The opecoelidae (Digenea) of sparid fishes of the western Mediterranean. II. Pycnadenoides yamaguti, 1938 and Pseudopycnadena Saad-Fares & Maillard, 1986

The genera Pycnadenoides Yamaguti, 1938 and Pseudopycnadena Saad-Fares & Maillard, 1986 are redefined and their validity discussed. Two forms, currently considered to be Pycnadenoides senegalensis Fischthal & Thomas, 1972, one from Lithognathus mormyrus and Diplodus vulgaris off Corsica (Scandola) and one from Sparus aurata off Provence and Languedoc, are described separately, as some preliminary biochemical studies suggest that they might be distinct. This species is commented upon in relation to Distomum mormyri Stossich, 1885, D. umbrinae Stossich, 1885, Pycnadenoides pagrosomi Yamaguti, 1938 and P. ghanensis Fischthal & Thomas, 1968. Pseudopycnadena fischthali Saad-Fares & Maillard, 1986 is redescribed from Diplodus vulgaris, D. annularis and D. sargus off Corsica (Scandola).

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Résumé Les auteurs redéfinissent et discutent la validité des genres Pycnadenoides Yamaguti, 1938 et Pseudopycnadena Saad-Fares & Maillard, 1986. Deux formes considérées actuellement comme Pycnadenoides senegalensis Fischthal & Thomas, 1972, l'une parasite de Lithognathus mormyrus et de Diplodus vulgaris des côtes de Corse (Scandola), l'autre parasite de Sparus aurata des côtes de Provence et du Languedoc, sont décrites séparément. Des études biochimiques préliminaires suggèrent qu'il pourrait s'agir de deux espèces différentes. Cette espèce est discutée par rapport à Distomum mormyri Stossich, 1885, D. umbrinae Stossich, 1885, Pycnadenoides pagrosomi Yamaguti, 1938 et P. ghanensis Fischthal & Thomas, 1968. Pseudopycnadena fischthali Saad-Fares & Maillard, 1986 est redécrit à partir d'exemplaires provenant de Diplodus vulgaris, D. annularis et D. sargus des côtes de Corse (Scandola).

     

1H NMR conformational study of sulfated and non-sulfated cholecystokinin fragment CCK27–33: Influence of the sulfate group on the peptide folding

¹H NMR study of cholecystokinin fragment (CCK_27–33) in (C²H₃)₂SO and in ²H₂O at different pH shows that sulfated (CCK₇) and non sulfated (NS-CCK₇) peptides are under preferentially folded conformations characterized by a β-turn including the sequence Gly-Trp-Met-Asp with a H-bond between the CO of Gly and the NH of Asp. This structure is probably stabilized by an ionic interaction between Tyr and Asp. Moreover, the N-terminal part of CCK₇ forms a C₇ structure with a weak H-bond between the CO of Gly and the NH of Trp. In this model all CCK₇ hydrophobic side chains are in close vicinity, far from the hydrophilic sulfate group. Full interaction with brain CCK₈ receptors could require both the sulfate group and the maintening of conformational constraints.     

Effect of biocides on Pseudomonas aeruginosa phage F116

Pseudomonas aeruginosa phage F116 is of interest in understanding the virucidal mechanisms of disinfectant action. Phage F116 has been used to test several disinfectants. The bacteriophage was relatively resistant to several biocides commonly used in disinfection processes. Only 0.05% cetylpyridinium chloride, 0.1% peracetic acid and 2% phenol were highly active against the phage.     

Development and fine structure of the bony scutes in Corydoras arcuatus (Siluriformes,callichthyidae)

The development and the structure of the bony scutes have been studied in a growth series of the armored catfish Corydoras arcuatus using light and electron microscopy. Fibroblast-like cell condensations appear in the dermis, in the posterior region of the caudal peduncle, and these will constitute the scute papillae. Collagen bundles of the preexisting dermis colonized by the papilla cells are remodeled and incorporated in the papilla to form, in addition to newly synthesized woven-fibered bony material, the initium of the scute. This process of formation differs from that described for the dermal papilla of an elasmoid scale. During growth, the osteoblasts surrounding the scute constitute the scute sac in which the scute grows. Parallel-fibered bone is deposited on both sides of the initium, and osteoblasts are incorporated within the scute matrix. The remodeling and incorporation of collagen bundles of the preexisting dermis is maintained during growth only in the deep, anterior region of the scute. The posterior region and the upper surface of the scute are close to the epidermal-dermal boundary. When growth slows down in the upper part of the scute, a characteristic, well-mineralized tissue, composed of thin vertical fibrils and granules and devoid of typical striated collagen fibrils, is deposited on the scute surface. A new term, hyaloine, is introduced for this nonosseous, highly mineralized layer constituting the upper part of the scute. Hyaloine shows thin electron-dense lines, which probably correspond to periodic growth arrests. The structure and localization of the hyaloine are compared to other well-mineralized, similar tissues found on the surface of the dermal skeleton in lower vertebrates. © 1993 Wiley-Liss, Inc.     

Use of anion exchange perfusion chromatography for protease recovery at process scale

Summary A protease fromAspergillus niger LCF 8 was purified in anion exchange mode using BioCAD Workstations and the process scaled up. The use of POROS 50 HQ media brings the benefits of Perfusion chromatography i.e. high resolution and high dynamic capacity with very short cycle times. Results obtained at pilot scale enable to purify at process scale 151g of protease/m³ crude broth in 1h. The small column size needed (2.25 l media/m³ crude broth) and the high processing speed of POROS^* 50 HQ compared with conventional media lead to greatly improved cost effectiveness and higher product recovery.