bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abundance and flowering success patterns in a short‐term grazed grassland: early evidence of facilitation
Authors: BOSSUYT B. , DE FRÉ B. , HOFFMANN M. 
Published: September 2005

Summary

Associational resistance is a grazing avoidance mechanism resulting from herbivores being less inclined to eat palatable plant species when these species grow in association with unpalatable species. Such facilitative interactions between plant species may have important consequences for patterns of relative abundance and reproduction in plant communities.
We studied the relationship between abundance and flowering success of palatable species and the cover of three unpalatable species (Senecio jacobaea, Iris pseudacorus and Lysimachia vulgaris) in a grassland where moderately intense grazing (0.17–0.42 grazers ha−1) had been ongoing for 3 years. Plots were selected so that there were no systematic differences in microenvironmental conditions associated with the level of cover of unpalatable species.
Several palatable species had a higher frequency, cover and/or flowering success when they grew in the neighbourhood of an unpalatable species.
Several species (both palatable and unpalatable) were significantly taller in the vicinity of a large unpalatable species, probably due to the combined effects of grazing avoidance and increased light competition.
These facilitative effects, however, have not yet resulted in a higher local species richness or plant community evenness. It is nevertheless likely that more pronounced effects will be seen if grazing is continued, because facilitative interactions between plant species induced by grazing have already led to a shift in patterns of abundance and flowering success.
Regulation of the Pituitary Growth Hormone‐Releasing Hormone Receptor in Ageing Male and Female LOU Rats: New Insights into Healthy Ageing
Authors: Veyrat‐Durebex C. , Alliot J. , Gaudreau P. 
Published: September 2005

AbstractAgeing is characterised by a decrease of somatotroph functionality, involving growth hormone‐releasing hormone receptor (GHRH‐R). The present study was conducted in LOU/C/jall (LOU) rats, a strain described as a model of healthy ageing, which is characterised by a low adiposity and long life expectancy without developing severe pathologies. Effects of age and diet (chow versus self‐selection), on levels of anterior pituitary GHRH‐R mRNA transcripts, were assessed in male and female LOU rats. The effect of age on pituitary GHRH‐R functionality was examined in the anterior pituitary of both males and females fed chow diet. Moreover, serum insulin‐like growth factor‐I (IGF‐I), T4 and leptin were measured because changes in their concentration could affect GHRH‐R expression. In the pituitary of 18‐month‐old male and female LOU/C/jall rats fed standard chow, the level of 2.5‐kb GHRH‐R mRNA transcript, coding for functional GHRH‐R, was significantly decreased. In 24‐ to 34‐month‐old males and females, it progressively returned to the level of younger animals, suggesting an enrichment of the group with survivors maintaining functional GHRH‐R. In males and females repeatedly submitted to self‐selection, this phenomenon was not observed. Studies with the GHRH‐R agonist, Fluo‐GHRH, revealed that 73% of 16–18‐month‐old male and female rats studied did not show an increase of fluorescence density characteristic of receptor‐mediated internalisation upon incubation at 37 °C. In the other 27%, the increase of fluorescence was identical to that observed in pituitaries of young rats, suggesting the presence of an optimal level of functional GHRH‐R. Serum levels of leptin, free T4 and total IGF‐I decreased more drastically in ageing males and in rats fed a self‐selection diet. A positive correlation was demonstrated between leptin and IGF‐I levels in ageing males and females fed standard chow and ageing females submitted to a self‐selection regimen. In conclusion, healthy ageing in LOU rats fed chow diet appears to be associated with a maintenance of functional pituitary GHRH‐R levels found in younger rats but not necessarily with those of serum leptin, T4 and IGF‐I.
Effect of Rolipram, a Phosphodiesterase IV Inhibitor, on Allergic Footpad Swelling using Various Adjuvants in Mice
Authors: Yamaki K. , Alam A. H. M. K. , Hossain Md. A. , Taneda S. , Yanagisawa R. , Takano H. , Yoshino S. 
Published: September 2005

AbstractWe studied the effect of rolipram, a phosphodiesterase (PDE) IV inhibitor, on allergic footpad swelling in mice. For this study, varying adjuvants including complete Freund's adjuvant (CFA), incomplete Freund's adjuvant (IFA) and Imject Alum (Alum) were used because the extent of antigen‐specifically induced T helper type 1 (Th1) and Th2 responses had been shown to depend on adjuvants used. To induce allergic footpad swelling, we immunized mice with ovalbumin (OVA) emulsified in either CFA or IFA, dissolved in Alum or in phosphate‐buffered saline (PBS) as a control (day 0), followed by subcutaneous injection of the antigen into footpads on day 21. Rolipram was given orally to the animals daily from days 0–20. Results showed that treatment with rolipram was followed by an increase in early swelling at 0.5 h and a decrease in late swelling at 6 and 24 h in the CFA group. In the IFA group, rolipram significantly enhanced swelling at, but not after, 30 min. In the Alum and the PBS groups, the PDE inhibitor failed to affect the OVA‐specific footpad reaction at all times examined. Treatment of the CFA and IFA groups with rolipram significantly inhibited the production of the Th1 antibody anti‐OVA immunoglobulin G2a (IgG2a), and the drug enhanced Th2 cell‐dependent anti‐OVA IgE production. In both groups, rolipram also enhanced the secretion of Th2 cytokines including interleukin‐4 (IL‐4) and IL‐10. These findings suggest that rolipram may facilitate early allergic footpad swelling mediated by Th2 immune responses, while the late phase of swelling associated with Th1 responses may be attenuated by the PDE IV inhibitor.
A Commentary on the Zinkernagel–Hengartner ‘Credo 2004’
Authors: Cohn M. 
Published: September 2005

AbstractIn ‘Credo 2004’, Zinkernagel and Hengartner give us a food‐for‐thought analysis of immune responsiveness based on a ‘pragmatic and empiric point of view.’ The Credo 2004 postulates derived by inductive extrapolation from observation to generalization do not satisfactorily account for immune behaviour because they lack a conceptualization as illustrated here. Nevertheless, Credo 2004 is certainly valuable in a limited framework because it is based on the most likely of assumptions namely that the immune system was evolutionarily selected to protect against infectious agents, and therefore the study of pathogens will most accurately reveal how the immune system responds normally to protect. After reformulating them, the postulates of Credo 2004 are analysed with respect to their generality.
Metabolic engineering of proanthocyanidins by ectopic expression of transcription factors in Arabidopsis thaliana
Authors: Sharma Shashi B. , Dixon Richard A. 
Published: September 2005

SummaryGenetic transformation of Arabidopsis thaliana with the Arabidopsis TT2 MYB transcription factor resulted in ectopic expression of the BANYULS gene, encoding anthocyanidin reductase, AHA10 encoding a P‐type proton‐pump and TT12 encoding a transporter involved in proanthocyanidin biosynthesis. When coupled with constitutive expression of PAP1, a positive regulator of anthocyanin biosynthesis, TT2 expression in Arabidopsis led to accumulation of proanthocyanidins, but only in a subset of cells in which the BANYULS promoter is naturally expressed. Ectopic expression of the maize Lc MYC transcription factor weakly induced AHA10 but did not induce BANYULS, TT12 or accumulation of proanthocyanidins. However, high‐level combined expression of TT2, PAP1 and Lc resulted in proanthocyanidin synthesis throughout young leaves and cotyledons, followed by death of the plants 1 to 2 weeks after germination. We discuss these results in relation to engineering proanthocyanidins to improve the quality of food and forage plants.
Immediate‐early and delayed cytokinin response genes of Arabidopsis thaliana identified by genome‐wide expression profiling reveal novel cytokinin‐sensitive processes and suggest cytokinin action through transcriptional cascades
Authors: Brenner Wolfram G. , Romanov Georgy A. , Köllmer Ireen , Bürkle Lukas , Schmülling Thomas 
Published: September 2005

SummaryCytokinins are hormones that regulate many developmental and physiological processes in plants. Recent work has revealed that the cytokinin signal is transduced by two‐component systems to the nucleus where target genes are activated. Most of the rapid transcriptional responses are unknown. We measured immediate‐early and delayed cytokinin responses through genome‐wide expression profiling with the Affymetrix ATH1 full genome array (Affymetrix Inc., Santa Clara, CA, USA). Fifteen minutes after cytokinin treatment of 5‐day‐old Arabidopsis seedlings, 71 genes were upregulated and 11 genes were downregulated. Immediate‐early cytokinin response genes include a high portion of transcriptional regulators, among them six transcription factors that had previously not been linked to cytokinin. Five plastid transcripts were rapidly regulated as well, indicating a rapid transfer of the signal to plastids or direct perception of the cytokinin signal by plastids. After 2 h of cytokinin treatment genes coding for transcriptional regulators, signaling proteins, developmental and hormonal regulators, primary and secondary metabolism, energy generation and stress reactions were over‐represented. A significant number of the responding genes are known to regulate light (PHYA, PSK1, CIP8, PAT1, APRR), auxin (Aux/IAA), ethylene (ETR2, EIN3, ERFs/EREBPs), gibberellin (GAI, RGA1, GA20 oxidase), nitrate (NTR2, NIA) and sugar (STP1, SUS1) dependent processes, indicating intense crosstalk with environmental cues, other hormones and metabolites. Analysis of cytokinin‐deficient 35S:AtCKX1 transgenic seedlings has revealed additional, long‐lasting cytokinin‐sensitive changes of transcript abundance. Comparative overlay‐analysis with the software tool mapman identified previously unknown cytokinin‐sensitive metabolic genes, for example in the metabolism of trehalose‐6‐phosphate. Taken together, we present a genome‐wide view of changes in cytokinin‐responsive transcript abundance of genes that might be functionally relevant for the many biological processes that are governed by cytokinins.
The tobacco plastid accD gene is essential and is required for leaf development
Authors: Kode Vasumathi , Mudd Elisabeth A. , Iamtham Siriluck , Day Anil 
Published: September 2005

SummaryAngiosperm plastid genomes typically encode approximately 80 polypeptides, mainly specifying plastid‐localized functions such as photosynthesis and gene expression. Plastid protein synthesis and expression of the plastid clpP1 gene are essential for development in tobacco, indicating the presence of one or more plastid genes whose influence extends beyond the plastid compartment. The plastid accD gene encodes the β‐carboxyl transferase subunit of acetyl‐CoA carboxylase and is present in the plastids of most flowering plants, including non‐photosynthetic parasitic plants. We replaced the wild‐type accD gene with an aadA‐disrupted mutant allele using homologous recombination. Persistent heteroplasmy in the presence of antibiotics indicated that the wild‐type accD allele was essential. The phenotype of the accD knockout was revealed in plastid transformants grown in the absence of antibiotics. Leaves contained pale green sectors and lacked part or all of the leaf lamina due to arrested division or loss of cells. Abnormal structures were present in plastids found in mutant plants, indicating that accD might be required to maintain the plastid compartment. Loss of the plastid compartment would be expected to be lethal. These results provide genetic evidence showing the essential role of plastid ACCase in the pathway leading to the synthesis of products required for the extra‐plastidic processes needed for leaf development.
Oleate desaturase enzymes of soybean: evidence of regulation through differential stability and phosphorylation
Authors: Tang Guo‐Qing , Novitzky William P. , Carol Griffin H. , Huber Steven C. , Dewey Ralph E. 
Published: September 2005

SummaryThe endoplasmic reticulum‐associated oleate desaturase FAD2 (1‐acyl‐2‐oleoyl‐sn‐glycero‐3‐phosphocholine Δ12‐desaturase) is the key enzyme responsible for the production of linoleic acid in non‐photosynthetic tissues of plants. Little is known, however, concerning the post‐transcriptional mechanisms that regulate the activity of this important enzyme. The soybean genome possesses two seed‐specific isoforms of FAD2, designated FAD2‐1A and FAD2‐1B, which differ at only 24 amino acid residues. Expression studies in yeast revealed that the FAD2‐1A isoform is more unstable than FAD2‐1B, particularly when cultures were maintained at elevated growth temperatures. Analysis of chimeric FAD2‐1 constructs led to the identification of two domains that appear to be important in mediating the temperature‐dependent instability of the FAD2‐1A isoform. The enhanced degradation of FAD2‐1A at high growth temperatures was partially abrogated by treating the cultures with the 26S proteasome‐specific inhibitor MG132, and by expressing the FAD2‐1A cDNA in yeast strains devoid of certain ubiquitin‐conjugating activities, suggesting a role for ubiquitination and the 26S proteasome in protein turnover. In addition, phosphorylation state‐specific antipeptide antibodies demonstrated that the Serine‐185 of FAD2‐1 sequences is phosphorylated during soybean seed development. Expression studies of phosphopeptide mimic mutations in yeast suggest that phosphorylation may downregulate enzyme activity. Collectively, the results show that post‐translational regulatory mechanisms are likely to play an important role in modulating FAD2‐1 enzyme activities.
Use of genomic history to improve phylogeny and understanding of births and deaths in a gene family
Authors: Sampedro Javier , Lee Yi , Carey Robert E. , DePamphilis Claude , Cosgrove Daniel J. 
Published: September 2005

SummaryPolyploidy events have played an important role in the evolution of angiosperm genomes. Here, we demonstrate how genomic histories can increase phylogenetic resolution in a gene family, specifically the expansin superfamily of cell wall proteins. There are 36 expansins in Arabidopsis and 58 in rice. Traditional sequence‐based phylogenetic trees yield poor resolution below the family level. To improve upon these analyses, we searched for gene colinearity (microsynteny) between Arabidopsis and rice genomic segments containing expansin genes. Multiple rounds of genome duplication and extensive gene loss have obscured synteny. However, by simultaneously aligning groups of up to 10 potentially orthologous segments from the two species, we traced the history of 49 out of 63 expansin‐containing segments back to the ancestor of monocots and eudicots. Our results indicate that this ancestor had 15–17 expansin genes, each ancestral to an extant clade. Some clades have strikingly different growth patterns in the rice and Arabidopsis lineages, with more than half of all rice expansins arising from two ancestral genes. Segmental duplications, most of them part of polyploidy events, account for 12 out of 21 new expansin genes in Arabidopsis and 16 out of 44 in rice. Tandem duplications explain most of the rest. We were also able to estimate a minimum of 28 gene deaths in the Arabidopsis lineage and nine in rice. This analysis greatly clarifies expansin evolution since the last common ancestor of monocots and eudicots and the method should be broadly applicable to many other gene families.
Longterm survival of transplanted human corneal epithelial cells and corneal stem cells
Authors: Egarth Maria , Hellkvist Josefine , Claesson Margareta , Hanson Charles , Stenevi Ulf 
Published: September 2005

Abstract.Purpose:  To investigate the survival of donor‐derived epithelial cells in conventional penetrating keratoplasty (PKP) and in homologous penetrating central limbal keratoplasty (HPCLK). Methods and Patients:  Epithelial cells from 26 eyes of 26 patients were analysed. All cases were sex‐mismatched (i.e. the transplant and patient were of different genders). At suture removal more than 1 year post surgery, epithelial cells were obtained by gently wiping the removed sutures on glass slides. The cell samples were analysed using fluorescent in situ hybridization (FISH) of the sex chromosomes. This technique makes it possible to allocate the origin of each cell nucleus to either the donor or the recipient. Results:  All 19 conventional PKPs were clear and seven had donor‐derived epithelial cells at suture removal. Five of the seven HPCLK grafts were clear at the time of investigation (365–1355 days post surgery), and donor‐derived epithelial cells were found in two grafts. Conclusion:  Harvesting cells from removed sutures in combination with FISH enables the clinical study of cell survival in corneal transplants without jeopardizing functioning grafts. From the limited sample investigated, the following tentative conclusions can be made. Donor‐derived epithelial cells can remain in conventional PKP for over 1 year. In combined stem cell and corneal grafts (HPCLK), donor‐derived epithelial cells may also be retrieved at 1 year or beyond following surgery but the correlation between their presence and a remaining clear graft is uncertain.
The geographic mosaic in predispersal interactions and selection on Helleborus foetidus (Ranunculaceae)
Authors: Rey P. J. , Herrera C. M. , Guitián J. , Cerdá X. , Sánchez-lafuente A. M. , Medrano M. , Garrido J. L. 
Published: September 2005

Abstract
We examine the hierarchical geographic structure of the interaction between a plant, Helleborus foetidus, and its floral herbivores and pollinators (interactors). Six populations from three distant regions of the Iberian Peninsula were used to examine intra- and inter-regional variation in plant traits, interactors and plant fecundity, and to compare, through selection gradient and path analyses, which traits were under selection, and which interactors were responsible for differential selection. Geographic and temporal congruency in interactor-mediated selection was further tested using a recent analytical approach based on multi-group comparison in Structural Equation Models. Most plant traits, interactors and fecundity differed among regions but not between populations. Similarly, the identity of the traits under selection, the selection gradients (strength and/or the direction of the selection) and the path coefficients (identifying the ecological basis for selection) varied inter- but not intra-regionally. Results show a selection mosaic at the broad scale and, for some traits, a link of differential selection to trait differentiation.
Host ploidy, parasitism and immune defence in a coevolutionary snail–trematode system
Authors: Osnas E. E. , Lively C. M. 
Published: September 2005

Abstract
We studied the role of host ploidy and parasite exposure on immune defence allocation in a snail–trematode system (Potamopyrgus antipodarum-Microphallus sp.). In the field, haemocyte (the defence cell) concentration was lowest in deep-water habitats where infection is relatively low and highest in shallow-water habitats where infection is common. Because the frequency of asexual triploid snails is positively correlated with depth, we also experimentally studied the role of ploidy by exposing both diploid sexual and triploid asexual snails to Microphallus eggs. We found that triploid snails had lower haemocyte concentrations than did diploids in both parasite-addition and parasite-free treatments. We also found that both triploids and diploids increased their numbers of large granular haemocytes at similar rates after parasite exposure. Because triploid P. antipodarum have been shown to be more resistant to allopatric parasites than diploids, the current results suggest that the increased resistance of triploids is because of intrinsic genetic properties rather than to greater allocation to defence cells. This finding is consistent with recent theory on the advantages of increased ploidy for hosts combating coevolving parasites.
Analysis of Soil Fertility and Management Effects on Yields of Wheat and Corn in the Rolling Pampa of Argentina
Authors: Alvarez R. , Grigera S. 
Published: September 2005

AbstractThe Rolling Pampa is the most productive region of the Argentine Humid Pampa comprising around 10 Mha. Wheat (Triticum aestivum L.), corn (Zea mays L.), and soya bean [Glycine max (L.) Merr.] are the main grain crops produced. To develop sound cropping strategies, a better understanding of the impact of soil fertility and management on crops is needed. The objective of this study was to develop models for estimating the effects of growing season precipitation, soil fertility and management on wheat and corn yields. Data from 347 wheat and 323 corn field experiments and production fields over six growing seasons were used. Soil, management and weather characteristics were determined and yields were then evaluated. Data were analysed using linear and quadratic models and a quadratic polynomial surface model. Soil fertility, management and rainfall and interactions were analysed. Growing season precipitation correlated with wheat (R2 = 0.42) and corn (R2 = 0.25) yield. Maximum wheat yield was achieved with 350–400 mm rainfall and corn yield reached a plateau around 700 mm. Soil fertility accounted for 33 % of wheat yield variability and 5 % of corn yield variability. Management accounted for 48 and 9 % respectively. Whole polynomial models integrating rainfall, fertilizer N and P rates, soil N and P, previous crop and tillage system accounted for 67 % of wheat yield variability and 51 % of corn yield variability. Soil organic matter was not included in the models but an indirect effect on yield was detected as organic matter correlated with initial soil N levels for both crops. Soya bean as a previous crop had a positive effect on wheat and corn yields. Wheat was insensitive to tillage system but corn yield was higher under no till. N and P fertilization had a two‐ to three‐fold greater impact on yield than soil nutrient levels. As this region is considered to be of high soil fertility and has a history of very low fertilizer consumption, adequate use of N and P fertilization will be essential to maintaining high wheat and corn yields.