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31.
Evgenios Agathokleous Regina G.Belz Mitsutoshi Kitao Takayoshi Koike Edward J.Calabrese 《林业研究》2019,(5):1569-1580
Root/shoot(R/S)ratio is an important index for assessing plant health,and has received increased attention in the last decades as a sensitive indicator of plant stress induced by chemical or physical agents.The R/S ratio has been discussed in the context of ecological theory and its potential importance in ecological succession,where species follow different strategies for above-ground growth for light or below-ground competition for water and nutrients.We present evidence showing the R/S ratio follows a biphasic dose–response relationship under stress,typical of hormesis.The R/S ratio in response to stress has been widely compared among species and ecological succession classes.It is constrained by a variety of factors such as ontogeny.Furthermore,the current literature lacks dose-response studies incorporating the full dose–response continuum,hence limiting scientific understanding and possible valuable application.The data presented provide an important perspective for new-generation studies that can advance current ecological understanding and improve carbon storage estimates by R/S ratio considerations.Hormetic response of the R/S ratio can have an important role in forestry for producing seedlings with desired characteristics to achieve maximum health/productivity and resilience under plantation conditions. 相似文献
32.
The interaction of drought and elevated carbon dioxide concentration ([CO(2)]) on carboxylation capacity of Rubisco (V(cmax)) and susceptibility to photoinhibition may be an important determinant of plant responses to seasonal fluctuations in precipitation in an anticipated elevated [CO(2)] environment. Japanese white birch (Betula platyphylla var. japonica) leaves that developed wholly during a period of drought showed an increase in leaf nitrogen and a decrease in leaf carbohydrates that could ameliorate photosynthetic down-regulation, defined as a decrease in V(cmax) in response to elevated [CO(2)]. Photochemical quenching (q(P)) was decreased by elevated [CO(2)] but increased by drought when compared at a given intercellular [CO(2)] (C(i)), indicating that elevated [CO(2)] could increase the risk of photoinhibition, whereas long-term drought could alleviate the risk of photoinhibition. However, only a small variation in q(P) was measured among seedlings in the various water availability x [CO(2)] treatment combinations, consistent with the small treatment differences in chronic photoinhibition among the seedlings, as indicated by the ratio of variable to maximum chlorophyll fluorescence after overnight dark-adaptation. Our results suggest that the offsetting responses-reduced V(cmax) plus increased C(i) at elevated [CO(2)] and increased V(cmax) plus reduced C(i) under drought conditions-resulted in a narrow range of susceptibility to photoinhibition at the growth [CO(2)] in Japanese white birch seedlings grown in various water availability x [CO(2)] treatment combinations. 相似文献
33.
Ono M Ohtaki T Tanemura K Ishii M Watanabe G Taya K Tsumagari S 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2011,73(9):1145-1149
In the present study, the effect of 4-day fasting on steroid hormone metabolism in the liver and secretion of LH was examined in cows. Six non pregnant, dry Holstein cows were used. The estrous cycle was synchronized in all cows using CIDR-Ovsynch. Cows were allocated to a control group (n=3) and a fasting group (n=3). In the fasting group, cows were fasted for four days from day -4 to day -1 (day 0=day of 2nd GnRH injection) but otherwise were fed ad libitum. The experiment was repeated in a crossover design after an interval of about one month. The peripheral progesterone (P(4)) concentration in the fasting group was significantly higher than in the control group on day -1 and 0. The peripheral estradiol-17β concentration in the fasting group was also significantly higher than in the control group on day -1 and 0. The portal vein P(4) concentration in the fasting group was significantly higher than in the control group. On day 0, there was no difference in LH secretion between groups. The mean percentages of lipid droplets in liver cells in the fasting group were significantly higher than in the control group on day 0. These results suggest that short-term fasting leads to reduced hepatic steroid hormone metabolism by accumulation of fat in the liver, which causes high peripheral steroid hormone concentrations. 相似文献
34.
Tadatoshi Nobata Hirohisa Kyougoku Takashi Miyano 《The Journal of reproduction and development》2013,59(5):500-505
During oocyte growth, the morphology of the nucleolus changes into a compact and
homogenous structure. The compact nucleoli in full-grown oocytes are not stained by
aceto-orcein staining or immunofluorescence staining. In this study, we developed a
hematoxylin staining method for pig oocytes in whole-mount preparations to visualize
the nucleoli. Nucleoli of growing and full-grown oocytes were stained blue with
hematoxylin. Using this staining method, the changes in the oocyte nucleolus during
maturation were examined. The nucleolar diameter gradually decreased in maturing
oocytes (10.7 ± 0.1 μm to 9.0 ± 0.7 μm, P<0.05) before germinal vesicle breakdown
(GVBD). The results suggest that the nucleolar volume of oocytes decreases before
GVBD. 相似文献
35.
Kitao M Tobita H Utsugi H Komatsu M Kitaoka S Maruyama Y Koike T 《Tree physiology》2012,32(8):998-1007
To assess the effects of elevated CO(2) concentration ([CO(2)]) on the photosynthetic properties around spring budbreak, we monitored the total leaf sugar and starch content, and chlorophyll fluorescence in 1-year-old needles of Sakhalin spruce (Picea glehnii Masters) seedlings in relation to the timing of budbreak, grown in a phytotron under natural daylight at two [CO(2)] levels (ambient: 360?μmol mol(-1) and elevated: 720?μmol mol(-1)). Budbreak was accelerated by elevated [CO(2)] accompanied with earlier temporal declines in the quantum yield of PSII electron transport (Φ(PSII)) and photochemical quenching (q(L)). Plants grown under elevated [CO(2)] showed pre-budbreak leaf starch content twice as high with no significant difference in Φ(PSII) from ambient-CO(2)-grown plants when compared at the same measurement [CO(2)], i.e., 360 or 720?μmol mol(-1), suggesting that the enhanced pre-budbreak leaf starch accumulation might not cause down-regulation of photosynthesis in pre-existing needles under elevated [CO(2)]. Conversely, lower excitation pressure adjusted for the efficiency of PSII photochemistry ((1?-?q(P)) F(v)'/F(m)') was observed in plants grown under elevated [CO(2)] around budbreak when compared at their growth [CO(2)] (i.e., comparing (1?-?q(P)) F(v)'/F(m)' measured at 720?μmol mol(-1) in elevated-CO(2)-grown plants with that at 360?μmol mol(-1) in ambient-CO(2)-grown plants), which suggests lower rate of photoinactivation of PSII in the elevated-CO(2)-grown plants around spring budbreak. The degree of photoinhibition, as indicated by the overnight-dark-adapted F(v)/F(m), however, showed no difference between CO(2) treatments, thereby suggesting that photoprotection during the daytime or the repair of PSII at night was sufficient to alleviate differences in the rate of photoinactivation. 相似文献
36.
Effect of an immunopotentiator on Aeromonas salmonicida infection in rainbow trout (Salmo gairdneri) 总被引：1，自引：0，他引：1
The immunoactive peptide FK-565 (heptanoyl-y-D-glutamyl-(L)-mesodiaminopimelyl-(D)-alanine) was found to induce protection against intraperitoneal Aeromonas salmonicida infection in rainbow trout (Salmo gairdneri Richardson). The survival rate was as high as 60% when FK-565 was given intraperitoneally as a single dose (1mg/kg) one day before bacterial challenge. A non-specific stimulation of phagocytic cells by FK-565 at an early stage of the bacterial infection may contribute to the resistance observed. The phagocytic activity of peritoneal phagocytic cells as well as phagocytic cells of the pronephros were stimulated by FK-565 in vivo and in vitro, respectively, as compared to untreated control fish. Furthermore, decreased activity of phagocytic cells previously immunosuppressed with cyclophosphamide was rapidly restored by application of FK-565. 相似文献
37.
Otabe K. Sugimoto T. Jinbo T. Honda M. Kitao S. Hayashi S. Shimizu M. Yamamoto S. 《Veterinary research communications》1998,22(2):77-85
This study was undertaken to investigate whether the level of C-reactive protein (CRP) in the serum of dogs undergoes physiological variation, using 10 normal Beagle dogs (5 males and 5 females), 1–2 years old, maintained in a healthy condition in a controlled environment. The CRP concentration in the sera collected seven times each day at intervals of approximately 3 h ranged from 0.8 to 16.4 µg/ml (mean 5.06±3.60) in one experiment and from 0.8 to 14.0 µg/ml (mean 4.50±2.80) in a second experiment. On examining the 24-h variations in the concentration of CRP in serum, neither consistent changes nor a definite pattern of circadian rhythm was detected. During 28 days observation, only very slight changes, which seemed attributable to analytical errors, were seen in any of the dogs, except one. The concentration of CRP in the serum during the 28 days ranged from 0.8 to 22.6 µg/ml (mean 3.65±1.40). The concentrations underwent no significant variations in individual dogs, but significant differences were found between the dogs (p<0.01). 相似文献
38.
Tsuchiya R Tatsuki Y Kitao S Furuichi M Neo S Hisasue M Yamada T Kobayashi K 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2008,70(2):181-183
Characteristics of the signal transduction in Platelet activating factor (PAF)-activated platelets and effects of anti-platelet agents on this response were investigated in vitro for potential therapeutic applications in canine endotoxemia. Blockade of the PAF receptor by a specific blocker has the strongest inhibitive effect on the PAF-induced platelet reactions. The response was also inhibited by either Ca(2+) channel blockers or prostaglandin E(1). 相似文献
39.
We investigated susceptibility to photoinhibition in leaves acclimated to different light regimes in intermediately shade-tolerant Japanese oak (Quercus mongolica Fisch. ex Turcz. var. crispula (Blume) Ohashi) and shade-tolerant Japanese maple (Acer mono Maxim. var. glabrum (Lév. et Van't.) Hara), to elucidate adaptability to gap formation in leaves differing in shade acclimation. We hypothesized that there is a tradeoff between shade adaptation and capacity to mitigate photoinhibition associated with leaf morphology. We simultaneously measured chlorophyll fluorescence and gas exchange in seedlings that had been grown in full sunlight (open), 10% of full sun (moderate shade) and 5% of full sun (deep shade). Shade-tolerant A. mono adapted to deep shade through changes in leaf morphology, lowering its leaf mass per area (LMA), but Q. mongolica showed little change in LMA between moderate and deep shade. Photochemical quenching (qP) did not differ between species in full sunlight and moderate shade; however, in deep shade, qP of Q. mongolica was higher than that of A. mono, suggesting that Q. mongolica grown in deep shade is less susceptible to photoinhibition at gap formation. This is consistent with the finding that chronic photoinhibition 3 days after the transfer to full sunlight, indicated by the decrease in maximum photochemical efficiency, Fv/Fm, at predawn, was less in deep-shade-grown Q. mongolica than in deep shade-grown A. mono. In deep shade, the electron transport rate (ETR) of Q. mongolica was higher than that of A. mono, whereas thermal energy dissipation through photosystem II antennae, indicated by non-photochemical quenching, was lower in Q. mongolica than in A. mono. In deep shade, the greater ETR capacity in Q. mongolica in association with higher LMA and higher leaf N content could contribute to maintaining high qP and mitigating photoinhibition. These results indicate that, by maintaining a high electron transport capacity even in deep shade, the gap-dependent and intermediate-shade-tolerant Q. mongolica trades improved shade adaptation for higher growth potential when a gap event occurs. 相似文献