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X Chromosome of Drosophila Melanogaster Copyright 0 1992 by the Genetics Society of America Genetic and Developmental Analysisof Polytene Section 17 of the X Chromosome of Drosophila melanogaster Daniel F. Eberl,*" Lizabeth A. Perkins: Marcy En elstein: Arthur J. Hilliker* and Norbert Perrimon *Department of Molecular Biology and Genetics, University of Guelph, Guelph, Ontario, CanadaNlG 2W1,and ?Department of Genetics and Howard Hughes Medical Institute, Harvard Medical School, Boston, Massachusetts 021 15 Manuscript received April 22, 199 1 Accepted for publication November 22, 1991 ABSTRACT Polytene section 17 of the X chromosome of Drosophila melanogaster, previously known to contain six putative lethal complementation groups important in oogenesis and embryogenesis, has here been further characterized genetically and developmentally. We constructed fcl'Y, a duplication of this region, which allowed us to conduct mutagenesis screens specific for the region and to perform complementation analyses (previously not possible). We recovered 67 new lethal mutations which defined 15 complementation groups within Df (l)N19which deletes most of polytene section 17. The zygotic lethal phenotypes of these and preexisting mutations within polytene section 17 were exam- ined, and their maternal requirements were analysedin homozygous germline clonesusing the dominant female sterile technique. We present evidence that an additional gene, which produces two developmentally regulated transcripts, is located in this region and is involved in embryogenesis, although no mutations in this gene were identified. In this interval of 37 to 43 polytene chromosome bands we have defined 17 genes, 12 (7 1%)of which are of significance to oogenesis or embryogenesis. HE X chromosome is the most extensively char- contains six putative complementation groups impor- T acterized portion of the genome of the model tant in the regulation of oogenesis or embryogenesis, higher eukaryote, Drosophilamelanogaster. It com- namely, unpaired(upd), porcupine (porc), foreclosed prises about 20% of the nuclear genome and deficien- cfcl),fused vu),phantom (phm),and exocephalon (exo) cies are available for about 77% (estimated from WIES- (NUSSLEIN-VOLHARDand WIESCHAUS 1980; WIES- CHAUS, NUSSLEIN-VOLHARDand JURGENS 1984) and CHAUS, NUSSLEIN-VOLHARDandJURcENs 1984; EBERL duplications are available for approximately 68% (es- and HILLIKER1988; PERRIMON,ENCSTROM and MA- timated from EBERLand HILLIKER1988) of the eu- HOWALD 1989), as well as one cloned DNA sequence chromatic portion of the X chromosome. Euchromatin containing a pair of alternative transcripts which show constitutes about 50% of the mitotic length of the X a highly specific developmentallyregulated pattern of chromosome and contains 99% of the X chromosome expression (NG et al. 1989). Complementation analysis gene loci (see HILLIKER,APPELS and SCHALET1980). was not possible,however, due to the lackof an The availability of X chromosome duplications and appropriate duplication. Therefore, to further char- deficiencies has been invaluable for conducting de- acterize the organization of this region we conducted tailed genetic analyses of specific segments of the X a genetic and developmental analysis of polytene sec- chromosome. Such studies have allowed usto acquire tion 17 of the X chromosome. a great deal of information on the nature of genetic organization in D. melanogaster (e.g., JUDD, SHEN and MATERIALS AND METHODS KAUFMAN1972), and have provided us withmutations Genetic strains:Flies were raised on standardDrosophila that identify gene loci that are important in a variety media at 18O , 25' or 29". Table1 lists and briefly describes of biological pathways or phenomena. Of particular the preexisting X chromosome duplications and deficiencies interest to us are genes which are important in the employed in this study. It should be noted that we present regulation of oogenesis and embryogenesis. revisedcytological descriptions for 11 of these re- Some regions of the X chromosome have not been arrangements. Preexisting lethal mutations isolated by other laboratories and fallin within the region analyzed include extensively analyzed due to the lack of appropriate 1(1)9130 and p~rcl'~~'(FERRUS et al. 1990) and ~pd'''~, duplications. The chromosomal region defined by upd'"'' and phmXEo7(WIESCHAUS, NUSSLEIN-VOLHARD and Df(l)NI9, essentially polytene section 17, is one of JURGENS 1984) and were obtained from the laboratories in these. Nevertheless, this region of the X chromosome which they were discovered. The os0, Bx, Bx' and fu muta- tions were obtained from the Bowling Green Drosophila ' Current address: Department of Biochemical Pharmacology, State Uni- Stock Center. The FM3Iw v lts/@Yy+ strain is described by versity of New York. Buffalo, New York 14260. KOMITOPOULOUet al. (1983). The X-linked dominant female Genetics 130 569-583 (March, 1992) 570 D. F. Eberl et al. TABLE 1 X chromosome deficiencies and duplications employed in this study Rearrangement Cytology References" Source of stock Df (1)os"' 17A3; 17A6' 3 A. FERRUS Df (1)o~~~'~ 17A5; 17A12 7 This work Df (W2 17A7-9; 17B2 7 This work Df (4fu" 17A3-5; 18B4-C16 1 B. LIMBOURG Df (l)N19 17A3-6; I7F2-18A3' 2 Bowling Green In(l)ClLy4R Deficient for 17A7-11; 18A3-4' 5 This work Df 17A2-7; 18B7-11' 1 B. LIMBOURG Df (I)&"' 17B3-Cl; 1 7E7-F3' 1 B. LIMBOURG Df(l)EI60.2 17B3-C1; 18A4-7' 6 W. ENGELS Df (I)EI28 Deficient for 17B3-C2; 1 8AB' 6 W. ENGELS Df (l)fuBIo 17C5-Dl; 1 8A4-76,c 1 B. LIMBOURG Df (1)fUH4 17C3; 1 7D2' 1 B. LIMBOURG Dp(l;3)JC153 16E; 17A7-12; 99D3-8' 394 M. TANOUYE Dp(1;3)fu"" 17A; 17DE 98B' 1 B. LIMBOURC Dp(l;Y)W39 Duplicated for 16F; 18A5-7 and 19E5-7 to base 7 This work (=fcl+Y)d T(l;Y)W32 16F1-4; Ys 374 M. TANOUYE T(l:Y)V7 16F1-4: Ys 3.4 M. TANOUYE 1, BUSSONet al. 1988; 2, CRAYMERand ROY 1980; 3, FERRUSet al. 1990; 4, TANOUYE,FERRUS and FUJITA1981; 5, STURTEVANTand BEADLE 1936;6, ENCEIS and PRESTON1981; 7, this work. ' The cytology of these rearrangements has been reexamined (D. F. EBERL)and the revised breakpoints are reported here. For previous descriptions of the cytology, see the additional references given. ' There is also a tandem duplication, Dp(1;1)17A; I9AB superimposed on this deficiency, such that the deficiency is present in both copies. Cytologically, Dp(l$)W39 is identical tofcl+Y in polytene chromosome squashes. sterile Fs(l)K1237 (or od') (BUSSONet al. 1983; PERRIMON 17. The mutagens employed were y-radiation, ethyl meth- 1984) was utilized for germline clone analysis (see below). anesulfonate (EMS) and 1,2:3,4-diepoxybutane (DEB). A The en-lac2 strain was obtained from C. HAMA and T. mutagenesis protocol based on that of LEWISand BACHER KORNBERG.This strain carries a ,!-galactosidase (lad)gene (1968) was used for EMS (12 and 25 mM) and DEB (10 under the control of the engrailed (en) regulatory regions mM) . on the second chromosome (HAMA,ALI and KORNBERG Complementation analysis: Complementation analyses 1990). After the blastoderm stage, the en-lac2 strain ex- were largely performed following the general procedure presses the &galactosidase protein in patterns identical to described by EBERLand HILLIKER(1988). Eachof these the endogenous en protein (HAMA,ALI and KORNBERC schemes utilized one of Dp(1 ;f)W39, Dp(1;Y)W39 (=fcl+Y), 1990). Descriptions of other genetic strains and mutations Dp(I;3)fu"' or Dp(l;3)JC153 (see Table 1). Complemen- are provided by LINDSLEYand GRELL(1 968) andLINDSLEY tation analyses involving asone genetic variant a viable Bx, and ZIMM (1985, 1987, 1990). os or& allele did not necessitate the use of an X duplication Mutagenesis: To analyze the genetic organization of the for complementation. region uncovered by Df(l)Nl9, we constructed a duplica- Cytology: Salivary gland preparations were made from tion, on the Y chromosome, of polytene section 17 of the X larvae heterozygous for specific rearrangements and cyto- chromosome. The details of the construction of this dupli- logically normal chromosomes. Salivary glands weredis- cation, fcl+Y or Dp(l;Y)W39, are reported in the RESULTS sected from third instar larvae in 45% acetic acid, trans- section and are diagrammed in Figures 1 and 2. ferred to a drop of 2% acetolacto-orcein on a siliconized A deletion encompassing a portion of section 17, slide, squashed immediately with a coverslip and examined Df(l)osUEJ9,was constructed by irradiating females hetero- using phase contrast optics. Breakpoints were determined zygous for an X chromosome marked with y c11 v f car and using the polytene X chromosome map of BRIDGES(1938). an Ore-R wild-type X chromosome. These females were Germline clone analysis: Germline clones of zygotic crossed tofos' car/Y males. Female progeny expressing the lethal mutations were generated using the dominant female os' recessive phenotype were further analyzed as putative sterile technique (PERRIMONand GANS1983; PERRIMON, deletions. Another mutation, UE69, recovered from this ENCSTROMand MAHOWALD1984, 1989; PERRIMONet al. experiment, is an allele of os-upd. 1986). Recessive lethal mutations falling within polytene section Analysis of embryonic phenotypes: Embryonic cuticles 17, as defined by Df(l)Nl9, were isolated in three different were prepared according to the HOYER'Smount technique screens diagrammed in Figure 3. Screen A (Figure 3A) of VANDER MEER (1977). The determination of the lethal involved the selection oftemperature sensitive lethals falling phase of a particular genotype was performed as described within the region defined by Df(l)Nl9. The lethal mutations
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