Cloning of the homeotic Sex combs reduced gene in Drosophila and in situ localization of its transcripts (original) (raw)
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The EMBO Journal, 1985
We have extended our 'chromosomal walk' in the Antennapedia-complex (ANT-C) by isolating overlapping DNA sequences spanning the chromosomal segment between Antennapedia (Antp) and Deformed (Dfd). The transcription units, homeoboxes and M-repeats were mapped within this region. Four transcription units Antp, fushi tarazu (ftz), Sex combs reduced (Scr) and Dfd contain both a homeobox and an M repeat, whereas at least two additional transcription units, x and z, were found to lack these elements. The Scr locus was identified by deletion mapping. It consists of at least two exonic regions separated by a large intron. The homeobox is located in the 3' exon and is 82% homologous to the one in Antp. Scr encodes a major 3.9-kb RNA. A corresponding cDNA clone was used as a probe for in situ hybridization to sections of various embryonic stages. At gastrula stages Scr+ transcripts accumulate in the posterior head and the anterior thoracic region of the germ band. At later stages a strong accumulation of transcripts is observed in the suboesophageal and the prothoracic ganglion of the ventral nervous system. Key words: Drosophila/homeotic genes/Sex combs reduced/cloning/homeobox The homeotic gene Sex combs reduced (Scr) is a member of the ANT-C. Scrmutants show a reduction in the number of sex comb teeth on the male foreleg, which represents a partial transformation of the first to the second thoracic segment, and a partial transformation of the labial palps into maxillary palps (Lewis et al., 1980a, 1980b). The same segmental transformations, prothorax to mesothorax and labial to maxillary, are also found in homozygous Scrembryos (Struhl, 1983; Wakimoto and Kaufman, 1981). Genetic and molecular mapping of Scr has given ambiguous results since some of the mutants appear to map to the right offtz and some to the left, towards the centromere (Hazelrigg and Kaufman, 1983; Scott et al., 1983). Multiple sex combs (In(3)Msc1) appears to be a dominant allele of Scr, since hemizygous In(3)Msc1/Df(3R)Scr animals have the same phenotype as Scrhomozygotes. However, in addition to having a reduced number of sex comb teeth on the foreleg, In (3R)Mscl/+ males also carry a small number of sex comb teeth on the second legs, indicating a partial transformation in the opposite direction, i.e., from mesoto prothorax. In earlier reports (Garber et al., 1983; Kuroiwa et al., 1984) we have described the cloning of the distal part of the ANT-C including the Humeral (Hu), Antp and ftz loci. Here we report the cloning and molecular analysis of the region between Antp and Deformed (Dfd) with particular emphasis on the Scr locus. As expected, Scr contains a homeobox which is a small highly conserved DNA segment characteristic for homeotic genes and other controlling genes involved in the spatial organization of the embryo (McGinnis et al., 1984a, 1984b; Scott and Weiner, 1984; Gehring, 1985). The Scr+ transcripts are localized in those regions of the embryo which are affected in Scrmutants.
Genetics, 2009
The Drosophila Hox gene, Sex combs reduced (Scr), is required for patterning the larval and adult, labial and prothoracic segments. Fifteen Scr alleles were sequenced and the phenotypes analyzed in detail. Six null alleles were nonsense mutations (Scr 2 , Scr 4 , Scr 11 , Scr 13 , Scr 13A , and Scr 16) and one was an intragenic deletion (Scr 17). Five hypomorphic alleles were missense mutations (Scr 1 , Scr 3 , Scr 5 , Scr 6 , and Scr 8) and one was a small protein deletion (Scr 15). Protein sequence changes were found in four of the five highly conserved domains of SCR: the DYTQL motif (Scr 15), YPWM motif (Scr 3), Homeodomain (Scr 1), and C-terminal domain (CTD) (Scr 6), indicating importance for SCR function. Analysis of the pleiotropy of viable Scr alleles for the formation of pseudotracheae suggests that the DYTQL motif and the CTD mediate a genetic interaction with proboscipedia. One allele Scr 14 , a missense allele in the conserved octapeptide, was an antimorphic allele that exhibited three interesting genetic properties. First, Scr 14 /Df had the same phenotype as Scr 1 /Df. Second, the ability of the Scr 14 allele to interact intragenetically with Scr alleles mapped to the first 82 amino acids of SCR, which contains the octapeptide motif. Third, Scr 6 , which has two missense changes in the CTD, did not interact genetically with Scr 14 .
Genetics, 2009
The Drosophila Hox gene, Sex combs reduced (Scr), is required for patterning the larval and adult, labial and prothoracic segments. Fifteen Scr alleles were sequenced and the phenotypes analyzed in detail. Six null alleles were nonsense mutations (Scr 2 , Scr 4 , Scr 11 , Scr 13 , Scr 13A , and Scr 16) and one was an intragenic deletion (Scr 17). Five hypomorphic alleles were missense mutations (Scr 1 , Scr 3 , Scr 5 , Scr 6 , and Scr 8) and one was a small protein deletion (Scr 15). Protein sequence changes were found in four of the five highly conserved domains of SCR: the DYTQL motif (Scr 15), YPWM motif (Scr 3), Homeodomain (Scr 1), and C-terminal domain (CTD) (Scr 6), indicating importance for SCR function. Analysis of the pleiotropy of viable Scr alleles for the formation of pseudotracheae suggests that the DYTQL motif and the CTD mediate a genetic interaction with proboscipedia. One allele Scr 14 , a missense allele in the conserved octapeptide, was an antimorphic allele that exhibited three interesting genetic properties. First, Scr 14 /Df had the same phenotype as Scr 1 /Df. Second, the ability of the Scr 14 allele to interact intragenetically with Scr alleles mapped to the first 82 amino acids of SCR, which contains the octapeptide motif. Third, Scr 6 , which has two missense changes in the CTD, did not interact genetically with Scr 14 .
The EMBO journal, 1985
We report the isolation and characterization of caudal (cad), a previously unknown Drosophila homeo box-containing gene from the 38E region on the left arm of the second chromosome. This homeo box has diverged from the prototype sequence in Antennapedia, but contains subregions which are highly homologous. By Northern analysis and in situ hybridization experiments two transcripts of 2.4 kb were found to accumulate in nurse cells and in the oocyte during oogenesis. These transcripts generate a transient concentration gradient along the antero-posterior axis at the syncytial blastoderm stage. At the cellular blastoderm stage transcripts accumulate in a single band from 13-19% egg length at the posterior end. One zygotic transcript of 2.6 kb is detected. At later stages this transcript is localized in ectodermally and endodermally derived tissues such as the proctodeum, the Malpighian tubules and the posterior midgut. The 2.6-kb transcript is detectable until the onset of metamorphosis.
Development (Cambridge, England), 1990
The homeotic genes of Drosophila control the differentiation of segments during development. Mutations in these genes cause one or more segments to develop structures normally found elsewhere in the organism. Several studies have shown that the spatial patterns of homeotic gene transcription are highly complex, and that these precise patterns of transcription are critical to normal development. The homeotic gene Antennapedia (Antp), a member of the Antennapedia Complex, is required for the correct differentiation of thoracic segments in both embryos and adults. The patterns of total Antp transcript and protein accumulation have been described in detail, but the contribution of each promoter to the overall pattern in embryos has not been reported. We have examined in detail the spatial distribution of transcripts from each of the Antp promoters in both embryo sections and whole embryos by in situ hybridization using promoter-specific probes. We show that the transcripts from each of ...
Biology of the Cell, 2005
Background information. The Pc-G (Polycomb group) and trx-G (trithorax group) genes play a key role in the regulation of the homoeotic genes. The homoeotic gene Scr (Sex combs reduced) contained in the Antennapedia complex specifies segmental identity of the labial and prothoracic segments in Drosophila. Regulation of Scr requires the action of different enhancer elements spread over several kilobases. We previously identified an HMGB (high mobility group)-like protein DSP1 (dorsal switch protein 1), which works like a trx-G protein for the normal Scr expression.
The EMBO journal, 1994
Each of the homeotic genes of the HOM or HOX complexes is expressed in a limited domain along the anterior-posterior axis. Each homeotic protein directs the formation of characteristic structures, such as wings or ribs. In flies, when a heat shock-inducible homeotic gene is used to produce a homeotic protein in all cells of the embryo, only some cells respond by altering their fates. We have identified genes that limit where the homeotic gene Sex combs reduced (Scr) can affect cell fates in the Drosophila embryo. In the abdominal cuticle Scr is prevented from inducing prothoracic structures by the three bithorax complex (BX-C) homeotic genes. However, two of the BX-C homeotic genes, Ultrabithorax (Ubx) and abdominal-A (abd-A), have no effect on the ability of Scr to direct the formation of salivary glands. Instead, salivary gland induction by Scr is limited in the trunk by the homeotic gene teashirt (tsh) and in the last abdominal segment by the third BX-C gene, Abdominal-B (AbdB). ...
Development (Cambridge, England), 1988
The distributions of the products of the homeotic genes Sex combs reduced (Scr) and Ultrabithorax (Ubx) and of the segmentation genes, fushi tarazu (ftz), even skipped (eve) and engrailed (en) have been monitored in polyhomeotic (ph) mutant embryos. None of the genes monitored show abnormal expression at the blastoderm stage in the absence of zygotic ph expression. Both Scr and Ubx are ectopically expressed in the epidermis of ph embryos, confirming the earlier proposal, based on genetic analysis, that ph+ acts as a negative regulator of Antennapedia (ANT-C) and bithorax (BX-C) complex genes. At the shortened germ band stage, en is also ectopically expressed, mainly in the anterior region of each segment. In contrast to these effects in the epidermis, the expression of en, Ubx, Scr and ftz is largely or completely suppressed in the central nervous system, whereas eve becomes ectopically expressed in most neurones.