Saturday, September 17, 2016

Standing with Standing Rock

Note: This program first aired September 17, 2016.

Our bodies are over 60% percent water. We can only live a matter of days without water. Water covers 71% of the surface of this planet.

It should be no surprise that people attempting to live according to traditional, earth centered, non western value systems hold water to be sacred. Call them Indians, native peoples, first nation, aboriginal, tribal, many of these communities still hold to ideals that see water as the sacred blood of the earth, as the first medicine. And so it should be—all life depends on access to clean water.

Water is a polar molecule, making it a wonderful solvent, readily dissolving any substance that has an atomic electrical charge. Liquid water is fluid, and can easily transport any other fluid substance in it, even if that substance is non polar, having no electrical charge, and can’t dissolve in the water. Even if that substance is crude oil.

Crude oil is made up of a mixture of many different fractions of hydrocarbons, ranging from the heavy end with things like asphalt and paraffin, to the light end with things like the methane and propane, some of the constituents of natural gas. Crude oil contains other substances, related to the hydrocarbons we burn in our cars and furnaces, things you might have experimented with in organic chemistry class, like the aromatics benzene, toluene, and xylene. And even though the aromatics come from crude oil, something we typically think of as insoluble in water, these light fractions are soluble in water. They also have a low atomic weight, so they evaporate into the air quite readily as well. And worst of all, they are carcinogenic.

This is the kind of thing you think about when you learn that an oil transporting pipeline is about to be built through a river that is your source of drinking water. You think about the pipeline leaking, and the heavy fraction of the crude oil, being denser than freshwater, sinking to the bottom of the river, virtually impossible to clean up, and the lighter more soluble fractions traveling with the water to be taken up by municipal water systems down stream. You think about how common it is for pipelines to break, and in isolated rural areas how long it takes for people to notice.

These are the things I was thinking about as I stood in the rain attending a solidarity event for the Standing Rock Sioux tribe in North Dakota. The Standing Rock tribe has been protesting the fast track approval of the Dakota Access pipeline, its permitted path through off reservation sacred sites, and its crossing of the Missouri River, the drinking water source for the tribe and rural farmers and ranchers downstream. Native tribes from all over north America have been converging on the protest encampment at the Sioux reservation in a show of solidarity, and events like the one I attended, organized by Wabenaki leaders here in Maine, are popping up nationwide. You don’t have to be Native American to understand that water is sacred, though watching the Wabenaki prayer ceremonies made me realize that I lost the language of sacred connection many generations ago. Nor do you have to be a scientist to understand the linkage of water pollution and illness, and unfortunately I speak that language all too fluently.

Water is not unique in the universe, in fact the only reason we have it hear on Earth is that it came here the same way all the other matter on Earth did, as an aggregation of space dust and rocks. But water is what makes this planet unique, and what makes life possible on this third rock from the sun. The Standing Rock Sioux know it, and so do you.

References:






Saturday, September 3, 2016

Fungus Among Us Part 3

Note: This program first aired on September 3, 2016.

Last week we talked about fungus, and they ways it makes a living in this world. The mushrooms we see in the forest are just the tip of the fungal iceberg, the vast majority of fungal biomass in the forest is subterranean. These are the bundles of fungal fiber called mycelium, and if the mushroom’s job is reproduction of the fungus, the mycelium’s job is to nourish it.

There are three ways that fungi can get food from the environment; they can parasitize another fungus*, they can decay organic matter, or it can form a relationship with a plant in an “I’ll scratch your back if you scratch mine” symbiosis called mutalism. We covered parasitism and saprotrophism earlier, leaving mutalism for today.

It turns out that many of those mushrooms you see erupting from the forest floor are from fungal biomass that is in direct relationship with the trees that make up that forest. The individual hyphal filaments that make up the mycelium, or all that fungal biomass beneath the surface of the soil, get up close and personal with the tiny root hairs, or rootlets from the tree and form what is called a mycorrhizal relationship, “myco” referring to fungus, and “rrhizal” referring to roots. Trees and their fungus typically form what is called an ectomycorrhizal relationship—meaning the fungus only just barely infiltrates the upper layers of the rootlet tissue, squeezing in between the cells of the root outer cortex, forming a sheath.  The conjoining of the tree roots with the fungal mycelium effectively expands the tree’s root system by orders of magnitude, and even directly connects it to other trees of its species if the mycelium forms an ectomycorrhizal relationship with more than one individual. 

Typically a fungal species has only one suitable tree species it can pair with, though often trees can have many different fungal partners. Many of the trees I see daily are obligated to form relationships with fungal partners; they cannot grow without the assistance of the fungus. Those groups include pines, oak, beech and spruce. Other tree species are facultative, and can grow without a fungal partner but grow better with one. Examples include maples, juniper, willows and elms.

I said this is an I’ll scratch your back if you scratch mine kind of situation, both partners benefit from this trans species contact. As I noted, the tree gets a major extension of its root system, gaining what one source called “hundreds of thousands of kilometers’ of individual hyphae, collecting water and inorganic nutrients from the soil. Essential nutrients like phosphorous and nitrogen are limited in the terrestrial environment, and the fungus is able to aggregate these and make them more available to the tree than they would be otherwise. The fungus also is able to collect water from the soil, though there can also be instances when the plant gives moisture to the fungus as well. And in some cases the fungus produces plant growth hormones, stimulating tree root growth. What we know for sure the fungus gets out of the relationship is carbon, in the form of sugar. 10 to 15 % of the carbon fixed by the tree gets channeled to the mycorrhizal partner. Both players are able to trade something they are good at getting from the environment for something they need, to the benefit of everyone.

This kind of relationship isn’t limited to trees and mushrooms. Many herbaceous plants and agricultural crops form mycorrhizal relationships as well, relationships characterized by even deeper infiltration of the fungus into the plant tissue. And in a totally different part of the world, coral reefs, we see the mutualistic symbiosis of coral polyps and photosynthetic plankton, swapping carbon in the form of sugar in return for inorganic nutrients. In a great example of convergent evolution, many realms of life species have evolved to swap resources in order to increase their competitive fitness. That is the cool thing about evolution, when something works, it keeps popping up independently on the tree of life.

So many of those mushrooms you see in the woods this fall, are part of a legacy of remarkable biological cooperation.

* or plants or even animals!
 
References:









Saturday, August 27, 2016

Fungus Among Us Part 2

Note: This program first aired on August 27, 2016.

Last week we looked at mushrooms, and talked about how they are the reproductive structures of certain kinds of fungus. Mushrooms are simply the above ground spore making structures of an otherwise underground organism, one made of miles of bundles of filaments called mycelium. If the mushroom’s job is to make spores, then what is the job of the mycelium, all the fungal biomass we don’t see? Just like in other realms of life, different life stages have different jobs for the organism, and the mycelial job is feeding. Fungus are heterotrophs like you and I, they rely on food sources outside of their bodies (unlike plants—which create their own carbohydrates). As heterotrophs we eat food, ingesting the complex material which is then broken down into smaller more accessible biological molecules and absorbed directly into our bodies in our guts. Fungus don’t have mouths or guts, but they still digest food using the same process. They excrete the digestive enzymes onto the material they are eating, and once that material is broken down into smaller molecules, it can be absorbed by the fungal filament. For example neither humans nor fungus can absorb cellulose, one of the primary molecules of wood, and much plant material. When humans eat cellulose, we call it insoluble fiber, and though it has health benefits, we don’t digest it and don’t get any nutrition from it. When  the mycelium of certain fungi encounter cellulose, they are able to produce enzymes that break the cellulose down into the individual molecules of glucose it is made from. Fungi can then absorb the glucose, gaining nutrition from the cellulose. The ability to digest cellulose and lignin, the other primary constituent of wood, is one of fungi’s super powers.

There are lots of fungi out there, but we’ve been trying to limit our discussion to mushrooms—so do all mushrooms eat wood? No, in fact there are three different modes of nutrition for the mushrooms that we see out in the woods. The first, and least common, so we’ll get it out of the way, is parasitism. There are fungi that parasitize other fungi! Parasitism is a symbiosis that is typically thought to benefit one partner and have a negative impact on the other. The parasitic fungus benefits by stealing nutrition from the parasitized fungus. In our region the most common parasitic fungus you will see is lobster mushroom, which is a fungus that doesn’t make its own mushroom, but hijacks the mushroom of other species. I’ve talked about Lobster mushroom before on the show.

The second mode of nutrition for mushrooms is to be a decomposer or saprotroph. This is the default or ancestral mode of fungal nutrition, the ability to excrete digestive enzymes into the environment and break down complex organic molecules into simple (and thus absorbable) organic molecules is the hall mark of this kingdom of life. If it weren’t for fungi (and many bacteria as well), we would be overwhelmed with dead organic matter, and in fact life would stop because it would run out of raw materials. Fungi are the recyclers of the biological world, they process millions of tons of organic waste a year, turning dead material back into building blocks like carbon dioxide and individual mineral nutrients that can be used again by plants to make more food. The balance between the carbon taken out of the atmosphere by plants and the carbon put back into the atmosphere by animals, bacteria and fungi is what keeps climate relatively stable*, at least until plate tectonics changes atmospheric circulation** and weather patterns change, and throw that balance out of whack, driving extinction and more importantly evolution. Heady stuff for those little mushrooms along the trail.

I said there are three modes of nutrition for fungi, but we are out of time for today, so we will look at the third, and if you are a plant, most interesting mode, next week. 

*Before the geologists get mad at me--Yes, the rock cycle plays a really important part in this as well--carbon going into and coming out of geological sinks like limestone...


**And influences the rock cycle by exposing or burying carboniferous rocks...

 


References:

  
All the same ones as last week plus:


Still one of my favorite theories out there, even if it is now being challenged: www.scientificamerican.com/article/mushroom-evolution-breaks-down-lignin-slows-coal-formation/



Saturday, August 20, 2016

Fungus Among Us


Note: This program first aired on August 20, 2016.

There’s fungus among us. Though it has been a dry summer, in the past few weeks, right after each heavy rain, on the trails I run I see mushrooms pushing their way up out of the forest floor. Russulas and Lactariuses, coral fungus and boletes, an occasional amanita and delicious chanterelles. And those are just the groups I can identify with relative ease.

Mushrooms are the reproductive structures of certain kinds of fungus, ascomycetes and basidiomycetes. There are many other kinds of fungus out there as well, but they don’t make mushrooms (think mold and yeast and a bunch of stuff that is essentially invisible to human eyes).  As the reproductive structures of ascomyctes and basidiomycetes, they emerge when environmental conditions favor fungal growth. The timing of these appearances gives a clue as to what those favorable conditions are. It has been a dry summer, dry enough that all of the organic matter that makes up the upper layers of the forest floor is dry, and we’ve experienced a few small forest fires. Scary stuff in our dense, low fire frequency eastern forest.  The mushrooms we see emerge after damp weather are the result of the action of billions of fungal filaments below ground in the soil. These filaments, called mycelium make up the bulk of fungal biomass, at least in terms of the mushrooms we see in the forest. The mushrooms are truly only the tip of the ice berg.

Mycelium are made up of even smaller individual filaments called hyphae, and grow through the soil in the forest feeding on organic matter. Like the fine hair like roots of plants, these microscopic fillaments don’t do well when the soil is very dry, their movement and metabolism are aided by the water that makes the soil damp. Hence, a nice flush of rain  that wets the forest soil results in a boom of mycelial activity, and it is when compatible mycelium meet up underground that a mushroom results. Rapid increases in mycelium increases the chance of these meetings, hence mushrooms appearing overnight after wet weather. The mushroom’s only job is to create spores, which can result from sexual reproduction between those two compatible mycelia, and are a dispersal mechanism for fungus. Tiny and airborn, spores can travel great distances on air currents, and if they land in the right spot, can germinate and form a new hyphal strand. If that strand of hyphae finds what it needs it continues to grow and becomes multistranded mycelium. If it runs into another mycelium from the same species, and they are compatible mating types, they will merge and share their genetic information, and build a mushroom from this conjoined mycelium. In special cells in the mushroom (typically on the gills underneath the cap) meiosis will occur and the spores that are formed will contain a mix of genetic information unique from either parent.

If that is the job of the mushroom, what is the job of all that mycelium in the forest soil? We’ll answer that question next week.


References:

Mostly books this time around: 

David Arora, Mushrooms Demystified

George Barron, Mushrooms of Northeast North America

Lawrence Millman, Fascinating Fungi of New England

Elizabeth Noore-Landecker, Fundamentals of the Fungi, 4th ed.

James, Timothy (2007). "Analysis of mating type locus organization and synteny in mushroom fungi: Beyond model species". In J. Heitman; J. W. Kronstad; J. W. Taylor; L. A. Casselton. Sex in Fungi: Molecular Determination and Evolutionary Implications. Washington DC: ASM Press. pp. 317–331.

Saturday, July 30, 2016

Going Gray

Note: This program first aired on July 30, 2016.

This week’s show originated as a question from my nephew. He was wondering why hair turns gray. I have thought of that myself, as I sport a head full of white hairs, which started losing color far ahead of the curve early in my 20s. And the answer to the question is of course, complicated and partially unknown.

To start we have to look at where hair, and fur color comes from. Hair is made of several layers of a structural protein called keratin (the same thing your finger nails are made of). It grows from collection of cells, which some sources refer to as a mini-organ, called a follicle. The skin of most mammals is studded with hair follicles, it is a defining characteristic of the group. The color of hair is controlled by cells around the follicle called melanocytes, who’s job unsurprisingly is to generate a pigment called melanin. Melanin gives hair its color, by being injected into the filamentous protein we call hair, as it grows. The variety of hair colors we see in mammalian  animals is determined by the mix and balance of different types of melanins, broadly speaking, eumelanins are black and brown, and phaeomelanins are lighter, reds and yellows.

Human hair has three develpmental stages: anagen or growth phase, which lasts for years,  catagen or transitional phase, as the hair transitions from active growth to being shed, and telogen, a quiescent phase that ends with the hair fiber being shed. While we look mainly at what is going on with the hair itself, these phases represent dramatic differences in the functioning of the hair follicle. As the hair is growing in anagen, the melanocytes are pumping melanin into the hair fiber. When the follicle enters catagen, the first thing that happens is the melanocytes stop melanin production and undergo apoptosis, which is programmed cell death. Individual melanocytes then only get to produce melanin for a single strand of hair. Hair pigmentation shuts off in the transitional phase of hair growth, and if it doesn’t turn back on when the cycle starts over, the resulting hair that grows will be colorless, or white.

Now I said that not only does the melanocyte stop producing pigment, it actually dies, and in order for the next hair that grows to have pigment a new melanocyte has to form. And that is where the root of all this going gray as a normal part of aging happens. The new melanocytes arise from stem cells, melanocyte stem cells, which can mature into a pigment producing cell when needed. These stem cells continually divide and create more stem cells, so there is always a supply on hand when the hair follicle returns to the anagen active growth phase. The current thinking is that mammals go gray as they age because stem cells start to lose their integrity the older they are. The older you are the more damaged the cells in the melanocyte stem cell reservoir are, so the chances of a functional stem cell being able to mature into a pigment producing cell go down. The more times cells divide, the more chances there are for errors in transcription, the copying of genetic information. That is why age impacts cellular health, in general, the older a cell is, the more times it has divided. Cells only have so many times they can divide, before the telomere mechanisms inhibit further cell division and the cell effectively is put out to pasture. When we get very old, we don’t have any melanocyte stem cells left. Normal aging (which really means the changing of our cellular DNA, or shortening of our telomeres, that occurs during cell division) results in this decrease in stem cells, but cellular stress in the form of mutagens that damage DNA can as well, things like Xrays and UV light.

Many questions remain about this going gray business. The diversity of pattens of human graying is thought to be genetic but we don’t know why, and are there implications for other stem cells in the body, do all your stem cells function the same way? Why do dogs go gray around their muzzles but not other parts of their bodies? Why do some mammals not go gray at all? Many questions, fewer answers, but that is actually a good thing. If we had all the answers there would be nothing left to do. So please, keep your questions coming.
 
References:





Saturday, July 23, 2016

Caterpillars, Food Webs and Doug Tallamy


Note: This program first aired July 23, 2016.

Ecosystems are like salad bars, you fill your plate with lots of leafy greens and then sprinkle lesser amounts of more concentrated food items on top (nuts, olives, bacon bits). Ecosystems have a similar food or trophic structure, at the bottom are the primary producers, the plants and other photosynthetic organisms, as you move up at each level there are fewer and fewer non plant individuals ( herbivores, omnivores and carnivores).

Land plants are the primary producers of terrestrial ecosystems, doing the work of capturing the sun’s energy on dry ground, they are the lettuce on the salad bar of the forest. And it turns out there are bacon bits here in the forest as well, in the form of caterpillars. As herbivores these organisms are able to transfer the energy that plants capture from the sun to higher trophic levels in the forest food web. That is what I learned listening to a talk from University of Delaware entomologist Doug Tallamy when he came to Maine to speak earlier this summer.

Tallamy’s work looks at the relationship between the primary producers, insects and the upper trophic levels, mainly birds. And what he has discovered has profound implications for the way we manage the landscapes directly under our control. It turns out that if you want birds around, particularly migratory song birds, you need insects, specifically caterpillars. These birds migrate thousands of miles to northern North America to breed, because of the plentiful food sources here. 

Caterpillars, which are made up of fat and protein, are very nutrient dense and make up a huge proportion of that food for many of these birds. Tallamy recalled watching a pair of birds feeding their young, calculating that the nest of young birds were fed hundreds of caterpillars a day, thousands over the two week period they spent in the nest. And here is where it gets interesting, because if you want caterpillars around, caterpillars being the larval stage of lepidoptreans, the butterflies and moths, you need plants, because caterpillars eat plants.

But not just any plants, caterpillars generally eat specific plants, plants they have a long evolutionary relationships with. Plants do everything they can to not be eaten, evolving elaborate chemical warfare against hungry insects. Insects do everything they can to evolve physiologic means of evading the plant defenses, in an ever escalating evolutionary game, the relationship between the eater and the “eat-ee” gets more and more specific. We have all heard about the monarch butterfly and its host plant common milkweed, but many lepidopterans have this level of specificity with their target food source. Others are less specific and play the field, having relationships with plants in more than one genus. And plants are not monogamous, as the “prey species” in this relationship, they have many different insects trying to eat them, and can play host to tens to hundreds of different kinds of caterpillars. 

What Tallamy and his lab have quantified is the number of different lepidopteran species (in the form of the caterpillars—which are the stage in which these insects do the majority of their primary production energy transfer) various genera of plants support. The results are astonishing. In my area, native tree genera like willow (Salix) and oak (Quercus) can support between 300 and 350 different types of caterpillars!  Other native tree genera support nearly that many. The corallary to this is that nonnative trees and shrubs, frequently planted as part of “normal” landscaping, support virtually no caterpillars, because no native insects have evolved ways to evade these plants’ defenses. None. Insects are the animal that is responsible for transferring the majority of primary productivity from plants to the rest of the terrestrial food web. Birds, reptiles, amphibians, spiders, and rodents all rely on caterpillars as a food source. So if you don’t have plants that support insects, you don’t have anything else in the food web either.  Biodiversity is our life support system, and what I learned from Doug Tallamy is that it starts from the ground up, in an elegant and fundamental relationship between those that eat and those that are eaten.

References:

Doug Tallamy’s book on native plant landscaping in the suburban environment: http://www.bringingnaturehome.net/

Download the data from Doug Tallamy’s studies here: http://udel.edu/~dtallamy/host/

One of Doug’s popular science articles (slightly dated) but with interesting stats: https://www.americanforests.org/magazine/article/backyard-biodiversity/

 Our local native plant advocacy group, Wild Seed Project, has lists of appropriate native plants (to Maine) for different environmental conditions: http://wildseedproject.net/using-natives-in-the-landscape-a-comprehensive-plant-list/

The native plant finder at the National Wildlife Federation site: http://www.nwf.org/nativeplants-beta/About (its a beta version--still a little buggy, no pun intended, for example, when I searched my zip code some high scoring trees did not appear, but when I searched them individually they showed up in my zip code…)

Want to eat some bugs yourself? Here’s a list of internet resources: https://edibug.wordpress.com/where-to-get-bugs/


Saturday, July 9, 2016

Bumble Bees Part 2: Life History

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

A worker bee, temporarily interrupted from foraging.
I’ve been spending a lot of time lately thinking about bumble bees, watching which flowering plants they visit and which they don’t, looking at them trying to discern one species from the next, and learning when they like to fly and when they don’t. I’ve volunteered to survey bumble bees for the Maine Bumble Bee Atlas project and the learning curve has been steep. The entomologists who direct the project are evidence of the fact that the rabbit hole you can go down when you open your eyes and start to see the insect world all around you has no bottom. Arthropods are the most successful phylum of animals on the planet, and there is no shortage of wonder to be pursued in their diversity. For me it seems bumble bees may just be the beginning.

One place to start is with their life history. I’ve kept honey bees on and off for a few years and thought that bumble bees worked the same way, albeit on a smaller scale. I was wrong. Bumble bees, like honey bees are true eusocial insects, meaning they live in colonies that have castes of workers with behavioral specialization, communal care of brood, overlapping generations, and reproduction limited to a few specific individuals (often a single queen and specially raised males). Bumble bees live this eusocial life in a way very different from the European honey bees many of us bee keepers are familiar with.

Bumble bee colonies over winter as queens, the large, mated reproductively active females that are raised and mated the fall before. When the weather turns cool these individuals search out an overwintering spot, in leaf litter at the edge of the forest. These are well fed bees, having been raised on the bountiful nectar and pollen from the late season golden rods and asters. These queens emerge in the spring and are the stock from which the new colonies form. The only bumble bees that survive the winter are the queens, colonies do not over winter, workers do not over winter. Only single bees do, prepared to start a brand new colony of their own the next year.

So those first really big bees you see flying in the spring are the over wintered queens. They emerge and look for a spot in which to nest, a spot that will house their  modest colonies for the summer. Old rodent burrows are especially good spots, as apparently are the seat cushions of the old abandoned cars in the woods you see frequently in Maine as early 20th century farmsteads are reclaimed by forest. Once a queen finds a good nest cavity, she lays the first of her eggs (remember she mated the fall before, so she has all the sperm she needs to lay fertilized eggs), She incubates them herself by generating heat shivering, and feeds the larva nectar and pollen when they hatch. One bee foraging to feed several hungry babies though does not quite cut it, so the first round of bees that are produced by the queen are quite small. These are the first worker bees you will see in the spring, they look stunted, and quite literally they are—nutritionally they got enough to survive but not really thrive. Once there are more workers in the colony, the subsequent larvae get fed better, and the resulting bees are bigger. This pattern continues throughout the summer, the queen lays eggs, staying in the nest once there are enough worker bees to do the foraging, the workers out in the field collecting the nectar and pollen needed to sustain the hive. Workers live around 25 days, and a typical hive has between 50-100 bees when up and running during the summer.

At the end of the summer, two different kinds of bees get produced by the hive. The first are males—these come from unfertilized eggs. They have one purpose only, that next year’s queens can get fertilized before hibernating. The others are the new queens. The last batch of worker bee eggs that are laid become the queens for next year. Theoretically the hive is at its highest capacity at the end of the summer, the land is covered with golden rod and asters and thus there is plenty of forage, and many workers able to feed these up and coming queens. Once these very large nascent queens emerge, they mate with the males which also unsurprisingly emerge at the same time. As fall progresses on, the old queen, the founder of the colony, dies. Her daughters, the worker bees, all die. Her sons, the males, all die. The only bumble bees that don’t die are the new queens, well fed and stocked with sperm, ready to over winter in the leaf litter until the process starts over again in the spring.

It’s a pretty remarkable process, and something to consider when you clean up your yard in the fall. Do the bumble bees a favor, leave those leaves where they are until the spring, in doing so you create safe space for the potential bumble bees of the future.

References: