DEV3011 Lecture 2: Differential Gene Expression Techniques

Introduction to Gene Expression Analysis Techniques

  • Overview of the lecture content involving various techniques for analyzing differential gene expression.

  • Importance of understanding why certain techniques are chosen for different analyses.

  • Objective: By the end of the lecture, students should be able to describe principles and practices in classical molecular biology methods and newer methodologies.

Structure of the Lecture

  • Preparation of slides, indication of a general overview rather than detailed examination of every slide.

  • Mention of techniques like Southern and Northern blots but more in-depth focus on Western blotting.

  • Emphasis on the decision-making process regarding the choice of technique based on the molecule of interest.

Developmental Biology Context

  • Emphasis on the transition from a single cell (zygote) to a multicellular organism through developmental stages:
      - Zygote
      - Blastocyst
      - Implantation
      - Gastrulation
      - Post-gastrulation differentiation into various cell types

  • Importance of understanding gene expression changes during these stages of development.

Molecular Changes Driving Differentiation

  • Explanation of how specific gene expressions lead to cell type differentiation.

  • Role of transcription factors and epigenetic regulation as key drivers in gene expression.

  • Control genes: Ubiquitously expressed genes acting as controls in experiments.

Identifying Gene Expression Changes

  • Discussion on identifying which molecules to analyze: DNA, RNA, or proteins.

  • Insights into developmental processes by understanding gene expression profiles at different stages:
      - Cardiac versus skeletal muscle cell differentiation.

Techniques for Analyzing DNA

  • Human Genome Project:
      - Overview of the sequencing of the human genome and its significance.
      - Historical context of the project costing billions, comparing to modern sequencing technologies.

  • Chromosomal alterations identification:
      - Example: Down syndrome (Trisomy 21) identified in the late 1950s.

  • Karyotyping as a method to see chromosomal structure and identify abnormalities through visual representation.

Southern Blotting Technique

  • Developed by Edwin Southern in 1975.

  • Explanation of DNA-DNA hybridization to determine the presence of specific DNA sequences within a genome.

  • Information regarding the ongoing relevance despite newer techniques.

Advanced DNA Sequencing Techniques

  • Overview of DNA sequencing technology advancements since the 1970s to modern high-throughput sequencing techniques.

  • DNA sequencing analysis challenges: vast information and the necessity for high-power analysis tools.

  • Interpretation of mutations through chromatograms.

Prenatal Testing and Application of Sequencing

  • Non-invasive prenatal testing (NIPT) to assess aneuploidy in chromosomes.
      - Importance of assessing chromosomes 13, 18, and 21 given their associated developmental issues.

  • Consideration of maternal age-related meiotic fidelity issues associated with chromosomal abnormalities.

RNA Analysis Techniques

  • Function of RNA in amplifying DNA and controlling gene expression:
      - Highlighting the importance of RNA as an intermediary.

  • Classical methods for detecting RNA:
      - Northern blotting as analogous to Southern blotting but focused on RNA detection.

  • The significance of controls in RNA expression analysis.

Case Study: Trisomy 21 Gene Expression Analysis

  • The impact of trisomy 21 on gene expression across 310 genes.

  • Methodologies like Northern blots and RT-qPCR for assessing gene expression related to developmental stages and phenotypic outcomes.

Modern Gene Expression Techniques

  • Introduction to reverse transcription polymerase chain reaction (RT-PCR) and quantitative PCR (qPCR):
      - Steps involved in converting RNA to cDNA and subsequent amplification.
      - Explanation of CT value importance for quantification of RNA.

Microarray and RNA Sequencing Approaches

  • Introduction to microarrays:
      - Overview of hybridization techniques to analyze thousands of genes simultaneously.

  • RNA sequencing (RNA-seq):
      - Current state-of-the-art technology for assessing the entire complement of RNA in a sample.
      - Case studies utilizing RNA-seq data to identify differential gene expression at a single-cell resolution.

Bioinformatics Requirements

  • The need for specialized bioinformatics skills to handle the large data sets produced by RNA-seq.

  • Examples of questions that can be posed through big data analysis in gene expression.

Visualizing Gene Expression

  • Discussion on RNA in situ hybridization as a visual technique for assessing transcript localization.

  • Challenges and opportunities in visualizing proteins through combination of Western blotting and microscopy techniques.

Proteins and Their Role in Gene Expression

  • Transition from RNA to protein, exploring how proteins embody the functional outcomes of gene expression.

  • Western blotting methodology:
      - Explanation of protein separation, transfer to membranes, and probing with antibodies for specific protein detection.

Immunofluorescence and Conducive Visualization Techniques

  • Techniques for visualizing protein localization in cells and tissues:
      - Use of fluorescent and colorimetric tagging methods.
      - Applications in developmental biology to visualize protein expression within various cellular contexts.

Developmental Models and Reporter Systems

  • Use of transgenic animal models to track gene expression during development.

  • The relevance of CRISPR-Cas9 and other gene editing technologies:
      - Fast evolution and wide application in contemporary gene expression studies.

Conclusion of Techniques

  • Recap on strategies for analyzing gene expression:
      - Which molecule to test, the appropriate technique based on samples, and resolution required.

  • Emphasis on evolving technologies enhancing our molecular understanding of developmental biology.

  • Summary of techniques including Southern, Northern, Western blots, qPCR, microarrays, RNA-seq, and in situ hybridization.