Biology Projects from 2CO

Great work from 2CO! Very impressive!

1. Sensations by Miriam, Weixin, Ellis and Grace

2. DNA by Yanxuan, Kayean, Hannah, Charisse and Yingying

3. Prime Investigators by Su Jin, Kaysee, Samantha and Yun Rui

4. Ace Attorney game by Kimberly Quah, Kirsten, Megan, Amanda and Xinhui

5. Aging by Chloe, Jaime, Hillary and Clare

Physics to Excite!

Hi 1SE, here are your photos for Physics to excite. Most photos were badly taken because there were students who refused to look at the camera or blocked themselves from view >=( Anyway, looks you had a great time and learnt a lot!

Food Entrepreneurs

Hi girls you can access your photos here. Glad to see that everyone had fun! XD

Photos to Underwater World Sleepover Program are here!! Photos will be uploaded in batches though, because they came from different cameras so I will need some time collating them. Check again at the end of the week, especially for the sea lion photos.

Common weed-killer chemically castrates frogs: study

WASHINGTON (AFP) - – One of the most common weed-killers in the world, atrazine, causes chemical castration in frogs and could be killing off amphibian populations worldwide, a study published showed.

Researchers compared 40 male control frogs with 40 male frogs reared from the moment they hatched from eggs until full sexual maturity in atrazine concentrations in the range that animals experience year-round in areas where the chemical herbicide is found.

Ninety percent of the male frogs exposed to atrazine had low testosterone levels, decreased breeding gland size, feminized laryngeal development, suppressed mating behavior, reduced sperm production and decreased fertility, while the control group showed features typically found in male frogs.

And what happened to the remaining 10 percent of atrazine-exposed frogs was deemed "the most dramatic finding" of the study by the researchers, led by Tyrone Hayes of the University of California at Berkeley: they developed into females that copulated with males and produced eggs.

The larvae from those eggs were all male, the study published in the Proceedings of the National Academy of Sciences (PNAS) found.

"Many studies have focused on death from disease and its role in global amphibian declines and sudden disappearances of populations, but virtually no attention has been paid to the slow, gradual loss of amphibian populations due to failed recruitment," the study said.

"The production of sex-reversed all male-producing animals could drive populations to extinction," the authors of the study warned.

Earlier studies have found that atrazine also caused feminization in zebra fish and leopard frogs and caused a significant decline in sperm production in male salmon and caiman lizards.

Atrazine is widely used by farmers in 60 countries around the world as a weed- and grass-killer, particularly in fields of corn, grain sorghum and sugar cane. It is also used on golf courses.

Apart from the United States, Australia and China are among the biggest markets for atrazine, according to Tim Pastoor, principal scientist for Syngenta, the US company that makes the herbicide.

Atrazine is banned in the European Union, but farmers there use an almost identical chemical called terbuthylazine, Pastoor said.

Environmental activist organizations in the United States have called for atrazine to be taken off the market in the United States, but the Environmental Protection Agency (EPA) four years ago refused to ban the chemical.

"The EPA have already considered the question of whether or not atrazine will affect frogs' sexual development, and the answer to that is clearly no," Pastoor told AFP.

"But the main reason Syngenta stands behind atrazine is because farmers have come to us and said, 'Please keep this product on the market.'

"The reason they ask us is because it's a product that works, it increases crop yields, and it's inexpensive, and something that's inexpensive and works is magic to a farmer," said Pastoor.

Around 80 million pounds of atrazine are applied annually to crop fields in the United States alone, and half a million pounds of the herbicide fall to earth in rainfall in the United States, some of it hundreds of miles from the farmland where it was originally applied, the study says.

"Atrazine can be transported more than 1,000 kilometers (620 miles) from the point of application via rainfall and, as a result, contaminates otherwise pristine habitats," the study says.

Atrazine has also been associated with low sperm count, poor semen quality and prostate problems in humans.

A small study led in 2003 by University of Rochester professor in environmental medicine Shanna Swan found that men who lived in the Midwest -- the biggest corn-growing region in the United States -- who had high levels of atrazine in their urine also had low sperm counts.

"We haven't been able to follow up and confirm that study, but it did find an association," Swan told AFP.

"But the important message here is: this is a very prevalent exposure. Human beings are definitely exposed, and a lot of them, because it's the most commonly used pesticide," Swan said.

Reference: Yahoo Singapore News

Third-hand smoke also bad for you: study

WASHINGTON (AFP) - – You know smoking is bad for you. You know inhaling someone else's smoke is bad for you. Now a US study says third-hand smoke -- tobacco residue clinging to surfaces -- is also bad for you.

When a cigarette burns, nicotine is released in the form of a vapor that collects and condenses on indoor surfaces such as walls, carpeting, drapes and furniture, where it can linger for months, said the study, which was published in the Proceedings of the National Academy of Sciences (PNAS).

"Our study shows that when this residual nicotine reacts with ambient nitrous acid it forms carcinogenic tobacco-specific nitrosamines, or TSNAs," said Hugo Destaillats, a corresponding author of the study.

"TSNAs are among the most broadly acting and potent carcinogens present in unburned tobacco and tobacco smoke," he said.

The most likely human exposure to TSNAs is through either inhalation of dust or the contact of skin with carpet or clothes -- making third-hand smoke particularly dangerous to infants and toddlers.

Opening a window or turning on a fan to air out a room while a cigarette burns does not eliminate the hazard of third-hand smoke. Smoking outdoors doesn't help much either.

"Smoking outside is better than smoking indoors but nicotine residues will stick to a smoker's skin and clothing," said Lara Gundel, a co-author of the study.

"Those residues follow a smoker back inside and get spread everywhere. The biggest risk is to young children," she said.

"Dermal uptake of the nicotine through a child's skin is likely to occur when the smoker returns and if nitrous acid is in the air, which it usually is, then TSNAs will be formed."

Substantial levels of TSNAs were also found in the truck of a heavy smoker, the study says, adding that most vehicle engines emit some nitrous acid that can infiltrate the passenger compartment of a vehicle.

Researchers from the Lawrence Berkeley National Laboratory led the study, which they say is the first to quantify the reactions of third-hand smoke with nitrous acid.

Reference: Yahoo news: Third hand smoke also bad for you

Imagination

"Imagination is everything. Imagination is more important than knowledge. For knowledge is limited to all we now know and understand, while imagination embraces the entire world, and all there ever will be to know and understand." Albert Einstein

I have been thinking about this quote by Einstein. Science and maths have always been subjects that required a lot of imagination without us realising it. In maths, numbers require imagination because they are abstract in nature. For example, there is no such thing as a "5". It cannot be seen. However, you can see 5 oranges, 5 cars and 5 tables. "5" therefore, is something that we have to imagine and relate to in order to grasp the fundamentals of maths, such as addition and subtraction.

Likewise, there is a lot of imagination in biology. We cannot see molecules or atoms floating about within our body. Yet, they are there and we have to imagine how these small particles come together to make up the whole organism. Sometimes, imagination is hard work, but with time, imagination lays the foundation for greater discoveries.

Please don't lose your imagination and ability to visualize and understand the "scientific definitions"! On a lighter note, here is a really imaginative movie :) :

Mouse with a Human Ear

Somewhat disturbing post by Karl S. Kruszelnicki of ABC Science:

Back in 1997, a rather bizarre photograph suddenly became very famous. It showed a totally hairless mouse, with what appeared to be a human ear growing out of its back. That photograph prompted a wave of protest against genetic engineering, which continues today. But there was absolutely no genetic engineering involved in getting that ear to cover almost all of the mouse's back.

The layperson might ask, why would you want to have a "spare" human ear? The reason is that it's very difficult to repair the ear. The ear is mostly made of cartilage, which is tricky to work with, and at the same time, has a highly visible and complicated shape. So a spare ear would solve a lot of problems. The Indian surgeon, Sushruta, describes operations to repair the ear in 600 BC. The ear is often damaged in car accidents, fights or fires. There is also the disease called "microtia", which means literally "small ear". It can range from a slightly smaller ear, to almost complete absence of the external ear. It can occur in up to 1 in 1,000 births.

In August 1997, Joseph Vacanti and his colleagues wrote their ground-breaking paper in the journal, Plastic and Reconstructive Surgery. The publicity was enormous, helped by a film made by the BBC's Tomorrow's World.

On October 11, 1999, the anti-genetics group, Turning Point Project, placed a full-page ad in the New York Times showing the photo of the mouse with the human ear, with a misleading caption that read, "This is an actual photo of a genetically engineered mouse with a human ear on its back". In truth, the mouse was not genetically engineered, and the "ear" had no human cells in it.

A "genetically engineered mouse" would have to have its DNA (its genetic "blueprint") modified. The Turning Point propaganda implied that some DNA from a human (the section that has the blueprint for making the human ear) had been inserted into the DNA of the mouse. Then, this human DNA had somehow taken over the mouse DNA, and commanded it to grow a human ear. But it never happened - the mouse in the famous photo had never been genetically engineered.

The "mouse-ear" project began in 1989, when Charles Vacanti (brother of Joseph) managed to grow a small piece of human cartilage on a biodegradable scaffold. The scaffold was the same synthetic material (99% polyglycolic acid and 1% polylactic acid) used in dissolving surgical stitches. In the body, it degrades into carbon dioxide and water. The fibres of this material were woven into a loose mesh that was 97% air - leaving lots of room for cells to grow into. His surgeon colleagues had told him that the human ear was the body's most difficult cartilaginous tissue to reconstruct and rebuild - and that they would love to have a "spare" ear to transplant.

After 8 years, Charle's team got to the stage where they could mould their sterile biodegradable mesh into the exact shape of a 3 year-old's ear. The next step was to seed this ear-shaped scaffold with cartilage cells from the knee of a cow (remember how I said that the famous mouse-ear had absolutely no human cartilage cells in it). The team used a Nude Mouse. The Nude Mouse got its name thanks to a random mutation in the 1960s that left the mouse with no hair, and virtually no immune system. The lack of hair was irrelevant to their project, but the lack of immune system was critical. It meant that the mouse would not reject the foreign cow cartilage cells. The only purpose of the mouse in this project was to supply power to let the cow cartilage cells grow. The cartilaginous ear was implanted under the skin layer of the mouse, but over the muscle layer. Over some three months, the mouse grew extra blood vessels that nourished the cow cartilage cells, that then grew and infiltrated into the biodegradable scaffolding (which had the shape of a human ear). By the time that the scaffolding had dissolved away, the cartilage had enough structural integrity to support itself.

That cartilaginous structure that looked like a human ear was never transplanted onto a human, because it was full of cow cells and would have been rejected by a person's immune system.

But the same Tissue Technology was used for 12 year-old Sean G. McCormack, who was born with Poland's Syndrome. He had absolutely no bone or cartilage on his left chest. His heart and lungs were protected only by skin. This was a problem everyday, and especially in his beloved sport of baseball in which he was a star pitcher - because a single ball to the chest could kill him. The Vacanti brothers used McCormack's own cartilage cells to grow a "chest plate", the size of a CD, on their synthetic biodegradable polymer, that was moulded to the shape of his chest. They implanted the seeded cartilage in his chest, and it grew with him.

But like the mouse with the "human" ear, there was absolutely no genetic engineering involved - only genuine scientific invention…

Reference: Mouse with Human Ear

Inspiration from a leaf

Antoni Gaudi was an architectural legend who designed many iconic buildings in Barcelona.

Thia is one of his creations: a school with an undulating roof. The undulating roof allowed rainwater to run off quickly.



The design of the roof was derived from this inspiration:



Yes, a leaf.

Students often ask, why do we have to study cells or leaf structure? Do I actually use these knowledge? Not many of us will eventually further our studies in Science, but there are many things that we can appreciate from the beauty of different life forms. They can be inspiration for different works, just like Antonio Gaudi used a leaf as inspiration for architecture.

Lighting the Bunsen Burner is easy!

Sec 1s, this is a good video to watch. The guy (Mr Keller) in the video has some interesting experiments at the end.

Sec 2s, this is a good review for you, in case you are not confident of handling the Bunsen Burner.

Every organism starts from a cell!

This post is specially for 1SE:


Thanks for all your photos, here's a picture of our "baby photoboard" :) Your photos were awesome cute!


Remember that all life starts from a single cell:

What is your place in the World?

Interesting Presentation Created by Karl Fisch, and modified by Scott McLeod.