BIOL 200 EXAM 4 LECTURE + READING NOTES

Developmental Biology

Body Orientation in Organisms

  • Anterior: Towards the head

  • Posterior: Towards the tail

  • Dorsal: Towards the back

  • Ventral: Towards the belly

Developmental Patterning in Flies

  • Factors involved in developmental patterning:

    • Signals/Inducers: Molecules that can influence the development.

    • Receptors: Proteins that receive signals.

    • Transcription Factors: Proteins that regulate gene expression.

    • Cytoplasmic Determinants: Maternal factors contributing to development.

Identifying Developmental Genes

  • Methods to determine genes involved:

    • Genetic screens

    • Find it/Lose it/Move it strategy

    • Find it experiment using FISH (Fluorescence In Situ Hybridization):

      • Visualizes mRNA with a complementary probe.

      • Does not hybridize with DNA since DNA is double-stranded.

      • Presence of a fluorescent signal indicates the location of target mRNA.

    • Limitations:

      • Cannot be used in living cells without compromising cell integrity.

Prediction on Bicoid mRNA

  • Bicoid mRNA: Critical for anterior development.

    • If functional, should be localized to the anterior end in early Drosophila development.

Drosophila Development Features

  • Early developmental stage: Syncytium (multiple nuclei in shared cytoplasm).

    • Diffusion occurs without membranes between nuclei.

Protein Binding Factors

Binding Probability

  • Two key factors influencing protein binding to DNA:

    • Concentration: Level of protein present.

    • Affinity: Strength of the interaction.

  • Combined influence of affinity and concentration determines the binding probability.

Flower Development in Arabidopsis

Model System Criteria

  • Criteria for selecting Arabidopsis as a model:

    • High offspring yield

    • Ease of creating mutants without ethical concerns

    • Small genome

    • Cost-effective laboratory growth

    • Capable of self-pollination / easy to crossbreed

    • High natural genetic variation.

Sepal vs. Carpal Cells

Differences in Development

  • Differential Gene Expression: Variations caused by cytoplasmic determinants or inductive signals.

ABC Model of Flower Development

  • Gene Functions:

    • A: Forms sepals

    • A+B: Forms petals

    • B+C: Forms stamens

    • C: Forms carpals

  • Role of MADS Box transcription factors in regulating flower organ development.

Ecological Interactions

Types of Interactions

  • Mutualism: Both species benefit.

  • Commensalism: One benefits, the other is unaffected.

  • Consumption: One species benefits at the other's expense (e.g., predation).

  • Amensalism: One species is harmed, the other is unaffected.

Extreme Mutualism Case Study

  • Nodulation: Relationship between legumes and rhizobia.

    • Legume provides carbon (sugars)

    • Rhizobia provide nitrogen (ammonia).

Plant-Nutrient Interactions

  • Questions regarding nitrogen storage and availability in plants in response to increased CO2 levels and fertilizer usage.

Microbe Engineering for Fertilizer Reduction

Steps in Microbe Engineering

  1. Develop: Culture, isolate, and gene edit.

  2. Characterize: Nitrogen fixation capabilities and biosafety.

  3. Product Evaluation: Enhanced efficiency in nutrient fixation.

Advantages Over Plant Engineering

  • Faster generation time for microbes.

  • Lower consumer resistance to engineered microbes vs. engineered plants.

  • Potential applications across multiple plant varieties.

Nitrogen Fixation and Klebsiella

Genetic Regulation

  • Klebsiella regulates nitrogen fixation based on NH4+ levels.

    • High NH4+ levels induce feedback mechanisms to inhibit NifA transcription factor.

Ethical Concerns

  • Potential benefits vs. risks associated with bioengineering in agriculture.

Toll Receptor in Immune Response

Toll Protein Functionality

  • Toll-like receptors (TLRs): Function in pathogen detection; specifically important in Drosophila's immune response.

Signal Transduction

  • Sequence of events leading from pathogen entry to activation of antifungal responses.

Immune System Responses

Types of Immunity

  • Innate Immunity: Fast, general, no memory.

  • Adaptive Immunity: Slower, specific, includes memory to pathogens.

Inflammatory Response Sequence

  1. Pathogen entry

  2. Clot formation by platelets.

  3. Signal gradient from macrophages.

  4. Blood vessel dilation via mast cell degranulation.

  5. Recruitment and activity of neutrophils.

Human Microbiome Insights

  • Bacterial diversity significantly decreases closer to host cells, indicating selective communication.

Breast Milk and Inflammatory Responses

  • Composition and benefits of human milk, focusing on HMOs and their role in sustaining an infant's immune health.

Immune System Regulation

  • Impact of immune dysregulation leading to allergies and autoimmune diseases.

Review of Key Concepts in Development and Immunity

  • Drosophila embryonic development key factors (bicoid, hunchback) and their significance in studying genetics and regulatory mechanisms.

  • Similarities in developmental processes across organisms including flowering plants and immune system responses.

Flowering Plant Reproduction

  • Overview of the floral meristem's role in producing flowers and the ABC model explaining organ differentiation.

Nitrogen Fixation Overview

  • Basic process of nitrogen fixation and significance of legumes in restoring nitrogen in soils to support plant growth.

CRISPR-Cas9: A revolutionary tool in genetic engineering.

  • Mechanism: Utilizes a guide RNA to direct the Cas9 nuclease to a specific DNA sequence, resulting in a double-strand break in the DNA.

  • Applications:

    • Gene editing: Can be used to knock out genes or insert new genetic material.

    • Research: Enables precise modifications for functional studies in various organisms.

    • Medicine: Potential to correct genetic disorders and engineer immune cells for targeted therapies.

    • Agriculture: Used to create crops with desirable traits, such as disease resistance.

  • Considerations:

    • Ethical concerns regarding the implications of altering the germline in humans.

    • Off-target effects: Potential unintended edits in non-target regions of the genome, requiring thorough validation.

CRISPR-Cas9: A revolutionary tool in genetic engineering.

  • Mechanism: Utilizes a guide RNA to direct the Cas9 nuclease to a specific DNA sequence, resulting in a double-strand break in the DNA.

  • Applications:

    • Gene editing: Can be used to knock out genes or insert new genetic material.

    • Research: Enables precise modifications for functional studies in various organisms.

    • Medicine: Potential to correct genetic disorders and engineer immune cells for targeted therapies.

    • Agriculture: Used to create crops with desirable traits, such as disease resistance.

  • Considerations:

    • Ethical concerns regarding the implications of altering the germline in humans.

    • Off-target effects: Potential unintended edits in non-target regions of the genome, requiring thorough validation.