Perspectives from Undergraduate Life Sciences Faculty: Are We Equipped to Effectively Accommodate Students With Disabilities in Our Classrooms?

Higher education has evolved in ways that may increase the challenges life science faculty face in providing accommodations for students with disabilities. Guided by Expectancy-Value Theory, we interviewed 34 life sciences faculty instructors from institutions nationwide to explore faculty motivation to create disability-inclusive educational experiences. We found that faculty in our sample perceive that providing most standard accommodations is a manageable but often challenging task. Further, faculty in our sample feel that improving accommodations necessitates additional support from their institutions. Most faculty had high attainment value for providing accommodations, in that they strongly believed that supporting students with disabilities is the fair and right thing to do. However, faculty did not perceive much utility value or intrinsic value in their task of providing accommodations, and most reported that providing accommodations can be a substantial burden on faculty. These findings imply that current approaches to providing inclusive educational experiences for students with disabilities rely primarily on the personal belief that providing accommodations is the right thing to do, which likely results in a flawed and inequitable system given that not all faculty equally share this conviction.

Preparing Teaching Assistants to Facilitate Course-based Undergraduate Research Experiences (CUREs) in the Biological Sciences: A Call to Action

Course-based undergraduate research experiences (CUREs) offer an expanding avenue to engage students in real-world scientific practices. Increasingly, CUREs are instructed by graduate teaching assistants (TAs), yet TAs may be underprepared to facilitate and face unique barriers when teaching CUREs. Consequently, unless TAs are provided professional development (PD) and resources to teach CUREs effectively, they and their students may not reap the assumed benefits of CURE instruction. Here, we describe three perspectives - that of the CURE TA, the CURE designer/facilitator, and the CURE student - that are collectively intended to inform the development of tentative components of CURE TA PD. We compare these perspectives to previous studies in the literature in an effort to identify commonalities across all sources and offer potential insights for advancing CURE TA PD efforts across a diversity of institutional environments. We propose that the most effective CURE TA PD programs will promote the use of CURE-specific instructional strategies as benchmarks for guiding change in teaching practices and should focus on three major elements: 1) enhancement of research and teaching acumen, 2) development of effective and inclusive mentoring practices, and 3) identification and understanding of the factors that make CUREs a unique learning experience.

The Disproportionate Impact of Fear of Negative Evaluation on First-Generation College Students, LGBTQ+ Students, and Students with Disabilities in College Science Courses

Fear of negative evaluation (FNE), defined as a sense of dread associated with being negatively judged in a social situation, has been identified as the primary factor underlying undergraduate anxiety in active-learning science courses. However, no quantitative studies have examined the extent to which science undergraduates experience FNE and how they are impacted by FNE in college science courses. To address this gap, we surveyed 566 undergraduates from one university in the U.S. Southwest who were enrolled in life sciences courses where they had opportunities to speak in front of the whole class. Participants were asked a suite of questions regarding their experiences with FNE in large-enrollment college science courses. We found that first-generation college students, LGBTQ+ students, and students with disabilities reported disproportionately high levels of FNE compared with their counterparts. Additionally, students reported that FNE can cause them to overthink their responses and participate less in class. Participants rated being cold called and presenting alone as forms of whole-class participation that elicit the highest levels of FNE. This research highlights the impact of FNE on undergraduates and provides student-generated recommendations to reduce FNE in active-learning science courses.

Synthesizing Research Narratives to Reveal the Big Picture: a CREATE(S) Intervention Modified for Journal Club Improves Undergraduate Science Literacy

Communicating science effectively is an essential part of the development of science literacy. Research has shown that introducing primary scientific literature through journal clubs can improve student learning outcomes, including increased scientific knowledge. However, without scaffolding, students can miss more complex aspects of science literacy, including how to analyze and present scientific data. In this study, we apply a modified CREATE(S) process (Concept map the introduction, Read methods and results, Elucidate hypotheses, Analyze data, Think of the next Experiment, and Synthesis map) to improve students' science literacy skills, specifically their understanding of the process of science and their ability to use narrative synthesis to communicate science. We tested this hypothesis using a retrospective quasi-experimental study design in upper-division undergraduate courses. We compared learning outcomes for CREATES intervention students to those for students who took the same courses before CREATES was introduced. Rubric-guided, direct evidence assessments were used to measure student gains in learning outcomes. Analyses revealed that CREATES intervention students versus the comparison group demonstrated improved ability to interpret and communicate primary literature, especially in the methods, hypotheses, and narrative synthesis learning outcome categories. Through a mixed-methods analysis of a reflection assignment completed by the CREATES intervention group, students reported the synthesis map as the most frequently used step in the process and highly valuable to their learning. Taken together, the study demonstrates how this modified CREATES process can foster scientific literacy development and how it could be applied in science, technology, engineering, and math journal clubs.

Not the same CURE: Student experiences in course-based undergraduate research experiences vary by graduate teaching assistant

To expose all undergraduate science students to the benefits of participating in research, many universities are integrating course-based undergraduate research experiences (CUREs) into their introductory biology laboratory curriculum. At large institutions, the bulk of introductory labs are instructed by graduate teaching assistants (GTAs). Graduate students, who are often teachers and researchers in training, may vary in their capacity to effectively teach undergraduates via the CURE model. To explore variation in GTA teaching and the subsequent outcomes for students, we used a case study research design at one institution where introductory biology students participate in GTA-taught CURE lab sections. We used multiple data sources, including in-class focus groups, worksheets, and surveys to explore student perceptions of the GTA-led CURE. Students perceived variation both in the ability of their GTAs to create a supportive and comfortable learning environment, and in the instructional priorities of their GTAs. We also compared student and GTA perspectives of student engagement with research elements in the CURE. While GTAs were divided in their perceptions of whether the CURE provided students with the opportunity to experience the element of relevant discovery, most students—regardless of their GTA—did not perceive that relevant discovery was emphasized in the CURE. Finally, individual GTAs seemed to influence how students perceived why they were participating in the CURE. These data imply that students in CUREs may have vastly different and potentially inequitable research experiences depending on their instructor.

Enthusiastic but Inconsistent: Graduate Teaching Assistants' Perceptions of Their Role in the CURE Classroom

Despite growing evidence of positive student outcomes from course-based undergraduate research experiences (CUREs), little consideration has been given to employing graduate teaching assistants (GTAs) as CURE instructors. GTAs may be novice researchers and/or teachers and likely vary in their interest in teaching a CURE. Guided by expectancy-value theory, we explored how GTAs' self-efficacy and values regarding teaching a CURE impact motivation and perceptions of their roles as CURE instructors. Using a multiple case study design, we interviewed nine GTAs who taught a network CURE at one research institution. Though most GTAs held a relatively high value for teaching a CURE for a range of reasons, some GTAs additionally perceived high costs associated with teaching the CURE. Through the interview data, we established three profiles to describe GTA perceptions of their role as CURE instructors: "Student Supporters," "Research Mentors," and "Content Deliverers." Those implementing GTA-led CUREs should consider that GTAs likely have different perceptions of both their role in the classroom and the associated costs of teaching a CURE. The variability in GTA perceptions of CUREs implies that undergraduate students of different GTAs are unlikely to experience the CURE equivalently.

Is This Science? Students' Experiences of Failure Make a Research-Based Course Feel Authentic

Course-based undergraduate research experiences (CUREs) and inquiry-based curricula both expose students to the scientific process. CUREs additionally engage students in novel and scientifically relevant research, with the intention of providing an "authentic" research experience. However, we have little understanding of which course design elements impact students' beliefs that they are experiencing "authentic" research. We designed a study to explore introductory biology students' perceptions of research authenticity in CURE and inquiry classes. Using the Laboratory Course Assessment Survey, we found that students in CURE sections perceived higher levels of authentic research elements than students in inquiry-based sections. To identify specific factors that impact perceptions of research authenticity, we administered weekly reflection questions to CURE students. Coding of reflection responses revealed that experiences of failure, iteration, using scientific practices, and the relevant discoveries in their projects enhanced students' perceived authenticity of their research experiences. Although failure and iteration can occur in both CUREs and inquiry-based curricula, our findings indicate these experiences-in conjunction with the Relevant Discovery element of a CURE-may be particularly powerful in enhancing student perceptions of research authenticity in a CURE.

Undergraduate Biology Education Research Gordon Research Conference: A Meeting Report

The 2019 Undergraduate Biology Education Research Gordon Research Conference (UBER GRC), titled "Achieving Widespread Improvement in Undergraduate Education," brought together a diverse group of researchers and practitioners working to identify, promote, and understand widespread adoption of evidence-based teaching, learning, and success strategies in undergraduate biology. Graduate students and postdocs had the additional opportunity to present and discuss research during a Gordon Research Seminar (GRS) that preceded the GRC. This report provides a broad overview of the UBER GRC and GRS and highlights major themes that cut across invited talks, poster presentations, and informal discussions. Such themes include the importance of working in teams at multiple levels to achieve instructional improvement, the potential to use big data and analytics to inform instructional change, the need to customize change initiatives, and the importance of psychosocial supports in improving undergraduate student well-being and academic success. The report also discusses the future of the UBER GRC as an established meeting and describes aspects of the conference that make it unique, both in terms of facilitating dissemination of research and providing a welcoming environment for conferees.

Genome Sequences of Cluster K Mycobacteriophages Deby, LaterM, LilPharaoh, Paola, SgtBeansprout, and Sulley

Mycobacteriophages Deby, LaterM, LilPharaoh, Paola, SgtBeansprout, and Sulley were isolated from soil using Mycobacterium smegmatis mc2155. Genomic analysis indicated that they belong to subclusters K1 and K5. Their genomic architectures are typical of cluster K mycobacteriophages, with most variability occurring on the right end of the genome sequence.

Catching the Wave: Are Biology Graduate Students on Board with Evidence-Based Teaching?

Graduate students hold a critical role in responding to national calls for increased adoption of evidence-based teaching (EBT) in undergraduate classrooms, as they not only serve as teaching assistants, but also represent the pool from which future faculty will emerge. Through interviews with 32 biology graduate students from 25 institutions nationwide, we sought to understand the progress these graduate students are making in adopting EBT through qualitative exploration of their perceptions of and experiences with both EBT and instructional professional development. Initial inductive content analysis of interview transcripts guided the holistic placement of participants within stages of Rogers's diffusions of innovations model, which we use as a theoretical framework to describe the progress of EBT adoption. We found that most graduate students in our sample are aware of and value EBT, but only 37.5% have implemented EBT. Many who were progressing toward EBT adoption had sought out supplementary instructional experiences beyond the requirements of their programs, and 72% perceived an institutional lack of support for teaching-related professional development opportunities. These data indicate that, while many graduate students are already engaged with the movement to adopt EBT, graduate training programs should emphasize increasing access to quality training in EBT strategies.

Abstract P2-10-08: A predictive test for neoadjuvant chemotherapy in breast cancer identifies a subset of triple negative patients with resistant disease and the poorest prognosis

Prediction of pathological complete response (pCR) for neoadjuvant treatment is an area of unmet clinical need, especially for triple negative breast cancer (TNBC) as pCR is correlated with better outcomes. Predicting which patients will have residual disease (RD) provides an opportunity to improve treatment planning. We developed a test to predict which patients are likely to achieve pCR or RD to the standard of care (taxane-based) neoadjuvant chemotherapy using gene expression profiling of 325 previously identified novel biomarkers.

Three microarray datasets were used (GSE22226, GSE25055, and GSE25065) including a total of 594 stage II-III breast cancer patients of which 125 (21%) achieved pCR, and 469 (79%) RD. ER+ tumors were present in 57% of the patients and 52% were PGR+. Almost 90% of the patients were Her2-. Of 231 TNBC, 78 (33.8%) achieved pCR, while 153 (66.2%) RD. Of 303 ER+Her- patients 26 (8.6%) achieved pCR while 277 (91.4%) RD. The cohort was divided into balanced populations with 476 patients used for training (80%) and test (20%) rounds of model development, while 118 patients were reserved as a validation set. Combining a “winnowing” process to remove genes with least predictive power, and hundreds of thousands of step-wise runs, followed by ranking genes based on conditional probabilities, we developed a 17-gene cassette (BA100) which was locked-down in the validation set with ROC (AUC) = 0.818. With a cut-off of 83% sensitivity and 68% specificity (PPV 0.4; NPV 0.94), BA100 achieved a 16% true positive rate (true pCR) and 55% true negative rate (true RD) identifying 76% of the patients who achieved pCR, and 69% of the patients with RD. In TNBC, BA100 classified 29% as true positives (TP), 36% as false positive (FP), 30% true negative (TN), and 4.8% false negative (FN). Kaplan Meier (KM) curves showed a significant difference in 5-year disease-free survival (5Y DFS) between TP and TN (p=0.00453) or FP (p=2.09E-06). However, FP had even worse outcomes than TN patients. To improve the TP rate, additional genes expressed in TNBC plus the original 325 genes were subjected to a second round of gene selection to discriminate between TP and FP, resulting in a 16-gene cassette (BA100.1). With a cut-off of 95% sensitivity and 73% specificity (PPV 0.7; NPV 0.95), applying BA100.1 reduced the FP rates from 24% to 9%, while correctly identifying 88% of RD in the validation set. KM curves showed no significant difference in 5Y DFS between 124 TNBC (53.7%) classified as TN versus 29 TNBC (12.6%) classified as FP, while a significant difference in survival rate was found between TNBC classified as TN vs TP (Cox Proportional Harzard p=8.42e-05).

Taken together, we developed a predictive test consisting of two gene cassettes that accurately identified 71% (88/104) of pCR, and 88% (417/469) of RD patients. Gene cassettes include several transcriptional repressors, PI3K signal transduction, components of telomerase, DNA repair genes, fatty acid metabolism and estrogen-independent proliferation. The test stratified TNBC with differential response to chemotherapy and survival rates so that novel approaches can be used without delay. Further validation will confirm the test utility.

Citation Format: Fournier MV, Chen J, Obenauer J, Goodwin EC, Tannenbaum SH, Brufsky AM. A predictive test for neoadjuvant chemotherapy in breast cancer identifies a subset of triple negative patients with resistant disease and the poorest prognosis [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P2-10-08.

Induced senescence in HeLa cervical carcinoma cells containing elevated telomerase activity and extended telomeres

Proliferation of normal somatic human cells in culture is limited by replicative senescence, a growth-arrested state that appears to be triggered by the erosion of telomeres. Tumor cells such as HeLa cervical carcinoma cells, which contain short telomeres, can be induced to undergo senescence by various manipulations including oncogene withdrawal. Repression of the human papillomavirus (HPV) type 18 E6/E7 genes in HeLa cells by the bovine papillomavirus E2 transcriptional regulatory protein results in reactivation of the dormant p53 and p105(Rb) tumor suppressor pathways in these cells, repression of telomerase, and profound growth arrest. Strikingly, the growth-arrested cells rapidly and synchronously acquired numerous characteristics of primary cells undergoing replicative senescence. To explore the role of telomerase and telomere length in induced senescence, we expressed an exogenous hTERT gene, which encodes the catalytic subunit of telomerase, to generate stable HeLa cell clones with elevated telomerase activity and extended telomeres. Expression of the E2 protein in these cells repressed HPV E6/E7 expression, activated tumor suppressor pathways, and induced senescence as assessed by growth arrest, morphological changes, senescence-associated beta-galactosidase expression, and increased autofluorescence. Cells carrying the hTERT gene and control cells displayed identical responses to E2 expression. Therefore, HeLa cell senescence induced by HPV repression is not triggered by short telomeres or low levels of telomerase activity.

Repression of human papillomavirus oncogenes in HeLa cervical carcinoma cells causes the orderly reactivation of dormant tumor suppressor pathways

Most cervical carcinomas express high-risk human papillomaviruses (HPVs) E6 and E7 proteins, which neutralize cellular tumor suppressor function. To determine the consequences of removing the E6 and E7 proteins from cervical cancer cells, we infected HeLa cells, a cervical carcinoma cell line that contains HPV18 DNA, with a recombinant virus that expresses the bovine papillomavirus E2 protein. Expression of the E2 protein resulted in rapid repression of HPV E6 and E7 expression, followed approximately 12 h later by profound inhibition of cellular DNA synthesis. Shortly after E6/E7 repression, there was dramatic posttranscriptional induction of p53. Two p53-responsive genes, mdm2 and p21, were induced with slightly slower kinetics than p53 and appeared to be functional, as assessed by inhibition of cyclin-dependent kinase activity and p53 destabilization. There was also dramatic posttranscriptional induction of p105(Rb) and p107 after E6/E7 repression, followed shortly thereafter by induction of p130. By 24 h after infection, only hypophosphorylated p105(Rb) was detectable and transcription of several Rb/E2F-regulated genes was dramatically repressed. Constitutive expression of the HPV16 E6/E7 genes alleviated E2-induced growth inhibition and impaired activation of the Rb pathway and repression of E2F-responsive genes. This dynamic response strongly suggests that the p53 and Rb tumor suppressor pathways are intact in HeLa cells and that repression of HPV E6 and E7 mobilizes these pathways in an orderly fashion to deliver growth inhibitory signals to the cells. Strikingly, the major alterations in the cell cycle machinery underlying cervical carcinogenesis can be reversed by repression of the endogenous HPV oncogenes.

E2F-Rb complexes assemble and inhibit cdc25A transcription in cervical carcinoma cells following repression of human papillomavirus oncogene expression

Expression of the bovine papillomavirus E2 protein in cervical carcinoma cells represses expression of integrated human papillomavirus (HPV) E6/E7 oncogenes, followed by repression of the cdc25A gene and other cellular genes required for cell cycle progression, resulting in dramatic growth arrest. To explore the mechanism of repression of cell cycle genes in cervical carcinoma cells following E6/E7 repression, we analyzed regulation of the cdc25A promoter, which contains two consensus E2F binding sites and a consensus E2 binding site. The wild-type E2 protein inhibited expression of a luciferase gene linked to the cdc25A promoter in HT-3 cervical carcinoma cells. Mutation of the distal E2F binding site in the cdc25A promoter abolished E2-induced repression, whereas mutation of the proximal E2F site or the E2 site had no effect. None of these mutations affected the activity of the promoter in the absence of E2 expression. Expression of the E2 protein also led to posttranscriptional increase in the level of E2F4, p105(Rb), and p130 and induced the formation of nuclear E2F4-p130 and E2F4-p105(Rb) complexes. This resulted in marked rearrangement of the protein complexes that formed at the distal E2F site in the cdc25A promoter, including the replacement of free E2F complexes with E2F4-p105(Rb) complexes. These experiments indicated that repression of E2F-responsive promoters following HPV E6/E7 repression was mediated by activation of the Rb tumor suppressor pathway and the assembly of repressing E2F4-Rb DNA binding complexes. Importantly, these experiments revealed that HPV-induced alterations in E2F transcription complexes that occur during cervical carcinogenesis are reversed by repression of HPV E6/E7 expression.

Rapid induction of senescence in human cervical carcinoma cells

Expression of the bovine papillomavirus E2 regulatory protein in human cervical carcinoma cell lines repressed expression of the resident human papillomavirus E6 and E7 oncogenes and within a few days caused essentially all of the cells to synchronously display numerous phenotypic markers characteristic of cells undergoing replicative senescence. This process was accompanied by marked but in some cases transient alterations in the expression of cell cycle regulatory proteins and by decreased telomerase activity. We propose that the human papillomavirus E6 and E7 proteins actively prevent senescence from occurring in cervical carcinoma cells, and that once viral oncogene expression is extinguished, the senescence program is rapidly executed. Activation of endogenous senescence pathways in cancer cells may represent an alternative approach to treat human cancers.

Bovine papillomavirus E2 protein activates a complex growth-inhibitory program in p53-negative HT-3 cervical carcinoma cells that includes repression of cyclin A and cdc25A phosphatase genes and accumulation of hypophosphorylated retinoblastoma protein

The bovine papillomavirus E2 protein can inhibit the proliferation of HT-3 cells, a p53-negative cervical carcinoma cell line containing integrated human papillomavirus type 30 DNA. Here, we analyzed HT-3 cells to explore the mechanism of p53-independent E2-mediated growth inhibition. Expression of the E2 protein repressed expression of the endogenous human papillomavirus type 30 E6/E7 genes. This was accompanied by hypophosphorylation and increased accumulation of p105Rb and repression of E2F1 expression. The E2 protein also caused reduced cyclin-dependent kinase (cdk) 2 activity, but this did not appear to be due to increased expression of cdk inhibitors. Rather, expression of cyclin A, which regulates cdk2 activity, and the cdc25A and cdc25B phosphatases, which are thought to activate cdk2, was significantly reduced at both the RNA and protein levels in response to E2 expression. The E2 protein reduced expression of cdc25A and cdc25B in both HT-3 and HeLa cells, but not in cells that were not growth-inhibited by the E2 protein. E2 point mutants unable to inhibit cell growth did not repress cdc25A and cdc25B expression, nor did the cell cycle inhibitors hydroxyurea and mimosine. Based on these results and the known properties of cell cycle components, we propose a model to account for E2-induced growth inhibition of cervical carcinoma cell lines.

Transactivation-competent bovine papillomavirus E2 protein is specifically required for efficient repression of human papillomavirus oncogene expression and for acute growth inhibition of cervical carcinoma cell lines

The papillomavirus E2 proteins can function as sequence-specific transactivators or transrepressors of transcription and as cofactors in viral DNA replication. We previously demonstrated that acute expression of the bovine papillomavirus type 1 (BPV1) E2 protein in HeLa and HT-3 cervical carcinoma cell lines greatly reduced cellular proliferation by imposing a specific G1/S phase growth arrest. In this report, we analyzed the effects of a panel of point mutations in the BPV1 E2 protein to identify the functional requirements for acute growth inhibition. Disruption of E2-specific transactivation by mutations within either the transactivation domain or the DNA binding domain severely impaired E2-mediated growth inhibition in HeLa and HT-3 cells, even though these mutants retain various other E2 activities. This result indicates that functional transactivation activity is required for acute E2-mediated growth inhibition. HeLa cells, which contain a wild-type p53 gene, and HT-3 cells, which contain a transactivation-defective p53 gene, exhibited similar responses to the E2 mutants, suggesting that identical functions of the E2 protein were required for growth arrest regardless of p53 status. Replacement of the E2 transactivation domain with that of the herpes simplex virus VP16 generated a chimeric transactivator that efficiently stimulated expression of an E2-responsive reporter plasmid yet was completely defective for growth inhibition, suggesting that an E2-specific transactivation function is required for growth arrest. Surprisingly, the transactivation-defective E2 mutants were also markedly defective in their ability to repress transcription of the native human papillomavirus type 18 (HPV18) E6/E7 oncogenes in HeLa cells and of the HPV18 promoter present in a transfected reporter plasmid. These mutants were also defective in their ability to increase p53 levels. Therefore, efficient repression of the HPV18 promoter in HeLa cells is not merely a consequence of the binding of an E2 protein to appropriately situated binding sites in the promoter.

Context effects on N6-adenosine methylation sites in prolactin mRNA

The methylation of internal adenosine residues in mRNA only occurs within GAC or AAC sequences. Although both of these sequence motifs are utilized, a general preference has been noted for the extended sequence RGACU. Not all RGACU sequences in an mRNA are methylated and the mechanisms that govern the selection of methylation sites in mRNA remain unclear. To address this problem we have examined the methylation of transcripts containing sequences of a natural mRNA, namely, bovine prolactin mRNA. In this mRNA, a specific AGACU sequence in the 3' untranslated region is the predominant site of methylation both in vivo and in vitro. The degree to which N6-adenosine methyltransferase recognizes the sequence context of the consensus methylation site was explored by mutational analysis of the nucleotides adjacent to the core sequence as well as the extended regions in which the core element was found. Our results indicate that efficient methylation depends on the extended five nucleotide consensus sequence but is strongly influenced by the context in which the consensus sequence occurs within the overall mRNA molecule. Furthermore, consensus methylation sites present in an RNA duplex are not recognized by the methyltransferase.

The 3'-flanking sequence of the bovine growth hormone gene contains novel elements required for efficient and accurate polyadenylation

In addition to the conserved AAUAAA hexanucleotide, GU- and U-rich sequences in the 3'-flanking region are thought to be critical for efficient polyadenylation. The 3'-flanking sequence requirements for efficient and accurate polyadenylation of the bovine growth hormone (bGH) gene were determined by quantitative S1 nuclease analysis of transcripts derived from various bGH 3' deletions and block mutations transiently transfected into COS-1 cells. Though the bGH 3'-flanking sequence contains a portion of the putative GU efficiency element, we find that mutation of this element leads to a marginal decrease in efficiency similar to that from mutation of other sequences that do not contain recognizable GU- or U-rich motifs. The data are consistent with a diffuse efficiency element in the bGH polyadenylation signal rather than a discrete element as is thought to exist in other mammalian signals. We have also determined that a region from 18 to 27 nucleotides downstream of the cleavage site contains sequences required for correctly positioning the cleavage site.

The use of RNase H and poly(A) junction oligonucleotides in the analysis of in vitro polyadenylation reaction products

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Cloning and nucleotide sequencing of the bovine growth hormone gene

A gene coding for bovine growth hormone was isolated from a bovine genomic library. The nucleotide sequence of the coding regions of the gene was found to be identical with that of a nearly full-length growth hormone cDNA clone. The gene sequence is approximately 1800 bp in length and contains four intervening sequences. The second intervening sequence of 227 nucleotides does not contain a repetitive element similar to that observed in the rat growth hormone gene. A comparison of the 5' and 3' flanking and untranslated regions of the bovine, human and rat growth hormone genes revealed many areas of highly conserved sequence. Especially noteworthy was the observation that all three genes had a 38 nucleotide homologous sequence within their 5' flanking regions located about 100 bp upstream from their transcription initiation sites.