Macro-Climatic Distribution Limits Show Both Niche Expansion and Niche Specialization among C4 Panicoids

Grasses are ancestrally tropical understory species whose current dominance in warm open habitats is linked to the evolution of C₄ photosynthesis. C₄ grasses maintain high rates of photosynthesis in warm and water stressed environments, and the syndrome is considered to induce niche shifts into these habitats while adaptation to cold ones may be compromised. Global biogeographic analyses of C₄ grasses have, however, concentrated on diversity patterns, while paying little attention to distributional limits. Using phylogenetic contrast analyses, we compared macro-climatic distribution limits among ~1300 grasses from the subfamily Panicoideae, which includes 4/5 of the known photosynthetic transitions in grasses. We explored whether evolution of C₄ photosynthesis correlates with niche expansions, niche changes, or stasis at subfamily level and within the two tribes Paniceae and Paspaleae. We compared the climatic extremes of growing season temperatures, aridity, and mean temperatures of the coldest months. We found support for all the known biogeographic distribution patterns of C₄ species, these patterns were, however, formed both by niche expansion and niche changes. The only ubiquitous response to a change in the photosynthetic pathway within Panicoideae was a niche expansion of the C₄ species into regions with higher growing season temperatures, but without a withdrawal from the inherited climate niche. Other patterns varied among the tribes, as macro-climatic niche evolution in the American tribe Paspaleae differed from the pattern supported in the globally distributed tribe Paniceae and at family level.     

A practical approach to FRET-based PNA fluorescence in situ hybridization

Given the demand for improved methods for detecting and characterizing RNA variants in situ, we developed a quantitative method for detecting RNA alternative splicing variants that combines in situ hybridization of fluorescently labeled peptide nucleic acid (PNA) probes with confocal microscopy Förster resonance energy transfer (FRET). The use of PNA probes complementary to sequences flanking a given splice junction allows to specifically quantify, within the cell, the RNA isoform generating such splice junction as FRET efficiency measure. The FRET-based PNA fluorescence in situ hybridization (FP-FISH) method offers a conceptually new approach for characterizing at the subcellular level not only splice variant isoform structure, location, and dynamics but also potentially a wide variety of close range RNA–RNA interactions. In this paper, we explain the FP-FISH technique workflow for reliable and reproducible results.     

α-Synuclein Levels in Blood Plasma from LRRK2 Mutation Carriers

The diagnosis of Parkinson’s disease (PD) remains primarily a clinical issue, based mainly on phenotypic patterns. The identification of biomarkers capable of permitting the preclinical detection of PD is critically needed. α-Synuclein is a key protein in PD, with missense and multiplication mutations in the gene encoding α-synuclein (SNCA) having been reported in familial cases of PD, and accumulation of the protein identified in Lewy bodies (LBs) and Lewy neurites (LNs) in affected brain regions. With the objective of validating the use of α-synuclein as a clinical or progressive biomarker in an accessible tissue, we used an enzyme-linked immunosorbent assay (ELISA) to measure α-synuclein levels in the peripheral blood plasma of idiopathic PD and LRRK2 mutation carrier patients and compared our findings with healthy control subjects. Compared to healthy controls, we found a significant decrease in plasma total α-synuclein levels in idiopathic PD (iPD) patients (n = 134, p = 0.010). However, the reduction was less significant in patients who were LRRK2 mutation carriers (n = 32, p = 0.133). This lack of significance could be due to the small number of individuals employed in this group. No predictive value of total α-synuclein in the diagnosis of PD was found in a receiver operating characteristic (ROC) curve analysis. Although this is a pilot study requiring corroboration on a larger cohort of patients, our results highlight the possible use of plasma α-synuclein as a biomarker for PD.     

An integrative taxonomic revision of the Cape Verdean skinks (Squamata,Scincidae)

Miralles, A., Vasconcelos, R., Perera, A., Harris, D. J. & Carranza, S. (2010). An integrative taxonomic revision of the Cape Verdean skinks (Squamata, Scincidae). —Zoologica Scripta, 40, 16–44. A comprehensive taxonomic revision of the Cape Verdean skinks is proposed based on an integrative approach combining (i) a phylogenetic study pooling all the previously published molecular data, (ii) new population genetic analyses using mitochondrial and nuclear data resulting from additional sampling, together with (iii) a morphological study based on an extensive examination of the scalation and colour patterns of 516 live and museum specimens, including most of the types. All Cape Verdean species of skinks presently recognised, formerly regarded as members of the genera Mabuya Fitzinger, 1826 and Macroscincus Bocage, 1873 are considered as members of the Cape Verdean endemic genus Chioninia Gray, 1845. The new phylogeny and networks obtained are congruent with the previously published phylogenetic studies, although suggesting older colonization events (between 11.6 and 0.8 Myr old), and indicate the need for taxonomic changes. Intraspecific diversity has been analysed and points to a very recent expansion of Chioninia delalandii on the southern islands and its introduction on Maio, to a close connection between Chioninia stangeri island populations due to Pleistocene sea‐level falls and to a generally low haplotypic diversity due to the ecological and geological characteristics of the archipelago. Three new consistent morphological synapomorphies supporting two of the four main clades of the genus have been identified. The complex taxonomic status of Euprepes fogoensis O’Shaughnessy, 1874 has been resolved and a lectotype has been designated for this species; Chioninia fogoensis nicolauensis (Schleich, 1987) is elevated to species rank, whereas Chioninia fogoensis antaoensis (Schleich, 1987) is now regarded as a junior subjective synonym of C. fogoensis. Additionally, one new subspecies of Chioninia vaillanti and two of Chioninia spinalis are described (Chioninia vaillanti xanthotis ssp. n., Chioninia spinalis santiagoensis ssp. n. and Chioninia spinalis boavistensis ssp. n.) and a lectotype has been designated for Mabuia spinalis Boulenger, 1906. Finally, an identification key for the Chioninia species is presented.     

Prevalence of potentially pathogenic culturable bacteria on eggshells and in cloacae of female Pied Flycatchers in a temperate habitat in central Spain

ABSTRACT Bacteria grow on avian eggshells and thus can potentially cause diseases in developing embryos. Little is known about culturable bacteria colonizing avian eggshells in free‐living birds, with most studies restricted to poultry. Our objective was to examine the culturable bacterial array growing on eggshells during incubation that could negatively affect hatching success of Pied Flycatchers (Ficedula hypoleuca) in a temperate montane habitat in central Spain. Cloacal culturable bacteria of females were also analyzed because bacteria can be vertically transmitted from females to eggs. We used fecal samples as surrogates of cloacal samples due to the small size of sampled birds. We found that eggshells and female cloacae of Pied Flycatchers harbored 24 and 40 bacterial families and species, respectively, but only a few in each clutch and each cloaca. Rod‐shaped gram‐negative bacteria and bacteria in the family Pseudomonadaceae were the most common bacteria on eggshells during early and late incubation and in female cloacae. Although based on small sample sizes, we found that females with rod‐shaped gram‐negative bacteria in their cloacae laid eggs that also had these bacteria, providing possible evidence for vertical transmission. We found no evidence for vertical transmission of Pseudomonadaceae, suggesting a possible environmental source for these bacteria. The prevalence of bacterial morphological types and major taxonomical categories on eggshells did not vary from early to late stages of incubation, providing support for the hypothesis that incubation may have bacteriostatic effects on bacterial proliferation on eggshells. Despite being primary egg invaders in poultry, we detected no effects of culturable Pseudomonadaceae or Pseudomonas luteola on hatching success. Our study represents the first to examine the culturable bacteria growing on the eggshells of a wild bird in a temperate habitat and additional studies based on culture‐independent techniques are required to confirm our results.     

The formation of titan cells in Cryptococcus neoformans depends on the mouse strain and correlates with induction of Th2‐type responses

Cryptococcus neoformans is a pathogenic yeast that can form titan cells in the lungs, which are fungal cells of abnormal enlarged size. Little is known about the factors that trigger titan cells. In particular, it is not known how the host environment influences this transition. In this work, we describe the formation of titan cells in two mouse strains, CD1 and C57BL/6J. We found that the proportion of C. neoformans titan cells was significantly higher in C57BL/6J mice than in CD1. This higher proportion of titan cells was associated with a higher dissemination of the yeasts to the brain. Histology sections demonstrated eosinophilia in infected animals, although it was significantly lower in the CD1 mice which presented infiltration of lymphocytes. Both mouse strains presented infiltration of granulocytes, but the amount of eosinophils was higher in C57BL/6J. CD1 mice showed a significant accumulation of IFN‐γ, TNF‐α and IL17, while C57BL/BL mice had an increase in the anti‐inflammatory cytokine IL‐4. IgM antibodies to the polysaccharide capsule and total IgE were more abundant in the sera from C57BL/6J, confirming that these animals present a Th2‐type response. We conclude that titan cell formation in C. neoformans depends, not only on microbe factors, but also on the host environment.     

DNA methylation changes in murine breast adenocarcinomas allow the identification of candidate genes for human breast carcinogenesis

Epigenetic inactivation due to aberrant promoter methylation is a key process in breast tumorigenesis. Murine models for human breast cancer have been established for nearly every important human oncogene or tumor suppressor gene. Mouse-to-human comparative gene expression and cytogenetic profiling have been widely investigated for these models; however, little is known about the conservation of epigenetic alterations during tumorigenesis. To determine if this key process in human breast tumorigenesis is also mirrored in a murine breast cancer model, we mapped cytosine methylation changes in primary adenocarcinomas and paired lung metastases derived from the polyomavirus middle T antigen mouse model. Global changes in methylcytosine levels were observed in all tumors when compared to the normal mammary gland. Aberrant methylation and associated gene silencing was observed for Hoxa7, a gene that is differentially methylated in human breast tumors, and Gata2, a novel candidate gene. Analysis of HOXA7 and GATA2 expression in a bank of human primary tumors confirms that the expression of these genes is also reduced in human breast cancer. In addition, HOXA7 hypermethylation is observed in breast cancer tissues when compared to adjacent tumor-free tissue. Based on these studies, we present a model in which comparative epigenetic techniques can be used to identify novel candidate genes important for human breast tumorigenesis, in both primary and metastatic tumors.