Tissue heterogeneity of the mammalian mitochondrial proteome

The functionality of the mitochondrion is primarily determined by nuclear encoded proteins. The mitochondrial functional requirements of different tissues vary from a significant biosynthetic role (liver) to a primarily energy metabolism-oriented organelle (heart). The purpose of this study was to compare the mitochondrial proteome from four different tissues of the rat, brain, liver, heart, and kidney, to provide insight into the extent of mitochondrial heterogeneity and to further characterize the overall mitochondrial proteome. Mitochondria were isolated, solubilized, digested, and subjected to quantitative liquid chromatography-mass spectroscopy. Of the 16,950 distinct peptides detected, 8,045 proteins were identified. High-confidence identification threshold was reached by 1,162 peptides, which were further analyzed. Of these 1,162 proteins, 1,149 were significantly different in content ( P and q values < 0.05) between at least 2 tissues, whereas 13 were not significantly different between any tissues. Confirmation of the mitochondrial origin of proteins was determined from the literature or via NH2-terminal mitochondrial localization signals. With these criteria, 382 proteins in the significantly different groups were confirmed to be mitochondrial, and 493 could not be confirmed to be mitochondrial but were not definitively localized elsewhere in the cell. A total of 145 proteins were assigned to the rat mitochondrial proteome for the first time via their NH2-terminal mitochondrial localization signals. Among the proteins that were not significantly different between tissues, three were confirmed to be mitochondrial. Most notable of the significantly different proteins were histone family proteins and several structural proteins, including tubulin and intermediate filaments. The mitochondrial proteome from each tissue had very specific characteristics indicative of different functional emphasis. These data confirm the notion that mitochondria are tuned by the nucleus for specific functions in different tissues.

Functional consequences of mitochondrial proteome heterogeneity

Potential functional consequences of the differences in protein distribution between the mitochondria of the rat liver, heart, brain, and kidney, as determined in the companion paper in this issue (Johnson DT, French S, Blair PV, You JS, Bemis KG, Wang M, Harris RA, and Balaban RS. The tissue heterogeneity of the mammalian mitochondrial proteome. Am J Physiol Cell Physiol292: C689-C697, 2006), were analyzed using a canonical metabolic pathway approach as well as a functional domain homology analysis. These data were inserted into the Kyoto Encyclopedia of Genes and Genomes pathway framework to give global and metabolic pathway-specific information on the impact of the differential protein distribution on mitochondrial function. Custom pathway analysis was also performed using pathways limited to the mitochondrion. With the use of this approach, several well-known functional differences between these mitochondrial populations were confirmed. These included GABA metabolism in the brain, urea synthesis in the liver, and the domination of oxidative phosphorylation in the heart. By comparing relative protein amounts of mitochondria across tissues, a greater understanding of functional emphasis is possible as well as the nuclear "programming" required to enhance a given function within the mitochondria. For proteins determined to be mitochondrial and lacking a defined role functional domain BLAST analyses were performed. Several proteins associated with DNA structural modification and a novel CoA transferase were identified. A protein was also identified capable of catalyzing the first three steps of de novo pyrimidine synthesis. This analysis demonstrates that the distribution of nuclear encoded proteins significantly modifies the overall functional emphasis of the mitochondria to meet tissue-specific needs. These studies demonstrate the existence of mitochondrial biochemical functions that at present are poorly defined.

Functional consequences of mitochondrial proteome heterogeneity

Potential functional consequences of the differences in protein distribution between the mitochondria of the rat liver, heart, brain, and kidney, as determined in the companion paper in this issue (Johnson DT, French S, Blair PV, You JS, Bemis KG, Wang M, Harris RA, and Balaban RS. The tissue heterogeneity of the mammalian mitochondrial proteome. Am J Physiol Cell Physiol292: C689-C697, 2006), were analyzed using a canonical metabolic pathway approach as well as a functional domain homology analysis. These data were inserted into the Kyoto Encyclopedia of Genes and Genomes pathway framework to give global and metabolic pathway-specific information on the impact of the differential protein distribution on mitochondrial function. Custom pathway analysis was also performed using pathways limited to the mitochondrion. With the use of this approach, several well-known functional differences between these mitochondrial populations were confirmed. These included GABA metabolism in the brain, urea synthesis in the liver, and the domination of oxidative phosphorylation in the heart. By comparing relative protein amounts of mitochondria across tissues, a greater understanding of functional emphasis is possible as well as the nuclear "programming" required to enhance a given function within the mitochondria. For proteins determined to be mitochondrial and lacking a defined role functional domain BLAST analyses were performed. Several proteins associated with DNA structural modification and a novel CoA transferase were identified. A protein was also identified capable of catalyzing the first three steps of de novo pyrimidine synthesis. This analysis demonstrates that the distribution of nuclear encoded proteins significantly modifies the overall functional emphasis of the mitochondria to meet tissue-specific needs. These studies demonstrate the existence of mitochondrial biochemical functions that at present are poorly defined.

Mitochondrial matrix phosphoproteome: effect of extra mitochondrial calcium

Post-translational modification of mitochondrial proteins by phosphorylation or dephosphorylation plays an essential role in numerous cell signaling pathways involved in regulating energy metabolism and in mitochondrion-induced apoptosis. Here we present a phosphoproteomic screen of the mitochondrial matrix proteins and begin to establish the protein phosphorylations acutely associated with calcium ions (Ca(2+)) signaling in porcine heart mitochondria. Forty-five phosphorylated proteins were detected by gel electrophoresis-mass spectrometry of Pro-Q Diamond staining, while many more Pro-Q Diamond-stained proteins evaded mass spectrometry detection. Time-dependent (32)P incorporation in intact mitochondria confirmed the extensive matrix protein phosphoryation and revealed the dynamic nature of this process. Classes of proteins that were detected included all of the mitochondrial respiratory chain complexes, as well as enzymes involved in intermediary metabolism, such as pyruvate dehydrogenase (PDH), citrate synthase, and acyl-CoA dehydrogenases. These data demonstrate that the phosphoproteome of the mitochondrial matrix is extensive and dynamic. Ca(2+) has previously been shown to activate various dehydrogenases, promote the generation of reactive oxygen species (ROS), and initiate apoptosis via cytochrome c release. To evaluate the Ca(2+) signaling network, the effects of a Ca(2+) challenge sufficient to release cytochrome c were evaluated on the mitochondrial phosphoproteome. Novel Ca(2+)-induced dephosphorylation was observed in manganese superoxide dismutase (MnSOD) as well as the previously characterized PDH. A Ca(2+) dose-dependent dephosphorylation of MnSOD was associated with an approximately 2-fold maximum increase in activity; neither the dephosphorylation nor activity changes were induced by ROS production in the absence of Ca(2+). These data demonstrate the use of a phosphoproteome screen in determining mitochondrial signaling pathways and reveal new pathways for Ca(2+) modification of mitochondrial function at the level of MnSOD.

Experiments on the role of gas height in the Rayleigh–Marangoni instability problem

Experimental evidence is provided to show the effect of gas phase dynamics on the onset of thermal convection and on the accompanying patterns in a silicone oil-air convecting bilayer. Very good agreement with three-dimensional calculations for linearized stability is obtained mostly for small and large gas heights. Reasons for this agreement as well as the results at intermediate gas heights are qualitatively explained from the perspective of well-established nonlinear analysis.

The Missouri planning grant for the education and training of health sciences librarians

The planning grant at the School of Library and Informational Science (SLIS) at the University of Missouri has two aims: (a) developing a model curriculum for health sciences librarianship at the master's level and (b) developing materials that can be delivered by alternative instructional methods. To accomplish the first aim, the faculty will investigate the possibility of offering courses in other disciplines, such as health care administration, educational technology, adult education, and medical sociology. In addition, the SLIS faculty will investigate the development of new kinds of placement for the students' practicum experience. To reach the second aim, the SLIS faculty will investigate alternative means of delivering both graduate and continuing education. Three instructional modalities will be evaluated. Some material will be delivered via satellite broadcast, some material will be made available via the World Wide Web and some will be presented in an intensive seminar. The outcome of the planning grant will be two distinct plans. The first will be a plan for the curriculum in health sciences librarianship at the master's level. The second will be a plan for offering instruction through alternative methods, both for graduate education and for continuing education.

Environmental risk factors for Lyme disease identified with geographic information systems

OBJECTIVES

A geographic information system was used to identify and locate residential environmental risk factors for Lyme disease.

METHODS

Data were obtained for 53 environmental variables at the residences of Lyme disease case patients in Baltimore County from 1989 through 1990 and compared with data for randomly selected addresses. A risk model was generated combining the geographic information system with logistic regression analysis. The model was validated by comparing the distribution of cases in 1991 with another group of randomly selected addresses.

RESULTS

In crude analyses, 11 environmental variables were associated with Lyme disease. In adjusted analyses, residence in forested areas (odds ratio [OR] = 3.7, 95% confidence interval [CI] = 1.2, 11.8), on specific soils (OR = 2.1, 95% CI = 1.0, 4.4), and in two regions of the county (OR = 3.5, 95% CI = 1.6, 7.4) (OR = 2.8, 95% CI = 1.0, 7.7) was associated with elevated risk of getting Lyme disease. Residence in highly developed regions was protective (OR = 0.3, 95% CI = 0.1, 1.0). The risk of Lyme disease in 1991 increased with risk categories defined from the 1989 through 1990 data.

CONCLUSIONS

Combining a geographic information system with epidemiologic methods can be used to rapidly identify risk factors of zoonotic disease over large areas.

Microcirculatory dynamics in experimental human gingivitis

The purpose of this study was to determine the changes that occur in the gingival microcirculation during the development of experimental gingivitis in humans. There have been no studies published to date combining videomicroscopy and laser Doppler flowmetry to study vascular dynamics in experimental gingivitis. Alterations occurring in the microcirculation of the marginal gingiva in 10 (18-30-year-old), healthy male humans when they suspended oral hygiene procedures in a proscribed area for 12-16 days were monitored. A partial mouth, experimental gingivitis model was employed. Gingival health was evaluated before and after the experimental period by assessing gingival and plaque indices and gingival crevicular fluid volume. Gingival vascular monitoring included measurement of red blood cell velocity in individual gingival microvessels via videomicroscopy and measurement of regional gingival blood flow using laser doppler flowmetry. The number of vessels visible in a given microscopic field in a given subject and the number of vessels exhibiting flow were also determined from the videotapes. Systemic cardiovascular and respiratory parameters were monitored to ensure that gingival vascular changes were not secondary to systemic changes. Gingivitis developed in all subjects; significant increases (Student t-test, p < 0.05) were seen in plaque index, gingival index, bleeding on probing and crevicular fluid volume. No change in superficial capillary blood velocity and a significant decrease in gingival regional blood flow were seen with gingivitis. A significant increase in the number of vessels visible in microscopic fields and a decrease in the % of vessels exhibiting flow were observed. Gingival microcirculation exhibited a dramatic, dynamic change in response to the development and progression of gingivitis.

Aging and microcirculatory dynamics in human gingiva

There have been no published reports characterizing gingival vascular function in humans of different ages. In this study, we compared gingival vascular dynamics in 60 healthy male humans ranging in age from 18-75 years (young, 18-25 years (Y); middle, 35-45 years (M); old, 65-75 years (O), 20 subjects/group). Both videomicroscopy of individual microvessels and laser doppler flowmetry were employed to assess marginal gingival circulation. Systemic cardiopulmonary parameters were monitored as controls. The number of gingival vessels visible in a microscopic field was higher and the number of microvessels exhibiting active flow was lower in M and O compared to Y. There were no differences among age groups in laser doppler flow values (tissue blood flow) or in red blood cell velocity in individual vessels. Although not statistically significant with age there was a trend towards decreasing blood flow velocity in both the laser doppler and videomicroscopic measurements. Blood pressure increased slightly with age. Peripheral oxygen saturation was lower in O compared to Y and M. No differences were seen in heart rate, respiratory rate or end-tidal carbon dioxide concentration. The changes in blood pressure and oxygen saturation were expected. The differences in numbers of visible vessels and the number of vessels with active blood flow may reflect the way the gingival microcirculation adapts with age to changing nutritional needs or to microbial and/or mechanical challenge.

Diagnosis of a mass in the neck

A mass in the neck can occur because of developmental factors, lymphadenopathy, salivary gland disease, or neuromas. It is important to examine areas other than the neck in assessing these masses, most of which can be diagnosed by a good history/physical examination and simple laboratory tests, described here.

The interpretative validity of the FAM: long-term psychotherapists' ratings of psychiatric inpatients

Newmark, Conger, and Faschingbauer (1976) found a significant difference between mean ratings of MMPI and FAM (Faschingbauer's Abbreviated MMPI) based interpretations. Since this may have been specific to lack of rater experience, the present study attempted a replication using long-term psychotherapists as raters. The only significant difference was for 20 male psychiatric inpatients. Females (n = 16) and the pooled sample showed no significant differences between ratings regardless of the source test. When the present results are compared to those of Newmark, Conger and Faschinbauer (1976) and earlier work by Fashcinbauer (1973), it appears that the FAM yields interpretation as accurate as one would expect given its psychometric dissimilarity from the MMPI.

Effect of time-specific sets and patients' personality style on state and trait anxiety

60 subjects representing equal numbers of repressors arid sensitizers were matched for age and sex and evaluated on three measures of anxiety which differed in time span in which anxiety was estimated. As expected, sensitizers reported significantly greater anxiety than repressors regardless of the proximity of the time on which they based their estimates. A significant interaction between reports of anxiety and repression-sensitization demonstrated that sensitizers report less anxiety when recording their current condition than remote remembrances, whereas repressors tend to report essentially the same level of anxiety regardless of whether they are estimating their anxiety over “a year or two,” “a month or two,” or “now.”

MMPI correlates of extreme field independence and field dependence in a psychiatric population

34 male and 34 female hospitalized psychiatric patients were divided into field-independent and field-dependent groups on the basis of rod-and-frame test performance and their MMPI scores were compared. A multiple discriminant analysis followed by a series of 2 X 2 factorial analyses of variance was used to assess the results. As in previous studies, more similarities than differences were found between the two cognitive styles. However, field-independent subjects tended to be more unconventional, aggressive, antisocial, and perhaps defensive than field-dependent subjects. Explanations of results were explored in reference to previous findings.

Effects of birth order and sex on field independence-dependence

Birth order and field-independence research has produced seemingly similar findings concerning social dependence. However, of the few empirical efforts examining such similarities, methodological differences have produced ambiguous findings. The effects of sex and three birth-order categories on Rod-and-frame scores were evaluated for 248 male and 389 female psychiatric inpatients. A 2 × 3 analysis of variance showed significant sex and birth-order effects, with males and firstborns less field-dependent than females and both later-borns and only children, respectively. The unpredicted birth-order results essentially contradicted previous findings and were discussed in terms of sample differences and the apparent need for improved social-dependency measures.