Electron Transfer Involving the Phylloquinone (A1) Cofactor of Photosystem I Examined with Time Resolved Absorbance and Electron Paramagnetic Resonance Spectroscopy

The dependence of the electron transfer (ET) rate on the Photosystem I (PSI) cofactor phylloquinone (A1) is studied by time-resolved absorbance and electron paramagnetic resonance (EPR) spectroscopy. Two active branches (A and B) of electron transfer converge to the FX cofactor from the A1A and A1B quinone. The work described in Chapter 5 investigates the single hydrogen bond from the amino acid residue PsaA-L722 backbone nitrogen to A1A for its effect on the electron transfer rate to FX. Room temperature transient EPR measurements show an increase in the rate for the A1A- to FX for the PsaA-L722T mutant and an increased hyperfine coupling to the 2-methyl group of A1A when compared to wild type. The Arrhenius plot of the A1A- to FX ET in the PsaA-L722T mutant suggests that the increased rate is probably the result of a slight change in the electronic coupling between A1A- and FX. The reasons for the non-Arrhenius behavior are discussed. The work discussed in Chapter 6 investigates the directionality of ET at low temperature by blocking ET to the iron-sulfur clusters FX, FA and FB in the menB deletion mutant strain of Synechocyctis sp. PCC 6803, which is unable to synthesize phylloquinone, by incorporating the high midpoint potential (49 mV vs SHE) 2,3-dichloro-1,4-naphthoquinone (Cl2NQ) into the A1A and A1B binding sites. Various EPR spectroscopic techniques were implemented to differentiate between the spectral features created from A and B- branch electron transfer. The implications of this result for the directionality of electron transfer in PS I are discussed. The work discussed in Chapter 7 was done to study the dependence of the heterogeneous ET at low temperature on A1 midpoint potential. The menB PSI mutant contains plastiquinone-9 in the A1 binding site. The solution midpoint potential of the quinone measures 100 mV more positive then wild-type phylloquinone. The irreversible ET to the terminal acceptors FA and FB at low temperature is not controlled by the forward step from A1 to FX as expected due to the thermodynamic differences of the A1 cofactor in the two active branches A and B. Alternatives for the ET heterogeneity are discussed.

The electromyographic threshold in boys and men

Abstract Background Children have been shown to have higher lactate (LaTh) and ventilatory (VeTh) thresholds than adults, which might be explained by lower levels of type-II motor-unit (MU) recruitment. However, the electromyographic threshold (EMGTh), regarded as indicating the onset of accelerated type-II MU recruitment, has been investigated only in adults. Purpose To compare the relative exercise intensity at which the EMGTh occurs in boys versus men. Methods Participants were 21 men (23.4 ± 4.1 years) and 23 boys (11.1 ± 1.1 years), with similar habitual physical activity and peak oxygen consumption (VO2pk) (49.7 ± 5.5 vs. 50.1 ± 7.4 ml kg−1 min−1, respectively). Ramped cycle ergometry was conducted to volitional exhaustion with surface EMG recorded from the right and left vastus lateralis muscles throughout the test (~10 min). The composite right–left EMG root mean square (EMGRMS) was then calculated per pedal revolution. The EMGTh was then determined as the exercise intensity at the point of least residual sum of squares for any two regression line divisions of the EMGRMS plot. Results EMGTh was detected in 20/21 of the men (95.2 %) and only in 18/23 of the boys (78.3 %). The boys’ EMGTh was significantly higher than the men’s (86.4 ± 9.6 vs. 79.7 ± 10.0 % of peak power output at exhaustion; p < 0.05). The pattern was similar when EMGTh was expressed as percentage of VO2pk. Conclusions The boys’ higher EMGTh suggests delayed and hence lesser utilization of type-II MUs in progressive exercise, compared with men. The boys–men EMGTh differences were of similar magnitude as those shown for LaTh and VeTh, further suggesting a common underlying factor.

Indenture between Captain Thomas Bushby and Sarah Bushby and Edward Clarke Campbell

Indenture of bargain and sale between Captain Thomas Bushby of the Island of Jersey and his wife Sarah Bushby to Edward Clarke Campbell of the town of Niagara regarding 100 acres in Sherbrooke Forest in the District of Niagara, also Lots 6 and 7 in the town plot of Sherbrooke. This document was registered in the Township of Sherbrooke on December 28, 1849 - instrument no. 503, March 17, 1849.

Indenture between Thomas Murtagh and Samuel Zimmerman

Indenture of mortgage in fee between Thomas Murtagh of the Town of Elgin and Samuel Zimmerman of NIagara Falls regarding Lot no. 15 in Block N in the Town Plot of Elgin - instrument no. 3164[9?], September 24, 1855.

Indenture between St. Catharines Victoria Lawn Cemetery and Mrs. H.K. Woodruff

Indenture between St. Catharines Victoria Lawn Cemetery and Mrs. H.K. Woodruff for a perpetual care fund and $67.20 into a general care and improvement fund in respect to the southerly portion of Lot no.9 in section P of the St. Catharines Victoria Lawn Cemetery. The deed no. is 859. This is the S.D. Woodruff plot, Nov. 4, 1932.

Indenture (vellum) between the Honourable William Dickson of Niagara and Robert Dickson of Niagara

Indenture (vellum) between the Honourable William Dickson of Niagara and Robert Dickson of Niagara for the mill tract and town plot in Dumfries, Ontario, Jan. 16, 1841.

Indenture between the Honourable William Dickson and of Niagara and Commander Thomas Bushby, then Lieutenant in the Royal Navy

Indenture between the Honourable William Dickson and of Niagara and Commander Thomas Bushby, then Lieutenant in the Royal Navy for land in the village plot of Sherbrooke – instrument no. 230. This was recorded on Sept. 15, 1843 in Book A, folio 281-282. April 15, 1843.