human genome

how does the human genome compare to that of a worm or a fruit fly?


"The relevance of the fruit fly to the human genome project reflects the remarkable conservation among genes in different animals. The fly genome, which was sequenced in the year 2001, is 165 million base pairs in length (spread over four chromosomes) and contains approximately 14 000 genes.

The human genome contains 3-4 times as many genes but most of these are thought to have arisen by two rounds of genome doubling during the evolution of vertebrates. Therefore, humans have more genes than flies but about the same number of gene families. Since it is easy to create mutants and carry out experiments on fruit flies, the functions of many fly genes have been established.

The relationship between fly and human genes is so close that the sequences of newly discovered human genes, including disease genes, can often be matched against their fly counterparts. This provides a lead towards the function of the human gene and could help in the development of effective drugs."

-Richard Twyman (http://genome.wellcome.ac.uk/doc_WTD020807.html)

i think it is unimaginable that the human genome only has 3-4 times as many genes as the fruit fly!  we are "so complex" compared to a fly.  and yet the human has about 30,000-40,000 genes compared to the fruit fly which has 13,600.  it was estimated that the human genome would have 80,000-100,000 genes.  but this illustrates that size does not necessarily correlate with complexity.  a fruit fly is actually a complex organism, with a nervous system, a digestive system, a muscular system, eyes, legs, and a kind of external skeleton.  in addition, fruit flies have wings and antennae, which humans do not.  when we consider the tremendous amount of biological complexity in those 13,600 genes, perhaps it is surprising that humans have so many more genes than the fruit fly.

anatomy of a cow

in preparation for my hunt, i watched a few videos about dressing an elk in the field, including skinning and de-boning.  i find it fascinating that so many people are comfortable with the idea of hunting and harvesting an animal, but are uncomfortable with the idea of investigating the human body on a cadaver.  there are a lot of similarities between the two, but it feels so different.

this lab experience gives be a more intimate knowledge of what parts of an animal i am eating.  i can actually visualize the rump roast or the backstrap because i have made incisions in those areas on a body.  it is a weird thing to compare, i know, but i like knowing where my meat comes from and this takes it to a whole new level.

i also have a more thorough understanding of massage; i can picture the direction of each muscle fiber and i can imagine myelin sheath being stripped during neuromuscular massage.  and during acupuncture i can imagine the depth of the needle and which organ or muscle it contacts.  i like that this lab experience has shed new light on other parts of my life.

imaging

unfortunately, i missed week 5 because i was in portlandia.  fortunately, i got to attend my cousin's wedding and camp on the oregon coast!

my left knee has been aching on and off for about 8 weeks now.  at first, it hurt for a few days and then felt fine for a few days.  there was nothing specific that provoked it except direct massage.  i could bike or drive to work, and there was no difference.  i could ice it and take ibuprofen for short term relief when it hurt.  i chose to treat the pain with massages and acupuncture.  neither gave full relief.  while i was in portland, a physical therapist loosely diagnosed a torn meniscus and suggested that an mri is needed to determine the severity.  i went back to my chinese medicine practitioner yesterday to ask what acupuncture and herbs can do for a torn meniscus.  tears and breaks are, unfortunately, not easily treated with chinese medicine.  today i went to an orthopedic surgeon and he thinks it is a vascular tumor.  he also suggests an mri for a better diagnosis.  i scheduled an mri with gadolinium contrast.  i am interested in how the "gad" affects the image.

it is one of the most commonly used contrast agents used in magnetic resonance imaging (mri).  it is usually injected into the body and is quickly excreted through the filtration of the kidneys.  the fda declared gadolinium safe for use in mri scans in 1998 to provide greater detail when viewing the brain and connective tissues such as spinal discs, cartilage, scar tissue, soft tissue tears, tumors, etc.  after gadolinium is injected, it surrounds the abnormal tissues creating an enhanced view of even the slightest abnormality.  it creates a "glowing" effect within the body allowing technicians to see problem areas in very specific ways, especially location and size.  the side effects include burning at the site of injection, mild nausea and headache.

breathe and beat

on week 4 we started class with an oral practical to test our knowledge of the back, arm, and brachial areas.  it is amazing how easy it is to remember dozens of structures after spending time dissecting them.

human life is sustained, in large part, by our heart and lungs.  one could argue, both physically and emotionally.  so it was a powerful experience to hold her heart and lungs in my hands.

first, we removed rose's right lung.  interestingly, there were two places that the lung was attached by an adhesion to the pericardial wall.  this was unfortunate because the purpose of a serous membrane is to prevent adhesions from forming so that organs may move freely.  i don't know what caused these adhesions, but i can imagine that they were not comfortable.  when we finally pulled out her lung, we were surprised that the majority of her lung was in her posterior thorax because of her kyphosis.  the body is so adaptable!  in this case, i imagine she felt like she couldn't get a full breath, that she was a shallow breather because her lungs were so far posterior.  also, her lungs were partially black as if she had smoked (or inhaled second hand smoke) for years, so perhaps she had difficulty breathing because of her degraded lung tissue.

next, we removed her heart from the pericardial sac, maintaining as much structure as possible so that other students can learn about the heart first hand.  we were able to maintain the sac, the aortic arch, and several places where we can see and feel atherosclerosis.  when i held her heart i felt overwhelmed with gratitude and powerful energy.  this is a very special gift that we have received.

these two important organs are given a lot of credit in our daily lives - from breathing techniques in yoga to a broken heart when a loved one is lost.  and they work together to maintain human life.  the lungs exchange gas in pulmonary ventilation, or breathing.  the lungs and blood exchange gas in pulmonary diffusion.  the heart, lungs, and all of the adjoining blood vessels work together to keep the circulatory system healthy and working efficiently to sustain life.  they are interdependent.  the heart pumps blood, the lungs deliver oxygen, the blood vessels carry the required blood and nutrients to keep the heart and lungs going.  and i was able to hold a human heart and a human lung!

arms

on week three, we dissected rose's arms.  we are moving quickly through the dissection.

it was fascinating to see the capsule of fascia that surrounds all of the forearm muscles.  all of the muscles are held together by this white connective tissue which is unyielding to the muscles underneath.  if a forearm muscle swells it can be extremely painful because the capsule doesn't allow for expansion.

if someone were to ask me about pain in their forearm, i could now explain it this way...
the forearms rely on the coordinated movements that happen between the flexor muscles (posterior) and the extensor muscles (anterior).  in many cases, the muscles on one side of the forearms get overworked and begin to bind (the muscles "glue themselves together") to support one another through the strain.  these adhesions are the main source of forearm pain.  and these side-by-side muscles begin to act like one big muscle rather than smaller, more action-specific muscles.  this leads to extreme fatigue and the chance for more serious injury.  adhesions also prevent muscles from relaxing and lengthening fully - they are in a constant state of contraction which results in tired, overworked muscles.

these types of adhesions can be prevented by avoiding repetitive movements, stretching after exercise, and practicing good technique when using the forearm muscles.

further reflection

week two (august 30) of bio 203 was interesting as we got to see the sciatic nerve!  although not in line with grant's dissector, it was a fascinating dissection and very interesting to palpate.  surprisingly, it is approximately the same size as the spinal cord, which means that after it diverges from the spinal cord it gets larger, unlike most spinal nerves.

during our class time, we further dissected the back to clean superficial muscles and reflect intermediate and deep back muscles.  next, we cleaned several structures in the suboccipital region.  finally, we were able to cut the laminae of the vertebrae to reveal the spinal cord.  this was fascinating!  it took us at least an hour just to saw and chisel the laminae after they were exposed.  it gave me a new appreciation for how protected our spinal cord is.

rose

august 23 was week one of bio 203.

we met our cadaver, who we named rose.  i felt overwhelming gratitude to have such a special opportunity - both the immeasurable gift of her body to my education and the invitation to be a part of this small lab class.

within the first few minutes we noticed:
-she is an older woman, probably early 80's
-she has a 6" incision on her abdomen which is half taped closed and half sewn closed with a thick twine-like material
-she has a lot of fat, probably borders on overweight and obese
-she has an iv gauze and tape on her wrist
i am excited to learn more about how her disease and distress manifested in her physical body.

the first chapter in grant's dissector instructed us to start with her back.  there were a lot of protocols and techniques to learn, but we had enough time to clean the surfaces of the superficial back muscles.

the most interesting thing i saw was the impact of her kyphosis.  there is no way to tell (yet) if it is a result of a damaged vertebra or poor posture (or a combination).  for now, we can determine that she had kyphosis for a long period of time because all of the tissues along her upper thoracic vertebrae (approximately T2-T4) has hardened to the point that it almost feels like bone on the surface.  i can't wait to see what other effects we will see when we get into her thorax!