Exonic STK11 deletions are not a rare cause of Peutz-Jeghers syndrome

Background: Peutz-Jeghers syndrome (PJS) is a rare, autosomal dominant cancer predisposition syndrome characterised by oro-facial pigmentation and hamartomatous polyposis of the gastrointestinal tract. A causal germline mutation in STK11 can be identified in 30% to 80% of PJS patients.

A rare haplotype of the vitamin D receptor gene is protective against diabetic nephropathy

Background. Vitamin D and its analogues are reported to have renoprotective effects in chronic kidney disease including diabetic nephropathy (DN). Vitamin D3 is converted to 1,25(OH) D3 by CYP2R1 and CYP27B1. The biological action of 1,25(OH) D3 is mediated via its receptor. VDR, CYP27B1 or CYP2R1 gene variants could modify the biological activity of vitamin D3. We have conducted the first case- control association study to determine the relationship between polymorphisms in VDR, CYP27B1 and CYP2R1 genes, and the risk of DN in individuals with type 1 diabetes.

Quantifying forage specialisation in polyphagic insects: the polylectic and rare solitary bee, Colletes floralis (Hymenoptera: Colletidae)

Many insect species vary in their degree of foraging specialisation, with many bee species considered polyphagic (polylectic). Wild, non-managed bee species vary in their conservation status, and species-specific biological traits such as foraging specialisation may play an important role in determining variance in population declines. Current agri-environment schemes (AESs) prescribe the introduction of flower seed mixes for agricultural systems to aid the conservation of wild bees. However, the extent to which flower combinations adequately meet bee foraging requirements is poorly known. We quantitatively assessed pollen use and selectivity using two statistical approaches: Bailey's Intervals and Compositional Analysis, in an examplar species, a purportedly polylectic and rare bee, Colletes floralis, across 7 sites through detailed analysis of bee scopal pollen loads and flower abundance. Both approaches provided good congruence, but Compositional Analysis was more robust to small sample sizes. We advocate its use for the quantitative determination of foraging behaviour and dietary preference. Although C. floralis is polylectic, it showed a clear dietary preference for plants within the family Apiaceae. Where Apiaceae was uncommon, the species exploited alternative resources. Other plant families, such as the Apiaceae, could be included, or have their proportion increased in AES seed mixes, to aid the management of C. floralis and potentially other wild solitary bees of conservation concern. © 2011 The Authors. Insect Conservation and Diversity © 2011 The Royal Entomological Society.

Increasing density of rare species of intertidal gastropods: tests of competitive ability compared with common species.

Many assemblages contain numerous rare species, which can show large increases in abundances. Common species can become rare. Recent calls for experimental tests of the causes and consequences of rarity prompted us to investigate competition between co-existing rare and common species of intertidal gastropods. In various combinations, we increased densities of rare gastropod species to match those of common species to evaluate effects of intra- and interspecific competition on growth and survival of naturally rare or naturally common species at small and large densities. Rarity per se did not cause responses of rare species to differ from those of common species. Rare species did not respond to the abundances of other rare species, nor show consistently different responses from those of common species. Instead, individual species responded differently to different densities, regardless of whether they are naturally rare or abundant. This type of experimental evidence is important to be able to predict the effects of increased environmental variability on rare as opposed to abundant species and therefore, ultimately, on the structure of diverse assemblages. © 2012 Inter-Research.


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Life history of the rare red alga Tsengia bairdii (=Platoma bairdii) (Nemastomataceae, Rhodophyta) from Scotland

A single thallus of the rare red seaweed Tsengia bairdii (Farlow) K. Fan et Y.Fan( Platoma bairdii (Farlow) Kuckuck) (Nemastomataceae) was collected on a subtidal pebble on the west coast of Scotland. The terete gelatinous axes, which were only 7 mm high, were monoecious. They bore numerous cystocarps and a few spermatangia, which represent the first observation of male structures in this genus. Released carpospores grew into expanded basal discs that gave rise to erect axes bearing irregularly cruciate tetrasporangia. irregularly cruciate to zonate tetrasporangia were also formed on these basal discs. Karyological studies on dividing tetrasporocytes showed about 25 bodies, identified as paired meiotic chromosomes on the basis of their size in comparison to mitotic and meiotic chromosomes in other red algal species. These observations confirm the isomorphic life history inferred from early field collections and show that this species is monoecious. Tsengia bairdii is an extremely rare seaweed in Europe - it seems to be confined to sublittoral cobbles and has a temporally patchy distribution.

Are richness patterns of common and rare species equally well explained by environmental variables?

We investigated relationships between richness patterns of rare and common grassland species and environmental factors, focussing on comparing the degree to which the richness patterns of rare and common species are determined by simple environmental variables. Using data collected in the Machair grassland of the Outer Hebrides of Scotland, we fitted spatial regression models using a suite of grazing, soil physicochemical and microtopographic covariates, to nested sub-assemblages of vascular and non-vascular species ranked according to rarity. As expected, we found that common species drive richness patterns, but rare vascular species had significantly stronger affinity for high richness areas. After correcting for the prevalence of individual species distributions, we found differences between common and rare species in 1) the amount of variation explained: richness patterns of common species were better summarised by simple environmental variables, 2) the associations of environmental variables with richness showed systematic trends between common and rare species with coefficient sign reversal for several factors, and 3) richness associations with rare environments: richness patterns of rare vascular species significantly matched rare environments but those of non-vascular species did not. Richness patterns of rare species, at least in this system, may be intrinsically less predictable than those of common species.

Realizing a high magnetic moment in Gd/Cr/FeCo: The role of the rare earth

The search for materials or systems exhibiting a high magnetic saturation has been of longstanding importance. It has been suggested that increased saturation could be achieved by coupling a transition metal via a spacer to a rare earth. We report Gd/Cr/Fe₇₀Co₃₀ multilayer stacks and find reduced yet modulating magnetic moment as a function of Cr thickness. Through a micro structural analysis the lowered moment is indicated by the nucleation of the ultrathin Gd films into an fcc phase. We discuss the possible solution in terms of quasi-perfect lattice match seed material to promote growth of hcp Gd.

Rare and common variants in extracellular matrix gene Fibrillin 2 (FBN2) are associated with macular degeneration

Neurodegenerative diseases affecting the macula constitute a major cause of incurable vision loss and exhibit considerable clinical and genetic heterogeneity, from early-onset monogenic disease to multifactorial late-onset age-related macular degeneration (AMD). As part of our continued efforts to define genetic causes of macular degeneration, we performed whole exome sequencing in four individuals of a two-generation family with autosomal dominant maculopathy and identified a rare variant p.Glu1144Lys in Fibrillin 2 (FBN2), a glycoprotein of the elastin-rich extracellular matrix (ECM). Sanger sequencing validated the segregation of this variant in the complete pedigree, including two additional affected and one unaffected individual. Sequencing of 192 maculopathy patients revealed additional rare variants, predicted to disrupt FBN2 function. We then undertook additional studies to explore the relationship of FBN2 to macular disease. We show that FBN2 localizes to Bruch's membrane and its expression appears to be reduced in aging and AMD eyes, prompting us to examine its relationship with AMD. We detect suggestive association of a common FBN2 non-synonymous variant, rs154001 (p.Val965Ile) with AMD in 10,337 cases and 11,174 controls (OR=1.10; p-value=3.79×10(-5)). Thus, it appears that rare and common variants in a single gene - FBN2 - can contribute to Mendelian and complex forms of macular degeneration. Our studies provide genetic evidence for a key role of elastin microfibers and Bruch's membrane in maintaining blood-retina homeostasis and establish the importance of studying orphan diseases for understanding more common clinical phenotypes.