Category Archives: protists

Friday Fellow: B. coli

by Piter Kehoma Boll

It’s time to give more space for parasites, including human parasites! So today our fellow comes right from the stool of many mammals, including humans. Its name is Balantidium coli, or B. coli for short.

B. coli is a ciliate, i.e., a member of the phylum Ciliophora, a group of protists that have their cells covered by cilia, which are nothing more than very short and numerous flagella. Most ciliates are free-living organisms, and in fact B. coli is the only ciliate known to be harmful to humans, but not only to humans. Many other mammals are also known to host this fellow, especially pigs.

balantidium_coli

The red elongate macronucleus of B. coli makes it look like a bad guy, don’t you think? Photo extracted from http://www.southampton.ac.uk/~ceb/Diagnosis/Vol2.htm

The typicall habitat of B. coli is the large intestine of mammals. The protist lives there in an active phase called trophozoite (seen in the image above) and feeds on the natural bacteria that live in the gut. When facing dehydration, which happens in the final portion of the intestine or after the organism is released with the feces, B. coli changes to an inactive phase called cyst, which is smaller than the trophozoite and covered by a thick wall. The cysts released in the environment may be ingested by a new host and reach their intestine, where they will return to the trophozoite form.

balantidium_coli2

A cyst of B.coli. Photo extracted from http://www.southampton.ac.uk/~ceb/Diagnosis/Vol2.htm

Symptoms of infection by B. coli, also known as balantidiasis, include explosive diarrhea every 20 minutes and, in acute infections, it may cause perforation of the colon and become a life-threatening condition.

Fortunately, infection in humans is not that common. The most affected country nowadays are the Philippines, but you may get infected anywhere. The best way to reduce the infection risks is by having good sanitary conditions and personal hygiene. However, as pigs are the most common vectors of the disease, it will likely continue to exist as long as humans raise pigs.

– – –

ResearchBlogging.orgReferences:

Schuster, F., & Ramirez-Avila, L. (2008). Current World Status of Balantidium coli Clinical Microbiology Reviews, 21 (4), 626-638 DOI: 10.1128/CMR.00021-08

Wikipedia. Balantidium coli. Available at <https://en.wikipedia.org/wiki/Balantidium_coli&gt;. Access on February 23, 2017.

Leave a comment

Filed under Friday Fellow, Parasites, protists

Friday Fellow: Northern Plaited Radiolarian

by Piter Kehoma Boll

Some weeks ago I introduced a diatom here and mentioned that, despite the fact that they are a very abundant group, little information on species is available. Today our species is a radiolarian and, just as with the diatoms, they are abundant but little known.

I struggled to find an extant species that also had a good and available photo to share. And the winner was a species known as Cleveiplegma boreale, or Rhizoplegma boreale perhaps. I’m not sure what is the currently accepted name. Anyway, it does not have a common name, but I decided to create one, so let’s call it “northern plaited radiolarian”.

Radiolarians are unicelular organism that have an intricate mineral skeleton that contains a central capsule that typically divides the cell into two portions: an inner one and an outer one. Our fellow today looks like this:

cleveiplegma_boreale

A living specimen of the northern plaited radiolarian. Photo by John Dolan.*

The northern plaited radiolarian has from 6 to 10 spines growing out of it and there is a complex plaited pattern of the skeleton that surrounds them and the inner shell. Measuring anout 20µm in diameter, it is a rather large radiolarian.

Although it is known from fossils along the Quaternary, from at least 10 thousand years before present, the northern plaited radiolarian is still a living species. Currently it is known to occur in the Nordic Seas, around Scandinavia, Iceland and Greenland, in the North Pacific, including the Bering Sea, and in the Southern Ocean, around Antarctica. We can see, therefore, that this species likes cold waters.

Ah, and they feed on diatoms… I guess.

– – –

ResearchBlogging.orgReferences:

Dolven, J., & Bjørklund, K. (2001). An early Holocene peak occurrence and recent distribution of Rhizoplegma boreale (Radiolaria): a biomarker in the Norwegian Sea Marine Micropaleontology, 42 (1-2), 25-44 DOI: 10.1016/S0377-8398(01)00011-1

Dumitrica, P. (2013). Cleveiplegma nov. gen., a new generic name for the radiolarian species Rhizoplegma boreale (Cleve, 1899) Revue de Micropaléontologie, 56 (1), 21-25 DOI: 10.1016/j.revmic.2013.01.001

– – –

*Creative Commons License
This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.

Leave a comment

Filed under Friday Fellow, protists

Friday Fellow: Wheel Necklace Diatom

ResearchBlogging.orgby Piter Kehoma Boll

Most of you likely know what diatoms are, microscopic algae with a silica shell that are very abundant in the world’s oceans and one of the main oxygen producers. You may have seen images like the one below, showing the diversty of diatoms, but can you name a single species?

diatoms

The beautiful, yet largely neglected by non-experts, diversity of diatoms. Photo by Wikimedia user Wipeter.*

Today I decided to bring you a diatom Friday Fellow and let me tell you: it was not at all easy to select a nice species with a considerable amount of available information and a good picture. But at the end the winner of the First Diatom Friday Fellow Award was…

Thalassiosira rotula!

thalassiosira_rotula

Three connected individuals of Thalassiosira rotula. Photo by micro*scope.**

As with most microorganisms, this species has no common name and, as it is a tradition here, I decided to make one up and chose wheel necklace diatom. Necklace diatom seems to be a good common name for species in the genus Thalassiosira, as they are formed by several individuals connected to each other in a pattern that resembles a necklace. I decided to call this particular species wheel necklace diatom because of its specific epithet, rotula, which means little wheel in Latin.

The wheel necklace diatom is a marine species found worldwide close to the coast. It is very abundant and the dominant species in some areas, so it is of great ecological importance. Small planctonic crustaceans, such as copepods, usually feed on the wheel necklace diatom and, as those crustaceans are used as food for much larger animals, the wheel necklace diatom is responsible for sustaining a whole food chain.

– – –

References:

Ianora, A., Poulet, S., Miralto, A., & Grottoli, R. (1996). The diatom Thalassiosira rotula affects reproductive success in the copepod Acartia clausi Marine Biology, 125 (2), 279-286 DOI: 10.1007/BF00346308

Krawiec, R. (1982). Autecology and clonal variability of the marine centric diatom Thalassiosira rotula (Bacillariophyceae) in response to light, temperature and salinity Marine Biology, 69 (1), 79-89 DOI: 10.1007/BF00396964

– – –

*Creative Commons License
This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.

**Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License.

Leave a comment

Filed under Algae, Botany, Friday Fellow, protists

Friday Fellow: Tepid ammonia

by Piter Kehoma Boll

One of the few groups of living being not yet featured in Friday Fellow is Rhizaria, a group of single-celled organisms that includes the famous foraminifers. So today I decided to bring you just that, a foraminifer. And I think a good species to start with is Ammonia tepida, or the “tepid ammonia” as I decided to call it.

A live Ammonia tepida. Credits to Scott Fay.*

A live Ammonia tepida. Credits to Scott Fay.*

The tepid ammonia is found worldwide in brackish waters, or more precisely in the sediments deposited in brackish waters worlwide. It is able to tolerate a wide range of temperatures and degrees of salinity and is considered an ideal species of laboratory studies. As most foraminifers, the tepid ammonia secrets a shell of calcium carbonate, which is deposited on the cell’s surface in the form of a chain of chambers forming a spiral path, thus making it look like a snail shell.

Living in the sediments, the tepid ammonia feeds mainly on algae, but also consumes bacteria. In the laboratory, it demonstrated to have the ability to prey on small animals, such as nematodes, copepods and molluk larvae.

This kid got talent!

– – –

References:

Dupuy, C.; Rossignol, L.; Geslin, E.; Pascal, P.-Y. (2010) Predation of mudflat meio-macrofaunal metazoans by a calcareous foraminifer, Ammonia tepida (Cushman, 1926). The Journal of Foraminiferal Research 40 (4): 305–312.

Munsel, D.; Kramar, U.; Dissard, D.; Nehrke, G.; Berner, Z.; Bijma, J.; Reichart, G.-J.; Neumann, T. (2010) Heavy metal incorporation in foraminiferal calcite: results from multi-element enrichment culture experiments with Ammonia tepida. Biogeosciences 7 (8): 2339–2350.

– – –

*Creative Commons License
This image is licensed under a Creative Commons Attribution 2.5 Generic License.

 

Leave a comment

Filed under Friday Fellow, protists