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101.
102.
Is gestational diabetes an acquired condition? 总被引:5,自引:0,他引:5
Intrvenous injection of 30 mg of streptozotocin per kg body weight induces a mild diabetes in pregnant rats (first generation); the non-fasting blood glucose is increased and the percentage of endocrine tissue and also the percentage of granulated beta cells do not increase. The fetuses of these mildly diabetic pregnant rats have an increased percentage of pancreatic endocrine tissue and there is beta-cell degranulation. The modifications in the endocrine pancreas during intrauterine life causes persistent changes in later adult life (second generation), which are not perceptible in basal conditions, but become apparent in situations stressing the beta-cell activity, such as an intravenous glucose load or pregnancy. During pregnancy in the second generation rats an increased non-fasting blood glucose and no adaptation of the beta cells is seen. This inadequate adaptation to pregnancy causes changes in the fetal endocrine pancreas of the fetuses of the third generation. From these experiments it may be concluded that gestational diabetes is an acquired condition. 相似文献
103.
Schoonaert K D'Août K Aerts P 《Folia primatologica; international journal of primatology》2006,77(3):246-254
Registering substrate reaction forces from primates during climbing requires the design and construction of customized recording devices. The technical difficulties in constructing a reliable apparatus hinder research on the kinetics of primate locomotion. This is unfortunate since arboreal locomotion, especially vertical climbing, is an important component of the hominoid locomotor repertoire. In this technical paper, we describe a custom-built climbing pole that allows recordings of dynamic 3-dimensional forces during locomotion on horizontal and sloping substrates and during vertical climbing. The pole contains an instrumented section that can readily be modified and enables us to register forces of a single limb or multiple limbs in a broad range of primates. For verification, we constructed a similar set-up (which would not be usable for primates) using a conventional force plate. Data for a human subject walking on both set-ups were compared. The experimental set-up records accurate and reliable substrate reaction forces in three orthogonal directions. Because of its adjustability, this type of modular set-up can be used for a great variety of primate studies. When combining such kinetic measurements together with kinematic information, data of great biomechanical value can be generated. These data will hopefully allow biological anthropologists to answer current questions about primate behaviours on vertical substrates. 相似文献
104.
Nitrogen supply differentially affects litter decomposition rates and nitrogen dynamics of sub-arctic bog species 总被引:5,自引:0,他引:5
High-latitude peatlands are important soil carbon sinks. In these ecosystems, the mineralization of carbon and nitrogen are
constrained by low temperatures and low nutrient concentrations in plant litter and soil organic matter. Global warming is
predicted to increase soil N availability for plants at high-latitude sites. We applied N fertilizer as an experimental analogue
for this increase. In a three-year field experiment we studied N fertilization effects on leaf litter decomposition and N
dynamics of the four dominant plant species (comprising >75% of total aboveground biomass) in a sub-arctic bog in northern
Sweden. The species were Empetrum nigrum (evergreen shrub), Eriophorum vaginatum (graminoid), Betula nana (deciduous shrub) and Rubus chamaemorus (perennial forb). In the controls, litter mass loss rates increased in the order: Empetrum < Eriophorum < Betula < Rubus. Increased N availability had variable, species-specific effects: litter mass loss rates (expressed per unit litter mass)
increased in Empetrum, did not change in Eriophorum and Betula and decreased in Rubus. In the leaf litter from the controls, we measured no or only slight net N mineralization even after three years. In the
N-fertilized treatments we found strong net N immobilization, especially in Eriophorum and Betula. This suggests that, probably owing to substantial chemical and/or microbial immobilization, additional N supply does not
increase the rate of N cycling for at least the first three years. 相似文献
105.
Cornelissen JH Quested HM van Logtestijn RS Pérez-Harguindeguy N Gwynn-Jones D Díaz S Callaghan TV Press MC Aerts R 《Oecologia》2006,147(2):315-326
Plant traits have become popular as predictors of interspecific variation in important ecosystem properties and processes.
Here we introduce foliar pH as a possible new plant trait, and tested whether (1) green leaf pH or leaf litter pH correlates
with biochemical and structural foliar traits that are linked to biogeochemical cycling; (2) there is consistent variation
in green leaf pH or leaf litter pH among plant types as defined by nutrient uptake mode and higher taxonomy; (3) green leaf
pH can predict a significant proportion of variation in leaf digestibility among plant species and types; (4) leaf litter
pH can predict a significant proportion of variation in leaf litter decomposability among plant species and types. We found
some evidence in support of all four hypotheses for a wide range of species in a subarctic flora, although cryptogams (fern
allies and a moss) tended to weaken the patterns by showing relatively poor leaf digestibility or litter decomposability at
a given pH. Among seed plant species, green leaf pH itself explained only up to a third of the interspecific variation in
leaf digestibility and leaf litter up to a quarter of the interspecific variation in leaf litter decomposability. However,
foliar pH substantially improved the power of foliar lignin and/or cellulose concentrations as predictors of these processes
when added to regression models as a second variable. When species were aggregated into plant types as defined by higher taxonomy
and nutrient uptake mode, green-specific leaf area was a more powerful predictor of digestibility or decomposability than
any of the biochemical traits including pH. The usefulness of foliar pH as a new predictive trait, whether or not in combination
with other traits, remains to be tested across more plant species, types and biomes, and also in relation to other plant or
ecosystem traits and processes. 相似文献
106.
107.
Vanden Wymelenberg A Minges P Sabat G Martinez D Aerts A Salamov A Grigoriev I Shapiro H Putnam N Belinky P Dosoretz C Gaskell J Kersten P Cullen D 《Fungal genetics and biology : FG & B》2006,43(5):343-356
The white-rot basidiomycete Phanerochaete chrysosporium employs extracellular enzymes to completely degrade the major polymers of wood: cellulose, hemicellulose, and lignin. Analysis of a total of 10,048 v2.1 gene models predicts 769 secreted proteins, a substantial increase over the 268 models identified in the earlier database (v1.0). Within the v2.1 'computational secretome,' 43% showed no significant similarity to known proteins, but were structurally related to other hypothetical protein sequences. In contrast, 53% showed significant similarity to known protein sequences including 87 models assigned to 33 glycoside hydrolase families and 52 sequences distributed among 13 peptidase families. When grown under standard ligninolytic conditions, peptides corresponding to 11 peptidase genes were identified in culture filtrates by mass spectrometry (LS-MS/MS). Five peptidases were members of a large family of aspartyl proteases, many of which were localized to gene clusters. Consistent with a role in dephosphorylation of lignin peroxidase, a mannose-6-phosphatase (M6Pase) was also identified in carbon-starved cultures. Beyond proteases and M6Pase, 28 specific gene products were identified including several representatives of gene families. These included 4 lignin peroxidases, 3 lipases, 2 carboxylesterases, and 8 glycosyl hydrolases. The results underscore the rich genetic diversity and complexity of P. chrysosporium's extracellular enzyme systems. 相似文献
108.
Gene expression profiles can be regarded as sums of simpler modes, analogous to the modes of a vibrating violin string. Decomposition of temporal gene expression profiles into modes by singular value decomposition (SVD) was reported before, but the question as to what degree the SVD modes can be interpreted in terms of biology remains open. We report and compare the results of SVD of published datasets from hippocampal development, neuronal differentiation in vitro, and a control time-series hippocampal dataset. We demonstrate that the first SVD mode reflects the magnitude of expression, interpretable on the Affymetrix platform. In the datasets from gene profiling of hippocampal development and neuronal differentiation, the second mode reflects a monotonous change in expression, either up- or down-regulation, in the time course of experiment. We demonstrate that the top two SVD modes are conserved between datasets and therefore, likely reflect properties of the underlying system (gene expression in hippocampus) rather than of a particular experiment or dataset. Our results also indicate that the magnitude of expression, and the direction of change in expression during hippocampal development, are uncorrelated, suggesting that they are regulated by largely independent mechanisms. 相似文献
109.
Engelborghs S Maertens K Vloeberghs E Aerts T Somers N Mariën P De Deyn PP 《Neurochemistry international》2006,48(4):286-295
To improve clinical, neuropsychological and behavioural characterisation of the cerebrospinal fluid (CSF) biomarkers beta-amyloid((1-42)) protein (Abeta42), protein tau (tau) and tau phosphorylated at threonine 181 (P-tau181) across diagnostic dementia categories, a prospective study was set up. Patients with probable Alzheimer's disease (AD) (n=201), AD with cerebrovascular disease (CVD) (AD+CVD) (n=33), frontotemporal dementia (FTD) (n=27), dementia with Lewy bodies (DLB) (n=22) and healthy controls (n=148) were included. All patients underwent neuropsychological examination and behavioural assessment by means of a battery of behavioural assessment scales. CSF was obtained by lumbar puncture and levels of Abeta42, tau and P-tau181 were determined with commercially available ELISA kits. Negative correlations between CSF Abeta42 levels and aggressiveness (Spearman: r=-0.223; p=0.002) and positive correlations with age at inclusion (r=0.195; p=0.006), age at onset (r=0.205; p=0.003) and MMSE scores (r=0.198; p=0.005) were found in AD. In AD+CVD, CSF Abeta42 levels were correlated with MMSE (r=0.482; p=0.006), Hierarchic Dementia Scale (r=0.503; p=0.017) and Boston Naming Test (r=0.516; p=0.012) scores. In controls, age was positively correlated with CSF tau (r=0.465; p<0.001) and P-tau181 levels (r=0.312; p<0.001). CSF tau and P-tau181 levels correlated significantly in all groups, whereas CSF Abeta42 correlated with tau and P-tau181 levels in healthy controls only. Negative correlations between CSF Abeta42 levels and aggressiveness were found in AD patients. CSF Abeta42 seems to be a stage marker for AD (+/-CVD) given the positive correlations with neuropsychological test results suggesting that CSF Abeta42 might be of help for monitoring disease progression. Different correlations between age and CSF biomarker levels were obtained in healthy controls compared to AD patients, indicating that AD-induced pathophysiological processes change age-dependent regulation of CSF biomarker levels. 相似文献
110.
Glomulin is predominantly expressed in vascular smooth muscle cells in the embryonic and adult mouse
McIntyre BA Brouillard P Aerts V Gutierrez-Roelens I Vikkula M 《Gene expression patterns : GEP》2004,4(3):351-358
Mutations in the glomulin gene result in dominantly inherited vascular lesions of the skin known as glomuvenous malformations (GVMs). These lesions are histologically distinguished by their distended vein-like channels containing characteristic 'glomus cells', which appear to be incompletely or improperly differentiated vascular smooth muscle cells (VSMCs). The function of glomulin is currently unknown. We studied glomulin expression during murine development (E9.5 days post-coitum until adulthood) by non-radioactive in situ hybridization. Glomulin was first detected at E10.5 dpc in cardiac outflow tracts. Later, it showed strong expression in VSMCs as well as a limited expression in the perichondrium. At E11.5-14.5 dpc glomulin RNA was most abundant in the walls of the large vessels. At E16.5 dpc expression was also detectable in smaller arteries and veins. The high expression of glomulin in murine vasculature suggests an important role for glomulin in blood vessel development and/or maintenance, which is supported by the vascular phenotype seen in GVM patients with mutations in this gene. 相似文献