An estimate of the photosynthetic production of individual trees in a Chamaecyparis obtusa plantation

A Weibull function was used to model the vertical distribution of leaf area of individual trees in a 25-year-old Chamaecyparis obtusa (Siebold & Zucc.) Endl. plantation. The parameter representing the shape of the leaf distribution was independent of tree size. A scale parameter tended to decrease with tree size suggesting a critical minimum height for retention of foliage by trees. On the basis of leaf distribution, the photosynthetic production of individual trees was estimated from the canopy photosynthetic production, which was determined from a model of canopy photosynthesis. The data indicated that the photosynthesis of a tree was proportional to the corresponding tree weight to the power of 1.84. Furthermore, the photosynthetic production varied as the 3/2nd power of total leaf area of the tree. Thus, it was concluded that the photosynthetic production per unit of leaf area, that is, the mean photosynthetic activity of a tree, is proportional to the stem girth at clear length, or the square root of the leaf area of the tree.     

Seasonal change in the temperature coefficientQ 10 for respiration of field-grown hinoki cypress (Chamaecyparis obtusa) trees

The effect of temperature upon nighttime respiration was examined on four different sized sample trees in a 17-year-old hinoki cypress (Chamaecyparis obtusa (Sieb. et Zucc.) Endl.) stand over two years. Seasonal changes inQ ₁₀ values and their responses to mean temperature were investigated. On the basis of the monthly relationships between nighttime respiration (r) and temperature inside a chamber (θ),r=r ₀exp (kθ), theQ ₁₀ value (=exp(10k)) was calculated. TheQ ₁₀ values were high (Q ₁₀≥3.0) in winter when mean air temperature was low, and gradually decreased toward summer (Q ₁₀≤1.5) through spring with increasing temperature. TheQ ₁₀ values were negatively correlated with mean air temperature. The response ofQ ₁₀ values to mean air temperature was described by a single equation, regardless of tree size. This result, which might be characteristic of this species, shows that respiration ofC. obtusa trees is promoted by slight increases of air temperature in winter season. On the other hand, temperature sensitivity of total respiration reduced during growing season when ambient temperature was high. These chaning temperature sensitivity according to seasons may depend on the seasonal change of the ratio of growth respiration to total respiration. It is concluded that changes in temperature due to changing seasons not only change respiration rate, but also change the response of respiration rate to temperature by shiftingQ ₁₀ values.     

Effect of liquid whey feeding on fecal microbiota of mature and growing pigs

The effect of liquid whey feeding on fecal bacteria and their metabolites was assessed in five pregnant sows and 66 growing pigs. Sows were fed a control diet for 4 weeks (control period) followed by the same diet but with whey feeding (5 L/day/pig) for 4 weeks (whey period). One group of growing pigs was given 267 L of whey per pig (whey group), while the other group was not (control group). In both cases, liquid whey was given separately from control diet. Sows in the whey period had feces showing lower pH, lower ammonia concentration, and larger population sizes of total bacteria, lactobacilli and bifidobacteria. The bacterial gene library analysis indicated that Mitsuokella and Megasphaera were more frequently detected, while Clostridium disporicum were detected less frequently in the whey period. Feces from whey‐fed growing pigs showed lower pH than that from control pigs in the early stage of growing. Also, larger populations of total bacteria, lactobacilli and bifidobacteria were recorded in the whey group. From the bacterial gene library analysis, the detection frequency of Lactobacillus reuteri tended to be higher in the whey group. These results indicate that whey feeding influences the hindgut microbiota of pigs, possibly leading to a fermentation shift that is favorable for animal health.     

Deriving the mean mass–density trajectory by reconciling the competition–density effect law with the self-thinning law in even-aged pure stands

The competition–density (C–D) effect law refers to the relationship between mean mass w and density ρ at a particular moment among a set of tree populations grown at a wide range of densities. The self-thinning law refers to the time trajectory of w and ρ in overcrowded stands. Because these two laws have not yet been theoretically harmonised, the aim of this paper is to achieve the unification of the two laws. Under the assumption that the reciprocal equation of the C–D effect in self-thinning stands and the self-thinning equation both hold, the slope of the reciprocal equation becomes the same as that of the self-thinning equation on logarithmic scales as the growth stage progresses. Finally, the reciprocal equation is converted to the w–ρ trajectory, eliminating the biological time from the reciprocal equation. The w–ρ trajectory of stands starting with any initial density has thus been explicitly formulated. Larger values of the relative mortality rate play an important role in relieving the C–D effect and cause the w–ρ trajectory to approach the self-thinning line at an earlier stage of growth. Stands exponentially decreasing in number obey the self-thinning law after a sufficient lapse of biological time, irrespective of their initial densities. Unknown functions, such as the survivorship curve and the ceiling biomass, have been explicitly represented as a function of biological time. The approximate expression for the w–ρ trajectory suitably mimics the time trajectory of mean stem and density in an eastern pine plantation.     

Unchanged Distribution Density of Anionic Sites on the Glomerular Wall in Rats with Active Heymann Nephritis

In various kinds of glomerulonephritis, alteration of anionic charge on the glomerular basement membrane (GBM) and podocytes has been controversial for more than decade. To elucidate the relation between glomerular protein leakage and anionic sites on the glomerular wall, we examined the distribution of anionic sites on the GBM and podocytes of rats with active Heymann nephritis (AHN). Urinalysis for protein levels was conducted, and the kidneys were examined using electron microscopic cytochemistry for the assessment of anionic charge with two cationic probes. The anionic sites on podocytes were decreased in number in the AHN rats; however, the distributions of anionic sites on the GBM were similar in density to those seen in the control animals. From these results, we consider that the decrease in anionic charge density on podocytes might be attributable to protein leakage and that the charge barrier of the GBM is irrelevant to the protein leakage in AHN rats.     

Sex differences in stress responses to transportation in goats: Effects of gonadal hormones

The present study examined sex differences and the involvement of gonadal hormones in stress responses caused by road transportation in Shiba goats. In experiment 1, we investigated the stress responses of males and females to transportation. Plasma levels of cortisol (Cor) significantly increased during 1 h of transportation, and those in females were significantly higher than those in males. Plasma glucose (Glu) and free fatty acid (FFA) levels also increased similarly in both females and males by transportation, and there were no sex differences. Food intake following transportation decreased only in males compared with that in the basal session, in which the animals were not transported. Experiment 2 examined the involvement of gonadal hormones in stress responses to transportation using castrated males. Goats were given cholesterol (Cho), 5α‐dihydrotestosterone (DHT) or 17β‐estradiol (Es). The plasma Cor levels increased during transportation regardless of hormone treatment, and those in DHT treated goats were significantly lower than those in Cho or Es treated animals. Plasma Glu and FFA levels also increased during transportation, regardless of hormone treatment, and there were no differences between treatments. Food intake following transportation was significantly lower than that in the basal session only in goats given DHT. In conclusion, gender affects Cor secretion that is increased by transportation and the decrease of food intake following transportation in Shiba goats, and the major cause of these differences is androgen.     

Molecular Monitoring of the Main Changes in Bacterial Floral Diversity in the Gastrointestinal Tract of a Thoroughbred Foal with Catarrhal Enteritis by Using PCR-DGGE

In this study, the main changes in bacterial floral diversity in the gastrointestinal tract of a Thoroughbred foal were monitored by using polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE). The foal died of catarrhal enteritis of the cecum and large colon. Diarrheal feces and gastrointestinal contents were compared with normal feces. The closest relatives of the bacterium in the samples were Lactobacillus johnsonii (100% similarity), uncultured Bacteroides sp. (92.5% similarity), Bacteroides fragilis (96.3% similarity), and Enterococcus faecium/Enterococcus durans (100% similarity); these were detected by PCR-DGGE using a universal primer set. Monitoring revealed that the numbers of Escherichia coli/Shigella sonnei (97.9% similarity) were significantly higher in the diarrheal feces. Thus, PCR-DGGE is a useful tool for monitoring the main changes in bacterial floral diversity occurring in the gastrointestinal tracts of Thoroughbreds.     

Mechanisms responsible for reduced cardiotoxicity of mitoxantrone compared to doxorubicin examined in isolated guinea-pig heart preparations

We reported previously that doxorubicin, an anticancer agent that has an anthracycline structure, alters Ca2+ releasing and uptake mechanisms in the sarcoplasmic reticulum of myocardial cells. These effects of doxorubicin are apparently related to its cardiotoxicity. Mitoxantrone is a similar anticancer agent with an anthracenedion structure that has been shown to be significantly less cardiotoxic. In the present study, the effects of mitoxantrone on the functions of the sarcoplasmic reticulum were examined in isolated muscle preparations obtained from the guinea-pig heart. In electrically-stimulated left atrial muscle preparations, incubation in vitro for 4 hr with 30 or 100 microM mitoxantrone significantly prolonged the time to the peak of twitch tension, markedly increased the developed tension observed at lower stimulation frequencies, thereby attenuating the slope of positive force-frequency relationships, and increased the postrest contraction observed after a 60-sec quiescent period. In myocytes isolated from ventricular muscles, 30 microM mitoxantrone increased the peak and the size of intracellular Ca2+ concentrations ([Ca2+] i), and prolonged the time to peak [Ca2+]i. In skinned muscle fiber preparations obtained from the left ventricular muscle, 30 muM mitoxantrone significantly increased the caffeine-induced contraction without affecting the Ca2+ sensitivity of contractile proteins. These results suggest that mitoxantrone enhances Ca2+ release from the sarcoplasmic reticulum in isolated atrial muscle preparations obtained from the guinea-pig heart. Apparent enhancement of the sarcoplasmic reticulum functions, in contrast to anthracyclines that has been shown to suppress these functions, seems to explain the relative lack of marked cardiotoxicity of mitoxantrone.