Chronic alterations in ovine maternal corticosteroid levels influence uterine blood flow and placental and fetal growth

Previous work from this laboratory demonstrated that the elevation of maternal plasma corticosteroid concentrations during pregnancy is important for the support of fetal development. Reducing ovine maternal plasma cortisol concentrations to nonpregnant levels stimulates homeostatic responses that defend fetal blood volume. The present study was designed to test the hypothesis that chronic decreases or increases in maternal plasma cortisol concentration alter uterine and placental blood flow and morphology. Three groups of pregnant ewes and their fetuses were chronically catheterized and studied: ewes infused with cortisol (1 mg.kg(-1).day(-1); high cortisol), ewes adrenalectomized and underreplaced with cortisol (0.5 mg.kg(-1).day(-1); low cortisol), and control ewes. The normal increment in uterine blood flow between 120 and 130 days was eliminated in the low-cortisol ewes; conversely, uterine blood flow was increased in the high-cortisol group compared with the control group. Fetal arterial blood pressure was increased in the high-cortisol group compared with controls, but there was no increase in fetal arterial pressure from 120 to 130 days of gestation in the low-cortisol group. The fetuses of both low-cortisol and high-cortisol groups had altered placental morphology, with increased proportions of type B placentomes, and overall reduced fetal placental blood flow. The rate of fetal somatic growth was impaired in both low-cortisol and high-cortisol groups compared with the fetuses in the intact group. The results of this study demonstrate that maternal plasma cortisol during pregnancy is an important contributor to the maternal environment supporting optimal conditions for fetal homeostasis and somatic growth.     

Nitrogen Loss and Denitrification as Studied in Relation to Reductions in Nitrogen Loading in a Shallow,Hypertrophic Lake (Lake Søbygård,Denmark)

A detailed mass balance on nitrogen was carried out in shallow and hypertrophic Lake Søbygård during 4.5 years before through 2.5 years after a 36 % reduction in nitrogen loading. Annual mean loss rate of nitrogen was 159–229 mg N m⁻² d⁻¹ before the loading reduction and 125 mg N m⁻² d⁻¹ after. In spite of a short hydraulic retention time (18–27 days) the proportion of nitrogen loading lost in the lake was high (38–53 %) and not affected by changes in loading. Calculated denitrification accounted for 86–93% of the loss rate, while 7–14% was permanently buried. Marked seasonal variations in the loss percentage were found during the season, ranging from 23 % in first quarter to 65 % in third quarter. The seasonal variation in the loss percentage of nitrogen showed a hysteresis like relationship to temperature, with a high percentage in fourth quarter. This suggests that the amount of available substrate, which mainly consists of sedimentated phytoplankton, accumulated during summer, is an important regulating factor. The ability of various published input-output models to predict the observed changes in in-lake nitrogen concentration in Lake Søbygård was tested. This study has further confirmed that small lakes with short retention and high nitrogen loading may significantly reduce the nitrogen loading of downstream aquatic environments.     

Calcitonin gene-related peptide, neurokinin A and substance P: effects on nociception and neurogenic inflammation in human skin and temporal muscle.

Calcitonin gene-related peptide (CGRP) was injected alone and in combination with substance P (SP) or neurokinin A (NKA) into the forearm skin and temporal muscle of human volunteers. In the skin, 50 pmol of CGRP induced a wheal response and a delayed erythema. No pain was recorded. No interaction between CGRP and SP or NKA was observed. In the temporal muscle, 200 pmol of CGRP alone did not induce pain or tenderness but, in combination with SP or NKA, CGRP elicited a significant pain sensation. It is concluded that CGRP may be involved in neurogenic inflammation and that only SP, of the three peptides present in nociceptive C fibers, seems to be of major importance in relation to cutaneous nociception. Simultaneous neurogenic release of CGRP and other neuropeptides in skeletal muscle may induce myofascial pain.     

Qualitative Analyses of Polishing and Precoating FIB Milled Crystals for MicroED

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Alpha-synuclein association with phosphatidylglycerol probed by lipid spin labels

Alpha-synuclein is a small presynaptic protein, which is linked to the development of Parkinson's disease. Alpha-synuclein partitions between cytosolic and vesicle-bound states, where membrane binding is accompanied by the formation of an amphipathic helix in the N-terminal section of the otherwise unstructured protein. The impact on alpha-synuclein of binding to vesicle-like liposomes has been studied extensively, but far less is known about the impact of alpha-synuclein on the membrane. The interactions of alpha-synuclein with phosphatidylglycerol membranes are studied here by using spin-labeled lipid species and electron spin resonance (ESR) spectroscopy to allow a detailed analysis of the effect on the membrane lipids. Membrane association of alpha-synuclein perturbs the ESR spectra of spin-labeled lipids in bilayers of phosphatidylglycerol but not of phosphatidylcholine. The interaction is inhibited at high ionic strength. The segmental motion is hindered at all positions of spin labeling in the phosphatidylglycerol sn-2 chain, while still preserving the chain flexibility gradient characteristic of fluid phospholipid membranes. Direct motional restriction of the lipid chains, resulting from penetration of the protein into the hydrophobic interior of the membrane, is not observed. Saturation occurs at a protein/lipid ratio corresponding to approximately 36 lipids/protein added. Alpha-synuclein exhibits a selectivity of interaction with different phospholipid spin labels when bound to phosphatidylglycerol membranes in the following order: stearic acid > cardiolipin > phosphatidylcholine > phosphatidylglycerol approximately phosphatidylethanolamine > phosphatidic acid approximately phosphatidylserine > N-acyl phosphatidylethanolamine > diglyceride. Accordingly, membrane-bound alpha-synuclein associates at the interfacial region of the bilayer where it may favor a local concentration of certain phospholipids.     

Caspase-mediated parkin cleavage in apoptotic cell death

The parkin protein is important for the survival of the neurons that degenerate in Parkinson's disease as demonstrated by disease-causing lesions in the parkin gene. The Chinese hamster ovary and the SH-SY5Y cell line stably expressing recombinant human parkin combined with epitope-specific parkin antibodies were used to investigate the proteolytic processing of human parkin during apoptosis by immunoblotting. Parkin is cleaved during apoptosis induced by okadaic acid, staurosporine, and camptothecin, thereby generating a 38-kDa C-terminal fragment and a 12-kDa N-terminal fragment. The cleavage was not significantly affected by the disease-causing mutations K161N, G328E, T415N, and G430D and the polymorphism R366W. Parkin and its 38-kDa proteolytic fragment is preferentially associated with vesicles, thereby indicating that cleavage is a membrane-associated event. The proteolysis is sensitive to inhibitors of caspases. The cleavage site was mapped by site-directed mutagenesis of potential aspartic residues and revealed that mutation of Asp-126 alone abrogated the parkin cleavage. The tetrapeptide aldehyde LHTD-CHO, representing the amino acid sequence N-terminal to the putative cleavage site was an efficient inhibitor of parkin cleavage. This suggests that parkin function is compromised in neuropathological states associated with an increased caspase activation, thereby further adding to the cellular stress.     

Short-range spatial variability of soil δ15N natural abundance – effects on symbiotic N2-fixation estimates in pea

The δ¹⁵N natural abundance (‰) of the total soil N pool varies at the landscape level, but knowledge on short-range variability and consequences for the reliability of isotopic methods are poorly understood. The short-range spatial variability of soil δ¹⁵N natural abundance as revealed by the ¹⁵N abundance in spring barley and N₂-fixing pea was measured within the 0.15–4 m scale at flowering and at maturity. The short-range spatial variability of soil δ¹⁵N natural abundance and symbiotic nitrogen fixation were high at both growth stages. Along a 4-m row, the δ¹⁵N natural abundance in barley reference plants varied up to 3.9‰, and sometimes this variability was observed even between plants grown only 30 cm apart. The δ¹⁵N natural abundance in pea varied up to 1.4‰ within the 4-m row. The estimated percentage of nitrogen derived from the atmosphere (%Ndfa) varied from 73–89% at flowering and from 57–95% at maturity. When increasing the sampling area from 0.01 m² (single plants) and up to 0.6 m² (14 plants) the %Ndfa coefficient of variation (CV) declined from 5 to 2% at flowering and from 12 to 2% at maturity. The implications of the short-range variability in δ¹⁵N natural-abundance are that estimates of symbiotic N₂-fixation can be obtained from the natural abundance method if at least half a square meter of crop and reference plants is sampled for the isotopic analysis. In fields with small amounts of representative reference crops (weeds) it might be necessary to sow in reference crop species to secure satisfying N₂-fixation estimates.