In and out of refugia: historical patterns of diversity and demography in the North American Caesar's mushroom species complex

Some of the effects of past climate dynamics on plant and animal diversity make‐up have been relatively well studied, but to less extent in fungi. Pleistocene refugia are thought to harbour high biological diversity (i.e. phylogenetic lineages and genetic diversity), mainly as a product of increased reproductive isolation and allele conservation. In addition, high extinction rates and genetic erosion are expected in previously glaciated regions. Some of the consequences of past climate dynamics might involve changes in range and population size that can result in divergence and incipient or cryptic speciation. Many of these dynamic processes and patterns can be inferred through phylogenetic and coalescent methods. In this study, we first delimit species within a group of closely related edible ectomycorrhizal Amanita from North America (the American Caesar's mushrooms species complex) using multilocus coalescent‐based approaches; and then address questions related to effects of Pleistocene climate change on the diversity and genetics of the group. Our study includes extensive geographical sampling throughout the distribution range, and DNA sequences from three nuclear protein‐coding genes. Results reveal cryptic diversity and high speciation rates in refugia. Population sizes and expansions seem to be larger at midrange latitudes (Mexican highlands and SE USA). Range shifts are proportional to population size expansions, which were overall more common during the Pleistocene. This study documents responses to past climate change in fungi and also highlights the applicability of the multispecies coalescent in comparative phylogeographical analyses and diversity assessments that include ancestral species.     

Genetic improvement of spinosad resistance in the biocontrol agent Orius laevigatus

BioControl - Augmentative biological control has experienced a remarkable success, particularly in protected crops. Yet integrated pest management (IPM) still requires corrective treatments to...     

Metabolomic approach with LC-QTOF to study the effect of a nutraceutical treatment on urine of diabetic rats

The rat treated with streptozotocin has been proposed as the most appropriate model of systemic oxidative stress for studying antioxidant therapies. In that sense, rosemary extracts have long been recognized as having antioxidant properties, and folic acid may be able to improve endothelial progenitor cell function. A mixture containing both has been tested as a possible nutraceutical to improve health complications in diabetes. We have developed the methodology to evaluate metabolic changes in the urine of streptozotocin-induced diabetic rats after supplementing their diet with rosemary extract obtained with supercritical fluids (SFE) containing 10% folic acid in an acute but short-term study. It has been done with a metabolomics approach using LC-QTOF as an analytical tool. About 20 endogenous metabolites have been identified by databases and MS/MS showing statistically significant changes. Among them, several amino acids and their metabolites point to changes due to the effect of the gut microbiota. In addition, the comparison between control and streptozotocin-diabetic rats has permitted the showing of some metabolic coincidences between type 1 diabetes and other (possible) autoimmune diseases such as autism and/or Crohn's disease, and the nutraceutical intervention has succeeded in inducing changes in such biomarkers.     

Association between simple sequence repeat-rich chromosome regions and intergenomic translocation breakpoints in natural populations of allopolyploid wild wheats

Background and Aims

Repetitive DNA sequences are thought to be involved in the formation of chromosomal rearrangements. The aim of this study was to analyse the distribution of microsatellite clusters in Aegilops biuncialis and Aegilops geniculata, and its relationship with the intergenomic translocations in these allotetraploid species, wild genetic resources for wheat improvement.

Methods

The chromosomal localization of (ACG)_n and (GAA)_n microsatellite sequences in Ae. biuncialis and Ae. geniculata and in their diploid progenitors Aegilops comosa and Aegilops umbellulata was investigated by sequential in situ hybridization with simple sequence repeat (SSR) probes and repeated DNA probes (pSc119·2, Afa family and pTa71) and by dual-colour genomic in situ hybridization (GISH). Thirty-two Ae. biuncialis and 19 Ae. geniculata accessions were screened by GISH for intergenomic translocations, which were further characterized by fluorescence in situ hybridization and GISH.

Key Results

Single pericentromeric (ACG)_n signals were localized on most U and on some M genome chromosomes, whereas strong pericentromeric and several intercalary and telomeric (GAA)_n sites were observed on the Aegilops chromosomes. Three Ae. biuncialis accessions carried 7U^b–7M^b reciprocal translocations and one had a 7U^b–1M^b rearrangement, while two Ae. geniculata accessions carried 7U^g–1M^g or 5U^g–5M^g translocations. Conspicuous (ACG)_n and/or (GAA)_n clusters were located near the translocation breakpoints in eight of the ten translocated chromosomes analysed, SSR bands and breakpoints being statistically located at the same chromosomal site in six of them.

Conclusions

Intergenomic translocation breakpoints are frequently mapped to SSR-rich chromosomal regions in the allopolyploid species examined, suggesting that microsatellite repeated DNA sequences might facilitate the formation of those chromosomal rearrangements. The (ACG)_n and (GAA)_n SSR motifs serve as additional chromosome markers for the karyotypic analysis of UM genome Aegilops species.     

Monosaccharides modulate HCV E2 protein-derived peptide biological properties

A hepatitis C virus E(2) protein-derived sequence was selected for studying the effect of N-glycosylation on the peptide chain's conformational structure. The results suggested that the (534)TDVF(537) motif contained in peptide 33402 ((529)WGENDTDVFVLNNTRY(544)) had a type III beta-turn, relevant in antigen recognition of polyclonal antibodies, binding to human cells, and binding to HLA DRB1 *0401 molecules. N-Glycopeptides derived from this sequence contained monosaccharides in Asn(532). N-Glycopeptides presented differences in peptide chain structure compared to non-glycosylated peptides. Peptide 33402 specifically bound to human cells, specificity becoming lost when it was N-glycosylated. N-Glycosylation decreased antigen recognition of mouse polyclonal sera against this sequence. N-Glycopeptide binding to HLA DRB1 *0401 molecules was similar to that presented by non-glycosylated peptide, indicating that N-glycosylation did not affect binding to HLA DRB1 *0401 molecules. N-Glycosylation induced changes at structural and functional level which could be relevant for modulating human cell binding properties and antibody recognition.     

SVCT2 transporter expression is post‐natally induced in cortical neurons and its function is regulated by its short isoform

Different studies have demonstrated the importance of micronutrients, such as vitamins, for normal adult brain function and development. Vitamin C is not synthesized in the brain, but high levels are detected in this organ because of the existence of specific uptake mechanisms, which concentrate ascorbic acid from the bloodstream to the cerebrospinal fluid and then into neurons and glial cells. Two different isoforms of sodium–vitamin C cotransporters (SVCT1 and SVCT2) have been cloned. SVCT2 expression has been observed in the adult hippocampus and cortical neurons by in situ hybridization. In addition, the localization of SVCT2 in the rat fetal brain has been studied by immunohistochemistry and in situ hybridization, demonstrating that SVCT2 is highly expressed in the ventricular and subventricular areas of the brain cortex. However, there are currently no immunohistochemical data regarding SVCT2 expression and function in the post‐natal brain. Therefore, we analyzed SVCT2 expression in the developing brain cortex of mice, and demonstrated an increase in SVCT2 mRNA in mice at 1–15 days of age. The expression of a short isoform, SVCT2sh, was also detected within the same period. SVCT2 expression was concentrated in neurons within the inner layer of the brain cortex. Both SVCT2 isoforms were coexpressed in N2a cells to obtain functional data. Fluorescence resonance energy transfer analysis revealed a molecular interaction between SVCT2wt and SVCT2sh. Finally, differences in transport ratios suggested that SVCT2sh expression inhibited ascorbic acid uptake in N2a cells when both isoforms were coexpressed.

     

Exposure to Low Level of Arsenic and Lead in Drinking Water from Antofagasta City Induces Gender Differences in Glucose Homeostasis in Rats

Populations chronically exposed to arsenic in drinking water often have increased prevalence of diabetes mellitus. The purpose of this study was to compare the glucose homeostasis of male and female rats exposed to low levels of heavy metals in drinking water. Treated groups were Sprague-Dawley male and female rats exposed to drinking water from Antofagasta city, with total arsenic of 30 ppb and lead of 53 ppb for 3 months; control groups were exposed to purified water by reverse osmosis. The two treated groups in both males and females showed arsenic and lead in the hair of rats. The δ-aminolevulinic acid dehydratase was used as a sensitive biomarker of arsenic toxicity and lead. The activity of δ-aminolevulinic acid dehydratase was reduced only in treated male rats, compared to the control group. Treated males showed a significantly sustained increase in blood glucose and plasma insulin levels during oral glucose tolerance test compared to control group. The oral glucose tolerance test and the homeostasis model assessment of insulin resistance demonstrated that male rats were insulin resistant, and females remained sensitive to insulin after treatment. The total cholesterol and LDL cholesterol increased in treated male rats vs. the control, and triglyceride increased in treated female rats vs. the control. The activity of intestinal Na+/glucose cotransporter in male rats increased compared to female rats, suggesting a significant increase in intestinal glucose absorption. The findings indicate that exposure to low levels of arsenic and lead in drinking water could cause gender differences in insulin resistance.     

Amyloidity is not diagnostic for species in the Mycena pearsoniana complex (Mycena sectio Calodontes)

In Mycena sectio Calodontes with otherwise amyloid spores, the inamyloid spores of Mycena pearsoniana Dennis ex Singer were a distinguishing feature for this species and its subsection Violacella. Although the original concept of this species was European, Singer chose to typify it with material collected in Mexico. The name has since been applied to all European collections with inamyloid spores and decurrent lamellae. Our phylogenetic analysis of 91 ITS sequences from European, North and South American Calodontes collections shows that European collections identified as M. pearsoniana fall into two well-supported sibling clades together with both inamyloid and weakly amyloid North American collections. Since the holotype of M. pearsoniana is in an advanced state of decay, we have selected an epitype from a North American locality with a climate comparable to the Mexican type locality. Our results show weakly and inamyloid spore reactions to be homoplastic in Calodontes, and furthermore that spores of M. pearsoniana can show either amyloid or inamyloid reactions interchangeably. This raises doubt about the taxonomic value of this trait in Mycena systematics.