Por Mauro Rebelo

The Quest for Embryos

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Figure 1 – Buenos Aires harbor seen from the Tigre river estuary

From the estuary of the Tigre river, we can see the city and the harbor of Buenos Aires, where the Golden Mussel infestation started in 1991. The invasion has taken all its tributaries and is a major concern at the nuclear power plant of Atucha, just 100 km from the Argentine capital.

We were there to sample mussels for a reproduction experiment. Even though Golden Mussel is an invasive species with a high reproductive capacity, all groups that have tried to reproduce them in the lab in Brazil have failed, so we went to the learn the secrets of spawning with Dr. Daniel Cataldo and his team at the Univrsity of Buenos Aires.

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Figure 2 – Dr. Cataldo observes mussels in the stereoscope.


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Figure 3 – Dr. Rebelo observes mussels in the stereoscope

Mussels have an external reproduction, which means they don’t do intercourse. Like many other species, they release their gametes (female eggs and male sperm) the water, where they meet and facundation happens.

This release of cells is called spawning and it is the tricky part of reproduction in the laboratory. In the environment, several factors can trigger the gametes release, water temperature being the main one. In lab conditions, however, mussels may need an extra stimulus. And sometimes, it simply doesn’t happen.

Our main concern was if we would find mature females. The peak of the reproductive season is December, and we were a little early. Luckily, however, ovaries were full and we could proceed with the spawning induction. We submitted the mussels to temperature change and a low concentration of serotonin. Even though mussels seemed happy filtering water, nothing seemed to happen in the reproductive field.

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Figure 4 – ovaries of female Limnoperna fortunes full of mature eggs


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Figure 5 – experimental set up for spawning in the Argentine Museum of Natural History.

After 12h mussels started to spawn. Less than we would want, but enough to see embryos in different stages of development: from single cell embryos 30 min old to 4 cell embryos with about 2h. They kept spawning for the whole day and allowed us to sample embryos for further experiments.

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Figure 6 – Mussel embryos after fertilization in the laboratory

The validated embryo production protocol is a major achievement for the further development of the esteryle mussels.