Das Wandern des Aktivit�tsmaximums im BR4-Locus vonAcricotopus lucidus als Modell f�r die Wirkungsweise eines komplexen Locus

Developmental puffing activity in the salivary gland and Malpighian tubule chromosomes ofAcricotopus lucidus (Diptera, Chironomidae)

“…The sequence of developmental changes in activity can be seen especially well in the apparent migration of the puff maximum along the BR 4 region (from distal to proximal) described by Mechelke (1961). The migration comes about by the sequential, asynchronous and synchronous, inactivation and activation of loci lying closely together but separated by inactive bands.…”

“…10c, d). The activation of 4(E 25, 27), after the regression of BR 4 and after the delayed regression of 4(E 31-35) (located near the BR 4 locus, disrupted by the Balbiani ring and only visible in autoradiograms or in chromosomal mutations in which BR 4 and 4(E 31-35) have been separated), and its regression, together with the activation and regression of 4(E 17), gives the appearance of migration of the puff along the BR 4 region (Mechelke 1961 ; Fig. 10a-f).…”

“…As a prerequisite for this, exact cytological chromosome maps were necessary. Only a few chromosome sections of A. lucidus had been published with a band designation (Mechelke 1960(Mechelke , 1961(Mechelke , 1963(Mechelke , 1967Panitz 1964Panitz , 1965, therefore, as a basis for the puffing analysis, exact maps of the three salivary gland chromosomes of A. lucidus were drawn.…”