Atypical Aeromonas salmonicida Isolated from Diseased Turbot (Scophtalmus maximus L.)

Atypical Aeromonas salmonicida were isolated from 3 outbreaks of disease among farmed turbot (Scophthalmus maximus L.) in 3 different farms, 1 from Norway (Nl) and 2 from Denmark (DK1 and DK2). In all 3 cases, the incidence of disease and mortality was high and the main characteristic pathological finding was skin ulcers and septicaemia. The isolated bacteria were subjected to a thorough phenotypic and genotypic examination and comparison in the laboratory. All 3 isolates belonged to A. salmonicida but dis-played some very different biochemical properties. However, the 2 Danish strains, DK1 and DK2 had identical ribotypes but different from that of Nl, whereas the plasmid pro-files of DK1 and Nl were identical but different from that of DK2. These observations emphasize the need for an improvement of our understanding of the taxonomy and epi-demiology of atypical A. salmonicida.     

Gas compression in lungs decreases peak expiratory flow depending on resistance of peak flowmeter

Pedersen, O. F., T. F. Pedersen, and M. R. Miller. Gascompression in lungs decreases peak expiratory flow depending onresistance of peak flowmeter. J. Appl.Physiol. 83(5): 1517-1521, 1997.It has recentlybeen shown (O. F. Pedersen T. R. Rasmussen, Ø. Omland, T. Sigsgaard, P. H. Quanjer, and M. R. Miller. Eur. Respir. J. 9: 828-833, 1996) that the addedresistance of a mini-Wright peak flowmeter decreases peak expiratoryflow (PEF) by ~8% compared with PEF measured by a pneumotachograph.To explore the reason for this, 10 healthy men (mean age 43 yr, range33-58 yr) were examined in a body plethysmograph with facilitiesto measure mouth flow vs. expired volume as well as the change inthoracic gas volume (Vb) and alveolar pressure(PA). The subjects performed forced vital capacity maneuvers through orifices of different sizes andalso a mini-Wright peak flowmeter. PEF with the meter and other addedresistances were achieved when flow reached the perimeter of theflow-Vb curves. The mini-Wright PEF meter decreased PEF from 11.4 ± 1.5 to 10.3 ± 1.4 (SD) l/s(P < 0.001),PA increased from 6.7 ± 1.9 to 9.3 ± 2.7 kPa (P < 0.001), anincrease equal to the pressure drop across the meter, and caused Vb atPEF to decrease by 0.24 ± 0.09 liter(P < 0.001). We conclude that PEF obtained with an added resistance like a mini-Wright PEF meter is awave-speed-determined maximal flow, but the added resistance causes gascompression because of increasedPA at PEF. Therefore, Vb at PEFand, accordingly, PEF decrease.

     

Appomattoxia ancistrophora gen. et sp. nov., a new Early Cretaceous plant with similarities to Circaeaster and extant Magnoliidae

A new genus and species of fossil angiosperm (Appomattoxia ancistrophora) is established based on well-preserved fruiting units and associated pollen from the Early Cretaceous (Early or Middle Albian) Puddledock locality in the Potomac Group sequence of Virginia, eastern North America. Fruiting units are small, unilocular, and with a single, pendulous, orthotropous seed. The fruit surface is characterized by densely spaced unicellular spines with hooklike tips, which probably functioned in biotic dispersal. Pollen grains adhering to the stigmatic area of many specimens are monocolpate and tectate with granular to columellate infratectal structure, and are similar to dispersed grains assigned to Tucanopollis and Transitoripollis. Comparison of fossil Appomattoxia ancistrophora with extant plants reveals an unusual combination of characters that includes similarities with some magnoliid taxa, particularly Piperales (Piperaceae, Saururaceae) and Laurales (Chloranthaceae), as well as the monotypic ranunculid family Circaeasteraceae. Appomattoxia ancistrophora differs from extant Piperales in having a pendulous rather than erect ovule, and differs from extant Circaeaster in details of the fruit wall, as well as the presence of monosulcate rather than tricolpate pollen.     

Site selective bis-intercalation of a homodimeric thiazole orange dye in DNA oligonucleotides.

We have used one and two dimensional 1H NMR spectroscopy to characterize the binding of a homodimeric thiazole orange dye, 1,1'-(4,4,8,8-tetramethyl-4,8-diaza-undecamethylene)-bis-4- (3-methyl-2,3-dihydro-(benzo-1,3-thiazole)-2-methylidene)-quinolin ium tetraiodide (TOTO), to various double stranded DNA oligonucleotides. TOTO binds strongly to all the oligonucleotides used, but usually more than one complex is observed and exchange between different binding sites broadens the lines in the NMR spectra. Complete precipitation occurs when TOTO is bound to small oligonucleotides. Binding to larger oligonucleotides occurs by bis-intercalation. The 1:1 complex of TOTO with the oligonucleotide d(CCGACTGATGC):d (GCATCAGTCGG) gave only one complex that was shown to be a bis-intercalation in the CTGA:TCAG binding site. The binding to this site was also characterized by studying the TOTO complex with the d(CCGCTGAGC):d(GCTCAGCGG) oligonucleotide. NOE connectivities and molecular modelling were used to characterize the complex. The 1:1 complex of TOTO with the oligonucleotide d(CCGCTAGCG):d(CGCTAGCGG) containing a CTAG:CTAG binding site was similarly characterized by NMR. It was concluded that the binding of TOTO to larger oligonucleotides is site selective with CTAG:CTAG as the preferred binding site.     

The first solvation shell of magnesium ion in a model protein environment with formate,water, and X-NH3, H2S,imidazole, formaldehyde,and chloride as ligands: An ab initio study

The first coordination shell of an Mg(II) ion in a model protein environment is studied. Complexes containing a model carboxylate, an Mg(II) ion, various ligands (NH₃, H₂S, imidazole, and formaldehyde) and water of hydration about the divalent metal ion were geometry optimized. We find that for complexes with the same coordination number, the unidentate carboxylate–Mg(II) ion is greater than 10 kcal mol^?1 more stable than the bidentate orientation. Imidazole was found to be the most stable ligand, followed in order by NH₃ formaldehyde, H₂O, and H₂S. © 1995 Wiley-Liss, Inc.     

Removal of toluene in waste gases using a biological trickling filter

The removal of toluene from waste gas was studied in a trickling biofilter. A high level of water recirculation (4.7 m h^–1) was maintained in order to keep the liquid phase concentration constant and to achieve a high degree of wetting. For loads in the range from 6 to 150 g m^–3 h^–1 the maximum volumetric removal rate (elimination capacity) was 35±10 g m^–3 h^–1, corresponding to a zero order removal rate of 0.11±0.03 g m^–2 h^–1 per unit of nominal surface area. The surface removal was zero order above the liquid phase concentrations of approximately 1.0 g m^–3, corresponding to inlet gas concentrations above 0.7–0.8 g m^–3. Below this concentration the surface removal was roughly of first order. The magnitude of the first order surface removal rate constant, k_1A , was estimated to be 0.08–0.27 m h^–1 (k_1A a=24–86 h^–1). Near-equilibrium conditions existed in the gas effluent, so mass transfer from gas to liquid was obviously relatively fast compared to the biological degradation. An analytical model based on a constant liquid phase concentration through the trickling filter column predicts the effluent gas concentration and the liquid phase concentration for a first and a zero order surface removal. The experimental results were in reasonable agreement with a very simple model valid for conditions with an overall removal governed by the biological degradation and independent of the gas/liquid mass transfer. The overall liquid mass transfer coefficient, K_La, was found to be a factor 6 higher in the system with biofilm compared to the system without. The difference may be explained by: 1. Difference in the wetting of the packing material, 2. Mass transfer occurring directly from the gas phase to the biofilm, and 3. Enlarged contact area between the gas phase and the biofilm due to a rough biofilm surface.