Homework 1 is posted and due 917 Bonus

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Homework #1 is posted and due 9/17 Bonus #1 is posted and due 10/24

Homework #1 is posted and due 9/17 Bonus #1 is posted and due 10/24 Discussions started this week

Why so many steps?

Why so many steps?

Multiple steps allow for signal specificity. Different relay molecules lead to different responses

Multiple steps allow for signal specificity. Different relay molecules lead to different responses

Multiple steps allow for signal amplification: Calcium is a simple method of amplifying signals

Multiple steps allow for signal amplification: Calcium is a simple method of amplifying signals

Calcium is a common effector. Cytoplasmic calcium levels are normally low.

Calcium is a common effector. Cytoplasmic calcium levels are normally low.

During signal transduction, calcium can be released into the cytoplasm: Perception

During signal transduction, calcium can be released into the cytoplasm: Perception

During signal transduction, calcium can be released into the cytoplasm: Transduction

During signal transduction, calcium can be released into the cytoplasm: Transduction

During signal transduction, calcium can be released into the cytoplasm: Response

During signal transduction, calcium can be released into the cytoplasm: Response

During signal transduction, calcium can be released into the cytoplasm

During signal transduction, calcium can be released into the cytoplasm

General model of Ca++ signaling

General model of Ca++ signaling

General model of Ca++ signaling

General model of Ca++ signaling

Multiple steps allow for signal amplification: Calcium is a simple method of amplifying signals

Multiple steps allow for signal amplification: Calcium is a simple method of amplifying signals

Ca++ is involved in many responses

Ca++ is involved in many responses

Ca++ is involved in signal transduction for responses of: • • • in Plants

Ca++ is involved in signal transduction for responses of: • • • in Plants in Animals Development • Neurons Cold • Muscle movement Guard cell closing • Wounding Osmotic shock • Development Light • Fertilization Fungal infection • Hormones Touch • … Pollen tube growth Wounding… How can there be specificity?

Everything has its place…

Everything has its place…

Some Ca++ channels have specific effectors associated with them: Micro-domains Ikeda, Science 12 Oct

Some Ca++ channels have specific effectors associated with them: Micro-domains Ikeda, Science 12 Oct 2001 Vol 294: 318 -319

Root nodules: Nitrogen fixation

Root nodules: Nitrogen fixation

Bacteria and Plants Symbiosis

Bacteria and Plants Symbiosis

Signaling between bacteria and plants

Signaling between bacteria and plants

1 n. M Nod Fig 3. Shaw and Long, Plant Physiology, March 2003, Vol.

1 n. M Nod Fig 3. Shaw and Long, Plant Physiology, March 2003, Vol. 131, pp. 976– 984 10 n. M Nod A biphasic Ca++ response to Nod factor: 1 n. M Nod - toward nucleus 10 nm Nod - away from nucleus

1 n. M Nod 10 n. M Nod A biphasic Ca++ response to Nod

1 n. M Nod 10 n. M Nod A biphasic Ca++ response to Nod factor: 1 n. M Nod - toward nucleus 10 nm Nod - away from nucleus Fig 3. Shaw and Long, Plant Physiology, March 2003, Vol. 131, pp. 976– 984

Everything has its place…

Everything has its place…

2 hypotheses about how Ca++ signals are transduced: Signatures vs. Switches Fig 1. Scrase-Field

2 hypotheses about how Ca++ signals are transduced: Signatures vs. Switches Fig 1. Scrase-Field and Knight, Current Opinion in Plant Biology 2003, 6: 500– 506

Photosynthesis: Plants can make sugar using energy from the sun, water from the ground,

Photosynthesis: Plants can make sugar using energy from the sun, water from the ground, and CO 2 from the air.

Stomata regulate gas exchange: CO 2 in, O 2 and water out H 2

Stomata regulate gas exchange: CO 2 in, O 2 and water out H 2 O

Stomata open closed

Stomata open closed

Opening and closing of stomata

Opening and closing of stomata

Ca++ fluxes in guard cells in response to hormone or stress that cause stomatal

Ca++ fluxes in guard cells in response to hormone or stress that cause stomatal closing. Wildtype vs. det 3 and gca 2: mutants that fail to close stomata following treatment Fig 5. Sanders et al. , The Plant Cell, S 401–S 417, Supplement 2002

2 hypotheses about how calcium signals are transduced: Signatures vs. Switches Fig 1. Scrase-Field

2 hypotheses about how calcium signals are transduced: Signatures vs. Switches Fig 1. Scrase-Field and Knight, Current Opinion in Plant Biology 2003, 6: 500– 506

Signal Transduction External Stimulus Internal Effector… Effector Response Perception (by receptor) Stimulus

Signal Transduction External Stimulus Internal Effector… Effector Response Perception (by receptor) Stimulus

Homework #1 is posted and due 9/17 Bonus #1 is posted and due 10/24

Homework #1 is posted and due 9/17 Bonus #1 is posted and due 10/24 Discussions started this week