95 research outputs found
Effects of temperature and photoperiod on daily activity rhythms of Lutzomyia longipalpis (Diptera: Psychodidae)
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Previous issue date: 2014Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. LaboratĂłrio de Biologia Molecular de FlavivĂrus. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. LaboratĂłrio de Transmissores de Leishmanioses. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. LaboratĂłrio de Biologia Molecular de FlavivĂrus. Rio de Janeiro, RJ, Brasil / Instituto Nacional de CiĂȘncia e Tecnologia em Entomologia Molecular (INCT-EM)/CNPq. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. LaboratĂłrio de Biologia Molecular de FlavivĂrus. Rio de Janeiro, RJ, Brasil / Instituto Nacional de CiĂȘncia e Tecnologia em Entomologia Molecular (INCT-EM)/CNPq. Rio de Janeiro, RJ, Brasil.Background: Insect vectors have been established as models in Chronobiology for many decades, and recent
studies have demonstrated a close relationship between the circadian clock machinery, daily rhythms of activity
and vectorial capacity. Lutzomyia longipalpis, the primary vector of Leishmania (Leishmania) infantum in the New
World, is reported to have crepuscular/nocturnal activity in the wild. However, most of these studies applied hourly
CDC trap captures, which is a good indicative of L. longipalpis behaviour, but has limited accuracy due to the
inability to record the daily activity of a single insect during consecutive days. In addition, very little is known about
the activity pattern of L. longipalpis under seasonal variations of average temperature and day length in controlled
laboratory conditions.
Methods: We recorded the locomotor activity of L. longipalpis males under different artificial regimes of
temperature and photoperiod. First, in order to test the effects of temperature on the activity, sandflies were
submitted to regimes of light/dark cycles similar to the equinox photoperiod (LD 12:12) combined with different
constant temperatures (20°C, 25°C and 30°C). In addition, we recorded sandfly locomotor activity under a mild
constant temperature (25°C with different day length regimes: 8 hours, 12 hours and 16 hours).
Results: L. longipalpis exhibited more activity at night, initiating dusk-related activity (onset time) at higher rather
than lower temperatures. In parallel, changes of photoperiod affected anticipation as well as all the patterns of
activity (onset, peak and offset time). However, under LD 16:08, sandflies presented the earliest values of maximum
peak and offset times, contrary to other regimes.
Conclusions: Herein, we showed that light and temperature modulate L. longipalpis behaviour under controlled
laboratory conditions, suggesting that sandflies might use environmental information to sustain their crepuscular/
nocturnal activity, as well as other important aspects as mating and host-seeking at appropriate times in different
seasons. Our results depict previously unappreciated aspects of the L. longipalpis daily rhythms of activity that might
have important epidemiological implications
Acoustic signals in the sand fly Lutzomyia (Nyssomyia) intermedia (Diptera: Psychodidae)
<p>Abstract</p> <p>Background</p> <p>Acoustic signals are part of the courtship of many insects and they often act as species-specific signals that are important in the reproductive isolation of closely related species. Here we report the courtship songs of the sand fly <it>Lutzomyia (Nyssomyia) intermedia</it>, one of the main vectors of cutaneous leishmaniasis in Brazil.</p> <p>Findings</p> <p>Recordings were performed using insects from three localities from Eastern Brazil: Posse and JacarepaguĂĄ in Rio de Janeiro State and Corte de Pedra in Bahia State. The three areas have remnants of the Brazilian Atlantic forest, they are endemic for cutaneous leishmaniasis and <it>L. intermedia </it>is the predominant sand fly species. We observed that during courtship <it>L. intermedia </it>males from all populations produced pulse songs consisting of short trains. No significant differences in song parameters were observed between the males of the three localities.</p> <p>Conclusions</p> <p><it>L. intermedia </it>males produce acoustic signals as reported for some other sand flies such as the sibling species of the <it>Lutzomyia longipalpis </it>complex. The lack of differences between the males from the three localities is consistent with previous molecular studies of the <it>period </it>gene carried out in the same populations, reinforcing the idea that <it>L. intermedia </it>is not a species complex in the studied areas and that the three populations are likely to have similar vectorial capacities.</p
Molecular and Behavioral Differentiation among Brazilian Populations of Lutzomyia longipalpis (Diptera: Psychodidae: Phlebotominae)
Lutzomyia longipalpis is the main vector of visceral leishmaniasis in the Americas. There is strong evidence that L. longipalpis is a species complex, but there is still no consensus regarding the number of species occurring in Brazil. We combined molecular and behavioral analyses of a number of L. longipalpis populations in order to help clarify this question. This approach has allowed us to identify two main groups of populations in Brazil. One group probably represents a single species distributed mainly throughout the coastal regions of North and Northeast Brazil and whose males produce the same type of copulation song and pheromone. The second group is more heterogeneous, probably represented by a number of incipient species with different levels of genetic divergence among the siblings that produce different combinations of copulation songs and pheromones. The high level of complexity observed raises important questions concerning the epidemiological consequences of this incipient speciation process
Vitamin E for prevention of oxaliplatin-induced peripheral neuropathy: a pilot randomized clinical trial
Carbon recovery dynamics following disturbance by selective logging in Amazonian forests
Abstract When 2 Mha of Amazonian forests are disturbed by selective logging each year, more than 90 Tg of carbon (C) is emitted to the atmosphere. Emissions are then counterbalanced by forest regrowth. With an original modelling approach, calibrated on a network of 133 permanent forest plots (175 ha total) across Amazonia, we link regional differences in climate, soil and initial biomass with survivors' and recruits' C fluxes to provide Amazon-wide predictions of post-logging C recovery. We show that net aboveground C recovery over 10 years is higher in the Guiana Shield and in the west (21 AE3 Mg C ha Ă1 ) than in the south (12 AE3 Mg C ha Ă1 ) where environmental stress is high (low rainfall, high seasonality). We highlight the key role of survivors in the forest regrowth and elaborate a comprehensive map of post-disturbance C recovery potential in Amazonia
Studies on populations of Lutzomyia longipalpis (Lutz & Neiva, 1912) (Diptera: Psychodidae: Phlebotominae) in Brazil
Micronucleus test in peripheral blood of rats treated with hyperbaric oxygen after subtotal splenectomy preserving the lower pole
COVID-19 symptoms at hospital admission vary with age and sex: results from the ISARIC prospective multinational observational study
Background:
The ISARIC prospective multinational observational study is the largest cohort of hospitalized patients with COVID-19. We present relationships of age, sex, and nationality to presenting symptoms.
Methods:
International, prospective observational study of 60â109 hospitalized symptomatic patients with laboratory-confirmed COVID-19 recruited from 43 countries between 30 January and 3 August 2020. Logistic regression was performed to evaluate relationships of age and sex to published COVID-19 case definitions and the most commonly reported symptoms.
Results:
âTypicalâ symptoms of fever (69%), cough (68%) and shortness of breath (66%) were the most commonly reported. 92% of patients experienced at least one of these. Prevalence of typical symptoms was greatest in 30- to 60-year-olds (respectively 80, 79, 69%; at least one 95%). They were reported less frequently in children (â€â18 years: 69, 48, 23; 85%), older adults (â„â70 years: 61, 62, 65; 90%), and women (66, 66, 64; 90%; vs. men 71, 70, 67; 93%, each Pâ<â0.001). The most common atypical presentations under 60 years of age were nausea and vomiting and abdominal pain, and over 60 years was confusion. Regression models showed significant differences in symptoms with sex, age and country.
Interpretation:
This international collaboration has allowed us to report reliable symptom data from the largest cohort of patients admitted to hospital with COVID-19. Adults over 60 and children admitted to hospital with COVID-19 are less likely to present with typical symptoms. Nausea and vomiting are common atypical presentations under 30 years. Confusion is a frequent atypical presentation of COVID-19 in adults over 60 years. Women are less likely to experience typical symptoms than men
Infecção natural de Lutzomyia intermedia Lutz & Neiva, 1912, em ĂĄrea endĂȘmica de leishmaniose tegumentar no Estado do Rio de Janeiro
Num foco de leishmaniose tegumentar, em JacarepaguĂĄ, Rio de Janeiro, foi encontrado um exemplar de Lutzomyia intermedia naturalmente infectado com Leishmania braziliensis.In a focus of cutaneous leishmaniasis in JacarepaguĂĄ, Rio de janeiro, one specimen of Lutzomyia intermedia was found naturaly infected with Leishmania braziliensis
Biologia de Lutzomyia intermedia (Lutz & Neiva, 1912) e Lutzomyia longipalpis (Lutz & Neiva, 1912) (Diptera, Psychodidae) em condiçÔes experimentais: II. InfluĂȘncia de fatores ambientais no comportamento das formas imaturas e adultas Biology of Lutzomyia intermedia (Lutz & Neiva, 1912) and Lutzomyia longipalpis (Lutz & Neiva, 1912) (Diptera, Psychodidae) in experimental conditions: II. Influence of environmental factors in the behavior of immature stages and adults
Com o objetivo de ampliar os conheciemntos sobre a biologia de Lutzomyia intermedia e Lutzomya longipalpis, mantidos em colĂŽnias autĂŽnomas no laboratĂłrio, apresentamos dados referentes a alteraçÔes em seu comportamento determinadas por influĂȘncia de fatores ambientais. L. longipalpis foi mais fĂĄcil de criar, mais produtiva e mais resitente ĂĄs variaçÔes das condiçÔes ambientais; suga a qualquer hora do dia, enquanto que L. intermedia prefere fazĂȘ-lo ao crepĂșsculo e Ă noite, quando tambĂ©m ocorrem masi freqĂŒentemente as desovas e as ecdises dos adultos das duas espĂ©cies. As fases imaturas de ambas as espĂ©cies resistem Ă imersĂŁo na ĂĄgua por atĂ© 1 hora e a baixa temperatura de 5ÂșC por atĂ© 6 horas.<br>Proceeding on our studies on the biology of Lutzomyia intermedia and Lutzomyia longipalpis in closed colonies in the laboratory, we here present our observations on changes in their behavior caused by environmental conditions. L. longipaldis was easier to breed, more productive and more resistant to environmental changes; it feeds at any time of the day or night, while L. intermedia prefers to do it at sunset and at night, the preferencial time for oviposition and ecdysis of adults of both species. The immature stages of both species resisted to immersion in water for up to 1 hour and low temperature (5ÂșC) for 1 to 6 hours
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