bluuebunny/crossref_metadata_2025 huggingface dataset:
Photoluminescence spectroscopy of single crystalline ZnO‐nanoparticles from the gas phase
Authors: Schneider L. , Halm S. , Bacher G. , Roy A. , Kruis F. E.
Published: March 2006

Photoluminescence (PL) measurements on ZnO nanoparticles synthesized by chemical vapour synthesis (CVS) are presented. We show that the green defect related emission band can be almost completely suppressed by the right choice of processing parameters, like oxygen concentration and sintering temperature. Using temperature dependent time integrated and time resolved PL measurements we obtained information about the excitonic structure of the nanoparticles. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Determination of crystallographic polarity of ZnO bulk crystals and epilayers
Authors: Tampo H. , Fons P. , Yamada A. , Kim K.‐K. , Shibata H. , Matsubara K. , Yoshikawa H. , Kanie H. , Niki S.
Published: March 2006

The crystallographic polarity of ZnO bulk crystals and epilayers were determined by X‐ray diffraction (XRD) using anomalous dispersion near the Zn K‐edge. The method is not destructive and is straightforward to carry out using a typical XRD measurement system. The polarity difference between the Zn (0001) and O (000$ \bar 1 $) surfaces could be easily determined using a {0002} diffraction peak and the Bremstrahlung radiation from a Cu rotating anode source. By using the normalized pre and post‐Zn K‐edge diffraction intensity ratios of the {0002} diffraction peak, Zn polar and O polar ZnO layers could always be distinguished but, the absolute value of the ratio was found to change with layer thickness. Acid etching results confirmed the veracity of the polarity determination of the XRD measurement. To test the technique, Zn and O polar ZnO layers were grown by radical source molecular beam epitaxy on MgO buffer layers on c‐sapphire substrate and O polar ZnO layers were grown on a‐plane substrates and measured using the X‐ray technique with excellent agreement. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Percolation model for long wave phonons in random zincblende alloys: from II‐VI's to III‐V's
Authors: Chafi A. , Pagès O. , Fristot D. , Postnikov A. V. , Tite T. , Laurenti J. P. , Bormann D. , Maksimov O. , Tamargo M. C.
Published: March 2006

We propose a simplified version of our 1‐bond → 2‐mode percolation model initially developed for the q ∼ 0 phonon properties of the stiff Be‐VI bond in (Zn,Be)‐chalcogenides, which open the class of random mixed crystals with contrast in the bond stiffness. The simplified version applies to the ‘usual’ alloys, i.e. made of soft‐like bonds only. It is derived from detailed comparison of the Raman responses from the stiff Be‐Te bond and the soft Zn‐Te one in the pioneer (Zn,Be)Te system. The simplified version is eventually tested on (Ga,In)As whose 1‐bond → 2‐mode behavior in the Ga‐As range of the Raman spectra remains a much debated issue. Further, we lay the foundations for a comprehensive re‐examination of the puzzling phonon behavior' of the similar (Ga,In)P alloy, by analogy with (Ga,In)As. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photoluminescence recombination centers in ZnO
Authors: Shibata H. , Tampo H. , Sakai M. , Yamada A. , Matsubara K. , Sakurai K. , Ishizuka S. , Kim K. , Fons P. , Iwata K. , Niki S. , Tamura K. , Nakahara K. , Takasu H. , Maeda K. , Niikura I.
Published: March 2006

We have studied the effects of (i) impurity doping, (ii) rapid thermal annealing, and (iii) crystal polarity control on photoluminescence spectra in the band‐edge emission region of high quality ZnO. As a result, we have discussed the possible lattice defects responsible for some photoluminescence emission peaks, namely (i) peak I 8 appears at 3.3596 eV, (ii) peak I 9 appears at 3.3565 eV and (iii) peak G appears at 3.3327 eV. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photoluminescence properties of ZnO single crystals with polar and non‐polar faces
Authors: Sasaki H. , Kato H. , Izumida F. , Endo H. , Maeda K. , Ikeda M. , Kashiwaba Y. , Niikura I. , Kashiwaba Y.
Published: March 2006

Photoluminescence (PL) was circumstantially measured for ZnO single crystals with polar and non‐polar faces. PL spectra of ZnO single crystals depended on the sector and polarity of ZnO single crystals. Emissions due to excitons from c ‐plane substrates sliced from the +c sector were strong, and FWHMs of the emissions were smaller than those from substrates sliced from the –c sector. An emission due to neutral‐donor‐bound exicitons (D0X) at 3.361 eV was dominantly observed on all surfaces of ZnO single crystals, and an emission due to ionized‐donor‐bound excitons (D+X) around 3.366 eV was observed on the O‐face but not on the Zn‐face at 4.2 K. It is thought that surface state densities due to oxygen caused this difference in PL emission for polarity of ZnO. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A high‐resolution electron microscopy study of MgxZn1–xO films grown on MgO/c‐sapphire
Authors: Vashaei Z. , Minegishi T. , Suzuki H. , Cho M.W. , Yao T.
Published: March 2006

We report on the microstructure of MgxZn1–xO films grown on MgO/c‐sapphire by P‐MBE. Cross sectional specimens of three layers with rock salt, wurtzite, and mixed crystal structure were studied by high‐resolution transmission electron microscopy (HRTEM). Selected area diffraction pattern (SADP) and fast fourier transform (FFT) were also employed to analyze the samples. The results indicate the growth of cubic‐MgZnO along the [111] direction accompanied by twinning. HRTEM micrograph of wurtzite‐MgZnO confirmed that initial stage of the growth starts with a cubic structure and then changes to the wurtzite phase. Our results demonstrate that by introducing a thin MgO buffer layer, growth of cubic‐MgZnO with low Mg content is feasible. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Regulation of cardiolipin synthase levels in Saccharomyces cerevisiae
Authors: Su Xuefeng , Dowhan William
Published: March 2006

The Saccharomyces cerevisiae cardiolipin (CL) synthase encoded by the CRD1 gene catalyses the synthesis of CL, which is localized to the inner mitochondrial membrane and plays an important role in mitochondrial function. To investigate how CRD1 expression is regulated, a lacZ reporter gene was placed under control of the CRD1 promoter and the 5′‐untranslated region of its mRNA (PCRD1‐lacZ). PCRD1‐lacZ expression was 2.5 times higher in early stationary phase than in logarithmic phase for glucose grown cells. Non‐fermentable growth resulted in a two‐fold elevation in expression relative to glucose grown cells. A shift from glycerol to glucose rapidly repressed expression, whereas a shift from glucose to glycerol had the opposite effect. The derepression of PCRD1‐lacZ expression by non‐fermentable carbon sources was dependent on mitochondrial respiration. These results support a tight coordination between translation and transcription of the CRD1 gene, since similar effects by the above factors on CRD1 mRNA levels have been reported. In glucose‐grown cells, PCRD1‐lacZ expression was repressed 70% in a pgs1Δ strain (lacks phosphatidylglycerol and CL) compared with wild‐type and rho− cells and elevated 2.5‐fold in crd1Δ cells, which have increased phosphatidylglycerol levels, suggesting a role for phosphatidylglycerol in regulating CRD1 expression. Addition of inositol to the growth medium had no effect on expression. However, expression was elevated in an ino4Δ mutant but not in ino2Δ cells, suggesting multiple and separate functions for the inositol‐responsive INO2/INO4 gene products, which normally function as a dimer in regulating gene function. Copyright © 2006 John Wiley & Sons, Ltd.
The budding yeast rRNA and ribosome biosynthesis (RRB) regulon contains over 200 genes
Authors: Wade Christopher H. , Umbarger Mark A. , McAlear Michael A.
Published: March 2006

The ribosome biogenesis pathway constitutes one of the major metabolic obligations for a dividing yeast cell and it depends upon the activity of hundreds of gene products to produce the necessary rRNA and ribosomal protein components. Previously, we reported that a set of 65 S. cerevisiae genes that function in the rRNA biosynthesis pathway are transcriptionally co‐regulated as cells pass through a variety of physiological transitions. By analysing multiple microarray‐based transcriptional datasets, we have extended that study and now suggest that the ribosomal and rRNA biosynthesis regulon contains over 200 genes. This regulon is distinct from the set of ribosomal protein genes, and the promoters of the expanded RRB gene set are highly enriched for the PAC and RRPE motifs. Since a similar pattern of organization and gene regulation can be recognized in C. albicans, the RRB regulon appears to be a conserved, extensive, and metabolically important group of genes. Copyright © 2006 John Wiley & Sons, Ltd.
Biotransformation of malachite green by Saccharomyces cerevisiae MTCC 463
Authors: Jadhav J. P. , Govindwar S. P.
Published: March 2006

In recent years, use of microbial biomass for decolourization of textile industry wastewater is becoming a promising alternative in which some bacteria and fungi are used to replace present treatment processes. Saccharomyces cerevisiae MTCC 463 decolourized the triphenylmethane dyes (malachite green, cotton blue, methyl violet and crystal violet) by biosorption, showing different decolourization patterns. However, malachite green decolourized by biosorption at the initial stage and further biodegradation occurred, about 85% in plain distilled water within 7 h, and about 95.5% in 5% glucose medium within 4 h, under aerobic conditions and at room temperature. Decolourization of malachite green depends on various conditions, such as concentration of dye, concentration of cells, composition of medium and agitation. HPLC, UV‐VIS, FTIR and TLC analysis of samples extracted with ethyl acetate from decolourized culture flasks confirmed the biodegradation of malachite green into several metabolites. A study of the enzymes responsible for the biodegradation of malachite green in the control and cells obtained after decolourization showed the activities of laccase, lignin peroxidase, NADH‐DCIP reductase, malachite green reductase and aminopyrine N‐demethylase in control cells. A significant increase in the activities of NADH‐DCIP reductase and MG reductase was observed in the cells obtained after decolourization, indicating a major involvement of reductases in malachite green degradation. Copyright © 2006 John Wiley & Sons, Ltd.
Density, biomass, and guild structure of arboreal arthropods as related to their inhabited tree size in a Cryptomeria japonica plantation
Authors: Hijii Naoki
Published: March 2006

Arboreal arthropods in a 15‐year‐old plantation of Cryptomeria japonica were surveyed using the smoking method under open conditions and also in the enclosed condition in which the whole above‐ground part of a tree was covered by a cloth bag. Per tree, the number of individuals collected was 8200–14000, with a biomass of 340–1700 mg d.wt. Collembola and Acarina were major components in number, while Diplopoda, Collembola, and Araneae occupied the larger part of the biomass. About 60–70% of total numbers of individuals dropped within two hours after the open fumigation. Clear power‐form regressions between total numbers of individuals and biomasses of all animals and their host tree size (stem diameter at clear length, DB) showed they were approximately proportional to DB2. The guilds of scavengers and tourists demonstrated the most significant correlations between their numbers and biomasses and the tree size. Numbers and biomasses of Collembola, Diptera, and Araneae revealed remarkable dependence on the tree size. From these regressions, numbers of individuals and biomasses per unit ground area were estimated for all arthropods to be 3755/m2 and 165.87 mg d.wt./m2, respectively. Power‐form regressions were observed between numbers and biomasses of prey and predators. The number‐and biomass ratios of all predators to all prey tended to decrease with increasing tree size. A similar trend was observed in the corresponding ratios of parasitic Hymenoptera to lepidopteran larvae, while those of Araneae to Collembola were almost constant, irrespective of tree size.
A simple generalized model of attack by predators and parasites
Authors: Fujii Koichi , Holling C. S. , Mace P. M.
Published: March 2006

A generalized descriptive equation for the effect of prey density on the instantaneous rate of attack was proposed; urn:x-wiley:09123814:ere0141:equation:ere0141-math-0001 where A(No) is the number of attacks per predator during time Tt, No is the prey density, Tt is the total time the prey was exposed, Th is the handling time per prey, a′ is the rate of successful search, and c is the facilitation coefficient. The proposed equation can describe all types of the functional response curves; with c=a′ th (pseudo Type I), with c=0 (Type II), with c>a′ th (Type III), and with c<0 (Type IV). The applicability of the equation was tested against the results of a simulation model and available laboratory and field data on predation. The equation described these data very well and in many cases yielded biologically interesting insights, although the equation was proposed primarily for descriptive purposes.
Size‐sex relationship and sexual dimorphism in Japanese Arisaema (Araceae)
Authors: Kinoshita Eiichiro
Published: March 2006

The size‐sex relationship and sexual differences of six Arisaema species native to Japan were investigated. The size‐sex relationship showed almost the same pattern in all species. When the plant was small in size, the sex expression was male, and sex expression changed from male to female as the plant grew larger. Male ratios decreased rapidly around a critical size, but this critical size differed from one species to another.

Sexual differences were detected in reproductive structures and behavior, although no difference was detected in vegetative structures. The stoutness, longevity and inner tissue of the scape showed remarkable differences between males and females, and this difference was represented most clearly as the size‐weight relationship. Earlier initiation of flowering in males was also observed.

No difference was found in resource allocation to reproductive structures between male and female plants at the flowering stage. However, a broad variation in the amount of resource allocation to reproductive structures was found at the fruiting stage in female individuals, which was attributed to differences in the setting rate of mature fruits.
Evaluation of the light interception by non‐photosynthetic organs in a Larix leptolepis plantation
Authors: Kurachi Nahoko , Hagihara Akio , Hozumi Kazuo
Published: March 2006

Vertical changes in relative light intensity within the canopy of a 19‐year‐old (as of 1982) plantation of Japanese larch were investigated before and after defoliation. The relative light intensity at 1.3m above the ground was 6% before defoliation, while it was about 20% after defoliation. The leaf area index and the total longitudinal section area of such non‐photosynthetic organs as stems and branches were in the range 4.84 to 5.61 ha/ha and 0.788 to 0.798 ha/ha, respectively. An equation of I′(z)/I0=exp[‐(KFF(z)+KcC(z)], which gives a description of light attenuation within a canopy, was proposed on the assumption that the relative light intensity I′(z)/Io at a depth z from the canopy surface is affected by both the cumulative densities of leaf area F(z) and the longitudinal section area of non‐photosynthetic organs C(z) existing above that depth. The value of the extinction coefficient for the leaves KF was computed to be 0.31–0.36 ha/ha, while that for the non‐photosynthetic organs Kc was computed to be 1.4–1.7 ha/ha. The function C(z) was proportional to F(z), or C(z)=aF(z) where the constant a was 0.11–0.13. The proposed equation led to the formula, I′(z)/I0=exp[‐KF(z)]. The apparent extinction coefficient K was partitioned into two terms as follows, K=KF+aKc. The value of K was estimated to be 0.46–0.59 ha/ha, and was about 1.5 times larger than of KF.
Species numbers, area, and habitat diversity on the habitat‐islands of Mizorogaike pond, Japan
Authors: Shimizu Yoshikazu
Published: March 2006

Species‐area relationships of flowering plants were analyzed on the habitat‐islands (hummocks on a floating bog) of Mizorogaike Pond, Japan. Three habitat units (Sphagnum cuspidatum unit, Sphagnum palustre unit, and fallen leaves unit) in which habitat conditions were homogeneous and a group of habitat‐specific species occurred were recognized on the hummocks. Six hummock types were determined according to various combinations of the three habitat units. The most fundamental species‐area relationships in which size itself affects the number of species were shown by hummocks with only one habitat unit. The species‐area relationships for hummocks with two or three habitat units included the effects of habitat diversity in addition to size. The speciesarea curve for all hummocks was an average of these relationships. It is concluded that area in species‐area relationships affects species numbers in two ways: number of habitat units and size of each habitat unit.
The effects of a typhoon on Japanese warm temperate rainforests
Authors: Bellingham P. J. , Kohyama Takashi , Aiba Shin‐ichiro
Published: March 2006

A powerful typhoon (Typhoon No. 13) affected stands of primary warm temperate rainforest in Yakushima, southern Japan, in 1993. Censuses in three sites 1–5 months after the typhoon showed low levels of mortality resulting from the typhoon (0.4–3.0% of stems). Stems killed by the typhoon were generally larger than surviving stems. Among surviving stems there were generally low levels of damage (e.g. 0.5–1.3% of surviving stems lost crowns) and not all damage was widespread (e.g. defoliation was apparent only in one of three sites). The sizes of uprooted stems, stems that lost crowns and relatively undamaged stems were not different. Different species appeared to be damaged in different ways at different sites. Damage was most evident in higher altitude seaward sites but gap formation was more frequent in lower altitude sites near valley floors. After the typhoon the resultant gap area occupied 9.4% of one site and 8.6% of another, which is greater than that before the typhoon. Fresh sprouts were found on 17.35% of 2161 stems after the typhoon, including many apparently undamaged stems as well as those that were damaged. Species which sprouted most frequently were those that regenerate by seed least frequently in these forests; these species may maintain their relative abundance in part by sprouting. Most tree species in these forests may be relatively resistant to typhoons and there may be more opportunities for their regeneration following gap formation caused by the typhoon.
Pollination of the orchidEpipactis thunbergiiby syrphid flies (Diptera: Syrphidae)
Authors: Sugiura Naoto
Published: March 2006

The behavior of visitors to the flowers of the orchidEpipactis thunbergiiwas studied, with special attention to the role of the epichile in the pollination process. Only four species of syrphid flies legitimately pollinated the flower, among whichSphaerophoria macrogasterwas regarded as the most effective pollinator. The movable epichile, possessing a furrow at its base, played a critical role in the pollination process: it threw the syrphid fly onto the stigmatic surface when both sides of the basal slanting surface of the furrow were presumably pressed in the direction of the hypochile by the fore (and middle) legs of the retreating syrphid fly. At this moment, the fly received a set of pollinia on the thorax.
Microdistribution of sulfate‐reducing bacteria in sediments of a hypertrophic lake and their response to the addition of organic matter
Authors: Fukui Manabu , Takii Susumu
Published: March 2006

To clarify the ecological significance of the association of sulfate‐reducing bacteria (SRB) with sediment particle size, SRB utilizing lactate (l‐SRB), propionate (p‐SRB) and acetate (a‐SRB) were examined with different sizes of sediment particles in a hypertrophic freshwater lake using the anaerobic plate count method. The numbers of l‐SRB and a‐SRB were 104–105 colony forming units (CFU) per ml in the 0–3 cm layer and 102–103 CFU ml−1 in the 10–13 cm layer while the numbers of p‐SRB were one or two orders lower than those of l‐SRB and a‐SRB. A sediment suspension was fractionated into four fractions (<1, 1–10, 10–94 and >94 μm). The highest proportions of l‐SRB and a‐SRB were found in the 10–94 μm fraction: 66–97% for l‐SRB and 53–98% for a‐SRB. The highest proportion of p‐SRB was found in the >94 μm fraction (70–74%). These results indicate that most SRB were associated with sediment particles. One isolate from an acetate‐utilizing enrichment culture was similar to Desulfotomaculum acetoxidans, a spore‐forming sulfate‐reducing bacterium. When lactate and sulfate were added to sediment samples, l‐SRB and a‐SRB in the <10 μm‐fraction grew more rapidly than those in whole sediment for the first 2 days. This result suggests that nutrients uptake by free‐living and small particle‐associated (<10 μm) SRB is higher than that by SRB associated with larger particles.
Changes in foliage distribution with relative irradiance and tree size: Differences between the saplings of Acer platanoides and Quercus robur
Authors: Niinemets Ülo
Published: March 2006

Dependencies of foliage arrangement and structure on relative irradiance and total height (TH) were studied in saplings of Acer platanoides and Quercus robur. The distribution of relative foliar area and dry weight (leaf area and weight in a crown layer per total tree leaf area and weight, respectively) were examined with respect to relative height (RH, height in the crown per TH) and characterized by the Weibull function. The distributions of relative area and weight were nearly identical, and the differences between them were attributable to a systematic decline in leaf dry weight per area with increasing crown depth. Foliage distribution was similarly altered by tree size in both species; RH at foliage maximum was lower and relative canopy size (RCS, length of live crown per TH) greater in taller trees. However, the distribution was more uniform in A. platanoides than in Q. robur. Apart from the size effects, relative irradiance also influenced canopy structure; RCS increased in Q. platanoides and decreased in Q. robur with increasing irradiance. As crown architecture was modified by irradiance, foliage distribution was shifted upwards with decreasing irradiance in A. platanoides, but it was independent of irradiance in Q. robur. Higher foliage maximum at lower irradiance in more shade‐tolerant A. platanoides is likely to contribute towards more efficient foliar display for light interception and increase the competitive ability of this species in light‐limited environments. Consequently, these differences in crown architecture and foliage distribution may partly explain the superior behavior of A. platanoides in understory.
Production and population ecology of Phyllospadix iwatensis Makino. II. Comparative studies on leaf characteristics, foliage structure and biomass change in an intertidal and subtidal zone
Authors: Yabe Tohru , Ikusima Isao , Tsuchiya Takayoshi
Published: March 2006

A seagrass in Japan, Phyllospadix iwatensis Makino, is distributed in the lower intertidal zone and upper subtidal zone making a dense population on the Choshi coast, Japan. Intertidal P. iwatensis is able to receive sufficient light for photosynthesis but experienced severe exposure to the air, which decreased a large amount of aboveground biomass in April to June (i.e. the daytime exposure season). Subtidal P. iwatensis was never exposed throughout the year and the aboveground biomass increased gradually over the daytime exposure season. However, the maximum aboveground biomass and shoot density of the subtidal plant never exceeded that of the intertidal plant. The dense foliage, large aboveground biomass and high shoot density of both intertidal and subtidal plants is likely to be an adaptation to heavy water movement, but the subtidal plants always received insufficient light for photosynthesis as a result of having dense foliage, particularly in turbid water. In choppy and swell sea, P. iwatensis did not seem to be adapted to growing in the subtidal zone where there was shortage of light.
Topographic variations of soil properties and stand structure in aPinus thunbergiiplantation
Authors: Enoki Tsutomu , Kawaguchi Hideyuki , Iwatsubo Goro
Published: March 2006

Soil properties and above‐and belowground forest structure were studied across various topographies in a 20‐year‐oldPinus thunbergiiParl. plantation on Mt Tanakami, Japan. The soil properties and stand structure varied greatly with slope position fromridge top to valley floor. Soil thickness, fine soil content and soil moisture content were greater in lower slope positions. The amount of organic carbon in the forest floor was greater in upper slope positions. The organic carbon content in the mineral soil was slightly greater in lower slope positions. These changes in soil properties suggested an upslope decrease in decomposition rate and water and/or nutrient availability. The aboveground structure ofP. thunbergiiwas more developed at lower slope positions. The mean stem diameter, height and volume ofP. thunbergiiincreased downslope with decreasing tree density. However, fine root biomass increased greatly upslope. This inverse relationship between tree height and fine root biomass indicated morphological plasticity ofP. thunbergiiin exploiting environmental heterogeneity. Variations in soil‐plant interactions in the stand along various topographies caused spatial heterogeneity in the accumulation pattern of organic matter in plants and the soil.
Resource availability and growth responses to defoliation in seedlings of three early‐successional, tropical, woody species
Authors: Lim W. H. L. , Turner I. M.
Published: March 2006

A growth experiment was conducted using seedlings of three early‐successional, tropical, woody species:Dillenia suffruticosa (Dilleniaceae), Macaranga heynei (Euphorbiaceae) and Trema tomentosa (Ulmaceae). These species are characteristic of different positions along a soil fertility gradient in Singapore, with D. suffruticosa being the least and T. tomentosa the most demanding of high nutrient availability. The seedlings were grown in vermiculite at either low or high nutrient availabilities supplied by watering with different concentrations of a commercial plant food. Half the seedlings were subjected to a 50% defoliation at the start of the experiment by cutting off the distal half of each leaf. After 9 weeks the plants were harvested. Macaranga heynei and T. tomentosa seedlings showed no significant difference in parameters of growth such as total dry weight and total leaf area between the defoliated and control seedlings. The seedlings compensated completely for the loss of leaf area. Dillenia suffruticosa did show significant reductions in growth in some parameters due to defoliation, and these were more pronounced under the high nutrient treatment. These findings support the hypothesis that plants characteristic of resource‐rich sites can readily recover from herbivory through fast growth, probably associated with a rapid turnover of leaves, whereas species of resource‐poor habitats cannot easily replace losses due to herbivory and are adversely effected by defoliation.
Different responses of pollinating bees to size variation and sexual phases in flowers of Campanula
Authors: Inoue Ken , Maki Masayuki , Masuda Michiko
Published: March 2006

To examine the response of pollinating bees to size and sexual phases of flowers, we constructed an artificial population of Campanula having large flower variation and presented it to potentially pollinating bees in nurseries. The pollinating bee groups (halictid, megachilid and bumble bees) responded differentially to both the flower size and to the sexual phases of the flowers. Whereas visitation rate of megachilid bees increased with the flower size, those of halictid bees and bumble bees did not show particular trends; for example, bumble bees visited almost all of the flowers consistently. Visitation frequencies to male‐and female‐phased flowers were significantly different between megachilids at Tokyo and halictids. This study indicates that pollinator attraction could not solely explain the evolution of the flower size in Campanula, and that other factors such as pollen transfer efficiency, should be considered.
Habitat preference, food habits and growth of juveniles ofLates angustifronsandLates mariae(Pisces: Centropomidae) in Lake Tanganyika
Authors: Kondo Takaki , Abe Naoya
Published: March 2006

Habitat preference of juveniles ofLates angustifronsandLates mariae, endemic fish species in Lake Tanganyika, was investigated in the field and in the laboratory. Both species settle on the grass bed after the post‐larval pelagic phase.L. angustifronspreferred the short grass bed composed ofVallismeriasp., whileL. mariaepreferred the tall grass bed composed ofPotamogeton schweinfurthii. L. angustifronsalways rested near the root, keeping a position parallel to the bottom; dark cross bands on the body may be advantageous as camouflage in the short grass bed. On the other hand,L. mariaealways stayed in mid‐water, keeping a head‐down position parallel to a leaf or stem of grass; such posture and longitudinal stripes on the body may be advantageous as camouflage in the tall grass bed. Both species were more active at night, and fed mainly on atyid shrimps.Lates angustifronsshifted its main food from shrimps to fish with growth, as was suggested inL. mariae. Difference in the habitat preference may play an important role in their coexistence.
Responses in spatial organization to manipulations of the food resource in polygynandrous alpine accentors
Authors: Nakamura Masahiko
Published: March 2006

The alpine accentorPrunella collarisis a territorial and polygynandrous mating species. The breeding unit is a group consisting of about seven members who share a group territory which contains all the resources necessary for living. Each female holds a small territory around her own nest within the larger group territory. Supplemental food in the form of millet seed was provided for a total of 23 group territories to test the hypothesis that the abundance and distribution of food influences the size of a female's territory and her dispersion pattern which, in turn, determine the mating system. Both males and females had regular access to the feeders, but females and groups provided with feeders did not have smaller territories than those without feeders. No groups were divided into two by offering extra food. Provision of extra food resulted in an increase of group size but did not alter the sex ratio. All members, including new settlers, were sexually active and the sexual relationships among the members of a group were still multiple matings. Food addition did not prompt the fed females to choose nest sites nearer the feeder. Nest sites were restricted to particular rocky slopes and non‐vegetated areas which were invariably free from snow each year due to the effects of strong winds and the topography. Females showed a nest‐site fidelity for successive years. The reason why supplemental food had no effect on the territory size or dispersion of female alpine accentors is discussed.
Production and population ecology of Phyllospadix iwatensis Makino. I. Leaf growth and biomass in an intertidal zone
Authors: Yabe Tohru , Ikusima Isao , Tsuchiya Takayoshi
Published: March 2006

In an intertidal zone on Choshi coast, Japan, Phyllospadix iwatensis Makino emerges at daytime in spring and summer, while at night time in winter. The plants therefore experience seasonally different stresses caused by emergence, for example, intense light, ultraviolet rays, extreme temperature and desiccation, all of which the plants are unable to avoid during daytime emergence. Seasonal changes in the biomass and LAI suggest that the optimum periods for growth of P. iwatensis would be in March when the emergent period is short or nil and light availability is high while water temperature is not too low. Dense foliage and low canopy height of P. iwatensis in the intertidal zone relieve the plant from the stresses in emergent periods and from the disturbance caused by strong water movement in some coastal areas with active wave action.
The effect of color polymorphism on mortality in the aphid Macrosiphoniella yomogicola
Authors: Agawa Hiroko , Kawata Masakado
Published: March 2006

We examined body color polymorphism in the aphid Macrosiphoniella yomogicola from July to September 1993. We classified body color into eight types: green 1, green 2, red 1, red 2, white, orange, yellow and mist. The frequencies of body color varied with time and among patches of the host plant, yomogi (Artemisia spp.). Color diversity within a shoot was calculated using the Shannon diversity index. Of five usable data sets, three showed negative relationships between color diversity and mortality. The regression coefficients for two of these relationships were significant. No significant relationship between mortality and the number of aphids was found. The color diversity was not significantly related to a particular body color found on a yomogi shoot. Color polymorphism may be maintained because selection may favor a high color diversity on the host plant shoot.
Establishment and maintenance of the breeding territory in the polygynous great reed warbler
Authors: Ezaki Yasuo
Published: March 2006

Settlement of male great reed warblers in the breeding ground was highly asynchronous at Lake Biwa in Japan. It took over 1 month from the appearance of the first male to a saturation in number of males. In resource‐defense‐polygyny, males are expected to try to defend as large an area as possible in the optimal habitat. In fact, a small number of the earliest settling males divided up the breeding ground almost completely as territories among themselves and these were later reduced in size with the addition of later settlers. The reduction was not due to a seasonal decline of aggressiveness on the part of the owners but to a higher level of intrusion pressure by later arriving males. The neighbor‐neighbor relationship, once established, was rather stable. Home range overlap was small and territorial contacts were few between neighbors. Territorial boundaries seem not to shift despite the addition of new males as long as the neighbors were the same. The stable relationships between neighbors are expected to help the earlier resident to maintain his large and good territories throughout the breeding season and hence polygyny is favored in this species.
Size dependency of gametophytes decay in Athyrium brevifrons Nakai during spring desiccation
Authors: Sato Toshiyuki
Published: March 2006

Gametophyte populations in Athyrium brevifrons were analysed with respect to population size and surviving area (%) of individual thalli in a transplant garden at Sapporo during 5–26 April 1983, to study the safe‐microsite for gametophyte establishment in nature. Spores dispersed in August 1982 germinated and grew into thalli of various widths (<10 mm); 10.3% of the thalli matured by early October 1982. Maturation was attained by gametophytes of width 4–7 mm. The number of gametophytes gradually decreased with increasing width. By April 1983, 20.5% of total gametophytes were mature with a mode of 5–6 mm in width. The relative number of gametophytes with surviving area of 2–20% increased and that of 85–100% decreased in accordance with collection days delayed until after snow‐melt. Surviving area (%) on gametophyte of all widths decreased with decreasing soil moisture contents. In particular, immature gametophytes of 2–4 mm width showed a significant correlation (P<0.01) between soil moisture content and relative number of gametophytes with 0–20% surviving area and mean surviving area (%) of every width of thalli. The spring desiccation might be a factor that reduces or limits gametophyte populations in nature.
Succession of sessile organisms on experimental plates immersed in Nabeta Bay, Izu Peninsula, Japan V. An integrated consideration on the definition and prediction of succession
Authors: Hirata Tetsu
Published: March 2006

Successional changes of sessile organisms over about 3 years on concrete plates immersed at depths of 1.0, 2.5, 4.0 and 5.5 m in Nabeta Bay, Shimoda, Pacific coast of Japan, were investigated from their species composition, percentage cover, and the structure, metabolism, biomass and maturity of the community for the purpose of verifying the hypothesis of succession by Margalef (1968) and Odum (1969). The process of succession was divided into five stages from a cluster analysis based on Horn's (1966) similarity in community structure. The five stages were characterized from dominant, species and 18 community attributes in terms of structure, metabolism, biomass and maturity. With the advance of stages, two large‐sized, long‐lived species, the kelp Eisenia bicyclis and the oyster Crassostrea nippona, dominated; 18 community attributes showed a directional succession ending in a constant community structure, low community metabolism, accumulation of community biomass except chlorophyll a and an enhanced degree of community maturity. This directionality in succession of community attributes was valid for the prediction of Margalef and Odum, despite a tendency for estimated daily energy budget to be more heterotrophic in such an open system. From these results, it was suggested that the definition of succession by Odum (1969) should be interpreted as the regularity in shift of dominant species, not individual species, and as the control of system by feedback mechanism developing with succession rather than community‐controlled mechanism.
Overlapping territories of Pseudosimochromis curvifrons males and other herbivorous cichlid fishes in Lake Tanganyika
Authors: Kuwamura Tetsuo
Published: March 2006

Males of the herbivorous cichlid fish Pseudosimochromis curvifrons established mating territories 3–10 m in diameter, which included both spawning and feeding sites. Territorial males attacked conspecific males and also other species. Only conspecific males were chased out of the territories. Territorial males attacked other species at the spawning sites while courting or waiting for females and at other sites in their territories while patrolling and foraging. Attacks against herbivorous species were more frequent than against non‐herbivores since herbivores were much more abundant. Territories of four abundant herbivorous cichlids largely overlapped the territories of P. curvifrons males. Symbiotic relationships were not detected between the species. Instead, they were aggressive towards each other but coexisted by segregating feeding sites in the overlapping areas. The aggressive coexistence of P. curvifrons males with other herbivores may have resulted from the energetic costs of defending their relatively large territories against all food competitors. Interspecific food‐resource partitioning may also have facilitated the coexistence.
Optimal seasonal timing of univoltine and bivoltine insects
Authors: Iwasa Yoh , Yamauchi Atsushi , Nozoe Shinji
Published: March 2006

This study examines the optimal seasonal timing of the life cycle for univoltine and bivoltine insects, assuming that resource availability has a peak in the middle of a year and is symmetric around it. Results show that if the growth rate increases in proporrion to the bodyweight, bivoltine life cannot be optimal. If the growth rate is a power function of the bodyweight with a power smaller than unity, a symmetric bivoltine solution can be the optimal provided that the resource availability has a plateau in the middle of the season. If the resource availability has a sharp peak, the optimal pattern is an asymmetric bivoltine solution in which the larval periods of two generations differ in length. The bivoltine life cycle is more likely to be superior to the univoltine one if: growth is fast, suitable growing season is long, biomass loss during nonlarval stages is small, and egg size is small.
Importance of communal foraging grounds outside the reed marsh for breeding great reed warblers
Authors: Ezaki Yasuo
Published: March 2006

Foraging habitat selection of breeding great reed warblers was studied at a shore of Lake Biwa. The foraging grounds of parent warblers during the nesting period were not restricted to the breeding territory of the reed marsh, their nestling habitat. The paddy field outside the reed marsh was used communally by them throughout the breeding season. Females with early stage nestlings did not visit the paddy field whereas when nestlings were older than 3 days, more than half of their total food was collected there. Females with nests adjacent to the paddy field tended to exploit the paddy field more often than those with nests distant from it. Monogamously mated females tended to exploit the paddy field more often than polygynously mated females. Food collected in the paddy field was larger than that in the reed marsh and parent birds were prepared to travel longer distances to exploit the rich source of food in the paddy field. The importance of the communal foraging ground outside the reed marsh as a background of the polygynous mating system of this species is discussed.
Gap‐detecting mechanism in the seed germination of Mallotus japonicus (Thunb.) Muell. Arg., a common pioneer tree of secondary succession in temperate Japan
Authors: Washitani Izumi , Takenaka Akio
Published: March 2006

Germination responses of Mallotus japonicus (Thumb). Muell. Arg. seeds to temperature revealed a gap‐detecting mechanism in the seed germination of the species. Among various constant and alternating temperatures examined in the range from 12–40°C, only very limited temperature regimes were found to be favourable for seed germination, specifically, alternating temperatures between 18–32°C and 28–40°C. A single several‐hour higher‐temperature (32–40°C) treatment could also induce the germination of seeds which had been imbibed for several days at a constant temperature in the range of 20–26°C, suggesting that there is a process requiring higher temperature among the overal germination processes. Seeds located at or near the surface of denuded soil would have a good chance of experiencing such a temperature change when several rainy days are followed by fine weather, while seeds beneath close vegetation would not. On the other hand, the pressence or absence of light or a simulated ‘canopy ligh’ had little effect on the germination. Therefore, it was concluded that the seeds of M. japonicus have a ‘gapdetecting mechanism’ in the form of a higher‐temperature requirement of a certain process involved in the overall germination processes.
Production dependence of vegetative propagation in Disporum smilacinum A. Gray
Authors: Hori Yoshimichi , Yokoi Tomoko , Yokoi Yota
Published: March 2006

The dependence of vegetative propagation on the production of individual plants was examined in Disporum smilacinum A. Gray on the basis of shading experiments and field surveys. This species typically showed four types of reproductive behavior: sterile plants producing one plantlet (no propagation), sterile plants producing more than two plantlets (vegetative propagation), fertile plants producing one plantlet (sexual reproduction) and fertile plants producing more than two plantlets (both sexual reproduction and vegetative propagation).

The propagation of D. smilacinum was clearly related to the annual net production of each individual plant. The probability of a mother plant producing more than two vegetative propagules (plantlets) increased with net production of the plant in the current year. The number of propagules per plant and runner length increased with net production.

It was possible to explain the types of reproductive behavior of this species on the basis of both the initial plant size before sprouting and its net production during the growing season. There was a critical initial plant size for sexual reproduction and a critical level of production for vegetative propagation.
The effect of tubificids and chironomids on particle redistribution of lake sediment
Authors: Fukuhara Haruo
Published: March 2006

The effects of chironomid larvae, Chironomus plumosus, and tubificid worms, Limnodrilus spp., on particle redistribution in lake sediment were investigated experimentally using pots containing sediments obtained from Lake Suwa, Japan. The chironomids and tubificids increased the water content of surface sediment. The chironomid larvae had no effect on particle size distribution, while tubificids continuously accumulated small particles on the surface sediment through their selective feeding activity. Particles larger than 0.125 mm were buried at a sediment depth of 6 cm. In Lake Suwa, long diatom frustules, large plant debris and blue‐green algal flocs were found to accumulate in the deeper layer of the lake sediment inhabited by tubificids at high density.
Den distribution and den use by the red fox Vulpes vulpes japonica in Kyushu
Authors: Nakazono Toshiyuki , Ono Yuiti
Published: March 2006

The distribution of dens and den use by the red fox was studied in Kumamoto Prefecture between 1968 and 1982. A total of 80 dens were classified into natal, residential, and temporarily‐visited dens. Natal dens comprised 12.4% of all dens. Relative proportions were quite stable for a long period. This indicates a constant number of reproducing females in the area for a considerable length of time. Seasonally the utilization of den showed three peaks in February, May and October. The peaks coincided well with the peaks of reproductive activity of female foxes. The results of multiple regression analysis of distribution of dens with respect to selected environmental parameters around densites indicated that the fox selectively utilize open land, rather than densely vegetated areas. The persistence of dens, the selective utilization by foxes of open land and the sizes of dens were all related to the breeding activities of female foxes inhabiting the area. Reproductive females usually used plural dens (“den group”) in one reproductive season. The numbers of those females occuring in the area were maintained at a steady level for fairy long periods. These indicate that the existence of a stable social relationship between females mediated through occupancy of “den groups.”
The ecology of Carex oxyandra II. The behavior of seedlings and tillers
Authors: Tsujimura Azuma
Published: March 2006

A study on the seedlings and tillers of Carex oxyandra, a pioneer perennial, was carried out at Mt. Bandai, Fukushima Prefecture, Japan. A field experiment showed that seedlings had a rather low rate of growth, a small biomass and a high mortality rate. On the other hand, tillers in clones befan growth much earlier, had a rapid growth rate and grew to a larger body size. Furthermore, there was a considerable difference in growth pattern between tillers without flowers and those with flowers; tillers without flowers had a longer growing season and a larger amount of leaves, roots and new rhizomes. The numerical proportions of these two types of tillers in clones varied with clonal vigor.
Rat bone marrow erythroid cell fractionation by counter current distribution in non-charge-sensitive two-phase systems
Authors: Garcia-Pérez A. I. , Sancho P. , Mendieta J. , Luque J.
Published: March 2006

Counter-current distribution in non charge-sensitive aqueous poly(ethylene glycol)-dextran two phase systems allows the fractionation of rat bone marrow cells into two broad cell subpopulations with different distribution coefficients in a relatively short time. Morphological identification and enzymatic studies suggest that erythroid cells are mainly present in the subpopulation with the higher distribution coefficient. The distribution coefficient and, therefore, surface hydrophobicity of these cells, apparently increase in parallel with an increase in their degree of differentiation and maturation.