''Nematocida parisii'' is a parasitic species of

Microsporidia Microsporidia are a group of spore-forming unicellular parasites. These spores contain an extrusion apparatus that has a coiled polar tube ending in an anchoring disc at the apical part of the spore. They were once considered protozoans or prot ...

fungi found in wild isolates of the common

nematode The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum Nematoda (also called Nemathelminthes), with plant-Parasitism, parasitic nematodes also known as eelworms. They are a diverse animal phylum inhab ...

, ''

Caenorhabditis elegans ''Caenorhabditis elegans'' () is a free-living transparent nematode about 1 mm in length that lives in temperate soil environments. It is the type species of its genus. The name is a blend of the Greek ''caeno-'' (recent), ''rhabditis'' (ro ...

''. The fungus forms spores and replicates in the intestines before leaving the host.

Infection

''N. parisii'' is an

intracellular parasite Intracellular parasites are microparasites that are capable of growing and reproducing inside the cells of a host. Types of parasites There are two main types of intracellular parasites: Facultative and Obligate. Facultative intracellular para ...

that is transmitted from one animal to another, most commonly through the

fecal–oral route The fecal–oral route (also called the oral–fecal route or orofecal route) describes a particular route of transmission of a disease wherein pathogens in fecal particles pass from one person to the mouth of another person. Main causes of fecal ...

. Once it gets into the intestines, it forms small, ovoid microbes that become spores and leave holes in the intestinal wall. The spores are believed to exit cells by disrupting a conserved

cytoskeletal The cytoskeleton is a complex, dynamic network of interlinking protein filaments present in the cytoplasm of all cells, including those of bacteria and archaea. In eukaryotes, it extends from the cell nucleus to the cell membrane and is compo ...

structure in the intestine called the

terminal web The terminal web is a filamentous structure found at the apical surface of epithelial cells that possess microvilli. It is composed primarily of actin filaments stabilized by spectrin, which also anchors the terminal web to the apical cell membran ...

. None of the known immune pathways of ''C. elegans'' appear to be involved in mediating resistance against ''N. parisii''. Microsporidia have been found in several nematodes isolated from different locations, indicating that they are common natural parasites of ''C. elegans''. The ''N. parisii''–''C. elegans'' system is a useful tool for studying infection mechanisms of intracellular parasites.Troemel ER, Félix M, Whiteman NK, Barrière N, Ausubel FM (2008) Microsporidia are natural intracellular parasites of the nematode Caenorhabditis elegans. PLoS Biol 6(12): e309.

Anatomy

''N. parisii'' has two life stages: the spore stage and the meront stage. The spores have a bulky

cell wall A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane. It can be tough, flexible, and sometimes rigid. It provides the cell with both structural support and protection, and also acts as a filtering mech ...

to help them live outside the host cell during transmission, as well as a polar tube that aids in the infection of the host cell. The tube helps the sporoplasm turn itself inside out in order to get close enough to the host cell to infect it. The sporoplasm becomes the merit, which then becomes more spores after infection within the host cell. Once the spores have matured, they can be released to infect another host. Because its genome size is small and it has very few metabolic pathways, ''N. parisii'' needs its host to survive.

Related species

In 2016, a new species of microsporidia was found in a wild-caught ''C. elegans''. Genome sequencing placed it in the same genus, ''

Nematocida ''Nematocida'' is a genus of Microsporidia Microsporidia are a group of spore-forming unicellular parasites. These spores contain an extrusion apparatus that has a coiled polar tube ending in an anchoring disc at the apical part of the spor ...

'', as prior microsporidia seen in these nematodes. The new species, named '' Nematocida displodere'', was shown to infect a broad range of tissues and cell types in ''C. elegans'', including the

epidermis The epidermis is the outermost of the three layers that comprise the skin, the inner layers being the dermis and hypodermis. The epidermis layer provides a barrier to infection from environmental pathogens and regulates the amount of water rele ...

, muscle, neurons, intestine, seam cells, and

coelomocyte A coelomocyte () is a phagocytic leukocyte that appears in the bodies of animals that have a coelom. In most, it attacks and digests invading organisms such as bacteria and viruses through encapsulation and phagocytosis, though in some animals (e.g. ...

s. These related species are being used to study the host and pathogen mechanisms responsible for allowing or blocking eukaryotic parasite growth in different tissue niches.

References

Microsporidia Parasites of animals Caenorhabditis elegans {{parasite-stub

Infection

Anatomy

Related species

See also

References