Shelly A. Trigg: Hi everyone, my name is Shelley trig and I am a postdoc at the University of Washington in the School of aquatic and fisheries sciences. Today I'm going to be talking about a combination of a series of experiments exploring the tolerance of Pacific gooey duck.
Shelly A. Trigg: To low pH through comparative physiology genomics and DNA methylation. Before I get started, I'd like to acknowledge the CO authors.
Shelly A. Trigg: Who are collaborators from University of Rhode Island. My advisor Stephen Roberts some others from University of Washington and Washington see grants and the Jamestown school on point with need hatchery and tribe.
Shelly A. Trigg: This work is funded by the US Department of Agriculture foundation for Food and Agriculture Research
Shelly A. Trigg: If you're not familiar with the Pacific gooey duck. These are large bearing clams that are native to the north eastern Pacific and they range from Alaska down through California
Shelly A. Trigg: There are among the most valuable farmed shellfish on a per acre basis and they bring in over $20 million dollars in annual sales to Washington State alone.
Shelly A. Trigg: I wanted to show a picture of gooey duck seed, which are about three to five millimeters across and these get planted out in these large plots.
Shelly A. Trigg: Each one of these little circles is a PVC tube that is about 12 inches deep. It's open on both ends and one seed goes in each tube and the tube is to serve as protection as the animal develops.
Shelly A. Trigg: And as they get bigger and bigger they burrow deeper into the sand. So they'll eventually grow out of the tube.
Shelly A. Trigg: Gooey duck are also ecologically important because they serve as bio filters and as a prey source for many animals. They're important culturally as they have sustained tribes as food and as a revenue source.
Shelly A. Trigg: So the question how pH effects gooey duck comes from trying to understand how these animals might tolerate the ocean acidification conditions that are predicted for the future.
Shelly A. Trigg: And also,
Shelly A. Trigg: To see if stress conditioning of these animals could be beneficial in agriculture. For instance, if adults were exposed to a low pH condition, could they potentially pass on a resilience traits to their offspring.
Shelly A. Trigg: Or if juveniles were exposed to a low pH condition would it make them more resilient to low pH that they experienced when they're adults.
Shelly A. Trigg: So to begin answering these questions. These experiments and I'm going to talk about. Look at the pH effect on rootstock performance and reproductive development juvenile development and potential carryover effects or in other words traits that get passed down from parents to offspring.
Shelly A. Trigg: This first experiment looks at the impact of static low pH on rootstock so here animals were exposed to either ambient or a low pH for 93 days and I found that the low pH negatively impacted rootstock survival.
Shelly A. Trigg: I also found that it delayed female reproductive development. So here we're looking at representative images of the gonads from animals from an animal in the ambient group and the low pH group.
Shelly A. Trigg: There's a lot of pink here in the pink is connective tissue and there's fewer purple dots and those are the eggs. The white is the follicle area. So you can see there's smaller follicles in the low pH group, meaning that they are less mature.
Shelly A. Trigg: We looked at this at two different time points 72 days after they exposure. So we can see this is the same data is just looking at more images and
Shelly A. Trigg: There are smaller egg sizes in the low pH group and then at the later time point the egg size tended to be really similar. However, there's differences in
Shelly A. Trigg: Connective tissue proportion, which actually these ambient animals showed signs of spawning and egg resort option.
Shelly A. Trigg: Which was less apparent in the low pH group, although the low pH group was showing signs of reproductive development. So they were still developing. But just at a delayed rate.
Shelly A. Trigg: We did not see this develop this a reproductive delay in the males. We saw similar proportions of immature and mature sperm.
Shelly A. Trigg: And then what you would expect, over time, there will be larger proportions of mature sperm and that happened in both the groups, indicating similar reproductive development rates.
Shelly A. Trigg: So now I'm going to talk about another experiment that was done on juveniles looking at static low pH. This is an experiment that was carried out by Holly Putnam, who is now a P i and the University of Rhode Island.
Shelly A. Trigg: And this is work she did as a postdoc and Stephen Roberts lab and what she did was exposed juveniles to either ambient
Shelly A. Trigg: Moderate low pH or a very low pH condition for 23 days after the 23 days she moved the animals into an ambient condition. A common garden condition and then split them back out after 112 days in this common garden to either ambient or a low pH condition.
Shelly A. Trigg: And this was to ask if
Shelly A. Trigg: The pH that the animals experiment experienced initially would impact how they responded to the second exposure, she found that after the initial exposure animals exposed to very low pH or smaller in size than the other groups.
Shelly A. Trigg: However,
Shelly A. Trigg: When
Shelly A. Trigg: Being in the common garden for a few weeks and then
Shelly A. Trigg: At the end of the common garden, she found that animals exposed initially to moderate or low pH showed an accelerated growth compared to animals just in the ambient condition.
Shelly A. Trigg: In the during the second exposure and at the end of the second exposure.
Shelly A. Trigg: She saw that they
Shelly A. Trigg: Ambien animals.
Shelly A. Trigg: That had never seen the low pH actually showed a growth delay when they experienced the low pH condition where animals that had seen the moderate or low pH initially did not experience the growth delay this indicated, there was some kind of environmental memory.
Shelly A. Trigg: With seeing that low pH initially and to understand what that might be. We sequenced the gooey duck genomes using 10 X genomics and phase genomics and we found 18 scaffolds that span 942 mega bases. And this included about 35,000 genes.
Shelly A. Trigg: We looked at DNA methylation and you can see that there's high methylation within jeans and these animals.
Shelly A. Trigg: I performed a differentially method region analysis from animal sampled at different time points. What we're looking at here are heat maps of different regions each row of the heat map is a different region and
Shelly A. Trigg: The red indicates high methylation and blue indicates low methylation and the column on the left is the ambient animals, the column on the right is the low pH animals in the column in the middle is some moderately low pH.
Shelly A. Trigg: Exposed to animals. So you can see at these different time points. There are different regions that are
Shelly A. Trigg: That are showing changes in their methylation.
Shelly A. Trigg: And I wondered if these regions might be in particular genomic features and I found that after 10 days. These regions tended to be in three prime UT are regions and after the second exposure.
Shelly A. Trigg: also saw that they were in three prime UT are regions and within interests and overall these regions tended to be in jeans and particular
Shelly A. Trigg: After the common garden, the methylation differences tended to be in genes involved inside a skeleton activity where after the second exposure. These two did to be in genes involved a nucleic acid binding and mitochondrial activity.
Shelly A. Trigg: So I'm going to move on to talk about another experiment, looking at the impact of variable low pH on rootstock
Shelly A. Trigg: And these are similar conditions to the first experiment I showed the only differences, we're looking at a variable pH.
Shelly A. Trigg: And it's also for a shorter shorter period of time. So I did not see an impact on survival during the exposure and I saw
Shelly A. Trigg: Again, no real difference in survival. When these animals were at ambient condition.
Shelly A. Trigg: They similarly declined.
Shelly A. Trigg: And then to look at if the parental conditioning impacts their offspring performance. We looked at
Shelly A. Trigg: Larvae so we reared their larvae under ambient conditions and then we looked at their size. So this is data that was generated by Sam girl who's a grad student at University of Rhode Island.
Shelly A. Trigg: And the here we're looking at size over time and the blue boxes are animals from parents that were exposed to ambient pH and the yellow boxes are
Shelly A. Trigg: Animals from parents that were exposed to the variable low pH. So you can see in general there's not much of a size difference between the parents so their parents conditioning had little impact on their size, except at these two time points.
Shelly A. Trigg: Sam also measured their metabolic rate over time. And he found that in general the animal. The larvae from parents that were exposed to variable low pH showed a reduced metabolic rate.
Shelly A. Trigg: So regardless of their size.
Shelly A. Trigg: Meaning they were able to achieve the same
Shelly A. Trigg: Size, but with a reduced metabolic rate.
Shelly A. Trigg: Now I'm going to talk about the
Shelly A. Trigg: Impact of variable low pH on juvenile offspring development. So I took those larvae and I reared them.
Shelly A. Trigg: Under continued wearing them under ambient conditions until they were juveniles and then I expose these juveniles to either ambient or variable low pH, the same conditions as I expose their parents to
Shelly A. Trigg: I found that variable, variable low pH exposure lead to reduced survival, regardless of parental conditioning.
Shelly A. Trigg: There was a marginal effect from parental conditioning, meaning that
Shelly A. Trigg: They showed slightly reduced survival compared to ambient parents, but it was not a significant effect.
Shelly A. Trigg: also looked at size at the end of this experiment, and I saw that parental and juvenile variable low pH exposure had an interactive effect and led to larger sized animals.
Shelly A. Trigg: Then I also measured their metabolic rate over time. And in general, I saw that the parental variable low pH exposure generally lead to lower metabolic rate in July in the juveniles.
Shelly A. Trigg: So here the darker color means they had Ambien parents and the lighter color means they had low pH treated parents. So you can see
Shelly A. Trigg: There's a few quite a few time points where they show a lower metabolic rate.
Shelly A. Trigg: So in summary, rootstock
Shelly A. Trigg: In regards to the brutes doc and reproductive development. The longer duration and constant low pH exposure is more detrimental to the brutes doc survival and female reproductive development is more sensitive to low pH than males.
Shelly A. Trigg: Regards to juvenile development. There is evidence for this environmental memory and that the initial low pH exposure led to larger animals, four months after they experienced that low pH.
Shelly A. Trigg: And these were. This was associated with methylation changes and jeans related to cite a skeleton activity initial low pH exposure.
Shelly A. Trigg: prevented a growth delay that was seen a naive juveniles and this was associated with methylation changes in jeans related to nucleic acid binding and mitochondrial activity.
Shelly A. Trigg: And in terms of carryover effects. I found that parental variable low pH conditioning leads to reduce the energy demand and offspring that achieve the same or larger size under low pH condition.
Shelly A. Trigg: And the implications of the all of this or that pH can be used to induce beneficial trades that persist over time the effects seem to be staged dependent and conditions need to be further optimized.
Shelly A. Trigg: To find
Shelly A. Trigg: What's going to be the best in doc local church conditions. So if you have any questions about this research, please feel free to message me
Shelly A. Trigg: On the path double meeting platform or email me at st@uw.edu thank you so much for tuning in. I hope you have a great rest of the conference. And I hope to hear from you.