CYTOLOGY OF A GENETIC SEXING SYSTEM IN ANOPHELES ALBIMANUS

1979 ◽  
Vol 21 (2) ◽  
pp. 201-211 ◽  
Author(s):  
P. E. Kaiser ◽  
J. A. Seawright ◽  
D. J. Joslyn
Keyword(s):  
Gamma Irradiation ◽  
Polytene Chromosome ◽  
Physical Distance ◽  
Crossing Over ◽  
Resistance Allele ◽  
Anopheles Albimanus ◽  
Genetic Sexing ◽  
Physical Size ◽  
Chromosome Inversions ◽  
Chromosome Arm

Several translocation and translocation-inversion strains were induced in Anopheles albimanus Wiedemann by using X and gamma irradiation. The propoxur resistance allele (prr), located on chromosome arm 2R, was used to screen for T(Y;2R) translocations and In(2R) inversions. Six T(Y;2R) translocations and eight In(2R) inversions are described herein. The strains designated In(2R)[T(Y:2R)3]2 and In(2R)[T(Y;2R)6]4 eliminated 99.8% and 99.7%, respectvely, of the crossing over between the translocation breakpoint and the prr locus. A direct correlation is shown between genetic map units and physical distance (micrometers) of the polytene chromosome. Inversions are shown to eliminate recombinants in excess of the expected value based on physical size of the aberration. The Y chromosome, which is heterochromatic and located in the chromocenter in polytene complements, is visible in two terminal translocations.

A LINKAGE STUDY INVOLVING TWO WHEAT-RYE TRANSLOCATION CHROMOSOMES

1969 ◽  
Vol 11 (1) ◽  
pp. 143-146 ◽  
Author(s):  
C. J. Driscoll ◽  
G. D. Patil
Keyword(s):  
Genetic Markers ◽  
Transmission Rate ◽  
Wheat Chromosome ◽  
Linkage Study ◽  
Linkage Test ◽  
Crossing Over ◽  
Complete Linkage ◽  
Transmission Rates ◽  
Chromosome Arm

Two wheat-rye translocation chromosomes involving the same wheat chromosome arm but different rye segments were subjected to a linkage test. Apparently no crossing over occurred between the non-homologous rye segments. The genetic markers possessed by these rye segments showed complete linkage in repulsion. The male transmission rates of the translocation chromosomes agree with those expected on the basis of the male transmission rate of each when competing with the normal wheat chromosome.

scholarly journals Direct evidence for crossover and chromatid interference in meiosis of two plant hybrids (Lolium multiflorum×Festuca pratensis and Allium cepa×A. roylei)

2020 ◽  
Author(s):  
Marco Tulio Mendes Ferreira ◽  
Marek Glombik ◽  
Kateřina Perničková ◽  
Martin Duchoslav ◽  
Olga Scholten ◽  
...  
Keyword(s):  
Allium Cepa ◽  
Direct Evidence ◽  
Lolium Multiflorum ◽  
Crossing Over ◽  
Festuca Pratensis ◽  
Physical Measure ◽  
Crossover Interference ◽  
Chromosome Arm ◽  
Double Crossovers

Abstract Crossing over, in addition to its strictly genetic role, also performs a critical mechanical function, by bonding homologues in meiosis. Hence, it is responsible for an orderly reduction of the chromosome number. As such, it is strictly controlled in frequency and distribution. The well-known crossover control is positive crossover interference which reduces the probability of a crossover in the vicinity of an already formed crossover. A poorly studied aspect of the control is chromatid interference. Such analyses are possible in very few organisms as they require observation of all four products of a single meiosis. Here, we provide direct evidence of chromatid interference. Using in situ probing in two interspecific plant hybrids (Lolium multiflorum×Festuca pratensis and Allium cepa×A. roylei) during anaphase I, we demonstrate that the involvement of four chromatids in double crossovers is significantly more frequent than expected (64% versus 25%). We also provide a physical measure of the crossover interference distance, covering ~30–40% of the relative chromosome arm length, and show that the centromere acts as a barrier for crossover interference. The two arms of a chromosome appear to act as independent units in the process of crossing over. Chromatid interference has to be seriously addressed in genetic mapping approaches and further studies.

Polytene chromosome relationships of five species of the Anopheles dirus complex in Thailand

Genome ◽  
1995 ◽  
Vol 38 (3) ◽  
pp. 426-434 ◽  
Author(s):  
Anan Poopittayasataporn ◽  
Visut Baimai
Keyword(s):  
Salivary Gland ◽  
Polytene Chromosome ◽  
Chromosome Banding ◽  
Natural Populations ◽  
Anopheles Dirus ◽  
Structural Conformation ◽  
Salivary Gland Polytene Chromosome ◽  
Chromosome Arm ◽  
And Inversion ◽  
Paracentric Inversions

Photographic maps and rearrangements of each salivary gland polytene chromosome arm of Anopheles nemophilous (species F) and of An. dirus species A, B, C, and D of the Dirus group from natural populations in Thailand are presented. Structural conformation of heterokaryotypes and comparison of chromosome banding sequences reveal 10 paracentric inversions. The data on fixed inversion of 3Rb and inversion polymorphism of the X chromosome shared by these species were used to construct a phylogeny of the five members of the An. dirus complex, thereby outlining their patterns of speciation through chromosomal rearrangements.Key words: polytene chromosome rearrangements, Anopheles dirus, phylogeny.

scholarly journals Male crossing over and genetic sexing systems in the Australian sheep blowfly Lucilia cuprina

Heredity ◽  
1991 ◽  
Vol 67 (3) ◽  
pp. 365-371 ◽  
Author(s):  
Geoffrey G Foster ◽  
Gaye L Weller ◽  
Geoffrey M Clarke
Keyword(s):  
Lucilia Cuprina ◽  
Crossing Over ◽  
Genetic Sexing ◽  
Australian Sheep ◽  
Sexing Systems

scholarly journals Correlation between pairing initiation sites, recombination nodules and meiotic recombination in Sordaria macrospora.

Genetics ◽  
1992 ◽  
Vol 132 (1) ◽  
pp. 135-148 ◽  
Author(s):  
D Zickler ◽  
P J Moreau ◽  
A D Huynh ◽  
A M Slezec
Keyword(s):  
Synaptonemal Complex ◽  
Crossing Over ◽  
Chromosome 2 ◽  
Wild Type ◽  
Sordaria Macrospora ◽  
Recombination Nodules ◽  
Chromosome Arm ◽  
Serial Section Reconstruction ◽  
Pairing Initiation ◽  
Effective Pairing

Abstract The decrease of meiotic exchanges (crossing over and conversion) in two mutants of Sordaria macrospora correlated strongly with a reduction of chiasmata and of both types of "recombination nodules." Serial section reconstruction electron microscopy was used to compare the synapsis pattern of meiotic prophase I in wild type and mutants. First, synapsis occurred but the number of synaptonemal complex initiation sites was reduced in both mutants. Second, this reduction was accompanied by, or resulted in, modifications of the pattern of synapsis. Genetic and synaptonemal complex maps were compared in three regions along one chromosome arm divided into well marked intervals. Reciprocal exchange frequencies and number of recombination nodules correlated in wild type in the three analyzed intervals, but disparity was found between the location of recombination nodules and exchanges in the mutants. Despite the twofold exchange decrease, sections of the genome such as the short arm of chromosome 2 and telomere regions were sheltered from nodule decrease and from pairing modifications. This indicated a certain amount of diversity in the control of these features and suggested that exchange frequency was dependent not only on the amount of effective pairing but also on the localization of the pairing sites, as revealed by the synaptonemal complex progression in the mutants.

scholarly journals MAGIC: Mosaic Analysis by gRNA-Induced Crossing-over

2020 ◽  
Author(s):  
Sarah E. Allen ◽  
Gabriel T. Koreman ◽  
Ankita Sarkar ◽  
Bei Wang ◽  
Mariana F. Wolfner ◽  
...  
Keyword(s):  
Neural Development ◽  
Cell Biology ◽  
Double Strand Breaks ◽  
Crossing Over ◽  
Dna Double Strand Breaks ◽  
Strand Breaks ◽  
Somatic Tissues ◽  
Mosaic Analysis ◽  
Chromosome Arm ◽  
A New Technique

AbstractMosaic animals have provided the platform for many fundamental discoveries in developmental biology, cell biology, and other fields. Techniques to produce mosaic animals by mitotic recombination have been extensively developed in Drosophila melanogaster but are less common for other laboratory organisms. Here, we report mosaic analysis by gRNA-induced crossing-over (MAGIC), a new technique for generating mosaic animals based on DNA double-strand breaks produced by CRISPR/Cas9. MAGIC efficiently produces mosaic clones in both somatic tissues and the germline of Drosophila. Further, by developing a MAGIC toolkit for one chromosome arm, we demonstrate the method’s application in characterizing gene function in neural development and in generating fluorescently marked clones in wild-derived Drosophila strains. Eliminating the need to introduce recombinase-recognition sites in the genome, this simple and versatile system simplifies mosaic analysis in Drosophila and can be applied in any organism that is compatible with CRISPR/Cas9.

AN ANALYSIS OF REGIONAL CONSTRAINTS ON EXCHANGE IN DROSOPHILA MELANOGASTER USING RECOMBINATION-DEFECTIVE MEIOTIC MUTANTS

Genetics ◽  
1984 ◽  
Vol 106 (1) ◽  
pp. 45-71 ◽  
Author(s):  
Paul Szauter
Keyword(s):  
Drosophila Melanogaster ◽  
X Chromosome ◽  
Regional Distribution ◽  
Physical Distance ◽  
Evolutionary Significance ◽  
Genetic Constitution ◽  
Crossing Over ◽  
X Chromosomes ◽  
Controlling System ◽  
Meiotic Mutations

ABSTRACT The frequency of crossing over per unit of physical distance varies systematically along the chromosomes of Drosophila melanogaster. The regional distribution of crossovers in a series of X chromosomes of the same genetic constitution, but having different sequences, was compared in the presence and absence of normal genetically mediated regional constraints on exchange. Recombination was examined in Drosophila melanogaster females homozygous for either normal sequence X chromosomes or any of a series of X chromosome inversions. Autosomally, these females were either (1) wild type, (2) homozygous for one of several recombination-defective meiotic mutations that attenuate the normal regional constraints on exchange or (3) heterozygous for the multiply inverted chromosome TM2. The results show that the centromere, the telomeres, the heterochromatin and the euchromatic-heterochromatic junction do not serve as elements that respond to genic determinants of the regional distribution of exchanges. Instead, the results suggest that there are several elements sparsely distributed in the X chromosome euchromatin. Together with the controlling system affected by recombination-defective meiotic mutations, these elements specify the regional distribution of exchanges. The results also demonstrate that the alteration in the distribution of crossovers caused by inversion heterozygosity (the interchromosomal effect) results from the response of a normal controlling system to an overall increase in the frequency of crossing over, rather than from a disruption of the system of regional constraints on exchange that is disrupted by meiotic mutations. The mechanisms by which regional constraints on exchange might be established are discussed, as is the possible evolutionary significance of this system.

Une ébauche de carte cytologique pour le chromosome VII de Petunia hybrida hort.

Genome ◽  
1988 ◽  
Vol 30 (3) ◽  
pp. 423-426
Author(s):  
D. Maizonnier ◽  
A. Cornu ◽  
E. Farcy
Keyword(s):  
Petunia Hybrida ◽  
Gamma Ray ◽  
Physical Distance ◽  
The Other ◽  
Gene Location ◽  
Anthocyanin Synthesis ◽  
Crossing Over ◽  
Strong Inhibition ◽  
Cytological Mapping ◽  
Genetic Marking

Gamma-ray treatment and telotrisomic analysis were used for cytological mapping in petunia, which resulted in the genetic marking of both arms of the shorter median chromosome of the genome. An4, which is responsible for anthocyanin synthesis in part of the corolla and in the pollen, is located rather distally on the arm called α; both vs5, a mutation for virescent rosettes, and ph3, producing bluish hues of flower anthocyanins, are located on the other arm. The possibility of determining the order and physical distance of the genes with regard to the centromere is discussed. The sketch of a cytological map for chromosome VII revealed, as previously for chromosome VI, a strong inhibition of crossing-over between two genes located on both arms of the chromosome.Key words: petunia, telotrisomy, gene location, deletion.[Traduit par la revue]

Genetic and cytological mapping of a "Y–2" translocation in the Mediterranean fruit fly Ceratitis capitata

Genome ◽  
1995 ◽  
Vol 38 (6) ◽  
pp. 1091-1097 ◽  
Author(s):  
Jorge L. Cladera ◽  
M. Alejandra Delprat
Keyword(s):  
Y Chromosome ◽  
Polytene Chromosome ◽  
Large Scale ◽  
Fruit Fly ◽  
Chromosome 2 ◽  
Genetic Sexing ◽  
Male Recombination ◽  
Late Stages ◽  
Breakpoint Mapping ◽  
Determining Factor

In this paper we analyze genetically and cytologically a Y – chromosome 2 translocation with several markers, some of which are potentially useful for large scale sex separation. The breakpoint of this Y–2 translocation is located at region 6B on the trichogene polytene chromosome map. It was found that, in strains carrying this TY–2, only 40% of the fertilized eggs survived to the adult stage, 26% of them dying as embryos, 27% as larvae, and 7% as pupae. Early lethality is explained by the nonviability of adjacent-1 products of meiosis containing a deletion of section 1A–6B. The reciprocal segregation products, carrying this chromosome segment in triplicate, survive until late stages. By analyzing the phenotype of these individuals we conclude that all markers used in this study are located outside the triplicated region and that the male determining factor is not included in the piece of the Y chromosome translocated to chromosome 2. The male recombination frequencies of several genes located on chromosome 2 relative to the breakpoint of translocation T5038 have also been studied here.Key words: genetic sexing strain, Medfly polytene chromosome, adjacent-1 product, translocation breakpoint mapping.

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