Empirical Percentile Growth Curves with Z-scores Considering Seasonal Compensatory Growths for Japanese Thoroughbred Horses

Percentile growth curves are often used as a clinical indicator to evaluate variations of children’s growth status. In this study, we propose empirical percentile growth curves using Z-scores adapted for Japanese Thoroughbred horses, with considerations of the seasonal compensatory growth that is a typical characteristic of seasonal breeding animals. We previously developed new growth curve equations for Japanese Thoroughbreds adjusting for compensatory growth. Individual horses and residual effects were included as random effects in the growth curve equation model and their variance components were estimated. Based on the Z-scores of the estimated variance components, empirical percentile growth curves were constructed. A total of 5,594 and 5,680 body weight and age measurements of male and female Thoroughbreds, respectively, and 3,770 withers height and age measurements were used in the analyses. The developed empirical percentile growth curves using Z-scores are computationally feasible and useful for monitoring individual growth parameters of body weight and withers height of young Thoroughbred horses, especially during compensatory growth periods.     

Clarification of relationship between single-nucleotide polymorphism panels of Shiga toxin-producing Escherichia coli O157:H7/H- strains

Eighty strains of enterohemorrhagic Escherichia coli O157:H7/H- were analyzed by three single-nucleotide polymorphism (SNP) panels using whole-genome sequencing data. The partial concordance of SNP types among the different SNP panels was observed on minimum spanning trees reconstructed with SNP data. As for lineage I/II strains, some of the clade 7 strains belonged to one unique SNP type as determined by three panels, suggesting that clade 7 should be divided into at least two genotypes, namely, the unique type and the rest. In addition, clade 8 contained two unique genotypes, which was consistent with the previous prediction. Similarly, for lineage II, clade 12 should be divided into three genotype strains. In contrast, many strains of several clades belonging to lineage I were clustered into the same node on each minimum spanning tree upon testing with the three SNP panels. Previous studies reported that lineage I diverged more recently than lineages I/II and II. Such low diversity in lineage I in this study may have arisen because this lineage has not accumulated SNPs because of its relatively recent divergence. Based on the concordance observed in this study, some of the previously published O157 genotype distribution data were successfully interpreted to clarify the clade distribution, which was well supported by previous literature.     

Effects on the Local Immunity in the Testis by Exposure to Di-(2-ethylhexyl) Phthalate (DEHP) in Mice

Exposure to di-(2-ethylhexyl) phthalate (DEHP) has been reported to induce spermatogenic disturbance through oxidant stress and affect the immune system as an adjuvant. However, the effect of DEHP on the testicular immune microenvironment has not yet been investigated. In the present study, we examined the testicular immune microenvironment after exposure to doses of DEHP, previously identified as no-observed-adverse-effect levels. Adult male mice were administered food containing 0%, 0.01% or 0.1% DEHP and then testes were analyzed. The results showed that a slight but significant spermatogenic disturbance appeared in the 0.1% DEHP group but not in the 0.01% DEHP group at 8 weeks. It was also demonstrated that lymphocytes and F4/80- and MHC class II- positive cells were significantly increased with the elevation of IL-10 and IFN-γ mRNA expressions in the testes of not only the 0.1% DEHP group but also the 0.01% DEHP group at 8 weeks. Histochemical analyses involving horseradish peroxidase (HRP) as a tracer showed that a little blood-borne HRP had infiltrated into the lumen of a few seminiferous tubules beyond the blood-testis-barrier in both the 0.1% and 0.01% DEHP groups at 8 weeks. This indicates that a dose of DEHP that has little effects on spermatogenesis can change the testicular immune microenvironment with functional damage of the blood-testis barrier.     

Transmission of extended-spectrum cephalosporin-resistant Salmonella harboring a blaCMY-2-carrying IncA/C2 plasmid chromosomally integrated by ISEcp1 or IS26 in layer breeding chains in Japan

Dissemination of extended-spectrum cephalosporin (ESC)-resistant Salmonella is a public health concern in the egg production industry. ESC-resistant Salmonella often acquires the bla gene via insertion sequences (ISs). Therefore, this study aimed to assess antimicrobial resistance in Salmonella from Japanese layer breeding chains and egg processing chains, and determine the genetic profiles of IS-like elements in ESC-resistant Salmonella. Antimicrobial susceptibility testing was performed on 224 isolates from 49 facilities involving layer breeder farms, hatcheries, pullet-rearing farms, and layer farms in breeding chains along with egg processing chains. ESC-resistant Salmonella strains were whole-genome sequenced. Among them, 40 (17.9%) were resistant to at least streptomycin, tetracycline, ampicillin, chloramphenicol, cefpodoxime, nalidixic acid, ciprofloxacin, and/or kanamycin despite lacking resistance to azithromycin and meropenem. Moreover, 15 were ESC-resistant Salmonella harboring bla_CMY-2 (Salmonella enterica serovar Ohio, n=12; S. Braenderup, n=1; untypeable with O7:b:-, n=1) and bla_CTX-M-14 (S. Cerro, n=1). IncA/C₂ plasmids containing ISEcp1, IS26, and multiple antimicrobial resistance genes (including bla_CMY-2) were identified in S. Ohio isolates from pullet-rearing and layer farms belonging to the same company. Chromosomal integration of partial or whole IncA/C₂ plasmids was seen with two S. Ohio isolates via ISEcp1 or IS26, respectively. Antimicrobial resistance genes such as bla_CMY-2 might be transmitted among the upper and the lower levels of layer breeding chains via the replicon type IncA/C₂ plasmids containing ISEcp1 and IS26.     

Histopathological findings of the nasopharynx-associated lymphoid tissue of pigs co-infected with porcine circovirus 2 and porcine reproductive and respiratory syndrome virus

Porcine circovirus 2 (PCV2) causes porcine circovirus-associated disease, and co-infection with porcine reproductive and respiratory syndrome virus (PRRSV) severely affects the pig breeding industry. Both viruses target the macrophages in lymphoid tissues. Various porcine pathogens enter via the nasal cavity, and the nasopharynx-associated lymphoid tissue (NALT) acts as the mucosal immune system. However, the pathological analysis has not progressed. This study aimed to histologically examine the NALT of pigs with suspected PCV2 and PRRSV infections. Six pigs were subjected to necropsy, and their NALT, tonsils, and mesenteric lymph nodes were collected. Macrophages, lymphocytic depletion, multinucleated giant cells, intracytoplasmic inclusion bodies, and neutrophil infiltration increased in the NALT. In situ hybridization revealed positive signals for PCV2 in the NALT of all pigs and PRRSV in the NALT of three pigs. PCV2-positive macrophages were mainly identified in the follicles, whereas PRRSV-positive tissues were found primarily around the crypt and directly below the epithelium. Quantitative PCR revealed 10⁸–10¹⁰ copies of PCV2 DNA/µL and 10²–10⁴ copies of PRRSV DNA/µL in the NALT. Therefore, both PCV2 and PRRSV were detected in the NALT of pigs. In conclusion, the infection and replication of both viruses in the NALT and tonsils may suppress host immunity and promote co-infection with other pathogens.     

Empirical Growth Curve Estimation Using Sigmoid Sub-functions that Adjust Seasonal Compensatory Growth for Male Body Weight of Thoroughbred Horses

Thoroughbred horses are seasonal mating animals, raised in northern regions or countries. Foals born yearly in spring generally show a typical seasonal compensatory growth pattern, in which their growth rate declines in the first winter and increases in the next spring. In this study, a new empirical adjustment approach is proposed to adjust for this compensatory growth when growth curve equations are estimated, by using 1,633 male body weights of Thoroughbreds as an illustrating example. Based on general Richards growth curve equation, a new growth curve equation was developed and fit to the weight-age data. The new growth curve equation had a sigmoid sub-function that can adjust the compensatory growth, combined with the Richards biological parameter responsible for the maturity of animals. The unknown parameters included in the equations were estimated by SAS NLMIXED procedure. The goodness of fit was examined by using Akaike’s Information Criterion (AIC). The AIC values decreased from 13,053 (general Richards equation) to 12,794 (the newly developed equation), indicating the better fit of the new equation to the weight-age data. The shape of the growth curve was improved during the period of compensatory growth. The proposed method is one of the useful approaches for adjusting seasonal compensatory growth in growth curve estimations for Thoroughbreds, and for their management during the compensatory period. Based on this approach, the optimal growth curve equations can be estimated also for female body weight of Thoroughbreds or other growth traits affected by seasonal compensatory growth.