Constitutive heterochromatin in mouse chromosomes treated with typsin

PROTEIN PROFILES OF FLAX GENOTROPHS

Protein profiles of partially purified protein extracts from main stem tissue of Durrant's L and S flax (Linum usitatissimum L.) genotrophs were examined with one and two dimensional electrophoresis on acrylamide gels. The purification retained mainly glycoproteins. Among this reduced spectrum of plant proteins, some of the proteins separated had relative mobility (Rm) shifts between L and S. For two proteins, the Rm shifts were demonstrated in two-dimensional separations using mixtures of the L and S extracts. The Rm shifts were all in the same direction, the S protein ran slightly slower than the corresponding L protein, in both dimensions. This shift direction agreed with previous studies on Rm shifts with peroxidase and esterase isozymes and with similar shifts in acid phosphatase isozymes.

HOMOEOLOGOUS CHROMATIN EXCHANGE IN A RADIATION-INDUCED GENE TRANSFER

Some of the ionizing-radiation-induced translocations between alien and wheat chromosomes show no deleterious effects and are transmitted normally through the pollen. Translocations of this type will be called "compensating". In one such compensating translocation, designated T4, a segment of Agropyron elongatum (Host.) P.B. chromosome 7el1 with gene Lr19 controlling resistance to leaf rust was transferred into wheat chromosome 7D. The T4 translocation was found to have involved chromosome arms 7el1α and 7DL. The pairing relationships of Agropyron telosome 7Eα with telosomes 7AL, 7BL, 7DS and 7el1α was studied in wheat-Aegilops speltoides Tausch. hybrids. The 7Eα telosome paired with 7DS and, therefore, is homoeologous with it. It did not pair with 7AL, 7BL, and 7el1α. Hence 7AL, 7BL, 7DL, 7el1α must be homoeologous. Consequently, chromatin in the long arm of chromosome 7D was replaced with homoeologous chromatin of the Agropyron chromosome in the T4 translocation.