Neurospora crassa Genetic Maps and Mapped Loci (January, 2000)
David D. Perkins. Department of Biological Sciences, Stanford University, Stanford,
Maps. Loci are displayed only if their order is established with reasonable certainly, either from meiotic crossing over in multiple-point crosses, from duplication coverage, or by physical mapping Loci are not displayed but are listed below the maps if their order is uncertain relative to the loci that are shown, except that closely linked loci may sometimes be shown in parentheses on the map even if their relative order is unknown. Evidence for linkage is given in the lists and is referenced in the new compendium (Perkins, Radford, and Sachs 2000 Chromosomal Loci of Neurospora crassa. Academic Press). Crossover values and interval lengths are approximations. Numbers on which they are based are often small and the various stocks used for mapping differ in genes that affect meiotic recombination. Linkage group I is estimated to be at least 200 map units long and the total for all seven groups probably exceeds 1000.
Rearrangement breakpoints are shown only if their map position has been determined precisely. Insertional and quasiterminal rearrangements are usually the best mapped. Many of these duplication-generating rearrangements have been instrumental in determining the order of flanking gene loci by means of duplication-coverage tests. When a rearrangement involves more than one break in the same chromosome, the breakpoints are distinguished by superscripts L (left), R (right), or M (middle). Symbols for rearrangements with quasiterminal breakpoints are shown below the relevant linkage-group tip. Rearrangement symbols are abbreviated. For example, T(IL®IIR)39311 is shortened to T(39311). Full symbols can be found in the FGSC Stock List or in Perkins, D. D., Advan. Genet. 36:239-398 (1997), where descriptions and linkage relations of 355 chromosome rearrangements are given.
Lists: Accompanying the map of each linkage group is a list of all the loci known with reasonable certainty to be located in that group. These are ordered alphabetically by locus symbol. Neither the maps nor the lists include anonymous RFLP and RAPD markers. Recombination percentages and numerical fractions are from random ascospore progeny. When data are from asci, the numbers of tetratype (T) and nonparental ditype (NPD) asci are given, together with the total number. In statements with the format "Locus c is between a, b and d, e", the word "and" separates markers to the left of c from markers to the right. If synonyms exist, only the preferred symbol is given. Names, references, synonyms, and a documented description of each locus will be found in the new compendium. Over 1000 loci have now been assigned to linkage group.
For background and references see Perkins and Barry 1977 Advan. Genet. 19:133-285, Perkins 1997 Advan. Genet. 36:239-398 (cytogenetics, chromosome rearrangements); Perkins 1986 J. Genet. 65:121-144 (mapping by duplication coverage); Perkins 1999 Fungal Genet. Newslett. 46:34-41 (genetic nomenclature),
I am grateful to colleagues who have generously contributed linkage data, and to the National Science Foundation (Grant MCB-9728675) for support.
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