Test of the principle of initial value in rat genetic models of exercise capacity

An inverse relationship between initial level of physical capacity and the magnitude of response to training is termed the principle of initial value. We tested the operation of this principle under experimental conditions of minimal genetic and environmental variation. Inbred rat strains previously identified as genetic models of low [Copenhagen (COP)] and high [Dark Agouti (DA)] intrinsic (untrained) exercise capacity were trained for 8 wk on a treadmill using two disparate protocols: 1) a relative mode where each rat exercised daily according to its initial capacity, and 2) an absolute mode where both strains received the same amount of training independent of initial capacity. Response to exercise was the change in running capacity as estimated by meters run to exhaustion before and after training. When trained with the relative mode, COP rats gained 88 m (+21%; NS) whereas DA rats increased distance run by 228 m (+36%; P < 0.001). When each strain trained with the same absolute amount of training, the COP strain showed essentially no change (-6 m, -2%) and the DA strain gained 325 m (+49%; P < 0.009). Differences in response to exercise between the COP and DA could not be explained by body mass differences, oxidative enzyme activity (citrate synthase or ATP), or spontaneous behavioral activity. Our data demonstrate that genetic factors causative of high response to exercise are not uniquely associated with genetic factors for low intrinsic capacity and thus are not in accord with the principle of initial value.     

Effectiveness of latanoprost (Xalatan) monotherapy in newly discovered and previously medicamentously treated primary open angle glaucoma patients

We evaluated the effectiveness of latanoprost (Xalatan) monotherapy in primary open angle glaucoma (POAG). Latanoprost is a prostaglandin analogue, the pure 15(R) epimer of 13,14-dihydro-17-phenyl-18,19,20-trinor-PGF2alpha-isopropyl ester. As a prodrug it is being activated by enzymatic hydrolysis in the cornea after which it becomes active acid of latanoprost. Latanoprost is lowering the intraocular pressure (IOP) by increasing the uveoscleral outflow. In this study, latanoprost was used once daily as monotherapy what offers much better compliance for the patients than other combinations of drugs, preserving good IOP control. Based on the significant reduction of the IOP, measured on the day 60 of the trial (mean change in IOP was -5.1 mmHg, with 95% confidence interval in range from -5.6 to -4.5), it is concluded that use of latanoprost is advisable when calculating better IOP control, few side-effects and reductions in costs of potential surgical procedures.     

Formation and analysis of mannosylerythritol lipids secreted by Pseudozyma aphidis

Pseudozyma aphidis DSM 70725 was found to be a novel producer of mannosylerythritol lipids (MELs). The MELs were quantified by HPLC. Glucose as carbon source for precultivation supported growth well. By contrast, at concentrations >30 g l^–1 in preculture, subsequent MEL formation in the main culture with soybean oil as sole carbon source was reduced. The type of substrate supply considerably influenced MEL formation. High concentrations of soybean oil (80 ml l^–1) at init favored the production process when compared to a stepwise (20 ml l^–1) addition. Mannose or erythritol were suitable second carbon sources that enhanced the MEL yield with soybean oil as preferred primary substrate. After 10 days, a maximum yield of 75 g l^–1 was attained during shake-flask cultivation. Biofuel (rapeseed oil methyl ester) also resulted in high yields of MEL, but glucose reduced the MEL yield. Analysis by GC-MS showed that all fatty acids contained in MEL and derived from soybean oil or related methyl ester were degraded by C2-units to differing extents. The surface (water/air) and interfacial (water/hexadecane) tension of the MELs produced from different carbon sources were reduced to a minimum of 26.2 mN m^–1 and 1 mN m^–1, respectively.     

Phylogenetic and functional diversity of bacterioplankton during Alexandrium spp. blooms

The phylogenetic and functional diversity of the bacterioplankton assemblage associated with blooms of toxic Alexandrium spp. was studied in three harbours of the NW Mediterranean. Denaturing gradient gel electrophoresis and DNA sequence analysis revealed the presence of a bacterium within the Roseobacter clade related to the presence of Alexandrium cells. Phylogenetic diversity was affected by the presence of Alexandrium spp., geographic situation and seasonality. In contrast, functional diversity, assessed with Biolog plates, was clearly affected by seasonality, but not by the presence of Alexandrium, indicating that the presence of the bacterium associated with the blooms was not enough to modify the metabolic pattern of the bacterioplankton assemblage.     

Phosphorylation of EEA1 by p38 MAP kinase regulates mu opioid receptor endocytosis

Morphine analgesic properties and side effects such as tolerance are mediated by the mu opioid receptor (MOR) whose endocytosis is considered of primary importance for opioid pharmacological effects. Here, we show that p38 mitogen-activated protein kinase (MAPK) activation is required for MOR endocytosis and sufficient to trigger its constitutive internalization in the absence of agonist. Further studies established a functional link between p38 MAPK and the small GTPase Rab5, a key regulator of endocytosis. Expression of an activated mutant of Rab5 stimulated endocytosis of MOR ligand-independently in wild-type but not in p38alpha-/- cells. We found that p38alpha can phosphorylate the Rab5 effectors EEA1 and Rabenosyn-5 on Thr-1392 and Ser-215, respectively, and these phosphorylation events regulate the recruitment of EEA1 and Rabenosyn-5 to membranes. Moreover, phosphomimetic mutation of Thr-1392 in EEA1 can bypass the requirement for p38alpha in MOR endocytosis. Our results highlight a novel mechanism whereby p38 MAPK regulates receptor endocytosis under physiological conditions via phosphorylation of Rab5 effectors.     

Development of a strain-specific quantitative method for monitoring Pseudomonas fluorescens EPS62e, a novel biocontrol agent of fire blight

Pseudomonas fluorescens EPS62e has been selected in a screening procedure for its high efficacy controlling Erwinia amylovora infections in flowers, immature fruits and young pear plants. We developed two monitoring methods which allowed specific detection and quantification of EPS62e by combining classical microbiological techniques with molecular tools. RAPD and unspecific-PCR fingerprints were used to differentiate EPS62e from other P. fluorescens strains. Differential amplified fragments from EPS62e were sequence characterized as SCAR markers and two primer pairs were designed and selected for their specificity against EPS62e. A SCAR primer pair was evaluated and validated for the assessment of population dynamics of EPS62e on pear plants under greenhouse conditions using plating and most probable number assays coupled to PCR. Both techniques were useful in monitoring the biological control agent. The population level of EPS62e after treatment was 7 log CFU(gf.w.)(-1), which in turn decreased progressively to 4-5 log CFU(gf.w.)(-1) after 17 days and then remained stable until the end of the assay 11 days later. The limit of detection of both monitoring methods developed was around 3 log CFU(gf.w.)(-1), thus, providing a reliable tool for the analysis of EPS62e in greenhouse or field trials, and the assessment of threshold population levels for efficient biocontrol of fire blight.     

Transmission of Chlamydia pneumoniae infection from blood monocytes to vascular cells in a novel transendothelial migration model

Chlamydia pneumoniae uses blood monocytes (PBMC) for systemic dissemination, persists in atherosclerotic lesions, and has been implicated in the pathogenesis of atherosclerosis. During transmigration in a newly developed transendothelial migration model (TEM) C. pneumoniae-infected PBMC spread their infection to endothelial cells. Transmigrated PBMC retained their infectivity and transmitted the pathogen to smooth muscle cells in the lower chamber of the TEM. Detection of chlamydial HSP60 mRNA proved pathogen viability and virulence. We conclude that PBMC can spread chlamydial infection to vascular wall cells and we suggest the TEM as a novel tool to analyze host-pathogen interactions in vascular chlamydial infections.