Topic
Hyphal tip
About: Hyphal tip is a research topic. Over the lifetime, 664 publications have been published within this topic receiving 25246 citations.
Papers published on a yearly basis
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Papers
TL;DR: There is an emerging body of work exploring the use of weaker expression promoters to avoid undue stress in fungal hosts, and exploration of the metabolic pathways and fluxes together with the development of sophisticated fermentation protocols may result in new strategies to produce recombinant proteins in filamentous fungi.
Abstract: Hosts used for the production of recombinant proteins are typically high-protein secreting mutant strains that have been selected for a specific purpose, such as efficient production of cellulose-degrading enzymes. Somewhat surprisingly, sequencing of the genomes of a series of mutant strains of the cellulolytic Trichoderma reesei, widely used as an expression host for recombinant gene products, has shed very little light on the nature of changes that boost high-level protein secretion. While it is generally agreed and shown that protein secretion in filamentous fungi occurs mainly through the hyphal tip, there is growing evidence that secretion of proteins also takes place in sub-apical regions. Attempts to increase correct folding and thereby the yields of heterologous proteins in fungal hosts by co-expression of cellular chaperones and foldases have resulted in variable success; underlying reasons have been explored mainly at the transcriptional level. The observed physiological changes in fungal strains experiencing increasing stress through protein overexpression under strong gene promoters also reflect the challenge the host organisms are experiencing. It is evident, that as with other eukaryotes, fungal ER is a highly dynamic structure. Considering the above, there is an emerging body of work exploring the use of weaker expression promoters to avoid undue stress. Filamentous fungi have been hailed as candidates for the production of pharmaceutically relevant proteins for therapeutic use. One of the biggest challenges in terms of fungally-produced heterologous gene products is their mode of glycosylation; fungi lack the functionally important terminal sialylation of the glycans that occurs in mammalian cells. Finally, exploration of the metabolic pathways and fluxes together with the development of sophisticated fermentation protocols may result in new strategies to produce recombinant proteins in filamentous fungi.
1,321 citations
TL;DR: Isolates established from single zoospores gave rise to as much variation in their asexual progenies as the original mass cultures, and subcultures established by single sporangia or single hyphal tips were much more uniform than zoospore cultures, although significant differences in growth rate could still be detected.
Abstract: The variability in culture of mycelial isolates of Phytophthora infestans was studied by examining the variation among single zoospore, single sporangium, and single hyphal tip subcultures. Extensi...
617 citations
TL;DR: The main changes observed under light and scanning electron microscopy after oil treatment were loss of cytoplasm in fungal hyphae, and budding of hyphal tip, and the hyphal wall and its diameter became markedly thinner, distorted and resulted in cell wall disruption.
394 citations
TL;DR: The ultrastructure of freeze-substituted tip cells of Fusarium acuminatum was analysed and it is suggested that cytoskeletal elements play important roles in localized cell wall formation and the filasome, a previously unreported type of coated vesicle in fungi, might be involved in wall synthesis.
Abstract: The ultrastructure of freeze-substituted tip cells of Fusarium acuminatum was analysed by conventional and high-voltage transmission electron microscopy (HVEM). At least 2 morphologically distinct types of Golgi-like endomembrane cisternae were observed, each existing as single, fenestrated sheets and tubular elements that were often very closely associated with mitochondria. From HVEM observations of thick (0.25 and 0.5 micron) sections, the Spitzenkorper appeared to correspond to an apical mass of vesicles. A network of microfilaments was identified among component vesicles of the Spitzenkorper and adjacent to developing septa. Microtubules were oriented primarily parallel to the direction of hyphal growth and were located in all areas of the cytoplasm, including the tip cell apex. Cytoplasmic vesicles were closely associated with these microtubules. From these observations it is suggested that cytoskeletal elements play important roles in localized cell wall formation. The filasome, a previously unreported type of coated vesicle in fungi, might also be involved in wall synthesis.
327 citations
TL;DR: The minimum effective concentration assay was related to inhibition of glucan synthase activity in vitro and may provide a starting point for development of susceptibility testing methods for lipopeptides.
Abstract: The lipopeptide antifungal agents, echinocandins, papulacandins, and pneumocandins, kill Candida albicans by inhibiting glucan synthesis. For this fungus, there is a good correlation of in vitro enzyme inhibition with in vitro assays of MICs. Semisynthetic lipopeptides such as cilofungin, LY303366, L-693,989, and L-733,560 have activity in vivo against Aspergillus infections but appear to be inactive in broth dilution in vitro tests (MICs, > 128 micrograms/ml). To understand how compounds which lack activity in vitro can have good in vivo activity, we monitored the effect of pneumocandins on the morphology of Aspergillus fumigatus and A, flavus strains by light microscopy and electron microscopy and related the changes in growth to inhibition of glucan synthesis. Pneumocandin B0 caused profound changes in hyphal growth; light micrographs showed abnormally swollen germ tubes, highly branched hyphal tips, and many cells with distended balloon shapes. Aspergillus electron micrographs confirmed that lipopeptides produce changes in cell walls; drug-treated germlings showed very stubby growth with thick walls and a conspicuous dark outer layer which was much thicker in the subapical regions. The rest of the hyphal tip ultrastructure was unaffected by the drug, indicating considerable specificity for the primary target. The drug-induced growth alteration produced very compact clumps in broth dilution wells, making it possible to score the morphological effect macroscopically. The morphological changes could be assayed quantitatively by using conventional broth microdilution susceptibility assay conditions. We defined the endpoint as the lowest concentration required to produce the morphological effect and called it the minimum effective concentration to distinguish it from the no-growth endpoints used in MIC determinations. The minimum effective concentration assay was related to inhibition of glucan synthase activity in vitro and may provide a starting point for development of susceptibility testing methods for lipopeptides.
317 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2021 | 25 |
| 2020 | 18 |
| 2019 | 19 |
| 2018 | 15 |
| 2017 | 19 |
| 2016 | 17 |