The Exobasidiales: An evolutionary hypothesis

To gain insight in the phylogenetic relationships within the Exobasidiales, septal pore apparatus, host-parasite interactions, sori, hymenia, basidia, and nucleotide sequences from the 5′ terminal domain of the nuclear large subunit rRNA gene were studied and compared. The results of our molecular phylogenetic analyses correlate well with the morphological data and both reflect the distribution of parasites on several host groups. Thus, the Exobasidiales seem to be divided into four groups, which are distinguishable by basidial morphology and host range as follows: (i) the Exobasidiaceae parasitizing mainly Ericanae are characterized by an abaxial orientation of the hilar appendices of the ballistosporic basidiospores on the elongate basidia, (ii) the Cryptobasidiaceae occurring mainly on Lauraceae sporulate inside the host tissue with elongate gastroid basidia, (iii) the Brachybasidiaceae living on monocots are characterized by elongate basidia bearing two ballistosporic basidiospores with adaxially oriented hilar appendices, and (iv) the Graphiolaceae occurring on palms produce chains of gastroid basidia in distinct basidiocarps. The arrangement of the four groups and the tree topology within Exobasidium derived from the molecular analyses essentially parallel phylogenetic host relationships, suggesting cospeciation. Based on our results, however, the radiation of Exobasidium on Vaccinioideae cannot be explained by cospeciation alone. 1 Part 204 of the series “Studies in Heterobasidiomycetes” from the Botanical Institute, University of Tübingen     

Extremely low frequency electromagnetic fields and heat shock can increase microvesicle motility in astrocytes

The effect of extremely low frequency electromagnetic fields (EMF) on microvesicles was examined in rat astrocytes by video-enhanced microscopy in combination with a perfusable cell chamber. The EMF effect was compared with the effect of heat shock (HS) and with a combination of them both. The velocity of microvesicles was measured using image processing software (NIH Scion image 1.61). After exposure of astrocytes to EMF (50 Hz, 100microT, 1 h), the velocity of microvesicles in astrocytes increased from 0.32 +/- 0.03 microm/s (n = 120, 95% CI) in the untreated control group to 0.41 +/- 0.03 microm/s (n = 175, 95% CI). Fifteen minutes after HS (45 degrees C, 10 min) the microvesicles showed a velocity of 0.56 +/- 0.03 microm/s (n = 125, 95% CI). Combination of HS and EMF led to an increase in velocity up to 0.54 +/- 0.03 microm/s (n = 110, 95% CI). No significant difference between HS and HS+EMF was found. Compared to the untreated control group, the increased microvesicle velocity of the exposed cells might be a stress response of the cell. It is possibly a sign of intensified intracellular traffic required to adjust the metabolic needs.     

Expression of a chimeric retroviral-lipase mRNA confers enhanced lipolysis in a hibernating mammal

Hibernating mammals can survive several months without feeding by limiting their carbohydrate catabolism and using triacylglycerols stored in white adipose tissue (WAT) as their primary source of fuel. Here we show that a lipolytic enzyme normally found in the gut, pancreatic triacylglycerol lipase (PTL), is expressed in WAT of hibernating 13-lined ground squirrels (Spermophilus tridecemlineatus). PTL expressed in WAT is encoded by an unusual chimeric retroviral-PTL mRNA approximately 500 bases longer than the predominant PTL message found in other ground squirrel tissues. Seasonal measurements detect the chimeric mRNA and PTL enzymatic activity in WAT before and during hibernation, with both showing their lowest observed levels 1 wk after hibernation concludes in mid-March. PTL is expressed in addition to hormone-sensitive lipase, the enzyme typically responsible for hydrolysis of triacylglycerols in WAT. Because of the distinct catalytic and regulatory properties of both enzymes, this dual-triacylglycerol lipase system provides a means by which the fuel requirements of hibernating 13-lined ground squirrels can be met without interruption.     

He-Ne laser irradiation protects B-lymphoblasts from UVA-induced DNA damage

The effect of He-Ne laser (632.8 nm) pre-irradiation on UVA (343 nm)-induced DNA damage in the human B-lymphoblast cell line NC37 was investigated using the comet assay. He-Ne laser pre-irradiation was observed to result in a dose-dependent decrease in UVA-induced DNA damage. This effect was also found to be dependent on the incubation period between He-Ne laser pre-irradiation and the UVA exposure. Whereas the control cells with a higher DNA damage point to an initial ability of faster repair, both the control and the He-Ne laser pre-irradiated cells subsequently show the same rate of DNA repair. The results suggest that He-Ne laser irradiation protect the cells from UVA-induced DNA damage primarily through an influence on processes that prevent an initial DNA damage. Received: 10 April 2000 / Accepted: 24 November 2000     

A rapid and sensitive procedure for determination of 5-N-acetyl neuraminic acid in lipopolysaccharides of Haemophilus influenzae: a survey of 24 non-typeable H. influenzae strains

In view of the importance of 5-N-acetyl neuraminic acid in bacterial pathogenesis, a sensitive, reproducible and reliable method for the determination of 5-N-acetyl neuraminic acid levels in lipopolysaccharide (LPS) is described and applied to 24 different non-typeable Haemophilus influenzae (NTHi) strains. The method involves analysis by high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD) of terminal 5-N-acetyl neuraminic acid residues released by neuraminidase treatment of O-deacylated LPS. The procedure is relatively fast and the instrumental effort is moderate. The results of the procedure were compared with data obtained by 1H NMR and electrospray ionisation-mass spectrometry (ESI-MS). The analysis of LPS from 24 NTHi strains showed that 5-N-acetyl neuraminic acid was found to be a common constituent of LPS in NTHi. Only one strain (NTHi 432) did not show any sialylation. Molar ratios (LPS/5-N-acetyl neuraminic acid) ranged between 5/1 and 500/1. Several strains in which no 5-N-acetyl neuraminic acid could be determined by other methods including 1H NMR and ESI-MS were shown to contain 5-N-acetyl neuraminic acid by this HPAEC-PAD procedure. The method was applied to determine levels of terminal 5-N-acetyl neuraminic acid in LPS from NTHi strains grown under different conditions and mutant strains containing inactive LPS biosynthetic genes.     

Similar Susceptibility to Excess Irradiance in Sun and Shade Acclimated Saplings of Norway Spruce [Picea Abies (L.) Karst.] and Stone Pine (Pinus Cembra L.)

Photosynthetica - We compared the responses of sun and shade acclimated saplings of Picea abies and Pinus cembra to excess photosynthetic photon flux density (PPFD) equivalently exceeding the level...     

Foetidin,a sesquiterpenoid coumarin from Ferula assa-foetida

A new sesquiterpenoid coumarin, foetidin, has been isolated from the roots of Ferula assa-foetida.     

Further characterization of 4-bromomisonidazole as a potential detector of hypoxic cells

[14C]Bromomisonidazole was prepared by direct bromination of [ring-2] [14C]misonidazole in dioxane. The uptake and binding of the two labeled sensitizers were compared in vitro in 1-mm EMT-6 spheroids which contain a necrotic core. Using liquid scintillation counting it was shown that spheroids incubated with 50 microM [14C]bromomisonidazole concentrated drug above levels in the medium by 1 1/2 hr and achieved maximum concentration by 10 hr with no further increase at 23 hr. Spheroids incubated with 50 microM [14C]misonidazole may concentrate the sensitizer more slowly but ultimately reached the same fivefold increase over levels in the medium by 23 hr as was observed for bromomisonidazole. Autoradiographs prepared from spheroids after incubation with [14C]misonidazole or [14C]bromomisonidazole showed silver grains preferentially located over viable hypoxic cells in the inner half of the spheroid rim adjacent to the necrotic center, with lower grain density over nonviable necrotic areas and many fewer grains over oxic cells at the periphery of the spheroid. The results indicate that both severely and moderately hypoxic cells may preferentially bind [14C]bromomisondiazole. The data support the potential of radiolabeled bromomisonidazole for in vivo imaging pending additional studies of the metabolism of this agent.