Volume 14, Part 1, February 2000

Mycological Dispatches

Hope for 'diabet ic' mice and maybe men - andwomen - comes from a species of Pseudo-ma ssaria, an ascomycete (Hyponectriaceae),according to a research report by Zhang et al. inScience 284 (1999) 974-977. The strain, ATCC74411 , " .. .was recovered from leaves of anundetermined plant collection near Kinshasa,Democratic Republic of Congo." Trisha Guraprovides the News of the Week synopsis, p. 886,entitled "New lead found to a possible 'InsulinPill ' ." The research group, led by Zhang andMoller of Merck's New Jersey laboratory, hasfound that the fungus produces a unique agentthat may lead to a new type of antidiabetes pillthat would obviate the need for injections. Thegroup's screening protocol used tissue cultures ofhamster ovary cells modified to produce thehuman insulin receptor. Around 50,000 tests ofmixes of synthetic chemicals and natural extractswere carried out before positive results wereachieved from an extract prepared fromPseudomassaria culture broth. From the manycompounds in this medium, Gino Salituro, aMerck chemist, was able to purify the activeagent, a unique insulin mimetic quinone, L-783-281 (dimethylesterriquinone B-1), whichstimulated the phosphorylating activity of thecultured insulin receptors by up to 100times morethan the other natural products tested. In notbeing a protein, like insulin, L-783-281 should beable to withstand digestion if administered orally.When tested on mutant mice with symptomssimilar to those of patients afflicted with type 2(adult onset) diabetes, the results showed areduction in such symptoms as high blood sugar

and defects in insulin production and an enhancedability to respond to insulin. The report includes apicture of a Pseudomassaria culture on agar,showing its dark orange-brown colour.

A News Focus report by Virginia Morell inScience 284 (1999) 728-731 asks "Are pathogensfelling frogs?" . In Australia a massive die-off ofmore than a dozen species of frogs, including themotorbike frog (so-called from the gear-changingsound of its call) and four species that appear tohave become extinct, is b eing attributed toBatrachochytrum dendrobatidi s, a recentlydescribed new genus and species identified byPeter Daszak (University of Georgia , Athens).The first die-offs occurred near Brisbane in 1979,perhaps from an introduced infected exotic frog,and from there spread, at a rate of 100 km/yr,throughout the continent.

This virulent fungus is also a prime suspect inthe catastrophic pandemic that includes thedisappearance of frogs in Panama and CostaRica, mass die-offs in the United St ates, and,some epidemiologists believe, may be the keyfactor in the sudden, mysterious decline of frogsaround t he globe since 1970. Preliminary geneticstudies indicate that only a single species isinvolved , that it is a newly emerging, highlypathogenic, amphibian disease, and that it israpidly spreading to new areas worldwide. Theinfection is believed to start when zoosporesinvade surface skin cells and then grow by usingtheir keratin. The subsequent cause of death isunknown, but a toxin is suspected.

R. T. Moore

Myco-Snippets

'Extinct' fungus is rediscovered

The 4 January 2000 issue of the Independent(and some other 'quality' newspapers) reportedthat Cytidia salicina (Corticiaceae), a commonred fungus on Salix last seen in north-eastScotland in 1900 has turned up again.Originally found by the Rev. J. Keith, Minister

of Forres, in 1886, it has now been rediscoveredby a r etired forester in Kielder Forest ,Northumberland. It is apparently common In

Scandinavia.

RTM

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