Something More Useful, For Once.

SOURCE: http://www.physorg.com/news144592569.html

Without glial cells, animals lose their senses

Sensory neurons have always put on a good show. But now, it turns out, they'll be sharing the credit. In groundbreaking research to appear in the October 31 issue of Science, Rockefeller University scientists show that while neurons play the lead role in detecting sensory information, a second type of cell, the glial cell, pulls the strings behind the scenes. The findings, point to a mechanism that may explain not only how glia are required for bringing sensory information into the brain but also how glia may influence connections between neurons deep within in it.


"This is a convincing demonstration that glia play an essential role in the function of the nervous system," says Shai Shaham, head of the Laboratory of Developmental Genetics. "Without sensory neurons, animals can't sense their environment and react to it. What we found is that glia are required for the activity of these neurons and that glia are required to establish the quality of the animal's response to its environment."

In their work, Shaham, graduate student Taulant Bacaj, and postdoctoral fellow Maya Tevlin worked with a structure called the amphid, a sensory organ in the C. elegans nervous system that contains glia and neurons. Of the organ's 12 neurons, four are completely ensheathed by glia and eight are partially ensheathed, with sensory endings exposed to the outside environment (via the worm's nose). To see what glia do for these neurons, Bacaj removed the glia and observed the effect on the neurons' shape, their ability to generate behavior when exposed to odors and temperatures, and their ability to absorb certain dyes.

The results were striking. The absence of glia affected at least one of these three properties in each of the neurons, suggesting that glia not only regulate all of these properties but that they specifically regulate them in different neurons. In the absence of glia, for example, the sensory endings of the ensheathed neurons lost their intricate branch-like structure, shriveling into nubs. However, the partially ensheathed neurons retained their normal shape, despite their inability to respond to stimuli in their environment..

"Instead of finding their perfect temperature, the worms kept crawling toward warmer and warmer regions," says Bacaj. "Also, they didn't avoid odors they didn't like and weren't drawn to odors that they did like, suggesting that the neurons could not coordinate an appropriate behavioral response."

"It's a new layer of complexity that was never described before," says Shaham.

To get a molecular handle on how glia regulate the functions of neurons, Shaham, Tevlin and Bacaj looked at which proteins are expressed more in glial cells than in any other cell in C. elegans. They found that one of these proteins, called FIG-1, was exclusively expressed in glia surrounding the amphid sensory organ (and its sister organ in the tail). When the glia secreted this protein, neurons in the sensory organ could sense the environment; without it, the neurons had difficulties in picking up specific sensory cues.

Because FIG-1 resembles a human protein called thrombospondin, which is secreted by glia in vertabrates, the results suggest that interactions between neurons and glia in C. elegans may be similar to those in humans. They also suggest that glia-neuron interactions at sensory organs may provide insight into glia-neuron interactions at synapses, connection sites between neurons deep within the brain.

"The FIG-1 protein is similar to a glial protein found at vertebrate synapses," says Shaham. "So we think there might be a connection between glial proteins in C. elegans and those in vertebrates. The difference is that at synapses, you have a neuron receiving information from another neuron, whereas at sensory organs, a neuron is receiving information from the outside world."

Source: Rockefeller University

Quotable Quotes - Part the Second.

Posting from BioSoc session here. Kekeke. XP

Huimin: Brown algae is... uh... brown.

PuHwai: How about lab session...
Huimin: Huh? Lap session!? You want them to run arh!?

Daniel: What you want the J1s to do when they come in next year?
Huimin: Elope! Elope!

Huimin: Squueze the juice out!

Huimin: What you wanna do?
Joshua: Lab sessions.
Huimin: Do what there?
Joshua: Run.

Huimin: And laugh more, man. *smiles widely* =)

Joshua: Lol!
PuHwai: Lol!
Joshua: Lol!
PuHwai: Lol!

(At 5:16 pm)
Lim Yi Sheng: ...Sorry, am I late?

Daniel: ... and the following week after CNY week...
Lim Yi Sheng: Huh? CMI week!?

Daniel: *Points to me typing here* Aiyah! Stop it lah! *growls*

Lim Yi Sheng: Make them feel very guilty...
Daniel: Ok la, you do that, make them feel guilty, mission for Lim Yi Sheng
Lim Yi Sheng: Can I target the opposite sex only?

Huimin: Basically, it won't be like normal guidebook. Like plant, then species...
Lim Yi Sheng: Then what? Species, then plant?

Daniel: Eh, don't abuse the blog leh!
*me types it in*
Daniel: Ehhhhhh! =(

Me: Sir, say something funny leh!
Mr. Lan: Dowan.

RSBS ftw!


EDIT:

Just one more from today (meaning October 28th).

Huimin: So what do you find around the mouth of a jellyfish?
Lawrence: Jelly.

Quotable Quotes - Part 1

Hellos people! If you all don't know, I'm Jinghua here. Yupyup. From time to time I'll be posting up little bits of interesting conversations here. Ehehe.

(And, yes, this has the approval of Our Dear Leader The Great Daniel Chew)

And so, to begin, from our last meeting,

(After Readon leaves)
Huimin: You know, I expected Readon to be... abit... darker?

(On Pu Hwai and his old classmates, on Pu Hwai's current classmate joining BioSoc, and countless other occasions...)
Huimin: Kyaaaaaaahhhh! Soooooo cuuuuuuute~!

Daniel: So Jinghua? What do you want to do for the NLB thing? Mug?
Me: Nope. Isn't that *your* hobby?

Me: But Daniel Chew has absolute and comparative advantage in everything!
Pu Hwai: So we let Daniel Chew produce everything?

Daniel: But if we put lightsticks in the exhibition in the library, someone has to go there and replace it everyday.
Me: Not just everyday. Like 2-3 times a day. Who's going to do it?
Shi Ting: *shrinks away*
Geraldine: Don't you live near there, Shi Ting?
(Everybody turns to look at Shi Ting)
Shi Ting: Why me....

(Just before leaving)
Shi Ting: I don't want to go there to change lightsticks everyday!

(On secondary schools...)
Huimin: Mixed school rocks!
Daniel: Guys' school rocks!
Geraldine: Girls' school rocks!
Me: ...

Huimin: Why don't we get a large tub of water and buy those cheap cheap long gau hu (垄沟鱼, fish found in drains) to...
Daniel: Huh? Yong tau fu!?

Huimin: Your classmate is joining BioSoc? What does she look like? How tall is she? Is she short?
Daniel: Uhh... About Geraldine's height. Is that short?
Huimin: ... Then how big is she?
Daniel: Uhh... Abit fatter than Geraldine. Is that big?
Huimin: Then is she dark?
Daniel: Uhh... About the same as Geraldine. Is that dark?
Huimin: ...
Geraldine: ...
Me: ...

(After learning Daniel was in volleyball)
Huimin: Omigod! You're in volleyball? Teach me!
(Every 5 minutes after that)
Huimin: Heyy! Teach me volleyball leh!

Hmm. That's it for now, then. Will post more once I manage to hear more stuff. XD

Melamine

The recent food scare involving the addition of melamine to milk has really affected each one of us greatly, so I thought I would post some facts related to melamine so that everyone can have a broader picture of what's happening!

----------------

Picture showing the resonant forms of melamine

Melamine is an organic base chemical most commonly found in the form of white crystals rich in nitrogen, with a 1,3,5-triazine skeleton. It is an aromatic compound consisting of carbon, nitrogen and hydrogen, and is a trimer of cyanamide (CN₂H₂), containing 66% nitrogen by mass. It is also a metabolite of cyromazine, a pesticide, and is formed through dealkylation of ingested cyromazine.

Melamine is most often produced using urea in an industrial process. First, urea decomposes into cyanic acid and ammonia in an endothermic reaction:

6 (NH₂)₂CO → 6 HCNO + 6 NH₃

Then, cyanic acid polymerizes to form melamine and carbon dioxide:

6 HCNO → C₃H₆N₆ + 3 CO₂

This is exothermic, but the overall process is endothermic.

Melamine is widely used industrially to manufacture plastics, adhesives, countertops, dishware and whiteboards. It is prized for its durability and is used to produce brightly-coloured dishware most popular in the 1950s. As a component of plastics and laminates (in wood, dishware etc.), melamine is used to form a melamine formaldehyde resin that is a hard, thermosetting plastic material made from melamine and formaldehyde by polymerization.

Picture of melamine plates

Melamine resin is known for its fire resistance and heat tolerance. In contact with heat, it decomposes, thus acting as a heat sink; furthermore it releases inert nitrogen gases upon combustion thus limiting the access to oxygen and flammable gases; and the resin also chemically and physically inhibits burning through char formation.

However, melamine has numerous biological side effects which have grabbed the world’s attention through the recent China milk contamination debacle. Where adulteration of the milk took place, water was added to raw milk to increase its volume, but this lowered its nutritional and protein content, which was checked by distributors by measuring nitrogen content. This prompted farmers to add melamine to increase the apparent protein content due to the high amount of nitrogen present.

There have been no studies on melamine on human health, but it can be extrapolated from other studies involving small mammals and other animals. Exposure to melamine has resulted in the irritation of eyes, skin and mucous membranes; dermatitis; chronic inflammation of kidneys and the ulceration of urinary bladder epithelium in mice; urolithiasis (kidney stone formation, at the centre of the recent scandal); and bladder cancer. Melamine’s effects are most serious in the kidneys and urinary tract, with ingestion of melamine in animals resulting in acute renal failure. Bladder tumours found through animal studies were secondary to the development of calculi (kidney stones) and uroliths (urinary bladder stones), caused by chronic physical injury by such stones.

Picture showing kidney stones formed
from mineral deposits in the kidney

The main constituents of the stones in the urinary bladders of rats given melamine in the diet were found to be unchanged melamine and uric acid in a 1:1 molar ratio. Melamine complexes with cyanuric acid to form melamine cyanurate, precipitating as stones in the bladder and kidneys. This crystalline complex is held together by hydrogen bonds similar to DNA base pairing, and is repeated throughout to form an extensive network of hydrogen bonds and a lattice-like structure. The formation of this complex vastly increases its toxicity over melamine and cyanuric acid individually.

Extensive hydrogen bonding between melamine (in blue) and cyanuric acid (in red)

The tolerable Daily Intake (TDI) of melamine as established by the US Food and Drug Administration (FDA) is 0.63 mg/kg of body weight. This means that an adult weighing 60 kg or a child weighing 30 kg can ingest 37.8 mg of melamine and 18.9 mg of melamine respectively every day over a lifetime without any appreciable health risk.

But even if officials say these safety figures are already a reduced estimate, who really knows about melamine’s true effects? Meanwhile what we can do is to be judicious in selecting our groceries and food intake, avoiding those suspected dairy products from China.

Picture of polyunsaturated fatty acids, including
omega-3 (n-3) and omega-6 (n-6) fatty acids

Here’s something that has not been reported in the news so far though: scientific studies show that dietary PUFA (polyunsaturated fatty acids) modulate differentially normal and pre-neoplastic (preceding the formation of an abnormal growth of tissue, which can be benign or malignant) urothelial proliferation induced by melamine. Fish oil, rich in omega-3 fatty acids, have shown a strong protective effect against the formation of such uroliths.

A toast to salmon!

Welcome!!

Hi guys!

Welcome to the inaugural RSBS blog! This is meant to complement the existing yahoo groups by offering up a new means for discussion on anything and everything (literally) under the sun that is related to biology. For we know that there is a world out there waiting for us to explore, and there are many stuff that we can share to enrich each other.

Take your time to explore the features of the blog: for your convenience, posts can be grouped under common labels of your choice for easy classification so others can refer to them more conveniently. Comments can be added on to any post under any category(label) at any time, so feel free to air your views!

The calendar on the side bar can be used to mark out important dates to you and the club, so do refer to it periodically to check for upcoming events, and feel free to add any event to the calendar. Soon meeting dates will be added to the calendar as well, so just check the calendar to see when and where our weekly meetings will be.

Please put up any interesting things related to biology on the blog, or contribute your comments about the club, activities conducted, or even takeaways from lectures and tutorials! From time to time, bits of interesting facts will also be put up on the blog, so keep posted for this!

Dive in and maximize this blog space! We hope to get a lively discussion going!

Best wishes,
Exco of '08-09