bluuebunny/crossref_metadata_2025_split huggingface dataset:
Long‐term canopy dynamics analysed by aerial photographs in a temperate old‐growth evergreen broad‐leaved forest
Authors: Fujita Takashi , Itaya Akemi , Miura Masahiro , Manabe Tohru , Yamamoto Shin‐Ichi 
Published: July 2003

Summary

We used aerial photographs to analyse canopy dynamics over 32 years in a 4‐ha permanent plot of an old‐growth evergreen broad‐leaved forest in the Tatera Forest Reserve, south‐western Japan.
We used aerial photographs taken in 1966, 1983, 1993 and 1998 to create digital elevation models (on a 2.5‐m grid) of the canopy surface in a 10‐ha area that included the 4‐ha plot. A topographic map of the ground surface of the 4‐ha plot was also created from ground measurements taken in 1990. The canopy height at each location was calculated and the ‘vegetation height profile technique’ was applied to quantify canopy dynamics.
The size distributions of gaps at each observation time showed peaks at both small and intermediate sizes. The total number of gaps and gap density increased over the study period, while total gap area, mean gap size and maximum gap size fluctuated. While the overall mean rates of gap formation and closure (0.58 vs. 0.50% year−1) were nearly balanced, we found large temporal variation.
Of the 6400 of 2.5 × 2.5‐m quadrats, 3.4% remained as gaps throughout the 32‐year period. These tended to be in the centres of large, old gaps, whereas those that experienced re‐disturbance (2.5%) were distributed along the edges of old gaps. A large proportion (74.5%) maintained a closed canopy state.
Meteorological data suggested that the variation in gap formation and gap closure rates may be related to year‐to‐year variations in the number and severity of typhoons.
This study suggests that long‐term and large openings are essential for the establishment of deciduous broad‐leaved and shade intolerant pioneer species in predominantly evergreen broad‐leaved forests.
Seed dispersal patterns produced by white‐faced monkeys: implications for the dispersal limitation of neotropical tree species
Authors: Wehncke E. V. , Hubbell S. P. , Foster R. B. , Dalling J. W. 
Published: July 2003

Summary

Primate frugivores are important seed dispersers for a large fraction of tree species in many tropical forests. The movement, diet preferences and defecation patterns produced by primates may therefore strongly influence seed dispersion patterns and seedling recruitment success. Here we examine the pattern of seed dispersal generated by white‐faced monkeys (Cebus capucinus) in relation to adult tree distribution in the 50‐ha plot on Barro Colorado Island (BCI), Panamá.
Diet breadth of Cebus was remarkably wide. Over four months they consumed fruits of 95 out of an estimated 240 species available. Seeds of 67 species passed intact through the gut and 28 were spat out.
Dispersal effectiveness of Cebus was also high. Two Cebus groups on average spent < 10 min feeding in individual trees, had large home ranges (> 150 ha), travelled 1–3 km day−1 and defecated seeds in small clumps throughout the day.
Mean dispersal distance of ingested seeds was 216 m (range 20–844 m), with the highest probability of dispersal 100–200 m from the parent plant. For six of nine species studied, the distance between defecation sites and nearest conspecific adults of seeds in faeces was not significantly different from random expectations.
The scattered dispersal pattern produced by Cebus suggests that this species contributes relatively little to dispersal limitation (sensu) compared to other dispersers in the community. Long‐distance dispersal by Cebus resulted in substantial movement of seeds in and out of the 50 ha plot, and suggests that inverse modelling procedures to estimate dispersal functions from trap data may not adequately describe dispersal patterns generated by this primate.
The effects of spatial pattern of nutrient supply on yield, structure and mortality in plant populations
Authors: Day Kieron J. , Hutchings Michael J. , John Elizabeth A. 
Published: July 2003

Summary

Early in growth, plant populations subjected to heterogeneous conditions can achieve significantly higher yields than populations grown in homogeneous conditions that provide the same amount of nutrients. We hypothesized that this yield enhancement would be ephemeral, and that yields of populations grown under different patterns of nutrient supply will converge as time passes. We also predicted that plant size frequency distributions will continue to differ between populations in heterogeneous and homogeneous conditions, that spatial patterns of mortality will differ, and that greater mortality will occur in populations under heterogeneous conditions. An experiment was carried out on Cardamine hirsuta to test these hypotheses.
The experiment was harvested after 60 days, when flowering had begun in all populations. At this time, populations grown with the same nutrient supply but different patterns of supply did not differ in yield. Populations grown at higher nutrient levels had greater yields but suffered more mortality.
In heterogeneous conditions, plants in nutrient‐rich locations were larger than plants in nutrient‐poor locations, and larger than plants in identical positions in populations growing under homogeneous conditions. Plants in nutrient‐rich patches in heterogeneous treatments suffered more mortality than plants in nutrient‐poor patches. Contrary to prediction, total mortality at all levels of nutrient supply was significantly higher in populations in homogeneous conditions.
Coefficient of variation in shoot sizes was higher in populations at higher nutrient levels, but unaffected by pattern of nutrient supply. CV of root mass per unit of substrate was greater under heterogeneous than homogeneous conditions.
Frequency distributions of shoot size, and root mass per unit of substrate, were strikingly different between populations grown under different patterns of nutrient supply. The differences are interpreted as showing that under homogeneous conditions all parts of the habitat are heavily exploited, giving rise to uniformly high levels of interplant competition. In contrast, nutrient‐poor patches in the heterogeneous treatments contain low root masses. Plants in these patches remain small, but have a high probability of survival. We propose that these differences in intensity of habitat occupation, and presumably in competition, explain the lower mortality in populations growing under heterogeneous conditions.
Asymmetric competition and the evolution of propagule size
Authors: Rodríguez‐Gironés M. A. , Sandsten H. , Santamaría L. 
Published: July 2003

Summary

In an asexually reproducing plant (Potamogeton pectinatus L.) the competitive advantage of a larger propagule over a smaller one was determined by a single parameter (α, the competitive asymmetry coefficient), independent of sowing density or average propagule size. Competitive advantage was determined by the relative size difference between propagules instead of their absolute difference.
Productivity per germination site increased with the number and size of propagules present, even at densities high enough to result in decreased per capita yield due to plant competition.
Both the number of propagules produced by a plant and their size increased with increasing per capita resource capture. Therefore, propagule size was neither equal to the size of the propagule from which the plant germinated nor independent of resource status.
Our results clarify what assumptions should be made in ecological and evolutionary models dealing with competition for resources between seedlings. In particular, the use of relative size differences instead of absolute ones should lead to the evolution of smaller propagules than those expected if competitive advantage grew with absolute propagule size.
Spatial patterns of maternal lineages and clones of Galium odoratum in a large ancient woodland: inferences about seedling recruitment
Authors: Ziegenhagen Birgit , Bialozyt Ronald , Kuhlenkamp Vivian , Schulze Inge , Ulrich Andreas , Wulf Monika 
Published: July 2003

Summary

We investigated spatial genetic patterns in the clonal herbaceous plant species Galium odoratum L., which has previously been shown to be significantly associated with ancient woodlands.
A maternally inherited chloroplast DNA marker was developed for G. odoratum. Seven chloroplast haplotypes were detected in the study area and mapped at different spatial scales. Their spatial patterns suggest that both local and non‐local gene flow occurs via seeds.
Fingerprints from DIG‐labelled AFLP technology were validated as markers for G. odoratum clone identification. A single primer–enzyme combination was sufficient to distinguish between clones. A typical patch of G. odoratum is composed of numerous genets, mainly occurring in separate clusters of ramets, which may be several meters in diameter.
Pairwise similarities, calculated from the AFLP banding patterns, were used for spatial autocorrelation analysis. The distinct spatial genetic structure at the patch level may be due to the genetic similarity of neighbouring genets or to clonal growth.
The spatial patterns obtained using the two DNA markers, suggest that a mixture of local and non‐local gene flow via both seeds and pollen is occurring. Repeated seedling recruitment (RSR) would be consistent with the life history of G. odoratum in ancient woodlands with long‐term spatial continuity.
Chemokine Upregulation Follows Cytokine Expression in Chronic Relapsing Experimental Autoimmune Encephalomyelitis
Authors: Glabinski A. R. , Bielecki B. , Ransohoff R. M. 
Published: July 2003

AbstractChronic relapsing experimental autoimmune encephalomyelitis (ChREAE) is an autoimmune disease of the central nervous system (CNS) induced by CNS myelin components. In the early active stage, both ChREAE and multiple sclerosis (MS) are characterized by the presence of perivascular inflammatory cuffs disseminated in the CNS. There is growing evidence that chemoattractant cytokines (chemokines) play an important role in this process. The main goal of the present study was to analyse the hypothesis that chemokine expression in the CNS during autoimmune inflammation is regulated by proinflammatory cytokines. To address this concept, we analysed temporal relations between chemokine and cytokine expression during ChREAE. Phasic upregulation of gene expression for chemokines T‐cell activation gene 3 (TCA‐3)/CCL1, monocyte chemoattractant protein‐1 (MCP‐1)/CCL2, macrophage inflammatory protein‐1 alpha (MIP‐1α)/CCL3, MIP‐1β/CCL4, regulated on activation normal T cell expressed and secreted (RANTES)/CCL5 and MIP‐2/CXCL2–3 as well as cytokines tumour necrosis factor‐α (TNF‐α), ‐β, LT‐β, interferon‐γ (IFN‐γ) and transforming growth factor‐β1 (TGF‐β1) in the CNS was observed during attacks of ChREAE. Expression of cytokines TNF‐β and LT‐β preceded, and the expression of TGF‐β1 followed chemokine upregulation. Our results suggest that chemokine expression during CNS autoimmune inflammation may be regulated by some proinflammatory cytokines.
The dynamin‐like protein ADL1C is essential for plasma membrane maintenance during pollen maturation
Authors: Kang Byung‐Ho , Rancour David M. , Bednarek Sebastian Y. 
Published: July 2003

SummaryDynamin‐related GTPases regulate a wide variety of dynamic membrane processes in eukaryotes. Here, we investigated the function of ADL1C, a member of the Arabidopsis 68 kDa dynamin‐like protein family. Analysis of heterozygous adl1C‐1 indicates that the mutation specifically affects post‐meiotic male gametogenesis. Fifty percent of the mature pollen from heterozygous adl1C‐1 androecia are shriveled and fail to germinate in vitro. During microspore maturation, adl1C‐1 pollen grains display defects in the plasma membrane and intine morphology, suggesting that ADL1C is essential for the formation and maintenance of the pollen cell surface and viability during desiccation. Consistent with a role in cell‐surface dynamics, immunofluorescence microscopy indicates that ADL1C is localized to the cell plate of dividing somatic cells and to the tip of expanding root hairs. We propose that ADL1C functions in plasma membrane dynamics, and we discuss the role of the ADL1 family in plant growth and development.
Microfilaments and microtubules control the morphology and movement of non‐green plastids and stromules in Nicotiana tabacum
Authors: Kwok Ernest Y. , Hanson Maureen R. 
Published: July 2003

SummaryPlastid stromules are stroma‐filled tubular extensions of the plastid envelope membrane. These structures, which have been observed in a number of species, allow transfer of proteins between interconnected plastids. The dramatic shape of stromules and their dynamic movement within the cell provide an opportunity to study the control of morphology and motion of plastids. Using inhibitors of actin and tubulin, we found that both microfilaments and microtubules affect the shape and motility of non‐green plastids. Actin and tubulin control plastid and stromule structure by independent mechanisms, while plastid movement is promoted by microfilaments but inhibited by microtubules. The presence or absence of stromules does not affect the motility of plastids. Photobleaching experiments indicate that actin and tubulin are not necessary for the bulk of green fluorescent protein (GFP) movement between plastids via stromules.
Signaling of systemic acquired resistance in tobacco depends on ethylene perception
Authors: Verberne Marianne C. , Hoekstra Jan , Bol John F. , Linthorst Huub J.M. 
Published: July 2003

SummaryThe hypersensitive interaction between Tobacco mosaic virus (TMV) and tobacco results in accumulation of salicylic acid (SA), defense gene expression, and development of systemic acquired resistance (SAR) in uninfected leaves. The plant hormones SA and ethylene have been implicated in SAR. From a study with ethylene‐insensitive (Tetr) tobacco, we concluded that ethylene perception is required to generate the systemic signal molecules in TMV‐infected leaves that trigger SA accumulation, defense gene expression, and SAR development in uninfected leaves. Ethylene perception was not required for the responses of the plant to the systemic signal that leads to SAR development.
Mutations in the huge Arabidopsis gene BIG affect a range of hormone and light responses
Authors: Kanyuka Konstantin , Praekelt Uta , Franklin Keara A. , Billingham Olivia E. , Hooley Richard , Whitelam Garry C. , Halliday Karen J. 
Published: July 2003

SummaryIn independent genetic screens, for shade‐avoidance response and cytokinin sensitivity, we identified two Arabidopsis mutants, attenuated shade avoidance 1 (asa1) and umbrella1 (umb1), which have very similar pleiotropic phenotypes. asa1 and umb1 are allelic to tir3‐1, and are caused by mutations in BIG, which is required for normal auxin efflux. They have a compact rosette, fewer lateral roots, delayed flowering, more secondary inflorescence, smaller seeds and, in the Laer‐0 background, much shorter internodes between adjacent flowers, suggesting an interaction between BIG and ERECTA. These mutants have organ‐specific defects in response to cytokinins, ethylene, N‐1‐naphthylphthalamic acid (NPA) and gibberellin (GA). The phenotype of the asa1 ga1‐3 double mutant is consistent with defects in GA signalling. There are subtle effects in responses to auxins, abscisic acid and brassinolide. Elongation growth associated with shade avoidance in phyA phyB null mutants is suppressed by asa1 in all organs other than the hypocotyl. Therefore, we here provide evidence that BIG is a key player not just in auxin signalling, but in a multitude of light and hormone pathways.
Where do gibberellin biosynthesis and gibberellin signaling occur in rice plants?
Authors: Kaneko Miyuki , Itoh Hironori , Inukai Yoshiaki , Sakamoto Tomoaki , Ueguchi‐Tanaka Miyako , Ashikari Motoyuki , Matsuoka Makoto 
Published: July 2003

SummaryTo identify where gibberellin (GA) biosynthesis and signaling occur, we analyzed the expression of four genes involved in GA biosynthesis, GA 20‐oxidase1 and GA 20‐oxidase2 (OsGA20ox1 and OsGA20ox2), and GA 3‐oxidase1 and GA 3‐oxidase2 (OsGA3ox1 and OsGA3ox2), and two genes involved in GA signaling, namely, the gene encoding the α‐subunit of the heterotrimeric GTP‐binding protein (Gα), and SLENDER RICE1 (SLR1), which encodes a repressor of GA signaling. At the vegetative stage, the expression of OsGA20ox2, OsGA3ox2, Gα, and SLR1 was observed in rapidly elongating or dividing organs and tissues, whereas the expression of OsGA20ox1 or OsGA3ox1 could not be detected. At the inflorescence or floral stage, the expression of OsGA20ox2, OsGA3ox2, Gα, and SLR1 was also observed in the shoot meristems and stamen primordia. The overlapping expression of genes for GA biosynthesis and signaling indicates that in these tissues and organs, active GA biosynthesis occurs at the same site as does GA signaling. In contrast, no GA‐biosynthesis genes were expressed in the aleurone cells of the endosperm; however, the two GA‐signaling genes were actively expressed, indicating that the aleurone does not produce bioactive GAs, but can perceive GAs. The expression of OsGA20ox1 and OsGA3ox1 was observed only in the epithelium of the embryo and the tapetum of the anther. Based on the specific expression pattern of OsGA20ox1 and OsGA3ox1 in these tissues, we discuss the unique nature of the epithelium and the tapetum in terms of GA biosynthesis. The epithelium and the tapetum are considered to be an important source of bioactive GAs for aleurone and other organs of the flower, respectively.
Vacuolar malate uptake is mediated by an anion‐selective inward rectifier
Authors: Hafke Jens B. , Hafke Yuliya , Smith J. Andrew C. , Lüttge Ulrich , Thiel Gerhard 
Published: July 2003

SummaryElectrophysiological studies using the patch‐clamp technique were performed on isolated vacuoles from leaf mesophyll cells of the crassulacean acid metabolism (CAM) plant Kalanchoë daigremontiana to characterize the malate transport system responsible for nocturnal malic acid accumulation. In the presence of malate on both sides of the membrane, the current–voltage relations of the tonoplast were dominated by a strongly inward‐rectifying anion‐selective channel that was active at cytoplasmic‐side negative voltages. Rectification of the macroscopic conductance was reflected in the voltage‐dependent gating of a 3‐pS malate‐selective ion channel, which showed a half‐maximal open probability at −43 mV. Also, the time‐averaged unitary currents following a step to a negative voltage corresponded to the time‐dependent kinetics of the macroscopic currents, suggesting that the activity of this channel underlies the anion‐selective inward rectifier. The inward rectifier showed saturation kinetics with respect to malate (apparent Km of 2.5 mm malate2− activity), a selectivity sequence of fumarate2− > malate2− > Cl− > maleate2– ≈ citrate3–, and greater activity at higher pH values (with an apparent pK of 7.1 and maximum activity at around pH 8.0). All these properties were in close agreement with the characteristics of malate transport observed in isolated tonoplast vesicles. Further, 100 µm niflumate reversibly blocked the activity of the 3‐pS channel and inhibited both macroscopic currents and malate transport into tonoplast vesicles to the same extent. The macroscopic current densities recorded at physiological voltages and the estimated channel density of 0.2 µm−2 are sufficient to account for the observed rates of nocturnal malic acid accumulation in this CAM plant, suggesting that the 3‐pS, inward‐rectifying, anion‐selective channel represents the principal pathway for malate influx into the vacuole.
Visualization of abscisic acid‐perception sites on the plasma membrane of stomatal guard cells
Authors: Yamazaki Daiki , Yoshida Shigeo , Asami Tadao , Kuchitsu Kazuyuki 
Published: July 2003

SummaryAbscisic acid (ABA) is a phytohormone that plays a key role as a stress signal, regulating water relations during drought conditions, by inducing stomatal closure. However, to date, no putative ABA receptor(s) has been reported at the protein sequence, gene family, or cellular localization levels. We used biotinylated ABA (bioABA) to characterize the ABA‐perception sites in the stomatal guard cells of Vicia faba. Treatment with bioABA induced stomatal closure and shrinkage of guard cell protoplasts (GCPs). The ABA‐perception sites were visualized by fluorescence microscopy and confocal laser scanning microscopy (CLSM), using bioABA and fluorescence‐labeled avidin. Fluorescent particles were observed in patches on the surface of the GCPs. Fluorescence intensity was quantified by flow cytometry (FCM) as well as by CLSM. Binding of bioABA was inhibited by ABA in a dose‐dependent manner. Pre‐treatment of GCPs with proteinase K also blocked the binding of bioABA. Binding of bioABA was inhibited by RCA‐7a, an ABA analog that induces stomatal closure, but not by RCA‐16, which has no effect on stomatal aperture. Another ABA analog, PBI‐51, inhibited ABA‐induced stomatal closure. This ABA antagonist also inhibited binding of bioABA to the GCPs. These results suggest that ABA is perceived on the plasma membrane of stomatal guard cells, and that the present experimental methods constitute valuable tools for characterizing the nature of the ABA receptor(s) that perceives physiological ABA signals. These imaging studies allow us to demonstrate the spatial distribution of the ABA‐perception sites. Visualization of the ABA‐perception sites provides new insights into the nature of membrane‐associated ABA receptor(s).
Coordinate repression of regulators of embryonic identity by PICKLE during germination in Arabidopsis
Authors: Dean Rider Stanley , Henderson James T. , Jerome Ronald E. , Edenberg Howard J. , Romero‐Severson Jeanne , Ogas Joe 
Published: July 2003

SummaryIn angiosperms, germination represents an important developmental transition during which embryonic identity is repressed and vegetative identity emerges. PICKLE (PKL) encodes a CHD3‐chromatin‐remodeling factor necessary for the repression of expression of LEAFY COTYLEDON1 (LEC1), a central regulator of embryogenesis. A candidate gene approach and microarray analysis identified nine additional genes that exhibit PKL‐dependent repression of expression during germination. Transcripts for all three LEAFY COTYLEDON genes, LEC1, LEC2, and FUS3, exhibit PKL‐dependent repression, and all three transcripts are elevated more than 100‐fold in pkl primary roots that inappropriately express embryonic traits (pickle roots). Three other genes that exhibit PKL‐dependent regulation have expression patterns correlated with zygotic or somatic embryogenesis, and one gene encodes a putative Lin‐11, Isl‐1, MEC‐3 (LIM) domain transcriptional regulator that is preferentially expressed in siliques. Genes that exhibit PKL‐dependent repression during germination are not necessarily regulated by PKL at other points in development. Our data suggest that PKL selectively regulates a suite of genes during germination to repress embryonic identity. In particular, we propose that PKL acts as a master regulator of the LEAFY COTYLEDON genes, and that joint derepression of these genes is likely to contribute substantially to expression of embryonic identity in pkl seedlings.