Widespread vegetative compatibility groups in the dry-rot fungus Serpula lacrymans

Serpula lacrymans is the most notorious decayer of wooden buildings in temperate regions. The occurrence of geographically widespread vegetative compatibility groups (VCG) in S. lacrymans in Europe is demonstrated in this study. Among 22 heterokaryotic isolates of S. lacrymans, five VCG were found. The most widespread VCG included isolates from Belgium, south and central Norway, separated by more than 1500 km. No other genetic variation, measured as DNA sequence variation or ISSR polymorphisms, was detected between the investigated S. lacrymans isolates, whereas a considerable level of genetic variation was found among five European isolates of the sister taxon, S. himantioides. It is hypothesised that isolates of S. lacrymans have lost their ability to recognize self from nonself due to sharing of similar VC alleles, caused by a recent genetic bottleneck during the establishment in northern Europe. Isolates re-isolated from overlapping mycelial zones between different compatible isolates had significantly slower growth than that of the original isolates and the different isolates within a VCG had different growth morphology, indicating that isolates within a single VCG may belong to different genets.     

Molecular phylogenetics suggest a North American link between the anthropogenic dry rot fungus Serpula lacrymans and its wild relative S. himantioides

The dry rot fungus Serpula lacrymans causes damages in wooden buildings and constructions in temperate regions worldwide. In this study, the global phylogeography of S. lacrymans and its wild relative S. himantioides has been investigated to clarify genealogical relationships and determine the origin and spread of the building strains. Internal transcribed spacer (ITS) nrDNA and parts of the beta-tubulin (tub) and the translation elongation factor (efa) 1a genes were sequenced, and phylogenetic relationships inferred. Some analyses suggest that S. lacrymans may have originated from an ancient S. himantioides lineage, but most results support that S. lacrymans and S. himantioides are monophyletic sister species. Phylogenetic analysis of the ITS data revealed two subgroups within S. lacrymans corresponding to two earlier described varieties; one group occurring frequently in houses worldwide ('Domesticus'), and one group represented by individuals from forests in Northern California ('Shastensis'). A few collections from nature were included in the Domesticus group as well, among other specimens from two newly discovered localities in Far East Russia and Siberia. In the Domesticus group little sequence variation occurs, suggesting a recent worldwide dispersal, possibly linked to human activity. Phylogenetic analyses indicate that the Domesticus group may have originated from an ancient lineage related closely to the Shastensis group. A remarkable shift in morphology and habitat preferences has occurred during the evolution of the Domesticus lineage, linked to the transition from nature to human-made habitats.     

Imaging of long-distance alpha-aminoisobutyric acid translocation dynamics during resource capture by Serpula lacrymans

alpha-Aminoisobutyric acid (AIB) is a nonmetabolized amino acid analogue of alanine, which at low (muM) concentrations acts as a tracer for amino acid movements. At high concentrations (mM), it competitively inhibits membrane transport and metabolism of protein amino acids and acts as a systemic translocated inhibitor of mycelial extension in fungi. AIB can control mycelial spread of the basidiomycete Serpula lacrymans, the cause of brown rot of wood in buildings. However, it is not known how effectively the inhibitor is distributed throughout the mycelium. Realistically heterogeneous microcosms, in which the fungus grew across nutritionally inert sand to colonize discrete wood resources, were used to investigate patterns of inhibition and translocation following local application of AIB. At a 0.1 M concentration, locally applied AIB caused immediate arrest of extension throughout the whole mycelium, maintained for a 6-week experimental period. The dynamics of translocation of subtoxic amounts of [1-(14)C]AIB ([(14)C]AIB) were mapped by photon-counting scintillation imaging in conjunction with destructive harvest to establish the velocity, direction, and rate of translocation and the extent of [(14)C]AIB reallocation accompanying the invasion of fresh wood. Locally applied [(14)C]AIB was distributed throughout complex mycelial networks within 2 h of application, becoming localized in growing margins by 12 h. Encounter with a fresh wood resource triggered a widespread response, causing withdrawal of [(14)C]AIB from throughout the network, accompanied by accumulation in the newly colonized wood and associated mycelium. The results are discussed in the context of nutrient dynamics in wood decomposer fungi and the mechanism of the amino acid reallocation response.     

Genetics of self/nonself recognition in Serpula lacrymans

This study provides an analysis of the vegetative incompatibility system in Serpula lacrymans (Basidiomycota), a genetic system used to recognize nonself in fungi. Seventy-five worldwide isolates could be grouped into eight vegetative compatibility (VC) types, some of them distributed on different continents. Mating studies combined with vegetative incompatibility analyses revealed that the vegetative incompatibility response between isolates mainly could be explained by two biallelic vegetative incompatibility (vic) loci. The frequency distributions of the interpreted vic alleles do not seem to support the idea of frequency-dependent or balancing selection acting on the vic loci. We find little genetic variation at the vic loci and in one of the loci there was a significant heterozyote deficiency among strains in the overall material. The results may be explained by a recent worldwide dispersal of a few S. lacrymans isolates and, correspondingly, only a few vic alleles are being maintained in these populations.     

The himanimides,new bioactive compounds from Serpula himantoides (Fr.) Karst

In a screening of basidiomycete cultures from Chile for the production of antibiotics we identified a Serpula himantoides strain as a producer of metabolites inhibiting the growth of bacteria and fungi. Bioactivity guided purification resulted in the isolation of four new antibiotics. Their structures were elucidated by spectroscopic methods. All four compounds are succinimide and maleimide derivatives, of which two are N-hydroxylated.     

Fungal variegatic acid and extracellular polysaccharides promote the site-specific generation of reactive oxygen species

Journal of Industrial Microbiology & Biotechnology - This study aims to clarify the role of variegatic acid (VA) in fungal attack by Serpula lacrymans, and also the generation and scavenging of...     

Localized, Cold-Induced Inhibition of Translocation in Mycelia and Strands of Serpula lacrimans

Thompson, W., Brownlee, C, Jennings, D. H. and Mortimer, A.M. 1987. Localized, cold-induce inhibition of translocationin mycelia and strands of Serpula lacrimans. —J. exp.Bot. 38: 889–899 The effect has been investigated of localized low temperatureon translocation of ³²P across myceliui of Serpula lacrimansusing two gas-flow detectors capable of recording radioactivitycontinuously. When the temperature of a band of mycelium wasreduced to 0 ? C, radioactivity ceased to accumulai and in factdeclined under the detector (number 2) separated from the sourceof radioactivity by tr cold-treated mycelium. In the myceliumbeneath the other detector (number 1), closest to the sourceradioactivity, the rate of accumulation of radioactivity increased.When the temperature was raised t 20 ?C, radioactivity beganto accumulate in the mycelium under detector 2 and, apart froma sma fluctuation, continued to accumulate at a uniform rate.In the mycelium under detector 1, the accumulation of radioactivitystopped for a short time but then recommenced at a rate similarto thi found at 0 ?C. In other experiments the distributionof radioactivity (¹⁴C) throughout the myceliui was measuredat the end in homogenized samples. In these experiments a bandof mycelium we subjected to 0 ?C or to 20 ?C for the whole experimentalperiod, or only after the mycelium had bee translocating radioactivityalready for 16 h. These experiments showed that the changesin the rate of accumulation of ³²P in living mycelium underthe two gas flow detectors used for in situ measurements werenot due to a reversal of the flow of translocation. The resultsare consistent with an hypothesis that a turgor-driven massflow of solution is the mechanism for translocation in thisfungus and are considered in relation to the results of similarexperiments on phloem translocation in higher plants. Key words: Serpula lacrimans, mycelium, translocation, low-temperature, phloem transport     

Book reviews

Book reviewed in this article:
B iotechnology V olume 2. G enetic F undamentals and G enetic E ngineering (1993). Edited by H.-J. Rehm and G. Reed.
C owan and S teel's M anual for the I dentification of M edical B acteria (1993). Edited by G.I. Barrow and R.K.A. Feltham.
Bacillus thuringiensis , AN E nvironmental B iopesticide : T heory and P ractice (1993). Edited by P.F. Entwistle, J.S. Cory, M.J. Bailey and S. Higgs.
T rends in M icrobiology : V irulence , I nfection and P athogenesis (1993).
N etworking in B rucellosis R esearch (1991). Edited by J.F. Frank.
Serpula lacrymans : F undamental B iology and C ontrol S trategies (1991). Edited by D.H. Jennings and A.F. Bravery.
M onitoring G enetically M anipulated M icroorganisms in the E nvironment (1993). Edited by C. Edwards.     

Asian origin and rapid global spread of the destructive dry rot fungus Serpula lacrymans

The dry rot fungus Serpula lacrymans (Basidiomycota) is the most damaging destroyer of wood construction materials in temperate regions. While being a widespread aggressive indoor biodeterioration agent, it is only found in a few natural environments. The geographical source of spread and colonization by this fungus in human environments is thus somewhat of an enigma. Employing genetic markers (amplified fragment length polymorphisms, DNA sequences and microsatellites) on a worldwide sample of specimens, we show that the dry rot fungus is divided into two main lineages; one nonaggressive residing naturally in North America and Asia (var. shastensis), and another aggressive lineage including specimens from all continents, both from natural environments and buildings (var. lacrymans). Our genetic analyses indicate that the two lineages represent well-differentiated cryptic species. Genetic analyses pinpoint mainland Asia as the origin of the aggressive form var. lacrymans. A few aggressive genotypes have migrated worldwide from Asia to Europe, North and South America and Oceania followed by local population expansions. The very low genetic variation in the founder populations indicate that they have established through recent founder events, for example by infected wood materials transported over land or sea. A separate colonization has happened from mainland Asia to Japan. Our data also indicate that independent immigration events have happened to Oceania from different continents followed by admixture.     

The effects of salinity,temperature and mercury on mortality of the trocophore larvae of Serpula vermicularis L. (Annelida: Polychaeta)

Using response surface methods 4-day old larvae of Serpula vermicularis L. were shown to be more euryplastic with respect to salinity and temperature than were gastrulae and 1-day old larvae. Significant interaction was found between the effects of temperature and reduced salinity on mortality of the larvae at each age tested. Four-day old trocophore larvae were more resistant to reduced salinity at low temperatures than were gastrulae and 1-day old larvae. The change in tolerance with age was in resistance rather than capacity adaptation and, since the larvae were acclimated at 16 °C, this change was genetic.Mercuric ions did not show synergistic effects with reduced salinity but merely acted additively. The concentrations of mercury found to be toxic were much higher than those that are likely to be found in coastal waters where S. vermicularis occurs.     

EXPERIMENTS ON THE EFFECT OF CENTIMETRE-LENGTH ELECTROMAGNETIC WAVES ON WOOD-DESTROYING FUNGI

In an attempt to devise a practical method of killing wood-destroying fungi, mycelia of Coniophora puteana and Merulius lacrymans were exposed to the beamed radiation from a standard Service radar transmitter transmitting pulses of radiation of wave-length 9.1 cm. Growth of Coniophora puteana on malt agar films on glass slides was checked. Many superficial hyphae were killed. Exposures up to I hr. did not kill the mycelium of either fungus when growing on malt agar slopes or plates, or wood blocks. The only obvious effect was a check in growth whenever drying of the mycelium occurred.
It is concluded that the rays have no lethal effect and injure the fungi only through drying of the mycelium due to the increase in temperature which they bring about.     

A new staphylococcal anti-inflammatory protein that antagonizes the formyl peptide receptor-like 1

Bacteria have developed mechanisms to escape the first line of host defense, which is constituted by the recruitment of phagocytes to the sites of bacterial invasion. We previously described the chemotaxis inhibitory protein of Staphylococcus aureus, a protein that blocks the activation of neutrophils via the formyl peptide receptor (FPR) and C5aR. We now describe a new protein from S. aureus that impaired the neutrophil responses to FPR-like1 (FPRL1) agonists. FPRL1 inhibitory protein (FLIPr) inhibited the calcium mobilization in neutrophils stimulated with MMK-1, WKYMVM, prion-protein fragment PrP(106-126), and amyloid beta(1-42). Stimulation with low concentrations of fMLP was partly inhibited. Directed migration was also completely prevented toward MMK-1 and partly toward fMLP. Fluorescence-labeled FLIPr efficiently bound to neutrophils, monocytes, B cells, and NK cells. HEK293 cells transfected with human C5aR, FPR, FPRL1, and FPRL2 clearly showed that FLIPr directly bound to FPRL1 and, at higher concentrations, also to FPR but not to C5aR and FPRL2. FLIPr can reveal unknown inflammatory ligands crucial during S. aureus infections. As a novel described FPRL1 antagonist, it might lead to the development of therapeutic agents in FPRL1-mediated inflammatory components of diseases such as systemic amyloidosis, Alzheimer's, and prion disease.     

Serpula lacrymans reacts with a general,unspecialized chemical response during interaction with mycoparasitic Trichoderma spp. and bacteria

Serpula lacrymans causes structural damage in timber via cellulose and hemicellulose decomposition. Serpula lacrymans shares its habitat with bacteria and fungi, interactions that often result in stress and changed behaviour of the partners. A typical response to environmental stress is the production of bioactive metabolites and pigments. The diversity and function of these metabolites in inter- and intra-kingdom interactions, is largely elusive. Using dual culture approaches and secondary metabolite fingerprinting with high performance thin layer chromatography (HPTLC) it was demonstrated that stress induces an unspecific vs. Similar metabolite patterns were identified when S. lacrymans was co-cultured with different bacteria and mycoparasitic fungi (Trichoderma spp.). By analysing the metabolites produced along the gradient from the contact zone to more remote parts of the mycelium, we show a systemic reaction of S. lacrymans and that direct contact with other microbes is not a necessity to induce secondary metabolites.     

Production of Conidia by Botrytis fabae grown in vitro

Conidiation in Botrytis fabae was stimulated by irradiating 1 to 3 day old, but not 4 to 5 day old mycelium. Three cycles of 12 h irradiation + 12 h darkness stimulated the production of about twice as many spores compared with only 12 h irradiation. At 18°C all the spores had been produced within 3 days but not within 2 days from the start of irradiation. Near-u.v. irradiation at wavelengths of 375–400 nm induced most sporulation. Red light at 600–650 nm also stimulated conidiation but irradiation at other wavelengths from 300 to 700 nm was ineffective. Fewer conidia were produced when the fungus was kept in darkness at 4°C between periods of irradiaton at 18°C compared with continuous 18°C. The optimum osmotic potential of the culture, medium for conidiation was about-27 bar although more mycelium grew at even lower osmotic potentials. Abundant spore production occurred when the fungus was grown in media with a wide range of pH values.     

Improved molecular methods to characterise Serpula lacrymans and other Basidiomycetes involved in wood decay

Early detection of indoor wood-decay fungi is crucial to prevent building deterioration and thereby avoid considerable economic loss. Due to their increased sensitivity, two reliable DNA-based fingerprinting techniques, capillary electrophoresis single-strand conformation polymorphism (CE-SSCP) and denaturing high-performance liquid chromatography (DHPLC), were used to identify Serpula lacrymans and to profile wood-rot Basidiomycetes in the built environment. Molecular fungal diversity was assessed on 74 environmental samples, collected from 2003 to 2009 from infected buildings in France. S. lacrymans, the most widespread, indoor wood-decay fungus accounted for 64% of total wood-rot Basidiomycetes. A number of other common wood-rot fungi such as Coniophora puteana, Trametes versicolor and Donkioporia expansa were identified. Other Basidiomycetes such as Phlebiopsis gigantea and Scleroderma verrucosum were detected for the first time in the built environment. Reliable diagnostic tools were developed using two PCR-based molecular typing techniques, one for routine diagnosis and another one for community inventories. Together they provided useful data for characterising the complexity of wood-decay ecosystems and helped reveal the coexistence of different wood-decay fungi within the same microbiotope.     

Biological characterization of induced phages from Saccharopolyspora hirsuta 367 and comparison with phage JHJ-1.

Phages JHJ-2 and JHJ-3 were isolated from Saccharopolyspora hirsuta 367 UC 8106 following induction with mitomycin C and amplified on S. hirsuta NRRL B-5792. Their properties were compared with those of phage JHJ-1, isolated previously from S. hirsuta 367 NRRL 12045. The DNA restriction patterns appeared to be identical. One-step growth experiments showed no differences between the replication cycles. Burst sizes ranged from 100 to 110 p.f.u. per cell. However, the three phages showed some differences in their behaviour in different hosts. The host range of phage JHJ-1, on non-lysogenic strains, was emended to include all of the Saccharopolyspora strains tested; the host range of phage JHJ-2 was shown to be identical to JHJ-1. Phage JHJ-3 did not form detectable plaques on strains of S. rectivirgula or S. erythraea except S. erythraea NRRL 2359. Neither phage JHJ-2 nor JHJ-3 formed plaques on any lysogenic strains, while JHJ-1 formed plaques on all such strains except S. hirsuta 367 UC8106. Phage JHJ-3 was characterized as a temperate bacteriophage because it formed turbid, self-limiting plaques and lysogenized S. hirsuta NRRL B-5792. It was spontaneously released from UC8106. Both JHJ-1 and JHJ-2 formed clear and invasive (Inv+ phenotype: the property to grow on old mycelium) plaques on some Saccharopolyspora strains but clear and self-limiting plaques on others. Thus, the expression of the Inv+ phenotype encoded by JHJ-1 and JHJ-2 appears to be modulated by the host cell.     

On the histochemical demonstration of N-acetyl-β-galactosaminidase

Summary Aging neurons accumulate lipofuscin pigment granules which appear to be secondary lysosomes of the residual body variety. The biological significance of the residual bodies is debated. They were here studied with the aim of testing a hypothesis that the membranes surrounding these granules might be more vulnerable than the membranes around younger types of lysosomes.For this purpose large motor neurons of young and old rats were compared with respect to lysosomal membrane latency, using a modified Bitensky lysosomal lability test. Utilizing successively increasing incubation times, the lysosomes of old neurons, in particular the residual bodies in polar aggregates of old neurons—presumed to represent lipofuscin pigment granules—were found to have a clearly reduced latency in comparison with lysosomes of young neurons.These findings support the notion that the residual bodies are more fragile than younger lysosomes.Supported by the Swedish Medical Research Council (Project No. 12X-2037).     

Background and radiation resistance tests of neutral particle analyzer detectors for ITER by using a fast neutron beam

The radiation resistance and background sensitivity of scintillation (Hamamatsu H8500D photo-multiplier) and semiconductor (ORTEC BF-018-100-60 and BU-012-050-100) detectors to neutron and gamma radiation were investigated. Conclusions are drawn concerning the possibility of using such detectors in neutral particle analyzers that are being developed for ITER at the Ioffe Institute.     

The expression of lipopolysaccharide by strains of Shigella dysenteriae, Shigella flexneri and Shigella boydii and their cross-reacting strains of Escherichia coli

Strains of Shigella dysenteriae, Shigella flexneri and Shigella boydii express lipopolysaccharides, that enable the serotyping of strains based on their antigenic structures. Certain strains of S. dysenteriae, S. flexneri and S. boydii are known to share epitopes with strains of Escherichia coli ; however, the lipopolysaccharide profiles of the cross-reacting organisms have not been compared by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) lipopolysaccharides profiling. In the present study, type strains of these bacteria were examined using SDS-PAGE/silver staining to compare their respective lipopolysaccharide profiles. Strains of S. dysenteriae, S. boydii and S. flexneri all expressed long-chain lipopolysaccharide, with distinct profile patterns. The majority of strains of Shigella spp., known to cross-react with strains of E. coli , had lipopolysaccharide profiles quite distinct from the respective strain of E. coli . It was concluded that while cross-reacting strains of Shigella spp. and E. coli may express shared lipopolysaccharide epitopes, their lipopolysaccharide structures are not identical.