The progamic phase of an early-divergent angiosperm, Annona cherimola (Annonaceae)

33 Pag. The definitive version, with the figures, is available at: http://aob.oxfordjournals.org/Background and Aims: Recent studies of reproductive biology in ancient angiosperm lineages are beginning to shed light on the early evolution of flowering plants, but comparative studies are restricted by fragmented and meagre species representation in these angiosperm clades. In the present study, the progamic phase, from pollination to fertilization, is characterized in Annona cherimola, which is a member of the Annonaceae, the largest extant family among early-divergent angiosperms. Beside interest due to its phylogenetic position, this species is also an ancient crop with a clear niche for expansion in subtropical climates. Methods: The kinetics of the reproductive process was established following controlled pollinations and sequential fixation. Gynoecium anatomy, pollen tube pathway, embryo sac and early post-fertilization events were characterized histochemically. Key Results: A plesiomorphic gynoecium with a semi-open carpel shows a continuous secretory papillar surface along the carpel margins, which run from the stigma down to the obturator in the ovary. The pollen grains germinate in the stigma and compete in the stigma-style interface to reach the narrow secretory area that lines the margins of the semi-open stylar canal and is able to host just one to three pollen tubes. The embryo sac has eight nuclei and is well provisioned with large starch grains that are used during early cellular endosperm development. Conclusions: A plesiomorphic simple gynoecium hosts a simple pollen–pistil interaction, based on a support–control system of pollen tube growth. Support is provided through basipetal secretory activity in the cells that line the pollen tube pathway. Spatial constraints, favouring pollen tube competition, are mediated by a dramatic reduction in the secretory surface available for pollen tube growth at the stigma–style interface. This extramural pollen tube competition contrasts with the intrastylar competition predominant in more recently derived lineages of angiosperms.This work was supported by the Spanish Ministry of Education (Project Grants AGL2004-02290/AGR, AGL2006-13529 and AGL2007-60130/AGR), GIC-Aragón 43, Junta de Andalucía (AGR2742), and the European Union under the INCO-DEV program (Contract 015100). J.L. was supported by a grant from Junta de Andalucía.Peer reviewe

Why Are Some Plant Genera More Invasive Than Others?

Determining how biological traits are related to the ability of groups of organisms to become economically damaging when established outside of their native ranges is a major goal of population biology, and important in the management of invasive species. Little is known about why some taxonomic groups are more likely to become pests than others among plants. We investigated traits that discriminate vascular plant genera, a level of taxonomic generality at which risk assessment and screening could be more effectively performed, according to the proportion of naturalized species which are pests. We focused on the United States and Canada, and, because our purpose is ultimately regulatory, considered species classified as weeds or noxious. Using contingency tables, we identified 11 genera of vascular plants that are disproportionately represented by invasive species. Results from boosted regression tree analyses show that these categories reflect biological differences. In summary, approximately 25% of variation in genus proportions of weeds or noxious species was explained by biological covariates. Key explanatory traits included genus means for wetland habitat affinity, chromosome number, and seed mass

Identification of microRNA activity by Targets' Reverse EXpression

Motivation: Non-coding microRNAs (miRNAs) act as regulators of global protein output. While their major effect is on protein levels of target genes, it has been proven that they also specifically impact on the messenger RNA level of targets. Prominent interest in miRNAs strongly motivates the need for increasing the options available to detect their cellular activity

Apps for Justice

Since they were first established, legal aid programs in the United States have struggled to serve all of the low-income clients in need of legal representation. However, in recent years, a growing number of individuals with moderate-incomes have also found themselves unable to afford legal representation. With too high an income to qualify for free legal services, yet too cash-poor to pay for a market rate attorney, many chose to go pro se, representing themselves in court. As a result, pro se representation has become a growing burden on the U.S. justice system, and furthermore, because clients without legal representation often fare quite poorly in the courts, has severely widened the access to justice gap. Our work has examined the theoretical basis and practical application of one promising solution to the access to justice gap: legal expert systems. Properly designed, legal expert systems can simulate the knowledge and thought processes of a trained attorney through the application of abstract principles to specific cases, simulating the client-attorney interaction to diagnose, infer, and treat the legal problem at hand. In order to test these concepts against the reality of legal practice and the current state of technology the Apps for Justice team has developed two prototype legal expert systems (in the form of web apps): Rights of Tenants in Maine, which uses an interview process to address common landlord-tenant issues through a customized action plan; and Maine Family Law Intake, which replicates a client intake process to produce completed forms for clients filing for divorce.https://digitalcommons.mainelaw.maine.edu/student-impact-summit/1012/thumbnail.jp

Apps for Justice

Since they were first established, legal aid programs in the United States have struggled to serve all of the low-income clients in need of legal representation. However, in recent years, a growing number of individuals with moderate-incomes have also found themselves unable to afford legal representation. With too high an income to qualify for free legal services, yet too cash-poor to pay for a market rate attorney, many chose to go pro se, representing themselves in court. As a result, pro se representation has become a growing burden on the U.S. justice system, and furthermore, because clients without legal representation often fare quite poorly in the courts, has severely widened the access to justice gap. Our work has examined the theoretical basis and practical application of one promising solution to the access to justice gap: legal expert systems. Properly designed, legal expert systems can simulate the knowledge and thought processes of a trained attorney through the application of abstract principles to specific cases, simulating the client-attorney interaction to diagnose, infer, and treat the legal problem at hand. In order to test these concepts against the reality of legal practice and the current state of technology the Apps for Justice team has developed two prototype legal expert systems (in the form of web apps): Rights of Tenants in Maine, which uses an interview process to address common landlord-tenant issues through a customized action plan; and Maine Family Law Intake, which replicates a client intake process to produce completed forms for clients filing for divorce.https://digitalcommons.mainelaw.maine.edu/student-impact-summit/1012/thumbnail.jp

Systems engineering research

International audienceIn this paper, we propose selected research topics that are believed central to progress and growth in the application of systems engineering (SE). As a professional activity, and as an intellectual activity, systems engineering has strong links to such associated disciplines as decision analysis, operation research, project management, quality management, and systems design. When focussing on systems engineering research, we should distinguish between subjects that are of systems engineering essence and others that more closely correspond to those that are more relevant for related disciplines.