Go Evo-Devo!! I guess I can skip the evo-devo lecture in the evolution class now, eh?
[Hat-tip: Pharyngula]
A royal scam, and one involving AI
22 hours ago
Showing posts with label development. Show all posts
Showing posts with label development. Show all posts
Wednesday, March 11, 2009
Regulatin' Genes is where its all at! Evo-Devo!!
[Hat-tip: Pharyngula]
Sunday, October 26, 2008
Socially learned foraging behaviors in wild black bears
The American Black Bear, Ursus americanus, is currently the only species of bear in the state of California. In a fascinating presentation by Rachel Mazur, pictures and videos were used to depict the beauty of these bears in their natural and not so natural environments; the latter being bears foraging for food in developed areas of the national parks including getting food out of trash cans, cars, etc.
Research by Mazur finds that bears have traits for social learning and the most critical times of a bears learning process is during the first year when they are in constant contact with their mother (Mazur, 2008). Three separate hypotheses were compared to describe how these bears are learning to become food-conditioned to developed areas. The first is that bears inherit these behaviors from their mothers and can be predicted (Mazur, 2008). The others include bears learning individually (that is, without the help of the mother) and transmitted learning from sow to cub (Mazur, 2008).
The methods used for this experiment were efficient in that homogeneity was taken into consideration. Therefore five variables were taken into consideration including park, sow identity, sow behavior, rearing method and cub outcome (Mazur, 2008). The two national parks which Mazur encouraged everyone to visit include Sequoia National Park and Yosemite National Park. From showing clips of a movie on this research, it was evident that many years of hard work by numerous staff was done to work with these bears and monitor their statuses.
Mazur stated that she was very pleased with the results that they came across. An easy to read table of her results shows the number of sows that they started with (23 food conditioned and 9 wild), the rearing methods of these sows (rearing in wild or food-conditioned rearing), and the outcome of the cubs once separated from their mothers (Mazur, 2008).
Conclusions made by Mazur asserted that rearing method had a highly significant effect on the cub outcome (Mazur, 2008). If a cub was reared food-conditioned, it was much more likely to be food-conditioned once separate from its mother. That being said, the last hypothesis stated by Mazur was seen to be the most accurate: that bears become food-conditioned through social learning.
In both seminar and paper, Mazur stated that there are numerous implications for the work that has been done. She posed a question to the room regarding the bear’s possibility of creating culture and even tradition in our national forests with these new food-conditioned characteristics (Mazur, 2008). What I found beneficial in this work is the implication that food-conditioning in developed areas in our national forests do not necessarily imply adaptive strategies of these Ursus americanus, but may very well be falling into an ecological trap (Mazur, 2008). I also found it interesting for her to note that science and management have recently become less taboo as a pair in the scientific world.
Reference:
R MAZUR, V SEHER (2008). Socially learned foraging behaviour in wild black bears, Ursus americanus Animal Behaviour, 75 (4), 1503-1508 DOI: 10.1016/j.anbehav.2007.10.027
Friday, October 24, 2008
Development and Divergence of Canid Morphology, A Critical Review
When considering the comparison, it is astonishing that toy poodles belong to the same family as wolves: Canidae. Even more interesting is the observation of the divergence of domestic dogs from wolves. Robert K. Wayne approaches this topic with his paper “Limb Mophology of Domestic and Wild Canids: The influence of Development on Morphologic Change.” His primary objective was to determine whether allometry as an index of development and function is the same in domestic and wild canids. (Wayne 1986)
Bivariate Analysis
Domestic dog breeds have wider long bones than their wild counterparts of the same femur length. When comparing relative long bone width, there was little difference between domestic dogs and wild canids. Metapodial, scapula, and olecranon length difference were ovbious between dogs and wild canids. Long bone width and development reflect that fact domestic dogs do not need to hunt or escape predation.
Discriminate Analysis
General size of all canidae family members, domestic and wild, was analyzed to determine similarity of morphologic patterns. Despite diversity in limb size and proportion, domestic dogs are highly distinguished from all except wolf-like canids. Morphologic separation of wild canids among each other and of domestic dogs and wild species depends on difference in metatarsal and olecranon morphology. This suggested that morphologic evolution abides by phylogenetic boundaries (Wayne 1986).
Ontogenetic Analysis
Similarity of dog-intraspecific and dog-ontogenetic analysis showed that small dog breeds are paedomorphic whereas large dog breeds are hypermorphic. This assumes that diversity of limb diversity is predetermined and reflected in the development of an individual as breeders artificially select domestic dogs for favorable traits.
Conclusion
Wayne’s study indicated that allometry can be utilized as an index of devlelopment and function in both domestic dogs and wild canids. Morphological and bone differences were apparent amongst all members of the canidae family. However, some differences were not as distinguishable between domestic dogs and closely related wolves. As domestic dogs are bred for entertainment value, these differences will become more apparent.
Literature cited
Wayne, R. K. (1986). "Limb Morphology of Domestic and Wild Canids: The influence of Development on Morphologic Change." Journal of Morphology 187: 301-319.
Monday, September 8, 2008
Yet another controversy to teach in our classrooms
And this one is a good analogy to the creationist arguments
The theory of childhood, also known as child origin, is a damnable, loathsome and indefensible lie. How can any thinking person suppose all humans used to be babies once? There is no development path from babies to adults, no transitional forms between these two species. Show me even one baby with the head of a grown man on his body. Can you? No? Not even a bearded toddler? No adults with unfused skullbones, outside unfortunate disorders? Not even a tiny little newborn girl suddenly sprouting a respectable bosom? You can't find them, because they don't exist. There isn't a single transitional form between children and adults, and you will never find one because the theory simply is an unscientific lie.
The development of children has been well-researched in our six-month study following a sample of one thousand children and adults of various ages. We have conclusively proven that while there are minor changes in features like height and body fat, and replacement of deciduous teeth with permanent teeth, incontravertibly still every creature in the study that started out as a child had only slightly more adult features at the end of the observation period than at its beginning. Children and adults are separate kinds and there will never be sufficient changes to change one into the other. We reject any evidence from longer-term studies as we believe the laws of physics have changed within the last year.
To claim people come from children is demeaning and morally degrading. We have observed how children behave. If we acted like small children we'd all be demanding and impatient, and we'd be cheating, lying, and stealing from each other all the time. If the theory of childhood were true there would be no morality, and with no morality to build one on, no society. Childhood is a wicked lie used by charlatans to justify evils such as public schools.
There is no consensus on the theory of childhood in the scientific community. We should teach the controversy. Our children will be served well to learn that the prospect of them becoming adults is merely a theoretical idea. Many children come from families that do not subscribe to the theory of childhood, and they could be disturbed if the theory were taught as fact.
[From metaquotes: ari_rahikkala makes a compelling arguement...]
Sunday, May 4, 2008
Impressions from the Central California Research Symposium
Kara Ward shares her experience attending the 29th Annual Central California Research Symposium held recently on campus.
Overall Impression:
The 29th annual CCRS symposium, held at Cal State-Fresno, was without doubt an experience to remember. Although I cannot say that it was my preferred activity for the afternoon, I can definitely say that when I left the symposium I had acquired a greater knowledge of how many undergraduate and graduate science talks and public presentations progress. I myself have not attended many of the weekly Friday Biology seminars they have here at Fresno State so it was definitely a treat to attend this symposium and I was actually very interested in seeing work produced by my peers.
Out of the six presentations that were actually presented to us, it was apparent that each presenter had a different angle and strategy in the planning and preparation of his or her presentation. Of the six presentations, a few presenters actually did an excellent job in presenting their topic thoroughly in the sparse time allotted to them. These few presenters stood out because of their ability to utilize all of their skills to present a complete presentation. Others, however, failed in many areas such as utilizing their allotted time efficiently, in using the correct grammar and speech necessary to give a public presentation, and most importantly, in presenting the material and data in a manner that we the audience could understand. It is my opinion that these presenters would defiantly [sic] benefit from more practice and possible lessons in how to give public presentations. I can definitely understand that they had to present a lot of information and data in a very short time, but more practice on the presentation itself may have produced much smoother delivery and pace. It was apparent that many of the presenters were nervous and a public speaking course could and would serve them well. Overall my assessment of this symposium is fair, and based on my experience attending this symposium, I would positively attend next year should I be afforded the opportunity and recommend that all science majors do the same.
Critique 1: The Identification of Brachyuran Megalopae of the San Francisco Bay Estuary
Presented by: Vanessa Gonzales
I chose this presentation to critique because I had heard a few things about the Chinese mitten crab in prior classes; however I had never actually been presented with such detailed facts about the crab’s lifecycle and I was extremely intrigued by it. I liked the flow of the presentation and appreciated how she began her talk explaining the problem before going into the details of the experiment. I thought Gonzales did and great job of explaining how the presence of the crabs negatively affected the habitat by competition with and predation of some of the native species; however, I would have liked her to speak a little more about some of the native species which were affected. I also thought that the presenter did an excellent job of providing graphs, charts and tables which illustrated the facts and stressed the points that she was trying to make. As I stated earlier, I feel that the presenter did a great job of going through all of the important stages in the life cycle of the crab. This background information would be vital to know prior to being able to understand the full extent of the problem at hand as well as understanding how the experiment was set up and I feel that she was wise to include it. As the presentation continued and Gonzales entered the research portion of the presentation, I felt that she entered into somewhat of a read and speak mode. By read and speak mode I mean that it almost seemed like she was just reading lines from her note cards and it was apparent that she may have gotten lost in her notes, because between every sentence she would say phrases akin to “um” and “like”. Aside from these minor areas, I felt that the presenter did a good job of presenting the information in an organized manor. The presentation flowed and each section was explained well by Gonzales who utilized her time well.
Critique 2: Potential Impacts of Selenium on California Red-Legged Frog (Rana draytonii)
Presented by: Foung Vang
I chose this presentation to critique because I had never heard of the primary organism of this study, the Red-Legged Frog, and just the name was enough to warrant my interest. After reading the abstract, provided by the presenter, my initial thoughts went to the Zebrafish experiment we conducted in our Developmental Biology lab in which we treated the fish with varying amounts of ethanol. Based on my experiences with the Zebrafish lab, I knew that most experiments monitoring early development are quite interesting and could really go either way so I was definitely interested in seeing the outcome of this experiment. Overall I felt that there were some strong areas of the presentation as well as some weak areas. The weak areas in the presentation for me, was the lack of background information on the frogs as well as the lack of graphics and illustrations. Where the presenter did a great job of providing us with a background of selenium and the issues presented by selenium in the environment, he hardly spoke at all about the history and life cycle of the frogs. It almost seemed as if the presenter was too eager to begin the discussion of the hypothesis and results section of the experiment, but in doing so, the presentation came off as being unbalanced and dry. Although this lecture presented a lot of facts and data, I still felt as if something was lacking in the overall presentation. Perhaps the problem for this presenter was merely a time management issue, trying to put too much information in a twelve minute presentation; however, this should not be an excuse. My overall assessment of this talk was that it was very informative and the presenter was well spoken, however, I still would have preferred a little more background information on the target organism as well as a little more visual stimulation.
Monday, April 28, 2008
Regenerative medicine inspired by a Newt
Student post submitted by Sheena Edmonds
An experiment was done that utilized immature muscle cells of newts and mice. The two types of myoblasts were grown together and induced to differentiate into skeletal muscle fibers. Some of the newt myoblasts fused with the mouse myoblasts and created a hybrid. The hybrid cells were isolated and stimulated with serum (Cai, 2007). The serum was expected to cause the newt myotube to synthesize DNA but they did not expect the mouse myotube to do the same. Shockingly, the mouse myotube also began to synthesize DNA which indicated that there was something in the newt myotube nuclei that made the mouse myotube nuclei able to respond to the serum (Cai, 2007). In yet another experiment, the mouse myotube dedifferentiated when it was treated with extract derived form the regenerating limb of the newt implying the signal that initiates dedifferentiation was in the extract. Researchers subjected the extract to chemical and physical treatment including lipid removal, boiling, and trypsin digestion. The results proved the signal within the extract was a protein (Cai, 2007). Moreover, these two experiments confirm that mammalian cells can dedifferentiate when stimulated with the right factors. Identification of the exact molecules would aid in studying the mechanism for dedifferentiation which could eventually be used to regenerate tissue in vivo.
Researchers have now directed their attention to studying the dedifferentiation process that occurs in human myoblasts. They found that ciliary neurotrophic factor (CNTF) plays an important role in regulating many processes with in the nervous system. They also found that there are an abundance of CNTF receptors in human skeletal muscles (Cai, 2007). More excitingly they tested the affects of CNTF and found that it induced committed myoblasts to dedifferentiate into mulitpotent cells. Not only could these cells restore skeletal muscles, they also have the ability to differentiate into new tissues such as neurons, glial cells, and smooth muscle cells (Cai, 2007).
By investigating the way invertebrates adapt to the stresses and strains of their environment researchers have come closer to discovering the mechanism by which cells that were previously thought to be permanently differentiated can work backwards to their original pluripotent cells. This new method for regenerative medicine is one of the many breakthroughs in modern science. Dedifferentiation of one’s own cells offers many advantages over other researched treatments. It poses little threat of initiating an immune response and it is morally more correct then utilizing human embryonic stem cells.
Reference:
CAI, S., FU, X., SHENG, Z. (2007). Dedifferentiation: A New Approach in Stem Cell Research. BioScience, 57(8), 655. DOI: 10.1641/B570805
Additional related articles:
Mammalian myotube dedifferentiation induced by newt regeneration extract
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