Biomedical subjects

Kerry G Bemis

Publications and source records attributed to Kerry G Bemis.

3 recordsLinked to original sources

PubMed2006

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 NH(2)-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 NH(2)-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.

Amino Acid Sequence↗

PubMed2004

Phencyclidine-induced changes in rat cortical gene expression identified by microarray analysis: implications for schizophrenia.

Acute phencyclidine induces schizophrenia-like symptoms in healthy humans and psychotic episodes in schizophrenics. Although phencyclidine is known as a N-methyl d-aspartate receptor antagonist (NMDA-R), the molecular events underlying the behavioral symptoms remain largely unknown. Statistical analysis of oligonucleotide microarray data was used to identify phencyclidine-induced alterations in rat cortical gene expression. Acute phencyclidine produced a statistically significant change in 477 genes in rat prefrontal cortex (PFC), a brain area associated with cognitive dysfunction in schizophrenics. Real-time quantitative PCR (RTQ-PCR) confirmed a subset of these changes ranging from -59% to 255% (smallest confirmation: -19%). Subsequent time-course and dose-response studies using RTQ-PCR confirmed and extended the original microarray results. At the molecular level, genes altered by phencyclidine are related to diverse biological processes including stress, inflammatory response, growth and development, neural plasticity and signal transduction. Further analysis, aimed at assessing the relevance of our results to schizophrenia, revealed dysregulation of genes related to: (i) thalamocortical projections, (ii) neurotransmission and neuromodulation, (iii) thyroid hormone activity, (iv) oligodendrocyte linage, (v) brain lipid metabolism, (vi) sleep architecture and (viii) the velocardiofacial syndrome.

Animals↗

PubMed2004

At what scale should microarray data be analyzed?

INTRODUCTION: The hybridization intensities derived from microarray experiments, for example Affymetrix's MAS5 signals, are very often transformed in one way or another before statistical models are fitted. The motivation for performing transformation is usually to satisfy the model assumptions such as normality and homogeneity in variance. Generally speaking, two types of strategies are often applied to microarray data depending on the analysis need: correlation analysis where all the gene intensities on the array are considered simultaneously, and gene-by-gene ANOVA where each gene is analyzed individually. AIM: We investigate the distributional properties of the Affymetrix GeneChip signal data under the two scenarios, focusing on the impact of analyzing the data at an inappropriate scale. METHODS: The Box-Cox type of transformation is first investigated for the strategy of pooling genes. The commonly used log-transformation is particularly applied for comparison purposes. For the scenario where analysis is on a gene-by-gene basis, the model assumptions such as normality are explored. The impact of using a wrong scale is illustrated by log-transformation and quartic-root transformation. RESULTS: When all the genes on the array are considered together, the dependent relationship between the expression and its variation level can be satisfactorily removed by Box-Cox transformation. When genes are analyzed individually, the distributional properties of the intensities are shown to be gene dependent. Derivation and simulation show that some loss of power is incurred when a wrong scale is used, but due to the robustness of the t-test, the loss is acceptable when the fold-change is not very large.

Algorithms↗