Altered glomerular permeability induced by F(ab′)2 and Fab′ antibodies to rat renal tubular epithelial antigen

Altered glomerular permeability induced by F(ab′)2 and Fab′ antibodies to rat renal tubular epithelial antigen. Rats injected with F(ab′)2 and Fab′ antibody fragments directed against an antigen in the rat proximal tubular epithelial brushborder (Fx1A) developed immediate proteinuria [F(ab′)2 43.2 ± 6.7, N = 6; Fab′ 9.5 ± 2.8, N = 5; normal 1.6 ± 0.9 mg/day, N = 20]), that subsided after 3 to 5 days' duration. This reaction is in contrast to one exhibited by rats given intact IgG anti-Fx1A; the rats that did not develop immediate proteinuria (2.2 ± 0.3 mg/day, N = 5), and the glomerular binding of125I-antibody fragments was significantly less than that of intact IgG [F(ab′)2 0.11 ± 0.01; Fab′ 0.03 ± 0.01; IgG 0.17 ± 0.01% administered equimolar dose] at 24 hr. No proteinuria resulted from equimolar doses of nonantibody F(ab′)2 and Fab′. Less than 8% of the proteinuria induced by antibody fragments represented injected material, and 30 to 38% was albumin. Immunofluorescence revealed faint and diffuse glomerular capillary wall deposits of F(ab′)2 and Fab′ and tubular brushborder staining. Subepithelial, electrondense deposits and focal, podocyte effacement were seen by electron microscopy in rats given the F(ab′)2 antibody. Light microscopy and colloidal iron-staining were normal. In our study antibody fragments appear to interact directly with components of the outer, glomerular capillary wall to alter permeability in the absence of recognized mediators such as complement and inflammatory cells.Modification de la perméabilité glomérulaire déterminée par anticorps chez des rats anti-épithélium tubulaire F(ab′)2 et Fab′. Les rats été injectés avec des fragments F(ab′)2 et Fab′ contra anticorps de la bordure en brosse de l'épithélium tubulaire proximal de rat (Fx1A) ont immédiatement une protéinurie [F(ab′)2 43,2 ± 6,7, N = 6; Fab′ 9,5 ± 2,8, N = 5; normaux 1,6 ± 0,9 mg/d, N = 20] qui persiste pendant 3 à 5 jours. Cela réaction est différent de ce qui est observé chez les rats qui reçoivent l'IgG anti-Fx1A intacte; les rats quelles n'ont pas de protéinurie immédiate (2,2 ± 0,3 mg/d, N = 5) quoiqu'à 24 heures la liaison glomérulaire de fragments125I de l'anticorps soit significativement plus faible que celle de I'IgG intacte [F(ab′)2 0,11 ± 0,01; Fab′ 0,03 ± 0,01; IgG 0,17 ± 0,01 en % de la dose équimolaire administrée]. Aucune protéinurie n'a été la conséquence de l'administration équimolaire de F(ab′)2 et Fab′ non-anticorps. Moins de 8% de la protéinurie déterminée par les fragments d'anticorps représentent du matériel injecté et 30 à 38% est de l'albumine. L'immunofluorescence a montré des dépôts faibles et diffus, sur les parois des capillaires giomérulaires, de F(ab′)2 et Fab′ et le marquage de la bordure en brosse. En électronique, des dépôts denses sous-épithéliaux et l'effacement local des podocytes ont été observés chez les rats qui avaient reçu l'anticorps F(ab′)2. La microscopie optique et la coloration par le fer colloïdal n'ont pas montré d'anomalies. Dans notre étude les fragments d'anticorps semblent avoir paroi externe du capillaire glomérulaire et avoir modifié la perméabilité en l'absence de médiateurs connus tels le complément ou les cellules inflammatoires

The Effects of Aphid Traits on Parasitoid Host Use and Specialist Advantage

Specialization is a central concept in ecology and one of the fundamental properties of parasitoids. Highly specialized parasitoids tend to be more efficient in host-use compared to generalized parasitoids, presumably owing to the trade-off between host range and hostuse efficiency. However, it remains unknown how parasitoid host specificity and host-use depends on host traits related to susceptibility to parasitoid attack. To address this question, we used data from a 13-year survey of interactions among 142 aphid and 75 parasitoid species in nine European countries. We found that only aphid traits related to local resource characteristics seem to influence the trade-off between host-range and efficiency: more specialized parasitoids had an apparent advantage (higher abundance on shared hosts) on aphids with sparse colonies, ant-attendance and without concealment, and this was more evident when host relatedness was included in calculation of parasitoid specificity. More traits influenced average assemblage specialization, which was highest in aphids that are monophagous, monoecious, large, highly mobile (easily drop from a plant), without myrmecophily, habitat specialists, inhabit non-agricultural habitats and have sparse colonies. Differences in aphid wax production did not influence parasitoid host specificity and host-use. Our study is the first step in identifying host traits important for aphid parasitoid host specificity and host-use and improves our understanding of bottom-up effects of aphid traits on aphid-parasitoid food web structure

Trajectoire et potentiel de l'agroécologie, pour une transition vers des systèmes alimentaires durables, papier de positionnement du GIRAF

Downloadable from www.agroecologie.be.info:eu-repo/semantics/publishe