Ascocarp ultrastructure of Herpomyces sp. (Laboulbeniales) and its phylogenetic implications

1977 ◽  
Vol 55 (15) ◽  
pp. 2015-2032 ◽  
Author(s):  
Terry W. Hill
Keyword(s):  
Red Algae ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Spore Wall ◽  
Wall Formation ◽  
Pole Body ◽  
Phylogenetic Implications ◽  
Close Relationship

The asci of Herpomyces sp. (Laboulbeniales) compose a parenchymatous tissue produced by progressive cleavage of three or four meristematic ascogenous cells attached in the base of the ascocarp. Ascospores are delimited by membranes derived from an ascus vesicle, and the spore wall forms between paired prospore membranes. Dilated cisternae and epiplasmic membranes are associated with wall formation. While ascospores are developing, asci are displaced apically, their passage apparently lubricated by a matrix secreted by the peridial cells.The presence of an ascomycetous spindle pole body, septal pore with Woronin bodies, ascus vesicle, and dilated Golgi-like cisternae indicates a close relationship between Herpomyces sp. and the filamentous Ascomycetes while providing no support for theories maintaining a close relationship between Laboulbeniales and the red algae.

scholarly journals Mps1p Regulates Meiotic Spindle Pole Body Duplication in Addition to Having Novel Roles during Sporulation

2000 ◽  
Vol 11 (10) ◽  
pp. 3525-3537 ◽  
Author(s):  
Paul D. Straight ◽  
Thomas H. Giddings ◽  
Mark Winey
Keyword(s):  
Chromosome Segregation ◽  
Spindle Assembly Checkpoint ◽  
Spindle Pole Body ◽  
Class Ii ◽  
Spindle Pole ◽  
Spore Wall ◽  
Meiotic Spindle ◽  
Restrictive Temperature ◽  
Wall Formation ◽  
Pole Body

Sporulation in yeast requires that a modified form of chromosome segregation be coupled to the development of a specialized cell type, a process akin to gametogenesis. Mps1p is a dual-specificity protein kinase essential for spindle pole body (SPB) duplication and required for the spindle assembly checkpoint in mitotically dividing cells. Four conditional mutant alleles of MPS1disrupt sporulation, producing two distinct phenotypic classes. Class I alleles of mps1 prevent SPB duplication at the restrictive temperature without affecting premeiotic DNA synthesis and recombination. Class II MPS1 alleles progress through both meiotic divisions in 30–50% of the population, but the asci are incapable of forming mature spores. Although mutations in many other genes block spore wall formation, the cells produce viable haploid progeny, whereas mps1 class II spores are unable to germinate. We have used fluorescently marked chromosomes to demonstrate that mps1 mutant cells have a dramatically increased frequency of chromosome missegregation, suggesting that loss of viability is due to a defect in spindle function. Overall, our cytological data suggest that MPS1 is required for meiotic SPB duplication, chromosome segregation, and spore wall formation.

Ady3p Links Spindle Pole Body Function to Spore Wall Synthesis in Saccharomyces cerevisiae

Genetics ◽  
2002 ◽  
Vol 160 (4) ◽  
pp. 1439-1450
Author(s):  
Mark E Nickas ◽  
Aaron M Neiman
Keyword(s):  
Saccharomyces Cerevisiae ◽  
De Novo ◽  
Spindle Pole Body ◽  
Leading Edge ◽  
Spindle Pole ◽  
Spore Wall ◽  
Pole Body ◽  
Prospore Membrane ◽  
Sporulation Efficiency ◽  
Spore Walls

Abstract Spore formation in Saccharomyces cerevisiae requires the de novo synthesis of prospore membranes and spore walls. Ady3p has been identified as an interaction partner for Mpc70p/Spo21p, a meiosis-specific component of the outer plaque of the spindle pole body (SPB) that is required for prospore membrane formation, and for Don1p, which forms a ring-like structure at the leading edge of the prospore membrane during meiosis II. ADY3 expression has been shown to be induced in midsporulation. We report here that Ady3p interacts with additional components of the outer and central plaques of the SPB in the two-hybrid assay. Cells that lack ADY3 display a decrease in sporulation efficiency, and most ady3Δ/ady3Δ asci that do form contain fewer than four spores. The sporulation defect in ady3Δ/ady3Δ cells is due to a failure to synthesize spore wall polymers. Ady3p forms ring-like structures around meiosis II spindles that colocalize with those formed by Don1p, and Don1p rings are absent during meiosis II in ady3Δ/ady3Δ cells. In mpc70Δ/mpc70Δ cells, Ady3p remains associated with SPBs during meiosis II. Our results suggest that Ady3p mediates assembly of the Don1p-containing structure at the leading edge of the prospore membrane via interaction with components of the SPB and that this structure is involved in spore wall formation.

The fine structure of ascospore delimitation in the yeast Wickerhamia fluorescens

1973 ◽  
Vol 19 (11) ◽  
pp. 1389-1392 ◽  
Author(s):  
Lynn Rooney ◽  
Peter B. Moens
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Fine Structure ◽  
Outer Membrane ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Spore Wall ◽  
Serial Sections ◽  
Spore Body ◽  
Pole Body ◽  
Spindle Pole Bodies

Photographic records of complete serial sections of asci in different stages of sporulation show that one of the four nuclear lobes produced during meiosis in the ascus of the yeast Wickerhamia fluorescens has a complex spindle-pole body, which is the site from where the presumptive ascospore wall, or prospore wall, develops and eventually surrounds the ascospore nucleus and associated cytoplasm. The three remaining nuclei develop spindle-pole bodies and prospore walls to lesser and varying degrees. With few exceptions, all three degenerate. The outer membrane of the prospore wall forms a fold, or rim, on the outside of the spore. Thickening of the spore wall takes place first in the asymmetric ring, then around the spore body, and finally at the site where the nucleus is associated with the wall. It is shown that ascospore delimitation in W. fluorescens and Saccharomyces cerevisiae are similar to each other, and that it differs from the type observed in a number of Euascomycetes.

scholarly journals Fission Yeast Mutants Affecting Telomere Clustering and Meiosis-Specific Spindle Pole Body Integrity

Genetics ◽  
2002 ◽  
Vol 160 (3) ◽  
pp. 861-876
Author(s):  
Ye Jin ◽  
Satoru Uzawa ◽  
W Z Cande
Keyword(s):  
Fission Yeast ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Specific Protein ◽  
Spore Wall ◽  
Isolation And Characterization ◽  
Pole Body ◽  
Homologous Chromosome Pairing ◽  
Eukaryotic Organisms ◽  
And Function

Abstract In meiotic prophase of many eukaryotic organisms, telomeres attach to the nuclear envelope and form a polarized configuration called the bouquet. Bouquet formation is hypothesized to facilitate homologous chromosome pairing. In fission yeast, bouquet formation and telomere clustering occurs in karyogamy and persists throughout the horsetail stage. Here we report the isolation and characterization of six mutants from our screen for meiotic mutants. These mutants show defective telomere clustering as demonstrated by mislocalization of Swi6::GFP, a heterochromatin-binding protein, and Taz1p::GFP, a telomere-specific protein. These mutants define four complementation groups and are named dot1 to dot4—defective organization of telomeres. dot3 and dot4 are allelic to mat1-Mm and mei4, respectively. Immunolocalization of Sad1, a protein associated with the spindle pole body (SPB), in dot mutants showed an elevated frequency of multiple Sad1-nuclei signals relative to wild type. Many of these Sad1 foci were colocalized with Taz1::GFP. Impaired SPB structure and function were further demonstrated by failure of spore wall formation in dot1, by multiple Pcp1::GFP signals (an SPB component) in dot2, and by abnormal microtubule organizations during meiosis in dot mutants. The coincidence of impaired SPB functions with defective telomere clustering suggests a link between the SPB and the telomere cluster.

scholarly journals PREFERENTIAL OCCURRENCE OF NONSISTER SPORES IN TWO-SPORED ASCI OF SACCHAROMYCES CEREVISIAE: EVIDENCE FOR REGULATION OF SPORE-WALL FORMATION BY THE SPINDLE POLE BODY

Genetics ◽  
1980 ◽  
Vol 94 (3) ◽  
pp. 581-595 ◽  
Author(s):  
Lance S Davidow ◽  
Loretta Goetsch ◽  
Breck Byers
Keyword(s):  
Spindle Pole Body ◽  
Electron Microscopic Examination ◽  
Spindle Pole ◽  
Spore Wall ◽  
Yeast Cells ◽  
Thermal Arrest ◽  
Electron Microscopic ◽  
Spore Yield ◽  
Pole Body ◽  
Spindle Pole Bodies

ABSTRACT Yeast cells subjected to a reversible thermal arrest of meiosis yielded progressively fewer spores per ascus as the arrest was extended. Dissection of two-spored asci by a newly developed method that prevents selection of false asci revealed that the spores were not a random sample of the haploid meiotic products. Most, if not all, pairs of spores contain nonsister products of the reductional division. Electron microscopic examination of the meiotic cells revealed the cytological basis for this bias. All four spindle pole bodies (SPBs) present at the second meiotic division normally gain a structural modification (the outer plaque) upon which the initiation of the prospore wall occurs. In the formation of a two-spored ascus, only one spindle pole body on each meiosis I1 spindle was so modified. These observations suggest that the morphogenesis of spcires is regulated at meiosis 11 by limiting the number of SPBs gaining the outer plaque. The enhancement of spore yield upon addition of fresh medium suggests that this morphogenetic regulation responds more directly to nutrient deprivation arising during the thermal arrest, rather than to elevated temperature per se.

Meiosis, septal pore architecture, and systematic position of the heterobasidiomycetous fern parasite Herpobasidium filicinum

1994 ◽  
Vol 72 (9) ◽  
pp. 1229-1242 ◽  
Author(s):  
Robert Bauer ◽  
Franz Oberwinkler
Keyword(s):  
Nuclear Division ◽  
Light And Electron Microscopy ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Systematic Position ◽  
Pole Body ◽  
Phylogenetic Implications ◽  
Septal Pores ◽  
Unusual Type ◽  
Nuclear Features

Meiosis, spindle pole body cycle and septal pores in Herpobasidium filicinum were examined using light and electron microscopy and compared with findings in the Uredinales and other simple-pored heterobasidiomycetes. The septal pore apparatus in Herpobasidium filicinum is rustlike, and the nuclear characteristics are also similar but not identical to those found in the Uredinales. Some details, such as the spindle pole body behaviour at prophase, the presence of a complete wrapping of endoplasmic reticulum surrounding the nucleus during division, the extension of the spindle pole body into the cytoplasm during division, and the nucleolus behaviour, distinguish Herpobasidium filicinum from the rusts. On the other hand, nuclear division and spindle pole body characteristics in Herpobasidium filicinum show some features common with Cryptomycocolax abnorme. However, Herpobasidium filicinum shares more important nuclear features with Pachnocybe ferruginea, Eocronartium muscicola, Helicobasidium mompa, and Helicobasidium brebissonii than with the Uredinales or Cryptomycocolacales. Apart from the phylogenetic implications of the ultrastructural data, the most interesting observation in the present work is the unusual type of meiosis. No evidence for meiosis II was found in basidia of Herpobasidium filicinum. Instead, the genesis of the interphase I spindle pole body in Herpobasidium filicinum is essentially identical to the basidiomycetous postmeiotic and intermitotic spindle pole body duplication. Key words: Herpobasidium filicinum, heterobasidiomycetes, meiosis, septal pore, spindle pole body, ultrastructure.

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