LASPAU: Informativo, Fall 2004

By Eugenia M. del Pino*, Departamento de Ciencias Biológicas, Pontificia Universidad Católica del Ecuador, Quito, Ecuador

Thirty years ago, immediately after having completed a Ph.D. degree in Biology at Emory University (Atlanta, GA, USA, 1972), I began teaching developmental biology in Ecuador. My studies at Vassar College (Poughkeepsie, NY) and Emory University were sponsored by the Latin American Scholarship Program of American Universities (LASPAU), an organization that contributes to the teaching of science in Latin American universities. By accepting the LASPAU fellowship, I made a commitment early in my scientific career to teach and conduct academic work in an Ecuadorian setting. However, I chose developmental biology as my field—an area which to date is poorly represented in Latin America (del Pino, 1998). In fact, the Latin American Network of Biological Sciences (RELAB) recognizes that high priority research fields such as molecular biology and developmental biology are underrepresented in Latin America and has further concluded that local, regional, and international efforts need to be concentrated in these areas of research to facilitate the scientific advancement of the Latin American region.

My thesis advisor was Asa A. Humphries Jr., who was a student of Gerard Fankhauser, an embryologist trained in the classical school of embryology (Fankhauser, 1972). My dissertation dealt with the role of the egg jelly coats of the Xenopus egg in the union of gametes (del Pino, 1973). I was highly motivated to study animal development, and when I returned to Ecuador after completion of my training, I wanted to continue doing

experimental work. In Ecuador, I had no access to the model organism, the frog Xenopus. I therefore searched for an accessible frog to use for my studies. I found it in the gardens of the university; it is a “marsupial” frog, the hylid Gastrotheca. At my request, my former advisor, Asa A. Humphries, Jr. searched the literature. He wrote me a letter in which he explained that nothing was known about the development of the marsupial frogs. He added that I could make a successful career by studying these frogs. I followed his advice, and most of our scientific work has concentrated on questions of marsupial frog development (del Pino, 1989a).

Thirty years ago, because of my recently acquired expertise, the Pontificia Universidad Católica del Ecuador (PUCE) in Quito, introduced an “Embryology” course as a core requirement for biology students. Originally we trained high school biology teachers. Since 1976, the PUCE has offered a degree in Biology after eight semesters of study and submission of a thesis based on original research. Developmental biology continues to be a core subject. It is a five-credit course given in the fifth semester. Students attend three hours of lecture and one three-hour laboratory session each week. The enrollment is approximately 25 students. I taught both the lectures and laboratory sessions for many years, but recently other members of the faculty have taken over the laboratory sessions. Additionally, I offer three-credit elective seminars on developmental biology to students in the fifth and sixth semesters of their studies. Four to eight students may enroll in these elective courses. Developmental biology is not immediately applicable for the future employment of most Ecuadorian biologists. However, I consider that an introduction to this important area of biology is valuable for students all over the world because the study of developmental biology allows the integration of concepts derived from various branches of biology, including ecology and evolution. Moreover, the highly conserved molecular mechanisms of development provide extraordinary examples of the unity of biology. In addition, complex structures, such as the brain, can be more easily understood when studying embryos.

My teaching career began in 1972, immediately after I returned from the USA. I was invited to give an intensive seminar on embryology to advanced students from the Universidad Estatal de Guayaquil. I remember spending most of the day preparing for my daily two-hour lecture by reading Davidson (1968). I had never encountered another group of students with such an intense interest in what I was explaining. I also realized that my lectures were quite strange to them. Immediately after this, I started to teach embryology in Quito. (An outline of the contents of the 2001 Development course is included in Table 1.)

TABLE 1: Outline of the Developmental Biology Lecture Course*

Theme

Description

1
2
3
4
5
6
7
8
9
10

Introduction to developmental biology: Basic concepts
Axis formation in the frog and other vertebrates
Germ layers and the vertebrate body plan
Development of the mesoderm and endoderm
Neural development
Cleavage patterns and blastula formation in vertebrates
Vertebrate gastrulation and the formation of the neural tube
Drosophila development
Germ cells and fertilization
Development and evolution

* Based on the 2001 developmental biology semester course, with three lectures and one three-hour laboratory session per week (see the outline in Table 2). Wolpert et al. (1998) was used as textbook. Grading system: The university requires three preliminary grades and a final examination. My tests consist of four essay questions. Each answer must be no more than one page. Class presentations are also graded.

I discovered that three textbooks of embryology had been translated into Spanish: Brachet (1975); Balinsky (1978); and Patten (Carlson, 1990). I used these books as references for my lectures. I have also benefited from the collaboration of many colleagues who have donated textbooks to me for my teaching, including favorite textbooks such as Wolpert et al. (1998) and Gilbert (2000). At first, my students depended heavily on the notes that they took during lectures. My lecturing method included extensive use of the blackboard, and I repeated the main ideas more than once, using different words. As a result, however, many inaccuracies were incorporated into the students’ notes and, unfortunately, into their learning.

My lecture notes were short annotations, which I normally discarded after each session. However, in 1985 I acquired a personal computer, which allowed me to have neatly organized lecture notes. The students began to photocopy my lecture notes. Soon, I was preparing copies of the lecture notes as handouts to give to students before each lecture. Instead of freely talking about the subject, I learned to adhere to the lecture notes. The “learning” results were excellent. Students concentrated on listening to the explanations of the text that they had in front of them. This method facilitated the transmission of accurate information and more active participation of students in the classroom. For the first time in my teaching career, I kept my lecture notes. Each year, I improved my class notes, and in 1989 the university printed my textbook of animal development (del Pino, 1989b). I used this textbook successfully for several years.

During my career, I have witnessed the expansion of the field of developmental biology. Because it is growing at such a fast pace, textbooks become outdated quickly! I have switched to the use of textbooks in English for the teaching of developmental biology, and I have also changed my teaching method. I have reduced my own lecturing. Instead, I complement and supplement student presentations. I also encourage discussion. I may assign a group of two to four students to read and prepare the material that we will cover in a given session. They can consult with me about any doubts that they may have. Students make an oral presentation of the assigned material, which corresponds to a few pages of the textbook, for example Wolpert et al. (1998). Students often prepare overhead transparencies of good illustrations in this and similar books, or they bring illustrations that they have found on the Internet. Additionally a few students have acquired copies of the textbook. There is normally excellent class participation. Students learn to read and understand new material, a skill that should be useful in their future professional life. Moreover, students acquire the experience of talking in front of a group of people. We adhere to the textbook, avoiding the introduction of errors into their notes. The main disadvantage is that these textbooks are in English. However, our students have English reading ability.

To enhance the laboratory sessions, my colleagues have made extensive use of the excellent Web sites now available on the subject of development. Students are assigned to search for information, for example, about a model organism. They present their findings during the laboratory session. The excellent images that they find on the Web are a valuable complement to the laboratory exercises. Additionally, we use a videotape on amphibian embryogenesis and one about gastrulation in Xenopus. These videos were kindly provided by Horst Grunz (University of Essen, Germany; http://www.uni-essen.de/zoophysiologie/) and David Shook (University of Virginia; available by download at http://faculty.virginia.edu/shook/ShowMovies/), respectively.

Two different activities are conducted during each three-hour laboratory session. The first is a presentation of a model organism for development, based on textbook descriptions and the excellent material now available in the Internet. Groups of two to three students give these presentations, and the instructor adds additional information. Other activities include the study of frog and chick embryos in sections. Students often observe living chick embryos. Federico D. Brown taught the laboratory sessions in 2001 (Table 2).

In addition, as in the year 2001, students may be required to conduct an independent research project. Since we have only limited resources, these projects are often quite modest, and not very successful. In the 2001 course, four to five students conducted each project. They chose an organism, went to the field to collect samples, and observed the developmental processes. Students analyzed the morphology of development of two different frog and fish species. Additionally, they analyzed the gonads of frogs, mouse, and fish. Other students observed eggs in Drosophila, a moth, and a snail. The results were written up in the style of a scientific report, and each group of students also gave an oral presentation on the subject. For these presentations, the students made extensive use of resources found on the Internet.

I greatly enjoy teaching developmental seminars to small groups of students. During each session, half of the time is used for the presentation of assigned textbook chapters, such as from Gilbert (2000). The method is the same as that described in the lecture course. We cover two to three chapters of this book during the semester. During the second part of each session, we analyze recent literature, choosing papers that are not necessarily related to the assigned chapters. First, we read and understand the title and abstract of the article that we are studying. We then analyze the figures and tables with reference to the results and the abstract. Students really enjoy learning to read a paper analytically. In addition, students participate in experimental work that is being conducted in my laboratory. Their results are presented as a scientific report, written in the format of a thesis. The availability of developmental literature on the Internet is a valuable tool, as our library does not subscribe to biological journals. Students can now access research articles that are freely available; for example, the journal Development allows free access to older articles on its Web site.

The 1999 seminar course was particularly successful because the five participants not only learned new methodologies, but also became particularly interested in development. Later, all of them conducted research and prepared theses in developmental biology with my guidance. Just before this course started, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting methods were implemented in my laboratory, thanks to help from Georg Krohne (University of Würzburg, Germany) and his student Carmen Lang. She used these methods to study lamina-associated polypeptide 2 (LAP2) expression in cells of the marsupial frog Gastrotheca. I decided to demonstrate these techniques to the seminar participants, and in this way to improve my confidence with these methods. In the seminar, we analyzed the article by Lang et al. (1999), then in press, among others. This article provided the background for our experimental work. The course participants were thrilled to have the experience of running a gel (see photo on page 4). Each student loaded one or two gel lanes in the single gel that we ran during the course. The proteins were transferred to a nitrocellulose membrane and immunoblotted with a LAP2-specific antibody. The results were excellent, and as themes for their theses, the entire class studied LAP2 expression patterns in different fish and amphibians. Later, this collaborative work was published (del Pino et al., 2002), including the first blot, produced during the course. Similarly, some students who participated in these seminars have at other times done their undergraduate theses in developmental biology. Their collaboration has been welcome, for it has advanced our scientific work.

Not only the teaching of developmental biology, but also research in this field needs to be further emphasized in Latin America. In particular, the rich biodiversity of the region can provide alternative organisms for the analysis of development. Those studies may complement the information obtained from other model organisms, such as the frog Xenopus. Advancement of research and teaching of development can be further strengthened by international collaboration. Although developmental biology is not immediately applicable in Ecuadorian society, I believe that the opportunities for intellectual training it provides are important for scientists generally. That intellectual training includes the ability to interrelate concepts derived from various branches of biology and the knowledge of the highly conserved molecular mechanisms of development.

I thank I. Alcocer and F. D. Brown for introducing Internet tools into the teaching of Development laboratory sessions. I am grateful to Horst Grunz and David Shook for providing us with copies of their videos. Finally, I wish to recognize the help of the Pontificia Universidad Católica del Ecuador for allowing me to teach developmental biology in Ecuador. I thank G. M. Malacinski and S. Duhon for critical reading of the manuscript.

Balinski, B.I. (1978). Introducción a la embriología (translation of the third edition). Ediciones Omega, Barcelona.

Brachet, J. (1975). Introducción a la embriología molecular. H. Blume Ediciones, Madrid.

Carlson, B.M. (1990). Embriología básica de Patten. 5th edn. Interamericana. McGraw-Hill, Mexico.

Davidson, E.H. (1968). Gene activity in early development. Academic Press, New York.

del Pino, E.M. (1973). Interactions between gametes and environment in the toad Xenopus laevis (Daudin) and their relationship to fertilization. J. Exp. Zool. 185: 121–132.

del Pino, E.M. (1989a). Modifications of oogenesis and development in marsupial frogs. Development 107: 169–187.

del Pino, E.M. (1989b). Desarrollo embriónico temprano en los animales. Ediciones de la Pontificia Universidad Católica del Ecuador, Quito.

del Pino, E.M. (1998). Basic research and university training: Developmental biology in Latin America. In Wissenschaftleraustausch und Entwicklungszusammenarbeit vor der Jahrtausendwende. (Ed. A. von Humboldt Foundation) Nomos-Verlag, Baden-Baden, pp. 211–214.

del Pino, E.M., Sáenz, F.E., Pérez, O.D., Brown, F.D., Ávila, M.E., Barragán, V.A., Hadtad, N., Paulin-Levasseur, M. and Krohne, G. (2002) The LAP2 (lamina-associated polypeptide 2) expression in fish and amphibians. Int. J. Dev. Biol. 46: 327–334.

Gilbert, S.F. (2000). Developmental Biology. 6th edition. Sinauer Associates, Sunderland.

Lang, C., Paulin-Levasseur, M., Gajewski, A., Alsheimer, M., Benavente, R. and Krohne, G. (1999). Molecular characterization and developmentally regulated expression of Xenopus lamina-associated polypeptide 2 (XLAP2). J. Cell Sci.112: 749–59.

Wolpert, L., Bedtington, R., Brockes, J., Jessell, T., Lawrence, P. and Meyerowitz, E. (1998). Principles of Development. Current Biology Ltd., London.