Ovarian folliculogenesis in the smallnose fanskate sympterygia bonapartii (Müller & Henle, 1841) (Chondrichthyes, Rajidae) / Foliculogénesis ovárica en la raya marmorada, sympterygia bonapartii (Müller & Henle, 1841) (Chondrichthyes, Rajidae)

Chondrichthyes have become an important economic resource in the last decades, with Argentina as one of the countries that exploits more sharks and skates, even at levels that exceed de limits of many species. However, there is a scarce knowledge of the reproductive biology of this group, particularly from species inhabiting the Southern hemisphere. This work shows the most relevant facts during folliculogenesis in Sympterygia bonapartii. Results show that germinal cells are present in immature and maturing females. The most important facts that vary along de follicular development are the number of types and layers of follicular cells, the establishment of thin projections from the follicular cells and the degree of development of the thecae. Follicular cells are, at least, of two different types and both of them emit projections that break through the zona pellucida. The outer theca shows signs of synthetic activity. Atretic follicles of different sizes are present in exemplars of all the reproductive stages. These results are discussed in a physiological and adaptive context.

Los Condrictios se han convertido en un recurso económico importante en las últimas décadas, siendo Argentina uno de los países que más explota tiburones y rayas, incluso a niveles que exceden los límites de varias especies. A pesar de esto, es poco lo que se conoce sobre la biología reproductiva de este grupo, particularmente en especies del Hemisferio Sur. En este trabajo se estudian los estadios más relevantes de la foliculogénesis en Sympterygia bonapartii. Los resultados muestran que las ovogonias están presentes tanto en ejemplares inmaduros como subadultos. Las características más importantes que varían a lo largo del desarrollo folicular son el número de capas y tipos celulares que constituyen el epitelio folicular, el desarrollo de proyecciones de las células de la granulosa y el grado de desarrollo de las tecas. Las células foliculares son, al menos, de dos tipos y ambos emiten proyecciones que atraviesan la zona pelúcida. La teca externa presenta características compatibles con la actividad sintética. Folículos atrésicos de distintos tamaños están presentes en ejemplares de todos los estadios de madurez sexual. Estos resultados se discuten en un marco fisiológico y adaptativo.

Lutzomyia longipalpis (Diptera: Psychodidae: Phlebotominae): a review

Lutzomyia longipalpis is the most important vector of AmericanVisceral Leishmaniasis (AVL) due to Leishmania chagasi in the New World. Despite its importance, AVL, a disease primarily of rural areas, has increased its prevalence and became urbanized in some large cities in Brazil and other countries in Latin America. Although the disease is treatable, other control measures include elimination of infected dogs and the use of insecticides to kill the sand flies. A better understanding of vector biology could also account as one more tool for AVL control. A wide variety of papers about L. longipalpis have been published in the recent past years. This review summarizes our current information of this particular sand fly regarding its importance, biology, morphology, pheromones genetics, saliva, gut physiology and parasite interactions

Response of Achlya racemosa, A. proliferoides and Saprolegnia furcata to Sub-lethal Treatments of Amino Acids

The effect of four sub-lethal concentrations (400, 800, 1,200 and 1,600 microg/ml) of three amino acids such as isoluecine, aspartic acid and phenylalanine on vegetative growth and sexual and asexual reproduction of Achlya racemosa, A. proliferoides and Saprolegnia furcata was investigated. The density of vegetative growth and diameters of vegetative colonies of species of the Oomycetes fungi decreased with rising the concentration of the applied amino acid. Vegetative hyphae of treated fungi almost appeared branched in case of S. furcata, thick in case of A. racemosa and distorted in case of A. proliferoides as compared with control. The different treatments with amino acids depressed both sporangial formation and discharge, which were dependent on the tested species of zoosporic fungi, the amino acid and its dosage. Phenylalanine was the most effective amino acid in inhibiting sporulation and S. furcata was the most sensitive fungal species. Aspartic acid and isoleucine stimulated germination of discharged spores through the formation of germlings. Gemmae formation by the three fungi was reduced at the low concentrations of amino acids and nearly missed at high concentrations. Sex organs (oogonia and antheridia) were affected partly; rudiment oogonia were observed at low concentrations (400 and 800 microg/ml) and disappeared at higher concentrations, whereas antheridial branch formation was stimulated as the fungi were treated with isoleucine and to some extent phenylalanine.

Oogenesis in the swamp eel Synbranchus marmoratus (Bloch, 1795) (Teleostei; Synbranchidae). Ovarian anatomy, stages of oocyte development and micropyle structure

Synbranchus marmoratus (Synbranchidae), commonly known as the swamp eel, is a protogynous diandric teleost fish widely distributed throughout South America. The purpose of this work was to study the ovarian anatomy and to describe oocyte developmental stages in the swamp eel, Synbranchus marmoratus. S. marmoratus has a unique sacular ovary. It is covered by a conspicuous muscular wall, probably involved in an egg-releasing system acting as a peristaltic-like mechanism. The internal ovarian anatomy shows a U-shaped ovarian lamella delimiting a dorsal ovarian lumen. The microscopic study shows evidence of the existence of a germinal epithelium in the inner surface of the lamella, which contains germinal cells, pre-follicular cells and epithelial cells. The complete oogenesis process is divided into four stages: oogonia, primary growth, cortical alveoli and vitellogenesis. Besides, the ovulated oocytes, and atretic structures were described. The structure of the micropyle was studied by scanning electron microscopy (MEB). Near the animal pole the vitelline envelope forms crests that fuse together becoming furrow-like structures with a slightly spiraled direction that converge into the micropyle pit where is located the micropylar canal. Although the sex reversal process of Synbranchids has been subject of many studies, this is the first complete description of the ovarian anatomy and oogenesis.