Papers by Henrik Gyurkovics
Genetics, Jun 1, 1984
Rp11215D50 (= 0 5 0) is a lethal mutation caused by the insertion of a 1.3-kb P element 5' to seq... more Rp11215D50 (= 0 5 0) is a lethal mutation caused by the insertion of a 1.3-kb P element 5' to sequences encoding the largest (215 kilodaltons) subunit of Drosophila RNA polymerase 11. In dysgenic males 050 reverted to nonlethality at frequencies ranging from 2.6 to 6.5%. These reversions resulted from loss of P element sequences. Genetic tests of function and restriction enzyme analysis of revertant DNAs revealed that 35% or more of the reversion events were imprecise excisions. Two meiotic mutations that perturb excision repair and postreplication repair (mei-9" and mei-4ID5, respectively) had no influence on reversion frequency but may have increased the proportion of imprecise excisions. We suggest that these excisions are by-products of, rather than intermediates in, the transposition process. HE term "hybrid dysgenesis" refers to a syndrome of anomalies that occurs T in F1 hybrids of crosses between certain strains of Drosophila melanogaster (KIDWELL, KIDWELL and SVED, 1977). The anomalous traits include elevated visible and lethal mutation rates, sterility, chromosome breakage, recombination in males, transmission ratio distortion, local increases in chromosomal recombination in females and nondisjunction in females. These anomalies are observed among the hybrid progeny when females of M strains (maternally contributing) are crossed to males of P strains (paternally contributing) but are not observed in the reciprocal cross. The discovery that both chromosomal and cytoplasmic components are involved in the induction and stability of mutants produced by dysgenic flies (KIDWELL, KIDWELL and SVED, 1977; EN-GELS 1979a,b, 198 1) provided evidence for suggestions that this phenomenon involves some type of transposable genetic element (GOLUBOVSKY, IVANOV and GREEN 1977; GREEN 1977). These suggestions were confirmed by the discovery that P strains carry multiple copies of a mobile genetic factor, termed the P element, integrated at polymorphic sites throughout their genomes (RUBIN, KIDWELL and BINGHAM 1982; BINGHAM, KIDWELL and RUBIN 1982). Most M
Molecular Genetics And Genomics, Dec 1, 1985
The RplI215 region of the X chromosome of Drosophila melanogaster was investigated to identify ge... more The RplI215 region of the X chromosome of Drosophila melanogaster was investigated to identify genetic functions and correlate these with the known molecular organization of the region. Five genetic loci were identified in a subregion that is reported to transcribe nine or more messages. One locus is nod, which causes meiotic abnormalities, and three other loci are recessive lethal mutations whose developmental lesions are unknown. The fifth and most mutable of the loci is RplI215, which encodes the 215,000 dalton subunit of RNA polymerase II. Mutant effects of RplI215 alleles include: temperature-dependent (heat and cold) survival, altered sensitivity to ~-amanitin, male sterility, maternal effects and epistatic enhancement of mutant effects of other loci.
Natura Somogyiensis /, 2012
Genomic organization and functional analysis of a deletion variant of the 87A7 heat shock locus of Drosophila melanogaster
Journal of Molecular Biology, Mar 1, 1982
The major 70,000 Mr heat-induced protein (hsp 70) of Drosophila melanogaster is encoded at two lo... more The major 70,000 Mr heat-induced protein (hsp 70) of Drosophila melanogaster is encoded at two loci, 87A7 and 87C1. The 87A7 locus has two hsp 70-coding sequences (zc) about 2·8 × 103 bases apart in a divergent orientation. We have identified a variant 87A7 locus, the Sze-13 chromosome, which has a reduced heat shock puff. Characterization of this altered 87A7 locus reveals that it has a small deletion in the spacer between the two genes that inactivates the proximal gene. The mutant locus has been cloned and the breakpoints of the deletion determined by sequence analysis. We find that the deletion removes the entire 5′ half of the proximal hsp 70 gene and extends to position −479 base-pairs upstream from the start of transcription of the distal gene. Using flies that retain only the mutant 87A7 hsp 70 locus of Sze-13 we have shown that the one remaining “intact” hsp 70 gene is still active. Since a partially deleted hsp 70 gene lacking the 3′ half of the transcription unit is also active, it is likely that the initial portion of the transcription unit (zc) plus the conserved znc sequence that is immediately adjacent to the 5′ end of the gene contain the sequences necessary for hsp 70 expression.
Genetics, Nov 1, 1999
In the studies reported here, we have examined the properties of the Mcp element from the Drosoph... more In the studies reported here, we have examined the properties of the Mcp element from the Drosophila melanogaster bithorax complex (BX-C). We have found that sequences from the Mcp region of BX-C have properties characteristic of Polycomb response elements (PREs), and that they silence adjacent reporters by a mechanism that requires trans-interactions between two copies of the transgene. However, Mcp transregulatory interactions have several novel features. In contrast to classical transvection, homolog pairing does not seem to be required. Thus, trans-regulatory interactions can be observed not only between Mcp transgenes inserted at the same site, but also between Mcp transgenes inserted at distant sites on the same chromosomal arm, or even on different arms. Trans-regulation can even be observed between transgenes inserted on different chromosomes. A small 800-bp Mcp sequence is sufficient to mediate these longdistance trans-regulatory interactions. This small fragment has little silencing activity on its own and must be combined with other Polycomb-Group-responsive elements to function as a "pairing-sensitive" silencer. Finally, this pairing element can also mediate long-distance interactions between enhancers and promoters, activating mini-white expression.
Natura Somogyiensis /, 2014
The Tenthredopsis Costa, 1859 collections of the Hungarian public collections are reidentified an... more The Tenthredopsis Costa, 1859 collections of the Hungarian public collections are reidentified and published. Tenthredopsis albonotata (Brullé, 1832), Tenthredopsis andrei Konow, 1898 and Tenthredopsis floricola (Costa, 1859) are new records for the Hungarian fauna.
Journal of Cellular Biochemistry, 1984
The "enzyme-probe" method [Solti M, Friedrich P: Eur J Biochem 9S:SS1, 19791 has been applied to ... more The "enzyme-probe" method [Solti M, Friedrich P: Eur J Biochem 9S:SS1, 19791 has been applied to characterize the cyclic AMP pool in wild-type CantonS and memory-mutant dunceM" strains of Drosophila melanogaster. The kinetics of cyclic AMP breakdown in whole fly homogenates by endogenous cyclic nucleotide phosphodiesterase(s) indicate that the cyclic AMP pool is divided into free and bound fractions. The bound fraction in CantonS and dunceM" is 0.5 and 1.5 pmole/mg fly, respectively. Considering the total cyclic AMP content of the two strains, 1.6 and 10 pmoleimg fly, respectively, we conclude that the bulk of excess cyclic AMP in the mutant is free nucleotide.
Genetics, Aug 1, 1981
The region between 86Fl;2 and 87B15 on chromosome 3 of Drosophila melanogaster, which contains ab... more The region between 86Fl;2 and 87B15 on chromosome 3 of Drosophila melanogaster, which contains about 27 polytene chromosome bands including the 87A7 heat-shock locus, has been screened for EMS-induced visible and lethal mutations. We have recovered 268 lethal mutations that fall into 25 complementation groups. Cytogenetic localization of the complementation groups by deficiency mapping is consistent with the notion that each band encodes a single genetic function. We have also screened for mutations at the * Inahtate of Genetics, Biological Research Centre of the Hungarian Academy of Sciences, 6701 Szeged, POB 521,
PLOS Genetics, May 24, 2012
The homeotic genes in Drosophila melanogaster are aligned on the chromosome in the order of the b... more The homeotic genes in Drosophila melanogaster are aligned on the chromosome in the order of the body segments that they affect. The genes affecting the more posterior segments repress the more anterior genes. This posterior dominance rule must be qualified in the case of abdominal-A (abd-A) repression by Abdominal-B (Abd-B). Animals lacking Abd-B show ectopic expression of abd-A in the epidermis of the eighth abdominal segment, but not in the central nervous system. Repression in these neuronal cells is accomplished by a 92 kb noncoding RNA. This ''iab-8 RNA'' produces a micro RNA to repress abd-A, but also has a second, redundant repression mechanism that acts only ''in cis.'' Transcriptional interference with the abd-A promoter is the most likely mechanism.
Natura Somogyiensis /, 2011
Xyela nigroabscondita spec. nov. is described from Hungary and compared to Xyela lugdunensis (Ber... more Xyela nigroabscondita spec. nov. is described from Hungary and compared to Xyela lugdunensis (Berland, 1943), analysis and photos of the type of Xyela helvetica (Benson, 1961) is published.
Development, Feb 15, 2000
The Drosophila bithorax complex Abdominal-B (Abd-B) gene specifies parasegmental identity at the ... more The Drosophila bithorax complex Abdominal-B (Abd-B) gene specifies parasegmental identity at the posterior end of the fly. The specific pattern of Abd-B expression in each parasegment (PS) determines its identity and, in PS10-13, Abd-B expression is controlled by four parasegmentspecific cis-regulatory domains, iab-5 to iab-8, respectively. In order to properly determine parasegmental identity, these four cis-regulatory domains must function autonomously during both the initiation and maintenance phases of BX-C regulation. The studies reported here demonstrate that the (centromere) distal end of iab-7 domain is delimited by the Fab-8 boundary. Initiators that specify PS12 identity are located on the proximal iab-7 side of Fab-8, while initiators that specify PS13 identity are located on the distal side of Fab-8, in iab-8. We use transgene assays to demonstrate that Fab-8 has enhancer blocking activity and that it can insulate reporter constructs from the regulatory action of the iab-7 and iab-8 initiators. We also show that the Fab-8 boundary defines the realm of action of a nearby iab-8 Polycomb Response Element, preventing this element from ectopically silencing the adjacent domain. Finally, we demonstrate that the insulating activity of the Fab-8 boundary in BX-C is absolutely essential for the proper specification of parasegmental identity by the iab-7 and iab-8 cisregulatory domains. Fab-8 together with the previously identified Fab-7 boundary delimit the first genetically defined higher order domain in a multicellular eukaryote.
Development, Oct 1, 1988
Embryonic pattern in Drosophila is organized by a hierarchy of maternal and zygotic segmentation ... more Embryonic pattern in Drosophila is organized by a hierarchy of maternal and zygotic segmentation genes that interact to define increasingly precise spatial domains (reviewed by Scott & O'Farrell , 1986; Akam , 1987). A metameric body plan is already established by the onset of gastrulation (3 h postfertilization) such that each segment expresses the segment-polarity genes engrailed (en) and wingless'(wg) in single-cell-wide stripes (Kornberg, Sidon, O'Far
Genetics, Sep 1, 1993
The suppressor of position effect variegation (PEV) locus Su-var(3)6 maps to 87B5-10. The breakpo... more The suppressor of position effect variegation (PEV) locus Su-var(3)6 maps to 87B5-10. The breakpoints of deficiencies that define this interval have been placed on a 250-kb molecular map of the region. The locus is allelic to the ck19 complementation group previously shown to encode a type 1 serine-threonine protein phosphatase (PPl) catalytic subunit. When introduced into flies by P elernent-mediated transformation, a 5.8-kb genomic fragment carrying this gene overcomes the suppressor phenotype of Su-var(3)6'' and recessive lethality of all mutations of the locus. Four of the mutant alleles at the locus show a broad correlation between high levels of suppression of PEV, a high frequency of aberrant mitosis and low PP1 activity in larval extracts. However, some alleles with low PP1 activity show weak suppression of PEV with a high frequency of abnormal mitosis, whereas others show strong suppression of PEV with normal mitosis. The basis for these disparate phenotypes is discussed. ~~ C HROMOSOMAL rearrangements that move eu
Development, Dec 15, 2008
Although the boundary elements of the Drosophila Bithorax complex (BX-C) have properties similar ... more Although the boundary elements of the Drosophila Bithorax complex (BX-C) have properties similar to chromatin insulators, genetic substitution experiments have demonstrated that these elements do more than simply insulate adjacent cis-regulatory domains. Many BX-C boundaries lie between enhancers and their target promoter, and must modulate their activity to allow distal enhancers to communicate with their target promoter. Given this complex function, it is surprising that the numerous BX-C boundaries share little sequence identity. To determine the extent of the similarity between these elements, we tested whether different BX-C boundary elements can functionally substitute for one another. Using gene conversion, we exchanged the Fab-7 and Fab-8 boundaries within the BX-C. Although the Fab-8 boundary can only partially substitute for the Fab-7 boundary, we find that the Fab-7 boundary can almost completely replace the Fab-8 boundary. Our results suggest that although boundary elements are not completely interchangeable, there is a commonality to the mechanism by which boundaries function. This commonality allows different DNA-binding proteins to create functional boundaries.
Molecular and Cellular Biology, May 1, 2008
SWI/SNF ATP-dependent chromatin remodeling complexes (remodelers) perform critical functions in e... more SWI/SNF ATP-dependent chromatin remodeling complexes (remodelers) perform critical functions in eukaryotic gene expression control. BAP and PBAP are the fly representatives of the two evolutionarily conserved major subclasses of SWI/SNF remodelers. Both complexes share seven core subunits, including the Brahma ATPase, but differ in a few signature subunits; POLYBROMO and BAP170 specify PBAP, whereas OSA defines BAP. Here, we show that the transcriptional coactivator and PHD finger protein SAYP is a novel PBAP subunit. Biochemical analysis established that SAYP is tightly associated with PBAP but absent from BAP. SAYP, POLYBROMO, and BAP170 display an intimately overlapping distribution on larval salivary gland polytene chromosomes. Genome-wide expression analysis revealed that SAYP is critical for PBAP-dependent transcription. SAYP is required for normal development and interacts genetically with core-and PBAPselective subunits. Genetic analysis suggested that, like BAP, PBAP also counteracts Polycomb silencing. SAYP appears to be a key architectural component required for the integrity and association of the PBAP-specific module. We conclude that SAYP is a signature subunit that plays a major role in the functional specificity of the PBAP holoenzyme.
Development, Aug 1, 2006
The three homeotic genes of the bithorax complex (BX-C), Ubx, abd-A and Abd-B control the identit... more The three homeotic genes of the bithorax complex (BX-C), Ubx, abd-A and Abd-B control the identity of the posterior thorax and all abdominal segments. Large segment-specific cis-regulatory regions control the expression of Ubx, abd-A or Abd-B in each of the segments. These segment-specific cis-regulatory regions span the whole 300 kb of the BX-C and are arranged on the chromosome in the same order as the segments they specify. Experiments with lacZ reporter constructs revealed the existence of several types of regulatory elements in each of the cis-regulatory regions. These include initiation elements, maintenance elements, cell type-or tissue-specific enhancers, chromatin insulators and the promoter targeting sequence. In this paper, we extend the analysis of regulatory elements within the BX-C by describing a series of internal deficiencies that affect the Abd-B regulatory region. Many of the elements uncovered by these deficiencies are further verified in transgenic reporter assays. Our results highlight four key features of the iab-5, iab-6 and iab-7 cis-regulatory region of Abd-B. First, the whole Abd-B region is modular by nature and can be divided into discrete functional domains. Second, each domain seems to control specifically the level of Abd-B expression in only one parasegment. Third, each domain is itself modular and made up of a similar set of definable regulatory elements. And finally, the activity of each domain is absolutely dependent on the presence of an initiator element.
Csoportunkban a génaktivitás kromatin szintű szabályozásával foglalkozunk. Vizsgálatainkhoz elsős... more Csoportunkban a génaktivitás kromatin szintű szabályozásával foglalkozunk. Vizsgálatainkhoz elsősorban a Drosophila melanogaster testszerveződését és szegmentjeinek egyedi jellegzetességeit meghatározó homeotikus gén-rendszert, ezen belül is főképpen a bithorax-komplexet használjuk modellként. A bithorax-komplex az ecetmuslica középtorától hátrafelé elhelyezkedő szelvények megfelelő kialakulásáért felelős. A komplex három génje, az Ubx az abd-A és az Abd-B, kilenc szelvény azonosságát képes meghatározni. Ezt a komplexben az általuk szabályozott szelvényekkel kolineárisan elhelyezkedő kilenc, szelvény specifikus szabályozó régió (cis-regulátor) teszi lehetővé. Az egyre hátrébb elhelyezkedő szelvényekben mindig egy új cisz-regulátor aktiválódik, kerül nyitott kromatin
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Papers by Henrik Gyurkovics