Efectos de la biota edáfica en las interacciones planta-insecto a nivel foliar

A pesar de la inmensa diversidad de especies que habitan en el suelo y de la importancia funcional que tiene la biota edáfica tanto a nivel de comunidad como de ecosistema, la teoría ecológica ha tenido tradicionalmente sólo en cuenta las interacciones que ocurren en la parte aérea de las plantas. Recientemente esta situación ha cambiado y durante los últimos diez años se han publicado numerosos estudios que destacan la importancia que tienen las interacciones bióticas entre plantas y organismos edáficos sobre diferentes procesos que se dan enla parte aérea. Estos estudios han demostrado que las interacciones que se dan entre las raíces y los herbívoros edáficos, los hongos mutualistas y la flora microbiana, tienen efecto no sólo en el crecimiento de las plantas sino también en niveles tróficos superiores como son los herbívoros foliares, parasitoides, hiperparasitoides y polinizadores. En este artículo se hace una breve revisión de los mecanismos fundamentales que median la relación entre la biota edáfica y las interacciones bióticas de la parte aérea. Por último, se proponen abordajes complementarios como son la utilización de modelos espaciales y el estudio de estas interacciones desde una perspectiva evolutiva

Seasonal phenology of the major insect pests of quinoa (Chenopodium quinoa willd.) and their natural enemies in a traditional zone and two new production zones of Peru

Over the last decade, the sown area of quinoa (Chenopodium quinoa Willd.) has been increasingly expanding in Peru, and new production fields have emerged, stretching from the Andes to coastal areas. The fields at low altitudes have the potential to produce higher yields than those in the highlands. This study investigated the occurrence of insect pests and the natural enemies of quinoa in a traditional production zone, San Lorenzo (in the Andes), and in two new zones at lower altitudes, La Molina (on the coast) and Majes (in the "Maritime Yunga" ecoregion), by plant sampling and pitfall trapping. Our data indicated that the pest pressure in quinoa was higher at lower elevations than in the highlands. The major insect pest infesting quinoa at high densities in San Lorenzo was Eurysacca melanocampta; in La Molina, the major pests were E. melanocampta, Macrosiphum euphorbiae and Liriomyza huidobrensis; and in Majes, Frankliniella occidentalis was the most abundant pest. The natural enemy complex played an important role in controlling M. euphorbiae and L. huidobrensis by preventing pest resurgence. The findings of this study may assist quinoa producers (from the Andes and from regions at lower altitudes) in establishing better farming practices in the framework of integrated pest management

A reexamination of the effective fine structure constant of graphene, as measured in graphite

We present a refined and improved study of the influence of screening on the effective fine structure constant of graphene, $\alpha^*$, as measured in graphite using inelastic x-ray scattering. This follow-up to our previous study [J. P. Reed, et al., Science 330, 805 (2010)] was carried out with two times better energy resolution, five times better momentum resolution, and improved experimental setup with lower background. We compare our results to RPA calculations and evaluate the relative importance of interlayer hopping, excitonic corrections, and screening from high energy excitations involving the $\sigma$ bands. We find that the static, limiting value of $\alpha^*$ falls in the range 0.25 to 0.35, which is higher than our previous result of 0.14, but still below the value expected from RPA. We show the reduced value is not a consequence of interlayer hopping effects, which were ignored in our previous analysis, but of a combination of excitonic effects in the $\pi \rightarrow \pi^*$ particle-hole continuum, and background screening from the $\sigma$-bonded electrons. We find that $\sigma$-band screening is extremely strong at distances of the order of a few nm, and should be highly effective at screening out short-distance, Hubbard-like interactions in graphene, as well as other carbon allotropes.Comment: 23 pages, 5 figure

Polinizadores y polinización en frutales subtropicales : implicaciones en manejo, conservación y seguridad alimentaria

The commercialization and consumption of tropical fruits has grown worldwide during the last decade. This trend is expected to continue, due to the increasing world population and the greater demand for these products in western markets. As in most fruit crops, one of the main bottlenecks in production is pollination, which determines fruit-tree and pollinator management to a large extent. Pollination management is therefore a defining factor in the composition and diversity of agro-systems. Because of this, the intensive production of fruit crops in many areas of the world requires adequate management of crops to enable: (1) an optimal production of fruit crops; (2) the conservation of insect communities. This is particularly important in developing countries, where the centers of genetic diversity of these crops are generally found and pollinator diversity is often poorly known and seriously threatened by agricultural intensification. However, some of these crops have been introduced into geographic areas away from the native areas of origin, which is an agronomic challenge but, at the same time, provides an opportunity to study and test under controlled conditions new management strategies. In this work we present a brief review on pollinators and pollination in subtropical fruit crops focusing on three species of international economic relevance such as mango, avocado and cherimoya. With the knowledge acquired on these species in a Mediterranean context, we propose a road-map to develop appropriate management strategies in other fruit crops and geographical areas

Survival of women previously diagnosed of melanoma with subsequent pregnancy: a systematic review and meta-analysis and a single-center experience

Review[Abstract] Melanoma incidence has increased over the last few decades. How the prognosis of a previously diagnosed melanoma may be affected by a woman's subsequent pregnancy has been debated in the literature since the 1950s, and the outcomes are essential to women who are melanoma survivors in their childbearing years. The main objective of this systematic review is to improve the understanding of whether the course of melanoma in a woman may be altered by a subsequent pregnancy and to help clinicians' diagnosis. Eligible studies for the systematic review were clinical trials, observational cohort studies and case-control studies that compared prognosis outcomes for non-pregnant patients with melanoma, or pregnant before melanoma diagnosis, versus pregnant patients after a diagnosis of melanoma. The search strategy yielded 1101 articles, of which 4 met the inclusion criteria for the systematic review. All the studies were retrospective non-randomised cohorts with patients with melanomas diagnosed before pregnancy. According to our findings, a subsequent pregnancy was not a significant influence on the outcome of a previous melanoma. However, given the small number of identified studies and the heterogeneous data included, it is recommended to approach these patients with caution, and counselling should be given by known prognostic factors. We also reviewed the medical records of 84 patients of childbearing age (35.8 ± 6.3 years, range 21-45 years) who were diagnosed with cutaneous invasive melanoma in our hospital between 2008 and 2018 (N = 724). Of these, 11 (13.1%) had a pregnancy after melanoma diagnosis (age at pregnancy: 35.6 ± 6.3 years). No statistical differences in outcome were detected

Asymmetric Dimethylarginine at Sea Level Is a Predictive Marker of Hypoxic Pulmonary Arterial Hypertension at High Altitude

Background: Prolonged exposure to altitude-associated chronic hypoxia (CH) may cause high-altitude pulmonary hypertension (HAPH). Chronic intermittent hypobaric hypoxia (CIH) occurs in individuals who commute between sea level and high altitude. CIH is associated with repetitive acute hypoxic acclimatization and conveys the long-term risk of HAPH. As nitric oxide (NO) regulates pulmonary vascular tone and asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of NO synthesis, we investigated whether ADMA concentration at sea level predicts HAPH among Chilean frontiers personnel exposed to 6 months of CIH.Methods: In this prospective study, 123 healthy army draftees were subjected to CIH (5 days at 3,550 m, 2 days at sea level) for 6 months. In 100 study participants with complete data, ADMA, symmetric dimethylarginine (SDMA), L-arginine, arterial oxygen saturation (SaO2), systemic blood pressure, and hematocrit were assessed at months 0 (sea level), 1, 4, and 6. Acclimatization to altitude was determined using the Lake Louise Score (LLS) and the presence of acute mountain sickness (AMS). Echocardiography was performed after 6 months of CIH in 43 individuals with either good (n = 23) or poor (n = 20) acclimatization.Results: SaO2 acutely decreased at altitude and plateaued at 90% thereafter. ADMA increased and SDMA decreased during the study course. The incidence of AMS and the LLS was high after the first ascent (53 and 3.1 ± 2.4) and at 1 month of CIH (47 and 3.0 ± 2.6), but decreased to 20 and 1.4 ± 2.0 at month 6 (both p < 0.001). Eighteen participants (42%) showed a mean pulmonary arterial pressure (mPAP) >25 mm Hg, out of which 9 (21%) were classified as HAPH (mPAP ≥ 30 mm Hg). ADMA at sea level was significantly associated with mPAP at high altitude in month 6 (R = 0.413; p = 0.007). In ROC analysis, a cutoff for baseline ADMA of 0.665 μmol/L was determined to predict HAPH (mPAP > 30 mm Hg) with a sensitivity of 100% and a specificity of 63.6%.Conclusions: ADMA concentration increases during CIH. ADMA at sea level is an independent predictive biomarker of HAPH. SDMA concentration decreases during CIH and shows no association with HAPH. Our data support a role of impaired NO-mediated pulmonary vasodilation in the pathogenesis of HAPH

Deglacial-Holocene Pulses of Old Carbon-Enriched Mediterranean Water Masses: Implications for Aragonite Mounds Growth and Global Carbon Cycle

Major changes in the Mediterranean Thermohaline Circulation (MedTHC) related to deglaciation and monsoon dynamics have been documented, while in turn, Mediterranean waters have been proposed to play a role back in global climate variability, ocean circulation and carbon cycle budgets, for instance via changes in water mass residence times. The 14C offset between coeval planktonic and benthic foraminifera over time is a very useful tool to infer variations in the water column ventilation (with no biological interference) that becomes more accurate when combined with local paired 14C-U/Th analyses in cold-water corals (CWC). Here, we present a multi-proxy-archive study (i.e., estimates of reservoir ages, εNd, [CO3 2-], O2 and current speed) carried out on the on-mound sediment core MD13-3452 (305 m, West Melilla, Alboran Sea, Western Mediterranean), which investigates potential deglacial changes and triggers in deep reservoir ages, as well as possible impacts on CWC aragonite mound growth and on global carbon cycle.Our combined foraminifera-CWC radioactive isotopes results show: 1) the arrival of two pulses of aged waters at intermediate depth corresponding to the Younger Dryas (YD) and to the end of the last sapropel (S1), when low CWC mound growth rates dominated, and 2) a very well-ventilated water mass between those two events, parallel to a CWC mound flourishing stage. In combination with the other proxies, poorer ventilated water pulses seem to have had a different origin, but common higher content in respired carbon. Our results allow, for the first time, changes in ventilation rates to be shown, quantified, and timed in association with a periodical MedTHC weakening, as well as suggesting significant aragonite dissolution as a cause of decreased mound growth rate when higher CO2 episodes. Our findings may have implications for past hydrographic interconnexions between Mediterranean basins and for global marine carbon storage and alkalinity budget in particular