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Biology

Research Presentation Videos

Watch Mitsuko Yabe '14 discuss her research project.

Watch Parth Patel '15 discuss his research project.

 

Studies on Vesicle Transport in Drosophila

Alan Chen (2014); Student Collaborator(s): Karen Leung (2014 CMC); Michelle Ozaki (2016 SCR); Additional Collaborator(s): Zhaohua Irene Tang (W.M. Keck Science Center of the Claremont Colleges); Ruye Wang (HMC); Mentor(s): Clarissa Cheney

Abstract withheld upon request.
Funding Provided by: Howard Hughes Medical Institute

Studies on Vesicle Transport in Drosophila

Evenson William (2014); Mentor(s): Clarissa Cheney

Abstract withheld upon request. 
Funding Provided by: Howard Hughes Medical Institute

Mechanisms of FAD and NAD(P)H-dependent persulfide and polysulfide reducing enzymes of Pyrococcus and Archaeoglobus

Brian Zhu (2014); Mentor(s): EJ Crane

Abstract: FAD and NAD(P)H-dependent coenzyme A disulfide/polysulfide reductases (CoADR/Psr) have been proposed to be important in the sulfur metabolism of the SO-reducing anaerobic hyperthermophiles Pyrococcus and Thermococcus. In these studies, we determined the structure for the FAD and coenzyme-A containing holoenzyme from P. horikoshii and characterized its substrate specificity. The enzyme is capable of reducing a variety of persulfide, disulfide, and polysulfide compounds. The results suggest that likely in vivo substrates are NAD(P)H and per and polysulfide derivatives of coenzyme-A, although the aerobic rapid recycling of persulfide substrate observed may explain findings that CoADR is non-essential for SO respiration in Pyrococcus or Thermococcus and instead participates in oxidative defense in the presence of SO. One homologue of CoADR, Npsr, is usually found only in mesophilic bacteria. We are currently characterizing the Npsr of the sulfate (but not sulfur) reducing Archaeoglobus fulgidus, the only Npsr found in archaea or hyperthermophiles to date.
Funding Provided by: Class of 1971 SURP Fund

Analysis of Reproduction and Regeneration in an Endemic California Conifer

Scott Lindburg (2014); Mentor(s): Frances Hanzawa

Abstract: As the climate warms, some plant populations can respond by shifting their geographic or elevation range, and some individuals can acclimate physiologically. Pseudotsuga macrocarpa, a Southern California native tree, exists across a wide elevation gradient, but previous research showed that the low elevation populations are not regenerating since no young trees are found. We examined one cause of this likely range contraction by analyzing P. macrocarpa reproduction across a 1366-meter elevation gradient. We also measured two variables related to water use efficiency, stomatal density and δ13C, to assess how the trees are responding to environmental conditions across elevations. We found that the number of developing cones, stomatal density, and δ13C all display a quadratic relationship with elevation. In addition, we found that the number of initiated cones has a linear relationship with elevation. This is most likely due to adverse climate conditions or low pollination rates at the higher sites, which caused a larger proportion of the cones to abort at those elevations. The results suggest that low reproduction, as well as low survival rates of seedlings, contributes to lack of replacement of the populations at the low elevations. Existing trees, however, adjust to warmer, drier conditions by increasing their water-use efficiency. It is likely that the low elevation populations of this tree will eventually go locally extinct due to the unfavorable conditions caused by rising temperatures and reduced precipitation at the lower sites.
Funding Provided by: Sherman Fairchild Foundation

Effects of TiO2 and C60 nanoparticles on development and survivorship in Pieris rapae larvae

Helen Lamb (2015); Mentor(s): Frances Hanzawa

Abstract: The long-term effects of increasing environmental nanoparticle (NP) deposition on natural populations are poorly understood; NP concentration and effects could amplify as NPs move through the food web. In this experiment, we fed Pieris rapae (cabbage white butterfly) larvae with an artificial food containing NP TiO2 or C60 to determine whether NP consumption affects the development or survivorship of P. rapae. We tested two concentrations of each NP. We recorded each larva’s instar and survival daily, and measured body weight on days 9, 14, 21, and 28 (day 0 = day eggs were laid). We found that nano-TiO2 decreases survivorship and growth of larvae while C60 does not affect either. Nano-TiO2 and C60 both reduce the developmental rate of larvae, but the effect of nano¬TiO2 is stronger. These results call for further study of C60 in the environment and increased regulation of nano-TiO2 manufacture and disposal.
Funding Provided by: Schulz Fund for Environmental Studies

Significance of Snow Leopard Hemoglobin B Gene in High Altitude Adaptivity in the face of Climate Change

Mitsuko Yabe (2014); Additional Collaborator(s): Peggy Barr (Western University of Health Sciences College of Veterinary Medicine); Andrea Wournell (Western University of Health Sciences College of Veterinary Medicine); Mentor(s): Richard Hazlett

Abstract: Snow leopards (Uncia uncia) are endangered species threatened by habitat loss caused by climate change effects such as desertification and anthropogenic threats such as hunting. In order to combat high altitude, hypoxic environments, they may have adaptive modifications that are genetically based in single nucleotide polymorphisms (SNPs). In natural populations of deer mice, four amino acid substitutions in the hemoglobin B (HBB) protein have been attributable to allelic differences that are responsible for better fitness in high altitude environments. The purpose is to examine if there are parallel mutations in snow leopard HBB genes. Without these mutations, snow leopards may experience higher susceptibility to global warming conditions where CO2 concentrations are richer and oxygen is low in these environments. Genotyping-by-sequencing (GBS) technology, an approach for mapping traits in high diversity organisms, was chosen to identify SNPs across the entire snow leopard genome, including HBB. We extracted DNA from blood from 75 captive and 11 wild snow leopards and sent it to Cornell University for GBS; however, data has not been returned. As an alternative method, we amplified the HBB gene from snow leopard genomic DNA using primers based on a comparative analysis of the HBB gene of other species, including dog, pig, mouse and human. The optimization PCR resulted in multiple faint bands, and a single stronger 0.7 kb band (vs. expected 1.2 kb size), suggesting primer binding with non-HBB regions of the snow leopard genome. New primers will be designed and tested.
Funding Provided by: Koe Family Fund

Localization of two arginine vasotocin receptor types in Litoria caerulea

Jonathan Feingold (2015); Mentor(s): Kristine Kaiser

Abstract withheld upon request.
Funding Provided by: Schulz Fund for Environmental Studies; National Science Foundation (UCR)

The effect of anthropogenic noise on luteinzing hormone receptor and testosterone levels in White's treefrog testes

Neha Savant (2014); Mentor(s): Kristine Kaiser

Abstract withheld upon request.
Funding Provided by: Rose Hills Foundation

Effect of corticosterone levels on the rate of wound healing

Maria Arciniega (2016); Additional Collaborator(s): Sarah DuRant (Tufts University); Carolyn Bauer (Tufts University); Mentor(s): Jane Liu

Abstract: The stress response is characterized by increased secretion of glucocorticoids (CORT) into the bloodstream. While the stress response is adaptive in the short-term, prolonged stressors can result in chronic stress. Chronic stress, typified by increased exposure to CORT, can cause several pathological effects including decreased growth, inhibition of reproduction, and immunosuppression. We hypothesized that increased exposure to CORT prior to wounding would slow the rate of healing. We chronically stressed house sparrows (Passer domesticus) and manipulated their CORT levels to analyze the effect of prior CORT exposure on wound healing. One treatment group received injections of mitotane, which decreases CORT levels. Another treatment group received exogenous CORT. All birds were chronically stressed for 10 days, after which mitotane and CORT treatment was discontinued. All birds were wounded on Day 11 and wound healing rate was recorded until all birds were completely healed. Blood samples were taken periodically to confirm the manipulation of CORT levels. While we successfully decreased CORT levels in mitotane birds and increased CORT levels in exogenous CORT birds compared to control birds, we still found no significant difference in healing rates between treatments. Contrary to our predictions, increased CORT exposure prior to wounding did not slow the rate of healing. In conclusion, these findings indicate that the relationship between stress and wound healing is complex.
Funding Provided by: National Science Foundation # CBET-1258307

The Role of the Retinoblastoma Protein in Calcific Aortic Valve Disease

Maxine Garcia (2016); Student Collaborator(s): Marina Freytsis (Sackler Graduate School of Biomedical Sciences); Additional Collaborator(s): Gordon Huggins (Tufts Molecular Cardiology Research Institute); Philip Hinds (Sackler Graduate School of Biomedical Sciences); Mentor(s): Jane Liu

Abstract: Calcific aortic valve disease is a progressive disease that involves calcification of aortic valve leaflets. A better understanding of the biological mechanisms responsible for calcification of the aortic valve is required to develop better therapies. The retinoblastoma protein (pRb), expressed by the RB1 gene, has been identified as a key protein in osteogenesis. pRb forms a complex with RunX2, a transcription factor that enhances expression of bone-specific promoters. The role of pRb in osteogenesis led us to question the role this protein plays in aortic valve calcification. We hypothesize that pRb is directly involved in the biological mechanisms that cause aortic valve calcification. We hypothesized that we can knockdown pRb using a lentivirus containing shRNA. We also hypothesized pAVICs would calcify in response to osteogenic signals and that the intensity of response would differ between lots of fetal bovine serum. Through puromycin selection and western blot analysis, we found that though there was successful transduction of the lentivirus, knockdown of pRb did not ensue. Additionally, all serum lots exhibited calcific nodules when stained with alizarin red S. In two lots, osteogenic markers were highly expressed in serums treated with osteogenic signals. We will further study the role of pRb using the serums tested with osteogenic signals; we also hope to optimize parameters of the lentivirus infection to develop mutant pAVICs with pRb knockdown.
Funding Provided by: Molecular Cardiology Research Institute

Hydra viridissima and its Chlorella endosymbiont

Alonso Iñiguez (2015); Mentor(s): Daniel Martínez

Abstract: The origin and evolution of the endosymbiosis between the green hydra and its algal endosymbionts remains to be explored. Physiological studies performed to characterize the relationship between the endosymbiotic algae and hydra hosts suggest a mutualistic relationship due to the bi¬directional flow of nutrients. In order to better understand this relationship and the taxonomy of green hydra, we have undertaken a molecular phylogenetic study including green hydra collected from all over the world. Using nuclear and mitochondrial nucleotide sequences, we have reconstructed the phylogenetic relationship of the hydra hosts and algal endosymbionts. The endosymbiotic algae cluster in five distinct clades within a deeper Chlorella clade. Interestingly, the hydra hosts also group in five clades each with its unique alga. We found no evidence of co¬evolution, that is, of phylogenetic congruence, between the phylogenies of the hydra and the algae. The different algae that have established stable endosymbioses with hydra are not closely related to one another. Instead, they are related to different kinds of free-living algae. Our current working hypothesis is that after the initial establishment of the endosymbiosis between green hydra and algae, different algal replacement events have occurred.
Funding Provided by: Elgin Fund; National Institute of Health #1R01AG037965

The effects of stress and epigenetics on senescence in Hydra oligactis

Lauren Penfield (2014); Additional Collaborator(s): Emma Burdekin (2016); Mentor(s): Daniel Martínez

Abstract: The lack of senescence in hydra has raised many questions about the causes of aging. One hydra species, Hydra oligactis, can live indefinitely with constant budding rates at 18 °C. At a colder temperature of 10 °C, the majority of H. oligactis begin to reproduce sexually and show signs of aging. However, in a recent study in our laboratory, only 60% of hydra died from physiological decay. The remaining 40% of hydra reverted back to asexual or were never induced (~1%). These natural revertant hydra have been maintained at 10 °C for over one year. It is thought that testes formation is related to revertance because the natural revertants developed significantly more testes at a later time compared to the aging hydra. However, the exact mechanism behind revertance is unknown. To test for an epigenetic component of revertance, buds of the natural revertant hydra were collected and maintained at 18 °C for one month. These hydra then were induced at 10 °C. The natural revertant buds had significantly fewer testes compared to the aging hydra and had similar testes rate and formation compared to the original revertants. Additionally, to determine if stress is a factor in revertance, a cohort of H. oligactis were stressed by a long term heat shock prior to induction at 10 °C. Compared to the controls, the hydra stressed before induction had significantly fewer testes and fewer buds at early stages. These data suggest both health and genetics could play an important role sexual induction.
Funding Provided by: Sherman Fairchild Foundation

Alcyoniid Biodiversity of Dongsha Atoll

Samuel Du (2016); Student Collaborator(s): Sara Shi (2016); Prudence Hong (2016 HMC); Mentor(s): Catherine McFadden (HMC)

Abstract: The tropics of Cancer and Capricorn delineate the tropical zone, where conditions are ideal for coral reef formation. Dongsha Atoll, located south of Taiwan in warm water, sits squarely within this area and has substantial coral development of the family Alcyoniidae. Penghu Archipelago, west of Taiwan in cold water, is located on the very edge of the tropical zone, which is considered too north to have true coral reef development. However, despite its location, many species that inhabit usually reefs can be found there. A research interest of this lab is to compare the two reefs and see how much overlap there is between the two locations. Because it is difficult to identify species by physical characteristics, our understanding of the biodiversity of these different reefs is limited. To enhance our ability to identify species quickly and accurately, previous work has found a genetic “barcode” of three genes unique to each species: cytochrome oxidase I, mitochondrial mutS and 28S rDNA. We received samples from Dongsha Atoll, extracted DNA, and then amplified and sequenced the three genes. The samples were then proofread and aligned to a tree with representative species from previous surveys of Taiwan and elsewhere. We have found representatives from eleven genera at Dongsha, compared to only six from Penghu. At this time, we have not been able to identify all the samples at a species level, though the number varies by genera.
Funding Provided by: Howard Hughes Medical Institute

Xeniid Biodiversity of Green Island

Sara Shi (2016); Student Collaborator(s): Samuel Du (2016); Prudence Hong (2016 HMC); Mentor(s): Catherine McFadden (HMC)

Abstract: Green Island lies east of Taiwan at the limits of the tropical zone at about 22.6°N, supporting the family of soft corals, Xeniidae. There has been growing interest in Xeniidae because of their rapid colonization after reef disturbances. Identifying species of this family by sight, however, has proven difficult for field researchers as physical characteristics that differentiate species are not well defined. From Indonesian xeniids, it has been determined that there are several genes that can be used as “barcodes” to better identify xeniid species. Using these molecular “barcodes” from the cytochrome oxidase I (COI) gene, the mitochondrial mutS gene, and the 28S rDNA gene, we have been able to more accurately identify species of xeniids. We extracted DNA from samples we received from Green Island, amplified, purified, and sequenced each barcode gene, and analyzed the sequences. We have been able to compile phylogenetic trees for our samples, and using the three different genes, we have been able to identify some species and determine the closest relatives of others. Future work will involve analyzing and comparing barcodes of previously studied Indonesian xeniids against Green Island xeniids to compare species diversity among locations.
Funding Provided by: Howard Hughes Medical Institute

What a Tangled Web We Weave: Preserving Spider Biodiversity in Suburban Southern California

Dakota Spear (2015); Student Collaborator(s): Weston Staubus (2014); Mentor(s): Wallace Meyer; Jonathan Wright

Abstract: Spiders (order Araneae), as the largest and most diverse taxon of terrestrial predators, fulfill a vital ecological function, yet are poorly studied, with species of many regions still unknown. The coastal sage scrub (CSS) ecosystem is currently listed as endangered by the USGS, and has declined by 85 to 98% of its original distribution. Further study of spider communities in this endangered habitat type is required in order to make informed decisions regarding the management and preservation of the CSS ecosystem and the spider species that depend on it for their survival. In this study we use pitfall trap sampling to examine differences in the spider communities between the Bernard Field Station (BFS) in Claremont, CA, an 86 acre protected region consisting of CSS, grassland and recovering CSS habitats, and the surrounding suburban area. Significant differences in the spider community exist between the BFS and suburban Claremont, and species richness is significantly greater within the BFS. Spider communities also significantly differ among the three habitat types within the BFS. The BFS is a habitat island that provides refuge for a spider community unique from that of the surrounding suburban area; therefore, protected areas like the BFS are critical to the preservation of spider diversity.
Funding Provided by: Howard Hughes Medical Institute

Comparing ant communities among habitat types in a Southern California suburban matrix: conservation implications

Weston Staubus (2014); Student Collaborator(s): Dakota Spear (2015); Mentor(s): Wallace Meyer; Jonathan Wright

Abstract: Coastal sage scrub (CSS) once flourished in Southern California’s Mediterranean climate, extending from Baja California to the Central Coast. However, human incursion has eliminated CSS from over 85% of its historic range. Much of the remaining CSS exists as habitat islands surrounded by an urban/suburban matrix. The effects of such dramatic habitat loss on native ant communities are unknown. As such, managers are ill-equipped to make informed conservation decisions. In this study, we investigated the ant communities in and around a single CSS fragment located within the Robert J Bernard Biological Field Station (BFS), an ~ 90 acre research station belonging to the Claremont colleges. In addition to CSS, the BFS also contains a non-native grassland habitat and a transitional habitat where the grassland is being recolonized by CSS shrubs. The close proximity of these habitats presents a rare opportunity to examine differences among ant communities in each habitat type, without confounding variables such as climate variation or dispersal. Ants were collected from 48 sites (3 pitfall traps per site) in CSS, grassland, transitional, and suburban habitats. We found that the ant community within the BFS significantly differed from the community outside, but that the communities did not differ among CSS, grassland, and transitional sites. Our results indicate that preservation of undeveloped lands in Southern California is essential for conservation of ant diversity.
Funding Provided by: Howard Hughes Medical Institute

Variable Lymphocyte Receptor Gene Regulation in Lamprey Provides Insight into the Evolutionary Origins of Adaptive Immunity

Wanyi (Jennifer) Jia (2016); Mentor(s): Jonathan Moore

Abstract: In jawless vertebrates, leucine rich repeats encoded by DNA cassettes flanking the variable lymphocyte receptor (VLR) genes generate equal diversity present jawed vertebrates’ B cell immunoglobulins and T cell receptors. One of the two remaining jawless vertebrates, the lamprey, has three types of VLRs: A, B, and C. Although VLRA and VLRB are analogous to T cell and B cell receptors, it is still unknown whether jawless and jawed adaptive immunities are convergent or divergent evolutionarily. In the VLRB gene, an 862 base pair region was discovered to have regulatory properties of the variable lymphocyte receptor B. Specifically, the first 150 base pair segment contains transcription factor binding sites. Located upstream of the VLRB gene is a putative regulatory element of 494 base pairs called B.2. From previous research results, B.2 exhibited inhibitory effects on the expression of luciferase when transfected into catfish B and T cells. To determine the function of B.2, we engineered a B.2 tetramer and introduced it into a vector with an EGFP reporter gene for lamprey embryo injections. Furthermore, B.2 was broken into three segments of similar lengths to test which part is sufficient in carrying out VLRB transcription inhibition in catfish.
Funding Provided by: Howard Hughes Medical Institute

Novel Minor Histocompatability Antigen Discovery

Tyler Hill (2014); Additional Collaborator(s): Tanya Cunningham (Fred Hutchinson Cancer Research Center); Mentor(s): Marie Bleakley (Fred Hutchinson Cancer Research Center)

Abstract: Minor histocompatibility (H) antigens play an essential role in mediating graft vs. host disease and graft vs. tumor response in allogeneic bone marrow transplants. Few minor H antigens have been molecularly characterized, hindering clinical assessment of their importance in transplant medicine. Genome Wide Association Studies (GWAS) incorporates phenotype data obtained from functional assays, in conjunction with well-studied and SNP mapped collections of lymphoblastic cell lines (LCL) from the Centre d’Etude du Polymorphism (CEPH), to allow for relatively efficient identification of minor H antigen loci. Minor H antigen specific T cell clones were generated by primary in vitro stimulation of naïve T cells. The restricting HLA alleles for each T cell clone were determined through lysis assays of LCL expressing only one of the potential HLA-restricting alleles. CTL clone 1 is restricted by HLA-B7 and CTL clone 3 is restricted by HLA-A2. The frequency of minor H antigen recognized by CTL 1 is 84% (n=19) and 3 is 23% (n=13). HLA expression of cell lines transfected by vaccinia with restricting HLAs were confirmed by flow cytometry. Successful transfection of many target LCL was not achieved. The variation in rate of transfection was due in part due to innate differences between LCL. In the future, stable transfected LCL will be created by lentiviral transfection followed by fluorescence aided cell sorting. The identity of the two minor H antigens will be determined after further phenotyping of CEPH LCL and GWAS.
Funding Provided by: Cancer Center Support Grant (CCSG) CURE Supplement: NCI 5 P30 CA015704-39; K23CA154532-01 from the National Cancer Institute

Investigating lymphangiogenesis in the adult mammary gland during normal and tumor development

Sarah Black (2014); Additional Collaborator(s): Pepper Schedin (University of Colorado Cancer Center); Mentor(s): Traci Lyons (University of Colorado Cancer Center)

Abstract: Breast cancer diagnosed in the postpartum period often has a poor prognosis, in part because of the increased metastatic potential of this type of cancer. In the postpartum period, after the cessation of milk production, or after birth in the absence of lactation, postpartum mammary gland involution occurs. During postpartum involution, the microenvironment within a mammary gland changes dramatically to exhibit multiple pro-tumorigenic and pro-metastatic characteristics normally associated with wound healing and inflammation. The Schedin lab has observed increased lymphangiogenesis, a hallmark of wound healing and inflammation, during postpartum involution in rodent and human mammary tissues. Furthermore, in xenograft and isograft models of postpartum breast cancer increased tumor associated lymphatic vessel density was observed. Here, we evaluated postpartum lymphangiogenesis in an additional immune competent model of postpartum breast cancer. Further, the lab’s previous results indicated that pro-lymphangiogenic molecule Semaphorin 7a (Sem7a) is upregulated in postpartum tumors. Thus, we evaluated the expression and function of Sem7a to determine if Sem7a contributes to lymphangiogenesis associated with postpartum tumors.
Funding Provided by: University of Colorado Cancer Center: Cancer Research Summer Fellowship

A Protein Complex Directs Assembly of the Vitelline Layer of the C. elegans Eggshell

Diana Partida (2014); Mentor(s): Sara Olson

Abstract withheld upon request
Funding Provided by: Sherman Fairchild Foundation; Pomona College Department of Biology

The Role of Lipid Droplets in Early Embryonic Development in C. elegans

Brian Wysolmerski (2014); Mentor(s): Sara Olson

Abstract withheld upon request
Funding Provided by: Sherman Fairchild Foundation

Activation of Neutrophil-like Cells by Zymosan

Alyssa Cook (2016); Student Collaborator(s): Lorraine Beck (2014); Mentor(s): Melissa Petreaca

Abstract: Neutrophils are critical for the innate immune response, and play a central role in inflammatory disorders. This study investigates the ability of a fungal cell wall component, zymosan A, to activate neutrophil-like HL-60 cells. These cells were treated with zymosan A or with a positive control, phorbol myristic acid (PMA). Cell death and cell release of myeloperoxidase (MPO), a component of neutrophil primary granules, were used as indicators of activation. Cell death was determined using trypan blue exclusion, and release of MPO was determined via enzyme assays of cell extracts and supernatants. MPO assay results were normalized to total and living cell numbers. Both PMA and zymosan increased cell death and MPO release from cells, suggesting that zymosan A, like PMA, can activate neutrophil-like HL-60 cells.
Funding Provided by: Pomona College SURP (AC); Fletcher Jones Foundation (LB)

Effect of Aspirin Exposure on Migration and Survival of Breast Cancer Cells

Katherine Taylor Fortson (2016); Mentor(s): Melissa Petreaca

Abstract: Chronic inflammation is commonly treated with aspirin and other NSAID pain relievers, which target the cyclooxygenase (COX) enzymes. Due in part to the vast population of aspirin users, several studies have identified a relationship between regular aspirin use and a decreased risk of invasive and metastatic cancers. We investigated the effect of aspirin treatment on the survival and migration of a metastatic breast cancer cell line, M DA-MB-231. Under our conditions (0, 5, and 10 mM aspirin active ingredient, acetylsalicylic acid), aspirin had little effect on cell survival, but significantly inhibited cell migration. Our results suggest that aspirin use may also decrease cancer cell migration in vivo, providing one possible mechanism for its inhibitory effect on cancer invasion and metastasis.
Funding Provided by: Pomona College SURP

Evaluating a new method of modeling plant populations using data for a rare California plant

Eric Pasewark (2015); Mentor(s): Diane Thomson

Abstract: Matrix models have long been the standard for modeling plant populations. In the past decade a new method, called the Integral Projection Model, has emerged that promises to give a more accurate model based on the same data that the standard matrix models use. Both of these models assume that individual plant survival and their offspring are related to some continuous parameter such as size. Matrix models split the plant data into a few size classes, and calculate survival and fertility rates for these classes while the Integral Projection Model represents survival and fertility rates as continuous functions of size, which should represent the data more accurately. Few studies have analyzed the differences of these models on real data. I have been building the Integral Projection Model for population data on the Oenothera deltiodes, which is an endangered California plant whose population has been in decline for the past few decades. A previous paper supplies a matrix model for the data, which I will compare to the Integral Projection Model.
Funding Provided by: Howard Hughes Medical Institute

The Distribution of Tardigrade and Rotifer Species on Mt. Baldy and their Rates of Accumulation of Molecular Desiccation Protectants

Parth Patel (2015); Mentor(s): Jonathan Wright; Charles Taylor

Abstract: Tardigrades and rotifers both have the ability to enter cryptobiosis—a reversible state of suspended animation in which an organism is able to survive with minimal metabolic activity. In this state, cryptobiotic organisms can withstand various extreme climate conditions and survive for extended periods of time without any outside food or water. Initially, I collected local tardigrade and rotifers species and investigated the distribution patterns of tardigrades along a vertical transect of Mount Baldy. Particular importance was placed on species characterization and variance among different, indigenous lichen and moss communities. Tardigrades from four different genera were found in the study—Hypsibius, Milnesium, Macrobiotus, and Echiniscus. There did not appear to be any correlation between elevation and tardigrade species. Currently, I am using LC-MS to detect the presence and rate of accumulation of any molecular desiccation protectants in the collected tardigrade and rotifer samples. In order to run the animal samples through the LC-MS, I am first desiccating the animals in controlled humdities using saturated potassium nitrate solutions. Next, I pestle and sonicate the animals and use a centrifuge to concentrate the sugars and lighter molecules in the sample’s supernatant. Ultimately, I will compare the accumulation of these molecular protectants in the rotifers and tardigrade species against the elevation and microenvironment in which the species were found.
Funding Provided by: Paul K. Richter and Evelyn E. Cook Richter Memorial Fund; Pomona College Department of Biology

Exceptional Locomotory Performance in Paratarsotomus macropalpis Mites

Maria Young (2016); Student Collaborator(s): Yoni Rubin (2015 PIT); Mentor(s): Jonathan Wright; Anna Ahn; Dwight Whitaker

Abstract: Arachnids can achieve remarkably high velocities and extreme maneuverability, making them beneficial to biomechanical analysis of muscle utility and kinematic modeling. The local endemic mite species, Paratarsotomus macropalpis, was filmed using a Red Lake high frame-rate video camera in both the field and lab to analyze speed, stride frequency and gait changes during acceleration, deceleration and turning. Mites running in the field on concrete substrates at high temperatures (40°C to 60°C) were shown to travel at mean relative speed of 192.4 bl s−1 (body lengths per second), exceeding highest currently documented value for land animals (171 bl s−1) achieved by an Australian tiger beetle (Cicindella eburneola). Despite this exceptional value, it is consistent with interspecific scaling of relative speed as a function of body mass. The mites maintained exceptionally high stride frequencies (as fast as 135 Hz), which increased significantly with substrate temperature. Calculations showed that air resistance was not sufficient to explain measured deceleration. Although mites accelerate and decelerate extremely rapidly (on average 7.2 ms−2 and −10.1 ms−2, respectively), the forces involved are comparable to those found in other running animals. We recorded higher resolution lab footage of mites starting, stopping and turning to analyze gait and kinematic mechanisms. During normal running, adjacent and opposite tarsi are 180 degrees out of phase. This gait cycle is preserved during turning, although the two front pairs of tarsi initiate acceleration cycles and duty factors increase for inner tarsi during turns.
Funding Provided by: Howard Hughes Medical Institute

Research at Pomona