Virulence characteristics of Yersinia pseudotuberculosis isolated from breeding monkeys in Japan

Between April 2001 and 2007, 18 Yersinia pseudotuberculosis outbreaks occurred in breeding monkeys at 12 zoological gardens in Japan, and 28 monkeys of 8 species died. A total of 18 Y. pseudotuberculosis strains from the dead monkeys, comprising one strain per outbreak, were examined for serotype and the presence of the virulence genes virF, inv, ypm (ypmA, ypmB and ypmC) and irp2. Of the 18 Y. pseudotuberculosis strains, 7 (38.9%) were serotype 4b, 7 (38.9%) were serotype 1b, and there was one each of serotypes 2b, 3, 6 and 7. All the 18 strains examined harbored virF and inv. Sixteen (88.9%) strains, including the strain of serotype 7, harbored ypmA. However, no strain harbored ypmB, ypmC and irp2.

This study demonstrated that among other pathogenic factors, almost all the Y. pseudotuberculosis isolated from the outbreaks had the ypm gene encoding the superantigenic toxin, YPM. As most of the monkeys who died in those outbreaks originated from South America and other regions, where the presence of the ypm gene have not been reported, YPM might be the cause, or at least the most important factor for, the high mortality of the breeding monkeys infected by Y. pseudotuberculosis in Japan. This is also the first report of a fatal case due to Y. pseudotuberculosis serotype 7 infection in the world.     

Total hip arthroplasty outcomes assessment using functional and radiographic scores to compare canine systems.

A retrospective multi-centre study was carried out in order to compare outcomes between cemented and uncemented total hip arthoplasties (THA). A quantitative orthopaedic outcome assessment scoring system was devised in order to relate functional outcome to a numerical score, to allow comparison between treatments and amongst centres. The system combined a radiographic score and a clinical score. Lower scores reflect better outcomes than higher scores. Consecutive cases of THA were included from two specialist practices between July 2002 and December 2005. The study included 46 THA patients (22 uncemented THA followed for 8.3 +/- 4.7M and 24 cemented THA for 26.0 +/- 15.7M) with a mean age of 4.4 +/- 3.3 years at surgery. Multi-variable linear and logistical regression analyses were performed with adjustments for age at surgery, surgeon, follow-up time, uni- versus bilateral disease, gender and body weight. The differences between treatment groups in terms of functional scores or total scores were not significant (p > 0.05). Radiographic scores were different between treatment groups. However, these scores were usually assessed within two months of surgery and proved unreliable predictors of functional outcome (p > 0.05). The findings reflect relatively short-term follow-up, especially for the uncemented group, and do not include clinician-derived measures, such as goniometry and thigh circumference. Longer-term follow-up for the radiographic assessments is essential. A prospective study including the clinician-derived outcomes needs to be performed in order to validate the outcome instrument in its modified form.     

Identification of QTLs controlling harvest time and fruit skin color in Japanese pear (Pyrus pyrifolia Nakai)

Using an F₁ population from a cross between Japanese pear (Pyrus pyrifolia Nakai) cultivars ‘Akiakari’ and ‘Taihaku’, we performed quantitative trait locus (QTL) analysis of seven fruit traits (harvest time, fruit skin color, flesh firmness, fruit weight, acid content, total soluble solids content, and preharvest fruit drop). The constructed simple sequence repeat-based genetic linkage map of ‘Akiakari’ consisted of 208 loci and spanned 799 cM; that of ‘Taihaku’ consisted of 275 loci and spanned 1039 cM. Out of significant QTLs, two QTLs for harvest time, one for fruit skin color, and one for flesh firmness were stably detected in two successive years. The QTLs for harvest time were located at the bottom of linkage group (LG) Tai3 (nearest marker: BGA35) and at the top of LG Tai15 (nearest markers: PPACS2 and MEST050), in good accordance with results of genome-wide association study. The PPACS2 gene, a member of the ACC synthase gene family, may control harvest time, preharvest fruit drop, and fruit storage potential. One major QTL associated with fruit skin color was identified at the top of LG 8. QTLs identified in this study would be useful for marker-assisted selection in Japanese pear breeding programs.     

Seasonal changes of hormones and muscle enzymes in adult lacustrine masu (Oncorhynchus masou) and sockeye salmon (O. nerka)

The upstream migration of adult anadromous fishes is characterized by physiological changes in responses to reproductive and energetic challenges. This study analyzed the physiological responses of lake-resident anadromous masu salmon (Oncorhynchus masou) and sockeye salmon (O. nerka) to migration in order to determine if these fish might serve as a suitable model for ocean-running populations and to differentiate between physiological responses to reproduction and to exercise-linked aspects of migration. Reproductive (estradiol, testosterone, 11-ketotestosterone, 17α,20β-dihydroxy-4-pregnen-3-one) and metabolically-linked (thyroxine, triiodothyronine) hormones showed similar patterns to ocean-running anadromous populations. White muscle pyruvate kinase, lactate dehydrogenase and malate dehydrogenase decreased with the onset of spawning season while white muscle citrate synthase, β-hydroxyacetyl CoA dehydrogenase, phosphofructokinase and glutamate oxaloacetate transaminase did not, suggesting that the former group of enzymes are responding to reproductive or food intake signals while the second group, which typically change during anadromous migration, may be responding to exercise-linked aspects of migration. This revised version was published online in August 2006 with corrections to the Cover Date.     

Suppression of male reproductive activity by estradiol in goldfish: appearance of infertile males that perform active spawning behavior

Fisheries Science - Estrogenic endocrine-disrupting chemicals are an increasing social concern, as they can reduce the reproductive activity of wildlife. The present study aimed to clarify the...     

Spatiotemporal distribution of Flavobacterium psychrophilum and ayu Plecoglossus altivelis in rivers revealed by environmental DNA analysis

Outbreaks of bacterial cold-water disease (BCWD), caused by Flavobacterium psychrophilum, are widespread in Japan, especially among ayu Plecoglossus altivelis. There are few investigations of F. psychrophilum in river water, and its seasonal distribution has not been clarified. We aimed to identify the spatiotemporal dynamics of F. psychrophilum and ayu to provide information that is useful for establishing a countermeasure for BCWD. Quantitative analysis of environmental DNA (eDNA) was used to clarify the year-round dynamics of ayu and F. psychrophilum. We sampled river water from the Nagara and Ibi rivers in Japan, and conducted monthly water sampling and eDNA quantification. Changes in the eDNA concentration of ayu were consistent with the known life histories of the fish. There was a strong negative correlation between the eDNA concentration of F. psychrophilum and water temperature, suggesting a strong dependence of F. psychrophilum dynamics in the river on water temperature. Furthermore, relatively high eDNA concentrations were recorded for both organisms in early summer and fall, suggesting that ayu is infected with F. psychrophilum during these seasons when experiencing up- and downmigration, respectively.

     

Bayesian QTL mapping for recombinant inbred lines derived from a four-way cross

Recombinant inbred lines (RILs) are created by a cross between inbred lines followed by repeated selfing or sib-mating, which include many different types of new inbred lines with many recombination events on the genome. The phenotype of each RIL can be assessed based on multiple individuals within the same line to reduce non-genetic variability. Therefore, RILs are useful tools for QTL mapping allowing effective detection and fine localization of QTL. Usually only two inbred lines are involved to create RILs. In such two-way RILs, however, there are at most two different alleles at QTL and only QTL segregating between two parental lines can be detected. Recently a new crossing design using multiple founders for creating RILs was proposed in Arabidopsis thaliana and mice, where the genome of each RIL is a mosaic of the genomes from multiple parents. Such multi-way RILs are more useful to improve the efficiency in QTL detection than two-way RILs because of the increased chance of QTL segregation among multiple lines, leading to the successful detection of many QTL. In this paper, we propose a Bayesian method for mapping multiple QTL simultaneously in four-way RILs allowing the inference about the equivalence relationship among the four possible alleles descended from the four founder lines as well as the estimation of QTL locations and effects via a MCMC algorithm. Simulation experiments show that our method has the practical ability to detect QTL and to provide the information of equivalence relationship among alleles at detected QTL using four-way RILs.     

Acoustoelastic effect of wood III: effect of applied stresses on the velocity of ultrasonic waves propagating normal to the direction of the applied stress

Changes in the velocity of ultrasonic waves propagating in wood normal to the direction of applied stresses are discussed. The ultrasonic modes considered here are longitudinal waves and shear waves with particle motion along the direction of the applied stress. The ultrasonic velocities in wood were measured by the sing-around method. From the results of the acoustoelastic experiments in wood, changes in the ultrasonic velocities were expressed as a function of the applied stress. For the shear waves, the ultrasonic velocities decreased with an increase in compressive stress from the initial stress level. On the other hand, the ultrasonic velocities under tensile stress increased with an increase in stress at low stress levels and then gradually decreased with further a increase in the stress. In contrast, the longitudinal wave velocities increased with an increase in compressive stress at low stress levels and then decreased with additional increase in the stress. The wave velocities under a tensile stress decreased with an increase in the stress. The proportional relations between velocities and stresses at low stress levels are confirmed, and acoustoelastic constants were obtained from these relations. Their absolute values were smaller than those reported in previous studies but larger than those of metals. The acoustoelastic effect seemed to be almost equivalent on the sensitivity for stress measurement as the strain-gauge method.Part of this research was presented at the 48th annual meeting of the Japan Wood Research Society, Shizuoka, April, 1998