Tag Archives: Nature

VHS – Hemorrhagic Fish in the Great Lakes

In the process of completing a class project, I recently came upon the topic of viral hemorrhagic septicemia, or VHS, and I decided to do some research.  VHS is a viral fish disease that can cause large fish kills.  It is a rhabdovirus, a group of viruses that includes other disease-causing agents in fish.  “Rhabdo” means rod and refers to the shape of the virus.  There are a number of different types of the VHS virus.  The type found in the Great Lakes is nearly identical to the type isolated from the Maritime Region of Canada.

VHS virus

VHS is not a human pathogen and dies quickly at human body temperature.  However, the virus can cause large fish kills and change the dynamics of fisheries.  In Denmark, the disease caused deaths in rainbow trout farms leading to losses near $60 million US dollars annually in the early 1990s.

Fish kill

Large fish kills have also been seen in the Great Lakes region.  In 2006, fish mortalities were seen in several lakes throughout the region.  In 2008, round goby fish kills were seen in western Lake Michigan, and earlier this year a fish kill of thousands of gizzard shad was documented in the Milwaukee Harbor ship canals.

Once fish have been infected, deaths can occur days to weeks later.  It is important to note that some fish are able to fight off the disease.  Fish that are affected show hemorrhaging in the skin or near the eyes creating red patches.  Inside the fish, organs such as the liver, spleen and intestines are often filled with hemorrhages.  The ultimate cause of death is usually organ failure.

Hemorrhagic fish

VHS is transmitted between fish by exposure to bodily fluids or eating infected prey.  It also may enter the fish’s body through the gills or through open wounds.  VHS can also live outside of a fish in the water if conditions are right.  The most likely ways in which VHS is spread throughout waters are through the movement of fish (natural or by humans) and the movement of infected water in ballasts of shipping vessels or live wells of fishing boats.  Because the virus does not survive in birds and mammals, animals that eat infected fish are not likely to spread the disease.

It is not well known how or when the virus arrived in the Great Lakes region.  A likely explanation is that ballast water discharge from shipping vessels brought the virus to the lakes.  There are currently no effective treatments to stop fish to fish transmission of the disease or to treat infected fish.  Therefore, it is important that fishing and boating industries as well as recreational boaters and fishermen take precautions to avoid further spread of the virus.  With continued research and prevention steps, the virus will hopefully be stopped, fish kills will decrease, and we can all enjoy the beauty and the fish of the Great Lakes region for years to come.

Fishing on Lake Michigan

For more information about VHS, visit the Wisconsin DNR website or other DNR sites.

Fireflies and Science – An Enlightening Combination

Because they seem unusually abundant this summer (and in anticipation of an upcoming post), I thought I’d talk about fireflies today – fireflies and their role in scientific research.

Close-up

 There are over 2,000 species of fireflies, and they are named such due to the bioluminescence they produce to attract mates and deter predators.  The bioluminescent reaction is clearly seen on a hot summer night, especially in tropical and temperate climates.  Many people have fond memories of catching fireflies as children, gathering them in a jar with holes poked in the lid and enjoying the soft glow – a bioluminescent nightlight.

Firefly in jar (Sounds like the title of an ode)

 So what is bioluminescence?  Bioluminescence is the production of light by a living thing (bios = living, lumen = light).  This type of luminescence is a natural example of chemiluminescence – energy released as light through a chemical reaction.  It is seen in a variety of organisms including anglerfish, fungi and glowworm beetles (which are distinct from the firefly larvae that are also sometimes called glowworms).

While, as kids, we loved the blinking lights of the fireflies, few of us probably understood how the yellow-green glow was actually created.  It is indeed a chemical reaction.

Fireflies produce two compounds that make their light show possible.  One is called luciferin and the other is luciferase.  Luciferin is a pigment that reacts with oxygen to create the light we see.  Luciferase is a catalyst in this reaction meaning that it speeds up the reaction without being used up itself.  Other components within the firefly including magnesium and ATP, an energy source, fuel the reaction.

The energy resulting from the chemical reaction is released as heatless green, yellow, or reddish light (wavelengths between 510 to 670 nanometers for the light spectrum enthusiasts out there).

Light spectrum

It is this light that we see twinkling around us on hot summer nights.  In fact, scientists think the fireflies can control the pattern and speed of “twinkling” by controlling how much oxygen (a component of the reaction) they have in their bodies.

So what does this have to with scientists and research?  It turns out that the luciferase produced by fireflies can be a powerful research tool.  Organisms can be made to glow by engineering them to express the luciferase gene.  The plant below expresses luciferase, and when watered with a luciferin-containing mixture, it glows brightly.

Glowing tobacco plant

 Probably the most common use of luciferase in labs, and one that I found helpful in my own research, is as a reporter for what is happening within the DNA of a cell.  The luciferase gene can be engineered into a cell so that it is expressed only when a specific promoter – a segment of DNA that drives gene expression – is active.

So, if I wanted to know if a chosen promoter was active, I would create a stretch of DNA in which my promoter in question would lead to creation of luciferase when active.  Then, by adding luciferin to the mix, the presence or absence of light would tell me if luciferase was expressed and if my promoter was active.

Active promoter –> luciferase expression + luciferin = light (as in a firefly)

Inactive promoter –> no luciferase expression + luciferin = no light

Using this “equation” then, scientists can determine if a stretch of DNA is active merely my measuring whether light is produced.  This is one way in which firefly luciferase helps scientists do their work.

So the next time you catch a firefly, thank it for its contribution to science.  And then let it go so it can scare away predators, attract a mate and entertain kids of all ages with its bioluminescent backside.

A glowing backside

Eating Insects – A Sustainable Food Plan?

During a recent marathon of Andrew Zimmern’s “Bizarre Foods” episodes, I found myself intrigued by his oft-repeated claim that insects could be our answer to a world-wide food shortage and the expensive practice of raising livestock.

Of course, this claim often comes as Zimmern is biting into a scorpion, tarantula, or other nightmare-inducing organism, thus causing a cringe and not much further thought on the subject.

Zimmern and an insect feast.

However, for some reason, during this recent viewing of “Bizarre Foods,” I found myself intrigued by the idea.  So I did some searching to find out just how common this idea is to those “in the know.”  Turns out insects as food is a widely discussed option that could solve an ever-growing problem.

The costs of using livestock – chickens, cows, pigs – as major food sources are huge, both environmentally and economically.  And the use of large animals is wasteful.

Insects are a different story, though.

Insects are easy to raise requiring small amounts of water, food, and space.  Additionally, they are nutritious.  For example, catepillars are full of protein, zinc, calcium, and other vitamins.  The nutritional value of insects, while often overlooked in the US, is known and utilized throughout other parts of the world.

Therefore, due to the low cost and sustainability of insects as a food source as well as their potential to provide nutrition for people with little access to other vitamin- and protein-rich foods, the possibility of insects as a solution to world food shortages holds great promise.

Now if only those unaccustomed to eating the “pests” we usually try shooing out the door could get comfortable with the idea.  If it’s up to people like Zimmern and David Gracer, who works to convince chefs and “foodies” that insects are next big thing, perhaps the bug revolution will be here sooner rather than later.

Maybe we all just need to take a cue from Timon and Pumba of “Lion King” lore and enjoy the grubs.  Timon may be right – maybe they do taste like chicken!

Timon enjoying his insect delicacies.

 

 

 

Wisconsin History on the Ice Age Trail

With spring approaching (hopefully), everyone is looking forward to getting outside and taking advantage of all that Wisconsin has to offer in warmer weather.  On the Ice Age Trail, hikers can learn about Wisconsin history while taking a walk through beautiful scenery.

The Ice Age Trail is a hiking corridor that winds through 30 of the 72 counties in Wisconsin including Dane County.

Map of entire Ice Age Trail route when completed

The trail loosely follows the terminal moraine, or furthest advance, of the ice sheet present during the last continental glaciation – the Wisconsin Glaciation.  (For maps of the glaciation, see www.geology.wisc.edu/~davem/abstracts/06-1.pdf.)

It’s called the Wisconsin Glaciation because Wisconsin has some of the most interesting landforms that have survived since the time of the glacial epoch.  Much of the landscape was shaped by the glaciation that ended around 10,000 years ago.

As the ice moved south out of Canada, it split into various lobes.  The lobes stretched in various directions including one over Lake Michigan, one through the Wisconsin Valley and one over Lake Superior.  Many features of the Wisconsin landscape are a result of the impact of these lobes of ice on the earth.

The landscapes interpreted by the trail include forested areas, agricultural lands, prairies and wetlands.  On a segment of the trail near Devil’s Lake, a 25,000-year-old landscape can be found within a mile of a landscape that dates back 2 billion years.  These features allow hikers to witness landforms of various historical ages.

56 people have hiked the entire length of the trail (around 1,200 miles), but only about 640 miles are authorized as official segments of the Ice Age Trail.  New sections of trail are created around interesting features thus forming the educational trail.

Marker seen along official segments of the Ice Age Trail

The goal of the Ice Age Trail Alliance, the organization that builds and maintains the trail, is to interpret the history of Wisconsin through the landscape.  They aim to complete the entire length of trail within the next 50 years, thus creating a protected space that anyone can utilize and appreciate.

For more information and a glossary of terms, visit the Ice Age Trail Alliance website at http://www.iceagetrail.org/.

To plan a hike: Contact the Ice Age Trail Alliance at (800) 227-0046 for help planning your hike.  An Atlas and a Companion Guide with information about each section of the trail are available.  Visit http://www.iceagetrail.org/plan-a-hike for guidelines, trail closings and further suggestions.

To volunteer: Volunteers logged over 65,000 hours last year maintaining the trails.  To learn more about volunteer opportunities, go to http://www.iceagetrail.org/become-a-volunteer or contact the UW Hoofers Outing Club (http://www.hooferouting.org/) and ask about their projects with the Ice Age Trail Alliance.