TABLE 2

Phenotypic and molecular characterization of msc mutants

Meiotic unequal
SCR frequency
(× 103)b
Fold
increase
Chromosome Vlll
segregation (%)c
Dyad
no.
Sporulation
(%)d
Spore
viability
(%)e
GenotypeaEqu.Red.Aber.
Wild type0.3 ± 0.02161152425142 ± 0.744
red1::ADE21.1 ± 0.153.6941517655 ± 0.775
homologueΔ1.7 ± 0.485.7NDND
Class I
    red1::TN+621.2 ± 0.154.095235841 ± 562
    red1::TN+1430.72 ± 0.082.4890114642 ± 544
    red1::TN+4111.1 ± 0.013.696137349 ± 361
    red1::TN+6210.9 ± 0.13.097126453 ± 559
    red1::TN+9531.2 ± 0.134.0941514054 ± 154
    red1::TN+12931.6 ± 0.35.3941515855 ± 363
    red1::TN+20751.3 ± 0.204.3902822453 ± 350
    red1::TN+ 21741.3 ± 0.094.3912710442 ± 274
    mek1::TN+ 9441.1 ± 0.13.693256053 ± 547
    hop1::LEU20.27 ± 0.020.9900105256 ± 567
    rad24Δ0.68 ± 0.062.3900102042 ± 343
    rad24::TN+ 3421.5 ± 0.155.089299744 ± 741
    rad24::TN+ 3851.0 ± 0.093.390198142 ± 347
    rad24::TN+ 5091.4 ± 0.234.7835126655 ± 253
    rad24::TN+ 5851.0 ± 0.113.3871127742 ± 141
    rad24::TN+ 6141.0 ± 0.013.391189741 ± 336
    rad24::TN+ 6251.8 ± 0.146.0779145841 ± 142
    rad24::TN+ 8011.4 ± 0.164.7890116337 ± 739
    rad24::TN+13461.1 ± 0.063.693076247 ± 153
    mec3::TN+11520.84 ± 0.052.891187631 ± 144
    yor354c: TN+1608 (MSC6)1.4 ± 0.234.7783203130 ± 135
    609f0.86 ± 0.052.995233844 ± 0.547
    133f1.4 ± 0.194.78731010545 ± 154
    85f1.3 ± 0.074.3828103932 ± 537
    rad17Δ0.66 ± 0.032.291363227 ± 140
    mec1-10.20 ± 0.040.725 ± 9<0.1
    rad24Δ red1::ADE20.59 ± 0.022.098026134 ± 157
    spo11Δ0.001 ± 0.0009ND55 ± 7ND
    spo11Δ red1::ADE20.002 ± 0.0004ND52 ± 2ND
    spo11Δ rad24Δ0.001 ± 0.0006ND49 ± 3ND
Class II
    dmc1Δ0.86 ± 0.062.994601744 ± 327
    dmc1Δ red1::ADE21.72 ± 0.015.791093250 ± 361
    inp52::TN+ 2770.87 ± 0.052.9100004645 ± 348
    yml128cTN+1531 (MSC1)0.86 ± 0.092.999018161 ± 150
    ela1::TN>216 (MSC4)1.0 ± 0.13.38911015341 ± 146
    ylr219w::TN+ 751 (MSC3)0.83 ± 0.072.8100003734 ± 235
    bud3::TN+ 2396g1.2 ± 0.134.095059469 ± 555
    pet122::TN+ 593g1.8 ± 0.156.0762226412 ± 148
    ubr1::TN+330h0.82 ± 0.062.797127551 ± 243
    ubr1A0.18 ± 0.010.6ND59 ± 2ND
    ydr205w:: TN+1255 (MSC2)h1.2 ± 0.14.0100006552 ± 140
    360.41h1.3 ± 0.094.399017843 ± 549
    471h1.5 ± 0.095.0960410834 ± 334 ± 2
    227g1.4 ± 0.124.795056536 ± 354
Class III
    yhr039c::TN+1583 (MSC7)g0.65 ± 0.102.2751694336 ± 242
    mnr2::TN+ 1766g1.0 ± 0.123.36515205540 ± 332
    625f1.5 ± 0.195.057232010940 ± 250
    455f0.91 ± 0.133.05227215242 ± 332
    116-42f0.53 ± 0.031.84621334335 ± 533
    1589g1.1 ± 0.083.66223158642 ± 238
  • —, The experiment is not applicable to a particular genotype. ND, not determined.

  • a The symbol TN+ designates the transposon insertion position relative to the translational start site ATG +1 for each mutant allele, and TN> denotes an insertion position upstream of the ATG +1 site of the designated gene. The locus designation listed in the S. cerevisiae genome database is denoted for all previously uncharacterized (MSC) genes. The ± symbol denotes standard error.

  • b To determine the frequency of meiotic unequal SCR, yeast strains were grown to saturation in 2-ml cultures of YEPEG. The entire culture was then used to inoculate 100 ml S-raffinose + 5-FOA (0.1%) and incubated for ~36 hr to select against mitotic SCR recombinants. Cells were pelleted, washed twice with sterile water, and diluted 1:4 in liquid sporulation medium. Aliquots were washed twice in 250 mm EDTA, pH 8.0, followed by two washes in sterile H2O, and then plated on SD-Ura-Arg-Trp + 240 (μm CuSO4 · 5H2O and YEPD medium to determine mitotic unequal SCR frequency per viable cell. Cultures were aerated for 3 days to induce sporulation, and meiotic unequal SCR frequency was determined as described above. All incubations were at 30°. At least three independent colonies were assayed for each strain. As a result of 5-FOA counterselection, the frequency of mitotic unequal SCR was negligible in all experiments (data not shown).

  • c Segregation of the ARG4 and TRP1 markers, integrated on each homologue, ~2 cM from CEN 8, was used to determine the frequency of reductional, equational, or aberrant segregations in each strain. Reductional segregation resulted in a dyad containing one Arg+ Trp- and one Arg- Trp+ spore. In an equational segregation, both spores are Arg+ Trp+. Aberrant segregations give rise to dyads containing either one Arg+ Trp- and one Arg+ Trp+ or one Arg- Trp+ and one Arg+ Trp+ spore (Figure 1). Only dyads with two viable spores were included in these data. The frequency of equational segregation was significantly different from DT71 (WT, P < 0.01 to < 0.001) in all class I and II mutant strains, with the exception of the dmc1Δ (P < 0.05), rad24Δ, and yor354c::TN+1608 (MSC6) strains. At their current size, the data sets for rad24Δ and yor354c::TN+1608 are not significantly different from DT71 (P > 0.08). In addition, the frequency of reductional segregation in the current data sets for the class III mutant strains is not significantly different from that in DT71 (P > 0.08). The paucity of two-spore viable dyads produced impedes the analysis (see results).

  • d Sporulation percentage was calculated from a minimum of 200 individual cells plus asci.

  • e Spore viability was calculated from a minimum of 120 individual spores.

  • f The mutant phenotype not linked to transposon insertion.

  • g Linkage of the mutant phenotype to the transposon insertion not yet confirmed.

  • h Deletion of the ORF did not result in msc phenotype.