Event Title

Investigating pH Banding Kinetics of Chara corallina in Alternating Light Conditions with Rectangular Pulse Voltammetry

Location

Hager-Lubbers Exhibition Hall

Start Date

19-4-2016 3:30 PM

Description

PURPOSE: Chara corallina exhibits unique biochemistry under lighted conditions; it produces alternating acidic and basic bands due to regions that either pump out or allow in protons. This study focuses on the banding kinetics of these regions by measuring the pH profile in real-time to better understand the light-induced banding mechanism. SUBJECTS: Chara corallina internodal cells were cut from parent plants, trimmed, and kept in artificial pond water (APW) in light cycling on every 12 hours. METHODS AND MATERIALS: Glass-sealed carbon microelectrodes were prepared and a rectangular pulse voltammetry waveform was used to visualize minute changes in pH along the cell. Banding was visualized with phenyl red indicator dye in APW solution. The electrode was scanned along the cell using a small animal stereotaxic and lighted conditions were simulated with an LED light source. ANALYSES: A Wilcox Rank-sum analysis was used to compare the acidic/basic banding regions as well as the banding rates in the basic region. RESULTS: We found that the basic region is primarily responsible for the bulk of the pH banding phenomenon, while the acidic region remains relatively constant in both light and dark conditions. Focusing on the alkaline region, we found that the time for banding to stop when the light is removed is significantly faster than the time to restart when light is reintroduced. CONCLUSIONS: This offers insight unto the mechanism of light-induced banding in Chara corallina and it helps to confirm much of the current model proposed in the literature. The acidic regions are due to the action of a proton-pump. However, the basic regions seem to be strongly controlled by a photosynthetic bi-product that travels to these regions in a time-dependent manner to interact with and open the alkaline channels.

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Apr 19th, 3:30 PM

Investigating pH Banding Kinetics of Chara corallina in Alternating Light Conditions with Rectangular Pulse Voltammetry

Hager-Lubbers Exhibition Hall

PURPOSE: Chara corallina exhibits unique biochemistry under lighted conditions; it produces alternating acidic and basic bands due to regions that either pump out or allow in protons. This study focuses on the banding kinetics of these regions by measuring the pH profile in real-time to better understand the light-induced banding mechanism. SUBJECTS: Chara corallina internodal cells were cut from parent plants, trimmed, and kept in artificial pond water (APW) in light cycling on every 12 hours. METHODS AND MATERIALS: Glass-sealed carbon microelectrodes were prepared and a rectangular pulse voltammetry waveform was used to visualize minute changes in pH along the cell. Banding was visualized with phenyl red indicator dye in APW solution. The electrode was scanned along the cell using a small animal stereotaxic and lighted conditions were simulated with an LED light source. ANALYSES: A Wilcox Rank-sum analysis was used to compare the acidic/basic banding regions as well as the banding rates in the basic region. RESULTS: We found that the basic region is primarily responsible for the bulk of the pH banding phenomenon, while the acidic region remains relatively constant in both light and dark conditions. Focusing on the alkaline region, we found that the time for banding to stop when the light is removed is significantly faster than the time to restart when light is reintroduced. CONCLUSIONS: This offers insight unto the mechanism of light-induced banding in Chara corallina and it helps to confirm much of the current model proposed in the literature. The acidic regions are due to the action of a proton-pump. However, the basic regions seem to be strongly controlled by a photosynthetic bi-product that travels to these regions in a time-dependent manner to interact with and open the alkaline channels.