Molecular systematics

Plant Molecular Systematics. Macromolecular Approaches. John Wiley Sons,... 

Hillis, D.M., Moritz, C. and Mable, B.K. (1996) Molecular Systematics. Sinauer Associates, Sunderland, Massachusetts. 

O Donnell, K., Cigelnik, E., and Nirenberg, H. 1. (1998). Molecular systematics and phylo-geography of the Gibberella fujikuroi species complex. Mycologia 90,465 93. 

Zehnder, M.P. and Mariaux, J. (1999) Molecular systematic analysis of the order Proteocephalidea (Eucestoda) based on mitochondrial and nuclear rDNA sequences. International Journal for Parasitology 29, 1841-1852. 

Galazzo, D.E., Dayanandan, S., Marcogliese, D.J. and McFaughlin, J.D. (2002) Molecular systematics of some North American species of Diplostomum (Digenea) based on rDNA-sequence data and comparisons with European congeners. Canadian Journal of Zoology 80, 2207-221 7. 

Wallman, J. F., Leys, R., and Hogendoorn, K. (2005). Molecular systematics of Australian carrion-breeding blowflies (Diptera Calliphoridae) based on mitochondrial DNA. Invert. Syst. 19,1-15. 

Graeme Wistow (41), Section on Molecular Structure and Function, National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892 Elizabeth A. Zimmer (39), Laboratory of Molecular Systematics, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20560... 

A number of immunological techniques have been used in comparative studies.8,9 The most important of these is microcomplement fixation (MC F), a quantitative technique that has played a key role in many classic studies of molecular evolution and molecular systematics. By selecting proteins with different rates of evolution, a broad range of divergences can be examined. The cost of the technique is moderate, but biochemical expertise is required and the labor involved is substantial. Protein must be purified from some or all taxa for antibody production, and, for those taxa, a sizable tissue or serum sample is needed. Antibody production itself is usually done in rabbits, so an animal care facility must be available. Like isozyme electrophoresis, the large body of immunological distance data already available ensures the continued value of this technique for certain investigations. 

D. J. Crawford, Plant Molecular Systematics. Wiley, New York, 1990. 

Three problems with seed sources, either from seed banks or university greenhouse collections, have been encountered in past molecular systematic studies. These include contaminated seed source, errors in handling or labeling, and misidentification.11 Needless to say, these problems can be circumvented by vouchering all plant tissue grown from seed (see below). 

The extraction of DNA from mummified and fossilized plant tissue is one of the most exciting developments in molecular systematics. Mummified plant tissues up to 44,600 years old have yielded analyzable DNA.13-19 The recent publications of rbcL sequences from Miocene fossils (17-20 million years old) of Magnolia20 and Taxodium21 and the amplification of similar-aged DNA from Platanus and Pseudofagus21 open a new source for land plant tissue and offer enormous possibilities for research in molecular systematics and evolution. The latter report clearly invalidates the objections22 to the authenticity of the Miocene fossil plant DNA and hence of their systematic utility. 

The specimen should be properly dried, labeled, and identified by competent systematists or even specialists. Photographic records are helpful and sometimes must take the place of a plant specimen in situations when endangered or threatened species are involved and populations have already been vouchered (e.g., Hawaiian Lobeliaceae). Special arrangements must be made if the voucher for the molecular systematic study is unicate and will be carried out of the country, because most foreign countries require that the first set of plant specimens be deposited at the national or a local herbarium. The herbarium in which the vouchers are deposited (see Holmgren et a/.24) should be cited in subsequent publications. 

Museum collections are a tremendous and still largely underutilized resource for molecular systematic studies. The large research collections in the world contain huge amounts of material amenable to molecular analysis that may be otherwise unavailable due to extinction or collection difficulties. This can be especially acute in higher level studies of geographically diverse taxa. Collections can make possible, in time and resources, studies for which it would take years to gather material. 

Fibroblasts were selected because they are readily cultivated and radio-labeled and are available from skin explants of a variety of species. Autoradiograms of radiolabeled cellular proteins are more diverse and easily analyzable for molecular systematics than alternatives such as silver-stained serum or erythrocyte protein patterns. We have achieved nearly 100% success rates at minimal discomfort and risk to human subjects by establishing cultures from 3 mm punch biopsies from the upper buttock. Local lidocaine anesthesia is used. Samples are collected following informed consent and under an approved human research protocol. Other species are sampled by dart gun8 or while sedated. Skin samples can be collected from various body sites without compromising the 2D electrophoresis metric, which does not rely on quantitative differences in protein expression. To comply with the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), tissues collected from wild and captive exotic animals must be obtained under specific permits issued by the U.S. Fish and Wildlife Service. 

D. M. Hillis and C. Moritz (eds.), Molecular Systematics. Sinauer, Sunderland, Massachusetts, 1990. 

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