Patchy stomatal behavior during midday depression of leaf CO₂ exchange in tropical trees     

Kamakura M  Kosugi Y  Takanashi S  Matsumoto K  Okumura M  Philip E 《Tree physiology》2011,31(2):160-168

We investigated effects of heterogeneous stomatal behavior on diurnal patterns of leaf gas exchange in 10 tree species. Observations were made in middle and upper canopy layers of potted tropical rainforest trees in a nursery at the Forest Research Institute Malaysia. Measurements were taken from 29 January to 3 February 2010. We measured in situ diurnal changes in net photosynthetic rate and stomatal conductance in three leaves of each species under natural light. In both top-canopy and sub-canopy species, midday depression of net assimilation rate occurred in late morning. Numerical analysis showed that patchy bimodal stomatal behavior occurred only during midday depression, suggesting that the distribution pattern of stomatal apertures (either uniform or non-uniform stomatal behavior) varies flexibly within single days. Direct observation of stomatal aperture using Suzuki's Universal Micro-Printing (SUMP) method demonstrated midday patchy stomatal closure that fits a bimodal pattern in Shorea leprosula Miq., Shorea macrantha Brandis. and Dipterocarpus tempehes V.Sl. Inhibition of net assimilation rate and stomatal conductance appears to be a response to changes in vapor pressure deficit (VPD). Variable stomatal closure with increasing VPD is a mechanism used by a range of species to prevent excess water loss from leaves through evapotranspiration (viz., inhibition of midday leaf gas exchange). Bimodal stomatal closure may occur among adjacent stomata within a single patch, rather than among patches on a single leaf. Our results suggest the?occurrence of patches at several scales within single leaves. Further analysis should consider variable spatial scales in heterogeneous stomatal behavior between and within patches and within single leaves.  相似文献   

Improved fertilization rates by using a large volume tank in red spotted grouper (Epinephelus akaara)     

S. Okumura  K. Okamoto  R. Oomori  H. Sato  A. Nakazono 《Fish physiology and biochemistry》2003,28(1-4):515-516

Two types of spawning experiments were carried out using a small or a large tank in order to determine the reason for the low fertilization rate in artificially reared red spotted grouper. The mean fertilization rate in the large tank (45%) was significantly higher than the one in the small tank (22%). The fertilization rates were high when a pair spawned underwater (84%) compared with the `jump-type' spawning behavior (31%). Spawning in the large deep tank was effective for improving the fertilization rate in this species.  相似文献   

Acid fog removes calcium and boron from fir tree: One of the possible causes of forest decline     

Manabu Igawa  Kensuke Okumura  Hiroshi Okochi  Naoki Sakurai 《Journal of Forest Research》2002,7(4):213-215

We have observed acid fog in Mt. Oyama adjacent to the Kanto Plains in Japan, where acid fog under pH 3 has been frequently observed and natural fir forest (Abies firma) has been declining. We applied the simulated acid fog to the needles of fir twigs and the treatment removed calcium, boron, and cell-wall acidic sugars from the needles. We also observed high contents of calcium, boron, and acidic sugars in throughfall collected under the declining forest canopy. Ca⁺⁺ and Mg⁺⁺ ion leach via ion-exchange with major cations of fog-water and the amount of leached boron increased with the increase in the concentration of leached Ca⁺⁺. The deficiency of calcium and boron by leaching could be one of the main causes of decline of the fir forest.  相似文献   

Developmental fall in whole body protein turnover of chick embryos during incubation   总被引：1，自引：1，他引：0  

T Muramatsu  S Muramatsu  J Okumura  I Tasaki 《British poultry science》1987,28(1):165-172

Whole body protein turnover was measured in chick embryos during incubation to investigate whether or not there is a fall in fractional rates of protein synthesis and degradation during development. Stable isotopically labelled [15N]phenylalanine was injected intraperitoneally into embryos on days 12 and 19. From 60 to 90 min after injection the isotope enrichment in free and protein-bound phenylalanine was measured with a selected-ion gas-chromatograph mass-spectrometer. The results showed that from days 12 to 19 of incubation, there was a remarkable reduction in fractional rates of protein synthesis and degradation in the whole body of chick embryos. During embryonic growth, protein synthesis per unit of RNA that is, the minimum amino acid translation rate of RNA, did not change significantly, whereas the RNA:protein ratio was reduced to one-third from days 12 to 19 of incubation. It was concluded, therefore, that the dramatic fall in fractional synthesis rate in chick embryos would be entirely attributable to the rapid increase in protein content, thereby changing the RNA:protein ratio in parallel with the fractional synthesis rate.  相似文献   

Wear of tungsten carbide tipped circular saws in cutting particleboard: Effect of carbide grain size on wear characteristics     

H. Sugihara  S. Okumura  M. Haoka  T. Ohi  Y. Makino 《Wood Science and Technology》1979,13(4):283-299

Summary In order to study the wear of tungsten carbide tipped circular saws, three kinds of carbide tips (fine, medium and coarse grained ones) were employed, when sawing particleboards. The saw with coarse grained carbide tips showed the longest working life, while the fine-grained carbide tipped saw retained its usefulness for only a short period of sawing. In an experiment using a saw with all three kinds of carbide tips, it was also confirmed that the fine grained tips wore most and the coarse least. From the observations of the worn tips, it was found that the wear boundary on the clearance face was quite distinct for these tips, although for the fine grained one it was remarkably indented. There were many striations on the wear surface of the fine grained tip, but they scarcely appeared on those of the other two tips. The wear mechanism and the wearing process of the carbide tips are discussed.This paper was presented at the 22nd Annual Meeting of the Japan Wood Research Society at Tokyo, April, 1972The authors wish to express their appreciation to Dr. T. Kawakita, Sumitomo Electric Industries, Ltd., for supplying the carbide tips and to Mr. M. Hiraiwa, Nittokukan Saw Mfg. Co., Ltd., for manufacturing the saws. They are also greatly indebted to Dr. H. Saiki, Wood Structure Laboratory, Kyoto University, for taking scanning electron micrographs and for his valuable advice. This investigation was supported in part by Grants in Aid for Scientific Research in 1972 and 1973 from the Ministry of Education, Japan  相似文献   

Equine haptoglobin: isolation, characterization, and the effects of ageing, delivery and inflammation on its serum concentration.     

T Taira  T Fujinaga  M Okumura  K Yamashita  N Tsunoda  S Mizuno 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》1992,54(3):435-442

Haptoglobin (Hp) was isolated from equine serum by ammonium sulphate precipitation, anion-exchange chromatography and gel filtration. Equine Hp which migrated to the alpha 2-globulin region in electrophoresis, contained 2 fractions with molecular weights (NW) of 108,000 and 105,000, and each fraction consisting of 2 subunits. Quantitative measurement of Hp in equine serum was performed by the single radial immunodiffusion method using anti-equine Hp serum. In clinically normal horses, the highest concentration of serum Hp was found in newborn foals and a high value was maintained until 12 months of age. The concentration then decreased with age. Normal Hp values were 5.25 +/- 2.36 mg/ml in foals (less than or equal to 12 months old), 2.19 +/- 1.54 mg/ml in adult horses (greater than or equal to 18 months old) and 3.62 +/- 0.81 mg/ml in all horses. Serum Hp concentration in mares during the perinatal period in comparison with the normal adult female was high for 4 months pre-partum, a passing increase at delivery, and then decreased at 2 weeks post-partum returning to normal within 1 month of delivery. In horses with experimentally-induced inflammation, serum Hp concentration began to increase immediately after treatment and reached the highest value, 1.5 to 9 times higher than those of pre-treatment at 2 to 5 days, then decreased within 4 weeks. It was also elevated in most cases of horses with clinically inflammatory signs.  相似文献   

Effect of deficiencies of single essential amino acids on nitrogen and energy utilisation in chicks.     

J Okumura  S Mori 《British poultry science》1979,20(4):421-429

1. Diets 50% deficient in single essential amino acids were fed to chicks from day 8 to day 18 after hatching to evaluate body-weight gain, food consumption, body composition, nitrogen (N) and energy utilisation. 2. Body-weight gain was reduced most severely by deficiency of isoleucine followed in decreasing order by threonine, arginine, valine, histidine, tryptophan, methionine plus cystine, phenylalanine plus tyrosine, leucine and lysine, and possible reasons for the differences are discussed. 3. Body-weight gain and food efficiency were highly correlated with food consumption but metabolisable energy value of diets was not affected by single essential amino acid deficiencies. 4. Generally N retention (N retained/N consumed) and energy retention (energy retained/energy consumed) reflected food consumption, except for a lower N retention by chicks fed on the methionine plus cystine-deficient diet and for a lower energy retention by chicks fed on the valine deficient diet. 5. The amino acid deficient in the diet was present at very low concentration in the blood plasma.  相似文献   

The time is ripe for an English journal from Japan on wood science     

Former Editor-in-Chief Mikio Shimada  Shogo Okumura 《Journal of Wood Science》1998,44(1):2-2

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Action mechanism of an angiotensin I-converting enzyme inhibitory peptide derived from chicken breast muscle     

Saiga A  Okumura T  Makihara T  Katsuda S  Morimatsu F  Nishimura T 《Journal of agricultural and food chemistry》2006,54(3):942-945

In a previous study, we isolated the inhibitory peptide (P4 peptide, Gly-Phe-Hyp-Gly-Thr-Hyp-Gly-Leu-Hyp-Gly-Phe) for angiotensin I-converting enzyme (ACE) from chicken breast muscle extract possessing hypotensive activity for spontaneously hypertensive rats (SHRs). This study was performed to elucidate the peptide's action mechanisms of inhibiting ACE. Intravenous administration of synthetic P4 peptide resulted in significant drops in the blood pressures of SHRs. As Dixon plots indicate, the P4 peptide showed high affinity toward ACE (K(i) = 11.48 microM) and only 10% of the total amount of the P4 peptide was decomposed. The analyses of the relationship between the ACE inhibitory activity and structure of the P4 peptide clarified that Hyp-Gly-Leu-Hyp-Gly-Phe showed a stronger activity (IC50 = 10 microM) than the P4 peptide (IC50 = 46 microM). When Phe at the C-terminus of the P4 peptide was deleted, IC50 changed to 25000 microM, indicating that Phe at the C-terminus of the peptide is very important for ACE inhibitory activity.  相似文献   

Cell bioassay for paralytic shellfish poisoning (PSP): comparison with postcolumn derivatization liquid chromatographic analysis and application to the monitoring of PSP in shellfish     

Hayashi R  Saito H  Okumura M  Kondo F 《Journal of agricultural and food chemistry》2006,54(2):269-273

We performed a neuroblastoma cell (Neuro2a) culture assay modified slightly from a method reported previously to provide a simple and sensitive evaluation of paralytic shellfish poisoning (PSP) toxicity in shellfish. The cell bioassay was just as sensitive for C-toxins as for gonyautoxins. The sensitivity of our cell bioassay was 4 times that of the current standard mouse bioassay. Using the cell bioassay, we evaluated PSP toxicity in 361 shellfish samples collected from Mikawa Bay and Ise Bay, Aichi Prefecture, Japan, from April 1999-March 2002. The results were compared with those obtained in a postcolumn derivatization liquid chromatographic analysis. PSP toxins were detected in 236/361 samples by both assays, and there was a fairly good correlation (r = 0.9001, n = 236, p < 0.001) between the results from the two assays. We applied this cell bioassay when short-necked clams in the bay turned poisonous in 2001. The chronological changes in PSP toxicity in the short-necked clams were analyzed and compared with those of the cell density of poisonous plankton (Alexandrium tamarense) occurring in the bay. The PSP toxicity in shellfish peaked 2 weeks after the cell density reached a maximum. We recommend using the cell bioassay for routine monitoring of PSP toxicity in shellfish living in natural marine environments.  相似文献