Lecture 17 Symbiosis and Immunology Flashcards
(42 cards)
What is Metagenomics?
- analysis of genetic material derived from microbial communities.
- can reveal diversity and metabolic potential of microbial communities
- culture-independent
A Metagenomic Approach
- Isolate genomic DNA
- PCR amplify SSU rRNA genes (16S rRNA in bacteria)
- Clone and sequence amplified DNA
- Compare to database of known genes
What is Mutualism?
both partners benefit (often obligatory)
- Mycorrhizal fungi and plants
- Squid and bacteria
- Coral and zooxanthellae
- Tube worms and bacteria
Describe a Signaling molecule (autoinducer)
- Diffusible- moves in and out of cells
- Low cell density, gradient favors movement out
- High cell density, gradient favors movement in and genes activated
Quorum sensing
- Vibrio fischeri
- control light production; cells produce light only if they are at a high density
Mutualism: Photosynthetic Algae and Coral
- Use energy from photosynthesis to fix CO2 into Carbohydrate
- Symbiosis disrupted by changes in ocean temperature and acidity, can cause Coral Bleaching
Mutualism: Tube Worms and Bacteria
- Giant (>1M in length) tube worms (Riftia) grow several thousand meters below the surface of the ocean, near hydrothermal vents rich in hydrogen sulfide (H2S)
- The worms have no mouth or gut.
- Tube worm uses hemoglobin to deliver H2S and CO2 to bacteria in Trophosome
- Bacteria oxidize H2S for electrons
- Electrons enter and ETC, generates a PMF to make ATP and NADPH
Describe the Immune system
- widely distributed cells, tissues, organs
- recognizes foreign substances, neutralizes or destroys
- antigens - foreign substances that provoke immune response
- antibodies - bind antigens, inactivate or eliminate
Describe Immunity
-Ability to resist disease or infection
What is Immunology
-Studies how body defends against foreign invaders, harmful substances
Describe Innate Immunity
- non-specific
- first line of defense
- fast
- no memory
- cells - macrophages, neutrophils, dendritic cells
- components - anatomical features, complement, toll-like receptors, cytokines
Leukocytes
- The cells responsible for both innate and adaptive immune responses are the leukocytes (White blood cells)
- All leukocytes originate from pluripotent stem cells in the bone marrow
Five Major Types of Leukocytes
-Basophils, Eosinophils, Neutrophils,
Monocytes - mature into macrophages or dendritic cells
Lymphocytes - T,B and Natural Killer (NK) cells
-Macrophages, Neutrophils and Dendritic Cells are the major cells of the innate immune response.
Macrophages
- From monocytes in blood
- Enter, reside in tissue
What are the Three Major Functions of Macrophages
- Phagocytic
- Note: Dendritic cells and Neutrophils also phagocytic
- Engulf and destroy pathogens
- Use reactive oxygen and nitrogen species
- Hydrogen peroxide
- Nitric Oxide
- Antigen presentation
- Make cytokines
Phagocytosis
- Pseudopodia
- Phagosome
- Lysosome
- Phagolysomsome
What are the Major Antigen Presenting Cells and what doe they do?
- Macrophages, Dendritic Cells, and B cells
- Cells that can take in protein antigens, process them, and present peptide fragments of the antigen bound to MHC molecules to T cells
Physical Barriers of the Innate Immune Response
- Skin and Mucous Membranes
- Normal microflora at these sites also protect by competing with potential pathogens
Chemical Barriers of the Innate Immune Response
- Acidic pH of stomach
- Lysozyme in tears and breast milk
- Defensins - antimicrobial peptides
Other components - Complement, Toll-like receptors, Cytokines
Innate Immunity: The Complement System
- > 30 serum proteins
- Activated by enzymatic cleavage
- “complements” activity of antibody
Functions:
- opsonins - coat microbes for phagocytosis (Ex: C3b)
- Chemotactic factors - PMN migration from blood to infection (Ex: C5a)
Toll-Like Receptors (TLRs)
- Pattern recognition receptors
- At least 10 distinct receptors in family
- Bind Pathogen-Associated Molecular Patterns (PAMPs)
PAMPs
- TLR4 - LPS
- TLR2 - peptidoglycan
- TLR3 - dsRNA
- TLR5 - flagellin
Interleukins (IL)
- stimulate cell growth, differentiation, proliferation
Tumor Necrosis Factor (TNF)
- increases vascular permeability, induces fever, activates B and T cells
