Human Genetics shows the migration pattern of human species

Hi,

Using DNA from thousands of people from all around the world, Dr Spencer explains how our ancestors migrated around the world starting 60 thousand years ago.



Cheers

A Biologist's Mother's Day Song

Hi,

Here is something you should send to your mother in appreciation of all that she had given you.
It is a belated mother's day gift.



Much to my surprise, some people have requested the mp3--now you can get it here:
http://www.cdbaby.com/cd/cadamole (it's the first song)

Lyrics:
To make one me you just add
Half of mom and half of dad
That is what I once believed
But I know now that I was wrong
I got so much more from you mom
Than just half a set of genes
I got nutrients and transcription factors
and nearly everything that matters
plus my prenatal environment (transplacental inheritance)
mRNA, mitochondria,
That back in the day once belonged to ya (they're cytoplasmic)
and I just want to thank for supplying them

Just like two strands of DNA are spirally entwined
Your nature and your nurture are inspiringly combined
Scientists remind me and I find that it is true
Slightly more than half of everything I am is thanks to you

Mitochondria power my cells
and they have DNA as well
Transcription factors modulate transcription
And since they're in the cytoplasm
The eggs the only one that has em
and sperm I guess they don't have much ambition

My sex determination gene means that I'm a guy
From you I got my X chromosome, from Dad I got my Y
X has over a thousand genes, Y has less than 92
That's why more than half of everything I am is thanks to you

I roomed in your womb for nine whole months and never paid the rent
Your glucocorticoids shaped my hypothalmic development
I took in your blood and sucked it dry of every nutrient (its gross but true)
Sometimes I wonder where the time went (where did it go)
Sometimes I wonder where it went

I know Ill never understand all you have done for me (I'm not that smart)
But since you paid for college Ill get my B. S. degree (bachelor of science)
And I have learned its not BS but absolutely true
Slightly more than half of everything I am is thanks to you.

Cheers

Influenza H1N1 aka swine flu

Hi all,
Click on the image above to see it at a higher resolution. Source: Wikipedia

Today's entry contains the following:

• Q and A on the recent influenza scare that is sweeping across all the time zones of the earth within 24 hours.


• Link to Discovery New blog entry on the 1918 influenza pandemic


• Five videos of the survivors of the 1918 influenza pandemic. These people were very young children then and they should be in their 90s now.

Teachers may like to use the poster above to teach how genetic shifts occur in live-stock animals when they are infected with Influenza A virus.

Language teachers may like to use the videos to train their pupils to brush up on their listening skills.

Biology teachers of course can use this pandemic to teach how artificial selective breeding in live-stock and food animals can create a conducive environment for genetic shifts in pathogens.


Here is some information that I gathered by reading the newspapers,especially Dr Andy Ho’s articles in the Straits Times, Wikipedia, magazines and other sources. I would like would like to answer some of the usual questions that my students have asked me.

Q: Why is the swine flu called swine flu?

A: It was responsible for the 1918 Influenza pandemic that killed as many as 100 million people worldwide, but what we now know as H1N1 was first isolated and identified in pigs in the 1930s. It was the practice in those days to name germs after the organism where it was first found.

Q: How did this particular virus suddenly come about?

A:There are 3 types of influenza viruses, A, B, and C. Of these, influenza B and C can only infect humans. Influenza A viruses (which include Swine Flu) can infect a variety of animals such as chickens, ducks, pigs, wild birds and humans too. Each of the Influenza A viruses is specialised to infect a particular species of animal best, but some cross infection of other species can occur. For example some Bird Influenza A viruses can infect pigs too. Because of this, a situation could arise where 2 or more Influenza A viruses adapted to different animal species infect the same cells in a sick animal at the same time.

When this happens there is a likelihood that the gene segments of the co-infecting viruses could get mixed up while the viruses reproduce. This produces a new ‘hybrid’ virus in a process called genetic shift.This is exactly what happened in the case of the Swine Flu. Scientists have found that the Swine Flu virus contains gene segments of Pig, Bird and Human Influenza A. In essence, it is a new ‘Frankenstein' A virus that has been pieced together from the other regular viruses. It is a modified descendant of the same virus that caused the Spanish flu in1918.

Q: How do people die from swine flu?

A: The immune response of the body causes an "immune storm" to occur in the lungs. H1N1 has not caused a major pandemic since 1918, so several generations have grown up with no experience of this virus. It is so new to us that our immune systems throw everything at it. Lots of white blood cells swarm to the air sacs or alveoli, the blood capillaries dilate or become wider and more porous. This thickening of the alveoli walls reduces lung capacity, but there is worse to come. Blood fluids or plasma and also blood cells begin to leak into the alveoli and the patient will literally "drown" in these fluids. Due to the layers of white blood cells and other cells gathering at the alveoli and the flooding of the alveoli with fluids, oxygen will not be able to diffuse into the blood capillaries, causing breathlessness. Fluids stagnating in the alveoli will also attract germs to grow in it and cause further congestion.

Q: Why is there a high fever during flu?

A: The body raises its temperature to make conditions less comfortable for the virus and enable the immune system can work at a higher level of efficiency. However, the toxins produced by the immune system in response to the viral infection will travel in the blood to the brain and cause the brain to reset the optimum temperature at an even higher number. So the body thinks that it is still too low and so increases it even higher. (That is why you shiver when you are having a fever. The body thinks you are too cold as the brain thermostat has been set higher.)

Q: What is the difference between this flu (H1N1) and the seasonal winter flu?

A: The seasonal flu kills the very weak, the very old or the very young. But the H1N1 killed the robust, the healthy, the young, and the strongest cohort of the population.

At any one time, a significant proportion of the population has some immunity to each seasonal influenza virus and so it rarely spreads as quickly or causes as many deaths. In contrast, a ‘new hybrid’ virus such as swine flu, to which almost nobody in the population has any immunity to, spreads very quickly through the population and causes much worse symptoms resulting in much greater morbidity and mortality.

I would like to share a very interesting set of videos that I chanced upon. they are produced by Discovery News. It consists of a 5 part YouTube video set, each about 9 to 10 minutes. Briefly these are the salient points I gleaned from these videos. (Or you could skip my commentaries on the videos and go straight to them instead.)

1. A handful of survivors of the 1918 flu epidemic recount their personal circumstances. They were mostly about 5 or 6 years old then.


2. Four out of 10 workers in a young boy's father's shop died in quick succession.


3. Denial of the horrendous death rates was common.


4. People were concentrating on the World War I efforts instead and they did not want to think about death by disease.


5. Sick soldiers lying on the hospital floors were waiting for those on the beds to die, so that they could be upgraded to the beds.


6. The most common mode of catching the infection was in large gatherings.


7. The people in some towns were not allowed to travel out but the mail man brought the germs down the road when he delivered the mail in horse-drawn carriages.


8. Victims' fevers were so high that their hair turned white overnight and fell out.


9. People did not know what caused the disease, only guessing that it was caused by a bacterium. (By the way, the name, 'influenza' is simply Italian for "influence", showing how little was known about its cause.)


10. Maybe the Germans were spreading the bacteria. The Americans did not know about virus yet. (No electron microscope in those days.)


11. Everyone who put on the masks felt safe. But the masks were coarse and not designed for tiny virus particles. It is likened to using chicken wire to keep out dust in the air!


12. Victims drowned in their own fluids in the lungs, but this was passed off as bacterial pneumonia instead.


13. Children sang songs when they played skipping ropes or other games where the lyrics contained words such as influenza. For example:
    
    I had a little bird,
    And its name was Enza.
    I opened the window
    And in-flew-enza.


14. Vaccines were produced and distributed by trains. However they did not work as they were meant to kill bacteria not virus.


15. Folk remedies were prepared and used widely. They had the taste and smell of medicine but it did not harm people but instead helped them through the placebo effect. The smells were so bad that people did not want to go near those wearing them as talismans.


16. When patients arrived at the hospitals in ambulances, toe-tags where put on them even before they died!


17. When the patients looked very sick the nurses were told not to waste food on them, hence not feed them.


18. Mortality rate was close to 100% amongst the Red Indians. This is compared to 40% amongst the whites.


19. The seasonal flu kills the very weak or the very old or the very young.But the H1N1 killed the robust, the healthy, the young, and the strongest cohort of the population.


20. Soldiers who were sent by troop ships across the Atlantic Ocean to fight in WW1 faced an 80% mortality rate due to overcrowding.President Wilson was aware of the figures but he still had to fight the Germans. The people of America supported his decision.


21. Open wooden boxes with the dead persons were placed outside the main door and a government trucks came by to collect them.


22. The coffins were lowered into mass graves dug with excavators.


23. Guards were stationed outside coffin shops as they might get stolen.


24. Some men cut the throats of their wives and children before they killed themselves to avoid the flu.


25. People thought Armageddon itself was upon them. Others thought civilisation was ending.


26. The flu disappeared as suddenly as it appeared.


27. WW1 ended and the Germans were defeated just as the flu died away.


28. Scientists think that the critical number of immune survivors was reached right then and so the virus could not kill any more people and it became less virulent.


29. 'How can we forget so horrendous an event?', say the survivors who are in their 90's now.


30. Some of the survivors who where about 5 or 6 years old then lost their mothers. They suffered from life-long sadness and a feeling of being unsafe without their mothers.



You can read the actual article at this address:
'swine flu linked to 1918 influenza pandemic'

The five videos are copied here for your easy playing.


The 1918 flu pandemic 1 of 5


The 1918 flu pandemic 2 of 5


The 1918 flu pandemic 3 of 5


The 1918 flu pandemic 4 of 5


The 1918 flu pandemic 5 of 5

Note that these videos mostly recount the American experience. The 1918 pandemic was worldwide and killed an estimated 70 - 100m people.
Cheers

Lesson 1: Mutation

Hi,

On Nov 10, I happened to chance upon something in the Straits Times that I wanted to talk to you about.

There was a photograph of a cute baby, all of 2 weeks, born in China who has 8 toes on each foot!His hands looked normal with 5 fingers each.

This is the result of a mutation. His parents are normal, with 5 digits in each limb.

Mutations are caused by mutagens or carcinogens found in the environment, radiation from the sky (e.g. cosmic rays, X-rays, gamma rays, even UV light), natural radioactivity from minerals within the Earth, and a multitude of chemicals. Gamma rays are used nowadays to irradiate grains and seeds before storage to kill all fungi and bacteria on the surface of these seeds.

A mutation occurs when one or more genes (on the DNA) get changed during meiosis. The resulting gamete if fertilized, will develop into an offspring which may show such effects as polydactyly (too many fingers or toes). But many will have no visible effect.

Most of us have tiny changes in us which are called genetic variations. These are mostly not visible and inconsequential and if the changes are not deleterious, we go through life not knowing that we are different, physically and physiologically, that is.

Normal alimentary canal
(Source: www.scienceaid.co.uk)

I have read about people who are middle-aged before they found out that they have 4 kidneys and 4 ureters. It was only discovered when they had a radioactive dye injected into them to trace the path of discharge of urine from the kidneys via the urinary bladder.

Another incident involved a person who did not know that he had laterally-inverted visceral organs. This means that his internal organs were on opposite sides from nearly all people. His stomach was on his right, the appendix on his left, etc...

Oh, I forgot about his heart being tilted to his right instead of his left...

Students, please remember what I told you about the diagrams in text books? They are always drawn laterally inverted. You have to imagine that you are a doctor looking
at a patient lying on a operating table. The textbook diagrams always show organs as viewed by a doctor.

Cheers,
Have a good day.