ABSTRACT. T h e m e t h o d s u s e d b y c o l l a b o r a t o r s i n t h e I n t e r n a t i o n a l S t r e p t o m y c e s P r o j e c t (ISP)f o r . e m e n d a t i o n of d e s c r i p t i o n s of t y p e a n d n e o t y p e s t r a i n s of t h e g e n u s S t r e p t o m y c e s ( A c t i n o m y c e t a l e s ) a r e p r e s e n t e d . -------------An international cooperative effort, now i n progress, is directed toward collection of type cultures of the Streptomyces species for deposition with the Centraalbureau voor Schimmelcultures (CBS), Baarn. F r o m this center the reference cultures will be supplied to other culture collections s o that they a r e available throughout the world.An essential adjunct t o this activity is the redescription of each type culture in t e r m s of currently acceptable c r it e r i a and methods. Theurgent need for an authentic reference collection, accompanied by standardized characterizations f o r each species, has been pointed out by spokesmen f o r the several meetings and conferences which culminated i n this project.(See, for example, Gottlieb, 1959Gottlieb, , 1961 Kiister, 1959; Krasil'nikov, I961 .) More than 40 investigatorst representing 17 countries a r e participating in this research. Each culture is described independently by three of these cooperating specialists i n different laboratories before i t is deposited in the reference collection.This project is supported in part by a r e s e a r c h grant f r o m the National Science Foundation, U. S. A. The Subcommittee on Actinomycetes of the Committee on Taxonomy, A. S. M. and the Subcommittee on,Taxonomy of Actinomycetes of the International Committee on Bacteriological Nomenclature a r e co-sponsoring advisors.Participants in the 1964-1965 studies a r e listed on p. 338.

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Mouse embryonic stem (ES) cells cultured as aggregates and exposed to retinoic acid are induced to express multiple phenotypes normally associated with neurons. A large percentage of treated aggregates produce a rich neuritic outgrowth. Dissociating the induced aggregates with trypsin and plating the cells as a monolayer results in cultures in which a sizable percentage of the cells have a neuronal appearance. These neuron-like cells express class III beta-tubulin and the neurofilament M subunit. Induced cultures express transcripts for neural-associated genes including the neurofilament L subunit, glutamate receptor subunits, the transcription factor Brn-3, and GFAP. Levels of neurofilament L and GAD67 and GAD65 transcripts rise dramatically upon induction. Physiological studies show that the neuron-like cells generate action potentials and express TTX-sensitive sodium channels, as well as voltage-gated potassium channels and calcium channels. We conclude that a complex system of neuronal gene expression can be activated in cultured ES cells. This system should be favorable for investigating some of the mechanisms that regulate neuronal differentiation.

Transplantation approaches using cellular bridges, fetal central nervous system cells, fibroblasts expressing neurotrophin-3 (ref. 6), hybridoma cells expressing inhibitory protein-blocking antibodies, or olfactory nerves ensheathing glial cells transplanted into the acutely injured spinal cord have produced axonal regrowth or functional benefits. Transplants of rat or cat fetal spinal cord tissue into the chronically injured cord survive and integrate with the host cord, and may be associated with some functional improvements. In addition, rats transplanted with fetal spinal cord cells have shown improvements in some gait parameters, and the delayed transplantation of fetal raphe cells can enhance reflexes. We transplanted neural differentiated mouse embryonic stem cells into a rat spinal cord 9 days after traumatic injury. Histological analysis 2-5 weeks later showed that transplant-derived cells survived and differentiated into astrocytes, oligodendrocytes and neurons, and migrated as far as 8 mm away from the lesion edge. Furthermore, gait analysis demonstrated that transplanted rats showed hindlimb weight support and partial hindlimb coordination not found in 'sham-operated' controls or control rats transplanted with adult mouse neocortical cells.