of animal multicellularity
The parasite belongs to a lineage close to the evolutionary point at
which unicellular organisms became differentiated to form animals and fungi


Date:
January 28, 2022
Source:
University of the Basque Country
Summary:
Researchers have discovered a parasite present in seawater and
which belongs to a primitive lineage; they have named it Txikispora
philomaios.

This organism will help to explain how multicellularity developed
in animals.



FULL STORY ========================================================================== Researchers from the UPV/EHU-University of the Basque Country and CEFAS
have discovered a parasite present in seawater and which belongs to
a primitive lineage; they have named it Txikispora philomaios. This
organism will help to explain how multicellularity developed in
animals. Phylogenetic and phylogenomic studies using DNA from this
parasite are helping to understand the evolutionary changes and
adaptations that enabled the difficult transition to take place from microscopic unicellular organisms to multicellular animals and fungi.


==========================================================================
The researcher Ander Urrutia of the UPV/EHU's Cell Biology
in Environmental Toxicology research group and Animal Pathology at
CEFAS/OIE, is exploring "the great hidden diversity of unicellular
parasitic organisms in the intertidal zone in coastal ecosystems of
temperate climates, with the aim of trying to see where they are found,
what their ecology is like, how they behave, etc.." Environmental DNA
(eDNA) is one of the techniques used to achieve this goal: it is a
technique that involves "extracting the DNA contained in either an organic
or environmental matrix, for example in an organism or in previously
filtered seawater samples." In particular, Urrutia focused on organisms
that parasitize invertebrates: "There are a great many unidentified
parasites; we find new DNA sequences and infer their behaviour based
on their genetic similarity to other parasites, but we don't really
know what they are." In the task to classify the unicellular parasites
found in the samples, the researcher in the Department of Zoology and
Animal Cell Biology found an "a priori little-known parasite, which,
on the basis of its characteristics, did not fit into any existing
group. We had to do some molecular analyses which confirmed that it was
a different organism. Once we had produced several phylogenetic trees,
i.e. after comparing the DNA of this organism with that of its closest
possible relatives, we were able to see that it is an organism belonging
to a primitive lineage that is close to the point at which animals and
fungi became differentiated. It is close to the evolutionary moment
when a unicellular organism became differentiated to give rise to all
the animals that exist, shortly after which another similar cellular
organism was to become differentiated to eventually evolve into all the
fungi that exist," Urrutia explained.

The 'May-loving spore' "Txikispora philomaiosis a protist (a unicellular eukaryotic organism) that evolved shortly after the division that was undertaken by the common ancestor of animals and fungi, before its multicellularity was developed. All the world's animals and fungi come
from the same cellular organism that was presumably present in the ocean hundreds of millions of years ago. At some point it began to aggregate
and duplicate itself, while its cells specialised to form tissue,
and eventually a body, ranging from a microscopic jellyfish to a huge
blue whale," explained the researcher. Since the genetic rearrangement undergone by parasites often differs from that of their free-living
relatives, the study of this parasite and its genome will contribute
towards understanding how animal multicellularity developed. "In other
words, when and how cells began to communicate with each other, join
together, or specialise among themselves, forming increasingly complex organisms. The development of animal multicellularity is very important
from the point of view of basic biology," added Urrutia, who carried out
the research at CEFAS in the UK, at the Plentzia Marine Station (PIE)
and at the Institute of Evolutionary Biology (IBE/CSIC).

As Urrutia explained, "Txikispora is not only a new species, it also
gives a name to a new genus, a new family, a new order, and so on. In
other words, we now have the new Txikisporidae family, one with quite a
few cryptic sequences, i.e. unknown pieces of DNA that look very similar
to Txikispora and which could also belong to parasites, although we don't
know where they are or which animals they could parasitize. Many of them
are present in aquatic ecosystems in Europe, but we know nothing more
about them. That's another line of research I would like to pursue."
The UPV/EHU researchers were commissioned to name this parasite. The
name Txikispora was adopted owing to the fact that it is a small spore,
and philomaios is due to the fact that the parasite only appeared for
a few days during May, thus 'May-loving spore'. In addition to the
difficulty in placing it phylogenetically in its corresponding group,
it was difficult to find it in seawater: "We had been on a wild goose
chase until we realised that it is only found in the amphipod community
for a few days during this month; it is as if the parasite had disappeared
for the rest of the year," explained Urrutia.

Additional information This research is part of Ander Urrutia's PhD thesis entitled "Cryptic reservoirs of micro-eukaryotic parasites in ecologically relevant intertidal invertebrates from temperate coastal ecosystems" and supervised by Dr Ionan Marigomez (head of the Plentzia Marine Station --
PiE) and Dr Stephen W. Feist of the Centre for Environment, Fisheries
and Aquaculture Science -- CEFAS (United Kingdom). In~aki Ruiz-Trillo
from IBE-CSIC in Barcelona also collaborated in the study.

========================================================================== Story Source: Materials provided by
University_of_the_Basque_Country. Note: Content may be edited for style
and length.


========================================================================== Journal Reference:
1. Ander Urrutia, Konstantina Mitsi, Rachel Foster, Stuart Ross, Martin
Carr, Georgia M. Ward, Ronny Aerle, Ionan Marigomez, Michelle
M. Leger, In~aki Ruiz‐Trillo, Stephen W. Feist, David
Bass. Txikispora philomaios n. sp., n. g., a micro‐eukaryotic
pathogen of amphipods, reveals parasitism and hidden diversity
in Class Filasterea. Journal of Eukaryotic Microbiology, 2021;
DOI: 10.1111/jeu.12875 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/01/220128100733.htm

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