Subsequent Feeding Research Articles

Lemongrass essential oil in silage and as a feed additive has limited effect on animals feed intake and rumen fermentation

ABSTRACT This study aimed to evaluate the effects of lemongrass essential oil (LEO) addition during the ensiling and subsequent sheep feed intake, particle selection, in vitro rumen fermentation, total-tract apparent digestibility and nitrogen balance. Eight Dorper lambs 19.4±2.40 (mean±SD) kg of body weight were used in a trial using a 4 × 4 Latin Square design to evaluate: I. LEO addition during the whole-plant sorghum ensiling: 0 (EN−) and 4 (EN+) mL per kg of sorghum dry matter (DM); and II. LEO supply during the animals feeding: 0 (F−) and 1.6 (F+) mL per kg of diet DM. Treatments showed no effect on feed intake and particle size selection. Ensiling with LEO increased ammonia-N when LEO was not added during incubation. LEO addition during incubation decreased neutral detergent fibre (NDF) degradation when LEO was not added during the ensiling. In addition, LEO addition increased fermentation gas production and decreased digestibility. LEO addition in sheep feeding tended to decrease crude protein digestibility. Treatments did not affect nitrogen balance and the average daily gain. Thus, LEO supply during ensiling and sheep feeding does not affect feed intake, particle selection and nitrogen balance.

Impact of dairy cow personality traits and concentrate allowance on their response to training and adaptation to an automated milking system

The objectives of this study were to determine: 1) if dairy cow personality traits and concentrate allowance are associated with the behavior and performance of cows during training to use an automated milking system (AMS); and 2) if these factors were associated with the behavior and performance of cows after AMS training. Twenty-nine mid- to late-lactation Holstein cows (218 ± 49 DIM), who were milking on a rotary parlor and had never previously been milked in an AMS, were enrolled in this study. Cows were assigned to 1 of 2 dietary treatments, consisting of a basal partial mixed ration (PMR) common to both treatment groups, with a concentrate allowance (on dry matter basis) of: 1) 2.0 kg/d in the AMS (L-Tx); or 2) 6.0 kg/d in the AMS (H-Tx). Cows were trained to use the free-traffic AMS, with supervised milkings, over 72 h and were milked in this system for 63 d after training was complete. Variables relating to feeding behavior, milking activity, and production were measured from the start of AMS training until the end of the study. Between 42 and 63 d after AMS introduction, each cow was assessed for personality traits using a combined arena test consisting of exposure to a novel environment, novel object, and novel human. Principal components analysis of behaviors observed during the personality assessment revealed 2 factors (interpreted as boldness and activeness traits) that together explained 85% of the variance; each cow received a score for each trait. Associations between dietary treatment and personality traits with feeding behavior, milking activity, and production were analyzed using mixed-effect linear and logistic regression models. Cows with greater scores for the active trait produced less milk during the 3 d of AMS training compared with cows with lower scores. Within the H-Tx, more active cows had a 3.92 times greater risk of kicking off teat cups during AMS training than less active cows. However, during the 8 wk after training, more active cows had a 1.37 times lesser risk of teat cup kickoffs than those that were less active. Cows on the H-Tx produced 4.4 kg/d more energy-corrected milk compared with cows on the L-Tx in the 8 wk after training. During the 8 wk after AMS training the cows on the H-Tx consumed an average of 21.4 kg/d of PMR and were delivered 4.6 kg/d of AMS concentrate, while the L-Tx cows consumed 23.4 kg/d PMR and were delivered 2.0 kg/d of AMS concentrate. The results indicate that both dairy cow personality traits and AMS concentrate allocation influence their response to AMS training and subsequent feeding and milking behavior and production.

Dynamics of catches and state of stocks the European perch Perca fluviatilis in rivers in the middle Ob basin (in the Tomsk region)

European perch Perca fluviatilis Linnaeus, 1758 — is a mediumsized representative of the Percidae. It distributed in lowland rivers, lakes and artificial reservoirs, as well as in desalinated coastal areas of the seas of Northern Eurasia, with the exception of the Far East and the coast of the Arctic Ocean. This species is numerous almost everywhere. It is one of the main objects of industrial and amateur fishing. In the Middle Ob basin, a significant part of the life cycle of perch is associated with the floodplain system. There is, during the spring flood, its spawning and subsequent feeding of juveniles and producers take place. Therefore, the regulation of the Ob’s flow by the Novosibirsk hydroelectric power station dam served as one of the important factors that had a negative impact on the state of its reserves. Thus, within the Tomsk region, commercial catches of perch before the regulation of the Ob flow (1946–1961) averaged 354 tons per year, and after regulation (during the period of stable fishing pressure, in 1960–1985) — 157 tons. In recent years (2018–2022), the catch of perch has increased slightly and, according to official fisheries statistics, amounts to 211 tons per year, providing 5.9% of the total fish production in the region. Currently, the reserves of perch are in a relatively stable state, the estimated indicators of its biomass in rivers within the Tomsk region in recent years range from 1190.9 to 2277.5 tons, with an average number of 10.6 million pieces. The development of the perch’ reserves is satisfactory, averaging 94.2% of the recommended catch. Amateur fishermen do not have a significant impact on the state of perch stocks.

Eddington Envelopes: The Fate of Stars on Parabolic Orbits Tidally Disrupted by Supermassive Black Holes

Abstract Stars falling too close to massive black holes in the centers of galaxies can be torn apart by the strong tidal forces. Simulating the subsequent feeding of the black hole with disrupted material has proved challenging because of the range of timescales involved. Here we report a set of simulations that capture the relativistic disruption of the star, followed by 1 yr of evolution of the returning debris stream. These reveal the formation of an expanding asymmetric bubble of material extending to hundreds of au—an outflowing Eddington envelope with an optically thick inner region. Such outflows have been hypothesized as the reprocessing layer needed to explain optical/UV emission in tidal disruption events but never produced self-consistently in a simulation. Our model broadly matches the observed light curves with low temperatures, faint luminosities, and line widths of 10,000–20,000 km s−1.

Activation of a Silent Gene Cluster from the Endophytic Fungus Talaromyces sp. Unearths Cryptic Azaphilone Metabolites.

Fungal azaphilones have attracted widespread attention due to their significant potential as sources of food pigments and pharmaceuticals. Genome mining and gene cluster activation represent powerful tools and strategies for discovering novel natural products and bioactive molecules. Here, a putative azaphilone biosynthetic gene cluster lut from the endophytic fungus Talaromyces sp. was identified through genome mining. By overexpressing the pathway-specific transcription factor LutB, five new sclerotiorin-type azaphilones (1, 6, 8, and 10-11) together with seven known analogues (2-5, 7, 9, 12) were successfully produced. Compounds 8 and 9 exhibited antibacterial activity against Bacillus subtilis with MIC values of 64 and 16 μg/mL, respectively. Compound 11 showed cytotoxic activity against HCT116 and GES-1 with IC50 values of 10.9 and 4.9 μM, respectively, while 1, 4, 5, and 7-10 showed no obvious cytotoxic activity. Gene inactivation experiments confirmed the role of the lut cluster in the production of compounds 1-12. Subsequent feeding experiments unveiled the novel functional diversity of the dual megasynthase system. Furthermore, a LutC-LutD binary oxidoreductase system was discovered, and in combination with DFT calculations, the basic biosynthetic pathway of the sclerotiorin-type azaphilones was characterized. This study provided a good example for the discovery of new azaphilones and further uncovered the biosynthesis of these compounds.

Effect of Residual Gastric Volume on Risk of Ventilator-Associated Pneumonia in Adults Receiving Mechanical Ventilation and Early Enteral Feeding

Abstract Background Early enteral nutrition is the standard of care in critically ill patients receiving invasive mechanical ventilation. However, numerous studies have shown that early enteral nutrition is frequently not used. The main reason for nonuse is gastrointestinal intolerance to enteral nutrition which has been ascribed to gastroparesis with increased gastric volume, gastroesophageal reflux, and regurgitation or vomiting carrying a risk of aspiration and ventilator-associated pneumonia. Aim of the Work To test the hypothesis that the risk of ventilator-associated pneumonia is not increased when residual gastric volume is not monitored compared with routine residual gastric volume monitoring in patients receiving invasive mechanical ventilation and early enteral nutrition. Furthermore residual gastric volume monitoring may be associated with decreased calorie delivery and therefore, with underfeeding and increased morbidity. Patients and Methods This is a Prospective cohort study that was conducted at Ain Shams University Hospitals& Rashid General hospital for 6 months on critically ill patients admitted to ICU with mechanical ventilation. Sample sizes of 215 in each group totaling 430 in the study achieve 80% power to detect a non-inferiority margin difference between the group proportions of -0.0800. The reference group proportion is 0.158. The treatment group proportion is assumed to be 0.078 under the null hypothesis of inferiority. Results There was no significant difference between groups regard BMI (is calculated as weight in kilograms divided by height in meters squared), SAPS II or SOFA regard sex distribution the majority were male in both groups with no significant difference and also DM and HTN distributed with no significant difference between groups. Considering cause of admission and risk factors distribution between studied groups, in our study there is no significant difference or association between the two groups and the majority admission causes of both groups were respiratory and cancer. No significant difference between groups regard hospital stay or ICU days but MV days were significantly shorter in intervention group. In our study, Ventilator-Associated Pneumonia was significantly associated with control group as 47.4% had pneumonia while only 11.2% in intervention group had it. In the present study, cumulative calories deficit was significantly lower in intervention group, Intolerance and Prokinetic TTT were significantly associated with control group. Conclusion The current study supports the hypothesis that a protocol of enteral nutrition management without residual gastric volume monitoring is not inferior to a similar protocol including residual gastric volume monitoring in terms of protection against VAP. Residual gastric volume monitoring leads to unnecessary interruptions of enteral nutrition delivery with subsequent inadequate feeding and should be removed from the standard care of critically ill patients receiving invasive mechanical ventilation and early enteral nutrition.

Effect of Fungicide Application and Corn Hybrid Class on the Presence of Fusarium graminearum and the Concentration of Deoxynivalenol in Ear and Stalk Parts of Corn (Zea mays) Used for Silage.

In Wisconsin, the use of brown midrib (BMR) corn (Zea mays) hybrids for ensiling and subsequent feeding to dairy cows is quite common. The overall milk production from cows fed silage from BMR hybrids is typically higher than those fed silage made from dual-purpose hybrids. Gibberella diseases (ear and stalk rot) caused by Gibberella zeae (anamorph; Fusarium graminearum) and the accompanying accumulation of the mycotoxin deoxynivalenol (DON) can be significant issues during the field production of BMR hybrids. The work presented here aimed to understand the role of hybrid class on the distribution of F. graminearum DNA and DON in the ear and stalk parts of corn for silage. An ear and stalk partitioned sample experiment was conducted on silage corn from field trials in Arlington, Wisconsin, in 2020 and 2021. The trials were arranged in a randomized complete block design in both years, including one BMR hybrid, one dual-purpose hybrid, and seven fungicide application regimes. Paired ear and stalk samples were physically separated, dried, and ground at harvest before determining the concentration of F. graminearum DNA and DON in each sample. Across both years, the main effects of hybrid, treatment, and plant part were not significant (P > 0.1) on DON concentration. However, the hybrid-by-plant part interaction effect was significant (P < 0.01). Ears of the BMR hybrid accumulated the most DON, whereas the dual-purpose hybrid ears had the lowest DON concentration. The concentrations of DON and F. graminearum DNA were significantly (P < 0.01) and highly correlated in the ear (r = 0.73) but not in the stalk (r = 0.09, P = 0.33). These findings suggest that DON accumulation in the corn ear is a major contributor in the difference observed in the total DON between the hybrid classes. Therefore, growers and researchers are encouraged to focus production and breeding on hybrids in both classes that accumulate less DON in ears, resulting in lower total DON in corn chopped for silage.

Impact of extrusion temperature and moisture incorporation on nutrient digestibility in barramundi (Lates calcarifer) diet

This study aimed to evaluate the influence of extrusion temperature and moisture incorporation procedure on nutrient digestibility of diets fed to barramundi (Lates calcarifer). A single premix was processed under six contrasted extrusion processing conditions, with extruder barrel temperatures set at 100 °C and 110 °C, and liquid water either incorporated in the preconditioner, in the barrel, or in both. In a subsequent 33-day feeding trial, grow-out fish (758.3 ± 24.5 g) were fed the 6 diets and apparent digestibility coefficients (ADC) were assessed for 42 fatty acids, 17 amino acids, protein, lipids and energy. Digestibility of protein (92.3–93.7%), lipid (84.1–89.4%), and energy (69.4–75.2%) also remained unaffected by extrusion settings (P > 0.05). However, lower extrusion temperature and moisture incorporation in both preconditioner and barrel resulted in higher digestibility of poly-unsaturated fatty acids (PUFA), long-chain poly-unsaturated fatty acids (LC-PUFA), omega-3, omega-6 and 22:6 docosahexaenoic n-3 (DHA). Moreover, lower extrusion temperature significantly improved ADCs of essential amino acids, except lysine, histidine, and threonine (P < 0.05). The results showed no significant impact (P > 0.05) of the tested extrusion parameters on fish growth (TGC: 2.11 ± 0.17), feed intake, or feed conversion performance (FCR: 1.67 ± 0.13). The study unveils diverse responses to extrusion temperature and moisture levels regarding amino acid and fatty acid digestibility. These findings highlight the advantages of preconditioning during the extrusion process to enhance fatty acid digestibility.

Daily feeding frequency affects feed intake and body weight management of growing layers

The objective of this study was to investigate the effect of feeding behavior on feed intake and body weight in growing layers and the underlying mechanisms, thereby providing a scientific foundation for optimal feeding practices in growing layers' management. A total of 144 Hy-line brown growing layers of 10 wk old and similar body weight, were divided into 3 treatment groups with different feeding frequency and equal cumulative daily feeding amount: the once-a-day feeding group (F1) was fed at 9:00 am every day, with feeding amount of 150 g/layer; the twice-a-day feeding group (F2) were fed at 9:00 am and 13:00 pm every day, with each feeding amount of 75 g/layer; the 4 times-a-day feeding group (F4) were fed at 9:00 am, 11:00 am, 13:00 pm, and 15:00 pm every day, with each feeding amount of 37.5 g/layer. Pre-experiment lasted for 1 wk and formal experiment lasted for 8 wk. The results indicated that the daily feed intake and body weight were decreased (P < 0.05) while feed conversion ratio was not affected (P > 0.05) as daily feeding times increased. The glandular stomach proportion was significantly increased in twice-a-day feeding group, while liver proportion and ileum length were significantly increased in 4 times-feeding group (P < 0.05). Additionally, 4 times-feeding daily resulted in a significant elevation of blood glucose levels, which may have suppressed feed intake (P < 0.05). In 4 times-feeding group, the plasma triglyceride levels increased as feeding times, accompanied by a notable up-regulation in the mRNA level of appetite-suppressing gene, hypothalamic pro-opiomelanocortin (POMC) and glandular stomach ghrelin. This modulation effectively suppressed the subsequent feed intake and body weight. Therefore, 4 times feeding daily is recommended in growing layers' management, because it reduced the feed cost without affecting the feed conversion efficiency.

Heavy Metal Bioaccumulation in Rabbit Organs and Chrysomya albiceps (Wiedemann, 1819) Larvae: Implications for Forensic Entomology

Background: A closer relationship has been established between entomology and toxicology, giving rise to a new field known as entomotoxicology, which focuses on the bioaccumulation of toxic substances in scavenging insects and other arthropods. Methods: This study investigates the impact of lethal doses of Mercury Chloride (HgCl2) and Cadmium Chloride (CdCl2) administered to male rabbits (Oryctolagus cuniculus Linnaeus) on the distribution of Mercury and Cadmium in rabbit organs and their subsequent accumulation in Chrysomya albiceps larvae. The experimental groups were subjected to oral administration of specific concentrations of HgCl2 and CdCl2, while a control group received distilled water. Organ dissection and subsequent larval feeding were followed by acid digestion for sample preparation and inductively coupled plasma torch spectrometry coupled with a mass spectrometer (ICP-MS) was employed for analysis. Result: Results indicate a significant increase in Mercury concentrations in treated rabbit organs, with the liver exhibiting the highest concentration. Cadmium showed diverse distribution among rabbit organs, with the highest concentrations in the kidneys. Ch. albiceps larvae, reared on rabbit organs, exhibited varied concentrations of both Mercury and Cadmium, with significantly higher levels in the treated group. These findings underscore the ecological implications of heavy metal exposure and the potential utility of insect larvae in forensic investigations as bioindicators of environmental contamination.

Outcomes of paediatric fundoplication stratified by subtype of neurological impairment

AimsJejunal feeding is increasingly seen as an alternative to fundoplication in neurologically impaired children. However, fundoplication may offer important advantages. This study aimed to determine: (i) contemporary outcomes of fundoplication from a sub-specialised service; and (ii) whether outcomes were influenced by neurological characteristics. MethodsSingle-centre retrospective review of consecutive children undergoing fundoplication by three surgeons over five years (2017–2022) using a standardised technique. Children were stratified as neurologically unimpaired, static brain injury, neuromuscular condition or neurodegenerative impairment. Failure was defined as a requirement for subsequent jejunal feeding or further surgery. Data are presented as median (IQR) unless stated. Comparisons used Fisher's test. Results144 children underwent fundoplication at 1.9 years (1–5 years): 97/144 (67 %) had neurological impairment. Surgery was completed laparoscopically 128/144 (89 %) and converted in 9/137 (7 %). 84/144 (60 %) underwent concomitant gastrostomy formation. At 35 months (22–47), absolute failure was 16 % (23/144). Failure was higher in those with neurodegenerative conditions (not significant). Persistence of symptoms was noted in 23/144 (16 %). Two (1.4 %) required reoperation (<30 days). Nine (6.4 %) required admission to critical care. One death within 30 days was unrelated. ConclusionsGiven fundoplication may provide significant benefits (avoiding pump feeds, frequent tube failure/changes and risk of jejunal perforation), success rates are high and morbidity low, fundoplication should be offered to families as an alternative to jejunal feeding as part of comprehensive counselling. There was no significant difference in outcome between neurological impairment subtypes in this sample size.

The subapical labial sensory organ of spotted lanternfly Lycorma delicatula.

Deciphering how spotted lanternfly (SLF), an invasive polyphagous planthopper in North America, engages with its environment is a pressing issue with fundamental biological significance and economic importance. This interaction primarily depends on olfaction. However, the cellular basis of olfaction in SLF remains elusive. Here we investigate the neuronal and functional organization of the subapical labial sensory organ using scanning electron microscopy and electrophysiological recordings. This organ is believed to supply planthoppers with crucial sensory information that influences their subsequent feeding behaviour. We find in SLF that this organ comprises two identical placoid sensilla, each housing two distinct neurons. The A neuron displays a remarkable sensitivity to changes in airflow speed. Importantly, the same neuron also exhibits robust excitatory responses exclusively to three aldehydes out of a diverse pool of 85 tested odorants and inhibitory responses to 62 other odorants. By contrast, the B neuron solely serves as an olfactory detector, showing strong excitatory responses to 17 odorants and inhibitory responses to only three. The results provide a potential cellular basis for the behavioural responses of SLF to its ecologically relevant stimuli. Our study also identifies new odorants that may be useful for managing this serious pest.

Glycine supplementation can partially restore oxidative stress-associated glutathione deficiency in ageing cats.

Intracellular levels of glutathione, the major mammalian antioxidant, are reported to decline with age in several species. To understand whether ageing affects circulating glutathione levels in cats, blood was sampled from two age groups, < 3 years and > 9 years. Further, to determine whether dietary supplementation with glutathione precursor glycine (GLY) affects glutathione concentrations in senior cats (> 8 years), a series of free GLY inclusion level dry diets were fed. Subsequently, a 16-week GLY feeding study was conducted in senior cats (> 7 years), measuring glutathione, and markers of oxidative stress. Whole blood and erythrocyte total, oxidised and reduced glutathione levels were significantly decreased in senior cats, compared with their younger counterparts (P ≤ 0·02). The inclusion level study identified 1·5 % free GLY for the subsequent dry diet feeding study. Significant increases in erythrocyte total and reduced glutathione were observed between senior cats fed supplemented and control diets at 4 weeks (P ≤ 0·03; maximum difference of 1·23 µM). Oxidative stress markers were also significantly different between groups at 8 (P = 0·004; difference of 0·68 nG/ml in 8-hydroxy-2'-deoxyguanosine) and 12 weeks (P ≤ 0·049; maximum difference of 0·62 nG/mG Cr in F2-isoprostane PGF2α). Senior cats have lower circulating glutathione levels compared with younger cats. Feeding senior cats a complete and balanced dry diet supplemented with 1·5 % free GLY for 12 weeks elevated initial erythrocyte glutathione and altered markers of oxidative stress. Dietary supplementation with free GLY provides a potential opportunity to restore age-associated reduction in glutathione in cats.

Long-Term Effects of Pre-Weaning Individual or Pair Housing of Dairy Heifer Calves on Subsequent Growth and Feed Efficiency.

Our objective in this exploratory study was to evaluate the long-term impacts of pre-weaning social isolation vs. contact on subsequent growth and feed efficiency of Holstein heifers. As pre-weaned calves, 41 heifers were housed individually (n = 15 heifers) or in pairs (n = 13 pairs; 26 heifers). At 18 months of age, heifers were blocked by body weight and randomly assigned to one of three pens within a block (six to eight heifers per pen; six pens total), with original pairs maintained. Body weight (BW), hip height and width, and chest girth were measured at the start and end of the study. Each pen was given 3 days of access to a GreenFeed greenhouse gas emissions monitor to assess potential physiological differences between treatments in enteric methane emissions or behavioral differences in propensity to approach a novel object. During the 9-week study, heifers were fed a common diet containing 62.3% male-sterile corn silage, 36.0% haylage, 0.7% urea, and 1.0% mineral (DM basis). To calculate daily feed intake, as-fed weights and refusals were recorded for individual heifers using Calan gates. Feed samples were collected daily, composited by week, and dried to calculate dry matter intake (DMI). Feed refusal and fecal samples were collected on 3 consecutive days at 3 timepoints, composited by heifer, dried, and analyzed to calculate neutral detergent fiber (NDF), organic matter (OM), and DM digestibility. Feed efficiency was calculated as feed conversion efficiency (FCE; DMI/average daily gain [ADG]) and residual feed intake (RFI; observed DMI-predicted DMI). Paired and individually housed heifers did not differ in DMI, ADG, FCE, or RFI. Although no differences were found in initial or final hip height, hip width, or chest girth, heifers which had been pair-housed maintained a greater BW than individually housed heifers during the trial. Methane production, intensity, and yield were similar between treatments. Pre-weaning paired or individual housing did not impact the number of visits or latency to approach the GreenFeed; approximately 50% of heifers in each treatment visited the GreenFeed within 8 h of exposure. Digestibility of OM, DM, and NDF were also similar between housing treatments. In conclusion, pre-weaning pair housing had no adverse effects on growth, feed efficiency, or methane emissions at 18 to 20 months of age.

The impact of insect egg deposition on Pinus sylvestris transcriptomic and phytohormonal responses to larval herbivory.

Plants can improve their resistance to feeding damage by insects if they have perceived insect egg deposition prior to larval feeding. Molecular analyses of these egg-mediated defence mechanisms have until now focused on angiosperm species. It is unknown how the transcriptome of a gymnosperm species responds to insect eggs and subsequent larval feeding. Scots pine (Pinus sylvestris L.) is known to improve its defences against larvae of the herbivorous sawfly Diprion pini L. if it has previously received sawfly eggs. Here, we analysed the transcriptomic and phytohormonal responses of Scots pine needles to D. pini eggs (E-pine), larval feeding (F-pine) and to both eggs and larval feeding (EF-pine). Pine showed strong transcriptomic responses to sawfly eggs and-as expected-to larval feeding. Many egg-responsive genes were also differentially expressed in response to feeding damage, and these genes play an important role in biological processes related to cell wall modification, cell death and jasmonic acid signalling. EF-pine showed fewer transcriptomic changes than F-pine, whereas EF-treated angiosperm species studied so far showed more transcriptional changes to the initial phase of larval feeding than only feeding-damaged F-angiosperms. However, as with responses of EF-angiosperms, EF-pine showed higher salicylic acid concentrations than F-pine. Based on the considerable overlap of the transcriptomes of E- and F-pine, we suggest that the weaker transcriptomic response of EF-pine than F-pine to larval feeding damage is compensated by the strong, egg-induced response, which might result in maintained pine defences against larval feeding.

Bacterivorous nematodes decipher microbial iron siderophores as prey cue in predator-prey interactions.

The minimal levels of biological-available iron in the environment impose growth limitation on all living organisms. Microbes often secrete high iron-binding-affinity siderophores at high concentrations for scavenging iron from the iron-limited habitats. However, the high prevalence of siderophores released by bacteria into the environment raises an intriguing question whether this chemical cue can be detected by bacterivorous predators. Here, we show that the bacterivorous Caenorhabditis elegans nematode could employ its chemosensory receptor Odr-10 to detect pyoverdine, an iron siderophore secreted by an environmental bacterium, Pseudomonas aeruginosa. This enabled the nematode predator to migrate toward the prey. Our soil microcosm study showed that the detection of pyoverdine and subsequent feeding of P. aeruginosa prey by C. elegans could lead to the expansion of its population. These results showed that siderophores are a prey chemical cue by predators, with key implications in predator-prey interactions.

Visualisation of Bluetongue Virus in the Salivary Apparatus of Culicoides Biting Midges Highlights the Accessory Glands as a Primary Arboviral Infection Site

BackgroundArthropods transmit a wide range of pathogens of importance for the global health of humans, animals, and plants. One group of these arthropod vectors, Culicoides biting midges (Diptera: Ceratopogonidae), is the biological vector of several human and animal pathogens, including economically important livestock viruses like bluetongue virus (BTV). Like other arthropod-borne viruses (arboviruses), Culicoides-borne viruses must reach and replicate in the salivary apparatus, from where they can be transmitted to susceptible hosts through the saliva during subsequent blood feeding. Despite the importance of the salivary gland apparatus for pathogen transmission to susceptible animals from the bite of infected Culicoides, these structures have received relatively little attention, perhaps due to the small size and fragility of these vectors.ResultsIn this study, we developed techniques to visualize the infection of the salivary glands and other soft tissues with BTV, in some of the smallest known arbovirus vectors, Culicoides biting midges, using three-dimensional immunofluorescence confocal microscopy. We showed BTV infection of specific structures of the salivary gland apparatus of female Culicoides vectors following oral virus uptake, related visualisation of viral infection in the salivary apparatus to high viral RNA copies in the body, and demonstrated for the first time, that the accessory glands are a primary site for BTV replication within the salivary apparatus.ConclusionsOur work has revealed a novel site of virus-vector interactions, and a novel role of the accessory glands of Culicoides in arbovirus amplification and transmission. Our approach would also be applicable to a wide range of arbovirus vector groups including sand flies (Diptera: Psychodidae), as well as provide a powerful tool to investigate arbovirus infection and dissemination, particularly where there are practical challenges in the visualization of small size and delicate tissues of arthropods.

The Effect of Cuelure on Attracting and Feeding Behavior in Zeugodacus tau (Walker) (Diptera: Tephritidae).

As a vital pest control strategy, trapping plays an important role in the system of monitoring, catching and killing fruit flies. Cuelure (4-(4-acetoxyphenyl)-2-butanone, CL) is a male lure that attracts Zeugodacus tau and also stimulates feeding in this species. In this study, the attraction of Z. tau to CL and its subsequent feeding behavior were investigated. Under the significant influence of age and time of day, the attraction of CL to Z. tau was found to be optimal when flies were 14 days old, and the number of flies trapped increased with trapping duration. It was determined that consumption can improve the mating success and female adult fertility of Z. tau. After the observation period, the mating success rate of flies that ingested CL was significantly higher than that of the control group and was maintained at a higher level. It was found that parental consumption of CL could accelerate the development of eggs and larvae, resulting in increased pupation and emergence rates. The results of this study will further clarify the dynamic relationship between pest and lure, and provide a research basis for navigating the integrated management of Z. tau in the field.

Polyubiquitin protein of Aedes aegypti as an interacting partner of dengue virus envelope protein.

Dengue virus (DENV) is an arbovirus that comprises four antigenically different serotypes. Aedes aegypti (Diptera: Culicidae) acts as the principal vector for DENV transmission, and vector control is crucial for dengue fever epidemic management. To design effective vector control strategies, a comprehensive understanding of the insect vector and virus interaction is required. Female Ae. aegypti ingests DENV during the acquisition of a blood meal from an infected human. DENV enters the insect midgut, replicates inside it and reaches the salivary gland for transmitting DENV to healthy humans during the subsequent feeding cycles. DENV must interact with the proteins present in the midgut and salivary glands to gain entry and accomplish successful replication and transmission. Ae. aegypti midgut cDNA library was prepared, and yeast two-hybrid screening was performed against the envelope protein domain III (EDIII) protein of DENV-2. The polyubiquitin protein was selected from the various candidate proteins for subsequent analysis. Polyubiquitin gene was amplified, and the protein was purified in a heterologous expression system for in vitro interaction studies. In vitro pull-down assay presented a clear interaction between polyubiquitin protein and EDIII. To further confirm this interaction, a dot blot assay was employed, and polyubiquitin protein was found to interact with DENV particles. Our results enable us to suggest that polyubiquitin plays an important role in DENV infection within mosquitoes.

Involvement of a silkworm D2-like dopamine receptor in the promotion of feeding and related behaviors

The biogenic amine dopamine (DA) regulates various physiological and behavioral processes in insects through binding with specific receptors. Three types of typical receptors are known to date. Previously, we achieved functional and pharmacological characterization of the three DA receptors in the silkworm Bombyx mori (BmDopR1–3). BmDopR1 and BmDopR2 are functionally classified as D1-like DA receptors, and BmDopR3 as D2-like. The present pharmacological data and our previous studies suggested that bromocriptine (Bro), which acts as an agonist on the DA D2 receptors and also interacts with various serotonin and adrenergic receptors in vertebrates, is an agonist that also acts specifically on BmDopR3, with little effect on BmDopR1 and BmDopR2 in silkworms. Exploiting this subtype specificity of Bro, to offer clues on the involvement of DA and its receptors in silkworm feeding behavior, Bro was injected into fifth instar larvae and subsequent feeding and related behaviors (feeding amount, excretion amount, mandibular movement, and feeding behavior observation) were quantitatively evaluated. Bro injection increased feeding and excretion amounts but did not affect mandibular chewing speed. Visual observation of feeding behavior for 1 h revealed the prolongation of feeding and related moving time in Bro-injected larvae. Collectively, these results suggest that Bro directly acted on BmDopR3 as an agonist and promoted feeding and related behaviors in silkworm larvae.