Rapid in vitro activation of corpora allata by extracted locust brain allatotropic factor

Brains of young (newly emerged) adult female locusts (Locusta migratoria migratorioides) and of mature (> 9 days old) locusts contain an extractable allatotropic factor, soluble in 100% methanol and in distilled water. This factor stimulates juvenile hormone III (JH III) synthesis and release from corpora allata (CA) that have been excised from donor locusts and then incubated with (radiolabeled methyl)-methionine in vitro in its presence. In addition to JH III, which is the major product synthesized by the CA, other hexanesoluble, radiolabeled compounds–-more polar than JH III–-are also released when CA are incubated in vitro. The activation of CA by the allatotropic factor is rapid and quickly declines when the factor is removed from the medium. Corpora allata excised from young females are marginally active and can be activated by brain allatotropic factor to less of an extent than CA of mature locusts. The content of allatotropic factor in brains of mature locusts is higher than that ascertained in brains of young females. Allatotropic factor is also present in the corpora cardiaca.     

Factors interacting with promoter region of immunoglobulin genes. Determination of the binding site boundaries

The nuclear extracts of plasmacytomas producing antibodies were found to contain factors which formed complexes with the promoter fragment of the gene for immunoglobulin kappa-chains. The corresponding complexes found in the extracts of nonlymphoid cells had a different mobility. Two approaches were proposed for determining the boundaries of the region necessary for protein factors to be bound to DNA using nuclease Ba131. A 5'-ATTTGCAT-3' octanucleotide sequence was shown to be necessary for interaction with the protein nuclear factor in the studied plasmacytoma lines. The protein completely lost its affinity if at least one nucleotide was removed or substituted at the 5'- or 3'-end of this sequence. The procedures proposed for determining the precise boundaries of the sequence necessary for protein binding to DNA do not require a preliminary protein purification. The principles on which the procedures are based, set no limitations to their application to other systems used for studying the interaction of proteins with DNA.