zy zyxwvutsrqpon zyxwvutsrqpon zyxwvutsrqpo zyxwvutsrqp Heredifus 121: 2 0 7 ~212 (1994) Abstracts of papers presented at the Nordic Drosophila Meeting 1994, sponsored by Nordic Academy for Advanced Study (NorFA) and the University of Copenhagen August 13- 16, 1994, Kristiansminde/Sora, Denmark Organized by JURE PTSKUR,LEIF SDNDERGAARD and ERIKBAHN The abstracts were edited by Jure PiSkur, Asa Rasmuson-Lestander, Einar Arnason and Christophe Roos JURE PISKUR, ZORANGOJKOVIC,LEIF SQNDERGAARDWhen the mutant flies were allowed to compete with flies and ERIKBAHN:Genetic and biochemical analysis of carrying the wild type alleles, the mutant alleles were Drosophilu mutants having deregulated pyrimidine out-competed after only a few generations. We conclude that any deregulation of pyrimidine metabolism metabolism results in altered pyrimidine and associated Pyrimidine nucleotides play a central role in cellular pools. This causes various phenotypes, and such mutant metabolism and regulation. In relatively advanced organorganisms are at a disadvantage in competition with wild isms, three pathways participate in determining cellular type organisms. levels of pyrimidines: the six-step de novo biosynthetic pathway, the salvage pathway, and a three-step pathway Depurtment qj" Genetics, University of Copenhugen, 0. that catabolizes pyrimidines to beta-alaninc. However, so Furimugsgade 2A, DK- 1353 Copenhugen K , Denmark far very little is known about the control of the regnlation of pyrimidine pools in higher organisms. BIRGITTE STOKRRO', ERICMEYER',JOHNRAWIS* and Drosophilu melanogaster is an ideal organism for the JUREPISKUR':Cis-acting regulatory regions involved in study of the genetic basis of regulatory mechanisms in- expression of de novo pyrimidine biosynthesis as studied volved in the metabolism of pyrimidines. Several ap- in cultured Drosophilu cells proaches have been used for characterizing/obtaining Drosophilu strains with putative defects in pyrimidine De novo pyrimidine biosynthesis is an ubiquitous six-step metabolism: ( I ) flies were mutagenized and allowed to pathway providing pyrimidine nucleotides in the cell. lay cggs on medium containing concentrations of pyrim- While the biochemical aspects of this pathway are very idine analogs which are toxic for development of wild similar in all organisms, the number and organization of type flies; (2) progenies of black flies (beta-alanine/cuticle genes encoding the six enzymic activities differ among mutants) were screened for revertants with normal body organisms. In general, higher organisms developed multicolour; (3) various collections of mutant flies were exam- functional proteins, and these are encoded by three physined for apparent beta-alanine/cuticle deficiency and/or ically separated genes. It is the aim of this project to resistance to pyrimidine analogs. Several mutants, Su(b)', understand if and how the expression of these three genes S U ( ~ ) "s,~andfur' ~, werc obtained and tested on media is coordinated on the promoter level. containing pyrimidine analogs or elevated concentrations In Drosophilu melunogaster in vivo de novo pyrimidine of uracil. The nucleotide levels were measured in these biosynthesis is under tissue specific, developmental and mutants by high performance liquid chromatography. In sex, as well as house keeping control. In vitro, in cultured addition, mutant strains were tested for competitiveness Drosophilu cells presumably only the basal level expresin population cages. sion operates and is sufficient for normal cell growth. The The Su(h)', S ' U ( ~ ) " ~ 's,, and,fur' mutants all exhibited structural genes, rudimenrary ( r ) , dhod, and rudimenturyresistance to pyrimidine analogs and sensitivity to high like ( r - l ) , encoding the six-step pathway, have been uracil concentratlbns. The Su(b) mutants have deregu- cloned previously, and the transcription starts were deterlated de novo biosynthesis, s presumably has a defect in mined. The 5' regions, upstream from the putative start the Cdtdbohm of pyrimidines, and fur' has an unknown codons, were fused to the reporter gene, CAT (chloramdefect related to pyrimidine metabolism. The UTP pool phenicol acetyltransferase). 5' and internal deletions were in Su(b) mutants WLYSclearly higher than that in wild type introduced using appropriate restriction sites and/or exflies. However, the nucleotide levels seemed to be normal onuclease treatment. Drosophilu S2 cells were transiently in adult males of the jur' and s strains. On the other transformed with such newly constructed plasmid vechand, the pool is increased in the 3rd instar larvae of the tors. A lipofectin-based method was used for transformas strain. Therefore, in most of the examined mutants tion. relative resistance to pyrimidine analogs and sensitivity to The upstream sequences of all three genes, r, dhod, and uracil are due to a significantly enlarged pyrimidine pool. r-1, drove successfully transient expression of the reporter zyxwvutsr zyxwvut 208 zyxwvutsrq zyx zyx zyxwvutsrqpo zyxwvutsrqp zyxwvutsr ABSTRACTS, NORDIC DROSOPHILA MEETING gene. In general, only a couple of hundred base-pairs were necessary for expression of any of the three genes. The r promoter sequence was the strongest and the dhod, the weakest. It is interesting to point out that no extensive homology has been found among the three promoter sequences. However, short stretches of homology exist between r and dhod, and r and r-1, but not between dhod and r-I. The observed differences in the promoter strength in vitro suggest that also in vivo each promoter may have a specific expression rate resulting in different protein concentrations. ‘ Department of Genetics, University of Copenhagen, 0. Farimagsgade 2A, DK- 1353 Copenhagen K , Denmurk School qf Biological Sciences, University of Kentucky, Lexington, K Y 40506-0225, USA CHARLOTTE KRISTIANEHJULSACER, JUREPISKUR,and LEIF ScmnmGAAm: Nested arrangement in the D. melanogaster rudimentary gene The de novo pyrimidine biosynthesis of U M P is an ubiquitous pathway. However, the organization of coding units and resulting proteins varies greatly among organisms. In higher organisms the first three steps are carried out by a multifunctional protein with four different enzymic activities. In mammals this protein is encoded by the CAD, and in Drosophila by the rudimentary (r) gene. The D. melanogaster r transcription unit is slightly more than 14 kb in length and is split into at least 8 exons and 7 introns. The mRNA is app. 7.4 kb and is translated into a 249 kD protein. In the case of the CAD gene, the transcription unit extends over app. 25 kb, and it contains at least 37 introns. The size of the introns in the r gene varies greatly, the longest is 4.5 kb while the others are in the range of 70-800 bp. It is interesting that one of the introns in the C A D gene is located at the same position as the large intron in the r gene. We have sequenced this large intron of the D. melunogaster r gene and found an ORF entirely within the intron with the potential of encoding a 898 aa protein. The codon usage of this ORF is in agreement with the pattern of codon usage of D. melanogaster “chromosomal genes” as opposed to that of genes from transposable elements. At least in embryos this O R F is actively transcribed. Furthermorc, our results indicate that the ORF is present within the corresponding intron of at least one of the D. melanogaster sibling species, D . simulms. Preliminary sequencing data from the D. simuluns ORF has revealcd app. 95 YOhomology at the nucleotide level to the m e h o g a s t e r ORF. Nucleotide substitutions are mainly in the third positions of codons. This indicates that selection operates on the translated product. Our results have revealed a new example of the special arrangement of genes termed nested genes. This kind of arrangenient of genes refer to the organization of a functional gene residing within an intron of another seemingly unrelated functional gene. However, the function of the new gene that we identified in the large intron of the D. melanogaster r gene is still unknown. Herrdirus JZJ (IYY4) Department of Genetics, Institute of Molecular Biology, University of Copenhagen, 0ster Farimagsgade 2A, 1353 Copenhagen K , Denmurk A. LAMRERTSSON, S. SAZROE-LARSSEN, MAY LYAMOURI,and TOMASK: Drosophila Minutes and ribosomal proteins Minutes ( M ) are a group of over SO phenotypically dominant similar Drosophila mutations (small bristles, prolonged larval developmental time, rough eyes, lowered female fertility, and reduced body size) widely believed to affect ribosomal protein genes. We have recently demonstrated (only for the second time) that a third-chromosome Minute locus [M(3)95A] encodes a ribosomal protein, rpS3 (ANDERSON et at. 1994). Here we describe the characterization of two new P element induced Mihute mutations, M(2)32, P[w+] and M(3166, P[w‘I; the Minute phenotype can be reversed by mobilizing the P element. Both mutations were plasmid rescued, and clones from a Drosophila genomic lambda library have been isolated. Preliminary characterization of these clones shows that, in both cases, there is a gene close to the P insertion that encodes a 600-700nt large transcript, present throughout development. We show that the P insertion in M(3166, P[w ‘1 causes an extreme Minute phenotype. Other phenotypic effects are severe developmental lesions, e.g., missing antennae and maxillary palpus, severely damaged thorax and legs, and melanotic tumors. In combination with a temperature-sensitive allele of suppressor of forked [su(f)], a locus that encodes at least one cell-autonomous vital function, the Minute phenotype is enhanced and further developmental lesions are observed. The molecular characterization of the genes disrupted by the P element insertions, is now in progress. A. LAMBERTSSON, ANDERSON, S., S. SEBDE-LARSSEN, J. MERRIAM,and M. JACOBS-LORENA. 1994. - Genetics 137 513-520 Department of Biuloxy, Division qf General Genetics, University of Oslo, P.O.B. 1031 Blindern, N-0315 Oslo, Norway zy CHRISTOPHEROOS,’ MIKA TIRRONEN,’MEELIS KOLMER* and HANNUALHO’: Drosophila’s diazepam binding inhibitor The diazepam binding inhibitor (DBI, also termed acylCoA-binding protein, ACBP, or endozepine) is a 10 kDa polypeptide found from yeast to mammals. It has becn shown the DBI and its processing products are involved in various specific biological processes such as GABAA/ benzodpazepine receptor modidation, acyl-CoA metabolism, steroidogenesis, and insulin secretion. We have cloned and sequenced the Drosophila melanogaster gene and cDNA encoding for DBI. The Drosophila DBI gene encodes a protein of 86 amino acids, showing 51 YO56% identity with previously known DBI proteins. l h e gene is composed of one noncoding 5‘ and two coding exons and is localized on the chromosomal map at position 65E. Several transcription initiation sites were detected by RNase protection and primer extension experiments. Computer analysis of the promoter region revealed features typical of housekeeping genes, such as zyxwvutsrqponml zyxwvutsrqponm Heredifus 121 (1994) ABSTRACTS, NORDIC DROSOPHILA MEETING the lack of TATA and CCAAT elements. However, on the basis of its low G C content and the lack of a CpG island, the region resembles promoters of tissue-specific genes. Northern analysis revealed that the expression of the DBI gene occurred from the larval stage onwards throughout the adult stage. In adult flies, the DBI mRNA and immunoreactivity were detected in the cardia, part of the Malpighian tubules, fat body and gametes of both sexes. Developmentally regulated expression, disappearing during metamorphosis, was detected in the larval and pupal brains. No expression was detected in the adult nervous system. On the basis of the expression of DBI in certain, but not all, tissues with high energy consumption, we propose that, in Drosophila, DBI is involved in energy metabolism in a manner that depends on the Substrate used for energy production. 209 highest gene transcription level is seen. These results show that all three mutants and the deficiency have a significantly reduced enzyme activity. Department of Genetics, University of UmeB, S-901 87 UmeB, Sweden A. BIRVEand A. RASMUSON-LESTANDER: Genetic analysis of the Su(z)l2 gene in Drosophila melanogaster zyxwvutsr z zyxwvut zyxwvutsrqp A mutant called Su(z)l2 was isolated in a P-element mutagenesis screen in z Dp(l;l)w+R6fer9males of Drosophila melanogaster, where modifiers of the zeste repression of the white gene expression were isolated. The mutant Su(z)12 also causes a strong suppression of the z' repression of the w f Sand the wZmalleles, but no other tested white mutants are suppressed. Both these alleles enhance z f and are caused by an insertion of roo and Institute of Biotechnology, University of Helsinki, FinBEL elements, respectively. land The Su(z)l2 mutant also acts as a dominant suppressor Department of Biomedical Sciences, University of Tamof position-effect-variegation (PEV) when combined with pere, Finland the In( 1 ) ~ " rearrangement. '~ This indicates that the gene product might be involved in condensation of chromatin. J. LARSSON,J. ZHANGand A. RASMUSON-LESTANDER:Preliminary results show that Su(z)12 also enhances the Genetical and molecular analysis of the Su(z)5 gene in transformation seen in the mutants Asx, Pcl, Scm, and Drosophila melanogaster Pc, giving additional sex comb teeth on second and third The Su(z)S mutant causes suppression of the 2 ' mediated leg pairs in heterozygous double mutant male flies. This repression of white, it is embryonic lethal, and together indicates that Su(z)l2 is a member of the Polycomb group with the zeste null mutant (2") Su(z)S gives extreme (Pc-G) of negative regulators. Su(z)12 is homozygous lethal in the embryonic stage, reduction in viability, small bristles and deformed wings. Three Su(z)S alleles have been used to identify the and is mapped to chromosome 3 at 49.5m.u. On the region of localization. The gene is placed between the cytological map this corresponds to 3L: 85-86. We have l(2)lgl and Gsi genes in 21A-B, between the proximal tested several deficiencies uncovering the region 83B to 85F without being able to uncover the lethality. The breakpoints of Df(2L)PM4 (21B1-2) and Df(2L)netlS (21 B2-4). The presumed Su(z)S gene has been localized deficiency map is not complete, however. We have induced 18 revertants of Su(z)12 by causing to a iclone from a chromosomal walk made by Hans Philipp Lerch, Zurich. The Su(z)S mutant causes an the P-element to jump in a hybrid dysgenesis screen. These revertants remain embryonic lethal over Su(z)l2. altered restriction map within the clone iy36-1. Reversed Northern analysis reveals only one tran- This indicates that we have induced deficiencies in the scribed portion within this chromosomal region. A pupal region and that deletions of Su(z)12 do not cause supcDNA library was screened, and clones covering 2.35 kb pression of the zeste-white interaction. Su(z)12 is thus a were sequenced. Homologies were found with the gene dominant gain-of-function mutation. coding for S-adenosylmethionine synthetdse (Sam-S) Department of Genetics, Umed University, S-901 87 (EC 2.5.1.6), previously cloned in yeast, E. coli, rat, UmeB, Sweden human, and Arabidopsis. The identity over 314 aminoacids is 74 YO between Drosophila and rat. This A. RASMUSON-LESTANDER: Analysis of two unstable enzyme catalyses the reaction: methionine + ATP --t AdoMet + PPi + Pi. AdoMet acts as a universal methyl white alleles in Drosophila melanogaster donor, and after decarboxylation it also serves as a A revertant (w u K ) , derived from a white gene duplicapropylamine group donor in the biosynthesis of tion (w" w'p) strain, has been studied. The revertant is polyamines. Developmental Northerns show that the red-eyed and completely wildtype, also in males that are gene gives two transcripts, 2.0 and 2.3 kb long. The z I , but it is very unstable. It causes deletions and transpotranscription intensity is low in embryos and larvae, sitions of the white gene and offspring with a zeste-yellow increased in later pupae and adults and highest in adult eye color (only observable in a zeste' background) are females. also very often found. We have analysed the gene activity of the Sam-S One strain established from a yellow eyed male mutants 1(2)R23, Su(z)S, 1(2)M6, and the deficiency ( z w ' "") has been especially interesting. The strain is Df(2)PM44, which uncovers the region of the Sam-S even more unstable than the original red-eyed revertant, gene. Northern blots show that all three mutant strains causing deletions, transpositions, and reversions at a produce mRNA of the same sizes as wildtype flies. Only frequency of per offspring. Su(z)S//+ have a reduced transcription level, approxiThese two mutants have been analyzed molecularly, by mately 50 "J compared to that of wildtype. construction of genomic libraries from the w +"R and the An enzyme assay has been developed to measure the w uL strains, and by selection of clones from the white S-adenosylmethionine synthetase activity in crude pro- region. Results show that the transcribed white region in tein extracts from wildtype and mutant ovaries, where the both strains has identical restriction maps. A 10 kb re- ' ' zyxwvutsr + + 2 10 ABSTRACTS, NORDIC DROSOPHILA MEETING zyxwvutsrq zyx zyxwvut zyxwvut Hereditas 121 (1994) zyxwvu zyxwvutsrq zyxwvuts zyxwvutsrq gion 5’ of the gene is also found to be identical. 3’ of the white gene, an FB element is inserted in both strains that is not present in the Oregon R or Canton S strains. Interestingly, the zeste-yellow-eyed strain (z’w ’ ””) in addition contains a NOF element within this region. Since this is the only difference found between the z I w iO R and the z ‘ w i U z strains, the NOF element might be the cause of the difference in zeste interaction between the strains. Several stocks have been established from other aberrant offspring derived from these two strains and analysed for lengths of deleted or transposed white regions by Southern blotting or in situ hybridizations. I found that 1 I out of 12 analysed white deficiencies and I I of 12 white transpositions have a breakpoint 3’ of white close to or within the FB inserts. In situ hybridizations show that the FB sequences always are left at the white locus while NOF sequences sometimes remain and sometimes are deleted. 1993. SREBP-I, a Basic-Helix-Loop-Leucine Zipper Protein That Controls Transcription of the Low Density Lipoprotein Receptor Gene. - Cell 75: 187-197. Depurtment of Moleculur Biology, Stockholm University, S - 10691 Stockholm, Sweden Present address: Department of Crop Protection, the University of’ Adelaide, Glen Osmond, S A 5064, Australia Y. TRYSELIUS, B. ASLING,and D. HULTMARK: Using the Differential Display method, to clone new genes involved in the immune response, from the Drosophila cell line mbn-2 Differential Display (DD) is a very powerful PCR-based method which can be used to clone direrentially expressed genes. We have prepared RNA from the Drosophila mbn-2 cell line. The RNA is either from normal control cells, or from cells to which lipopolysaccharide (LPS) and laminarin, a fungal product, have been added. This treatment Department of Genetics, Ume2 University, S-901 87 activates the immune response of the cells, and triggers Umeci, Sweden the synthesis and release of antibacterial peptides (SAMAKOVLIS et al. 1992, BBRC, 188, 3; 1169-1175). We S. EKENGREN’, U. THEOPOLD~ and D. HULTMARK’: are using the D D method to identify additional genes Characterisation of HLH106, a bHLH-protein isolated that are turned on in response to LPS and laminarin. from D. melanogaster Poly dT primers are used to make cDNA. The PCR-reacWe are studying the expression and function of a basic tions are then run with an arbitrary decamer as 5’ primer, helix-loop-helix protein (bHLH) denoted HLH106, and a poly-dT primer as 3’ primer. a3’P-dCTP is included which we have isolated from Drosophila melanogaster. in the reactions, and the amplified bands are detected on This Drosophila protein has a very high sequence identity a sequencing gel. Bands that are present in the induced to a human bHLH protein denoted SREBP-1 (Sterol lane and absent in the control lane, are cut out and Regulatory Element Binding Protein). SREBP-1 acts as a reamplified. Confirmation of the expression pattern is transcription factor, functioning as a positive regulator of done on Northern blots. genes involved in the uptake and synthesis of cholesterol Department of Molecular Biology, Stockholm University, (YOKOYAMA et al. 1993; WANGet al. 1994). S-106 91 Stockholm, Sweden Both the human and the Drosophila proteins are differing from all former known bHLH-proteins in two imporE. Roos, G. BJORKISJND and Y. ENGSTROM: Insect tant aspects: ( I ) they are much larger; and (2) they bind immunity. Control of inducible and fat body specific to a DNA sequence denoted Sterol Regulatory Element expression of the Cecropin genes (SRE) and not to the E-box elements that almost all known bHLH proteins have as a target sequence The strong induction of antibacterial proteins in infected insects is part of a rapidly responding defense mecha( KADESH 1993). The DrUXJiJhih HLHlO6 is synthesized as a 125 kDa nism, the insect immune system. Cecropins are potent membrane bound precursor protein that is processed to a antibacterial peptides induced by bacteria, synthesized in soluble 68 kDa fragment that translocates to the nucleus. the fat body and exported into the hemolymph. This 68 kDa fragment is probably the gene-activating In a fusion construct, the CecA 1 promoter and 760 bp form of the protein. of upstream sequence were placed upstream of the E.coliThe function of HLH106 is yet not known. However, lacZ reporter gene. This construct was used to study the high sequence identity in important regions and simi- expression in cell cultures, as well as in vivo in translarities in size, sequence recognition, intracellular local- formed flies. Expression was induced by bacterial lipoization, posttranslational regulation and expression polysaccharide. To identify sequences necessary for suggest a similar function for SREBP-1 and HLH106. correct spatial and inducible CecA I gene expression deleDue to this, we are trying to reveal if HLH106, like the tions were made in the original CecA 1 -1ucZ construct. human homolog, is involved in the regulation of the Transformed fly strains were created using P-element cholesterol metabolism in D , melanogaster. mediated transformation. Cryostat sections and dissected flies and larvae were stained for 8-gal activity, which KADESH,T. 1993. Consequenccs of heteromeric interac- allowed characterization of the Cecropin expression in tions among Helix-Loop-Helix proteins. -. Cell Growth detail. To quantify the expression, the p-gal activity was Differ. 4: 49-55 measured in larval extracts using a spectrophotometric WANG,X., R. SATO,M. S. BROWN,X. HUAand J. L. assay. Fly strains transformed with a shorter fusion conGOLDSTEIN.1994. SREBP-I, a Membrane-Bound struct, - 105 bp, maintained inducible and tissue specific Transcription Factor Released by Sterol-Regulated expression. Fly strains carrying the shortest construct, Proteolysis. - Cell 77: 53--62 -68 bp, did not promote any expression of the reporter YOKOYAMA, C., X. WANG,M. R. BRIGGS,A. ADMON, gene. A 40 bp region is conserved among the Cec proJ. WLJ, X. HUA,J. L. GOLIXTEINand M. S. BROWN. moters. In fly strains transformed with a construct carry- zyxwvu zyxwvuts zy zyxwvutsrqponmlk zy Hcwdrras 121 (1994) AUSTRALTS, NORDIC DROSOPHILA MEETING 21 1 zyxwvut zyxwvutsrqp zyxwvutsr zyxwvutsr ing an internal deletion of these 40 bp, the reporter gene was no longer inducible. It can be concluded that the 40 bp conserved element is necessary for inducible and fat body specific expression. We further present the novel observation that late embryos are immunocompetent. Depurtmcnt of Molecular Biology, Stockholm University, S - 106 91 Stockholm, Sweden U.-M. PETERSEN',T. IP' and Y. ENGSTROM':Characterization of thc Drosophila dorsal-related immunity factor, D if A new Drosophila member of the Re1 family of transcription factors, the dorsal-related immunity factor, DiJ was recently cloned and has been suggested to be involved in the regulation of the immune response in Drosophila (IP et al. 1993, Cell 7 5 753--763). To analyse if Difcan act as a positive regulator of the Drosophila Cecropin genes, DifcDNA was subcloned into an expression vector under the control of the Drosophila Actin 5C promoter. Cotransfection assays were performed in the Drosophilu blood cell line mbn-2 and in Schneider L2 cells with various reporter constructs. These cotransfections demonstrated that Dif' can activate expression of the Drosophilu Cecropin A 1 (CecA I ) gene. The upstream region of all the four Drosophih Cecropin genes contains a conserved 40-bp region which includes a ICB-likemotif. Cotransfections of Dif with a reporter construct lacking these 40-bp, confirmed that this reigon is necessary for the activation of the CecAl promoter. Furthermore, this indicates that Dif activates transcription via the KB-like motif. Department of Genetics, Urned University, S-901 87 Umed, Sweden Department of Biology, Division of Generul Genetics, University of Oslo, P.O.Box 1031 Blindern, N-0315 Oslo 3, Norway ' EINARARNASON: Statistical analyses of a perturbation/ reperturbation experiment of selection and hitchhiking at the Alcohol dehydrogenase locus in Drosophila melunogaster A perturbation experiment was set up in replicate population cages competing the Fast us Slow alleles at the Alcohol dehydrogenase locus. The alleles used in the experiment were based on a number of well characterized isochromosoma1 lines and the Fast electromorphs had a high activity whereas the Slow had low activity. After frequencies had reached approximate equilibria a reperturbation was done to test whether the initial approach to equilibrium was due to hitchhiking effects which had broken up. Results and statistical analyses of selection and recombination modeled as an effective selection coefficient using generalized additive statistical models (gum), are presented. Institute of Biology, University of Icelund, Grenshsvegur 12, 108 Reykjavik, Iceland R. A. KRERS and V. LOESCHCKE: Selection for increased acclimation to thermal stress in Drosophilu buzzatii zyxwvutsrq Selection was carried out for increased resistance to extremes of heat (ca. 42°C for 90 min) using two replicate lines of Drosophila huzzatii originating from a large mass population. All flies were conditioned to high temperature Department qf Moleculur Biology, Stockholm Univer- before selection, which was performed every second gener.sity, S - 106 91 Stockholm, Sweden ation. Flies in control lines likewise received the conditionDepartment of Biology, Center . f . r Moleculur Genetics, ing treatment, but no heat shock. Resistance to heat stress University of Culijivniu, San Diego La Jolla, California increased slowly, with significant differences from controls 92093-0322 obtained after seven generations. Conditioning did not cause an increase in resistance in the control lines, alS. ANDERSSON,K. ERIKSSONand A. LAMBERTSSON': though resistance became lower in one control. After 10 Sequence comparisons of the repeated domain in the generations of selection, in one set of experiments all lines clec- 1 eggshell locus in the melanogaster species subgroup were compared with and without conditioning and in another, all reciprocal crosses among selected and control We have examined the X-linked female sterile locus dec-l (dejective chorion-1) in the melanogaster species sub- lines were made, with offspring tested for resistance with group. This locus encodes important eggshell proteins conditioning. produced in the follicle cells during stages 9 and 12 of Following selection, the heat shock response remained oogenesis. In D. mehnoguster four variant protein forms inducible, with conditioned flies surviving a heat stress have been found, differing in 2-3 kDa each. The varia- much better than those that were not. Differences among tion is duc to deletions of I , 2, or 3 units of a 5-times lines were much greater for conditioned flies than for those repeated sequence (78 bp long) of the central-coding re- not conditioned, suggesting that the acclimation ability of gion. The same type of deletions was found in two selected lines was increased. Further, survival of females variants of D.simulans, but in this species the maximum was greater than that of males when tested without number of repeats so far observed is four. The island conditioning, but, with conditioning, survival of males was species D. mauritiunu and D. sechellia both have the higher than that of females. Comparing crosses between repeat sequence repeated three times. Sequence compari- selected and control lines, survival of F, flies generally was sons reveal that the repeats in the sirnufuns complex have intermediate, with recessive X chromosome effects indibeen less homogenized by the forces of concerted evolu- cated, and no significant effects of cytoplasm. One selection than the corresponding repeats in D. melunoguster. tion line contained an autosomal factor that increased We have also defined two domains of the repetitive resistance of males relative to females. Overall, these region that evolve at different rates and are subject to results indicated that selection, although on adults of both different mechanisms of DNA turnover. We have ex- sexes, increased the acclimation response to heat stress tended our analysis of the repetitive region to D. teissieri differently for males and females of D. huzzatii. and D. yukuba and the repetitive regions of these species seem to differ extensively from those in the simulans Department of Ecology and Genetics, University of Afarhus, N y Munkegade, Bldg. 540, DK-8000 Aarhus C, Denmark complex. ' 21 2 zyxwvutsrq zyxwvutsrqp zyx zyxwvutsrq ABSTRACTS, NORDIC DROSOPHILA MEETING PERKYLSTEN: Cell cycle regulation and cell fates in the developing compound eye of Drosophilu melunoguster The post furrow round of mitoses that occur during the early stages of the final differentiation of the Drosophila compound eye depends on signals from the photo receptor pre-clusters that have formed. In D. melanogusteu DER 'Ip " (formerly Elipse"') homozygous mutants, where fewer than normal pre-clusters form, post furrow mitoses are much less frequent than in the wild type even though the total number of cells in the G2 stage of the cell cycle is higher (BAKER and RUBIN 1989). I show that these cells are competent of mitoses and that progression through the cell cycle at this point is regulated by the transcription of string, a cdc 25 homologue. This transcription is dependent on signals from the neighbouring photo-receptor pre-clusters. This restriction of the cell cycle can be overridden by expression of string from a heat shock promoter, which results in massive numbers of mitoses just behind the furrow. The resulting post-mitotic cells are removed from the eye during later stages in the eye differentiation and are un-detectable in the emerged fly. In D. melunoguster DER"'P 'I eyes massive apoptosis can be detected among a broad band of cells on the differentiating side of the disc (BAKERand RUBIN 1989). Whereas cyclin B levels are normal for cells of the first ten or so rows behind the furrow, cells that have entered the apoptotic region of the eye disc show much elevated levels of cyclin B , suggesting a possible role for the mitotic machinery during apoptosis in the eye. These data offer a way to search for developmental cues for the R I , R6, R 7 photoreceptors and accessory cells during eye differentiation. Hereditas 121 (1994) ity. The banding pattern in these chromosomes is identical with the one seen in the larval salivary gland polytene chromosomes. Mutations in the otu gene lead to female sterility and one of the important questions is that, is the gene activity of the polytene chromosomes appearing in the PNCs normal compared with the wild type nurse cells. To approach this problem we have performed mRNA in situ hybridisations with DNA probes from several genes known to be active in the wild-type nurse cells (e.g., bicoid, Bicuudul-D, K10, oskur, hsp 26, torso, and Toll) and compared their activity in the wild type nurse cells and PNCs of otu7 mutants. We found that the polytene chromosomes of the PNCs synthesise the mRNAs of these genes, and their transcripts are transported to the pseudo-oocytes. In addition, the overall transcriptional activity of the PNC chromosomes has been studied with tritiated uridine incorporation. We have also used reporter genes from enhancer trap lines to study the activity of specific genes in the pseudonurse cells. zyxwvutsrqponmlkjihgfedcbaZYXW N. E. and G . M. R U B I N(1989). Effect on eye development of dominant mutations in Drosophila homologue of the EGF receptor. Nature 340: 150153 BAKER, Department of Drvelopmentul Biology, The Wenner gren Institute, Stockholm University 106 91 Stockholm, Sweden Department of Genetics, University qf Helsinki, P.O. Box 17, Arkudiunkutu 7, SF-00014 Helsinki, Finland CHRISTOS SAMAKOVLIS,' GERARD MANNINGand MARKKRASNOW': Genetic control of branch fusion during tracheal morphogenesis An important aspect of tracheal morphogenesis is the formation of a continuous network from the twenty independent branched units deriving from separate invaginations of ectodermal cells. After the initial phases of invagination and stereotyped branch outgrowth, five of the seven major tracheal branches in each metamere extend processes that grow towards their cognate branches in the neighboring metameres and fuse to form a continuous tubular network. In a lucZ enhancer trap screen, we have identified molecular markers for a specialized tracheal cell type that plays a key role in branch fusion, as well as mutations in 7 genes that selectively disrupt the process. These markers define the homotip cell which leads each fusing branch and mediates the outgrowth, cell recognition, adhesion, and changes in cell structure involved in branch fusion. In two of these strains, lucZ is expressed in the homotip cells of all branches destined to fuse as the fusing branches approach each other. Mutations in these genes affect fusion in all tracheal branches; one of these mutants corresponds to the gene escurgot, encoding a putative zink finger DNA binding protein. The rest of the markers express lacZ in the homotip cells after esg expression in these cells has been established and as the different branches begin to fuse. Two of these markers are expressed later in all homotip cells whereas the expression and function of the rest is further restricted to subsets of the homotip cells. We suggest that these genes comprise a regulatory hierarchy involved in homotip cell determination and function and that they control the outgrowth and fusion of tracheal branches. zyxwvuts TAPIOI. HEINOand VESA-PEKKA LAHII: Gene activity of the polytene chromosomes in the ovarian pseudonurse cells of the D. melunoguster otu mutants The ovary of D. melunogaster is composed of multiple ovarioles, each containing a series of developing egg chambers. In each egg chamber, the somatically derived follicle cells surround the developing oocyte and the 15 interconnected nurse cells. The latter 16 cells are of germ-line origin. The main function of the nurse cells is to produce macromolecules to be used by the oocyte, before and after fertilisation. The nurse cells are transcriptionally very efficient because their chromosomes are endoreduplicated. In the wild type nurse cells the replicating chromatids become separated. In the socalled pseudonurse cells (PNCs) of ovuriun tumour (otu) mutants, they do not separate, and polytene chromosomes are formed. We have studied the polytene chromosomes appearing in the otu' and otu' mutants to see if they differ between the two tissues as a result of different gene activ- I Depurtment of Moleculur Biology, Stockholm University, S-106 91 Stockholm, Sweden Biochemistry Depurtment, Stanford University, Stunjord, CA 94305-5307, USA z