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.     

Backbone and side chain 1H, 15N and 13C assignments of the KSR1 CA1 domain

The backbone and side chain resonance assignments of the murine KSR1 CA1 domain have been determined based on triple-resonance experiments using uniformly [¹³C, ¹⁵N]-labeled protein. This assignment is the first step towards the determination of the three-dimensional structure of the unique KSR1 CA1 domain.     

Enalapril and losartan restored blood pressure and vascular reactivity in intrauterine undernourished rats

Epidemiological studies suggest that intrauterine undernutrition plays an important role in the development of arterial hypertension and endothelial dysfunction in adulthood. We have evaluated the effect of the Renin Angiotensin System inhibition on the blood pressure and the mesenteric arteriolar reactivity of the intrauterine undernourished rats. Wistar rats were fed either normal or 50% of the normal intake diets, during the whole gestational period. In this study only the male offspring was used. At 16 weeks of age, the rats were used for the study of blood pressure, microvascular reactivity studied in vivo-in situ to Angiotensin II (Ang II), Bradykinin (Bk) and Acetylcholine (Ach) before and after either losartan (10 mg/kg/15 days) or enalapril (15 mg/kg/21 days) treatment. We also evaluated the mesenteric and plasmatic Angiotensin Converting Enzyme (ACE), renal function, lipid plasmatic content, and insulin and glucose metabolism. Intrauterine undernutrition induced hypertension and increased response of mesenteric arterioles to Ang II and decreased vasodilation to Bk and Ach. The treatments with losartan or enalapril normalized the blood pressure levels and significantly improved the arteriolar responses to Bk, Ach and reduced the response to Ang II. No differences have been detected to ACE activity, renal function, lipid content and insulin and glucose metabolism. This study shows for the first time that Renin Angiotensin System inhibitors can normalize the cardiovascular alterations induced by intrauterine undernutrition.     

Influence of Soil Physical Properties on Plants of the Mussununga Ecosystem, Brazil

Distribution ranges of plant species are related to physical variables of ecosystems that limit plant growth. Therefore, each plant species response to physical factors builds up the functional diversity of an ecosystem. The higher the species richness of an ecosystem, the larger the probability of maintaining functions and the higher the potential number of plant functional groups (FGs). Thus, the richness potentially increases the number of functions of the highly diverse Atlantic Rainforest domain in Brazil. Severe plant growth limitations caused by stress, however, decrease species richness. In the Spodosols of the Mussununga, an associated ecosystem of Atlantic Rainforest, the percentage of fine sand is directly related to water retention. Moreover, the depth of the cementation layer in the Mussununga??s sandy soil is a physical factor that can affect the plants?? stress gradients. When a shallow cementation layer depth is combined with low water retention in soils and with low fine sand percentage, the double stresses of flooding in the rainy season and water scarcity in the dry season result. This study aimed to identify FGs among Mussununga plant species responding to water stress gradients of soil and to verify the effects of the gradients on plant species richness of the Mussununga. A canonical correspondence analysis (CCA) of species abundance and soil texture variables was performed on 18 plots in six physiognomies of the Mussununga. Species richness rarefactions were calculated for each vegetation form to compare diversity. The two main axes of the CCA showed two FGs responding to soil texture and cementation layer depth: stress tolerator species and mesic species. Physical variables affect plant diversity, with species richness rising as the fine sand proportion also rises in the Mussununga. The effect of the cementation layer is not significantly related to species richness variation.     

p82H identifies sequences at every human centromere

Summary A cloned alphoid sequence, p82H, hybridizes in situ to the centromere of every human chromosome. After washing under stringent conditions, no more than 8% of the grains are located on any specific chromosome. p82H thus differs from other centromeric sequences which are reported to be chromosome specific, because it detects sequences that are conserved among the chromosomes. Two experimental approaches show that the p82H sequences are closely associated with the centromere. First, p82H remains with the relocated centromeres in an inv(19) and an inv(6) chromosome. Second, p82H hybridizes at the centromere but not to the centromeric heterochromatin of chromosomes 1, 9 and 16 that have elongated 1qh, 9qh and 16qh regions produced by short growth in 5-azacytidine. The only noncentromeric site of hybridization is at the distal end of the 9qh region.     

Early Archean planktonic mode of life: Implications from fluid dynamics of lenticular microfossils

Lenticular, and commonly flanged, microfossils in 3.0–3.4 Ga sedimentary deposits in Western Australia and South Africa are unusually large (20–80 μm across), robust, and widespread in space and time. To gain insight into the ecology of these organisms, we performed simulations of fluid dynamics of virtual cells mimicking lenticular forms of variable sizes, oblateness, flange presence, and flange thickness. Results demonstrate that (a) the flange reduces sedimentation velocity, (b) this flange function works more effectively in larger cells, and (c) modest oblateness lowers sedimentation rate. These observations support interpretations that the lenticular microbes were planktonic—a lifestyle that could have been advantageous in an early Earth harsh environment including violent volcanic activities, repeated asteroid impacts, and relatively high UV‐radiation. Although the robustness of these organisms could have provided additional protection on the early Earth, this architecture may have impeded a planktonic lifestyle by increasing cell density. However, our data suggest that this disadvantage could have been compensated by enlargement of cell volume, which could have enhanced the ability of the flange to slow sedimentation rate, especially if coupled with vacuolation. The results of this simulation study may help to explain the unique morphology and unusually large size of these Archean microfossils.     

Expression of insulin-like growth factor-II and insulin-like growth factor binding proteins during Caco-2 cell proliferation and differentiation

The components of the insulin-like growth factor (IGF) axis and their roles in regulating proliferation and differentiation of the human colon adenocarcinoma cell line, Caco-2, have been investigated. Caco-2 cells proliferated in serum-free medium at 75% the rate observed in medium containing 10% fetal bovine serum. IGF-I (10 nM) increased Caco-2 cell growth in serum-free medium, but not to the rate seen with serum. Multiple IGF-II mRNA species were produced by Caco-2 cells, but IGF-I mRNA was undetectable. Secretion of radioimmunoassayable IGF-II corresponded with steady-state levels of IGF-II mRNA, neither of which was observed to change markedly over the course of 16 days of Caco-2 cell differentiation. Levels of sucrase-isomaltase mRNA, a marker for enterocytic differentiation, increased 12-fold between days 5 and 16 of culture. Northern blotting of total RNA and ligand blot and immunoblot analyses of serum-free conditioned medium revealed that Caco-2 cells produce several IGF binding proteins (IGFBPs), including IGFBP-2, -3, and -4, as well as a 31,000 M, species that was not identified. The pattern of IGFBP secretion changed dramatically during Caco-2 cell differentiation: IGFBP-3 and IGFBP-2 increased 8.5-fold and 5-fold, respectively, whereas IGFBP-4 and the 31,000 M, species decreased 43% and 90%. Caco-2 cell clones stably transfected with a human IGFBP-4 cDNA construct exhibited a 60% increase in steady-state level of IGFBP-4 mRNA, and secreted twice as much IGFBP-4 protein as controls. Moreover, IGFBP-4-overexpressing cells proliferated at only 25% the rate of control cells in serum-free medium, in conjunction with a 70% increase in expression of sucrase-isomaltase. In summary, these studies indicate that a complex IGF axis is involved in autocrine regulation of Caco-2 cell proliferation and differentiation. © 1996 Wiley-Liss, Inc.