COMMUNICATION WITH OTHER CELLS

BLOG III ASSIGNMENT

SENSORY NEURONES

1) Under what conditions would this interaction/ communication occur? Communication between the sensory system and photoreceptorcells ofDrosophila melanogaster occur when the sensory system detects carbon dioxide (CO2) via specialized taste neurons. A novel taste modality is identified, which is the taste of carbonated water.

2) How is this interaction initiated?The Drosophila eye emerges during the late larval stage and pupalstage from a monolayer epithelium called the eye antenna imaginal disc. The morphogenic furrow is a wave of differentiation sweeping across the eye imaginal disc from posterior to anterior initiating sequential differentiation at each line of cell it passes. The morphogenic furrow is initiated and pushed by a hedgehog signal that is short range and in induces a long range Dpp signal to induce neurogenesis while the Dpp signal secreted from the anterior margin of the eye imaginal disc.

3) What is the process of the interaction/ communication? Once the morphogenic furrow passes a point in the eye imaginal disc, it creates a cluster of proneural cells resembling rosettes, and a single cell out of this cluster is selected to become the founder cell, R8. The rest of the photoreceptor cells are specified with the help of R8, using a network of molecular interactions. Cell junctions are actively reorganized. 4) What is the end result of the interaction/ communication? Sequential activation of different transcription factors lead to regional or stochastic determination of photoreceptor sub-types. Outer photoreceptor (R1-6) express dim light sensitive rhodopsin. Inner photoreceptor cells express either UV sensitive rhodopsin or R4 where blue sensitive rhodopsin R5 is always accompanied by R8.

SKELETAL MUSCLE

1. Under what conditions would this communication occur? Although the life span of the fruit fly is short (2-3 months), muscle dysfunction due to ageing still occurs. Changes in endocrine signaling and the endocrine environment of the skeletal muscle of the drosophila melanogaster occurs during sarcopenia. Sarcopenia, which is the degenerative loss of skeletal is driven by changes in both extrinsic and intrinsic factors, one being endocrine regulation of muscle homeostasis. This causes the mitochondria to not function as efficiently as they usually do to provide energy to the Drosophila muscle cells. There is a decline in the production of anabolic cytokines, including IGF1, which leads to a decrease in myofibrillar production. Muscles are less responsive to anabolic and catabolic stimuli. One of the catabolic hormones glucorticoids, have reduced effect in muscles. The function of the glucorticoids are produced in the adrenal cortex, mobilized amino acids from muscle protein to favour gluconeogenesis in the fasting state, inhibit protein synthesis in the muscle and ehance proteolysis. Additionally, FOXO and 4E-BP signaling in muscles activates the lysosome system of protein degradation in the retina and also the brain and adipose tissue reducing accumulation of protein in all the tissues mentioned.

2. How is the communication/interaction initiated? Long distance communication is also known as endocrine signaling, achieved through endocrine cells.This type of signaling control the behavior of the organism as a whole. Endocrine cells secrete hormones, which travel through the bloodstream, carrying the signal to target cells such as photoreceptor cells, skeletal muscle cells. Each of these target cells have receptors to which the specific hormone binds. Long distance communication between these cells occur.

3. What is the process of this interaction/communication? Photoreceptor cells secrete hormones into the blood. These hormones signal only specific target cells, in this case skeletal muscle cells, which recognize them by their receptors binding to the hormone. The receptor pulls the hormones from the extracellular fluid.

4. What is the end result of this interaction/communication? The wings of the fruit flies usually are capable of beating up to 220 times per second. Normally, the muscle cells contain a high density of mitochondria which supply large quantities of MgATP fuel required for energetically costly flight. But due to sarcopenia, there is a reduction in mitochondrial function, and therefore in incapable of providing the high energy requirements needed for flight.

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