Loading...

BIO310: Developmental Biology

Unit 7: Very Late - And Post Embryonic Development   We have not yet covered one type of development that is extremely important for creating the next generation: the differentiation of sexes and the development of sexual characteristics and organs.  This process is known as sex determination, and, depending on the organisms involved, it can be determined or influenced by environmental as well as genetic factors.

Although the most dramatic types of development have already occurred in most organisms during their time as embryos, development itself does not necessarily end once organisms are hatched, born, or otherwise recognized as being fully-formed, independent creatures.  Some very important changes in physiology and morphology can occur on the way to—or even during—adulthood.  These changes include both metamorphosis—one of the most comprehensive reorganizations of tissues and structures possible—and regeneration.

Unit7 Learning Outcomes
Upon successful completion of this unit, students will be able to:

  • Answer questions about the various types of sex determination and development (chromosomal, environmental), including which organisms use which type of development and what chemicals, genes, proteins, and environmental cues affect these types of development.
  • Distinguish between different types of metamorphosis and regeneration; identify which groups of organisms use them; and answer questions about the molecules, genes, and structures involved in these processes.

7.1 Sex Determination   7.1.1 Chromosomal Determination   - Reading: Sinauer Associates: Professor Scott Gilbert’s Developmental Biology Companion: “Social Critique of Sex Determination Research” Link: Sinauer Associates: Professor Scott Gilbert’s Developmental Biology Companion: “Social Critique of Sex Determination Research” (HTML)
 
Instructions: This reading is optional.  Read this brief summary of an article by Eva Eicher and Linda Washburn criticizing the (inaccurate) overemphasis placed on male sexual development as an active event and female sexual development as a passive, “default” state.
 
Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

7.1.1.1 Invertebrates   - Reading: The National Institutes of Health: Professor Scott Gilbert’s Developmental Biology: “Chromosomal Sex Determination in Drosophila” Link: The National Institutes of Health: Professor Scott Gilbert’s Developmental Biology: “Chromosomal Sex Determination in Drosophila” (HTML)
 
Instructions: Read this section in its entirety along with all associated figures (Figs. 17.15-17.19).
 
Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

7.1.1.2 Mammals   - Reading: The National Institutes of Health: Professor Scott Gilbert’s Developmental Biology: “Chromosomal Sex Determination in Mammals” Link: The National Institutes of Health: Professor Scott Gilbert’s Developmental Biology: “Chromosomal Sex Determination in Mammals” (HTML)
 
Instructions: Read this section in its entirety along with all associated figures (Figs. 17.2-17.12).
 
Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

7.1.2 Dosage Compensation   - Reading: The National Institutes of Health: Professor Scott Gilbert’s Developmental Biology: “Transcriptional Regulation of an Entire Chromosome: Dosage Compensation” Link: The National Institutes of Health: Professor Scott Gilbert’s Developmental Biology: “Transcriptional Regulation of an Entire Chromosome: Dosage Compensation” (HTML)
 
Instructions: Read this section in its entirety along with all associated figures (Figs. 5.22-5.23).
 
Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

7.1.3 Unusual Sex Determination   Note: A small number of organisms in a variety of different phyla exhibit what we would consider to be uncharacteristic sex development or sexual systems: some species are simultaneous hermaphrodites; some change sex from male to female or female to male or back and forth; some, like peppermint shrimp, change sex from being male to being simultaneous hermaphrodites!  The molecular mechanisms and environmental influences behind these developmental changes are not always understood, but these sexual systems, and their potential adaptive benefits, are currently areas of considerable research interest.

  • Reading: Sinauer Associates: Professor Scott Gilbert’s Developmental Biology Companion: “Translational Regulation of Germline Sex Determination” and “Normal Hermaphroditism in Nematodes and Fish” Links: Sinauer Associates: Professor Scott Gilbert’s Developmental Biology Companion: “Translational Regulation of Germline Sex Determination” (HTML) and “Normal Hermaphroditism in Nematodes and Fish” (HTML)
     
    Instructions: Read these articles in their entirety to gain a better understanding of the complicated nature of sex determination and development.
     
    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

7.1.4 Environmental Sex Determination   - Reading: The National Institutes of Health: Professor Scott Gilbert’s Developmental Biology: “Environmental Sex Determination” and “Environmental Regulation of Normal Development” Link: The National Institutes of Health: Professor Scott Gilbert’s Developmental Biology: “Environmental Sex Determination” (HTML) and “Environmental Regulation of Normal Development” (HTML)
 
Instructions: Read all of “Environmental Sex Determination,” including Figs. 17.20-17.21. In “Environmental Regulation,” scroll down to read the brief sub-subsection entitled “Environment-Dependent Sex Determination.”
 
Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

7.2 Metamorphosis   - Reading: The National Institutes of Health: Professor Scott Gilbert’s Developmental Biology: “Metamorphosis” Link: The National Institutes of Health: Professor Scott Gilbert’s Developmental Biology: “Metamorphosis” (HTML)
 
Instructions: Read this section in its entirety along with all associated figures (Figs. 18.1-18.24).  This reading will cover subunits 7.2.1-7.2.3.
 
Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

7.2.1 Overview and Activation   7.2.2 Metamorphosis in Amphibians   7.2.3 Metamorphosis in Insects   7.2.4 Metamorphosis in Marine Invertebrates   - Reading: The Saylor Foundation’s “Metamorphosis in Marine Invertebrates” Link: The Saylor Foundation’s “Metamorphosis in Marine Invertebrates” (PDF)
                       
Instructions: Please read the entirety of the reading linked above.

7.3 Regeneration   - Reading: The National Institutes of Health: Professor Scott Gilbert’s Developmental Biology: “Regeneration” Link: Reading: The National Institutes of Health: Professor Scott Gilbert’s Developmental Biology: “Regeneration” (HTML)
 
Instructions: Read this section in its entirety along with all associated figures (Figs. 18.25-18.33).
 
Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

  • Web Media: DNATube: HHMI’s “Newt Limb Regeneration” Link: DNATube: HHMI’s “Newt Limb Regeneration” (Adobe Flash)
     
    Instructions: Watch this brief (approx. 1 minute) video showing and explaining the process of limb regeneration in amphibians.
     
    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.