Above- and belowground herbivory jointly impact defense and seed dispersal traits in Taraxacum officinale

Plants are able to cope with herbivores by inducing defensive traits or growth responses that allow them to reduce or avoid the impact of herbivores. Since above- and belowground herbivores differ substantially in life-history traits, for example feeding types, and their spatial distribution, it is likely that they induce different responses in plants. Moreover, strong interactive effects on defense and plant growth are expected when above- and belowground herbivores are jointly present. The strengths and directions of these responses have been scarcely addressed in the literature. Using Taraxacum officinale, the root-feeding nematode Meloidogyne hapla and the locust Schistocerca gregaria as a model species, we examined to what degree above- and belowground herbivory affect (1) plant growth responses, (2) the induction of plant defensive traits, that is, leaf trichomes, and (3) changes in dispersal-related seed traits and seed germination. We compared the performance of plants originating from different populations to address whether plant responses are conserved across putative different genotypes. Overall, aboveground herbivory resulted in increased plant biomass. Root herbivory had no effect on plant growth. Plants exposed to the two herbivores showed fewer leaf trichomes than plants challenged only by one herbivore and consequently experienced greater aboveground herbivory. In addition, herbivory had effects that reached beyond the individual plant by modifying seed morphology, producing seeds with longer pappus, and germination success

Introduction

Collective identities and transnational networks in medieval and early modern Europe, 1000-180

Molecular and functional analysis of the XPBC/ERCC-3 promoter: Transcription activity is dependent on the integrity of an Sp1 binding element.

The human XPBC/ERCC-3 gene, which corrects the excision-repair defect in xeroderma pigmentosum group B cells and the UV-sensitive CHO mutant 27-1 cells, appears to be expressed constitutively in various cell types and tissues. We have analysed the structure and functionality of the XPBC/ERCC-3 promoter. Transcription of the XPBC/ERCC-3 gene is initiated from heterogeneous sites, with a major startpoint mapped at position -54 (relative to the translation start codon ATG). The promoter region does not possess classical TATA and CAAT elements, but it is GC-rich and contains three putative Sp1-binding sites. In addition, there are two elements related to the cyclic AMP (cAMP)-response element (CRE) and the 12-O-tetradecanoyl phorbol-13-acetate-response element (TRE) in the 5'-flanking reg

Affinity purification of human DNA repair/transcription factor TFIIH using epitope-tagged xeroderma pigmentosum B protein

TFIIH is a high molecular weight complex with a remarkable dual function in nucleotide excision repair and initiation of RNA polymerase II transcription. Mutations in the largest subunits, the XPB and XPD helicases, are associated with three inherited disorders: xeroderma pigmentosum, Cockayne's syndrome, and trichothiodystrophy. To facilitate the purification and biochemical characterization of this intricate complex, we generated a cell line stably expressing tagged XPB, allowing the

Urbanization alters plastic responses in the common dandelion Taraxacum officinale

Urban environments expose species to contrasting selection pressures relative to rural areas due to altered microclimatic conditions, habitat fragmentation, and changes in species interactions. To improve our understanding on how urbanization impacts selection through biotic interactions, we assessed differences in plant defense and tolerance, dispersal, and flowering phenology of a common plant species (Taraxacum officinale) along an urbanization gradient and their reaction norms in response to a biotic stressor (i.e., herbivory). We raised plants from 45 lines collected along an urbanization gradient under common garden conditions and assessed the impact of herbivory on plant growth (i.e., aboveground biomass), dispersal capacity (i.e., seed morphology), and plant phenology (i.e., early seed production) by exposing half of our plants to two events of herbivory (i.e., grazing by locusts). Independent from their genetic background, all plants consistently increased their resistance to herbivores by which the second exposure to locusts resulted in lower levels of damage suffered. Herbivory had consistent effects on seed pappus length, with seeds showing a longer pappus (and, hence, increased dispersal capacities) regardless of urbanization level. Aboveground plant biomass was neither affected by urbanization nor herbivore presence. In contrast to consistent responses in plant defenses and pappus length, plant fitness did vary between lines. Urban lines had a reduced early seed production following herbivory while rural and suburban lines did not show any plastic response. Our results show that herbivory affects plant phenotypes but more importantly that differences in herbivory reaction norms exist between urban and rural populations

Cochrane Corner: Hearing aids for mild to moderate hearing loss in adults

This Cochrane Corner features the review entitled “Hearing aids for mild to moderate hearing loss in adults” published in 2017. In their review, Ferguson et al. identified five randomised controlled trials (RCTs) involving 825 participants, with moderate quality of evidence shown for all domains except adverse effects. Results showed a large beneficial effect of hearing aids on hearing-specific health-related quality of life and listening ability, and a small yet significant beneficial effect on overall health related quality of life. Ferguson et al. concluded that according to the available evidence, hearing aids are effective at improving hearing-specific health-related quality of life, general health related quality of life and listening ability in adults with mild to moderate hearing loss. The evidence supports the widespread provision of hearing aids as the first-line clinical management for those seeking help for hearing difficulties

Base excision repair deficient mice lacking the Aag alkyladenine DNA glycosylase.

3-methyladenine (3MeA) DNA glycosylases remove 3MeAs from alkylated DNA to initiate the base excision repair pathway. Here we report the generation of mice deficient in the 3MeA DNA glycosylase encoded by the Aag (Mpg) gene. Alkyladenine DNA glycosylase turns out to be the major DNA glycosylase not only for the cytotoxic 3MeA DNA lesion, but also for the mutagenic 1,N6-ethenoadenine (epsilonA) and hypoxanthine lesions. Aag appears to be the only 3MeA and hypoxanthine DNA glycosylase in liver, testes, kidney, and lung, and the only epsilonA DNA glycosylase in liver, testes, and kidney; another epsilonA DNA glycosylase may be expressed in lung. Although alkyladenine DNA glycosylase has the capacity to remove 8-oxoguanine DNA lesions, it does not appear to be the major glycosylase for 8-oxoguanine repair. Fibroblasts derived from Aag -/- mice are alkylation sensitive, indicating that Aag -/- mice may be similarly sensitive

Disruption of mouse ERCC1 results in a novel repair syndrome with growth failure, nuclear abnormalities and senescence.

BACKGROUND: The structure-specific ERCC1/XPF endonuclease complex that contains the ERCC1 and XPF subunits is implicated in the repair of two distinct types of lesions in DNA: nucleotide excision repair (NER) for ultraviolet-induced lesions and bulky chemical adducts; and recombination repair of the very genotoxic interstrand cross-links. RESULTS: Here, we present a detailed analysis of two types of mice with mutations in ERCC1, one in which the gene is 'knocked out', and one in which the encoded protein contains a seven amino-acid carboxy-terminal truncation. In addition to the previously reported symptoms of severe runting, abnormalities of liver nuclei and greatly reduced lifespan (which appeared less severe in the truncation mutant), both types of ERCC1-mutant mouse exhibited an absence of subcutaneous fat, early onset of ferritin deposition in the spleen, kidney malfunction, gross abnormalities of ploidy and cytoplasmic invaginations in nuclei of liver and kidney, and compromised NER and cross-link repair. We also found that heterozygosity for ERCC1 mutations did not appear to provide a selective advantage for chemically induced tumorigenesis. An important clue to the cause of the very severe ERCC1-mutant phenotypes is our finding that ERCC1-mutant cells undergo premature replicative senescence, unlike cells from mice with a defect only in NER. CONCLUSIONS: Our results strongly suggest that the accumulation in ERCC1-mutant mice of endogenously generated DNA interstrand cross-links, which are normally repaired by ERCC1-dependent recombination repair, underlies both the early onset of cell cycle arrest and polyploidy in the liver and kidney. Thus, our work provides an insight into the molecular basis of ageing and highlights the role of ERCC1 and interstrand DNA cross-links