scholarly journals Identification and Characterization of Breakpoints and Mutations on Drosophila melanogaster Balancer Chromosomes

2020 ◽  
Vol 10 (11) ◽  
pp. 4271-4285 ◽  
Author(s):  
Danny E. Miller ◽  
Lily Kahsai ◽  
Kasun Buddika ◽  
Michael J. Dixon ◽  
Bernard Y. Kim ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Repetitive Sequences ◽  
Intestinal Cell ◽  
Induced Mutations ◽  
Telomeric Sequences ◽  
Long Read ◽  
The Stability ◽  
Induced Apoptosis ◽  
Balancer Chromosomes

Balancers are rearranged chromosomes used in Drosophila melanogaster to maintain deleterious mutations in stable populations, preserve sets of linked genetic elements and construct complex experimental stocks. Here, we assess the phenotypes associated with breakpoint-induced mutations on commonly used third chromosome balancers and show remarkably few deleterious effects. We demonstrate that a breakpoint in p53 causes loss of radiation-induced apoptosis and a breakpoint in Fucosyltransferase A causes loss of fucosylation in nervous and intestinal tissue—the latter study providing new markers for intestinal cell identity and challenging previous conclusions about the regulation of fucosylation. We also describe thousands of potentially harmful mutations shared among X or third chromosome balancers, or unique to specific balancers, including an Ankyrin 2 mutation present on most TM3 balancers, and reiterate the risks of using balancers as experimental controls. We used long-read sequencing to confirm or refine the positions of two inversions with breakpoints lying in repetitive sequences and provide evidence that one of the inversions, In(2L)Cy, arose by ectopic recombination between foldback transposon insertions and the other, In(3R)C, cleanly separates subtelomeric and telomeric sequences and moves the subtelomeric sequences to an internal chromosome position. In addition, our characterization of In(3R)C shows that balancers may be polymorphic for terminal deletions. Finally, we present evidence that extremely distal mutations on balancers can add to the stability of stocks whose purpose is to maintain homologous chromosomes carrying mutations in distal genes. Overall, these studies add to our understanding of the structure, diversity and effectiveness of balancer chromosomes.

scholarly journals Chromosome Mapping of Repetitive Sequences inRachycentron canadum(Perciformes: Rachycentridae): Implications for Karyotypic Evolution and Perspectives for Biotechnological Uses

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Uedson Pereira Jacobina ◽  
Marcelo de Bello Cioffi ◽  
Luiz Gustavo Rodrigues Souza ◽  
Leonardo Luiz Calado ◽  
Manoel Tavares ◽  
...  
Keyword(s):  
Repetitive Sequences ◽  
Chromosome Mapping ◽  
Karyotypic Evolution ◽  
Dapi Staining ◽  
Telomeric Sequences ◽  
Replication Banding ◽  
The Family ◽  
Early Replication

The cobia,Rachycentron canadum, a species of marine fish, has been increasingly used in aquaculture worldwide. It is the only member of the family Rachycentridae (Perciformes) showing wide geographic distribution and phylogenetic patterns still not fully understood. In this study, the species was cytogenetically analyzed by different methodologies, including Ag-NOR and chromomycin A3(CMA3)/DAPI staining, C-banding, early replication banding (RGB), andin situfluorescent hybridization with probes for 18S and 5S ribosomal genes and for telomeric sequences (TTAGGG)n. The results obtained allow a detailed chromosomal characterization of the Atlantic population. The chromosome diversification found in the karyotype of the cobia is apparently related to pericentric inversions, the main mechanism associated to the karyotypic evolution of Perciformes. The differential heterochromatin replication patterns found were in part associated to functional genes. Despite maintaining conservative chromosomal characteristics in relation to the basal pattern established for Perciformes, some chromosome pairs in the analyzed population exhibit markers that may be important for cytotaxonomic, population, and biodiversity studies as well as for monitoring the species in question.

scholarly journals Characterization of the genome of the mealybug Planococcus lilacinus, a model organism for studying whole-chromosome imprinting and inactivation

2002 ◽  
Vol 79 (2) ◽  
pp. 111-118 ◽  
Author(s):  
K. NAGA MOHAN ◽  
PARAMITA RAY ◽  
H. SHARAT CHANDRA
Keyword(s):  
Drosophila Melanogaster ◽  
Repetitive Sequences ◽  
Gc Content ◽  
Model Organism ◽  
Fruit Fly ◽  
Single Copy ◽  
Coding Sequences ◽  
Repeat Sequences ◽  
Chromosome Imprinting

The co-occurrence of three chromosome-wide phenomena – imprinting, facultative heterochromatization and diffuse centromere – in the mealybug Planococcus lilacinus makes investigation of the genomics of this species an attractive prospect. In order to estimate the complexity of the genome of this species, 300 random stretches of its DNA, constituting ∼0·1% of the genome, were sequenced. Coding sequences appear to constitute ∼53·5%, repeat sequences ∼44·5% and non-coding single-copy sequences ∼2% of the genome. The proportion of repetitive sequences in the mealybug is higher than that in the fruit fly Drosophila melanogaster (∼30%). The mealybug genome (∼220 Mb) is about 1·3 times the size of the fly genome (∼165 Mb) and its GC content (∼35%) less than that of the fly genome (∼40%). The relative abundance of various dinucleotides, as analysed by the method of Gentles and Karlin, shows that the dinucleotide signatures of the two species are moderately similar and that in the mealybug there is neither over-representation nor under-representation of any dinucleotide.

Characterization of telomeres in Hordeum vulgare chromosomes by in situ hybridization. II. Healed broken chromosomes in telotrisomic 4L and acrotrisomic 4L4S lines

Genome ◽  
1992 ◽  
Vol 35 (6) ◽  
pp. 975-980 ◽  
Author(s):  
Shaoke Wang ◽  
Nora L. V. Lapitan ◽  
Marion Roder ◽  
Takumi Tsuchiya
Keyword(s):  
Arabidopsis Thaliana ◽  
In Situ Hybridization ◽  
Hordeum Vulgare ◽  
Telomeric Sequences ◽  
The Absolute ◽  
The Cross ◽  
The Stability ◽  
Different Parts

The ends of barley chromosomes hybridize in situ to the telomeric sequences of Arabidopsis thaliana. It was confirmed that the cross-hybridizing sequences in barley are found at the absolute ends of the chromosomes by exonuclease Bal31 digestion. The Bal31 experiments also indicated that telomere-like sequences do not occur in high copies at interstitial sites in barley. To determine whether healing of broken chromosomes occurred in aneuploid lines of barley containing extra chromosomes with breakages in different parts, in situ hybridization with the A. thaliana telomere on telotrisomic 4L and acrotrisomic 4L4S lines was conducted. Telosome 4L possesses breaks in the centromere and in an interstitial location in the long arm, while acrosome 4L4S possesses interstitial breaks in both long and short arms. In situ hybridization revealed the presence of telomere sequences on both broken ends of telosome 4L and acrosome 4L4S. In telosome 4L, telomere sequences were present even at the broken site of the centromere. These results show that broken ends of barley chromosomes were healed. Such healing may explain the stability of these chromosomes through many generations.Key words: telomere, centromere, telosome, acrosome, acrotrisomic, telotrisomic.

scholarly journals Genetic and molecular characterization of suppressors of SIR4 mutations in Saccharomyces cerevisiae.

Genetics ◽  
1989 ◽  
Vol 122 (1) ◽  
pp. 29-46 ◽  
Author(s):  
R Schnell ◽  
L D'Ari ◽  
M Foss ◽  
D Goodman ◽  
J Rine
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Null Allele ◽  
Loss Of Function ◽  
Induced Mutations ◽  
New Genes ◽  
Suppressor Mutations ◽  
Silencer Elements ◽  
Compensatory Mutations ◽  
The Stability

Abstract In order to learn more about other proteins that may be involved in repression of HML and HMR in Saccharomyces cerevisiae, extragenic suppressor mutations were identified that could restore repression in cells defective in SIR4, a gene required for function of the silencer elements flanking HML and HMR. These suppressor mutations, which define at least three new genes, SAN1, SAN2 and SAN3, arose at the frequency expected for loss-of-function mutations following mutagenesis. All san mutations were recessive. Suppression by san1 was allele-nonspecific, since san1 could suppress two very different alleles of SIR4, and was locus-specific since san1 was unable to suppress a SIR3 mutation or a variety of mutations conferring auxotrophies. The SAN1 gene was cloned, sequenced, and used to construct a null allele. The null allele had the same phenotype as the EMS-induced mutations and exhibited no pleiotropies of its own. Thus, the SAN1 gene was not essential. SAN1-mediated suppression was neither due to compensatory mutations in interacting proteins, nor to translational missense suppression. SAN1 may act posttranslationally to control the stability or activity of the SIR4 protein.

scholarly journals Analysis of a Strong Suppressor of Segregation Distorter in Drosophila melanogaster

Genetics ◽  
2020 ◽  
Vol 215 (4) ◽  
pp. 1085-1105 ◽  
Author(s):  
Rayla Greenberg Temin
Keyword(s):  
Drosophila Melanogaster ◽  
Natural Populations ◽  
Drive System ◽  
Deletion Mapping ◽  
Naturally Occurring ◽  
New Information ◽  
The Stability ◽  
Insight Into ◽  
Mendelian Transmission

Segregation Distorter (SD) is a naturally occurring male meiotic drive system in Drosophila melanogaster, characterized by almost exclusive transmission of the SD chromosome owing to dysfunction of sperm receiving the SD+ homolog. Previous studies identified at least three closely linked loci on chromosome 2 required for distortion: Sd, the primary distorting gene; E(SD) (Enhancer of SD), which increases the strength of distortion; and Rsp (Responder), the apparent target of Sd. Strength of distortion is also influenced by linked upward modifiers including M(SD) (Modifier of SD) and St(SD) (Stabilizer of SD), and by various unlinked suppressors. Although Sd is known to encode a mutant RanGAP protein, none of the modifiers have been molecularly identified. This work focuses on the genetic and cytological characterization of a strong X-linked suppressor, Su(SD), capable of restoring Mendelian transmission in SD/SD+ males. Sd and its cohort of positive modifiers appear to act semiquantitatively in opposition to Su(SD) with distortion strength depending primarily on the total number of distorting elements rather than which particular elements are present. Su(SD) can also suppress male sterility observed in certain SD genotypes. To facilitate its eventual molecular identification, Su(SD) was localized by deletion mapping to polytene region 13C7-13E4. These studies highlight the polygenic nature of distortion and its dependence on a constellation of positive and negative modifiers, provide insight into the stability of Mendelian transmission in natural populations even when a drive system arises, and pave the way for molecular characterization of Su(SD) whose identity should reveal new information about the mechanism of distortion.

scholarly journals The Drosophila melanogaster ade5 Gene Encodes a Bifunctional Enzyme for Two Steps in the de novo Purine Synthesis Pathway

Genetics ◽  
2000 ◽  
Vol 154 (3) ◽  
pp. 1239-1253
Author(s):  
Allyson F O'Donnell ◽  
Stanley Tiong ◽  
David Nash ◽  
Denise V Clark
Keyword(s):  
Drosophila Melanogaster ◽  
De Novo ◽  
Single Gene ◽  
Hybrid Dysgenesis ◽  
Induced Mutations ◽  
Gene Encoding ◽  
Purine Synthesis ◽  
E Coli ◽  
Gene Maps

Abstract Steps 6 and 7 of de novo purine synthesis are performed by 5-aminoimidazole ribonucleotide carboxylase (AIRc) and 4-[(N-succinylamino)carbonyl]-5-aminoimidazole ribonucleotide synthetase (SAICARs), respectively. In vertebrates, a single gene encodes AIRc-SAICARs with domains homologous to Escherichia coli PurE and PurC. We have isolated an AIRc-SAICARs cDNA from Drosophila melanogaster via functional complementation with an E. coli purC purine auxotroph. This cDNA encodes AIRc yet is unable to complement an E. coli purE mutant, suggesting functional differences between Drosophila and E. coli AIRc. In vertebrates, the AIRc-SAICARs gene shares a promoter region with the gene encoding phosphoribosylamidotransferase, which performs the first step in de novo purine synthesis. In Drosophila, the AIRc-SAICARs gene maps to section 11B4-14 of the X chromosome, while the phosphoribosylamidotransferase gene (Prat) maps to chromosome 3; thus, the close linkage of these two genes is not conserved in flies. Three EMS-induced X-linked adenine auxotrophic mutations, ade41, ade51, and ade52, were isolated. Two gammaradiation-induced (ade53 and ade54) and three hybrid dysgenesis-induced (ade55, ade56, and ade58) alleles were also isolated. Characterization of the auxotrophy and the finding that the hybrid dysgenesis-induced mutations all harbor P transposon sequences within the AIRc-SAICARs gene show that ade5 encodes AIRc-SAICARs.

Map positions of third chromosomal female sterile and lethal mutations of Drosophila melanogaster

Genome ◽  
2004 ◽  
Vol 47 (5) ◽  
pp. 832-838 ◽  
Author(s):  
Christopher Schuetze ◽  
Michelle Peters ◽  
Jia-Jen Duong ◽  
Matthieu Cavey ◽  
Ruth Dörig ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Maternal Effect ◽  
Slow Growth ◽  
Phenotypic Characterization ◽  
Female Sterility ◽  
Induced Mutations ◽  
Position Effects ◽  
Chromosomal Site ◽  
Chromosomal Mutations

Chromosomal mutations induced by ethyl methanesulfonate (EMS) treatment can cause female sterility or maternal-effect lethality in Drosophila. EMS is particularly useful to researchers because it creates mutations independent of position effects. However, because researchers have little control over the chromosomal site of mutation, post-mutagenic genetic mapping is required to determine the cytological location of the mutation. To make a valuable set of mutants more useful to the research community, we have mapped the uncharacterized part of the female-sterile – maternal-effect lethal Tübingen collection. We mapped 49 female-sterile – maternal-effect lethal alleles and 72 lethal alleles to individual deficiency intervals on the third chromosome. In addition, we analyzed the phenotype of ovaries resulting from female sterile mutations. The observed phenotypes range from tumorous ovaries and early blocks in oogenesis, to later blocks, slow growth, blocks in stage 10, to apparently full development of the ovary. The mapping and phenotypic characterization of these 121 mutations provide the necessary information for the researcher to consider a specific mutant as a candidate for their gene of interest.Key words: Drosophila melanogaster, oogenesis, female sterile, maternal-effect lethal, EMS-induced mutations.

scholarly journals ON THE COMPONENTS OF SEGREGATION DISTORTION IN DROSOPHILA MELANOGASTER

Genetics ◽  
1977 ◽  
Vol 86 (2) ◽  
pp. 321-355
Author(s):  
Barry Ganetzky
Keyword(s):  
Drosophila Melanogaster ◽  
Segregation Distortion ◽  
Meiotic Drive ◽  
Chromosome 2 ◽  
Induced Mutations ◽  
Distorted Segregation ◽  
X Ray ◽  
Naturally Occurring ◽  
Segregation Distorter

ABSTRACT The segregation distorter (SD) complex is a naturally occurring meiotic drive system with the property that males heterozygous for an SD-bearing chromosome 2 and an SD  +-bearing homolog transmit the SD-bearing chromosome almost exclusively. This distorted segregation is the consequence of an induced dysfunction of those sperm that receive the SD  + homolog. From previous studies, two loci have been implicated in this phenomenon: the Sd locus which is required to produce distortion, and the Responder (Rsp) locus that is the site at which Sd acts. There are two allelic alternatives of Rsp—sensitive (Rspsens) and insensitive (Rspins); a chromosome carrying Rspins is not distorted by SD. In the present study, the function and location of each of these elements was examined by a genetic and cytological characterization of X-ray-induced mutations at each locus. The results indicate the following: (1) the Rsp locus is located in the proximal heterochromatin of 2R; (2) a deletion for the Rsp locus renders a chromosome insensitive to distortion; (3) the Sd locus is located to the left of pr(2-54.5), in the region from 37D2-D7 to 38A6-B2 of the salivary chromosome map; (4) an SD chromosome deleted for Sd loses its ability to distort; (5) there is another important component of the SD system, E(SD), in or near the proximal heterochromatin of 2L, that behaves as a strong enhancer of distortion. The results of these studies allow a reinterpretation of results from earlier analyses of the SD system and serve to limit the possible mechanisms to account for segregation distortion.

TEM characterization of Au/Polysilicon interactions

1990 ◽  
Vol 48 (4) ◽  
pp. 650-651
Author(s):  
N. David Theodore ◽  
Leslie H. Allen ◽  
C. Barry Carter ◽  
James W. Mayer
Keyword(s):  
Solid Phase ◽  
Single Crystal Silicon ◽  
Chemical Vapor ◽  
Electrical Contacts ◽  
Silicon Substrates ◽  
Crystal Silicon ◽  
Transmission Electron ◽  
Polysilicon Films ◽  
The Stability

Metal/polysilicon investigations contribute to an understanding of issues relevant to the stability of electrical contacts in semiconductor devices. These investigations also contribute to an understanding of Si lateral solid-phase epitactic growth. Metals such as Au, Al and Ag form eutectics with Si. reactions in these metal/polysilicon systems lead to the formation of large-grain silicon. Of these systems, the Al/polysilicon system has been most extensively studied. In this study, the behavior upon thermal annealing of Au/polysilicon bilayers is investigated using cross-section transmission electron microscopy (XTEM). The unique feature of this system is that silicon grain-growth occurs at particularly low temperatures ∽300°C).Gold/polysilicon bilayers were fabricated on thermally oxidized single-crystal silicon substrates. Lowpressure chemical vapor deposition (LPCVD) at 620°C was used to obtain 100 to 400 nm polysilicon films. The surface of the polysilicon was cleaned with a buffered hydrofluoric acid solution. Gold was then thermally evaporated onto the samples.

Sign in / Sign up

Export Citation Format

Share Document