High levels of genetic structuring as a result of population fragmentation in the tropical tree species Caesalpinia echinata Lam.

We have investigated levels of genetic diversity within and among seven remnant populations of Caesalpinia echinata Lam., an endangered species found as fragmented populations in three major areas around the coastal regions of Brazil. Using amplified fragment length polymorphism (AFLP) genetic markers, we detected levels of within-population genetic diversity ranging from 0.092 to 0.163, with the lowest values generally being found in the smallest populations. Estimates of between-population genetic differentiation were strongly correlated with geographical distance ( r = 0.884, p <0.001), which, along with a neighbour-joining phylogenetic analysis, strongly suggested high levels of genetic isolation by distance. Over half (62%) of the total genetic diversity was partitioned between populations, further highlighting the genetic distinctness of individual populations. Taken together, these results suggest that fragmentation has led to an increase in population differentiation between fragments of C. echinata. These formations will be of great value in the development of conservation plans for species exhibiting high levels of genetic differentiation due to fragmentation, such as indication of conservation unit size, which populations should be chosen as priority in conservation plans and which samples should be introduced in areas with a low number of individuals of brazilwood.

Comparison of techniques to examine the diversity of fungi in adult patients with cystic fibrosis

This study compares conventional and molecular techniques for the detection of fungi in 77 adult cystic fibrosis (CF) patients. Three different methods were investigated, i.e., (1) conventional microbiological culture (including yeasts and filamentous fungi), (2) mycological culture with CF-derived fungal specific culture media, and (3) Non-culture and direct DNA extraction from patient sputa. Fungi isolated from environmental air samples of the CF unit were compared to fungi in sputa from CF patients. Fungi (n = 107) were detected in 14/77(18%) of patients by method 1, in 60/77 (78%) of patients by method 2 and with method 3, in 77/77(100%) of the patients. The majority of yeasts isolated were Candida albicans and C. dubliniensis. Exophiala (Wangiella) dermatitidis, Scedosporiumapiospermum, Penicillium spp., Aspergillus fumigatus, and Aspergillus versicolor were also identified by sequence analysis of the rDNA short internal transcribed spacer (ITS2) region. Conventional laboratory analysis failed to detect fungi in 63 patients mainly due to overgrowth by Gram-negative organisms. Mycological culture with antibiotics dramatically increased the number of fungi that could be detected. Molecular techniques detected fungi such as Saccharomyces cerevisiae, Malassezia spp., Fuscoporia ferrea, Fusarium culmorum, Acremonium strictum, Thanatephorus cucumeris and Cladosporium spp. which were not found with other methods. This study demonstrates that several potentially important fungi may not be detected if mycological culture methods alone are used. A polyphasic approach employing both enhanced mycological culture with molecular detection will help determine the presence of fungi in the sputa of patients with CF and their healthcare environment.