Presence of the telescope fish Mendosoma lineatum in Patagonian waters, a new species in the ichthyological fauna from the south-west Atlantic Ocean.

The presence of the telescope fish Mendosoma lineatum in Patagonian waters of Argentina is reported. Mendosoma lineatum is the second species of the Latridae recorded in the south-west Atlantic Ocean and its presence in Patagonia is an addition to both the ichthyological fauna of the Argentinean Sea and the south-west Atlantic Ocean.

Fluorescence and Textural Characterization of Ortho-Amine Tetraphenylporphyrin Covalently Bonded to Organo-Modified Silica Xerogels.

Most of the studies performed with porphyrins involve these species functionalized with peripheral substituents lying on the same macrocyclic molecular plane. The main objective of this work deals with the successful preservation and optimization of the fluorescence of a uncommonly used porphyrin species, i.e. tetrakis-(ortho-amino-phenyl)-porphyrin; a molecule with substituents localized not only at one but at both sides of its molecular plane. In cases like this, it must be stressed that fluorescence can only be partially preserved; nevertheless, intense fluorescence can still be reached by following a twofold functionalization strategy involving: (i) the bonding of substituted macrocycles to the pore walls of (ii) organo-modified silica monoliths synthesized by the sol-gel method. The analysis of both absorption and emission UV spectra evidenced a radiation energy transfer taking place between the porphyrin and the host silica matrix. Our results showed that the adequate displaying of the optical properties of macrocyclic species trapped in SiO2 xerogels depend on the polarity existing inside the pores, a property which can be tuned up through the adequate selection of organic groups used to modify the surface of the pore cavities. Additionally, the pore widths attained in the final xerogels can vary depending on the identity of the organic groups attached to the network. All these facts finally demonstrated that, even if using inefficient surface functionalization species, such as ortho-substituted tetraphenylporphyrins, it is still possible to modulate the pore shape, pore size, and physicochemical environment created around the trapped macrocycles. The most important aspect related to this research deals with the fact that the developed methodology offers a real possibility of controlling both the textural and morphological characteristics of a new kind of hybrid porous materials and to optimize the physicochemical properties of diverse active molecules trapped inside the pores of these materials.

Trophic ecology of yellownose skate Zearaja chilensis, a top predator in the south-western Atlantic Ocean.

The diet and trophic level (TL ) of the yellownose skate Zearaja chilensis in the south-western Atlantic Ocean (35°-54° S), and how these varied in relation to body size, sex, maturity stage, depth and region were determined by analysis of stomach contents. From 776 specimens analysed, 671 (86·5%) ranging from 180 to 1190 mm total length (LT ) had prey in their stomachs. The diet was dominated by fishes, mainly the notothenioid Patagonotothen ramsayi and the Argentine hake Merluccius hubbsi. The consumption of fishes and crabs increased with increasing predator size, and these preys were more important in the north than in the south. Isopods and other crustaceans were consumed more in the south and their consumption decreased as the size of Z. chilensis increased. The TL of Z. chilensis increased with LT from 4·29 to 4·59 (mean 4·53), confirming their ecological role as a top predator. The small and large size classes exhibited a low diet overlap and the highest spatial segregation, whereas medium and large specimens had higher co-occurrence and dietary overlap indices. A clear distinction in tooth shape was noted between sexes in adult specimens, with males having longer cusps. This sexual heterodonty may be related to reproductive behaviour, increasing the grasping ability of males during courtship, because there were no differences in diet between the sexes.

First report of the black gemfish Nesiarchus nasutus (Perciformes: Gempylidae) in Argentinean waters.

The gempylid Nesiarchus nasutus is reported for the first time from Argentinean waters, the southernmost occurrence of the species in the Southwestern Atlantic. This suggests that the fluctuating environmental characteristics of the area would be proper for the presence of tropical and subtropical species.

Effects of intrinsic and extrinsic factors on the diet of Bathyraja macloviana, a benthophagous skate.

The effects of intrinsic (sex, maturity stage and body size) and extrinsic (depth and region) factors on the diet of Bathyraja macloviana, in the south-west Atlantic Ocean, were evaluated using a multiple-hypothesis modelling approach. Bathyraja macloviana fed mainly on polychaetes followed by amphipods, isopods and decapods. Effects of intrinsic and extrinsic factors on diet composition of this species were found. The consumption of polychaetes had a humped relationship with total length (L(T), and isopods and decapods increased with increasing L(T). Immature individuals preyed on amphipods more heavily than mature individuals. Furthermore, region and depth had an important effect on the consumption of isopods, decapods and amphipods. Such ontogenetic changes and spatial patterns may provide insights into understanding the regulatory mechanisms of marine communities.

Chondrichthyan egg cases from the south-west Atlantic Ocean.

Egg cases of 21 oviparous chondrichthyan species from the south-west Atlantic Ocean are described and compared. The catshark Schroederichthys bivius has a cigar-shaped egg case with curled tendrils only at the posterior end. Egg cases of the elephant fish Callorhinchus callorynchus are spindle-shaped with anterior and posterior tubular extensions and lateral flanges. The skate Amblyraja doellojuradoi presents medium-sized egg cases (71 mm in length) with a lateral keel extending to the first portion of the horns. The endemic skate species of the genus Atlantoraja have medium to large egg cases (69-104 mm in length) and present relatively large posterior horns. Egg cases of the genus Bathyraja have a medium size, 75-98 mm in length, and are characterized by a very similar morphology, a relatively smooth to rough surface case and posterior horns strongly curved inwards. Egg cases of the genera Dipturus and Zearaja are very large, 115-230 mm in length, and have a well-developed posterior apron. Despite the problematical identification of skates at species level, the egg capsules of the endemic genus Psammobatis are easily diagnosed; the capsules are small (25-53 mm in length), those of Psammobatis rutrum being the smallest known to date in the world. Egg cases of Rioraja agassizi have a medium size, 61-68 mm in length, relatively straight sides, a smooth surface and silky attachment fibres placed in the lateral keel next to each horn. Those of the genus Sympterygia are small to medium sized, 51-86 mm in length, and display the thickest lateral keel and the longest posterior horns among the skates of the world. Egg cases can be a useful tool for identifying species and egg-laying areas; therefore, a provisional key for the south-west Atlantic Ocean chondrichthyan capsules is presented.

Morphological, morphometric, meristic and osteological evidence for two species of hake (Actinopterygii: Gadiformes: Merluccius) in Argentinean waters.

Morphologically, both classic and landmark-based morphometry and meristic analyses of 241 specimens of Merluccius, along with the re-examination of six paratype specimens of Merluccius hubbsi, the holotype and three paratypes of Merluccius patagonicus and the syntype of Merluccius australis revealed the presence of only two species of Merluccius in Argentinean waters. Internal structures (hyomandibula, urohyal and sagitta otolith) of M. hubbsi were compared to those reported for M. patagonicus and were shown to have identical morphology. Type specimens of M. patagonicus showed a complete overlap in morphometric and meristic characters with M. hubbsi, whereas M. australis had a greater number of second dorsal and anal-fin rays, and more lateral-line scales. In addition, M. australis had a smaller eye and longer snout than M. hubbsi and M. patagonicus. The results indicate that there is no evidence for a third hake species in Argentinean waters. Merluccius patagonicus is a synonym of M. hubbsi.

First record of a dicephalic specimen of tope Galeorhinus galeus (Elasmobranchii: Triakidae).

The first case of dicephalia in tope Galeorhinus galeus analysed in developing foetuses removed from a pregnant female caught off the Mar del Plata coastal waters, Argentine Sea, is reported here.

The mucosa of the digestive tract in Micropogonias furnieri: a light and electron microscope approach.

The histomorphological aspects as well as the histochemical content and distribution of glycoproteins (GPs) in the mucosa of the digestive tract of the white croaker Micropogonias furnieri were studied. The buccopharyngeal cavity and the esophagous showed a squamous stratified epithelium with mucous cells. The stomach presented three portions: cardias, fundus and pylorus. Tubular glands formed by a single type of gland cell were located along the cardias and fundus. Histochemical tests showed that the buccopharyngeal cavity and the esophagous presented the largest amount of the different types of mucosubstances. Both organs showed abundant secretory mucous cells that synthesize large quantities of neutral, sulphated and sialylated GPs. The surface epithelium in the cardias and fundus synthesized and secreted scarce sialylated and neutral GPs whereas the secretions of the apical surface were abundant. The pylorus secreted large amounts of neutral as well as sulphated and sialylated GPs. Gland cells secreted neutral GPs. The ultrastructural features of the gut cells were quite similar to those of other teleosts. The buccopharyngeal cavity and the esophagous surface epithelial cells, identified by their superficial localization, were characterized by cytoplasmic vesicles of different size. Abundant goblet cells with secretory mucous granules were also present. Gastric glands in the stomach contained just one form of cell with a fine structure similar to cells that secrete pepsinogen.

Medical ethics education in the eighties: a study of five medical schools.

Five Southern California medical schools were examined using a case study approach. In-depth interviews were conducted with faculty members and administrators from Loma Linda University, the University of Southern California, and the University of California at Irvine, Los Angeles, and San Diego, Schools of Medicine. Using an interview instrument based on a needs assessment model, the interviewer examined interviewees' perspectives on the current curriculum and their opinions on the 'ideal' medical ethics curriculum. Key issues of concern for each medical school's medical ethics curricula were discussed.