Effects of Research Disturbance Levels on 5-Day-Old
Black-Legged Kittiwake Chicks

The ability to closely monitor and manipulate marked populations of seabirds is invaluable for ecological research and conservation efforts. A reconfigured radar tower on Middleton Island, Alaska provides accessible semi-artificial nesting sites for black-legged kittiwakes (Rissa tridactyla). However, long-term researcher disturbance may affect seabird physiology, as disturbed and undisturbed birds may not be directly comparable in studies. We tested effects of researcher disturbance on kittiwake chicks by categorizing disturbance levels as “high”, “medium”, and “low” based on researcher activities at 3 locations. A subset of the high disturbance birds were supplementally fed (whole fish ad libitum 3x/day). A (N=77) and B (N=77) chicks were measured after being bled in <3min when the A chick was 5 days old. Regurgitation was noted if produced during measurements. Whole-blood glucose and ketones were measured with handheld point-of-care (POC) meters; glucose was further measured with plasma in the lab. Despite being validated in adult kittiwakes, glucose values of the chicks from handheld meters did not show good concordance with lab-measured glucose (R2=0.08). Red blood cells were used for genetic sexing in the lab.
Disturbance levels significantly impacted body condition in low and high-unfed A chicks, but there was no significant difference between that of low and high-fed A chicks. Blood metabolites do not reflect body condition or disturbance category. Chicks of the low disturbance area regurgitated significantly more than the chicks of any other disturbance category.

Heading for a breakdown: Assessing evolution through the hybridization of two sexual systems

Hybridization is an important evolutionary pathway that has contributed to the world’s vast biodiversity. In plants, hybridization is known to be an important mechanism for speciation, phenotypic divergence, and changes in reproductive systems. Solanum species present an ideal system to investigate how hybridization between two different sexual systems impacts the reproductive and phenotypic biology of the hybrid progeny. Hybrids were acquired from crosses between Australian species Solanum dioicum (dioecious) and S. ultraspinosum (andromonoecious). The only successful hybrids from the original crosses were those derived from S. diocium as the pollen donor and S. ultraspinosum as the pollen recipient. Due to strong maternal effects, all the F1 hybrids resembled S. ultraspinosum, so all F1 plants were andromonoecious. To assess phenotypic differences between the hybrids and their parents, I collected morphometric data and used ImageJ software. A series of statistical analyses were done using R. A principal component analysis confirmed that the hybrids were distinct from both parents, but were most similar to S. ultraspinosum. The F2 hybrids appear to demonstrate variability in inflorescence architecture, which may be suggestive of a change in sexual system, although further analysis is needed. In attempts to create an F3 hybrid generation, nearly all of our crosses have failed—suggesting that a hybrid breakdown is occurring. To determine where the breakdown is occurring, I will be employing a technique using fluorescent microscopy. Overall, my study will promote a better understanding of hybridization—a driving force of plant speciation—which has broad impacts for the long-term viability of plant species.

Size Variation and Morphometric Analysis of Freshwater Mussels (Elliptio complanata) in the Susquehanna River

Freshwater mussels are a vastly understudied group of animals, and as a result, basic life history characteristics are unknown for many species. In some species, gravid females display a deceptive lure made from part of their mantle, but unless the female is displaying the lure, it is difficult to quickly and accurately determine the sex of mussels based on their external morphology. As a result, local mussel populations have hidden sex ratios, making estimates of population growth difficult. Using live Eastern elliptio mussels (Elliptio complanata) from the Susquehanna River and the Buffalo Creek, we sought to determine if there is a predictive relationship between sex and shape. Samples of gonadal fluid were extracted from the visceral mass to determine the sex of each individual. These data were then connected to three measurements of the corresponding shell: length, width, and depth (girth). No sexual dimorphism was present using these simple measurements. However, in a subset of the population sampled, further morphometric analyses of shape from digitized photographs of the animals revealed differences between the sexes, displaying a level of dimorphism previously unknown in this species. Determining the sex of live individuals has important implications for future studies of mussel biology, including answering questions related to mussel reproduction, demography, and population distribution.

Surface Roughness Analysis as Relative Dating Technique

When moraines degrade, two distinct changes in their morphology occur: 1) weathering
of boulders on the moraine surface leads to fewer and smaller boulders over time; 2)
initially sharp crests of the moraine become gentle over time as erosion transports
material downhill. These two attributes of moraines, surface roughness and the
sharpness of the crest, are important parameters to characterize the evolution of
glaciated landscapes but they have not been quantified. We established two metrics to
quantify these attributes of moraine morphology using high-resolution elevation data
and compared them against publicly available cosmogenic ages. The surface
roughness of the moraines is proportional to the number and size of the boulders, and
we quantified it by calculating the standard deviation of slope determined from 1-m
LiDAR data. For example, each boulder on the moraine surface produces local slope,
and a large number of boulders on a young moraine should lead to a high variability of
slopes, measured in degrees. Second, we quantified the sharpness of moraine crests
by measuring the maximum curvature along crest-perpendicular transects. Young
moraines tend to have sharp crests resulting in high values of the maximum curvature,
compared to gentle crests of old moraines with low curvature values. We analyzed only
the surfaces of well-dated lateral moraines with five or more cosmogenic ages per
moraine. Preliminary results show a weak negative temporal correlation in the surface
roughness and the sharpness of the moraine crests. However, the correlation is more
apparent at 100,000-yr scale than at 10,000-yr scale, probably because most of the
moraines date to ~16–22 ka. The correlation between these morphologic metrics and
age can be improved by analyzing older moraines from a variety of climate conditions.
This new relative dating technique can be used for mapping glacial landscapes in other
planets, such as Mars.

Identification of Novel Microorganisms and Nitrogen Fixing Organisms in Central Pennsylvania

In this project we sought to identify novel organisms from various locations throughout the Bucknell Natural Area. Bacteria were isolated on minimal media (lacking ammonia and nitrate) supplemented with a small amount of yeast extract and sucrose or mannitol. After repeated quadrant streaking, two novel microorganisms were isolated. PCR amplification of the 16S rRNA gene followed by sequencing of the PCR product indicates that one is of the Pantoea genus and the other of the Paenibacillus genus. Once the organisms were isolated, metabolic analyses were conducted using the BIOLOG GenIII plates. We will present the metabolic analysis as well as the results of annotating the genomes of these two organisms. In a second part of this experiment, the community characteristics of the soil samples were assessed using BIOLOG Ecoplates and community DNA was used to assess nitrogen fixing capability by PCR amplification using the nifK and nifH genes.

Exploring How Life History Affects Stress Responses
When an organism encounters a stressful stimulus, the endocrine system activates a physiological stress response through a cascade of hormone signaling, which functions to promote short-term survival by mobilizing and reallocating energy. In vertebrates, glucocorticoids (GCs) are released during the stress response. However, vertebrates vary greatly in their life histories, which in turn may require differentially regulated stress responses. Vertebrate species fall along a continuum of slow to fast life histories. Those with slow life histories tend to have slower growth rates, later maturation, larger size, fewer offspring, and longer lifespans. Alternatively, those with fast life histories tend to have faster growth rates, earlier maturation, smaller size, more offspring, and shorter lifespans. Although quail are classified as having faster life histories compared to other vertebrates, there is still ample variation among quail species. We are developing a comparative quail model to investigate whether stress responses differ based on where a specific quail species falls on the life history continuum. Specifically, we categorized how stress responses differ using three distinct measures. We predict that species with slow life histories will be able to turn off a stress response more rapidly compared to species with fast life histories. Our initial results show that the Blue Scale quail (fast life history) actually recovered more quickly from stressors, in comparison to Chinese Button quail (slow life history). I will discuss interpretations and implications of these results in further detail.

Effect of Tillage Radish on Mycorrhizal Density in a Regenerative Agriculture System

Traditional agriculture has become dependent on industrial methods, using heavy machines, fossil fuels and synthetic chemicals. However, due to the harm of these methods, a growing movement of regenerative agriculture is emerging. This approach takes advantage of the natural tendencies of organisms in the ecosystem to grow abundant nutritious crops, without the negative effects. The Bucknell Farm follows such a practice, with two main principles being no-till, and the usage of cover crops. Manual tilling in industrial farms loosen the soil to prep for the planting season but have also been shown to induce soil erosion. Cover crops are used to build organic matter, and to retain water in the fields. By planting non-harvested crops during the off-season, these plants help prevent nutrient and water losses. A common cover crop used is the tillage radish, which grows long roots that loosen the soil allowing subsequent crops to develop deeper root systems while using less energy. However, as a member of the Brassicaceae, tillage radish releases chemicals, isothiocyanates, that are known to inhibit the growth of mycorrhizae fungi. These fungi are known to be beneficial in farms, helping crops with water absorption and nutrient collection. Our research looks into whether the tillage radish affects mycorrhizal propagule count in the subsequent growing season. Using the Most Probable Number method (MPN) we investigate if the tillage radish reduces the mycorrhizae populations and if this reduction can be detrimental to the subsequent crop seen by reduced nutrient content.

Kalman Symposium 2022 – Michaela Bracken

Synthesis of Fluorinated Fatty Acids for Use in Iron Oxide Nanoparticle Formation

Iron oxide nanoparticles are useful in several applications including imaging as contrast agents for MRI’s, drug carrier delivery for target specific sites and other biological therapeutic agents. Basic iron carboxylates of fatty acids can be used as precursors to nanoparticles. These complexes are important to study so that applications of iron oxide nanoparticles can be improved and built upon. If they contain a fluorine atom, basic iron carboxylates can be studied using 19F NMR to examine the structure and aggregation of these nanoparticle precursors. To accomplish this goal, fatty acids with a fluorine marker must be synthesized, due to their commercial unavailability. Our approach focused on an SN2-like fluorination of hydroxy fatty acids using XtalFluor-E. Sodium-12-fluorostearate was synthesized as an initial target from 12-hydroxystearic acid. This molecule was easily prepared but fell short of success due to the marker being too far away from the iron aggregation site. The position of the marker in the ligand is important and determines how well the activity can be monitored by NMR when reacted with iron. A second ligand, 6-hydroxy heptadecanoic acid, is being created that uses bromovaleric acid as the starting material. This synthesis, which is currently in progress, will require additional steps but will put the fluorine marker closer to iron to give a better read of the aggregation activity at the iron center.

Measuring Concordance of Sulcogyral Patterns in Monozygotic and Dizygotic Twin Pairs

The brain’s surface is made up of sulci (grooves) and gyri (ridges) that together create the distinct folded (sulcogyral) appearance of the brain. Sulcogyral folding patterns have been identified in the orbitofrontal cortex (OFC) based on the continuity of the medial and lateral orbital sulci (MOS & LOS). Pattern types are named according to their frequency in the neurotypical population, with Type I present in ~50%, Type II in ~30%, Type III in ~15%, and Type IV in ~5%. It has been previously found that populations with schizophrenia have reduced frequency of Type I patterns, but the heritability of the OFC sulcogyral patterns is unknown.
The goal of this project was to explore whether OFC patterns are heritable. We examined whether there is increased concordance of patterns in 172 monozygotic (MZ) twins relative to 304 dizygotic (DZ) twins using structural magnetic resonance imaging data. We also characterized pattern subtypes to explore variance within OFC sulci that is not based on MOS and LOS continuity.
We find no difference in concordance rates between MZ and DZ twin pairs. Results from subtype analysis suggest that variability exists in other sulci that are not captured in overall OFC pattern characterization. This suggests subtyping may be important for future studies to further understand the relationships between pattern types and subtypes. Overall, these results suggest minimal genetic influence on OFC pattern types, indicating that OFC sulcogyral patterns may capture important variance that is not genetic in origin but is relevant to psychiatric disease risk.

INFLUENCE OF MATERNAL SEPARATION ON STRESS & ALCOHOL REWARD: CONTRIBUTIONS OF B-ENDORPHIN

Adverse childhood experiences affect over half of the population. and are associated with chronic health problems, mental illness, and substance misuse in adulthood. The opioid peptide β-endorphin regulates the stress response and has been implicated in the risk for excessive alcohol consumption. Clinical research has demonstrated that initial sensitivity to the rewarding effects of alcohol is associated with stress sensitivity and predicts the risk of developing an alcohol use disorder. Here, we explored the influence of β-endorphin on changes induced by maternal separation in open field activity, [as well as the initial rewarding effects of alcohol], using control C57BL/6J and β-endorphin deficient B6.129S2-Pomc tm1Low /J; KO mice. Maternal separation (MS) occurred for three hours each day from postnatal days (PND) 5-18. Maternal interactions did not differ between genotypes, but were influenced by the separation protocol. MS and control subjects were tested as adolescents (PND-26 to 32) or adults (PND-58 to 72). Anxiety was assessed using an open field assay, [followed by a single-exposure conditioned-place preference paradigm to measure alcohol reward].  The effects of maternal separation, early stress, on anxiety and alcohol reward are age and B-endorphin dependent.