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Cytogenetic Studies of Neurospora crassa


Singleton, Jesse Robertson (1948) Cytogenetic Studies of Neurospora crassa. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/SK7K-FX44.


The literature pertinent to the nuclear cycle in the life history of Neurospora is reviewed. A description of methods used in the cytological studies is presented, and the most useful are summarized as schedules of treatment. The morphology of the mitotic and pachytene chromosomes of N. crassa is described and diagrammed. The chromosome cycle in the developing ascus is described in detail, and special points of interest are discussed. The cytological basis of spore abortion caused by the presence in the ascus, in the homozygous condition, of genes from the Abbott strains is discussed briefly. Five translocations, three previously found by McClintock (1945) and two others found by the writer, are described and tentatively identified as to the chromosomes involved. From a consideration of the consequences of crossing-over and disjunction in the translocation heterozygote, equations are derived by means of which the frequencies of the various types of exchange and disjunction can be calculated or estimated. Non-random segregation in T4637 following an effective exchange in a single interstitial segment is described, and a possible mechanism suggested.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:(Genetics and Embryology)
Degree Grantor:California Institute of Technology
Major Option:Biology
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Unknown, Unknown
Thesis Committee:
  • Unknown, Unknown
Defense Date:1 January 1948
Record Number:CaltechETD:etd-08042006-130929
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:3008
Deposited By: Imported from ETD-db
Deposited On:09 Aug 2006
Last Modified:22 Mar 2023 19:26

Thesis Files

PDF (Sinleton_jr_1948.pdf) - Final Version
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