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It is taken for granted that immature mosquito only breathe atmospheric air through their siphons. However, there is no quantitative study that demonstrated it. We analysed the survival of the last instar larvae ofAedes aegyptifully submerged at different temperatures, and measured oxygen consumption from air and dissolved in water, of larvae and pupae of this species under different conditions. Results revealed that under water, larvae survived much longer than expected, reaching 50% mortality only after 58, 10, and 5 days at 15°, 25° and 35°C, respectively. Interestingly, whereas we registered moults to pupae in larvae with access to air, individuals kept submerged never moulted. When remaining at the water surface, larvae obtained 12.72% of O2from the water, while pupae only 5.32%. When completely submerged, larvae consumed less oxygen than in contact with the surface, but enough for surviving, while pupae did not. At both media, temperature affected larvae respiration rate, with relatively close Q10values. In the related species,Ae. albopictus, a similar pattern of O2consumption were observed. Larvae got 12.14% of their oxygen from the water. Interestingly, no significant differences in total O2consumption were found between water O2consumption, whenAe. albopictuslarvae were submerged, or when they also have access to air (dual O2consumption). Our findings not only challenge the classical idea that mosquito larvae only breathe atmospheric O2, but also force us to reconsider the potential effectiveness of control methods based on asphyxiating larvae by detaching from water surface.Summary statementWe present the first quantitative analysis of mosquito larvae respiration in air and water, unravelling the unknown capacity of larvae of the most cosmopolitan disease vector of breathing underwater.

BackgroundMembrane potential (Vmem) exerts physiological influence across a wide range of time and space scales. To study Vmem in these diverse contexts, it is essential to accurately record absolute values of Vmem, rather than solely relative measurements.Materials & MethodsWe use fluorescence lifetime imaging of a small molecule voltage sensitive dye (VF2.1.Cl) to estimate mV values of absolute membrane potential.ResultsWe test the consistency of VF2.1.Cl lifetime measurements performed on different single photon counting instruments and find that they are in striking agreement (differences of mem under two-photon (2P) illumination with better than 20 mV of Vmem resolution, a nearly 10-fold improvement over other lifetime-based methods.ConclusionsWe demonstrate that VF-FLIM is a robust and portable metric for Vmem across imaging platforms and under both one-photon and two-photon illumination. This work is a critical foundation for application of VF-FLIM to record absolute membrane potential signals in thick tissue.

Protein aggregation increases during aging and is a pathological hallmark of many age-related diseases. Protein homeostasis (proteostasis) depends on a core network of factors directly influencing protein production, folding, trafficking, and degradation. Cellular proteostasis also depends on the overall composition of the proteome and numerous environmental variables. Modulating this cellular proteostasis state can influence the stability of multiple endogenous proteins, yet the factors contributing to this state remain incompletely characterized. Here, we perform genome-wide CRISPRi screens to elucidate the modulators of proteostasis state in mammalian cells using a fluorescent dye to monitor endogenous protein aggregation. These screens recovered components of the known proteostasis network, and uncovered a link between protein and lipid homeostasis. We subsequently showed that increased lipid uptake and/or disrupted lipid metabolism led to increased lysosomal protein aggregation and, concomitantly, accumulation of sphingolipids and cholesterol esters. Surprisingly, lysosomal proteostasis impairment by lipid dysregulation is independent of lipid peroxidation or changes in lysosomal stability, nor is it caused by effects on many other aspects of lysosomal or proteasomal function. These results suggest that lipid dysregulation may have primary effects on the stability of endogenous proteins, potentially through direct biophysical mechanisms.

Membrane potential (Vmem) is a fundamental biophysical signal present in all cells. Vmem signals range in time from milliseconds to days, and they span lengths from microns to centimeters. Vmem affects many cellular processes, ranging from neurotransmitter release to cell cycle control to tissue patterning. However, existing tools are not suitable for Vmem quantification in many of these areas. In this review, we outline the diverse biology of Vmem, drafting a wish list of features for a Vmem sensing platform. We then use these guidelines to discuss electrode-based and optical platforms for interrogating Vmem. On the one hand, electrode-based strategies exhibit excellent quantification but are most effective in short-term, cellular recordings. On the other hand, optical strategies provide easier access to diverse samples but generally only detect relative changes in Vmem. By combining the respective strengths of these technologies, recent advances in optical quantification of absolute Vmem enable new inquiries into Vmem biology.

Voltage imaging with fluorescent indicators offers a powerful complement to traditional electrode or Ca2+-imaging approaches for monitoring electrical activity. Small molecule fluorescent indicators present the unique opportunity for exquisite control over molecular structure, enabling detailed investigations of structure/function relationships. In this paper, we tune the conjugation between aniline donors and aromatic π systems within the context of photoinduced electron transfer (PeT) based voltage indicators. We describe the design and synthesis of four new voltage-sensitive fluorophores (VoltageFluors, or VFs). Three of these dyes have higher relative voltage sensitivities (ΔF/F) than the previously-reported indicator, VF2.1.Cl. We pair these new indicators with existing VFs to construct a library of voltage indicators with varying degrees of conjugation between the aniline nitrogen lone pair and the aromatic π system. Using a combination of steady-state and time-resolved fluorescence spectroscopy, cellular electrophysiology, fluorescence lifetime imaging microscopy (FLIM), and functional imaging in mammalian neurons and human cardiomyocytes, we establish a detailed link between the photophysical properties of VF dyes and their ability to report on membrane potential dynamics with high signal-to-noise. Anilines with intermediate degrees of conjugation to the aromatic π system experience intermediate rates of PeT and possess the highest absolute voltage sensitivities. Measured using FLIM in patch-clamped HEK cells, we find that the absolute voltage sensitivity of fluorescence lifetime (Δτfl per mV), coupled with traditional fluorescence intensity-based metrics like ΔF/F and signal-to-noise ratio (SNR), provides a powerful method to both predict and understand indicator performance in cellular systems., Voltage imaging with fluorescent indicators offers a powerful complement to traditional electrode or Ca2+-imaging approaches for monitoring electrical activity.

Simple Summary Sucking lice are permanent and obligate ectoparasites throughout their whole life cycle. Echinophthiriids escorted their mammal hosts during their passage from fully terrestrial to amphibian life. Seal lice synchronize their reproduction cycle with that of their mammalian hosts. Echinophthiriids tolerate long immersion periods and extreme hydrostatic pressures. Diving lice can reach kilometers under the surface and survive, during the months their hosts remain in the open ocean. In the present work, we describe and discuss how some of these adaptations allow seal lice to cope with the amphibious habits of their hosts and how they can help us to understand why insects are so rare in the ocean. Abstract Insects are the most evolutionarily and ecologically successful group of living animals, being present in almost all possible mainland habitats; however, they are virtually absent in the ocean, which constitutes more than 99% of the Earth’s biosphere. Only a few insect species can be found in the sea but they remain at the surface, in salt marshes, estuaries, or shallow waters. Remarkably, a group of 13 species manages to endure long immersion periods in the open sea, as well as deep dives, i.e., seal lice. Sucking lice (Phthiraptera: Anoplura) are ectoparasites of mammals, living while attached to the hosts’ skin, into their fur, or among their hairs. Among them, the family Echinophthiriidae is peculiar because it infests amphibious hosts, such as pinnipeds and otters, who make deep dives and spend from weeks to months in the open sea. During the evolutionary transition of pinnipeds from land to the ocean, echinophthiriid lice had to manage the gradual change to an amphibian lifestyle along with their hosts, some of which may spend more than 80% of the time submerged and performing extreme dives, some beyond 2000 m under the surface. These obligate and permanent ectoparasites have adapted to cope with hypoxia, high salinity, low temperature, and, in particular, conditions of huge hydrostatic pressures. We will discuss some of these adaptations allowing seal lice to cope with their hosts’ amphibious habits and how they can help us understand why insects are so rare in the ocean.

Lutzomyia longipalpis is known as one of the primary insect vectors of visceral leishmaniasis. For such ectothermic organisms, the ambient temperature is a critical life factor. However, the impact of temperature has been ignored in many induced-stress situations of the vector life. Therefore, this study explored the interaction of Lu. longipalpis with temperature by evaluating its behaviour across a thermal gradient, thermographic recordings during blood-feeding on mice, and the gene expression of heat shock proteins (HSP) when insects were exposed to extreme temperature or infected. The results showed that 72 h after blood ingestion, Lu. longipalpis became less active and preferred relatively low temperatures. However, at later stages of blood digestion, females increased their activity and remained at higher temperatures. Real-time imaging showed that the body temperature of females can adjust rapidly to the host and remain constant until the end of blood-feeding. Insects also increased the expression of HSP90(83) during blood-feeding. Our findings suggest that Lu. longipalpis interacts with temperature by using its behaviour to avoid temperature-induced physiological damage during the gonotrophic cycle. However, the expression of certain HSP might be triggered to mitigate thermal stress in situations where a behavioural response is not the best option.

Pollinating insects can be exposed to temperatures far from ambient air when visiting flowers, reducing their warming tolerance. Typically, such scenario occurs when flowers are exposed to solar radiation. The case of thermogenic flowers is particular because they warm up even when they are not exposed to solar energy. The flowers of Arum attract their pollinators with a deceptive method and trap them for a whole day, thereby imposing elevated temperature to visiting insects. Therefore, we predict a relatively high basal thermal tolerance in those insects. The aim of this study was to assess the thermal tolerance and warming tolerance of females of two fly species (genus Psychoda) pollinating Arum sp. (thermogenic plant). We measured their critical temperature (CTmax) and its response to rate of temperature increase as well as acclimation period to moderate temperature of 25 °C. We found relatively low CTmax (33.7 °C on average) for both species, and a weak response to acclimation period and ramping rate. In general, the thermal tolerance increased with a rapid ramping in temperature. To evaluate the warming tolerance, we compared thermal tolerance limits to flower temperatures measured in the field. We highlighted that the temperature of the thermogenic floral organ could reach values close to the thermal tolerance threshold of pollinators. This discovery raises questions about the sustainability of the interaction between these thermogenic plants and their pollinators.

Purpose: The aim of this research is to understand how the social-economic context influences the transformative potential of the sharing economy (SE). Originality/value: The literature on SE is still fraught with uncertainty. We have found that there is a paradox between generating social benefits to the community versus increasing social inequality. Design/methodology/approach: Data were collected from documentary analysis, netnography, participant observation, and interviews. The data collected were analyzed in the light of the theoretical framework proposed by Wittmayer et al. (2019) for the analysis of narratives related to social innovation. Findings: The produced narratives differ in terms of the type of platform (profit and non-profit). We have found that, in non-profit platforms, the economic and social context does not influence the transformative potential guided by the SE; for-profit platforms, on the other hand, the narrative of ‘income opportunity’ is context-sensitive. The main contributions of the research are the use of a theoretical framework of social innovation to analyze the narratives of the SE and the observation of contextual differences about the phenomenon, which should lead platforms and governments (in their regulatory role) to have different views on SE. We conclude that the narratives of the SE are different. For-profit platforms either do not take part or contribute very little to the phe nomenon of social innovation as a transformative process and, in the contexts of greater social-economic vulnerability, it can be a mechanism of worsening social inequality. / Objetivo: O objetivo desta pesquisa foi compreender como os contextos econômicos e sociais influenciam no potencial transformador da economia compartilhada (EC). Originalidade/valor: A literatura referente ao tema da EC ainda é repleta de incertezas. Entre elas, verificamos que há um paradoxo entre a geração de benefícios sociais à comunidade e o aumento da desigualdade social. Design/metodologia/abordagem: Os dados foram coletados por meio de análise documental, netnografia, observação participante e entrevistas. A partir da coleta, analisaram-se os dados à luz do framework teórico proposto por Wittmayer et al. (2019) para o exame de narrativas ligadas à inovação social. Resultados: As narrativas produzidas diferem quanto ao tipo de plataforma (com e sem fins lucrativos). Verificamos que, nas plataformas sem fins lucrativos, os contextos econômicos e sociais não influenciam no potencial transformador orientado pela EC, diferentemente das plataformas com fins lucrativos, nas quais a narrativa “oportunidade de renda” é sensível ao contexto. As principais contribuições da pesquisa realizada consistem na utilização de um framework teórico da inovação social para analisar as narrativas da EC e na observação de diferenças contextuais sobre o fenômeno, o que deveria levar as plataformas e os governos (no seu papel regulador) a ter diferentes olhares sobre a EC. Concluímos que as narrativas da EC se apresentam diferentemente. As plataformas com poucos (ou sem) fins lucrativos se inserem no fenômeno da inovação social como um processo transformador e, nos contextos de maior vulnerabilidade econômico social, podem ser um mecanismo de agravamento da desigualdade social.

Blood-sucking arthropods exploit multimodal information for locating and recognising potential hosts. The heat emitted by the body of endothermic vertebrates constitutes a major cue for orientation. To exploit it in a reliable way, insects must be able to deal with two variants of thermal information, that is heat exchange and temperature fluctuations. Evaluating whether or not an object qualifies as a host by its temperature requires solving thermodynamic ambiguities in a context where temperature increase at the receptor level is just one, yet insufficient, piece of information. To be exploitable, this piece of information needs to be integrated with other variables. Here, I discuss the physical constraints associated to thermal orientation, as well as the way different blood-sucking insects acquire and make use of heat to recognise a host.

As the world comes to terms with the realities surrounding COVID-19, media sources have likened quarantine experiences to that of incarceration. Individuals who have experienced incarceration and individuals who have experienced the incarceration of loved ones (LO), have already experienced periods of time apart. We are exploring the experiences of individuals who have some experience with incarceration; whether they were personally incarcerated, or they experienced the incarceration of a LO. Utilizing snowball sampling, a mixed methods survey was circulated on social media. Survey items included demographic information, questions about incarceration, issues related to COVID-19 quarantines, and the UCLA Loneliness Scale. Results follow similar patterns to previous studies. However, this unique population argues that COVID-19 quarantines are not the same as periods of incarceration. Similarly, future research and community agencies need to examine the unique needs of those who have experienced the incarceration of a loved one.

The development of fluorescent dyes that emit and absorb light at wavelengths greater than 700 nm and that respond to biochemical and biophysical events in living systems remains an outstanding challenge for noninvasive optical imaging. Here, we report the design, synthesis, and application of near-infrared (NIR)-absorbing and -emitting optical voltmeter based on a sulfonated, phosphine-oxide (po) rhodamine for voltage imaging in intact retinas. We find that po-rhodamine based voltage reporters, or poRhoVRs, display NIR excitation and emission profiles at greater than 700 nm, show a range of voltage sensitivities (13 to 43% ΔF/F per 100 mV in HEK cells), and can be combined with existing optical sensors, like Ca2+-sensitive fluorescent proteins (GCaMP), and actuators, like light-activated opsins ChannelRhodopsin-2 (ChR2). Simultaneous voltage and Ca2+ imaging reveals differences in activity dynamics in rat hippocampal neurons, and pairing poRhoVR with blue-light based ChR2 affords all-optical electrophysiology. In ex vivo retinas isolated from a mouse model of retinal degeneration, poRhoVR, together with GCaMP-based Ca2+ imaging and traditional multielectrode array (MEA) recording, can provide a comprehensive physiological activity profile of neuronal activity, revealing differences in voltage and Ca2+ dynamics within hyperactive networks of the mouse retina. Taken together, these experiments establish that poRhoVR will open new horizons in optical interrogation of cellular and neuronal physiology in intact systems.

Membrane potential is a fundamental biophysical parameter common to all of cellular life. Traditional methods to measure membrane potential rely on electrodes, which are invasive and low-throughput. Optical methods to measure membrane potential are attractive because they have the potential to be less invasive and higher throughput than classic electrode based techniques. However, most optical measurements rely on changes in fluorescence intensity to detect changes in membrane potential. In this chapter, we discuss the use of fluorescence lifetime imaging microscopy (FLIM) and voltage-sensitive fluorophores (VoltageFluors, or VF dyes) to estimate the millivolt value of membrane potentials in living cells. We discuss theory, application, protocols, and shortcomings of this approach.

Purpose: The aim of this research is to understand how the social-economic context influences the transformative potential of the sharing economy (SE). Originality/value: The literature on SE is still fraught with uncertainty. We have found that there is a paradox between generating social benefits to the community versus increasing social inequality. Design/methodology/approach: Data were collected from documentary analysis, netnography, participant observation, and interviews. The data collected were analyzed in the light of the theoretical framework proposed by Wittmayer et al. (2019) for the analysis of narratives related to social innovation. Findings: The produced narratives differ in terms of the type of platform (profit and non-profit). We have found that, in non-profit platforms, the economic and social context does not influence the transformative potential guided by the SE; for-profit platforms, on the other hand, the narrative of ‘income opportunity’ is context-sensitive. The main contributions of the research are the use of a theoretical framework of social innovation to analyze the narratives of the SE and the observation of contextual differences about the phenomenon, which should lead platforms and governments (in their regulatory role) to have different views on SE. We conclude that the narratives of the SE are different. For-profit platforms either do not take part or contribute very little to the phe nomenon of social innovation as a transformative process and, in the contexts of greater social-economic vulnerability, it can be a mechanism of worsening social inequality. RESUMO Objetivo: O objetivo desta pesquisa foi compreender como os contextos econômicos e sociais influenciam no potencial transformador da economia compartilhada (EC). Originalidade/valor: A literatura referente ao tema da EC ainda é repleta de incertezas. Entre elas, verificamos que há um paradoxo entre a geração de benefícios sociais à comunidade e o aumento da desigualdade social. Design/metodologia/abordagem: Os dados foram coletados por meio de análise documental, netnografia, observação participante e entrevistas. A partir da coleta, analisaram-se os dados à luz do framework teórico proposto por Wittmayer et al. (2019) para o exame de narrativas ligadas à inovação social. Resultados: As narrativas produzidas diferem quanto ao tipo de plataforma (com e sem fins lucrativos). Verificamos que, nas plataformas sem fins lucrativos, os contextos econômicos e sociais não influenciam no potencial transformador orientado pela EC, diferentemente das plataformas com fins lucrativos, nas quais a narrativa “oportunidade de renda” é sensível ao contexto. As principais contribuições da pesquisa realizada consistem na utilização de um framework teórico da inovação social para analisar as narrativas da EC e na observação de diferenças contextuais sobre o fenômeno, o que deveria levar as plataformas e os governos (no seu papel regulador) a ter diferentes olhares sobre a EC. Concluímos que as narrativas da EC se apresentam diferentemente. As plataformas com poucos (ou sem) fins lucrativos se inserem no fenômeno da inovação social como um processo transformador e, nos contextos de maior vulnerabilidade econômico social, podem ser um mecanismo de agravamento da desigualdade social.

The nervous system of triatomines follows the general plan for insects in terms of organization. Yet, its anatomy is in line with the form of the different regions of the bug’s body. The brain is located in the posterior region of the elongated head, the cavity of which is mostly occupied by the cibarial pump. The ganglia composing the ventral nerve cord exhibit a high degree of fusion, conforming a mass of suboesophageal or gnathal ganglia, a prothoracic ganglion and a unique posterior nervous mass, formed by the fusion of meso- and meta-thoracic and segmental abdominal ganglia. Most of the integration centres (i.e. neuropils) of the brain and ganglia are less structured than in other insects, but they can be easily recognized by histological inspection. In the brain, all major centres are well defined, and in the ganglia it is possible to establish the correspondence of each neuropil with its respective thoracic or abdominal segment. We have tried to keep the nomenclature employed for naming different structures as clear as possible. In some cases, synonymy is indicated, in order to allow the reader to find equivalents in the literature concerning other insects, which could have adopted different criteria. This chapter presents a synthesis of our present knowledge of the neuroanatomy of kissing bugs, underlining its particularities. A general description is presented here, but much work is still needed to elaborate an atlas as detailed as those existing for domestic and fruit flies or honey bees.

Many arthropod species have adopted the blood of vertebrates as their main food. Blood is rich in nutrients and, except for the presence of parasites, otherwise sterile. This food, however, is not freely available nor is its obtention devoid of risk; it circulates inside vessels hidden underneath the skin of mobile hosts, which are able to defend themselves and even predate the insects attempting to feed on them. Thus, the haematophagous lifestyle is associated with major morphological, physiological and behavioural adaptations that have accumulated throughout the evolutionary history of the various lineages of blood-sucking arthropods, including triatomines. These adaptations have, on the other hand, significant consequences for the evolution of parasites, as well as for the epidemiology of vector-transmitted diseases. This review article analyses various aspects of the behaviour of triatomine bugs to illustrate how behavioural traits represent particular adaptations to their close association with hosts, which may easily turn into predators. The aim is to offer to the reader an up-to-date integrative view of the behaviour of Chagas disease vectors from a personal perspective, with the hope of encouraging young and experienced colleagues to explore this fascinating aspect of triatomine biology.

The phlebotomine sand flyLutzomyia longipalpisis the primary insect vector of visceral leishmaniasis in the Americas. For ectothermic organisms such as sand flies, the ambient temperature is a critical factor influencing all aspects of their life. However, the impact of temperature has been ignored in previous investigations of stress-induced responses by the vector, such as taking a blood meal or duringLeishmaniainfection. Therefore, this study explored the interaction ofLu. longipalpiswith temperature by evaluating sand fly behaviour across a thermal gradient after sugar or blood-feeding, and infection withLeishmania mexicana.Thermographic recordings of sand fly females fed on mice were analysed, and the gene expression of heat shock proteins HSP70 and HSP90(83) was evaluated when insects were exposed to extreme temperatures or infected. The results showed that 72h after blood ingestion females ofLu. longipalpisbecame less active and preferred relatively low temperatures. However, at later stages of blood digestion females increased their activity and remained at higher temperatures prior to taking a second blood meal; this behaviour seems to be correlated with the evolution of their oocysts and voracity for a second blood meal. No changes in the temperature preferences of female sand flies were recorded in the presence of a gut infection byLe. mexicana,indicating that this parasite has not triggered behavioural immunity inLu. longipalpis. Real-time imaging showed that the body temperature of female flies feeding on mice increased to the same temperature as the host within a few seconds after landing. The body temperature of females remained around 35 ± 0.5 °C until the end of blood-feeding, revealing a lack of thermoregulatory behaviour. Analysis of expression of heat shock proteins revealed insects increased expression of HSP90(83) when exposed to higher temperatures, such as during blood feeding. Our findings suggest thatLu. longipalpisinteracts with the environmental temperature by using its behaviour to avoid temperature-related physiological damage during the gonotrophic cycle. However, the expression of certain heat shock proteins might be triggered to mitigate against thermal stress in situations where a behavioural response is not the best option.

Feeding on the blood of warm-blooded vertebrates is associated to thermal stress in haematophagous arthropods. It has been demonstrated that blood-sucking insects protect their physiological integrity either by synthesising heat-shock proteins or by means of thermoregulatory mechanisms. In this work, we describe the first thermoregulatory mechanism in a tick species,Ornithodoros rostratus. By performing real-time infrared thermography during feeding on mice we found that this acarian eliminates big amounts of fluid (urine) through their coxal glands; this fluid quickly spreads over the cuticular surface and its evaporation cools-down the body of the tick. The spread of the fluid is possible thanks to capillary diffusion through the sculptured exoskeleton ofOrnithodoros. We discuss our findings in the frame of the adaptive strategies to cope with the thermal stress experienced by blood-sucking arthropods at each feeding event warm-blooded hosts.

Active searching for vertebrate blood is a necessary activity for haematophagous insects, and it can be assumed that this search should also be costly in terms of energetic expenditure. Whether by swimming, walking, running or flying, active movement requires energy, increasing metabolic rate relative to resting situations. We analysed the respiratory pattern and energetic cost of pedestrian locomotion in the blood-sucking bug

Voltage imaging with fluorescent indicators offers a powerful complement to traditional electrode or Ca2+-imaging approaches to monitoring electrical activity. Small molecule fluorescent indicators present the unique opportunity for exquisite control over molecular structure, enabling detailed investigations of structure/function relationships. In this paper, we examine the use of conformationally-restricted aniline donors within the context of photoinduced electron transfer (PeT) based voltage indicators. We describe the design and synthesis of four new voltage-sensitive fluorophores (VoltageFluors, or VF dyes). We pair these new indicators with existing VF dyes to construct a library of voltage indicators with varying conformations about the dihedral angle between the nitrogen lone pair and the aromatic ring. Using a combination of steady-state and time-resolved fluorescence spectroscopy, cellular electrophysiology, fluorescence lifetime imaging microscopy (FLIM), and functional imaging in mammalian neurons and human cardiomyocytes, we show that differences in voltage sensitivity within aniline-modified VF dyes span an order of magnitude. Annulated anilines show high levels of PeT and low voltage sensitivity, while sterically-congested anilines whose lone pairs do not couple to the aromatic π system are exceptionally bright and display little voltage sensitivity. Conformationally flexible anilines possess the highest absolute voltage sensitivity. Measured using FLIM in patch-clamped HEK cells, we find that voltage sensitivity of the fluorescence lifetime provides the best predictor of performance in cellular systems. By comparing in-depth photophysical characterization with performance in action potential detection, we establish a detailed link between probe conformation and the ability to report on membrane potential dynamics with high fidelity.

Active searching for vertebrate blood is a necessary activity for haematophagous insects, and it can be assumed that this search should also be costly in terms of energetic expenditure. Either if it is by swimming, walking, running or flying, active movement requires energy, increasing metabolic rates relative to resting situations. We analysed the respiratory pattern and the energetic cost of pedestrian locomotion in the blood-sucking bug Rhodnius prolixus using flow-through respirometry, by measuring carbon dioxide emission and water loss before, during and after walking. We observed an increase of up to 1.7-fold in the metabolic rate during walking as compared to resting in male R. prolixus and 1.5-fold in females, as well as a change in their respiratory pattern. The last switched from cyclic during resting to continuous, when the insects started to walk, remaining this condition unchanged during locomotion and for several minutes after stopping. Walking induced a significant loss of weight in both, males and females. This can be explained by the increase in both, the metabolic rate and the water loss during walking. These data constitute the first metabolic measures of active hematophagous insects and provide the first insights on the energetic expenditure associated to the active search for blood in this group.

Lice from pinnipeds, i.e. sea lions, seals, and walruses, are the only insects capable of surviving marine dives. Along their evolutionary history, they adapted to tolerate hypoxia, high salinity, low temperature and, in particular, to tolerate conditions of high hydrostatic pressure. To understand the limits of the capacity of lice to survive during host deep dives, we conducted a series of controlled experiments in the laboratory. We collected lice from elephant seals and submitted the different life stages to high pressure conditions. Lice were first exposed to one of four hydrostatic pressures: (a) 30 Kg/cm2; (b) 80 Kg/cm2; (c) 150 Kg/cm2, or (d) 200 Kg/cm2. They were then exposed a second time to higher or lower hydrostatic pressure conditions to test for the impact of the first experience, which could either be deleterious or trigger physiological adaption, allowing them a better tolerance to high pressure. We found that lice from elephant seals can tolerate hydrostatic pressures higher than 200 Kg/cm2 (close to 200 atm), equivalent to 2000 m depth. Adults exhibited lower recovery times than nymphs after immersion at high hydrostatic pressure. Our findings show that lice developed unique adaptations to endure extreme marine conditions. We discuss these extreme performances as related to the morphological characteristics and physiological responses to diving in these insects.

Correctional systems spend considerable resources providing visitations for incarcerated individuals. Researchers have explored whether visitations decrease recidivism, increase prosocial b...

The increase in body temperature over that of the environment has been frequently reported in insects, in particular in relation with flight activity. Scarab beetles of the genus Cyclocephala living in tropical areas are known to exploit the heat produced by thermogenic plants, also producing heat by endothermy. Here, we report the first case of endothermy in a species of this genus living in a temperate region, Cyclocephala signaticollis. We characterised the phenomenon in this beetle using infrared thermography and exposing them to different thermal conditions. We evaluated the frequency of endothermic bouts, the nature of their periodic occurrence and their association with the activity cycles of the beetles. We found that endothermy occurs in both males and females in a cyclic fashion, at the beginning of the night, around 21:00 local time. The mean temperature increase was of 9 °C, and the mean duration of the bouts was 7 min. During endothermic bouts, the temperature of the thorax was on average 3.6 °C higher than that of the head and 4.8 °C above that of the abdomen. We found no differences between females and males in the maximum temperature attained and in the duration of the endothermy bouts. The activity period of the beetles extends throughout the whole night, with maximum activity between 22:00 and 23:00. By subjecting the beetles to different light regimes we were able to determine that the rhythm of endothermy is not controlled by the circadian system. Finally, we experimentally tested if by performing endothermy the scarabs try to reach a particular body temperature or if they invest a given amount of energy in heating up, instead. Our results indicate that at lower ambient temperature beetles show higher increase in body temperature, and that endothermy bouts last longer than at relatively higher ambient temperatures. We discuss our findings in relation to the ecology and behaviour of this beetle pest. Fil: Zermoglio, Paula Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentina Fil: Castelo, Marcela Karina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentina Fil: Lazzari, Claudio Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universite de Tours; Francia

The heat emitted by the host body constitutes a short distance orientation cue for most blood-sucking insects, as is the case of the kissing-bug Rhodnius prolixus. We evaluated here how kissing bugs assess the distance to a warm target, in order to reach it by displaying the Proboscis Extension Reflex (PER). We confronted blind-folded insects to a thermal source either at 35° or at 40 °C under both, open- and closed-loop conditions. The results showed that nymphs were able to estimate the distance to a thermal source just using thermal information. Free walking insects displayed PER with a maximum frequency at 5 mm from the object, even without touching it. Yet, our experiments showed that the insects need to walk freely to estimate the distance to the source accurately, i.e. performing the PER at a distance allowing them to reach the target with the tip of the proboscis. The distance at which PER was triggered was independent of the temperature of the thermal source (35° or 40 °C). Moreover, our results also unravelled that mechanical stimuli can be integrated with thermal cues, being capable of affecting the triggering of PER in kissing bugs. This is the first study providing evidence that blood-sucking vector insects use mechanoreception for eliciting their bites. We discuss our findings in the light of present models explaining the ability of kissing bugs to estimate the distance and the temperature of a potential food sources.

Incarcerated parents have complex life histories that often remain unresolved during incarceration, can continue to create barriers to prosocial success on release, and present similar intergenerational challenges for their children. This study examines the life histories of incarcerated fathers and mothers from the Pacific Northwest and how their experiences vary based on race and ethnicity. Five areas examined were exposure to trauma, child welfare involvement, mental health and substance abuse problems, juvenile justice and adult criminal justice involvement, and intergenerational criminal justice involvement. The sample comprised 359 incarcerated parents, and their racial/ethnic composition was 59% White, 14% African American, 11% multiracial, 8% Native American, and 7% Latino. Few differences were found across racial and ethnic groups. Mothers appeared more similar to each other across groups than fathers. Results illustrated similarities yet some surprising differences with national trends o...

All cells maintain ionic gradients across their plasma membranes, producing transmembrane potentials (Vmem). Mounting evidence suggests a relationship between resting Vmem and the physiology of non-excitable cells with implications in diverse areas, including cancer, cellular differentiation, and body patterning. A lack of non-invasive methods to record absolute Vmem limits our understanding of this fundamental signal. To address this need, we developed a fluorescence lifetime-based approach (VF-FLIM) to visualize and optically quantify Vmem with single-cell resolution in mammalian cell culture. Using VF-FLIM, we report Vmem distributions over thousands of cells, a 100-fold improvement relative to electrophysiological approaches. In human carcinoma cells, we visualize the voltage response to growth factor stimulation, stably recording a 10–15 mV hyperpolarization over minutes. Using pharmacological inhibitors, we identify the source of the hyperpolarization as the Ca2+-activated K+ channel KCa3.1. The ability to optically quantify absolute Vmem with cellular resolution will allow a re-examination of its signaling roles., eLife digest All living cells are like tiny batteries. As long as a cell is alive, it actively maintains a difference in electrical charge between its interior and exterior. This charge difference, or voltage, is called the membrane potential, and it is vital for our bodies to work properly. For example, fast changes in membrane potential control our heartbeat and underpin the electrical signals that brain cells use to communicate. Slower changes in membrane potential – ranging from minutes to days – may also play important roles in other organs. To understand how and why membrane potential is important in these contexts, we need methods to measure it accurately in individual cells. One way is to puncture cells with microscopic electrodes: this yields accurate results but damages the cells and can only measure one cell at a time. Alternative methods treat cells with special fluorescent dyes and then image them with a microscope. The dyes emit light in response to voltage variations: when the cells’ membrane potential changes, the dyes glow brighter. The changes in light intensity give an estimate of the size of the change in membrane potential. This allows many cells to be analyzed without harming them, but it is less accurate. Fluorescence lifetime refers to how long fluorescent dyes take to finish emitting light, and this phenomenon has already helped researchers to record a variety of processes in the cell. Lazzari-Dean et al. therefore wanted to use fluorescence lifetime to develop a better way of recording membrane potential. This method, called VF-FLIM, relied on measuring how long certain dyes took to finish emitting light at specific voltages, rather than how bright they were. Experiments using mammalian cells grown in the laboratory showed that the membrane potentials measured with VF-FLIM were similar to those recorded with electrodes, which represent the highest standard of accuracy. The new method was at least eight times more accurate than other techniques using fluorescent dyes. VF-FLIM could also measure many thousands of cells within a few hours, a hundred times faster than electrode-based methods. Finally, tests on human cancer cells revealed that VF-FLIM could detect that these cells go through gradual changes in membrane potential in response to growth signals. VF-FLIM is a new, non-invasive tool that can measure changes in membrane potential more quickly and accurately. This will help to better understand the many roles membrane potential could play in healthy and diseased cells.