BIOL-UA 995 “Becoming a Scientist”
Module II Writing Assignment: Identifying Your Scientific Inspiration and Question
1. Inspirational Paper:
A fundamental goal of developmental biology is to ascertain the underlying mechanisms that allow patterning, the process by which a group of equivalent cells are induced to form complex organizations of cell fates in space and time. One prevailing theory used to explain this phenomenon is the morphogen hypothesis. In this model, a diffusable molecule (morphogen) establishes a continuous gradient, and differential sensitivities of target genes to this molecule allows this continuous signal to specify discrete cell fates. The achetypal example in biology of a morphogen is bicoid. Bicoid (Bcd) is a transcrition factor that is expressed from a maternally deposited bcd mRNA that is normally localized to the anterior pole of the D. melanogaster embryo. A true morphogen must also be sufficient to establish the patterning; this is shown for Bcd by ecotopic microinjection of bcd mRNA in the embryo which induces formation of anterior structures.
Ochoa-Espinosa et al. tested the morphogen hypothesis with regards to bicoid by asking whether different concentration thresholds within the Bcd gradient actually …show more content…
conclude that their paper is not an overhaul of the morphogen hypothesis, as they show how particular aspects of the model are represented in early D. melanogaster body patterning. For example, differential sensitivities are represented in some target genes and Bcd does directly activate target genes in a concentration dependent manner. However, what Ochoa et al. have found is that the Bcd. concentration gradient is not the primary means of body patterning or positional specification. They propose an integrated model where the Bcd and Hb (both from maternally deposited mRNA) gradients work in tandem with the terminal Torso (Tor) system and ubiquitously expressed repressors to establsih a complex positioning
Module II Writing Assignment: Identifying Your Scientific Inspiration and Question
1. Inspirational Paper:
A fundamental goal of developmental biology is to ascertain the underlying mechanisms that allow patterning, the process by which a group of equivalent cells are induced to form complex organizations of cell fates in space and time. One prevailing theory used to explain this phenomenon is the morphogen hypothesis. In this model, a diffusable molecule (morphogen) establishes a continuous gradient, and differential sensitivities of target genes to this molecule allows this continuous signal to specify discrete cell fates. The achetypal example in biology of a morphogen is bicoid. Bicoid (Bcd) is a transcrition factor that is expressed from a maternally deposited bcd mRNA that is normally localized to the anterior pole of the D. melanogaster embryo. A true morphogen must also be sufficient to establish the patterning; this is shown for Bcd by ecotopic microinjection of bcd mRNA in the embryo which induces formation of anterior structures.
Ochoa-Espinosa et al. tested the morphogen hypothesis with regards to bicoid by asking whether different concentration thresholds within the Bcd gradient actually …show more content…
conclude that their paper is not an overhaul of the morphogen hypothesis, as they show how particular aspects of the model are represented in early D. melanogaster body patterning. For example, differential sensitivities are represented in some target genes and Bcd does directly activate target genes in a concentration dependent manner. However, what Ochoa et al. have found is that the Bcd. concentration gradient is not the primary means of body patterning or positional specification. They propose an integrated model where the Bcd and Hb (both from maternally deposited mRNA) gradients work in tandem with the terminal Torso (Tor) system and ubiquitously expressed repressors to establsih a complex positioning