Army Ants (2).

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.

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.

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.

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.

• 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.

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.....

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.

Monarch bufferfly.

 

Have you ever heard about butterflies able to migrate across America and through the sea? Monarch can!

Monarch is born is north America and south Canada. As caterpillars, they eat only milkweed leaves, which give them toxin, so as to protect themselves from predators. After several molts, they become flying butterflies and they depart the bith place for Mexico, along with the shorter day length. There are several different migration pathways and one of them is to go across the Mexico Gulf (not shown in the picture). When they find grilling platform on the sea, they will have a rest on this precious 'land' and depart in the following morning. In Mexico hemihibernating field, there are tens of thounds of butterflies getting together. Here, their reproducing system get inactivated and they stay in clusters, in order to keep warm, for six months.

When spring comes, they fly back to America and Canada, with active reproducing systems. Upon arrival at the breeding place, they begin to mate and lay eggs, and also their life reaches to the end.

Whales, parlicons, sea lions and dolphins in San Diego.

This was the whale-watching season in San Diego - Humpback. Unfortunately I was so sea-sick that I cannot even stand up when I saw the whale so not surprising that I have no pictures for whales here. However, I got pictures for early creatures - sea lions and parlicons as well as dolphins.

Sea lions are the first animal appearing in our sight. They climbed up to the buoyto to enjoy the sun. Later on, both dolphins and parlicons appeared at the same time because they are chasing the same swarm of fish. Parlicons are big birds gliding in the wind. They are more than two meters wide with wings expanded and dive into the sea to catch their food fish. When they are not hunting, they can glide quiet at one meter above the sea surface as a fleet (see videos). Don't complain about the poor quality of the videos because they were caught with my cell phone.Also, you can see clearly at least three dolphins in the second picture. They were swimming right beneath our ship.

The largest urban bat colony in Austin.

Austin owns the largest urban colony of bats all over the world - which is a 1.5 million population. They stay beneath the Congress Bridge of the downtown area of Austin, TX and head to the forest for their food during dusk. More than one million bats are flying in the sky at the same time and it is the splendour of the nature.

Freetail bats migrate between Mexico and Austin from Spring March to Fall September. Late August or early September is the best timing for bats watching because the next generation have been able to fly together with their parents, which means the population reaches its maximum. The daily foraging timing varies from 8:00pm to 8:30pm in different months but basically they will depart the bridge at the sunset. They will head to the west side of the bridge and tons of insects have been in their stomach after they return. The departing process will last for 15 minutes.

Rio

There was a recent movie called Rio describing how a precious blue macaw was adopted in a bookstore and at last returned to his forest.

The movie makes animation roles for birds, monkeys and humans. Birds hunters catch beautiful and precious birds from the forest and sell them in the market as pets. Blue is caught when he was a baby and dropped off the truck when he was carried to the market. Fortunately he was found and adopted by a lady who was the owner of a bookstore.An ornithologist found Blue by accident and proposed that he is the only male blue macaw in the world and the ornithologist owned the only female - easy to guess that they gathered them together to breed more progeny. Before they make more progeny, the pair of blue macaw was stolen and sold to bird sales. There are hundreds of birds got collected and to be sold. Because Blue was bred in a bookstore, in a cage, he was not able to fly, which is strange, but he was able to open the lock - it helps a lot to escape. Finally, Blue rescued all of those birds and learned how to fly and finally, lived a happy life with his wife and children.

This reminds me of that I have ever owned an owl but unfortunately it died of  drowning - it wanted some water in a certain night so it went to the tank which was occupied by a big turtle. I did not what happened but in the next morning, I found it dead in the water..... What a pity!

Osmoregulation teaching.

So glad that after a teaching period from 1:30pm to 9:30pm, I was rewarded a comment that "Our TA is cool, much better than the previous one which is so boring". I do not know who is the previous one but I was so glad to hear about a comment like that.

Yesterday, we learned how to use a microscope, observed prepared slides and made some fresh slides demonstrating osmoregulation in living cells. We were supposed to use Neutral Red to make inner epithelium of onions stained visible but it seemed that the dye was dead. So we switched to outer epithelium which was purple in nature. Purple onion cells in 3% NaCl shrunk with some space among cells which were initially tightly connected.

One problem/question I cannot answer is that, why shall we use sucrose solution to activate mitochondria when we stain them with Janus Green B? JG is blue when oxygen is present while pink when oxygen is absent. If we add more sucrose, mitochondria will consume more oxygen which makes the dye turn to pink. However, what we expected is to observe blue mitochondria. According to this logic, sucrose does not help to make mitochondria clear at all.

Department Seminar

Today, David McCauley, an assistant professor of Zoology gave us a talk about his research since he arrived in OU about SoxE gene in lamprey.

His research is the regulation of genetic interactions on the development and evolution of neural crest. Only vertebrates have neuronal crest and the progenitor cells of neuronal crest differentiate through three streams of migration into the embryo, giving rise to cartilage, neurons and muscles.

They modified the existing staining with Alcian Blue into a new technology which works in lamprey to show clearly the structures of branchial arch. With this technique, they defined that the branchial arch in lamprey consist of two types of cartilage, morph I which appear in stacks of flattened cells and skeletal rods and morph II which is made of round cells and less flexible.

He is working on a gene called SoxE which has been proven necessary for the development of branchial arch in zebrafish and Africa clawed frog. With the newly invented technique, they have found the expression of SoxE in lamprey branchial arch. With mopholino (injection of complementary RNA which cannot be recognized and cleaved by endogenous enzymes so as to inhibit the expression of a certain gene) they verified that the loss of SoxE result in developmental defect of branchial arch. Mopholinos targeting different isoforms of SoxE demonstrate that SoxE1 and E2 are required for branchial arch formation and E3 is responsible for morphogenesis of branchial arch. Also, they determined the negative regulation of SoxE on collagen gene, Col2a1. 

Tiger beetle? Not really.

On the early morning of my general test day about half a year ago, I saw this beautiful beetle right outside our lab building. When I was taking pictures for it, boss came up and got excited about it too. Then he told me it might be a tiger beetle. It is so amazing that its back is shining green with blue and red rings on its neck. Even the legs are decorated with blue/purple. It was running so fast that my phone camera cannot follow it up so that is why the beetle in the picture is not in focus. In fact, it is about 2 inches long and 1 inch wide. The whole body is charming shining. I dare not deprive it from the nature so several pictures were the only record about it in my hand.

Later, when I try to confirm its identity, I found that it was too large to be a tiger beetle. Usually, tiger    (top: tigers, bottom: leopards)          beetles are half an inch long and they have big eyes on the head. Also, most of them are of uniform color on back. But look at this guy, it was 2 inches long and colorful on his back. I cannot name it to my knowledge. Just call it leopard beetle for now because I think leopards is much more pretty than tigers!

Nucleic acid, proteins and enzymes (2).

Enzyme can be proteins or nucleic acids but mostly proteins. When protein enzymes are folded properly, their catalytic core will be collected together internally so as to make an isolated space for the contact between enzymes and substrates. Enzymes do not change during catalytic reaction but lower the energy threshold required for a reaction to happen. They make it by closing the distance between substrates.

The ability to hold substrates come from non-covalent bonds including hydrogen bonds,  electrostatic, and van der waals force. When the hydrophobic resides on an enzyme are held together, they form a catalytic core attacking one of the chemical bonds in the substrate and temporarily connected to the 'new' substrate to make it stable. Later, the enzyme will transfer this active bond to the other site, on the same substrate or other substrates and then release the new synthesized particles. By then, a reaction is catalyzed.

Nucleic acid, proteins and enzymes (1).

Nucleic acid consists of nucleotides. Each of nucleotides has three parts: triphosphate, ribose and base. They work as the backbone of nucleic acids, energy carrier (ATP) and signaling transducer (cAMP). There are four different bases so that there are four different nucleotides for DNA and RNA each. However, those four bases are primary types and there exist other types of nucleotides.

Proteins are made of amino acids which are connected by peptide bonds, which are covalent bonds. Based on the polarity of R group on each of them, amino acids are grouped into polar, non-polar, basic and acidic amino acids. Non-polar amino acids are hydrophilic so when they get gathered in a protein, they tend to fold into the internal part of a protein by hydrorepulsion. This property is important for some protein functions such as the transmembrane helix and sheet of protein have to be made up of primarily hydrophilic amino acids so they can stay stable in the phospholipid membrane. Also, this is extremely important for the function of an enzyme.