Category Archives: Animals

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.

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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

A New Breed of Pet

Specific puppy hybrids are high-cost designer pets.  Puggles and labradoodles are carefully bred to create desired characteristics such as less shedding or more docile personalities.

But research on a new breed may change the way people think about pets.  The new designer pet?  Foxes.

Research at the Institute of Cytology and Genetics in Siberia is breeding foxes to have the same docile characteristics as our favorite lapdogs.  This is the latest version of animals being bred for domestication.  The goal at that outset of the project, over 50 years ago, was to recreate the domestication of wolves into dogs.

With each generation of fox pups, researchers tested the responses of the foxes to humans – are they approachable, can they be pet, do they wag their tails?  Amazingly, instead of taking thousands of years, it took only a few years.

Just the second generation was approachable, the fourth generation allowed themselves to be pet, and by the sixth generation, the kits followed humans around and licked them – actions practically indistinguishable from that of pet dogs.

Even more interestingly than the domestication (at least to this biologist) were the physical changes that accompanied it.  Within 15 generations of the specially bred foxes, they acquired floppy ears, spotted coats, and curly and shorter tails.  These characteristics (called a domestication phenotype) are seen in many species of domesticated animals including dogs, pigs, and chickens.

These changes seen in many domesticated animals suggest that there is a set of genes that are shared by all animals capable of domestication.  The researchers in Siberia are currently searching for those genes.  However, the genes responsible for tameness are proving difficult to find.

And how do the genes affect docility and domestication?  No one knows yet, but one theory is that the genes control chemical signals in the brain that affect attitude.  These chemical changes may then have downstream effects on the physical appearance of the animals.

So, do you want a tame fox?  A company in Siberia will sell you one.  For the low, low price of just $6, 950 (transportation and paperwork included).  The youngest that foxes can be adoped is 3 ½ months old.  And I have to admit, they’re pretty cute…

 A domesticated fox pup

The company claims that caring for the foxes is much like caring for dogs.  They can live inside or outside and can benefit from having a crate.  They can eat dog food and can even be trained to use a litter box.  They should be walked and brushed regularly.

And apparently they’re rather playful.

So, if you’re up for it, you have $7,000 lying around, and you need something a little more interesting than a plain old dog, look into getting your very own pet fox!  Oh, and as for that genetic research – maybe it’ll lead us to the next domesticated pet.  Any bets on what it’ll be?

For more information, see the recent article in National Geographic, March 2011.  Want to buy your own fox?  Visit http://www.sibfox.com/