Phylogeographic insights into cryptic glacial refugia

The glacial episodes of the Quaternary (2.6 million years ago-present) were a major factor in shaping the present-day distributions of extant flora and fauna, with expansions and contractions of the ice sheets rendering large areas uninhabitable for most species. Fossil records suggest that many species survived glacial maxima by retreating to refugia, usually at lower latitudes. Recently, phylogeographic studies have given support to the existence of previously unknown, or cryptic, refugia. Here we summarise many of these insights into the glacial histories of species in cryptic refugia gained through phylogeographic approaches. Understanding such refugia might be important as the Earth heads into another period of climate change, in terms of predicting the effects on species distribution and survival.     

Analysis of the genusZea (Poaceae) using polymorphic chloroplast simple sequence repeats

We have used polymorphic chloroplast simple sequence repeats (cpSSRs) to analyse levels of diversity and relationships within the genusZea. Between two and nine alleles were found at 15 polymorphic loci and combining the data from these loci gave 32 haplotypes in the 37 accessions studied. Genetic differentiation between the two sections within the genus was calculated using theST statistic which showed that 70% of the total variation was found to exist between the sections. A phylogenetic analysis based on the ² distance metric showed a large split between the two sections and suggested multiple origins of modern cultivated maizeZea mays subsp.mays. The agreement of the phylogenetic tree with other molecular, morphological and karyological studies suggests that cpSSRs may have value in phylogenetic studies in plants.     

Involvement of a phospholipase C in the hemolytic activity of a clinical strain of <Emphasis Type="Italic">Pseudomonas fluorescens</Emphasis>

Background  

Pseudomonas fluorescens is a ubiquitous Gram-negative bacterium frequently encountered in hospitals as a contaminant of injectable material and surfaces. This psychrotrophic bacterium, commonly described as unable to grow at temperatures above 32°C, is now considered non pathogenic. We studied a recently identified clinical strain of P. fluorescens biovar I, MFN1032, which is considered to cause human lung infection and can grow at 37°C in laboratory conditions.     

Simple coumarins from two populations of Diosma acmaeophylla

Investigation of two collections of Diosma acmaeophylla afforded seven simple coumarins, three of which were common to both samples. The chemotaxon     

Restricted gene flow in fragmented populations of a wind-pollinated tree

Fragmentation of natural populations can have negative effects at the genetic level, thus threatening their evolutionary potential. Many of the negative genetic impacts of population fragmentation can be ameliorated by gene flow and it has been suggested that in wind-pollinated tree species, high or even increased levels of gene flow are a feature of fragmented populations, although several studies have disputed this. We have used a combination of nuclear microsatellites and allele-specific PCR (AS-PCR) analysis of chloroplast single nucleotide polymorphisms (SNPs) to examine the levels and patterns of genetic diversity and population differentiation in fragmented populations of juniper (Juniperus communis) in Ireland and inform conservation programs for the species. Significant population differentiation was found for both chloroplast and nuclear markers, indicating restricted gene flow, particularly over larger geographic scales. For conservation purposes, the existence of genetically distinct clusters and geographically localised chloroplast haplotypes suggests that the concept of provenance should be taken into account when formulating augmentation or reintroduction strategies. Furthermore, the potential lack of seed dispersal and seedling establishment means that ex-situ approaches to seed and seedling management may have to be considered.     

Extent of incorporation of hydroxycinnamaldehydes into lignin in cinnamyl alcohol dehydrogenase-downregulated plants

Down-regulation of cinnamyl alcohol dehydrogenase leads to an accumulation of cinnamaldehydes available for incorporation into the developing lignin polymer. Using electron spin resonance spectroscopy we have demonstrated that the parent radical of 4-hydroxy-3-methoxycinnamaldehyde is generated by peroxidase catalysed oxidation. The extent of radical generation is similar to that of 4-hydroxy-3-methoxycinnamyl alcohol and is increased by further aromatic methoxylation. From the distribution of the electron-spin density, it was predicted that the regiochemistry of 4-hydroxy-3-methoxycinnamaldehyde coupling would be similar to that of the corresponding alcohol, with the possibility of a higher degree of 8-O-4 linkages occurring. These predictions were confirmed by polymerisation studies, which also showed that after radical coupling the alpha,beta-enone structure was regenerated. This suggests that, although the cross-linking and physical properties of cinnamaldeyde rich lignins differ from that of normal lignins, cinnamaldehydes are incorporated into the lignin polymer under the same controlling factors as the cinnamyl alcohols.     

Patterns of variation at a mitochondrial sequence-tagged-site locus provides new insights into the postglacial history of European Pinus sylvestris populations

Due to their maternal mode of inheritance, mitochondrial markers can be regarded as almost 'ideal' tools in evolutionary studies of conifer populations. In the present study, polymorphism was analysed at one mitochondrial intron (nad 1, exon B/C) in 23 native European Pinus sylvestris populations. In a preliminary screening for variation using a polymerase chain reaction-restriction fragment length polymorphism approach, two length variants were identified. By fully sequencing the 2.5 kb region, the observed length polymorphism was found to result from the insertion of a 31 bp sequence, with no other mutations observed within the intron. A set of primers was designed flanking the observed mutation, which identified a novel sequence-tagged-site mitochondrial marker for P. sylvestris. Analysis of 747 trees from the 23 populations using these primers revealed the occurrence of two distinct haplotypes in Europe. Within the Iberian Peninsula, the two haplotypes exhibited extensive population differentiation (PhiST = 0.59; P < or = 0.001) and a marked geographical structuring. In the populations of central and northern Europe, one haplotype largely predominated, with the second being found in only one individual of one population.     

Cytomegalovirus seropositivity is associated with glucose regulation in the oldest old. Results from the Leiden 85-plus Study

ABSTRACT: BACKGROUND: Cytomegalovirus (CMV) infection has been reported to contribute to the pathogenesis of type 1 diabetes and post-transplantation diabetes. However, CMV infection has not been evaluated as a possible risk factor for type 2 diabetes. Our aim was to investigate potential associations between CMV seropositivity, CMV IgG antibody level and glucose regulation in the oldest old. RESULTS: CMV seropositive subjects were more likely to have type 2 diabetes (17.2% vs 7.9%, p = 0.016), had a higher level of HbA1c (p = 0.014) and higher non-fasting glucose (p = 0.024) in the oldest olds. These associations remained significant after adjustment for possible confounders. CMV IgG antibody level was not significantly associated with glucose regulation (all p > 0.05). CONCLUSIONS: In the oldest old, CMV seropositivity is significantly associated with various indicators of glucose regulation. This finding suggests that CMV infection might be a risk factor for the development of type 2 diabetes in the elderly.