No abstract

Background: Breast cancer (BRCA) is a heterogeneous disease, characterized by different histopathological and clinical features and responses to various therapeutic measures. Despite the research progress of DNA methylation in classification and diagnosis of BRCA and the close relationship between DNA methylation and hormone receptor status, especially estrogen receptor (ER), the epigenetic mechanisms in various BRCA subtypes and the biomarkers associated with diagnostic characteristics of patients under specific hormone receptor status remain elusive. Results: In this study, we collected and analyzed methylation data from 785 invasive BRCA and 98 normal breast tissue samples from The Cancer Genome Atlas (TCGA) database. Consensus classification analysis revealed that ERpositive BRCA samples were constitutive of two distinct methylation subgroups; with the hypomethylated subgroup showing good survival probability. This finding was further supported by another cohort of ER-positive BRCA containing 30 subjects. Additionally, we identified 977 hypomethylated CpG loci showing significant associations with good survival probability in ER-positive BRCA. Genes with these loci were enriched in cancerrelated pathways (e.g., Wnt signaling pathway). Among them, the upregulated 47 genes were also in line with good survival probability of ER-positive BRCA, while they showed significantly negative correlations between their expression and methylation level of certain hypomethylated loci. Functional assay in numerous literatures provided further evidences supporting that some of the loci have close links with the modulation of tumor-suppressive mechanisms via regulation gene transcription (e.g., SFRP1 and WIF1). Conclusions: Our study identified a hypomethylated ER-positive BRCA subtype. Notably, this subgroup presented the best survival probability compared with the hypermethylated ER-positive and hypomethylated ER-negative BRCA subtypes. Specifically, we found that certain upregulated genes (e.g., SFRP1 and WIF1) have great potential to suppress the progression of ER-positive BRCA, concurrently exist negative correlations between their expression and methylation of corresponding hypomethylated CpG loci. Therefore, our study indicates that different epigenetic mechanisms likely exist in ER-positive BRCA and provides novel clinical biomarkers specific to ER-positive BRCA diagnosis and therapy.

Many arthropods exhibit flower-visiting behavior, including a variety of spider species. However, as spiders are assumed to be strictly predatory, flower-visiting spiders are an often neglected group. We conducted a systematic biodiversity study of flower-visiting spiders based on published papers and field surveys. Most previous studies have focused on the herbivorous behavior of flower-visiting spiders (nectivory or pollinivory) and their effects on host flowers (tritrophic interactions with flower-visiting insects). In our field survey, we utilized standard transect walks (active sampling) and colored pan traps (passive sampling) to investigate species occurrence, diurnal and seasonal variation, and flower color preference of flower-visiting spiders. From the transect walks, crab spider species were found to be the dominant flower-visiting spiders and, based on all spider species, juvenile visitors were significantly more common than adults. Furthermore, in terms of spider number and species richness, tulips were the preferred flower to visit. For the pan traps, wolf spiders were found to be the dominant spider species. No significant differences were observed in the number of spiders caught in different colored pans, suggesting that color may not be an important flower trait in regard to spider preference. To the best of our knowledge, this study is the first to propose the term ‘flower-visiting spiders’ and conduct a systematic investigation of their diversity. However, this is preliminary research and further studies are required, especially as biodiversity is often closely linked to survey sites and ecotopes.

1. Crab spiders (Thomisidae) are common flower-visiting spiders that ambush prey on inflorescences. As such, they require specific flowers or substrates for hunting, which are most often selected using sensory cues (e.g. vision). However, few studies have examined the visual preference of crab spiders for particular flowers. In this study, the visual preferences of the crab spider Ebrechtella tricuspidata for different inflorescence characteristics (e.g. colour and shape) were investigated.2. The results showed that adult spiders explored all colours and shapes, whereas juvenile spiders displayed an overall preference for long (red) and short (purple) wavelength colours. Thus, differences in colour were not particularly important for E. tricuspidata with regard to visual attractiveness and selection.3. However, inflorescence shape (e.g. tulip) was found to be a more desirable trait for selection, which was probably due to the provision of shelter.4. These results also suggest that male preference for female spiders depended somewhat on the background colour (wavelength) of the flower on which the female was located.

The increasing concentration of carbon dioxide in atmosphere is not only a major cause of global warming, but it also adversely affects the ecological diversity of invertebrates. This study was conducted to evaluate the effect of elevated CO2 concentration (ambient, 400 ppm and high, 800 ppm) and Wolbachia (Wolbachia‐infected, W+ and Wolbachia‐uninfected, W−) on Hylyphantes graminicola. The total survival rate, developmental duration, carapace width and length, body weight, sex ratio, net reproductive rate, nutrition content, and enzyme activity in H. graminicola were examined under four treatments: W− 400 ppm, W− 800 ppm, W+ 400 ppm, and W+ 800 ppm. Results showed that Wolbachia‐infected spiders had significantly decreased the total developmental duration. Different instars showed variations up to some extent, but no obvious effect was found under elevated CO2 concentration. Total survival rate, sex ratio, and net reproductive rate were not affected by elevated CO2 concentration or Wolbachia infection. The carapace width of Wolbachia‐uninfected spiders decreased significantly under elevated CO2 concentration, while the width, length and weight were not significantly affected in Wolbachia‐infected spiders reared at ambient CO2 concentration. The levels of protein, specific activities of peroxidase, and amylase were significantly increased under elevated CO2 concentration or Wolbachia‐infected spiders, while the total amino content was only increased in Wolbachia‐infected spiders. Thus, our current finding suggested that elevated CO2 concentration and Wolbachia enhance nutrient contents and enzyme activity of H. graminicola and decrease development duration hence explore the interactive effects of factors which were responsible for reproduction regulation, but it also gives a theoretical direction for spider's protection in such a dynamic environment. Increased activities of enzymes and nutrients caused by Wolbachia infection aids for better survival of H. graminicola under stress.

Chemical signals are important to all living organisms, especially to plants which don’t have vision or mobility. Plant volatiles participate in the competition between plants, herbivores and predators; meanwhile, the tritrophic interactions promote the evolution of plant volatiles. To our knowledge, spiders are common predators in the interactions, but only few studies have begun to investigate what floral volatiles do to spiders. Here, we used Ebrechtella tricuspidata and their common host flowers (tulips) found in our previous field survey to determine the volatile scent preference of spiders for host flowers. Eight main floral volatile scent compounds of tulips were picked out and tested in dual choice behavioural assays. E. tricuspidata showed a significant avoidance of α-pinene and no preference for limonene, β-ocimene, linalool, benzaldehyde, benzyl-alcohol, methyl-salicylate, or 2-phenylethanol. The results illustrate that facultative flower visitor E. tricuspidata is not popular among some kinds of tulip. This probably represents a typical response: facultative flower visitors cannot tolerate all defensive floral volatile scents. Compared with previous studies, we detect that the same floral volatile scent compound has different effects on different spiders, indicating that floral volatile scent compounds attract and reject spiders with specificity and they evolved for different functions and targets. However, this is a preliminary study on the effects of chemical signals on plant-spider interactions, both chemical and physical signals should be considered in future research.

Hylyphantes graminicola is a resident spider species found in maize and cotton fields and is an important biological control agent of various pests. Previous studies have demonstrated that stress from elevated CO2 and Wolbachia infection can strongly affect spider species. Thus, based on CO2 levels (400 ppm, current atmospheric CO2 concentration and 800 ppm, high CO2 concentration) and Wolbachia status (Wolbachia‐infected, W+ and Wolbachia‐uninfected, W−), we divided H. graminicola individuals into four treatment groups: W− 400 ppm, W− 800 ppm, W+ 400 ppm, and W+ 800 ppm. To investigate the effects of elevated CO2 levels (W− 400 vs W− 800), Wolbachia infection (W− 400 vs W+ 400), and the interactions between these two factors (W− 400 vs W+ 800), high‐throughput transcriptome sequencing was employed to characterize the de novo transcriptome of the spiders and identify stress‐related differentially expressed genes (DEGs). De novo assembly of complementary DNA sequences generated 86 688 unigenes, 23 938 of which were annotated in public databases. A total of 84, 21, and 157 DEGs were found among W− 400 vs W− 800, W− 400 vs W+ 400, and W− 400 vs W+ 800, respectively. Functional enrichment analysis revealed that metabolic processes, signaling, and catalytic activity were significantly affected by elevated CO2 levels and Wolbachia infection. Our findings suggest that the impact of elevated CO2 levels and Wolbachia infection on the H. graminicola transcriptome was, to a large extent, on genes involved in metabolic processes. This study is the first description of transcriptome changes in response to elevated CO2 levels and Wolbachia infection in spiders.