Reconstitution of oxidative phosphorylation in submitochondrial particles by a soluble protein phosphoryl transferase

A protein designated phosphoryl transferase has been isolated from beef heart mitochondria and has been found to increase the ability of Submitochondrial particles, oxidizing either NADH or succinate, to synthesize ATP from ADP and inorganic orthophosphate. Increases in the value of P:O ratios between 0.45 and 1 have been observed with succinate as substrate. Phosphoryl transferase was released from beef heart mitochondria by sonic disruption in the presence of EDTA and was then purified by fractionation with ammonium sulfate, chromatography on DEAE-cellulose, and recycling molecular sieve chromatography on polyacrylamide gel (BioGel P-200). The isolated phosphoryl transferase displayed a single peak in the analytical ultra-centrifuge and a single band in strip electrophoresis. Its molecular weight was estimated to be 124,000; its isoelectric point, pH 5.7. The absorption spectrum of the protein showed a maximum at 278-280 m[mu], a minimum at 250 m[mu], and a shoulder at 290 m[mu]. At pH 13 two distinct maxima appeared at 282 m[mu] and 288.5 m[mu]. Increases in the P:O ratios of Submitochondrial particles, induced by purified phosphoryl transferase, were observed only at the site of energy conservation between reduced coenzyme Q and cytochrome c. The protein has also been isolated from phosphorylating Submitochondrial particles. During recycling gel filtration, a protein was separated from the phosphoryl transferase which inhibited the ATPase activity of Submitochondrial particles and counteracted the effect of the phosphoryl transferase in increasing the P:O ratio.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/33229/1/0000619.pd

Learning biochemistry at the mastery level -- introductory biochemistry at the University of Michigan

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28633/1/0000447.pd

The relative essentiality of the antioxidative function of Coenzyme Q--the interactive role of DT-diaphorase

This paper will address two aspects regarding the antioxidative role of coenzyme Q (CoQ): (1) Is the antioxidant function of CoQ primary or secondary (coincidental), i.e. was this molecule selected during evolution to function primarily as an essential functional component of the mitochondrial electron transfer chain and oxidative phosphorylation processes, is its antioxidative capability merely a coincidence of its hydroquinone structure, or was its synthetic enzyme sequence selected on the basis of the advantage to the evolving organism of both functions of CoQ? (2) What is the mechanism whereby the hydroquinone (antioxidant) form of CoQ (CoQH2) is maintained in high proportion in the various and many membranes in which it resides, and in which an obvious electron transfer mechanism to reduce it is not present? The essentiality of the antioxidative role of CoQH2 will be explored and compared to other primary and secondary antioxidants. Recent evidence implicating the two-electron quinone reductase, DT-diaphorase, in the maintenance of the reduced, antioxidant state of CoQ during the oxidative stress of exhaustive exercise will be presented, and a hypothesis concerning the evolutionary significance of DT-diaphorase will be offered.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31956/1/0000909.pd

Inhibition by coenzyme Q of ethanol- and carbon tetrachloride-stimulated lipid peroxidation in vivo and catalyzed by microsomal and mitochondrial systems

The ability of coenzyme Q to inhibit lipid peroxidation in intact animals as well as in mitochondrial, submitochondrial, and microsomal systems has been tested. Rats fed coenzyme Q prior to being treated with carbon tetrachloride or while being treated with ethanol excrete less thiobarbituric acid-reacting material in the urine than such rats not fed coenzyme Q. Liver homogenates, mitochondria, and microsomes isolated from rats treated with carbon tetrachloride and ethanol catalyze lipid peroxidation at rates which exceed those from animals also fed coenzyme Q. The rate of lipid peroxidation catalyzed by submitochondrial particles isolated from hearts of young, old, and endurance trained elderly rats was inversely proportional to the coenzyme Q content of the submitochondrial preparation in assays in which succinate was employed to reduce the endogenous coenzyme Q. Reduced, but not oxidized, coenzyme Q inhibited lipid peroxidation catalyzed by rat liver microsomal preparations. These results provide additional evidence in support of an antioxidant role for coenzyme Q.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27527/1/0000571.pd

Induction of respiratory control in submitochondrial particles by dicyclohexylcarbodiimide

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/33289/1/0000681.pd

The effect of endurance exercise on bone dimensions, collagen, and calcium in the aged male rat

Sixteen weeks of a relatively mild running program, started at 22 months of age, lowered the body weights of 26-month-old male rats to the level of 9-month-old rats and increased the weights and the collagen densities of hind limb bones to levels greater than those of 9-, 22-, and 26-month-old sedentary rats. The densities (g/cm3) and the calcium densities (mg/cm3) of the hind limb bones decreased with age and were restored to the 9-month level by training the elderly rats to run. These data suggest that exercise is capable of inducing a compensation for, or a reversal of, age-associated bone loss (osteoporosis) and restoring the bone mineral content in aged rats to the level of those of mature young adult animals.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25887/1/0000450.pd

Quantifying imperfect detection in an invasive pest fish and the implications for conservation management

In managing non-native species, surveillance programmes aim to minimise the opportunity for invasions to develop from initial introductions through early detection. However, this is dependent on surveillance methods being able to detect species at low levels of abundance to avoid false-negative recordings through imperfect detection. We investigated through field experimentation the ability to detect Pseudorasbora parva, a highly invasive pest fish in Europe, in relation to their known density and sampling method. Secure pond mesocosms of area 100 m2 contained P. parva densities from 0.02 to 5.0 m"122; each density was in triplicate. These were searched using point sampling electric fishing and deployment of fish traps (non-baited and baited). No fish were captured at densities 0.5 m"122, whereas for electric fishing it only exceeded 0.95 at 5.0 m"122 using high searching effort. These data reveal that small pest fishes such as P. parva may be prone to imperfect detection when at low densities and this is consistent with a number of other invasive species. This indicates the importance of designing surveillance programmes using methods of known statistical power to optimise conservation resource expenditure and enhance management outcomes

Foot Injuries in Michigan, USA, Gray Wolves (\u3ci\u3eCanis lupus\u3c/i\u3e), 1992–2014

The range of gray wolves (Canis lupus) in the contiguous US is expanding. Research and monitoring to support population recovery and management often involves capture via foothold traps. A population-level epidemiologic assessment of the effect of trap injuries on wolf survival remains needed to inform management. We describe the baseline rate, type, and severity of foot injuries of wolves born 1992–2013 in Michigan’s Upper Peninsula, evaluate the reliability of field-scoring trap-related injuries, and the effect of injuries on wolf survival. We assessed foot injuries by physical and radiographic exam at postmortem and/or time of capture for 351 wolves using the International Organization for Standardization 10990-5 standard and the effects of injuries, sex, age, previous capture and body condition on survival using proportional hazards regression. We used ordinal regression to evaluate epidemiologic associations between sex, age, previous capture, body condition, cause of death and injury severity. Most wolves (53%) experienced no physically or radiographically discernable foot injuries over their lifetimes. Among those wolves that did experience injuries, 33% scored as mild. Foot injuries had little epidemiologically discernable effect on survival rates. Wolves with higher foot trauma scores did experience an increased risk of dying, but the magnitude of the increase was modest. Most limb injuries occurred below the carpus or tarsus, and scoring upper-limb injuries added little predictive information to population-level epidemiologic measures of survival and injury severity. There was little association between injury severity and cause of death. Based on necropsy exams, previous trap injuries likely contributed to death in only four wolves (1.1%). Our results suggest that injuries resulting from foothold traps are unlikely to be a limiting factor in recovery and ongoing survival of the Michigan gray wolf population

Exercise-induced reversal of age-related declines of oxidative reactions, mitochondrial yield, and flavins in skeletal muscle of the rat

The ability of gastrocnemius muscle homogenates to catalyze the oxidation of succinate, glutamate + malate, pyruvate + malate, palmitoyl-coenzyme A, decanoylcarnitine and palmitoylcarnitine in the presence of ADP decreased by approximately 32% in sedentary male Sprague-Dawley rats between the ages of 9 and 25 months. Following 21 weeks of treadmill training (running), such homogenates from 25-month-old animals catalyzed oxidations 55% more rapidly than those from 25-month-old sedentary rats, and 17% faster than those from 9-month-old sedentary rats. Total and peptide-bound flavin of gastrocnemius muscles also declined between 9 and 25 months of age and were elevated in the 25-month-old endurance trained rats to levels greater than both 9- and 25-month-old sedentary animals. The yield of protein in the mitochondrial fraction from the quadriceps femoris muscle decreased between 9 and 25 months and was restored to the 9-month level by endurance training. The kinetic characteristics of the isolated mitochondria were not influenced by age or exercise. These data indicate that 2-year-old rats retain the capacity to increase skeletal muscle oxidative capacity and mitochondrial population density in response to endurance training.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24891/1/0000318.pd