Nitrogen isotope fractionation during nitrogen transport from ectomycorrhizal fungi,Suillus granulatus,to the host plant,Pinus densiflora

The ¹⁵N natural abundance in Pinus densiflora Sieb. et Zucco that had been inoculated and not inoculated with ectomycorrhizal fungi (Suillus granulatus (L.:Fr.) O. Kuntze) was compared. The inoculated pine needles showed a lower δ¹⁵N value, while the uninoculated ones showed a higher δ¹⁵N value. Higher δ¹⁵N values in the mycelial mat of the ectomycorrhizal fungi compared to those of the inoculated pine needles were also observed. These facts indicate that nitrogen isotope fractionation occurred during the nitrogen transport from mycorrhizal fungi to the host plants.     

Effect of nitrogen deposition on CH4 uptake in forest soils in Hokkaido,Japan

Abstract

It has been well documented by short-term artificial experiments that the CH⁴ uptake is inhibited by N input, especially NH^{4 p+}-N input. To investigate the effect of the natural N input by throughfall and other factors on the CH⁴ uptake in forest soils, we measured the CH⁴ uptake rates for 6 months during the snow-free period of the year and N input by throughfall throughout the year at 10 sites in Hokkaido, Japan, from 1997 to 2002. Water filled pore space (WFPS) and pH values in the soils varied widely among the sites (38-93% and 3.9-6.2, respectively). The rates of NH^{4 p+}-N and NH^{3 p-}-N inputs ranged from 1.3 to 6.9 kg N ha^p-1 year^p-1 and from 0.8 to 2.9 kg N ha^p-1 year^p-1, respectively. The NH^{4 p+}-N input was generally higher than the NH^{3 p-}-N input. Total N input by throughfall amounted to 2.3-9.4 kg N ha^p-1 year^p-1. The highest CH⁴ uptake rate occurred within the period from July to September (41-215 μg CH⁴ m^p-2 h^p-1) each year at most sites. CH⁴ uptake rate was relatively low (~50 μg CH⁴ M-2 h^p-1) at northern sites, while a high CH⁴ uptake rate was observed throughout the year 100 (? CH⁴ m^p-2 h^p-1) at southern sites. The mean CH⁴ uptake rates were significantly different among the sites. Cumulative CH⁴ uptake ranged from 1.4 to 6.6 kg CH⁴ ha^p-1 [184 d]^p-1 with a mean values of 3.22 ± 1.36 kg CH⁴ ha^p-1 [184 d]^p-1. Cumulative CH⁴ uptake increased with increasing temperature and decreased with an increase in precipitation (Rain), NH^{4 p+}-N input (TF^NH4) WFPS, soil total C (TC), and total N (TN). There was a quadratic relationship between the CH⁴ uptake and NH^{3 p-}-N input (TF^NO3), soil pH, and C / N ratio in soil. A regression equation was obtained as follows to predict the CH⁴ uptake in forest soils: Cumulative CH⁴ uptake = 0.47 / Rain + 0.38 / TF^NH4 + 0.34 / TC - 0.30 / TF^N03 (R ^p2 = 0.74, p = 0.0001). This equation indicates that atmospheric N input into forest soils is one of the main factors that control cumulative CH⁴ uptake with precipitation, total carbon content in soil in Hokkaido, Japan.     

Clinical assessment of systolic myocardial deformations in dogs with chronic mitral valve insufficiency using two-dimensional speckle-tracking echocardiography

ObjectiveThe objective of this study was to clinically assess myocardial deformations in dogs with chronic mitral valve insufficiency (CMVI) using two-dimensional speckle-tracking echocardiography (2D-STE).Animals87 dogs with CMVI.MethodsDogs were placed into 1 of 3 classes, based on the International Small Animal Cardiac Health Council classification. In addition, 20 weight- and age-matched healthy dogs were enrolled as controls. The dogs were examined for myocardial deformations using 2D-STE, and strain and strain rate in the longitudinal, circumferential, and radial directions were evaluated.ResultsClass II and III dogs had higher circumferential strain than class I dogs (P = 0.002 and P = 0.001, respectively) and controls (P < 0.001 and P < 0.001, respectively). Class III dogs had higher radial strain than class I dogs (P = 0.001) and controls (P < 0.001). Class III dogs had higher radial strain rate than class I dogs (P = 0.006) and controls (P = 0.001). Other deformations, including longitudinal deformations, were not significantly different between classes of CMVI or between CMVI dogs and controls.ConclusionsIn the clinical progression of CMVI in dogs, myocardial deformations, as assessed by 2D-STE, differed according to myocardial contractile direction. Thus, assessments of multidirectional myocardial deformations may be important for better assessment of clinical cardiac function in dogs with CMVI.     

Effect of age on myocardial function assessed by two-dimensional speckle-tracking echocardiography in healthy beagle dogs

ObjectivesThe objective of this study was to evaluate the effect of age on myocardial function assessed by two-dimensional speckle-tracking echocardiography (2D-STE) in healthy dogs.AnimalsThirty-two healthy Beagles were used.MethodsMyocardial function was assessed in each dog by using 2D-STE, and the results were compared between young and old dogs.ResultsThe myocardial deformations in systole, besides the apical rotation rate, were not significantly different between young and old dogs. In contrast, the early diastolic circumferential strain rate, basal rotation rate, and torsion rate were significantly lower in old dogs than in young dogs (P = 0.03, P = 0.033, and P = 0.015, respectively). Late diastolic longitudinal and radial strain rates were significantly higher in old dogs than in young dogs (P = 0.002 and P = 0.018, respectively).ConclusionsYoung and old dogs showed similar systolic myocardial deformations, but significant differences in the values of some diastolic deformation variables were found between young and old dogs, highlighting the need for using age-matched control subjects in studies of diastolic function.     

Immunologic Profiles of Peripheral Blood Leukocytes and Serum Immunoglobulin G Concentrations in Perinatal Mares and Neonatal Foals (Heavy Draft Horse)

The purpose of this study was to examine sequential changes in the immunologic parameters of perinatal mares and neonatal foals of the heavy draft horse. Blood samples were collected from clinically healthy pregnant mares and their newborn foals every week from 1 month before the expected foaling date, and 1 hour, 1 day (24-48 hours), and 1, 2, 3, and 4 weeks after foaling. Peripheral blood samples were used to examine total leukocyte counts (n = 20), differential leukocyte counts (n = 20), lymphocyte subpopulations (n = 13), lymphocyte responses to mitogens (n = 10), neutrophil phagocytic function (n = 12), and serum immunoglobulin G (IgG) concentrations (n = 10). In perinatal mares, remarkable changes observed included increased neutrophils, decreased lymphocytes, decreased CD4⁺ T lymphocytes, and decreased lymphocyte responses to mitogens at delivery. These changes were speculated to be the result of physical stress associated with delivery. In neonatal foals, increase in the phagocytic function of neutrophils, and increase in serum IgG concentration after suckling colostrum and increase of lymphocytes accompanied by physiologic growth were observed. Compared to dams, foals showed lower phagocytic function of neutrophils before suckling and fewer lymphocytes and lower lymphocyte responses to mitogens within 1 day after birth. This study revealed immunologic dynamics in perinatal mares and neonatal foals. Immunologic functions are suppressed in foaling mares and are immature in neonatal foals, especially before colostral intake. We expect these data will be useful for further studies in the field of clinical immunology, and preventive medicine.     

Factors Affecting Gestation Length in Heavy Draft Mares

The purpose of this study was to examine the factors affecting gestation length in 209 foalings from 65 heavy draft horses by multiple linear regression analysis. The objective variable was gestation length, and the explanatory variables were stud farm, year foaled, month foaled, age of mare, parity of mare, last gestation length, foal gender, and some meteorological parameters (the mean values of prepartum 10 days: maximum temperature, minimum temperature, average barometric pressure, and hours of sunshine in a day). The mean gestation length for 209 foalings was 334.9 (standard deviation = 8.3) days, with a range of 313-352 days. Stepwise regression analysis showed that last gestation length and foal gender had significant (P < .01) effects on gestation length. Multiple regression analysis showed that last gestation length (standard partial regression coefficient = 0.54) was more influential on the present gestation length than foal gender (standard partial regression coefficient = 0.22). The present gestation length and the last gestation length were moderately positively correlated (r = 0.56, P < .01). Colt foal (n = 106) pregnancies were significantly (P < .01) longer than fillies (n = 103) (mean ± SEM: colt 337.1 ± 0.7 vs. filly 332.7 ± 0.9). According to our results, last gestation length (mare itself) and foal gender were the main factors affecting gestation length in heavy draft horses. Once several gestation lengths are known, predictions with acceptable accuracy can be made about the gestation length of that mare's following foaling.     

Hepatocellular carcinoma in a young dog

A 25-month-old Chihuahua dog with no clinical signs was evaluated for high serum liver enzymes. Ultrasonography and computed tomography revealed a mass in the left hepatic medial lobe. The histological diagnosis reached using resected tissues was hepatocellular carcinoma (HCC). To the authors’ knowledge, this is the youngest dog diagnosed with HCC.     

Response of cholecystokinin and digestive enzyme mRNA levels to various feed ingredients in yellowtail Seriola quinqueradiata

Cholecystokinin (CCK) is the key regulator hormone that stimulates the secretion of digestive pancreatic enzymes in vertebrates. In fish, little is known about the mechanism of induction of CCK in the digestive tract by feed ingredients. To investigate the response of CCK and digestive enzymes to fish feed ingredients in yellowtail Seriola quinqueradiata, we performed a number of experiments in which we measured the mRNA levels of CCK, trypsin, and lipase after oral administration of a single bolus of the ingredients. We administered fish meal and fish oil in experiment 1; high and low concentrations of fish meal in experiment 2; and five different dietary protein sources (fish meal, soybean meal, soy protein concentrate, corn gluten meal, and glutamic acid fermentation by-products) in experiment 3. In experiments 1 and 3, only fish meal significantly increased the mRNA levels of CCK and digestive enzyme. In experiment 2, a high concentration of fish meal [20?% (w/v)] significantly increased CCK and trypsin mRNA levels, but a low concentration of fish meal [1?% (w/v)] did not. These results suggest that high concentrations of fish meal (the protein source in fish feed) has the most potent effect on stimulation of CCK synthesis and secretion of digestive enzymes in yellowtail.     

Utilization patterns of estuarine and marine habitats by the halfbeak Zenarchopterus dunckeri at Iriomote Island,southern Japan,evaluated from otolith microchemistry

Estuarine and marine habitat use patterns in the halfbeak Zenarchopterus dunckeri were examined at Iriomote Island, southern Japan, by analyzing otolith Li/Ca and Sr/Ca ratios. The ranges of both Li/Ca and Sr/Ca ratios in juvenile Z. dunckeri from the maximum (30 psu) to minimum (0.5 psu) salinity levels of brackish water estimated from rearing experiments, were compared with those of wild individuals collected from upstream and downstream stations in the Urauchi River estuary. The majority of wild-caught individuals had invariable Li/Ca and Sr/Ca ratios along an otolith transect from the core to the posterior edge, which fell within the otolith Li/Ca and Sr/Ca ranges estimated for estuarine individuals in the rearing experiments, suggesting that such individuals developed within the estuary without migrating to a marine environment at any time, although some downstream-dwelling fish had higher otolith elemental ratios than the predetermined estuarine ranges in the mid transect section. The latter fish may have been accidentally flushed from the estuary into the sea by heavy flood events, subsequently returning to the estuary. The overall results suggested that Z. dunckeri is essentially an estuarine resident, completing its life cycle within an estuarine system.