Ribitol dehydrogenase of Klebsiella aerogenes. Sequence and properties of wild-type and mutant strains.

Evidence is presented for the sequence of 249 amino acids in ribitol dehydrogenase-A from Klebsiella aerogenes. Continuous culture on xylitol yields strains that superproduce 'wild-type' enzyme but mutations appear to have arisen in this process. Other strains selected by such continuous culture produce enzymes with increased specific activity for xylitol but without loss of ribitol activity. One such enzyme, ribitol dehydrogenase-D, has Pro-196 for Gly-196. Another, ribitol dehydrogenase-B, has a different mutation.     

Zymomonas mobilis ATCC 10988 plasmid pZMO3 expresses mobilisation functions in Escherichia coli JM83 and RR1

Zymomonas mobilis plasmid pZMO3, equivalent to pZM2 the complete nucleotide sequence of which has been published (Misawa and Nakamura, 1989), expressed mobilisation functions in Escherichia coli JM83 and RR1 when fused to the HindIII site of pUC19. Experimental evidence based on filter mating and DNA sequence analysis supports that an ORF of pZMO3 coding for a 66 kd protein should be responsible for self-mobilisation ability.     

Purification, amino acid sequence and immunological characterization of Ole e 6, a cysteine-enriched allergen from olive tree pollen

The Ole e 6 allergen from olive tree pollen has been isolated by combining gel permeation and reverse-phase chromatographies. It is a single and highly acidic (pI 4.2) polypeptide chain protein. Its NH₂-terminal amino acid sequence has been determined by Edman degradation. Total RNA from the olive tree pollen was isolated, and a specific cDNA was amplified by the polymerase chain reaction using a degenerate oligonucleotide primer designed according to the NH₂-terminal sequence of the protein. The nucleotide sequencing of the cDNA rendered an open reading frame encoding a 50 amino acid polypeptide chain, in which two sets of the sequential motif Cys-X₃-Cys-X₃-Cys are present. No sequence similarity has been found between this protein and other previously described polypeptides.     

NGF controls APP cleavage by downregulating APP phosphorylation at Thr668: relevance for Alzheimer's disease

NGF has been implicated in forebrain neuroprotection from amyloidogenesis and Alzheimer's disease (AD). However, the underlying molecular mechanisms are still poorly understood. Here, we investigated the role of NGF signalling in the metabolism of amyloid precursor protein (APP) in forebrain neurons using primary cultures of septal neurons and acute septo‐hippocampal brain slices. In this study, we show that NGF controls the basal level of APP phosphorylation at Thr668 (T668) by downregulating the activity of the Ser/Thr kinase JNK(p54) through the Tyr kinase signalling adaptor SH2‐containing sequence C (ShcC). We also found that the specific NGF receptor, Tyr kinase A (TrkA), which is known to bind to APP, fails to interact with the fraction of APP molecules phosphorylated at T668 (APP^pT668). Accordingly, the amount of TrkA bound to APP is significantly reduced in the hippocampus of ShcC KO mice and of patients with AD in which elevated APP^pT668 levels are detected. NGF promotes TrkA binding to APP and APP trafficking to the Golgi, where APP–BACE interaction is hindered, finally resulting in reduced generation of sAPPβ, CTFβ and amyloid‐beta (1‐42). These results demonstrate that NGF signalling directly controls basal APP phosphorylation, subcellular localization and BACE cleavage, and pave the way for novel approaches specifically targeting ShcC signalling and/or the APP–TrkA interaction in AD therapy.     

Primary structure and biological activity of bradykinin potentiating peptides fromBothrops insularis snake venom

Several bradykinin potentiating peptides (BPPs) were isolated from the venom of the Brazilian arboricole snake Bothrops insularis by gel filtration on Sephadex G-150-120, followed by sequencial high-voltage paper electrophoreses atpH 3.5, 6.5, and 2.1. The BPPs were assayed by their ability to potentiate the contractile activity, on the isolated guinea pig ileum, and the hypotensive activity, on anesthetized rats, of bradykinin. Eight BPPs, containing 3–13 amino acid residues, were sequenced and their primary structures were shown to have a marked degree of homology with those of several BPPs from other venoms.     

Adattamenti fisiologici alla vita « aerea » nel genere Tillandsia

Abstract

Physiological adaptations to « aerial » life in the genus Tillandsia.—Ten « atmospheric » Tillandsia species, with different degree of adaptation to drought, were investigated to verify the occurrence of CAM and to determine their daily transpiration pattern.

Most of the species were collected during the Botanical Expeditions of the Accademia dei Lincei in Latin America in 1969 and 1971. All species had been maintained in the greenhouse of the Naples Botanical Garden during the winter months and in the open air during the warmer months, previous to experiments. The diurnal cycle of transpiration, the malic acid content and cell sap pH of the leaves were studied under outdoor conditions. Curves of malic acid and pH variations typical of CAM have been obtained for all the examined species. Moreover, the transpiration data indicate that stomata are open at night. The rates of transpiration appear to be extremely low. The highest transpiration rates refer to the species of the relatively moister habitats, the lowest to the more xeric species. Results indicate that CAM and low rates of transpiration are ecological adaptations to extremely dry habitats.