Identity of a Tilapia Pheromone Released by Dominant Males that Primes Females for Reproduction

Knowledge of the chemical identity and role of urinary pheromones in fish is scarce, yet it is necessary in order to understand the integration of multiple senses in adaptive responses and the evolution of chemical communication [1]. In nature, Mozambique tilapia (Oreochromis mossambicus) males form hierarchies, and females mate preferentially with dominant territorial males, which they visit in aggregations or leks [2]. Dominant males have thicker urinary bladder muscular walls than subordinates or females and store large volumes of urine, which they release at increased frequency in the presence of subordinate males or preovulatory, but not postspawned, females [3–5]. Females exposed to dominant-male urine augment their release of the oocyte maturation-inducing steroid 17α,20β-dihydroxypregn-4-en-3-one (17,20β-P) [6]. Here we isolate and identify a male Mozambique tilapia urinary sex pheromone as two epimeric (20α- and 20β-) pregnanetriol 3-glucuronates. We show that both males and females have high olfactory sensitivity to the two steroids, which cross-adapt upon stimulation. Females exposed to both steroids show a rapid, 10-fold increase in production of 17,20β-P. Thus, the identified urinary steroids prime the female endocrine system to accelerate oocyte maturation and possibly promote spawning synchrony. Tilapia are globally important as a food source but are also invasive species, with devastating impact on local freshwater ecosystems [7, 8]. Identifying the chemical cues that mediate reproduction may lead to the development of tools for population control [9–11].

A multi-component pheromone in the urine of dominant male tilapia (Oreochromis mossambicus) reduces aggression in rivals

Males often use scent to communicate their domi- nance, and to mediate aggressive and breeding behaviors. In teleost fish, however, the chemical composition of male pher- omones is poorly understood. Male Mozambique tilapia, Oreochromis mossambicus, use urine that signals social status and primes females to spawn. The urinary sex pheromone di- rected at females consists of 5β-pregnane-3α,17α,20β-triol 3- glucuronate and its 20α-epimer. The concentration of these is positively correlated with male social rank. This study tested whether dominant male urine reduces aggression in receiver males, and whether the pregnanetriol 3-glucuronates also re- duce male-male aggression. Males were allowed to fight their mirror image when exposed to either: i) water control or a chemical stimulus; ii) dominant male urine (DMU); iii) C18- solid phase (C18-SPE) DMU eluate; iv) C18-SPE DMU eluate plus filtrate; v) the two pregnanetriol 3-glucuronates (P3Gs); or vi) P3Gs plus DMU filtrate. Control males mounted an increas- ingly aggressive fight against their image over time. However, DMU significantly reduced this aggressive response. The two urinary P3Gs did not replicate the effect of whole DMU. Neither did the C18-SPE DMU eluate, containing the P3Gs, alone, nor the C18-SPE DMU filtrate to which the two P3Gs were added. Only exposure to reconstituted DMU (C18-SPE eluate plus filtrate) restored the aggression-reducing effect of whole DMU. Olfactory activity was present in the eluate and the polar filtrate in electro-olfactogram studies. We conclude that P3Gs alone have no reducing effect on aggression and that the urinary signal driving off male competition is likely to be a multi-component pheromone, with components present in both the polar and non-polar urine fractions.

O controlo do circuito, da tramitação, da recuperação dos documentos e a legislação nos arquivos municipais de Moçambique

Este estudo tem como objectivo conciliar aspectos da Arquivística à Boa Administração através da gestão dos documentos com efoque no controlo do circuito, da tramitação, da recuperação dos documentos e a legislação nos arquivos municipais em Moçambique no período 1933-2007. O estudo realizado em três universos: municípios de Maputo, da Beira e de Quelimane, em que se confirma que os instrumentos de controlo utilizados na circulação e recuperação dos documentos contribuem para uma boa governação, garantindo a transparência dos actos administrativos e a salvaguarda dos direitos dos cidadãos. Mostra-se que nunca se deve prescindir quer das actividades que delineiam os macro e micro processos nas instituições quer da definição prévia dos percursos documentais, da regulamentação dos procedimentos, da utilização de técnicas que permitam a recuperação dos documentos e da informação: Mostra-se a importância da formação e do conhecimento dos procedimentos pelos funcionários dos escalões autorizados a realizar, pareceres e despachos, da determinação das formas do controlo documental e da garantia no cumprimento dos prazos estabelecidos para cada percurso e, finalmente, a necessária observância prática da legislação criada para esse efeito. ABSTRACT; This case study has as a main objective the reconciliation of the filing aspects with a good Administration though the management of documents and its network, specially in the restoring of files and its legislation into the Municipal Archives of Mozambique during the period of 1933-2007. The study was based on three cities where municipal councils were created, namely: Maputo, Beira and Quelimane. Record's contrail tools used either for registering record transactions or for the access of information contained in them, ensure good governance, transparency and protection of citizen rights. We show the necessity of the activities which lead to macro and micro processes within the organization. This requires that records procedures on transactions must be established and so the guidelines for records' contrail, registration and tools for the information retrieval. We indicate procedures to be followed by authorized civil servants, the importance of their practical training and we define types of records' contrail to ensure their preservation and use in order to accomplish the national legislation.