Eight-spore legends
Fig 1. Schematic diagram of ascus development in N. tetrasperma. A. Anaphase I.
Alleles of a centromere-linked gene (e.g. mat A and mat a) segregate at the first
division of meiosis. B. Telophase II. The two second-division spindles overlap, and are
aligned nearly parallel to one another along the long axis of the ascus. C. Interphase II.
The nuclei in each proximal and distal half ascus are non-sisters arising from different
spindles. D. Telophase III. The spindles are again aligned in pairs in each half ascus.
E. Interphase III. The eight nuclei are aligned in four pairs, all lined up in single file. F.
The four pairs of nuclei (A + a) become enclosed in each of the four ascospores. G. A
mitosis in young ascospores results in four nuclei per ascospore. Additional mitoses
occur in mature black ascospores. (From Raju and Burk, 2004, Fung. Genet. Biol. 41:
582-589.)
Fig 2. Ascus development in wild type N. tetrasperma. A. Anaphase III. Condensed
chromosomes are segregating on the two spindles that are aligned across each half
ascus. B. Interphase III, at about ascospore delimitation. C. An ascus with four, young,
binucleate ascospores. D. Two four-spored asci following a mitosis in the ascospores.
E. A partial rosette of maturing asci. (Ascus development in wild type x bud is similar to
that in wild type x wild type.) Scale bars in A-D = 10 m, E = 100 m. (From Raju and
Burk, 2004, Fung. Genet. Biol. 41: 582-589.)
Fig 3. E x Wild type. A rosette of 4 to 8-spored asci. In 5 to 8-spored asci, one or more
large, heterokaryotic ascospores are replaced by pairs of small, homokaryotic
ascospores. E shows variable penitrance when heterozygous, but most of the asci abort
when E is homozygous. (From Raju, 1992, Mycol. Res. 96, 103-116.)
Fig 4. E Sk-3 x WT. A rosette of asci showing the effect of Sk-3 on the eight-spored
phenotype of E. Most of the asci contain 6-8 ascospores. (Photo by N.B. Raju.)
Fig 5. E Sk-3 x Sk-3. An ascus showing normal metaphase I. The spindle is aligned
longitudinally, as in most wild-type N. tetrasperma strains. (Photo by N.B. Raju.)
Fig 6. E Sk-3 x WT. Metaphase I, showing the spindle, spindle pole bodies, condensed
chromosomes, and the nucleolus. (Photo by N.B. Raju.)
Fig 7. E Sk-3 x Sk-3. Telophase I. The segregated telophase chromosomes are at the
two poles; the old nucleolus and the spindle are still visible. (Photo by N.B. Raju.)
Fig 8. E Sk-3 x Sk-3. Metaphase II. An ascus showing partially overlapping spindles.
(From Raju 1992, Mycol. Res. 96: 103-116.)
Fig 9. E Sk-3 x Sk-3. Metaphase II. An ascus showing slightly overlapping spindles.
(Photo by N.B. Raju.)
Fig 10. E Sk-3 x Sk-3. Metaphase II. An ascus showing non-overlapping, tandem
spindles. The two spindles are aligned closer than those in N. crassa, however. (Photo
by N.B. Raju.)
Fig 11. E Sk-3 x WT. Anaphase II. The two non-overlapping spindles are aligned in
tandem. (Photo by N.B. Raju.)
Fig 12. E Sk-3 x Sk-3. Metaphase III. The four spindles at the first postmeiotic mitosis
are not aligned in pairs. Instead, they are aligned nearly equidistant and across the
ascus, similar to the spindles in N. crassa. (Photo by N.B. Raju.)
Fig 13. E Sk-3 x Sk-3. Metaphase III. The four spindles are aligned irregularly, relative
to one another. (Photo by N.B. Raju.)
Fig 14. E Sk-3 x Sk-3. Interphase III, prior to spore delimitation. The eight nuclei fail to
associate in pairs or align in single file, and are expected to cut out mostly uninucleate
ascospores. (Photo by N.B. Raju.)
Fig 15. E Sk-3 x Sk-3. Interphase III, prior to spore delimitation. The eight nuclei fail to
associate in pairs or align in single file, and are expected to cut out mostly uninucleate
ascospores. (From Raju, 1992, Mycol. Res. 96, 103-116.)
Fig 16. E x Sk-2. Immature asci showing 5-8 ascospores; in these asci, one or more
large ascospores are replaced by pairs of small ascospores. (Photo by N.B. Raju.)
Fig 17. E x Sk-2. A five-spored ascus shortly, after spore delimitation; a single large
ascospore is replaced by a pair of small uninucleate ascospores. The remaining three
large ascospores are binucleate. (Photo by N.B. Raju.)
Fig 18. E x Sk-2. A seven-spored ascus, shortly after spore delimitation. Only a single
ascospore is large and binucleate; the remaining six ascospores are small and
uninucleate. (Photo by N.B. Raju.)
Fig 19. E x Sk-2. An 8-spored ascus following a mitosis in the young ascospores, but
prior to the death of four of the eight ascospores that do not carry Sk-2. (Photo by N.B.
Raju.)
Fig 20. E x Sk-2. An 8-spored ascus following a mitosis in the young ascospores, but
prior to the death of four of the eight ascospores that do not carry Sk-2. (From Raju,
1992, Mycol. Res. 96, 103-116.)
Fig 21. E Sk-3 x Sk-3. Three asci, showing metaphase II (top), four binucleate
ascospores (middle), and an elongated ascus that has just cut out eight uninucleate
ascospores (bottom). (From Raju, 1992, Mycol. Res. 96, 103-116.)
Fig 22. E x WT. Four- to eight-spored asci. The ascospores in the top four-spored
ascus are expected to be heterokaryotic for mating type and self-fertile, where as the
smaller ascospores in the bottom eight-spored ascus will be homokaryotic and selfsterile. Note the size-difference of mature ascospores in the four- and eight-spored asci.
The middle immature ascus contains two large ascospores and four small ascospores.
(Photo by N.B. Raju.)
Fig 23. Wild type (female) x P655 (male). A rosette of four-spored asci from an
outcross, where the wild type was used as the protoperithecial parent. (Photo by N.B.
Raju.)
Fig 24. P655 (female) x Wild type (male). A rosette of eight-spored asci from the same
cross as that in Fig 23, but with P655 used as the protoperithecial parent. (Photo by
N.B. Raju.)