Reflection
All
the journal assignments helped me understand biology better. The
journal that I enjoyed writing the most was about de-extinction because I did
not know it was possible to somehow bring an extinct species back to life. At
the beginning I could not think of why someone would want to do that since
extinct animals are extinct for certain reasons but as I did my research and
read a few articles I learned that it is an incredible discovery that if we use
it properly it can help us. For instance, if we focus on using those methods to
prevent in danger animals to extinct, it can help the environment and the food
chain to maintain.
After
completing these journal assignments, now I am more aware of why so much money
goes to scientific studies and that for every new discovery there can be a
downside to it or it can be beneficial. Although we think we live in such a
modern world, discoveries keep happening everyday and if you think about it
there are some things that are there but we don’t know them. The cure to cancer
or the cure to HIV is somewhere out there waiting to be discovered. I think it
is important to educate people on how important it is to support scientific studies,
especially if it can benefit a lot of people.
Carla Valdez
Biology 1010
Hardy
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D |
e-extinction has been a controversial issue in biology during this past few years. De-extinction has been proposed by various scientists throughout the years, this consists of the idea of bringing an extinct species back to life. So far, three methods have been proposed to do this: cloning, modification of DNA and a process called breeding back. Cloning is the method that has gotten more attention. Scientists think that they can reconstruct an extinct species’ genome through a sample of viable DNA of that species. These DNA samples can be obtained from museum specimens. Once they reconstruct that genetic material, next step would be to combine a lab-created nuclear cell of the extinct animal with an egg of another similar species, whose nucleus was removed and implant the embryo in the uterus of the same species.
Another method would be the modification of the DNA of a close living relative of that extinct species. This could be done by using a cell line of the living species that could progressively splice in the extinct species sequences to replace the corresponding regions of the living species chromosomes. Scientists have tested this hypothesis by successfully splicing the DNA of a thylacine into a mouse.
A more natural and easier way to bring extinct species back to life is the process called ‘breeding back’. This method is being tested with cattle by scientist Henri Kerkdijk-Otten of the Megafauna Foundation. He is hoping to bring aurochs back, which are the ancestors of domestic cows. This process consists of using strategic mating to incrementally restore the anatomy and the genome of an extinct animal. For example, in the case of cows; cows with the most aurochs’ characteristics would be mated with another cow with the same characteristics. A domesticated cow with mostly aurochs’ characteristics could be resulted after some generations of strategic mating.
There are pros and cons towards this issue. The reasons of why de-extinction should be done are the same of why we make an effort to protect endangered species: to preserve biodiversity, to restore diminished ecosystems, to advance the science of preventing extinctions, and to undo harm what humans have caused in the past. Some of the extinct animals were very important to their ecosystems and it would be great if they could be brought back to life. For example the woolly mammoths were the dominant herbivore in the North. When they were extinct the grasslands they helped sustain were replaced by species-poor tundra and boreal forest. If they were restored to the north, it would bring back carbon-fixing grass and reduce greenhouse-gas-releasing tundra. Also the methods of de-extinction would be useful to help preserve today’s endangered species. And examining the genomes of extinct species can tell us more about what made them vulnerable in the first place.
Some arguments of why extinct species should remain extinct are because some of those animals are not adapted to the world we live in now. An animal also needs a safe home but since that animal was extinct, so was its natural habitat. It is also a fantasy to think that with biotechnology humans can repair the hard that we’ve done to biodiversity. Another argument against de-extinction is that once we find a way to bring extinct species back to life, we would put less effort into keeping endangered species safe. Research priorities can be changed. De-extinction is expensive and it takes time, so it will take money and time away from other research findings.
My opinion on this controversial issue is that scientists should turn to de-extinction if it is necessary. For instance, if the extinct animal was fundamental in its ecosystem and in the food chain. Also, I think that scientists should focus more on using those methods to try to preserve the living species that are closer to extinction rather than worrying about restoring animal that are already extinct.
The Cushion sea star is a species of starfish and an invertebrate animal. It belongs to the Animalia Kingdom; its Phylum is Echinodermata, which is a type of marine animals, Subphylum Asterozoa, and Class Asteroidea. This species rapidly evolved into two independently species of Cushion sea stars, the Cryptasperina hystera and C. pentagona.
The Crypstasperina hystera and C. pentagona live in different regions on the Australian coast. The biggest difference between these two closely related species is the way they reproduce. The Pentagona has male and female starfish that release sperm and eggs in the water to fertilize. When the egg and sperm get together it converts into larvae that floats around in the water until it grows into an adult sea star. The Hystera are hermaphrodites that brood their young internally and give birth to miniature sea stars ready to grow. A team of researchers in Australia, Canada and the U.S analyzed genes in the two species’ nuclear and mitochondrial DNA to discover how recently the sea stars separated. They estimated that they split around 6,000 years ago, which is an amazingly short period of time for a species to show evolutionary changes.
Another adaptation to the environment of starfish in general is regeneration. This is one of the starfish’s greatest adaptations to its dangerous marine environment. After being attacked by a predator, some species of starfish can regrow almost their entire body with just a part of their arm. This is possible because most of their vital organs and nervous systems are located in their arms.
The starfish’s feeding habits is another adaptation that evolved to fit their environment. Most sea stars are carnivorous; they prey for clams, oysters and sea snails. They locate their preys with light-sensing eyespots at their arm tips. Other species eat decomposed dead plants and animals, and some have diets that consist of algae and plankton.
Starfish have also developed special digestive systems that adapted to the food sources in each species’ environment. They have two stomachs, a cardiac stomach and a pyloric stomach. The cardiac stomach digests their prey. They inject it into bivalve mollusks and suck out the soft internal body parts. The pyloric stomach completes the digestion. This allows starfish to eat animals much larger than their mouths.
Other adaptations of sea stars in their tough, bony, calcified skin that protects them from predators. Their skin colors act as camouflage to help them blend into their environment. Some species have bright colors to scare off or confuse predators. They also produce and release huge amounts of eggs and sperm into the water giving them a better chance of survival.
Article Summary
Denise Grady, an author of The New York Times describes in her article Malnourished Gain Lifesaver in Antibiotics studies found on how antibiotics can help children that suffer from malnutrition. Scientists from Washington University concluded that severe malnutrition is not only caused by lack of food, and that feeding alone may not cure it. The study was published Wednesday in The New England Journal of Medicine; the senior author is Dr. Mark J. Manary, who is an expert in malnutrition and known to be one of the pioneers in using peanut butter as a “therapeutic food”.
The second study, directed by Dr. Jeffrey I. Gordon, found that an imbalance in bacterial population in the gut may contribute to a severe form of malnutrition called kwashiorkor. The fortified peanut butter could help restore the proper balance or even giving the patient with kwashiorkor the bacteria they lack. Although the use of enriched peanut butter was a huge advance finding, some malnourished children died despite receiving it, or did not grow or gain weight as well as expected.
The experiment was directed by Dr. Trehan and his colleagues in Malawi. The experiment involved 2,767 children, 6 months to 5 years of age, who suffered from severe acute malnutrition. All of them were given peanut butter and were assigned at random to receive an antibiotic or a placebo for one week. The researchers kept track of recovery (weight gain, growth 0r disappearance of symptoms like swelling), and death rates. In the placebo group, 85.1 percent of the children recovered, compared to 88.7 percent taking amoxicillin and 90.9 percent taking cefdinir. In the children who recovered, the ones taking antibiotics had a higher rate of weight gain.
Because of the results and the fact that these antibiotics cost only a few dollars, the World Health Organization expects to recommend broader use of antibiotics when treating malnutrition. But the practice had not been tested in a controlled, rigorous way.
The second study focused on children with kwashiorkor. The exact cause for kwashiorkor has not been found, although many scientists have blamed the lack of protein and calories.
“Could it be human genetic variations?” Dr. Gordon asked. “Environmental factors? Malnutrition interacting with impaired immunity? Diarrhea? All these infections? What the heck is going on? That was in a sense part of the birthplace for our study.”
Fecal samples revealed that the children with kwashiorkor had a different, less diverse microbiome than the healthy children. The bacterial mix in their gut became healthier when they were fed the enriched peanut butter, but reverted when it was not given to them.
To test their hypothesis, gut bacteria from the children with kwashiorkor was transplanted into the guts of germ-free mice, the animals lost weight if they were fed a typical Malawian diet, and their metabolism became abnormal. They improved if given the enriched peanut butter, but, like the children, reverted when it was taken away.
http://www.nytimes.com/2013/01/31/health/antibiotics-can-save-lives-of-severely-malnourished-children-studies-find.html?ref=science
