Book Review: Genetics

The five subject areas covered are, Observations of Chromosomes: Basic Techniques, Complimentary Techniques for the Study of Chromosomes and DNA, Study of Pollen and the Embryo Sac, Production of Interspecific Hybrids Culture of Embryos and Fertilized Ovaries, and Polyploidisation. Each section is prefaced by a brief introduction followed by many procedures used to study the subject in question.

The first subject area is divided into studies of chromosomes during mitosis and meiosis using differing plant tissues. Many of the techniques appear to be nearly identical down to using the same chemicals and tissue sources so at times, there is redundancy. However the variety of techniques abound with lots of choices to try with a tissue not listed but, which may be closely related. The tissues studied to determine number and morphology of chromosomes ranged from root and leaf meri stems to embryos, protoplasts, callus, embryoids, and fungal mycelium. The studies of cells undergoing meiosis dealt almost exclusively with meiosis at the Metaphase I stage with one protocol dealing with meiosis at Prophase 1.

The second subject area, Complementary techniques for the study of chromosomes and DNA, covers the topics of Giemsa-banding, Fluorochrome-banding, Hybridisation in situ, and Cytophotometry and autoradiography. It is stated that, since the first report of chromosome banding using plant material in the early 1970's, most labs have developed their own modifications to the techniques and let word of mouth be the method of dissemination of this new information instead of publication. There are four protocols presented for Giemsa-banding for C-banding-somatic mitosis and only one protocol for C-banding meiosis and N-banding-somatic mitosis. If the editors intent was to bring together modifications done by various investigators, I would have expected more protocols to be presented. Three different staining methods were presented for Fluorochrome-banding. Hybridization in situ dealt with the hybridization of a probe of DNA or RNA with a cytological preparation allowing for the precise location of a complimentary sequence. The techniques presented used radioactively labelled probes, biotin- and fluorescein-labelled rRNA probes, and DNA probes labelled with digoxigenin. The technique of choice would be determined by the method of detection available to the investigator and the degree of resolution desired. Also, many laboratories are moving away from the use of radioactivity and the latter two techniques are nonradioactive in nature. All three techniques are presented in great detail. The cytophotometry and autoradiography portion of this section is very brief but adequate.

The section dealing with the study of pollen and the embryo sac presents five different protocols for staining pollen for determination of fertility. Protocols are also given for observation of pollen germination in situ and in vitro. The techniques for working with embryo sacs differ more with the mode of observation than with the preparation of the tissues. The ovules are fixed in either FAA or FPA and the modes of observation are light field, phase contrast, Nomarski interferential contrast, and interferential contrast microscopy. An improvement to this section would be photographs showing the merits of each form of observation type since the preparation of tissues is so similar.

The section entitled, "Production of interspecific hybrids. Culture of embryos and fertilized ovaries", is quite brief in comparison to the other subjects covered. There is little, if any, information on creating the interspecific hybrids and only slightly more on the culture of embryos produced by crosses. For those wishing to culture embryo and fertilized ovules, a good book on plant tissue culture would be more appropriate to consult. Also one generally thinks of ovules being fertilized, not ovaries.

The final section dealing with Polyploidisation concentrates almost exclusively with treating plantlets, seeds or roots with colchicine. Only one technique uses nitrogen protoxide and it is sketchy, at best. Techniques are given to determine if polyploidisation has taken place. These include measuring of guard cell length, counting of chloroplast number per guard cell, determining the number of nucleolar chromocentromeres, counting the number of stomata per given area and measuring diameter of pollen grains. Nothing is said but, one assumes the bigger or more abundant indicate an increase in ploidy level. The Annexes, or Appendices, contain very little information. The recipes for three stains are presented along with instructions for making permanent mounts and taking photographs. Many of the individual protocols had their own instructions for preparing stains, culture media and fixatives so were not included in the Annexes. However, many of the recipes for stains and other chemical solutions were not included and it will be necessary to find them in other sources.

As presented in the Introduction, this book is intended for use by teachers and students and as an indispensable tool for researchers and laboratory technicians. I would agree about it's use by laboratory technicians, researchers and teachers but I would recommend its use only by advanced students who already have a working knowledge of plant cytogenetic techniques. I would not recommend it for a beginning cytogenetics class without the support of a text explaining the reasons behind the techniques and a more complete list of stains and fixatives. Another drawback to using this text in a classroom setting is that while many of the techniques have a list of supporting literature, many of these articles are in French or French journals, or in journals not readily available at many Universities and Colleges and not accessible to students.