The histidine locus is complex in Neurospora crassa Many mul

The histidine locus is complex in Neurospora crassa. Many multiple alleles are known, such as 245, CD-16, 430, and 261, which lack the ability to synthesize the amino acid histidine. Such strains will consequently be unable to grow on minimal medium. Provide an interpretation for the following observations involving these histidine strains of Neurospora When heterokaryons are produced (single \"cells\" containing nuclei from two different strains), the combination of strains 245 and 261 always produces growth on minimal medium, whereas the combination of strains CD-16 and 245 never produces growth on minimal medium. When strain 430 is crossed with strain 261, rare ascospores are produced, which can grow on minimal medium

Solution

(a) the inference explains that strain 261 is able to synthesize histidine synergistically with strain 245. It also poves that the strain 245 can work synergistically only with the strain 261, not with strain CD-16.

(b) strain 261 has an ability to work in sync with other strains so as to facilitate growth on minimal medium