Carla Pollastro – Neuroendocrine control of male reproductive behavior in the blenny Salaria pavo

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Scienze Naturali e Ambientali - Tesi di Laurea

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The neuroendocrine influence upon male sexual behavior in a species with different male reproductive morphotypes.

In Salaria pavo (Perciformes, Blenniidae) we recognize 3 main morphotypes: the male”bourgeois” (Fig.1A), sexually mature, characterized by a complete development of the sexual characters(in particular an evident head crest and the ventral anal gland), the female (Fig.1B)with an evident different morphotype from the bourgeois male, and the “sneaker “male (Fig.1C), sexually mature, smaller than the bourgeois male and phenotypically more similar to the female than to the bourgeois male.

Salaria pavo main morphotypesWe can distinguish at least a third male morphotype: the”transitional”male, an intermediate stage of the bourgeois male, sexually immature, phenotypically similar to the”bourgeois”male.

The presence of different male morphotypes is the main reason to study this species. In particular, I focused my interests in the study on the neuroendocrine control of male sexual behavior that should be more complex than in species characterized by only one male morphotype.

The examined population (in Algarve, Atlantic Ocean) was chosen for its specific ethological features compared to the other populations (for example the Adriatic sea population): At Culatra island (Algarve, Portugal) the"bourgeois"male chooses for a nest and waits for the courtship by the female. However, the "sneaker “male miming the female phenotype and behavior can deceive the male and fertilize eggs laid by a female in the nest. Samples were, therefore, collected between May and July 2009 on Culatra island according to the tide’s cycles since the Salaria pavo is an euryhaline intertidal blenny.

The collected individuals were subjected to hormonal implants, placed in isolation in aquariums for 8 days and then euthanized for the subsequent tissues’ removal and analyses. The experimental groups were four: Controls (Castor Oil), Androgens (Testosterone, 11Ketotestosterone) and Aromatase Inhibitor (Flutamide). The specific objective was to evaluate the effects of hormonal unbalance on hormonal levels, development of secondary sexual characteristics and expression of androgen receptors alpha and beta.

The molecular analysis were conducted in the Dr.Oliveira’s laboratory of ISPA (Lisbon) and they showed that

  • 11KT levels increased in response to 11KT- or Flutamide-treatments (in the latter, the increase of 11KT levels is due to a response to the aromatase inhibition inducted by Flutamide).
  • The hormonal treatments had no effect on the rate of growth in all males, but androgens strongly influenced the development of the secondary sexual characters. In fact they stimulated the growth of the head crest (especially in the sneaker males which were missing it at the beginning of the experience), reduced the size of the anal gland in the bourgeois males and promoted its development in sneaker males.
  • Androgen receptors analyses showed that sneaker males can be more responsive to androgens than bourgeois males and this effect is due to changes in levels of circulating androgens.

Contrary to previous experiments (Oliveira et al. 2001; Gonçalves et al.2007), my experience had a comparative approach considering the differences between the three types of males and included at the same time a multifactorial evaluation of morphological characteristics, hormone levels , and expression of androgen receptors.

Future experiments should consider brain’s macro-areas for the molecular analysis and a longitudinal study during early development for putative changes of hormonal levels.

Carla Pollastro

Tesi di Laurea Specialistica

Autore: Carla Pollastro
Relatore: Giancarlo Panzica
Università: Università degli Studi di Torino
Facoltà: Facoltà di Scienze Matematiche, Fisiche e Naturali
Corso: Laurea Spec. in Evoluzione del Comportamento Animale e dell’Uomo
Data di Discussione: 11/07/2011
Voto: 109
Disciplina: Neuroendocrinologia del comportamento
Tipo di Tesi: Sperimentale
Lingua: Inglese
Grande Area: Area Scientifica
Dignità di Stampa: Si
In Collaborazione con: Ispa(Istituto Superior de Psicologia Aplicada), Lisbona

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