- 1922-1923 (x)
- Department of Biology (x)
- Search results
Search results
Show moreThe diet of zoo-housed animals has significant implications to many aspects of each species’ health and survival. A recent study revealed the diet of free-ranging Matschie’s tree kangaroos (Dendrolagus matschiei) to be mostly browse-focused, including plants like leaves, ferns, and orchids. Prior to those findings, zoo-housed tree kangaroos were fed diets, mostly biscuit-based, that differ vastly from that of free-ranging tree kangaroos possibly contributing to widespread issues within zoos concerning obesity and low reproductive success. The Cleveland Metroparks Zoo (CMZ) houses two Matschie’s tree kangaroos which, in 2019, underwent a significant diet change from a more traditional, baseline, biscuit-heavy diet to one that is more leaf or ‘browse’-heavy to better reflect that of free-ranging tree kangaroos. Therefore, we are currently investigating how the behavior of zoo-housed tree kangaroos change after this diet shift. Baseline behavioral data was recorded at CMZ from December 2017 to November 2018 on the female tree kangaroo prior to implementing the new diet and behavioral data is currently being collected on the same female as well as the male tree kangaroo housed at CMZ after the new diet. Behavioral observations were made instantaneously at thirty second intervals for a period of twenty minutes using ZooMonitor from video recordings captured with the Annke camera system. Using a G-test, our preliminary results show that the female tree kangaroo’s activity budget differed significantly between the baseline and browse-heavy periods (G=446.9 ; p <0.001 ). With these results, we found that she doubled her time spent feeding during the browse-heavy period, with 8.0% of her time spent feeding during the baseline and 16.0% of her time spent feeding during the browse-heavy period. In addition, we found that the male tree kangaroo spent 11.4% of his time feeding during the browse-heavy period. These results suggest that a transition to a browse-heavy diet to better reflect free-ranging tree kangaroo diets can increase the time spent engaging in natural feeding behaviors for zoo-housed tree kangaroos. Future parts of this study will examine how the diet shift contributes to tree kangaroo energy expenditure, nutrient intake patterns, and reproductive endocrinology.
Show less
Show moreThe incurable and devastating disease of age-related hearing loss (ARHL) affects a majority of the elderly worldwide. As humans age, their cells of the inner ear, which are responsible for hearing, undergo degenerative aging, as well as apoptosis (programmed cell death). Scientists believe that ARHL may be associated with specific cell types of the inner ear known to be high in mitochondrial concentration. These sensorineural tissues as well as the specific neurons, namely hair cells, spiral ganglion neurons, and cells of stria vascularis, are susceptible to irreversible cellular damage. A decline of mitochondrial function is common in various age-dependent neurodegenerative diseases. Mitochondrial health is tightly regulated by Ca2+signals, which plays an important role in ARHL. Calcium and other cations enters via mechanotransduction channels when a sound from the outside environment comes in the inner ear that cause the hair cell bundles to deflect to one side with sound frequencies. Thus, the goal of this study was to reveal the intrinsic mechanisms that relate to energy metabolism and cellular calcium balance genes expression levels in the mammalian inner ear from early development. Changes in expression of energy metabolism genes in the inner ear cells were examined in mouse models, comparing these gene expression profiles in mice ranging from embryonic day 16 to adult age of up to 4 months. Mouse models are widely used to study mammalian hearing and comprehensive databases are available. Here, databases were used to compare with preliminary data that was obtained in Dr. Ruben Stepanyan’s laboratory that had indicated the expression of mitochondrial metabolism genes can alter with age, possible affecting hearing. Once this data was obtained, it was compared on a spreadsheet and graphed using Excel. The following graphs of expression levels were made: fluorescence activated cell sorting (FACS) of all genes studied, spiral and vestibular ganglion neurons, inner and outer hair cells, and fluorescence activated cell sorting (FACS) of all the individual genes. In doing so, we were able to identify mitochondrial metabolism and cellular calcium balance-related genes that can undergo changes in expression levels in the mammalian inner ear, thus providing their importance in hearing.
Show less
Show moreMeiosis is an important mechanism that generates genetic variation for sexually reproducing organisms through recombination. In order for an organism to successfully propagate its genetic material from one generation to the next, its genome must be properly delivered as gametes. Meiotic crossing over of DNA ensures proper homolog segregation by repairing programmed double-stranded breaks. Meiotic defects caused by chromosome structural variants are detrimental to reproduction. During the interchromosomal effect, heterozygous inversions suppress crossing over between affected chromosomes while increasing crossing over between normal chromosome pairs. These defects in chromosomal dynamics trigger the pachytene checkpoint, leading to a delay in prophase progression. It has been suggested that this delay in prophase causes the interchromosomal effect on recombination. However, whether the interchromosomal effect on crossing over is caused directly by defects in chromosome dynamics or indirectly by the delay in prophase remains unclear. We are distinguishing between these two hypotheses by investigating the distributions and frequencies of crossovers in Drosophila mutants when prophase is extended by utilizing maelstrom mutants that trigger the pachytene checkpoint independently of chromosome defects. We are analyzing the changes in crossover distribution and frequencies in these mutants using recessive markers on unaffected chromosome. We are also collecting confocal imaging data of the mutants’ germarium to visualize the effects of maelstrom mutations on meiosis. Our data will provide insights into the mechanisms of the interchromosomal effect and reveal whether or not the interchromosomal effect is directly mediated by a delay in pachytene or, alternatively, mediated by disrupted crossover control mechanisms.
Show less
Show moreMicrobial communities play a key role in shaping many diverse ecosystems through their biogeochemical contributions. These communities comprise not only bacteria and archaea but also their viruses, whose reproduction profoundly affects host cell biology. While many bacterial species have been well characterized, the challenges of isolation and sequencing have hampered the study of environmental viruses such as bacteriophages. The model organism Azotobacter vinelandii is a common nitrogen-fixing soil bacterium. To our knowledge, no Azotobacter phages currently exist in culture. However, modern bioinformatic and database approaches can be used to identify the metagenomic sequences that may derive from bacteriophages that infect Azotobacter. We have developed a pipeline that scans metagenomic samples from the IMG JGI database to identify phage sequences whose abundance co-varies with Azotobacter vinelandii abundance. The viral sequences identified can be grouped into clusters, and the resulting clusters can then be analyzed for auxiliary metabolic genes (AMGs). These candidate sequences may then be used to guide phage isolation strategies and predict phage ecological impact.
Show less
Show moreAs a result of recent climate change, many species are rapidly altering their geographic ranges, in a phenomenon known as range shifting. In general, the shifts tend to be geographically poleward or upslope, but there is a lot of variation in the magnitude or direction of contemporary range shifts. Theory suggests that specialization might constrain range shift responses. In this experiment, we examined the relationship between the magnitude and direction of range shift responses and degree of diet specialization of Ohio butterfly larvae. We used a long-term monitoring dataset of butterfly range dynamics to test this relationship. Surprisingly, we did not find any association between the range shift responses and the dietary specialization, after accounting for the shared evolutionary history among species. In future work, different methods of quantifying diet breadth may reveal an association. Further research in the same area will be focused on finding other traits that may be predictive of range shifts.
Show less
Show moreTryptophan is a fluorescent amino acid that is commonly used as a probe in protein structure-dynamics studies. It is also widely used as a convenient standard for measurements of fluorescence quantum yields of organic and bioorganic molecules. Literature values of the fluorescence quantum yield range from 0.13 to 0.15 upon excitation of tryptophan at 270 nm in aqueous solution. Even though the fluorescence quantum yield of tryptophan is known with a high degree of accuracy upon excitation at 270 nm (i.e., ca. ± 0.02), this value is being used indiscriminately in the literature for the determination of the fluorescence quantum yield of molecules at other excitation wavelengths. In those studies, the assumption has been made that the magnitude of the fluorescence quantum yield of tryptophan does not change with excitation wavelength. This assumption is based on the so-called Kasha’s rule, which states that fluorescence emission occurs in appreciable yield only from the lowest excited singlet state of an organic molecule. Consequently, the fluorescence quantum yield is typically independent of the excitation wavelength used. However, many molecules are known to not obey the Kasha’s rule. Therefore, in this study, we examine the hypothesis that the fluorescence quantum yield of tryptophan does not depend on the excitation wavelength used. We also investigate if the fluorescence quantum yield of tryptophan varies when the salt concentration of the phosphate buffer solution at a physiological pH of 7.4 is varied. The results demonstrate that the fluorescence quantum yield of tryptophan depends on excitation wavelength. It is, however, independent of the ionic strength of the buffered solution in a salt concentration range from 5 to 100 millimolar. A photophysical relaxation mechanism that satisfactorily explains the excitation wavelength dependence of the fluorescence quantum yield of tryptophan will be presented.
Show less
Show moreThe marine mollusk Aplysia californica is an important model organism for neuroscience research. In laboratory aquaria, animal waste may accumulate and harm animals unless water is replaced frequently. To keep animals healthy for longer, we have designed a marine environment that replicates the natural nitrogen cycle. Our animals’ holding tanks have two compartments: a main compartment for animals and a refugium for macroalgae. We are studying whether ammonia and nitrate derived from animal waste cause illness in Aplysia, and whether macroalgae can sequester nitrates and reverse illness. We measured increases in nitrate and ammonia in the absence of macroalgae. We also tracked markers of poor health in animals as waste products increased. We hypothesized that macroalgae sequesters nitrates, and the accumulation of nitrate can lead to health problems of Aplysia.
Show less
Show moreAfter a thorough literature search and through experience at adaptive sports events, we identified a lack of established guidelines for Sport-related concussion (SRC) evaluation and management in wheelchair athletes. Wheelchair athletes are a unique population, and certain conventional methods of evaluating SRC in able-bodied sports cannot be used. For example, wheelchair athletes’ underlying disabilities restrict the use of standard balance testing protocols. In addition, some wheelchair athletes have concurrent traumatic brain injuries and may have baseline cognitive deficits associated with their disability that mimic the symptoms of a concussion. This research focused on discussing current concussion management guidelines in Adaptive Sports and formulating a new Concussion Management Protocol (CMP). We developed a CMP that incorporated the Wheelchair Error Scoring System (WESS), a seated balance test based on the Balance Error Scoring System to evaluate ataxia. We collected baseline data on wheelchair athletes that included a concussion history, symptoms, Standardized Assessment of Concussion and WESS. Baseline data was collected at 39th National Veterans Wheelchair Games (NVWG) where 81 athletes were asked to complete all aspects of the baseline exam. Out of the 76 patients who tried the WESS, only 28 could complete the full test. Those who were unable to perform the WESS had limitations with the wheelie balance task which led to the adaptation to an alternative test, the King-Devick. We also discovered that 43% of the athletes reported a history of a concussion.
Show less