Detection and spread of Phytophthora austrocedri within infected Juniperus communis woodland and diversity of co‐associated Phytophthoras as revealed by metabarcoding

Phytophthora austrocedri is a recently invasive soilborne pathogen which is causing widespread mortality of Juniperus communis in northern Britain. The pathways by which a single genotype of P. austrocedri has spread to infect such a geographically dispersed range of woodland sites within a relatively short timeframe are unknown. This study examined the detectability of P. austrocedri in soil and water within infected J. communis woodland using qPCR to gain a better understanding of the pathogen's key mechanisms of spread. A Phytophthora metabarcoding method was also applied to investigate the wider diversity of Phytophthora species present in water at one of the sites. qPCR analyses of P. austrocedri in soil samples at a J. communis woodland exhibiting low‐to‐moderate levels of disease suggested a slow natural spread of the pathogen in soil, requiring high moisture conditions. However, the ubiquity of P. austrocedri DNA in soil samples collected across a heavily infected J. communis site suggests that once established at a site the pathogen can be spread readily in soil locally, most likely vectored by animal movements and/or human activities. The hypothesis that P. austrocedri is aerially transmitted in rainwater was not adequately proven, and an alternative hypothesis for the widespread distribution of the pathogen on J. communis in northern Britain is presented. Metabarcoding identified DNA from a diverse range of Phytophthora species in river and rainwater samples although the main target pathogen, P. austrocedri, was not amplified which disagreed with some of the qPCR findings. Possible reasons for this are discussed.     

Evaluating the Technique of Using Nitrogen Retention as a Response Criterion for Amino Acid Studies in the Horse

Six Quarter Horse yearling fillies were used in a duplicated 3 × 3 Latin square experiment to evaluate the technique of using nitrogen retention as a response criterion for amino acid studies in the horse. Yearlings were paired by age and randomly assigned to one of three concentrates fed with medium-quality Coastal Bermudagrass hay. Diet A, a soybean meal–based concentrate, was amino acid sufficient. Diet B, a cottonseed hull–based concentrate containing 2% urea, was amino acid deficient. Horses fed diet C, identical to diet B, were orally dosed with synthetic essential amino acids and cysteine, immediately before eating, to match amino acid levels in diet A. Nitrogen retention was not different between diets A and B. There was a trend for horses fed diet C to have higher nitrogen retention, as a result of higher nitrogen intake. Nitrogen retained as a percent absorbed was lower (P < .05) for diet B than for diet A, whereas values for diet C were not different from diets A or B. Nitrogen retention was not an effective response criterion in this study. Differences in nitrogen retained as a percentage absorbed were observed between amino acid–sufficient and deficient diets. However, horses fed amino acid–deficient diets and dosed with synthetic amino acids likely require some modified dosage level to achieve the same or higher values as those for amino acid–sufficient diets.     

Endocrine Profile Comparisons of Fat Versus Moderately Conditioned Mares Following Parturition

The influence of progesterone, luteinizing hormone (LH), and estrogen on the mare's estrous cycle has been well researched and documented, but other endocrine profiles have not received as much attention. To evaluate endocrine concentrations in fat-conditioned (body condition score [BCS] of 7–8) versus moderately conditioned mares (BCS of 5–6), 24 mares were allotted to and maintained in respective groups from late gestation until pregnancy was confirmed after breeding on the second postpartum estrus. Serum concentrations of thyroxine (T₄), insulin-like growth factor-1 (IGF-1), and leptin were assayed to characterize circulating blood concentrations. Additionally, LH and progesterone serum concentrations were assayed to evaluate the estrous cycle status of the mares. Leptin and progesterone concentrations were not different (P > .05) between the groups. Nevertheless, serum concentrations of T₄ were higher (P < .01) and IGF-1 concentrations lower (P < .01) in moderately conditioned as compared with fat-conditioned mares during times of ovulation and the interovulatory period. Furthermore, serum concentrations of LH were found to be different between the groups only when the estrous cycle approached the second ovulation (P < .0001). Results of this study suggest that mares maintained in a BCS of 5 or greater are similar in terms of reproductive efficiency. Although the circulating serum concentrations of T₄ and IGF-1 are different after parturition, their influence does not affect reproductive capabilities of mares with a BCS of 5 or greater.     

Alteration in lymphocyte responses,cytokine and chemokine profiles in chickens infected with genotype VII and VIII velogenic Newcastle disease virus

Newcastle disease (ND) is a highly contagious avian disease and one of the major causes of economic losses in the poultry industry. The emergence of virulent NDV genotypes and repeated outbreaks of NDV in vaccinated chickens have raised the need for fundamental studies on the virus–host interactions. In this study, the profiles of B and T lymphocytes and macrophages and differential expression of 26 immune-related genes in the spleen of specific-pathogen-free (SPF) chickens, infected with either the velogenic genotype VII NDV strain IBS002 or the genotype VIII NDV strain AF2240, were evaluated. A significant reduction in T lymphocyte population and an increase in the infiltration of IgM⁺ B cells and KUL01⁺ macrophages were detected in the infected spleens at 1, 3 and 4 days post-infection (dpi) (P < 0.05). The gene expression profiles showed an up-regulation of CCLi3, CXCLi1, CXCLi2 (IL-8), IFN-γ, IL-12α, IL-18, IL-1β, IL-6, iNOS, TLR7, MHCI, IL-17F and TNFSF13B (P < 0.05). However, these two genotypes showed different cytokine expression patterns and viral load. IBS002 showed higher viral load than AF2240 in spleen at 3 and 4 dpi and caused a more rapid up-regulation of CXCLi2, IFN-γ, IL-12α, IL-18, IL-1β, iNOS and IL-10 at 3 dpi. Meanwhile, the expression levels of CCLI3, CXCLi1, IFN-γ, IL-12α, IL-1β and iNOS genes were significantly higher in AF2240 at 4 dpi. In addition, the expression levels of IL-10 were significantly higher in the IBS002-infected chickens at 3 and 4 dpi. Hence, infection with velogenic genotype VII and VIII NDV induced different viral load and production of cytokines and chemokines associated with inflammatory reactions.     

Dietary xylanase and live yeast supplementation influence intestinal bacterial populations and growth performance of piglets fed a sorghum-based diet

This study was to evaluate the effect of xylanase supplementation and the addition of live yeast, Saccharomyces cerevisiae, on growth performance and intestinal microbiota in piglets. One hundred and eighty commercial crossbred 23-d-old piglets (PIC 417) were sorted by initial BW and allocated to 3 treatments: control (CTR) diet, CTR diet supplemented with xylanase at 16,000 birch xylan units/kg (XYL) and XYL diet supplemented with live yeast (2 × 10¹⁰ CFU/g) at 1 kg/t (XYL + LY). Each treatment had 10 replicates, with 6 animals each. A sorghum-based diet and water were available ad libitum for 42 d of the study. Average daily gain (ADG) and average daily feed intake (ADFI) were measured from 0 to 42 d (23- to 65-d-old) and feed conversion ratio (FCR) calculated. At the end of the study, bacterial identification through 16S rRNA (V3 to V4) sequencing of the ileal and caecal digesta from one piglet per replicate was performed. No treatment effects were observed on ADFI. Pigs offered the live yeast in addition to the xylanase had increased ADG compared with those supplemented with xylanase alone (XYL + LY vs. XYL; P = 0.655). FCR was improved with XYL and XYL + LY compared with CTR (P = 0.018). Clostridiaceae counts in the ileum tended to reduce by 10% with XYL and 14% with XYL + LY compared to CTR (P = 0.07). XYL and XYL + LY increased the counts of Lactobacillaceae in the caecum compared with CTR (P < 0.0001). Dietary supplementation of live yeast combined with xylanase improved growth performance and microbial balance of piglets during the nursery phase.     

Breakpoints for disc diffusion susceptibility testing of bacteria associated with fish diseases: A review of current practice

A survey of the methods being employed to determine antimicrobial susceptibility of bacteria associated with aquaculture was performed on behalf of the Permanent Advisory Network for Diseases in Aquaculture. Thirty-two laboratories in 18 countries responded and 25 reported the breakpoints they used for disc diffusion assays applied to Group 1, non-fastidious organisms isolated from finfish. A total of 117 breakpoints were reported for assays in which the disc contents were those specified by the current standard protocols. Data on the source of these breakpoints and the confidence the laboratories had in them are presented. Overall there was a considerable variation in the breakpoints employed by different laboratories and this variation is discussed in terms of the inter-laboratory precision that can be expected from the application of disc diffusion protocols. This paper discusses the possible clinical significance of the variations in the breakpoints and, where there are available data, the extent to which those in use are consistent with breakpoints suggested by other approaches.The data presented in this paper represent a starting point for the movement towards harmonising breakpoints used in association with the standard disc diffusion protocols that have been proposed for susceptibility testing of bacteria associated with fish diseases.     

Impacts of land use and salinization on soil inorganic and organic carbon in the middle-lower Yellow River Delta

Soil inorganic carbon (SIC) is an important reservoir of carbon (C) in arid, semi-arid, and semi-humid regions. However, knowledge is incomplete on the dynamics of SIC and its relationship with soil organic C (SOC) under different land use types in the semi-humid region, particularly in coastal zones impacted by soil salinization. We collected 170 soil samples from 34 profiles across various land use types (maize-wheat, cotton, paddy, and reed) in the middle-lower Yellow River Delta (YRD), China. We measured soil pH, electrical conductivity (EC), water-soluble salts, and SOC and SIC contents. Our results showed significant differences in both SOC and SIC among land use types. The dry cropland (maize-wheat and cotton) soils had significantly higher SOC and SIC densities (4.71 and 15.46 kg C m^-2, respectively) than the paddy soils (3.28 and 14.09 kg C m^-2, respectively) in the 0–100 cm layer. Compared with paddy soils, reed soils contained significantly higher SOC (4.68 kg C m^-2) and similar SIC (15.02 kg C m^-2) densities. There was a significant positive correlation between SOC and SIC densities over a 0–100 cm soil depth in dry cropland soils, but a negative relationship in the paddy soils. On average, SOC and SIC densities under maize-wheat cropping were 15% and 4% lower, respectively, in the salt-affected soils in the middle-lower YRD than the upper YRD. This study indicated that land use types had great influences on both SOC and SIC and their relationship, and salinization had adverse effect on soil C storage in the YRD.