RESUMEN

Cytokeratins are structural proteins of the intermediate filament family and are mainly expressed in epithelial cells. In several vertebrates it has been shown that keratin 8 is expressed in simple epithelial tissues, some non-epithelial tissue and in hyper-proliferative tissues during development and tumor transformation. We previously cloned and characterised the zebrafish (Danio rerio) homologous cytokeratin 8 cDNA (zfk8) which was described as an epidermal marker during zebrafish development. It has been found that the zfk8 gene is normally expressed in simple epithelia in embryonic and mature zebrafish. Using whole-mount in situ hybridisation, we show in this report that expression of zfk8 is tightly linked to the regeneration of caudal fin and exclusively observed in epidermal cells. It is strongly expressed in the epidermis overlaying the inter-rays zone of regenerating caudal fin. Our results indicate that in zebrafish, cytokeratin 8 is a suitable epidermal marker during regeneration.

Asunto(s)

Epidermis/fisiología , Regulación del Desarrollo de la Expresión Génica , Queratinas/metabolismo , Animales , Embrión no Mamífero , Epidermis/embriología , Hibridación in Situ , Queratinas/genética , ARN Mensajero/análisis , Regeneración , Pez Cebra

RESUMEN

We report the characterization of a zebrafish DnaJ-like protein, homologue to the human Hsp40 protein hdj1, that we named zf-Hsp40. We have studied its expression during fin regeneration and we show that zf-Hsp40 mRNA level is drastically increased in all ray segments beneath the regenerated part, or blastema, in response to caudal fin amputation. In order to investigate whether zf-Hsp40 is part of a stress response system after injury, we studied the expression of the zebrafish Hsc70 transcript. Our results show a correlation between the expression of the two transcripts.

Asunto(s)

Proteínas Portadoras/biosíntesis , Proteínas Portadoras/genética , Proteínas HSP70 de Choque Térmico , Proteínas de Choque Térmico/biosíntesis , Proteínas de Choque Térmico/genética , Pez Cebra/embriología , Pez Cebra/fisiología , Secuencia de Aminoácidos , Animales , ADN Complementario/metabolismo , Biblioteca de Genes , Proteínas del Choque Térmico HSC70 , Proteínas del Choque Térmico HSP40 , Hibridación in Situ , Datos de Secuencia Molecular , ARN Mensajero/metabolismo , Regeneración , Homología de Secuencia de Aminoácido , Proteínas de Pez Cebra

RESUMEN

N-arginine (R) dibasic (NRD) convertase (nardilysin; EC 3.4.24.61), a metalloendopeptidase of the M16 family, specifically cleaves peptide substrates at the N-terminus of arginines in dibasic motifs in vitro. In rat testis, the enzyme localizes within the cytoplasm of spermatids and associates with microtubules of the manchette and axoneme. NRD1 and NRD2 convertases, two NRD convertase isoforms, differ by the absence (isoform 1) or presence (isoform 2) of a 68-amino acid insertion close to the active site. In this study, we overexpressed both isoforms, either by vaccinia virus infection of BSC40 cells or transfection of COS-7 cells. The partially purified enzymes exhibit very similar biochemical and enzymic properties. Microsequencing revealed that NRD convertase is N-terminally processed. Results of immunocytofluorescence, immunoelectron microscopy and subcellular fractionation studies argue in favour of a primary cytosolic localization of both peptidases. Although the putative signal peptide did not direct NRD convertase into microsomes in an in vitro translation assay, biotinylation experiments clearly showed the presence of both isoforms at the cell surface. In conclusion, although most known processing events at pairs of basic residues are achieved by proprotein convertases within the secretory pathway, NRD convertase may fulfil a similar function in the cytoplasm and/or at the cell surface.

Asunto(s)

Isoenzimas/metabolismo , Metaloendopeptidasas/metabolismo , Animales , Biotinilación , Células COS , Citoplasma/enzimología , Concentración de Iones de Hidrógeno , Isoenzimas/genética , Masculino , Proteínas de la Membrana/metabolismo , Metaloendopeptidasas/genética , Biosíntesis de Proteínas , ARN Mensajero/metabolismo , Ratas , Ratas Wistar , Proteínas Recombinantes/metabolismo , Fracciones Subcelulares

RESUMEN

Rat testis NRD convertase (EC 3.4.24.61) is a Zn2+-dependent endopeptidase that cleaves, in vitro, peptide substrates at the N-terminus of Arg residues in dibasic sites. This putative processing enzyme of the insulinase family of metallopeptidases exhibits a significant degree of similarity to insulinase and two yeast processing enzymes, Axl1 and Ste23. We report the cloning of two human testis cDNA species encoding isoforms of NRD convertase, hNRD1 and hNRD2. Whereas the hNRD1 transcript (3.7 kb) is equivalent to the previously characterized rat cDNA (rNRD1), hNRD2 and rNRD2 are 3.9 kb novel forms containing a nucleotide insertion encoding a 68-residue segment. This motif, which is inserted N-terminal of the Zn2+-binding site, HXXEH, is contained within the most conserved region among the insulinase family members. Analysis of the deduced primary sequences revealed 92% identity between rat and human orthologues. The human gene encoding NRD convertase was localized to chromosome 1p32.1-p32.2. Whereas NRD convertase is mostly expressed in testis and in 24 cell lines, low mRNA levels were detected in most of the 27 other tissues tested.

Asunto(s)

Insulisina/genética , Isoenzimas/genética , Metaloendopeptidasas/genética , ARN Mensajero/biosíntesis , Testículo/enzimología , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Línea Celular , Chlorocebus aethiops , Mapeo Cromosómico , Cromosomas Humanos Par 1/genética , Clonación Molecular , ADN Complementario/genética , Humanos , Insulisina/biosíntesis , Isoenzimas/biosíntesis , Masculino , Metaloendopeptidasas/biosíntesis , Ratones , Datos de Secuencia Molecular , Especificidad de Órganos , Reacción en Cadena de la Polimerasa , Ratas , Homología de Secuencia de Aminoácido , Especificidad de la Especie , Porcinos , Testículo/metabolismo

RESUMEN

The cuticular hydrocarbons ofFormica selysi (Formicinae) andMonica rubida (Myrmicinae) reared in single species and in mixed species colonies were determined using gas chromatography (GC) and GC-mass spectrometry. In colonies containing both species, each species modified its species-specific recognition odor. This odor is composed, at least partly, of cuticular hydrocarbons. The cuticular hydrocarbons ofM. rubida consist only of saturated alkanes (n-alkanes and branched alkanes). InF. selysi the mixture also contains unsaturated compounds (monoenes and dienes). In hetero-specific colonies, a new chemical signature developed. This signature resulted from qualitative and quantitative changes in the spectrum of hydrocarbons produced by each species and permitted the two species to inhabit the same nest without displaying interspecific aggression. The readjustment seemed to be more an active synthesis or an active transfer than simply a passive transfer from one species to the other. This may imply that the ants synthesized some components of the hydrocarbon signature of the other species. These synthesizing processes may be activated under particular social environmental conditions.

RESUMEN

Attractiveness in adult females of Calliphora vomitoria is correlated with ovarian development and there is a marked increase during the previtellogenic and vitellogenic periods. The development of attractiveness may result from the combined actions of ecdysteroids and juvenile hormone. A rise in total hydrocarbons parallels the first increase in levels of these hormones during the previtellogenic stage. Cuticular hydrocarbons subsequently fall, along with the disappearance of hemolymphatic ecdysteroids, and then rise again during the vitellogenic phase of JH production. Increasing and decreasing of some cuticular hydrocarbons, some hydrocarbons implicated in the attractiveness, are correlated with variation of the titer of these hormones, especially JH III.

Asunto(s)

Dípteros/fisiología , Hidrocarburos/metabolismo , Hormonas de Insectos/metabolismo , Animales , Corpora Allata/metabolismo , Ecdisteroides , Ecdisterona/metabolismo , Femenino , Hemolinfa/metabolismo , Hormonas de Invertebrados/metabolismo , Hormonas Juveniles/metabolismo , Ovario/crecimiento & desarrollo , Periodicidad , Reproducción/fisiología , Sesquiterpenos/metabolismo

RESUMEN

Colonies ofReticulitermes flavipes andR. santonensis were collected from the southeastern United States (Georgia) and the southwest of France (Charente-maritime). Defensive compounds and cuticular hydrocarbons were identified by gas chromatography-mass spectrometry and quantified by gas chromatography using an internal standard for each caste and all colonies. These analyses show that although the cuticular hydrocarbons ofR. santonensis in Europe andR. flavipes in Georgia are identical, their relative proportions are different. However, the defensive compounds synthesized by their soldiers are different. A strong chemical polymorphism between sympatric colonies ofR. flavipes in the SW United States was detected in terms of both the hydrocarbons of the workers and soldiers and in the defensive secretions of the soldiers. The six defensive secretion phenotypes are based on the presence or absence of terpenes whereas the cuticular hydrocarbon phenotypes are based on significant differences in the proportions of the various components. A multivariate analysis (analysis of principal components) clearly permitted discrimination of four phenotypes (three inR. flavipes and one inR. santonensis) without intermediates. The hydrocarbons responsible for these variations were identified, and it was shown that the variations are neither seasonal nor geographic. The phenotypes of the cuticular hydrocarbons (workers and soldiers) and defensive compounds are linked in each colony, forming in three groups inR. flavipes Georgia, one subdivided into four subgroups according to the defensive secretion phenotypes. The role of these polymorphisms is discussed and ethological tests indicate that the chemical polymorphism do not determine aggressive behavior. The taxonomic significance of these results is considered and two hypothesis are formulated: (1) We only detected a strong genetic polymorphism in one unique species, and we believe thatR. santonensis was introduced into Europe in the last century from oneR. flavipes colony. (2) Chemical variability characterizes the sibling species that can be grouped into the same subspeciesR. flavipes. Unknown mechanisms of reproductive isolation separate them.