ISSN:
1432-0886
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Abstract The ultrastructural distribution of small nuclear ribonucleoproteins (U1-snRNP and Sm antigen) in the nucleus ofChironomus salivary gland cells was investigated by means of specific antibodies and immunocytochemistry using colloidal gold complexes as markers. Particular attention was paid to the structural relationships of snRNPs with transcriptionally active areas in polytene chromosomes and with Balbiani ring granules. Our results demonstrate strong binding of anti-snRNP antibodies to RNP fibrils or the fibrillar network occurring within nuclear regions active in transcription (Balbiani rings or minor puffs). This confirms data reported previously on mammalian cells showing early association of snRNPs with nuclear fibrillar constituents containing newly synthesized pre-mRNA. In addition, Balbiani ring granules in the process of formation at the transcriptionally active sites were sometimes labeled on their periphery or on the transitory part between the granule and its precursor RNP fibril, while free granules observed in the nucleoplasm were virtually devoid of label. These findings suggest that mRNA processing, including splicing, takes place prior to the formation of mature Balbiani ring granules.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01737288
