bluuebunny/crossref_metadata_2025 huggingface dataset:
Ontogeny of Enamel Thickness in the Teeth of Alligator and its Significance for Crocodyliform Dental Evolution
Authors: Schmiegelow Amy Brianne , Sellers Kaleb C , Holliday Casey M
Published: November 2023

Enamel is a key dental tissue responsible for mediating forces that are incurred through biting and feeding. Thus, disparity in enamel thickness among individual teeth as well as among species should provide important information on diet and feeding behavior. Crocodylians, including Alligator mississippiensis, evolved the highest bite forces among vertebrates, and thus their teeth likely also have adaptions to accommodate these extreme behaviors and loads. However, little is known about the ontogenetic and phylogenetic patterns of enamel thicknesses in the teeth of alligators, crocodyliforms and other sauropsids. Positional and ontogenetic changes in enamel thickness in alligators may reflect feeding ecology, as thicker enamel may be needed to resist higher bite forces. Moreover, craniodental diversity among extinct crocodyliforms suggests that enamel thickness may offer key ecomorphological insights into their evolution. Teeth and alveoli from three mandibular positions were sampled from an ontogenetic series of alligators and microCT scanned. Slice data and 3D models were used to measure the enamel thickness, enamel and dentin volume, and surface area of the enamel‐dentin junction. These data were complemented by a sample of molariform teeth from fossil crocodyliforms including the durophagous, Late Cretaceous alligatoroid Brachychampsa, its early Cenozoic relative Allognathosuchus, the herbivorous, Late Cretaceous Iharkutosuchus and several early Jurassic protosuchian taxa in order to assess variation and potential for ecological signal in the clade. We found that the most anterior teeth maintain the thinnest enamel compared to middle and posterior (molariform) positions throughout alligator ontogeny. Enamel thickness in all teeth scaled with isometry throughout alligator ontogeny. Comparisons of the molars of fossil crocodyliforms with those from alligators reveal a diversity of enamel thickness and complexity, suggesting phylogenetic as well as ecological signals may be impacting tooth structure, function, and evolution, warranting further investigation into the system.

Support or Funding Information

This work was funded by the Missouri Research Board, Life Sciences Undergraduate Research Opportunities Program, and the Biology Honors Program.
Differential Lectin Binding and Coronary Angiography in a Danio and non‐Model Fish Species
Authors: He Wei , Manalo Trina , May Adam , Quinn Joshua , Lafontant Pascal J
Published: November 2023

Lectins are carbohydrate‐binding proteins commonly used in the study of mammalian cells and tissues. However lectins have received little use in fish models and non‐models species. Here, we determine the binding patterns of commonly used lectins, including wheat germ agglutinin (WGA), Ulex europaeus agglutinin (UEA lectin), Bandeiraea simplicifolia lectin (BS lectin), Concanavalin A (Con A), Ricinus communis (RCA), and Lycopersicon esculentum lectin (tomato lectin) in zebrafish and giant danio hearts. Our results show that WGA stained fish cardiac myocyte borders in patterns similar to that seen in mammalian hearts, with staining markedly stronger in the fish compact hearts. Con A showed broad and strong staining in fish ventricles. Interestingly, BS lectin reacted poorly to a number of fish species including zebrafish, pearl danio, common koi, goldfish, and Buenos Aires tetra. By contrast BS lectin strongly stained coronary vessels of giant danio, and several pleco and gourami species. Importantly, enhanced BS lectin binding to vascular endothelium compared to endocardium allowed for 3D coronary angiography in the giant danio by confocal and lightsheet microscopy, and for quantitation of vascular reconstruction during regeneration. In conclusion, our study demonstrates that lectins are simple but important tools for studies in models and non‐models fish species, and in adult and regenerating giant danio heart.

Support or Funding Information

R15 HD084262‐01, FDC‐PDF‐DePauw University
DEVELOPMENT OF A MULTIDISCIPLINARY CLINICAL CADAVER PROGRAM
Authors: Sandeski Robert Eric , Kovacs George
Published: November 2023

The traditional fixation techniques used in many university bequeathal programs has enabled students to learn the intricacies of the human form for decades. This process has served as a hands‐on means of learning human anatomy primarily used by undergraduate learners. Postgraduate and practicing clinicians however rarely accessed this resource until the development of the Clinical Cadaver Program at Dalhousie University. Their training and skill acquisition primarily occurs at the bedside of live patients and while important, may pose a patient safety risk. To address this issue, a proportion of the donated human cadaveric specimens within the established Human Donation Program are now being prepared using a modified light‐embalming technique developed by Dalhousie University. The Department of Medical Neuroscience is now able to prepare specimens that maintain their natural tissue integrity without the normal hardening and rigidity of tissues that occur with traditional cadaveric fixation techniques. The result is a safe, very realistic high fidelity form of simulation that allows clinical practice and research in performing medical procedures using the human body.

The program continues to grow as demand for access to specimens increases. It is now a recognized and critical component of an integrated provincial simulation program. Competency based learning is now a mandated educational movement in postgraduate medicine. This move requires learning opportunity exposure that in many instances are simply not available with enough frequency to ensure skill competence. The clinical cadaver program provides for safe practice in a controlled environment that will allow clinicians to attain and maintain procedural competence.
SUCCESSFUL SOFT CURE EMBALMING OF A WHOLE BODY CADAVER AFTER THREE YEARS IN A CRYOGENIC STATE
Authors: Heltzel Sara , Sochor Mark , Sikon Dana , Sikon Richard
Published: November 2023

INTRODUCTION

Step‐wise medical education has resulted in an increased demand for cadaveric tissue with extended retention times. Soft cure‐embalming, an alternative anatomical preservation technique, has been designed to meet the research and medical training needs of today's students. The soft cure‐embalming (SCE) technique accomplishes a realistic tissue feel without rapid biological breakdown, thus maximizing retention and educational use. The SCE technique proved successful for preserving and restoring cadaveric components (i.e., cephalus, upper and lower extremities) obtained from fresh frozen whole body cadavers.

HYPOTHESIS

Can the SCE technique be used to successfully preserve and restore an intact fresh frozen whole body cadaver that has been cryogenically suspended for 3+ years?

METHODS

A fresh tissue whole body cadaver received in January 2012 was maintained in a cryogenic state (0 – 10°F) for 3.25 years. In March 2015, the cadaver was thawed to room temperature and preserved using SCE fluid and standard embalming techniques (i.e., injection via the right common carotid artery). The cadaver was cured for ~4 weeks, after which time the stratum corneum epidermal layer was shed/removed.

RESULTS

The soft‐cure embalmed whole body cadaver had exceptional results for tissue penetration and soft cure‐fixation despite the prolonged time spent in a deep freeze. Ample tissue perfusion was noted upon external examination in both the distal upper and lower extremities and in the cephalus. Internal anatomical structures were also examined and proved to be remarkably preserved and revived by the SCE fluid. The cadaver was utilized for anatomical dissection and teaching of medical procedures. External and internal structures were deemed by course participants to have an extremely realistic tissue feel. The ability to “reanimate” a whole body cryogenically suspended for 3+ years via this process is unprecedented.

DISCUSSION

Soft cure‐embalming is extremely successful in preserving and restoring cadaveric tissue that has been previously frozen. The SCE technique significantly extends tissue retention time and educational utilization. The SCE tissue in this study was particularly well received by educators. Multiple educational sessions can be given utilizing same tissue, and it is possible to perform medical training in step‐wise fashion over several weeks utilizing the same cadaveric specimen.

FUTURE WORK

Varying cryogenic intervals preceding SCE technique implementation will be explored. Techniques for simulating blood flow and perfusion in soft‐cure embalmed tissues will be investigated.
Educational Outcomes of Implementing Prosected Hands and Feet as Educational Tools in a Traditionally Full Dissection Medical Gross Anatomy Laboratory
Authors: Williams Sutton Ross , Sinning Allan , Notebaert Andrew , Darling Ryan
Published: November 2023

The purpose of this study is to determine if replacing full dissection of hands and feet with the use of prosected hands and feet has effects on exam performance for first year medical students enrolled in medical gross anatomy. Comparisons examining the difference in performance on practical exam questions pertaining to the hands and feet dependent on how the students learned the structures were made between two academic years. The students enrolled in the course in 2014 learned these structures from active dissection while those enrolled in the course in 2015 learned these structures from prosected specimens. Within subjects comparisons were also made between the 2015 first year medical student's performance on practical exam questions based upon if they learned the structure via active dissection or through the use of prosected specimens. ANOVA tests were used to identify if student performance on practical exam questions demonstrated significant differences dependent on how students learned the structures. Initial analyses indicates that there is no statistical difference between class years in performance on practical exam questions. Additional analyses will examine the differences in performance on structures of the sole of the foot and the within subject comparisons upon completion of the course. Based upon the initial findings, these students do not appear to be at a disadvantage in exam performance based upon the method in which they learn hand structures.
The Use of a Checklist to Increase the Quality of Student Dissections in Medical Gross Anatomy Labs
Authors: Johnson Eric , Foster James
Published: November 2023

Medical students will often neglect the quality of cadaveric dissection in order to leave the Gross Anatomy lab early to pursue other activities. The resulting incomplete dissections contain significant amounts of connective tissue and skin which obscures visualization and identification of anatomical structures. To address this issue, the faculty at the Alabama College of Osteopathic Medicine (ACOM) developed a system to improve the quality of student dissections. To this end, we created a checklist that gives the anatomy faculty and fellows guidelines to assess the quality of each dissection. Each dissection group is checked off at the end of the lab and the students are required to remedy any deficiencies in the dissection that are noted in the checklist before the beginning of the next lab period. The students maintain a continuous lab report and points contributing to their grade in the course are given for the level of quality of each completed dissection as determined from the checklist. Since we began utilizing the checklists, the quality of the dissections has noticeably improved. We believe that one reason for the improvement is that the checklists provide a well‐defined endpoint that the students must reach. The checklists also allow the faculty and fellows to describe deficiencies in the dissection to help the students improve their dissection abilities and give a higher understanding of anatomical relationships.
Anatomical Education, Memory Consolidation and the Testing Effect
Authors: Easteal Ron Albert , Biddell Jason
Published: November 2023

As educators, anatomists must attempt to instill relevant Anatomical structures to the long‐term memory (LTM) of medical and professional students. Cognitive research tells us retrieval practice (RP) is twice as effective in accumulating LTM when compared to studying alone. RP is the recall of previously tested material by self or group testing. The increase in LTM is called the ‘testing effect’ (TE). RP is most effective when practiced a day or two after initial presentation, and repeated after intervals of a week or so.

While cognitive science examines the efficacy of RP, it fails to explain a neurological rationale for those counter‐intuitive events. There is recent neuroanatomical evidence that correlates the time‐delay of acquisition with transfer of memory between the hippocampus (HPC) and the Neo‐Cortex (NC). Anatomical educators and their students will be more confident in using this powerful learning tool if they understand the correlation between RP and LTM.

RP is sequenced through a series of retrieval practices following initial study/presentation (study‐RP‐RP‐RP etc.). The first interval may be a day or so, while the succeeding intervals may be evenly spaced or expanded throughout the course.

Memory has 4 stages: 1. Sensory memory; 2; Working memory (WM) 3; Hippocampal consolidation (HC); and 4; LTM in the neocortex. Stages 1 and 2 last around 20 seconds. HPC consolidation and its transfer to the NC can take from 1 day to 1 month, showing that this is a direct link to RP expanding over time.

HC consolidation incorporates both synaptic consolidation, and systems consolidation. Synaptic Consolidation is the strengthening and replication of synapses in the HPC and NC, making memory more robust. This process is called long‐term potentiation (LTP). Synaptic consolidation fades over time as system consolidation (SC) takes over. SC transfers representations from the HPC to the NC, thus strengthening inter‐cortical ‘crosstalk’ and stabilizing LTM.

One major contributor to SC is adult neurogenesis in the dentate gyrus of the HPC. Development and maturation of these new cells take place during 4 weeks, providing LTM connections to the neocortex. Another major potentiator of LTM is sleep following subject presentation. Thus, LTM facilitation is potentiated from day 2 to 1 month after presentation.

R.P (as opposed to studying), acts by reactivating the cortex and bringing the representations back to the WM. The WM reactivates consolidation, ultimately reinforcing memory in the neo‐cortex.

Support or Funding Information

N/A
Evaluation of Power Point Presentation Reflection Among Students of Applied Medical Sciences College, Najran University
Authors: MOKHTAR AHMED ELSIR , ELMUSTAFA SHAMAIL DAFALLA ABUIDREIS
Published: November 2023

Introduction

Power Point and Slideshow lectures and presentations are a popular teaching method in undergraduate medical and paramedical teaching and education. PowerPoint software offers a tremendous number of options for personalizing slides to provide an opportunity to enhance a presentation. The rise of the slide has generated considerable debate, with some people concerned that PowerPoint diminishes the potential of critical thinking by the audience, and others encouraging innovative graphic design as assisting the transmission of information.

Objectives

To assess the student's satisfaction regarding slideshow and power point based lectures and their perspective on teaching methods and evaluate preference and effectiveness in learning.

Methods

This is a descriptive cross‐sectional study was carried out among the undergraduate applied medical sciences (Physiotherapy and Radiology) students of Najran University participated voluntarily, during the period from Nov.2014 to Oct.2015; collected data analyzed by using Statistical Package for Social Sciences (SPSS Program).

Results

Showed that 52.63% of students believe that the most distracted factor in power point presentation is the large number of presenting slides 42.11% of the students considered that more than one topic that's presented in the presented slides, and slides color and themes comes in the lowest distracting factors considered 5.26% of the students show that. Regarding the suitable numbers of the slides in 50 mints, 47.37% said 10–20 slides, 36.84% said 30–40 slides and 15.79% said 20–30 slides. About most boring and dull factors 63.16% of students in this study show response to the large number of presented slides, 26.32% large number of bullets and 10.53% of them show that fast presentation. Also 52.63% suggested six bullets are quite enough, three bullets were suggested by 21.05%, nine bullets by15.79% and at last just 10.53% of students mentioned twelve bullets.

Conclusion

Most of the students believed that Power Point presentations have a lot of disadvantage which can make it deadly dull. At last the integrated (PowerPoint and chalkboard) based method of teaching was found more suitable tool of teaching and learning than PowerPoint or chalkboard alone.
Experiencing Embodied Learning: A Mixed‐Methods Analysis of a Yoga Anatomy Workshop
Authors: Klein Barbie , Sugrue Megan , Loyet Mackenzie
Published: November 2023

Research in simulation and multimodal learning environments explore a practice of embodied cognition in which movement enhances learning and memory. We examined if studying anatomy while kinesthetically experiencing yoga poses affects comprehension and perception of the material. Using principles from experiential learning theories, we developed two workshops: the first focused on muscle names, locations, and actions by guiding students through five yoga poses; the second workshop moved through a yoga flow of poses and inversions to study cardiovascular and lymphatic anatomy, respectively. To account for order effect, non‐identical pre‐ and post‐tests were created for each workshop with inter‐rater agreement distinguishing questions as higher and lower order based on the Blooming Anatomy Tool (BAT), ensuring equivalent exam difficulty without exact question repetition. Tests were administered to Yoga Anatomy participants and a control group that did not participate in the workshops. To analyze exam performance, paired and independent samples t‐tests were calculated for Yoga Anatomy and control pre‐ and post‐tests. Although the quantitative findings of student achievement did not exhibit statistical significance, positive trends seen with the Yoga Anatomy intervention warrant further investigation. Qualitative analysis of surveys indicated the activity was an enjoyable review, helped connect lecture and laboratory material, and modeled how to apply course content to a practical activity. Future directions for this pilot project include augmenting the study design to account for sampling issues, improving test question items, and expanding the workshops to medical students.
Instructor Presence and the Value of Instructor‐Student Interface in the Gross Anatomy Laboratory
Authors: Contreras Nicolas , Harper Caitlin J , Lachman Nirusha , Hafferty Frederic W. , Pawlina Wojciech
Published: November 2023

While small group learning and team‐based learning (TBL) have become widely accepted modalities in medical education, surprisingly little is known about how medical students interact between and within their learning teams and how dissection teams themselves interact with faculty or teaching assistants (TAs). This study sought to examine: (1) interactions between faculty/TAs and student teams; and (2) student table‐to‐table interactions taking place in the anatomy didactic block at Mayo Medical School. In addition, interactions between students in the same student team and overall team dynamics were examined by faculty. The purpose of this study is to understand dissection group dynamics and how these sets of interactions relate to student academic performance. The amount of time faculty/TAs spent with a group during each teaching session was recorded by students at the end of each session. The number of team‐to‐team interactions were also recorded. These values were then compared to student examination performance. Results from this study indicated that the individual time faculty/TAs spend with teams and the number of table‐to‐table interactions appeared to have no correlation with overall team academic performance. However, faculty assessment of interactions within student teams and overall team dynamics appears to be an accurate predictor of the team's overall academic performance, where groups with well‐defined leadership roles and strong cooperation between team members performed higher than those where this was not present.

Support or Funding Information

Mayo Clinic College of Medicine Department of Anatomy
Applied Anatomy Labs: Interactive Small Group Learning
Authors: Mork Amy Lovejoy , Klement Brenda , Paulsen Douglas F , Wineski Lawrence E
Published: November 2023

Medical education has shown an increasing trend toward active, small group learning, and away from a primarily passive, lecture based instruction. To further reinforce the small group learning that has traditionally characterized the educational process in cadaver dissection labs, a series of interactive, applied anatomy labs was added to the first year integrated curriculum at Morehouse School of Medicine. Applied anatomy labs typically consist of four to five stations through which small groups of students rotate over the three hour lab period. An applied anatomy lab normally coincides with the completion of the dissection lab and lecture components of each anatomical region. The current curriculum includes applied anatomy lab sessions covering: Back and Upper Limb, Thorax and Abdominal Wall, Abdomen, Orthopedic Surgery/Lower Limb, Pelvis and Perineum, and Head and Neck. During these sessions, the students interact in functional and clinically relevant activities related to the region just completed (e.g., blood pressure measurements following upper limb, cardiac ultrasound during the thorax, pelvic exam simulations after pelvis and perineum). The applied anatomy labs provide an opportunity to utilize clinical faculty to demonstrate regionally relevant techniques for physical exam or treatment, hands on applications of diagnostic and surgical technology, or enhancement of the students’ understanding of both the normal anatomy and related pathologies in small group learning sessions. Applied anatomy labs account for 18 hours (12%) of the 148 total gross anatomy lab hours and enhance opportunities to promote interactive, small group learning within the integrated first year medical curriculum.

Support or Funding Information

Sponsored in part by NIH PO31B04017 and G12RR003034
A Remediation Strategy for Gross Anatomy in the New Horizons Curriculum
Authors: Pizzimenti Marc A
Published: November 2023

An important aspect of curricular design is ensuring that proper contingencies are in place for student remediation. Anticipating and planning for such contingencies, even when these are well‐considered and appropriately timed, often proves difficult when curricula are designed around integrated concepts and early clinical experiences. Although remediation plans are tailored to student needs, certain criteria must be met for the plan to be effective. A student considered for remediation must have completed the course (strand), demonstrated deficiencies that are consistent over the course or within certain parts of the course (strand), and demonstrated success in other parts of the curriculum. Medical gross anatomy has maintained a unique position to ensure adequate laboratory dissection experience that is coupled with concepts that help students integrate anatomy with other aspects of the curriculum. As such, the finalized remediation extends over an 8‐week period where students participate in guided self‐directed activities that were integral to the original course of study. These activities are tailored to student needs and include dissection, online modules, and working through pre‐dissected regions. Additional resources include pre‐recorded lectures and focused faculty interaction. The assessment strategies for the laboratory component were similar to those used in the original course. However, conceptual understanding was assessed using oral presentations, narrative descriptions of the anatomical concepts in clinical vignettes, and the use of multiple‐choice questions. This remediation strategy was designed to ensure students have sufficient knowledge, skills, and attitudes for continued progression through the curriculum.
Correlating clinical reasoning skills to expert interaction in first year medical students
Authors: Manuel Morganne , Rae Guenevere
Published: November 2023

The purpose of this study was to examine the relationship between clinical diagnostic reasoning skills and expert clinical interaction. First year medical students interacted with pathologists by examining the cadaver in which they dissected four times during their gross anatomy course. During these interactive sessions, Pathology faculty and residents gave advice to each dissection team as to the degree that discovered lesions had towards their “first patient's” cause of death. After conclusion of the gross anatomy course, the students were assessed for their clinical reasoning skills by using a newly designed method, which required students to complete an autopsy report on the cadaver in which they dissected. The student reports were compared to similar reports prepared by a team of clinical experts. The students’ score on the assessment was correlated to the amount of time (in minutes) that pathology faculty interacted with the students during the gross anatomy course. The results indicate that interactions with a clinical expert increases medical students’ development of clinical reasoning skills within the environment of the gross anatomy laboratory.
To what extent are first‐year medical students willing to disclose errors: relating a reflective writing exercise in gross anatomy to medical error disclosure
Authors: Sun Philip Young‐woo , Wittich Christopher M , Lachman Nirusha , Pawlina Wojciech
Published: November 2023

Medical error is an important cause of patient morbidity/mortality. Disclosing medical errors to patients is an important component of safe practice. There is a growing need to assess the inherent nature of how physicians in training approach such unanticipated outcomes. With limited exposure for medical students to the idea of medical error disclosure, which is an important area of professionalism in medicine, we believe that a reflective writing exercise can be an efficient tool to objectively assess how students acknowledge and address medical errors early in their medical career. Every year, students in the 1st year gross anatomy course are asked to respond to a scenario in which a medical student's cellular phone conversation with a friend in a public area (i.e. post office) was overheard by a family member of a cadaver donor to Mayo Medical School. Students were asked to write an apology email to the offended party (Mrs. X) as though they were the student who made the mistake. Students were given 48 hours to complete and submit the assignment. We retrospectively reviewed the medical error disclosure assignment of medical students in the first‐year gross anatomy course at Mayo Medical School between 2005 and 2015. An instrument for assessing medical error disclosure, consisting of fifteen items evaluated on Likert scale (1–5, 1 is the lowest and 5 is the highest), was developed. Using this evaluation tool, we assessed the basic elements of medical error disclosure – acknowledgement of error/system failure, expression of regret, awareness of its impact, description of future behavior, and proper tone as an apology letter. Preliminary data from years 2005, 2008, 2011, and 2014 indicated the mean error disclosure scores of 3.49 ± 0.83, 3.32 ± 0.81, 3.29 ± 0.84, and 3.25 ± 0.75, respectively. The word count in those four class years were 246.9 ± 84.0, 236.3 ± 86.4, 211.2 ± 92.3, and 242.3 ± 79.1 words, respectively. The proportion of students who claimed to have spoken with his/her mother was 2 out of 42 (4.7%), 4 out of 49 (8.2%), 0 out of 48 (0%), and 20 out of 51 (39%) students, respectively. Across the four class years, there was a non‐significant but uniform trend of reduced mean error disclosure score over time, while the mean word count did not show a certain pattern. One notable trend over the class years was an increasing attribution to their mother as the person they spoke with, possibly a way to help alleviate Mrs. X's frustration by eliciting empathy. Overall, this efficient, integrated writing exercise serves as a sensitive tool to objectively gauge skills in the basic areas of medical error disclosure in a preclinical anatomy course.

Support or Funding Information

My sponsor is Dr. Wojciech Pawlina, the senior author of the abstract. Funding will be considered by the Department of Anatomy, Mayo Clinic College of Medicine, Rochester, MN.
Assessing simulation‐based interventional angiography training in novices
Authors: Zaika Oleksiy , Boulton Mel , Eagleson Roy , de Ribaupierre Sandrine
Published: November 2023

Laparoscopic surgical procedures require visual‐spatial coordination in workspaces with restricted views, involving constrained motions. The development of the skills needed for these procedures can be facilitated by 3D simulator‐based training. Surgical training programs are introducing additional requirements of competency‐based simulation in their curricula. Cerebral angiography (CA), however, has lagged behind in this regard, relying strictly on clinical case exposure frequency as a means of assessing proficiency. Simulation in CA training has encountered some roadblocks, possibly due to lack of validation studies that would support more widespread acceptance. The AngioMENTOR visual‐haptic simulator has been regarded as an effective training tool, increasing performance in diagnostic CA. However, this simulator has not been tested thoroughly for training interventional skills in CA. In our current study, neurosurgery and radiology residents will be trained in diagnostic CA, and later assessed on their interventional performance on a variety of cases using AngioMENTOR. The participants’ spatial abilities are used as a baseline measure for comparative assessment of their procedure times, fluoroscopy use, contrast injection, and error correction. We hypothesize that individuals with higher spatial ability would perform the procedure more quickly, using less fluoroscopy and spending less time in incorrect vessels. These findings would complement our initial work on diagnostic CA simulation training, and provide quantitative metrics of performance on this simulator‐based task.
Gross Anatomy for Teacher Education (GATE): Equipping the Anatomy Educator
Authors: Brooks William , Doss Austin
Published: November 2023

Qualified anatomy educators are currently in short‐supply across U.S. colleges and universities. As a means of contributing to the education and training of current and future anatomists, the University of Alabama at Birmingham (UAB) has designed an anatomy mini‐course known as Gross Anatomy for Teacher Education (GATE). The goals of this three‐day mini‐course are to enhance the educational effectiveness of current anatomy instructors and to contribute to the training of a new generation of anatomist‐educator. GATE cycles through the four major anatomical regions in a four‐year rotation: trunk, back/upper limb, lower limb, and head/neck. The course includes didactic instruction and full cadaveric dissection. Attendees of the first two years of the course have included anatomy educators from high schools, community colleges, and four‐year colleges and universities as well as graduate students and postdoctoral trainees in the biomedical sciences. Attendees have represented five states thus far. The purpose of this study was to evaluate the effectiveness of GATE through a pre‐test/post‐test model and by responses to course evaluations. Attendees were administered a 10 question, multiple choice quiz at the beginning and end of each course. In both years, a statistically significant increase in short‐term knowledge outcomes was observed (P<0.001). When asked to evaluate the level of improvement in anatomical knowledge, most attendees answered ‘greatly improved’. When asked to evaluate the level of interest in anatomy education, faculty overwhelmingly answered ‘greatly improved’. We also asked attendees to describe how attending the GATE mini‐course had impacted their instruction. The most common response was that GATE had provided many clinical correlates that attendees had utilized to improve student engagement with the content. The GATE mini‐course demonstrates one way in which major universities can contribute to the instruction and professional development of anatomy educators in high schools and small colleges across the country.

Support or Funding Information

The 2015 GATE mini‐course was funded in part by an Educational Outreach Grant from the American Association of Anatomists.
Identifying the MAP kinase Slt2/Mpk1 as a new interacting protein for Mms2
Authors: Kung George , Wang Yuqi
Published: November 2023

Mms2 is an ubiquitin E2 variant that works with the E2 conjugating enzyme Ubc13 in the DNA damage response pathway. To gain a better understanding of the functions of Mms2 as well as the molecular mechanisms that regulate Mms2, we conducted a proteomic study to identify proteins that interact with Mms2. Flag‐tagged Mms2 was expressed in the budding yeast, and proteins that co‐immunoprecipitated with Flag‐tagged Mms2 were analyzed by mass spectrometry. As a result, we identified Mpk1/Slt2, a mitogen activated protein kinase (MAP kinase), as an interacting protein of Mms2. Notably, Mms2 protein contains a serine residue that matches the consensus sequence (PXSP) of MAP kinase, suggesting a possibility that Mms2 is a substrate of Mpk1/Slt2. Studies designed to test this hypothesis are underway.
Phenotypic and Genetic Characterization of the Escherichia coli Protein YbjN in Response to Ionizing Radiation
Authors: Menhart Mary , Bruckbauer Steven T. , Cox Michael M.
Published: November 2023

Ionizing radiation (IR) causes a wide variety of damage to cells, including DNA double stranded breaks (DSBs) and the creation of reactive oxygen species (ROS). ROS created by IR cause damage to all cellular components which may ultimately result in cell death. To elucidate the mechanisms by which some bacterial species survive extreme DNA damage from IR, IR resistant E. coli were generated through directed evolution. A single isolate from the resulting populations was subjected to random transposon mutagenesis and screened for genes important for IR resistance. Of the 46 genes identified 7 are of unknown function, one of which being ybjN. Overexpression of YbjN has been observed to suppress growth rate, motility, biofilm formation, and metabolic pathways with an up‐regulation of stress‐related genes including cold shock and the SOS response. YbjN is expressed highly in E. coli under stress conditions, such as IR exposure and highly alkaline conditions. This data suggests that the YbjN protein may induce a dormant state which would allow the cell more time to repair DNA or other damage caused by ROS. In work to be completed soon, the effects of ybjN gene loss or modification on ROS damage and DNA DSB damage will be examined separately. We will determine whether ybjN has a specific involvement with either. The function of the ybjN gene is important for cell survival against IR. An elucidation of its function will enable a greater understanding of how cells recover from this extreme stress.
Regulation of the Kinetoplast maxicircle DNA replication by RNase HIIC in Trypanosoma brucei
Authors: Misra Smita , Mittal Mukul K , Singha Ujjal K , Chaudhuri Minu , Chaudhuri Gautam
Published: November 2023

Ribonuclease H (RNase H, EC # 3.1.26.4) catalyzes the hydrolysis of RNA from a DNA/RNA hybrid. This ubiquitous enzyme interacts with several different DNA‐modifying enzymes in the cell and participates in the replication, recombination and repair of nuclear and mitochondrial DNA molecules. We report here that the type 2 RNase H of the parasitic protozoan Trypanosoma brucei is a predominantly mitochondrial enzyme and is essential for the survival of both the procyclic and the blood stream forms. Yeast 2‐hybrid and co‐IP analyses for the mitochondrial DNA replication‐associated proteins interacting directly with RNase HIIC revealed binding of RNase HIIC with the mitochondrial DNA ligase Kα which is involved in kinetoplast DNA replication. Interestingly, we found that RNase HIIC also binds with the DNA recombinase DMC1 which is also located in the mitochondrion of the parasite. Chromatin immunoprecipitation data indicated binding of both RNase HIIC and DMC1 to the maxicircle DNA. We found that the maxicircle DNA and transcripts derived from it are decreased significantly in the cells with decreased levels of RNase HIIC. This enzyme is required for the recovery from DNA damage caused by caffeine, hydroxyurea and methylmethane sulfonate, as the RNase HIIC knocked down cells are more sensitive to the lethality of these DNA damaging agents. We conclude that RNase HIIC collaborates with DNA ligase Kα and DMC1 to participate in the replication and repair of mitochondrial maxicircle DNA in these parasite cells.

Support or Funding Information

This research is supported in part by DOD‐CDMRP IDEA Expansion Grant# BC103645 and NIH/NCI grant 1R21CA181920‐01 to GC.
Acetylation of DNA Polymerase Beta Regulates the Choice of the Base Excision Repair Pathway
Authors: Howald Olivia Kay , Balakrishnan Lata
Published: November 2023

Base excision repair (BER) is the main pathway through which base damages are repaired in the cell. Single nucleotide damage can be corrected either through short patch BER (SP‐BER), in which the single damaged base is replaced, or long patch BER (LP‐BER), in which two or more nucleotides can be replaced. Several proteins are involved in the process including DNA polymerase beta (pol β) and FEN1, both of which are the focus for this study. DNA pol β is a multifunctional protein which contains both polymerase and lyase properties. In LP‐BER, pol β displaces the uncleaved 5′dRP moiety into a flap structure which is recognized and cleaved by FEN1 and subsequently ligated by DNA ligase 1. Previous in vitro studies show that pol β acetylation reduces lyase activity, requiring repair to proceed via LP‐BER. In this study, we determined the effect of in vitro acetylation on the enzymatic activities of DNA pol β and FEN1. Both unmodified and acetylated forms of pol β were tested for their synthesis and strand displacement activities. Interestingly, acetylated forms of pol β showed much greater activity at all concentrations versus unmodified forms. Interestingly we also found that FEN1 cleavage activity was increased in reactions containing acetylated pol β compared to the unmodified form due to the increased strand displacement activity of the polymerase. Our results suggest that the acetylated form of DNA pol β more actively participates in LP‐BER, creating longer strands of corrected, higher fidelity nucleotides.

Support or Funding Information

This work was supported by a grant from the National Institutes of Health GM098328 (to LB)
Instability within the coding sequence of the repetitive RNA polymerase II C‐terminal domain
Authors: Exner Alexandra E , Fuchs Stephen M
Published: November 2023

The carboxyl‐terminal domain (CTD) of RNA polymerase II is composed of a conserved tandemly repeating 7 amino acid sequence and plays an essential role in transcription. We and others have shown that number of CTD repeats differs between species (e.g. 26 in yeast, 52 in humans) but also, variability is seen amongst individuals within a single species. The DNA that encodes repetitive amino acid sequences is thought to be unstable and prone to both expansion and contraction of the DNA sequence, resulting in protein products of different length. Previous studies have shown mutations that confer a shorter CTD protein product impair growth and spontaneous suppressor mutations can arise in which the CTD coding region rearranges by either expansion or contraction to improve growth. Our goal was to study this plasticity of the CTD by measuring the rate at which the CTD contracted to repair a series of premature stop codons. Specifically, we inserted stop codons after repeats 8–11, which produced a shortened protein product and lead to decreased growth. The CTD was indeed able to contract and delete the stop codon‐containing repeats, and often delete extra repeats in the contraction process. To explore the mechanisms involved in these contraction events, we measured mutation frequency in yeast in which factors important for DNA repair had been deleted. Our results show that, unlike CTD expansion, which requires homologous recombination, contraction percentage was greatly increased in rad52Δ cells. We have used this data to build a CTD contraction model wherein we propose that the DNA encoding the repetitive CTD region is unstable, and nonessential repeats act as a template during DNA repair to confer plasticity. These findings will be helpful in explaining the variation in CTD repeat number amongst individuals within a species, as well as a useful general model for the instability in genomic regions encoding repetitive amino acid sequences.

Support or Funding Information

Start up funding from Tufts University
Function of Cdc45 in DNA Replication and in Response to Genotoxic Stress
Authors: DeBrot Amanda , Lancaster Cynthia , Bjornsti Mary‐Ann
Published: November 2023

DNA replication is a highly conserved and tightly regulated process, with a variety of factors acting to ensure faithful duplication and stability of chromosomal DNA. During replication, positive supercoils form ahead of the advancing replication fork. DNA topoisomerase 1 (Top1) acts to prevent DNA damage by relieving the torsional strain created by these supercoils. The camptothecin (CPT) class of chemotherapeutics target Top1, creating a long‐lived DNA‐Top1‐CPT covalent complex, which leads to S‐phase specific DNA lesions and cellular death.

Our lab previously performed a genetic screen to isolate mutant proteins that enhanced cell sensitivity to Top1‐mediated DNA damage. One of the mutant proteins identified was Cdc45G510E, which contains a single amino substitution at residue G510. Cells expressing this protein were also hypersensitive to other forms of DNA damage and exhibited collapsed replication forks, suggesting a role for Cdc45 in protecting cells from genotoxic stress.

Cdc45 is an essential protein found within the CMG (Cdc45‐MCM‐GINS) replicative helicase. Until recently, it was considered a scaffolding protein that had only been identified in eukaryotes. However, sequence alignments and structural studies suggest that Cdc45 may in fact be the eukaryotic ortholog of the archaeal RecJ protein. This is due, in large part, to the conservation of residues within DHH (Asp‐His‐His) motifs in the N‐terminus of Cdc45, which act to coordinate a metal ion and are essential for the nuclease activity of various RecJ proteins. The functional similarities between Cdc45 and RecJ identified thus far are the inclusion within the respective replicative helicases and the ability to bind ssDNA. RecJ has also been determined to aid in DNA damage repair, such as homologous recombination and rescue of stalled replication forks. In our mutational analyses of yeast CDC45, we demonstrated that the conserved DHH residues were also necessary for Cdc45 function in protecting cells from genotoxic stress. Moreover, several of these residues are also required to maintain cell viability in the absence of exogenous DNA damage.
A Novel Role For RPA Phosphorylation In The Regulation Of G2 Exit In The Face Of Persistent DNA Damage
Authors: Wilson Timothy M. , Ghospurkar Padmaja L. , Haring Stuart J.
Published: November 2023

Background

Replication Protein A (RPA), a heterotrimeric complex with critical roles in DNA metabolism and cell cycle progression, is observed to be hyper‐phosphorylated in response to genotoxic stress. Hyper‐phosphorylation of human RPA (hRPA) occurs primarily on the N‐terminus (NT) of the 32 kDa Rpa2 (hRpa2) subunit. In contrast, phosphorylation of yeast RPA (yRPA) on the Rpa2 (yRpa2) NT is not detectable upon exposure to commonly used genotoxic agents (e.g., methyl methanesulfonate, hydroxyurea). In fact, the yRpa2 NT has never been identified as a major site of phosphorylation upon DNA damage treatment. However, the examination of yRpa2 NT phospho‐mutants suggests that the phospho‐state of yRpa2 NT may play a key role in cell cycle progression despite the continued presence of DNA damage (checkpoint adaptation). In some instances checkpoint adaptation might allow for the positive cellular consequence of continued cell growth. This comes with a potential negative organismal cost, as checkpoint adaptation is often detrimental to cell survival and is also associated with increased genomic instability, which can ultimately lead to mutations that cause cellular disease.

Study Objective

To elucidate the importance of the yeast Rpa2 NT in regulating exit from the G2/M checkpoint.

Method

We examined yRpa2 phosphorylation and the cell cycle progression of yRpa2 NT mutants in an inducible HO endonuclease system that generates a single double‐strand break (DSB) that cannot be repaired by homologous recombination (HR).

Results and Conclusions

We have demonstrated that the presence of the yRpa2 NT is necessary for checkpoint adaptation. Furthermore, we have recently discovered that in the presence of a persistent lesion, yRpa2 NT hyper‐phosphorylation is now readily detected. This is consistent with our published data demonstrating that checkpoint adaptation is affected in yRpa2 phospho‐mutant cells. Because N‐terminal phosphorylation is now detectable under this condition, we have employed alanine scanning mutagenesis to identify which sites on the yRpa2 NT are phosphorylated and important for promoting checkpoint adaptation. We have also examined the kinases responsible for phosphorylating the yRpa2 NT during checkpoint adaptation. In addition, we have evidence that phosphorylation of the yRpa2 NT occurs primarily upon prolonged exposure to other agents that specifically result in DSB formation. Finally, we propose a model that suggests that Rad53 deactivation and Rfa2 phosphorylation may be linked to coordinate checkpoint adaptation in yeast. Understanding how yRPA phospho‐states influence cellular division in the presence of persistent/prolonged genotoxic stress may help provide the framework for deciphering the molecular mechanism(s) cells employ to maintain their genome.

Support or Funding Information

This research was supported by NSF‐CAREER 1253723 to SJH.