Search

BackgroundSkin-penetrating nematodes of the genus Strongyloides infect over 600 million people, posing a major global health burden. Their life cycle includes both a parasitic and free-living generation. During the parasitic generation, infective third-stage larvae (iL3s) actively engage in host seeking. During the free-living generation, the nematodes develop and reproduce on host feces. At different points during their life cycle, Strongyloides species encounter a wide variety of host-associated and environmental bacteria. However, the microbiome associated with Strongyloides species, and the behavioral and physiological interactions between Strongyloides species and bacteria, remain unclear.ResultsWe first investigated the microbiome of the human parasite Strongyloides stercoralis using 16S-based amplicon sequencing. We found that S. stercoralis free-living adults have an associated microbiome consisting of specific fecal bacteria. We then investigated the behavioral responses of S. stercoralis and the closely related rat parasite Strongyloides ratti to an ecologically diverse panel of bacteria. We found that S. stercoralis and S. ratti showed similar responses to bacteria. The responses of both nematodes to bacteria varied dramatically across life stages: free-living adults were strongly attracted to most of the bacteria tested, while iL3s were attracted specifically to a narrow range of environmental bacteria. The behavioral responses to bacteria were dynamic, consisting of distinct short- and long-term behaviors. Finally, a comparison of the growth and reproduction of S. stercoralis free-living adults on different bacteria revealed that the bacterium Proteus mirabilis inhibits S. stercoralis egg hatching, and thereby greatly decreases parasite viability.ConclusionsSkin-penetrating nematodes encounter bacteria from various ecological niches throughout their life cycle. Our results demonstrate that bacteria function as key chemosensory cues for directing parasite movement in a life-stage-specific manner. Some bacterial genera may form essential associations with the nematodes, while others are detrimental and serve as a potential source of novel nematicides.

Diomus guilavoguii Duverger, 1994, an adventive species, is recorded from Guangzhou (Guangdong Province), China for the first time. Larvae of D. guilavoguii were collected in association with an invasive mealybug, Paracoccus marginatus Williams & Granara de Willink, 1992, infesting papayas, cassava and several ornamental plants. However, little has been known about the biology of D. guilavoguii, especially the morphology of their larvae since their original descriptions.Diomus guilavoguii Duverger, 1994, native to Conakry, Guinea (Africa), is recorded as established in Guangdong Province for the first time. However, it is unclear when and how D. guilavoguii spread from Africa to Guangzhou, Guangdong Province. Both the adult and larva feed on the invasive mealybug Paracoccus marginatus Williams & Granara de Willink (Hemiptera, Pseudococcidae) that infests papaya and ornamental plants. In this paper, the external morphology and male genitalia of adults are re-described. The detailed descriptions of larva and pupa are also provided for the first time. The status of D. guilavoguii and D. hennessyi Fürsch, 1987 are discussed.

The proteome profiles of the cuticle and haemolymph of two strains of the Chinese Oak silk moth A. pernyi, with cyan and yellow coloured bodies, were compared in order to identify the differentially expressed proteins (DEPs) that determine the differences in the colouration of the two strains. A total of 324 DEPs, including 124 up-regulated and 200 down-regulated proteins, were identified in the cuticles of the cyan and yellow coloured individuals, and 286 DEPs including 79 up-regulated and 207 down-regulated proteins in the haemolymph of the cyan and yellow coloured individuals. Several DEPs associated with the colour of larvae of A. pernyi were screened, including an ommochrome-binding protein, juvenile hormone esterase, protein yellow, L-dopachrome tautomerase yellow-f2 and fumarylacetoacetase, the expression levels in the cuticle and haemolymph of the yellow larvae were higher than those in the cyan coloured larvae, indicating their possible roles underlying the colouration of the yellow larvae of A. pernyi.

IntroductionNeurodevelopment in larval stages of non-model organisms, with a focus on the serotonin- and FMRFamide-immunoreactive components, has been in the focus of research in the recent past. However, some taxonomic groups remain understudied. Nemertea (ribbon worms) represent such an understudied clade with only few reports on nervous system development mostly from phylogenetically or developmentally derived species. It would be insightful to explore neurodevelopment in additional species to be able to document the diversity and deduce common patterns to trace the evolution of nervous system development.MethodsFluorescent immunohistochemical labeling with polyclonal primary antibodies against serotonin and FMRF-amide and a monoclonal antibody against synapsin performed on series of fixed larval stages of two nemertean species Cephalothrix rufifrons (Archinemertea, Palaeonemertea) and Emplectonema gracile (Monostilifera, Hoplonemertea) were analyzed with confocal laser scanning microscopy.ResultsThis contribution gives detailed accounts on the development of the serotonin- and FMRFamide-immunoreactive subsets of the nervous system in two nemertean species from the first appearance of the respective signals. Additionally, data on synapsin-like immunoreactivity illustrates the general structure of neuropil components. Events common to both investigated species are the appearance of serotonin-like immunoreactive signals before the appearance of FMRF-like immunoreactive signals and the strict progression of the development of the lateral nerve cords from the anteriorly located, ring-shaped brain toward the posterior pole of the larva. Notable differences are (1) the proboscis nervous system that is developing much earlier in investigated larval stages of E. gracile and (2) distinct early, but apparently transient, serotonergic neurons on the frontal and caudal pole of the larva in E. gracile that seem to be absent in C. rufifrons.DiscussionAccording to the results from this investigation and in line with previously published accounts on nervous system development, the hypothetical last common ancestor of Nemertea had a ring-shaped brain arranged around the proboscis opening, from which a pair of ventro-lateral nerve cords develops in anterior to posterior progression. Early frontal and caudal serotonergic neurons that later degenerate or cease to express serotonin are an ancestral character of Nemertea that they share with several other spiralian clades.

This study is the first report of the stalk borer Diatraea impersonatella (Walker) on sugarcane in Honduras. A total of 167 larvae were collected from sugarcane crops in the Department Francisco Morazán, Municipality Villa de San Francisco, Honduras, during November 2022 to January 2023. The larval specimens were reared with the objective of obtaining adults for the morphological identification of the species through the inspection of male genitalia. [ABSTRACT FROM AUTHOR]

Brycon moorei is an endemic species of the Magdalena River basin with a strong commercial, sports and consumption fishing pressure; however, knowledge of ontogeny is scarce or non-existent. For this reason, the present study describes and compares early development in this species. Product of semi-natural induced reproduction, at established times, samples were taken from fertilization until day 15 after hatching to characterize the stages of zygote, cleavage, blastula, gastrula, segmentation, organogenesis, hatching and early juvenile. It was found that the latency time was 6 hours after the second dose at 26°C; hatching occurred at 13 hours post-fertilization (HPF). In the larval stage, cannibalism begins at 22 hours post-hatching (HPH); the maximum buccal opening was reached at 37 HPH with 1773.37 µm and the yolk sac was totally absorbed at 37 HPH. For the pre-bending stage, the mean weight was 3.14±0.36 mg and the length were 6.85±0.53 mm; in the final stage of post-flexion, the average weight and total length were 221.6±15.84 mg and 25.66±0.64mm, respectively. Finally, juveniles with the same characteristics as an adult were presented at 326 HPH. It is concluded that Brycon moorei presents an embryonic and larval development, like most of the species of the genus Brycon and others of the Characidae family; but with the shortest time to consume endogenous reserves and with the shortest time to start cannibalism. [ABSTRACT FROM AUTHOR]

Clupeid fish species are widely distributed and of highly variable stock sizes. In the North Sea, the common clupeid species are herring (Clupea harengus) and sprat (Sprattus sprattus), but during recent decades, the generally more southerly distributed sardine (Sardina pilchardus) have been more frequently observed. Comparative studies of early life stages of small pelagic clupeids are scarce, and their abilities to co‐exist and relations to environmental characteristics are vastly understudied. We here investigated and compared distributional patterns of co‐occurring larval sprat and sardine in the North Sea, hypothesizing that they are separated into spatial niches linked to specific hydrographical characteristics. Sampling was carried out by a large ring‐net during standard fish surveys (IBTS Q3) in August 2018, 2019, and 2020. Sprat larvae were found widespread across the area of investigation, with the highest concentration in the central North Sea off the eastern and northern flanks of Dogger Bank, where abundances could reach 20 larvae/m2. Sardine larvae, on the other hand, showed their highest abundances in the Southern and German Bights. Distributions of the two species appeared complementary, and statistical correlations were indicative of separate hydrographical niches, where sardine larvae resided in relatively warmer and fresher water. The relative abundances of sardine versus sprat varied between years. Sardine larvae were especially abundant in 2020, twice as abundant as sprat, and observations indicate increasing importance of sardines in the North Sea. [ABSTRACT FROM AUTHOR]

A new species of the subgenus Leptus (Amaroptus), L. (A.) sivasensissp. n., is described and illustrated from an ectoparasitic larva collected from Cerceris sabulosa (Panzer, 1799) (Hymenoptera: Crabronidae) in İmranlı district of Sivas province, Türkiye. The holotype and paratypes of Leptus (Amaroptus) vuki are studied and some corrections to the original description are presented. Also, new metric data and host records are given for L. (L.) tridentatus and L. (L.) rosellae, and intraspecific differences of both species are discussed. [ABSTRACT FROM AUTHOR]

Larvae and juveniles of three species in the family Gobiidae are described based on laboratory-reared material: Bathygobius fuscus to post-settlement, Bathygobius cyclopterus to 2 days old, and Bathygobius petrophilus to just after hatching. Newly hatched larvae of these species are distinguishable from each other by the melanophore arrangements on the dorsal region of the trunk, ventrally near the tip of the tail, and along the lateral midline. The early development of Bathygobius fuscus was similar to that described previously for Bathygobius soporator but differed in the appearance of melanophores and the shape of the second dorsal fin and anal fin. [ABSTRACT FROM AUTHOR]

Larval settlement is an important process that drives population and community dynamics of marine invertebrates. Barnacles are frequently used to investigate settlement mechanisms of marine invertebrate larvae. Adult barnacles induce settlement of conspecific larvae nearby which ultimately facilitates copulation with neighbouring individuals. A significant factor involved in the larval induction process is the proteinaceous waterborne settlement pheromone (WSP), which is purified from adult barnacles. A previous study suggested that the concentration of WSP informs barnacle cyprid larvae about the abundance of adult barnacles in the environment nearby but it is unclear whether WSP works in a species-specific or non-species-specific manner. In this study, we conducted settlement assays using recombinant WSPs and cyprids of two congenic barnacle species, Amphibalanus amphitrite and A. improvisus , to investigate the species specificity of WSPs. We found that A. amphitrite and A. improvisus cyprids responded similarly to con-specific WSPs as to allo-specific WSP stimuli indicating that WSPs are not species-specific. Our findings suggest that cyprids approach potential settlement sites using WSPs, non-species-specific settlement pheromones, before performing a closer search of the substratum using a species-specific pheromone. [ABSTRACT FROM AUTHOR]

The life cycle of the common ancestor of Metazoa is a widely debated topic in EvoDevo. This is intimately linked to a number of questions, such as how the larva appeared in the metazoan life cycle and which larval form can be considered ancestral. To approach these questions, we can analyse the life cycles and larval forms of Cnidaria, the basal metazoans that form a sister group to the Bilateria. Almost all cnidarians have a pelagic larva in their life cycle. These larvae are commonly referred to as "planula," with few exceptions. The planula is a ciliated lecithotrophic larva with epithelial ectoderm and endoderm, a gastric cavity, and an elongated body. The review examines whether the larvae of various Cnidaria fit this description and explores which larval form is ancestral for different cnidarian taxa. It also highlights the enormous diversity of cnidarian larvae, which is still underestimated, and infers the relationship between the evolution of life cycles, reproductive patterns, and larval forms in various phylogenetic groups of cnidarians. [ABSTRACT FROM AUTHOR]

We describe and illustrate the semiaquatic Ptilodactylidae Anchytarsus campanerisp. n., based on adult and immature specimens collected in a small mountainous stream in Tocantins State (Brazil). Mature larvae, pupae and adults were found co-occurring in partially submerged leaf packs. Adults can be easily recognized by their total body length and body length/width ratio, shape of the last labial palpomere of the male and aedeagal morphology. We also provide updated taxonomic keys to identify larvae and adults of Anchytarsus and notes on their biology. [ABSTRACT FROM AUTHOR]

The rice leaf folder, Cnaphalocrocis medinalis (Lepidoptera: Pyralidae), is a notorious pest of rice in Asia. The larvae and adults of C. medinalis utilize specialized chemosensory systems to adapt to different environmental odors and physiological behaviors. However, the differences in chemosensory genes between the olfactory organs of these two different developmental stages remain unclear. Here, we conducted a transcriptome analysis of larvae heads, male antennae, and female antennae in C. medinalis and identified 131 putative chemosensory genes, including 32 OBPs (8 novel OBPs), 23 CSPs (2 novel CSPs), 55 ORs (17 novel ORs), 19 IRs (5 novel IRs) and 2 SNMPs. Comparisons between larvae and adults of C. medinalis by transcriptome and RT-qPCR analysis revealed that the number and expression of chemosensory genes in larval heads were less than that of adult antennae. Only 17 chemosensory genes (7 OBPs and 10 CSPs) were specifically or preferentially expressed in the larval heads, while a total of 101 chemosensory genes (21 OBPs, 9 CSPs, 51 ORs, 18 IRs, and 2 SNMPs) were specifically or preferentially expressed in adult antennae. Our study found differences in chemosensory gene expression between larvae and adults, suggesting their specialized functions at different developmental stages of C. medinalis. These results provide a theoretical basis for screening chemosensory genes as potential molecular targets and developing novel management strategies to control C. medinalis. [ABSTRACT FROM AUTHOR]

In this study, we morphologically examine larval specimens of Ranitomeya variabilis, which were breed in captivity and genetically determined to belong to the French Guiana population. We provide detailed data on the external morphology, chondrocranium, cranial muscle systems and inner organs of the tadpoles. Additionally, we provide essential characteristics for the recognition of the tadpoles of the different Ranitomeya species. The external morphology of the R. variabilis tadpoles was assessed by measurements and photographs of the specimens. Internal morphology was analyzed using µCT images, µCT-based three-dimensional reconstructions, and dissection of specimens for organ and muscle descriptions. The majority of the muscle configurations observed herein for larval specimens of R. variabilis are consistent with data presented in previous studies for larvae of other Ranitomeya species. In addition, several of the observed morphological characters are defined for different taxonomic levels within Dendrobatidae, e.g., the reduction of tectal cartilages and the insertion of the M. rectus cervicis on the third or fourth branchial arch. The absence of the anterolateral process of the ceratohyal in Ranitomeya and Dendrobates further strengthens their close relationship, in contrast to the more distantly related Epipedobates and Phyllobates where this structure is present. The absence of the M. levator arcuum branchialium I and II, the M. interhyoideus posterior and the M. diaphragmatopraecordialis might be defining traits for Ranitomeya. The specific characters observed in this study for R. variabilis, are the fusion of the superficialis and profundus portion of the musculus levator longus larvae and the absence of the parotic crista. [ABSTRACT FROM AUTHOR]

A new host plant record and notes on the immature stages of the butterfly Anthene lycaenina villosina is described and illustrated from specimens documented in the Balinsasayao Twin Lakes Natural Park, Negros Island, Philippines. [ABSTRACT FROM AUTHOR]

An animal's ability to regrow lost tissues or structures can vary greatly during its life cycle. The annelid Capitella teleta exhibits posterior, but not anterior, regeneration as juveniles and adults. In contrast, embryos display only limited replacement of specific tissues. To investigate when during development individuals of C. teleta become capable of regeneration, we assessed the extent to which larvae can regenerate. We hypothesized that larvae exhibit intermediate regeneration potential and demonstrate some features of juvenile regeneration, but do not successfully replace all lost structures. Both anterior and posterior regeneration potential of larvae were evaluated following amputation. We used several methods to analyze wound sites: EdU incorporation to assess cell proliferation; in situ hybridization to assess stem cell and differentiation marker expression; immunohistochemistry and phalloidin staining to determine presence of neurites and muscle fibers, respectively; and observation to assess re‐epithelialization and determine regrowth of structures. Wound healing occurred within 6 h of amputation for both anterior and posterior amputations. Cell proliferation at both wound sites was observed for up to 7 days following amputation. In addition, the stem cell marker vasa was expressed at anterior and posterior wound sites. However, growth of new tissue was observed only in posterior amputations. Neurites from the ventral nerve cord were also observed at posterior wound sites. De novo ash expression in the ectoderm of anterior wound sites indicated neuronal cell specification, although the absence of elav expression indicated an inability to progress to neuronal differentiation. In rare instances, cilia and eyes re‐formed. Both amputations induced expanded expression of the myogenesis gene MyoD in preexisting tissues. Our results indicate that amputated larvae complete early, but not late, stages of regeneration, which indicates a gradual acquisition of regenerative ability in C. teleta. Furthermore, amputated larvae can metamorphose into burrowing juveniles, including those missing brain and anterior sensory structures. To our knowledge, this is the first study to assess regenerative potential of annelid larvae. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Dalian Ocean University is the property of Journal of Dalian Ocean University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The toxic ribbon worm, Cephalothrix cf. simula (Palaeonemertea, Nemertea), possesses extremely high concentrations of tetrodotoxin (TTX). Although TTX has been found in the eggs of this species, the fate of the toxin in the ontogeny of the animal has not been explored. Here, using high performance liquid chromatography with tandem mass spectrometry and immunohistochemistry with anti-TTX antibodies, we examined levels, profile, and localization of TTX and its analogues (TTXs) in larvae of C. cf. simula throughout 41 days post-fertilization. A detailed investigation of cells in sites of TTX-accumulation was performed with light and electron microscopy. Newly hatched larvae possessed weak TTX-like immunoreactivity in all cells. With subsequent development, intensity of TTX-labeling in the ectodermal structures, mesodermal cells and apical cylinder of the apical gland increased. In the ectodermal structures, an intense TTX-labeling was observed in the multiciliated, type II granular, type I mucoid, and basal cells of the epidermis, and in the type III granular cells of the mouth gland. In the mesoderm, TTX was localized in the muscle and unigranular parenchyma-like cells. Eggs and larvae of C. cf. simula contained five TTXs, with two major toxins – TTX and 5,6,11-trideoxyTTX. Level and relative proportion of TTXs did not differ significantly among developmental stages, confirming that larvae obtained toxins from maternal eggs and were able to retain it. The results of this study provide insights into the formation of TTX-bearing apparatus of C. cf. simula through the larval development. [ABSTRACT FROM AUTHOR]

Copyright of Anbar Journal of Agricultural Sciences is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The results of the study of growth, ossification sequence and peculiarities of the development of skeletal elements, body proportions and meristic characters of laboratory-reared larvae and fry of two dwarf forms of Arctic charr Salvelinus alpinus сomplex spawning at the shore slope (Lake Tokko) and in the profundal zone (Lake Bol'shoe Leprindo) (Transbaikalia) are presented. Charr from Lake Bol'shoe Leprindo demonstrated slower rates of growth and morphogenesis, retardation of the ossification of their predorsal bones series with its displacement from larval to juvenile period of the ontogeny, but the acceleration of the development of the vertebral column. High mortality of pre-larvae of charr from this lake connected with the transfer to exogenous feeding was observed. For the first time the problem of the reorganization of early ontogeny of charr of the genus Salvelinus in connection with the colonization of deepwater habitat is discussed. In larvae of charr from Lake Tokko, the ossification of vertebral centra was often accompanied by the formation of anomalous bony structures in the notochord. The phenomenon of the penetration of skeletogenic cells into the notochord, which has been described in hybrids of sympatric charr forms, was found in a pure charr form for the first time. The development of characteristic morphological features of the two charr forms in the ontogeny was traced. Differences in body proportions between their fry corresponding to those between adult fish were revealed. [ABSTRACT FROM AUTHOR]

Food availability is believed to affect macro-invertebrate larval survival at sea, which was poorly demonstrated. On the coast immediately outside an estuary (Ariake Sound, Kyushu, Japan), a population of the callianassid shrimp, Neotrypaea harmandi, with diatom-feeding larvae, lies on an intertidal sandflat. It is likely from previous research that the shrimp population is self-recruited by larvae in 20–50-m water depths of an interface area influenced by estuary and inner shelf and growth of a dominant diatom species in the estuary is nitrogen-limited. Apparent shrimp self-recruitment rates were monitored each year during 1989–2013. Public databases were used about the largest river's flow and dissolved inorganic nitrogen (DIN) in the estuary. A high positive correlation was detected between shrimp recruitment rate and DIN concentration which was in turn correlated with river flow rate. Hydrographic surveys were conducted from inner shelf to estuary in 2011–2013. Chlorophyll-fluorescence was positively related with DIN concentration in the near-surface for estuary and in the lower subsurface for inner shelf. Based on a public reanalysis model database for temperature in the western North Pacific were examined yearly variations in the degree of western Kyushu-coastward movement by potentially nutrient-rich, cold bottom waters from offshore. The contributions of DIN from estuary and from inner shelf to shrimp recruitment rate were assessed by multiple regression, with, as explanatory variables, estuarine DIN concentration and lower temperature anomaly in inner-shelf water (surrogate for the higher DIN concentration). DIN of estuary and 'DIN' of inner shelf explained recruitment-rate variations by 77% and 23%, respectively. [ABSTRACT FROM AUTHOR]

Pesticides are linked to global insect declines, with impacts on biodiversity and essential ecosystem services. In addition to well-documented direct impacts of pesticides at the current stage or time, potential delayed "carryover" effects from past exposure at a different life stage may augment impacts on individuals and populations. We investigated the effects of current exposure and the carryover effects of past insecticide exposure on the individual vital rates and population growth of the solitary bee, Osmia lignaria Bees in flight cages freely foraged on wildflowers, some treated with the common insecticide, imidacloprid, in a fully crossed design over 2 y, with insecticide exposure or no exposure in each year. Insecticide exposure directly to foraging adults and via carryover effects from past exposure reduced reproduction. Repeated exposure across 2 y additively impaired individual performance, leading to a nearly fourfold reduction in bee population growth. Exposure to even a single insecticide application can have persistent effects on vital rates and can reduce population growth for multiple generations. Carryover effects had profound implications for population persistence and must be considered in risk assessment, conservation, and management decisions for pollinators to mitigate the effects of insecticide exposure.

Knowledge about how the COVID-19 pandemic can affect aquatic wildlife is still extremely limited, and no effect of SARS-CoV-2 or its structural constituents on invertebrate models has been reported so far. Thus, we investigated the presence of the 2019-new coronavirus in different urban wastewater samples and, later, evaluated the behavioral and biochemical effects of the exposure of Culex quinquefasciatus larvae to two SARS-CoV-2 spike protein peptides (PSPD-2002 and PSPD-2003) synthesized in our laboratory. Initially, our results show the contamination of wastewater by the new coronavirus, via RT-qPCR on the viral N1 gene. On the other hand, our study shows that short-term exposure (48 h) to a low concentration (40 μg/L) of the synthesized peptides induced changes in the locomotor and the olfactory-driven behavior of the C. quinquefascitus larvae, which were associated with increased production of ROS and AChE activity (cholinesterase effect). To our knowledge, this is the first study that reports the indirect effects of the COVID-19 pandemic on the larval phase of a freshwater invertebrate species. The results raise concerns at the ecological level where the observed biological effects may lead to drastic consequences.

A major advantage of experimentation in Xenopus is the ability to query the localization of endogenous proteins and RNAs in situ in the entire animal during all of development. Here I describe three variations of staining to visualize mRNAs and proteins in developing Xenopus embryos and tadpoles. The first section outlines a traditional colorimetric staining for mRNAs that is suitable for all stages of development, and the second extends this protocol for fluorescence-based detection for higher spatial and quantitative resolution. The final section details detection of proteins by immunofluorescence, optimized for tadpole stages but widely applicable to others. Finally, optimization strategies are provided.

Cell death is a critical process that occurs normally in health and disease. However, its study is limited due to available technologies that only detect very late stages in the process or specific death mechanisms. Here, we report the development of a family of fluorescent biosensors called genetically encoded death indicators (GEDIs). GEDIs specifically detect an intracellular Ca2+ level that cells achieve early in the cell death process and that marks a stage at which cells are irreversibly committed to die. The time-resolved nature of a GEDI delineates a binary demarcation of cell life and death in real time, reformulating the definition of cell death. We demonstrate that GEDIs acutely and accurately report death of rodent and human neurons in vitro, and show that GEDIs enable an automated imaging platform for single cell detection of neuronal death in vivo in zebrafish larvae. With a quantitative pseudo-ratiometric signal, GEDIs facilitate high-throughput analysis of cell death in time-lapse imaging analysis, providing the necessary resolution and scale to identify early factors leading to cell death in studies of neurodegeneration.

The chemical threat agent tetramethylenedisulfotetramine (TETS) is a γ-aminobutyric acid type A receptor (GABA AR) antagonist that causes life threatening seizures. Currently, there is no specific antidote for TETS intoxication. TETS-induced seizures are typically treated with benzodiazepines, which function as nonselective positive allosteric modulators (PAMs) of synaptic GABAARs. The major target of TETS was recently identified as the GABAAR α2β3γ2 subtype in electrophysiological studies using recombinantly expressed receptor combinations. Here, we tested whether these in vitro findings translate in vivo by comparing the efficacy of GABAAR subunit-selective PAMs in reducing TETS-induced seizure behavior in larval zebrafish. We tested PAMs targeting α1, α2, α2/3/5, α6, ß2/3, ß1/2/3, and δ subunits and compared their efficacy to the benzodiazepine midazolam (MDZ). The data demonstrate that α2- and α6-selective PAMs (SL-651,498 and SB-205384, respectively) were effective at mitigating TETS-induced seizure-like behavior. Combinations of SB-205384 and MDZ or SL-651,498 and 2-261 (ß2/3-selective) mitigated TETS-induced seizure-like behavior at concentrations that did not elicit sedating effects in a photomotor behavioral assay, whereas MDZ alone caused sedation at the concentration required to stop seizure behavior. Isobologram analyses suggested that SB-205384 and MDZ interacted in an antagonistic fashion, while the effects of SL-651,498 and 2-261 were additive. These results further elucidate the molecular mechanism by which TETS induces seizures and provide mechanistic insight regarding specific countermeasures against this chemical convulsant.

A striking feature of pathogenic Candida species is morphological plasticity that facilitates environmental adaptation and host infection. Candida auris is an emerging multidrug-resistant fungal pathogen first described in Japan in 2009. In this study, we demonstrate that clinical isolates of C. auris have multiple colony and cellular morphologies including the yeast, filamentous, aggregated, and elongated forms. This phenotypic diversity has been observed in eight clinical isolates of C. auris representing four major genetic clades, suggesting that it could be a general characteristic. We further demonstrate that different cell types of C. auris exhibit distinct antifungal resistance and virulence properties in a Galleria mellonella infection model. Our findings imply that morphological diversity is an important biological feature of C. auris and could be a contributor to its emergence and rapid prevalence worldwide.Lay summaryCandida auris is an emerging multidrug-resistant fungal pathogen. Morphological analyses indicate that filamentation is a general feature of clinical isolates of C. auris. This ability is associated with antifungal resistance and virulence.

Balancing exploration and anti-predation are fundamental to the fitness and survival of all animal species from early life stages. How these basic survival instincts drive learning remains poorly understood. Here, using a light/dark preference paradigm with well-controlled luminance history and constant visual surrounding in larval zebrafish, we analyzed intra- and intertrial dynamics for two behavioral components, dark avoidance and center avoidance. We uncover that larval zebrafish display short-term learning of dark avoidance with initial sensitization followed by habituation; they also exhibit long-term learning that is sensitive to trial interval length. We further show that such stereotyped learning patterns is stimulus-specific, as they are not observed for center avoidance. Finally, we demonstrate at individual levels that long-term learning is under homeostatic control. Together, our work has established a novel paradigm to understand learning, uncovered sequential sensitization and habituation, and demonstrated stimulus specificity, individuality, as well as dynamicity in learning.

Developmental and behavioral plasticity allow animals to prioritize alternative genetic programs during fluctuating environments. Behavioral remodeling may be acute in animals that interact with host organisms, since reproductive adults and the developmentally arrested larvae often have different ethological needs for chemical stimuli. To understand the genes that coordinate the development and host-seeking behavior, we used the entomophilic nematode Pristionchus pacificus to characterize dauer-constitutive mutants (Daf-c) that inappropriately enter developmental diapause to become dauer larvae. We found two Daf-c loci with dauer-constitutive and cuticle exsheathment phenotypes that can be rescued by the feeding of Δ7-dafachronic acid, and that are dependent on the conserved canonical steroid hormone receptor Ppa-DAF-12. Specifically at one locus, deletions in the sole hydroxysteroid dehydrogenase (HSD) in P. pacificus resulted in Daf-c phenotypes. Ppa-hsd-2 is expressed in the canal-associated neurons (CANs) and excretory cells whose homologous cells in Caenorhabditis elegans are not known to be involved in the dauer decision. While in wildtype only dauer larvae are attracted to host odors, hsd-2 mutant adults show enhanced attraction to the host beetle pheromone, along with ectopic activation of a marker for putative olfactory neurons, Ppa-odr-3. Surprisingly, this enhanced odor attraction acts independently of the Δ7-DA/DAF-12 module, suggesting that Ppa-HSD-2 may be responsible for several steroid hormone products involved in coordinating the dauer decision and host-seeking behavior in P. pacificus.

BackgroundDespite increasing documentation of insecticide resistance in malaria vectors against public health insecticides in sub-Saharan Africa, there is a paucity of information on the potential fitness costs of pyrethroid resistance in malaria vectors, which is important in improving the current resistant management strategies. This study aimed to assess the fitness cost effects of insecticide resistance on the development and survival of immature Anopheles gambiae from western Kenya.MethodsTwo-hour old, first instar larvae (L1) were introduced and raised in basins containing soil and rainwater in a semi-field set-up. Each day the number of surviving individuals per larval stage was counted and their stage of development were recorded until they emerged as adults. The larval life-history trait parameters measured include mean larval development time, daily survival and pupal emergence. Pyrethroid-resistant colony of An. gambiae sensu stricto and susceptible colony originating from the same site and with the same genetic background were used. Kisumu laboratory susceptible colony was used as a reference.ResultsThe resistant colony had a significantly longer larval development time through the developmental stages than the susceptible colony. The resistant colony took an average of 2 days longer to develop from first instar (L1) to fourth instar (L4) (8.8 ± 0.2 days) compared to the susceptible colony (6.6 ± 0.2 days). The development time from first instar to pupa formation was significantly longer by 3 days in the resistant colony (10.28 ± 0.3 days) than in susceptible colony (7.5 ± 0.2 days). The time from egg hatching to adult emergence was significantly longer for the resistant colony (12.1 ± 0.3 days) than the susceptible colony (9.6 ± 0.2 days). The pupation rate (80%; 95% (CI: 77.5-83.6) vs 83.5%; 95% (CI: 80.6-86.3)) and adult emergence rate (86.3% vs 92.8%) did not differ between the resistant and susceptible colonies, respectively. The sex ratio of the females to males for the resistant (1:1.2) and susceptible colonies (1:1.07) was significantly different.ConclusionThe study showed that pyrethroid resistance in An. gambiae had a fitness cost on their pre-imaginal development time and survival. Insecticide resistance delayed the development and reduced the survivorship of An. gambiae larvae. The study findings are important in understanding the fitness cost of insecticide resistance vectors that could contribute to shaping resistant management strategies.

Glucose is arguably the most important molecule in metabolism, and its dysregulation underlies diabetes. We describe a family of single-wavelength genetically encoded glucose sensors with a high signal-to-noise ratio, fast kinetics, and affinities varying over four orders of magnitude (1 μM to 10 mM). The sensors allow mechanistic characterization of glucose transporters expressed in cultured cells with high spatial and temporal resolution. Imaging of neuron/glia co-cultures revealed ∼3-fold faster glucose changes in astrocytes. In larval Drosophila central nervous system explants, intracellular neuronal glucose fluxes suggested a rostro-caudal transport pathway in the ventral nerve cord neuropil. In zebrafish, expected glucose-related physiological sequelae of insulin and epinephrine treatments were directly visualized. Additionally, spontaneous muscle twitches induced glucose uptake in muscle, and sensory and pharmacological perturbations produced large changes in the brain. These sensors will enable rapid, high-resolution imaging of glucose influx, efflux, and metabolism in behaving animals.

The influence of temperature on development, growth and survival of pacific oyster Crassostrea gigas embryos and larvae is investigated in controlled conditions at a hatchery located in Peter the Great Bay (Japan Sea) — the TINRO subdivision for mariculture on Popov Island in July-August, 2019. The oyster embryos and larvae obtained from natural producers in the process of artificial spawning were grown under temperature of 21–22 оC (close to natural conditions in the coastal waters of Primorye) and 24–25 оC. The higher temperature had a positive effect on development and growth rate of embryos and larvae. Under the temperature of 24–25 оC, the embryogenesis was completed earlier by 2 hours, the transition to the D-veliger stage — by 8 hours, the stage of veliconch was reached in 1 day earlier, the stage of pediveliger — in 4 days earlier than under the temperature of 21–22 оC. The daily size increments were larger under the higher temperature, with the most significant differences at the stages of veliger (6.4 vs 4.2 µm day–1) and veliconch (14.3 vs 10.9 µm day–1), with no difference at the stage of pediveliger. The greatest average daily increment was reached with exotrophic nutrition (at the veliconch stage) in both cases. The larval mortality was higher under the higher temperature in 1.3 times at the stages from fertilized egg to D-veliger and in 1.4 times at the stages from D-veliger to pediveliger because of intensification of metabolic processes and the water pollution in the tanks for growing, with the largest difference at the stages of veliger and veliconch, as well, as the longest ones. There is concluded that the temperature of 24–25 оC lays within the range of optimal conditions for embryonic and larval development of pacific oyster (within the biokinetic zone) and this temperature is recommended for cultivation of this species in Primorye hatcheries, with selection of optimal parameters for the rearing.

Oryctes rhinoceros merupakan serangga fitofag dan telah dilaporkan sebagai hama di beberapa negara. Larva O. rinocheros makan pada bahan organik (bagian tanaman yang membusuk) dan tidak menyebabkan kerusakan ekonomi. Seperti pada kebanyakan serangga, O. rhinoceros berinteraksi dengan mikroorganisme pada sistem pencernaanya. Selain itu, mikroorganisme dalam saluran pencernaan serangga juga merupakan sumber daya alam yang bermanfaat untuk kepentingan manusia, seperti enzim-enzim yang memiliki arti penting dalam bidang industri dan digunakan sebagai agens bioremediator untuk mengatasi masalah pencemaran lingkungan. Penelitian ini bertujuan untuk mengeksplorasi dan mempelajari keanekaragaman khamir dalam saluran pencernaan larva O. rhinoceros. Pada studi ini, khamir diisolasi dari saluran pencernaan instar tiga O. rhinoceros dan ditumbuhkan pada media Yeast Malt Agar (YMA). Berdasarkan ciri makroskopis dan mikroskopis, 7 isolat khamir yang diperoleh teridentifikasi sebagai Candida sp. (isolat K1 dan K4), Pichia sp. (isolat K3), dan Debaromyces sp.(K2, K5, K6 dan K7).

Background: Edible insects are rich in protein, amino acids, fat, vitamins, and trace elements. However, they are the potential carriers of toxicants, allergenic substances, anti-nutrients, and pathogens. The present study aims to determine the proximate and nutritional, fatty acid, metal composition, and microbial load of palm weevil larvae (Rhynchophorus phoenicis Fabricius, (Coleoptera: Curculionidae)), an insect species commonly consumed in Nigeria. Methods: Twenty five R. phoenicis were randomly collected in April, 2021 from different local farms. The insects were exterminated by freezing and thereafter defrosted at room temperature in the laboratory; with the exception of the samples for moisture analysis, they were oven dried to a constant weight at around 65 °C for 24 h, grounded, and analyzed for proximate content, fatty acids, metals, and microbial load following standard laboratory procedures. Results: The results show that R. phoenicis contained 45.60% crude fat, 15.79% crude fiber, and 5.25% crude protein by weight. Linoleic acid, oleic acid, and palmitic acid made up most of the fatty acid concentrations at 54.13, 23.86, and 14.19%, respectively. Iron (Fe) content was the highest metal (4.923 ppm), followed by manganese (Mn; 2.767 ppm) and zinc (Zn; 1.04 ppm). The isolated microorganisms were mold and yeast (5×10-5 Colony Forming Unit (CFU)/g), Staphylococcus sp. (33×10-5 CFU/g), and Micrococcus/Bacillus substilis sp. (5×10-5 CFU/g). Conclusion: The high nutritional composition present in R. phoenicis evaluated in this study, compared to the dietary protein value obtained from other animal food sources, suggests the need for their adoption as animal protein and essential fatty acid sources in human diets. DOI: 10.18502/jfqhc.10.2.12668

Thyroid hormones (THs) are essential for normal vertebrate development and diverse environmental chemicals are hypothesized to cause developmental toxicity by disrupting TH-mediated signaling. The larval zebrafish (Danio rerio) is an emerging in vivo model of developmental TH disruption; however, the effects of TR antagonism have not yet been studied in zebrafish. NH3, generally considered a potent and specific thyroid hormone receptor (TR) antagonist, has been used in rodents and Xenopus laevis to characterize phenotypes of TR antagonism. The objective of this study is to determine the effects of NH3 on endpoints previously determined to be TH-sensitive in larval zebrafish, specifically teratology and mortality, photomotor behavior, and mRNA expression of TH signaling genes. Zebrafish embryos were exposed to NH3 via static waterborne exposure at concentrations ranging from 0.001 to 10 μM beginning at 6 h post-fertilization (hpf) through 5 days post fertilization (dpf). Significant mortality and teratogenesis was observed at 3, 4, and 5 dpf in zebrafish exposed to NH3 at 10 μM. At concentrations that did not cause significant mortality, NH3 did not exert a consistent antagonistic effect on photomotor behavior assays or mRNA expression when administered alone or in the presence of exogenous T4. Rather, depending on the NH3 concentration and larval age NH3 decreased or increased swimming triggered by transition from light to dark. Similarly, inconsistent antagonistic and agonistic effects on mRNA expression of TH signaling genes were noted following treatment with NH3 alone. NH3 did inhibit T4 (30 nM)-induced gene expression; however, this was only consistently observed at a concentration of NH3 (10 μM) that also caused significant mortality. Collectively, these results suggest that NH3 does not act solely as a TR antagonist in larval zebrafish, but instead exhibits complex modulatory effects on TR activity. These data support the hypothesis that NH3 is a selective thyroid hormone receptor modulator. Further studies of NH3 interactions with the zebrafish thyroid hormone receptor are required to characterize the activity of NH3 in target tissues of the larval zebrafish at the molecular level, highlighting the importance of characterizing NH3 effects in specific models of TH-disruption to better interpret its actions in mechanistic screens of environmental chemicals for TH action.

Learning changes the activity of neurons across multiple brain regions, but the significance of this distributed organization remains poorly understood, owing in part to the difficulty of observing brain-wide activity patterns in commonly used mammalian model systems. This review discusses the promise of using the small and optically accessible nervous system of larval zebrafish to study the brain-wide networks that encode experience. I discuss the opportunities and challenges of studying learning and memory in the larval zebrafish, the lessons learned from recent studies of brain-wide imaging during experience-dependent behavior, and the potential for using zebrafish neurotechnology to understand the physiological principles and behavioral significance of distributed memory networks.

De novo heterozygous variants in the brain-specific transcription factor Neuronal Differentiation Factor 2 (NEUROD2) have been recently associated with early-onset epileptic encephalopathy and developmental delay. Here, we report an adolescent with developmental delay without seizures who was found to have a novel de novo heterozygous NEUROD2 missense variant, p.(Leu163Pro). Functional testing using an in vivo assay of neuronal differentiation in Xenopus laevis tadpoles demonstrated that the patient variant of NEUROD2 displays minimal protein activity, strongly suggesting a loss of function effect. In contrast, a second rare NEUROD2 variant, p.(Ala235Thr), identified in an adolescent with developmental delay but lacking parental studies for inheritance, showed normal in vivo NEUROD2 activity. We thus provide clinical, genetic, and functional evidence that NEUROD2 variants can lead to developmental delay without accompanying early-onset seizures, and demonstrate how functional testing can complement genetic data when determining variant pathogenicity.

The composition of tick microbiomes varies both within and among tick species. Whether this variation is intrinsic (related to tick characteristics) or extrinsic (related to vertebrate host and habitat) is poorly understood but important, as microbiota can influence the reproductive success and vector competence of ticks. We aimed to uncover what intrinsic and extrinsic factors best explain the microbial composition and taxon richness of 11 species of neotropical ticks collected from eight species of small mammals in 18 forest fragments across central Panama. Microbial richness varied among tick species, life stages, and collection sites but was not related to host blood source. Microbiome composition was best explained by tick life stage, with bacterial assemblages of larvae being a subset of those of nymphs. Collection site explained most of the bacterial taxa with differential abundance across intrinsic and extrinsic factors. Francisella and Rickettsia were highly prevalent, but their proportional abundance differed greatly among tick species, and we found both positive and negative cooccurrence between members of these two genera. Other tick endosymbionts (e.g., Coxiella and Rickettsiella) were associated with specific tick species. In addition, we detected Anaplasma and Bartonella in several tick species. Our results indicate that the microbial composition and richness of neotropical ticks are principally related to intrinsic factors (tick species and life stage) and collection site. Taken together, our analysis informs how tick microbiomes are structured and can help anchor our understanding of tick microbiomes from tropical environments more broadly.IMPORTANCE Blood-feeding arthropod microbiomes often play important roles in disease transmission, yet the factors that structure tick microbial communities in the Neotropics are unknown. Utilizing ticks collected from live animals in neotropical forest fragments, this study teases apart the contributions of intrinsic and extrinsic tick-associated factors on tick microbial composition as well as which specific microbes contribute to differences across tick species, tick life stages, the mammals they fed on, and the locations from where they were sampled. Furthermore, this study provides revelations of how notable tick-associated bacterial genera are interacting with other tick-associated microbes as well as the forest animals they encounter.

In the fruit fly Drosophila melanogaster, gustatory sensory neurons express taste receptors that are tuned to distinct groups of chemicals, thereby activating neural ensembles that elicit either feeding or avoidance behavior. Members of a family of ligand -gated receptor channels, the Gustatory receptors (Grs), play a central role in these behaviors. In general, closely related, evolutionarily conserved Gr proteins are co-expressed in the same type of taste neurons, tuned to chemically related compounds, and therefore triggering the same behavioral response. Here, we report that members of the Gr28 subfamily are expressed in largely non-overlapping sets of taste neurons in Drosophila larvae, detect chemicals of different valence, and trigger opposing feeding behaviors. We determined the intrinsic properties of Gr28 neurons by expressing the mammalian Vanilloid Receptor 1 (VR1), which is activated by capsaicin, a chemical to which wild-type Drosophila larvae do not respond. When VR1 is expressed in Gr28a neurons, larvae become attracted to capsaicin, consistent with reports showing that Gr28a itself encodes a receptor for nutritious RNA. In contrast, expression of VR1 in two pairs of Gr28b.c neurons triggers avoidance to capsaicin. Moreover, neuronal inactivation experiments show that the Gr28b.c neurons are necessary for avoidance of several bitter compounds. Lastly, behavioral experiments of Gr28 deficient larvae and live Ca2+ imaging studies of Gr28b.c neurons revealed that denatonium benzoate, a synthetic bitter compound that shares structural similarities with natural bitter chemicals, is a ligand for a receptor complex containing a Gr28b.c or Gr28b.a subunit. Thus, the Gr28 proteins, which have been evolutionarily conserved over 260 million years in insects, represent the first taste receptor subfamily in which specific members mediate behavior with opposite valence.

BACKGROUND: Understanding the spatio-temporal dynamics of prey and predator distributions can provide valuable insights into pest management strategies and conservation of natural enemies in agro-ecosystems. The alfalfa weevil, Hypera postica (Gyllenhal), is an economically important pest of alfalfa throughout the western United States. Coccinellids and nabids are among the most important natural enemies of this species, contributing to the biological control of H. postica in alfalfa fields. The spatio-temporal dynamics of H. postica and these two predator groups were investigated using 81 (= 9 × 9 grid) sample points in each of five alfalfa fields in north-central Montana. The data were analyzed using variogram and spatial analysis by distance indices (SADIE). RESULTS: Variogram analysis revealed the spatial dependence (aggregation) of H. postica in 17 of 19 sampling times for larvae, and three of 12 sampling times for adults. Using SADIE, statistically significant aggregation distribution was evident in four of 19 sampling times for larvae, and five of 12 sampling times for adults of H. postica. Combined variogram and SADIE showed strong evidence of spatial aggregation of H. postica larval population (~95%) while a moderate level of aggregation in the adult population (~67%) of the sampling times analyzed. The average aggregation distances based on the range value of the variogram were 22.3 m and 14.7 m for larvae and adults, respectively. Based on variogram results, populations of natural enemies, coccinellids and Nabis spp. were found spatially aggregated in 57.9% and 5.6% of the sampling times, respectively. SADIE further supported the variogram results as coccinellid populations (52.6% of sampling times) were highly aggregated in contrast with the Nabis spp. populations (5.6% of sampling times) in alfalfa fields. There was no evidence of significant spatial synchrony between H. postica and its predators, coccinellids and Nabis spp. CONCLUSION: Our study was able to determine the spatial and temporal distribution of H. postica and its two natural enemies (coccinellids and nabids) in irrigated alfalfa fields. The possible implications of these findings for integrated pest management (IPM) of alfalfa weevil populations are discussed.

Malaria risk factor assessment is a critical step in determining cost-effective intervention strategies and operational plans in a regional setting. We develop a multi-indicator multistep approach to model the malaria risks at the population level in western Kenya. We used a combination of cross-sectional seasonal malaria infection prevalence, vector density, and cohort surveillance of malaria incidence at the village level to classify villages into malaria risk groups through unsupervised classification. Generalized boosted multinomial logistics regression analysis was performed to determine village-level risk factors using environmental, biological, socioeconomic, and climatic features. Thirty-six villages in western Kenya were first classified into two to five operational groups based on different combinations of malaria risk indicators. Risk assessment indicated that altitude accounted for 45-65% of all importance value relative to all other factors; all other variable importance values were < 6% in all models. After adjusting by altitude, villages were classified into three groups within distinct geographic areas regardless of the combination of risk indicators. Risk analysis based on altitude-adjusted classification indicated that factors related to larval habitat abundance accounted for 63% of all importance value, followed by geographic features related to the ponding effect (17%), vegetation cover or greenness (15%), and the number of bed nets combined with February temperature (5%). These results suggest that altitude is the intrinsic factor in determining malaria transmission risk in western Kenya. Malaria vector larval habitat management, such as habitat reduction and larviciding, may be an important supplement to the current first-line vector control tools in the study area.

Inducing regeneration in injured spinal cord represents one of modern medicine's greatest challenges. Research from a variety of model organisms indicates that Hedgehog (Hh) signaling may be a useful target to drive regeneration. However, the mechanisms of Hh signaling-mediated tissue regeneration remain unclear. Here, we examined Hh signaling during post-amputation tail regeneration in Xenopus laevis larvae. We found that while Smoothened (Smo) activity is essential for proper spinal cord and skeletal muscle regeneration, transcriptional activity of the canonical Hh effector Gli is repressed immediately following amputation, and inhibition of Gli1/2 expression or transcriptional activity has minimal effects on regeneration. In contrast, we demonstrate that protein kinase A is necessary for regeneration of both muscle and spinal cord, in concert with and independent of Smo, respectively, and that its downstream effector CREB is activated in spinal cord following amputation in a Smo-dependent manner. Our findings indicate that non-canonical mechanisms of Hh signaling are necessary for spinal cord and muscle regeneration.

BackgroundAedes (Stegomyia) albopictus (Skuse, 1894) is the main vector of dengue virus in China. The resistance to insecticides is a huge obstacle for the control of this species, and determining its resistance status and mechanisms in China is essential for the implementation of vector management strategies.MethodsWe have investigated the larval and adult resistance status of Ae. albopictus to deltamethrin in eight field populations in China. Mutations at the voltage-gated sodium channel gene, related to the knockdown resistance (kdr) effect, were detected by sequencing of PCR products. The eight field populations were examined for pyrethroid resistance using the World Health Organization standard bioassays, and the association between the mutations and phenotypic resistance was tested.ResultsThe eight field populations of larvae of Ae. albopictus in China exhibited high resistance to deltamethrin; the RR50 values ranged from 12 (ZJ) to 44 (GZ). Adult bioassay revealed that Ae. albopictus populations were resistant to deltamethrin (mortality rate

An extensive network of storm water conveyance systems in urban areas, often referred to as the "underground storm drain system" (USDS), serves as significant production habitats for mosquitoes. Knowledge of whether USDS habitats are suitable for newly introduced dengue vectors Aedes aegypti and Ae. albopictus will help guide surveillance and control efforts. To determine whether the USDS functions as a suitable larval habitat for Culex, Ae. aegypti and Ae. albopictus in southern California, we examined mosquito habitat utilization and larval survivorship using laboratory microcosm studies. The data showed that USDS constituted 4.1% of sampled larval habitats for Ae. aegypti and Ae. albopictus, and 22.0% for Cx. quinquefasciatus. Furthermore, USDS water collected in the summer completely inhibited Aedes larval development, but yielded a 15.0% pupation rate for Cx. quinquefasciatus. Food supplementation in the microcosms suggests that nutrient deficiency, toxins and other factors in the USDS water led to low success or complete failure of larval development. These results suggest that USDS habitats are currently not major productive larval habitats for Aedes mosquitoes in southern California. Our findings prompt inclusion of assessments of pupal productivity in USDS habitats and adult mosquito resting sites in the mosquito surveillance program.

Genetic engineering techniques have contributed to the now widespread use of zebrafish to investigate gene function, but zebrafish-based human disease studies, and particularly for neurological disorders, are limited. Here we used CRISPR-Cas9 to generate 40 single-gene mutant zebrafish lines representing catastrophic childhood epilepsies. We evaluated larval phenotypes using electrophysiological, behavioral, neuro-anatomical, survival and pharmacological assays. Local field potential recordings (LFP) were used to screen ∼3300 larvae. Phenotypes with unprovoked electrographic seizure activity (i.e., epilepsy) were identified in zebrafish lines for 8 genes; ARX, EEF1A, GABRB3, GRIN1, PNPO, SCN1A, STRADA and STXBP1. We also created an open-source database containing sequencing information, survival curves, behavioral profiles and representative electrophysiology data. We offer all zebrafish lines as a resource to the neuroscience community and envision them as a starting point for further functional analysis and/or identification of new therapies.

BackgroundAedes albopictus is one of the most invasive species in the world as well as the important vector for mosquito-borne diseases such as dengue fever, chikungunya fever and zika virus disease. Chemical control of mosquitoes is an effective method to control mosquito-borne diseases, however, the wide and improper application of insecticides for vector control has led to serious resistance problems. At present, there have been many reports on the resistance to pyrethroid insecticides in vector mosquitoes including deltamethrin to Aedes albopictus. However, the fitness cost and vector competence of deltamethrin resistant Aedes albopictus remain unknown. To understand the impact of insecticide resistant mosquito is of great significance for the prevention and control mosquitoes and mosquito-borne diseases.Methodology/principal findingsA laboratory resistant strain (Lab-R) of Aedes albopictus was established by deltamethrin insecticide selecting from the laboratory susceptible strain (Lab-S). The life table between the two strains were comparatively analyzed. The average development time of Lab-R and Lab-S in larvae was 9.7 days and 8.2 days (P < 0.005), and in pupae was 2.0 days and 1.8 days respectively (P > 0.05), indicating that deltamethrin resistance prolongs the larval development time of resistant mosquitoes. The average survival time of resistant adults was significantly shorter than that of susceptible adults, while the body weight of resistant female adults was significantly higher than that of the susceptible females. We also compared the vector competence for dengue virus type-2 (DENV-2) between the two strains via RT-qPCR. Considering the results of infection rate (IR) and virus load, there was no difference between the two strains during the early period of infection (4, 7, 10 day post infection (dpi)). However, in the later period of infection (14 dpi), IR and virus load in heads, salivary glands and ovaries of the resistant mosquitoes were significantly lower than those of the susceptible strain (IR of heads, salivary glands and ovaries: P < 0.05; virus load in heads and salivary glands: P < 0.05; virus load in ovaries: P < 0.001). And then, fourteen days after the DENV-2-infectious blood meal, females of the susceptible and resistant strains were allow to bite 5-day-old suckling mice. Both stains of mosquito can transmit DENV-2 to mice, but the onset of viremia was later in the mice biting by resistant group as well as lower virus copies in serum and brains, suggesting that the horizontal transmission of the resistant strain is lower than the susceptible strain. Meanwhile, we also detected IR of egg pools of the two strains on 14 dpi and found that the resistant strain were less capable of vertical transmission than susceptible mosquitoes. In addition, the average survival time of the resistant females infected with DENV-2 was 16 days, which was the shortest among the four groups of female mosquitoes, suggesting that deltamethrin resistance would shorten the life span of female Aedes albopictus infected with DENV-2.Conclusions/significanceAs Aedes albopictus developing high resistance to deltamethrin, the resistance prolonged the growth and development of larvae, shorten the life span of adults, as well as reduced the vector competence of resistant Aedes albopictus for DENV-2. It can be concluded that the resistance to deltamethrin in Aedes albopictus is a double-edged sword, which not only endow the mosquito survive under the pressure of insecticide, but also increase the fitness cost and decrease its vector competence. However, Aedes albopictus resistant to deltamethrin can still complete the external incubation period and transmit dengue virus, which remains a potential vector for dengue virus transmission and becomes a threat to public health. Therefore, we should pay high attention for the problem of insecticide resistance so that to better prevent and control mosquito-borne diseases.