Influence of dietary lipids on agonistic and affiliative behavior in Macaca fascicularis

The current study evaluates the hypothesis, derived from previous investigations, that alterations in dietary fat and cholesterol influence the social behavior of monkeys. Subjects were 62 adult male, cynomolgus macaques (Macaca fascicularis) assigned originally to an investigation of atherosclerosis regression. This study thus involves a secondary analysis of data derived from an investigation conducted for another purpose. Animals were housed for 14 months' in social groups of five individuals each and initially fed a diet very high in saturated fat and cholesterol to induce coronary artery atherosclerosis. Monkeys were then exposed for 28 months to one of three conditions; (1) a moderately high-fat, high-cholesterol diet and an unstable social environment (in which monkeys were switched among groups monthly); (2) a low-fat, low-cholesterol diet and an unstable social environment; and (3) a low-fat, low-cholesterol diet and a stable social environment. A comparison of animals living in unstable groups revealed that those consuming the low-fat diet exhibited more overt aggression (P < 0.001) and overt submission (P < 0.01) than did monkeys eating the high-fat diet. A second comparison involved only those animals living in stable social units. These monkeys, while consuming the low-fat diet, engaged in more aggression and submission (P_s < 0.05), spent less time in passive body contact or within touching distance (P_s < 0.001), and spent more time alone (P < 0.001) than they had initially while consuming a very high-fat diet. The current investigation is the first on this topic to include measures of social behavior in animals both before and after a reduction in dietary fat. The findings that such a reduction is associated with increased agonism and decreased affiliation may help explain the epidemiologic association in human beings between low or reduced plasma cholesterol concentrations and a high incidence of violence-related mortality. More generally, the data are consistent with the hypothesis that there is a negative feedback adaptation providing for appropriate changes in behavior in response to periodic dietary privation. © 1996 Wiley-Liss, Inc.     

Changes in diversity and storage function of ectomycorrhiza and soil organoprofile dynamics after introduction of beech into Scots pine forests

Diversity and storage function of mycorrhiza as well as soil organoprofile formation were investigated in a chronosequence of a pure Scots pine (Pinus sylvestris L.) stand, of Scots pine stands that were underplanted with beech (Fagus sylvatica L.) and in three pure beech stands of different age. Mycorrhiza diversity was higher in the pure beech stands compared to the pure pine stand. Beech and pine trees in the mixed stands had similar dominant mycorrhiza morphotypes. However, trees in two of the three pure beech stands were mycorrhized with other types. Mycorrhizal abundance and nutrient amounts of mycorrhizae associated with beech trees were higher in the mixed and in the pure beech stands compared to pine mycorrhizae indicating that nutrient uptake was higher in older beech than in older pine trees. Humus quality varied from pine to beech stands. Plant litter storage in the humus layer was highest in the youngest mixed stand and lowest in the oldest beech stand. Humus forms changed from moder grass-type in the pure Scots pine stand to mor-like moder and moder rich in fine humus with increasing age of beeches in the mixed stands. The older beech stands were characterised by oligomull and mull-like moder as the dominating humus forms. The ecologically favourable humus forms, i.e., nutrient rich humus forms in the older beech stands correlate well with the higher mycorrhizal diversity and abundance as well as the higher nutrient storage of their mycorrhizae in these stands. The results are also discussed with regard to the 'base-pump effect' of beech trees.     

Sodium–Calcium Exchangers of the SLC8 Family in Oligodendrocytes: Functional Properties in Health and Disease

Neurochemical Research - The solute carrier 8 (SLC8) family of sodium–calcium exchangers (NCXs) functions as an essential regulatory system that couples opposite fluxes of sodium and calcium...     

Genome and plastome effects on photosynthesis parameters in Oenothera species of differential low-temperature tolerance

The influence of the plastid genome (plastome) on the temperature dependence of chlorophyll fluorescence parameters was studied in four Oenothera species from climatically different habitats. Equipped with their natural plastome, the species could be arranged with respect to their low-temperature tolerance in the order Oe'villosa' (plastome I) = Oe argillicola (V) > Oe. grandiflora (III) > Oe elata ssp. hookeri (J). Exchanging the naturally occurring plastome with those from other species did not result in changes of the photosynthetic performance of the genotypes, except for decreasing pigment contents and photosynthesis rates (on area basis) in Oe. elata ssp. hookeri with plastome III. Furthermore, plastome exchange in Oe. elata ssp. hookeri and in Oe. grandiflora did not affect kinetic properties of purified ribulose-l,5-bis-phosphate carboxylase/oxygenase (EC 4,1.1.39), indicating that the gene for the large subunit of this enzyme has remained conserved during plastome evolution in Oenothera . It is concluded that the evolution of the plastome in North American Oenothera spp. did not influence the temperature adaptation of the photosynthetic apparatus, but that the latter is governed by effects residing in the nuclear genome.     

Functional and morphological cardiac magnetic resonance imaging of mice using a cryogenic quadrature radiofrequency coil

Cardiac morphology and function assessment by magnetic resonance imaging is of increasing interest for a variety of mouse models in pre-clinical cardiac research, such as myocardial infarction models or myocardial injury/remodeling in genetically or pharmacologically induced hypertension. Signal-to-noise ratio (SNR) constraints, however, limit image quality and blood myocardium delineation, which crucially depend on high spatial resolution. Significant gains in SNR with a cryogenically cooled RF probe have been shown for mouse brain MRI, yet the potential of applying cryogenic RF coils for cardiac MR (CMR) in mice is, as of yet, untapped. This study examines the feasibility and potential benefits of CMR in mice employing a 400 MHz cryogenic RF surface coil, compared with a conventional mouse heart coil array operating at room temperature. The cryogenic RF coil affords SNR gains of 3.0 to 5.0 versus the conventional approach and hence enables an enhanced spatial resolution. This markedly improved image quality - by better deliniation of myocardial borders and enhanced depiction of papillary muscles and trabeculae - and facilitated a more accurate cardiac chamber quantification, due to reduced intraobserver variability. In summary the use of a cryogenically cooled RF probe represents a valuable means of enhancing the capabilities of CMR of mice.     

Mitogen-activated protein kinases interacting kinases are autoinhibited by a reprogrammed activation segment

Autoinhibition is a recurring mode of protein kinase regulation and can be based on diverse molecular mechanisms. Here, we show by crystal structure analysis, nuclear magnetic resonance (NMR)-based nucleotide affinity studies and rational mutagenesis that nonphosphorylated mitogen-activated protein (MAP) kinases interacting kinase (Mnk) 1 is autoinhibited by conversion of the activation segment into an autoinhibitory module. In a Mnk1 crystal structure, the activation segment is repositioned via a Mnk-specific sequence insertion at the N-terminal lobe with the following consequences: (i) the peptide substrate binding site is deconstructed, (ii) the interlobal cleft is narrowed, (iii) an essential Lys-Glu pair is disrupted and (iv) the magnesium-binding loop is locked into an ATP-competitive conformation. Consistently, deletion of the Mnk-specific insertion or removal of a conserved phenylalanine side chain, which induces a blockade of the ATP pocket, increase the ATP affinity of Mnk1. Structural rearrangements required for the activation of Mnks are apparent from the cocrystal structure of a Mnk2 D228G -staurosporine complex and can be modeled on the basis of crystal packing interactions. Our data suggest a novel regulatory mechanism specific for the Mnk subfamily.