Effects of Ozone and/or Excess Soil Nitrogen on Growth, Needle Gas Exchange Rates and Rubisco Contents of Pinus Densiflora Seedlings

The effects of ozone (O₃) and excess soil nitrogen (N), singly and in combination, on growth, needle gas exchange rates and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) contents of Pinus densiflora seedlings were investigated. One-year-old seedlings were grown in 1.5-L pots filled with brown forest soil with 3 levels of N supply (0, 100 or 300 mg N·L^?1 fresh soil volume). The seedlings were exposed to charcoal-filtered air or 60±5 nL·L^?1 O₃ (8 hours a day) in naturally-lit phytotrons for 173 days from 22 May to 11 November. The exposure to O₃ or high N supply to the soil caused a significant reduction in the dry weights of the seedlings. Although no significant interactive effects of O₃ and excess soil N were detected on the dry weight growth of the seedlings, the whole-plant dry weight of the O₃-exposed seedlings grown in the soil treated with 300 mg N·L^?1 was greatly reduced compared with the control value. Ozone reduced net photosynthetic rate at 350 µmol·mol^?1 CO₂ (A ₃₅₀ ), carboxylation efficiency (CE) of photosynthesis and Rubisco content without a significant change in the gaseous phase diffusive conductance to CO₂ (gs) of the needles. The excess soil N reduced the A ₃₅₀ , CE, gs and Rubisco content of the needles. These results suggest that the reduction in the dry weight growth of Pinus densiflora seedlings induced by the exposure to O₃ and/or excess soil N was caused by reduction in the net photosynthetic rate mainly due to the decrease of Rubisco quantity in the chloroplasts.     

Factors Influencing Early Survival and Growth of Laboratory‐reared Pacific Bluefin Tuna,Thunnus orientalis,Larvae

The collection of fertilized eggs for mass culture of Pacific bluefin tuna (PBT) relies on the spontaneous spawning of broodstock in captivity, and the spawning season of the broodstock is generally from mid‐May to September. The diameter of fertilized eggs from the broodstock decreases during the spawning season. To investigate the influence of three potential factors, the egg diameter (larger or smaller), the rearing water temperature (25 or 28 C), and the aeration rate during the night (strong or weak), on early survival and on growth of PBT larvae, replicate trials were conducted to assess these three factors until 7 d after hatching (d.a.h.). At 7 d.a.h., survival rates of larvae reared with strong nighttime aeration were found by a three‐way ANOVA to be significantly higher than for larvae reared with weak aeration. Furthermore, growth rates of PBT larvae hatched from larger eggs were significantly faster than those from smaller eggs. However, a significant difference in the survival rate was not detected for the factors, egg diameter and rearing water temperature. The results indicate that rearing with strong nighttime aeration significantly improved the early survival of PBT larvae and the egg diameter (a proxy for egg quality) and influenced growth.     

Heritability estimates of fractures in Japanese Thoroughbred racehorses using a non‐linear model

Thoroughbred racehorses are produced by mating small numbers of Arabian stallions and native British mares, and have been improved by selection of horseracing performance for about 300 years. While these improvements led to good performance as racehorses, they exposed horses to numerous medical disorders, aggravated by extensive exercise. Fractures are frequent medical disorders in Thoroughbred racehorses. In this study, fracture heritability was estimated using 3,927 Japanese Thoroughbred racehorses to elucidate the risk of racehorse fractures. The heritability estimates of all examined fractures were low (h² = 0.06), while those of fractures in carpal bone and carpus (carpal bone plus distal radius) were moderate (h² = 0.37, 0.24, respectively). Fracture occurrence age for carpal bone and distal radius was both 3.3 years old and was younger than that for other fractures. These results indicated that a larger proportion of the variation in the studied population was due to genetic factors for carpal fractures than for other fractures, while the fractures at other bones were largely affected by environmental factors, correlated with the athlete period (number year in racing). These findings contribute to develop a management plan for suppressing racehorse fractures and improving horseracing safety.     

Seroepidemiologic studies on Babesia equi and Babesia caballi infections in horses in Jilin province of China

The prevalence of equine piroplasmosis caused by Babesia equi and Babesia caballi in northeast China has remained unknown, although the People's Republic of China is recognized as an endemic country for the diseases. In the present study, we investigated the prevalence of equine piroplasmosis in Jilin province, a part of northeast China. A total of 111 serum samples were taken from horses in eastern Jilin, and examined for diagnosis of B. equi and B. caballi infections by the enzyme-linked immunosorbent assays with recombinant antigens, equi merozoite antigen-1 and P48, respectively. Of the 111 samples, 38 (34%) and 36 (32%) samples were sero-positive for B. equi infection and B. caballi infection, respectively. In addition, 14 (12%) samples were sero-positive for both B. equi and B. caballi infections. These results indicate that equine piroplasmosis is widespread and therefore a cause for serious concern in northeast China.     

A model for explaining genotypic and environmental variation in vegetative biomass growth in rice based on observed LAI and leaf nitrogen content

The objectives of this study are to propose a model for explaining the genotypic and environmental variation in above-ground biomass growth via photosynthesis and respiration processes from transplanting to heading for different rice genotypes grown under a wide range of environments, and to identify the physiological traits associated with genotypic difference in the biomass growth based on model analysis. Cross-locational experiments were conducted with nine different rice genotypes at eight locations in Asia covering a wide climate range under irrigated conditions with sufficient nitrogen application. The crop growth rate observed during the period from transplanting to heading ranged from 3.4 to 19.4 g m⁻² d⁻¹ among the genotypes grown at the eight locations. About one-third of the data sets were utilized for model calibration and the remaining sets were used for model validation. An above-ground biomass growth model was developed by integrating processes of single leaf photosynthesis as a function of stomatal conductance and leaf nitrogen content, growth and maintenance respiration and crop development. To rigorously examine the validity of this process model, measured data were input as external variables for leaf area index (LAI) development and leaf nitrogen content per unit leaf area. The model well explained the observed dynamics in above-ground biomass growth (R² = 0.95*** for validation dataset) of nine rice genotypes grown under a variety of environments in Asia. The model simulation suggested that genotypic difference in the biomass growth was closely related to the difference in the stomatal conductance and leaf nitrogen content, as well as to LAI. This paper proposes the model structure, algorithms and all parameter values contained in the model, and discuss its effectiveness as a component of a more comprehensive model for simulating dynamics of biomass growth, LAI development and nitrogen uptake as a function of genotypic coefficients and environments.     

Growth performance responses to increased tryptophan supplementation in growing barrows fed three different very low crude protein corn and soybean meal-based diets fortified with essential amino acids

Seventy-five individually fed barrows averaging 35 kg were used in a series of three experiments for 6-week growth assays (25 barrows each) to determine the effects of l -tryptophan (Trp) supplementation on growth performance and to establish the lower limits of dietary crude protein (CP) levels. Corn and soybean meal (SBM)-based diets containing 9% (Experiment 1), 10% (Experiment 2), and 11% CP (Experiment 3) fortified with deficient essential amino acids (AAs) except Trp were used as basal diets for each experiment. The experimental diets were supplemented with 0.00%, 0.02%, 0.04%, or 0.06% Trp. A 16% CP corn–SBM-based diet was set as a positive control in each experiment, and feed and water were provided ad libitum. Average daily gain and gain-to-feed ratio improved quadratically (P < 0.05) as supplemented Trp increased in the 9% and 10% CP group, although these positive effects were not observed in the 11% CP group. Because the maximum performance parameters in 9%, 10%, and 11% CP groups were not different from that of the 16% CP positive control group, the marginally reduced level of dietary CP without growth performance being affected appears to be around 9% at most. A potential reduction of nitrogen intake was clearly indicated.     

Structure, allometry, and biomass of plantation Metasequoia glyptostroboides in Japan

We quantified structural features and the aboveground biomass of the deciduous conifer, Metasequoia glyptostroboides (Hu and Cheng) in six plantations in central Japan. In order to derive biomass estimates we dissected 14 M. glyptostroboides trees into three structural components (stem wood, branch wood and foliage) to develop allometric equations relating the mass of these components and of the whole tree to diameter at breast height (DBH). We found robust relationships at the branch and whole tree level that allow accurate prediction of component and whole tree biomass. Dominant tree height was similar within five older (>40 years) plantations (27–33 m) and shorter in a 20-year-old plantation (18 m). Average stem diameter varied from 12.8 cm in the youngest stand to greater than 35 cm in the oldest stand.

Metasequoia have relatively compact crowns distributed over the top 30% of the tree although the youngest stand had the deepest crown relative to tree height (up to 38%). At the individual tree level in older stands, 87% of the aboveground biomass was allocated to the stem, 9% to branch wood and 4% to foliage. We found little difference in the relative distribution of above ground biomass among the stands with the exception of lower foliage biomass in larger diameter trees. Total aboveground biomass of the older stands varied twofold, ranging from a maximum of 450 Mg ha⁻¹ in a 42-year-old stand to a minimum of 196 Mg ha⁻¹ in a 48-year-old stand. Total above ground biomass of the 20-year-old stand was 176 Mg ha⁻¹.     

Comparison of prevalence of Felis catus papillomavirus type 2 in squamous cell carcinomas in cats between Taiwan and Japan

Felis catus papillomavirus (FcaPV), especially type 2 (FcaPV2) is considered as one of the causative agents in squamous cell carcinoma (SCC) in cats. However, our previous study detected FcaPV3 and FcaPV4, but not FcaPV2 in feline SCCs collected in Japan, suggesting that the prevalence of FcaPV2 in SCC may vary depending on geographic locations. To evaluate this hypothesis, two conventional PCR reactions targeting E1 and E7 genes were performed to detect FcaPV2 in feline SCC samples collected in Taiwan and Japan. While 46.9% (23/49) of feline SCC cases from Taiwan were PCR positive for FcaPV2, only 8.6% (3/35) cases from Japan were positive. Our result suggests that the prevalence of FcaPV2 in feline SCCs may depend on the region.