A CROSSOVER SUPPRESSOR-ENHANCER SYSTEM IN THE MOSQUITO AEDES AEGYPTI

A small reciprocal translocation T(1;2)1 involving chromosomes 1 and 2 and a paracentric inversion In(1)3 on m chromosome (1) of A. aegypti interact to give peculiar but consistent crossover values. The system is termed COSES and is associated with partial sterility. In females it suppresses crossing over tremendously to the right of bz and enhances crossing over to its left. In the males it enhances crossing over to the right of m (only 3 crossover units away from bz) hut the region to its left remains unaffected. COSES also displays interchromosomal effects by enhancing crossing over in linkage group III. Cytological and genetic evidence for the presence of translocation and inversion are presented. All three pairs of chromosomes are correlated to the three linkage groups.

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CROSSOVER SUPPRESSORS AND BALANCED RECESSIVE LETHALS IN CAENORHABDITIS ELEGANS

Genetics ◽

10.1093/genetics/88.1.49 ◽

1978 ◽

Vol 88 (1) ◽

pp. 49-65

Author(s):

Robert K Herman

Keyword(s):

Caenorhabditis Elegans ◽

Linkage Group ◽

The Other ◽

Crossing Over ◽

Linkage Groups ◽

Recessive Lethal ◽

X Ray ◽

C Elegans ◽

Complementation Groups ◽

The Right

ABSTRACT Two dominant suppressors of crossing over have been identified following X-ray treatment of the small nematode C. elegans. They suppress crossing over in linkage group II (LGII) about 100-fold and 50-fold and are both tightly linked to LGII markers. One, called C1, segregates independently of all other linkage groups and is homozygous fertile. The other is a translocation involving LGII and X. The translocation also suppresses rrossing over along the right half of X and is homozygous lethal. CI has been used as a balancer of LGII recessive lethal and sterile mutations induced by EMS. The frequencies of occurrence of lethals and steriles were approximately equal. Fourteen mutations were assigned to complementation groups and mapped. They tended to map in the same region where LGII visibles are clustered.

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Genetics of Glossina morsitans morsitans (Diptera: Glossinidae). IX. Definition of linkage group III and further mapping of linkage groups I and II

Canadian Journal of Genetics and Cytology ◽

10.1139/g84-040 ◽

1984 ◽

Vol 26 (3) ◽

pp. 253-257 ◽

Cited By ~ 3

Author(s):

R. H. Gooding

Keyword(s):

Linkage Group ◽

Aldehyde Oxidase ◽

Glossina Morsitans Morsitans ◽

Linkage Groups ◽

Glossina Morsitans ◽

Malic Dehydrogenase ◽

Group Iii ◽

Glycerophosphate Dehydrogenase ◽

Group I ◽

The Right

In Glossina morsitans morsitans Westwood, linkage group III is defined as the autosome carrying the locus Mdh (malic dehydrogenase), the only locus so far identified in this linkage group. The locus αGpd.2 (α-glycerophosphate dehydrogenase) was located 45 map units (MU) to the left of Xo (xanthine oxidase) and the loci Est.1 and Est.2 (loci for two esterases found in the thorax) were mapped approximately 5–10 MU to the right of Ao (aldehyde oxidase) in linkage group II. The location of G6pd (glucose-6-phosphate dehydrogenase) has been confirmed to be approximately 37 MU to the left of oc (ocra body color) in linkage group I and it was shown that this region of the X chromosome does not involve the large paracentric inversion found in the Handeni line. A genetic map for 12 loci in the three linkage groups found in G. m. morsitans is presented.Key words: Diptera, Glossina, mapping, inversion, isozymes.

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SEX AND CROSSING OVER IN LINKAGE GROUP III OF TRIBOLIUM CASTANEUM

Canadian Journal of Genetics and Cytology ◽

10.1139/g77-028 ◽

1977 ◽

Vol 19 (2) ◽

pp. 259-263 ◽

Cited By ~ 1

Author(s):

Alexander Sokoloff

Keyword(s):

Sex Differences ◽

Linkage Group ◽

Tribolium Castaneum ◽

Relative Position ◽

Genetic Background ◽

Crossing Over ◽

Group Iii ◽

The Third ◽

Main Factors ◽

Coleoptera Tenebrionidae

The relative position of the genes black (b), light ocular diaphragm (lod) and aureate (au) for the third linkage group of T. castaneum (Herbst) (Coleoptera, Tenebrionidae) has been determined as b – lod – au. The distances between the various genes vary, depending on the cross. The b++/+ lod au ♂ × + lod au/+ lod au ♀ crosses give the following recombination values: au – lod = 18.32 ± 1.21%; b – lod = 21.05 ± 1.51% and b – au = 37.43 ± 1.27%. The reciprocal crosses give au – lod = 27.67 ± 1.62%; b – lod = 13.97 ± 1.26% and b – au = 39.79 ± 1.78%. For the larger distances encompassed in the b – au region the recombination values in the two sexes were not significantly different. For the shorter b – lod region the recombination values were significantly larger in the females than in the males, while for the adjacent lod – au region the opposite was true. On the basis of the current literature it would appear that the main factors contributing to these sex differences in recombination are the modifiers which are different in the genetic background of the two sexes.

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THE GENETIC ANALYSIS OF A RECIPROCAL TRANSLOCATION, eT1(III; V), IN CAENORHABDITIS ELEGANS

Genetics ◽

10.1093/genetics/99.3-4.415 ◽

1981 ◽

Vol 99 (3-4) ◽

pp. 415-428

Author(s):

Raja E Rosenbluth ◽

David L Baillie

Keyword(s):

Caenorhabditis Elegans ◽

Genetic Analysis ◽

Gene Order ◽

Reciprocal Translocation ◽

New Order ◽

Linkage Groups ◽

Recombination Rates ◽

Left Half ◽

New Gene ◽

The Right

ABSTRACT The Caenorhabditis elegans mutation e873, which results in a recessive uncoordinated phenotype (formerly named Unc-72) and which had been isolated after 32P t reatment (BRENNER1 974), has now been found to act as a crossover suppressor and to be associated with a translocation between linkage groups (LG's) IIIand V. The translocation has been named, eTl(ZI1; V); eT1acts as a dominant crossover suppressor for both the right half of LGIIIand the left half of LGV,providing a balancer for a total of 39 map units. The uncoordinated e873phenotype has been shown to be a consequence of Eminactive unr- 36111gene. It was possible to demonstrate that, in translocation heterozygotes, eT1chromosomes marked with either sma-3or dpy-11segregate from normal LGIII,while those marked with bli-5, sm-2or unc-42segregate from normal LGV.Since bli-5and sma-2are normally on LGIII,and dpy-11is normally on LGV,it is concluded that: (a) eT1is a reciprocal translocation; (b) there is a breakpoint between sma-3and sma-2in LGIII(the region containing unc- 36)and one between dpy-11and unc-42in LGV;(c) thera is no dominant centromere between sma-2and bli-5on LGIII,since in eT1these genes are not linked to a LGIIIcentromere. Similarly, it is highly unlikely that there is a centromere to the left of dpy-11on LGV.The new gene order in eT1was determined by measuring recombination rates between markers in eT1homozygotes. It is concluded that the new order is: dpy-1 sma-3 (break) dpy-11 unc-60,and bli-5 sma-2 (break) unc-42 unc-51.——Thisis the first analysis of a C. eleganstranslocation with respect to reciprocity, breakpoints and new gene order.

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Correlation of the physical and genetic maps of the centromeric region of the right arm of linkage group III of Neurospora crassa.

Genetics ◽

10.1093/genetics/136.4.1297 ◽

1994 ◽

Vol 136 (4) ◽

pp. 1297-1306

Author(s):

C R Davis ◽

R R Kempainen ◽

M S Srodes ◽

C R McClung

Keyword(s):

Linkage Group ◽

Neurospora Crassa ◽

Fragment Length Polymorphism ◽

Centromeric Region ◽

Recombination Frequency ◽

Genetic Maps ◽

Polymorphism Analysis ◽

Group Iii ◽

Sib Selection ◽

The Right

Abstract We have cloned three linked genes serine-1 (ser-1), proline-1 (pro-1) and acetate-2 (ace-2) that lie near the centromere on the right arm of linkage group III (LGIIIR) of Neurospora crassa. The ser-1 gene was cloned by sib selection. A chromosomal walk that spans 205 kilobases (kb) was initiated from ser-1. Complementation analysis with clones isolated during the walk allowed identification of the pro-1 and ace-2 genes. Restriction fragment length polymorphism analysis has confirmed the localization of ser-1, pro-1 and ace-2 to the centromeric region of LGIIIR. Genetically, we measured 1% recombination between ser-1 and pro-1 and 2% recombination between pro-1 and ace-2. Physical distances for these intervals were 114 kb from ser-1 to pro-1 and 36 kb from pro-1 to ace-2. Thus, for the pro-1 to ace-2 interval we calculate a physical/genetic correlation of 18 kb/map unit (mu) whereas, in the immediately adjacent, centromere-proximal interval from ser-1 to pro-1, we calculate 114 kb/mu. This provides evidence for a centromere effect, a decrease in recombination frequency as one approaches the centromere.

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Chromosomal regions which control sporulation in Bacillus subtilis

Canadian Journal of Microbiology ◽

10.1139/m69-137 ◽

1969 ◽

Vol 15 (7) ◽

pp. 787-790 ◽

Cited By ~ 6

Author(s):

Marvin Rogolsky

Keyword(s):

Bacillus Subtilis ◽

Linkage Group ◽

Genetic Map ◽

Gene Clusters ◽

Linkage Groups ◽

The Third ◽

The Right

Large quantities of sporulation mutants have been isolated with a variety of mutagens. The genetic sites for asporogeny have been localized on the chromosome of Bacillus subtilis through transduction with phage PBSI. Through these procedures specific portions of the chromosome which are associated with sporulation have been identified. Although asporogenic (Sp−) defects were observed to be scattered throughout the four linkage groups of the genetic map of B. subtilis, only three extensive Sp− linkage groups were identified. The first linkage group of Sp− markers is located at the proximal end of the chromosome between the cys A and ery markers. The second cluster of spore genes mapped to the right of ura, and the third linkage group of spore markers mapped to the left of lys-2. Defects within specific regions of the first and third spore gene clusters obstructed some early products of sporogenesis.

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Location of factors enhancing crossing over on linkage group I of Neurospora

Genetics Research ◽

10.1017/s0016672300013367 ◽

1973 ◽

Vol 21 (2) ◽

pp. 195-204

Author(s):

Jenny Hargrave ◽

S. F. H. Threlkeld

Keyword(s):

Linkage Group ◽

Distal Region ◽

Proximal Region ◽

Crossing Over ◽

Group I ◽

The Right

SUMMARYAn enhancement of cross-over frequencies previously reported by Newcombe & Threlkeld (1972) is shown to be due to two regions located on linkage group I, a few cross-over units to the right of the centromere. The distal region appears to be shorter than the proximal region, but equally effective in enhancing cross-over frequencies. The longer proximal region is readily divisable by cross-overs and probably spans several crossover units.

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Genetics of Glossina palpalis palpalis: designation of linkage groups and the mapping of eight biochemical and visible marker genes

Genome ◽

10.1139/g95-109 ◽

1995 ◽

Vol 38 (5) ◽

pp. 833-837 ◽

Cited By ~ 10

Author(s):

R. H. Gooding ◽

B. M. Rolseth

Keyword(s):

Linkage Group ◽

Recombination Frequency ◽

Marker Genes ◽

Glossina Palpalis Palpalis ◽

Linkage Groups ◽

Group Iii ◽

Eye Color ◽

Eye Color Mutants ◽

Octanol Dehydrogenase ◽

Glossina Palpalis

The loci for three enzymes (hexokinase, phosphoglucomutase, and testicular esterase) and two eye-color mutants (brick and tan) are mapped on the X chromosome of Glossina palpalis palpalis. The loci occur in the order brick Hex (tan/Pgm) Est-t, with a recombination frequency of approximately 78% between the outer two loci. The locus for octanol dehydrogenase is located in linkage group II and the loci for malate dehydrogenase and phosphoglucose isomerase are separated by a recombination frequency of about 42.5% in linkage group III. Intrachromosomal recombination occurs at a much lower frequency in males than in females. The distribution of five biochemical marker genes in the linkage groups of G. p. palpalis is markedly different from that found in other higher flies.Key words: tsetse, Glossina palpalis palpalis, linkage map.

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Genetic analysis by means of the parasexual cycle in Aspergillus niger

Genetics Research ◽

10.1017/s0016672300010752 ◽

1967 ◽

Vol 10 (1) ◽

pp. 45-61 ◽

Cited By ~ 46

Author(s):

Pol Lhoas

Keyword(s):

Aspergillus Niger ◽

Linkage Group ◽

Genetic Analysis ◽

Sexual Cycle ◽

Crossing Over ◽

Linkage Groups ◽

Parasexual Cycle ◽

Sexual Species ◽

Data Support ◽

Almost All

An investigation of mitotic segregation and recombination in A. niger gave the following results:1. Thirty-one non-allelic markers have been assigned to six linkage groups (containing 11, 9, 6, 3, 1 and 1 markers respectively) by the analysis of haploid mitotic segregants from synthesized diploids.2. The sequence of nine markers in one linkage group was determined and some of the map intervals were estimated by the analysis of haploids, recombinants for linked markers.3. Almost all the haploid segregants were obtained on medium supplemented with the aminoacid analogue, p-fluoro-phenylalanine, the action of which is interpreted as an induction of chromosome losses.4. The rates of mitotic crossing-over and haploidization are much higher than in the sexual species A. nidulans and the data support Pontecorvo's (1958) suggestion that the parasexual cycle can be a substantial alternative to the sexual cycle.

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Recombination block in the Spore killer region of Neurospora

Genome ◽

10.1139/g87-022 ◽

1987 ◽

Vol 29 (1) ◽

pp. 129-135 ◽

Cited By ~ 28

Author(s):

Joseph L. Campbell ◽

Barbara C. Turner

Keyword(s):

Linkage Group ◽

Chromosome Rearrangement ◽

Meiotic Drive ◽

Structural Basis ◽

Crossing Over ◽

Homologous Pairing ◽

Group Iii ◽

Normal Crossing ◽

Selective Plating ◽

Spore Killer

Spore killers Sk-2K and Sk-3K are chromosomal meiotic drive factors in Neurospora. In heterozygous crosses, ascospores not contining the Spore killer die. Sk-2K and Sk-3K, which differ in killing specificity, were found to be associated with suppression of recombination in a centromere-spanning region of linkage group III, and investigation of that recombination block is reported here. The block covers a region that is normally 30 to 40 map units long. A locus (r(Sk-2)) conferring resistance to Sk-2K maps to the left end of the recombination block. Recombination is normal in r(Sk-2) × Sk sensitive but blocked in Sk-2K × r(Sk-2); so the block does not depend upon killing. By selective plating, SkK stocks carrying genetic markers within the block were obtained at frequencies on the order of 10−5 or 10−6. Since this tight block is far beyond what has been observed for genetic reduction of recombination, a structural basis is assumed. No evidence of chromosome rearrangement was obtained. Crosses homozygous for Sk-2K show normal crossing-over and map order for the flanking markers cum and his-7 and three included markers (acr-7, acr-2, and leu-1). Results would be consistent with a divergence of sequence great enough to interfere with homologous pairing. Key words: meiotic drive, Neurospora, crossover suppressor.

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