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81.
Bidding Customs and Habitat Improvement for Matsutake (Tricholoma matsutake) in Japan. A brief history of Japan’s matsutake production, use, and management is presented, with emphasis on habitat improvement
efforts and the land use tradition of iriai. Bidding systems for allotment of matsutake gathering rights are discussed. Three villages with different bidding systems
are compared to see what effects the bidding systems have on village finances, matsutake production, and matsutake habitat
enhancement. Contrary to expectations, habitat for matsutake was not improved when land owners were guaranteed the gathering
and selling rights to matsutake growing on their own lands. Instead, habitat improvement was most successful and matsutake
production was highest on community-owned lands in Oka Village, where the iriai tradition is strongest. 相似文献
82.
BACKGROUND AND AIMS: The light availability on a temperate, deciduous-forest floor varies greatly, reflecting the seasonal leaf dynamics of the canopy trees. The growth and/or reproductive activity of understorey plants should be influenced by the length of the high-irradiance period from snowmelt to canopy closure. The aim of the present study was to clarify how spring-blooming species regulate the translocation of photosynthetic products to current reproduction and storage organs during a growing season in accordance with the changing light conditions. METHODS: Growth pattern, net photosynthetic rate, seed production, and shoot and flower production in the next year of Trillium apetalon were compared between natural and experimentally shaded conditions. Furthermore, translocation of current photosynthetic products within plants was assessed by a labelled carbon-chase experiment. KEY RESULTS: During the high-irradiance period, plants showed high photosynthetic ability, in which current products were initially used for shoot growth, then reserved in the rhizome. Carbon translocation to developing fruit occurred after canopy closure, but this was very small due to low photosynthetic rates under the darker conditions. The shading treatment in the early season advanced the time of carbon translocation to fruit, but reduced seed production in the current year and flower production of the next year. CONCLUSIONS: Carbon translocation to the storage organ had priority over seed production under high-irradiance conditions. A shortened bright period due to early canopy closure effectively restricts carbon assimilation, which greatly reduces subsequent reproductive output owing to low photosynthetic products for fruit development and small carbon storage for future reproduction. As populations of this species are maintained by seedling recruitment, acceleration of canopy closure timing may influence the maintenance and dynamics of populations. 相似文献
83.
The size-dependent sex allocation model predicts that the relative resource allocation to female function often increases
with plant size in animal-pollinated plants. If size effects on reproductive success vary depending on the environmental conditions,
however, the size dependency may differ among populations. We tried to detect site-specific variation in size-dependent sex
allocation of a monocarpic hermaphrodite with reference to light availability. Multiple flowers and fruits were sampled from
the individuals of Cardiocrinum cordatum, a monocarpic understory herb, and pollen, ovule and seed production were measured with reference to the plant size in two
populations. Furthermore, frequency and foraging behavior of pollinator visitation was observed. Ovule production per flower
increased with plant size in both populations, while pollen production per flower increased with size only in the population
under sparse canopy. Therefore, proportional allocation to male function decreased with plant size in the population under
closed canopy, but did not change in the population under sparse canopy. Pollinators usually visited only one flower per plant,
indicating the negligible geitonogamous pollination in this species. Although seed production under closed canopy was lower
than that under sparse canopy, seed-set rate per flower and seed mass per fruit were independent of plant size in either of
the populations. Size-dependent sex allocation in this species was site-specific, suggesting that not only resource storage
before reproduction (i.e., plant size) but also resource availability of environment throughout the reproductive process (i.e.,
light availability) affect reproductive performance in this species. 相似文献
84.
Influence of leaf trichomes on boundary layer conductance and gas‐exchange characteristics in Metrosideros polymorpha (Myrtaceae)
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The amount of trichomes on the leaves of Metrosideros polymorpha varies enormously, ranging from 0 to ca 150 g/m2 across environmental gradients on the island of Hawaii. Pubescent individuals are abundant in dry areas or on young lava flows, whereas glabrous individuals are abundant in wet areas or on developed soils. To understand the adaptive advantages of pubescent individuals in arid environments, we addressed the following questions: (1) whether leaf trichomes increase the boundary layer resistance to gas diffusion, which in turn reduces the transpiration rate and increases water‐use efficiency (WUE); and (2) whether pubescent individuals have other associated leaf and shoot traits that have adaptive significance in arid environments. We made detailed ecophysiological measurements on M. polymorpha in three populations in habitats that varied in aridity. We found a large allocation of leaf mass to trichomes, up to 33 percent at the arid site, but our analyses showed that trichomes had small effects (1–9%) on gas exchange and negligible effects on WUE, suggesting the trichomes may have roles beyond increasing WUE. However, pubescent individuals did have higher Rubisco amount and a lower leaf‐to‐ sapwood area ratio, which are considered adaptive in arid environments. These results suggest that pubescent individuals of M. polymorpha are indeed adapted to arid environments with changes in a suite of traits. The adaptive significance of the enormous variation in amounts of trichomes remains unclear and may be related to functions other than increasing boundary layer resistance. 相似文献
85.
Resource subsidies from external habitats can substantially affect the food web dynamics of local habitats. In this paper, we explore a mathematical model that is tailored for a stream food web, studied by Nakano and colleagues, in which consumers, in situ prey and subsidies all show seasonal fluctuation. The model reveals that the food web dynamics are stabilized if subsidies increase in summer when in situ productivity is low. Consumer dynamics are stabilized because subsidies complement seasonal resource deficiency. In situ prey dynamics are stabilized because subsidies indirectly balance the predation pressure by consumers, with seasonal change in prey carrying capacity. In summer when prey carrying capacity is low, seasonally abundant subsidies indirectly decrease predation pressure, whereas in winter, with high prey carrying capacity, scarce subsidies increase the predation pressure. Our results suggest that temporal productivity differences between spatially linked habitats are important to promote the stability of food web dynamics in a landscape context. 相似文献
86.
Characterization of size-fractionated cDNA libraries generated by the in vitro recombination-assisted method. 总被引:3,自引:0,他引:3
Osamu Ohara Takahiro Nagase Gaku Mitsui Hiroshi Kohga Reiko Kikuno Shuichi Hiraoka Yu Takahashi Satoshi Kitajima Yumiko Saga Haruhiko Koseki 《DNA research》2002,9(2):47-57
We here modified a previously reported method for the construction of cDNA libraries by employing an in vitro recombination reaction to make it more suitable for comprehensive cDNA analysis. For the evaluation of the modified method, sets of size-selected cDNA libraries of four different mouse tissues and human brain were constructed and characterized. Clustering analysis of the 3' end sequence data of the mouse cDNA libraries indicated that each of the size-fractionated libraries was complex enough for comprehensive cDNA analysis and that the occurrence rates of unidentified cDNAs varied considerably depending on their size and on the tissue source. In addition, the end sequence data of human brain cDNAs thus generated showed that this method decreased the occurrence rates of chimeric clones by more than fivefold compared to conventional ligation-assisted methods when the cDNAs were larger than 5 kb. To further evaluate this method, we entirely sequenced 13 human unidentified cDNAs, named KIAA1990-KIAA2002, and characterized them in terms of the predicted protein sequences and their expression profiles. Taking all these results together, we here conclude that this new method for the construction of size-fractionated cDNA libraries makes it possible to analyze cDNAs efficiently and comprehensively. 相似文献
87.
Cellulolytic environment in the midgut of the wood-feeding higher termite Nasutitermes takasagoensis
Tokuda G Watanabe H Hojo M Fujita A Makiya H Miyagi M Arakawa G Arioka M 《Journal of insect physiology》2012,58(1):147-154
Unlike lower termites, xylophagous higher termites thrive on wood without the aid of symbiotic protists. In the higher termite Nasutitermes takasagoensis, both endogenous endo-β-1,4-glucanase and β-glucosidase genes are expressed in the midgut, which is believed to be the main site of cellulose digestion. To further explore the detailed cellulolytic system in the midgut of N. takasagoensis, we performed immunohistochemistry and digital light microscopy to determine distributions of cellulolytic enzymes in the salivary glands and the midgut as well as the total cellulolytic activity in the midgut. Although cellulolytic enzymes were uniformly produced in the midgut epithelium, the concentration of endo-β-1,4-glucanase activity and luminal volume in the midgut were comparable to those of the wood-feeding lower termite Coptotermes formosanus, which digests cellulose with the aid of hindgut protists. However, the size of ingested wood particles was considerably larger in N. takasagoensis than that in C. formosanus. Nevertheless, it is possible that the cellulolytic system in the midgut of N. takasagoensis hydrolyzes highly crystalline cellulose to a certain extent. The glucose produced did not accumulate in the midgut lumen. Therefore, the present study suggests that the midgut of the higher termite provides the necessary conditions for cellulolysis. 相似文献
88.
Responses of alpine shrubs to simulated environmental change during three years in the mid-latitude mountain, northern Japan 总被引:3,自引:0,他引:3
Effects of artificial warming on phenology, individual leaf traits, vegetative growth, and reproduction of five alpine species (two deciduous and three evergreen shrubs) were investigated during three years in the mid-latitude alpine, northern Japan. Eleven open-top chambers (OTCs) were set up on a fellfield (1680 m a. s. l.) in the Taisetsu Mountains by which air temperature at plant height was increased by ca 2°C. Vaccinium uliginosum (deciduous shrub) showed earlier leaf emergence in every season and earlier flowering only in the first season in the OTCs. By contrast, acceleration of leaf emergence in the OTCs was not clear for other species, i.e. Arctous alpinus (deciduous shrub). Ledum palustre. V. vitis-idaea , and Empetrum nigrum (evergreen shrub). Both deciduous species showed longer leaf life-span in the OTCs every season. All evergreen species had higher leaf survival rates in the OTCs. indicating extension of leaf life-span. Leaf nitrogen concentration and leaf mass per unit leaf area (mg cm −2 ) generally tended to decrease in the OTCs. Relationships between the individual leaf traits and cumulative air temperature during the leaf developing period were not clear. Total leaf production during the three seasons increased in the OTCs in A. alpinus. L. palustre. V. vitis-idaea , and E. nigrum. All evergreen shrubs showed larger shoot growth in the OTCs but both deciduous shrubs did not show significant changes. In contrast to the vegetative growth, deciduous shrubs produced more flowers in the OTCs. Fruit production was not influenced by the OTCs for all species. The extension of photosynthetic period in the OTCs may contribute to the larger vegetative growth or flower production. 相似文献
89.
Kawashima H Amaha M Ioi H Yamanaka G Kashiwagi Y Sasamoto M Takekuma K Hoshika A Watanabe Y 《Neurochemical research》2005,30(3):311-314
NOx (NO2 and NO3) in CSF obtained from 22 patients with influenza-associated encephalopathy were higher than those of a control group. Within the different prognosis, there were no significant differences in NOx levels. By analyzing the serum obtained from patients infected with influenza, including encephalopathy, with others, the serum zinc levels did show marked differences between them. Four out of eleven patients with influenza-associated encephalopathy showed low zinc levels below the normal range. However, there were no significant differences in the zinc levels between the group with sequela and without sequela. These results indicate that the increase of NOx levels detected in influenza-associated encephalopathy relates to the low zinc levels, and both low molecules might play an important role for the cause of encephalopathy. 相似文献
90.
Monkey embryonic stem (ES) cell is a useful tool for preclinical studies of regenerative medicine. In this paper, we investigated whether monkey ES cells can be differentiated into osteoblasts in vitro using factors known to promote osteogenesis. We prepared embryoid bodies (EB) in the presence of retinoic acid (RA) and subsequently differentiated in the medium containing either dexamethasone (DEX) or bone morphogenetic protein (BMP)-2 in addition to osteogenic supplements (OS), specifically ascorbic acid and beta-glycerophosphate. RA treatment during EB formation induced osteoblastic marker genes, such as collagen type 1, osteopontin, and Cbfa1. For the expression of osteocalcin, however, cultivation with medium containing either DEX or BMP-2 in addition to OS was required. These results showed that osteoblasts could be derived from monkey ES cells in vitro and BMP-2 + OS was effective to induce calcification. 相似文献