Meiotic pairing behavior of two free duplications of linkage group I in Caenorhabditis elegans

1984 ◽  
Vol 195 (1-2) ◽  
pp. 52-56 ◽  
Author(s):  
A. M. Rose ◽  
D. L. Baillie ◽  
J. Curran
Keyword(s):  
Caenorhabditis Elegans ◽  
Linkage Group ◽  
Meiotic Pairing ◽  
Group I ◽  
Pairing Behavior

Isolation and mapping of DNA probes within the linkage group I gene cluster of Caenorhabditis elegans

Genome ◽  
1989 ◽  
Vol 32 (3) ◽  
pp. 365-372 ◽  
Author(s):  
T. Starr ◽  
A. M. Howell ◽  
J. McDowall ◽  
K. Peters ◽  
A. M. Rose
Keyword(s):  
Caenorhabditis Elegans ◽  
Linkage Group ◽  
Gene Cluster ◽  
Physical Map ◽  
Dna Polymorphisms ◽  
Caenorhabditis Briggsae ◽  
Coding Regions ◽  
Group I ◽  
Type Strains ◽  
I Gene

We have isolated probes for DNA polymorphisms across the linkage group I gene cluster in Caenorhabditis elegans, using Tc1-linkage selection. The probes detect strain polymorphism between the wild-type strains of var. Bristol and var. Bergerac. As a result of mapping the sites hP4, hP5, hP6, hP7, hP9, and sP1, more than 1000 kilobases (kb) of cloned cosmid DNA has been positioned on the genetic map. We found there is more DNA per map unit in the center of the gene cluster than expected on the basis of the genomic average. Furthermore, the amount is not constant across the entire region but reaches a peak in the hP9 unc-13 interval. To find the coding regions, we examined DNA cross-homology between two species, Caenorhabditis elegans and Caenorhabditis briggsae. Approximately one-third of the DNA in the hP5 hP9 interval was examined for coding regions and 21 sequences were identified within 318 kb of DNA.Key words: Caenorhabditis elegans, physical map, DNA polymorphisms, genetic mapping, Caenorhabditis briggsae.

The synaptonemal complexes of Caenorhabditis elegans: duplication mutants sDp1 and mnDp1, disjunction regulator regions and aneuploidy

Nematology ◽  
2010 ◽  
Vol 12 (5) ◽  
pp. 759-766
Author(s):  
Paul Goldstein
Keyword(s):  
Caenorhabditis Elegans ◽  
Linkage Group ◽  
X Chromosome ◽  
Initiation Site ◽  
Genetic Maps ◽  
Wild Type ◽  
Pachytene Nucleus ◽  
Synaptonemal Complexes ◽  
Recombination Nodules ◽  
Group I

AbstractThe duplication mutants sDp1 and mnDp1 in Caenorhabditis elegans differ in their size and recombination/pairing strategies within the pachytene nucleus. mnDp1 is a duplication of approximately 18% of the X chromosome with the duplicated segment transposed and inserted into linkage group V. sDp1 is a free duplication which covers 30 map units of linkage group I and crossing-over has been determined genetically with its homologue. Analysis of the synaptonemal complexes (SC) and pachytene karyotypes of both duplication mutants reveal that there is an extension of one of the SCs in mnDp1 while the sDp1 free duplication partially pairs with its homologue along a small portion of its length. The remaining region exists as a univalent in the pachytene nucleus. This indicates that there is at least one SC initiation site on the sDp1 free duplication. Only bivalent pairing is permitted and there are no trivalents. To some extent, the autosomes preferentially pair at the exclusion of the sDp1 duplication. Switching of pairing partners was evident between the duplication and the homologue, probably because of the size of the duplication. Thus, the mechanism of chromosome segregation in the two duplications is different. The number of Disjunction Regulator Regions, which are associated with X-chromosome nondisjunction, was three in both mutants compared to six in wild-type. The number of males produced in mnDp1 was 1.0%, in sDp1 it was 2.0%, while in wild-type it is 0.3%. Recombination nodules were not observed in any nuclei. The ultimate goal of these studies is to correlate the physical and genetic maps and in this study linkage group I has been identified in the pachytene nucleus.

Maternal-effect lethal mutations on linkage group II of Caenorhabditis elegans.

Genetics ◽  
1988 ◽  
Vol 120 (4) ◽  
pp. 977-986
Author(s):  
K J Kemphues ◽  
M Kusch ◽  
N Wolf
Keyword(s):  
Caenorhabditis Elegans ◽  
Linkage Group ◽  
Maternal Effect ◽  
Essential Genes ◽  
The Other ◽  
C Elegans ◽  
Lethal Mutations ◽  
Embryonic Lethal ◽  
Embryonic Lethal Mutations ◽  
F1 Progeny

Abstract We have analyzed a set of linkage group (LG) II maternal-effect lethal mutations in Caenorhabditis elegans isolated by a new screening procedure. Screens of 12,455 F1 progeny from mutagenized adults resulted in the recovery of 54 maternal-effect lethal mutations identifying 29 genes. Of the 54 mutations, 39 are strict maternal-effect mutations defining 17 genes. These 17 genes fall into two classes distinguished by frequency of mutation to strict maternal-effect lethality. The smaller class, comprised of four genes, mutated to strict maternal-effect lethality at a frequency close to 5 X 10(-4), a rate typical of essential genes in C. elegans. Two of these genes are expressed during oogenesis and required exclusively for embryogenesis (pure maternal genes), one appears to be required specifically for meiosis, and the fourth has a more complex pattern of expression. The other 13 genes were represented by only one or two strict maternal alleles each. Two of these are identical genes previously identified by nonmaternal embryonic lethal mutations. We interpret our results to mean that although many C. elegans genes can mutate to strict maternal-effect lethality, most genes mutate to that phenotype rarely. Pure maternal genes, however, are among a smaller class of genes that mutate to maternal-effect lethality at typical rates. If our interpretation is correct, we are near saturation for pure maternal genes in the region of LG II balanced by mnC1. We conclude that the number of pure maternal genes in C. elegans is small, being probably not much higher than 12.

scholarly journals Glycoproteins that exhibit extensive size polymorphisms in Dictyostelium discoideum.

Genetics ◽  
1989 ◽  
Vol 122 (1) ◽  
pp. 59-64 ◽  
Author(s):  
E Smith ◽  
A A Gooley ◽  
G C Hudson ◽  
K L Williams
Keyword(s):  
Linkage Group ◽  
Dictyostelium Discoideum ◽  
Allelic Variation ◽  
Surface Glycoprotein ◽  
Developmentally Regulated ◽  
Electrophoretic Variants ◽  
Cellular Slime Mould ◽  
Repeat Units ◽  
Group I ◽  
Cellular Slime

Abstract Electrophoretic variants which arise from amino acid substitutions, leading to charge differences between proteins are ubiquitous and have been used extensively for genetic analysis. Less well documented are polymorphisms in the size of proteins. Here we report that a group of glycoproteins, which share a common carbohydrate epitope, vary in size in different isolates of the cellular slime mould, Dictyostelium discoideum. One of these proteins, PsA, a developmentally regulated prespore-specific surface glycoprotein, has previously been shown to exist in three size forms due to allelic variation at the pspA locus on linkage group I. In this report, a second glycoprotein, PsB, which is also prespore specific but found inside prespore cells, is studied. PsB maps to linkage group II and exhibits at least four different sizes in the isolates examined. We propose that the size polymorphisms are the product of allelic variation at the pspB locus, due to differences in the number of repeat units.

The genetic and RFLP characterization of the left end of linkage group III in Caenorhabditis elegans

Genome ◽  
1993 ◽  
Vol 36 (4) ◽  
pp. 712-724 ◽  
Author(s):  
Dave Pilgrim
Keyword(s):  
Caenorhabditis Elegans ◽  
Linkage Group ◽  
Genetic Map ◽  
Physical Map ◽  
Group Iii ◽  
C Elegans ◽  
Genomic Regions ◽  
Caenorhabditis Elegans Genome ◽  
Selection Of

A genetic approach was taken to identify new transposable element Tc1 -dependent polymorphisms on the left end of linkage group III in the nematode Caenorhabditis elegans. The cloning of the genomic DNA surrounding the Tc1 allowed the selection of overlapping clones (from the collection being used to assemble the physical map of the C. elegans genome). A contig of approximately 600–800 kbp in the region has been identified, the genetic map of the region has been refined, and 10 new RFLPs as well as at least four previously characterized genetic loci have been positioned onto the physical map, to the resolution of a few cosmids. This analysis demonstrated the ability to combine physical and genetic mapping for the rapid analysis of large genomic regions (0.5–1 Mbp) in genetically amenable eukaryotes.Key words: Caenorhabditis elegans, genome analysis, RFLP, physical map, genetic map.

Linkage Analysis of Sex Determination in Bracon sp. Near hebetor (Hymenoptera: Braconidae)

Genetics ◽  
2000 ◽  
Vol 154 (1) ◽  
pp. 205-212
Author(s):  
Alisha K Holloway ◽  
Michael R Strand ◽  
William C Black ◽  
Michael F Antolin
Keyword(s):  
Linkage Group ◽  
Sex Determination ◽  
Rapd Markers ◽  
Random Amplified Polymorphic Dna ◽  
Parasitic Wasp ◽  
Specific Pattern ◽  
Diploid Males ◽  
Phenotypic Marker ◽  
Group I ◽  
Sex Locus

Abstract To test whether sex determination in the parasitic wasp Bracon sp. near hebetor (Hymenoptera: Braconidae) is based upon a single locus or multiple loci, a linkage map was constructed using random amplified polymorphic DNA (RAPD) markers. The map includes 71 RAPD markers and one phenotypic marker, blonde. Sex was scored in a manner consistent with segregation of a single “sex locus” under complementary sex determination (CSD), which is common in haplodiploid Hymenoptera. Under haplodiploidy, males arise from unfertilized haploid eggs and females develop from fertilized diploid eggs. With CSD, females are heterozygous at the sex locus; diploids that are homozygous at the sex locus become diploid males, which are usually inviable or sterile. Ten linkage groups were formed at a minimum LOD of 3.0, with one small linkage group that included the sex locus. To locate other putative quantitative trait loci (QTL) for sex determination, sex was also treated as a binary threshold character. Several QTL were found after conducting permutation tests on the data, including one on linkage group I that corresponds to the major sex locus. One other QTL of smaller effect had a segregation pattern opposite to that expected under CSD, while another putative QTL showed a female-specific pattern consistent with either a sex-differentiating gene or a sex-specific deleterious mutation. Comparisons are made between this study and the indepth studies on sex determination and sex differentiation in the closely related B. hebetor.

Linkage group I: the simultaneous estimation of recombination and interference

1976 ◽  
Vol 16 (1-5) ◽  
pp. 335-339 ◽  
Author(s):  
D.A. Meyers ◽  
P.M. Conneally ◽  
E.W. Lovrien ◽  
E. Magenis ◽  
A.D. Merritt ◽  
...  
Keyword(s):  
Linkage Group ◽  
Simultaneous Estimation ◽  
Group I

Can abortive early homologous associations promote increased crossing-over in an adjacent rearranged segment?

Genome ◽  
1988 ◽  
Vol 30 (4) ◽  
pp. 469-472 ◽  
Author(s):  
Marjorie P. Maguire
Keyword(s):  
Crossing Over ◽  
Meiotic Pairing ◽  
Pairing Behavior ◽  
Chromosome Segments

Meiotic pairing behavior of rearranged chromosome segments is compared across an informative series of combinations. The question is raised whether the simplest explanation for some peculiar findings may include a sequence of synaptic precursor events at leptotene or zygotene, the course of which may eventually strongly affect crossover frequency.Key words: meiosis, synapsis, crossing-over, rearrangement.

DOMINANT-AND-RECESSIVE EPISTASIS IN A HOMEOTIC MOSQUITO MUTANT

1976 ◽  
Vol 18 (4) ◽  
pp. 593-600
Author(s):  
Satish C. Bhalla
Keyword(s):  
Linkage Group ◽  
Wild Type ◽  
Pure Strain ◽  
Group Iii ◽  
Homeotic Mutant ◽  
Culex Pipiens Fatigans ◽  
Group I ◽  
Ratio Data ◽  
Independent Segregation ◽  
Selection For

Folowing selection for 15 generations a pure strain of a homeotic mutant spur was isolated from a Brazilian population of the mosquito Culex pipiens fatigans. Monohybrid crosses showed a 13:3 segregation indicating dominant-and-recessive epistasis for wild-type vs. spur. This implies that a dominant allele at one locus and a recessive at the other interact to produce the mutant phenotype. Dihybrid crosses with linkage group II markers yellow and ruby gave 39:13:9:3 ratios indicating independent segregation. However, the dihybrid cross with linkage group I marker maroon showed a highly significant departure from 39:13:9:3 ratio. Data available indicate that the phenotype spur is controlled by a dominant epistat in linkage group III and a recessive epistat (approximately 31.9 crossover units from maroon) in linkage group I.

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