Maine Bumble Bee Atlas

Note: This program first aired on July 2, 2016.

Citizen science is a growing movement in this country. I’ve talked about it before on the show, describing the Signs of the Seasons program that uses the observations of amateur naturalists to document the phenological patterns of seasonal events, like when the red maple trees are in bloom, when various sea weeds become reproductive and when the first wood frogs are heard. The timing of those events results from environmental cues, particularly temperature, and thus changes in the timing of those key seasonal milestones could reflect and inform our understanding of how the environment is responding to climate change.

Another citizen science initiative underway here in Maine is the Maine Bumble Bee Atlas, a project designed to use trained volunteers to survey bumblebee populations throughout the state. Like the Butterfly and Dragonfly surveys before it, the goal of the Bumble Bee Atlas project is to document the abundance, diversity and distribution of bumblebees in Maine, in the absence of any good baseline data. Because we lack baseline data, we don’t really know what bees are here or how many of them there are. Historic records point to 17 different species of bumblebees in the state, but those historic records are incomplete. And while there have been documented declines in bumblebee populations in other parts of the country, we don’t know if that has happened here. At its simplest, the project will establish a baseline of understanding with data from all over the state, collected over a 5 year period, that will allow scientists to have a high degree of confidence that what is out there has truly been sampled, and that the data set really reflects the diversity distribution and abundance. You get enough people collecting enough data in enough places, you stand a high probability of having enough overlap to get good coverage. Citizen science is based on this premise, it accomplishes through the use of knowledgeable volunteers what it never could relying only on professional field biologists. There are plenty of us willing and interested volunteers, and not enough field biologists to generate this massive, multi year data set.

I recently attended the one day training session in preparation for participating in this year’s sampling season, and learned that volunteering is a great way to get education. I learned a lot I didn’t know about bumblebees, it was very exciting for a super nerd like myself. Bumblebees are of course of interest because of their ecological role as native pollinators of flowering plants. Something like 90% of angiosperm species rely at least in part on some form of animal pollination. Here in Maine there are many different insect species that perform this pollination job. The Lepidoptera (butterflies and moths), ants, beetles, wasps and hornets (especially the wasp and hornet queens), flies, bee flies (which are bee parasites), and bees. We have over 250 species of native bees in Maine, most of which are solitary bees, only 17 of which are bumble bees. Relative to other states this is actually a pretty low number of bee species. The boxes of honey bees you see on blue berry barrens in late spring are native to Europe, and are used commercially for agricultural pollination because their colonies grow large quickly, providing thousands of foraging (and thus pollinating) individuals in each colony.

It can’t be stressed enough the role these pollinators play in terrestrial ecosystems. Plants and insects have evolved over millions of years to rely on one another, and declines in pollinating insects result in declines in vegetation. Plants are the source of all of our energy, they are the means by which energy from the sun becomes useful to us biologically. In both ecological and agricultural systems, without mechanisms of pollination, you will see declines.

Next week we’ll look more closely at the specifics of bumble bee natural history, and learn how their lifestyle makes them unique among those 250+ species of native bees in Maine.

References:

Listing of citizen science opportunities throughout New England (not sure how up to date: http://newengland.stewardshipnetwork.org/citizen-science)

The Maine Bumble Bee Atlas home page: https://ac41277bd54735c2b85336aff6fdfbfd153fcee3.googledrive.com/host/0B985dSJVRA1maGtVekhDUkJjYWM/

The Maine Bumble Bee Atlas blog: http://www.maine.gov/wordpress/bumblebeeatlas/

The Maine Bumble Bee Atlas on Facebook (current and great photos!) https://www.facebook.com/MaineBumblebeeAtlas/

If you are curious, the Maine Butterfly Survey site: https://2d042df5ce2f94779d5a6c1b6c47d612202b3787.googledrive.com/host/0B985dSJVRA1mWm43NXVQWEhmVGM/

And the Maine Damselfly and Dragonfly Survey site: https://bad7c31b56f9e6bfcd572114fde5c911ee02ad88.googledrive.com/host/0B985dSJVRA1mbUNxVms3ejBSa1E/

Horseshoe Crabs

Note: This show first aired on June 18, 2016. 

Its June and the full moon is right around the corner and that makes some of us naturalist types on the coast of Maine excited to see horseshoe crabs. We should probably refer to them by their latin name Limulus polyphemus, because their common name is a misnomer, they aren’t crabs or even crustaceans at all. They are in the group Chelicerata, along with sea spiders, scorpions, land spiders, mites, and our favorite, ticks. Like all the Arthropods though (including all the insects and crustaceans), they have a chitinous exoskeleton and jointed legs. When you see them in the water, their armored head and body and long spike like tail look otherworldly. Their uneven erratic movement is jarring to watch. They look out of place, but what they really are is out of time. They are living fossils remaining essentially unchanged in the fossil record for the past 200 million years (they outlived the dinosaurs by a long shot)**, and with fossil ancestry going back nearly 400 million years. What they are still doing here it is hard to say, other than doing what they have always done, feeding on soft mud or sand bottoms, crawling around on the surface of the substrate or burrowing shallowly in, preying on small invertebrates like worms, bivalves and tiny crustaceans. As adults they don’t have many predators (logger head turtles are one, humans are another), and they are most at risk of predation when young, tasty little nibblelets.  

Traditional thinking has it that at the time of the late spring and early summer full and new moons, and the high tidal ranges typically associated with them, horseshoe crabs come up coastal estuaries to breed, laying eggs at the high water mark. And this timing does play out in the majority of the horseshoe crab’s range; on the broad sandy beaches of the inner bays on the mid Atlantic coastal plain, horseshoe crabs by the tens of thousands mount a beachhead assault on moonlit nights, laying millions upon millions of little blue green eggs in the sand. Look at the footage from Delaware Bay to see what I mean. Here in Maine though evidence shows that the crabs’ activity is not strongly associated with lunar period. They seem to be more cued to things like water temperature and salinity, and even weather (so us naturalist types can get over it and just go whenever things start getting warm). Down in Delaware, where horseshoe crabs are essentially at their ecological zenith, the timing is important not only because the beach habitats where these eggs are being laid are so uniform, and the tidal ranges lower than here, but also because other animals rely heavily on these eggs as a food source. Animals that are timing their arrival to Delaware Bay to coincide with the emergence of the horseshoe crabs from the sea.  Migrating shore birds like ruddy turnstones, sanderlings, plovers, and most famously perhaps red knots congregate by the tens of thousands as they migrate from the southern hemisphere, all descending on Delaware Bay for a horseshoe crab caviar feeding orgy that refuels them with nutritious high fat high protein eggs and enables the rest of their migration to high northern latitudes. This convergence is a wonder of nature. By comparison, what the horseshoe crabs do here in Maine pales.

Because they are at the absolute northern edge of their breeding range, populations of horseshoe crabs in Maine are found in isolated pockets, breeding not on wide open beach fronts but up in the estuaries of coastal rivers. They certainly provide a food resource for other marine organisms, and probably some migratory birds, but not in the keystone way they do further south. As an animal that time forgot, here in Maine they are doubly so, showing up more as a persistent oddity than a fundamental player in the food webs observed here. But as climate continues to change and waters warm many species are shifting their ranges to higher latitude. This may present difficulties for horseshoe crabs, as Maine’s coastline lacks their typical favored habitat, protected sandy beaches (most of our sandy beaches are apparently too high energy). And will all those birds that gorge themselves in the Chesapeake region be able to find them if they started breeding further north? These are the kinds questions we have to think about for all species as we watch climate change play out over our life times.

I would be remiss to not mention another reason people are interested in horseshoe crabs, and that is their blood. In areas where the crabs are abundant, they are collected at the shore and drained of much of their blood, which contains a protein that clots in the presence of gram negative bacteria. This blood factor is used to test medical equipment to ensure it sterility. If you’ve ever had surgery or an IV, it is likely you have benefited from this, and as of now there is no synthetic alternative. The crabs apparently can regenerate blood (much like we can) when returned to the ocean, which they are—and given human’s typical treatment of ocean resources, I think this shows amazing forethought. 

** Some say that calling them a "living fossil" is a misnomer, as the species in the fossil record are not the same as the modern Limulus polyphemus (which only dates back 20 million years or so). So be it. To me the term implies something that is strange to our eyes, because of how little it has changed, rather than something as weird as an orchid, weird because of the lengths to which is has changed....so yes, I think it is ok to call horseshoe crabs living fossils, even though, they aren't exactly perfectly unchanged from the Paleozoic era (see the last reference for more info).

References:

Great videos on this site:

http://naturedocumentaries.org/96/horseshoe-crabs-mating-maine/

https://www.fws.gov/northeast/pdf/horseshoe.fs.pdf

Older report on long term study in Maine:

http://www.cascobayestuary.org/wp-content/uploads/2014/07/2004_schaller_horseshoe_crab_surveys1.pdf

Report on long term study in Maine:

http://www.damariscottariver.org/wp-content/uploads/2015/12/Ten-Year-Report-Monitoring-of-the-Atlantic-Horseshoe-Crab-Limulus-polyphemus-During-the-Spawning-Season-in-the.pdf

http://dnr2.maryland.gov/fisheries/Pages/horseshoe-crab.aspx

Sample of the recent articles that refute the "living fossil" label http://phenomena.nationalgeographic.com/2011/11/22/in-evolutions-race-horseshoe-crabs-took-a-slower-pace/
 

Eastern Tent Caterpillars

Note: This show first aired June 11, 2016.

Early summer in Maine is astonishing. One moment the forest canopy is open, allowing glimpses of the newly arrived migrating warblers, a day or two later and the broad leaves have exploded from their buds, and any chance you had of seeing a tiny fast moving bird is gone. These rapidly growing fresh green leaves are not just a beautiful annoyance to bird watchers, but a nutritious salad bar for many of the insects that those warblers come here to eat. The young newly emerged leaves have a high water and nitrogen content to support their rapid growth, and generally lack the defensive chemicals that develop age, protecting the mature leaves. The high nutrient content combined with a lack of protection make them easy targets for developing insect larvae.
 

One type of larva that everyone has been freaking out about this year is the Eastern Tent Caterpillar, aka Malacosoma americanum. If you have been around any cherry or apple trees this spring, you have seen these. They are a remarkably social insect, emerging as tiny caterpillars in May, from a mass of eggs that overwintered glued to a branch on the host tree. The larvae congregate together and immediately start spinning a large three dimensional web in the crotch between two branches, that’s the tent. This web serves as home base for this community of caterpillars. As a native of north America, they especially like native cherry trees, but are also commonly seen in apple trees, though will occasionally end up on other species. The caterpillars emerge just as the new leaves are emerging on the host tree in the spring, perfectly timed to hatch just as their food source does. As they grow they continue to spin more and more silk, enlarging their tent as they themselves need more room. The tent provides a space to congregate when they are not feeding, and a temperature regulation mechanism. The tent is usually oriented to have maximum surface area towards the sun in the morning, so the caterpillars can warm up, become active and digest their food more efficiently. They go through a series of six instars, or caterpillar size classes, shedding their soft exoskeleton and expanding their body into a new larger skin. Generally they spend all of their time on their host tree, but at the end of their larval period, the group disbands, and individuals wander off, in search of good places to pupate on their own. When you see individuals wandering about over the landscape, this is what they are doing—looking for a good spot like a tree trunk or fence post on which to spin their cocoon and undergo the three week transformation into an adult.

One would think that these caterpillars would be sitting ducks for any and all predators—after all they live in big juicy groups in large easy to spot nests. As a result they have evolved several defensive mechanisms that keep them off the menu for most birds and parasitic insects, the organisms that would be their most likely predators. First they have a behavioral tic that causes them to thrash about wildly if threatened. This makes it especially hard for a parasitic wasp to successfully inject an egg into the caterpillar. Secondly, as is noted, they feed on cherry trees, and cherry tree tissue contains cyanide, so these caterpillars can sometimes release cyanide containing juices if threatened. Thirdly, and probably most obviously, the backs of these caterpillar are lined with hundreds of irritating hairs. Any animal that eats the caterpillar has to contend with the build up of these hairs in their throats and stomachs, the effects of which can range from uncomfortable to debilitating. The Black billed cuckoo is one local bird that has evolved the ability to eat these irritating caterpillars hair and all, the birds eat their fill and then cough up the lining of their stomach, growing a new one ready for the next meal of hairy tent caterpillars.

Seeing a tree, like the black cherry tree in my yard, totally stripped of leaves by hungry caterpillars is alarming, when all around lush green leaves are spilling out of twigs. The cherry tree looks dead, but trees are not that easy to kill, and it takes more than a denuding by tent caterpillars to do in a cherry tree. They, and many other broad leaf trees, have the ability to grow another set of leaves later in the summer, from buds that form in the spring (as opposed to the ones that over winter). Watch a tree attacked by tent caterpillars this summer, by August it should have sprouted new leaves, and not a tent caterpillar in sight. The caterpillars pupate in June and emerge as adults at the end of June or into July depending on location. The adult’s job, as is the job of so many adult lepidopterans, is simply to mate as soon as possible, lay eggs and die. Those eggs, once laid, wait many long months, until next spring, before the next round of tent caterpillars emerges, and we start all over again. 

References:

http://www.maine.gov/dacf/php/gotpests/bugs/factsheets2/tent-cater-wisc.pdf

https://entomology.ca.uky.edu/ef423

http://www.maine.gov/dacf/php/gotpests/bugs/tent-caterpillars.htm

http://web.cortland.edu/fitzgerald/Easterntent.htm

http://northernwoodlands.org/outside_story/article/of-cuckoos-and-caterpillars

http://www.nytimes.com/2016/05/15/nyregion/when-caterpillars-move-in-the-yellow-billed-cuckoo-feasts.html?login=email&_r=0

http://biologylabs.utah.edu/coley/ColeyPubs/2006Coley_cats_Oikos.pdf

https://extension.tennessee.edu/publications/Documents/W227.pdf

Hatching Chickens at Blue Hill Consolidated School

On May 28, 2016 the show aired an interview I did with some students at Blue Hill Consolidated School, about their classroom chicken hatching project.

We talked about what they learned from the experience.

Photo by Mary Tobey

You can listen to the show here: http://archives.weru.org/world-around-us/2016/05/world-around-us-52116/

Photosynthesis (the best thing ever)

Note: This program first aired on May 14, 2016.

Every day this time of year the world gets more and more green. Over night it seems like lawns spring up lushly, and the light green fuzz that covers the deciduous forest asserts itself more strongly every day. All of that green is a result of the growth of the photosynthetic structures of plants, structures that are replacing the ones that died last fall in preparation for the cold and dry winter season, or are growing anew from last year’s seeds. The primary photosynthetic structure for land plants is the leaf, a structure that has a lot of surface area relative to its volume. The surface area is important, as the leaf’s main job is to absorb solar radiation, so surface area equals absorption potential.

You all learned (I hope) in school that plants take carbon dioxide and water and sunlight and make sugar and oxygen gas*. The energy from the sunlight, electromagnetic radiation, gets transformed into chemical energy as stored in the bonds between the carbons and the hydrogens in the glucose molecule that is formed. Something we can’t store gets turned into something we can. It sounds quite simple, and if you look at them chemical equation for this reaction, it even looks quite simple. The reality though is far different, as my biology students this spring learned. Photosynthesis is amazing, and beautiful, and a process that virtually all life depends on, but it is not simple.

Nor should it be. Plants execute a very tricky procedure in fixing the carbon from carbon dioxide in to a glucose molecule. It isn’t easy to transform and store energy. Photosynthesis starts with light and that light energy gets transferred to electrons, electrons that are hanging out on chlorophyll molecules in the chloroplasts of plant leaves. Chlorophyll is a pigment that absorbs light, mostly red and blue light, because those wavelengths are especially good at activating chlorophyll’s electrons. Green light incidentally, is not good at all at exciting chlorophyll’s electrons, so it isn’t absorbed, it is reflected instead, which is why plants look green. Those electrons go through a series of steps in processes imaginatively called photosystems I and II. The light bumps them up to a high energy state, and over the course of photosystem I and II they bump back down, releasing that energy along the way. The end results of photosystems I and II are a whole bunch of temporary energy storage molecules called ATP, and a few electron acceptor molecules. ATP is adenosine triphosphate and is the go to molecule for temporary chemical energy in cells. The phosphate part is what makes it good for holding energy, but is also what makes it only able to do it temporarily, as the phosphate is very unstable. So ATP isn’t a viable long term storage solution, but cells make ATP to then use the energy stored in ATP to do other cellular business. Photosystems I and II are the light dependent parts of photosynthesis, and where the water (a reactant in the reaction) is used and the oxygen (a product of the reaction) gets formed.  The water gets split, and is where the electrons that get moved around ultimately come from, and the oxygen is a byproduct of splitting the water. Notice, no where in this part of photosynthesis have we talked about carbon or glucose. Carbon doesn’t have anything to do with this part.

The other nearly entirely separate part of photosynthesis is the light independent reaction—called the Calvin cycle. This is where all that ATP gets used, and those electron acceptor molecules from the photosystems give their electrons back up. Carbon dioxide gets incorporated into several different intermediate molecules with names like PGA and G3P and RuBP, and after 6 full turns of the Calvin cycle, you end up with enough carbons being fixed to make one glucose molecule. That requires a lot of electrons , and even more ATP. When you study the Calvin cycle you gain an appreciation for just how much energy really goes into making glucose, the energy molecule of life.  And note here, in the Calvin cycle, this is where the carbon comes into play. The carbon dioxide is a reactant in the chemical equation, and the glucose is the product linked to it. The water and oxygen gas that appear right next to the carbon and glucose on paper aren’t really connected to them at all in the plant cell, except for a few electrons.

And what that also means, if you think about it, is that the material of glucose, the carbon that makes up the main backbone of the glucose molecule comes only from the carbon dioxide the plant inhales from the atmosphere. That means that plants make food out of air. The material portion of that food, the actual atoms that make up the sugar we all eat, came out of thin air. And that is something I can’t get over, every time I think about how amazing plants are that is what I come back to, plants make food out of air (specifically the carbon dioxide gas) and oxygen out of water. I only wish I could make that much of a difference in the world.

*Here’s that reaction equation: 6 CO₂ + 6 H₂O → C₆H₁₂O₆ + 6 O₂

References:

Look at any college level biology book and  you will find the basic mechanics of photosynthesis. I used Freeman’s Biological Science 5^th ed in my class this past year https://www.pearsonhighered.com/product/Freeman-Biological-Science-5th-Edition/9780321743671.html

Antlers

Note: This program first aired on May 7, 2016.

Walking in the woods in late winter or early spring, if you are very lucky, you may happen upon antlers, either singly or in a pair, dropped from one of two local species of Cervidae or deer family, the white tailed deer or the moose. The sexually mature males of each of these species drop their antlers in the winter after the mating season has ended for the year, to be found by gnawing rodents and the occasional and lucky human.

These species produce a new set of antlers every year, in a feat that pushes the boundaries of mammalian bone growth. Antlers are in fact bone, but have two distinct phases of development that are as different from each other as life and death. The first phase of antler development is the growth phase. This starts in early spring on a male cervid. The initiation of antler production in temperate and high latitude cervids is determined by photoperiod, or day length. The length the day is increasing in the spring, and this signal is picked up through the eyes and transmitted to the pineal gland, which regulates melatonin production. Melatonin has a regulatory effect for sex hormone production, and is involved in both the shedding of the old antlers and the production of the new ones.

Antler development begins on the pedicles, bony knobs that develop on the skulls of young male deer and moose. The surface of all bones in the body is covered by a vascular tissue called the periosteum, and the pedicles have a specialized periosteum that is antlerogenic, meaning it gives rise to the antlers. This specialized tissue is similar to some embryonic tissue or stem cells, and can self differentiate into antler tissue in a similar way that certain embryonic cells turn into bone. In fact, this tissue can be transplanted to other places on the deer’s body, and will result in the growth of an antler to the transplant site (so yes, you could make a unicorn deer). The sex hormones or androgens like testosterone seem to have the biggest impact, female deer can be induced to grow antlers if their hormones are manipulated correctly, and in the wild the female deer that are occasionally seen with antlers are actually hermaphrodites (possessing female genitalia but undescended testicles).

When the antlers first begin to grow they are soft and spongy, almost like cartilage. The tissue is mainly water, and the dry fraction of the growing bone is mostly protein with a small amount of minerals like calcium and phosphorous. The antlers are at this stage living tissue, full of blood vessels and nerves, and covered by a thin hair covered skin like membrane called velvet. Antlers grow like onion roots—from the tip, and at an incredibly fast rate, upwards of ¼ inch a day. The frame of the growing antler is constructed first, and is then slowly filled in as the summer goes on. In late summer as the days begin to shorten noticeably, testosterone levels go up and the antlers begin to calcify. The blood vessels that have nourished the growing bone structure die back and the bone dies but stays attached to the pedicles. Once the bone dies, the velvet dies as well, and bucks and bull moose rub the thin skin off, revealing the smooth mineralized mature bony antler underneath. The antlers are used during the mating season as males fight other males for access to females, and females make themselves available to the males of their choosing. After the fall mating season is complete, a hormonally mediated abscission zone forms at the boundary between the pedicle and the antler, and the bone there erodes away to the point that the antler falls off.

The fast growth rate of antlers, combined with the requirement to regrow the antlers on a yearly basis create a huge nutritional and metabolic burden on these animals. It takes a large amount of mineral nutrients, and an even larger amount of calories. Growing a large set of antlers certainly signals age, as the antlers grow larger each year, and also access to the natural resources required to produce them, poor nutrition can show up as poorly developed antlers.

The ancestors of this antler bearing group of animals didn’t have antlers, in fact they had tusks—enlarged canine teeth that they apparently used for the same purposes as antlers are used today. And whether it is a saber toothed deer or an Irish elk with its 12 foot wide antlers, these show that sexual selection, the selective force that deals only with getting a mate, is what drives some of the most remarkable feats of evolution known.

References:

From the Journal of Anatomy regarding ossification of  antler tissue in deer: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1571559/

More on deer antlers from the Journal of Anatomy: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1571559/

About photoperiod, pineal gland and melatonin http://millar.bio.ed.ac.uk/andrewM/Jo%20Selwood%20site/photoperiodism.htm

On the Irish Elk http://www.iwla-rh.org/html/DGIF_articles/deer_antlers.html

http://extension.missouri.edu/p/G9486

http://www.iwla-rh.org/html/DGIF_articles/deer_antlers.html

http://extension.missouri.edu/p/G9486

Viruses

Note: This program first aired on April 9, 2016. 

I thought this week we’d spend a little time talking about viruses, because I’ve been spending some quality time this winter with them. I imagine many of you out there listening have too.

Viruses are the strange fruit of the biosphere, they don’t quite meet all of the typical criteria for being alive, yet are clearly alive none the less, in a way that things like rocks and other inanimate objects are not. In the technical jargon, viruses are obligate intracellular parasites, which decoded means that viruses require access to the cells of a host organism to complete their reproduction; the amount of time they can survive outside the host cell varies from virus to virus, from just minutes to years. Regardless of how long they can lie dormant in the outside world, they can’t do anything active until they are inside a host cell.

The reason for this is largely due to their anatomy (or lack there of). Viruses are not cells, they do not have a phospholipid cell membrane. All other living cells do have these membranes. Additionally viruses lack the molecular machinery needed to reproduce their genetic information. The only things they can call their own are their viral genetic molecules (a piece of DNA or RNA) surrounded by a protein coating called a capsid. What cells lack in anatomy they make up for in ingenuity, they are the MacGyvers of the natural world. They can take the machinery and structure of a living cell and use it for their own nefarious purposes. It’s perfect really—why bother to evolve the enzymes required to replicate DNA or the organelles needed to generate a cell membrane, when you can just appropriate the use of some one else’s? Viruses do just that, many of them construct an envelope out of material from a host cell’s membrane, which functions as an invisibility cloak and grants passage past a host’s immune cells. Viruses lack the enzymes with which to replicate their genetic material, and have solved this problem by evolving the mechanism by which they hijack the replication molecules of a host cell. That is why they have to get inside a cell to do their business.

Viruses are incredibly small and incredibly diverse. Part of this diversity stems from the fact that viruses also are incredibly specific. Each virus is adapted to hijack a specific kind of cell, and only that kind. Generalists are the exception not the rule the virosphere. Human evolution has been shaped by viruses throughout our history; influenza, hepatitis, small pox, dengue, rabies, measles, polio, now we have zika and ebola to add to the mix. Each of these viruses has a favorite cell type, influenza goes for respiratory epithelial cells, polio prefers motor neurons.  Hepatitis reproduces primarily in the liver, causing the inflammation we recognize as the disease, and more than 200 different types of viruses, including the rhinoviruses, infect the cells lining the inside of your nose and cause the common cold. Developing vaccines to combat rapidly evolving or newly discovered viruses informs much of our biomedical research.  

All that moving in and out of our cells has left a lasting imprint not just on human social history, but on our very genome as well. The more we learn about the human genome, the more we realize that viruses have been a part of our world for a very long time. Scientists estimate that as much as 8 percent of our DNA is viral in origin. When the virus moves into a cell to reproduce, sometimes things don’t quite go according to plan, and instead of hijacking the cell machinery to make viral DNA, the viral DNA gets incorporated into the cell nuclear material (the same kinds of mechanisms are used in genetic engineering today).  If that viral DNA ends up in the genome of a germline cell (one that is destined to become a gamete), it can be passed on to offspring, which apparently happened a lot. There is evidence emerging that this viral DNA is actually influencing the expression of some of our human genes. The deeper we look the more connected we are.

Stay well out there, wash your hands, cover your cough, stay home in bed if you are sick. Virus season will be over soon.

References:

University of California Berkley to the rescue again: http://www.ucmp.berkeley.edu/alllife/virus.html

The Journal Nature has a wonderful and well stocked educational website: http://www.nature.com/scitable/topicpage/cell-membranes-14052567

Viral DNA is in our DNA, and it can influence the sex of your kid: http://www.livescience.com/54247-ancient-viral-genes-may-determine-babys-sex.html

A list of human viral pathogens http://viralzone.expasy.org/all_by_species/678.html

It wouldn’t be a show about viruses without something from Carl Zimmer: http://phenomena.nationalgeographic.com/2015/02/01/our-inner-viruses-forty-million-years-in-the-making/