Roxithromycin exposure induces motoneuron malformation and behavioral deficits of zebrafish by interfering with the differentiation of motor neuron progenitor cells.

Roxithromycin (ROX), a commonly used macrolide antibiotic, is extensively employed in human medicine and livestock industries. Due to its structural stability and resistance to biological degradation, ROX persists as a resilient environmental contaminant, detectable in aquatic ecosystems and food products. However, our understanding of the potential health risks to humans from continuous ROX exposure remains limited. In this study, we used the zebrafish as a vertebrate model to explore the potential developmental toxicity of early ROX exposure, particularly focusing on its effects on locomotor functionality and CaP motoneuron development. Early exposure to ROX induces marked developmental toxicity in zebrafish embryos, significantly reducing hatching rates (n=100), body lengths (n=100), and increased malformation rates (n=100). The zebrafish embryos treated with a corresponding volume of DMSO (0.1%, v/v) served as vehicle controls (veh). Moreover, ROX exposure adversely affected the locomotive capacity of zebrafish embryos, and observations in transgenic zebrafish Tg(hb9:eGFP) revealed axonal loss in motor neurons, evident through reduced or irregular axonal lengths (n=80). Concurrently, abnormal apoptosis in ROX-exposed zebrafish embryos intensified alongside the upregulation of apoptosis-related genes (bax, bcl2, caspase-3a). Single-cell sequencing further disclosed substantial effects of ROX on genes involved in the differentiation of motor neuron progenitor cells (ngn1, olig2), axon development (cd82a, mbpa, plp1b, sema5a), and neuroimmunity (aplnrb, aplnra) in zebrafish larvae (n=30). Furthermore, the CaP motor neuron defects and behavioral deficits induced by ROX can be rescued by administering ngn1 agonist (n=80). In summary, ROX exposure leads to early-life abnormalities in zebrafish motor neurons and locomotor behavior by hindering the differentiation of motor neuron progenitor cells and inducing abnormal apoptosis.

LET-381/FoxF and its target UNC-30/Pitx2 specify and maintain the molecular identity of C. elegans mesodermal glia that regulate motor behavior.

While most glial cell types in the central nervous system (CNS) arise from neuroectodermal progenitors, some, like microglia, are mesodermally derived. To understand mesodermal glia development and function, we investigated C. elegans GLR glia, which envelop the brain neuropil and separate it from the circulatory system cavity. Transcriptome analysis shows that GLR glia combine astrocytic and endothelial characteristics, which are relegated to separate cell types in vertebrates. Combined fate acquisition is orchestrated by LET-381/FoxF, a fate-specification/maintenance transcription factor also expressed in glia and endothelia of other animals. Among LET-381/FoxF targets, the UNC-30/Pitx2 transcription factor controls GLR glia morphology and represses alternative mesodermal fates. LET-381 and UNC-30 co-expression in naive cells is sufficient for GLR glia gene expression. GLR glia inactivation by ablation or let-381 mutation disrupts locomotory behavior and promotes salt-induced paralysis, suggesting brain-neuropil activity dysregulation. Our studies uncover mechanisms of mesodermal glia development and show that like neuronal differentiation, glia differentiation requires autoregulatory terminal selector genes that define and maintain the glial fate.

Bacterial plant pathogens affect the locomotor behavior of the insect vector: a case study of Citrus volkameriana-Triozae erytreae-Candidatus Liberibacter asiaticus system.

Plant pathogens can alter the behavior of their insect vectors as well as their survival and reproduction. The African psyllid, Trioza erytreae, is one of the vectors of Huanglongbing, a citrus disease caused mainly by "Candidatus Liberibacter asiaticus" (CLas). The purpose of this study was to characterize the effects of CLas on the psyllid, T. erytreae using Citrus volkamerina plants as the study system. The study focused more specifically on the CLas effects prior to and after its acquisition by the psyllid T. erytreae. Our results did not support the hypothesis that CLas effects psyllid probing behavior prior to acquisition; few differences were observed between uninfected T. erytrea feeding on CLas-infected versus control plants. On the other hand, compared to psyllids that had completed their development on control plants, the ones that had completed their development on a CLas-infected plant exhibited changes in their behavior (greater velocity), physiology (smaller mass) and biochemistry (lower water and lipid content). Altogether, our results confirm the existence of a marked postacquisition effect on the vector locomotor behavior and a minor preacquisition effect of CLas on the vector behavior, which can be partially explained by physiological and biochemical changes.

Quantitative Trait Locus Determining the Time of Blood Feeding in Culex pipiens (Diptera: Culicidae).

Mosquitoes and other blood feeding arthropods are vectors of pathogens causing serious human diseases, such as Plasmodium spp. (malaria), Wuchereria bancrofti (lymphatic filariasis), Borrelia burgdorferi (Lyme disease), and viruses causing dengue, Zika, West Nile, chikungunya, and yellow fever. Among the most effective strategies for the prevention of vector-borne diseases are those aimed at reducing human-vector interactions, such as insecticide applications and insecticide-treated bed nets (ITNs). In some areas where ITNs are widely used, behavioral adaptations have resulted in mosquitoes shifting their time of blood feeding to earlier or later in the night when the bed nets are not being employed. Little is known about the genetic basis of these behavioral shifts. We conducted quantitative trait locus (QTL) analysis using two strains of Culex pipiens sensu lato with contrasting blood feeding behaviors, wherein the lab adapted Shasta strain blood feeds at any time of the day or night, while the newly established Trinidad strain feeds only at night. We identified a single locus on chromosome 2 associated with the observed variation in feeding times. None of the core clock genes period, timeless, clock, cycle, PAR-domain protein 1, vrille, discs overgrown, cryptochrome 1, or cryptochrome 2 were located within the QTL region. We then monitored locomotor behavior to determine if they differed in their flight activity. The highly nocturnal Trinidad strain showed little daytime activity while the day-feeding Shasta strain was active during the day, suggesting blood feeding behavior and flight activity are physiologically linked.

Acute toxicity of broflanilide on neurosecretory system and locomotory behavior of zebrafish (Danio rerio).

Broflanilide, a novel meta-diamide insecticide, possesses moderate acute toxicity to zebrafish, with a 96-h median lethal concentration (96-LC50) of 0.76 mg/L. However, its effect on fish behavior and the underlying mechanisms are still unclear. The present study evaluated the effects of broflanilide on the zebrafish brain over a 96-h exposure by comparing the histopathological changes and relative expression of targeted genes with the behavioral metrics. The results of the toxicity test showed that broflanilide could cause deformities, such as deformation of the operculum and spinal curvature, at 0.6, 0.82 and 1.15 mg/L. Results also showed tissue damage and apoptosis in the cerebellum under 0.27 and 0.6 mg/L exposure. Additionally, broflanilide affected the neurotransmitters, metabolites and transcripts of genes associated with dopamine, gamma-aminobutyric acid expression. and the signaling pathways in zebrafish brains at 0.60 mg/L after 1 h and 96 h of exposure, while the levels of glutamate, glutamate decarboxylase, GABA transaminase, nicotinamide adenine dinucleotide (NADH) and adenosine triphosphate (ATP) were also inhibited at 0.27 mg/L after 96 h of exposure. The accumulated swimming distance was significantly longer and the average speed was significantly faster than the control at 0.27 and 0.6 mg/L after 1-h of exposure, while these metrics were lowered at 0.6 mg/L after 96 h of exposure. The study results demonstrates that broflanilide affects the zebrafish brain, neurotransmitters and associated fish behaviors. This study also provides deeper insight into the mechanistic understanding of the effects of broflanilide on the zebrafish brain.

Behavioral and ultrastructural effects of novaluron on Aedes aegypti larvae.

Chitin synthesis inhibitors (CSI) are supposed to inhibit formation of chitin microfibrils in newly synthesized cuticle during molting process. Conversely, there has been comparatively few data on morphological effects of CSI on non-target insect organs. In this work, the effects of the CSI novaluron on behavior and midgut of A. aegypti were evaluated. Toxicity bioassays revealed that novaluron is toxic to A. aegypti larva with LC50 = 18.57 mg L-1 when exposed in aqueous solution for 24 h. Novaluron treated larvae were less active and spent more time resting compared to the control group. Histopathology showed that midguts of novaluron-treated larvae had cytoplasm vacuolization and damaged brush border. Cytotoxic effects in midguts of treated larvae induced necrosis, autophagy and damage to mitochondria. Despite being chitin synthesis inhibitor, novaluron did not induce alterations in the integument of A. aegypti larvae. Fluorescence microscopy revealed that the number of digestive cells were higher in novaluron-treated larvae than in control, in response to digestive cell apoptosis. The present study highlights the importance of novaluron against A. aegypti larvae by causing injuries to non-target organs, altering behaviors, inducing cell death and inhibiting cell proliferation.

Pyriproxyfen, a juvenile hormone analog, damages midgut cells and interferes with behaviors of Aedes aegypti larvae.

Juvenile hormone analogs (JHA) are known to interfere with growth and biosynthesis of insects with potential for insecticide action. However, there has been comparatively few data on morphological effects of JHA on insect organs. To determine pyriproxyfen effects on Aedes aegypti larvae, we conducted toxicity, behavioral bioassays and assessed ultrastructural effects of pyriproxyfen on midgut cells. A. aegypti larvae were exposed in aqueous solution of pyriproxyfen LC50 concentrations and evaluated for 24 h. This study fulfilled the toxic prevalence of pyriproxyfen to A. aegypti larvae (LC50 = 8.2 mg L-1). Behavioral observations confirmed that pyriproxyfen treatment significantly changes swimming behavior of larvae, limiting its displacement and speed. The pyriproxyfen causes remarkable histopathological and cytotoxic alterations in the midgut of larvae. Histopathological study reveals presence of cytoplasmic vacuolization and damage to brush border of the digestive cells. The main salient lesions of cytotoxic effects are occurrence of cell debris released into the midgut lumen, cytoplasm rich in lipid droplets, autophagosomes, disorganized microvilli and deformed mitochondria. Data suggest that pyriproxyfen can be used to help to control and eradicate this insect vector.

Distress vocalization delay in the neonate lamb as a neurobehavioral assessment tool.

Acoustic features of infant distress vocalizations including latency and rate of emission are used as indices of neurological deficit and integrity in human and rodent neonates. This paper investigates the relationship between temporal characteristics of distress calls, elicited by an isolation stimulus, and indicators of neurobehavioral development over 12 hr postpartum in the neonate lamb. Delayed vocalization initiation was found to be associated with poor locomotor and orientation behavior reflecting the capacity of the lamb to reunite with and follow its dam, and a lowered rate of signal emission following commencement of vocalization. Animals demonstrating delayed vocalization initiation also appeared more likely to be of a birth weight predisposed to fetal distress, and to urinate when exposed to a novel environment. Based on these preliminary studies, we propose that compromised emission of vocal signals is indicative of neurobehavioral deficit in the neonate lamb.

Sublethal Exposure to Clove and Cinnamon Essential Oils Induces Hormetic-Like Responses and Disturbs Behavioral and Respiratory Responses in Sitophilus zeamais (Coleoptera: Curculionidae).

Essential oils have been suggested as suitable alternatives for controlling insect pests. However, the potential adaptive responses elicited in insects for mitigating the actions of these compounds have not received adequate attention. Furthermore, as is widely reported with traditional insecticides, sublethal exposure to essential oils might induce stimulatory responses or contribute to the development of resistance strategies that can compromise the management of insect pests. The current study evaluated the locomotory and respiratory responses as well as the number of larvae per grain produced by the maize weevil, Sitophilus zeamais Motschulsky, after being sublethally exposed to the essential oils of clove, Syzygium aromaticum L., and cinnamon, Cinnamomum zeylanicum L. The essential oils showed similar insecticidal toxicity (exposure route: contact with dried residues; Clove LC95 = 3.96 [2.78-6.75] µl/cm(2); Cinnamon LC95 = 3.47 [2.75-4.73] µl/cm(2)). A stimulatory effect on the median survival time (TL50) was observed when insects were exposed to low concentrations of each oil. Moreover, a higher number of larvae per grain was produced under sublethal exposure to clove essential oil. S. zeamais avoided the treated areas (in free-choice experiments) and altered their mobility when sublethally exposed to both essential oils. The respiratory rates of S. zeamais (i.e., CO2 production) were significantly reduced under low concentrations of the essential oils. We recommend the consideration of the potential sublethal effects elicited by botanical pesticides during the development of integrated pest management programs aiming to control S. zeamais.

The dysregulation of movement and reproductive capacity in Caenorhabditis elegans exposed to Triclosan ;du-ring pregnancy / 中华实用儿科临床杂志

Objective To observe the effect of Triclosan( TCS) exposure on Caenorhabditis elegans( c. ele-gans) F1 generation of locomotory behavior, brood size, and generation time. Methods The trial included a control group and 4 TCS treatment groups with different doses (100 nmol/L,1 μmol/L,10μmol/L,20μmol/L),the exposure time being 24 hours,the effect of c. elegans′head thrashes,body bending frequency,the brood size and generation time was observed. Results (1) The control group exposed to 100 nmol/L,1 μmol/L,10 μmol/L,20 μmol/L TCS,their head thrash frequency of c. elegans F1 was(109. 40±8. 61) times/min,(84. 70±7. 82) times/min,(76. 35±7. 44) times/min,(74. 74±5. 93)times/min,(71. 95±4. 19)times/min,respectively,the head thrash ability of c. elegans was significantly inhibited(F=62. 245,P<0. 01). (2) When the control group was exposed to 100 nmol/L,1 μmol/L,10μmol/L,20 μmol/LTCS,the frequency of c.elegans F1 body bent was (19.94±2.46)times/20 s,(15.13±1.99) times/20 s,(14.63±2.31)times/20 s,(14.69±1.96)times/20 s,(12.00±1.86)times/20 s,respectively,and the comparative differences between groups were statistically significant(F=25. 636,P<0. 01). (3) When the control group was exposed to 0,100 nmol/L,1 μmol/L,10 μmol/L,20 μmol/L TCS,the body sizes of the c. elegans F1 generation was (286.83±6.01)articles,(273.33±6.41)articles,(214.17±7.25)articles,(173.67±9.20)articles, (118. 50 ± 6. 98 ) articles, respectively, the brood size of the C. elegans F1 generation exposed to 100 nmol/L, 1μmol/L,10 μmol/L,20 μmol/L TCS levels,were reduced by 4. 71%,25. 60%,39. 45%,58. 67%,the ge-neration time of the c. elegans′F1 generation was shortened by 2. 14%-5. 38% in the TCS treatment groups compared with the control group(F=27. 520,P<0. 01). Conclusions After c. elegans exposure to TCS,locomotory behavior can be severe-ly affected,reproductive damage causes a decline in the number of brood size,and the speeding-up of the breeding rate is related to the concentration of TCS concentration-response.