An interspecific functional complementation test in Drosophila for introductory genetics laboratory courses

Introductory genetics courses often include evolutionary genetics concepts such as sequence homology and functional conservation. It is usually assumed that two sequences showing homology (i.e., sharing a common ancestral sequence) perform the same molecular function. The correlation, however, does not always hold true, and evidence for functional conservation must come from functional studies. In this study we describe a genetics laboratory class that demonstrates functional conservation between the Drosophila protein Muscleblind (Mbl) and its human ortholog MBNL1. We use the Gal4/UAS system to express MBNL1 in a Drosophila mutant background and measure the in vivo activity of the human protein by rescue of mbl mutant phenotype in embryos. As a control, ubiquitous expression of Drosophila MblC, one of the four protein isoforms encoded by the gene, increased by 71% the viability of mbl mutant embryos and greatly reduced the hypercontracted abdomen of mutant larvae. In a parallel experiment, human MBNL1 provided a robust rescue of the embryonic lethality (78%) and improved abdomen hypercontraction as well. Under both conditions, rescued larvae die as first instars, probably due to overexpression effects, lack of alternative protein isoforms, or incomplete expression in critical tissues such as the nervous system. The use of two constructs in the rescue experiment (UAS-mblC and UAS-MBNL1) and the incomplete rescue prompt several questions for students. The fact that a human protein works in a Drosophila cellular context illustrates the use of an in vivo test to prove functional conservation.     

Introducing student inquiry in large introductory genetics classes

An appreciation of genetic principles depends upon understanding the individual curiosity that sparked particular investigations, the creativity involved in imagining alternative outcomes and designing experiments to eliminate these outcomes, and the clarity of thought necessary to convince one's scientific peers of the validity of the conclusions. At large research universities, students usually begin their study of genetics in large lecture classes. It is widely assumed that the lecture format, coupled with the pressures to be certain that students become familiar with the principal conclusions of genetics investigations, constrains most if not all departures from the formats textbooks used to explain these conclusions. Here I present several examples of mechanisms to introduce meaningful student inquiry in an introductory genetics course and to evaluate student creative effort. Most of the examples involve altered student preparation prior to class and additional in-class activities, while a few depend upon a smaller recitation section, which accompanies the course from which the examples have been drawn. I conclude that large introductory classes are suitable venues to teach students how to identify scientific claims, determine the evidence that is essential to eliminate alternative conclusions, and convince their peers of the validity of their arguments.     

Introductory biology courses: a framework to support active learning in large enrollment introductory science courses

Active learning and research-oriented activities have been increasingly used in smaller, specialized science courses. Application of this type of scientific teaching to large enrollment introductory courses has been, however, a major challenge. The general microbiology lecture/laboratory course described has been designed to incorporate published active-learning methods. Three major case studies are used as platforms for active learning. Themes from case studies are integrated into lectures and laboratory experiments, and in class and online discussions and assignments. Students are stimulated to apply facts to problem-solving and to learn research skills such as data analysis, writing, and working in teams. This course is feasible only because of its organizational framework that makes use of teaching teams (made up of faculty, graduate assistants, and undergraduate assistants) and Web-based technology. Technology is a mode of communication, but also a system of course management. The relevance of this model to other biology courses led to assessment and evaluation, including an analysis of student responses to the new course, class performance, a university course evaluation, and retention of course learning. The results are indicative of an increase in student engagement in research-oriented activities and an appreciation of real-world context by students.     

遗传学精品课程改革与建设

精品课程是教育部全面提高高等学校教学质量的质量工程项目之一,结合遗传学国家级精品课程建设,从课程体系、教学内容体系、教材体系、教学方法、实践教学体系等方面对遗传学精品改革与建设进行了介绍。     

Design and implementation of an introductory course for computer applications in molecular genetics

Formal training in computational biology was initiated at Wayne State University in 1990 to meet the needs of the faculty. This was still at a time when the molecular databases and analysis tools could be housed in what is now equivalent to a modern but dated desktop computer. In 1995 the course was expanded to include graduate students to provide these senior students with a foundation in computational biology. This course has armed our students with a requisite set of basic skills that are necessary for a successful career in molecular genetics. It is now an integral component of the graduate program of the Center for Molecular Medicine and Genetics and our experiences in course delivery have been detailed (BioInformatics Methods and Protocols, S. Misener and S. A. Krawetz, eds., Humana Press, Totowa, NJ, 2000.). The course was expanded to a campus-wide unlimited enrollment program for the summer of 2000 to address the needs of our student body. In this review we present our experience with delivering a multidisciplinary campuswide computational biology course to a new and widely diverse student body.     

Conservation genetics of an endangered orchid in eastern Canada

Platanthera leucophaea, the Eastern Prairie Fringed-orchid, is a globally imperilled species native to the USA and Canada, with its Canadian distribution limited to the Province of Ontario. In Canada, where P. leucophaea is listed as endangered, approximately 40 % of populations have been extirpated in recent years, and many remaining populations have experienced substantial declines. In this study, we investigated whether reduced population sizes have led to low genetic diversity and inbreeding. We also investigated the extent to which hybridization with Platanthera psycodes may be threatening the genetic integrity of P. leucophaea populations. We found that overall, genetic diversity is low, and inbreeding is high. This is despite evidence of regular gene flow between proximate populations, although more distant populations show high levels of genetic differentiation. At sites where P. leucophaea is sympatric with P. psycodes, interspecific hybridization occurs in a bidirectional manner, i.e. with both parental species acting as either pollen donor or pollen recipient. Inbreeding and low genetic diversity in all populations, and hybridization in some populations, may pose future threats to P. leucophaea, and should be considered in the future by biodiversity managers.     

Lack of impact of undergraduate genetic courses on the teaching of medical genetics.

The impact of undergraduate genetic courses on the academic performance of first-year medical students in the medical genetics course at the University of Pittsburgh School of Medicine was evaluated over a period of 9 years. Comparisons were made between medical students who had taken a formal undergraduate course in genetics and those who had not. Little if any differences were found in the academic performance in the medical genetics course between these two groups of students. Perhaps the design of undergraduate courses in genetics should be re-evaluated to give more depth to the medical student's preparation for appreciating the significance of genetics in normal and abnormal human variation.     

Gregor Mendel's classic paper and the nature of science in genetics courses

The discoveries of Gregor Mendel, as described by Mendel in his 1866 paper Versuche uber Pflanzen-Hybriden (Experiments on plant hybrids), can be used in undergraduate genetics and biology courses to engage students about specific nature of science characteristics and their relationship to four of his major contributions to genetics. The use of primary source literature as an instructional tool to enhance genetics students' understanding of the nature of science helps students more clearly understand how scientists work and how the science of genetics has evolved as a discipline. We offer a historical background of how the nature of science developed as a concept and show how Mendel's investigations of heredity can enrich biology and genetics courses by exemplifying the nature of science.     

Mammalian cell genetics. 3. Characterization of x-ray-induced forward mutations in Chinese hamster cell cultures

X-irradiation induces forward mutations from 8-azaguanine sensitvity to resistance in Chinese hamster cells in culture. At this locus the number of induced mutations increases non-linearly with X-ray exposure. The mutation rate increase from 4.2·10⁻⁷ per locus per R with 200 R to 1.8·10⁻⁶ per locus per R with 1200 R. Several factors including cell density markedly influence the mutational yield. Reversion tests using specific chemical mutagens on 72 randomly isolated, azaguanine-resistant mutants suggest that both point mutations and chromosome deletions might have occurred in the hamster cells after exposure to ionizing radiation.     

Using the Genetics Concept Assessment to document persistent conceptual difficulties in undergraduate genetics courses

To help genetics instructors become aware of fundamental concepts that are persistently difficult for students, we have analyzed the evolution of student responses to multiple-choice questions from the Genetics Concept Assessment. In total, we examined pretest (before instruction) and posttest (after instruction) responses from 751 students enrolled in six genetics courses for either majors or nonmajors. Students improved on all 25 questions after instruction, but to varying degrees. Notably, there was a subgroup of nine questions for which a single incorrect answer, called the most common incorrect answer, was chosen by >20% of students on the posttest. To explore response patterns to these nine questions, we tracked individual student answers before and after instruction and found that particular conceptual difficulties about genetics are both more likely to persist and more likely to distract students than other incorrect ideas. Here we present an analysis of the evolution of these incorrect ideas to encourage instructor awareness of these genetics concepts and provide advice on how to address common conceptual difficulties in the classroom.     

Animal care courses: helping fulfill the mandate of animal care committees in Canada

Animal Care Committees (ACCs) at Canadian universities and research centers operate under the aegis of the Canadian Council on Animal Care (CCAC) and its guidelines for the humane care and treatment of animals in teaching, research, and testing. All Canadian universities have at least one active committee. The committees are expected to assume an educative role beyond the provision of information concerning housing, maintenance, and appropriate conditions for the treatment of animals in research. This includes critical examination of the serious ethical issues involved in animal research within the context of the principles and practices endorsed by the CCAC. One-day animal care courses provided by ACCs at three Canadian universities are described. Comparisons are made between the content and structure of curricula and the ways these relate to the teaching and research mandate in each institution, focusing particularly on the teaching of ethics in each course. The implications for heightening awareness of ethical issues in animal research and improving the effectiveness of these courses are discussed.     

Population genetics of hereditary hemochromatosis in Saguenay Lac-Saint-Jean (Quebec, Canada).

Hereditary hemochromatosis (HH) is an autosomal recessive disorder that has a high prevalence in Caucasian populations. Based on HLA typing in 18 families, the gene frequency was estimated 0.12. The homozygote frequency was 0.014 and the heterozygote frequency was 0.21 in Saguenay Lac-Saint-Jean (SLSJ), a geographically isolated region of northeastern Quebec. The genealogical reconstruction showed that 15 of the 57 obligate carriers of the HH gene could be traced back to a unique ancestor in the 18th century. The mean coefficients of inbreeding and kinship were 17 and 15 times, respectively, higher in the HH group than in three control groups. The values of both coefficients were much higher than those found in other HH populations and in most of the other recessive disorders prevalent in SLSJ.