Isolation and characterisation of plant defensins from seeds of Asteraceae, Fabaceae, Hippocastanaceae and Saxifragaceae

AbstractFrom seeds of Aesculus hippocastanum, Clitoria ternatea, Dahlia merckii and Heuchera sanguinea five antifungal proteins were isolated and shown to be homologous to plant defensins previously characterised from radish seeds and γ-thionins from Poaceae seeds. Based on the spectrum of their antimicriobial activity and the morphological distortions they induce on fungi the peptides can be divided into two classes. The peptides did not inhibit any of three different α-amylases

Sensibilité au stress oxydatif de patients présentant une maladie d’Alzheimer: résultats préliminaires

info:eu-repo/semantics/publishe

Isolation of ALA(1)-proctolin, the first natural analog of proctolin, from the brain of the Colorado potato beetle

Methanolic head and brain extracts of the Colorado potato beetle contain several myotropins, active in the Locusta oviduct motility assay. Reversed phase high performance liquid chromatography (RP HPLC) gave evidence for the presence of three myotropic factors, with retention times close to that of proctolin. Both strongly stimulated the frequency, amplitude and tonus of the myogenic oviduct contractions. Gas phase sequencing and FAB-MS revealed that, besides proctolin (Arg-Tyr-Leu-Pro-Thr), two natural proctolin analogues were present. The first one is Ala-Tyr-Leu-Pro-Thr and is designed as Ala(1)-proctolin. The threshold concentration for biological activity of Ala(1)-proctolin was 10(-7) M, compared to 10(-10) M for proctolin itself. Ala(1)-proctolin is the first identified biological analogue of proctolin. The full nature of the first amino acid of a third proctolin-analogue (x-Tyr-Leu-Pro-Thr) is probably a modified amino acid of which the identity could as yet not be revealed. Our results suggest the existence of a family of proctolin-like peptides.status: publishe

Normocalcemia is maintained in mice under conditions of calcium malabsorption by vitamin D–induced inhibition of bone mineralization

Serum calcium levels are tightly controlled by an integrated hormone-controlled system that involves active vitamin D [1,25(OH)2D], which can elicit calcium mobilization from bone when intestinal calcium absorption is decreased. The skeletal adaptations, however, are still poorly characterized. To gain insight into these issues, we analyzed the consequences of specific vitamin D receptor (Vdr) inactivation in the intestine and in mature osteoblasts on calcium and bone homeostasis. We report here that decreased intestinal calcium absorption in intestine-specific Vdr knockout mice resulted in severely reduced skeletal calcium levels so as to ensure normal levels of calcium in the serum. Furthermore, increased 1,25(OH)2D levels not only stimulated bone turnover, leading to osteopenia, but also suppressed bone matrix mineralization. This resulted in extensive hyperosteoidosis, also surrounding the osteocytes, and hypomineralization of the entire bone cortex, which may have contributed to the increase in bone fractures. Mechanistically, osteoblastic VDR signaling suppressed calcium incorporation in bone by directly stimulating the transcription of genes encoding mineralization inhibitors. Ablation of skeletal Vdr signaling precluded this calcium transfer from bone to serum, leading to better preservation of bone mass and mineralization. These findings indicate that in mice, maintaining normocalcemia has priority over skeletal integrity, and that to minimize skeletal calcium storage, 1,25(OH)2D not only increases calcium release from bone, but also inhibits calcium incorporation in bone