2,012 research outputs found
Floral nectar: fifty years of new ecological perspectives beyond pollinator reward
Floral nectar is central to ecology, since it mediates interactions with pollinators, flower-visiting
antagonists and microbes through its chemical composition. Here we review how historical
assumptions about its ecological meaning were first challenged, then modified and expanded since
the discovery of secondary metabolites in nectar. We then explore the origin of specific neuroactive
nectar compounds known to act as important insect neurotransmitters, and how advances in the field
of bee cognition and plant-microbe-animal interactions challenge such historical views. As all actors
involved in the latter interactions are under simultaneous reciprocal selective pressures, their
coexistence is characterized by conflicts and trade-offs, the evolutionary interpretation of which
suggests exciting new perspectives in one of the longest studied aspects of plant-pollinator
interactions
Secondary Metabolites in Nectar-Mediated Plant-Pollinator Relationships
n recent years, our understanding of the complex chemistry of floral nectar and its ecological implications for plant-pollinator relationships has certainly increased. Nectar is no longer considered merely a reward for pollinators but rather a plant interface for complex interactions with insects and other organisms. A particular class of compounds, i.e., nectar secondary compounds (NSCs), has contributed to this new perspective, framing nectar in a more comprehensive ecological context. The aim of this review is to draft an overview of our current knowledge of NSCs, including emerging aspects such as non-protein amino acids and biogenic amines, whose presence in nectar was highlighted quite recently. After considering the implications of the different classes of NSCs in the pollination scenario, we discuss hypotheses regarding the evolution of such complex nectar profiles and provide cues for future research on plant-pollinator relationships
Physics of the Earth system: design and implementation of an experimental educational module for high school students
Correlating Fluorescence and High-Resolution Scanning Electron Microscopy (HRSEM) for the study of GABAA receptor clustering induced by inhibitory synaptic plasticity
Both excitatory and inhibitory synaptic contacts display activity dependent
dynamic changes in their efficacy that are globally termed synaptic
plasticity. Although the molecular mechanisms underlying glutamatergic
synaptic plasticity have been extensively investigated and described, those
responsible for inhibitory synaptic plasticity are only beginning to be
unveiled. In this framework, the ultrastructural changes of the inhibitory
synapses during plasticity have been poorly investigated. Here we combined
confocal fluorescence microscopy (CFM) with high resolution scanning electron
microscopy (HRSEM) to characterize the fine structural rearrangements of post-
synaptic GABAA Receptors (GABAARs) at the nanometric scale during the
induction of inhibitory long-term potentiation (iLTP). Additional electron
tomography (ET) experiments on immunolabelled hippocampal neurons allowed the
visualization of synaptic contacts and confirmed the reorganization of post-
synaptic GABAAR clusters in response to chemical iLTP inducing protocol.
Altogether, these approaches revealed that, following the induction of
inhibitory synaptic potentiation, GABAAR clusters increase in size and number
at the post-synaptic membrane with no other major structural changes of the
pre- and post-synaptic elements
ÂżConviene buscar petrĂłleo en el mar?
El economista Barberis Bosch y la ambientalista Di Paola analizan la producciĂłn de hidrocarburos y el desarrollo energĂ©tico con miradas distintas.Fil: Barberis Bosch, Francisco. Universidad Nacional de Mar del Plata. Facultad de Ciencias EconĂłmicas y Sociales; Argentina.Fil: Di Paola, MarĂa Marta. FundaciĂłn Ambiente y Recursos Naturales, Argentina
Identification and antibiotic susceptibility of viridans group streptococci isolates recovered from patients hospitalized at a teaching hospital in Buenos Aires City
Members of the viridans group streptococci (VGS) are the cause of local and invasive infections. Due to the severity of these infections and taking into account that reports regarding epidemiological aspects are scarce, the aims of this work were the identification and the study of the antibiotic susceptibility profiles of the isolates recovered from patients that were hospitalized in order to find out about the resistance level and the epidemiology of infections in which VGS are involved. A hundred and thirty two isolates identified as VGS were isolated at Hospital de ClĂnicas «JosĂ© de San MartĂn» during the period 2011-2015. The identification was performed by biochemical test and mass spectrometry by Matrix Assisted Laser Desorption Ionization -Time of Flight Mass Spectrometry. Streptococcus anginosus group was prevalent (42%) followed by Streptococcus mitis group (33%). In the latter, isolates of Streptococcus pneumoniae were excluded. All the VGS isolates were susceptible to ertapenem, meropenem, linezolid and vancomycin; 25.8% were resistant (I+R) to penicillin, being prevalent in the S. mitis group. Regarding ceftriaxone and cefepime 96.9% of the isolates were susceptible. Only two isolates were resistant to levofloxacin, 27.2% to tetracycline and it was not found high level resistance to gentamycin (MIC range 0.5-32 ÎŒg/ml). Resistance to erythromycin was 17.4% with no significant difference between M and MLS phenotypes. The most active antibiotics were in addition to ceftriaxone and cefepime, vancomycin, ertapenem, meropenem and linezolid. These results highlight the importance of the continuous surveillance of the infections caused by VGS in order to predict a correct antibiotic therapy.Fil: Heine, Adriana C.. Universidad de Buenos Aires. Facultad de Medicina. Hospital de ClĂnicas General San MartĂn; ArgentinaFil: GarcĂa, Susana. Universidad de Buenos Aires. Facultad de Medicina. Hospital de ClĂnicas General San MartĂn; ArgentinaFil: Barberis, Claudia. Universidad de Buenos Aires. Facultad de Medicina. Hospital de ClĂnicas General San MartĂn; ArgentinaFil: Vay, Carlos Alberto. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Houssay; Argentina. Universidad de Buenos Aires. Facultad de Medicina. Hospital de ClĂnicas General San MartĂn; ArgentinaFil: Mollerach, Marta Eugenia. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Houssay; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y BioquĂmica. Departamento de MicrobiologĂa, InmunologĂa y BiotecnologĂa; ArgentinaFil: Bonofiglio, Laura. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Houssay; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y BioquĂmica. Departamento de MicrobiologĂa, InmunologĂa y BiotecnologĂa; ArgentinaFil: Famiglietti, Ăngela. Universidad de Buenos Aires. Facultad de Medicina. Hospital de ClĂnicas General San MartĂn; Argentin
Distasteful nectar deters floral robbery
Toxic nectar is an ecological paradox[1,2]. Plants divert substantial resources to produce nectar that attracts pollinators [3], but toxins in this reward could disrupt the mutualism and reduce plant fitness [4]. Alternatively, such compounds could protect nectar from robbers [2], provided they do not significantly alter pollinator visitation to the detriment of plant fitness [1,5â8]. Indeed, very few studies have investigated the role of plant toxins in nectar for defence against nectar robbers [4,9,10]. Here, we compared two Aconitum species (A. napellus and A. lycoctonum) that have flowers specialized for long-tongued bumblebee pollinators (Bombus hortorum) but are occasionally robbed by short-tongued bumblebees (B. terrestris) [6,11â13]. Pollinator visits to flowers were much more frequent than by robbers but visits correlated negatively with nectar alkaloid concentration and declined sharply between 200-380ppm. However, alkaloid concentrations of > 20ppm were deterrent to B. terrestris suggesting robbers were less tolerant of nectar alkaloids. Nectar of both plant species contained similar concentrations of carbohydrates and toxic alkaloids, but A. lycoctonum was more likely to secrete nectar in each flower and was also visited more frequently by pollinators and robbers. We conclude that alkaloids in Aconitum sp. nectar affect rates of both pollinator visitation and robbery but may have co-evolved with nectar availability to maintain the fitness benefits of specialized plant-pollinator relationships. Chemical defence of nectar is, however, ultimately constrained by pollinator gustatory sensitivity
Identifying bottlenecks in the life cycle of plants living on cliffs and rocky slopes : lack of knowledge hinders conservation actions
Long term survival of plant populations relies on successful reproductive cycle to obtain generation turnover.
Focusing on plant species of conservation concern, we brought together a group of plant conservationists from
different countries to assess whether the already available information on plant reproductive biology and
autecology is adequate for identifying which phases of single species life cycle might act as bottleneck.
We compiled a list of 80 plant species of conservation concern living on European cliffs and rocky slopes, for
which biological and autecological information was collected from scientific literature, technical reports, and
expert knowledge.
Results have shown that the available information on species reproductive biology and autecology is inadequate
to identify bottlenecks in the life cycle of many species and to provide insights for the practical conservation
of many more. Available knowledge is mainly referred to the flowering phase, less on seed production and
much less on seedling establishment and on cloning. Meanwhile and noteworthy, flowering resulted to be the less
critical phase for the fulfilment of the species life cycle.
Overall, with this perspective article we aim to encourage a constructive debate among the scientific community
members and policymakers to set up novel concerted strategies for the conservation of plant species of
conservation concern. The challenge of the discussion is the implementation of the current approach with new biological and ecological information to be exclusively targeted at identifying the constraints that limit the
generation turnover and furnishing specific indications for active management.peer-reviewe
Notulae to the Italian flora of algae, bryophytes, fungi and lichens: 7
In this contribution, new data concerning algae, bryophytes, fungi, and lichens of the Italian flora are presented. It includes new records and confirmations for the algae genus Chara, the bryophyte genera Cephalozia, Conardia, Conocephalum, Didymodon, Sphagnum, Tetraplodon, and Tortula, the fungal genera Endophyllum, Gymnosporangium, Microbotryum, Phragmidium, and Pluteus, and the lichen genera Candelariella, Cladonia, Flavoplaca, Lichenothelia, Peltigera, Placolecis, Rinodina, Scytinium, and Solenopsora
- âŠ