avannah Oliver Bio 206 BC Conor Houlihan & Anthony Marchio Assignment #3 Topic 10: Actin Reorganization Detailed focus question: How do Rho GTPases impinge on key actin dynamic regulators during dendritic growth and remodeling in Drosophila? Introduction. To first introduce my topic, I will give a background on the activation of Rho and Ras and its effects on the four different aspects of axonogenesis (initiation, elongation, guidance, and branching.) Ran is one of the six subfamilies of small GTPases. Ran, Rho, Ras, and several other proteins act as molecular switches which influence the cycling between GDP and GTP-bound states. A. Initiation, elongation and guiding in axonogenesis 1. Five members of the Ras family (Ras, R-Ras, Rap1, …show more content…
Ras and Rho family members influence activities of Ran and Rho GTPases. (Watabe-Uchida, 2006) 3. Protein Rac1 associates with Beta-catenin on an elaborate pathway to promote dendritic growth in rat hippocampal neurons. However, in Drosophila, rac1 influences size in mushroom body neurons of the central nervous system. (Shivalkar M, Giniger E, 2012) 4. The activation of Ras downstream to the extracellular matrix creates a cascade of small GTPases which regulate axon initiation. RalA may participate in the polarized transport essential for axon initiation which could promote initial polarization. (Hall, A., & Lalli, G., 2010) 5. Guidance is directed in the axon at the tip of the axon—the growth cone. Changes in filamentous actin in the growth cone direct microtubule components which in turn influence elongation. (Hall, A., & Lalli, G., 2010) II. Abl tyrosine kinase controls dendritic morphogenesis in Drosophila. In the axons, guanine nucleotide exchange factor (GEF) called Trio is the regulator of Rho GTPases. The GEFs catalyze the exchange of GDP for GTP which will in turn control actin organization. When together, Abl and Rac have conflicting duties. Moreover, Ran promotes branch formation while Abl inhibits …show more content…
After being wounded, an accumulation of Rho family GTPases are found during single cell repair. (Verboon, Jeffrey M & Parkhurst, Susan M, 2015) 3. RhoI mutants of Drosophila have a disorganized actin cable which allows for the wound to be open for an extra 2 hours and then proceeds to close. (Verboon, Jeffrey M & Parkhurst, Susan M, 2015) 4. Inactivation of Rho and ROCK work antagonistically to Rac/ Cdc42. Because Rac and Cdc42 establish a positive-feedback loop to reinforce neuronal polarization, the disruption by inactivation of Rho and ROCK could be detrimental because of severe defects in phenotypes and outgrowth. (Hall, A., & Lalli, G., 2010) 5. As an example of the above, mice with the misregulation of Rho activity display clear guidance defects in the axonal projections of the posterior limb of the anterior commissure. (Hall, A., & Lalli, G., 2010) III. In Drosophila embryos, epithelial wound repair is achieved through two main mechanisms—contractile actomyosin cable and actin-based cellular protrusions. The Rho GTPases are active regulators of these wound repair
Barlow (1953) first postulated the existence of feature-sensitive ganglion cells in a frog’s retina based on an inhibitory-surround structure of the receptive field. He maintained that the “on-off” units of these cells triggered by the presence of a particular stimulus corresponded to certain behaviour in the frog. For example, presenting a spot of light in the visual field would cause certain neurons to fire in a particular ganglion cell, and in a live frog, would cause the frog to snap at the stimulus. Barlow concluded that these cells must be “fly detectors”. Lettvin et al. (1959) further examined the visual mechanisms of the frog and discerned fo...
...s to interfere with bonding to the receptors. The final possibility uses CNP, which downregulates the activation in MAP kinase pathways in the chondrocytes (4).
The MECP2 gene makes a protein, also called MECP2, believed to play a pivotal role in silencing, turning off or regulating the activity of other genes. The MECP2 mutation (change in the gene) causes the turn-off/regulatory mechanism to fail, allowing other genes to function abnormally(Rett Syndrome - NORD). Rett syndrome is a genetic disorder of developmental failure of brain maturation. This is thought to occur when subsets of neurons and their connections are disrupted during a dynamic phase of brain development. This deviation occurs at the end of pregnancy or in the first few months of life during the critical phases of synapse development. How mutations in MeCP2 lead to Retts is not well understood but is the focus of intense research.
“The Death of the Moth” by Virginia Woolf presses upon the matter of life and death through the author’s perspective of a mere day moth. Woolf uses the moth and its struggles as a metaphor about the inevitability of death and how humans are as susceptible to it as the smallest life forms. She paints a picture of life that is so pure that the reader has no choice but to feel pity towards the moth and its inability to do anything but try to fly. Woolf’s use of the moth as metaphor to show the purity of life is shown through her imagery and syntax.
“This knowledge will help us design drugs that mimic the viral effects on these proteins to either activate a host’s immune response or shut it down,” said Dr. Michael Gale, associate ...
The objective of this experiment is to determine what genes are responsible for the white-eye color in two strains of Drosophila melanogaster, known as the common fruit fly. Drosophila is used as the experimental organism for many reasons which include its small size, easy maintenance, short 10 day generation time, and a fully sequenced genome. The characteristics of the wild type, which is the most common phenotype found in nature, include brick red eyes, long wings, gray/tan body, and smooth bristles. Of course, there are mutations that occur that cause specific traits to deviate from the wild-type phenotype. These traits include wing length, bristle shape, body color, and eye color.
The venus flytrap is a unique plant that is known to be a carnivore. Many people are fascinated by this plant’s peculiar diet. While many people are surprised by this plant’s food, only few know how this strange plant attracts, kills, and digests their prey.
Geraldine Brooks the author of People of the Book conveys the story of Sarajevo Haggadah. In the chapter “An Insect’s Wings,” Lola, a young Jewish girl, experiences running away from Nazis and coming back to Sarajevo. In this chapter, it also shares some details of how the famed Sarajevo Haggadah was saved from WWII. This chapter shares the journey of Lola and all the unpleasant events she went through.
New Scientist 212.2835 (2011): 6. Academic Search Complete. Web. The Web. The Web.
Eagles are the embodiment of a nation’s pride and honor. They serve as symbolic beasts demonstrating power, strength, and dexterity. However, the most common term associated with these creatures is “majestic.” The Philippine Eagle, Pithecophaga jefferyi, is one such creature. Mostly known for being one of the largest eagles in the world, it is acknowledged for sporting an enormous black beak, buttery yellow feet, snowy white abdomen, and creamy brown feathers dressed from neck to tail. Most striking though may be its pale gray-blue eyes that jump out behind the sporadically flared feathers
This reduces the amount of current that would otherwise leak out of the axon and increases the distance that the current can flow passively. Myelination, aka axon insulation, increases action potential conduction up to 150m/s compared to 0.5-10m/s conduction velocities of unmyelinated axons! Speedy delivery of current information along axons is also due to the nodes of Ranvier. Nodes of Ranvier are gaps between insulated portions of the axon. The gaps create a place where the current can flow out of the axon so an action potential can be generated.
The idea of the project was to experiment breeding Drosophila Melanogaster (fruit fly) to figure out if certain genes of that species were sex linked or not (autosomal). A mono-hybrid cross and di-hybrid cross was performed. For the mono-hybrid cross, white eyed female and red eyed male were placed in one vial for them to reproduce. For the di-hybrid cross, red eyed and normal winged flies and sepia eyed and vestigial winged flies were placed in their vial to reproduce. In the mono-hybrid cross the results expected were within a 1:1:1:1 ratio. Expected results similar to the expected desired null hypothesis proposed with what the F1 parental generation breeds. The potential results would have had to have been within the ratios of 9:3:3:1. The results were clear and allowed the null hypothesis to be correct. The white eyed gene in the fruit flies is sex linked. Sepia eyes and vestigial wings are not sex linked and are examples of independent assortment.
The cytoskeleton is a highly dynamic intracellular platform constituted by a three-dimensional network of proteins responsible for key cellular roles as structure and shape, cell growth and development, and offering to the cell with "motility" that being the ability of the entire cell to move and for material to be moved within the cell in a regulated fashion (vesicle trafficking)’, (intechopen 2017). The cytoskeleton is made of microtubules, filaments, and fibres - they give the cytoplasm physical support. Michael Kent, (2000) describes the cytoskeleton as the ‘internal framework’, this is because it shapes the cell and provides support to cellular extensions – such as microvilli. In some cells it is used in intracellular transport. Since the shape of the cell is constantly changing, the microtubules will also change, they will readjust and reassemble to fit the needs of the cell.
Synaptic vesicles exist in different types, either tethered to the cytoskeleton in a reserve pool, or free in the cytoplasm (Purves, et al., 2001). Some of the free vesicles make their way to the plasma membrane and dock, as a series of priming reactions prepares the vesicular and plasma membrane for fusion (Lodish, Berk, Zipursky, Matsudaira, Baltimore, & Darnell, 2000).
Darwin’s research on insect pollination constituted specific interest in orchids and became a powerful example of natural selection over time. Orchids have evolved in various ways, primarily mimicry, that increases their reproductive success, as well as influence the evolution of other insects that mimic them. Most flowers are limited to attracting insects only with their bright inflorescences and fragrance, but orchids have evolved another tactic. Some flowers in the Orchidaceae family utilize a pseudo-copulation method where they mimic insects of the opposite sex for pollination. In addition, orchids have evolved even further to releasing the female pheromone that entices the male, also resulting in pollination. Both orchids and orchid mantises have become amazingly specialized to thrive in their environment (Dobzhansky 1973). Known for their detailed skill in mimicry, these organisms are ideal to study how visual and odor deception influence relations, specifically pollination. Mimicry has become an important strategy that these organisms have mastered, giving them a significant advantage over the competition.