Balancing Thymocyte Adhesion and Motility: A Functional Linkage Between β1 Lntegrins and The Motility Receptor RHAMM

Thymocyte differentiation involves several processes that occur in different anatomic sites within the thymus. Therefore, thymocytes must have the ability to respond to signals received from stromal cells and adopt either adhesive or motile behavior. We will discuss our data indicating human thymocytes use α4β1 integrin, α5β1 integrin and RHAMM to mediate these activities. Immature multinegative (MN; CD3–4–8–19-) thymocytes use α4β1 and α5β1 integrins to mediate weak and strong adhesion. This subset also uses α4β1 integrin to mediate motility. As thymocytes differentiate, they begin to express and use RHAMM to mediate motility in conjunction with α4β1 and α5β1 integrins. Motile thymocytes use β1 integrins to maintain weakly adhesive contacts with substrate to provide traction for locomoting cells, thus weak adhesion is a requirement of motile behavior. Hyaluronan (HA) is also required by thymocytes to mediate motility. HA binding to cell surface RHAMM redistributes intracellular RHAMM to the cell surface where it functions to mediate motility. We propose that the decision to maintain adhesive or motile behavior is based on the balance between low and high avidity binding conformations of β1 integrins on thymocytes and that RHAMM:HA interactions decrease high avidity binding conformations of integrins pushing the balance toward motile behavior

Can we increase students’ scientific literacy while minimizing disciplinary content in a multidisciplinary science course?

Interdisciplinary Studies (IDS) 137 is a multidisciplinary science laboratory course designed for non-science majors at our campus. An overarching objective of the course is to increase scientific problem solving skills and attitudes among the students by having them practice science by completing experiments rather than study discipline-specific course content. Three instructors have worked together to organize the course such that students complete four labs in each of biology, chemistry and physics. To quantitatively measure gains in scientific literacy of IDS 137 students, we developed the Augustana Interdisciplinary Scientific Literacy Evaluation (AISLE). The AISLE includes twenty multiple-choice questions that students complete at the beginning and again at the end of the course. Questions are designed to probe students’ scientific thinking and attitudes in a multidisciplinary manner. The answers are scored using a scale of 2, 1 or 0 for best, acceptable and least correct answers and generates a numeric score that corresponds to scientific skills and attitudes. I will outline the instructional strategy we used to design the course and the criteria we selected to develop the AISLE such that it would reliably measure gains in scientific literacy among the enrolled students. The validity of AISLE was established by collecting calibration data from undergraduate students in non-science majors, from science majors at various stages of their degree and from professors. I will invite the audience to investigate samples of the AISLE problems and test their scientific literacy first hand to evaluate how effectively our approach probes scientific skills and attitudes. I will conclude by presenting the calibration data and compare it to data we have collected from IDS 137 students from two academic years

Immunotargeting with CD154 (CD40 Ligand) Enhances DNA Vaccine Responses in Ducks

Engagement of CD154 on activated T cells with CD40 on antigen-presenting cells (APCs) potentiates adaptive immune responses in mammals. Soluble multimeric forms of CD154 have been used as an adjuvant or in immunotargeting strategies to enhance vaccine responses. The objective of our study was to examine the ability of duck CD154 (DuCD154) to enhance DNA vaccine responses in the duck hepatitis B model. Constructs were generated to express the functional domain of DuCD154 (tCD154), truncated duck hepatitis B virus (DHBV) core antigen (tcore) and chimera of tcore fused to tCD154 (tcore-tCD154). Expression in LMH cells demonstrated that all proteins were secreted and that tCD154 and tcore-tCD154 formed multimers. Ducks immunized with the plasmid ptcore-tCD154 developed accelerated and enhanced core-specific antibody responses compared to ducks immunized with ptcore or ptcore plus ptCD154. Antibody responses were better sustained in both ptcore-tCD154- and ptcore plus ptCD154-immunized ducks. Core-specific proliferative responses of duck peripheral blood mononuclear cells were enhanced in ducks immunized with ptcore-tCD154 or ptcore alone. This study suggests that the role of CD154 in the regulation of adaptive immune responses had already evolved before the divergence of birds and mammals. Thus, targeting of antigens to APCs with CD154 is an effective strategy to enhance DNA vaccine responses not only in mammalian species but also in avian species