Skip Navigation

American Zoologist 1966 6(1):33-41; doi:10.1093/icb/6.1.33
© 1966 by The Society for Integrative and Comparative Biology
This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrow Request Permissions
Google Scholar
Right arrow Articles by CLEVER, U.
Right arrow Search for Related Content
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

Gene Activity Patterns and Cellular Differentiation

ULRICH CLEVER
Department of Biological Sciences, Purdue University Lafayette, Indiana

Puffing in giant chromosomes ot Diptera is considered to reflect the pattern of active gene loci in these chromosomes. In any one tissue only a relatively small portion of the total bands (about 10 to 20%) have been observed to form a puff at some time or another in larval development. These patterns of "potentially active" loci are tissue specific, though greatly overlapping. The actual rate of activity at these loci is controlled independently of each other and independently in each tissue by factors of the extranuclear metabolism. Puffing at some loci seems to be related to specific cellular functions, such as secretion of the salivary glands. The activity of others may be related to more basic metabolic processes. In relation to larval development, puffing patterns may change with changing cell functions or with developmental processes in the cells themselves. In salivary glands ofChironomus activity of DNAase and of acid phosphatase seems to change in relation to cell breakdown at the end of the pupal molt. Changes of acid phosphatase activity begin early in the last larval ins tar, but the enzyme is bound to lysosomes until metamorphosis. This suggests that the genes specifically active during metamorphosis have to interact with a longterm control-system of development. The induction of metamorphosis is a sequential process, gene activations being among the first steps in this sequence. The activation of these genes by ecdysone is independent of protein synthesis. It is only the reaction of these genes that leads to the subsequent events in the cell, including the subsequent puff activations. This is shown by the fact that they depend on early RNA synthesis as well as on protein synthesis. These results on puffing are discussed with regard to the general problem of the relationships between patterns of gene activity and differentiation.


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?




Disclaimer:
Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.