Could Offspring Inherit Acquired Traits?

ABSTRACT

A team of researchers lead by Larry Feig has recently found evidence suggesting that certain acquired traits could be passed down to offspring. If it is true, the implications for our understanding of genetics are notable.

 

METHODS AND RESULTS

Feig and his colleagues bred “knock-out” mice, which due to a genetic defect lack ras-GRF proteins, which play a key role in Long Term Potentiation. When placed in a shock chamber, knock-out mice are unable to associate the shock with the cage, and do not learn to fear the cage itself like normal mice. However, many experiments have shown that they can overcome this memory deficiency if they are exposed to an Enriched Environment as juveniles. This includes stimulatory objects, enhanced social interactions, and opportunities for exercise. Enriched Environments unlock a camp/p38-dependent signaling cascade that enhances Long Term Potentiation. Knock-out mice reared in an Enriched Environment respond to the shock chamber normally, contextualizing their fear and showing increased freezing responses whenever in the cage, not just after a shock.

 

Feig’s team wanted to know if the mice’s ability to overcome their genetic defect could be passed down to offspring. They bred mice lacking ras-GRF to test the theory. They found that the offspring of Enriched knock-out mice responded normally to the shock chamber, and had increased Long Term Potentiation. To assure the effect wasn’t environmental, the mice were raised by a foster mother in an un-enriched environment. These mice were still able to overcome their genetic deficiency, proving that the enhanced Long Term Potentiation wasn’t learned.

 

This effect was only seen over one generation (grandchildren did not also inherit the “rescued” memory) and was only carried by the mother. Enriched male knock-out mice did not produce offspring that could overcome their lack of ras-GRF without enrichment.

 

As of yet, Feig’s team does not know how this happens. No mechanism in our understanding of modern genetics allows for this.

 

IMPLICATIONS

If this effect is as it appears, and traits acquired in a mother’s life before conception are being passed on to offspring, the implications for the field of genetics are staggering. It contradicts what we currently know about genetic inheritance.

 

MENDELIAN GENETICS

Our current understanding of genetics is based on the work of Gregor Mendel, a monk who studied pea traits in the 19^th century. Through studying characteristics like flower color and seed shape, he was able to see that certain traits were dominant or recessive, (later learned to be expressed by genes) and they occur in pairs in organisms. However, when organisms reproduce, the genes split and unite, competing or combining to express a phenotype. Most work in this field is based upon Mendelian theories. Mendelian genetics provided the mechanism for Darwinian evolution, combining to create the contemporary theory of evolution, i.e. traits that are successful result in more offspring for the successful organism, leading to even more expression of the successful gene, leading to eventual adaptation and evolution. Only genes are expressed in an offspring. If a woman was burned by acid, her child will not be born with burns as well, because the burns were acquired in her life, they are not part of her DNA.

 

LAMARCKIAN GENETICS

Before Mendel, our understanding of trait inheritance was based on a Naturalist named Jean-Baptiste Lamarck. He believed that adaptations in animals were based on acquired traits that were passed on to offspring. A giraffe, for example, would have started with a relatively short neck, but would stretch itself to reach a higher branch. When the giraffe had a baby, that giraffe would be born with its mother’s longer neck and would in turn stretch itself a little longer to reach even higher branches, giving birth to an offspring with an even longer neck. This process would continue until what we now know as a giraffe was born.

CONCLUSION

Feig’s findings suggest that genetics may have a Lamarckian component, with acquired traits able to overcome our model of genetic inheritance and express themselves in a first generation offspring. Given that the mechanism for this phenomenon is unknown, it is quite possible that there is a perfectly reasonable explanation for this occurrence, but there is a small possibility that genetic inheritance as we know it is flawed. Granted, I strongly believe that is NOT the case, but if it is, not only would the field of genetics have to be completely rethought, but also its dependent fields such as evolutionary biology and the study of genetic diseases would need a major overhaul.

What Do Your Dreams Reveal About You?

Overview
To what extent are our judgments and behaviors affected by what we dream? This question of whether or not dreams affect daily life is one that haunts most of us regularly. We wonder if dreams have specific hidden meanings and if we should truly believe them and/or take action that respond to their content. Is there any way we can learn more about ourselves from what we dream? Carey K. Morewedge of Carnegie Mellon Univesity and Michael I. Norton of Harvard University have done a series of studies that try to answer these questions of the significance our dreams may hold. They argue that we all interpret our dreams with motivated intention that reflects our waking life, as opposed to waking life being a reflection of our dreams.


Why We Believe
There are many people who try to interpret their dreams constantly and try to gather meaning from them. In fact, most of us love to dwell on what we dreamt the night before and try to figure out how it corresponds to our daily lives. So, why is it so natural for us as humans to try to find meaning in our dreams? Morewedge and Norton claim that:
1) Dreams occur at random and are then questioned as to why they appeared
2) There is no correction process for our dreams as opposed to our waking thoughts
3) We use it as evidence for our previous judgments

Psychologically…
Because dreams occur seemingly “out of the blue,” we see it almost as divine-intervention. People want validation for their thoughts and behavior and will blame it on anything they can use. If dreams come out of nowhere, they are game to any type of interpretation. There is also the assumption of “why would I have a thought if it was not meaningful?” Dreams also seem immune to any sort of influence from the outside world and are seen as pure versions of our thoughts.

External vs. Internal
Externally generated thoughts are seen as less meaningful as opposed to thoughts that are generated internally. If you are irritated by something, you are more likely to give it any sort of emotional weight if it appears to come from within. If you are aware of the external source causing irritation, you are less likely to change your behavior and judgment. Due to these internal sources, a dream is more likely to be interpreted because there is no external source to trace back to. The dreamer has some access to the dream even though the link itself is ambiguous. The less able people are to attribute thoughts to external sources, the more likely they are to interpret. Another way to think of it is that dreams are almost as easy to dismiss as to consider “a sign from God.”

Studies
1) They surveyed various populations to see who believed if dreams revealed hidden truths. The three groups tested were portions of the U.S., Korea and India. The majority in all three believed Freud’s theory about dreams having hidden meaning (56% for Americans, 64% for Koreans and 73% for Indians). Freud’s theory was preferred to: a dream’s role in problem solving, being a byproduct of sensory input and lastly their ability to throw out useless information for improved learning (in that order throughout the cultures).

2) 4 scenarios were given to the tested individuals about a plane crash (a dream, actual knowledge of a plane crash, homeland security issuing an increased alert and finally, simply the thought of a crash). A dream of a plane crash would affect the majority of the population to change their travel plans over even the knowledge of an actual crash.
3) How much people believe their dreams has to do with whether or not they believe Freud’s theory.
4) Dreams about a friend or an enemy: Results derived from previous experiences; pleasant dreams about friends were more meaningful and the same with unpleasant dreams about enemies. No other order held much significance. There was also a posttest done having to do with whether there was a pattern of motivated recollection of dreams. There did not appear to be one.

5) A hypothetical dream featuring a friend kissing the tested individual's significant other. Result was that the dream in which the friend cheats is less meaningful and the dream where that friend defends is seen as more meaningful.
6) God speaks in a dream and makes a request to for the person travel the world or work in a leper colony. The two categories tested were “believers” and “agnostics." Believers saw the dream as more meaningful while the agnostics did not attribute much meaning to it at all.

Conclusions
What people derive from their dreams almost always coincide with what they already believe in daily life. These dreams do affect one’s judgment and behavior but only because it can be used to blame pre-existing thoughts during waking life. The issue of self-preservation seems to play a large part in dreams and how people react to them. The idea of thought interpretation needs to be researched more due to people’s tendency to attribute as much meaning to random thoughts as a long process of focused attention. There is also an element of exerting a type of control in dreams by whatever one chooses to interpret being the force behind an action.

However They Do Provide Some Insight
Just not into the future. People’s concerns, fears and causes of stress can very much show up in their dreams or nightmares. The content provides insight, but it’s not exactly hidden. Dreams can also create self-fulfilling prophecies with people who believe their dreams so intensely and act upon them.

But who knows…

Reference Article
1. Morewedge, C & Norton M. (February 2009). When Dreaming Is Believing: The (Motivated) Interpretation of Dreams. Journal of Personality and Social Psychology, Vol. 96, No. 2, pp. 249-264.

Article on inheritance of acquired traits: REDUX!

Hey, all! This article may look familiar to some of you, as it is the same one I was supposed to present on in February. However, due to illness, my presentation was rescheduled for Thursday. Comment again, if you so please, they help me a lot! Thanks!

http://www.newscientist.com/article/mg20126945.100-can-experiences-be-passed-on-to-offspring.html

-Katie B

Do You Believe Your Dreams? Probably.

Here's the article:
http://www.sciencedaily.com/releases/2009/02/090217125544.htm

Schizophrenia and Autism as Diametrically Opposed Disorders Determined by a Genetic Tug of War

Introduction
Autism and Schizophrenia are intensely studied disorders, and many hypothesis exist theorizing environmental and genetic causes. Bernard Crespi and Christopher Badcock recently developed a theory that could not only provide insight into what causes these two disorders but also could connect the two in an illuminating way. The basis of their theory is made of two parts.
1) That Autism and Schizophrenia are diametrically related disorders.
2) That a tug of war between maternal and paternal genes can lead to the expression of either disorder in their offspring.

This is a deeply controversial explanation both because it is a large overriding explanation of such a huge range of mental conditions and also because gender assumptions underlie the genetic part of the theory.

Autism and Schizophrenia as Diametrically Opposed

“The core of this hypothesis is that psychosis and autism represent two extremes on a cognitive spectrum with normality at its center (Crespi, 2008).”

Autism is characterized by impairments in social interaction. Generally this is characterized by some combination of deficits in language and communication, and repetitive and restricted behaviors and interests. Autistic behavior tends to be more self-oriented or selfish than normal behavior. Often autistic individuals are mechanistic focused as opposed to mentalistic, Meaning they are concerned with their physical environment as opposed to social interaction. Brain size and head size is generally larger with a notable increase in cortical thickness. The hippocampus is larger which may be related to the cause of the enhanced visual-spatial, mathematic and mechanistic aspects of some autistic cognition. The amygdala is highly activated when humans gaze upon one another, and when they perceive emotion given off from the eyes and surrounding face. It is especially sensitive to fear. Autistic individuals tend to have larger amygdalas as well as lower levels of oxytocin.



Schizophrenic behavior is grouped into either positive or negative symptoms. Positive symptoms are hyper-sensitivity or awareness to the outside world, for example the development of hallucinations or delusions. Negative symptoms are loss of will, flat affect and psychomotor retardation. Whole brain size is smaller in schizophrenia with reductions in grey matter, white matter and lower cortical thickness. The hippocampus is smaller in size and altered in shape which could contribute to symptoms like paranoia and delusions because it is responsible for updating and creating one’s social and spatial worldviews and coordinates its communication with the amygdala. The amygdala is smaller and seemingly underdeveloped, possibly leading to their notable over-responsiveness to gaze and misunderstanding of gaze ie paranoia.

Badcock and Crespi concluded that the characteristic symptoms of autism and schizophrenia are opposite, where autism is generally more inward, schizophrenia tends to be an exaggerated concern with the outside world resulting in paranoia.


The Case for Imprinting and Maternal and Paternal Genes Are Involved

Some genes are expressed when inherited from one parent but not when inherited from the other. “This is achieved through a process called imprinting, in which genes in the sperm and egg are marked for expression or silencing in a later embryo and child (Badcock, Crespi, Battle of the Sexes May Set the Brain, 2008).”
Imprinted genes have the most far-reaching effects on growth and development, and imprinting is “also common among genes that drive brain development (Badcock, Crespi Battle of the Sexes May Set the Brain, 2008),”

Asperger viewed autism as an extreme variant of male intelligence. This idea stemmed from the view that autistics had difficulty empathizing, and socializing as well as a high capacity for order and systematizing rules governing objects. This was also consistent with the higher number of male autistics as well as increased empathy, emotional and language development in girls.

In schizophrenia Crespi and Badcock viewed negative symptoms as less influenced by the paternal brain and relatively unaffected by the maternal brain. Positive symptoms, on the other hand, are more a consequence of the maternal brain as they are hyper-mentalistic outputs to the limbic system, creating fear or paranoia.

Prader-Willi and Angelman Syndromes As Evidence

These two syndromes provide a great piece of evidence for Crespi and Badcock’s theory, because they result from opposite disruptions on a strand of imprinted genes on chromosome 15. Scientists know that Prader-Willi syndrome is from an increase in maternal gene expression, while Angelman syndrome occurs when there is an imbalance towards less maternal gene expression. Prader-Willi is characterized by low birth weight and a high incidence of psychosis in adulthood. Angelman is characterized by autistic-like behavior: non-reciprocal social behavior, poor eye contact, and repetitive behaviors.


Crespi and Badcock concluded that the correlation between psychosis in Prader-Willi syndrome and autistic behavior in Angelman syndrome supports a diametric relation between imprinted genes and a connection between maternal and paternal gene expression.

Beckwith-Wiedemann and Silver-Russell Syndrome as More Evidence


Crespi and Badcock thought that these syndromes would act almost as sister syndromes to Prader-Willi and Angelman. The data is a little less clear. A gene called IGF2, which controls growth is normally only expressed from one’s father. Paternal gene expression bias creates Beckwith-Wiedemann syndrome. Normally the child’s birth weight is more than 50% above normal, and has a greatly elevated risk of autism. Maternal gene expression causes Silver-Russell syndrome shows lower weight and higher incidence of psychosis. I should note that I found less definitive data on these two syndromes.

Conclusions

Crespi and Badcock concluded that based on the research about autism and schizophrenia one can see their diametrically opposed features. In each comparison between the above syndromes, Crespi and Badcock noted that there was a connection between autism and paternal gene expression as well as psychosis and maternal gene expression. Ultimately they supported their hypothesis based on these relationships. Their theory opens up a new way to examine autism and schizophrenia, and although Crespi and Badcock have compelling evidence there is still much research to be done to either confirm or contradict their findings. It is another valuable part of the quest to better understand the origins of these two disorders.

Bibliography

1. Badcock, C. &. Crespi, B.(2008, August 28). Battle of the Sexes May Set the Brain. Nature , 454, pp. 1054-1055.
2. Badcock, C. (2008). Nature or Nurture? Genes or Society? Autism or Psychosis? A New Theory Resolves Some Long-Standing Contradictions in Explaining Mental Illness. Sociology Research News , 5 (3), 2-4.
3. Carey, B. (2008, November 11). In a Novel Theory of Mental Disorders, Parents' Genes Are in Competition. New York Times .
4. Crespi, B. &. Badcock, C. (2008). Psychosis and Autism as Diametrical Disorders of the Social Brain. Behavioral and Brain Sciences , 31, 241-320.

The Incredible Erasable Mind

The idea of erasing one's memory has been around for a while. It plays a prominent role in science fiction literature and movies, like Men in Black and The Eternal Sunshine of the Spotless Mind. And until now, it has remained in the fictional realm. Recently, however, a team of scientists at the Department of Psychology and Gene Research Center in Brooklyn, New York discovered that the fiction that we read and watch is getting closer and closer to the truth.

What They Knew

The team of scientists - including those that were quoted in the NY Times article, Todd Sacktor and Andre Fenton - set out to determine several things, using previously gathered information. Firstly, they knew about the existence of protein kinase C (PKMzeta). PKMzeta is an autonomously active protein enzyme that is known to store unpleasant memories. This enzyme was discovered when a PKMzeta-inhibitor was injected in to a rat's brain, and the rat promptly forgot it's "unpleasant" memory.

How PKMzeta Works:

PKMzeta is necessary for the continuation of induced long-term potentiation in synaptic transmission. We already know how a synaptic transmission works. Long term potentiation is a state of increased sensitivity that's triggered when a synapse is stimulated. PKMzetas interfere by gathering themselves in to the receiving end of a synapse, which further increases sensitivity. 

PKMzeta-Inhibitor:

The scientists used two PKMzeta-Inhibitors for the experiment: zeta inhibitory peptide (ZIP) and Chelerythrine.  Chelerythrine and ZIP are cell-permeable PKMzeta-inhibitors. They reverse synaptic potentiation in the hippocampus when applied up to 1 day after long term potentiation is induced, essentially stopping the long term potentiation.

What They're Asking

The scientists were curious about how selective PKMzeta was when storing memories. Were all forms of memory and information in the brain stored by PKMzeta?

The Experiment

Equipped with Chelerythrine, ZIP, a harmless saline solution, several rats, and platform at which one end a shock was received by the rats, they were ready to see how important PKMzeta was when it came to "place avoidance memory", or "spacial memory". 

On the first trial, rats ran to the shock zone within 2 seconds, but after a while, they learned to avoid it. Twenty-two hours later, Chelerythrine was injected in to the dorsal hippocampus of some rats, saline solution in to others, and their retention of the avoidance memory was tested 2 hours after the injection.  

The Result

The graph shows that the naive rats entered the shock zone rapidly, but had learned to avoid the location for several minutes by the 8th training trial. As soon as Chelerythrine was injected into the dorsal hippocampi, the retention of the place avoidance memory was essentially erased, causing avoidance of the shock zone to drop to the level of a naive rat. During the long term memory retention trial it was discovered that the rats still showed no signs of recognizing the shock zone. However, after a single training trial, they began to avoid the shock zone. The same trial was performed using ZIP, with almost identical results. 

This told the scientists that ZIP and Chelerythrine are interchangeable PKMzeta-inhibitors. They also learned that neither PKMzeta-inhibitor permanently disabled the rat's ability to store memories. Finally, they successfully determined that PKMzeta is directly involved in spatial memory.

The scientists conducted other experiments, testing the relationship between PKM-zeta and Classically Conditioned Fear Memory using shock tests and Instrumentally Conditioned Memory using a dark compartment. Having determined the similarity between Chelerythrine and ZIP, they continued their experiments using only ZIP, this time injecting it in to either the basolateral amygdala or the dorsal hippocampus. Through all their tests, they found that specific inhibition of PKMzeta impaired the retention of accurate associations in different brain regions, regardless of positive or negative reinforcement, essentially erasing specific memories. This revealed to them that PKMzeta is a general molecular mechanism for memory. They also determined that the PKMzeta-inhibitors that they used erased the memories without disrupting the function of the region in which it was injected. 

The Ethics Question

The team of scientists say that they are fairly confident that the PKMzeta-inhibitors will translate well from rats to humans. If we had the ability to successfully erase specific memories in a human being, how would we use it? Is it worth having in order to erase the memory of a traumatic event, even if it might end up in the wrong hands? The debate rages on, and I don't think there will ever be an end to it.

Bibliography

1. PKMzeta Maintains Spatial, Instrumental, and Classically Conditioned Long-Term Memories, research article, PloS Biology, Dec. 23, 2008

2. Brain Researchers Open Door to Editing Memory, NY Times, April 6, 2009, Benedict Carey

MHC and another sweaty t-shirt

I have always been interested in scent and how it effect the human mind. Growing up with a father who doesn’t wear deodorant because he doesn’t like how it effects his scent and a grandfather who knows each grandchild by the scent of their hair it is easy to understand why. I first read the article Scent and Sensibility when I was on birth control and it really made me open my eyes…and nose. I knew I wanted to further research this as soon as I was assigned this presentation.


The Study

In 1995 Claus Wedekind created a study that changed the way the world viewed scent and attraction. He choose 44 men and 49 women to participate in the study. The men were instructed to wear a t-shirt for two days without using any kind of scent products. Then Wedekind place the t-shirts in plastic lined boxes with holes in them so the women would be able to smell them properly. The women in the study were scheduled to smell when they were at the middle of their menstrual cycle which is when the nose works the best. Each woman was given seven boxes: three with scents similar to hers, three different, and one control.


The Deciding Factor

The main chemical element in this study and other studies involving scent is a gene called MHC, which stands for Major Histocompatibility Complex. MHC are molecules that control the body’s immune systems response to noticing “self” and “non self”. In Wedekind’s study MHC was what was involved with how the woman chose which partner to pick. Women choose the t-shirt that had MHC most different from their own.

Here’s the catch

The birth control pill has changed women’s abilities to have sex and protect themselves. It is a great step for women kind. But is it doing females good in the long run? In Wedekind’s study he notes that women on the pill were attracted to the t-shirts with scents most similar to their own. He noted that this was due to the pill making the body seem to think that it is already pregnant. In a similar study using t-shirts and MHC, 18 women that were on the pill were tested. Curiously in researching this study it is noted that the women in this study did nothing to enhance their scent abilities. The women in Wedekind’s study used nasal spray to clear their nose and read a book on how to enhance their scent. In the study with women just on the pill it was concluded that they were indeed attracted to men with MHC similar to theirs and this goes against human nature.

One thing to note is that women that have fallen in love online and are on the pill may not be impacted as harshly by its effects on their MHC because their mind will be confused by their emotions.


Conclusion

So maybe your on the pill and planning to get married soon? Should you stay on the pill? As studies show it would be best not to and to wait until your body is back to normal before you crawl into bed with a man whose scent just isn’t up to par.



Bibliography


F. , Douglas. "Histocompatibility." Medical Microbiology 1997-2009 8 Apr 2009.


s., Craig Roberts. " MHC-correlated odor preferences in humans and the use of oral contraceptives." Proceedings of the Royal Society . 08/25/2008. 1 Apr 2009


"Sweaty T-Shirt Study ." Human Thermodynamics 5/28/2008 1 Apr 2009.