A.D.M. Rayner

The challenge of the individualistic mycelium

A marine propeller which has a boss having inner and outer cylinders coaxially disposed with each other in such a manner that at least one opposing surface of the inner and outer cylinders is obliquely formed in trough shape of wedge type and the other opposing surface thereof is obliquely formed correspondingly in crest shape of wedge type, and a resilient member disposed in the gap between the oblique opposing surfaces of the inner and outer cylinders so as to integrate both the cylinders.

Fungal Communities in the Decay of Wood

Nowhere, we believe, can the presence of fungal communities, their structure, dynamics, and diversity, be more explicit and susceptible to direct analysis than in decaying wood. In consequence, wood provides an excellent venue, both for the study of community interactions, and for the development of a conceptual framework within which they can be rationalized. Three outstanding characteristics of wood, as a resource for exploitation by heterotrophs, account for this belief: its bulk, its spatial definition, and its durability.

Outgrowth Patterns of Mycelial Cord-forming Basidiomycetes from and between Woody Resource Units in Soil

SUMMARY: Wood blocks colonized by the basidiomycetes Hypholoma fasciculare and Phanerochaete velutina were placed in plastic trays containing moist unsterilized soil. Both fungi grew out radially from the inoculum blocks in the form of networks of mycelial cords. When a second, uncolonized wood block, or set of wood blocks, was provided as a ‘bait’ about 5 cm from the inoculum block, marked changes in the form and growth characteristics of the mycelial network followed contact with the bait. These changes were influenced by the relative size of inoculum and bait and included inhibition of radial extension from the inoculum; stimulation of development of connective mycelium; directed growth responses to the bait; fan-shaped outgrowth with conserved polarity from the bait; eventual regression of non-connective mycelium originating from the inoculum. These effects presumably reflect the capacity of the mycelium to behave as a co-ordinated unit and to economize on biomass when growing between discontinuously supplied resource units.

Extent, development and function of mycelial cord systems in soil

Mycelial cord systems of Phallus impudicus, Phanerochaete velutina, Steccherinum fimbriatum, Stropharia aeruginosa and Tricholomopsis platyphylla, when excavated in the field, were found to be between 318 m (5. aeruginosa) and 317 m (P. velutina) in overall length. Cord systems of P. impudicus, P. velutina and T. platyphylla increased in length by 0.8, 0.95 and l.0 m respectively over 12–14 months. In all cases extension occurred via the peripheries of the systems, whilst certain more central parts disappeared. Mycelial development from colonized wood-blocks in tubes of non-sterile soil showed similar patterns to that observed in the field. However, in tubes of γ-irradiated soil mycelia were not aggregated into cords to such an extent as in non-sterile soil, and, except for T. platyphylla, had slower extension rates, although sometimes being more luxuriant. Wood-blocks colonized by Hypholoma fasciculate, S. fimbriatum, P. impudicus and P. velutina underwent significantly greater losses in dry weight in sterile soil than did blocks in non-sterile soil, except for those colonized by T. platyphylla. Cord systems of like and unlike mycelial types of P. velutina from wood blocks fused in soil, but whilst fusion of those of like mycelial type gave rise to cords of substantial diameter, fusions between different mycelial types were followed by death of the fine cords in the fused regions and avoidance of such regions thereafter. Cord formation by a coprophilous species occurred in non-sterile but not sterile conditions, and was associated with strong substratum directed growth responses.

Degrees of freedom : living in dynamic boundaries

Defining dynamic boundaries scaling hierarchies - individuals and collectives from molecules to communities determinacy and indeterminacy differentiation and integration versatility and degeneracy balance and circumstance me and you, us and them - merger, takeover and rejection compassion in place of strife - the future of human relationships?.

Mating behaviour, mycelial antagonism and the establishment of individuals in Stereum hirsutum

Single basidiospore isolates from different fruit bodies of Stereum hirsutum always produced a morphologically distinct secondary mycelium when paired in culture. This type of mycelium was only formed in certain crosses between sibs, and the strains belonged to two incompatibility groups, indicating that the species is heterothallic. Secondary mycelia obtained from various compatible combinations of non-sibs were always strongly antagonistic when paired. Field isolates from fruit body tissue or wood were similarly antagonistic if obtained from different columns of decay in the same log or from separate localities, indicating that they represented separate heterokaryotic individuals. An unusual reaction occurred in about one-third of the incompatible pairings between sibling monospore mycelia. This took the form of a band of appressed, sparse mycelium, widest at the ends, and bounded by narrow regions of exuded droplets. These bands usually expanded unilaterally, with one of the isolates partially or totally replacing the other. In some cases this expansion stopped along a line where typical antagonism later developed. On the basis of these reactions, a simple procedure for detecting interfertility between Stereum isolates is described. This may facilitate an experimental taxonomic approach hitherto thought impossible for Stereum due to the widely held belief that members of the genus are homothallic.

Mycelial interactions, morphogenesis and ecology of Phlebia radiata and P. rufa from oak

Attached or fallen branches of oak ( Quercus robur ) colonized by Phlebia radiata and P. rufa were collected from locations in South-West Britain, and the patterns of decay within the branches analysed. Isolates were cultured from decayed wood, fruit-body tissue and from single basidiospores. Isolates were paired on malt agar in various combinations and also against other species of decay fungi. Bipolar incompatibility was found in both species, although P. rufa behaved inconsistently, and intraspecific pairings between genetically different dikaryons were mutually antagonistic. Pairings between the two species always resulted in strong mutual antagonism, immediately after hyphal fusion, and no dikaryons with clamp connexions were formed between homokaryons. Both species tended to replace other decay fungi in culture, but P. radiata was generally the more successful. All of the above interactions appeared to depend on contact with septate mycelia. Colonies of both species on agar extended relatively rapidly from a wide peripheral zone of appresed, mostly coenocytic mycelium which generally lacked hyphal fusions. Behind this zone, which was wider in P. radiata than in P. rufa , hyphae with clamp connexions developed and aerial mycelium was formed. The aerial mycelium of P. rufa was generally rather localized and rapidly aggregated into small hymenial surfaces on homokaryotic and dikaryotic mycelia. P. radiata formed a much more diffuse, floccose aerial mycelium which formed hymenia only occasionally on old cultures. Homokaryotic and dikaryotic cultures of both species produced oidia, although P. rufa did so more abundantly and more consistently than P. radiata . The cultural differences between the two species were correlated with differences in their ecology: P. radiata is regarded as a secondary colonizer, but P. rufa is probably a pioneer colonizing weakened, but still-living wood.

Population structure, inter-mycelial interactions and infection biology of Stereum gausapatum

Isolates from wood, fruit body tissue and single basidiospores of Stereum gausapatum from several locations in South-West England showed several types of reaction when paired on 2% malt agar. ‘Compatible’ reactions resulted in the formation of a distinct secondary mycelium between monospore isolates. ‘Lytic’ reactions resulted in the development, between monospore isolates, of a crescent-shaped zone of appressed mycelium bounded by regions of liquid droplet exudation. In pairings between sibs, the distribution of these two reaction types showed a reciprocal relationship depending on which fruit body had been used for isolation. In non-sib pairings the compatible reaction predominated although, as in a few sib pairings, in many instances it appeared to follow an initial lytic reaction. A narrow pigmented zone of ‘mutual antagonism’ was usually formed between different wood or fruit body tissue isolates, or laboratory-produced secondary mycelia, and also between certain non-compatible/non-lytic combinations of monospore sibs. Some interactions between monospore sibs were ‘weak’, with little or no pigment production or other obvious effect. These observations suggest that S. gausapatum is heterothallic and that there is a link between the mechanisms underlying the lytic and compatible reactions. The implications in the infection biology of S. gausapatum and in relation to findings for other Stereum spp. are discussed.

Structure and development of mycelial cord systems of Phanerochaete laevis in soil

The total length of a mycelial cord system of Phanerochaete laevis , present in the surface soil and litter of a deciduous woodland, increased from 1415 to 1479 cm over a period of 13 months. This increase was accompanied by loss of 270 cm from the central parts, and a corresponding proliferation at the periphery of the system. Mycelial growth from colonized beech blocks (approx. 8 cm 3 ) into 30 cm long glass tubes containing γ-irradiated soil showed little differentiation of cords and usually ceased well before reaching the ends of the tubes. By contrast, in similar tubes containing unsterilized soil, well-defined cord systems were formed which reached the ends of the tubes within about 15 weeks. These developed from an advancing front of more or less constant width containing numerous finely-branched cords. Following lysis at the rear of this front a relatively few large cords remained which were still connected to the blocks. Light inhibited mycelial development in the tubes in both γ-irradiated and unsterilized soil. After 15 weeks in the tubes wood blocks from γ-irradiated soil had undergone a greater loss in dry weight (22–27% compared with about 15%) and had a higher nitrogen content than those from non-irradiated soil.

Responses of Living Hyphae Associated with Self and Non-self Fusions in the Basidiomycete Phanerochaete velutina

SUMMARY: Before fusion, hyphae of the basidiomycete Phanerochaete velutina responded similarly to one another when grown on a cellophane membrane, regardless of whether they were genetically the same or different. Long-range (up to 250 μm) curvature (homing) to specific sites in the lateral wall of recipient compartments often occurred in fusions involving main hyphal apices. Induction of tip outgrowth from lateral walls was most evident before short-range, tip-to-tip fusions resulting in H-connections between main hyphae. Spitzenkorper (apical bodies) became aligned with receptive sites before directed growth. A period (about 5–20 min) of expansion of the contact region preceded formation of a fusion pore. Fusions were abundant in the vicinity of septa, but never observed between tips of main hyphae which repelled one another. In fusions involving hyphae from the same thallus or of mating-incompatible homokaryons, the fusion pore usually enlarged until it occupied virtually the entire contact area. Except in the case of clamp-connexions, nuclear interchange was followed by aggregation and division in the pore region before septum formation. Between different heterokaryons, the fusion pore never expanded fully, nuclei were rarely exchanged, and rapid cytoplasmic lysis and vacuolation occurred. Lysis also occurred sooner or later between sexually compatible homokaryons; only in a few cases was dolipore dissolution and nuclear migration observed.