Biology

Antibiotic Resistance in Soil 

Jordan Ochoa
Lamar University

The evolution of antibiotic-resistant bacteria represents a pressing global crisis. The idea of not having treatment for an infection is quite frightening but is unfortunately a growing concern.  Antibiotic resistance occurs when bacteria develop mechanisms that allow them to survive exposure to antimicrobial drugs. The pool of available antibiotics is limited due to the stringent requirements for human compatibility, safety testing, and scalability of production. Because bacteria have short generational lifespans, genetic mutations and horizontal gene transfer occur with high frequency, enabling newer bacterial generations to resist antibiotic treatments. This is a study focused on the survey of antibiotic-resistant bacteria (ARB) within the soil of industrialized areas of Southeast Texas. The research will focus on identifying the prevalence of antibiotic resistance genes (ARGs) from soil samples. Methods include serial dilution of the soil, culturing the bacteria in presence of antibiotics, isolating the DNA from bacteria growing in presence of antibiotics such as gentamicin, tetracycline, penicillin, rifampicin, and polymyxin B, and molecular screening for antibiotic resistant genes. So far, results have shown consistent resistance of the antibiotics tetracycline and penicillin from most soil samples. As this research is ongoing, we hope to identify ARGs in the samples that are being tested. Results will enhance understanding of environmental reservoirs of resistance and may reveal antibiotic-resistant bacteria. Closing the gaps in knowledge about antibiotic resistance is critical for global public health. In particular, the soil and water ecosystems of Southeast Texas may harbor untapped potential for identifying resistance genes that could overall contribute to future therapeutic solutions.

Comparative Preservation of Mitochondrial and Nuclear DNA in Soft and Keratinized Tissues: A Model for Cold-Case Forensic Investigations

Isabella Arroyo
Our Lady of the Lake University

DNA is one of the most valuable forms of forensic evidence, allowing investigators to identify individuals and establish connections between biological evidence and crime scenes. However, in cold cases involving prolonged decomposition, DNA degradation can significantly reduce the quality and quantity of genetic material available for analysis. Understanding which tissue types and genetic markers best preserve DNA during decomposition may improve forensic DNA recovery from degraded remains. This study compares DNA preservation in soft tissue (muscle) and keratinized tissue (claws/hooves) throughout decomposition while evaluating the stability of mitochondrial DNA (mtDNA) and nuclear DNA (nDNA) over time. Model tissues from chicken feet, mouse feet, and pig hooves are being used to simulate tissue types commonly encountered in forensic investigations. By comparing DNA recovery from both tissue types and genetic targets, this study aims to identify the combination most likely to yield successful DNA analysis under simulated cold-case conditions. The first phase focused on developing and optimizing a customized DNA extraction protocol to maximize DNA yield and quality from each tissue type. Following optimization, DNA samples will be collected at multiple stages of decomposition and analyzed using the DeNovix DS-11 FX spectrophotometer/fluorometer to assess DNA concentration and purity. Quantitative PCR (qPCR) will then be performed using mitochondrial gene targets (ND5 and CYTB) and nuclear gene targets (Histone H4 and KRT14/KRT75L3) to compare amplification success across tissue types and decomposition stages. The findings will improve understanding of DNA preservation in decomposed tissues and provide insight into the resilience of mitochondrial and nuclear DNA during decomposition, helping improve forensic DNA recovery strategies and human identification in cold-case investigations involving degraded biological evidence.

If You Give a Fish a Treadmill: Does Fry Size Determine Swimming Ability?

Jupiter Chaudron
California State University, Sacramento

The goal of this research was to investigate if the size of fish fry determined their swimming ability, which provides insightful knowledge on the trade offs that can occur regarding the reproduction of cichlids. I hypothesized that larger fry would exhibit a better swimming ability than their smaller counter parts, which is an idea that has been explored only in larger fish, not fry. For this experiment, cichlid fry (or: recently hatched juveniles) were used. Thirty convict cichlid (Amatitlania nigrofasciata) fry were sourced from the California State University Sacramento Evolutionary Ecology of Fishes lab, and their swimming ability was measured using a 3D designed and printed swim tunnel. A water current was simulated using a remote control water pump, which could increase in speed. Each fry was placed into the swim tunnel, with the speed increasing every thirty seconds if they were still swimming once the current sped up. The results of this experiment were that larger fry consistently make it to a higher speed than smaller fry, which supports my hypothesis and provides valuable insight into the biological compromises involved with cichlid reproductive behavior, while also complementing the present work on the subject. This study was able to extend the current knowledge on the topic of fish body size and swimming ability by applying it to very small fish, which fills a gap in the current research. Future research could go more in depth on this topic, exploring how morphology plays a role in a fry’s swimming ability.