The article reviewed in this summary is
Hayes, T.B., Khoury, V., Narayan, A., Nazir, M., Park, A., Brown, T., Adame, L., Chan, E., Buchholz, D., Stueve, T., and Gallipeau, S. 2010. Atrazine induces complete feminization and chemical castration in male African clawed frogs (Xenopus laevis). Proceedings of the National Academy of Sciences 107: 4612-4617.
The authors have assigned key words described throughout this article including amphibian decline, endocrine disruption, pesticide and sex reversal. The larger or global context for the research conducted in this article is that the pesticide Atrazine is widely utilized across the entire world, contaminating water sources by mobilizing through rainfall, disrupting habitats and impacting organisms by acting as an endocrine disruptor. The research specifically described in this article is how continued Atrazine exposure affects the reproductive development of a male population of African clawed frogs. This research explores the issue of atrazine exposure contributing to the generation of sex reversed frogs in a male population. The article addresses previous studies where Atrazine had no significant effects on amphibians in specific conditions. It also includes other studies where this pesticide proved to be an endocrine disruptor; reducing testosterone and promoting demasculinization and feminization in amphibians.
Atrazine exposure is a worldwide issue, but the geographical area used to collect the amphibians used for this research was in Tecalote Creek in San Diego County. The types of data used in this research include larynx structure or development, presence of visible nuptial pads and breeding gland size, testosterone levels, spermatogenesis, aromatase expression, matin...
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...o states another important finding that the decreased fertility and competition for mates indicates that endocrine disruptors may affect population levels and lead to declines in amphibians.
The reference list of this article includes 54 references. The reference cited most often throughout the article is reference number 10,
Hayes et al. 2002. Hermaphroditic, demasculinized frogs after exposure to the herbicide atrazine at low ecologically relevant doses. Proc Natl Acad Sci USA 99: 5476–5480.
Prior to reading this article there were many words I was unfamiliar with. These words include aromatase which is an enzyme involved in the production of estrogen by converting testosterone to estradiol, nuptial pads which is a sex characteristic found on the hands of male amphibians and larynx, an organ located in the neck which contains the vocal chords.
The rhetorical occasion of this excerpt is to inform others about the dangers of chemicals on earth’s vegetation and animal life.
Amalin, D.M., Peña, J.E., Duncan, R., Leavengood, J., Koptur, S. (2009): Effects of Pesticides on the Arthropod Community in the Agricultural Areas near the Everglades
The pesticide DDT banned in 1987 was a detrimental to the environment leading to it to be banned in 1987. DDT remains in the soils for a long period of time. The chemicals affect the ecology of the soil and water run off causing contamination of livestock and native animals and aquatic species. Studies indicated a range of human health impacts from DDT including cancers, infertility, miscarriage and nervous system impairment. The social and economic impact of DDT use in viticulture was significant.
Retrieved on June 12, 2006 from the World Wide Web at: http://www.blackwell-synergy.com/links/doi/10.1111/j.1745-6622.1997.tb00124.x.
The scientists found the dinosaur DNA in blood in mosquitoes who were fossilized in amber. There were pieces missing in the dinosaur sequence, so the scientists used a frogs DNA to fill in the gaps. They were then able to produce a dinosaur and alter their chromosomes. The scientists made all the dinosaurs female so the dinosaurs couldn’t breed on their own. What the scientists didn’t think through was that certain frogs can change their sex if the opposite sex is absent in the environment. When the scientists gave the frog DNA to dinosaurs, they also gave the dinosaurs the ability to change sex as well. Now there were female and male dinosaurs, and the dinosaurs were able to produce on their own. Like Dr. Malcolm said, “Life
The second part of this lab was a computer simulation program to illustrate a frog’s electrocardiogram using various drugs in an isolated setting. The computer program entitled “Effects of Drugs on the Frog Heart” allowed experimental conditions to be set for specific drugs. The different drugs used were calcium, digitalis, pilocarpine, atropine, potassium, epinephrine, caffeine, and nicotine. Each of these drugs caused a different electrocardiogram and beats per minute reading. The calcium-magnesium ration affects “the permeability of the cell membrane”(Fox). When calcium is placed directly on the heart it results in three physiological functions. The force of the heart increases while the cardiac rate decreases. It also causes the appearance of “ectopic pacemakers in the ventricles, producing abnormal rhythms” (Fox). Digitalis’ affect on the heart is very similar to that of calcium. It inhibits the sodium-potassium pump activated by ATP that promotes the uptake of extracellular calcium by the heart. This in return strengthens myocardial contraction (Springhouse). Pilocarpine on the other hand
The Methodology used to gather information for this paper was found through various sources. The sources used are all verifiable and established informational resources including (but not limited to) the following; course textbooks, books, journals, and online databases.
Hansen, M., ABA Journal. Jul97, Vol. 83 Issue 7, p20. 2p. 1 Color Photograph, 1 Chart.
Stokes, W.S. “Animals and the 3 R’s on Toxicology Research and Testing.” Human and Experimental Toxicology December 2015: 7. Academic Search Premier. Web. 14 February
55.2 (March 2011): 39-45. Academic Search Complete. EBSCO. Web. The Web. The Web.
Pesticides that behave like the female hormone estrogens can have serious effects on reproductive success and function on animal exposed to them. Reproductive success or fitness is defined by having live reproductively capable off...
There is also a new method that scientists are trying to use for the conservation of endangered animals. Sperm freezing, artificial insemination and embryo transfer are routine methods in several domestic species and applications of these techniques may also be used in wild species. However, reproduction physiology is very specific and before any technique can successfully be applied, the main reproduction features must be examined in target species or at least in a nearby relative species.
In addition to their many adverse effects on the human body, flame retardants also represent a hazard to the environment. They have similar effects on other animals as they do on humans. Even after certain types of flame retardants’ production was stopped after the discovery of their dangerous effects, they are still being detected in the environment, and are therefore still disturbing the ecosystem. (Guigueno,