Nuestro último artículo, aceptado en Aquaculture

Hormonal manipulations for the enhancement of sperm production in cultured fish and evaluation of sperm quality

Constantinos C. Mylonas, Neil J. Duncan, Juan F. Asturiano

Abstract

This article reviews the use of hormonal treatments to enhance sperm production in aquaculture fish and the methods available for evaluating sperm quality. The different types of testis development are examined and a brief review is presented of the endocrine regulation of spermatogenesis in fishes, including the increasing evidence of the existence of spermatozoa subpopulations. Hormonal manipulations are employed to induce spermatogenesis in species such as the freshwater eels, to synchronize maximal sperm volume to ovulation for in vitro fertilization and to enhance sperm production in species with poor spermiation. The hormones that are employed include gonadotropins (GtH) of piscine or mammalian origin, and gonadotropin-releasing hormone agonists (GnRHa) administered by injections or controlled-release delivery systems, with or without dopaminergic inhibitors.

Pheromones in the culture water and hormones added to the sperm in vitro have also been employed to enhance spermiation and sperm quality, respectively, in some fishes. Hormonal therapies usually do not affect sperm quality parameters, except in cases where fish fail to spermiate naturally or produce very small volumes of high-density sperm. Different parameters have been used to evaluate fish sperm quality, including sperm volume and density, spermatozoa motility and morphometry, and seminal plasma composition. The development of Computer-Assisted Sperm Analysis (CASA) systems made possible the estimation of a higher number of sperm motion parameters using an objective, sensitive and accurate technique. The development of Assisted Sperm Morphology Analysis (ASMA) software has introduced a new approach for sperm evaluation studies, demonstrating changes in the spermatozoa related to reproductive season, hormonal treatments or the cryopreservation processes, and how these may be related to changes in sperm motility and fertilization capacity. The article concludes with a few practical protocols for the enhancement of sperm production in aquaculture species.

Available here: http://authors.elsevier.com/sd/article/S004484861630206X

Nuestro último artículo, aceptado en Reproduction in Domestic Animals

First production of larvae using cryopreserved sperm: Effects of preservation temperature and cryopreservation on European eel sperm fertilization capacity

Juan F. Asturiano, Sune R. Sørensen, Luz Pérez, Peter Lauesen, Jonna Tomkiewicz

Abstract

Sperm cryopreservation is a useful tool in captive fish reproduction management, i.e. in order to synchronize gamete production, especially in the case of species as the European eel, where the time of female spawning readiness is unpredictable. Several protocols to cryopreserve sperm of this species have been described, but until recently fertilization trials were not feasible. The present study evaluated the effect of cold storage of diluted sperm prior to fertilizations and tested if a previously defined protocol for European eel sperm cryopreservation can be successfully applied in fertilization trials to produce viable offspring. In our experiment, the sperm motility was evaluated after the extraction and the best samples were selected and pooled. Until stripping of eggs and fertilization, diluted sperm samples were maintained at either 4 or 20 ºC, or cryopreserved, following existing protocols. Fertilization of two egg batches was attempted. Diluted sperm caused a similar percentage of fertilized eggs and a similar number of embryos and larvae, independently of storage temperature (4 or 20 ºC). The cryopreserved sperm resulted in a lower percentage of fertilized eggs, but embryos developed and a few larvae (“cryolarvae”) were obtained 55 h after fertilization in one of the two egg batches. This result evidences that the tested cryopreservation protocol is applicable for eel reproduction management, although improvements will be required to enhance fertilization success.

Oferta de contrato predoctoral en Berlín dentro del Proyecto IMPRESS

The Leibniz-Institute of Freshwater Ecology and Inland Fisheries (www.igb-berlin.de) is the largest research institute for freshwater research in Germany. It is member of the Leibniz Association and the Forschungsverbund Berlin e.V. IGB has close links to all three universities in the German capital and currently hosts about 50 doctoral students from approximately 15 different nations. Since 1996, the IGB has been committed to research on sturgeon remediation and restoration in the tributaries of the Baltics and the North Sea, including several national and international projects and programmes. Within the EU Marie Sklodowska-Curie Initial Training Network IMPRESS (Improved production strategies for endangered freshwater species, http://www.impress-itn.eu), the Research Group Applied Fish Physiology and Aquaculture led by Dr. Sven Würtz is looking for a hard-working, enthusiastic

Early-stage researcher

Trait-related optimization of hatchery technology to improve fitness and stocking efficiency in sturgeon

This is position 7 within IMPRESS, available from now on until 31.08.2018

IMPRESS aims at developing new technologies for improved production, management and conservation of threatened iconic diadromous fish species. IMPRESS is set up as intersectoral network of 15 ESR hosted by 9 different hosts covering molecular biology, physiology, and aquaculture technology, as well as human dimensions of biodiversity conservation. The project will focus on assessing and improving fitness of hatchery-reared early life stages in the wild. Challenge tests will be carried out to characterize ecophysiological adaptations to fluctuating environmental challenges and improve aquaculture technologies in conservation aquaculture. During the project the ESR will spend up to 6 months at the Norwegian University of Life Sciences (host Ian Meyer) assessing impaired cognitive ability and behaviour in hatchery of sturgeon. Finally the student will carry out transcriptome analysis of selected samples at the ZF Screens (Ron Dirks) in Leiden, Netherlands. This mobility will enhance multidisciplinary training of the student, and give him/her important experience of both academic and non-academic sectors (training school programme).

More details on the topic, the ITN network, the location, the team of supervisors and their groups, the expected mobility, salary and general eligibility criteria can be found in a long version of this job advertisement posted at www.igb-berlin.de/job-offers.html.

Applicants should have a 2.1 degree or equivalent in a relevant life science (biology, fisheries sciences, aquaculture and environmental sciences). Excellent communication skills in English are required. Experience with molecular techniques (e.g. qPCR, transcriptome analysis) and analytical chemistry (mass spectrometry, chromatography) is highly preferred. Candidates with a background in aquaculture (particularly larval rearing) will be deemed highly competitive.

According to EU regulations candidate students must not have resided for more than 12 months during the previous 3 years in the prospective host country, Germany.

Salary is paid according to the regulations of the programme. In keeping with the IGB's policy regarding gender equity, female applicants are particularly encouraged. Among candidates of equal aptitude and qualifications, a person with disabilities will be given preference.

Review of applications meeting the required standards will start immediately and continue until a candidate is appointed. Please send your application and further inquiries to Dr. Sven Würtz (wuertz@igb-berlin.de).

La SIBIC estrena nueva web

La Sociedad Ibérica de Ictiología cumplió 5 años el pasado diciembre de 2015 y ha renovado su web (www.sibic.org). La nueva web es mucho más moderna y dinámica. Se ha construido para que sea totalmente accesible desde ordenadores, tablets y smartphones. También se han integrado la web de la revista Fishes in Mediterranean Environments (www.fishmedjournal.org) y los congresos celebrados hasta el momento por la SIBIC. Además se ha añadido la versión en inglés para facilitar y fomentar la visibilidad y las relaciones internacionales.
Os invitamos a navegar por la nueva sibic.org

Nuestro último artículo, aceptado en Comparative Biochemistry and Physiology - Part A: Molecular & Integrative Physiology

Sodium affects the sperm motility in the European eel

M. Carmen Vílchez, Marina Morini, David S. Peñaranda, Víctor Gallego, Juan F. Asturiano, Luz Pérez

Abstract

The role of seminal plasma sodium and activation media sodium on sperm motility was examined by selectively removing the element from these two media, in European eel sperm. Sperm size (sperm head area) was also measured using an ASMA (Automated Sperm Morphometry Analyses) system, in the different conditions. Intracellular sodium [Na+]i was quantitatively analyzed by first time in the spermatozoa from a marine fish species. Measurement of [Na+]i was done before and after motility activation, by Flow Cytometry, using CoroNa Green AM as a dye. Sperm motility activation induced an increase in [Na+]i, from 96.72 mM in quiescent stage to 152.21 mM post-activation in seawater. A significant decrease in sperm head area was observed post-activation in seawater. There was a notable reduction in sperm motility when sodium was removed from the seminal plasma, but not when it was removed from the activation media. Sodium removal was also linked to a significant reduction in sperm head area in comparison to the controls. Our results indicate that the presence of the ion Na+ in the seminal plasma (or in the extender medium) is necessary for the preservation of sperm motility in European eel, probably because it plays a role in maintaining an appropriate sperm cell volume in the quiescent stage of the spermatozoa.

Nueva Training School de AQUAGAMETE

The AQUAGAMETE COST ACTION is pleased to announce the 6th AQUAGAMETE training school which will be focused on the Molecular basis of gamete quality and reproduction, with a strong orientation towards GENOMIC TOOLS. 

The course will be organized by the Fish Physiology and Genomics Department of INRA, Rennes (France) (coordination by Julien Bobe and Catherine Labbé), and will be held in Rennes from June 6th to 10th 2016.

The course will include conferences on:

- Sperm genetic damage and repair in Fish (Paz Herraez, Spain)

- Overview of sequencing technologies and strategies available to analyze fish reproduction (Yann Guiguen, France)

- Epigenetics and inheritance (Francesc Piferrer, Spain)

- Transgenesis approaches in fish reproduction (speaker to be determined)

- CrispR/Cas9 technology for research on fish reproduction (Amaury Herpin, France)

- microRNA and female fecundity (Amine Bouchareb, France)

The practical sessions will be coordinated by the Fish Physiology and Genomics staff.  Include experiment on: 

- RNA extraction (2h30)

- Microarray analysis of fish samples in reproduction research (10h)

- Sequence searching including tools presentation, primer design, phylogeny/syntheny search (5 h)

The number of participant is restricted to 16 persons. Priority will be given to early stage researchers (MSc students, PhDstudents, young post-docs) and to participants with no experience in genomics and with a professional project related to gamete quality or fish reproduction, including representative from industry.

Financial support from the AQUAGAMETE COST action for travelling, accommodation and meals will be available for students. The access to lectures, laboratory facilities and support material is supported for all participants by the AQUAGAMETE COST action and by the host Fish Physiology and Genomics department.

The application deadline is May 2nd, 2016. Complete applications must be sent via e-mail to aquagamete@gmail.com. Eligible candidates will be announced by May 6th. For more detailed information please contact Pepa Bayarri (aquagamete@gmail.com).

Applications should include the following documents:

• Application form (attached);

• Short Curriculum Vitae in the area;

• Motivation letter for participating in the training school, which should indicate the academic/professional status of the applicant;

• Letter of recommendation from the applicant’s supervisor or employer;

• Financial Support justification (only for students).

More information available soon at: http://aquagamete.webs.upv.es