Spore movement driven by the spore wall in an eusporangiate fern

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.

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Characterization of the mbsA Gene Encoding a Putative APSES Transcription Factor in Aspergillus fumigatus

International Journal of Molecular Sciences ◽

10.3390/ijms22073777 ◽

2021 ◽

Vol 22 (7) ◽

pp. 3777

Author(s):

Yong-Ho Choi ◽

Sang-Cheol Jun ◽

Min-Woo Lee ◽

Jae-Hyuk Yu ◽

Kwang-Soo Shin

Keyword(s):

Aspergillus Fumigatus ◽

Pathogenic Fungus ◽

Hyphal Growth ◽

Spore Wall ◽

Mrna Levels ◽

Chitin Synthesis ◽

Helix Loop Helix ◽

Growth Development ◽

Opportunistic Pathogenic

The APSES family proteins are transcription factors (TFs) with a basic helix-loop-helix domain, known to regulate growth, development, secondary metabolism, and other biological processes in Aspergillus species. In the genome of the human opportunistic pathogenic fungus Aspergillus fumigatus, five genes predicted to encode APSES TFs are present. Here, we report the characterization of one of these genes, called mbsA (Afu7g05620). The deletion (Δ) of mbsA resulted in significantly decreased hyphal growth and asexual sporulation (conidiation), and lowered mRNA levels of the key conidiation genes abaA, brlA, and wetA. Moreover, ΔmbsA resulted in reduced spore germination rates, elevated sensitivity toward Nikkomycin Z, and significantly lowered transcripts levels of genes associated with chitin synthesis. The mbsA deletion also resulted in significantly reduced levels of proteins and transcripts of genes associated with the SakA MAP kinase pathway. Importantly, the cell wall hydrophobicity and architecture of the ΔmbsA asexual spores (conidia) were altered, notably lacking the rodlet layer on the surface of the ΔmbsA conidium. Comparative transcriptomic analyses revealed that the ΔmbsA mutant showed higher mRNA levels of gliotoxin (GT) biosynthetic genes, which was corroborated by elevated levels of GT production in the mutant. While the ΔmbsA mutant produced higher amount of GT, ΔmbsA strains showed reduced virulence in the murine model, likely due to the defective spore integrity. In summary, the putative APSES TF MbsA plays a multiple role in governing growth, development, spore wall architecture, GT production, and virulence, which may be associated with the attenuated SakA signaling pathway.

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The role of NbTMP1, a surface protein of sporoplasm, in Nosema bombycis infection

Parasites & Vectors ◽

10.1186/s13071-021-04595-8 ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Shiyi Zheng ◽

Yukang Huang ◽

Hongyun Huang ◽

Bin Yu ◽

Ni Zhou ◽

...

Keyword(s):

Indirect Immunofluorescence ◽

Selective Breeding ◽

Developmental Stages ◽

Transmembrane Protein ◽

Surface Protein ◽

Spore Wall ◽

Significant Inhibition ◽

Pcr Analysis ◽

Immunofluorescence Analysis ◽

Nosema Bombycis

Abstract Background Nosema bombycis is a unicellular eukaryotic pathogen of the silkworm, Bombyx mori, and is an economic and occupational hazard in the silkworm industry. Because of its long incubation period and horizontal and vertical transmission, it is subject to quarantine measures in sericulture production. The microsporidian life-cycle includes a dormant extracellular phase and intracellular proliferation phase, with the proliferation period being the most active period. This latter period lacks spore wall protection and may be the most susceptible stage for control. Methods In order to find suitable target for the selective breeding of N. bombycis-resistant silkworm strains, we screen highly expressed membrane proteins from the transcriptome data of N. bombycis. The subcellular localization of the candidate protein was verified by Indirect immunofluorescence analysis (IFA) and immunoelectron microscopy (IEM), and its role in N. bombycis proliferation was verified by RNAi. Results The N. bombycis protein (NBO_76g0014) was identified as a transmembrane protein and named NbTMP1. It is homologous with hypothetical proteins NGRA_1734 from Nosema granulosis. NbTMP1 has a transmembrane region of 23 amino acids at the N-terminus. Indirect immunofluorescence analysis (IFA) results suggest that NbTMP1 is secreted on the plasma membrane as the spores develop. Western blot and qRT-PCR analysis showed that NbTMP1 was expressed in all developmental stages of N. bombycis in infected cells and in the silkworm midgut. Downregulation of NbTMP1 expression resulted in significant inhibition of N. bombycis proliferation. Conclusions We confirmed that NbTMP1 is a membrane protein of N. bombycis. Reduction of the transcription level of NbTMP1 significantly inhibited N. bombycis proliferation, and this protein may be a target for the selective breeding of N. bombycis-resistant silkworm strains.

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Spore wall proteins of Plasmodiophora brassicae

Transactions of the British Mycological Society ◽

10.1016/s0007-1536(83)80046-1 ◽

1983 ◽

Vol 80 (3) ◽

pp. 497-506 ◽

Cited By ~ 7

Author(s):

Susan E. Moxham ◽

R.S.S. Fraser ◽

S.T. Buczacki

Keyword(s):

Plasmodiophora Brassicae ◽

Spore Wall

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Ultrastructure and development of urediospore ornamentation in Melampsora lini

Canadian Journal of Botany ◽

10.1139/b71-291 ◽

1971 ◽

Vol 49 (12) ◽

pp. 2067-2073 ◽

Cited By ~ 26

Author(s):

L. J. Littlefield ◽

C. E. Bracker

Keyword(s):

Endoplasmic Reticulum ◽

Plasma Membrane ◽

Outer Surface ◽

Spore Wall ◽

Wall Material ◽

Wild Type ◽

Melampsora Lini ◽

Inner Surface ◽

External Position ◽

Basal Portion

The urediospores of Melampsora lini (Ehrenb.) Lev. are echinulate, with spines ca. 1 μ long over their surface. The spines are electron-transparent, conical projections, with their basal portion embedded in the electron-dense spore wall. The entire spore, including the spines, is covered by a wrinkled pellicle ca. 150–200 Å thick. The spore wall consists of three recognizable layers in addition to the pellicle. Spines form initially as small deposits at the inner surface of the spore wall adjacent to the plasma membrane. Endoplasmic reticulum occurs close to the plasma membrane in localized areas near the base of spines. During development, the spore wall thickens, and the spines increase in size. Centripetal growth of the wall encases the spines in the wall material. The spines progressively assume a more external position in the spore wall and finally reside at the outer surface of the wall. A mutant strain with finely verrucose spores was compared to the wild type. The warts on the surface of the mutant spores are rounded, electron-dense structures ca. 0.2–0.4 μ high, in contrast to spines of the wild type. Their initiation near the inner surface of the spore wall and their eventual placement on the outer surface of the spore are similar to that of spines. The wall is thinner in mutant spores than in wild-type spores.

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