurden im Urin der Ratten ausgeschieden.

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We thank Dr.D. C. Remy for a sample of syntheticdl-1-(-propylphenethyl)-pyrrolidin-2-one.     

‘Atrichosis’, a new hairless gene with cyst formation in rats

Summary A new hairless gene in the Donryu strain of the rat has been designated atrichosis (at). Histological sections demonstrated that atrichotic skin was quite similar to that found in human skin with multiple follicular cysts, which is one type of skin tumor in humans.     

A possible case of centric fission in a primate

Resumen Los estudios cromosómicos llevados a cabo en un macho dePresbytis entellus sugieren que los mecanicos de fisión céntrica han intervenido en la evolución cromosómica de los mamíferos, que la fisión puede producir cromosomas telocéntricos estables, y que los mecanismos de fusión pueden acompañarse de una duplicación centromérica.     

Increased release of tumour cells by collagenase at acid pH: a possible mechanism for metastasis.

The ability of collagenase to disaggregate a solid metastasizing lymphosarcoma has been shown to considerably increase with reducing environmental pH. It is suggested that this effect may be operating in vivo to release cells from a primary tumour.     

Extraadrenal adrenaline formation by two separate enzymes

Adrenaline (A) is synthesized in the adrenal medullae by the enzyme phenylethanolamine-N-methyltransferase (PNMT). After surgical removal of the adrenal medullae tissue A levels ranged from 22% of control in the heart to 125% of control in the liver. Use of a novel assay to measure tissue A formation revealed that many tissues can synthesize A using PNMT and another enzyme that N-methylates both noradrenaline and dopamine. These enzymes are non-neuronal, inducible and synthesize a major fraction of tissue and urine A.     

Regulation of neural circuit formation by protocadherins

The protocadherins (Pcdhs), which make up the most diverse group within the cadherin superfamily, were first discovered in the early 1990s. Data implicating the Pcdhs, including ~60 proteins encoded by the tandem Pcdha, Pcdhb, and Pcdhg gene clusters and another ~10 non-clustered Pcdhs, in the regulation of neural development have continually accumulated, with a significant expansion of the field over the past decade. Here, we review the many roles played by clustered and non-clustered Pcdhs in multiple steps important for the formation and function of neural circuits, including dendrite arborization, axon outgrowth and targeting, synaptogenesis, and synapse elimination. We further discuss studies implicating mutation or epigenetic dysregulation of Pcdh genes in a variety of human neurodevelopmental and neurological disorders. With recent structural modeling of Pcdh proteins, the prospects for uncovering molecular mechanisms of Pcdh extracellular and intracellular interactions, and their role in normal and disrupted neural circuit formation, are bright.