A new homeobox-containing gene, msh-2, is transiently expressed early during mesoderm formation of Drosophila.
Many homeobox-containing genes of Drosophila regulate pathways of differentiation. These proteins probably function as promoter- or enhancer-selective transcription factors. We have isolated a new homeobox-containing gene, msh-2, by means of the polymerase chain reactions (PCR) using redundant primers. msh-2 is specifically expressed in mesodermal primordia during a short time period early in development. It first appears at blastoderm stage just before the ventral invagination of the mesoderm and shortly after twist, a gene required for mesoderm formation, is expressed. During germband elongation all the mesodermal cells in the segmented part of the embryo express msh-2, but soon afterwards msh-2 becomes restricted to the dorsal mesoderm, which includes the primordia for the visceral musculature and the heart. Prior to muscle differentiation, msh-2 expression ceases, except for two rows of cells that will be included in the dorsal vessel. Embryos that are deficient for the chromosomal region, 93C-F, which includes the msh-2 gene, show normal mesoderm invagination and dorsal spreading. However, later in development no visceral muscle and dorsal vessel differentiation can be detected, but some skeletal muscles do form, albeit abnormally. msh-2 expression, except for a patch in the head, is dependent on twist function. On the other hand, snail, another mesoderm determinant, does not appear to be required for msh-2 initiation, but is necessary for the maintenance of msh-2 expression after germband elongation. H2.0, a homeo-box-containing gene specifically expressed in visceral mesoderm, is not transcribed in the mesoderm in 93C-F deficiency embryos.(ABSTRACT TRUNCATED AT 250 WORDS)
Bodmer
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Howard Hughes Medical Institute, San Francisco, CA.
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D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001756:Blastoderm / Q000502:physiology; D002454:Cell Differentiation / Q000502:physiology; D004330:Drosophila / Q000196:embryology / Q000235:genetics*; D015870:Gene Expression / Q000235:genetics*; D005801:Genes, Homeobox / Q000235:genetics*; D008648:Mesoderm / Q000502:physiology*; D008969:Molecular Sequence Data; D009132:Muscles / Q000196:embryology; D010641:Phenotype; D016133:Polymerase Chain Reaction / Q000379:methods