Bivavle Mollusks, such as mussels, are generally considered to be well-known bioengineers due to their ability to aggregate and reduce local flow conditions. They are impacted by changes in their microenvironment, such as alternations in seawater chemistry or water flow. As a result, there may be benefits such as lower energetic costs and risk of dislodgment in reduced flow. However, there may also be harmful effects such as minimal water exchange and less food availability. Furthermore, the chemical conditions within mussel bed aggregations can affect mussel survival rates due to changes in byssal thread production and overall attachment strength. At the UW Friday Harbor Laboratories, Summer 2019, we conducted laboratory experiments to quantify how mussels alter the chemistry of the interstitial spaces within their aggregations. Specifically, we placed aggregations of mussels (M. galloprovincialis) in a flume and measured the dissolved oxygen (DO) concentration within the aggregation, referred to as “in bed,” and compared it to the dissolved oxygen values upstream, referred to as “ambient.” The mussels were arranged to mimic the set up of an aquaculture rope. We found that the difference between ambient and in bed DO concentrations went up to 2.5 mg/L when flow was less than 5cm/s. This difference increased with temperature due to increased respiration. These findings indicate that flow and temperature mediate processes that determine the chemical microenvironment in a mussel bed. Furthermore, the conditions in these microscale environments may have important consequences for the survival of mussels and other species that rely on them for shelter.

Hydra vulgaris are some of the simplest animals with neurons. They only have two thin, near transparent layers of tissue: myo-endodermal and myo-ectodermal layers. Interspersed in each layer is a network of neurons known as the nerve net. All cells in the animal are constantly renewed, which allows Hydra to regenerate after being cut in pieces or dissociated into single cells, though how the nerve net regenerates has not been well studied. Each cell in the animal can be examined simultaneously due to the animals’ small size and simple, translucent body pattern. Hydra also exhibit stereotypical (regular and defined) behaviors. This makes Hydra great models for examining simple signaling pathways from which the complex pathways in vertebrates derive. The Hydra nerve net is composed of circuits that coordinate the behavior of the animal. The most obvious are the contractile burst (CB) and rhythmic potential (RP) circuits. I selectively blocked these circuits to understand how they drive behavior. It has been found that N-[1-(2-phenylethyl)-3-piperidinyl]-1-benzofuran-2-carboxamide (E9), affects Hydra behavior, appearing to block the CB circuit but leaving others, including the RP circuit, uninhibited (unpublished data, Woods Hole MA). I worked to understand the affinity and response rate of this molecule to Hydra by establishing a dose response curve for E9 on Hydra. To determine effective concentrations of E9, I imaged animals in serial concentrations ranging from 3uM-300uM. I then identified the response of neural circuit firing patterns to varying concentrations of E9 by applying this technique to animals that express GCaMP, a protein that fluoresces when bound to calcium, in neurons. I found that 30uM is the lowest concentration of E9 sufficient to block the CB circuit. This research provides a tool for studying the link between circuits and behavior, and allows us to characterize how behaviors depend on identified circuits.

Mislabeling fish is a common issue that is found nationwide. As it was found in “Bait and switch: UCLA study finds fish fraud runs rampant” that 26 of 47 fish types are mislabeled. Our study focused on retrieving samples of DNA from fish such as tilapia, cod, and salmon etc. However, our main focus was on Tuna. During this experiment all samples were tested for DNA sequences through polymerase chain reaction, Gel electrophoresis, and Sanger sequencing, which was performed in California. After receiving the DNA sequences from California, we inputted the forward and reverse sequences of the DNA into the Basic Local Alignment Search Tool (BLAST) and the Barcode of Life Database (BOLD), to identify what type of organism it was. Running the samples through both databases revealed that all of the fish samples were correctly labeled. This concludes that Tuna was not more mislabeled when compared to the rest of the fish samples.

In both natural and aquaculture settings, bivalve mussels form tight aggregations and act as ecosystem engineers, altering the flow of water around their microenvironment and potentially causing changes in seawater chemistry. Low flow reduces water exchange in the interstitial spaces within a mussel aggregation, which, in connection with mussel respiration, could lead to low oxygen conditions that are harmful to mussels and the many organisms which rely on them. Low dissolved oxygen concentrations affects a mussel's ability to create strong attachments and may negatively impact mussel survival in decreased water velocities. Through our research at UW's Friday Harbor Labs, we investigated how flow mediates water exchange and dissolved oxygen concentrations within the microenvironment of a mussel aggregation. As a part of a larger project to understand how flow affects interstitial chemistry in natural flow conditions, we conducted a field experiment to measure the exchange of oxygen within an aggregation of Mytilus galloprovincialis.The mussel aggregation, modeled to mimic mussels growing on an aquaculture rope, was deployed off of a floating dock. Using dissolved oxygen and water velocity probes, we quantified differences in dissolved oxygen concentrations between in-bed and ambient water across naturally occurring water velocities. Our data indicates that mussels reduce dissolved oxygen relative to ambient conditions, especially when flow speeds are less than 10 cm/s. In contrast, increased water velocites (> 10 cm/s) effectively flush the interstitial spaces with ambient water and equilibrate oxygen concentrations. This work provides field evidence in support of previous laboratory observations and indicates that mussels frequently create reduced oxygen conditions that could impact their survival in nature.  

Magnetoreception, an organism’s ability to detect Earth’s magnetic field, is a sixth sense shaping the niches of a vast array of life. Using this internal compass, magnetotactic bacteria orient themselves along magnetic fields, birds follow precise migratory routes, and mole rats can geolocate their nests. While the exact molecular mechanisms governing this sense have remained elusive, two prominent theories have emerged to unravel this phenomenon. Primarily found in bacteria, fish, and burrowing insects, the magnetite particle model (MPM) postulates that magnetite particles embedded in the cell act as putative mechanical receptors. However, as simple organisms evolved into more complex animals, the mode in which magnetic fields are detected also evolved. Found in migratory animals such as birds, the radical pair model (RPM) posits that cryptochromes, a protein family of photoreceptors found in the retina, adapted to double as a magnetoreceptor. Within this protein family, Cry1a, a cryptochrome playing a key role in regulating circadian rhythm, has been shown to form chemical intermediates containing magnetically sensitive radical electron pairs. These radical pairs, in turn, alter products of the reactions facilitated by Cry1a. This literature review aims to elucidate the role of Cry1a as a putative magnetoreceptor, while applying phylogenetic analysis to better understand evolutionary adaptations of cellular responses. Using “Cry1a” AND “magnetoreception” as search terms, literature on the role and function of Cry1a was mined from Pub Med with emphasis on taxonomic diversity. Results show RPM-mediated magnetoreceptive organisms have developed independent of a common ancestor, suggesting this to be a homoplastic trait triggered by environmental factors to harvest an existing photosensitive system. Moreover, recent findings showing increased neural responses in magnetized Drosophila fly larva provides crucial evidence supporting the dual function of Cry1a. Further research into the underpinnings of these responses is needed to advance our understanding of this biologic mystery.

Retinal diseases tend to affect specific neuron subtypes, ranging from age-related macular degeneration, which is caused by the deterioration of photoreceptors near the central portion of the retina (macula), to glaucoma, in which abnormally high intraocular pressure leads to ganglion cell death. Unfortunately, adult mammals are not able to regenerate retinal neurons. However, zebrafish and other amphibians can completely regenerate their retinal neurons in many different models of damage, and restore retinal structure and visual function. The source of regeneration stems from the resident Müller glia cells, which normally provide neuronal support and span all three retinal layers. A critical gene for the initiation of transforming Müller glia into neurons was found to be Ascl1. This led our lab to hypothesize that the introduction and upregulation of Ascl1 in mammalian Müller glia might stimulate them to become retinal neurons after damage, as occurs in these other regenerating species. Indeed, after introducing Ascl1 into the Müller glia of mice, we found newly regenerated retinal interneurons (bipolar cells) that successfully integrated into the retinal circuitry and functionally responded to light stimulus. In addition to Ascl1, we have identified two other transcription factors, that when introduced in combination with Ascl1, stimulate the generation of two different retinal neurons (ganglion cells and amacrine cells). We are currently developing a model of glaucoma, damaging the ganglion cells with a neurotoxin, and then testing the visual acuity using Optomotry to determine whether regenerated ganglion cells will mediate a functional improvement. Ectopic expression of a proneural transcription factor to stimulate retinal regeneration provides a potential therapeutic intervention for treating blinding diseases, that even now, have few modest treatment options.

Mosquitoes primarily navigate using their olfactory system and can use this system to form “memories” that influence their choice in hosts. When a mosquito encounters an odor, information is sent through the antennal lobes in the brain to the mushroom bodies, which are structures responsible for learning and memory consolidation. This odor-learning pathway is mediated by neurotransmitters like dopamine and serotonin. Recent research has shown that the mosquito Culex quinquefasciatus has extremely low levels of dopamine in the antennal lobes compared to other species, and is unable to learn to avoid odors associated with a negative response. This led us to predict that dopamine is essential for aversive learning in mosquitoes. We hypothesized that Cx. quinquefasciatus differed from other mosquitoes in learning ability because they were previously tested in the light and they are the most nocturnal of the originally tested species. To test this hypothesis, we conditioned the mosquitoes in the absence of light in an aversive learning paradigm to measure how frequently they chose to avoid the conditioned odor. An inability to learn regardless of light condition would indicate that the role of dopamine as a neuromodulator in the antennal lobes evolved partly to allow diurnal mosquitoes to avoid defensive hosts. Next, specific neurotransmitters in the antennal lobe were mapped using confocal microscopy, revealing their concentrations which may explain behavioral differences from other mosquitoes. Most mosquito species show some plasticity in host selection, which can lead to the transmission of animal diseases, like West Nile Virus, to humans. Mosquitoes are the world’s deadliest disease vector, killing over 700,000 people globally each year, so understanding how and why this adaptation occurs can help us understand the framework that underlies the spread of mosquito borne diseases and bring us one step closer to solving this global issue.