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347I.348II.349III.349IV.355V.378VI.381381References381Glossary379 Summary: Hosts and their symbionts are involved in intimate physiological and ecological interactions. The impact of these interactions on the evolution of each partner depends on the time‐scale considered. Short‐term dynamics – ‘coevolution’ in the narrow sense – has been reviewed elsewhere. We focus here on the long‐term evolutionary dynamics of cospeciation and speciation following host shifts. Whether hosts and their symbionts speciate in parallel, by cospeciation, or through host shifts, is a key issue in host–symbiont evolution. In this review, we first outline approaches to compare divergence between pairwise associated groups of species, their advantages and pitfalls. We then consider recent insights into the long‐term evolution of host–parasite and host–mutualist associations by critically reviewing the literature. We show that convincing cases of cospeciation are rare (7%) and that cophylogenetic methods overestimate the occurrence of such events. Finally, we examine the relationships between short‐term coevolutionary dynamics and long‐term patterns of diversification in host–symbiont associations. We review theoretical and experimental studies showing that short‐term dynamics can foster parasite specialization, but that these events can occur following host shifts and do not necessarily involve cospeciation. Overall, there is now substantial evidence to suggest that coevolutionary dynamics of hosts and parasites do not favor long‐term cospeciation. [ABSTRACT FROM AUTHOR]

We report the development of 60 microsatellite markers on four species of the fungal complex Microbotryum, causing anther smut of the Caryophyllaceae. Microsatellites were found in four expressed sequence tag (EST) libraries, built from isolates of M. lychnis-dioicae, M. violaceum sensus stricto, M. lagerheimii and M. dianthorum, collected, respectively, from the plants Silene latifolia, S. nutans, S. vulgaris and Dianthus carthusianorum. Intrapopulation polymorphism was investigated using 24 isolates, and cross-amplification was explored using 23 isolates belonging to at least 10 different Microbotryum species. This study provides numerous microsatellite markers for population genetics and mapping studies. [ABSTRACT FROM AUTHOR]

The mating system of Microbotryum violaceum was investigated in populations that are polymorphic for mating-type bias, where individuals produce viable haploids of only one of the two required mating types. The cause of mating-type bias was identified as deleterious recessive alleles linked to mating type. Maintenance of the deleterious alleles was promoted by early conjugation among products of single meioses, such that the duration of the free-living haploid stage is minimized. This development was also observed in nonbiased isolates. As a consequence, the mating system tends toward mating within the tetrad, which might be expected to reduce heterozygosity. However, complete centromere linkage of mating type ensures conjugation between first division meiotic products, such that mating in M. violaceum is analogous to forms of meiotic parthenogenesis with first division restitution (i.e. automixis with central fusion). This fungus was used to test the prediction that this mating system would maintain heterozygosity in regions of the genome linked to centromeres. Therefore, populations were screened for additional heterozygous lethal recessive alleles linked to centromeres, and several examples were found. Furthermore, the occurrence of intratetrad mating in M. violaceum provides an explanation for low variation among individuals within populations, inconsistent estimates of outcrossing rates, low levels of mating between tetrads of one diploid individual, and high frequencies of haplo-lethal alleles in natural populations.

A 2.5-year-old dog with congenital pulmonary valve dysplasia was treated by percutaneous balloon dilation of the stenotic orifice. Clinical and hemodynamic improvement was apparent immediately and for 9 months after the valvuloplasty procedure.

Two surgeons in a health maintenance organization group practice performed 280 fine needle aspirations (FNAs) on 257 palpable breast lesions in 200 patients. The cytology was interpreted by four pathologists at a community hospital. FNA cytology had a sensitivity of 96% and a specificity of 94% in these cases; there were no false-positive diagnoses of cancer. FNA cytology improved the identification of benign disease and decreased the risk of missing cancers. FNA cytology also improved the predictive value of mammographic information and was more helpful than mammography in demonstrating the need for biopsy of small palpable lesions that turned out to be "minimal" breast cancers.