Transpiration and canopy conductance at two slope positions in a Japanese cedar forest watershed

Plant–soil system patterns and processes along a slope are among the greatest causes of uncertainty in estimating watershed-scale transpiration (E). Tree-to-tree and radial variations in xylem sap flux density (F_d), in addition to tree biometrics, were measured over a 2-year period (2005–2006) in two slope stand positions. The areas of interest consisted of an upper slope plot (UP) and a lower slope plot (LP) in a Japanese cedar (Cryptomeria japonica D. Don) forest watershed and the environmental controls of stand E for each plot were compared. Canopy stand E (E_C) and canopy stomatal conductance (G_C) in the UP were less than those in the LP during the growing season, while those in the UP were greater than those in the LP over winter. In addition, mean stand F_d (J_S) in the UP was greater than that in the LP over winter, but J_S values were similar in the UP and LP except in the winter, which allows us to extrapolate watershed-scale E based on J_S estimated from F_d measurements of a partial stand in the watershed. However, this relationship contains a bias and differed between 2005 and 2006. Although there were significant differences in soil moisture conditions between the UP and LP in both years, a systematic relationship between the similarity in J_S and soil moisture conditions was not found. The bias was due to a tendency for J_S in the LP to be greater than that in the UP in 2006. This tendency was amplified because J_S in the LP was greater than that in the UP around an atmospheric humidity deficit (D) of 1–1.5 kPa and frequencies of this D range were higher in 2006 than in 2005. The greater J_S in the LP at D  1–1.5 kPa could be explained by the difference in the response of G_C to D between the UP and LP. Our results suggest this to be the cause of the similarity in J_S values for the UP and LP and for the occasional abortion of its similarity. However, even when the bias or the occasional deviation is disregarded, the error in estimating stand E from a partial stand is so small that it is comparable to an F_d measurement error. For example, the error when using only the LP was 6.6% for stand E.     

Seasonal changes of azimuthal,radial, and tree-to-tree variations in sap flux affect stand transpiration estimates in a <Emphasis Type="Italic">Cryptomeria japonica</Emphasis> forest,central Taiwan

Stand transpiration (E) estimated using the sap flux methods is affected by the azimuthal, radial, and tree-to-tree variations of sap flux. Although several studies have examined the relative importance of the three variations in estimating E, the seasonality of the three variations remains unknown. In the current study, we attempted to clarify whether the relative importance of these three variations could show seasonal changes. Using sap flux data measured in a subtropical cloud forest from August 2010 to July 2011, we calculated the differences resulting from omitting the three variations in estimating E. The effects of the three variations in estimating E showed seasonality. The azimuthal and tree-to-tree variations were more pronounced during winter, whereas the radial variation was more pronounced during summer. However, the effect of tree-to-tree variation was consistently much larger than the other two variations throughout the study period. The tree-to-tree variation is more important in estimating E monthly, seasonally and annually than both the azimuthal and radial variations, although all three variations have shown seasonality. In addition, the sensor allocation for summer would be acceptable for the practical estimation of E if aiming at the long time scale.     

Expression of interleukin-18 receptor mRNA in the mouse endometrium

Interleukin-18 (IL-18) is a proinflammatory cytokine involved in chronic inflammation, autoimmune diseases, and a variety of cancers, and is expressed in mouse uteri. Our previous study suggested that IL-18 acts as a paracrine factor, regulating endometrial function. To elucidate the physiological roles of IL-18 in the mouse endometrium, the expression of the IL-18 receptor (IL-18R) alpha subunit was analyzed. IL-18Ralpha mRNA was expressed in several mouse organs in addition to the endometrium. In situ hybridization analysis using a biotin-labeled mouse IL-18Ralpha riboprobe demonstrated that IL-18Ralpha mRNA expression was detected in glandular epithelial cells, stromal cells around uterine glands, and myometrial cells in the mouse uterus, suggesting that these cells are targets for IL-18. The uterine IL-18Ralpha mRNA expression level changed with the estrous cycle. The uterine IL-18Ralpha mRNA levels of estrous mice were higher than those of diestrous mice. In addition, the IL-18Ralpha mRNA levels in uteri at 3 and 14 days after ovariectomy were higher than those at diestrus and decreased following treatment with estradiol-17beta or progesterone. These findings suggest that IL-18Ralpha gene expression is regulated by estrogen and progesterone and that the uterine IL-18 system is involved in the regulation of uterine functions in a paracrine manner.     

Ecological studies of Yersinia enterocolitica. II. Experimental infection with Y. enterocolitica in pigs

Fattening pigs were inoculated with the human pathogenic strains of Yersinia enterocolitica, biovar 4 serovar 3 phagovar 8 and biovar 2 serovar 5.27. Each pig received 2.6 × 10⁹ organisms by catheter into the stomach and thereafter 10% sodium bicarbonate solution, by the same route. The serovar 3 strain became established in the intestines of four out of six 11-week-old pigs and in all three 24-week-old pigs. Serovar 5.27 established in the intestines of all four 10-week-old pigs. In these pigs, both serovars were excreted in the feces at 10²?10⁶ cells g^?1 for a few weeks. However, the serovar 5.27 was excreted in the feces at less than 10^3·3 cells g^?1 for 2 weeks by 24-week-old pigs. Horizontal transmission with the serovar 5.27 strain was observed on the 5th–11th day, and the bacteria were present in the intestines during the 2nd week. However, the serum titers to O-agglutinin were 1/10 and less, but in one pig, the titer was 1/40 against serovar 5.27 strain.     

Pathogenicity for chickens of avian influenza viruses isolated from whistling swans and a black-tailed gull in Japan

We isolated 24 Hav1 Neq1 and 18 Hav6 Nav3 influenza viruses from such free-living wild waterfowl as whistling swans, black-tailed gulls, and tufted ducks in western Japan in 1980. Two Hav1 Neq1 viruses isolated from a whistling swan and a black-tailed gull and a Hav6 Nav3 virus from a whistling swan were examined for their pathogenicity for chickens. Five-week-old specific-pathogen-free chickens were inoculated with the viruses intratracheally or intraperitoneally. Virus was recovered successfully from all the organs, including the brain, despite the absence of signs of disease. The intracerebral pathogenicity index scores obtained for the Hav1 Neq1 viruses were 0.43 and 0.87; the score for the Hav6 Nav3 virus was 0.43. No virus produced plaques in cultivated chick embryo fibroblast cells in the absence of trypsin.     

Involvement of the fas ligand and fas system in apoptosis induction of mouse uterine natural killer cells

Uterine natural killer (uNK) cells in the pregnant uterus are known to be associated with the normal development of the placenta. In the mouse pregnant uterus, many uNK cells exist during mid pregnancy, although they show a sudden decrease during late pregnancy and almost disappear before delivery. Our previous study indicated that uNK cells showed clear apoptotic morphology during late pregnancy. Therefore, the present study was carried out to define the involvement of Fas ligand (FasL) and Fas in apoptosis induction of uNK cells. Immunohistochemical analyses revealed that uNK cells expressed FasL in the cytoplasmic granules and Fas on the cell membrane during late pregnancy. In lpr/lpr mice, which genetically lack Fas, many uNK cells were clearly observed during late pregnancy compared with wild-type mice, and moreover uNK cells still existed at day-18 of pregnancy, although there were few in wild-type mice during the same period. In the experiment of in vitro culture, uNK cells derived from wild-type placenta showed chromatin condensation and DNA fragmentation frequently following the anti-Fas antibody treatment, as compared with the control. From these results, it is suggested that FasL and Fas-dependent apoptosis regulates cell appearance of uNK cells in the mouse pregnant uterus.     

Genetic alterations of KIT during clonal expansion and subsequent acquisition of resistance to toceranib in a canine mast cell tumor cell line

One of the potential mechanisms underlying acquired resistance to toceranib in canine mast cell tumor (MCT) is the emergence of a secondary mutation in the KIT gene. Here, genetic alterations of KIT during clonal expansion and subsequent acquisition of resistance to toceranib were investigated in the toceranib‐susceptible canine MCT cell line VI‐MC, which carries a KIT‐activating mutation resulting in a predicted p.(Asn508Ile) amino acid change in the receptor tyrosine kinase protein KIT. Two sublines were cloned from VI‐MC and toceranib‐resistant sublines then were established by continuous exposure to toceranib. The mutation status of KIT in parental VI‐MC and its sublines was investigated using next‐generation sequencing (NGS). Additionally, effects of secondary mutations on toceranib sensitivity in p.(Asn508Ile)‐mutant KIT were examined. KIT secondary mutations, including those encoding p.(Asn679Lys)‐, p.(Asp819Val)‐, and p.(Asp819Gly)‐mutant KIT, that confer toceranib insensitivity to p.(Asn508Ile)‐mutant KIT emerged only in toceranib‐resistant VI‐MCs. These mutations were not detected by NGS in the parental VI‐MC line or in the toceranib‐naive cloned VI‐MCs, although the parental line and sublines exhibited genetic heterogeneity in KIT that may have been caused by genetic evolution during clonal expansion. VI‐MC clones with these secondary mutations in KIT appear to have arisen from subclones during treatment with toceranib rather than being pre‐existing. However, further study using a higher resolution technique will be needed to confirm the developmental mechanism of KIT secondary mutation in canine MCT cells with acquired resistance to toceranib.     

Rainfall interception in a moso bamboo (Phyllostachys pubescens) forest

In recent years, moso bamboo (Phyllostachys pubescens) forest areas in Japan have rapidly expanded, and bamboo is now invading nearby natural or plantation forests. To date, only one study has examined the rainfall interception of a moso bamboo forest. In that study, it was reported that the interception ratio (interception/rainfall) of the bamboo forest did not exceed the interception ratios of other natural and plantation forests (n = 4) in Japan. To expand the current state of knowledge about rainfall interception of bamboo forests, we measured throughfall and stemflow at another bamboo forest site. Annual rainfall (Rf), throughfall (Tf), and stemflow (Sf) during the measurement period were 2,105, 1,556, and 322 mm, respectively. Annual rainfall interception at the plot (I) was 228 mm. Tf/Rf, Sf/Rf, and I/Rf were 73.9, 15.3, 10.8%, respectively. I/Rf was less than 20% throughout the year except in October, the month with lowest rainfall. We also summarized rainfall interception data from 19 other natural and plantation forests. The I/Rf value of our site did not exceed the I/Rf values of these natural and plantation forests (n = 19). Our data will be useful for assessing changes in water resources that result from replacement of natural or plantation forests by bamboo forests.     

Combination reaction between humic acid and calcium ions

In the previous paper (1), liming an acid humus volcanic ash soil resulted in the formation of humic acids combined with calcium, but had no significant effect on acid brown forest soils containing humic acids of a lower degree of humification. Subsequently, the authors examined the humus composition of the soils treated with calcium acetate, and conducted some experiments on the combination reaction between humic acid and calcium ions. The results obtained are presented in this paper.     

Mineralization of physically fractionated rotten plant residues under upland conditions

A well-rotten mixture of rice straw and calcium cyanamide (rice straw compost prepared indoors) was separated physically into four fractions using a combination of methods which involved sieving, sedimentation and centrifugation. The four fractions obtained were Fl-3 (>0.043 mm), F4 (sedimented at 4°C), F5 (sedimented by centrifugation at 10⁴ × g for 10 min) and F6 (supernatant). The air-dried and pulverized fractions were mixed with upland soils and incubated for 4 weeks at 30°C under upland conditions. The amount of nitrogen mineralized in each fraction was determined, In a red yellow soil, 11.2% of the organic nitrogen present in the unfractionated, air-dried sample was mineralized, compared with 6.8% in volcanic ash soil. The contribution of fraction F5 to the total amount of mineralized nitrogen in wet compost was the highest, followed by F6. Fraction Fl-3 showed immobilization of inorganic nitrogen in both soil types. On the other hand, fractionated samples obtained after air-drying the wet compost showed no immobilization for Fl-3, although the values obtained for other fractions were similar to those obtained for the corresponding fractions of wet compost.

Well-rotten plant residues such as rice straw (compost prepared outdoors), Timothy and Ladino clover were air-dried, then separated into fractions and analyzed for elementary composition as well as inorganic nitrogen content using the same procedures. Although the amounts of mineralized nitrogen were higher in fractions F5 and F6 compared with other fractions, the values were much lower compared with those of undecomposed plant residues.

It was found that the amount of organic nitrogen mineralized in soil was affected not only by the C/N ratio of the plant residues but also by the differences in characteristics or properties of the plant materials and soils.