Sexual dimorphism of body size and sternopleural bristle number: a comparison of geographic populations of an invasive cosmopolitan drosophilid

Zaprionus indianus is a cosmopolitan drosophilid, of Afrotropical origin, which has recently colonized South America. The sexual dimorphism (SD) of body size is low, males being almost as big as females. We investigated 10 natural populations, 5 from America and 5 from Africa, using the isofemale line technique. Three traits were measured on each fly: wing and thorax length and sternopleural bristle number. Two indices of SD were compared, and found to be highly correlated (r > 0.99). For the sake of simplicity, only the female/male (F/M) ratio was further considered. A significant genetic variability of SD was found in all cases, although with a low heritability (intra-class correlation of 0.13), about half the value found for the traits themselves. For size SD, we did not find any variation among continents or any latitudinal trend, and average values were 1.02 for wing length and 1.01 for thorax length. Bristle number SD was much greater (1.07). Among mass laboratory strains, SD was genetically much more variable than in recently collected populations, a likely consequence of laboratory drift. Altogether, SD, although genetically variable and prone to laboratory drift, is independent of size variations and presumably submitted to a stabilizing selection in nature.     

Biophysics of sphingolipids I. Membrane properties of sphingosine, ceramides and other simple sphingolipids

Some of the simplest sphingolipids, namely sphingosine, ceramide, some closely related molecules (eicosasphingosine, phytosphingosine), and their phosphorylated compounds (sphingosine-1-phosphate, ceramide-1-phosphate), are potent metabolic regulators. Each of these lipids modifies in marked and specific ways the physical properties of the cell membranes, in what can be the basis for some of their physiological actions. This paper reviews the mechanisms by which these sphingolipid signals, sphingosine and ceramide in particular, are able to modify the properties of cell membranes.     

The influence of β-cyclodextrin on the kinetics of progesterone transformation by Rhizopus nigricans

The process of progesterone 11α-hydroxylation by the pelleted growth form of the filamentous fungus Rhizopus nigricans has been described with a mathematical model, based on Michaelis-Menten enzyme kinetics and the rate of substrate dissolution. It was confirmed that the low water solubility of steroids is the limiting step of this process at high steroid concentrations. In order to overcome this problem, β-cyclodextrin, which is known to form inclusion complexes with these organic compounds, was added to the production medium. The phase solubility of the steroid-β-cyclodextrin system was investigated and the effect of β-cyclodextrin addition on progesterone biotransformation evaluated. Enhancement of steroid solubility was demonstrated and nearly two-fold increase in reaction rate was found in the presence of β-cyclodextrin.     

Novel pharmacological TRPC inhibitors block hypoxia-induced vasoconstriction

The Ca(2+)-permeable, nonselective cation channel TRPC6 is gated via phospholipase C-activating receptors and has recently been implicated in hypoxia-induced pulmonary vasoconstriction (HPV), idiopathic pulmonary hypertension and focal segmental glomerulosclerosis (FSGS). Therefore, TRPC6 is a promising target for pharmacological interference. To identify and develop TRPC6-blocking compounds, we screened the Chembionet library, a collection of 16,671 chemically diverse drug-like compounds, for biological activity to prevent the 1-oleoyl-2-acetyl-sn-glycerol-triggered Ca(2+) influx in a stably transfected HEK(TRPC6-YFP) cell line. Hits were validated and characterised by fluorometric and electrophysiological methods. Six compounds displayed inhibitory potency at low micromolar concentrations, lack of cytotoxicity and blocked the receptor-dependent mode of TRPC6 activation. The specificity was tested towards closely (TRPC3 and TRPC7) and more distantly related TRP channels. One of the compounds, 8009-5364, displayed a 2.5-fold TRPC6-selectivity compared to TRPC3, and almost no inhibition of TRPC7 or the other TRP channels tested. Block of native TRPC3/6-like responses was confirmed in dissociated pulmonary artery smooth muscle cells. Two non-polar blockers effectively suppressed the HPV responses in the perfused mouse lung model. We conclude that pharmacological targeting of TRPC6 is feasible and provide a promising concept to treat pulmonary diseases that are characterised by excessive hypoxic vasoconstriction.     

Tropospheric ozone-induced structural changes in leaf mesophyll cell walls in grapevine plants

The structural changes in leaves of grapevine plants (Vitis vinifera L.) exposed to different ozone concentrations were investigated. Ozone fumigations were performed in open-top chambers at four different ozone levels (charcoal-filtered air (F), ambient air (N), ambient air + 25 mm³m⁻³ ozone (O-25) and ambient air + 50 mm³m⁻³ ozone (O-50)). The leaves of plants from chambers with increased ozone concentrations (O-25 and O-50) were significantly thicker than the controls (F), owing to increased thickness of the mesophyll layer. Observing O-50 leaves, it was found that the mesophyll cell wall displayed structural changes. In some places cell wall thickness increased up to 1 μm. We found callose deposits on the inner side of the cell walls of mesophyll cells. These data are in accord with the concept that the mesophyll cell wall acts as a barrier against the penetration of tropospheric ozone into the cells.     

Synthesis and chemical behaviour of D-glucosyl esters of glutamic acid having the side-chain carboxyl group involved in the glycosidic linkage.

Simultaneous and stepwise deprotection of the fully benzylated D-glucosyl esters of 1-benzyl N-benzyloxycarbonyl- and N-tert-butyloxycarbonyl-L-glutamic acid (1 and 5, respectively) have been examined. Catalytic hydrogenation of 1 led to intramolecular aminolysis to give pyroglutamic acid and D-glucose, but similar treatment in the presence of trifluoroacetic acid afforded both anomers of 1-O-(L-gamma-glutamyl)-D-glucopyranose, which were characterized as trifluoroacetates (2alpha and 2beta) and converted into 2,3,4,6-tetra-O-acetyl-1-O-[1-methyl N-(acetyl)-L-glutam-5-oyl]-D-glucopyranose (4) which was also prepared by a definitive method. Hydrogenolysis of 5 gave both anomers of 1-O-[N-(tert-butyloxycarbonyl)-L-gamma-glutamyl]-D-glucopyranose (6), which, upon treatment with trifluoroacetic acid at - 10 degrees, afforded 2alpha and 2beta, respectively. The structure of 6beta was established by its conversion into 2,3,4,6-tetra-O-acetyl-1-O-[1-methyl N-(tert-butyloxycarbonyl)-L-glutam-5-oyl]-beta-D-glucopyranose (7beta), whereas similar treatment of 6alpha gave a mixture of 1,3,4,6-tetra-O-acetyl-2-O-[1-methyl N-(tert-butyloxycarbonyl)-L-glutam-5-oyl]-alpha-D-glucopyranose (9) and 7alpha. A 1 leads to 2 acyl migration occurred during esterification of the aglycon carboxyl group of 6alpha with diazomethane to give 2-O-[1-methyl N-(tert-butyloxycarbonyl)-L-glutam-5-oyl]-alpha-D-glucopyranose (8).     

A practical validation approach for virus titer testing of avian infectious bursal disease live vaccine according to current regulatory guidelines

The method for virus titer determination of avian infectious bursal disease (IBD) live vaccine, developed long before regulatory validation guidelines is a cell culture based biological assay intended for use in vaccine release testing.The aim of our study was to perform a validation, based on fit-for-purpose principle, of an old 50% tissue culture infectious dose (TCID₅₀) method according to Guidelines of the International Cooperation on Harmonization of Technical Requirements for Registration of Veterinary Medicinal Products (VICH).This paper addresses challenges and discusses some key aspects that should be considered when validating biological methods. A different statistical approach and non-parametric statistics was introduced in validation protocol in order to derive useful information from experimental data. This approach is applicable for a wide range of methods.In conclusion, the previous virus titration method had showed to be precise, accurate, linear, robust and in accordance with current regulatory standards, which indicates that there is no need for additional re-development or upgrades of the method for its suitability for intended use.     

Checklist of the infraorder Tipulomorpha (Trichoceridae,Tipuloidea) (Diptera) of Finland

A checklist of the infraorder Tipulomorpha: families Trichoceridae, Pediciidae, Limoniidae, Cylindrotomidae and Tipulidae (Diptera) recorded from Finland.     

Sequential requirements of the N-terminal palmitoylation site and SH2 domain of Src family kinases in the initiation and progression of FcepsilonRI signaling

Initial biochemical signaling originating from high-affinity immunoglobulin E receptor (FcepsilonRI) has been ascribed to Src family kinases. To understand the mechanisms by which individual kinases drive the signaling, we conducted reconstitution experiments: FcepsilonRI signaling in RBL2H3 cells was first suppressed by a membrane-anchored, gain-of-function C-terminal Src kinase and then reconstructed with Src family kinases whose C-terminal negative regulatory sequence was replaced with a c-myc epitope. Those constructs derived from Lyn and Fyn, which are associated with detergent-resistant membranes (DRMs), physically interacted with resting FcepsilonRI and reconstructed clustering-induced signaling that leads to calcium mobilization and ERK1 and -2 activation. c-Src-derived construct, which was excluded from DRMs, failed to interact with FcepsilonRI and to restore the signaling, whereas creation of palmitoylatable Cys3 enabled it to interact with DRMs and with FcepsilonRI and to restore the signaling. Deletion of Src homology 3 (SH3) domain from the Lyn-derived construct did not alter its ability to transduce the series of signaling. Deletion of SH2 domain did not affect its association with DRMs and with FcepsilonRI nor clustering-induced tyrosine phosphorylation of FcepsilonRI beta and gamma subunits, but it almost abrogated the next step of tyrosine phosphorylation of Syk and its recruitment to FcepsilonRI. These findings suggest that Lyn and Fyn could, but c-Src could not, drive FcepsilonRI signaling and that N-terminal palmitoylation and SH2 domain are required in sequence for the initial interaction with FcepsilonRI and for the signal progression to the molecular assembly.     

Diurnal pattern of acetaldehyde emission by flooded poplar trees

The emission of the tropospheric trace gas acetaldehyde was determined in leaves of 4-month-old poplar trees ( Populus tremula × P. alba ) grown under controlled environmental conditions in a greenhouse. Using a dynamic cuvette system together with a high sensitivity laser-based photoacoustic detection unit, rates of acetaldehyde emission were measured with the high time resolution of about 15 min. Submergence of the roots resulted in the emission of acetaldehyde by the leaves. The emission increased linearly before reaching more or less steady-state values (ca 350 nmol m⁻² min⁻¹; ca 470 ng g⁻¹ dry weight min⁻¹) after approximately 6 h. Prolonged flooding of poplar trees resulted in a clear diurnal rhythm of acetaldehyde emission. The emission rates decreased when the light was switched off in the evening and peaked in the morning after the light was turned on again. This pattern significantly correlated with diurnal rhythms of stomatal conductance, photosynthesis, transpiration and with the concentrations of ethanol, the assumed precursor of acetaldehyde, in the xylem sap of flooded poplar trees. It may be concluded that under conditions of diminished stomatal conductance, acetaldehyde emission declines because its diffusive flux is reduced. Alternatively, reduced transpiration may decrease ethanol transport from the roots to the shoots and appreciable amounts of the acetaldehyde precursor ethanol are lacking in the leaves. The present results support the view that acetaldehyde emitted by the leaves of plants is derived from ethanol produced by alcoholic fermentation in submerged roots and transported to the leaves with the transpiration stream.