In vivo growth and genomic characterization of rickettsia‐like organisms isolated from farmed Chinook salmon (Oncorhynchus tshawytscha) in New Zealand

A rickettsia‐like organism, designated NZ‐RLO2, was isolated from Chinook salmon (Oncorhynchus tshawytscha) farmed in the South Island, New Zealand. In vivo growth showed NZ‐RLO2 was able to grow in CHSE‐214, EPC, BHK‐21, C6/36 and Sf21 cell lines, while Piscirickettsia salmonis LF‐89^T grew in all but BHK‐21 and Sf21. NZ‐RLO2 grew optimally in EPC at 15°C, CHSE‐214 and EPC at 18°C. The growth of LF‐89 ^T was optimal at 15°C, 18°C and 22°C in CHSE‐24, but appeared less efficient in EPC cells at all temperatures. Pan‐genome comparison of predicted proteomes shows that available Chilean strains of P. salmonis grouped into two clusters (p‐value = 94%). NZ‐RLO2 was genetically different from previously described NZ‐RLO1, and both strains grouped separately from the Chilean strains in one of the two clusters (p‐value = 88%), but were closely related to each other. TaqMan and Sybr Green real‐time PCR targeting RNA polymerase (rpoB) and DNA primase (dnaG), respectively, were developed to detect NZ‐RLO2. This study indicates that the New Zealand strains showed a closer genetic relationship to one of the Chilean P. salmonis clusters; however, more Piscirickettsia genomes from wider geographical regions and diverse hosts are needed to better understand the classification within this genus.     

B cell development in gut associated lymphoid tissues

B lymphocyte development can occur in a variety of anatomical sites. While typically considered to be a process that occurs in the bone marrow throughout life, it is becoming clear that gut associates sites of B cell development are critically important in many species of veterinary importance. Among these sites, the bursa of Fabricius in chickens and the ileal Peyer's patches of sheep are among the best studied. In these organs, it has become clear that many of the properties associated with B cell development in rodent and primate bone marrow do not apply. Thus while bone marrow B cell development typically involves an ongoing maturation of mature B cells from immature B lineage precursors that lack the expression of a surface immunoglobulin complex, gut associated lymphoid tissues (GALTs) may be colonized by a single wave of precursor cells during embryo development. Nonetheless, molecular analysis of the requirements for B lymphocyte development in GALTs reveals some striking parallels with requirements identified for B cell development in bone marrow. This article will discuss differences between B cell development in the bone marrow and GALTs and recent evidence emerging that yields insights into how these processes are regulated.     

Urinary catecholamine and metanephrine to creatinine ratios in healthy dogs at home and in a hospital environment and in 2 dogs with pheochromocytoma

BACKGROUND: Measurement of high concentrations of urine catecholamines and metanephrines is useful in diagnosing pheochromocytoma in humans. Stress increases catecholamine excretion in urine. HYPOTHESIS: Stress of a hospital visit increases urinary catecholamine and metanephrine excretion in dogs. ANIMALS: Fourteen clinically normal dogs, 2 dogs with pheochromocytoma. METHODS: Voided urine samples were collected by the owners 7 days before (t-7), during the hospital visit immediately after diagnostic procedures (t0), as well as 1 (t1) and 7 days (t7) after the hospital visit. Urine catecholamine and metanephrine concentrations were measured using high-pressure liquid chromatography and expressed as ratios to urine creatinine concentration. RESULTS: In client-owned dogs epinephrine and norepinephrine ratios at t0 were significantly higher compared with ratios at t7. Metanephrine and normetanephrine ratios at t-7, t0, and t1 did not differ significantly from each other; however, at t7 they were significantly lower compared to values at t-7. In staff-owned dogs no significant differences were detected among the different collecting time points for any variable. Metanephrine and normetanephrine ratios were significantly higher in client-owned dogs compared to staff-owned dogs at t-7, t0, and t1 but not at t7. CONCLUSIONS AND CLINICAL IMPORTANCE: Stress associated with a hospital visit and with the sampling procedure causes increases in urine catecholamine and metanephrine excretion. Urine collection for the diagnosis of pheochromocytoma probably should take place at home after adaptation to the sampling procedure.     

Report on the analyses of mAb reactive with porcine CD8 for the second international swine CD workshop

Based on an analysis of their reactivity with porcine peripheral blood lymphocytes (PBL), only three of the 57 mAbs assigned to the T cell/activation marker group were grouped into cluster T9 along with the two wCD8 workshop standard mAbs 76-2-11 (CD8a) and 11/295/33 (CD8b). Their placement was verified through the use of two-color cytofluorometry which established that all three mAbs (STH101, #090; UCP1H12-2, #139; and PG164A, #051) bind exclusively to CD8⁺ cells. Moreover, like the CD8 standard mAbs, these three mAbs reacted with two proteins with a MW of 33 and 35 kDa from lymphocyte lysates and were, thus, given the wCD8 designation. Because the mAb STH101 inhibited the binding of mAb 76-2-11 but not of 11/295/33, it was given the wCD8a designation. The reactivity of the other two new mAbs in the T9 cluster with the various subsets of CD8⁺ lymphocytes were distinct from that of the other members in this cluster including the standards. Although the characteristic porcine CD8 staining pattern consisting of CD8^low and CD8^high cells was obtained with the mAb UCP1H12-2, a wider gap between the fluorescence intensity of the CD8^low and CD8^high lymphocytes was observed. In contrast, the mAb PG164A, not only exclusively reacted with CD4⁻/CD8^high lymphocytes, but it also failed to recognize CD4/CD8 double positive lymphocytes. It was concluded that this mAb is specific for a previously unrecognized CD8 epitope, and was, thus, given the wCD8c designation. A very similar reactivity pattern to that of PG164A was observed for two other mAbs (STH106, #094; and SwNL554.1, #009). Although these two mAbs were not originally positioned in the T cell subgroup because of their reactivity and their ability to inhibit the binding of PG164A, they were given the wCD8c designation. Overall, five new wCD8 mAbs were identified. Although the molecular basis for the differences in PBL recognition by these mAbs is not yet understood, they will be important in defining the role of CD8⁺ lymphocyte subsets in health and disease.     

Escherichia coli O115 forms fewer attaching and effacing lesions in the ovine colon in the presence of E. coli O157:H7

Escherichia coli O115 has been isolated from healthy sheep and was shown to be associated with attaching-effacing (AE) lesions in the large intestine. Following previous observations of interactions between E. coli O157 and O26, the aim of the present study was to assess what influence an O115 AE E. coli (AEEC) would have on E. coli O157 colonisation in vitro and in vivo. We report that E. coli O115- and O157-associated AE lesions were observed on HEp-2 cells and on the mucosa of ligated ovine spiral colon. In single strain inoculum, E. coli O115 associated intimately with HEp-2 cells and the spiral colon in greater numbers than E. coli O157:H7. However, in mixed inoculum studies, the number of E. coli O115 AE lesions was significantly reduced suggesting negative interference by E. coli O157. Use of the ligated colon model in the present work has allowed in vitro observations to be extended and confirmed whilst using a minimum of experimental animals. The findings support a hypothesis that some AEEC can inhibit adhesion of other AEEC in vivo. The mechanisms involved may prove to be of utility in the control of AE pathovars.     

Osmotic Adjustment in Maize (Zea mays L.): Changes with Ontogeny and its Relationship with Phenotypic Stability

Genetic variation for osmotic adjustment was examined in a group of maize hybrids during vegetative and silking stages. Estimates of osmotic adjustment were derived from measurements of leaf relative water content (RWC) and osmotic potential (Ψ o ) before day-break. The degree of adjustment was estimated from the In RWC/In Ψ o relationship. All cultivars examined showed some degree of osmotic adjustment and significant differences (P < 0.05) were found among them. The utility of measurements in early vegetative stages as a mean of selection for osmotic adjustment in silking stage was established. A positive tendency was observed between osmotic adjustment and phenotypic stability.     

The effect of situational variability in climate and soil, choice of animal type and N fertilisation level on nitrogen leaching from pastoral farming systems around Lake Taupo, New Zealand

Agricultural systems with grazing animals are increasingly under scrutiny for their contribution to quality degradation of waterways and water bodies. Soil type, climate, animal type and nitrogen (N) fertilisation are contributors to the variation in N that is leached through the soil profile into ground and surface water. It is difficult to explore the effect of these factors using experimentation only and modelling is proposed as an alternative. An agro-ecosystem model, EcoMod, was used to quantify the pastoral ecosystem responses to situational variability in climate and soil, choice of animal type and N fertilisation level within the Lake Taupo region of New Zealand. Factorial combinations of soil type (Oruanui and Waipahihi), climate (low, moderate and high rainfall), animal type (sheep, beef and dairy) and N fertilisation level (0 or 60 kg N/ha/yr) were simulated. High rainfall climates also had colder temperatures, grew less pasture and carried fewer animals overall which lead to less dung and urinary N returned. Therefore, even though a higher proportion of N returned ultimately leached at the higher rainfall sites, the total N leached did not differ greatly between sites. Weather variation between years had a marked influence on N leaching within a site, due to the timing and magnitude of rainfall events. In this region, for these two highly permeable soil types, N applied as fertiliser had a high propensity to leach, either after being taken up by plants, grazed and returned to the soil as dung and urine, or due to direct flow through the soil profile. Soil type had a considerable effect on N leaching risk, the timing of N leaching and mean pasture production. Nitrogen leaching was greatest from beef cattle, followed by dairy and sheep with the level of leaching related to urine deposition patterns for each animal type and due to the amount of N returned to the soil as excreta. Simulation results indicate that sheep farming systems with limited fertiliser N inputs will reduce N leaching from farms in the Lake Taupo catchment.     

Sheath-blight resistance QTLS in japonica rice germplasm

Sheath blight (SB), caused by Rhizoctonia solani, is a serious disease of cultivated rice (Oryza sativa L.) for which genetic resistance is in demand by breeders. With the goal of resistance (SBR)-QTL discovery in U. S. japonica breeding material, 197 doubled-haploid lines from a cross between MCR10277 (resistant) and Cocodrie (susceptible) were evaluated in field and greenhouse assays with U. S. and Colombian pathogen isolates and genotyped at 111 microsatellite marker loci. Four SBR QTLs from MCR10277 were identified, together accounting for 47% of field genetic variation. In all trials the strongest effect was provided by a chromosome-9 QTL, qsbr_9.1, but some QTLs differed for U. S. and Colombian R. solani isolates. SBR QTLs coincided with only two of several height or heading-time QTLs, suggesting that the relationship between these developmental traits and SBR is not simple. For the U. S. isolates, a microchamber greenhouse assay revealed the same QTLs as did field inoculation.