Using Plants to Explore the Nature & Structural Complexity of Life

Use of real specimens brings the study of biology to life. This activity brings easily acquired plant specimens into the classroom to tackle common alternative conceptions regarding life, size, complexity, the nature of science, and plants as multicellular organisms. The activity occurs after a discussion of the characteristics of life and engages students in application of course content and utilization of scientific thinking. It is appropriate for any class in which the nature of life and its structural complexities are addressed and in which teachers want to help students gain familiarity with plants as multicellular organisms

Trichome Density and Distribution in Quercus garryana (Oregon White Oak)

Trichomes are hair-like structures that extend from a plant’s surface and help protect the plant from herbivores and excessive water loss. Studying trichome density and distribution can provide insight to a plant’s response to drought stress and herbivore damage. We studied the trichome density of up to 20 leaves from each of 47 mature Quercus garryana (Oregon’s native oak tree). Trees were located in one of three habitat types: oak savannah, oak woodland, and mixed oak-maple-conifer forest. Preliminary results show bundles of four and two trichome clusters were present in higher amounts than bundles of three and single trichomes on the abaxial (lower) leaf surface in the savannah and forest habitat. A lower trichome density was observed on the adaxial (top) versus abaxial (lower) leaf surfaces. Our early results support the conclusion that trichome anatomy is highly variable between Q. garryana trees and may help to explain tree survival in different habitats

The composition of aerial insect communities varies across habitats in an endangered oak ecosystem

Insect communities are sensitive to changes in their habitat including light and moisture levels, and as such can be considered important indicators of environmental change. We studied the abundance, diversity, and composition of insect families within three contrasting habitats in a 100-ha endangered oak ecosystem in central Oregon in order to gain baseline knowledge of these communities and how they might change with habitat restoration. Sampled habitats included an open-grassy savannah, semi-open woodland, and a conifer-deciduous mixed forest. Approximately 500 insects were collected and identified in Fall 2019. There was no significant difference in the mean number or diversity of insects collected in the different habitats. However, there was a difference in the composition of insect communities, with mixed conifer-oak forests having significantly different types of insects than the relatively interchangeable savannah and woodland. This important baseline information will allow us to assess the success of our restoration efforts in this endangered ecosystem

Functional Significance of Sympathetic Fiber Ingrowth in the Habenula

The physiological significance of noradrenergic sympathohabenular ingrowth following medial septal lesions was investigated. Following septal lesions, sympathetic fibers originating in the superior cervical ganglia are known to sprout into the medial habenular nuclei, and into the hippocampal formation. Previous work involving sympathohippocampal ingrowth showed that firing rates in septal animals with no ingrowth showed that firing rates in septal animals with no ingrowth were higher than rates of septal animals with ingrowth and controls. Those results suggested that sympathetic ingrowth in the hippocampus had some functional capability in a modulatory manner. The primary aim of the present study was to determine if the peripheral sympathetic ingrowth into the medial habenular nuclei following a septal lesion is functionally significant. The results showed that firing rates of neurons of the medial habenulae in animals receiving septal lesions were significantly higher than rates of control animals and septal lesioned + ganglionectomized animals

Exploring Phytoplankton Population Growth to Enhance Quantitative Literacy: Putting Vision & Change into Action

Quantitative literacy is essential to biological literacy (and is one of the core concepts in Vision and Change in Undergraduate Biology Education: A Call to Action; AAAS 2009). Building quantitative literacy is a challenging endeavor for biology instructors. Integrating mathematical skills into biological investigations can help build quantitative literacy. In our plankton population laboratory sequence, students test hypotheses about the influence of abiotic factors on phytoplankton populations by sampling experimental and control flasks over multiple weeks. Students track and predict changes in planktonic populations by incorporating weekly sample estimates into population growth equations. We have refined the laboratory protocols on the basis of student commentary and instructor observations. Students have reviewed the lab positively, and approximately one-quarter of them reported building their math skills by participating in the lab

Expressions 2021

https://openspace.dmacc.edu/expressions/1037/thumbnail.jp

Exploring Phytoplankton Population Growth to Enhance Quantitative Literacy: Putting Vision & Change into Action

Quantitative literacy is essential to biological literacy (and is one of the core concepts in Vision and Change in Undergraduate Biology Education: A Call to Action; AAAS 2009). Building quantitative literacy is a challenging endeavor for biology instructors. Integrating mathematical skills into biological investigations can help build quantitative literacy. In our plankton population laboratory sequence, students test hypotheses about the influence of abiotic factors on phytoplankton populations by sampling experimental and control flasks over multiple weeks. Students track and predict changes in planktonic populations by incorporating weekly sample estimates into population growth equations. We have refined the laboratory protocols on the basis of student commentary and instructor observations. Students have reviewed the lab positively, and approximately one-quarter of them reported building their math skills by participating in the lab.Keywords: Quantitative literacy, Vision and change, Population growth model

m6A RNA Modification Controls Cell Fate Transition in Mammalian Embryonic Stem Cells

N6-methyl-adenosine (m[superscript 6]A) is the most abundant modification on messenger RNAs and is linked to human diseases, but its functions in mammalian development are poorly understood. Here we reveal the evolutionary conservation and function of m[superscript 6]A by mapping the m[superscript 6]A methylome in mouse and human embryonic stem cells. Thousands of messenger and long noncoding RNAs show conserved m[superscript 6]A modification, including transcripts encoding core pluripotency transcription factors. m[superscript 6]A is enriched over 3′ untranslated regions at defined sequence motifs and marks unstable transcripts, including transcripts turned over upon differentiation. Genetic inactivation or depletion of mouse and human Mettl3, one of the m[superscript 6]A methylases, led to m[superscript 6]A erasure on select target genes, prolonged Nanog expression upon differentiation, and impaired ESC exit from self-renewal toward differentiation into several lineages in vitro and in vivo. Thus, m[superscript 6]A is a mark of transcriptome flexibility required for stem cells to differentiate to specific lineages

Five-year follow up of genotypic resistance patterns in HIV-1 subtype C infected patients in Botswana after failure of thymidine analogue-based regimens

Objective: Our objective was to establish genotypic resistance profiles among the 4% of Batswana patients who experienced virologic failure while being followed within Botswana's National Antiretroviral Treatment Program between 2002 and 2007. Methods: At the beginning of the national program in 2002, almost all patients received stavudine (d4T), together with didanosine (ddI), as part of their first nucleoside reverse transcriptase inhibitor (NRTI)-based regimen (Group 1). In contrast, the standard of care for all patients subsequently enrolled (2002-2007) included zidovudine/lamivudine (ZDV/3TC) (Group 2). Genotypes were analyzed in 26 patients from Group 1 and 37 patients from Group 2. Associations between mutations were determined using Pearson's correlation coefficient and Jaccard's coefficient of similarity. Results: Seventy-eight percent of genotyped patients possessed mutations associated with protease inhibitor (PI) resistance while 87% and 90%, respectively, exhibited mutations associated with NRTIs and non-nucleoside reverse transcriptase inhibitors (NNRTIs). The most frequent PI mutations involving resistance to NFV were L90M (25.2%) and D30N (16.2%), but mutations at positions K45Q and D30N were often observed in tandem (P = 60.5, J = 50; p = 0.002; Group 2) alongside Q61E in 42.8% of patients who received ZDV/3TC. Both major patterns of thymidine analogue mutations, TAM 1 (48%) and TAM 2 (59%), were represented in patients from Group 1 and 2, although M184V was higher among individuals who had initially received ddI (61% versus 40.5%). In contrast, L74V was more frequent among individuals from Group 2 (16.2% versus 7.7%). Differences in regard to NNRTI mutations were also observed between Group 1 and Group 2 patients. Conclusion: Despite a low rate of therapeutic failure (4%) among these patients, those who failed possessed high numbers of resistance mutations as well as novel resistance mutations and/or polymorphisms at sites within reverse transcriptase and protease

Comparison of Post-injection Site Pain Between Technetium Sulfur Colloid and Technetium Tilmanocept in Breast Cancer Patients Undergoing Sentinel Lymph Node Biopsy

BACKGROUND: No prior studies have examined injection pain associated with Technetium-99m Tilmanocept (TcTM). METHODS: This was a randomized, double-blinded study comparing postinjection site pain between filtered Technetium Sulfur Colloid (fTcSC) and TcTM in breast cancer lymphoscintigraphy. Pain was evaluated with a visual analogue scale (VAS) (0–100 mm) and the short-form McGill Pain Questionnaire (SF-MPQ). The primary endpoint was mean difference in VAS scores at 1-min postinjection between fTcSC and TcTM. Secondary endpoints included a comparison of SF-MPQ scores between the groups at 5 min postinjection and construction of a linear mixed effects model to evaluate the changes in pain during the 5-min postinjection period. RESULTS: Fifty-two patients underwent injection (27-fTcSC, 25-TcTM). At 1-min postinjection, patients who received fTcSC experienced a mean change in pain of 16.8 mm (standard deviation (SD) 19.5) compared with 0.2 mm (SD 7.3) in TcTM (p = 0.0002). At 5 min postinjection, the mean total score on the SF-MPQ was 2.8 (SD 3.0) for fTcSC versus 2.1 (SD 2.5) for TcTM (p = 0.36). In the mixed effects model, injection agent (p < 0.001), time (p < 0.001) and their interaction (p < 0.001) were associated with change in pain during the 5-min postinjection period. The model found fTcSC resulted in significantly more pain of 15.2 mm (p < 0.001), 11.3 mm (p = 0.001), and 7.5 mm (p = 0.013) at 1, 2, and 3 min postinjection, respectively. CONCLUSIONS: Injection with fTcSC causes significantly more pain during the first 3 min postinjection compared with TcTM in women undergoing lymphoscintigraphy for breast cancer