Balbiani ring

Aziz, J.B., N.M. Akrawi, and G.A. Nassori. 1991. The effect of chronic toxicity of copper on the activity of Balbiani rings and nucleolar organizing region in the salivary gland chromosomes of Chironomus ninevah larvae. Environ. Pollut. 69 125-130. 

Lamb, M.M. and Daneholt, B. (1979) Characterization of active transcription units in Balbiani rings of Chironomus tentans. Cell. 17(4), 835-848. 

Singh, O.P., Bjorkroth, B., Masich, S., Wieslander, L. and Daneholt, B. (1999) The intranuclear movement of Balbiani ring pre-messenger ribonucleoprotein particle. Exp. Cell Res., 251, 135-146. 

Grossbach, E. R., Bjorkroth, B., and Daneholt, B. (1990). Presence of histone HI on an active Balbiani ring gene. Cell (Cambridge, Mass.) 60, 78-83. 

Trepte, H. H. (1993). Ultrastructural analyrsis of Balbiani ring genes of Chironomus pallidivittatus in different states of Balbiani ring activity. Chromosoma 102, 433-445. 

Visa. N., Izaurralde, E., Ferreira, J.. Daneholt, B., and Mattaj, I. W. (1996). A nuclear cap-binding complex binds Balbiani ring pre-mRNA cotranscriptionally and accompanies the ribonucleoprotein particle during nuclear export. J. Cell Biol. 133(1), 5-14. 

Fig. 9. The RNP granules in the Balbiani rings of the Chironomus salivary gland. A. the region of a Balbiani ring numerous particles are visible B., C. the particles in the region of chromosome one can see the joining strands between the particles and chromatin material D. E. the particles moving across the pores of the nuclear membrane. A, X22,500 B, X49,500 C to E, X90,000. (From Stevens and Swift. 1966. J. Cell Biol., 31 55-77.)...

The first observations in situ of complexes containing D-RNA were made by Beermann and Bahr (1954) (see also Beermann and Clever, 1964), who found by electron microscopy a special type of granule in the nuclei of the salivary glands of Chironomus, These particles are about 400 A in diameter. They are accumulated in the region of Balbiani rings, which are the sites of intensive synthesis of mRNA that presumably serves as templates for the production of salivary proteins (Beermann, 1961). It is important to... 

Some support for this idea may be found in electron microscopic observations. Usually the structures described as D-RNP are observed directly in the area of active RNA synthesis in the chromosomes. Thus the Beermann particles at first appear in Balbiani rings engaged in the production of D-RNA. The perichromatin and interchromatin granules are also sometimes observed in contact with chromosomal masses, with which they are connected by 30A strands. Finally, the helical structures described in Amoeba, which are presumably also D-RNP, grow from a central axis that probably corresponds to a DNP strand. Of course, these observations are indirect, but they are quite compatible with the view that the ribonucleoprotein complex is formed immediately after the synthesis of D-RNA, even before completion of the RNA chain. 

Beermann, W. 1961. Bin Balbiani-ring als locus einer speicheldrusen-mutation. Chromosoma, 12 1-25. 

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