Why study bioluminescence?

Aequorea4
The bioluminescent jellyfish Aequorea victoria is the source of green fluorescent protein (GFP) Credit: Sierra Blakely, Wikimedia Commons

My research team, which is funded by the National Science Foundation (NSF), explores bioluminescence—the biological production of light by natural chemical reactions.   Specifically we focus on the evolutionary origins of bioluminescence in Motyxia, the only millipede genus in California that is bioluminescent.

Interestingly, Motyxia are blind, and so their visual signaling can only be seen by members of other species, such as predators.  In addition, Motyxia produce hydrogen cyanide, an extremely poisonous gas as a chemical defense.  Some of our research indicates that Motyxia’s bioluminescence serves as a warning signal to deter nocturnal mammals from eating these highly poisonous millipedes.

By helping to reveal the evolutionary origins of bioluminescence, we can better understand and investigate how other complex traits arise in nature.  In addition, bioluminescence research has a history of offering many proven and potential societal benefits in fields ranging from national defense to medicine. Some examples:

  • Bioluminescence is also called “cold light” because the biochemical reaction that generates bioluminescent light is typically more than 90 percent efficient, meaning that only 10 percent of bioluminescent chemical energy is wasted as heat. By contrast, incandescent light bulbs are only 10 percent efficient! We could enhance the efficiency of our lighting systems by designing them to mimic natural bioluminescent reactions.
  • The bioluminescent underbelly of the marine bobtail squid blends with background light from the water’s surface and so decreases the squid’s vulnerability to attack from predators dwelling below it.  This natural camouflage offers the potential to inspire luminescent (glow in the dark) hulls for warships.  The U.S. Navy is currently studying marine animals that use bioluminescence.
  • All humans spontaneously release ultra-weak photon emissions and generate light through processes that are similar to bioluminescence in other animals. However, cancerous cells emit more light than do normal cells. This difference suggests that human luminescence may be used as a clinical tool to help diagnose illness and pinpoint the exact locations of cancerous cells.
  • NSF-funded biologist Osamu Shimomura wanted to know what caused the jellyfish Aequorea victoria to glow green. One protein he found in the jellyfish, called green fluorescent protein (GFP), has revolutionized how scientists study cells.  GFP is now widely used in biological and biomedical research as a fluorescent tag to help researchers track specific biological activities, such as the spread of cancer, the production of insulin and the movement of HIV proteins.  And in 2008, Shimomura along with Drs. Martin Chalfie and Roger Tsien received the Nobel Prize in Chemistry for the discovery and development of GFP.
  • The enzyme that is responsible for bioluminescence in beetles is used by researchers to carry out next-generation pyrosequencing—a fast, inexpensive method for sequencing genomes.  In 2008, pyrosequencing was, for the first time, used to sequence the full genome of an individual human; the human was Dr. James Watson—the co-discoverer of DNA. Also, in 2008, pyrosequencing was used to sequence the complete genome of a Neanderthal.
  • Enzymes responsible for bioluminescence are used by researchers to detect ATP (adenosine triphosphate), which is an essential substance for living cells.
  • A version of a light-emitting compound from the seed shrimp Vargula (a small bioluminescent crustacean) is used by researchers to measure superoxide anions, which are a critically important component of metabolic systems that are difficult to detect in nature.
  • Many types of physiological processes trigger changes in concentrations of intracellular calcium ions—an essential component of biological processes. One way to track intracellular calcium concentrations is to insert into cells a type of photoprotein known as aequorin, which is derived from the bioluminescent jellyfish A. victoria.  Aequorin is highly sensitive and specific to calcium and—most importantly—emits light when it reacts and thereby signals calcium concentrations.  In addition, it is non-toxic to most cells.
  • Other photoproteins derived from diverse animals might be used someday to help understand other complex but fundamentally important biological dynamics. For example, Beroe, a comb jelly and Thalassicolla, a radiolarian, might also be used to help detect calcium ions, and Harmothoe, a scaleworm, might be used to detect iron ions.

Next time you’re up late and it’s dark outside (even better right after a summer rain), visit your local natural area—a moist gully or streamside are the best. Turn off your flashlight and allow your eyes become adjusted to the light. Blue ghosts, railroad-worms, luminous millipedes, and snail-eating firefly larvae are some of the bioluminescent organisms you might see. When you observe these fascinating organisms, consider how they emit light and why their ability to bioluminesce evolved. But importantly, just take a moment to quietly observe the nightlife and nature’s living light.

Continue reading

Posted in Uncategorized | Tagged , , | 8 Comments

Parasitoid wasps

asobara
Parasitoid wasp in the family Braconidae (genus Asobara)

pachycrepoideus
Parasitoid wasp in the family Pteromalidae (genus Pachycrepoideus)

Jamie Wahls, grad student in Tom Kuhar’s Vegetable Entomology Lab @ VT, visited our lab again with some of his fascinating parasitoid wasps. These are images of unidentified species of braconid and pteromalid that we captured with our  microphotography system. Handsome beasts.

(Canon 6D, 65 mm lens, 3x, 1/125s, f5.6 – image stack)

Posted in Uncategorized | Tagged , , , | Leave a comment

The poisonous web of a bioluminescent fly

Orfelia_A
The toxic web of Orfelia fultoni (Diptera, Keroplatidae)

    While on a collecting trip to the Pisgah Mountains of North Carolina, we found the fly Orfelia fultoni. These luminous fly larvae dotted the mossy bank of a spring and emitted a continuous blue glow. The spectrum is the bluest of any terrestrial bioluminescence, and originates from the larva’s head and tail. This luminescence has been experimentally shown to be effective in attracting insect prey (Sivinski, 1982). The fly larvae, which were about 1 cm long and translucent, appeared on the surface of the moss suspended in a web adorned with little ampules of clear fluid. In the image above, the fluid-filled ampules appear as tiny white cones, and you can see the larvae just to the right of the web in the middle of frame, you’ll have to look close. The ampules are filled with oxalic acid and when an entangled insect disturbs them, they rupture spilling the toxic fluid onto the insect prey (Fulton, 1939).


References

  • Fulton, B. B. (1939). Lochetic luminous Diptera larvae. Journal of the Elisha Mitchell Scientific Society, 55, 289-293.
  • Fulton, B. B. (1941). A luminous fly larva with spider traits (Diptera, Mycetophilidae). Annals of the Entomological Society of America, 34(2), 289-302.
  • Sivinski, J. (1982). Prey attraction by luminous larvae of the fungus gnat Orfelia fultoni. Ecological Entomology, 7(4), 443-446.
  • Viviani, V. R., Hastings, J., & Wilson, T. (2002). Two Bioluminescent Diptera: The North American Orfelia fultoni and the Australian Arachnocampa flava. Similar Niche, Different Bioluminescence Systems. Photochemistry and Photobiology, 75(1), 22-27.
  • The adventurous blog of Danté Fenolio: anotheca.com/wordpress
Posted in Uncategorized | Tagged , , , , | Leave a comment

Collecting millipedes on Brush Mountain

MarekLab_GatewayTr
(left to right) Paul Marek, Jackson Means, Katy Lawler, Nina Zegler and Elizabeth Francis

On Friday, we collected millipedes on Brush Mountain near Blacksburg, Virginia. We found the genera Narceus, Pseudopolydesmus, Apheloria, Rudiloria, and Nannaria. Other fascinating discoveries included several species of plethodontid salamanders, a large imperial moth caterpillar, a giant crayfish, cryptocercid cockroaches, and an aggregation of dancing Beech blight aphids.

Posted in Uncategorized | Tagged , , , , | 1 Comment

Fruit fly parasitoids

figitid
Parasitic wasps in the family Figitidae (Eucoilinae), top male – bottom female.

Jamie Wahls, graduate student here in the Department of Entomology at Virginia Tech working in Tom Kuhar’s Vegetable Entomology Lab, recently visited our lab with some of his parasitoid wasps. This is an image of an unidentified species of figitid wasp, and fruit fly parasitoid, that we captured with our  microphotography system.

(Canon 6D, 65 mm lens, 3x, 1/125s, f5.6 – stack of 10 images)

Posted in Uncategorized | Leave a comment

A poem

Beautiful Millipedes

I dreamed I am a millipede
So beautiful and happy indeed
What genus to be?
Well, let’s see!

Brachoria, Motyxia or Illacme
Each with their own species
Some with colors bright
Some glow at night

Brachoria, with species of 34
Living in the Appalachian forest floor
Colors of orange, yellow, violet, red
Snug under leaves in a burrow bed

Motyxia, bioluminescent glow
In the dark a crawling show
Species of toxic 8
Searching for a cyanide mate

Illacme plenipes, leggiest of all
Rediscovered by Rob and Paul
750 and 666 legs plentiful
Such a wonderful spectacle!

*Poem contributed by the laboratory’s poet laureate and my dad, Bob Marek. When he is not writing poetry, Bob enjoys studying the U.S. Constitution and reading the New York Times. He is also volunteer at the Cleveland Museum of Natural History and Fieldstone Farm Therapeutic Riding Center.

Posted in Uncategorized | Tagged , , , , | Leave a comment

Pinwheel of millipedes

Brachycybe_lecontii
A quarter pinwheel of millipedes of the species Brachycybe lecontii Wood, 1864

A murder of crows, a murmuration of starlings…a pinwheel of millipedes? Last week, Dr. Matt Kasson, his student Cameron, and I went on an expedition to find the millipede Brachycybe lecontii. The picture shown above is an aggregation of about 15 individuals on a decaying piece of wood that we discovered in Buchanan County, Virginia (there are 10 or so small juveniles hidden beneath the adults). Often, Brachycybe are found in these aggregations where individuals are arranged radially with their heads facing a common center and tails diverging outwards (also shown here).

These millipedes are blind, slow-moving and eat fungus. They are also fascinating biologically:

  • First, B. lecontii produces an unknown chemical secretion from serially arranged pores lining the lateral tips of its segments.
  • Second, the species demonstrates exclusive male parental care of young. The males  care for the eggs and the young by holding them ventrally in a basket formed by their many legs. There’s evidence that the males groom the eggs and clean them of fungus and bacteria.
  • Third, B. lecontii are social and live in multi-generational clusters of individuals affectionately referred to as pinwheels.
  • Finally, the genus Brachycybe  lives in East Asia and North America, and in geological time the group’s evolutionary age predates the breakup of these continents.


References

  • Brewer, M. S., Spruill, C. L., Rao, N. S., & Bond, J. E. (2012). Phylogenetics of the millipede genus Brachycybe Wood, 1864 (Diplopoda: Platydesmida: Andrognathidae): Patterns of deep evolutionary history and recent speciation. Molecular Phylogenetics and Evolution, 64(1), 232-242.
  • Gardner, M.R. (1975) Revision of the millipede family Andrognathidae in the Nearctic region (Diplopoda, Platydesmida). Memoirs of the Pacific Coast Entomological Society, 5, 61 pp.
  • Hasegawa, E., Yao, I., Futami, K., Yagi, N., Kobayashi, K., & Kudo, S. I. (2012). Isolation of microsatellite loci from the millipede, Brachycybe nodulosa Verhoeff. Conservation Genetics Resources, 4(1), 89-91.
  • Kudo, S. I., Akagi, Y., Hiraoka, S., Tanabe, T., & Morimoto, G. (2011). Exclusive male egg care and determinants of brooding success in a millipede. Ethology, 117(1), 19-27.
  • Shelley, R. M., McAllister, C. T., & Tanabe, T. (2005). A synopsis of the milliped genus Brachycybe Wood, 1864 (Platydesmida: Andrognathidae). Fragmenta Faunistica, 48(2), 137-166.

 

Posted in Uncategorized | Tagged , , , , | Leave a comment

National Moth Week 2014

1279px-Graellsia_isabellae_MHNT_male_dos_
Spanish moon moth, Graellsia isabellae (Graëlls, 1849). D. Descouens CC BY-SA 3.0

Join entomologists from Virginia Tech and celebrate National Moth Week! Come out to the campus of VPI and discover insect biodiversity and nighttime nature. We’ll be across the street from Price Hall, near Duck Pond at 8:30PM this Thursday, July 24. We’ll have a mercury-vapor lamp, black light and insect nets.

This year’s NMW is celebrating the silk moth, insect family Saturniidae. Pictured above is a member of this family from Spain. It’s a close relative to our Luna Moth (Actias luna) here in the U.S. Saturniid moths are fascinating insects with a super sense of smell. They can detect just a few molecules of a chemical or pheromone with their frilly, plumose antennae! (Pictured above is a male, here’s a female.)

Posted in Uncategorized | Tagged , , | Leave a comment

Collecting in the Blue Ridge

BlueRidgeMountains
The Blue Ridge Mountains of North Carolina

Elizabeth, Jackson and I just returned from a three-day collecting expedition to the Blue Ridge Mountains of Virginia and North Carolina. It was an exhilarating three days and two nights, with little sleep and lots of beetles and millipedes. One of the best discoveries of the trip were bioluminescent fly larvae of the species Orfelia fultoni (Diptera, Keroplatidae) from the mountains of North Carolina. These nocturnal fly larvae are carnivorous and spin webs to entangle their prey, which they attract with their glowing blue light.

Cychrine_1149
Snail-eating ground beetle, genus Scaphinotus (Coleoptera, Carabidae). It’s pointed head is adapted for poking into the apertures of snails to feed on the soft body parts.

Helops_sulcipennis_1044
Helops sulcipennis (Coleoptera, Tenebrionidae). This flightless beetle occurs in the higher reaches of the Blue Ridge Mountains in dry habitats referred to as “Appalachian Deserts”.

Teneb_1125
Meracantha contracta (Coleoptera, Tenebrionidae), found exclusively on dead tree snags.

Posted in Uncategorized | Tagged , , , , , | Leave a comment

Millipede from Burkes Garden

Appalachioriaseparandahamata_0201
Appalachioria separanda hamata (Burkes Garden, Virginia)

The Appalachian Mountains hold a great diversity of colorful millipedes, including this species that we found during a recent collecting trip to Burkes Garden, Virginia. This is one of two color morphs that we found in this spot (special thanks to Tim McCoy for spying this one). The other morph has yellow stripes and legs instead of the red spots and orange legs shown in this individual. The red & black morph likely mimics Rudiloria kleinpeteri and the yellow morph, Apheloria virginiensis (both found in the area). Many of these instances of divergent coloration occur between individuals that are very closely related (based on uniform DNA barcoding sequences). The genetic mechanism controlling this in millipedes is unknown. However, the genetics of variable color mimicry in nymphalid butterflies has been investigated in several fascinating articles (Joron et al. Nature, 2011; Kunte et al. Nature, 2013).

Appalachioriaseparandacalcaria_0320
Appalachioria separanda calcaria (Brush Mountain, Virginia), another colorful millipede from just a few miles north of the Entomology Department @ Virginia Tech. (The little white patch above the red medial spot is neat.)

Posted in Uncategorized | 3 Comments