The acquisition of finiteness in English by child second language learners in instructed contexts: age of onset and L1 effects

This thesis examines the acquisition of finiteness in English by child L2 learners by investigating the impact of the age of onset and the role of the learners’ L1 on their L2 acquisition. Following Meisel’s hypothesis that children older than 4 will resemble adult L2 acquisition in the domain of inflectional morphology, I investigated how two groups of children of different L1s and older than 4 learn the features of tense and agreement and whether accuracy would be declining as an effect of an older age of onset. Participants were 73 Chinese and 74 Russian learners who were aged either 9 or 12 at time of testing and had age of onset of learning English at ages 4 and 7 respectively. Children were all EFL learners recruited from EF (English First) private afternoon English language schools in Shanghai and Moscow, where children attended classes for a few hours a week. To assess children’s performance, I employed two types of tasks: two elicited production tasks whose prompts involved 3SG-agreement and past tense contexts (TEGI), and a freer type of elicitation prompting stories based on a sequence of pictures (MAIN). Data analysis demonstrated low accuracy, high numbers of omissions, asymmetries in the acquisition of morphemes, overgeneralisation of the progressive tense in 3SG-habitual contexts, and use of the periphrastic structure ‘is + verb(x)’. These results show that L2 children resemble aL2 acquisition supporting Meisel’s hypothesis. The empirical findings are interpreted in light of two opposing views that account for the optionality in verb inflection in L2 acquisition; the Full Access to UG and the Representational Deficit approaches; as argued data are more consistent with a representational deficit account. Older children consistently outperformed younger ones; as features are inaccessible, older learners compensate by relying on their higher cognitive abilities, learning strategies and metalinguistic skills, while younger children are mostly implicit learners using more the periphrastic structure as immersed children do. The periphrastic structure appears to be a stage in L2 development of verb morphology in English which denotes the emergence of finiteness as a category being triggered semantically through interpretable features of be. This is a first stage toward activation of uninterpretable features. Finally, signs of L1 influence became more pronounced in older learners; it was the older children showing more L1 effects, a finding which is again more consistent with a representational deficit account.PhD Studentship Agreement in the Department of Theoretical and Applied Linguistics with EF Education Firs

Chrysolina herbacea Modulates Terpenoid Biosynthesis of Mentha aquatica L.

Interactions between herbivorous insects and plants storing terpenoids are poorly understood. This study describes the ability of Chrysolina herbacea to use volatiles emitted by undamaged Mentha aquatica plants as attractants and the plant's response to herbivory, which involves the production of deterrent molecules. Emitted plant volatiles were analyzed by GC-MS. The insect's response to plant volatiles was tested by Y-tube olfactometer bioassays. Total RNA was extracted from control plants, mechanically damaged leaves, and leaves damaged by herbivores. The terpenoid quantitative gene expressions (qPCR) were then assayed. Upon herbivory, M. aquatica synthesizes and emits (+)-menthofuran, which acts as a deterrent to C. herbacea. Herbivory was found to up-regulate the expression of genes involved in terpenoid biosynthesis. The increased emission of (+)-menthofuran was correlated with the upregulation of (+)-menthofuran synthase

New live screening of plant-nematode interactions in the rhizosphere

Abstract Free living nematodes (FLN) are microscopic worms found in all soils. While many FLN species are beneficial to crops, some species cause significant damage by feeding on roots and vectoring viruses. With the planned legislative removal of traditionally used chemical treatments, identification of new ways to manage FLN populations has become a high priority. For this, more powerful screening systems are required to rapidly assess threats to crops and identify treatments efficiently. Here, we have developed new live assays for testing nematode responses to treatment by combining transparent soil microcosms, a new light sheet imaging technique termed Biospeckle Selective Plane Illumination Microscopy (BSPIM) for fast nematode detection, and Confocal Laser Scanning Microscopy for high resolution imaging. We show that BSPIM increased signal to noise ratios by up to 60 fold and allowed the automatic detection of FLN in transparent soil samples of 1.5 mL. Growing plant root systems were rapidly scanned for nematode abundance and activity, and FLN feeding behaviour and responses to chemical compounds observed in soil-like conditions. This approach could be used for direct monitoring of FLN activity either to develop new compounds that target economically damaging herbivorous nematodes or ensuring that beneficial species are not negatively impacted

Comparative genomics of the major parasitic worms

Parasitic nematodes (roundworms) and platyhelminths (flatworms) cause debilitating chronic infections of humans and animals, decimate crop production and are a major impediment to socioeconomic development. Here we report a broad comparative study of 81 genomes of parasitic and non-parasitic worms. We have identified gene family births and hundreds of expanded gene families at key nodes in the phylogeny that are relevant to parasitism. Examples include gene families that modulate host immune responses, enable parasite migration though host tissues or allow the parasite to feed. We reveal extensive lineage-specific differences in core metabolism and protein families historically targeted for drug development. From an in silico screen, we have identified and prioritized new potential drug targets and compounds for testing. This comparative genomics resource provides a much-needed boost for the research community to understand and combat parasitic worms

Phytochemistry in the development of pesticides and biocides

To date biopesticides and biocides are studied as substitutes for their toxic synthetic ancestors. The botanical pesticides are evaluated as tools intended for integrated crop protection schemes, while the natural biocides for their potential use in residential areas. In this study we evaluate various botanical matrixes for the nematicidal properties against the root knot nematode Meloidogyne spp., in the form of pastes and extracts for soil amendment as well as plant secondary metabolites isolated from the afore mentioned matrixes and used individually or in binary mixtures to create synergism. The effects of the treatment compound/s are evaluated in various growth stages of the parasite, considering physiology and behavior. Additionally we investigate the use of botanical extracts as natural biocides for the control of toxic cyanobacteria Aphanizomenon gracile in fresh waters. A first attempt is made to formulate a natural algicidal compound into a slow release product that could permit a long lasting biological activity and thus higher efficacy under open air condition