State University of New York System

About: State University of New York System is a education organization based out in Albany, New York, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 54077 authors who have published 78070 publications receiving 2985160 citations.

On applications of geometric morphometrics to studies of ontogeny and phylogeny.

Abstract: In press − − do not cite 2 The field of geometric morphometrics is relatively new (see Bookstein, 1991, Rohlf and Marcus, 1993) and has shown very rapid progress over the last few years. As might be expected during a period of rapid development, there can be technical problems in some of the pioneering studies as biologists attempt to apply the new tools. It is only now becoming clear how the new techniques should be combined in order to carry out comprehensive analyses of real datasets. Bookstein (1996b) gave a list of recommendations for such applications and Bookstein (1996a) gave several comprehensive examples of morphometric analyses. However, these accounts do not address some of the types of applications that are of particular interest in systematic biology. Bookstein (1994) pointed out problems with using geometric morphometric methods in the usual character-based cladistic studies. He emphasized that morphometrics cannot supply homologous shape characters. The purpose of this note is to comment some recent applications of morphometric methods in systematic biology. This note is particularly concerned with the morphometric methods used by Zelditch et al. These methods were also used by Burke et al. (1996). For convenience, these studies will be referred to using the acronym Z&F. In these studies the authors investigated the use of partial warps (Bookstein, 1991) as variables in ontogenetic and taxonomic studies. They were impressed by their observation that differences in partial warps scores (Rohlf, 1993b) corresponded to shape differences that could be localized on the bodies of the organisms. They also found differences in these variables between developmental stages and between species. They concluded that partial warps could be interpreted and used as traditional taxonomic characters and would be useful in evolutionary studies. Lynch et al. (1996) tried to interpret the partial warps they obtained in their study but they were cautious about using them in the ways advocated by Z&F. They suggested that extensive simulation studies needed to be done to validate the Z&F approach. Naylor (1996) investigated their approach using data based on a simulated phylogeny. Even though his simulated phylogeny was based on a sequence of simple morphological changes and had no homoplasy, the results showed high levels of homoplasy and did not recover the morphological changes used to create the phylogeny. The present paper is concerned with theoretical problems rather than empirical problems requiring validation through simulations. The fundamental problem is that Z&F …

Detection of single base substitutions in total genomic DNA

Abstract: Certain single base substitutions causing genetic diseases or resulting in polymorphisms linked to mutant alleles, alter a restriction enzyme cleavage site and can therefore be detected in total genomic DNA using DNA blots. Many base substitutions do not lead to an altered restriction site, but these can be detected using synthetic oligonucleotides as hybridization probes if the DNA sequence surrounding the base substitution is known. In the case of beta-thalassaemia, where 22 different single base mutations have been identified, a large number of probes would be required for diagnosis. An approach which was used to detect mutations in viral DNA involves the S1 nuclease treatment of heteroduplexes formed between wild-type and mutant DNA. Although certain single base mismatches are cleaved by S1 nuclease (ref. 11 and T. Shenk, personal communication), many other mismatches examined by this procedure are not cleaved (B. Seed, personal communication; R.M.M., unpublished data). Heteroduplexes between mutant and wild-type subgenomic fragments of double-stranded reovirus RNA migrate slower than the corresponding homoduplexes in polyacrylamide gels containing 7 M urea, but it is not known whether this method is applicable to DNA heteroduplexes containing single base mismatches. Here we describe a procedure that involves the electrophoretic separation of DNA heteroduplexes in a well-characterized gel system. We show that four different human beta-thalassaemia alleles with known single base mutations can be detected with as little as 5 micrograms of total genomic DNA. The method should be useful in the localization and diagnosis of mutations associated with genetic diseases.