1,720,982 research outputs found
Fine structure of the eggshell of Ommatissus binotatus Fieber (Homoptera, Auchenorrhyncha, Tropiduchidae)
No full textThe external morphology and fine structure of the eggshell of Ommatissus binotatus Fieber (Homoptera: Tropiduchidae) was investigated by light, scanning and transmission electron microscopy. The egg surface has 2 main regions: a specialized area and an unspecialized egg capsule. The specialized area is characterized by a large respiratory plate containing the operculum and a short respiratory horn. The latter consists of an external hollow tube and an internal cone-shaped projection hosting a micropylar canal. The eggshell has 4 layers: the vitelline envelope, a wax layer, the chorion and an outer mucous layer. The chorion has inner, intermediate and outer parts. The functions of the different parts of the eggshell are discussed. Characters useful to define the eggs and the oviposition habit in the family Tropiduchidae were provided. The size and morphology of the egg, plate, respiratory horn and operculum are suggested as useful characters for ootaxonomic analysis. (C) 1997 Elsevier Science Ltd
FINE-STRUCTURE OF THE CHORION AND MICROPYLE OF THE SEA BASS EGG DICENTRARCHUS-LABRAX (TELEOSTEA, PERCICHTHYDAE)
No full textThe fine structure of the chorion and micropyle of mature unfertilized eggs of the sea bass Dicentrarchus labrax was examined by scanning and transmission electron microscopy. The chorion consists of three layers: a thin electrondense outer layer, a paracrystalline middle layer and a thick inner layer consisting of 12 electrondense filamentous lamellae alternating with interlamellar material of lower electrondensity. The two more external layers are crossed by pore canals opening on the egg surface. The funnel-type micropyle is located at the animal pole of the egg. The walls of the micropylar canal have circular, rib-like thickenings reflecting the stratified inner layer of the chorion. The results are discussed and compared with those in other Teleostea
The terminal disk of Pachyteles larvae (Coleoptera: Carabidae: Paussinae): morphology and ultrastructure
No full textCHARACTERIZATION OF THE MAIN EGG ENVELOPE PROTEINS OF THE SEA BASS DICENTRARCHUS-LABRAX L (TELEOSTEA, SERRANIDAE)
No full textFish eggs are surrounded by a resistant acellular coat commonly called the chorion or zona radiata. This study characterizes the eggshell proteinaceous content of unfertilized eggs of the sea bass Dicentrarchus labrax, with a view to the preparation of immunogens. Solubilization of the purified eggshells was achieved in 8 M urea followed by one- and two-dimensional gel electrophoresis. Glycoproteins were detected using concanavalin-A in one and two-dimensional gels, and the principal glycoproteins had a molecular weight of 47 kDa and 170 kDa. Partial purification of a few polypeptides in the 45 kDa to 55 kDa range was achieved by gel filtration chromatography. Although whole eggshells were relatively insoluble even in 8 M urea, partial purification of these polypeptides enable them to dissolve completely in solutions at low ionic strength. (C) 1994 Wiley-Liss, Inc
Biology and functional morphology of Pachyteles larvae (Coleoptera: Carabidae: Paussinae)
No full textThe terminal disk of Pachyteles larvae (Coleoptera: Carabidae: Paussinae): a morphological study
No full textEffects of cryopreservation on the fish spermatozoa ultrastructure
No full textAnomalies of spermatozoa of Sparus aurata and Diplodus puntazzo caused by different cryogenic protocols were analysed. Milt was diluted with cryosolutions containg different diluent (0.1 M Na citrate and 0.17 M NaCl) and cryoprotective (DMSO and glycerol). Ultrastructure was studied by TEM at different phases of the cryopreservation procedure, that induced sperm anomalies varying in quantity with the different protocols. In particular, cryosolutions with 0.1 N Na citrate or 0.17 M NaCl were equally effective when used according to the same protocol, while the relative concentration of DMSO likely determined the different incidence of anomalies detected
Isolation and characterization of lignin from beech wood and chestnut sawdust for the preparation of lignin nanoparticles (LNPs) from wood industry side-streams
No full textLignin was isolated through mild acidolysis from local wood sources such as beech wood and chestnut wood sawdust, a high-volume side product of wood industries. The lignin fractions were characterized by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), Fourier-transform infrared (FTIR), ultraviolet-visible (UV-Vis) and two-dimensional heteronuclear single-quantum correlation nuclear magnetic resonance (2D HSQC NMR) spectroscopies and size exclusion chromatography (SEC). The Klason lignin (KL) content and polysaccharide composition were determined using traditional methods. Lignin nanoparticles (LNPs) were prepared via a non-solvent method involving dialysis and characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and FTIR and UV-VIS spectroscopies. Semi-porous as well as hollow nanoparticles endowed with a spherical shape were observed. The large majority of the LNPs exhibited an average particle diameter of 90-120 nm. Dynamic light scattering (DLS) analysis showed that both distribution and frequency of dimensional classes of LNPs are clearly affected by the lignin solvent system, i.e. solvent selection governs the size distribution of LNPs
Is cryopreservation a homogeneous process? Ultrastructure and motility of untreated, prefreezing, and postthawed spermatozoa of Diplodus puntazzo (Cetti)
No full textA significant elevation of serum immunoglobulin (Ig) concentration occurred in female gilthead sea bream Sparus aurata during spawning. Furthermore, a progressive rise of serum Ig level was observed throughout the process of sexual inversion (from functional male to functional female), suggesting that the synthesis of Ig could be regulated by sex-related factors (probably
sexual hormones) involved in the process of oogenesis. The immunoglobulins of eggs were purified by affinity chromatography on protein A-sepharose. SDS-PAGE and Western blot analysis showed reactivity of the antiserum Pab1 with the Ig heavy and light chains, and some degradation products. This purification process yielded detectable amounts of Ig. The
sex-related increase of serum Ig during the reproductive period, and the detection of Ig in eggs suggest a transfer of Ig from the blood of the adult female
Viral particles of the endogenous retrovirus ZAM from Drosophila melanogaster use a pre-existing endosome/exosome pathway for transfer to the oocyte
No full text- …
