RESUMEN
A novel method using derivatized agarose beads for investigating the types of molecules, when isolated from all others, that can form stable adhesive bonds, was recently described by Roque et al. (1996). The findings from this study were extended to living sea urchin cell systems. Both the bead results and the experiments with sea urchin cells suggested that phosphorylated amino acids can form stable adhesive bonds with positively charged peptides (Roque et al., 1996). As these experiments only examined phosphorylated amino acids, the validity of the hypotheses developed in the earlier study was dependent on extending the experiments to additional phosphorylated molecules. In this study, effects of D-mannose, D-mannose-1-phosphate, D-fructose, D-fructose-1-phosphate, maltose and maltose-1-phosphate on embryo cell reaggregation and sperm-egg interaction using untreated, jelly coat-free and vitelline layer disrupted Strongylocentrotus purpuratus sea urchin eggs were examined. The phosphorylated sugars (50 mM), and not their non-phosphorylated counterparts, strongly inhibited fertilization of the 3 types of eggs. ATP, at concentrations as low as 0.8 mM also completely inhibited fertilization. The phosphorylated sugars had little or no effect on reaggregating sea urchin blastula cells. A likely explanation of these results is that sperm-egg interaction in the sea urchin involves positively and negatively charged receptors; the positively charged receptors are blocked by exogenously added phosphorylated molecules. These and earlier studies indicate that by extending results from bead modeling studies to living systems, interesting information can be obtained regarding bonding mechanisms that may modulate adhesive interactions.
Asunto(s)
Comunicación Celular/fisiología , Interacciones Espermatozoide-Óvulo/fisiología , Adenosina Trifosfato/farmacología , Animales , Blastocisto/citología , Blastocisto/efectos de los fármacos , Blastocisto/fisiología , Adhesión Celular/efectos de los fármacos , Adhesión Celular/fisiología , Comunicación Celular/efectos de los fármacos , Femenino , Fertilización/fisiología , Fructosa/farmacología , Fructosafosfatos/farmacología , Masculino , Maltosa/farmacología , Manosa/farmacología , Manosafosfatos/farmacología , Microesferas , Erizos de Mar , Interacciones Espermatozoide-Óvulo/efectos de los fármacos , Fosfatos de Azúcar/farmacologíaRESUMEN
Agarose beads derivatized with amino acids, peptides, carbohydrates and lectins were used to systematically determine what types of molecules, isolated from all others, can make adhesive bonds strong enough to hold cell-like beads together. The results indicated that strong adhesion occurred when at least one of the two members of certain bead pairs was derivatized with molecules that were dimers or trimers but not monomers. Also, beads derivatized with phosphorylated amino acids, but not their non-phosphorylated counterparts, adhered to beads derivatized with positively charged peptides. Adhesion was sensitive to ionic strength and pH of the medium. It was proposed that adhesion occurred between the phosphate groups of the phosphoamino acids and amino and guanidinium groups of the peptides. Cooperative bonding can explain the stability of the adhesion observed in this system. Information gained from the bead modeling work was used to design experiments to examine the role of phosphorylated molecules in modulating adhesion in sea urchin systems. Phosphoamino acids inhibited sperm-egg interaction, but not reaggregation of blastula cells. Inhibitors of alkaline phosphatase, however, did inhibit reaggregation. The results suggest that cell surface phosphorylated molecules may modulate cellular adhesiveness, in some systems promoting, while in others inhibiting adhesion.
Asunto(s)
Aminoácidos/metabolismo , Adhesión Celular/fisiología , Lectinas/metabolismo , Péptidos/metabolismo , Sefarosa/química , Aminoácidos/farmacología , Animales , Sitios de Unión , Fertilización/efectos de los fármacos , Concentración de Iones de Hidrógeno , Modelos Biológicos , Óvulo/efectos de los fármacos , Óvulo/fisiología , Fosforilación , Erizos de Mar/fisiología , Membrana Vitelina/efectos de los fármacosRESUMEN
A total of 50 Actinobacillus suis isolates were studied for their biochemical and antigenic characteristics. Of them, 40 isolates originated from different tissues of diseased pigs, and the other ten isolates were from horses with respiratory problems. There was no major biochemical difference among equine and porcine A. suis isolates. Results of tube agglutination tests showed that porcines isolates were antigenically homogeneous while equine isolates were heterogeneous.
Asunto(s)
Infecciones por Actinobacillus/veterinaria , Actinobacillus/clasificación , Enfermedades de los Caballos , Infecciones del Sistema Respiratorio/veterinaria , Enfermedades de los Porcinos , Actinobacillus/aislamiento & purificación , Infecciones por Actinobacillus/microbiología , Pruebas de Aglutinación , Animales , Antígenos Bacterianos/análisis , Caballos , Infecciones del Sistema Respiratorio/microbiología , PorcinosAsunto(s)
Artritis Infecciosa/veterinaria , Enfermedades de los Caballos/microbiología , Infecciones por Pasteurella/veterinaria , Pasteurella/aislamiento & purificación , Animales , Artritis Infecciosa/microbiología , Femenino , Miembro Posterior/microbiología , Caballos , Infecciones por Pasteurella/microbiología , QuebecRESUMEN
A serosurvey of Rift Valley Fever virus infection conducted among 557 sheep and 643 goats from Niger in 1986 points out that 2.8% of the 1,200 animals tested had RVF virus reacting antibodies. The circulation of the virus is demonstrated, as well for another phlebovirus related to RVF virus, the strain Arumowot.