Light induces an increasing release of benzyl nitrile against diurnal herbivore Ectropis grisescens Warren attack in tea (Camellia sinensis) plants.

Herbivore-induced plant volatiles (HIPVs) are critical compounds that directly or indirectly regulate the tritrophic interactions among herbivores, natural enemies and plants. The synthesis and release of HIPVs are regulated by many biotic and abiotic factors. However, the mechanism by which multiple factors synergistically affect HIPVs release remains unclear. Tea plant (Camellia sinensis) is the object of this study because of its rich and varied volatile metabolites. In this study, benzyl nitrile was released from herbivore-attacked tea plants more in the daytime than at night, which was consistent with the feeding behaviour of tea geometrid (Ectropis grisescens Warren) larvae. The Y-tube olfactometer assay and insect resistance analysis revealed that benzyl nitrile can repel tea geometrid larvae and inhibit their growth. On the basis of enzyme activities in transiently transformed Nicotiana benthamiana plants, CsCYP79 was identified as a crucial regulator in the benzyl nitrile biosynthetic pathway. Light signalling-related transcription factor CsPIF1-like and the jasmonic acid (JA) signalling-related transcription factor CsMYC2 serve as the activator of CsCYP79 under light and damage conditions. Our study revealed that light (abiotic factor) and herbivore-induced damage (biotic stress) synergistically regulate the synthesis and release of benzyl nitrile to protect plants from diurnal herbivorous tea geometrid larvae.

Lack of vitamin B12 impairs innate and adaptive immunity of Cuban tree frog (Osteopilus septentrionalis) tadpoles.

Vitamin B12 is a micronutrient required by a variety of organisms for healthy cellular functioning. Despite the systemic effects observed in cases of B12 deficiency, relatively little is known about how vitamin B12 affects immune health, especially in amphibians, which are declining at unprecedented rates. In this study, we tested how supplementing an algae diet with B12 affects the innate and adaptive immunity of Cuban tree frog (Osteopilus septentrionalis) tadpoles. We found that innate immunity, as measured by a bacterial killing assay, was significantly more robust in B12-supplemented tadpoles than control tadpoles, but no significant differences were found in natural antibody production or hematocrit between groups. Adaptive immunity, as measured by Aeromonas hydrophila-specific IgY antibodies, was significantly greater in tadpoles challenged with A. hydrophila and supplemented with B12 than in control tadpoles, those only challenged with A. hydrophila, and those only given B12. Our results suggest that vitamin B12 is an important factor in maintaining a functional immune system in tadpoles, which may also be true for all vertebrates.

A single oscillating proto-hypothalamic neuron gates taxis behavior in the primitive chordate Ciona.

Ciona larvae display a number of behaviors, including negative phototaxis. In negative phototaxis, the larvae first perform short spontaneous rhythmic casting swims. As larvae are cast in a light field, their photoreceptors are directionally shaded by an associated pigment cell, providing a phototactic cue. This then evokes an extended negative taxis swim. We report here that the larval forebrain of Ciona has a previously uncharacterized single slow-oscillating inhibitory neuron (neuron cor-assBVIN78) that projects to the midbrain, where it targets key interneurons of the phototaxis circuit known as the photoreceptor relay neurons. The anatomical location, gene expression, and oscillation of cor-assBVIN78 suggest homology to oscillating neurons of the vertebrate hypothalamus. Ablation of cor-assBVIN78 results in larvae showing extended phototaxis-like swims, even in the absence of phototactic cues. These results indicate that cor-assBVIN78 has a gating activity on phototaxis by projecting temporally oscillating inhibition to the photoreceptor relay neurons. However, in intact larvae, the frequency of cor-assBVIN78 oscillation does not match that of the rhythmic spontaneous swims, indicating that the troughs in oscillations do not themselves initiate swims but rather that cor-assBVIN78 may modulate the phototaxis circuit by filtering out low-level inputs while restricting them temporally to the troughs in inhibition.

Volatile-Mediated Signalling Between Potato Plants in Response to Insect Herbivory is not Contingent on Soil Nutrients.

Plant-plant signalling via volatile organic compounds (VOCs) has been studied intensively, but its contingency on abiotic conditions (e.g., soil nutrients, drought, warming) is poorly understood. To address this gap, we carried out a greenhouse experiment testing whether soil nutrients influenced signalling between potato (Solanum tuberosum) plants in response to insect leaf herbivory by the generalist caterpillar Spodoptera exigua. We placed pairs of plants in plastic cages, where one plant acted as a VOC emitter and the other as a receiver. We factorially manipulated soil nutrients for both emitter and receiver plants, namely: unfertilized (baseline soil nutrients) vs. fertilized (augmented nutrients). Then, to test for signalling effects, half of the emitters within each fertilization level were damaged by S. exigua larvae and the other half remained undamaged. Three days after placing larvae, we collected VOCs from emitter plants to test for herbivory and fertilization effects on VOC emissions and placed S. exigua larvae on receivers to test for signalling effects on leaf consumption and larval mass gain as proxies of induced resistance. We found that herbivory increased total VOC emissions and altered VOC composition by emitter plants, but these effects were not contingent on fertilization. In addition, bioassay results showed that receivers exposed to VOCs from herbivore-damaged emitters had lower levels of herbivory compared to receivers exposed to undamaged emitters. However, and consistent with VOC results, fertilization did not influence herbivore-induced signalling effects on receiver resistance to herbivory. In sum, we found evidence of S. exigua-induced signalling effects on resistance to herbivory in potato plants but such effects were not affected by increased soil nutrients. These results call for further work testing signalling effects under broader range of nutrient concentration levels (including nutrient limitation), teasing apart the effects of specific nutrients, and incorporating other abiotic factors likely to interact or covary with soil nutrients.

Consequences of climate-induced range expansions on multiple ecosystem functions.

Climate-driven species range shifts and expansions are changing community composition, yet the functional consequences in natural systems are mostly unknown. By combining a 30-year survey of subalpine pond larval caddisfly assemblages with species-specific functional traits (nitrogen and phosphorus excretion, and detritus processing rates), we tested how three upslope range expansions affected species' relative contributions to caddisfly-driven nutrient supply and detritus processing. A subdominant resident species (Ag. deflata) consistently made large relative contributions to caddisfly-driven nitrogen supply throughout all range expansions, thus "regulating" the caddisfly-driven nitrogen supply. Whereas, phosphorus supply and detritus processing were regulated by the dominant resident species (L. externus) until the third range expansion (by N. hostilis). Since the third range expansion, N. hostilis's relative contribution to caddisfly-driven phosphorus supply increased, displacing L. externus's role in regulating caddisfly-driven phosphorus supply. Meanwhile, detritus processing contributions became similar among the dominant resident, subdominant residents, and range expanding species. Total ecosystem process rates did not change throughout any of the range expansions. Thus, shifts in species' relative functional roles may occur before shifts in total ecosystem process rates, and changes in species' functional roles may stabilize processes in ecosystems undergoing change.

Changes in immune responses, gene expression, and life table parameters of Helicoverpa armigera Hübner fed on a diet containing the saponin of tea plant, Camellia sinensis.

Saponins cause mortality in insects by reducing food absorption and movement in the gut, which may be used to exploit the control of insect pests. In the current study, tea seed saponin (TSS) was extracted and then added to the artificial diets of Helicoverpa armigera. Pre-ovipositional period of the TSS-treated individuals increased while longevity and fecundity decreased compared to control. There was a significant reduction of the treated individuals in the life table parameters of TSS-treated Individuals including net reproduction rate (R0 ), intrinsic rate of population increase (r), finite rate of increase (λ), and gross reproduction rate (GRR). Also, we found that saponin suppressed the immune system by reducing the total hemocyte count, immune-related gene expression, and phenoloxidase activity. Our results demonstrated a lower expression of cecropin gene in the treated larvae with TSS while no significant differences were observed in attacin gene. Our results clearly showed that feeding of H. armigera larvae in the diet containing TSS significantly reduced demographic parameters, forced insects to obtain more time to complete one generation, and caused vulnerabilities against pathogens. These discrepancies alleviated nutrient uptake of the larvae and disrupted their feeding and growth. Hence, a proper formulation with a desirable concentration would be prepared and applied in the fields suffering H. armigera damage to monitor insecticidal efficiency of TSS.

Inhibitory effects of Serjania erecta on the development of Chrysodeixis includens.

The soybean looper, Chrysodeixis includens, is a primary soybean pest that reduces crop productivity. This work examined control of C. includens populations with methanolic extract of Serjania erecta, a native Cerrado plant, while minimizing risks to pollinators, natural enemies and the environment. Serjania erecta specimens were collected, identified, and subjected to methanol extraction. Bioassays were performed using newly hatched and second-instar caterpillars and different extract concentrations on the diet surface to obtain IC50 values. Two replicates, containing 10 caterpillars, were established in triplicate. The IC50 values were 4.15 and 6.24 mg of extract mL-1 for first-instar and second-instar caterpillars, respectively. These growth inhibition results informed the extract concentrations assessed in subsequent development inhibition assays, in which the pupal weight was higher under the control than under the treatments. Extract treatments increased the duration of the larval, pupal and total development. The potential of different concentrations of S. erecta extract to inhibit the enzymes carboxylesterases was also evaluated. Carboxylesterases activity decreased by 41.96 and 43.43% at 7.8 and 15.6 µg mL-1 extract, respectively. At 31.3 µg mL-1 extract, enzymatic activity was not detected. Overall, S. erecta leaf methanolic extract showed inhibitory potential against carboxylesterases.

Zebrafish Larvae Behavior Models as a Tool for Drug Screenings and Pre-Clinical Trials: A Review.

To discover new molecules or review the biological activity and toxicity of therapeutic substances, drug development, and research relies on robust biological systems to obtain reliable results. Phenotype-based screenings can transpose the organism's compensatory pathways by adopting multi-target strategies for treating complex diseases, and zebrafish emerged as an important model for biomedical research and drug screenings. Zebrafish's clear correlation between neuro-anatomical and physiological features and behavior is very similar to that verified in mammals, enabling the construction of reliable and relevant experimental models for neurological disorders research. Zebrafish presents highly conserved physiological pathways that are found in higher vertebrates, including mammals, along with a robust behavioral repertoire. Moreover, it is very sensitive to pharmacological/environmental manipulations, and these behavioral phenotypes are detected in both larvae and adults. These advantages align with the 3Rs concept and qualify the zebrafish as a powerful tool for drug screenings and pre-clinical trials. This review highlights important behavioral domains studied in zebrafish larvae and their neurotransmitter systems and summarizes currently used techniques to evaluate and quantify zebrafish larvae behavior in laboratory studies.

Silencing of multiple target genes via ingestion of dsRNA and PMRi affects development and survival in Helicoverpa armigera.

RNA interference (RNAi) triggered by exogenous double-stranded RNA (dsRNA) is a powerful tool to knockdown genetic targets crucial for the growth and development of agriculturally important insect pests. Helicoverpa armigera is a pest feeding on more than 30 economically important crops worldwide and a major threat. Resistance to insecticides and Bt toxins has been gradually increasing in the field. RNAi-mediated knockdown of H. armigera genes by producing dsRNAs homologous to genetic targets in bacteria and plants has a high potential for insect management to decrease agricultural loss. The acetylcholinesterase (AChE), ecdysone receptor (EcR) and v-ATPase-A (vAA) genes were selected as genetic targets. Fragments comprising a coding sequence of < 500 bp were cloned into the L4440 vector for dsRNA production in bacteria and in a TRV-VIGS vector in antisense orientation for transient expression of dsRNA in Solanum tuberosum leaves. After ingesting bacterial-expressed dsRNA, the mRNA levels of the target genes were significantly reduced, leading to mortality and abnormal development in larva of H. armigera. Furthermore, the S. tuberosum plants transformed with TRV-VIGS expressing AChE exhibited higher mortality > 68% than the control plants 17%, recorded ten days post-feeding and significant resistance in transgenic (transient) plants was observed. Moreover, larval lethality and molting defects were observed in larva fed on potato plants expressing dsRNA specific to EcR. Analysis of transcript levels by quantitative RT-PCR revealed that larval mortality was attributable to the knockdown of genetic targets by RNAi. The results demonstrated that down-regulation of H. armigera genes involved in ATP hydrolysis, transcriptional stimulation of development genes and neural conduction has aptitude as a bioinsecticide to control H. armigera population sizes and therefore decreases crop loss.

Foliar supplementation of ascorbic acid modulates biochemical performance of silkworm, Bombyx mori under thermal stress.

Dietary supplementation of ascorbic acid was found to be effective in modifying the composition of essential biomolecules. A relative investigation on effects of exogenous dietary supplementation of 0.2% ascorbic acid on the fifth instar larvae of silkworm, Bombyx mori exposed to a high thermal stress of range 40 ± 2 °C was carried out in the lab-set conditions. The observed elevation in various biomolecules, viz., DNA, RNA, protein, lipids, and carbohydrates were quantified in both the thermal stress-induced test groups and in the control, set aside. The test results so obtained were proven to be statistically significant. The present study reveals that foliar supplementation of ascorbic acid has been effective in positively-modulating the biochemical performance in larvae exposed to thermal stress. Moreover, the study also uncovers the possibilities of ascorbic acid as a potential candidate, capable of facilitating the production of good quality cocoons, from larvae exposed to thermal stress.

Metabolic responses to crude oil during early life stages reveal critical developmental windows in the zebrafish (Danio rerio).

Morphological effects of crude oil exposure on early development in fishes have been well documented, but crude oil's metabolic effects and when in early development these effects might be most prominent remains unclear. We hypothesized that zebrafish (Danio rerio) exposed to crude oil as a high energy water accommodated fraction (HEWAF) would show increased routine oxygen consumption (MO2) and critical oxygen tension (PCrit) and this effect would be dependent upon day of HEWAF exposure, revealing critical windows of development for exposure effects. Zebrafish were exposed to 0%, 10%, 25%, 50% or 100% HEWAF for 24 h during one of the first six days post-fertilization (dpf). Survival rate, body mass, routine MO2, and PCrit were then measured at 7 dpf. Survival rate and especially body mass were both decreased based on both exposure concentration and day of crude oil exposure, with the largest decrease when HEWAF exposure occurred at 3 dpf. HEWAF effects on routine MO2 also differed depending upon exposure day. The largest effect occurred at 3 dpf, when MO2 increased significantly by ~60% from 10.1 ± 0.8 µmol O2/g/h compared to control group value of 6.3 ± 0.4 µmol O2/g/h. No significant effects of HEWAF exposure on any day were evident for PCrit (85 ± 4 mmHg in the control population). Overall, the main effects on body mass and MO2 measured at 7 dpf occurred when HEWAF exposures occurred at ~3 dpf. This critical window for metabolism in zebrafish larvae coincides with time of hatching, which may represent an especially vulnerable period in development.

Potato plant variety affects the performance and oviposition preference of Phthorimaea operculella Zeller (Lepidoptera: Gelechiidae).

BACKGROUND: Damage by the potato tuber moth Phthorimaea operculella is one of the major constraints to commercial production of potato in many areas of the world. To promote effective pest management practices for P. operculella based on host plant, larval and adult performance of P. operculella fed on Lishu 6, Hezuo 88, Yunshu 304, and Qingshu 9 potato varieties was compared by examining their survival rate, larval feeding, pupal weight, and oviposition preference. RESULTS: Compared with larvae fed on the other three potato plants, those fed on Lishu 6 exhibited the highest survival rate, with almost 61.67% developing to the adult stage. Females also preferred to lay their eggs on Lishu 6 over Hezuo 88, Yunshu 304 and Qingshu 9; and the weight of P. operculella pupa on Lishu 6 plant (0.0085 g) was significantly heavier than that of on others, especially on Qingshu 9 (0.0062 g). Moreover, first instar larvae fed on Lishu 6 showed host preference to Qingshu 9. CONCLUSION: This study demonstrated that Lishu 6 is susceptible to P. operculella, and Qingshu 9 is not relatively susceptible to P. operculella, which suggested that the P. operculella feeding responses to dominant potato varieties in China is different. This variation can be applied for the potato breeding and pest management practice. © 2021 Society of Chemical Industry.

A positive association of larval therapy and hyperbaric oxygen therapy in veterinary wound care.

The treatment of cutaneous wounds is part of the veterinary routine from initial scientific reports due to being regularly present condition. Currently, several types of treatments are available to accelerate the healing process. This report presents the case of a dog with multiple lesions in the thoracic limbs resulting from a car accident, who underwent larval therapy and hyperbaric oxygen therapy (HBOT). The animal was a 2-year-old female mixed breed dog presenting severe skin degloving, fracture in the left thoracic limb (LTL), with abrasion lesions and dislocation in the right thoracic limb (RTL). The animal underwent multiple modality therapies, such as HBOT sessions associated with larval therapy; even after the LTL presented gangrene, this treatment resulted in optimal viability of the non-necrotic tissue adjacent to the gangrene. Due to chronic pain unresponsive to drug control and the presence of a fracture at a location where a possible exoprosthesis was supposed to be fixed, the LTL ended up being amputated. There are several reports of the use of HBOT or larval therapy in traumatized limbs; however, the combination of both therapies has not been previously described in the veterinary literature. Thus, we demonstrate through this report that it was possible to quickly recover the animal with good wound resolution through tissue oxygenation and a healthy granulation bed, both provided by the therapeutic combination.

Taste sensing and sugar detection mechanisms in Drosophila larval primary taste center.

Despite the small number of gustatory sense neurons, Drosophila larvae are able to sense a wide range of chemicals. Although evidence for taste multimodality has been provided in single neurons, an overview of gustatory responses at the periphery is missing and hereby we explore whole-organ calcium imaging of the external taste center. We find that neurons can be activated by different combinations of taste modalities, including opposite hedonic valence and identify distinct temporal dynamics of response. Although sweet sensing has not been fully characterized so far in the external larval gustatory organ, we recorded responses elicited by sugar. Previous findings established that larval sugar sensing relies on the Gr43a pharyngeal receptor, but the question remains if external neurons contribute to this taste. Here, we postulate that external and internal gustation use distinct and complementary mechanisms in sugar sensing and we identify external sucrose sensing neurons.

Analysis of chemical compositions and larvicidal activity of nut extracts from Areca catechu Linn against Aedes (Diptera: Culicidae).

BACKGROUND: There is a growing need to use green alternative larvicidal control for Aedes larvae compared to chemical insecticides. Substantial reliance on chemical insecticides caused insecticide resistance in mosquito populations. Thus, research for alternate chemical compounds from natural products is necessary to control Aedes larvae. This study explores the analysis of chemical compositions from Areca catechu nut as a potential larvicide for Aedes (Diptera: Culicidae). METHODS: The Areca catechu nut collected from Ipoh, Perak, Malaysia was grounded into powder and used for Soxhlet extraction. The chemical analysis of the extracts and their structures were identified using the GCMS-QP2010 Ultra (Shimadzu) system. National Institute of Standards and Technology (NIST) Chemistry WebBook, Standard Reference Database 69 (https://webbook.nist.gov/chemistry/) and PubChem (https://pubchem.ncbi.nlm.nih.gov/), the two databases used to retrieve the synonyms, molecular formula, molecular weight, and 2-dimensional (2D) structure of chemical compounds. Next, following WHO procedures for larval bioassays, the extracts were used to asses larvicidal activity against early 4th instar larvae of Aedes aegypti and Aedes albopictus. RESULTS: The larvicidal activities were observed against early 4th stage larvae with different concentrations in the range from 200 mg/L to 1600 mg/L. The LC50 and LC95 of Aedes aegypti were 621 mg/L and 2264 mg/L respectively; whereas the LC50 and LC95 of Aedes albopictus were 636 mg/L and 2268 mg/L respectively. Mortality was not observed in the non-target organism test. The analysis using gas chromatography and mass spectrometer recovered several chemical compounds such as Arecaidine, Dodecanoic acid, Methyl tetradecanoate, Tetradecanoic acid , and n-Hexadecanoic acid bioactive components. These chemical constituents were used as additive formulations in pesticides, pest control, insect repellent, and insecticidal agents. CONCLUSIONS: Our study showed significant outcomes from the extract of Areca catechu nut and it deserves further investigation in relation to chemical components and larvicidal actions between different species of Aedes mosquitoes. Even though all these findings are fundamental, it may have some interesting potentials to be developed as natural bio-larvicidal products.

Identification and field verification of an aggregation pheromone from the white-spotted flower chafer, Protaetia brevitarsis Lewis (Coleoptera: Scarabaeidae).

The white-spotted flower chafer (WSFC), Protaetia brevitarsis Lewis, is native to East Asia. Although their larvae are considered a potential resource insect for degrading plant residues, producing protein fodder, and processing to traditional medicine, adult WSFCs inflict damage to dozens of fruit and economic crops. The control of the WSFC still relies heavily on pesticides and the inefficient manual extraction of adults. Here, we report the identification and evaluation of the aggregation pheromone of WSFCs. From the headspace volatiles emitted from WSFC adults, anisole, 4-methylanisole, 2-heptanone and 2-nonanone were identified as WSFC-specific components. However, only anisole and 4-methylanisole elicited positive dose-response relationship in electroantennography tests, and only 4-methylanisole significantly attracted WSFCs of both sexes in olfactometer bioassays and field experiments. These results concluded that 4-methylanisole is the aggregation pheromone of WSFCs. Furthermore, we developed polyethylene vials as long-term dispensers of 4-methylanisole to attract and kill WSFCs. The polyethylene vial lures could effectively attracted WSFCs for more than four weeks. Pheromone-based lures can be developed as an environmentally friendly protocol for monitoring and controlling WSFC adults.

The effects of dietary saturated fat source on weight gain and adiposity are influenced by both sex and total dietary lipid intake in zebrafish.

The effects of saturated fat intake on obesity and cardiovascular health remain inconclusive, likely due in part to their varied nature and interactions with other nutrients. Investigating the synergistic effects of different saturated fat sources with other dietary lipid components will help establish more accurate nutritional guidelines for dietary fat intake. Over the past two decades, zebrafish (Danio rerio) have been established as an attractive model system to address questions regarding contributions of dietary lipid intake to diet-induced obesity in humans. The goal of the present study was to assess interactions of three different saturated fat sources (milk fat, palm oil, and coconut oil) with sex and total dietary lipid intake on weight gain and body composition in adult zebrafish. Larvae were raised on live feeds until 28 days post fertilization, and then fed a formulated maintenance diet until three months of age. An eight-week feeding trial was then initiated, in which zebrafish were fed nine experimental low- and high-fat diets varying in saturated fatty acid and long-chain polyunsaturated fatty acid content, in addition to a low-fat and high-fat control diet. At termination of the feeding trial, each treatment was evaluated according to body mass, moisture content, and adiposity. Sex and diet significantly interacted in their effects on body mass (P = 0.026), moisture content (P = 0.044), and adiposity (P = 0.035). The influence of saturated fat source on body mass was observed to be dependent on intake of total dietary lipid. In females, all three saturated fat sources had similar effects on adiposity. From these observations, we hypothesize that impacts of saturated fat intake on energy allocation and obesity-related phenotypes are influenced by both sex and intake of other dietary lipid components. Our results suggest that current nutritional guidelines for saturated fat intake may need to be re-evaluated and take sex-specific recommendations into consideration.

Establishment of a Drug Screening Model for Cardiac Complications of Acute Renal Failure.

Acute renal failure (ARF) is a clinical critical syndrome with rapid and severe decline of renal function. Complications of ARF, especially its cardiac complications (cardiorenal syndrome type 3, CRS-3), are the main causes of death in patients with ARF. However, the shortage and limited efficacy of therapeutic drugs make it significant to establish new large-scale drug screening models. Based on the Nitroreductase/Metronidazole (NTR/MTZ) cell ablation system, we constructed a Tg(cdh17:Dendra2-NTR) transgenic zebrafish line, which can specifically ablate renal tubular epithelial cells. The absence of renal tubular epithelial cells can lead to ARF in zebrafish larvae. The ARF symptoms, such as heart enlargement, slow heart rate and blood stasis, are similar to the clinical manifestations of human CRS-3. Furthermore, two therapeutic drugs (digoxin and enalapril) commonly used in the clinical treatment of heart failure were also effective in alleviating the symptoms of CRS-3 in zebrafish, which proved the effectiveness of this model. Drug screening further discovered a potential drug candidate, α-lipoic acid, which can effectively alleviate the symptoms of CRS-3 through its antioxidant function. Accordingly, we established a new ARF model of zebrafish, which laid a foundation for large-scale screening of new therapeutic drugs for its complications.

CNS Hypomyelination Disrupts Axonal Conduction and Behavior in Larval Zebrafish.

Myelination is essential for central nervous system (CNS) formation, health and function. As a model organism, larval zebrafish have been extensively employed to investigate the molecular and cellular basis of CNS myelination, because of their genetic tractability and suitability for non-invasive live cell imaging. However, it has not been assessed to what extent CNS myelination affects neural circuit function in zebrafish larvae, prohibiting the integration of molecular and cellular analyses of myelination with concomitant network maturation. To test whether larval zebrafish might serve as a suitable platform with which to study the effects of CNS myelination and its dysregulation on circuit function, we generated zebrafish myelin regulatory factor (myrf) mutants with CNS-specific hypomyelination and investigated how this affected their axonal conduction properties and behavior. We found that myrf mutant larvae exhibited increased latency to perform startle responses following defined acoustic stimuli. Furthermore, we found that hypomyelinated animals often selected an impaired response to acoustic stimuli, exhibiting a bias toward reorientation behavior instead of the stimulus-appropriate startle response. To begin to study how myelination affected the underlying circuitry, we established electrophysiological protocols to assess various conduction properties along single axons. We found that the hypomyelinated myrf mutants exhibited reduced action potential conduction velocity and an impaired ability to sustain high-frequency action potential firing. This study indicates that larval zebrafish can be used to bridge molecular and cellular investigation of CNS myelination with multiscale assessment of neural circuit function.SIGNIFICANCE STATEMENT Myelination of CNS axons is essential for their health and function, and it is now clear that myelination is a dynamic life-long process subject to modulation by neuronal activity. However, it remains unclear precisely how changes to myelination affects animal behavior and underlying action potential conduction along axons in intact neural circuits. In recent years, zebrafish have been employed to study cellular and molecular mechanisms of myelination, because of their relatively simple, optically transparent, experimentally tractable vertebrate nervous system. Here we find that changes to myelination alter the behavior of young zebrafish and action potential conduction along individual axons, providing a platform to integrate molecular, cellular, and circuit level analyses of myelination using this model.

Herbivore-induced volatiles influence moth preference by increasing the ß-Ocimene emission of neighbouring tea plants.

Herbivore-induced plant volatiles prime neighbouring plants to respond more strongly to subsequent attacks. However, the key volatiles that trigger this state and their priming mechanisms remain largely unknown. The tea geometrid Ectropis obliqua is one of the most devastating leaf-feeding pests of tea plants. Here, plant-plant communication experiments demonstrated that volatiles emitted from tea plants infested by E. obliqua larvae triggered neighbouring plants to release volatiles that repel E. obliqua adult, especially mated females. Volatile analyses revealed that the quantity of eight volatiles increased dramatically when plants were exposed to volatiles emitted by infested tea plants, including (Z)-3-hexenol, linalool, α-farnesene, ß-Ocimene and (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT). The results of behavioural bioassays demonstrated that ß-Ocimene strongly repelled mated E. obliqua females. Individual volatile compound exposure experiments revealed that (Z)-3-hexenol, linalool, α-farnesene and DMNT triggered the emission of ß-Ocimene from tea plants. Chemical inhibition experiments demonstrated that the emission of ß-Ocimene induced by (Z)-3-hexenol, linalool, α-farnesene and DMNT were dependent on Ca2+ and JA signalling. These findings help us to understand how E. obliqua moths respond to volatiles emitted from tea plants and provide new insight into volatile-mediated plant-plant interactions. They have potential significance for the development of novel insect and pest control strategies in crops.