Epistasis Blog

From the Computational Genetics Laboratory at the University of Pennsylvania (www.epistasis.org)

Wednesday, September 21, 2005

Epistasis for Fitness-Related Quantitative Traits in Arabidopsis thaliana

Russell Malmberg at the University of Georgia has published a new paper in Genetics on epistasis in Arabidopsis.

Malmberg RL, Held S, Waits A, Mauricio R. Epistasis for Fitness-Related Quantitative Traits in Arabidopsis thaliana Grown in the Field and in the Greenhouse. Genetics. 2005 Sep 12 [PubMed]

Abstract:

The extent to which epistasis contributes to adaptation, population differentiation, and speciation is a long-standing and important problem in evolutionary genetics. Using recombinant inbred lines of Arabidopsis thaliana grown under natural field conditions, we have examined the genetic architecture of fitness-correlated traits with respect to epistasis; we identified both single locus additive and two locus epistatic QTLs for natural variation in fruit number, germination, and seed length and width. For fruit number, we found 7 significant epistatic interactions, but only 2 additive QTLs. For seed germination, length, and width, there were from 2 to 4 additive QTLs and 5-8 epistatic interactions. The epistatic interactions were both positive and negative. In each case, the magnitude of the epistatic effects were roughly double those of the effects of the additive QTLS, varying from -41% to +29% for fruit number, and from -5% to +4% for seed germination, length, and width. A number of the QTLs we describe participate in more than one epistatic interaction, and some loci identified as additive also may participate in an epistatic interaction; the genetic architecture for fitness traits may be a network of additive and epistatic effects. We compared the map positions of the additive and epistatic QTLs for germination, seed width, and seed length from plants grown in both the field and greenhouse. While the total number of significant additive and epistatic QTLs was similar between the two growth conditions, the map locations were largely different. We found a small number of significant epistatic QTL x environment effects when we tested directly for them. Our results support the idea that epistatic interactions are an important part of natural genetic variation, and reinforce the need for caution in comparing results from greenhouse-grown and field-grown plants.

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At 5:28 AM, Blogger cylon said...

A typical dictionary definition of hypnosis states that it is: a state that resembles sleep but that is induced by suggestion. However, anyone who has tried hypnosis (and any self respecting hypnotist) will tell you that this is a very simplistic view of the subject!
A much better description comes from the Free Online Dictionary which states that hypnosis is: an artificially induced state of consciousness, characterised by heightened suggestibility and receptivity to direction. So what does this mean and how can it be used to your advantage?

Well, the subject of hypnosis has been discussed and pondered since the late 1700s. Many explanations and theories have come and gone though science, however, has yet to supply a valid and well-established definition of how it actually happens. It's fairly unlikely that the scientific community will arrive at a definitive explanation for hypnosis in the near future either, as the untapped resources of our 'mostly' uncharted mind still remain something of a mystery.
However, the general characteristics of hypnosis are well documented. It is a trance state characterized by extreme suggestibility, deep relaxation and heightened imaginative functioning. It's not really like sleep at all, because the subject is alert the whole time. It is most often compared to daydreaming, or the feeling you get when you watch a movie or read a captivating book. You are fully conscious, but you tune out most of the outside world. Your focus is concentrated intensely on the mental processes you are experiencing - if movies didn't provide such disassociation with everyday life and put a person in a very receptive state then they would not be as popular (nor would TV advertising be as effective!). Have you ever stated that a film wasn't great because you just couldn't 'get into it'???
This works very simply; while daydream or watching a movie, an imaginary world becomes almost real to you because it fully engages your emotional responses. Such mental pursuits will on most occasions cause real emotional responses such as fear, sadness or happiness (have you ever cried at a sad movie, felt excited by a future event not yet taken place or shivered at the thought of your worst fear?).
It is widely accepted that these states are all forms of self-hypnosis. If you take this view you can easily see that you go into and out of mild hypnotic states on a daily basis - when driving home from work, washing the dishes, or even listening to a boring conversation. Although these situations produce a mental state that is very receptive to suggestion the most powerful time for self-change occurs in the trance state brought on by intentional relaxation and focusing exercises. This deep hypnosis is often compared to the relaxed mental state between wakefulness and sleep.
In this mental state, people feel uninhibited and relaxed and they release all worries and doubts that normally occupy their mind. A similar experience occurs while you are daydreaming or watching the TV. You become so involved in the onscreen antics

 
At 12:30 AM, Anonymous self said...

Visualization is a tool that has been used for thousands of years by initiates of all the metaphysical schools. Today, it is incorporated into top athlete's daily routines and is used in business affairs frequently. It's use is wide-spread among highly successful people, either consciously or unconsciously, aware of its create power. So if it has stood the test of time and is still being used by high achievers we must come to the conclusion that it works! But has it ever worked for you?

If you answered 'yes' to the above question then you know how powerful this technique can be. If, on the other hand, you gave the more likely answer 'no' then take heart for I am about to reveal to you a sure fire way of reaching your objectives through this mostly misunderstood art.

The trouble with visualization is simple - its in its name!

When studying and contemplating the art of visualization most people have the impression that they must create visual images and make them real or life-like. Many people, in fact the majority, find this almost impossible to do. Even if they can formulate a solid picture of their objective they find it extremely difficult to sustain the image for any length of time. Either the image fades, changes or other intruding thoughts intervene.

This type of visualization is almost impossible to sustain and luckily it is not at all necessary. Why? Because it is in the subconscious mind that your visualization needs to be placed and there is good news. The subconscious mind does not know the difference between an imaginary event and a real one. Your visual image only needs to be a strong visually as any other imagined event. However, that is only half the story.

If all you had to do was just imagine stuff and your world automatically changed to reflect your imaginings this world would be full of chaos (not to mention all those creepy crawly bug-eyed monsters!). Therefore, there are a few more steps to complete before the visualization is passed to the subconscious for manifestation.

Let's try a little experiment. Remember a scene from your past that has a lot of good feelings around it. Any good memory will do, like the first time you heard the words "I love you" from your partner, an amazingly spectacular sunset, a great holiday event or your last birthday. Pick one and remember it. How clear is the image? Can you remember any sounds? What way did you feel? Is there any sense of touch, taste or smell? Identify how your memory works. Is it mostly visual, auditory, kinaesthetic or of a feeling nature?

Now we are going to create an imagined event in our lives that has the same strength and potency as that image. So relax and let's go.

Imagine something that you do everyday, something that you did yesterday, today and will do tomorrow. Let us take the example of waking up tomorrow morning. Don't try to add or take anything away, just think about it and analyse the scene. Is it dark or light? Are you lying next to someone in bed? Do you still feel tired? Has the alarm clock sounded? Are you irritable that you have to get up or full of joy at the dawn of a new day?

You will find that the imagined event is very similar to the memory with probably one key difference - your point of perspective. Is the memory behind you and the future event in front of you? Is one to the left and one to the right? Maybe they are both in front of you or the future seems to move in a clockwise direction. Whatever the perspective the thing to notice is that they are very similar in appearance.

Now imagine doing your future event a week from now, then a month from now, then six months from now. Where are those images placed? Are they moving further away, going clockwise, from left to right? This is your time-line and using it is important in visualization as you will see later.

Ok, let's imagine something that is very unlikely to happen and see where it differs from the last image.

Imagine you are sitting somewhere familiar which is extremely comfortable and relaxing to you. Now imagine that a person you know well comes up to where you are and says "hello". Imagine them telling you that they want to show you a new trick. All of a sudden they have three juggling balls. They throw them in the air and begin to juggle with ease. Then they begin to whistle one of your favourite tunes. You suddenly realize that there is a strong smell of flowers in the room and notice a vase of them just behind the juggler. Imagine laughing loudly at the scene and feeling joyful at the experience. Then the person juggling leans forward stands on leg and puts the other leg outstretched behind them. All the while still juggling and whistling. Then they begin to hop on their leg as a small bird flies over to perch on their head. Once you have the imagined event and stayed with it a few moments just let it fade.

Ok open your eyes. What was the difference between the two images? Can you spot any? Did you use more, less or roughly the same senses in your fantasy event as you did in the future one? Did you see them from different angles? Was the picture bigger in one than the other? Was the sound clearer, the feelings more acute or the smell stronger? Take some time and go back to each scene in your mind. How does the future event differ from the fantasy one? Are you looking at both from a different vantage point? Do you see yourself in the image of one but not the other? Analyse the scenes and see where they differ.

Have you identified how the future event differs from the fantasy one? If you have then its time to make visualization work for you! Take a goal that you have been working on or would like to achieve. Nothing too far-fetched at this point please! Pick something that is possible but at the moment seems a little impractical. Once you have it form a mental image of what it would be like to have, be or do that thing or be in that experience. Remember to form it the same way you do a memory. Give it the same strength visually, in sound, feeling, taste and touch - use your mind in its natural state. All you have to do is imagine the scene.

Ok how does it differ from the scene of waking in the morning? Can you identify the differences in perspective, sound, taste, touch, feelings and what you hear?

Now there will be one other key thing that differs in the images- it is very simple but often overlooked. You know that the future event is going to happen! This is reflected in the way we experience the image. So what we are going to do is fool your subconscious mind into thinking your goal is definitely going to happen by manipulating your goal image!

Once you know what the differences are in each image begin to change the goal image so that it is seen the same way as the future event in your imagination. Place the visualized scene in exactly the same position with the same perspective as your future event.

Place it in the correct position on your time-line. You may already begin to feel that the goal is more possible. Visualise in this way everyday and you will condition your subconscious mind to manifest the experiences necessary to make your goal attainment certain.

One more thing to remember: During the day think about your goal often. This reinforces the visualization and will begin to dispel doubt from your mind. hypnosis

 
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