Oxidative d-xylose metabolism of Gluconobacter oxydans

Summary Gluconobacter oxydans subsp. suboxydans ATCC 621 oxidizes d-xylose to xylonic acid very efficiently, although it cannot grow on xylose as sole carbon source. The oxidation of xylose was found to be catalyzed by a membrane-bound xylose dehydrogenase. The xylono--lactone formed in the oxidation reaction is subsequently hydrolyzed to xylonic acid by a -lactonase. The complete oxidation pathway of d-xylose in G. oxydans is evidently located in the periplasmic space.     

Mycological records from ISAM 9, Kevo,Finland

ISAM 9 (International Symposium of Arctic-Alpine Mycology) was held in August 2012?at the Kevo Lapland Research Station in Utsjoki in northernmost Finnish Lapland. In addition to Utsjoki, some excursions were made in Finnmark, the northernmost part of Norway. Kevo station lies in the subarctic zone characterized by mountain birch (Betula pubescens var. czerepanovii), but the fells reach the arctic tundra zone. Áilegas fells at Utsjoki village and at Nuvvus lie on acid ground as does Skalluvaara, and all are under influence of reindeer grazing. The Gistuskaidi fell is highest and is characterized by the presence of more basic rocks; the vegetation also reflects some amount of maritime influence. The places visited on the Norwegian side belong to the Nesseby commune at the sea shore and Tana commune on the shore of the Tana River and along the road to Båtsfjord where the tundra is maritime and mossy with calcareous spots. In all 123 taxa were found during the excursions, some of them not determined at species level. The reported fungal taxa belong to the Basidiomycota (115 taxa), Ascomycota (7 taxa), and Mycetozoa (1 taxon).     

Effect of spatial connectivity on host resistance in a highly fragmented natural pathosystem

Both theory and experimental evolution studies predict migration to influence the outcome of antagonistic coevolution between hosts and their parasites, with higher migration rates leading to increased diversity and evolutionary potential. Migration rates are expected to vary in spatially structured natural pathosystems, yet how spatial structure generates variation in coevolutionary trajectories across populations occupying the same landscape has not been tested. Here, we studied the effect of spatial connectivity on host evolutionary potential in a natural pathosystem characterized by a stable Plantago lanceolata host network and a highly dynamic Podosphaera plantaginis parasite metapopulation. We designed a large inoculation experiment to test resistance of five isolated and five well‐connected host populations against sympatric and allopatric pathogen strains, over 4 years. Contrary to our expectations, we did not find consistently higher resistance against sympatric pathogen strains in the well‐connected populations. Instead, host local adaptation varied considerably among populations and through time with greater fluctuations observed in the well‐connected populations. Jointly, our results suggest that in populations where pathogens have successfully established, they have the upper hand in the coevolutionary arms race, but hosts may be better able to respond to pathogen‐imposed selection in the well‐connected than in the isolated populations. Hence, the ongoing and extensive fragmentation of natural habitats may increase vulnerability to diseases.     

Linkage of the long QT syndrome to the short arm of chromosome 11: use of five highly polymorphic markers towards more detailed localization of the mutant gene

The long QT syndrome is an autosomally dominantly inherited cardiac disorder characterized by abnormalities of myocardial repolarization, exercise- or stress-related syncopal attacks and risk of sudden death due to cardiac arrhythmias. Genetic linkage studies have defined three LQT loci on chromosomes 11p15.5, 3q21–24 and 7p35–36. We performed linkage analyses in three Finnish LQT families using five amplifiable markers assigned to chromosome 11p15. By multipoint linkage analyses we obtained a maximal lod score of 5.503, suggesting that the LQT1 locus maps between D11S922 and D11S1338 on chromosome 11. Our data provide a step towards closer definition of the exact borderlines of the LQT1 locus in chromosome 11 and demonstrate markers with high utility in identification of gene carriers in the affected families.     

CNS thermosensitivity and control of latent heat dissipation in the pigeon

Thermoregulatory responses to heat exposure were studied in 12 hand-reared, acclimated pigeons (Columbia livia). Measurements of body temperature (Tcl), brain temperature (Tbr), cutaneous water evaporation (CWE) and respiratory frequency (fr) were carried out in intact conscious heat exposed birds. In a second group of lightly restrained birds, fr and CWE were taken when temperatures of the trunk, brain and air (Ta) were independently changed. Increasing Tbr to 43.5–43.8°C induced a pronounced polypnea (deep and fast, (300 breaths min⁻¹) when Tcl regulated at 42.4°C. Moreover, when hyperthermia (Tcl = 43.0°C) was combined with increased Tbr (43.0–43.8°C) shallow and fast panting (>500 breaths min⁻¹) was evoked. CWE was probably elicited by inputs generated by the skin warm receptors as a result of increased Ta. Moreover it was demonstrated that warming the brain to 42.5°C elicits cutaneous water evaporation in birds exposed to 26°C. When a high Ta (60°C) is accompanied by a high relative humidity (17%), the combined effect generates inputs eliciting intensive panting. The integration of the present and earlier data allows us to generate a model demonstrating the distinguished significance of the trunk, skin and brain thermosensors in the regulation of both respiratory and cutaneous latent heat dissipation. The present model also emphasizes the fact that the highly thermosensitive pigeon brain responds in a similar pattern to that found in mammals     

Loss of histochemically demonstrable catecholamines and acetylcholinesterase from sympathetic nerve fibres of the pineal body of the rat after chemical sympathectomy with 6-hydroxydopamine

Synopsis Newborn albino rats were injected daily for 8 days with 50 g/g of 6-hydroxydopamine. They were killed 3 weeks after the last injection together with untreated litter mate controls. Monoamines were demonstrated histochemically in the pineal body, in the iris and in the superior cervical ganglion with the formaldehyde-induced fluorescence method. Acetylcholinesterase was demonstrated in the pineal using acetylcholine as substrate and tetraisopropy-pyrophosphoramide (iso-OMPA) to inhibit non-specific cholinesterases.Treatment with 6-hydroxydopamine caused a complete disappearance of amine-containing fibres from the pineal, whereas some fluorescent ganglion cells remained in the superior cervical ganglion and in some rats a few amine-containing fibres in the iris. Acetylcholinesterase activity, located in fine nerve fibres of the pineal body, disappeared completely after treatment with 6-hydroxydopamine.Since 6-hydroxydopamine causes a selective destruction of the aminergic sympathetic fibres, it is concluded that the disappearance of the acetylcholinesterase activity indicates that in the pineal body this enzyme activity is located exclusively in truly aminergic nerve fibres.     

Histochemical evidence of chemical sympathectomy by guanethidine in newborn rats

Synopsis Guanethidine is known to cause a loss of catecholamines from sympathetically innervated tissues and sympathetic ganglia in adult animals but its effect on newborn animals has not been examined.Newborn rats were injected daily with guanethidine (20 mg/kg body weight) for 8 days. They were killed when 1 month-old along with untreated litter mate controls. Catecholamines were demonstrated in the iris, in the pineal body and in sympathetic ganglia, using the formaldehyde-induced fluorescence method.In the guanethidine-treated rats there was a complete loss of fluorescent nerve fibres from the pineal body and an almost complete loss of similar fibres from the iris. The sympathetic ganglia were reduced to less than 10% of the control ganglia, and the number of nerve cell bodies per unit area was decreased in the ganglion remnants.It is concluded that guanethidine causes, in newborn rats, an irreversible destruction of most sympathetic neurons, i.e. a chemical sympathectomy closely resembling that obtainable in newborn animals by injections of 6-hydroxydopamine or antiserum to nerve growth factor.     

Microbiological, Biochemical, and Electron Microscopic Characterization of a Pectinatus Strain

A spoilage organism isolated from turbid beer is described. The bacterium was gram negative, catalase negative, strictly anaerobic, and rod shaped, having flagella only on one side of the cell. The main metabolic product was propionic acid. In addition acetic, succinic, and lactic acids and acetoin were formed. Malonate inhibited the production of propionic acid by the strain studied and by both Pectinatus and Propionibacterium strains. The guanine-plus-cytosine content of deoxyribonucleic acid was 36 mol%. Differences between this strain and Pectinatus strains were 2 to 5 percentage points. Immunofluorescent staining and gel diffusion precipitin tests revealed that the antigenic structure differed from those of Pectinatus strains. The isolated organism can, despite some differences, be regarded as belonging to the genus Pectinatus.