Monthly Archives: January 2016

Friday Fellow: Red Panda

by Piter Kehoma Boll

One of the cutest animals on the world, or perhaps the cutest in fact, the red panda (Ailurus fulgens) is today’s Friday Fellow.

"Hello! I'm the cutest thing you've ever met!" Photo by Wikimedia user Kuribo.*

“Hello! I’m the cutest thing you’ve ever met!” Photo by Wikimedia user Kuribo.**

The red panda is endemic to temperate forests of the Himalayas in Nepal, China, India, Bhutan and Myanmar. It has, therefore, a considerably small range and prefers areas with a higher bamboo cover.

Despite its cuteness, the red panda’s wild population is declining, with less than 10 thousand individuals remaining, although a more accurate measurement is hard to achieve because local people tend to confuse other small carnivores with the red panda, which may lead to an overestimation of the population size. It is listed as an endangered species in the IUCN’s Red List and the main threats to its survival are habitat loss and fragmentation, inbreeding depression and poaching.

As the giant panda’s, the red panda’s main food is bamboo, but it also eats fruits, eggs and small animals, such as insects and small mammals.

Red pandas love bamboo. Photo by Wikipedia user Colegota.*

Red pandas love bamboo. Photo by Wikipedia user Colegota.*

The taxonomic classification of the red panda was a headache for a long time. It has been placed among the bears (Ursidae) and the raccoons (Procyonidae), but molecular studies indicated that it belongs to its own family, Ailuridae, which is closely related to Procyonidae, Mustelidae (weasels) and Mephitidae (skunks).

Being so cute and only slightly larger than an average domestic cat, as well as easily adaptable to live in captivity, it’s strange that the red panda has not become popular as a pet.

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References:

Pradhan, S.; Saha, G. K.; Khan, J. A. 2001. Ecology of the red panda Ailurus fulgens in the Singhalila National Park, Darjeeling, India. Biological Conservation, 98(1): 11-18.

Wikipedia. Red Panda. Available at: <https://en.wikipedia.org/wiki/Red_panda&gt;. Access on January 28, 2016.

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Zika virus and the negligence towards health research in poor countries

ResearchBlogging.org by Piter Kehoma Boll

About a year ago, almost nobody on the whole world was aware of the existence of a virus named Zika virus and the illness it may cause in humans, the Zika fever or Zika disease. But is this a new, previously unknown virus? Where did it come from and why is it suddenly of so much concern?

The Zika virus, or ZIKV, is a virus in the genus Flavivirus, which also include other viruses, such as the ones responsible for the dengue fever and the yellow fever. The name Flavivirus means “yellow virus” in Latin, due to the yellow fever. All the three diseases are transmitted to humans throughs mosquitoes, especially the widespread Aedes aegypti.

The mosquito Aedes aegypti is currently the main vector of the Zika virus. Photo by James Gathany.

The mosquito Aedes aegypti is currently the main vector of the Zika virus. Photo by James Gathany.

The Zika virus was discovered in 1947 in Uganda in a febrile rhesus monkey in the Zika Forest, hence the name. From 1951 on, serological studies indicated that the virus could also infect humans, as antibodies against the virus were found in the blood of humans in several African and Asian countries, such as Central African Republic, Egypt, Gabon, Sierra Leone, Tanzania, Uganda, India, Indonesia, Malaysia, the Philippines, Thailand and Vietnam.

In 1968, in Nigeria, the virus was isolated from humans for the first time. During the following decades of the 20th century, the virus was detected via serological evidence or isolated directly in many humans. However, despite the confirmation of this virus in humans, research developed very slowly, most likely because the affected countries don’t have enough resources to conduct the necessary studies and richer countries are not at all interested in the health of the poor ones.

There was a small increase in concern over the virus after it was detected outside Africa and Asia for the first time, in 2007, in the Yap Island, Micronesia. After that, some epidemics occurred in several archipelagoes in the Pacific.

Since last year, the Zika virus has been dectected in South America and started to spread rapidly across the countries. It was suggested that the virus reached Brazil in 2014 during the World Cup. (Thanks, FIFA!). By November 2015, the disease has reached Mexico, which means it is about to reach the United States! Now suddenly it started to be of a major concern worlwide.

Currently known distribution of the Zika virus in humans. Map of the United States Centers for Disease Control and Prevention.

Currently known distribution of the Zika virus in humans. Map of the United States Centers for Disease Control and Prevention.

Common symptoms of the Zika fever include mild headaches, fever, joint pains and rash. It was not considered a serious disease, as it usually fades quickly after a week, until recently, when it was linked to the development of microcephaly in fetuses of mothers infected by the virus during the first trimester of pregnancy.

I wonder how many children were born with microcephaly in Africa and Asia during the last decades because there was no investment to study the virus. Now that it suddenly became a worldwide threat, there is no vaccine, no adequate treatment and most physicians are unable to identify the illness through the symptoms.

And there are a lot of other viruses forgotten in poor tropical countries just waiting for the right opportunity to spread and scare North America and Europe. No one cares while they remain among poor African and Asian people, but global warming is here and tropical diseases love it more than anything else.

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References:

Gatherer, D. & Kohl, A., (2015). Zika virus: a previously slow pandemic spreads rapidly through the Americas Journal of General Virology DOI: 10.1099/jgv.0.000381

Hayes, E. B. 2009. Zika Virus Outside Africa. Emerging Infectious Diseases, 15(9): 1347-1350.

Vasconcelos, P. (2015). Doença pelo vírus Zika: um novo problema emergente nas Américas? Revista Pan-Amazônica de Saúde, 6 (2), 9-10 DOI: 10.5123/S2176-62232015000200001

Wikipedia. Zika virus. Available at: <https://en.wikipedia.org/wiki/Zika_virus&gt;. Access on January 25, 2016.

 

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Friday Fellow: Taq

by Piter Kehoma Boll

It’s time for us to start to look at the tiny little creatures living with us in this world. We haven’t featured any bacterium yet, so here comes the first one, the magnificent Taq!

Taq stands for Thermus aquaticus, the bacterium’s scientific name. It was initially discovered in hot springs of the Yellowstone National Park, but certainly no one could guess how it would impact science as a whole.

The Great Fountain Geyser in Yellowstone National Park is located near the place where Taq was first found. Photo by Paul Kordwig.*

The Great Fountain Geyser in Yellowstone National Park is located near the place where Taq was first found. Photo by Paul Kordwig.*

Usually with a small rod shape less than 1 µm in diameter and up to 10 µm in length, Taq can also reach more than 200 µm in length when acquiring a filament shape. Living in hot springs all around the world, it thrives at about 70°C. It produces its own food via chemosynthesis by oxydizing inorganic elements in the environment, but it can also associate with some cyanobacteria living in the same habitat to obtain food from their photosynthesis.

Taq under the microscope. The scale corresponds to 1µm. Photo by Diane Montpetit.

Taq under the microscope. The scale corresponds to 1µm. Photo by Diane Montpetit.

But what impact did it have in science? Well, because it lives in such high temperatures, Taq’s proteins need higher temperatures to denature, so they are useful to perform biochemical processes in high temperatures, such as in DNA amplification.

PCR (polymerase chain reaction) is a process used for amplifying short segments of an organism’s DNA. It needs to be performed in high temperatures in order to denaturate the DNA chain so that the primers can align. Primers are very short modified DNA fragments that determinate the beginning and the end of the segments that one wants to amplify. Amplifying a DNA segment means producing a large amount of copies of that segment. The problem in earlier PCRs was that the high temperatures needed to denaturate the DNA also denature the enzyme that produces the copies, called DNA polymerase. As a result, there was a need to add enzyme after every cycle of thermal denaturation. The DNA polymerase of Taq, called Taq polymerase, can resist the high temperatures of denaturation, so that it needs to be added only once.

Thanks to Taq polymerase, DNA amplification has become a much more efficient process, accelerating researches in molecular biology.

Sometimes revolution beginns with the tiniest things.

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References:

Brock, T. D. 1997. The value of basic research: discovery of Thermus aquaticus and other extreme thermophiles. Genetics, 146(4): 1207-1210.

Wikipedia. Thermus aquaticus. Available at: <https://en.wikipedia.org/wiki/Thermus_aquaticus&gt;. Access on January 21, 2016.

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The blacker the better… especially in Chernobyl

ResearchBlogging.org by Piter Kehoma Boll

We all know that plants use chlorophyll and other pigments to harvest energy from light and store it in synthesized molecules, a phenomenon called photosynthesis. It’s chlorophyll that makes plants (all well as some bacteria and algae) green. This ability to create their own food via photosynthesis is what separates cyanobacteria, algae and plants from other organisms, such as animals, fungi and protozoan, as the latter are usually seen as unable to harvest energy directly from the medium.

This view is changing, however, especially for fungi.

As most organisms, fungi also have pigments, and one of the most important ones is melanin (yes, the same pigment that makes our skin, hair and eyes dark). For some time it is known that fungi living in areas with a higher incidence of solar radiation are richer in melanin than those in less illuminated areas. It happens, for example, in the black mould, Aspergillus niger, a species that attacks many vegetables, but also exists all over the world in the soil.

Aspergillus niger, the black mold, is a melaized fungus found worldwide and that seems to love ionizing radiation. Photo by wikimedia user Y_tambe.*

Aspergillus niger, the black mold, is a melaized fungus found worldwide and that seems to love ionizing radiation. Photo by wikimedia user Y_tambe.*

The simple fact that fungi exposed to higher radiation levels are darker could simply mean that they are protecting themselves using melanin from the nocive light striking them. After all, that’s what happens in animals, including humans, right?

But that’s not the case. Melanized fungi actually seem to thrive in environments with high levels of ionizing radiation (ultraviolet, x and gamma rays), which is usually seen as very dangerous to life. The walls of the damaged nuclear reactor of Chernobyl are covered in melanized fungi and they also are found living very happy on board of the Internation Space Station. Experiments showed that these melanized species of fungi seem to benefit from radiation, increasing their growth and germination.

How could this happen? Well, the only reasonable answer seems to be that melanin is acting like a photosynthetic pigment, allowing fungi to use ionizing radiation as a source of energy! And several experiments confirmed that!

Aspergillus niger growing on an onion. Image extracted from gardener.wikia.com.*

Aspergillus niger growing on an onion. Image extracted from gardener.wikia.com.*

So, the next time you see a big black mold growing somewhere, remember that it’s color is as important to it as the green is for the plants. They are really able to use melanin as plants use chlorophyll and yet they can do it using radiation that would be lethal to other lifeforms.

In the end, fungi are more similar to plants than we thought when we used to considered them to be plants too.

Too bad that we cannot use the melanin in our own skin for the same purpose…

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Reference:

Dadachova, E., & Casadevall, A. (2008). Ionizing radiation: how fungi cope, adapt, and exploit with the help of melanin Current Opinion in Microbiology, 11 (6), 525-531 DOI: 10.1016/j.mib.2008.09.013

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Friday Fellow: Shoebill

by Piter Kehoma Boll

When I first saw a picture of this bird, many years ago, my first thought was that it could not be real. It looked like a character of an old Hanna-Barbera animation and not like a real creature.

A real bird or a cartoon character? Behold the shoebill! Photo by Olaf Oliviero Riemer.

A real bird or a cartoon character? Behold the shoebill! Photo by Olaf Oliviero Riemer.*

The shoebill (Balaeniceps rex), also known as whalehead or shoe-billed stork, is a large African bird originally thought to be closely related to the true storks, as its body somewhat resembles that of a stork. However, molecular studies concluded it to be more closely related to pelicans, as well as to herons and ibises (which previously were also considered to be closer to storks!).

As one can easily notice, the name shoebill comes from the bird’s massive bill. The pointed upper jaw and the sharp edges of the bill help the shoebill to capture prey and tear them to pieces. The most frequent prey are fish, but it may also consume frogs, snakes, small monitors and crocodiles, as well as, more rarely, turtles, rodents and small birds.With a height typically between 110 and 140 cm, but able to reach 150, the shoebill is a tall bird. Its wingspan is also big, reaching up to 260 cm.

Certainly an interesting bird to look at. Photo by wikimedia user Quartl.*

Certainly an interesting bird to look at. Photo by wikimedia user Quartl.*

The shoebills are solitary birds and even in crowded areas they avoid to stay to close to each other.  They apparently love hippos, as the disturbance that these large beasts create in water help them to obtain food by forcing fish to the surface.

The IUCN lists the shoebill as ‘vulnerable’ and its major threats include habitat destruction and hunting. Currently there are about 5,000 to 8,000 individuals with a disconnected distribution along river basins in sub-Saharan Africa.

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References:

John, J. R. M.; Nahonyo, C. L.; Lee, W. S.; Msuya, C. A. 2013. Observations on nesting of shoebill Balaeniceps rex and wattled crane Bugeranus carunculatus in Malagarasi wetlands, western Tanzania. African Journal of Ecology, 51(1): 184-187. DOI: 10.1111/aje.12023

Wikipedia. Shoebill. Available at: <https://en.wikipedia.org/wiki/Shoebill&gt;. Access on January 13, 2016.

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Endosperm: the pivot of the sexual conflict in flowering plants

ResearchBlogging.org by Piter Kehoma Boll

The theory of sexual selection, based on the idea that there are conflict of interests between males and females, is quite recognized, but almost entirely focused on animals, especially dioecious animals, i.e., animals in which males and females correspond to separate individuals. Meanwhile, hermaphroditic animals and other organisms, such as plants, are usually ignored, but does hermaphroditism or “non-animalism” prevent the occurrence of sexual selection?

The peacock is one of the most famous examples of how sexual selection can drive the evolution of dioecious species. Photo by Oliver Pohlmann.

The peacock is one of the most famous examples of how sexual selection can drive the evolution of dioecious species. Photo by Oliver Pohlmann.

In the last decades, hermaphroditic animals started to be investigated more deeply concerning sexual conflict as a considerable evolutionary force in these organisms. For example, some studies demonstrated that many hermaphrodites, during copulation, fight to play the role of male, or female, in something called “gender conflict” (which DOES NOT HAVE ANYTHING TO DO with any social aspect of the word “gender”. Here it refers to the sexual role that a hermaphroditic organisms plays during sex).

In plants, on the other hand, the subject is much less explored, especially due to the lack of direct interaction between the two mating organisms. Reproductive strategies in plants were seen, for a long time, as a mean to ensure the supposedly difficult task to unite male and female gametes when one is a sessile organism, i.e., an organism unable to move. After all, this disadvantage forces these organisms to develop special techniques that guarantee the transport of gametes through the environment. With such a relevant problem to assure that sex will happen, it seems absurd to think that plants could yet afford to choose with whom to get laid.

737px-Bee_merry_(8199716283)

Plants need external agents, such as wind, water or animals, to carry their gametes. Photo by psyberartist (flickr.com/people/10175246@N08).*

So far, the most approached point about sexual selection in plants is related to mechanisms developed by the female part to avoid the ovule to be fertilized by pollen of the same individual (the so-called self-fertilization) or of incompatible individuals (such as pollen of another species or of a close relative, because yes, incest can be a taboo even for plants). Another studied mechanism is related to the prevention of future attempts of fertilization once the zygot has been formed, as an already fertilized flower is not interested in receiving more and more pollen grains.

The passive travel of pollen from the male part to the female one gives us the impression that the male part cannot carry out any intersexual selection. After all, once the pollen arrives at a flower, it cannot leave, so its only chance is to try fertilization in any case, even if it is on an incompatible organism. This also highlights the fact that competition between pollen grains may occur on the female part, on a real race to see who gets first to the ovule. This competition may be controlled by the female part by changings in pollen receptivity.

Pollen_competition

When a pollen grain reaches the female part of a flower, it has no option but to germinate, creating a pollen tube that grows towards the ovule. In this picture, three pollen tubes are running towards the ovule and one of them has a clear advantage over the others. It may be because it arrived first or because the female part changed its receptivity to accept this specific grain more eagerly than the others.

An intriguing aspect in angiosperm reproduction is the phenomenon of double fertilization. When a pollen grain falls onto the female organ, it germinates, originating a long tube that grows towards the ovule, the so-called pollen tube. The pollen tube carries with it two male gametes: one of them will fertilize the egg cell, giving rise to the zygote that will form the embryo, and the other fertilizes the central cell, an auxiliary cell that accompanies the egg, giving rise to a second zygot that forms the endosperm, a tissue that feeds the embryo during its development.

double_fertilization

In the double fertilization of angiosperms, the pollen tube carries two male gametes to the ovule. One of them will fertilize the egg cell, leading to the embryo, and the other will fertilize the central cell, originating the endosperm.

Since the egg and the central cell, as well as both male gametes, are genetically identical, the endosperm is also identical to the embryo and may be seen as an altruist that sacrifices itself to assure the survival of its sibling. The evolutionary origin of the endosperm and its adaptive advantage remain subjects of much discussion and without much solution. The situation is yet more complicated because, in most angiosperms, the endosperm is triploid, having a duplicate maternal material because the central cell has two nuclei. In other words, the endosperm has two copies of the maternal genes and one copy of the paternal genes (configuration 2m/1p), while the embryo is an ordinary organism, having one copy of the maternal genes and one copy of the paternal genes (configuration 1m/1p).

Several hypothesis on the reason that led to the rising of this selfless triploid sibling have been raised and are usually based on different interpretations on the sequence of the events that happened during the evolution of the group. Functionally, the endosperm works are the female gametophyte of other plants, which is, in these, responsible for nourishing the developing embryo. The female gametophyte is the “mother” of the embryo, just like the pollen grain (male gametophyte) is the “father”. The plants with the flowers are, therefore, the embryo’s grandparents. Crazy, isn’t it? But that’s the rule for plants. One generation of large organisms (the sporophyte), gives rise to a generation of tiny organisms (the gametophyte), which in turn will “mate” to generate new large organisms.

Going back to the subject, the functional similarity between the endosperm and the female gametophyte seems to favor the hypothesis that the endosperm was initially a maternal tissue (having, therefore, an original configuration 1m/0p or 2m/0p) and the paternal intromission happened later. On the other hand, the phenomenon of double fertilization is also found in Gnetales (supposedly the closest group to angiosperms) and, in these, double fertilization originates two identical embryos. In addition, basal angiosperms also have diploid endosperms, with a single copy of chromosomes from each parent (1m/1p). This scenario points to a primitive situation of two embryos, in which one of them was deviated to the role of endosperm.

Here we need to include one more important concept in biology: genome imprinting. It is a phenomemon in which genes are differently expressed depending on the parent from which they came; and it is usually seen are a consequence of sexual conflict. What happens is that paternal cells may be silenced in some cells, so that the organism expresses, in those cells, only features inherited through the mothers. The opposite may also happen.

It is assumed that, in angiosperms, the paternal side benefits from the production of large endosperms that provide more nutrients to the embryo, so that there is interest both to express genes leading to a higher accumulation of resources coming from the mother and to silence genes that limit growth. In contrast, the maternal side would attempt to limit the nutrients destined to a single endosperm, as the excess of investment would compromise its future reproductive success. It is better for the mother to invest a little in each endosperm than to invest everything in a single one. Therefore, the maternal side would express genes that control the amount of resources invested in each embryo while inhibiting genes inducing an increased growth.

In such a scenario with genome imprinting, the increased expression of genes by duplication may be seen as a female strategy to counterattack a male attempt to express genes responsible for resource allocation. The paternal plant would express genes for resource collection, while the maternal plant, with two copies of its material in the endosperm, would express genes leading to a contrary response in higher intensity, trying to stop the paternal influence. Such a phenomenon has been attested in corn seeds, where 2m/0p endosperms are smaller than 2m/1p endosperms. As we can see, there is a fight between males and females even among plants!

In angiosperms, fertilization involves the direct interaction of five distinct organisms belonging to three generations: female sporophyte (maternal plant), masculine gametophyte (pollen grain), female gametophyte (ovule), embryo and endosperm. Each one of these organisms has an interest that may be contrary to one or more interests of the others, leading to a complex interaction still poorly defined and in which the endosperm certainly constitutes the most intriguing point and may be the consequence of certain strategies and, at the same time, lead to the emergence of new ones.

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References and further reading:

Alcock J (2001) Animal Behavior, 7th edn. Sinauer Associates, Sunderland

Arnqvist G, Rowe L (2005) Sexual Conflict: Princeton University Press, Princeton, N. J

Baskin, J., & Baskin, C. (2015). Pollen (microgametophyte) competition: an assessment of its significance in the evolution of flowering plant diversity, with particular reference to seed germination Seed Science Research, 25 (01), 1-11 DOI: 10.1017/S0960258515000033

Beale, K., & Johnson, M. (2013). Speed dating, rejection, and finding the perfect mate: advice from flowering plants Current Opinion in Plant Biology, 16 (5), 590-597 DOI: 10.1016/j.pbi.2013.08.005

Becraft, P. (2012). Endosperm Imprinting: A Child Custody Battle? Current Biology, 22 (3) DOI: 10.1016/j.cub.2011.12.043

Cailleau, A., Cheptou, P., & Lenormand, T. (2009). Ploidy and the Evolution of Endosperm of Flowering Plants Genetics, 184 (2), 439-453 DOI: 10.1534/genetics.109.110833

Charnov EL (1979) Simultaneous hermaphroditism and sexual selection. PNAS 76:2480–2484.

Davies NB, Krebs JR, West SA (2012) An introduction to behavioural ecology, 4th edn. Wiley-Blackwell, Oxford

Dresselhaus, T., & Franklin-Tong, N. (2013). Male–Female Crosstalk during Pollen Germination, Tube Growth and Guidance, and Double Fertilization Molecular Plant, 6 (4), 1018-1036 DOI: 10.1093/mp/sst061

Fetscher AE (2001) Resolution of male-female conflict in an hermaphroditic flower. Proc R Soc B 268:525–529. doi: 10.1098/rspb.2000.1395

Friedman WE (1995) Organismal duplication, inclusive fitness theory, and altruism: understanding the evolution of endosperm and the angiosperm reproductive syndrome. PNAS 92:3913–3917. doi: 10.1073/pnas.92.9.3913

Friedman WE (1998) The evolution of double fertilization and endosperm: an “historical” perspective. Sex Plant Reprod 11:6–16. doi: 10.1007/s004970050114

Friedman WE (2001) Developmental and evolutionary hypotheses for the origin of double fertilization and endosperm. Comptes Rendus de l’Académie des Sciences – Series III – Sciences de la Vie 324:559–567. doi: 10.1016/S0764-4469(01)01326-9

Grossniklaus U, Spillane C, Page DR, Köhler C (2001) Genomic imprinting and seed development: endosperm formation with and without sex. Curr Opin Plant Biol 4:21–27. doi: 10.1016/S1369-5266(00)00130-8

Haig D, Westoby M (1989) Parent-Specific Gene Expression and the Triploid Endosperm. Am Nat 134:147–155.

Haig D, Westoby M (1991) Genomic Imprinting in Endosperm: Its Effect on Seed Development in Crosses between Species, and between Different Ploidies of the Same Species, and Its Implications for the Evolution of Apomixis. Phil Trans R Soc B 333:1–13. doi: 10.1098/rstb.1991.0057

Härdling R, Nilsson P (1999) Parent-Offspring and Sexual Conflicts in the Evolution of Angiosperm Seeds. Oikos 84:27–34. doi: 10.2307/3546863

Lankinen, A., & Madjidian, J. (2011). Enhancing pollen competition by delaying stigma receptivity: Pollen deposition schedules affect siring ability, paternal diversity, and seed production in Collinsia heterophylla (Plantaginaceae) American Journal of Botany, 98 (7), 1191-1200 DOI: 10.3732/ajb.1000510

Leonard JL (1990) The Hermaphrodite’s Dilemma. J Theor Biol 147:361–371. doi: 10.1016/S0022-5193(05)80493-X

Maruyama, D., Hamamura, Y., Takeuchi, H., Susaki, D., Nishimaki, M., Kurihara, D., Kasahara, R., & Higashiyama, T. (2013). Independent Control by Each Female Gamete Prevents the Attraction of Multiple Pollen Tubes Developmental Cell, 25 (3), 317-323 DOI: 10.1016/j.devcel.2013.03.013

Mazer SJ (1987) Maternal investment and male reproductive success in angiosperms: parent-offspring conflict or sexual selection? Biol J Linn Soc 30:115–133. doi: 10.1111/j.1095-8312.1987.tb00293.x

Prasad NG, Bedhomme S (2006) Sexual conflict in plants. J Genet 85:161.

Schärer, L., Janicke, T., & Ramm, S. (2015). Sexual Conflict in Hermaphrodites Cold Spring Harbor Perspectives in Biology, 7 (1) DOI: 10.1101/cshperspect.a017673

Spira TP, Snow AA, Whigham DF, Leak J (1992) Flower Visitation, Pollen Deposition, and Pollen-Tube Competition in Hibiscus moscheutos (Malvaceae). Am J Bot 79:428–433. doi: 10.2307/2445155

Winsor JA, Peretz S, Stephenson AG (2000) Pollen competition in a natural population of Cucurbita foetidissima (Cucurbitaceae). Am J Bot 87:527–532

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Friday Fellow: Red Euglene

by Piter Kehoma Boll

Don’t be as fool as the Egyptian Pharaoh in the myth of the Plagues of Egypt. If you happen to find a lake with red water, as in the picture below, it is certainly not blood. It’s simply… a toxic alga!

Sometimes one may find the waters of a like turned red. Photo extracted from naturamediterraneo.com/forum/, posted by user Carlmor.

Sometimes one may find the waters of a lake turned red. Photo extracted from naturamediterraneo.com/forum/, posted by user Carlmor.

The creature responsible for this coloration is today’s Friday Fellow: Euglena sanguinea, or the red euglene, a microscopic freshwater protist with a worldwide distribution. This unicellular organisms has a red color due to the presence of astaxanthin, a pigment also found in some fish, like salmon, and in crustaceans, like shrimp and crayfish. Some birds may also have this pigment in their feathers. In red euglenes, astaxanthin acts as a protection against ultraviolet radiation, so that the higher the amount of UV radiation, the redder the algae become.

A fraction of a population of red euglenes under the microscope. Photo extracted from naturamediterraneo.com/forum/, posted by user Carlmor.

A fraction of a population of red euglenes under the microscope. Photo extracted from naturamediterranea.com/forum/, posted by user Carlmor.

When the conditions are adequate, usually due to high temperatures and high amounts of nutrients, the red euglene may overpopulate and cover the entire surface of water bodies, making it appear red. Water pollution, especially from domestic wastewater, is one of the main causes of nutrient increase in water bodies and thus a direct cause of many algal blooms.

The red euglene is known to produce euglenophycin, a very potent ichthyotoxin, i.e., a compound that is toxic to fish. As a result, red euglene blooms can lead to high fish mortality, making it an organism of major concern to fish breeders.

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References:

Gerber, S.; Häder, D-P. 2006. Effects of enhanced UV-B radiation on the red coloured freshwater flagellate Euglena sanguineaFEMS Microbiology Ecology, 13(3): 177-184. DOI: 10.1111/j.1574-6941.1994.tb00064.x

Wikipedia. Euglena sanguinea. Available at <https://en.wikipedia.org/wiki/Euglena_sanguinea&gt;. Access on  January 07, 2016.

Zimba, P. V.; Rowan, M.; Triemer, R. 2004. Identification of euglenoid algae that produce ichthyotoxin(s). Journal of Fish Diseases, 27: 115-117.

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