A mirage of cryptic species: Genomics uncover striking mitonuclear discordance in the butterfly Thymelicus sylvestris

Mitochondrial DNA (mtDNA) sequencing has led to an unprecedented rise in the identification of cryptic species. However, it is widely acknowledged that nuclear DNA (nuDNA) sequence data are also necessary to properly define species boundaries. Next generation sequencing techniques provide a wealth of nuclear genomic data, which can be used to ascertain both the evolutionary history and taxonomic status of putative cryptic species. Here, we focus on the intriguing case of the butterfly Thymelicus sylvestris (Lepidoptera: Hesperiidae). We identified six deeply diverged mitochondrial lineages; three distributed all across Europe and found in sympatry, suggesting a potential case of cryptic species. We then sequenced these six lineages using double‐digest restriction‐site associated DNA sequencing (ddRADseq). Nuclear genomic loci contradicted mtDNA patterns and genotypes generally clustered according to geography, i.e., a pattern expected under the assumption of postglacial recolonization from different refugia. Further analyses indicated that this strong mtDNA/nuDNA discrepancy cannot be explained by incomplete lineage sorting, sex‐biased asymmetries, NUMTs, natural selection, introgression or Wolbachia‐mediated genetic sweeps. We suggest that this mitonuclear discordance was caused by long periods of geographic isolation followed by range expansions, homogenizing the nuclear but not the mitochondrial genome. These results highlight T. sylvestris as a potential case of multiple despeciation and/or lineage fusion events. We finally argue, since mtDNA and nuDNA do not necessarily follow the same mechanisms of evolution, their respective evolutionary history reflects complementary aspects of past demographic and biogeographic events.     

Connecting Anxiety and Genomic Copy Number Variation: A Genome-Wide Analysis in CD-1 Mice

Genomic copy number variants (CNVs) have been implicated in multiple psychiatric disorders, but not much is known about their influence on anxiety disorders specifically. Using next-generation sequencing (NGS) and two additional array-based genotyping approaches, we detected CNVs in a mouse model consisting of two inbred mouse lines showing high (HAB) and low (LAB) anxiety-related behavior, respectively. An influence of CNVs on gene expression in the central (CeA) and basolateral (BLA) amygdala, paraventricular nucleus (PVN), and cingulate cortex (Cg) was shown by a two-proportion Z-test (p = 1.6 x 10^-31), with a positive correlation in the CeA (p = 0.0062), PVN (p = 0.0046) and Cg (p = 0.0114), indicating a contribution of CNVs to the genetic predisposition to trait anxiety in the specific context of HAB/LAB mice. In order to confirm anxiety-relevant CNVs and corresponding genes in a second mouse model, we further examined CD-1 outbred mice. We revealed the distribution of CNVs by genotyping 64 CD 1 individuals using a high-density genotyping array (Jackson Laboratory). 78 genes within those CNVs were identified to show nominally significant association (48 genes), or a statistical trend in their association (30 genes) with the time animals spent on the open arms of the elevated plus-maze (EPM). Fifteen of them were considered promising candidate genes of anxiety-related behavior as we could show a significant overlap (permutation test, p = 0.0051) with genes within HAB/LAB CNVs. Thus, here we provide what is to our knowledge the first extensive catalogue of CNVs in CD-1 mice and potential corresponding candidate genes linked to anxiety-related behavior in mice.     

Comprehensive Suppression of All Apoptosis-Induced Proliferation Pathways as a Proposed Approach to Colorectal Cancer Prevention and Therapy

Mutations in the WNT/beta-catenin pathway are present in the majority of all sporadic colorectal cancers (CRCs), and histone deacetylase inhibitors induce apoptosis in CRC cells with such mutations. This apoptosis is counteracted by (1) the signaling heterogeneity of CRC cell populations, and (2) the survival pathways induced by mitogens secreted from apoptotic cells. The phenomena of signaling heterogeneity and apoptosis-induced survival constitute the immediate mechanisms of resistance to histone deacetylase inhibitors, and probably other chemotherapeutic agents. We explored the strategy of augmenting CRC cell death by inhibiting all survival pathways induced by the pro-apoptotic agent LBH589, a histone deacetylase inhibitor: AKT, JAK/STAT, and ERK signaling. The apoptosis-enhancing ability of a cocktail of synthetic inhibitors of proliferation was compared to the effects of the natural product propolis. We utilized colorectal adenoma, drug-sensitive and drug-resistant colorectal carcinoma cells to evaluate the apoptotic potential of the combination treatments. The results suggest that an effective approach to CRC combination therapy is to combine apoptosis-inducing drugs (e.g., histone deacetylase inhibitors, such as LBH589) with agents that suppress all compensatory survival pathways induced during apoptosis (such as the cocktail of inhibitors of apoptosis-associated proliferation). The same paradigm can be applied to a CRC prevention approach, as the apoptotic effect of butyrate, a diet-derived histone deacetylase inhibitor, is augmented by other dietary agents that modulate survival pathways (e.g., propolis and coffee extract). Thus, dietary supplements composed by fermentable fiber, propolis, and coffee extract may effectively counteract neoplastic growth in the colon.     

Geographical patterns of hoverfly (Diptera,Syrphidae) functional groups in Europe: inconsistency in environmental correlates and latitudinal trends

Abstract 1. Relationships between species richness in higher taxa and large‐scale environmental variables have been widely studied over the past 15 years. Much less is known about how different functional groups (FGs) of species with similar biological and life‐history traits contribute to the overall trends, or how they differ in species‐richness patterns. 2. Multivariate analysis clustered 641 species of Syrphidae into eight FGs on the basis of 10 life‐history features, revealing feeding strategy as the main factor separating the groups. 3. Geographical trends in species richness and determinants of species richness within the FGs were compared across Europe. 4. Total species richness showed no latitudinal trend. However, the richness of individual FGs revealed variable relationships with latitude, including positive, negative, and hump‐shaped ones. This appeared to be related to how different environmental factors affected species richness within FGs. 5. Functional groups differed in their responses to the environmental variables. Annual temperature, evapotranspiration, and elevation span were the most important variables separating the FGs in ordination analysis. The multiple regression models showed further differences between FGs and their responses to the environment. 6. The FG approach revealed important inconsistencies in latitudinal diversity gradients and diversity‐climate relationships.     

Protective effect of quercetin and luteolin in human melanoma HMB-2 cells

Multifunctional effects of flavonoids are reported to be markedly connected with their structure and the functional groups in the molecule. The important role in the activity play C2–C3 double bond, hydroxyl group at C3 and the number of hydroxyl groups at phenyl ring (B). In this paper, the DNA protective free radical scavenging potential of quercetin (QU) and luteolin (LU) against H₂O₂ and their clastogenic effect alone and in combination with melphalan (MH) were investigated in human melanoma HMB-2 cells. Elevated frequency of chromosomal aberrations induced by MH, that at high doses have shown a variety of toxic side effects, was statistically decreased by studied flavonoids regarding to control (QU at the concentration of 50 μM and LU already at the concentration of 20 μM). The results concerning DNA protective potential against free radicals in HMB-2 cells demonstrated that QU and LU have significant effect in dose dependent manner. The percentage of QU protective effect is 40% at the concentration 20 μM, resp. 80% at the concentration 100 μM. Comparable values were obtained with LU. Results are correlated to their structural arrangement and organization of the hydroxyl groups.     

Does plant height determine the freezing resistance in the páramo plants?

Neotropical ecosystems between treeline and snowline, called páramos, stretch along Andean ranges from Costa Rica to northern Peru. The páramo climate is characterized by regular night frosts occurring throughout the year. Páramo plants use two strategies to deal with freezing temperatures. They either avoid ice formation in the tissues or tolerate extracellular ice formation. We tested the microclimate hypothesis, which suggests that the freezing resistance of the páramo plants is determined by plant height, that is, that taller plants experience a milder microclimate and avoid freezing, whereas smaller plants are exposed to the more extreme thermal conditions near the ground and tolerate them. We measured the temperature at which ice formed inside the plants (the ‘exotherm’), and compared it with the temperature at which 50% damage to the tissue occurred (Lt50); a significant difference between the exotherm and Lt50 would indicate freezing tolerance whereas the absence of a difference would indicate avoidance by supercooling. We analysed the freezing resistance of 38 common Ecuadorian páramo species. We found no correlation between plant height and freezing resistance mechanism or injury temperature and reject the microclimate hypothesis. Tolerant plants reach higher altitudes than avoidant plants, but their altitudinal ranges largely overlap and the Lt50 does not differ between them. These results suggest that there is no qualitative difference between the two strategies to survive the páramo frosts. Shrub leaves were injured at significantly lower temperatures than other life forms, such as herbs, which may reflect leaf anatomical differences among the plants.     

Nutrition, body weight and deterioration of familial combined hyperlipidemia

Lipid and apolipoprotein serum levels as a consequence of excessive nutrition in the overweight individuals with familial combined hyperlipidemia (FCHL) in comparison with the obese ones are studied only sporadically. In this study, the effect of overweight and obesity in subjects with FCHL on serum lipids and apolipoproteins was investigated. The participants were 36 overweight and 10 obese men. 17 normolipidemic healthy men served as the control group. The mean age of all subjects included was 49+/-9 years. Lipid and apolipoprotein serum levels were determined by standard methods. The increased body weight in overweight men with FCHL correlates with increased cholesterol and triacylglycerol serum levels (p<0.001), atherogenous ratio values, apolipoprotein serum levels--apo C-III, apo C-II and apo B100oo (p<0.001) as well as decreased HDL cholesterol serum levels (p<0.05). Lipid metabolism in men with FCHL is deteriorated by a high energy intake and its low output. The overweight and not only obesity, in association with FCHL, is an important risk factor for premature development of ischemic events.     

Nature of DNA lesions induced in human hepatoma cells, human colonic cells and human embryonic lung fibroblasts by the antiretroviral drug 3'-azido-3'-deoxythymidine

This study tried to clarify the question if nuclear genotoxicity played a role in 3'-azido-3'-deoxythymidine (AZT) toxicity. We investigated cytotoxic and DNA-damaging effects of AZT on human hepatoma HepG2 and human colonic CaCo-2 cells as well as on human diploid lung fibroblasts HEL. The amount of induced DNA damage was measured by standard alkaline single cell gel electrophoresis (SCGE). The nature of induced DNA lesions was evaluated (1) by modified SCGE, which includes treatment of lysed cells with DNA repair enzymes Endo III and Fpg and enables to recognize oxidized bases of DNA, and (2) by SCGE processed in parallel at pH 13.0 (standard technique) and pH 12.1, which enables to recognize alkali labile DNA lesions and direct DNA strand breaks. Cytotoxicity of AZT was evaluated by the trypan blue exclusion technique. Our findings showed that 3-h treatment of cells with AZT decreased the viability of all cell lines studied. SCGE performed in the presence of DNA repair enzymes proved that AZT induced oxidative lesions to DNA in all cell types. In hepatoma HepG2 cells and embryonic lung fibroblasts HEL the majority of AZT-induced DNA strand breaks were pH-independent, i.e. they were identified at both pH values (12.1 and 13.0). These DNA lesions represented direct DNA breaks. In colonic Caco-2 cells DNA lesions were converted to DNA strand breaks particularly under strong alkaline conditions (pH>13.0), which is characteristic for alkali-labile sites of DNA. DNA strand break rejoining was investigated by the standard comet assay technique during 48 h of post-AZT-treatment in HepG2 and Caco-2 cells. The kinetics of DNA rejoining, considered an indicator of DNA repair, revealed that AZT-induced DNA breaks were repaired in both cell types slowly, though HepG2 cells seemed to be more repair proficient with respect to AZT-induced DNA lesions.