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Alternate processing patterns of myosin heavy chain RNA during Drosophila development
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161 DIFFERENT CARBOXY-TERMINAL AMINO ACID SEQUENCES RESULT FROM DEVELOPMENTAL VARIATIONS IN THE SPLICING PATTEPN Or TRANSCRIPTS FROM THE DROSOPHILA MYOSIN ALKALI LIGHT CHAIN GENE. S. Falkenthal Denartment of Genetics, The Ohio State University, Columbus, Ohio, 43210. By sequence comparisons with a myosin alkali light chain (MLC-ALK) ~ N A clone and by $1 nuclease analyses, the pattern of introns and exons within the MLC-ALK gene has been deduced. In the 3' half of the gene, there M e two alternative splicin~ patterns which result ~ mRNAs that translate to Rive proteins with two alternative 14 amino acid carboxyterminal sequences. There is develoDmental~ulation of the selection of the above splicing sites. One splicing pattern produces an mRNA which translates into a protein used for both larval and adult musculature, whereas the other splicing nattern is used for the latter stage only.
ALTERNATE PROCESSING PATTERNS OF MYOSIN H E A V Y CHAIN RNA DURING DROSOPHILA DEVELOPMENT. S.I.Bernstein, D.R.Wassenberg II, K.D.Becker and L.Roche. Dept. of Biology and Molecular Biology Inst.,San Diego State Univ., San Diego, CA 92182 USA Drosophila has a single gene encoding myosin heavy chain (MHC) which is expressed during both larval and adult muscle development (Bernstein et al., Nature 302:393,1983; Rozek and Davidson, Cell 32: 23, 1983)~ Transcripts of 7.2 and 8.0 kb accumulate during larval myogenesis while transcripts of 7.2,8.0 and 8.6 kb accumulate during metamorphosis. We have found that alternate 3' ends are spliced to the coding region of the MHC message. The three resulting transcripts apparently encode MHC isoforms with different C-termini. The C-terminal of the MHC protein may play a role in stage- and tissue-specific contractile apparatus assembly and/or function. (Research supported by NIH grant GM32443 to S.I.B.)
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163 A SERICIN GENE OF BOMBYX MORI PRODUCES MULTIPLE TRANSCRIPTS UNDER DEVELOPMENTAL REGULATION PROGRAM. Y. Hamada and Y. Suzuki. Natl. Inst. Basic Biol., Myodaiji, Okazaki city. 444 lapan. Two possible allelic genes complementary to 10.0kb mRNA abundant in the middle silk gland have been isolated. It has been shown that the middle gland contains three transcripts 9.0, 4.0 and 2.7kb long besides the 10.0kb mRNA. They are all hybridizable with a DNA segment coding for the first exon. The I0.0, 9.0 and 2.7kb transcripts are produced only in fifth instar larva. The 4.0kb transcript is produced even at earlier stages. Genomic Southern blot analyses using the first or third exon DNA showed that in Bombyx mori genome there is only one single sequence corresponding to the cloned DNA. Northern blot analyses showed that all these four transcripts have the sequence corresponding to the fifth exon as well as the first exon, but the 9.0 and 2.7kb transcripts lack the third exon sequence. These results suggest that multiple transcripts are produced from a single gene via stage-specific RNA processing.
RNA PROBES TO DEVELOPMENTALLY REGULATED MUSCLE GENES. J.R. Coleman and C.P. Ordahl; Division of Biology and Medicine, Brown University, Providence, RI 02912 (JRC) and Department of Anatomy, UCSF, San Francisco, CA 94143 (CP0), USA. Sequencesfrom cDNA clones coding for chicken muscle proteins have been inserted into vectors containing the bacteriophage promoter SP6 and transcribed to generate 32p_ and 3H-labelled RNA probes of high specific activity for use in RNA blot and in situ hybridization analyses. Sequences used include the 3'-untranslated end of skeletal ~-actin (260 bp), the 3'-untranslated end of cardiac troponin T (140 bp), and a coding sequence from the 5' end of M-creatine kinase (240 bp). Sequences were inserted into vectors in both orientations and transcripts made of both DNA strands. Blot analyses using poly(A)+ RNA demonstrate that all three genes are activated during skeletal muscle cell differentiation i__n_novoCardiac troponin T expression ceases in skeletal muscle as development progresses, but continues in cardiac muscle, l__nn situ hybridization analyses of the cellular pattern of gene expression during skeletal muscle differentiation in vitro, are in progress (NIH GM-32018)
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161 DIFFERENT CARBOXY-TERMINAL AMINO ACID SEQUENCES RESULT FROM DEVELOPMENTAL VARIATIONS IN THE SPLICING PATTEPN Or TRANSCRIPTS FROM THE DROSOPHILA MYOSIN ALKALI LIGHT CHAIN GENE. S. Falkenthal Denartment of Genetics, The Ohio State University, Columbus, Ohio, 43210. By sequence comparisons with a myosin alkali light chain (MLC-ALK) ~ N A clone and by $1 nuclease analyses, the pattern of introns and exons within the MLC-ALK gene has been deduced. In the 3' half of the gene, there M e two alternative splicin~ patterns which result ~ mRNAs that translate to Rive proteins with two alternative 14 amino acid carboxyterminal sequences. There is develoDmental~ulation of the selection of the above splicing sites. One splicing pattern produces an mRNA which translates into a protein used for both larval and adult musculature, whereas the other splicing nattern is used for the latter stage only.
ALTERNATE PROCESSING PATTERNS OF MYOSIN H E A V Y CHAIN RNA DURING DROSOPHILA DEVELOPMENT. S.I.Bernstein, D.R.Wassenberg II, K.D.Becker and L.Roche. Dept. of Biology and Molecular Biology Inst.,San Diego State Univ., San Diego, CA 92182 USA Drosophila has a single gene encoding myosin heavy chain (MHC) which is expressed during both larval and adult muscle development (Bernstein et al., Nature 302:393,1983; Rozek and Davidson, Cell 32: 23, 1983)~ Transcripts of 7.2 and 8.0 kb accumulate during larval myogenesis while transcripts of 7.2,8.0 and 8.6 kb accumulate during metamorphosis. We have found that alternate 3' ends are spliced to the coding region of the MHC message. The three resulting transcripts apparently encode MHC isoforms with different C-termini. The C-terminal of the MHC protein may play a role in stage- and tissue-specific contractile apparatus assembly and/or function. (Research supported by NIH grant GM32443 to S.I.B.)
162
163 A SERICIN GENE OF BOMBYX MORI PRODUCES MULTIPLE TRANSCRIPTS UNDER DEVELOPMENTAL REGULATION PROGRAM. Y. Hamada and Y. Suzuki. Natl. Inst. Basic Biol., Myodaiji, Okazaki city. 444 lapan. Two possible allelic genes complementary to 10.0kb mRNA abundant in the middle silk gland have been isolated. It has been shown that the middle gland contains three transcripts 9.0, 4.0 and 2.7kb long besides the 10.0kb mRNA. They are all hybridizable with a DNA segment coding for the first exon. The I0.0, 9.0 and 2.7kb transcripts are produced only in fifth instar larva. The 4.0kb transcript is produced even at earlier stages. Genomic Southern blot analyses using the first or third exon DNA showed that in Bombyx mori genome there is only one single sequence corresponding to the cloned DNA. Northern blot analyses showed that all these four transcripts have the sequence corresponding to the fifth exon as well as the first exon, but the 9.0 and 2.7kb transcripts lack the third exon sequence. These results suggest that multiple transcripts are produced from a single gene via stage-specific RNA processing.
RNA PROBES TO DEVELOPMENTALLY REGULATED MUSCLE GENES. J.R. Coleman and C.P. Ordahl; Division of Biology and Medicine, Brown University, Providence, RI 02912 (JRC) and Department of Anatomy, UCSF, San Francisco, CA 94143 (CP0), USA. Sequencesfrom cDNA clones coding for chicken muscle proteins have been inserted into vectors containing the bacteriophage promoter SP6 and transcribed to generate 32p_ and 3H-labelled RNA probes of high specific activity for use in RNA blot and in situ hybridization analyses. Sequences used include the 3'-untranslated end of skeletal ~-actin (260 bp), the 3'-untranslated end of cardiac troponin T (140 bp), and a coding sequence from the 5' end of M-creatine kinase (240 bp). Sequences were inserted into vectors in both orientations and transcripts made of both DNA strands. Blot analyses using poly(A)+ RNA demonstrate that all three genes are activated during skeletal muscle cell differentiation i__n_novoCardiac troponin T expression ceases in skeletal muscle as development progresses, but continues in cardiac muscle, l__nn situ hybridization analyses of the cellular pattern of gene expression during skeletal muscle differentiation in vitro, are in progress (NIH GM-32018)
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