The Development and Validation of a Classroom Environment Scale for Filipinos

Classroom Psychosocial Environment

VOLUME 8    2008

VOLUME 7    2007

VOLUME 6    2006

VOLUME 5    2005

VOLUME 4    2004

VOLUME 3    2003

VOLUME 2    2002

VOLUME 1    2001

Copyright © 2001 NISMED.
For comments/suggestions, email the webmaster.

Antheridial Development from the Isolated Protoplast of Young Gametophyte of Tree Fern Cyathea contaminans (Hook) Copel.: A Scientific Approach 
to Teaching about Spermatogenesis

Rodolfo S. Treyes, Toshiyuki Kawakami & Hideo Ikeda
Faculty of Education, 
Hiroshima University, 
Higashi-Hiroshima, 
739-8523 Japan

AbstractMaterials & MethodsResultsDiscussion
ReferencesAppendix

Introduction

Cell culture has great significance in the in-vitro investigation of various biological processes, such as gametogenesis.  Using the cell-culture method, the process of cell differentiation can be clearly comprehended by students.  At present, several species of plants are used for cell culture. The method has been successfully applied in investigating the reproductive cells of ferns.

Ferns are versatile experimental systems for studying vascular plant morphogenesis (Dyer, 1979).  They are widely used as experimental materials, both in unicellular form in the first haploid stage (spore) and as multicellular tissues with complex cell differentiation (Nakamura & Maeda, 1994).

As free-living organisms, the gametophytes (prothallia) of ferns are considered effective and interesting pedagogical tools in introductory and advanced investigative exercises and in research projects in biology.  One of the most attractive features of ferns for biological studies is that their gametophyte is a free-living form that develops from a single-celled spore and grows independently into a sporophyte. This makes investigations of their reproductive cells easy and convenient. Various biological phenomena can be easily understood by using ferns for classroom inquiry and scientific pursuits. Watanabe and Ikeda (1994) and Watanabe, Treyes and Ikeda (1998) have developed some improvised methods and observations using ferns for classroom activities. Using a cell-culture method they developed, their students were able to independently perform an investigation and learn various laboratory techniques. Their students observed the development of the male sex organ (antheridium) and the process of spermatogenesis, both of which are considered remarkable cytological events.  Their students observed spermatogenesis occurring within the antheridia, the simple organs that develop on the surface of the prothallia.

Prothallial culture is the primary step for in-vitro study of the reproductive cells in ferns. Culturing fern prothallia involves growth hormones that support the developmental processes of the cultures and stimulate the development of the reproductive organs in ferns.  Some gibberellic acids have been tested as antheridial growth inducers. Positive results have been obtained by Schraudolf (as cited in Naff, 1979) and Voeller (as cited in Naff, 1979) using gibberellin A₃ (GA₃) on the following fern species: Lygodium japonicum, L. flexuosum, Mohria caffrorum and species of the genus Anemia.  In the study of Voeller (as cited in Naff, 1979), gibberellin A₃ failed to hasten antheridium formation in some species of the family Osmundaceae and Cyatheaceae.   Naff (1979) noted that adding GA₃ to the medium induces antheridial development in cultures of schizaeaceous species.

In the preliminary experiment on Cyathea, (common name, tree fern), our objective was to observe the differentiation of the antheridium in-vitro. We investigated the influence of GA₃ on the development of the antheridium from the isolated primordial cell.  The result revealed that GA₃ did not induce antheridial development  (Treyes, 2000).

In the studies conducted by Maeda, Sugimoto, Nakamura, Masuda, Kaneko and Sugai (1990), gametophyte was formed from the isolated protoplasts of the young sporophytes in the fern Lygodium japonicum. The isolated protoplasts generated cordate prothallial growth, producing both antheridia and archegonia.  These studies showed that in addition to GA₃, other growth substances secreted by some fern species influence the formation of reproductive organs.  Banks, Hickok and Ebb (1993) reported that antheridiogen, a pheromone that is secreted by the hermaphrodite prothallia, is a determinant of sex type. This antheridiogen promotes antheridial development.   Chiou and Farar (1997) reported that antheridiogen secreted by mature fern gametophytes promote antheridium formation in other nearby normally developing gametophytes.

This paper describes the antheridial development of C. contaminans in response to GA₇ treatment.   It also describes a simple laboratory activity that offers students an opportunity to perform simple cell cultures in order to observe the processes of spermatogenesis and mitosis.  The activity gives students classroom experience in:

1. performing spore culture techniques;

2. performing simple controlled experiments; and

3. developing testable hypotheses concerning the effects of varying concentrations of growth hormones on antheridial development.

Most students are acquainted with diverse biological concepts but often they have difficulty in relating these concepts to real-life situations.  Furthermore, students—and teachers as well—think that learning biological processes in the laboratory requires highly sophisticated equipment and deep level of scientific knowledge.  The suggested laboratory activity involves the use of simple equipment and materials that can be made readily available to students so they can perform the activity on their own.

AbstractMaterials & MethodsResultsDiscussion
ReferencesAppendix