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The temperature of the environment is one of the most important abiotic factors affecting the life of insects. As poikilotherms, their body temperature is not constant, and they rely on various strategies to minimize the risk of thermal stress. They have been thus able to colonize a large spectrum of habitats. Mosquitoes, such as Ae. aegypti and Ae. albopictus, vector many pathogens, including dengue, chikungunya, and Zika viruses. The spread of these diseases has become a major global health concern, and it is predicted that climate change will affect the mosquitoes’ distribution, which will allow these insects to bring new pathogens to naïve populations. We synthesize here the current knowledge on the impact of temperature on the mosquito flight activity and host-seeking behavior (1); ecology and dispersion (2); as well as its potential effect on the pathogens themselves and how climate can affect the transmission of some of these pathogens (3).

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. 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.

Seal lice, unique among insects, show remarkable adaptability to the extreme conditions of the deep sea. Evolving with their seal and sea lion hosts, they have managed to tolerate hypoxia, high salinity, low temperature, and elevated hydrostatic pressure. Given the diving capabilities of their mammalian hosts, which can reach depths of hundreds to thousands of meters, our study examines the morphological variation among closely related seal lice species infesting hosts with different maximum diving depths. In particular, our research reveals a significant morphological difference between lice associated with regular and deep-diving hosts, where lice from deep-diving hosts tend to be rounder. This could be an adaptation to withstand the high hydrostatic pressures found in the deep ocean. The rounded shape optimizes the louse’s ability to withstand external pressure by redistributing it over a larger ventral/dorsal plane. This in turn minimizes the internal energy required to support body deformations, thereby increasing the louse’s resilience in the deep sea environment.

Seal lice (Anoplura) parasitize amphibious hosts, such as pinnipeds, and are uniquely adapted to an oceanic environment. As obligate, permanent ectoparasites feed on the blood of their hosts and are completely dependent on them. While studies have begun to explore general diving adaptations, research into seal lice’s sensory biology remains limited. In contrast to the vast majority of insects, including human lice, seal lice are devoid of eyes and depend on antennal sensory reception. This study aims to describe the morphology and putative function of antennal sensilla in five seal lice species: Antarctophthirus microchir, A. carlinii, A. lobodontis, A. ogmorhini, and Lepidophthirus macrorhini, which parasitize the South American sea lion, Weddell seal, crabeater seal, leopard seal, and southern elephant seal, respectively. The antennal structures of each species were analyzed using scanning electron microscopy, and eight morphotypes were identified: spine, cuticular lobe, sensilla squamiformia, sensilla chaetica, sensilla basiconica I and II, tuft organs, and pore organs. The morphology of sensilla and their distribution on the antennal flagellum exhibited variability among genera and species. For instance, the southern elephant louse (Lepidophthirus macrorhini) is characterized by the presence of sensilla squamiformia, while Antarctophthirus spp. are distinguished by sensilla chaetica.

The discovery of bifunctional degradation activating compounds (BiDACs) has led to the development of a new class of drugs that promote the clearance of their protein targets. BiDAC-induced ubiquitination is generally believed to direct cytosolic and nuclear proteins to proteolytic destruction by proteasomes. However, pathways that govern the degradation of other classes of BiDAC targets, such as integral membrane and intraorganellar proteins, have not been investigated in depth. In this study we use morphological profiling and CRISPR/Cas9 genetic screens to investigate the mechanisms by which BiDACs induce the degradation of plasma membrane receptor tyrosine kinases (RTKs) EGFR and Her2. We find that BiDAC-dependent ubiquitination triggers the trafficking of RTKs from the plasma membrane to lysosomes for degradation. Notably, functional proteasomes are required for endocytosis of RTKs upstream of the lysosome. Additionally, our screen uncovers a non-canonical function of the lysosome-associated arginine/lysine transporter PQLC2 in EGFR degradation. Our data show that BiDACs can target proteins to proteolytic machinery other than the proteasome and motivate further investigation of mechanisms that govern the degradation of diverse classes of BiDAC targets. In this study authors use morphological profiling and CRISPR/Cas9 genetic screens to investigate the mechanisms by which BiDACs induce the degradation of plasma membrane receptor tyrosine kinases (RTKs) EGFR and Her2.

Free-flying honeybees exhibit remarkable cognitive capacities but the neural underpinnings of these capacities cannot be studied in flying insects. Conversely, immobilized bees are accessible to neurobiological investigation but display poor visual learning. To overcome this limitation, we aimed at establishing a controlled visual environment in which tethered bees walking on a spherical treadmill learn to discriminate visual stimuli video projected in front of them. Freely flying bees trained to walk into a miniature Y-maze displaying these stimuli in a dark environment learned the visual discrimination efficiently when one of them (CS+) was paired with sucrose and the other with quinine solution (CS−). Adapting this discrimination to the treadmill paradigm with a tethered, walking bee was successful as bees exhibited robust discrimination and preferred the CS+ to the CS− after training. As learning was better in the maze, movement freedom, active vision and behavioral context might be important for visual learning. The nature of the punishment associated with the CS− also affects learning as quinine and distilled water enhanced the proportion of learners. Thus, visual learning is amenable to a controlled environment in which tethered bees learn visual stimuli, a result that is important for future neurobiological studies in virtual reality.

Abstract From the advancement of tilapia production in recent years, diets are sought that allow the maximum growth, improving health and fish quality. In this study growth, biochemical, hematological and oxidative parameters were evaluated of tilapia fed with increasing selenium levels: 0.53, 0.86, 1.04 and 1.22 mg kg-1. It was used 400 juveniles (initial weight = 36.51 ± 10.88 g), fed for six weeks. There was no effect of selenium on fish growth, biochemical and hematological parameters. In the oxidative parameters, there was an increase in non-protein thiols and a decrease in malondialdehyde levels, evidencing antioxidant effects of selenium. The diet selenium levels above 0.86 mg kg-1 improved the antioxidant system and does not affect to biochemical, hematological and growth parameters of tilapia juveniles. Resumo Com o avanço da produção de tilápia nos últimos anos, buscam-se dietas que possibilitem o máximo crescimento, saúde e qualidade do pescado. Neste trabalho foram avaliados parâmetros de crescimento, bioquímicos, sanguíneos e oxidativos de tilápias alimentadas com níveis crescentes de selênio: 0,53, 0,86, 1,04 e 1,22 mg kg-1. Foram utilizados 400 juvenis (peso inicial =36,51 ± 10,88 g), alimentados durante seis semanas. Não ocorreu efeito do selênio no crescimento, nem nos parâmetros bioquímicos e hematológicos dos peixes. Nos parâmetros oxidativos, ocorreu aumento nos níveis de tióis não-proteicos e diminuição de malondialdeído, evidenciando efeitos antioxidantes do selênio. Os níveis de selênio acima de 0.86 mg kg-1 melhoram o sistema antioxidante dos peixes e não compromete os parâmetros bioquímicos, sanguíneos e de crescimento de juvenis de tilápia.

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 performed 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 identified known components of the proteostasis network and uncovered a novel link between protein and lipid homeostasis. Increasing lipid uptake and/or disrupting lipid metabolism promotes the accumulation of sphingomyelins and cholesterol esters and drives the formation of detergent-insoluble protein aggregates at the lysosome. Proteome profiling of lysosomes revealed ESCRT accumulation, suggesting disruption of ESCRT disassembly, lysosomal membrane repair, and microautophagy. Lipid dysregulation leads to lysosomal membrane permeabilization but does not otherwise impact fundamental aspects of lysosomal and proteasomal functions. Together, these results demonstrate that lipid dysregulation disrupts ESCRT function and impairs proteostasis.

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.

Immature mosquitoes are thought to breathe only atmospheric air through their siphons despite reports of prolonged submerged survival. We studied the survival of last-instar larvae of Aedes aegypti fully submerged at different temperatures and measured the oxygen consumption from air and water-dissolved larvae and pupae of this species under different conditions. Larvae survived much longer than expected, reaching 50% mortality only after 58, 10, and 5 days at 15°, 25°, and 35 °C, respectively. Larval to pupa molt was only observed in larvae with access to air, whereas individuals kept submerged never molted. Although most of the oxygen was obtained from the air, larvae obtained 12.72% of their oxygen from the water, while pupae took only 5.32%. In both media, temperature affected the respiration rate of the larvae, with relatively close Q10 values (1.56 and 1.83 for water and air, respectively). A similar pattern of O2 consumption was observed in Ae. albopictus, whose larvae obtained 12.14% of their oxygen from the water. The detailed quantification of oxygen consumption by mosquito larvae showed that water-dissolved oxygen is not negligible and physiologically relevant, challenging the idea that mosquito larvae only breathe atmospheric oxygen.