Spontaneous gallstone formation in deer mice: interaction of cholesterol,bile acids,and dietary fiber

A study of the physiologic and ecologic factors involved in a spontaneous seasonal gallstone cycle of deer mice (Peromyscus maniculatus gambelii) was conducted at the Tulelake National Wildlife Refuge (California, USA) from March 1991 to June 1992. The specific hypothesis examined was whether or not seasonal increases in dietary fiber intake provides the necessary conditions for a solubility defect, or supersaturation mechanism, resulting in precipitation of cholesterol gallstones. Results indicated that in addition to the seasonal gallstone prevalence cycle, these deer mice exhibit significant seasonal cycling in serum cholesterol, serum bile acids, fecal bile acids, and diet composition. These physiologic and dietary cycles were phase-advanced 3 mo over the gallstone prevalence cycle, indicating an approximate 3 mo time period for gallstone formation under field conditions. Further, seasonal dietary fiber (plant material and seeds) was positively correlated with both serum cholesterol and the fecal bile acids. This suggests that in wild deer mice, variations in dietary fiber may significantly affect the resorption of bile acids, thereby providing a potential physiologic and nutritional mechanism for spontaneous cholesterol gallstone formation.     

Role of mass spectrometry in the purification of peptides and proteins

Experiments were carried out to evaluate the fractionation of proteins and peptides according to mass. Model mixtures were separated by either reversed-phase or ion-exchange chromatography with mass spectrometry-compatible mobile phase additives. Fraction collection was triggered by the mass/charge ratio of each one of the components of the mixture. Chromatography was additionally monitored with a UV-Vis detector in order to compare the new technique with generally accepted in separations. The results indicated that adequate purification is achieved by this new technique. Fraction collection triggered by changes in the mass/charge ratio reduces sample handling and analysis time. This study demonstrates the utility of mass-directed fractionation of peptides and proteins when mass spectrometry-compatible mobile phase additives are used.     

Using matK sequence data to unravel the phylogeny of Casuarinaceae

Casuarinaceae are a Gondwanic family with a unique combination of morphological characters not comparable to any other family. Until recently, the 96 species in the family were classified in a single genus, Casuarina s.l. A recent morphological revision of the family resulted in the splitting of Casuarina s.l. into four genera-Allocasuarina, Casuarina s.s., Ceuthostoma, and Gymnostoma. This study uses matK sequence data from 76 species of Casuarinaceae and eight outgroup taxa to examine the phylogenetic structure within the Casuarinaceae. The study demonstrates the monophyly of the four genera and examines the relationships within the family; it tests the validity of the infra-generic subdivision of Allocasuarina; it discovers geography-based infra-generic subdivisions within Gymnostoma and Casuarina; and, finally, provides a molecular framework on which to trace the evolution of xeromorphy in the Casuarinaceae.     

Autoimmune islet destruction in spontaneous type 1 diabetes is not beta-cell exclusive

Pancreatic islets of Langerhans are enveloped by peri-islet Schwann cells (pSC), which express glial fibrillary acidic protein (GFAP) and S100beta. pSC-autoreactive T- and B-cell responses arise in 3- to 4-week-old diabetes-prone non-obese diabetic (NOD) mice, followed by progressive pSC destruction before detectable beta-cell death. Humans with probable prediabetes generate similar autoreactivities, and autoantibodies in islet-cell autoantibody (lCA) -positive sera co-localize to pSC. Moreover, GFAP-specific NOD T-cell lines transferred pathogenic peri-insulitis to NOD/severe combined immunodeficient (NOD/SCID) mice, and immunotherapy with GFAP or S100beta prevented diabetes. pSC survived in rat insulin promoter Iymphocytic choriomeningitis virus (rip-LCMV) glycoprotein/CD8+ T-cell receptor(gp) double-transgenic mice with virus-induced diabetes, suggesting that pSC death is not an obligate consequence of local inflammation and beta-cell destruction. However, pSC were deleted in spontaneously diabetic NOD mice carrying the CD8+/8.3 T-cell receptor transgene, a T cell receptor commonly expressed in earliest islet infiltrates. Autoimmune targeting of pancreatic nervous system tissue elements seems to be an integral, early part of natural type 1 diabetes.     

An aging-related cell surface NADH oxidase (arNOX) generates superoxide and is inhibited by coenzyme Q

This report describes a novel ECTO-NOX protein with an oscillating activity having a period length of ca. 26 min encountered with buffy coat fractions and sera of aged individuals (70–100 years) that generates superoxide as measured by the reduction of ferricytochrome c. The oscillating, age-related reduction of ferricytochrome c is sensitive to superoxide dismutase, is inhibited by coenzyme Q and is reduced or absent from sera of younger individuals (20–40 years). An oscillating activity with a regular period length is a defining characteristic of ECTO-NOX proteins (a group of cell surface oxidases with enzymatic activities that oscillate). The period length of ca. 26 min is longer than the period length of 24 min for the usual constitutive (CNOX) ECTO-NOX proteins of the cell surface and sera which neither generate superoxide nor reduce ferricytochrome c. The aging-related ECTO-NOX protein (arNOX) provides a mechanism to transmit cell surface oxidative changes to surrounding cells and circulating lipoproteins potentially important to atherogenesis. Additionally, the findings provide a rational basis for the use of dietary coenzyme Q to retard aging-related arterial lesions.     

The color loci of mice--a genetic century

Color loci in mammals are those genetic loci in which mutations can affect pigmentation of the hair, skin, and/or eyes. In the mouse, over 800 phenotypic alleles are now known, at 127 identified color loci. As the number of color loci passed 100 only recently, we celebrate this 'century' with an overview of these loci, especially the 59 that have been cloned and sequenced. These fall into a number of functional groups representing melanocyte development and differentiation, melanosomal components, organelle biogenesis, organelle transport, control of pigment-type switching, and some systemic effects. A human ortholog has been identified in all cases, and the majority of these human genes are found to be loci for human disorders, often affecting other body systems as well as pigmentation. We expect that a significant number of color loci remain to be identified. Nonetheless, the large number known already provide a treasury of resources for reconstruction of the mechanisms, at the subcellular, cellular and tissue levels, that produce a functional pigmentary system and contribute to the normal development and functioning of many other organ systems. The mutant mice also provide valuable models for the study of human disease.     

Aqueous two-phase partition and detergent precipitation of a drug-responsive NADH oxidase from the HeLa cell surface

The partitioning behaviour of a drug (capsaicin)-responsive NADH oxidase (tNOX) activity released from HeLa ceIls by low pH treatment followed by heat and proteinase K was determined. When partitioned in a standard 6.4% PEG 3350/6.4% dextran T-500 two-phase system, the bulk of the tNOX activity was in the dextran-rich lower phase. The activity was inhibited by and bound to the triazine dye, Cibacron blue. Affinity partition, where the Cibacron blue was coupled to amino PEG 5000 and added to the first two-phase separation step, resulted in the partitioning of activity to the upper PEG phase. A second partition with PEG-salts resulted in the release of the tNOX from the Cibacron blue–amino PEG enriched phase into the salt-enriched lower phase. The phase-purified protein exhibited anomalous behavior and tended to multimerize in sodium dodecyl sulphate (SDS) prior to SDS-polyacrylamide gel electrophoresis (PAGE). Multimerization appeared to be enhanced by PEG. The multimerization was enhanced with the reduced protein in the presence of detergent prior to SDS–PAGE. In addition, the activity was precipitated by PEG 8000 at concentrations between 6 and 30% by weight. In the presence of or after exposure to PEG 3350 or PEG 8000, the protein could not be detected by Western blot analysis after SDS–PAGE suggesting that the protein failed to enter the gel even though other HeLa cell surface proteins were unaffected. The anomalous multimerization behavior has thus far precluded the use of phase partition as a practical purification step for the oxidase.