Rachel+K.

=**Post #1: Genetics**= //**October 23, 2015**//

Progeria is an extremely rare and serious genetic disease which currently affects less than one-hundred and fifty people worldwide. This condition is shown through premature aging in children; the most severe version of the disease being know as Hutchinson-Gilford progeria syndrome. Lack of intelligence is not a symptom that accompanies progeria, but baldness, aged-looking skin and a small head are all symptoms that come with this disease. Internally, individuals with progeria tend to experience typical signs of old age: including arthritis, dislocated hips and rapidly progressing heart disease. This disease is fatal: the most common cause of death being heart attack or stroke brought upon by the heart disease that accompanies progeria.

It is obvious that progeria is a serious and horrible disease. So why does it occur? Progeria comes about by a single gene mutation in the gene lamin A. This disease is not hereditary and the mutation that causes it often appears to occur in the sperm before conception. This disease occurs by the substitution of a single base pair within the twenty-five thousand base pairs which lamin A is composed of. The lamin A gene codes for the proteins lamin A and lamin C. These proteins are an important part of stabilizing the inner membrane of the nucleus in a cell. The mutation that causes progeria brings forth an abnormal version of the protein lamin A. This protein destabilizes the inner membrane of the nucleus and causes serious damage to systems in the body such as the cardiovascular and musculoskeletal systems. Shown below in Figure 1 is the difference between a healthy human cell and one affected by progeria. It is easy to see which is more stable. Progeria is caused by sheer chance and is a truly heart-breaking disease.

Figure 1: ==

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This video outlines the challenges and triumphs that have come from the search for more information, treatments and cures regarding progeria. The speaker (Dr. Leslie Gordon) has been very involved in the race for a cure to this disease. Her own son was diagnosed with progeria and that has clearly been her motivation to search for a cure. This video describes her journey for treatments and a cure to this disease and how she is able to work in order to achieve the impossible.

Figure 2:



Figure 2 outlines some statistics involving progeria. The first is saying that an estimated 1 out of 4-8 million children are born with progeria. The second shows that one year of aging in a child born with progeria is often equivalent to ten years of aging in a person without this disease. The final portion outlines the fact that a child born with progeria is expected to live only up to 13.4 years of age. It should be noted that different sources come up with different statics for the first portion of this picture. For example, the video shown in this post says that 1 out of 18 million people are born with progeria, but many other sources have stated the same numbers as this picture gives.

Figure 3:

Figure 3 is the logo of the Progeria Research Foundation. It is an opened rose carried by a seagull which is flying upward in order to symbolize hope as well as inspiration. The background is Sam Bern's handprint ( a child affected by the disease who is recognized in Figure 4). The Progeria Research Foundation was formed by Dr. Leslie Gordon and Dr. Scott Berns when they found out that their son Sam had been diagnosed with progeria. It has been the source of how we know the cause of progeria today as well as treatments for the disease.

Figure 4:

Figure 4 shows a thirteen-year old boy named Sam Berns. He passed away four years after this picture was taken; at the age of seventeen in the year 2014. His mother was Dr. Leslie Gordon; based on the love that his family had for Sam, his parents worked Sam's entire life to develop research, treatments and to work toward a cure for progeria. They also developed the Progeria Research Foundation: an amazing resource for any families who must live with progeria in their children's lives. Although the work done during Sam's lifetime was not enough to save him, his legacy will live on as the source for the much-needed information on progeria and the hope for a cure to this dreadful disease.

Further Reading: This short, visually appealing video give a quick explanation of why progeria occurs at a genetic level. []

This article outlines in detail the visual and physical side effects of progeria. []

This article from the Progeria Research Foundation tells the story of many children who are currently living with progeria. []

This is a TED talk that Sam Berns carried out during his life. It is truly inspiring, and I suggest you take the time to watch it. []

Sources Cited: [] [] [] []

=**Post #2: Evolution**= //**November 23, 2015**//


 * The End-Cretaceous Mass Extinction **

The Cretaceous Mass Extinction (also known as the KT extinction) is said to have been the second greatest mass extinction in Earth's history. It was also the last of the five mass-extinctions as well as the most famous. It was through this extinction (which occurred 65 million years ago) that came the total extinction of non-avian dinosaurs as well as 50% of other organisms. It would be very difficult to piece together the full story of an event (or series of events) that occurred 65 million years ago, but we can certainly try. There are many different theories as to how this extinction occurred (some of which will be further outlined throughout this post), but it is clear that this devastating extinction was a key part to bringing forth the world which we know and love today.

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This video outlines many of the theories surrounding the cause of the Cretaceous Mass Extinction. It differentiates between the different pathways of thought regarding this extinction and shows visually some of the difficulties that the dinosaurs and other organisms faced as they struggled (and failed) to survive.

Figure 1:

Figure 1 is a visual representation of one of the theories surrounding the Cretaceous Extinction. Many believe that a single asteroid about 10 kilometers in diameter was the major cause of this extinction. It hit the earth in Mexico and caused an issue based on its initial shock value, but it also brought forth a change in atmosphere on the earth. Many organisms could not survive this shift in environment (including most dinosaurs), and they went extinct. This asteroid is the only portion of this extinction story that scientists are sure of, but there are other causes that may have worked with the asteroid.

Figure 2:

Figure 2 demonstrates another possible cause of the Cretaceous Extinction that would have worked in conjunction with the asteroid that was previously mentioned. Some scientists believe that many asteroids may have hit earth at the same time. Evidence which supports this is found in other craters found on earth which are thought to have been caused by other asteroids. In this thought pattern, many asteroids may have broken off of the same original asteroid and hit earth. This makes it easier to see such a momentous change in atmosphere and such a huge extinction.
 * It should be noted that Figure 2 does not show the type of asteroids that would have hit earth. They would have been much larger and more spread out over earth than what is pictured above.

Figure 3:

Figure 3 shows volcanoes much like those that may have played part in this extinction. It is believed that there may have been extreme lava flows that worked to alter earth's atmosphere. This lava flow would have been present millions of years before the asteroid hit, but when the asteroid was present, the impact of this dual change in atmosphere would have been too momentous for the dinosaurs and other species to survive. It is believed that magma spread over 2.6 million square kilometers going 2.4 kilometers thick over India. This would have spread vast levels of iridium throughout the earth: affecting many organisms in a detrimental way.

Figure 4:

Figure 4 shows what is left of the majority of dinosaurs. Fossils are the only way that we can learn about this extinct branch of organisms, and as we discover more of them, we learn more about the dinosaurs that once walked our earth. Had this extinction occurred, mammals may have never risen to the prominence they did on earth (as they would continue to be food for the dinosaurs), and the world would be a much different place today.

Further Reading: This article outlines evidence of the link between modern-day birds and the dinosaurs. __ [] __

This article talks of the Cretaceous Period as a whole (not only the extinction event). __ [] __

This article outlines some of the wonders that were brought about through the cretaceous period (including flowering plants). __ [] __

This website shows a portion of the fossil record from the Cretaceous Period. __ [] __

Sources: [] [] [] []

=**Post #3: Body Systems**= //**January 15, 2016**//

Pituitary Gland: Posterior Lobe
The Pituitary Gland is often referred to as the "master gland" as the hormones that it secretes control the other glands in the endocrine system. It is made up of a posterior and anterior lobe: both of which are responsible for important hormones. I have chosen to focus on the posterior lobe as it is is responsible for only two hormones, but they are hormones which I find interesting. This portion of the pituitary gland is responsible for the secretion of the hormones oxytosin and antidiuretic hormone (ADH, otherwise known as vasopressin). These hormones are actually created by another gland called the Hypothalamus. However, they are stored in neurosecretory vesicles (Herring bodies) and later secreted by the posterior pituitary into the bloodstream. This is a short overview of the functions and nature of the posterior pituitary gland.

Figure 1 shows a diagram of the pituitary and hypothalamus glands, but it focuses on the connection between the posterior pituitary and the hypothalamus. It shows the movement of oxytocin and ADH throughout this gland as well as demonstrating how well-connected it is to the hypothalamus.

Figure 1:



Video 1: media type="youtube" key="KCVUDKEGaAg" width="560" height="315"

This video details the control that the hypothalamus of the posterior pituitary. It briefly talks about how the hormones that are secreted by this gland are actually created by the hypothalamus and than transported through axons to the posterior pituitary. It then goes on to explain how these hormones are released through different neuroendocrine reflexes. It explains that both hormones are secreted based on the direction of the hypothalamus. These glands are completely intertwined. Figure 2:

Figure 2 shows the chemical form of the hormone oxytocin: one of the two hormones that are secreted by the posterior pituitary. Oxytocin is chemically classified as an nonapeptide (meaning that it has nine amino acids), and it is biologically classified as a neuropeptide. This substance acts as both a hormone and a brain neurotransmitter through its functions. Oxytocin plays a role through sex, childbirth and breastfeeding and has been labelled the "love hormone". It is interesting to note that high levels of oxytocin are often present in couples during their first six months of a relationship. It has neurological effects that can dictate emotion and social interaction. Despite these "lovely" attributes, oxytocin is also a major part of bringing and sustaining new life in the world.

Figure 3:

Figure 3 simply shows a beautiful newborn baby. This child is related to the posterior pituitary gland and oxytocin because of the effect that oxytocin has in the first minutes and subsequent months that a baby experiences outside of the womb. Oxytocin is responsible for one the few positive feedback mechanism present in the body. As this hormone is released during labour, it increases uterine motility which in turn causes the muscles of the uterus to contract. The subsequent release of oxytocin is triggered as the cervix is widened due to these contractions, and thus, more contractions occur. Oxytocin certainly plays an important role in the birth of a child, but it also plays a role after the child is born. This hormone also helps to sustain the child as it is involved in the production of breast milk. As the nipples are stimulated by a child latching on to them, oxytocin is released which in turn causes milk to be released. These are two major functions of oxytocin which help bring beautiful children such as the one above into the world.

Figure 4:

Figure 4 shows vasopressin pills. Vasopressin or ADH is the other hormone that is secreted by the posterior pituitary gland. Its role is to encourage the kidneys to increase water absorption in the blood. Insufficient levels of vasopressin (which could cause pills such as these to be needed) can cause diabetes insipidus. This condition is one in which the body loses its ability to concentrate its urine. If you are affected by this condition, you may release up to 20 litres of dilute urine a day. If an overload of ADH is secreted by the posterior pituitary, a condition called Syndrome of Inappropriate Antidiuretic Hormone will occur, causing an unhealthy increase in body fluids. It is important that the posterior pituitary secrete the right amount of ADH in order to prevent either of these conditions. These are just a few of the wonders and functions of the posterior pituitary gland. It is responsible for the secretion of two very different hormones that both play a huge role in our lives. The endocrine system is full of wonders such as these, and it has been interesting to learn an in depth explanation of just one small portion of this incredible body system.

Further Reading: This website gives information on the entire pituitary gland: both anterior and posterior. It is interesting to learn some of the functions and hormones involved in the anterior as well. __ [] __

This article gives a further link explanation between the pituitary and hypothalamus glands and talks about hormones secreted by each along with their functions. __ [] __

This video speaks of more of the functions of oxytocin based on the emotional and social behaviour side of things and speaks of a study done at Concordia University involving oxytocin. __ [] __

This article speaks of the label that the pituitary gland has as the "master gland" and why that is an appropriate nickname. __ [] __

Sources: [] [] [] []