Coprinellus Disseminatus Research Articles

Effects of growth-retarding environmental factors on growth kinetics and clamp connexion occurrence in the dikaryon of Coprinus disseminatus

Main leader hyphae of Coprinus disseminatus formed clamp connexions when dikaryotic colonies were grown under favourable conditions. When colony radial growth rate was slowed down by reducing the incubation temperature, incorporation of an inhibitor in the medium (cycloheximide, emetine, p-fluoro- dl -β phenyl-alanine, 2-deoxy- d -glucose, copper sulphate, sodium taurocholate or griseofulvin) or reducing the water potential of the medium with sucrose or potassium chloride, no clamp connexions were formed. The leader hyphae remained heterokaryotic dikaryons and the mean threshold colony radial growth rate for expression of clamp connexions was 174 μm h−1. Mean interseptal cell length and mean hyphal diameter reached their maxima between 10 and 15 °C. Temperature affected tip cell generation time more than colony radial growth rate. With increasing cycloheximide concentration, mean tip cell length, mean interseptal cell length and mean hyphal diameter all decreased. Tip cell generation time was unchanged over a concentration range of cycloheximide which had a large effect on colony radial growth rate. The threshold colony radial growth rate for expression of clamp connexions was lower when different cycloheximide concentrations were tested at 17° than at 25° but the calculated threshold rates of increase in surface area of hyphal tips were similar.

Nuclear and Non-nuclear Factors influencing Clamp Connection Formation in Coprinus disseminatus

Matings between sister single spore lines of Coprinus disseminatus showed a cryptic tetrapolar pattern. The two groups of matings that resulted in formation of mycelia with clamp connections (apparent dikaryons) differed in rate of nuclear penetration during mating. In one group penetration occurred at rates comparable with nuclear migration in other species and in the other group it was often extensive but at a rate similar to, or less than, the dikaryon growth-rate. No differences were detected between these two groups in stability, colony extension rate, frequency of clamp connections, proportions of true clamp connections and pseudoclamps, or number of nuclei per hyphal tip cell. Cytological studies and the isolation of hyphal tips showed that both groups of apparent dikaryons were heterokaryotic di- or trikaryons. The di- and trikaryotic conditions co-existed in the same mycelium, but adjacent cells of individual branching systems usually contained equal numbers of nuclei. Within apparent dikaryons the number and kinds of nuclei per cell were similar in hyphae with clamp connections and those with simple septa. Treatments that prevented clamp connection formation did not alter the nuclear status of most of the hyphae. Irregularities in nuclear distribution were infrequent and most were associated with pseudoclamps. Forty per cent of nodes with probable pseudoclamps yielded homokaryotic branches, which were of either constituent mating type. There was some indication that irregularities in nuclear distribution could also occur during divisions associated with simple septa.

Enviromentally Induced Changes in Clamp Connection Incidence in Hyphal Branching Systems of Coprinus disseminatus

Enviromentally Induced Changes in Clamp Connection Incidence in Hyphal Branching Systems of Coprinus disseminatus