Podospora Anserina
   HOME

TheInfoList



OR:

''Podospora anserina'' is a filamentous ascomycete
fungus A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...
from the order
Sordariales The order Sordariales is one of the most diverse taxonomic groups within the Sordariomycetes (subdivision Pezizomycotina, division Ascomycota). Species in the order Sordariales have a broad range of ecological diversity, containing lignicolous, ...
. It is considered a
model organism A model organism is a non-human species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the model organism will provide insight into the workings of other organisms. Mo ...
for the study of
molecular biology Molecular biology is a branch of biology that seeks to understand the molecule, molecular basis of biological activity in and between Cell (biology), cells, including biomolecule, biomolecular synthesis, modification, mechanisms, and interactio ...
of
senescence Senescence () or biological aging is the gradual deterioration of Function (biology), functional characteristics in living organisms. Whole organism senescence involves an increase in mortality rate, death rates or a decrease in fecundity with ...
(aging),
prions A prion () is a misfolded protein that induces misfolding in normal variants of the same protein, leading to cellular death. Prions are responsible for prion diseases, known as transmissible spongiform encephalopathy (TSEs), which are fat ...
, sexual reproduction, and
meiotic drive Meiotic drive is a type of intragenomic conflict, whereby one or more loci within a genome will affect a manipulation of the meiotic process in such a way as to favor the transmission of one or more alleles over another, regardless of its phenot ...
. It has an obligate sexual and pseudohomothallic life cycle. It is a non-pathogenic
coprophilous fungus A coprophilous fungus (''dung-loving'' fungus) is a type of saprobic fungus that grows on animal dung. The hardy spores of coprophilous species are unwittingly consumed by herbivores from vegetation, and are excreted along with the plant matter. ...
that colonizes the dung of herbivorous animals such as horses, rabbits, cows and sheep.


Taxonomy

''Podospora anserina'' was originally named ''Malinvernia anserina'' Rabenhorst (1857). ''Podospora anserina'' was subsequently published in Niessl (1883), which is used today to reference the common laboratory strain therefrom, 'Niessl'. It is also known as ''Pleurage anserina'' (Ces.) Kuntze. Genetics of ''P. anserina'' were characterized in Rizet and Engelmann (1949) and reviewed by Esser (1974). ''P. anserina'' is estimated to have diverged from ''
Neurospora crassa ''Neurospora crassa'' is a type of red bread mold of the phylum Ascomycota. The genus name, meaning 'nerve spore' in Greek, refers to the characteristic striations on the spores. The first published account of this fungus was from an infestatio ...
'' 75 million years ago based on
18S rRNA 18S ribosomal RNA (abbreviated 18S rRNA) is a part of the ribosomal RNA in eukaryotes. It is a component of the Eukaryotic small ribosomal subunit (40S) and the cytosolic homologue of both the 12S rRNA in mitochondria and the 16S rRNA in plas ...
and protein orthologous share 60-70% homology. Gene cluster orthologs between ''
Aspergillus nidulans ''Aspergillus nidulans'' (also called '' Emericella nidulans'' when referring to its sexual form, or teleomorph) is one of many species of filamentous fungi in the phylum Ascomycota. It has been an important research organism for studying eukary ...
'' and ''Podospora anserina'' have 63% identical primary amino acid sequence (even though these species are from distinct classes) and the average amino acid of compared proteomes is 10% less, giving rise to hypotheses of distinct species yet shared genes.


Research

''Podospora'' is a model organism to study genetics, aging (senescence, cell degeneration), ascomycete development,
heterokaryon In biology, a heterokaryon is a multinucleate cell that contains genetically different nuclei. This is a special type of syncytium. This can occur naturally, such as in the mycelium of fungi during sexual reproduction, or artificially as formed b ...
incompatibility,
mating in fungi Fungi are a diverse group of organisms that employ a huge variety of reproductive strategies, ranging from fully asexual to almost exclusively sexual species. Most species can reproduce both sexually and asexually, alternating between haploid ...
,
prion A prion () is a Proteinopathy, misfolded protein that induces misfolding in normal variants of the same protein, leading to cellular death. Prions are responsible for prion diseases, known as transmissible spongiform encephalopathy (TSEs), w ...
s, and mitochondrial and peroxisomal physiology. ''Podospora'' is easily culturable on complex (full) potato dextrose, cornmeal agar/broth, or even synthetic medium, and, using modern molecular tools, is easy to manipulate. Its optimal growth temperature is and can complete its life cycle in 7 to 11 days under laboratory conditions.


Strains

Most research has been done in a small collection of French strains sampled in the 1920s, in particular the strains named S and s. These two strains are known to be very similar except for the '' het-s'' locus. The reference genome published in 2008 corresponds to S+, a haploid derivate of the S strain with a + mating type. In addition, two other populations have been sampled, one in Usingen, Germany, and the other in Wageningen, the Netherlands, both of which have been used to study spore killing, the phenotypic expression of
meiotic drive Meiotic drive is a type of intragenomic conflict, whereby one or more loci within a genome will affect a manipulation of the meiotic process in such a way as to favor the transmission of one or more alleles over another, regardless of its phenot ...
in fungi. In addition there are multiple lab-derived strains: * ''ΔPaKu70'' is used to increase
homologous recombination Homologous recombination is a type of genetic recombination in which genetic information is exchanged between two similar or identical molecules of double-stranded or single-stranded nucleic acids (usually DNA as in Cell (biology), cellular organi ...
in protoplasts during transformations in order to create desirable gene deletions or allelic mutations. A ''ΔPaKu70'' strain can be achieved by transforming protoplasts with linear DNA that flanks the ''PaKu70'' gene along with an antibiotic cassette and then selecting for strains and verifying by PCR. Derived from the s strain. * Mn19 is a long-lived strain used to study senescence. It is derived from strain A+-84-11 grown on manganese (Mn). This particular strain has been reported to have lived over 2 years in a race tube covering over of vegetative growth. * ''ΔiΔviv'' is an immortal strain that shows no sign of senescence. It produces yellow pigmentation. Lack of ''viv'' increased life span in days by a factor of 2.3 compared to the wild type and lack of ''i'' by 1.6. However, strain ''ΔiΔviv'' showed no senescence during the whole study and was vegetative for over a year. These genes are synergistic and are physically closely linked. * AL2 is a long-lived strain. Insertion of linear mitochondrial plasmid containing ''al-2'' show increased life span. However, natural isolates that have homology to ''al-2'' do not show increased life span. * ''Δgrisea'' is a long-lived strain and copper uptake mutant. This strain has lower affinity to copper and thus lower intracellular copper levels, leading to use of the cyanide-resistant
alternative oxidase The alternative oxidase (AOX) is an enzyme that forms part of the electron transport chain in mitochondria of different organisms. Proteins homologous to the mitochondrial oxidase and the related plastid terminal oxidase have also been identified ...
, PaAOX, pathway (instead of copper-dependent mitochondrial
cytochrome c oxidase The enzyme cytochrome c oxidase or Complex IV (was , now reclassified as a translocasEC 7.1.1.9 is a large transmembrane protein complex found in bacteria, archaea, and the mitochondria of eukaryotes. It is the last enzyme in the Cellular respir ...
(COX) complex). This strain also exhibits more stable mtDNA. Copper use is similar to ''Δex1'' strain. * ''Δex1'' is an 'immortal strain' that has been grown for over 12 years and still shows no signs of senescence. This strain respires via a cyanide-resistant,
salicylhydroxamic acid Salicylhydroxamic acid (SHA or SHAM) is a drug that is a potent and irreversible enzyme inhibitor of the urease enzyme in various bacteria and plants; it is usually used for urinary tract infections. The molecule is similar to urea but is not h ...
(SHAM)-sensitive pathway. This deletion disrupts the COX complex.


Aging

''Podospora anserina'' has a definite life span and shows senescence phenotypically (by slower growth, less aerial
hypha A hypha (; ) is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium. Structure A hypha consists of one o ...
e, and increased pigment production in distal hyphae). However, isolates show either increased life span or immortality, as to study the process of aging many genetic manipulations have been done to produce immortal strains or increase life-span. In general, the
mitochondrion A mitochondrion () is an organelle found in the cell (biology), cells of most eukaryotes, such as animals, plants and fungi. Mitochondria have a double lipid bilayer, membrane structure and use aerobic respiration to generate adenosine tri ...
and mitochondrial chromosome is investigated. Senescence occurs because during respiration
reactive oxygen species In chemistry and biology, reactive oxygen species (ROS) are highly Reactivity (chemistry), reactive chemicals formed from diatomic oxygen (), water, and hydrogen peroxide. Some prominent ROS are hydroperoxide (H2O2), superoxide (O2−), hydroxyl ...
are produced that limit the life span and over time defective mitochondrial DNA can accumulate. With this knowledge, focus turned to nutrition availability, respiration (ATP synthesis) and oxidases, such as cytochrome c oxidase.
Carotenoids Carotenoids () are yellow, orange, and red organic compound, organic pigments that are produced by plants and algae, as well as several bacteria, archaea, and Fungus, fungi. Carotenoids give the characteristic color to pumpkins, carrots, parsnips ...
, pigments that are also found in plants and provide health benefits to humans, are known to be in fungi like ''Podospora's'' divergent ancestor ''Neurospora crassa''; in ''N. crassa'' (and other fungi) cartenoids ''al'' genes namely provide UV radiation protection. Over-expression of ''al-2'' ''Podospora anserina'' increased life span by 31%. Calorie restriction studies show that decreasing nutrients, such as sugar, increased life span, likely due to slower metabolism and thus decreased reactive oxygen species production or induced survival genes. Also, intracellular copper levels were found to be correlated with growth. This was studied in Grisea-deleted and ex1-deleted strains, as well as in a wild type s strain. ''Podospora'' without Grisea, a copper transcription factor, had decreased intracellular copper levels which lead to use of an alternative respiratory pathway that consequently produced less oxidative stress. In the ''P. anserina'' aging model,
autophagy Autophagy (or autophagocytosis; from the Greek language, Greek , , meaning "self-devouring" and , , meaning "hollow") is the natural, conserved degradation of the cell that removes unnecessary or dysfunctional components through a lysosome-depe ...
, a pathway for the degradation of damaged biomolecules and organelles, was shown to be a longevity assurance mechanism.


Heterokaryon incompatibility

The following genes, both allelic and nonallelic, are found to be involved in vegetative incompatibility (only those cloned and characterized are listed): ''het-c'', ''het-c'', ''het-s'', ''idi-2'', ''idi-1'', ''idi-3'', ''mod-A'', ''mode-D'', ''mod-E'', ''psp-A''. ''Podospora anserina'' contains at least 9 ''het'' loci.


Enzymes

''Podospora anserina'' is known to produce laccases, a type of phenoloxidase.


Genetics

Original genetic studies by
gel electrophoresis Gel electrophoresis is an electrophoresis method for separation and analysis of biomacromolecules (DNA, RNA, proteins, etc.) and their fragments, based on their size and charge through a gel. It is used in clinical chemistry to separate ...
led to the finding of the genome size,
megabases A base pair (bp) is a fundamental unit of double-stranded nucleic acids consisting of two nucleobases bound to each other by hydrogen bonds. They form the building blocks of the DNA double helix and contribute to the folded structure of both DNA ...
, with 7 chromosomes and 1 mitochondrial chromosome. In the 1980s the mitochondrial chromosome was sequenced. Then, in 2003, a pilot study was initiated to sequence regions bordering chromosome V's
centromere The centromere links a pair of sister chromatids together during cell division. This constricted region of chromosome connects the sister chromatids, creating a short arm (p) and a long arm (q) on the chromatids. During mitosis, spindle fiber ...
using BAC clones and direct sequencing. In 2008, a 10x whole genome draft sequence was published. The genome size is now estimated to be 35-36 megabases.
Genetic manipulation Genetic engineering, also called genetic modification or genetic manipulation, is the modification and manipulation of an organism's genes using technology. It is a set of technologies used to change the genetic makeup of cells, including th ...
in fungi is difficult due to low homologous recombination efficiency and which hinders genetic studies using allele replacement and . In 2005, a method for
gene deletion In genetics, a deletion (also called gene deletion, deficiency, or deletion mutation) (sign: Δ) is a mutation (a genetic aberration) in which a part of a chromosome or a sequence of DNA is left out during DNA replication. Any number of nucleoti ...
was developed based on a model for ''Aspergillus nidulans'' that involved cosmid plasmid transformation. A better system for ''Podospora'' was developed in 2008 by using a strain that lacked nonhomologous end joining proteins (
Ku (protein) Ku is a dimeric protein complex that binds to DNA double-strand break DNA end, ends and is required for the non-homologous end joining (NHEJ) pathway of DNA repair. Ku is evolutionarily conserved from bacteria to humans. The ancestral bacte ...
, known in ''Podospora'' as ''PaKu70''). This method claimed to have 100% of transformants undergo desired homologous recombination leading to allelic replacement, and after the transformation, the ''PaKu70'' deletion can be restored by crossing over with a wild-type strain to yield progeny with only the targeted gene deletion or allelic exchange (e.g. point mutation).


Secondary metabolites

It is well known that many organisms across all domains produce
secondary metabolites Secondary metabolites, also called ''specialised metabolites'', ''secondary products'', or ''natural products'', are organic compounds produced by any lifeform, e.g. bacteria, archaea, fungi, animals, or plants, which are not directly involved ...
, and fungi are prolific in this regard. Product mining was well underway in the 1990s for the genus ''Podospora''. From ''Podospora anserina'' two new natural products classified as pentaketides, specifically derivatives of
benzoquinone Benzoquinone (C6H4O2) is a quinone with a single benzene ring. There are 2 (out of 3 hypothetical) benzoquinones: * 1,4-Benzoquinone, most commonly, right image (also ''para''-benzoquinone, ''p''-benzoquinone, ''para''-quinone, or just quinone) * ...
s, were discovered; these showed antifungal, antibacterial, and cytotoxic activities.
Horizontal gene transfer Horizontal gene transfer (HGT) or lateral gene transfer (LGT) is the movement of genetic material between organisms other than by the ("vertical") transmission of DNA from parent to offspring (reproduction). HGT is an important factor in the e ...
is common in bacteria and between prokaryotes and eukaryotes yet is more rare between eukaryotic organisms. Between fungi, secondary metabolite clusters are good candidates for horizontal gene transfer, for example, a functional ''ST'' gene cluster that produces sterigmatocystin was found in ''Podospora anserina'' and originally derived from ''Aspergillus''. This cluster is well-conserved, including, notably, the transcription-factor binding sites. Sterigmatocystin itself is toxic and is a precursor to another toxic metabolite,
aflatoxin Aflatoxins are various toxicity, poisonous carcinogens and mutagens that are produced by certain Mold (fungus), molds, especially ''Aspergillus'' species such as ''Aspergillus flavus'' and ''Aspergillus parasiticus''. According to the USDA, "The ...
.


See also

*
Fungal prions A fungal prion is a prion that infects hosts which are fungi. Fungal prions are naturally occurring proteins that can switch between multiple, structurally distinct conformations, at least one of which is self-propagating and transmissible to oth ...
* PXMP3 *
Virus classification Virus classification is the process of naming viruses and placing them into a taxonomy (biology), taxonomic system similar to the classification systems used for cell (biology), cellular organisms. Viruses are classified by phenotypic characteri ...
* OLIGO Primer Analysis Software *
Point mutation A point mutation is a genetic mutation where a single nucleotide base is changed, inserted or deleted from a DNA or RNA sequence of an organism's genome. Point mutations have a variety of effects on the downstream protein product—consequences ...
*
Amyloid Amyloids are aggregates of proteins characterised by a fibrillar morphology of typically 7–13 nm in diameter, a β-sheet secondary structure (known as cross-β) and ability to be stained by particular dyes, such as Congo red. In the human ...


References


External links

* * {{Authority control Lasiosphaeriaceae Taxa named by Gottlob Ludwig Rabenhorst Fungi described in 1857 Model organisms Fungus species