Algae
May 5, 2008
Macrocystis sp.
I'm surprised that no kelp flies made it into this photograph. Dipterans (perhaps in the Coelopidae) seemed to be swarming on all of the knotted kelp clumps found on the rocky Weston Beach at Point Lobos. As Dr. William Bushing notes in this article on Macrocystis pyrifera, "...These decaying kelp plants provide food for many of the sandy beach invertebrates including kelp flies and beach hoppers on the surface, and marine life that burrows into the sand."
Even though there are no flies to spot, a close look will net you a reflection of me in the lower left pneumatocyst (I was wearing a hat) and partial reflections in the other two (mostly of the legs of the tripod).
Posted by Daniel Mosquin at 12:00 AM| Comments (9)
March 11, 2008
Chytriomyces sp.
The series for UBC Research Week continues. Today's write-up and photos are courtesy of Toko Mori. Toko writes:
My name is Toko Mori, a first-year graduate student in the Berbee Lab at the University of British Columbia. I study chytrid fungi, microscopic fungi that mainly live in freshwater. I especially focus on the local chytrids that parasitize freshwater microscopic algae. My long-term research goal is to create a tree of life of chytrids that parasitize algae and to see if there is any coevolutionary relationship between the species of parasitic chytrids and those of their host algae. I collected this chytrid on an alga, Vaucheria, from Burnaby Lake (Burnaby, BC) in August 2007. I have cultured it on agar and also co-cultured it with Vaucheria since then.
Since it seems that this is the first entry of chytrids in the Botany Photo of the Day, let me explain what they are. Chytrids are fungi, although they look quite different from mushrooms and molds, which we often think of as fungi. There are about one thousand species of chytrids which form the Phylum Chytridiomycota. Being the only group of fungi which reproduce by motile cells called zoospores (shown in picture 4), chytrids are considered to have diverged from the other fungi very early in their evolutionary history. Having motile spores gives them reproductive advantage in water. However, this is a double-edged sword; chytrids are unable to reproduce without moisture and thus bound to aquatic habitats.
Chytrids have recently attracted public attention as a cause for the population decline of amphibians. However, not all the chytrids are amphibian pathogens. To the contrary, many chytrid species are decomposers of organic matter in ponds and lakes, or parasites of microscopic invertebrates or algae, as in this case. Not much is known about their ecological roles.
Now let me explain these pictures. You are witnessing the moment of zoospore release, the highlight of their life history. The small round structure on the algal filament in picture 1 is a mature sporangium, where zoospores are produced. (The big bulge at the right end is a part of the alga, which I will explain later.) You can see the sporangium filled with small dots, each representing a zoospore. Five minutes later, the zoospores start to leave the sporangium, probably triggered by the sudden change in temperature caused by the intense light from the microscope. The change in pH of the surrounding water (when transferred from culture to a drop of distilled water on a slide) may also be the trigger. For a few minutes after the release, zoospores swarm just outside of the sporangium, until they start to swim away as in picture 3. As you may see in picture 4, the zoospores (ca. 4µm in diameter) have a flagellum like that of animal sperm. Eventually these zoospores stop swimming, retract their flagellum and encyst on a suitable substratum if they find one. Then they themselves will grow into a new sporangium, produce zoospores inside by mitosis, and start a new cycle of asexual reproduction.
A note for this alga. To co-culture this chytrid with its host, I received the culture of the host algal species, Vaucheria sessilis, from the Canadian Center for the Culture of Microorganisms at UBC. Vaucheria is unusual in that it lacks cell walls except when making reproductive structures; this entire filament seen here is one cell. The bulging end was formerly a spore, from which this algal filament grew.
Species identification is an important part of my research. Correct identification is the first step to making a tree of life. However, species identification of chytrids can be often difficult due to their simple body structure - there are not many morphological characters to study, at least on the light microscopy level. These days researchers combine molecular data and electron microscopy, together with traditional morphology. I have identified this chytrid down to the genus Chytriomyces, based on the light microscopic level morphology and molecular data.
Posted by Daniel Mosquin at 2:13 PM| Comments (13)
March 5, 2008
Laminaria setchellii
This entry is the second in a BPotD series for UBC Research Week, organized by Connor Fitzpatrick.
Dr. Rob DeWreede, Professor Emeritus in the Department of Botany, maintains a algae research lab at UBC. He provided today's photographs and write-up (note: the first photograph is courtesy of Dr. Colin Bates).
These photographs are of the kelp, Laminaria setchellii, a species of brown algae (Phaeophyceae). Both photographs were taken in Barkley Sound, which is located on the west coast of Vancouver Island, British Columbia, Canada. It is a region of much marine research, as it is adjacent to the site of the Bamfield Marine Sciences Centre, a research and teaching centre owned by three universities in British Columbia and two in Alberta.
Laminaria setchellii is a perennial seaweed, frequently found in the low intertidal and shallow subtidal zone, attached to rocks and, as here, intermingled with the seagrass Phyllospadix coulteri. As with all kelps, this macroscopic stage (the sporophyte) releases spores which germinate into separate microscopic male and female gametophytes, which in turn produce sperm and eggs, respectively. The egg, held on the female gametophyte, releases pheromones (chemicals which attract the motile sperm cells). The fertilized egg develops on the female gametophyte, overgrows the female gametophyte, and develops into a new diploid sporophyte phase.
Laminaria setchellii has been of interest to a number of students in the laboratory of Dr. DeWreede in the Department of Botany of the University of British Columbia. Ecological studies have included research on age structure and biomechanics of this kelp. Reports from the early 1900s suggested that some kelps had growth rings, and suggested also that these may be annual rings. We developed techniques that indicated that these rings are indeed formed annually, by much the same process responsible for the growth rings in trees. This knowledge opened a doorway of ecological investigation previously closed, e.g. research on age-related processes of these algae. We carried out research on the age distribution of populations of Laminaria setchellii under different ecological conditions, age-related reproductive effort, and age-related mortality. We discovered, for example, that individuals of Laminaria setchellii commonly live as long as 12 years, sometimes 20 – 24 years. Our studies on age-related reproductive effort enable us to test some hypotheses concerning reproductive effort in annual vs. perennial species of organisms, using seaweeds (research done by Terrie Klinger).
In addition, students in our laboratory have studied biomechanical properties of Laminaria setchellii, attempting to understand how these algae are able to tolerate the immense forces imposed on them by crashing waves generated by winter storms. For example, allowing for the greater density of water compared to air, crashing storm waves can impose forces equivalent to those generated by winds of 1000 km/hr! We investigated whether exposure to greater wave impact results in thicker stipes, larger holdfasts, or greater tissue strength, and the impact (on survival of Laminaria setchellii) of invertebrates such as crabs burrowing into the holdfast tissue (research done by Sophie Boizard). One conclusion from the data is that holdfasts of L. setchellii are “over-engineered”, as holdfasts of smaller diameter are attached with similar tenacity as larger holdfasts. However, if a holdfast segment is removed from the seaward-facing portion of the holdfast this results in significantly higher mortality than an identical segment removed from the lateral side of the holdfast. This result makes sense as a seaward-facing holdfast component experiences greater tensile stress than a lateral segment of the holdfast in breaking waves. Similarly, Laminaria setchellii holdfasts are asymmetrical, with more tissue allocated to seaward and shoreward parts of the holdfast.
Insights such as these are providing botanists and marine ecologists with a greater appreciation of the ways these fascinating organisms cope with some astounding physical forces, and how these apparently simple organisms can be used to test theories applicable to photosynthetic organisms more generally.
Posted by Daniel Mosquin at 9:02 AM| Comments (7)
February 25, 2008
Acetabularia sp.
Connor Fitzpatrick is the author of today's write-up. Connor writes:
Commonly known as mermaid's wineglasses, this algae comes courtesy of shyzaboy@Flickr during a beach exploration of the Grand Bahama Island. Given its location, it's very likely that this species is either Acetabularia crenulata or Acetabularia schenckii. The former has a large distribution: from coastal Florida, throughout the Gulf of Mexico and into Venezuela, the Caribbean Islands, India, the Philippines, and Australia. Acetabularia schenckii can be found off Florida, throughout the Gulf of Mexico and the northern coast of South America, although it has never been documented in the Bahamas.
The Acetabularia genus belongs to the Polyphysaceae family and contains twelve species. Like all other algae of the order Dasycladales, the Acetabularia are unicellular with a single nucleus (uninucleate). The thallus of the organism consists of a cap, a stalk, and a rhizoid, in which the nucleus can be found. Sexual reproduction is initiated with the formation of the cap at the stalk apex, at which point the nucleus undergoes a meiotic division followed by a series of mitotic divisions. The newly formed haploid nuclei travel up the stalk into the cap along with most of the cell contents. After this takes place the junction between the cap and stalk closes and gametangial walls begin to form enclosing the nuclei. The gametes are produced and released. Upon meeting, two gametes of opposite mating types will fuse and a new individual will form from the germinating zygote.
Another species of the genus, Acetabularia acetabulum, has proven instrumental in early studies of cell differentiation. In 1932, J.Hammerling conducted various experiments in which he grafted the enucleated (without a nucleus), cytoplasmic stalk portions of Acetabularia acetabulum onto a nucleate stalk of another species. The cap that grew from this individual was intially that of an Acetabularia acetabulum species, but if this cap was cut off the proceeding one would be that of the other species. Further experimentation led Hammerling to conclude that the regulation of cell differentiation took place in the cytosplasm, through the process called translation. Up until this point, it was believed that this regulation took place in the nucleus, through the process of transcription. Read more research on the ability of an enucleated fragment of Acetabularia mediterranea to initiate a cap (PDF).
The findings from early studies with Acetabularia helped clarify the central dogma of molecular biology, something which I had implicitly assumed to be indisputable. I guess being in school at a time when nothing but this dogma seems so absolute, it's hard for me to imagine a time when this wasn't the case. Thanks again to shyzaboy for a great shot! (original via BPotD Flickr Pool).
Posted by Daniel Mosquin at 9:04 AM| Comments (14)
October 27, 2007
Codium fragile subsp. tomentosoides
Thank you to Courtnay H, aka Seaweed Lady@Flickr, for sharing today's photograph (original image via BPotD Flickr Group Pool. If you love the sea and plants (like me), you certainly should view Courtnay's photographs on Flickr.
Courtnay suggests the following link to accompany her photograph: Codium fragile subsp. tomentosoides via Algaebase. If you visit that page, the word “weed” is used (Courtnay calls this photograph “beautiful invader”); indeed, this species is listed in the Global Invasive Species Database, with a comprehensive list of common names: dead man's fingers, green fleece, green sea fingers, oyster thief or Sputnik weed. Originally from Japan, it is now found in many temperate waters worldwide, its dispersal due to “shellfish aquaculture, recreational boating, and transport on ship hulls”.
The common name of oyster thief is due to this alga's tendency to proliferate in shellfish beds, where it can smother the shellfish with its rapid growth and colonial expansion. Sputnik weed is, as you might guess, a fifty year old common name from eastern North America. The introduction of this species to eastern North American waters was first observed around the same time as the launch of the Soviet Union's satellites.
Posted by Daniel Mosquin at 12:00 AM| Comments (2)
September 23, 2007
Pelvetia canaliculata
Botany Photo of the Day will have brief written entries on weekends, holidays and my vacations from April through September. – Daniel
Another nod of appreciation to Stephen B of Scotland aka stephenbuchan@Flickr for sharing today's photograph (original via the BPotD Flickr Pool). Thank you!
Channelled wrack can be found in the high intertidal zone on rocky shores of Atlantic Europe (e.g., in the United Kingdom).
Wikipedia has a tidy summary of Pelvetia canaliculata.
Posted by Daniel Mosquin at 12:00 AM| Comments (5)
July 5, 2007
Unidentified Algae
Botany Photo of the Day will have brief written entries on weekends, holidays and my vacations from April through September. – Daniel
Today's image is courtesy of bbum@Flickr, aka Bill from San Jose, California (original via BPotD Flickr Group Pool). Thank you!
If you'd like a challenge, try identifying this species of alga (I wasn't able to do it with an hour of searching, but then again, I'm not a phycologist!).
Posted by Daniel Mosquin at 12:00 AM| Comments (4)
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Botany Photo of the Day and all associated images are licensed under a Creative Commons License.
Botany Photo of the Day is a project of the UBC Botanical Garden and Centre for Plant Research, located in Vancouver, British Columbia Canada. UBC BGCPR is a department of the Faculty of Land and Food Systems within The University of British Columbia.