The effect of grading matrix assessment on student performance in a large first year biology class

In our large first year biology course, ‘Cells to Organisms’, for 400-900 students per semester, we aimed to provide students with clear links between the course delivery framework and assessment. We wanted the students’ grades to reflect higher order learning of key concepts of cellular and tissue biology, achievement of related practical skills, understanding of the nature of evidence and communication of science. In Semester 1 2008, student grades were determined by the traditional weighted average of marks for the assessment tasks. Since Semester 2 2008, the course has been graded with a grading matrix with specified standards for practical reports, practical competencies, communication tasks and knowledge for the grades of 7 (best) to 1 (worst). Analysis of results for the subsequent three semesters showed that 84-90% of students obtained a passing grade, and that 75% of those students achieved 60% or greater in the final examination – a marked improvement compared with about 50% of the students in Semester 1 2008. Also, their knowledge has improved with a 5% increase in the average mark in the final examination. The grading matrix resulted in improved student engagement with and performance in the assessment areas and graduate attributes addressed in the course

The effect of grading matrix assessment on student performance in a large first year biology class

In our large first year biology course, ‘Cells to Organisms’, for 400-900 students per semester, we aimed to provide students with clear links between the course delivery framework and assessment. We wanted the students’ grades to reflect higher order learning of key concepts of cellular and tissue biology, achievement of related practical skills, understanding of the nature of evidence and communication of science. In Semester 1 2008, student grades were determined by the traditional weighted average of marks for the assessment tasks. Since Semester 2 2008, the course has been graded with a grading matrix with specified standards for practical reports, practical competencies, communication tasks and knowledge for the grades of 7 (best) to 1 (worst). Analysis of results for the subsequent three semesters showed that 84-90% of students obtained a passing grade, and that 75% of those students achieved 60% or greater in the final examination – a marked improvement compared with about 50% of the students in Semester 1 2008. Also, their knowledge has improved with a 5% increase in the average mark in the final examination. The grading matrix resulted in improved student engagement with and performance in the assessment areas and graduate attributes addressed in the course

The role of conserved CXXXRXG motif in the expression and function of the human norepinephrine transporter

Highly conserved motifs in the monoamine transporters, e.g. the human norepinephrine transporter (hNET) GXXXRXG motif which was the focus of the present study, are likely to be important structural features in determining function. This motif was investigated by mutating the glycines to glutamate (causing loss of function) and alanine, and the arginine to glycine. The effects of hG117A, hR121G and hG123A mutations on function were examined in COS-7 cells and compared to hNET. Substrate K-m values were decreased for hG117A and hG123A, and their K values for inhibition of [3 H]nisoxetine binding were decreased 3-4-fold and 4-6-fold, respectively. Transporter turnover was reduced to 65% of hNET for hG117A and hR121G and to 28% for hG123A, suggesting that substrate translocation is impaired. K values of nisoxetine and desipramine for inhibition of [H-3]norepinephrine uptake were increased by 5-fold for hG117A, with no change for cocaine. The K-i value of cocaine was increased by 3-fold for hG123A, with no change for nisoxetine and desipramine. However, there were no effects of the mutations on the K-d of [H-3]nisoxetine binding or K-i values of desipramine or cocaine for inhibition of [H-3]nisoxetine binding. Hence, glycine residues of the GXXXRXG motif are important determinants of NET expression and function, while the arginine residue does not have a major role. This study also showed that antidepressants and psychostimulants have different NET binding sites and provided the first evidence that different sites on the NET are involved in the binding of inhibitors and their competitive inhibition of substrate uptake. (C) 2002 Elsevier Science B.V. All rights reserved

Roles of transmembrane domain 2 and the first intracellular loop in human noradrenaline transporter function: pharmacological and SCAM analysis

The aim was to investigate the roles of transmembrane domain 2 and the adjacent region of the first intracellular loop in determining human noradrenaline transporter (hNET) function by pharmacological and substituted-cysteine accessibility method (SCAM) analyses. It was first necessary to establish a suitable background NET for SCAM. Alanine mutants of endogenous hNET cysteines, hC86A, hC131A and hC339A, were examined and showed no marked effects on expression or function. hNET and the mutants were also resistant to methanethiosulfonate (MTS), ethylammonium (MTSEA) and MTStrimethylammonium (MTSET). Hence, wild-type hNET is an appropriate background for production of cysteine mutants for SCAM. Pharmacological investigation showed that all mutants except hT99C and hL109C showed reduced cell-surface expression, while all except hM107C showed a reduction in functional activity. The mutations did not markedly affect the apparent affinities of substrates, but apparent affinities of cocaine were decreased 7-fold for hP97C and 10-fold for hF101C and increased 12-fold for hY98C. [H-3]Nisoxetine binding affinities were decreased 13-fold for hP97C and 5-fold for hF101C. SCAM analysis revealed that only hL102C was sensitive to 1.25 mM MTSEA, and this sensitivity was protected by noradrenaline, nisoxetine and cocaine. The results suggest that this region of hNET is important for interactions with antidepressants and cocaine, but it is probably not involved in substrate translocation mechanisms

Tyrosine residue 271 of the norepinephrine transporter is an important determinant of its pharmacology

The aim was to examine the functional importance in the norepinephrine transporter (NET) of (i) the phenylalanine residue at position 531 in transmembrane domain (TMD) 11 by mutating it to tyrosine in the rat (rF531Y) and human (hF531Y) NETs and (ii) the highly conserved tyrosine residues at positions 249 in TMD 4 of human NET (hNET) (mutated to alanine: hY249A) and 271 in TMD 5, by mutating to alanine (hY271A), phenylalanine (hY271F) and histidine (hY271H). The effects of the mutations on NET function were for uptake of the substrates, examined by expressing the mutant and wildtype NETs in COS-7 cells and measuring the K-m and V-max for uptake of the substrates, [H-3]norepinephrine, [H-3]MPP+ and [H-3]dopamine, the K-D and B-max for [H-3]nisoxetine binding and the K-i of the inhibitors, nisoxetine, desipramine and cocaine, for inhibition of [H-3]norepinephrine uptake. The K-m values of the substrates were lower for the mutants at amino acid 271 than hNET and unaffected for the other mutants, and each mutant had a significantly lower than NET for substrate uptake. The mutations at position 271 caused an increase in the K-i or K-D values of nisoxetine, desipramine and cocaine, but there were no effects for the other mutations. Hence, the 271 tyrosine residue in TMD 5 is an important determinant of NET function, with the mutants showing an increase in the apparent affinities of substrates and a decrease in the apparent affinities of inhibitors, but the 249 tyrosine and 531 phenylalanine residues do not have a major role in determining NET function. (C) 2001 Elsevier Science B.V. All rights reserved

Pharmacological properties of the naturally occurring Ala457Pro variant of the human norepinephrine transporter

Recently, another reserach group has reported an almost complete loss of function of the human norepinephrine transporter (hNET) in patients who had orthostatic Intolerance and who were heterozygous for a guanine to cytosine exchange, resulting in a hNET Ala(457) Pro variant. To explore the reason for the deficiency in NET function, we compared in detail the pharmacology of the Ala(457) Pro variant with that of the wild-type hNET in COS-7 cells transiently transfected with hNET or Ala(457)Pro cDNA. Compared to the wild-type hNET, the Ala(457)Pro variant exhibited a five-fold higher affinity for cocaine, but a twofold lower affinity for the NET inhibitor nisoxetine, and an unchanged affinity for the antidepressant desipramine. Plasma membrane expression (measured as B-max of [H-3]nisoxetine binding) of the Ala(457)Pro variant was only 40% of that of the wild-type hNET. The Ala(457)Pro variant showed a six- to 10-fold decrease in affinity for the substrates dopamine and 1-methyl-4-phenylpyridinium (MPP+). Compared with the wild-type hNET, the maximum rate (V-max) of norepinephrine uptake by the Ala(457) Pro variant was slightly reduced, whereas the turnover number (calculated from V-max/B-max) was approximately two-fold higher. However, the Ala(457) Pro variant exhibited a 50-fold higher K-m (i.e. lower apparent affinity) for norepinephrine than the wild-type hNET. Thus, the previously reported loss of function of the Ala(457)Pro variant associated with orthostatic intolerance is only partly due to a reduction in plasma membrane expression of the transporter, and is mainly caused by the pronounced reduction in the apparent affinity of norepinephrine

Potencies of haloperidol metabolites as inhibitors of the human noradrenaline, dopamine and serotonin transporters in transfected COS-7 cells

Extrapyramidal symptoms, such as tardive dyskinesia, often develop in patients on long-term treatment with haloperidol. It has been proposed that these symptoms could be caused by neurotoxic effects of haloperidol metabolites following uptake by monoamine transporters, in an analogous mechanism to the neurotoxic effect of MPP+ (1-methyl-4-phenylpyridinium) metabolised from MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine). In this study, the hypothesis was partially investigated by determining the potencies of haloperidol and reduced haloperidol and the corresponding pyridinium and tetrahydropyridine metabolites, compared with MPP and MPTP, as inhibitors of the noradrenaline transporter (NAT), dopamine transporter (DAT) and 5-HT transporter (SERT). Two days after COS-7 cells were transiently transfected with the cDNA for the human NAT, DAT or SERT (Lipofectamine method), the cells were incubated with 10 nM [H]noradrenaline, dopamine or 5-HT, respectively, for 2 min at 37 °C, in the absence or presence of various concentrations of the eight compounds or a specific uptake inhibitor (NAT: nisoxetine 1 μM; DAT: GBR 12909 1 μM; SERT: citalopram 10 μM). Specific amine uptake (fmol/mg protein) was calculated as the difference in uptake in the absence and presence of the specific uptake inhibitor. K(i) values were calculated for the eight compounds for inhibition of NAT, DAT and SERT. Haloperidol, its five metabolites and MPP and MPTP all inhibited NAT, DAT and SERT. For the pyridinium and tetrahydropyridine metabolites of haloperidol, there were not marked differences between their potencies as inhibitors between each other for NAT or DAT or between NAT and DAT, with all of the K(i) values in the range of 5.8-16 μM. However, there were more marked differences for SERT, with all but one of the metabolites showing selectivity for inhibition of SERT relative to NAT and DAT. Haloperidol and reduced haloperidol had similar inhibitory potencies for all three transporters, and were clearly less potent than the other haloperidol metabolites only for inhibition of SERT. The lack of correlation between the inhibitory potencies of the haloperidol metabolites and their structural analogues, MPTP and MPP, suggests that they are not likely to cause neurotoxicity by a mechanism analogous to that of the latter neurotoxin

The rat norepinephrine transporter: Molecular cloning from PC12 cells and functional expression

The rat norepinephrine transporter (rNET) cDNA from the PC12 pheochromocytoma cell line has been cloned by RT-PCR and characterized. The cDNA encodes an integral membrane protein consisting of 617 amino acids which contains twelve putative transmembrane domains, two potential N-glycosylation sites, two potential phosphorylation sites for protein kinase C and one phosphorylation site for casein kinase II. The nucleotide and deduced amino acid sequence shows a high level of homology to the human and the bovine norepinephrine transporter and less homology to the rat dopamine transporter (rDAT). Heterologous expression of rNET in HEK293 cells revealed that uptake of [H]norepinephrine is sodium- and chloride-dependent and highly sensitive to the selective norepinephrine transporter inhibitors desipramine and nisoxetine. The cloned rNET cDNA provides the opportunity to investigate this transporter in heterologous expression systems and adds a new member to the family of sodium- and chloride-dependent neurotransmitter transporters

The personal response - A novel writing assignment to engage first year students in large human biology classes

The teaching of highly valued scientific writing skills in the first year of university is challenging. This report describes the design, implementation, and evaluation of a novel written assignment, The Personal Response and accompanying Peer Review, in the course, Human Biology (BIOL1015) at The University of Queensland. These assignments were the first assessment tasks of the course and were set early in the first semester of university. BIOL1015 had a diverse cohort of 319 first year students from five bachelor degree programs, primarily from Pharmacy and Human Movement Studies. Audio files in the form of interviews with eminent biomedical scientists were obtained from a leading public radio program. Students used these files as triggers to submit a short but highly structured assignment written from a personal perspective and in an expressive style. Evaluations revealed that overall, students found the task interesting and challenging. Students performed well, regardless of their background knowledge, disciplinary interest, or preference for topics within human biology. This study demonstrated that The Personal Response was an appropriate task for these first year students of human biology. It represents an alternative to traditional essay writing

A metacognitive activity to enhance student understanding of complexity of a threshold concept in biology

Background, Aims and Methods Threshold concepts are transformative, but also likely to be troublesome, for undergraduate students. Metacognitive activities that expose students to the structural complexity of a threshold concept and are organized in terms of the Structure of Observed Learning Outcomes (SOLO) taxonomy have been shown to improve student learning outcomes in a third year engineering course (Meyer et al., 2015). The current study aimed to emphasise to a large cohort of first year biology students the structural complexity of the concept of ‘cell membrane transfer’ and improve their understanding of the concept. The metacognitive activity was divided into several parts. In the first stage, students were asked to answer an open-ended question related to how transfer of substances occurs across the cell membrane. Following this, the students were asked to mark their own answer on a scale of 1-10 and provide justification of their marking by selecting one of statements 1-5, which were ascending in complexity based on the SOLO taxonomy. Subsequently, students were provided with 9 model answers to the question, which varied in structural complexity, and were asked to mark the answers out of 10. This was followed by an instructor explaining their marking of the 9 answers and justification of the marks. Lastly, students were asked to revisit their own answer and re-mark their answer out of 10 and provide justification. After the class, the instructor marked each student response, providing a score and justification, which could be compared to students’ pre- and post-scores and justification. Results and Discussion In our study, it was evident that students find it difficult to identify the variation in complexity of a threshold concept. More than 50% of students were unable to match the instructor score for each model answer, with the exception of only the least complex, and hence lowest scored, answer. The self-assigned student post-score of their own answers was marginally greater than the instructor’s score (