Expression of meiotic drive elements Spore killer-2 and Spore killer-3 in asci of Neurospora tetrasperma.

Abstract It was shown previously that when a chromosomal Spore killer factor is heterozygous in Neurospora species with eight-spored asci, the four sensitive ascospores in each ascus die and the four survivors are all killers. Sk-2K and Sk-3K are nonrecombining haplotypes that segregate with the centromere of linkage group III. No killing occurs when either one of these killers is homozygous, but each is sensitive to killing by the other in crosses of Sk-2K x Sk-3K. In the present study, Sk-2K and Sk-3K were transferred by recurrent backcrosses from the eight-spored species Neurospora crassa into Neurospora tetrasperma, a pseudohomothallic species which normally makes asci with four large spores, each heterokaryotic for mating type and for any other centromere-linked genes that are heterozygous in the cross. The action of Sk-2K and Sk-3K in N. tetrasperma is that predicted from their behavior in eight-spored species. A sensitive nucleus is protected from killing if it is enclosed in the same ascospore with a killer nucleus. Crosses of Sk-2K x Sk-2S, Sk-3K x Sk-3S, and Sk-sK x Sk-3K all produce four-spored asci that are wild type in appearance, with the ascospores heterokaryotic and viable. The Eight-spore gene E, which shows variable penetrance, was used to obtain N. tetrasperma asci in which two to eight spores are small and homokaryotic. When killer and sensitive alleles are segregating in the presence of E, only those ascospores that contain a killer allele survive. Half of the small ascospores are killed. In crosses of Sk-2K x Sk-3K (with E heterozygous), effectively all small ascospores are killed. The ability of N. tetrasperma to carry killer elements in cryptic condition suggests a possible role for Spore killers in the origin of pseudohomothallism, with adoption of the four-spored mode restoring ascospore viability of crosses in which killing would otherwise occur.

Download Full-text

Isolation of telomere DNA from Neurospora crassa

Molecular and Cellular Biology ◽

10.1128/mcb.7.9.3168-3177.1987 ◽

1987 ◽

Vol 7 (9) ◽

pp. 3168-3177

Author(s):

M G Schechtman

Keyword(s):

Linkage Group ◽

Neurospora Crassa ◽

Genetic Background ◽

Type Strain ◽

Wild Type Strain ◽

The Other ◽

Wild Type ◽

Oak Ridge ◽

Entire Chromosome ◽

Different Genetic Background

The most distal known gene on Neurospora crassa linkage group VR, his-6, was cloned. A genomic walk resulted in isolation of the telomere at VR. It was obtained from a library in which the endmost nucleotides of the chromosome had not been removed by nuclease treatment before being cloned, and mapping indicates that the entire chromosome end has probably been cloned. Sequences homologous to the terminal 2.5 kilobases of DNA from VR from these Oak Ridge N. crassa strains are found at other sites in the genome. To characterize these sites, I crossed an Oak Ridge-derived his-6 strain with a wild-type strain of different genetic background (Mauriceville) and characterized the hybridization patterns seen in the progeny. It appears that the sequences homologous to the VR terminus are found at genetically different sites in the two parental strains, and no hybridization to the VR telomere from Mauriceville was detected. The other genomic copies identified in the Oak Ridge parent were not telomeres. I suggest that any repeating sequence blocks found immediately adjacent to the VR terminus in Oak Ridge strains must be small and that the repeating element identified in that background may be an N. crassa transposable element integrated near the the chromosome end at VR.

Download Full-text

GENETIC AND PHYSIOLOGICAL CHARACTERISTICS OF A SLOW-GROWING CIRCADIAN CLOCK MUTANT OF NEUROSPORA CRASSA

Genetics ◽

10.1093/genetics/88.2.255 ◽

1978 ◽

Vol 88 (2) ◽

pp. 255-265

Author(s):

Jerry F Feldman ◽

Cheryl A Atkinson

Keyword(s):

Linkage Group ◽

Circadian Clock ◽

Neurospora Crassa ◽

Double Mutant ◽

Slow Growth ◽

Period Length ◽

The Other ◽

Wild Type ◽

Long Period ◽

Clock Mutant

ABSTRACT A circadian clock mutant of Neurospora crassa with a period length of about 25.8 hours (4 hr longer than wild type) has been isolated after mutagenesis of the band strain. This mutant, called frq-5, segregates as a single nuclear gene, maps near the centromere on linkage group III, and is unlinked to four previously described clock mutants clustered on linkage group VII R (Feldman and Hoyle 1973, 1976). frq-5 differs from the other clock mutants in at least two other respects: (1) it is recessive in heterokaryons, and (2) it grows at about 60% the rate of the parent band strain on both minimal and complete media. Double mutants between frq-5 and each of the other clock mutants show additivity of period length-two long period mutants produce a double mutant whose period length is longer than either of the two single mutants, while a long and a short period double mutant has an intermediate period length. Although slow growth and long periodicity of frq-5 have segregated together among more than 300 progeny, slow growth per se is not responsible for the long period, since all the double mutants have the slow growth characteristic of frq-5, but have period lengths both shorter and longer than wild type.

Download Full-text

Spore-Killing Meiotic Drive Factors in a Natural Population of the Fungus Podospora anserina

Genetics ◽

10.1093/genetics/156.2.593 ◽

2000 ◽

Vol 156 (2) ◽

pp. 593-605 ◽

Cited By ~ 4

Author(s):

Marijn van der Gaag ◽

Alfons J M Debets ◽

Jessica Oosterhof ◽

Marijke Slakhorst ◽

Jessica A G M Thijssen ◽

...

Keyword(s):

Linkage Group ◽

The Netherlands ◽

Natural Population ◽

Local Population ◽

Meiotic Drive ◽

Podospora Anserina ◽

Group Iii ◽

Spore Killing ◽

Different Types ◽

Spore Killer

Abstract In fungi, meiotic drive is observed as spore killing. In the secondarily homothallic ascomycete Podospora anserina it is characterized by the abortion of two of the four spores in the ascus. We have identified seven different types of meiotic drive elements (Spore killers). Among 99 isolates from nature, six of these meiotic drive elements occurred in a local population. Spore killers comprise 23% of the natural population of P. anserina in Wageningen, The Netherlands, sampled from 1991 to 1997. One Spore-killer type was also found in a French strain dating from 1937. All other isolates found so far are sensitive to spore killing. All seven Spore killer types differ in the percentage of asci that show killing and in their mutual interactions. Interactions among Spore killer types showed either mutual resistance or dominant epistasis. Most killer elements could be assigned to linkage group III but are not tightly linked to the centromere.

Download Full-text

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.

Download Full-text

Isolation of telomere DNA from Neurospora crassa.

Molecular and Cellular Biology ◽

10.1128/mcb.7.9.3168 ◽

1987 ◽

Vol 7 (9) ◽

pp. 3168-3177 ◽

Cited By ~ 24

Author(s):

M G Schechtman

Keyword(s):

Linkage Group ◽

Neurospora Crassa ◽

Genetic Background ◽

Type Strain ◽

Wild Type Strain ◽

The Other ◽

Wild Type ◽

Oak Ridge ◽

Entire Chromosome ◽

Different Genetic Background

Download Full-text

COMPLEMENTATION ANALYSIS OF LINKED CIRCADIAN CLOCK MUTANTS OF NEUROSPORA CRASSA

Genetics ◽

10.1093/genetics/82.1.9 ◽

1976 ◽

Vol 82 (1) ◽

pp. 9-17 ◽

Cited By ~ 3

Author(s):

Jerry F Feldman ◽

Marian N Hoyle

Keyword(s):

Linkage Group ◽

Circadian Clock ◽

Neurospora Crassa ◽

Period Length ◽

Complementation Analysis ◽

Wild Type ◽

The Right

ABSTRACT A fourth mutant of Neurospora crassa, designated frq-4, has been isolated in which the period length of the circadian conidiation rhythm is shortened to 19.3 ± 0.3 hours. This mutant is tightly linked to the three previously isolated frq mutants, and all four map to the right arm of linkage group VII about 10 map units from the centromere. Complementation tests suggest, but do not prove, that all four mutations are allelic, since each of the four mutants is co-dominant with the frq + allele—i.e., heterokaryons have period lengths intermediate between the mutant and wild-type—and since heterokaryons between pairs of mutants also have period lengths intermediate between those of the two mutants.

Download Full-text

DOMINANT-AND-RECESSIVE EPISTASIS IN A HOMEOTIC MOSQUITO MUTANT

Canadian Journal of Genetics and Cytology ◽

10.1139/g76-072 ◽

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.

Download Full-text

Immunological identification of the alternative oxidase of Neurospora crassa mitochondria.

Molecular and Cellular Biology ◽

10.1128/mcb.9.3.1362 ◽

1989 ◽

Vol 9 (3) ◽

pp. 1362-1364 ◽

Cited By ~ 66

Author(s):

A M Lambowitz ◽

J R Sabourin ◽

H Bertrand ◽

R Nickels ◽

L McIntosh

Keyword(s):

Neurospora Crassa ◽

Oxidase Activity ◽

Hydroxamic Acid ◽

Alternative Oxidase ◽

Fungal Species ◽

The Other ◽

Wild Type ◽

Higher Plant ◽

Sauromatum Guttatum ◽

Immunological Identification

Neurospora crassa mitochondria use a branched electron transport system in which one branch is a conventional cytochrome system and the other is an alternative cyanide-resistant, hydroxamic acid-sensitive oxidase that is induced when the cytochrome system is impaired. We used a monoclonal antibody to the alternative oxidase of the higher plant Sauromatum guttatum to identify a similar set of related polypeptides (Mr, 36,500 and 37,000) that was associated with the alternative oxidase activity of N. crassa mitochondria. These polypeptides were not present constitutively in the mitochondria of a wild-type N. crassa strain, but were produced in high amounts under conditions that induced alternative oxidase activity. Under the same conditions, mutants in the aod-1 gene, with one exception, produced apparently inactive alternative oxidase polypeptides, whereas mutants in the aod-2 gene failed to produce these polypeptides. The latter findings support the hypothesis that aod-1 is a structural gene for the alternative oxidase and that the aod-2 gene encodes a component that is required for induction of alternative oxidase activity. Finally, our results indicate that the alternative oxidase is highly conserved, even between plant and fungal species.

Download Full-text

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.

Download Full-text

Interrelationships in trace-element metabolism in metal toxicities in nickel-resistant strains of Neurospora crassa

Biochemical Journal ◽

10.1042/bj2120205 ◽

1983 ◽

Vol 212 (1) ◽

pp. 205-210 ◽

Cited By ~ 21

Author(s):

P Maruthi Mohan ◽

K Sivarama Sastry

Keyword(s):

Neurospora Crassa ◽

Metal Ion ◽

Type Strain ◽

Heavy Metal Ions ◽

Wild Type Strain ◽

The Other ◽

Wild Type ◽

Resistant Strains ◽

Trace Element Metabolism ◽

Very High

Three different Ni2+-resistant strains of Neurospora crassa (NiR1, NiR2 and NiR3) have been isolated. All are stable mutants and are fourfold more resistant to Ni2+ than the parent wild-type strain. NiR1 and NiR2 are also sixfold more resistant to Co2+, whereas NiR3 is only twice as resistant to Co2+; the former two are also twofold more resistant to Zn2+, but NiR3 is not. These three strains also differ in sensitivity to Cu2+. Toxicities and concomitant accumulation patterns of Ni2+, Co2+ and Cu2+ have been examined in these strains. NiR1 and NiR2, despite quantitative individual differences, generally accumulate very high amounts of Ni2+ and Co2+, and Mg2+ reverses the toxicities of these two ions by different mechanisms; Ni2+ uptake is suppressed, but not that of Co2+. In NiR3, Mg2+ controls uptake of both Ni2+ and Co2+. Studies indicate that two kinds of Ni2+-resistant strains of N. crassa exist; one kind is resistant because it can tolerate high intracellular concentrations of heavy-metal ions, whereas the other is resistant because it can control metal-ion accumulation.

Download Full-text