95E;96F of Drosophila melanogaster

Making use of deficiencies, inversions and translocations, we have genetically dissected the region 95E to 96F of Drosophila melanogaster. We localized cytologically the loci abnormal spindle (asp: 385.2: 96A20-25;96B1-10) and M(3)96C2 (96C1;96C5). We have also found several new phenotypes associated with lesions in the 95E to 97B region: (1) Minute(3)96A (M(3)96A) is a haplo-insufficient phenotype of thin and short bristles presented by individuals deficient for the region 95E6-8;96Al5. (2) abdominal-one reduced (aor) shows two different phenotypes associated with the distal breakpoint of I ~ a ( 3 R ) U b x ~ ~ (89E;96A1-7). One is the increase of the Ubx phenotype, but its effect requires the presence of lesions in Ubx. The other phenotype is a drastic reduction or disappearance of the first abdominal segment. Both phenotypes might be due to lesions in the same gene. (3) metaphase arrest (mar) is associated with the breakpoint of the T(Y;3)B197 (96B1-10) and produces a phenotype typical of mitotic mutants with arrest of the cell cycle during prometaphase or metaphase. There is another region localized in 97B which interacts with asp: in a background homozygous for asp, three doses of this region enhance the asp phenotype. T HE cell division locus abnormal spindle (asp, RIPOLL et al. 1985) resides in one of the rather “unexplored” regions of the Drosophila genome where the available genetic information is scarce. The closest accurately positioned genetic markers are M(3)95A (95A1) and Pr (96F11). Besides asp, we only know of the following loci in the M(3)95A-Pr region: M(3)96C, located in 96A-C (LINDSLEY et al. 1972), E(spl), in 96F11-14 (PREISS, HARTLEY and ARTAVANIS-TSAKONAS 1988), boss, in 96F8-11 (REINKE, and ZIPURSKY 1988), tld in 96A-C (JURGENS et al. 1984), and crb in 95E-96A ( JURGENS et ul. 1984). Through complementation analyses with two deficiencies described in this report two other loci have been located in this region: ash-2 (SHEARN, HERSPERGER and HERSPERGER 1987; SHEARN 1989), and bum (A. SPRADLING and D. MCKEARIN, personal communication). To better localize asp and characterize other loci in its vicinity we have roughly dissected the region surrounding asp, making use of deficiencies, inversions and translocations as genetic tools. In this report we describe the cytological localization of M(3)96C and asp, several new phenotypes associated with lesions in the 95E-96F interval, and some genetic interactions between lesions in the region and other genes outside of it. A summary of our results is presented in Figure 1 . ’ Present address and address for reprint requests: Department of Biochemistry, Imperial College, London SW7 2AZ, England. The publication costs of this article were partly defrayed by the payment of page charges. This article must therefore be hereby marked “advertisement“ in accordance with 18 U.S.C. $1734 solely to indicate this fact. Genetics 1 2 3 371-377 (October, 1989) MATERIALS AND METHODS Flies were reared on standard Drosophila medium at 25 O . Except when noted, all the mutations and chromosomes are described in LINDSLEY and GRELL (1 968), CRAYMER (1 984), and LINDSLEY and ZIMM (1985, 1986, 1987). The terminal duplications and interstitial deficiencies were generated following LINDSLEY et al. (1972). We have used the rearrangements shown in Table 1. All the translocations are described in LINDSLEY et al. (1 972). Tandem duplications were obtained followin the method previously described by GRELL (1 969). Brie i y, Xirradiated red females were mated to M(3)96C2 males, and the offspring of this cross was scored for suppression of the Minute phenotype. All the dominant suppressors except one were recovered from the sample of eggs laid by irradiated females during the first 72 hours after treatment. With the exception of Dp(3;3)M96Cz+I0, in which the tandemly duplicated fragment is in inverted sequence, all other suppressors turned out to be regular tandem duplications. Their sizes ranged from 5 to ca. 450 bands. Mitotic phenot pes were observed in brains of third instar larvae. Larvae o I the appropriate genotype were selected using sex, yellow, red and Tubby as larval markers. Brains were dissected in saline solution (0.7% NaCI) and fixed in 45% acetic acid. After this, they were stained with aceticorcein, squashed, and observed under a Zeiss Universal Microscope. The mitotic index was quantified following G O N Z ~ E Z , CASAL and RIPOLL (1988) using the average number of mitotic figures per optical field as a measure. Adult cuticles were prepared by cutting the appropriate pieces under the dissecting microscope. The internal organs were digested with hot 10% KOH and the cuticle washed in alcohol and mounted in Euparal for examination. RESULTS AND DISCUSSION The asp locus was previously located by meiotic recombination to the right arm of chromosome 3 at 372 C. Gonzilez et al. c ~ In (3RI Ubx7LL atsR(96Al-17; 96AZO-25) . "" * O f 13RIf16 (96A1-10;96E) * O f 13RIs09 l 95A;97A) Op (3;31M96C2'17196C1-96C5) 3 IO000 Op 13;3IM96CZ*9 (95A-97A) 8217 (95E6-8) l9,6A1-5) 196A10-20)l96B1-103 l96C5-9) H173 G73 A117 8197 H135 R87 B158 R71 l 97A) (978 ) 1978) rL A d l L I, A A X D E F A I B I C I D 1 E I F I A i Q l C k\ 96 97 M13196A ash-2 " M();96C Pr; boss* EisplI* . t, 4 aor asp mar Ml3I94CF