Genome-wide association study of stage III/IV grade C periodontitis (former aggressive periodontitis) in a Spanish population.

AIM: To identify loci associated with stages III/IV, grade C periodontitis (PIII/IV-C) through a genome-wide association study (GWAS). MATERIALS AND METHODS: 441 Caucasian Spanish PIII/IV-C cases from the SEPA Network of Research Clinics and 1141 controls from the Banco Nacional de ADN were genotyped with "Axiom Spain Biobank Array," which contains 757836 markers, including rare and low-frequency Spanish variants. The analysis of the individual association and subsequently the gene-level analysis with Sequence Kernel Association Test (SKAT) were carried out adjusting for age, sex and PC1 covariates. Pathway Analysis was additionally performed with Ingenuity Pathway Analysis (IPA) software on the top associated genes. RESULTS: In the individual analyses, no genome-wide significant signals were detected. However, 8 SNPs of 8 loci reached suggestive evidence of association with PIII/IV-C, including FAT3 rs35709256, CSNK1G2 rs4807188, MYH13 rs2074872, CNTN2 rs116611488, ANTXR1 rs4854545, 8p23.2 rs78672540, ANGPT1 rs13439823 and PLEC rs11993287 (p < 5 × 10-6 ). SKAT analysis identified other interesting signals at CNTN2, FBXO44, AP1M2, RSPO4, KRI1, BPIFB1 and INMT, although their probability does not exceed the multiple-test correction. IPA indicated significant enrichment of pathways related to cAMP, IL-2, CD28, VDR/RXR and PI3K/Akt.  CONCLUSIONS: GWAS found no SNPs significantly associated with PIII/IV-C.

Herbicide impact on the growth and reproduction of characteristic and rare arable weeds of winter cereal fields.

The decline of arable species characteristic of winter cereal fields has often been attributed to different factors related to agricultural intensification but most importantly to herbicide use. Herbicide phytotoxicity is most frequently assessed using short-term endpoints, primarily aboveground biomass. However, short-term sensitivity is usually not sufficient to detect actual effects because plants may or may not recover over time following sublethal herbicide exposures. Therefore, it is important to assess the long-term effects of herbicide applications. Annual species rely on renewable seed production to ensure their persistence; hence, assessment of herbicide sensitivity is more accurately estimated through effects on reproduction. Here we aim to assess the phytotoxicity of two commonly used herbicides: tribenuron and 2,4-D on eight plant species belonging to four families, each with one rare and one more common species. Specifically we examined the pattern of sensitivity using short-term and long-term endpoints (total aboveground biomass, total seed biomass and number of seeds) of these species; we determined the levels of and time to recovery in terms of stem length and fruit number, and assessed whether their rarity relates to their sensitivity to herbicide application. Our results suggest that although differences in herbicide sensitivity are not a direct cause of rarity for all species, it may be an important driver of declining arable plants.

Reduced seed predation after invasion supports enemy release in a broad biogeographical survey.

The Enemy Release (ER) hypothesis predicts an increase in the plant invasive capacity after being released from their associated herbivores or pathogens in their area of origin. Despite the large number of studies on biological invasions addressing this hypothesis, tests evaluating changes in herbivory on native and introduced populations and their effects on plant reproductive potential at a biogeographical level are relatively rare. Here, we tested the ER hypothesis on the South African species Senecio pterophorus (Asteraceae), which is native to the Eastern Cape, has expanded into the Western Cape, and was introduced into Australia (>70-100 years ago) and Europe (>30 years ago). Insect seed predation was evaluated to determine whether plants in the introduced areas were released from herbivores compared to plants from the native range. In South Africa, 25 % of the seedheads of sampled plants were damaged. Plants from the introduced populations suffered lower seed predation compared to those from the native populations, as expected under the ER hypothesis, and this release was more pronounced in the region with the most recent introduction (Europe 0.2 % vs. Australia 15 %). The insect communities feeding on S. pterophorus in Australia and Europe differed from those found in South Africa, suggesting that the plants were released from their associated fauna after invasion and later established new associations with local herbivore communities in the novel habitats. Our study is the first to provide strong evidence of enemy release in a biogeographical survey across the entire known distribution of a species.

Not All Field Margins Are Equally Useful: Effects of the Vegetation Structure of Margins on Cereal Aphids and Their Natural Enemies.

Differences in the semi-natural vegetation of field margins will affect the biological control services derived from the presence of these semi-natural habitats adjacent to fields. Of the plant functional traits that are most relevant for insects, plant life forms reflect different aspects of plant structure and functioning that can help predict the value of marginal vegetation for arthropods in agricultural systems. The aim of this study was to determine the effect of the vegetation structure of field margins on cereal aphids and on some of their natural enemies (parasitoids, hoverflies and ladybugs) in terms of plant life forms. We characterized margin vegetation using the relative cover of each life form and sampled insects in crops along transects parallel to field margins. Our results show that in the studied areas, the abundance of natural enemies was greater near margins dominated by annual plants than in margins dominated by perennial plants. On the other hand, the abundances of aphids and parasitism rates were higher near margins dominated by perennial woody plants than near margins dominated by perennial herbaceous plants. By promoting specific life forms in existing margins, farmers can enhance the conservation biological control and relieve aphid pressure on their crops.