Monday, June 29, 2009

The Google at Delphi


We all ask the same questions.
Sometimes, we don't want to admit to them.
And so we ask Google.
Our personal Oracle.
... and we come to discover
- that, the world over, people are hunched over their laptops at home asking whether:

Tomatoes are fruit.
Russia is in Europe.
They should have an abortion.
They should divorce their wife.
They should file jointly.
They should join the army.
They should get bangs.
They are kinky.
They are diabetic.
They are depressed.
They are in an abusive relationship.
They should have an affair.
They should have a nap.

These are the things that Google thinks you want to ask.

From the most mundane,
to the most fundamental
- questions about your life, your body, your relationships.

And, in getting to know each other, perhaps we can come to know ourselves.


from A to Z
what we want to know:

About Ourselves...




Why we do things...




and, What We Should Do...




Some Links

And, if you think that Google's coders were on the funny stuff when they wrote up their Divining Code - just remember that that is wholly in the tradition of the best diviners of our history.

The Oracle at Delphi sat at the crossroads of geologic faults, on ethylene-leaking fissures, as she dopily directed the battle plans of the Greeks.


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Friday, June 26, 2009

Misplaced Macroalga

When that twister dropped Dorothy off in Oz she still had her house - and it afforded her protection from the withering elements of new places and faces. Not so for this luscious kelp. This is no Oz, it's a beach - and that is no good home for a seaweed.

The kelp's choice in settlement substrate cannot be faulted - it's a fair sized cobble by any measure. But the surf in the Gulf of Maine can be fierce and apparently even such a weighty foundation can be lifted and tumbled over the substrate and up onto Wells Beach.

Our discovery is a brown macroalgae, a type of heterokont (the nature of which is tied to its chloroplast - which we will explore anon). It is a large multicellular organism with a distinct undulating blade, a smooth stipe, and branching hold-fast. Specifically, this is Saccharina latissima, commonly called the Sugar Kelp, and historically (until 2006) known as Laminaria saccharina.



Sweet as a Peanut?

Sadly, I learned too late that this doomed macroalga that caught my fancy could have found an alternate demise in my digestive tract. It seems that this Sugar Kelp is a delicate treat that has long been appreciated for its stores of the sugar mannitol: "In the 19th Century L. saccharina was sold in the streets of Edinburgh, as a snack", which was "said to have a taste reminiscent of peanuts."

* ID of the kelp species in my photos is tentative *
***and insufficient to confirm edibility!
***
* do not eat any kelp based on the information in this blog!*

Consumption of kelp has been implicated in arsenic and heavy metal poisoning. The alginic acids of brown algae contain carboxylic acid groups that bind to bivalent metal ions and result in elevated concentrations of heavy metals in algal biomass (including plutonium). Because of the higher elevations of heavy metals these effects are likely to be more significant in densely populated coastal areas.



Chloroplasts with Baggage

The diet of a macroalga, just as of the elm, is carbon dioxide. In every cell is a chloroplast that photosynthesizes using the energy of light to split water and generate ATP and NADPH (the molecules that cells use to store energy).

But wait - a curiosity - the chloroplast, it has 4 membranes! The chloroplasts of green algae and land plants have only 2 membranes... There is a family history, a glimpse into the distance past, to be had in this observation.

Start your consideration with this interesting fact: every cell must have a membrane to keep its insides in and its outsides out. And yet, the chloroplasts inside the cells of the brown algae have 4 membranes around their insides!

Next, consider that many cells in the world (within the Bacteria & Archaea) have only one membrane for themselves and no other compartments within them that are bounded by discrete membranes.

What would happen if cell #1 were to swallow cell #2 by simply indenting its own membrane (imagine the equivalent of pushing your thumb into a balloon), taking cell #2 into that little dent, and then sealing the dent on the other side with its own membrane? The result is one cell inside another - but now wrapped in an additional cloak of membrane. The swallowed cell, cell #2, now has two membranes around it.

And so we are but half way to four...

Imagine then, that a third cell, cell #3, is to repeat the process, but with cell #2 now playing the part of the swallowed.

Counting in from the outside there are now 4 intracellular membranes to be accounted for (contained within the cell membrane of cell #3), these are:

1 - the cloaking membrane derived from cell #3, that was used to wrap around cell #2
2 -the cellular membrane of cell #2
3 - the cloaking membrane derived from cell #2 and used to wrap around cell #1
4 - the cell membrane of cell #1

This is the story of millions of years of evolution, competition, and survival. Endosymbiosis (endo: within, sym: together, biosis: life) theory explains the difference between major divisions of life and their divergence. There are lineages derived from primary, secondary, and even tertiary endosymbiosis events.

Even our own cells contain organelles derived from an endosymbiosis event that occurred in ancient evolutionary history. Your mitochondria, those organelles that you must get from your mother's egg (very rarely from your father's sperm), are derived from proteobacteria and they still have their own chromosomes and DNA sequences that group them closer to modern day proteobacteria than anything else.


So, as if carried by a twister from a foreign world and an ancient past, this big brown leathery kelp has washed up from the sea to remind me that there are powerful forces at work in the world around me. Forces that thrust a creature and a cobble from their moist home in the sea to a dry death under a hot sun. And forces that blend the lives and deaths of creatures great and small, to create ever new winning combinations.

Some Links

Clues to identification came from a SalemSound.org invasive species card with information about some native Gulf of Maine kelps.

On the historical uses, both culinary and military, of Laminaria saccharina

More kelp in the blogosphere at Jessica's Nature Blog on WordPress

Some Papers

(Bryan 1979 PTRSL) Bioaccumulation of Marine Pollutants

(Schwartz 2002 NEJM) Paternal inheritance of mitochondrial DNA


(Seki 1998 Journal of Colloid and Interface Science) Biosorption of Heavy Metal Ions to Brown Algae,Macrocystis pyrifera, Kjellmaniella crassiforia,andUndaria pinnatifida

Thursday, June 25, 2009

Aphid Juice Bar


I did not recognize her. She looked nothing like her mom, not her dad either. During our first introduction she barely looked up as she sucked her little victim dry, its legs a-flailing.

I guess it takes a while to learn manners but soon enough, she'll affix herself to the leaf and begin her metamorphosis - into a ladybug! But, as it turns out, apparently she won't leave behind her predatory predilections then either. And until that day when these larval ladybugs pupate they will remain here, popping-off aphid bonbons.




Aphids are insects that derive their nutriment from the contents of their host plant phloem. Phloem is the plant vascular tissue that transports sugars derived from photosynthesis from the leaves down through the plant and into the roots. Just near the phloem lies the xylem, which is full of water that is being drawn up from the root hairs and out through the leaves by evaporation through tiny openings in the leaf surface - the stomata.

While aphids are efficient harvesters of phloem fluids - sap - they face the dilemma that while sap is available in abundance it is not very rich in an important subset of molecules necessary for life: essential amino acids (these are just a set of building blocks that are all built exactly the same except that they differ from each other by one side chain; when strung together they form polymers called proteins and these are essential for the basic functioning of any cell). This is a similar problem as is faced by any organism that relies heavily on plant based material for its diet (like termites, shipworms, and vegetarians).

And, to every gardeners initial chagrin, the aphids have apparently managed to acquire the essential amino acids afterall - by outsourcing. While the aphids themselves do not have the tools (the enzymes, which are made of proteins!) encoded in their genes they do have a business partner that does: Buchnera aphidicola.

B. aphidicola is a bacteria that has been working with aphids for so long (millions of years) that it no longer has the genes necessary for it to survive on its own in the world. It doesn't matter because without B. aphidicola the aphid reproductive rates plummet and they can't acquire the necessary nutrients from their obligate sap diet... and so the aphid is obliged to maintain them. Every aphid, as she produces her batch of mini-me clones (by parthenogenesis: the development of unfertilized eggs into adult females), transfers bacterial cells to the egg (direct mother-child transfer of microbes is called vertical transmission).



So, aphids pierce the phloem and let the sap flow through them and, in part, out of them (this is the 'honeydew' collected by some ants ). And as the fluid passes through them they sequester the rarer nitrogen compounds and transfer them to their symbiont bacteria for processing. The bacteria have the genes to build essential amino acids needed by the aphid and produce them in response to varying concentrations of compounds in the sap consumed.

Thus it seems the aphid is set to suck every plant dry and proliferate with abandon. But, as I observed, with some horror I admit, there are predators that can search out these patches of aphids and winnow them down from armies to pitiful doomed patches.


How then, does a ladybug know where to put her larvae? Here you must begin to suspect that quiet character in the background - the plant. Not only is the plant offering enticements in the way of nectar in exchange for facilitating its sex (fuzzy pollinators carry pollen from the male floral organs - the stamens - of one plant to the the female floral organs - the carpels - of another plant) it is also sending off puffs of chemicals to alert insect predators to the presence of available prey. Herbivorous prey items causing cellular damage to plant surfaces by chewing on leaves or poking stylets into vascular tissue cause chemical reactions that produce volatile chemicals that can be detected by flying insects and used to localize prey. The plants are calling for help.

Some research has suggested that the plants can use these volatiles not only to facilitate insect recruitment but to induce the production of deterrent chemicals in neighboring trees that have receptors for the volatiles and respond to their binding by expressing genes involved in the pathways that make chemicals distasteful to potential herbivores, it has been called the phenomenon of 'The Talking Trees'.




Some Questions Answered and Some Questions for Later

Are there other neat Aphid Symbiont stories?

Yes, there are!

>>>The presence of another bacteria often associated with aphids, Regiella insecticola, is associated with higher resistance to a fungal insect pathogen. Not only does the presence of the bacteria protect the individual, but its presence in the dead remains of aphids (presumably sucked dry ladybug larvae) protects against fungal colonization and production of spores that might spread out to surrounding aphids. (Scarborough 2005 Science)

>>>Changes in Buchnera aphidicola's genome affect the heat tolerance of their host aphids! Two alleles (versions) of the gene for the promoter of a small heat shock protein (ibpA) are maintained in Buchnera populations. One version has a deletion and has lost its functionality as a heat shock promoter. When it is cooler and the aphids haven't experienced any thermal stress those aphids containing Buchnera with the deletion have higher reproductive rates, but in those populations that do experience a heat shock the survival of aphids containing Buchnera plummets. (Dunbar 2007 PLOS Biology)

Are there other neat higher-order interaction stories?

Of course!

>>>Grasses (Lolium perenne) with a fungal endosymbiont (Neotyphodium lolii) produce alkaloid mycotoxins. Ladybug larvae eating aphids that suck the alkaloid containing sap of these grasses take longer to develop into adults and produce fewer offspring ladybugs when they eventually do mature. (de Sassi Proceedings of the Royal Society B) Why aren't the aphids protected, you ask? Perhaps by adapting to tolerate these compounds these aphids have been able to outcompete other herbivores? Perhaps, given time, the plants will produce a novel compound that suddenly affects these aphids....


On what species of plant are the aphids & ladybugs in my pictures living?

>>> I don't know! Maybe someone can comment me the answer? Thank you!


What is the function of the cornicles - those two spines on the aphid posterior?

>>> This one is for later.

Are ladybug larvae distasteful to birds? They sure stand out on those leaves!

>>> And this one too.


Some Links

Antje Schulte's photo story of Ant herders and a "huge predator who's eating their 'cows'. "
... and her blog here on Blogspot, Four Feet and More

The kids story of how the ladybug became the Massachusetts state insect.


Some Papers

Nitrogen fixation in marine shipworms
(Carpenter 1975 Science)

Fungal plant endosymbionts alter life history and reproductive success of aphid predator
(de Sassi 2006 PRS-B)

Aphid thermal tolerance is governed by a point mutation in bacterial symbionts
(Dunbar 2007 PLOS Biology)

Behavioural side-effects of insecticide resistance in aphids increase their vulnerability to parasitoid attack
(Foster 2007 Animal Behaviour)

Aphid protected from pathogen by endosymbiont
(Scarborough 2005 Science)

A fragile metabolic network adapted for cooperation in the symbitic bacterium Buchnera aphidicola
(Thomas 2009 BMC Systems Biology)

Methyl salicylate, a soybean aphid-induced plant volatile attractive to the predator Coccinella septempunctata
(Zhu 2005 Journal of Chemical Ecology)

Wednesday, June 24, 2009

Turkey Path Bolete




On the second day I couldn't resist.

With an eye to the pedestrian traffic I knelt by the mulch and ran my finger under the cap... it was smooth - My first!

A fruiting body of the familiar form, though stout, but without gills - a Bolete.

I know I am not the only one who looks for these little treasures in their daily commute. Like encountering a calm Wildebeest in the T - it's surprising. After a good summer rain I feel like strapping on a pith helmet, snapping back a gin and tonic, and grabbing my rifle to go out and be a brave adventurer in the world of the wild that roars up all around East Cambridge.



Lucky for me all I need is diligent alveolar macrophages and I can leave behind the rifle - it wouldn't do me any good against the invisible storm of spores that will storm up my nares and into my lungs. Better have that gin and tonic though.

Luckier still, I'm no soil-bound microbe. That mulch is a battlefield. The tender hyphae that lie underground just below that silent Bolete are probably pouring out their own armament of digestive enzymes and antimicrobials.



Boletes are mycorrhizal partners of trees. The fruiting body we see is the reproductive structure produced by an expansive subterranean organism that spreads its hairlike hyphae through the soil and around (ecto) and sometimes into (endo) the cells of its partner trees. It's a business deal, there is an exchange of material between the two partners: the fungus is ensured a continuous supply of energy-rich carbon compounds and the tree increases its below ground surface area and thus its access to nutrients like phosphorous, nitrogen, and important trace metals.

Sometimes these mycorrhizal hyphae can connect two trees or plants of different species - allowing transfer of sugars from one tree to another! This is the plant equivalent of siphoning someone's gastank. Some plants have gone so far as to dispense with producing chlorophyll at all! These are called mycotrophs (myco: fungus, troph: nourishment)! There are at least 16 species of mycotrophs in Massachusetts - I'm crossing my fingers for an eventual Dalliance with one of them.

And, as if there weren't enough curiosities to capture my fascination, in my clumsy inspection of this unidentified orange Bolete I accidentally became privy to one of its secrets - exposing its bright yellow inner flesh to air causes it to rapidly turn vivid green and then slowly black! I carried home the young cap that fell off, it became quite dark in the warm palms of my hand, and at home I endeavored to record the color change - the result is in the video below.


These chromatic-shift-inducing oxidation reactions can be localized to different parts of the fruiting body and can be used as a tool in species identification, as can the compounds produced. In the case of our unidentified Bolete it appears, from inspection of the pictures rather than from empirical tests of disturbance, that both the stem and the cap are endowed with the substrates involved. What role do these compounds play in the ecology of our Bolete? The compounds produced by these reactions are not present until the fruiting body has experienced a mechanical disruption of its surface - by the attentions of an amateur myco-fan or the tiny claws of some hard-shelled insect touring about on it. Chemicals produced in this way are likely to be deterrents that dissuade further grazing by insects, but since insect sensitivities vary and not all parts of the fruiting body are reactive there is room for positive interactions that facilitate retention and direction of insects that are effective spore dispersers.

And, lest we run the danger of thinking that it is always the fungus that must arm itself against the culinary designs of others, know that Laccaria bicolor - another mycorrhizal partner fungus - is a career insect killer. "L. bicolor first paralyzes the springtails, quite likely with a toxin... then it extends nutrient-seeking filaments into the insects." But don't think the story ends there! Oh no, this is "Nature, red in tooth and claw" (or is it... in hypha and root hair?) because scientists on the trail of the labeled nitrogen originating from the springtails found it .... in the Eastern White Pine tree.

So, as you read this on your HP Mini, in the park, under the branches of that peaceful pine - remember that you too are tied into this web of sex, death, and survival - keep an eye on those trees.



Some links

"Insects & Mushrooms" chapter from Jean Henri-Fabre's book "The Life of the Fly"

The Boston Mycological Club

Mushroom Observer - you can be one too!

More about the Boletales from MushroomExpert.com

Some Books

Fungus-Insect Relationships by Quentin Wheeler and Meredith Blackwell

Mr. Bloomfield's Orchard


In the Company of Mushrooms: A Biologist's Tale


Updates!

The day after I first posted this all evidence of these Boletes was completely gone! Was it a gang of school kids or do they suddenly become tasty at some point in development?

In any case, there was suddenly a new patch of them nearby 3 days later. I collected a broken fruiting body to peak under it's cap - it's bright red (don't know if it is this color while still attached - I guess I need to add a little pocket mirror to my walking gear if I can't commit to snapping little mushroom caps). Slicing through it you can easily the thick meaty cap and thin layer of tubes that form the pores.

I can't narrow this down to species with confidence but if I had to pick one right now I'd go with: Boletus subvelutipes. If you see the definitive characteristics that can rule this out or in then please enlighten me with a comment - Thank you!