NGF activates the phosphorylation of MAP1B by GSK3beta through the TrkA receptor and not the p75(NTR) receptor

We have recently shown that nerve growth factor (NGF) induces the phosphorylation of the microtubule-associated protein 1B (MAP1B) by activating the serine/threonine kinase glycogen synthase kinase 3beta (GSK3beta) in a spatio-temporal pattern in PC12 cells that correlates tightly with neurite growth. PC12 cells express two types of membrane receptor for NGF: TrkA receptors and p75NTR receptors, and it was not clear from our studies which receptor was responsible. We show here that brain-derived neurotrophic factor, which activates p75NTR but not TrkA receptors, does not stimulate GSK3beta phosphorylation of MAP1B in PC12 cells. Similarly, NGF fails to activate GSK3beta phosphorylation of MAP1B in PC12 cells that lack TrkA receptors but express p75NTR receptors (PC12 nnr). Chick ciliary ganglion neurons in culture lack TrkA receptors but express p75NTR and also fail to show NGF-dependent GSK3beta phosphorylation of MAP1B, whereas in rat superior cervical ganglion neurons in culture, NGF activation of TrkA receptors elicits GSK3beta phosphorylation of MAP1B. Finally, inhibition of TrkA receptor tyrosine kinase activity in PC12 cells and superior cervical ganglion neurons with K252a potently and dose-dependently inhibits neurite elongation while concomitantly blocking GSK3beta phosphorylation of MAP1B. These results suggest that the activation of GSK3beta by NGF is mediated through the TrkA tyrosine kinase receptor and not through p75NTR receptors.     

2-Propanol degradation by Sulfolobus solfataricus

Sulfolobus solfataricus used 2-propanol and 2-propanone (acetone) when grown in static cultures at 78 °C with or without glucose at 10 g l^–1. The presence of 3.92 g 2-propanol l^–1 in both cases inhibited growth. However, acetone accumulation following 2-propanol depletion suggested that 2-propanol was co-metabolized via the acetone metabolic pathway. Glucose at 10 g l^–1 increased 2-propanol and acetone utilization from 0.93 g l^–1 to 1.77 g l^–1 and from 0.11 g l^–1 to 1.62 g l^–1, respectively. Without glucose, immobilized S. solfataricus cells increased the 2-propanol removal rate to 0.035 g l^–1 h^–1, compared to 0.0012 g l^–1 h^–1 by its suspended counterpart. The results suggest the establishment of an immobilized reactor configuration is preferential for the treatment of high temperature solvent waste streams by this acidothermophilic Crenarchaeon.     

Rapid detection of columnaris disease in channel catfish (Ictalurus punctatus) with a new species-specific 16-S rRNA gene-based PCR primer for Flavobacterium columnare

A 16-S rRNA gene from the chromosomal DNA of the fish-pathogenic bacterium Flavobacterium columnare (formerly Flexibacter columnaris), strain ARS-I, was cloned, sequenced and used to design a polymerase chain reaction (PCR) primer set. The primer set amplified a specific 1193-bp DNA fragment from F. columnare strains but not from related bacteria, F. psychrophilum, F. aquatile, F. branchiophilum, or other bacterial pathogens of fish, Flexibacter maritimus, Cytophaga johnsonae, Edwardsiella ictaluri, E. tarda, Aeromonas hydrophila, and Streptococcus iniae or from the non-fish pathogen Escherichia coli. The PCR reaction conditions were optimized to permit detection of the organism from agar plates, broth culture, frozen samples, dead fish tissue, and live fish in less than 5 h (8 h, if the more sensitive nested PCR is used). DNA was extracted by a boiled-extraction method or by commercial column purification. The PCR product was detected at DNA concentrations below 0.1 ng and from as few as 100 bacterial cells. Nested PCR using universal eubacterial primers increased the sensitivity five-fold, allowing detection of F. columnare strains at DNA concentrations below 0.05 ng and from as few as 10 bacterial cells in apparently healthy, asymptomatic fish. The efficiency of this primer set was compared to the 16-S rRNA gene primer sets of Toyama et al. [Fish Pathol. 29 (1994) 271.] and that of Bader and Shotts [J. Aquat. Anim. Health 10 (1998) 311.]. The new primer set is as good or better than the previously published primer sets for detecting F. columnare in all samples and under all conditions tested.     

Photorhabdus: towards a functional genomic analysis of a symbiont and pathogen

Pathogenicity and symbiosis are central to bacteria-host interactions. Although several human pathogens have been subjected to functional genomic analysis, we still understand little about bacteria-invertebrate interactions despite their ecological prevalence. Advances in our knowledge of this area are often hindered by the difficulty of isolating and working with invertebrate pathogenic bacteria and their hosts. Here we review studies on pathogenicity and symbiosis in an insect pathogenic bacterium Photorhabdus and its entomopathogenic nematode vector and model insect hosts. Whilst switching between these hosts, Photorhabdus changes from a state of symbiosis with its nematode vector to one of pathogenicity towards its new insect host and both the bacteria and the nematode then cooperatively exploit the dying insect. We examine candidate genes involved in symbiosis and pathogenicity, their secretion and expression patterns in culture and in the host, and begin to dissect the extent of their genetic coregulation. We describe the presence of several large genomic islands, putatively involved in pathogenicity or symbiosis, within the otherwise Yersinia-like backbone of the Photorhabdus genome. Finally, we examine the emerging comparative genomics of the Photorhabdus group and begin to describe the interrelationship between anti-invertebrate virulence factors and those used against vertebrates.     

The "Gent" consensus on perforator flap terminology: preliminary definitions

Due to its increasing popularity, more and more articles on the use of perforator flaps have been reported in the literature during the past few years. Because the area of perforator flaps is new and rapidly evolving, there are no definitions and standard rules on terminology and nomenclature, which creates confusion when surgeons try to communicate and compare surgical techniques. This article attempts to represent the opinion of a group of pioneers in the field of perforator flap surgery. This consensus was reached after a terminology consensus meeting held during the Fifth International Course on Perforator Flaps in Gent, Belgium, on September 29, 2001. It stipulates not only the definitions of perforator vessels and perforator flaps but also the correct nomenclature for different perforator flaps. The authors believe that this consensus is a foundation that will stimulate further discussion and encourage further refinements in the future.