The tale that army ants are able to eat animals even people are not true, neither. Indeed army ants can beat big animals with their huge populations. However, they cannot beat other animals on speed. In other words, because they are so small that their paces have to be also small. This makes their locomotion speed very limited. The distance ants can travel within an hour is about one hundred meters, which is much slower than most animals. So as long as you want to escape from them, you can easily survive. Of course, this does not mean ants cannot catch animals. Those which are held in barn cannot escape so not surprisingly, become ants' food at the end.
When they move from one place to another, they can cover an area of hundreds of meters long and tens of meters wide. You can hear the sound of their moving and eating. When they settle down at a certain place, the queen ant's reproductive system immediately develops into mature condition and can help her to produce 100 to 300 thousand eggs within a week. After the hatch of those eggs, the army departs again for next camping location. By then, the queen ant becomes slim and has strong legs so she can move together with her army to the next nest.
Wednesday, September 28, 2011
Army Ants (1).
Most army ants live in tropic areas including Asia, Africa and America. They were described as that they can eat everything along the way they went by which include plants, crops and animals such as horses, mouse, insects even elephants. Some people thought they can be as big as a fox and able to dig into depth to find the food. Other people thought they could survive in the desert where is short of food and they feed on gold. They were regarded as an evil creatures.
But the fact is, they are one or two centimeters long at the most. They do not live in a place for a long time, usually for only two or three weeks. Then they move to another place for more food source. During the moving, ants get together to form a big lobe containing queen ant and larvae inside on the tree. The total mass can reach 1 kg so that might be the reason why people thought they can be as big as a fox. Ants cannot feed on gold or other kinds of mental, even though they are army ants. The season they were thought eating gold is that ants dig very deep to make their nest. Sometimes they make some sand containing gold out of their nest around the entrance of their nest. People misunderstood them that they were eating gold.
But the fact is, they are one or two centimeters long at the most. They do not live in a place for a long time, usually for only two or three weeks. Then they move to another place for more food source. During the moving, ants get together to form a big lobe containing queen ant and larvae inside on the tree. The total mass can reach 1 kg so that might be the reason why people thought they can be as big as a fox. Ants cannot feed on gold or other kinds of mental, even though they are army ants. The season they were thought eating gold is that ants dig very deep to make their nest. Sometimes they make some sand containing gold out of their nest around the entrance of their nest. People misunderstood them that they were eating gold.
Tuesday, September 27, 2011
Packing DNA up.
Can you imagine that if we extend and align our DNA end by end, it will be long enough to go across the middle of the Africa. Yes, it is true.
Our DNA is packed in the unit called nucleosome. The scaffold of the nucleosome is consisted of a series of proteins called histones. Different histones including H2A, H2B, H3 and H4 bind to each other to form a round octamer. 147 nucleorides are twisting around this histone complex. Together with linker nucleorides between histone complexes, about 200 nucleorides are contained in one nucleosome. Nucleosomes then further wind along the same axis to form a nucleosome fiber, standing vertically relative to the fiber axis. N terminals of histone subunits are critical for this fiber forming and covalent modification can be made on N terminals to activate or deactivate a certain DNA region.
Our DNA is packed in the unit called nucleosome. The scaffold of the nucleosome is consisted of a series of proteins called histones. Different histones including H2A, H2B, H3 and H4 bind to each other to form a round octamer. 147 nucleorides are twisting around this histone complex. Together with linker nucleorides between histone complexes, about 200 nucleorides are contained in one nucleosome. Nucleosomes then further wind along the same axis to form a nucleosome fiber, standing vertically relative to the fiber axis. N terminals of histone subunits are critical for this fiber forming and covalent modification can be made on N terminals to activate or deactivate a certain DNA region.
Olfactory, gustatory and pheromone systems 3
Flies have different sensory systems which can be divided into two categories: generalist and specialist systems. Generalist system responds to general chemical such as sugar and bitter that exist everywhere. This category includes olfactory and gustatory systems. The specialist system refers to pheromone system, in which those neurons respond to pheromones. The reason it is called specialist system is that pheromone system responds to pheromone strictly from the same species and single neuron responds to only one single type of pheromone so it is highly specific.
Pheromone can trigger a lot of behaviors.
Pheromone can trigger a lot of behaviors.
- Aggregation. Animals can get together to fight or threaten the predators. They express pheromone to recruit their partners.
- Sex. Females can release pheromone to notice the males that they are ready to mate. The pheromone can be sensed from miles away.
- Trail. Ants can leave pheromone on the way home with the food. So that other ants can track the signal to find and carry the food home.
- Territory. Dogs and cats have their pheromone in their urine. They put the signal at the border of their territory to demonstrate there is an occupant here.
Olfactory, gustatory and pheromone systems 2.
How can we or flies tell thousands of tastes or smells, considering that flies have only hundreds of neurons?
The olfactory system employs a 'combination' strategy: each olfactory neuron has only one single type of receptor which is sensitive to chemicals. There are several decades of receptor types, that is decades of neuron types. Each neuron can be activated by multiple chemicals and each chemical can activate multiple types of neurons.The result is, odorant A can activate neurons #1, 5 and 9, and #1 neuron can be responsive to odorant A, B and E. Similarly, neuron #5 can be activated by odorants C, F and H.
This kind of combination can make a matrix with thousands of different combinations, which enables flies to sense as many odorants as necessary: If #1, 3 and 5 neurons are activated by this odorant, it will be sugar. If #1, 4 and 9 neurons are responding to this odorant, it will be bitter.
The olfactory system employs a 'combination' strategy: each olfactory neuron has only one single type of receptor which is sensitive to chemicals. There are several decades of receptor types, that is decades of neuron types. Each neuron can be activated by multiple chemicals and each chemical can activate multiple types of neurons.The result is, odorant A can activate neurons #1, 5 and 9, and #1 neuron can be responsive to odorant A, B and E. Similarly, neuron #5 can be activated by odorants C, F and H.
This kind of combination can make a matrix with thousands of different combinations, which enables flies to sense as many odorants as necessary: If #1, 3 and 5 neurons are activated by this odorant, it will be sugar. If #1, 4 and 9 neurons are responding to this odorant, it will be bitter.
Olfactory, gustatory and pheromone in insects.
Like mammals, flies have two systems helping them sense the world, olfactory and gustatory systems. They use olfactory system to sense volatile chemicals whereas gustatory system to feel soluble compound.
Their olfactory system consists of two third antenna segments on the head and the maxillary palp. Those two appendages are covered by hundreds of sensillia each of which is filled with dendrites of two to four neurons. Those neurons are sensitive to volatile chemicals so they are called olfactory sensory neurons (OSN). Those neurons project to antenna lobes in the brains and signals get organized and coordinated in the brain.
The gustatory system is comprised of proboscis and the sensillia all over the body including wings and legs. Sensory neurons project to the subesophageal ganglion which is a higher level of gustatory signal center. The advantage of having gustatory sensory neurons on legs and wings is that flies do not have to be at the risk of taking some toxic ingestion if they are not sure whether some food is good or not. They can simply use their legs to touch the food then they know it is delicious or shit. On the contrary, we can not tell it until we put something in our mouth, which is risky.....
Their olfactory system consists of two third antenna segments on the head and the maxillary palp. Those two appendages are covered by hundreds of sensillia each of which is filled with dendrites of two to four neurons. Those neurons are sensitive to volatile chemicals so they are called olfactory sensory neurons (OSN). Those neurons project to antenna lobes in the brains and signals get organized and coordinated in the brain.
The gustatory system is comprised of proboscis and the sensillia all over the body including wings and legs. Sensory neurons project to the subesophageal ganglion which is a higher level of gustatory signal center. The advantage of having gustatory sensory neurons on legs and wings is that flies do not have to be at the risk of taking some toxic ingestion if they are not sure whether some food is good or not. They can simply use their legs to touch the food then they know it is delicious or shit. On the contrary, we can not tell it until we put something in our mouth, which is risky.....
Tuesday, September 20, 2011
Monarch colonies.
As we may see, there are 12 colonies in Mexico. Monarch stays only on moutaintops and those are the only habitats for them after millions of years' evolution. Isn't it exciting if my wedding is held there? Imagine that there are millions of butterflies flying around you, covering the whole sky. They are showing their bless on us. I got this inspiration last night.
Yesterday night, two speakers from Discovery Insitute brought us a beatiful movie about the metamorphosis in Monarch. The movie was well made with fantastic pictures and close video description of the life cycle of a Monarch. However, their conclusion is that, random mutation cannot make this fancy organism organized like that and they cannot evolve that migration stratergy by chance. All those amazing are due to the Intelligent Design. This was my first time hearing about intelligent design but I thinkit is pretty much alike between ID and God - when something is too fantastic to explain by science, it comes from ID or God.
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