CROSSING OVER AND NUCLEAR PASSING IN NEUROSPORA CRASSA

Double Crossing over in Neurospora.

CROSSOVER involves exchange of genetic material between only two of the A four products of meiosis. We should like to know whether there are any special properties of these two strands of the tetrad which enable them to participate in crossing over. Such knowledge might help us understand the mechanics of the crossing over process and would perhaps shed some light on the physical nature of the ...

Non-Random Crossing over in the Second Chromosome of Neurospora Crassa.

YTOLOGICAL analysis (LINDEGREN and RUMANN, in press) has C shown that Neurospora crassa probably contains nine chromosomes. These chromosomes were found to contain respectively, 29, 18, 13, 9, 5 , 3, 3, 2, and I chromomeres; but since they were not completely uncoiled, the number of ultimate chromomeres is probably at least twice as great. They are certainly the smallest chromosomes in which cr...

Quelling in Neurospora crassa.

Heterocaryosis in Neurospora Crassa.

T IS possible by means of X-ray or ultraviolet treatment to produce mutant I strains of Neurospora crassa that are deficient in their abilities to synthesize specific vitamins, amino acids, or other essential substances (BEADLE and TATUM 1941; TATUM and BEADLE 1g4zb). It occurred to us that it might be possible to determine whether the mutant genes concerned in such haploid strains are recessiv...

Timing of nuclear division cycle in Neurospora crassa.

The timing of the nuclear division cycle in Neurospora crassa was studied by inhibiting DNA synthesis with hydroxyurea added to exponentially growing cultures at concentrations that do not inhibit cytoplasmic growth. After the addition of hydroxyurea only the nuclei that have passed the S-phase divide, and therefore by counting the increase in the average number of nuclei per hypha, the stage i...