Primary Duck Hepatocyte Culture and Duck Hepatitis B Virus Infection Model.

Duck hepatitis B virus (DHBV) is an avian member of the hepatotropic DNA viruses, or hepadnaviridae. It shares with the human hepatitis B virus (HBV) a similar genomic organization and replication strategy via reverse transcription, but is simpler than HBV in lacking the X gene and in expressing just two coterminal envelope proteins: Large (L) and small (S). DHBV has been extensively used as a convenient and valuable animal model for study of the hepadnaviral life cycle, and for drug screening in vitro but also in vivo. Ducks and primary duck hepatocytes (PDHs) are inexpensive, easily accessible, and readily infected with DHBV. The high levels of genome replication and protein expression in duck liver and PDHs also facilitate monitoring of viral life cycle using conventional molecular biology techniques such as Southern blot for replicative DNA and covalently closed circular DNA (cccDNA), Northern blot for viral RNAs, and Western blot for viral proteins.

Harvest of waterfowl and Sandhill Crane in rural Alaska: Geographic and seasonal patterns.

We estimated the annual harvest of waterfowl and Sandhill Crane Grus canadensis and their eggs by Alaska's rural residents and described seasonal and geographic patterns. Subsistence in Alaska refers to patterns of resource use typical of rural, remote regions where Indigenous people are a high proportion of the population. Rural communities in Alaska rely on the legally-allowed spring-summer harvest of migratory birds for food and socio-cultural wellbeing, in addition to harvests in the fall-winter general hunting season. We based harvest estimates on a large dataset (637 community-years) composed from multiple sources. The estimated annual average harvest of waterfowl and Sandhill Crane by rural residents was 270,641 birds/year (68% in spring-summer, 32% in fall-winter) and 36,692 eggs/year in the 2004-2015 reference period. Harvest estimates for ducks, swans, and Sandhill Crane were lower than in the 1980s-1990s. Harvest amounts, seasonality, and species composition distinguished regional patterns for the Pacific-Aleutian mainland and islands, Bering Sea mainland, St. Lawrence-Diomede islands, North Slope, and Interior Alaska-Upper Copper River. Rural residents accounted for 79% of the total waterfowl harvest in Alaska and high proportions of the total Pacific Flyway harvest for several species of sea ducks, geese, swans, and Sandhill Crane. Alaska's Indigenous people are important partners in harvest management and conservation of migratory birds. Harvest data are needed to inform efficient and appropriate decisions to achieve management goals. This study can facilitate collaboration for harvest management and conservation across Alaska and the flyways by helping diverse users to understand their contributions to the total harvest.

On the wing: Morphological variation in the osteology of Mediterranean, Near Eastern, and European Anatidae (excluding Anserinae).

Accurate identification of waterfowl bones in archaeological and fossil assemblages has potential to unlock new methods of past environmental reconstruction, as species have differing habitat preferences and migration patterns. Therefore, identifying the presence of avian species with different ecological niches is key to determining past environments and ultimately how prehistoric people responded to climatic and environmental realignments. However, the identification of osteological remains of waterbirds such as ducks to species level is notoriously challenging. We address this by presenting a new two-dimensional geometric morphometric protocol on wing elements from over 20 duck species and test the utility of these shape data for correct species identification. This is an ideal starting point to expand utilization of these types of approaches in avifaunal research and test applicability to an extremely difficult taxonomic group.

Haplotype-resolved assembly of the mule duck genome using high-fidelity sequencing technology.

Mule duck is vitally important to the production of global duck meat. Here, we present two high-quality haplotypes of a female mule duck (haplotype 1 (H1):1.28 Gb, haplotype 2 (H2): 1.40 Gb). The continuity (H1: contig N50 = 14.90 Mb, H2: contig N50 = 15.70 Mb) and completeness (BUSCO: H1 = 96.9%, H2 = 97.3%) are substantially better than those of other duck genomes. We detected the structural variations (SVs) in H1 and H2. We observed a positive correlation between autosome length and the number of SVs. Z chromosome was some deficient in deletions and insertions, but W chromosome was some excessive. A total of 1,451 genes were haplotype specific expression (HSEs). Among them, 737 specifically expressed in H1, and 714 specifically expressed in H2. We found that H1 and H2 HSEs tended to be involved in similar biological processes, such as myometrial relaxation and contraction pathways, muscle structure development and phosphorylation. Our haplotype-resolved genome assembly provides a powerful platform for future functional genomics, molecular breeding, and genome editing in mule duck.

Wood duck nest survival and duckling recruitment is minimally affected by interspecific brood parasitism from hooded mergansers and black-bellied whistling-ducks.

In the southeastern United States, wood ducks (Aix sponsa) have historically experienced interspecific brood parasitism (IBP) primarily from hooded mergansers (Lophodytes cucullatus), but the recent northward expansion of black-bellied whistling-ducks (Dendrocygna autumnalis) has added a new complexity to these interactions. We monitored nest boxes in Louisiana to evaluate the influence IBP had on wood duck daily nest survival rate (after, DSR) and duckling recruitment. We monitored 1,295 wood duck nests from 2020-2023 and found 112 (8.7%) were parasitized by hooded mergansers and 148 (11.5%) by whistling-ducks. Parasitic egg-laying by hooded mergansers lowered wood duck DSR, while DSR for nests parasitized by whistling-ducks was comparable to clutches containing only wood duck eggs. We considered the wood duck capture histories of 2,465 marked female ducklings and 540 banded adult females to estimate a duckling recruitment probability for the entire study period. We recaptured 50 ducklings as adults; 6 (12.0%) hatched from clutches parasitized by hooded mergansers, 1 (2.0%) from a clutch parasitized by a whistling-duck, and 43 (86.0%) from clutches containing only wood duck eggs. The duckling recruitment probability was 0.039 (95% credible interval = 0.028, 0.051). Nest initiation date had a negative effect on recruitment, wherein most recruits hatched from nests initiated earlier in the season. Given only ~9% of wood duck nests contained hooded merganser eggs, we conclude IBP writ large had no detrimental effect on DSR at a population level. The lower DSR of clutches parasitized by hooded mergansers is potentially linked to a high abundance of early-season parasites that produce "dump nests" and these clutches are often abandoned without being incubated. Despite ongoing parasitism by hooded mergansers and the range expansion of whistling-ducks, wood duck productivity in Louisiana appears to be minimally affected by interspecific brood parasitism.

Testing the form-function paradigm: body shape correlates with kinematics but not energetics in selectively-bred birds.

A central concept of evolutionary biology, supported by broad scale allometric analyses, asserts that changing morphology should induce downstream changes in locomotor kinematics and energetics, and by inference selective fitness. However, if these mechanistic relationships exist at local intraspecific scales, where they could provide substrate for fundamental microevolutionary processes, is unknown. Here, analyses of selectively-bred duck breeds demonstrate that distinct body shapes incur kinematic shifts during walking, but these do not translate into differences in energetics. A combination of modular relationships between anatomical regions, and a trade-off between limb flexion and trunk pitching, are shown to homogenise potential functional differences between the breeds, accounting for this discrepancy between form and function. This complex interplay between morphology, motion and physiology indicates that understanding evolutionary links between the avian body plan and locomotor diversity requires studying locomotion as an integrated whole and not key anatomical innovations in isolation.

The GE296_RS03820 and GE296_RS03830 genes are involved in capsular polysaccharide biosynthesis in Riemerella anatipestifer.

Riemerella anatipestifer is a pathogenic bacterium that causes duck serositis and meningitis, leading to significant harm to the duck industry. To escape from the host immune system, the meningitis-causing bacteria must survive and multiply in the bloodstream, relying on specific virulence factors such as capsules. Therefore, it is essential to study the genes involved in capsule biosynthesis in R. anatipestifer. In this study, we successfully constructed gene deletion mutants Δ3820 and Δ3830, targeting the GE296_RS03820 and GE296_RS03830 genes, respectively, using the RA-LZ01 strain as the parental strain. The growth kinetics analysis revealed that these two genes contribute to bacterial growth. Transmission and scanning electron microscopy (TEM and SEM) and silver staining showed that Δ3820 and Δ3830 produced the altered capsules and compounds of capsular polysaccharides (CPSs). Serum resistance test showed the mutants also exhibited reduced C3b deposition and decreased resistance serum killing. In vivo, Δ3820 and Δ3830 exhibited markedly declining capacity to cross the blood-brain barrier, compared to RA-LZ01. These findings indicate that the GE296_RS03820 and GE296_RS03830 genes are involved in CPSs biosynthesis and play a key role in the pathogenicity of R. anatipestifer. Furthermore, Δ3820 and Δ3830 mutants presented a tendency toward higher survival rates from RA-LZ01 challenge in vivo. Additionally, sera from ducklings immunized with the mutants showed cross-immunoreactivity with different serotypes of R. anatipestifer, including 1, 2, 7 and 10. Western blot and SDS-PAGE assays revealed that the altered CPSs of Δ3820 and Δ3830 resulted in the exposure of some conserved proteins playing the key role in the cross-immunoreactivity. Our study clearly demonstrated that the GE296_RS03820 and GE296_RS03830 genes are involved in CPS biosynthesis in R. anatipestifer and the capsule is a target for attenuation in vaccine development.

Proximity among protected area networks promotes functional connectivity for wintering waterfowl.

The equilibrium theorem provided a fundamental framework for understanding species' distributions and movement in fragmented ecosystems. Wetland-dependent avian species are model organisms to test insular predictions within protected area networks because their mobility allows surveillance of isolated patches without landscape barriers. We hypothesized size and isolation would influence functional connectivity of sanctuaries by GPS-marked wintering mallards (Anas platyrhynchos) within a mesocosm protected sanctuary area network. We evaluated functional connectivity and sanctuary use, measured by movements between sanctuaries, using a multistate modeling framework. Proximity drove connectivity, underscoring that patch isolation-not size-influenced connectivity, even for an avian species with no ascertainable landscape resistance or barriers. We also found that sanctuary use increased overwintering survival by reducing harvest mortality. Our test of equilibrium theory predictions demonstrated that isolation of protected sanctuary areas supersedes their size in determining functional connectivity for mallards and access to these areas may have direct fitness consequences. Our findings could refine land acquisition, restoration, and management practices with equal or greater emphasis on adjacency in protected area network design, especially for wetland-dependent migratory gamebirds.

Automatic wild bird repellent system that is based on deep-learning-based wild bird detection and integrated with a laser rotation mechanism.

Wild bird repulsion is critical in agriculture because it helps avoid agricultural food losses and mitigates the risk of avian influenza. Wild birds transmit avian influenza in poultry farms and thus cause large economic losses. In this study, we developed an automatic wild bird repellent system that is based on deep-learning-based wild bird detection and integrated with a laser rotation mechanism. When a wild bird appears at a farm, the proposed system detects the bird's position in an image captured by its detection unit and then uses a laser beam to repel the bird. The wild bird detection model of the proposed system was optimized for detecting small pixel targets, and trained through a deep learning method by using wild bird images captured at different farms. Various wild bird repulsion experiments were conducted using the proposed system at an outdoor duck farm in Yunlin, Taiwan. The statistical test results of our experimental data indicated that the proposed automatic wild bird repellent system effectively reduced the number of wild birds in the farm. The experimental results indicated that the developed system effectively repelled wild birds, with a high repulsion rate of 40.3% each day.

Does Salmonella diarizonae 58:r:z53 Isolated from a Mallard Duck Pose a Threat to Human Health?

Salmonella diarizonae (IIIb) is frequently isolated from reptiles and less frequently from birds and mammals. However, its isolation from invasive human infections has not been widely reported. Migratory mallard ducks are excellent bioindicators of pathogen presence and pathogen antibiotic resistance (AMR). We present the first isolation from a mallard duck in central Europe of the antibiotic-resistant Salmonella enterica subsp. diarizonae with the unique antigenic pattern 58:r:z53 and report its whole-genome sequencing, serosequencing, and genotyping, which enabled the prediction of its pathogenicity and comparison with phenotypic AMR. The isolated strain was highly similar to S. diarizonae isolated from humans and food. Twenty-four AMR genes were detected, including those encoding aminoglycoside, fluoroquinolone, macrolide, carbapenem, tetracycline, cephalosporin, nitroimidazole, peptide antibiotic, and disinfecting agent/antiseptic resistance. Six Salmonella pathogenicity islands were found (SPI-1, SPI-2, SPI-3, SPI-5, SPI-9, and SPI-13). An iron transport system was detected in SPI-1 centisome C63PI. Plasmid profile analyses showed three to be present. Sequence mutations in the invA and invF genes were noted, which truncated and elongated the proteins, respectively. The strain also harbored genes encoding type-III secretion-system effector proteins and many virulence factors found in S. diarizonae associated with human infections. This study aims to elucidate the AMR and virulence genes in S. enterica subsp. diarizonae that may most seriously threaten human health.

Integrated transcriptomics and metabolomics study of embryonic breast muscle of Jiaji ducks.

Because number of matured muscle fibers in poultry does not increase after birth, the meat yield is mainly determined during embryogenesis. We previously indicated breast muscle grew rapidly from 18th day after hatching (E18) to E27, and almost stopped from E27 to E34 of Jiaji ducks, while the mechanism is unclear. This study utilized RNA-seq to explore the related genes of muscle development and their relationship with small molecule metabolites at E18, E27 and E34 of Jiaji ducks. Several thousand differentially expressed genes (DEGs) were detected among E18, E27 and E34. DEGs expression profiles included 8 trend maps, among which trend 1 was opposite to and trend 6 was consistent with breast muscle development trend of Jiaji ducks. Through joint analysis between trend 1 of DEGs and trend 1 of differential metabolites (DEMs), protein digestion and absorption pathway stood out. The decrease of COL8A2 gene expression will lead to the decrease of arginine content, which will inhibit the development of breast muscle in embryonic Jiaji duck. Similarly, joint analysis between trend 6 of DEGs and trend 6 of DEMs indicated the increase of GAMT gene expression will cause the increase of proline content, and then promote the development of breast muscle of Jiaji duck in embryonic period. These results will be helpful for further understanding the mechanism of muscle yields of Jiaji ducks.

The Effects of Aflatoxin B1 on Liver Cholestasis and Its Nutritional Regulation in Ducks.

The aim of this study was to investigate the effects of aflatoxin B1 (AFB1) on cholestasis in duck liver and its nutritional regulation. Three hundred sixty 1-day-old ducks were randomly divided into six groups and fed for 4 weeks. The control group was fed a basic diet, while the experimental group diet contained 90 µg/kg of AFB1. Cholestyramine, atorvastatin calcium, taurine, and emodin were added to the diets of four experimental groups. The results show that in the AFB1 group, the growth properties, total bile acid (TBA) serum levels and total superoxide dismutase (T-SOD), glutathione peroxidase (GSH-Px), and glutathione (GSH) liver levels decreased, while the malondialdehyde (MDA) and TBA liver levels increased (p < 0.05). Moreover, AFB1 caused cholestasis. Cholestyramine, atorvastatin calcium, taurine, and emodin could reduce the TBA serum and liver levels (p < 0.05), alleviating the symptoms of cholestasis. The qPCR results show that AFB1 upregulated cytochrome P450 family 7 subfamily A member 1 (CYP7A1) and cytochrome P450 family 8 subfamily B member 1 (CYP8B1) gene expression and downregulated ATP binding cassette subfamily B member 11 (BSEP) gene expression in the liver, and taurine and emodin downregulated CYP7A1 and CYP8B1 gene expression (p < 0.05). In summary, AFB1 negatively affects health and alters the expression of genes related to liver bile acid metabolism, leading to cholestasis. Cholestyramine, atorvastatin calcium, taurine, and emodin can alleviate AFB1-induced cholestasis.

Human-Induced Range Expansions Result in a Recent Hybrid Zone between Sister Species of Ducks.

Landscapes are consistently under pressure from human-induced ecological change, often resulting in shifting species distributions. For some species, changing the geographical breadth of their niche space results in matching range shifts to regions other than those in which they are formally found. In this study, we employ a population genomics approach to assess potential conservation issues arising from purported range expansions into the south Texas Brush Country of two sister species of ducks: mottled (Anas fulvigula) and Mexican (Anas diazi) ducks. Specifically, despite being non-migratory, both species are increasingly being recorded outside their formal ranges, with the northeastward and westward expansions of Mexican and mottled ducks, respectively, perhaps resulting in secondary contact today. We assessed genetic ancestry using thousands of autosomal loci across the ranges of both species, as well as sampled Mexican- and mottled-like ducks from across overlapping regions of south Texas. First, we confirm that both species are indeed expanding their ranges, with genetically pure Western Gulf Coast mottled ducks confirmed as far west as La Salle county, Texas, while Mexican ducks recorded across Texas counties near the USA-Mexico border. Importantly, the first confirmed Mexican × mottled duck hybrids were found in between these regions, which likely represents a recently established contact zone that is, on average, ~100 km wide. We posit that climate- and land use-associated changes, including coastal habitat degradation coupled with increases in artificial habitats in the interior regions of Texas, are facilitating these range expansions. Consequently, continued monitoring of this recent contact event can serve to understand species' responses in the Anthropocene, but it can also be used to revise operational survey areas for mottled ducks.

A biphasic accelerated strand exchange amplification strategy for culture-independent and rapid detection of Salmonella enterica in food samples.

Salmonella enterica is a common foodborne pathogen that can cause food poisoning in humans. The organism also infects and causes disease in animals. Rapid and sensitive detection of S. enterica is essential to prevent the spread of this pathogen. Traditional technologies for the extraction and detection of this pathogen from complex food matrices are cumbersome and time-consuming. In this study, we introduced a novel strategy of biphasic assay integrated with an accelerated strand exchange amplification (ASEA) method for efficient detection of S. enterica without culture or other extraction procedures. Food samples are rapidly dried, resulting in a physical fluidic network inside the dried food matrix, which allows polymerases and primers to access the target DNA and initiate ASEA. The dried food matrix is defined as the solid phase, while amplification products are enriched in the supernatant (liquid phase) and generate fluorescence signals. The analytical performances demonstrated that this strategy was able to specifically identify S. enterica and did not show any cross-reaction with other common foodborne pathogens. For artificially spiked food samples, the strategy can detect 5.0 × 101 CFU mL-1S. enterica in milk, 1.0 × 102 CFU g-1 in duck, scallop or lettuce, and 1.0 × 103 CFU g-1 in either oyster or cucumber samples without pre-enrichment of the target pathogen. We further validated the strategy using 82 real food samples, and this strategy showed 92% sensitivity. The entire detection process can be finished, sample-to-answer, within 50 min, dramatically decreasing the detection time. Therefore, we believe that the proposed method enables rapid and sensitive detection of S. enterica and holds great promise for the food safety industry.

Recombination and amino acid point mutations in VP3 exhibit a synergistic effect on increased virulence of rMDPV.

Recombinant Muscovy duck parvovirus (rMDPV) is a product of genetic recombination between classical Muscovy duck parvovirus (MDPV) and goose parvovirus (GPV). The recombination event took place within a 1.1-kb DNA segment located in the middle of the VP3 gene, and a 187-bp sequence extending from the P9 promoter to the 5' initiation region of the Rep1 ORF. This resulted in the alteration of five amino acids within VP3. Despite these genetic changes, the precise influence of recombination and amino acid mutations on the pathogenicity of rMDPV remains ambiguous. In this study, based on the rMDPV strain ZW and the classical MDPV strain YY, three chimeric viruses (rZW-mP9, rZW-mPR187, and rYY-rVP3) and the five amino acid mutations-introduced mutants (rZW-g5aa and rYY-5aa(ZW)) were generated using reverse genetic technology. When compared to the parental virus rZW, rZW-g5aa exhibited a prolonged mean death time (MDT) and a decreased median lethal dose (ELD50) in embryonated duck eggs. In contrast, rYY-5aa(ZW) did not display significant differences in MDT and ELD50 compared to rYY. In 2-day-old Muscovy ducklings, infection with rZW-g5aa and rYY-5aa(ZW) resulted in mortality rates of only 20% and 10%, respectively, while infections with the three chimeric viruses (rZW-mP9, rZW-mPR187, rYY-rVP3) and rZW still led to 100% mortality. Notably, rYY-rVP3, containing the VP3 region from strain ZW, exhibited 50% mortality in 6-day-old Muscovy ducklings and demonstrated significant horizontal transmission. Collectively, our findings indicate that recombination and consequent amino acid changes in VP3 have a synergistic impact on the heightened virulence of rMDPV in Muscovy ducklings.

Avian influenza viruses in New Zealand wild birds, with an emphasis on subtypes H5 and H7: Their distinctive epidemiology and genomic properties.

The rapid spread of highly pathogenic avian influenza (HPAI) A (H5N1) viruses in Southeast Asia in 2004 prompted the New Zealand Ministry for Primary Industries to expand its avian influenza surveillance in wild birds. A total of 18,693 birds were sampled between 2004 and 2020, including migratory shorebirds (in 2004-2009), other coastal species (in 2009-2010), and resident waterfowl (in 2004-2020). No avian influenza viruses (AIVs) were isolated from cloacal or oropharyngeal samples from migratory shorebirds or resident coastal species. Two samples from red knots (Calidris canutus) tested positive by influenza A RT-qPCR, but virus could not be isolated and no further characterization could be undertaken. In contrast, 6179 samples from 15,740 mallards (Anas platyrhynchos) tested positive by influenza A RT-qPCR. Of these, 344 were positive for H5 and 51 for H7. All H5 and H7 viruses detected were of low pathogenicity confirmed by a lack of multiple basic amino acids at the hemagglutinin (HA) cleavage site. Twenty H5 viruses (six different neuraminidase [NA] subtypes) and 10 H7 viruses (two different NA subtypes) were propagated and characterized genetically. From H5- or H7-negative samples that tested positive by influenza A RT-qPCR, 326 AIVs were isolated, representing 41 HA/NA combinations. The most frequently isolated subtypes were H4N6, H3N8, H3N2, and H10N3. Multivariable logistic regression analysis of the relations between the location and year of sampling, and presence of AIV in individual waterfowl showed that the AIV risk at a given location varied from year to year. The H5 and H7 isolates both formed monophyletic HA groups. The H5 viruses were most closely related to North American lineages, whereas the H7 viruses formed a sister cluster relationship with wild bird viruses of the Eurasian and Australian lineages. Bayesian analysis indicates that the H5 and H7 viruses have circulated in resident mallards in New Zealand for some time. Correspondingly, we found limited evidence of influenza viruses in the major migratory bird populations visiting New Zealand. Findings suggest a low probability of introduction of HPAI viruses via long-distance bird migration and a unique epidemiology of AIV in New Zealand.

Chlamydia psittaci detected at a live poultry wholesale market in central China.

BACKGROUND: We investigated the presence of Chlamydia psittaci in poultry and the environment in live poultry wholesale markets in Changsha during 2021-2022 and conducted a phylogenetic analysis to understand its distribution in this market. METHODS: In total, 483 samples were analyzed using real-time polymerase chain reaction and 17 C. psittaci-positive samples using high-throughput sequencing, BLAST similarity, and phylogenetic analysis. RESULTS: Twenty-two out of 483 poultry and environmental samples were positive for C. psittaci (overall positivity rate: 4.55%) with no difference in positivity rates over 12 months. Chlamydia psittaci was detected at 11 sampling points (overall positivity rate: 27.5%), including chicken, duck, and pigeon/chicken/duck/goose shops, with pigeon shops having the highest positivity rate (46.67%). The highest positivity rates were found in sewage (12.5%), poultry fecal (7.43%), cage swab (6.59%), avian pharyngeal/cloacal swab (3.33%), and air (2.29%) samples. The ompA sequences were identified in two strains of C. psittaci, which were determined to bear genotype B using phylogenetic analysis. Thus, during monitoring, C. psittaci genotype B was detected in the poultry and environmental samples from the poultry wholesale market in Changsha. CONCLUSIONS: To address the potential zoonotic threat, C. psittaci monitoring programs in live poultry markets should be enhanced.

RNF216 Inhibits the Replication of H5N1 Avian Influenza Virus and Regulates the RIG-I Signaling Pathway in Ducks.

The RING finger (RNF) family, a group of E3 ubiquitin ligases, plays multiple essential roles in the regulation of innate immunity and resistance to viral infection in mammals. However, it is still unclear whether RNF proteins affect the production of IFN-I and the replication of avian influenza virus (AIV) in ducks. In this article, we found that duck RNF216 (duRNF216) inhibited the duRIG-I signaling pathway. Conversely, duRNF216 deficiency enhanced innate immune responses in duck embryonic fibroblasts. duRNF216 did not interacted with duRIG-I, duMDA5, duMAVS, duSTING, duTBK1, or duIRF7 in the duck RIG-I pathway. However, duRNF216 targeted duTRAF3 and inhibited duMAVS in the recruitment of duTRAF3 in a dose-dependent manner. duRNF216 catalyzed K48-linked polyubiquitination of duck TRAF3, which was degraded by the proteasome pathway. Additionally, AIV PB1 protein competed with duTRAF3 for binding to duRNF216 to reduce degradation of TRAF3 by proteasomes in the cytoplasm, thereby slightly weakening duRNF216-mediated downregulation of IFN-I. Moreover, although duRNF216 downregulated the IFN-ß expression during virus infection, the expression level of IFN-ß in AIV-infected duck embryonic fibroblasts overexpressing duRNF216 was still higher than that in uninfected cells, which would hinder the viral replication. During AIV infection, duRNF216 protein targeted the core protein PB1 of viral polymerase to hinder viral polymerase activity and viral RNA synthesis in the nucleus, ultimately strongly restricting viral replication. Thus, our study reveals a new mechanism by which duRNF216 downregulates innate immunity and inhibits AIV replication in ducks. These findings broaden our understanding of the mechanisms by which the duRNF216 protein affects AIV replication in ducks.

Embryo injected with Ochratoxin A induced jejunum injury in ducklings by activating the TLR4 signaling pathway: Involvement of intestinal microbiota.

Ochratoxin A (OTA) is a common mycotoxin that causes intestinal injury in humans and various animal species. OTA may lead to intestinal injury in offspring due to the maternal effect. The aim of this study was to investigate the mechanism of embryo injected with OTA induced jejunum injury in ducklings. The results showed that OTA disrupted the jejunum tight junctions in hatching ducklings, and promoted the secretion of inflammatory cytokines. And this inflammatory response was caused by the activation of the TLR4 signaling pathway. Moreover, embryo injected with OTA could cause damage to the intestinal barrier in 21-day-old ducks, characterized by shortened villi, crypt hyperplasia, disrupted intestinal tight junctions, increased level of LPS in the jejunum, activation of the TLR4 signaling pathway, and increased levels of pro-inflammatory cytokines. Meanwhile, OTA induced oxidative stress in the jejunum. And dysbiosis of gut microbiota was mainly characterized by an increased the relative abundance of Bacteroides, Megamonas, Fournierella, and decreased the relative abundance of Alistipes and Weissella. Interestingly, embryo injected with OTA did not induce these changes in the jejunum of antibiotics-treated 21-day-old ducks. In conclusion, embryo injected with OTA induced jejunum injury in ducklings by activating the TLR4 signaling pathway, which involvement of intestinal microbiota.

Exploring avian exposure to parent polycyclic aromatic hydrocarbons (PAHs): Using the common eider Somateria mollissima in a global context.

Compared to other organic contaminants, birds are rarely studied for their exposure to polycyclic aromatic hydrocarbons (PAHs), mainly due to their effective metabolization of parent PAHs. However, as some studies suggest, exposure to PAHs may result in adverse health effects including decreased survival, especially following oil spills. In the present study, we analyzed samples from a sea duck, the common eider Somateria mollissima including feathers, preen oil, blood, liver and bile, to evaluate whether non- lethally collected samples could be reliably used for avian biomonitoring strategies. Phenanthrene was the only individual PAH detected across sample types, with the highest concentration found in preen gland and the lowest in blood. Significant differences in concentrations were observed between bile vs preen gland and liver vs preen gland, while for most compounds neither blood nor feathers showed detectable levels of parent PAHs. Therefore, the utility of those sample types for PAH exposure assessment may be limited and should be interpreted with caution, moreover as several physiological factors may affect them. Additionally, we also provide a comparison with the available literature to review current avian PAH exposure assessment and outline future research focused needs.