ELAC2 polymorphisms and prostate cancer risk: a meta-analysis based on 18 case–control studies

Polymorphisms in the elaC homolog-2 (ELAC2)/HPC2 gene have been hypothesized to alter the risk of prostate cancer. However, the results of the related published studies remained conflicting. We performed a meta-analysis of 18 studies evaluating the association between ELAC2 Ser217Leu and Ala541Thr polymorphisms and prostate cancer risk. Overall, ELAC2 Leu217 allele was associated with increased prostate cancer risk as compared with the Ser217 allele (odds ratio (OR)=1.13, 95% confidence interval (CI): 1.03–1.24, P=0.019 for heterogeneity), as well as in the heterozygote comparison (OR=1.21, 95% CI: 1.07–1.36, P=0.034 for heterogeneity) and the dominant genetic model (OR=1.20, 95% CI: 1.07–1.35, P=0.025 for heterogeneity). Furthermore, the ELAC2 Thr541 allele was associated with increased prostate cancer risk as compared with the Ala541 allele (OR=1.22, 95% CI: 1.00–0.48, P=0.131 for heterogeneity). In the stratified analyses for Ser217Leu polymorphism, there was significantly increased prostate cancer risk in Asian and Caucasian populations, and studies using sporadic and familial prostate cancer cases. Similar result was found in the Asian population in the stratified analyses for Ala541Thr polymorphism. This meta-analysis showed evidence that ELAC2 Ser217Leu and Ala541Thr polymorphisms were associated with prostate cancer risk, and might be low-penetrance susceptibility markers of prostate cancer

Nectar biodiversity: a short review

Nectaries differ in many aspects but a common feature is some kind of advantage for the plant conferred by foraging of consumers which may defend the plant from predators in the case of extrafloral nectaries, or be agents of pollination in the case of floral nectaries. This minireview is concerned mainly with floral nectaries and examines the following characteristics: position in flower; nectary structure; origin of carbohydrates, amino- acids and proteins; manner of exposure of nectar; site of nectar presentation; volume and production of nectar in time; sexual expression of flower and nectary morphology; nectar composition and floral sexual expression; variability of nectar composition; fate of nectar; energy cost of nectar production. The species of certain large families, such as Brassicaceae, Lamiaceae and Asteraceae, resemble each other in nectary organisation; other families, such as Cucur- bitaceae and Ranunculaceae, have various types of organisation. A scheme is presented to illustrate factors influencing nectary and nectar biodiversity

Changes in cytoplasmic carbohydrate content during Helleborus pollen presentation

Pollen grains of Helleborus foetidus and H. bocconei were exposed to low temperature treatments to simulate the natural events in pollen presentation of these two winter owering species and to analyze the pollen carbohydrate content (glucose, fructose, sucrose and starch). In both species, cytoplasmic polysaccharides, monosaccharides and sucrose were found, while only Helleborus foetidus contained starch. Polysaccharide, sucrose and monosaccharide content varied as low temperature exposure time varied, a decrease in temperature decreases polysaccharide content and increases sucrose and monosac-charides. The relative quantities of the various types of carbohydrates were not aVected by variations in the naturally occurring thermal cycles. Treatments did not greatly aVect pollen viability. Although the occurrence of carbohydrates in pollen is known since many years, their function is still unclear. The ndings of this research suggest a role of cytoplasmic pollen carbohydrates in resistance to low temperature exposure. The inter-conversion of carbohydrate type may be an adaptation for sustaining viability during pollen presentation that is particularly important for a winter owering species such as Helleborus foetidus and H. bocconei

Studies on the breeding systems of understorey species of a Chaco woodland in NE Argentina

The breeding systems of seven understorey species in a Chaco woodland in NE Argentina were studied by means of hand pollinations and fluorescence microscopy observations of post-pollination events. Six species showed self-incompatibility (SI), with heteromorphic SI in Erythroxylum microphyllum, and probable homomorphic gametophytic SI (stylar inhibition of self-pollen tubes) in Aechmea distichantha, Bromelia serra, Cleistocactus baumannii, Dyckia ferox and Grabowskia duplicata. Opuntia retrorsa was self-compatible. A notable feature of inter-morph cross-compatibility in E. microphyllum was differential fruiting success using pollen from different stamen whorls of the long-style morph. The high incidence of self-incompatibility in the understorey component of this Chaco woodland is similar to that found in some South American montane forests, and is in contrast to the widespread self-compatibility reported for this stratum in some neotropical forests. It is proposed that these breeding system differences are probably linked to the different taxonomic families represented in the understorey strata of these communities and are not a consequence of adaptations to pollination biology or other ecological factors.</p