Genetic crosses

NCMA2022 experiment update: Phenotyping 1,147 fish

Groton, 24 July 2022. A remarkable week ends with a sense of pride, accomplishment and a good dose of exhaustion. After more than two months of rearing, the silversides from our crosses in May have grown big, and at least for the warm, 26C treatment, they reached their final, intended size (~40 mm). Our rearing job came to a successful end, and now post-doctoral researcher Jessica Rick and PhD-student Maria Akopyan came back to the Rankin Lab equipped with hundreds of tubes and lots of RNAlater to finalize the sampling. This involved measuring the critical sustained swim speed of every individual fish, followed by meticulous measurements, photographs, and eventually an individual tube for preservation in RNAlater. Over the course of 9 days (and over 10h of work each day), the team measured 1,147 fish, which ranged in size between 15 and 50 mm. A big hat tip to the hard-working geneticists!

On 16 July 2022, Maria (left) and Jessi (right) are working meticulously through their individual sampling protocol of silversides reared for two months at 26C. Every rearing container contains about 40 fish.

On 21 July 2022, most of the rearing containers have been sampled and only 5 remain.

Maria is tackling individual length and weight measurments, photographing, labeling and preserving of silversides.

The old swim flume that has seen its fair share of experimental work, is being put to good use once again.

To calibrate the dial of the swim flume to flow speeds, we use dye and video recording.

Now, our rearing job still continues until the crosses in the 20C treatment reach their final size, when the second session of phenotyping will need to happen. And of course, there iare so many more steps to follow. Stay tuned.

On 16 July 2022, Maria looks concentrated while taking a picture of a reared silverside.

NCMA2022 experiment update: first genetic material sampled

18 June 2022. We are happy to report that our genomic silverside experiment has progressed from "Can we really pull this off?" to "We think we just might" over the past weeks. The silverside larvae of these different crosses show stunning size variability, between populations and temperatures. We already obtained two early life mortality estimates and lots of genetic material, including a full set of crosses reared at 26C and ad libitum food, reaching 20 mm in roughly 4 weeks post hatch. Fingers crossed for the rest of the rearing time.

9 dph larvae from the North Carolina Batch fertilization, waiting to be counted on 9 June 2022

Visually stunning comparison of 9 dph silverside larvae reared at 20C from North Carolina batches vs. Massachusetts batches

Digital length measurements of a small subsample of silverside larvae from the 26C treatment (crosses unknown)

Silverside juveniles subsampled on 16JUN 2022 from bucket 3 of tank D (D#), housing the Massachusetts Batch (B4 of 7) in the 26C treatment, counted via ImageJ, preserved in RNAlater