Culture collections of microfungi

The various methods for the preservation and storage of fungal cultures are described. Type, reference and standard collections are maintained at the Commonwealth Mycological Institute at Kew, Surrey. The documentation procedures adopted at C.M.I, and the uses made of these separate collections are outlined.     

Effect of External Supply of Growth Substances on Axillary Proliferation and Development in Dioscorea bulbifera

Bulbil development in cultured nodes of D. bulbifera proceededin the absence of growth substances from the medium. When IAAwas incorporated into the medium at the concentrations of 5mg l^–1 and 10 mg l^–1 the cultured nodes producedlarger bulbils than in its absences. When the concentrationof IAA was increased to 15 mg l^–1, however, the culturednodes produced a callus instead of a properly organized bulbil.The dry weight of bulbils increased when kinetin was added tothe medium at the concentrations of 0.05, 0.5, and 2.5 mg l^–1.The greatest increase was with 0.5 mg l^–1 kinetin. Onincreasing the concentration of kinetin in the medium to 5.0mg l^–1 the tissue produced had smaller dry weight thanthose produced in the absence of growth substances. Additionof different combinations of IAA and kinetin to the basal mediumresulted in the production of normal bulbils, roots, and shootsin some instances (suitable combinations) and in the productionof callus and abnormal shoots in others (non suitable combinations).     

Arabidopsis lipocalins AtCHL and AtTIL have distinct but overlapping functions essential for lipid protection and seed longevity

Lipocalins are a group of multifunctional proteins, recognized as carriers of small lipophilic molecules, which have been characterized in bacteria and animals. Two true lipocalins have been recently identified in plants, the temperature‐induced lipocalin (TIL) and the chloroplastic lipocalin (CHL), the expression of which is induced by various abiotic stresses. Each lipocalin appeared to be specialized in the responses to specific stress conditions in Arabidopsis thaliana, with AtTIL and AtCHL playing a protective role against heat and high light, respectively. The double mutant AtCHL KO × AtTIL KO deficient in both lipocalins was more sensitive to temperature, drought and light stresses than the single mutants, exhibiting intense lipid peroxidation. AtCHL deficiency dramatically enhanced the photosensitivity of mutants (vte1, npq1) affected in lipid protection mechanisms (tocopherols, zeaxanthin), confirming the role of lipocalins in the prevention of lipid peroxidation. Seeds of the AtCHL KO × AtTIL KO double mutant were very sensitive to natural and artificial ageing, and again this phenomenon was associated with the oxidation of polyunsaturated lipids. The presented results show that the Arabidopsis lipocalins AtTIL and AtCHL have overlapping functions in lipid protection which are essential for stress resistance and survival.     

DIFFERENCES IN RESTING-SITE PREFERENCE IN TWO COEXISTING LAND SNAILS, ARIANTA ARBUSTORUM AND ARIANTA CHAMAELEON (HELICIDAE), ON ALPINE SLOPES

Resting-site preference and patterns of spatial distributionwere examined in the sympatric land snails Arianta arbustorumand A. chamaeleon on two opposite slopes in the south-easternAlps, Austria. The two slopes did not differ in proportion ofA. arbustorum and A. chamaeleon (74.4% vs. 25.6% on the NNE-exposedslope and 68.3% vs. 31.7% on the SSW-exposed slope). Individualsof both species showed aggregated dispersion patterns. The nearest-neighbourmethod indicated that in both species snail aggregations predominantlyconsisted either of A. arbustorum or A. chamaeleon on the NNE-exposedslope with a mosaic of rocks and distinct patches of differentplants. On the SSW-exposed slope, which was less variable invegetation cover, snail aggregations consisted of conspecificand hetero-specific individuals. Juvenile and adult A. arbustorumpreferred to rest attached to leaves of Adenostyles alliariae,but avoided rock surfaces and patches of grass on the NNE-exposedslope. In contrast, juvenile and adult A. chamaeleon preferentiallyrested on rock surfaces, and also avoided grass patches. Juvenileand adult A. chamaeleon did not differ in resting-site preference,whereas small differences in resting sites were observed betweenjuvenile and adult A. arbustorum. Differences in resting-sitepreference is one way of niche differentiation which may allowindividuals of the two Arianta species to coexist. (Received 14 March 1996; accepted 8 July 1996)