Category Archives: Friday Fellow

Friday Fellow: Divergent Dinobryon

by Piter Kehoma Boll

Let’s return once more to the troublesome and neglected protists. This time I’m bringing you another tiny but beautiful alga, more precisely a golden alga. Its name is Dinobryon divergens and as usual there is no common name, so I invented one by simply translating the scientific name, thus I’ll call it the divergent dinobryon.

The divergent dinobryon is part of the class Chrysophyceae, commonly known as golden algae. Measuring about 50 µm in length, it lives in temperate lakes around the world and forms colonies composed of about 6 to 50 ovoid cells that are surrounded by a vase-like shell (lorica) of cellulose, as seen in the picture below.

dinobryon_divergens

A branching colony of Dinobryon divergens. The cells are clearly visible inside the lorica. Photo by Frank Fox.*

During colony formation, an original cell divides and one of the two daughter cells slides to the opening of the lorica and starts to construct a new one. It starts by creating the base of the lorica, which has a funnel shape and is attached to the inner wall of the original lorica. With further divisions, the colony starts to grow in a tree-like form. And the most interesting part is that the cells have two flagella and use them to swim, pulling the whole colony through the water.

As with other golden algae, the divergent dinobryon produces an internal siliceous structure that is globose, hollow and has a single opening connecting to the outside. This structure is called a statospore or stomatocyst and allows the cell to enter a resting state (cyst). The statospore is an important structure to help distinguish different species of golden algae.

The divergent dinobryon is a mixotrophic organism, meaning that it feeds by photosynthesis and by ingesting food too, especially bacteria. Kind of an interesting fellow, don’t you think?

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ResearchBlogging.orgReferences:

Franke, W., & Herth, W. (1973). Cell and lorica fine structure of the chrysomonad alga, Dinobryon sertularia Ehr. (Chrysophyceae) Archiv für Mikrobiologie, 91 (4), 323-344 DOI: 10.1007/BF00425052

Herth, W. (1979). Behaviour of the chrysoflagellate alga, Dinobryon divergens, during lorica formation Protoplasma, 100 (3-4), 345-351 DOI: 10.1007/BF01279321

Karim, A., & Round, F. (1967). Microfibrils in the lorica of the freshwater alga Dinobryon New Phytologist, 66 (3), 409-412 DOI: 10.1111/j.1469-8137.1967.tb06020.x

Sandgren, C. (1981). Characteristics of sexual and asexual resting cyst (statospore) formation in Dinobryon cylindricum Imhof (Chrysophyta) Journal of Phycology, 17 (2), 199-210 DOI: 10.1111/j.1529-8817.1981.tb00840.x

Sheath, R., Hellebust, J., & Sawa, T. (1975). The statospore of Dinobryon divergens Imhof: Formation and germination in a subarctic lake Journal of Phycology, 11 (2), 131-138 DOI: 10.1111/j.1529-8817.1975.tb02760.x

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Friday Fellow: Pliable Brachionus

by Piter Kehoma Boll

Charles Darwin had already noticed that small animals, such as those found in zooplankton, are widely distributed around the world, even those that are found in small ponds of freshwater. This seemed to go against the speciation theories, but it was thought to be the result of passive transport by other animals, such as migratory birds. One of such species is the tiny rotifer Brachionus plicatilis, or the pliable brachionus, as I decided to call it, a 0.1 to 0.2 mm long species found worlwide in saline lakes.

brachionus_plicatilis

A specimen of the pliable brachionus. Photo by Wikimedia user Sofdrakou.*

The pliable brachionus is a euryhaline species, meaning it can tolerate a wide range of salinity. Recent molecular studies have shown that it is actually a complex of at least 22 different species, but as this was not yet taxonomically defined, I will continue to use the terms Brachionus plicatilis and plicate brachionus in the broad sense.

In the last half century, the pliable brachionus became a commercially important species, being raised as a food source for fish larvae. It may be fed with a variety of microorganisms, such as bacteria, algae and yeasts. In the natural environment, it is considered a generalist filter-feeding species.

As many rotifers, the pliable brachionus usually reproduces by parthenogenesis, where the so-called amictic females produce diploid eggs that originate other amictic females. Under certain conditions, however, they may produce eggs that originate mictic females, which only lay haploid eggs. Unfertilized haploid eggs originate males, while those that are fertilized originate new females. A bit complex, right?

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ResearchBlogging.orgReferences:

Gómez, A., Serra, M., Carvalho, G., & Lunt, D. (2002). Speciation in ancient cryptic species complexes: evidence from the molecular phylogeny of Brachionus plicatilis(Rotifera) Evolution, 56 (7) DOI: 10.1554/0014-3820(2002)056[1431:SIACSC]2.0.CO;2

Øie, G., Makridis, P., Reitan, K., & Olsen, Y. (1997). Protein and carbon utilization of rotifers (Brachionus plicatilis) in first feeding of turbot larvae (Scophthalmus maximus L.) Aquaculture, 153 (1-2), 103-122 DOI: 10.1016/S0044-8486(96)01514-1

Suatoni, E., Vicario, S., Rice, S., Snell, T., & Caccone, A. (2006). An analysis of species boundaries and biogeographic patterns in a cryptic species complex: The rotifer—Brachionus plicatilis Molecular Phylogenetics and Evolution, 41 (1), 86-98 DOI: 10.1016/j.ympev.2006.04.025

Walker, K. (1981). 13. A synopsis of ecological information on the saline lake rotifer Brachionus plicatilis Müller 1786 Hydrobiologia, 81-82 (1), 159-167 DOI: 10.1007/BF00048713

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Friday Fellow: Tree Tumbo

by Piter Kehoma Boll

Today I’m introducing one of the most bizarre plant species in the world. Found in the Namib desert, in Namibia and Angola, the Welwitschia mirabilis, usually simply called welwitschia or tree tumbo in English, is the solely member of the order Welwitschiales, a group of gymnosperms in the division Gnetophyta.

welwitschia_mirabilis

A specimen of Welwitschia mirabilis in Naukluft, Namibia. Photo by Sara&Joachim*

The tree tumbo has a unique appearance. The seedlings have two cotyledons (the original leaves produced by the seed) and later develop two permanent leaves that grow opposite (at right angles) to the cotyledons. These permanent leaves grow continuosly, reaching up to 4 m in length. While growing, the leaves split and fray into several straps and occupy an area of about 8 m in circunference around the plant. The stem is woody and the flowers appear on a central part called crown. The species is dioecious, meaning that male and female flowers appear in different plants. Pollination is usually carried out by insects.

Living up to 2 thousand years, the tree tumbo is a very peculiar desert plant. Its leaves are broad and very large, different from what is the rule in the desert. Its root system is also very shallow, not penetrating deep in the ground. It seems that most of the water used by the plant is captured by the leaves from the morning fog.

Although having a very restrict range, the tree tumbo is not (yet) and endangered plant, as its population is considerably large. However, due to its popularity, some areas attract collectors, and since its growth is so slow, it may eventually become a vulnerable plant.

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References:

Bornmann, C. H. 1972. Welwitschia mirabilis: paradox of the Namib Desert. Edeavour, 31(113):95–99.

Wikipedia. Welwitschia mirabilis. Available at <https://en.wikipedia.org/wiki/Welwitschia&gt;. Access on March 1, 2017.

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Friday Fellow: Scarlet Elf Cup

por Piter Kehoma Boll

If you like to pay attention on mushrooms growing on the forest soil, you may have found this little fellow sometimes, especially if you live in the Northern Hemisphere. Scientifically known as Sarcoscypha coccinea, its common names include ruby elfcup, scarlet elf cup, scarlet elf cap, or simply scarlet cup.

The scarlet elf cup is an ascomycete, so it is more closely related to morels and truffles than to more famous gilled umbrella-shaped mushrooms. Its cup-shaped fruiting body has a bright red color on the inside and a white color on the outside. It can be found growing on decayed wood in forests of North America and Europe, although it has also been recorded in Australia and Chile.

sarcoscypha_coccinea

Beautiful scarlet elf cups growing on a a fallen log. Photo by geograph user ceridwen*

The fruiting bodies of the scarlet elf cup may vary depending on the environmental conditions. Usually those growing on buried wood in places protected from wind are the greatest, while those growing on wood above the ground and being exposed to wind are usually smaller. There is no agreement on whether the fruiting bodies are edible or not. Some authors consider it edible, while other do not recomend its ingestion. However, there are some records of people eating it, and it is also used as a medicine by Native American peoples, such as the Oneida people.

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References:

EOL. Encyclopedia of Life. Sarcoscypha coccinea. Available at < http://eol.org/pages/1009245/overview >. Access on March 1, 2017.

Wikipedia. Sarcoscypha coccinea. Available at <https://en.wikipedia.org/wiki/Sarcoscypha_coccinea >. Access on March 1, 2017.

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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.

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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.

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Friday Fellow: Brown-gutted Mud Roundworm

by Piter Kehoma Boll

If you have your face buried in the mud at the bottom of a European lake, you may end up finding some of those tiny little roundworms known as Monhystera stagnalis. As usual, there is no common name for this species, but I decided to call it brown-gutted mud roundworm. Why? Because it lives in the mud and has a reddish-brown gut.

monhystera_stagnalis

An individual of Monhystera stagnalis. Photo by Marco Spiller.*

The brown-gutted mud roundworm is a widely distributed roundworm species, being common especially throughout Europe. It inhabits the fine sediments at the bottom of freshwater bodies, both stagnant and flowing, where it feeds on the organic material deposit in this medium, having a special taste for bacteria. It is able to survive in moderate organic pollution, but is sensitive to low oxygen levels.

It is one of the most common nematode species in its environment and it is very small, measuring around 1 mm in length, females being slightly longer than males. They are found in all depths of the sediment and seem to have a preference for staying closer to the surface during winter and deeper in the mud during summer.

Females are ovoviviparous, meaning that they retain the egg inside their bodies until they hatch, so they are pregnant with eggs. Although we are used to think that invertebrates produce hundreds or thousands of eggs at once, this is not the case with the brown-gutted mud roundworm. Females are usually pregnant of a single egg, sometimes with two or three. They are modest worms.

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ResearchBlogging.orgReferences:

Pehofer, H. (1989). Spatial Distribution of the Nematode Fauna and Production of Three Nematodes (Tobrilus gracilis, Monhystera stagnalis, Ethmolaimus pratensis) in the Profundal of Piburger See (Austria, 913 m a.s.l) Internationale Revue der gesamten Hydrobiologie und Hydrographie, 74 (2), 135-168 DOI: 10.1002/iroh.19890740203

Traunspurger, W. (1996). Autecology of Monhystera paludicola De Man, 1880 – Seasonal, Bathymetric and Vertical Distribution of a Free-living Nematode in an Oligotrophic Lake Internationale Revue der gesamten Hydrobiologie und Hydrographie, 81 (2), 199-211 DOI: 10.1002/iroh.19960810205

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Friday Fellow: Paraná pine

by Piter Kehoma Boll

As the first conifer Friday Fellow, I decided to choose one of my beloved ones, the Paraná pine, Araucaria angustifolia, also known as Brazilian pine or candelabra tree.

The Paraná pine can reach up to 50 m in height, although most trees are smaller than that. They have a very particular shape and are easily distinguished from the surrounding forest where they occur, the so-called Mixed Ombrophilous Forest or Araucaria Moist Forest, in southern Brazil. The trees have a cylindrical trunk with a dark and thin bark that detaches in large and flexible pieces, being gray on the outer surface and reddish on the inner one. The crown changes its appearance during the development, being conical in young trees and with a candelabrum-like shape in mature specimens. Mature trees usually stand with their crowns above the forest canopy, which gives the Araucaria moist forest its particular look. The leaves grow in a spiral pattern around the stem and are very hard with a sharp point that can easily pierce through the human skin.

araucaria_angustifolia

A group of Paraná pines in Campos de Jordão, Brazil, close to the northernmost distribution of the species. Photo by Vinícius Ribeiro.*

The species current distribution is almost restricted to Brazil, from northern Rio Grande do Sul to southern São Paulo, with some small populations occurring in neighboring areas of Argentina and Paraguay. Once an abundant species, its population has been drastically reduced due to the heavy logging until the middle of the 20th century and the exploitation for the use of its seeds, called pinhão in Portuguese. As a result, it is currently considered as Critically Endangered by IUCN.

araucaria_angustifolia2

An adult tree in the municipality of Colombo, Paraná, Brazil. Photo by Mauro Guanandi.*

The paraná pine is a dioecious species, i.e., males and females are separate plants. As most conifers, it is pollinated by the wind. The large cones, which take two years to become ripe, contain a number of large and edible seeds used as food by many animals, as well as by humans. Pinhões cooked in salty water is a typical dish in southern Brazil during winter. One of the main seed dispersers of the Paraná pine is the azure jay, Cyanocorax caeruleus, which buries the seeds for future use.

araucaria_angustifolia3

A cone and lose seeds of Araucaria angustifolia in a market. Photo by Marcelo Träsel.**

As most (if not all) conifers, the Paraná pine forms mutualist associations with fungi, such as the glomeromycete Glomus clarum. Thus, in order to preserve this amazing tree, it is also necessary to guarantee the preservation of all its partner species, such as mycorrhizal fungi and seed dispersers.

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ResearchBlogging.orgReferences:

Angeli, A. (2003). Araucaria angustifolia (Araucaria). Departamento de Ciências Florestais – ESALQ/USP. Available at: <http://www.ipef.br/identificacao/araucaria.angustifolia.asp&gt;. Access on January 26, 2017.

IUCN (2016). Araucaria angustifolia The IUCN Red List of Threatened Species DOI: 10.2305/IUCN.UK.2013-1.RLTS.T32975A2829141.en

Soares, T. S. (2004). Araucária – o pinheiro brasileiro. Revista Científica Eletrônica de Engenharia Florestal, 2 (3).

SOUZA, A. (2007). Ecological interpretation of multiple population size structures in trees: The case of Araucaria angustifolia in South America Austral Ecology, 32 (5), 524-533 DOI: 10.1111/j.1442-9993.2007.01724.x

Zandavalli, R., Dillenburg, L., & de Souza, P. (2004). Growth responses of Araucaria angustifolia (Araucariaceae) to inoculation with the mycorrhizal fungus Glomus clarum. Applied Soil Ecology, 25 (3), 245-255 DOI: 10.1016/j.apsoil.2003.09.009

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