Good morning everyone,
In our lab this term, we have talked numerous times about the 'central dogma of information flow', the idea that information encoded in DNA is used during the process of transcription to make RNA, which itself is used during translation to make protein. This concept is part of the 'one gene, one protein' idea, that each gene encodes information to make a single type of protein.
During our discussions, we've also used estimates of the number of genes that we possess (perhaps 25,000), and our most recent lab included discussion of how effective any single one of them may be in influencing phenotype. Most individual genes are likely to have little or no obvious effects on phenotype, while some 'master regulator' genes, or other single genes that are responsible for the production of a key molecule in a cell, may exert more-pronounced effects.
In the news this week comes description of one such gene (gene FAAH, so called), which had been identified previously but whose function was unknown. It is now known that it is a crucial player in mammalian pain perception, for a woman has been described who has led a 'pain-free' life, and who has a genetic mutation in this one gene. Interestingly, this mutation also influences mood - she is described as never feeling anxiety as well.
While pain is unpleasant, do not wish for none of it, for it is a useful 'warning system' that alerts us to tissue damage. There have been others described who 'feel no pain', and their existence is pretty awful, for they experience injury after injury (many of them self-inflicted). Much of their story was described in a superb documentary from a few years ago, entitled A Life Without Pain - if you are interested in the topic, it is very worthwhile.
The subject in this most recent report is mostly, but not entirely pain-free, so her life is mostly normal. But, her case illustrates well the potential power of individual genes. They need not always be 'master regulators' to have individually-profound effects. Sometimes, being just a single link in an important chain is crucial.
Have a great weekend -
A bad bout of flu triggers 'taste bud cells' to grow in the lungs -- Science Daily
Good morning all,
As we slip slowly into Spring, it's easy to forget that we still are within flu (influenza) season. We should also remember that the latter half of flu season this year is characterized by a more-virulent flu strain than was common during the first half of this year's flu season, which explains why reports of flu-like illness have risen in recent weeks.
Seasonal flu is caused by influenza virus, whose make-up changes from one season to the next as well as over the course of an individual flu season - this is one of the reasons that 'flu shots' (vaccinations against the influenza virus) are recommended every year. Normally, last year's flu vaccine won't protect us this year, and sometimes the vaccine works very poorly altogether.
For most of us, flu is a passing annoyance, but influenza can be deadly - 10,000 people have died from the flu in this country during flu season this year. Last year's flu was particularly deadly, causing 80,000 deaths in the U.S. Most are caused by respiratory failure.
Influenza virus infects our respiratory mucosa (the linings of our respiratory tracts), triggering inflammation and cell death. Much research is aimed at determining how our immune systems detect the virus and attempt to prevent its effects, and new research out this week suggests a surprising tool: taste receptor-like cells, known as tuft cells. They had long been known to exist, but their function was never clear.
This new research shows that tuft cells in our respiratory tract and lungs proliferate and trigger immune responses when virus is detected. Interestingly, they can be promoted across much of the body - including our respiratory tract, out intestines, even our bladder. After infection from flu virus, they appear to remain activated and cause sustained inflammation, which can trigger long-tern allergies and tissue remodeling. Inflammation is a very useful part of our immune function, but it can also provide unnecessary side-effects (allergies, anyone?) and tissue damage if pronounced.
Fortunately, the best defense against the flu is easy: cover your coughs and sneezes, and wash your hands! Otherwise, prepare for your tuft cells to 'Spring' into action (pun intended).
Have a great weekend -
Chop Up a Worm. It Will Regenerate. Scientists Figured Out Why. - The New York Times
As we conclude our regeneration experiment this week, a new study comes along that suggests that part of the regeneration process is regulated by 'master genes', a concept that we explored earlier during our discussion of 'snake genes and human spines'. While our recent evaluation of regeneration focused upon stem cells, remember that it is the genes that these cells express that ultimately determines their cellular fate. This new study suggests that one particular gene EGR ("early growth response") is necessary for regeneration to occur.
This new study showed that EGR activation is necessary for regeneration in the marine three-banded panther worm (very similar to the planaria we used in our lab). While much remains to investigate regarding EGR and its function, the authors do note that humans also possess this same gene, and that it is known to be activated by injury. So, these studies performed in tiny flatworms are very relevant to us. And, once again, the topics we explore in lab remain at the forefront of genetic science. Very cool, I think!
Have a great weekend -
Here’s Why a 50-Degree Day Feels Colder in Fall Than in Spring - The New York Times
As we (hopefully? finally?) transition from winter into spring, we find that we enjoy even slightly warmer days than we have been experiencing, even if the same temperature is enjoyed less at other times of the year (for example, as autumn cools into winter). Why should a 50 °F day be perceived differently, at different times of the year?
Part of the answer has always been assumed to be psychological: we evaluate new conditions relative to what we have recently experienced, and warmer days in the spring are enjoyed relative to the recent, cooler temperature of winter. Increasingly, however, evidence is growing that suggests a physiological component, based on relatively gradual acclimation to prevailing temperatures over a longer term (weeks, months, or longer).
These data suggest that long-term physiological responses to temperature gradually shape our vasoconstriction and blood delivery to the surface (you knew there was a link to our current lecture topics!), as well as our sensitivity and tolerance to temperatures below and above our 'comfort zone'. This is part of a systemic response: our peripheral blood delivery is altered, our sensory systems modulate their responsiveness to temperature, and our minds reduce expectations of a quick change back to more moderate temperatures (which reduces disappoint when temperatures remain extreme).
So, the next time you are enjoying a bit of sunshine on a brisk Spring day, remember that the pleasure of it is not 'all in your head' - some of it is in your skin, and your arterioles, and your hypothalamus, and your skeletal muscles, ....
Happy Spring -
Exercise vs. Drugs to Treat High Blood Pressure and Reduce Fat - The New York Times
Good morning all,
I hope that you have had an excellent Break, and are ready for the second half of our term!
We will begin our third unit of the semester with consideration of the cardiac and pulmonary systems. There is much in our upcoming chapters that will be familiar (we all have some inherent understanding of how these systems function) and important (cardiovascular pathology is a leading contributor to human morbidity and mortality). Health science research and news is dominated by several major fields, including cancer, infectious disease, and cardiopulmonary health, for they are at the forefront of what ails us.
One critical feature of our cardiac and pulmonary function is its malleability - we have real power to change how these systems perform, through our habits. Lack of exercise and poor lifestyle choices (in terms of diet, tobacco use, alcohol/drugs) plague too many of us, and a large component of the pharmaceutical industry is geared toward making medications that influence our cardiovascular and pulmonary health. But, we already hold the power to improve our condition, through exercise. Exertion is a form of physiological stress, and (within reason), it is a useful stress - our tissues respond to extra use with improved effectiveness. But, the temptation to simply 'pop a pill', or the lack of available time for exercise, makes it difficult for most of us to meet fitness goals (such as 150 min of moderate exercise per week).
Are these options equivalent? Here's a link to a recent study that makes this type of comparison: are medications or exercise better for treating/managing high blood pressure and body fat stores?
This study reports benefits from both medications and from exercise, and highlights some of the difficulties in making these comparisons (such as ensuring equivalent samples, and quantifying exercise uniformly). They also note that exercise is more easily accessible - no appointments or prescriptions are necessary (although anyone beginning a new exercise program is advised to seek medical consult, first).
Remember, though, that there are health benefits to exercise that extend beyond individual physiological systems, and that many of the benefits are somewhat intangible (improved mood, improved decision-making, social benefits). Studies like this are good reminders that we too easily forget the power of exercise, and the power we already hold to improve our own health.
Perhaps Nike put it best in their advertisements from a few years ago: just do it.
See you on Tuesday -
Good morning all,
I'm sure that you have heard recent news about gene editing that was performed on two human embryos by a Chinese scientist, in an attempt to introduce resistance to HIV infection. His efforts only came to light after the children were born, and have been roundly criticized as 'crossing the bridge too soon' - there seems to have been little or no oversight of his work, and most geneticists agree that it is too early for us to consider human genome editing, before we better understand the risks, and the opportunities, it poses.
But, calls for a moratorium on this type of work are not universal - some believe that the time is now to proceed, and that the potential risks of waiting are greater than the potential for doing harm. Others say that this is simply scientific progress - messy, risky, but in the end, advancing our knowledge and capabilities. That this debate is prominent in the science literature is a sign that this is truly the cutting-edge of research and its application. I'm sure that we haven't heard the last on this issue, and I also am sure that in your lifetimes there will be increasing opportunity to perform exactly this kind of genome editing.
Think about children you might have in the future - would you edit their genomes to improve their health? Or to make them smarter? Or kinder? What if you could only choose one of these characteristics? What if improving one caused reductions in another? There is still much to learn, and much to discuss...
Hope that you all have had a great Break, and are ready for the second half of our semester! I have been taking care of our planaria, and they are almost ready for your evaluation.
Travel safely back to campus - see you on Wednesday.
Good morning everyone,
As I scan the science news each day, I often read articles that are interesting, and potentially useful. Less frequently do I encounter news reports that make me say 'wow!". Here is a link to a news report about a recent study that did, for it potentially changes something that has been fixed for perhaps a billion years.
You've heard much about DNA in your lecture and our lab, and you know the basics of its structure: two twisted strands of a sugar-phosphate backbone, with paired nucleotides along their length. You also know that the nucleotides in use are four only (A, C, G, and T) and that they pair in only two possibilities (A-T, C-G).
Recently, scientists have created synthetic DNA molecules that have not four, but eight different nucleotides (by adding synthetic nucleotides Z, P, S, and B).
There are LOTS of potential implications from this - from the spread of artificial DNA, to the possibility of new life forms, and the potential therapeutic uses of new forms of DNA. One of the more intriguing possibilities is the expanded possibility for use of DNA as a storage molecule. Computer scientists and bioengineers have long been testing methods for using DNA as a way to store digital information (after all, evolution has refined DNA structure/function for a long time, to the point at which it is highly efficient and reliable). Having additional base pairs is akin to adding letters to our alphabet - it makes the number of words or combinations of bases much, much greater, and it dramatically raises the density of data which could be stored by a molecule of DNA..
There are lots of details to work out, but this is a scientific breakthrough that will be a top contender for 'science advance of the year', if not the decade - and you can say that you are well-informed about it!
Hope that your Break is a good one!
Good morning everyone,
In our recent chapters, we have been considering aspects of nervous system structure and function. During our discussions, we noted that the cerebral cortex of the forebrain is responsible for our "higher" functions, including emotion, reasoning, and planning. Many would argue that these are uniquely human, or at least developed to a higher degree in humans than in any other animal.
Chief among these "higher" functions is that of consciousness. Consciousness has been described as a form of "meta-awareness" (literally, being aware that we are aware). While there are many aspects of neural function that we still do not understand, the neural basis for consciousness is generally agreed to be the most challenging. In fact, consciousness is often described as "the hard problem" of neuroscience, which is a way of saying that it is so poorly understood that we do not really know even how to begin study of it, let alone explanation of it.
As our tools and our thinking are refined, however, more and more investigators are willing to study consciousness. In doing so, they often invoke aid from philosophers and psychologists, for not only is consciousness the ultimate emergent property, it cannot be isolated from itself - we are consciously trying to study consciousness, and that has significant implications for our approaches and our interpretations.
I'm passing along here a link to a recent news article describing (perhaps) a new way of thinking about consciousness, and the study of it. It describes the work of a number of the most prominent neuroscientists working today (including Giulio Tononi, Cristof Koch, and Stanislas Dehaene). This article describes some of the modern techniques used to study consciousness, and also presents some specific models for how consciousness may occur. In doing so, it also offers some specific predictions that might be tested, which will allow us to evaluate which models may, or may not, be plausible.
If you are interested in the "brain-mind" problem, as it is called, you might enjoy this article.
Hope that your Break is a good one!
Good morning all,
As I scan the science news each day, I often read articles that are interesting, and potentially useful. Less frequently do I encounter news reports that make me say 'wow!". Here is one that did.
You will recall from our sensory systems chapter that the photoreceptors in our eyes exist in several forms, and that each form is able to interact with light of some defined frequency range. Together, they give us our vision in the range of light frequencies known as "visual light". Many other organisms can detect light frequencies outside of our visual range, including infrared and ultraviolet.
This news report describes a recent advance that marries technology and neuroscience (two of my favorite topics). Here, scientists have developed molecules that act as intermediates between the light entering the eye and the light striking the photoreceptors. These molecules harvest light of one frequency, and emit it at another (the phenomenon of fluorescence). In this case, they have been designed to harvest a light frequency normally unavailable to us (and to mice), and to then emit it at a frequency to which our photoreceptors are sensitive. The effect is to allow vision under light frequencies which are not normally useful to us.
As the article notes, these experiments only have been performed in mice, to date. But, you can be sure that human applications are coming. I think that they will have to build-in some sort of kill-switch, first - a way to get rid of the molecules should they prove problematic. My guess is that they are already working on it...
Have a great rest of the weekend -
In science education, we like to categorize - things are either "this way", or "that way". Simplifying the variety and pointing out the differences is a proven way to aid understanding, and "boiling things down" to their general features is usually also scientifically accurate - except when it isn't.
In our labs this term, we have talked about meiosis and chromosomes, how chromosomes are paired to give us our genotype, how genotype determines what gametes can be passed on, and how our alleles direct our phenotype. Much of those discussions, as is typical, are of a 'this-of-that' format - we either have this genotype or that one, this phenotype or that one. But exceptions to these general rules are interesting, and often enlightening.
Several weeks ago I sent you a news story about a bird that was spotted in Erie, PA that appeared to be a gynandromorph - a genetic mosaic of both male and female tissues. Gynandromorphs are rare, and form when something other than the normal pattern of gamete combinations, chromosome sorting, and cell division occurs during early embryonic formation.
This week, there is news of another, even rarer genetic variant, this time in humans: a semi-identical pair of twins. You are already familiar with identical twins, which form when a fertilized zygote splits into two genetically-equal cells that develop into separate individuals. Identical twins share 100% of their DNA.
You also know about fraternal twins, formed when two (separate) fertilized eggs, rather than one, develop at the same time. Fraternal twins share 50% of their DNA (on average), just like any two siblings born at different times from the same parents.
In this, case we have something different. Semi-identical (sesquizygotic) twins form when a single female egg is fertilized by not one, but two, male sperm. This early embryo divides and begins to develop into not one fetus, but two fetuses. These fetuses develop at the same time and are born as twins. In this case, though, they are predicted to share 75% of their DNA, because they share 100% of their mother's DNA and only 50% (on average) of their fathers DNA, which together average 75%. In the case reported here, the twins share a slightly higher value (89%).
It is likely that this unusual pattern of fertilization actually happens with some frequency, but that the early embryos do not typically survive. This chance occurrence will give geneticists a new data point in their ability to test hypotheses of genes and relatedness - no longer are all twins in their databases either 50% or 100% related, now there is a known 3rd possibility.
Have a great weekend -