questions

• Teratogen


  An agent or factor that can disrupt the normal development of an embryo or fetus, leading to congenital malformations or birth defects
• Alcohol as a teratogen


  Alcohol can interfere with gene expression: alcohol exposure can alter the expression of genes involved in critical developmental pathways, such as those regulating cell proliferation, differentiation, and patterning
• Alcohol is considered a potent teratogen
• Experiment to identify teratogens in humans or animal models


  1. Obtain fertilized eggs/embryos

  2. Divide into control and experimental groups

  3. Treat experimental group with potential teratogen

  4. Monitor development and compare to control
• Gain of function experiment to restore Sonic hedgehog (Shh) expression in Glyphosate exposed embryos


  1. Obtain fertilized chicken eggs

  2. Divide into control and experimental groups

  3. Treat experimental group with glyphosate

  4. Introduce exogenous Shh proteins into treated embryos using microinjection or electroporation

  5. Monitor Shh expression using in situ hybridization and immunohistochemistry
• Endocrine disruptor


  A substance that can interfere with the normal functioning of the endocrine system, including hormone biosynthesis, metabolism, and action
• Diethylstilbestrol (DES)


  A synthetic estrogen that was prescribed to pregnant women between 1938 and 1971 to prevent miscarriages and other pregnancy complications
• Effects of DES exposure in females


  • Structural abnormalities in the reproductive tract (e.g. T-shaped uterus, cervical ridges, vaginal adenosis)
  • Reproductive problems (e.g. infertility, ectopic pregnancies, preterm births, miscarriages)
• Experiment to investigate the effects of DES on female rodents


  1. Divide pregnant rodents into control and DES-exposed groups

  2. Monitor female offspring for reproductive tract development and function
• DES-exposed female rodents exhibited various abnormalities in their reproductive tracts, similar to those observed in DES daughters</b>
• Experiment to investigate the substance causing infertility in alien offspring


  1. Identify and isolate the substance from the soda can lining

  2. Establish a control group of healthy, fertile aliens (or appropriate model organisms)

  3. Expose different groups to varying concentrations of the isolated substance

  4. Monitor the exposed groups and control for reproductive health and offspring development

  5. Perform histological and molecular analyses to investigate potential mechanisms of action
• Mesenchymal-epithelial cell communication


  Secretion of growth factors by mesenchymal cells that can stimulate the proliferation, survival, and invasion of epithelial cancer cells
• Loss of function experiment to test the role of a cancer support cell in cancer cell proliferation


  1. Identify a specific type of cancer cell (immune cell) that contributes to cancer cell proliferation

  2. Use techniques such as siRNA or CRISPR to knock down or knockout a key gene or pathway in the cancer support cells

  3. Co-culture the genetically modified cancer support cells with cancer cells and assess the proliferation rate of cancer cells
• Gain of function experiment to test the role of a cancer support cell in cancer cell proliferation


  1. Identify a gene or pathway in the cancer support cells that is hypothesized to promote cancer cell proliferation

  2. Generate a construct to overexpress the gene of interest in the cancer support cells

  3. Co-culture the genetically modified cancer support cells with cancer cells and assess the proliferation rate of cancer cells
• Temperature-dependent sex determination (TSD)


  A mechanism where the sex of an organism is determined by the temperature during a critical period of embryonic or larval development
• Advantages and disadvantages of temperature-dependent sex determination


  • Advantage: Allows for the adjustment of sex ratios in response to environmental conditions
  • Disadvantage: May lead to a higher risk of producing a single sex in extreme temperature conditions, which can negatively impact the population's reproductive success
• Phenotypic plasticity


  The ability of an organism to change its phenotype (morphology, physiology, or behavior) in response to environmental cues or stimuli
• Advantages of phenotypic plasticity

  • Allows the organism to adapt to different environmental conditions within a single generation, without relying solely on genetic changes over multiple generations
  • Enables the organism to express the most suitable phenotype for the current environmental conditions, maximizing its fitness
• Developmental Symbiosis


  A type of symbiotic relationship where the development of one or both partners is entirely dependent on the presence of the other species
• Types of developmental symbiosis


  • Obligate symbiosis
  • Other type
• Obligate symbiosis


  The development of one or both partners is entirely dependent on the presence of the other species. Without the symbiont, the host organism cannot complete its normal development or life cycle.
• Obligate symbiosis


  • Relationship between the Hawaiian bobtail squid (Euprymna scolopes) and the bioluminescent bacterium Vibrio fischeri
• Developmental symbiosis can be seen in plants
• B.) Describe the symbiotic relationship between the Euprymna scolopes squid and the bacterium Vibrio fischeri. At what point does the relationship begin and what features do each species gain through this relationship. Be sure to include this specific process in your answer.
• Symbiotic relationship


  A close and long-term interaction between two different species
• Euprymna scolopes squid


  • Develops a specialized light organ called the "bilobed light organ" within the mantle cavity
• Acquisition of Vibrio fischeri bacteria


  Juvenile squid acquires Vibrio fischeri bacteria from the surrounding seawater environment
• Colonization of light organ


  Vibrio fischeri bacteria colonize and populate the light organ of the squid
• Bioluminescence production


  Vibrio fischeri bacteria produce bioluminescence through a process called quorum sensing
• Benefits to the squid


  • Gains the ability to produce light, which serves functions like camouflage (counterillumination), attracting prey, and communication
• Benefits to the Vibrio fischeri bacteria


  • Provided with a nutrient-rich environment inside the light organ, allowing them to thrive and reproduce
• When the relationship begins


  After hatching, the juvenile squid acquires Vibrio fischeri bacteria from the surrounding seawater environment
• Design and experiment to test the relationship between the mammalian gut and the bacteria that inhabit it


  1. Obtain two groups of genetically identical newborn mammals (e.g., mice or rats), one serving as the control group and the other as the experimental group

  2. Treat the experimental group with broad-spectrum antibiotics from birth to deplete their gut microbiota significantly

  3. Monitor the development and growth of both groups, measuring various parameters such as weight gain, organ development, immune system function, and behavior

  4. Perform analyses to compare the gut microbiota composition and diversity between the two groups using techniques such as 16S rRNA gene sequencing or metagenomics
• The experiment is designed to test the relationship between the mammalian gut and the bacteria that inhabit it