micro RNAs (miRNAs) are small non-coding RNas with approximately 20 nucleotides in length. They control gene expression during post-transcription by binding to 3’ or 5’ untranslated regions of the target mRNAs, which prevent translation, or mRNA degradation. The first miRNA known as Lin-4 was discovered in the nematode C. elegans in 1993 by a joint effort of Victor Ambros’s and Gary Ruvkun’s laboratories (Bartel DR 2004; Lee RC 1993). In C. elegans, the temporal developmental pattern of all larval stages were tightly controlled by the heterochromin genes. Among these genes is Lin-4, which was discovered by the isolation of a null mutation that caused a failure during temporal development (Horvitz HR 1980; Chalfie M 1981). Lin-4 mutant animals were missing some adult structures, were unable to lay eggs, and suffered from developmental defects. This study concluded that Lin-4 is essential …show more content…
In 1987, Fergusson et al., (from Hortitz’s lab) found that a mutation of the Lin-14 ¬gene caused the opposite phenotype of the Lin-4 mutant worms (Lee RC 2004, Ferguson EL1987). These studies suggested that Lin-4 could be the negative regulator of Lin-14 (Lee RC 2004). Following these findings, Ambros and his colleagues, Roslind Lee and Rhonda Feinbaum, found a 700bp fragment encoded in the Lin-4 gene which did not have the conventional start and stop codonsAs a result of their subsequent investigation, they generated a mutation in the putative ORFs; however, the Lin-4 function remained unchanged. Ambros then concluded that Lin-4 contained no coding region for protein (Lee RC 1993 and 2004). In addition, they found two very small Lin-4 transcripts with only 61 and 22 bp lengths (Lee RC 1993). While
"The Species of the Secondary Protein Structure. Virtual Chembook - Elmhurst College. Retrieved July 25, 2008, from http://www.cd http://www.elmhurst.edu/chm/vchembook/566secprotein.html Silk Road Foundation. n.d. - n.d. - n.d.
Cain, M. L., Urry, L. A., & Reece, J. B. (2010). Campbell Biology. Benjamin Cummings.
Ross Wolff, Jennifer, and David Zarkower. "Somatic Sexual Differentiation in Caenorhabditis Elegans." Current Topics in Developmental Biology 83 (2008): 1-39. Web. 28 Feb. 2014. .
Robert Warren, Lisa Nagy, Jane Selegue, Julie Gates, and Sean Carroll produced this experiment that wanted to examine homeotic gene expression in butterflies. The hypothesis they tested was do homeotic genes have driven morphological change or do the homeotic genes provide a pre-existing plan where insects segment diversity evolved. The genes Antp, Scr, Abd-A, and Ubx were isolated from a cDNA library and were used to explore differences in limb and wing numbers between flies and butterflies. Where Ubx and Abd-A are expressed, the limb and wing numbers arose. They started to wonder if the expression of BX-C genes were different in butterflies (P.Coeni) and fruit flies (drosophila). When they did tests, they saw that conservation of BX-C and ANT-C homeotic gene expression are fundamentally similar and don’t explain the differences in appendages in each species. They looked into embryogenesis, and at 20% of the embryogenesis of butterflies, they saw Abd-A protein and RNA are expressed in the anterior and abdominal segments. High levels of Antp expression are seen in the thorax. Past the 20% mark of embryogenesis, the patterns seen of Abd-A, DII, and Antp expression differed extremely - no DII or Antp were expressed in the abdominal proleg.
In “The Fish” by Elizabeth Bishop, the narrator attempts to understand the relationship between humans and nature and finds herself concluding that they are intertwined due to humans’ underlying need to take away from nature, whether through the act of poetic imagination or through the exploitation and contamination of nature. Bishop’s view of nature changes from one where it is an unknown, mysterious, and fearful presence that is antagonistic, to one that characterizes nature as being resilient when faced against harm and often victimized by people. Mary Oliver’s poem also titled “The Fish” offers a response to Bishop’s idea that people are harming nature, by providing another reason as to why people are harming nature, which is due to how people are unable to view nature as something that exists and goes beyond the purpose of serving human needs and offers a different interpretation of the relationship between man and nature. Oliver believes that nature serves as subsidence for humans, both physically and spiritually. Unlike Bishop who finds peace through understanding her role in nature’s plight and acceptance at the merging between the natural and human worlds, Oliver finds that through the literal act of consuming nature can she obtain a form of empowerment that allows her to become one with nature.
Nikitina, E. G., Urazova, L. N., & Stegny, V. N. (2012). MicroRNAs and Human Cancer.Experimental Oncology, 34(1), 2-8. Retrieved from http://archive.nbuv.gov.ua/portal/chem_biol/eol/2012_1/002.pdf
Zhenghou, Henan. "Identification of Small Non-coding RNAs in the Planarian Dugesia Japonica via Deep Sequencing." National Center for Biotechnology Information. U.S. National Library of Medicine, 8 Mar. 2012. Web. 18 Mar. 2014. .
...39-0512-6_10.Use of Genome-Wide RNAi Screens to Identify Regulators of Embryonic Stem Cell Pluripotency and Self-Renewal. Zheng X1, Hu G.
All references and resources are taken from the Public Library of Science, Biology March 2004 issue and from Science March 16, 2004
Antisocial personality disorder is a personality disorder marked by a general pattern of disregard for a violation of other people’s rights. Explanations of antisocial personality disorder come from the psychodynamic, behavioral, cognitive, and biological models. As with many other personality disorders, psychodynamic theorists propose that this disorder starts with an absence of parental love during infancy leading to a lack of basic trust. In this view, the children that develop this disorder respond to early inadequacies by becoming emotionally distant, and they bond with others through use of power and destructiveness. Behavioral theorists have suggested that antisocial symptoms may be learned through modeling, or imitation. As evidence, they point to the higher rate of antisocial personality disorder found among the parents of people with this disorder. Other behaviorists suggest that some parent’s unintentionally teach antisocial behavior by regularly awarding a child’s aggressive behavior. The cognitive view says that people with this disorder hold attitudes that trivialize the importance of other people’s needs. Cognitive theorists also believe that these people have a genuine difficulty recognizing a point of view other than their own. Finally studies show that biological factors may play an important role in developing antisocial disorder. Researchers have found that antisocial people, particularly those with high impulse and aggression, display lower serotonin activity and has been linked this same activity with other studies as well.
Telomere are special DNA structure that consist of repetitive nucleotide sequences, which serves as a “cap” to protect the ends of the chromosomes. These repetitive sequences can range from thousands of base pairs in Vertebrates to about a few hundreds of base pairs in yeast cells (Oeseburg, et al. 2009). Located at the ends of the chromosomes, the telomeres serves as a biological life line for cells. Once the telomeres reach a certain length, the cell will cease to divide. Oeseburg, et al (2009) suggested that the telomere has a crucial length, once reached, it could result in chromosome end-to-end fusion and chromosome dysfunction; which may eventually lead to cell apoptosis, c...
Almost all biology students learn the fundamentals of gene expression, DNA contains information which is transcribed into RNA to create protein. Students however, are not taught of RNA Interference, the biological process where RNA molecules inhibit a gene’s expression, RNAi for short. While RNAi is a fairly new discovery, its use in modern biological research is groundbreaking. RNA Interference works by binding Double-stranded RNA molecules (siRNA) to a complementary messenger RNA. The enzymes Dicer and Slicer then cleave the chemical bonds which hold the messeger RNA in place and prevent it from delivering protein silencing instructions thus, the term, Gene Silencing. This phenomenon was first discovered by Richard Jorgensen in 1990 when he was trying to produce deeper purple colored petunias by introducing more purple pigment genes to the flower. To his surprise, the purple petunia turned completely white and got the opposite of his predicted result. At the time Jorgensen coined this effect, “Cosuppression”. It was not until 1998 that Andrew Fire and Craig, C Mello explained the process of RNAi and discovered its use in Caenorhabditis elegans (C. Elegans). In 2006 Fire and Mello won the Nobel Prize in Physiology or Medicine “for their discover of RNA Interference – gene silencing by double stranded RNA”. They utilized the nematode, C. Elegans due to its whole genome being sequenced. This unique characteristic allows for every gene to be tested
Truth Wins OUt. “Dr. Dean Hamer (Molecular Biologist) .” truthwinsout.org. N.p., 31 Jan. 2008. Web. 26 Mar. 2012. .
The. San Francisco: Benjamin Cummings, 2002. Print. The. The "Epigenetics" of the "Epigenetic PBS. PBS, 09 Jan. 2000.
Distinct characteristics are not only an end result of the DNA sequence but also of the cell’s internal system of expression orchestrated by different proteins and RNAs present at a given time. DNA encodes for many possible characteristics, but different types of RNA aided by specialized proteins sometimes with external signals express the needed genes. Control of gene expression is of vital importance for an eukaryote’s survival such as the ability of switching genes on/off in accordance with the changes in the environment (Campbell and Reece, 2008). Of a cell’s entire genome, only 15% will be expressed, and in multicellular organisms the genes active will vary according to their specialization. (Fletcher, Ivor & Winter, 2007).