Increased chromosome damage in systemic sclerosis skin fibroblasts.

OBJECTIVE: To evaluate chromosome damage, by means of micronucleus frequency, in dermal fibroblasts from affected and non-affected skin from systemic sclerosis (SSc) patients and from controls. METHODS: Primary fibroblast cultures were obtained by biopsy from affected and non-affected skin from SSc patients. Control fibroblasts were derived from skin remnants from plastic surgery in healthy adults. The number of micronuclei-bearing cells per 1000 binucleated cells (MN+ cells/1000 BN) was determined in cultures with and without clastogenic stimulus (bleomycin 3 µg/mL). RESULTS: Primary cultures from 10 SSc patients (affected and non-affected skin) and nine controls were analysed by two blinded examiners. In the absence of bleomycin, the frequency of MN+ cells was higher in cultures from affected (14.01 ± 11.96 MN+ cells/1000 BN; p = 0.004) and non-affected (15.41 ± 13.58 MN cells/1000 BN; p = 0.005) skin from SSc patients as compared to fibroblasts from healthy controls (4.74 ± 3.30 MN cells/1000 BN). In bleomycin-treated cultures, the frequency of MN cells was higher in SSc affected (38.03 ± 26.14 MN cells/1000 BN; p = 0.041) and non-affected skin (38.47 ± 17.88 MN cells/1000 BN; p = 0.034) as compared to healthy control fibroblasts (20.54 ± 13.09 MN cells/1000 BN). There was no difference in the frequency of MN cells in cultures from affected and non-affected skin of SSc patients. CONCLUSIONS: This is the first demonstration that dermal fibroblasts from SSc patients present an increased frequency of spontaneous and clastogen-induced micronuclei. Increased clastogenesis seems to be a widespread phenomenon in SSc because fibroblasts from clinically affected and non-affected skin presented the equivalent increased micronuclei counts.

Individual, sexual, seasonal, and temporal variation in the amount of sagebrush lizard scent marks.

Although many animals deposit scent marks, previous studies have focused almost entirely on rodents or on the chemical structure of the signal. Here, we study the quantity and temporal pattern of chemical deposition by the territorial sagebrush lizard Sceloporus graciosus, measuring both femoral pore and fecal deposits. Specifically, we tested whether variation in deposition is a good cue of individual and sexual identity and/or whether it is more closely associated with body size and reproductive state, indicators of physiological condition. The results support the latter hypothesis. We found that although the amount of fluid deposited on a single perch (rarely quantified in mammals) carries little information on individual or sexual identity, it reflects the physiological condition and reproductive state of individual lizards and is replenished on a roughly weekly cycle, potentially providing additional information on the producer's activity level. The amount of deposition may thus provide important information to chemical receivers making mate choice and territorial defense decisions. The results further suggest that seasonal increases in gland production allow lizards to mark more sites rather than to influence the quality of the signal on a single perch.

Random sampling of constrained phylogenies: conducting phylogenetic analyses when the phylogeny is partially known.

Statistical randomization tests in evolutionary biology often require a set of random, computer-generated trees. For example, earlier studies have shown how large numbers of computer-generated trees can be used to conduct phylogenetic comparative analyses even when the phylogeny is uncertain or unknown. These methods were limited, however, in that (in the absence of molecular sequence or other data) they allowed users to assume that no phylogenetic information was available or that all possible trees were known. Intermediate situations where only a taxonomy or other limited phylogenetic information (e.g., polytomies) are available are technically more difficult. The current study describes a procedure for generating random samples of phylogenies while incorporating limited phylogenetic information (e.g., four taxa belong together in a subclade). The procedure can be used to conduct comparative analyses when the phylogeny is only partially resolved or can be used in other randomization tests in which large numbers of possible phylogenies are needed.

Phylogenies and comparative data, a microevolutionary perspective.

As species evolve along a phylogenetic tree, their phenotypes diverge. We expect closely related species to retain some phenotypic similarities owing to their shared evolutionary histories. The degree of similarity depends both on the phylogeny and on the detailed evolutionary changes that accumulate each generation. In this study, I review a general framework that can be used to translate between macroevolutionary patterns and the underlying microevolutionary process by comparing the observed relationships among measured species phenotypes and the expected relationship structure due to the phylogeny and underlying models of phenotypic evolution. I then show how the framework can be used to compare methods used (1) to reconstruct phylogenies, (2) to correct comparative data for phylogenetic non-independence, and (3) to infer details of the microevolutionary process from interspecific data and a phylogeny. Use of this framework and a microevolutionary perspective on the analysis of interspecific data opens up new fields of inquiry and many new uses for phylogenies and comparative data.

A comparative study of the evolution of sceloporus push-up displays.

Comparative studies are often used to infer the evolutionary histories of phenotypic traits. In this study, hypotheses suggesting that the evolution of Sceloporus push-up displays was constrained by the evolution of body size and the adoption of an arboreal lifestyle are tested with data from the literature on the push-up displays of 42 species of Sceloporus lizards and several phylogenetic comparative method techniques including independent contrasts, inferred changes, and spatial autocorrelation methods. Comparisons are made among the various phylogenetic analysis techniques and ways of modeling evolutionary change. Results suggest that components of display structure have evolved together and that the correlated evolution of display structural components has had a greater impact on the evolution of Sceloporus pushup displays than relationships between evolutionary changes in display structure and body size or display structure and microhabitat use. Increases in the complexity or communicative flexibility of Sceloporus push-up displays have been attained through altering the shape or type of head bob produced and the number of head bobs. A negative correlation between the two types of variation suggests that there is a limit or optimal length to these displays.