A novel type of gene interaction in D. melanogaster.

The genes interact according to classical mechanisms, namely, complementation, modification, polymery, and epistasis, in the cells and organisms carrying these genes. Here we describe a novel type of gene interaction when the interacting genes reside in parents, whereas the interaction event takes place in their progenies lacking these genes. The conditional mutations in the D.

Conditional mutations in Drosophila melanogaster: On the occasion of the 150th anniversary of G. Mendel's report in Brünn.

The basis for modern genetics was laid by Gregor Mendel. He proposed that traits belonging to the intraspecific variability class be studied. However, individuals of one species possess traits of another class.

[Parental effects of conditional mutations and their explanations].

A study of the properties of conditional dominant and recessive lethals in Drosophila melanogaster has demonstrated parental effects in the inheritance and manifestation of these mutations. Maternal and paternal effects are present when conditional mutations interact with (1) one another, (2) the Y chromosome, or (3) chromosomal rearrangements, as well as (4) when the visual expression of a conditional mutation is inherited or (5) during the formation ofmorphoses (monstrosities) in mutant offspring. The maternal and paternal effects do not exclude one another: the same mutation can display both patterns.

[Changes in the energy status of Drosophila as a result of genetic mutation].

Conditional dominant lethals (CDL) represent a special class of genetic mutations observed in Drosophila. Mutation manifests as a dominant allele in one genotype, but lethality is not expressed in another genotype. CDL mutants exhibit a set of traits discriminating them from classic mutations.

[Conditional lethal mutations shift the genome from stability to instability].

The phenomenology of genomic destabilization is described in Drosophila melanogaster mutants containing radiation-induced conditional dominant lethals in the X chromosome and in autosome 2. Destabilization manifests itself as (1) the loss or decrease of lethality of previously lethal mutations; (2) the loss of expression of visible dominant mutations in an opposite homolog; (3) chromosomal instability resulting in the loss of the X chromosome in germline and somatic cells; (4) the occurrence of novel mutations (secondary mutagenesis); (5) the occurrence of single and mass modifications; (6) disturbances in individual development (formation of morphoses). The key event for the shift of the genome from the stable state into the unstable one is the occurrence of a conditional dominant lethal mutation.