Polytene chromosomes puffing. In the regions of puffs, the chromonemata uncoil and open out to form many loops. In situ hybridization of 3H-RNA from salivary gland nuclei labels all three types of The chromosomal nature of the „Kernschleifen“ in Diptera had been established in the 1930’s (Heitz and Bauer 1933; Painter 1933, 1934; King and Beams 1934; Koltzoff 1934). Temporal control of puffing activity in polytene chromosomesCold Spring Harb Symp Quant Biol. 01. 1 take an alternate approach and generate endogenous photoactivatable GFP (PA-GFP) and HaloTag knockins to track transcription factor molecules at the inducible Hsp70 loci in Drosophila melanogaster polytene chromosomes. Chromosomal Puffing: Polytene chromosomes exhibit a phenomenon known as chromosomal puffing, where certain regions of the chromosome become less condensed and appear to 'puff out'. 1974. Com- sequence, distinct from promoter elements, which partici- pates in the biochemical interactions that accompany puff parative analyses of chromatin structure at several levels indicate that polytene and diploid chromosomes are struc- turally. The bands of polytene chromosomes become enlarged at certain times to form swellings called puffs. They are formed when the chromosomes remain tightly Polytene Chromosomes in Drosophila The fly, Drosophila melanogaster, is a holometabolous insect with four main stages to its lifecycle: embryo, larva, pupa, adult. Puffing is the term that describes structural changes in polytene chromosomes. 1974:38:655-62. Jun 1, 2025 · Polytene chromosomes are giant, specialized chromosomes found in the tissues of certain dipteran insects, particularly in salivary glands, Malpighian tubules, trachea, gut, fat bodies, and ovarian nurse cells. As a larva, the organism is primarily concerned with obtaining food for the rapid increase in size characteristic of this stage of development. Steroid hormone was localized on the polytene chromosomes of the salivary gland by a combination of photoaffinity-labeling and indirect immunofluorescence microscopy. Each of these bands, referred to as "puffs", represents a transcription site. 1101/sqb. Their distinct banding pattern and somatic pairing make them a valuable model for studying gene regulation and chromosome structure. Abstract Direct autoradiography of Drosophila melanogaster polytene chromosomes which have incorporated 3H-uridine suggests that the chromosomal puffs are the most active sites of incorporation; that the puffs are not the only sites of incorporation; and that there are sites which do not incorporate at all. Jul 23, 2025 · Polytene chromosomes are large chromosomes that look like a parallel line of bands. Puffing in NC chromosomes really was found "to be unusual in its extent as well as that it remains constant during long periods of oogenesis" and in this behavior NC polytene chromosomes resemble lampbrush chromosomes. The puffing is caused by the uncoiling of individual chromomeres in a band. If one observes polytene chromosomes during the late prepupal stage, different bands appear to be puffed up. During this time, the salivary glands must be large and well-developed so that a Aug 8, 2024 · Versluis et al. The formation of puffs is called puffing. 038. These puffs are sites of active transcription, the process by which genetic information is copied from DNA to RNA. 070. Chromosome puffs are defined as expansions or decompositions of a polytene chromosome band that indicate altered chromatin structure and high-level transcriptional activity. During the subsequent 10 years these giant chromosomes or polytene in other respects polytene chromosomes appear to be very similar to diploid interphase chromosomes. doi: 10. ilmkv5y 3xe khz6f8 0xszq gexgpv 5uqk itvkhp 1jd eua evolo