bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modelling the discrimination of 13CO2 above and within a temperate broad‐leaved forest canopy on hourly to seasonal time scales
Authors: BALDOCCHI D. D. , BOWLING D. R. 
Published: March 2003

ABSTRACTFluxes and concentrations of carbon dioxide and 13CO2 provide information about ecosystem physiological processes and their response to environmental variation. The biophysical model, CANOAK, was adapted to compute concentration profiles and fluxes of 13CO2 within and above a temperate deciduous forest (Walker Branch Watershed, Tennessee, USA). Modifications to the model are described and the ability of the new model (CANISOTOPE) to simulate concentration profiles of 13CO2, its flux density across the canopy–atmosphere interface and leaf‐level photosynthetic discrimination against 13CO2 is demonstrated by comparison with field measurements. The model was used to investigate several aspects of carbon isotope exchange between a forest ecosystem and the atmosphere. During the 1998 growing season, the mean photosynthetic discrimination against 13CO2, by the deciduous forest canopy (Δcanopy), was computed to be 22·4‰, but it varied between 18 and 27‰. On a diurnal basis, the greatest discrimination occurred during the early morning and late afternoon. On a seasonal time scale, the greatest diurnal range in Δcanopy occurred early and late in the growing season. Diurnal and seasonal variations in Δcanopy resulted from a strong dependence of Δcanopy on photosynthetically active radiation and vapour pressure deficit of air. Model calculations also revealed that the relationship between canopy‐scale water use efficiency (CO2 assimilation/transpiration) and Δcanopy was positive due to complex feedbacks among fluxes, leaf temperature and vapour pressure deficit, a finding that is counter to what is predicted for leaves exposed to well‐mixed environments.
CD40L‐Induced IL‐12 Production is Further Enhanced by the Th2 Cytokines IL‐4 and IL‐13
Authors: Bullens D. M. A. , Kasran A. , Thielemans K. , Bakkus M. , Ceuppens J. L. 
Published: March 2003

Interaction of the CD40L (CD154) molecule on activated T cells with its receptor, CD40, on macrophages and dendritic cells (DC) provides a strong signal for interleukin (IL)‐12 production. As IL‐12 is the most important factor in driving Th precursor (Thp) cells into T(h)elper 1 cells, CD40–CD40L interactions strongly promote Th1 differentiation. Th2 cytokines (IL‐4, IL‐13, IL‐10) on the other hand, are known to inhibit Th1 differentiation, and to promote either directly or indirectly, Th2 differentiation. Inhibition of lipopolysaccharide (LPS)‐induced IL‐12 production by IL‐4, IL‐13 and IL‐10 is supposed to be one such mechanism. However, we here report that IL‐4 and IL‐13 enhance p70 IL‐12 production and p40 mRNA transcription by human monocytes when the latter are stimulated trough triggering of CD40. This effect on IL‐12 induction is most clear in the presence of interferon (IFN)‐γ, which upregulates CD40 expression. IL‐10 potently inhibits IL‐12 production. The increased IL‐12 production in the presence of IL‐4 and IL‐13 is however, not the indirect result of a reduction in IL‐10 production, but is most likely owing to a direct effect of IL‐4 and IL‐13. We conclude that IL‐4 and IL‐13 enhance rather than decrease the IL‐12 production by human monocytes during interaction with T cells. This effect can potentially contribute in vivo to switching of an ongoing Th2 response towards a Th1 response and the findings also support the dominant effect of CD40/CD40L interaction on Th1 development, even in the presence of Th2 cytokines.
Massive dolomitization of a late Miocene carbonate platform: a case of mixed evaporative brines with meteoric water, Nijar, Spain
Authors: Lu Feng H. , Meyers William J. 
Published: March 2003

Late Miocene platform carbonates from Nijar, Spain, have been extensively dolomitized. Limestones are present in the most landward parts of the platform, in stratigraphically lower units and topographically highest outcrops, suggesting that dolomitizing fluids were derived from the adjacent Nijar Basin. The dolomite crystals range from <10 to ≈100 μm existing as both replacements and cements. Na, Cl and SO4 concentrations in the dolomites range from 200 to 1700 p.p.m., 250–650 p.p.m., and 600–7000 p.p.m., respectively, comparable with other Tertiary and modern brine dolomite values, and also overlapping values from mixing‐zone dolomites. Sr concentrations range between 50 and 300 p.p.m., and the molar Sr/Ca ratios of dolomitizing fluids are estimated to range between 7× seawater brine to freshwater ratios. The δ18O and δ13C of the dolomites range from −1·0 to +4·2‰ PDB, and −4·0 to +2·0‰ PDB, respectively. 87Sr/86Sr values (0·70899–0·70928) of the dolomites range from late Miocene seawater to values greater than modern seawater.Mixtures of freshwater with seawater and evaporative brines probably precipitated the Nijar dolomites. Modelled covariations of molar Sr/Ca vs. δ18O and Na/Ca vs. δ18O from these mixtures are consistent with those of the proposed Nijar dolomitizing fluids. Complete or partial dolomite recrystallization is ruled out by well preserved CL zoning, nonstoichiometry and quantitative water–rock interaction modelling of covariations of Na vs. Sr and δ18O vs. δ13C. The possibility of multiple dolomitization events induced by evaporative brines, seawater and freshwater, respectively, is consistent with mineral‐mineral mixing modelling.The basin‐derived dolomitizing brines probably mixed with freshwater in the Nijar Basin or mixed with fresh groundwater in the platform, and were genetically related either to deposition of the Yesares gypsum or the Feos gypsum. Dolomitization occurred during either the middle Messinian or the early upper Messinian. Nijar dolomitization models may be applicable to dolomitization of other late Miocene platform carbonates of the western Mediterranean. Moreover, the Nijar models may offer an analogue for more ancient evaporite‐absent platform carbonates fringing evaporite basins.
Morphological phylogenetics of Australian gall‐inducing thrips and their allies: the evolution of host‐plant affiliations, domicile use and social behaviour
Authors: Morris David C. , Mound Laurence A. , Schwarz Michael P. , Crespi Bernard J. 
Published: March 2003

SummaryA phylogeny for seventy‐two species of Australian thrips in the subfamily Phlaeothripinae, based on cladistic analysis of forty morphological adult characters, is presented. We use this phylogeny to infer the evolutionary history of host‐plant affiliations, gall induction and other types of domicile use, and different forms of social behaviour. Maximum parsimony analysis yielded forty‐eight cladograms of length 316, and the strict consensus of these cladograms was well resolved. This phylogeny indicated that: (1) associations of thrips with their host plants tend to be evolutionarily conservative, with monophyletic groups of thrips on the host‐plant generaAcacia,CasuarinaandGeijera, (2) galling has evolved multiple times, on different host plants, (3) transitions in domicile use include changes between galling and living in holes or old galls, between living in glued phyllodes and living in old galls, and between leaf‐feeding and galling, and (4) in three of five cases, inquiline lineages were not closely related to their host lineages and the evolution of inquilinism apparently involved a host‐plant shift. However, in two cases, inquilines were very closely related to their gall‐inducing hosts. Eusocial behaviour (involving soldier castes) has evolved in different lineages from those that exhibit communal behaviour (cooperation in building or defending domiciles), suggesting a lack of direct transition between the two social systems. This phylogeny serves as a framework for future molecular systematic studies, and future comparative analysis of ecology and behaviour in the Phlaeothripinae.
Revision of European species of genus Metaphycus Mercet (Hymenoptera: Chalcidoidea: Encyrtidae), parasitoids of scale insects (Homoptera: Coccoidea)
Authors: Guerrieri Emilio , Noyes John S. 
Published: March 2003

SummaryFifty‐three European species of Metaphycus are revised. Three generic synonymies are proposed, nine species are described as new, sixteen new specific synonymies and four new combinations are proposed and lectotypes are designated for three species (lounsburyi, philippiae, timberlakei). A dichotomous key to the species is provided, each species is further characterized by a description and notes are provided on their distribution and known hosts. A host‐parasitoid index for all known European species is provided as an appendix.
Polyphyly of Lordiphosa and its relationships in Drosophilinae (Diptera: Drosophilidae)
Authors: Hu Yao‐Guang , Toda Masanori J. 
Published: March 2003

SummaryThe phylogenetic relationships of Lordiphosa and some taxa in Drosophilinae were analysed on the basis of a total of forty‐one selected drosophilid species. These included eighteen species of five Lordiphosa species‐groups as the main target, twenty‐three species representative of the major drosophiline ingroup taxa and four species of Steganinae as outgroup. Sixty‐eight morphological characters of adults were subjected to cladistic analysis. From the results it is concluded that Lordiphosa is polyphyletic; the Lo. tenuicauda species‐group and genus Nesiodrosophila form a single monophyletic group; Lordiphosa proper (i.e. Lordiphosa spp. minus the tenuicauda group) comprises another monophyletic group; within Lordiphosa proper the fenestrarum, nigricolor and denticeps groups are all monophyletic, but monophyly of the miki group is not strongly supported; genera Hirtodrosophila and Scaptomyza and subgenus Sophophora are all monophyletic; and within Drosophilinae, genus Scaptodrosophila is the first to have split from the main lineage, but the branching order of other clades, Chymomyza, Lordiphosa proper, Sophophora, Hirtodrosophila, Nesiodrosophila+ Lo. tenuicauda group, Scaptomyza, Dorsilopha and subgenus Drosophila, remains unresolved. The topology of maximum parsimony cladograms suggests that Lordiphosa proper lies close to Sophophora as proposed previously, although its phylogenetic position could not be determined conclusively. By contrast, bootstrap values tended to contradict another hypothesis that Lordiphosa and Scaptomyza are sister groups.
Molecular characterization of cDNA encoding for adenylate kinase of rice (Oryza sativa L.)
Authors: Kawai Maki , Kidou Shin‐ichiro , Kato Atsushi , Uchimiya Hirofumi 
Published: March 2003

SummaryTwo types of genes (Adk‐a, and Adk‐b) encoding for adenylate kinase (AK, EC 2.7.4.3.) were isolated from the cDNA library constructed from poly(A)+ RNA of rice (Oryza sativa L.). Two cDNAs were heterogeneous at 5′ and 3′ ends of non‐coding sequences and had possible polyadenylation signals. One of the genes, Adk‐a, had 1154 bp sequences encoding 241 amino acid residues, while the other type, Adk‐b, contained 1085 bp sequences encoding for 243 amino acid residues. Homology between Adk‐a and Adk‐b was 73.7% in nucleotide sequences, and 90.8% in amino acid level. Two genes showed about 53% homology to bovine mitochondrial adenylate kinase (AK2) at nucleotide and amino acid levels. Concerning the codon usage of rice AK genes, T was abundant at the third position of a codon in the reading frames.In order to examine the enzyme activity of the protein encoded by the rice cDNA, Adk‐a was cloned into an expression vector, pUC119, which was introduced into Escherichia coli strain CV2, a temperaturesensitive mutant of adenylate kinase. We found that the transformant carrying the rice Adk‐a gene in the sense orientation recovered cell growth at nonpermissive high temperature (42°C) and expressed enzyme activities higher than the untransformed CV2 and the transformant possessing Adk‐a cDNA in the antisense orientation. These observations suggest that rice Adk‐a codes a biologically active enzyme. Furthermore, sucrose was found to regulate the transcription of AK genes in rice cell cultures. Organ related accumulation of mRNA in whole plants was also found.
Characterization of a pollen‐specific cDNA from sunflower encoding a zinc finger protein.
Authors: Baltz R , Domon C , Pillay DT , Steinmetz A 
Published: March 2003

SummaryWe have isolated, via differential hybridization screening of a floral cDNA library from sunflower, a cDNA clone that hybridizes to a 1100 nucleotide‐long mRNA found exclusively in mature pollen grains. The cDNA encodes a 219 amino acid‐long polypeptide containing two potential zinc fingers alternating with two basic domains. A similar organization is found in the erythroid‐specific transcription factor Eryf1 from chicken and its murine homolog GF‐1. The C‐terminus of the protein contains a sixfold repeat of the pentapeptide sequence (S,T,A)(E,D)TQN. These features suggest that the SF3 protein is a transcription factor required for the expression of late pollen genes. The SF3 gene is a member of a multicopy gene family. A genomic copy of the gene has been isolated and sequenced; it is split by four short, AT‐rich introns.
Expression of maize Adh1 intron mutants in tobacco nuclei
Authors: Lou Hua , McCullough Andrew J. , Schuler Mary A. 
Published: March 2003

SummaryIn vivo and in vitro gene transfer experiments have suggested that the elements mediating intron recognition differ in mammalian, yeast and plant nuclei. Differences in the sequence dependencies, which also exist between dicotyledonous and monocotyledonous nuclei, have prevented some monocot introns from being spliced in dicot nuclei. To locate elements which modulate efficient recognition of introns in dicot nuclei, the maize Adh1 gene has been expressed in full‐length and single intron constructs in Nicotiana benthamiana nuclei using an autonomously replicating plant expression vector. Quantitative PCR‐Southern analyses indicate that the inefficient splicing of the maize Adh1 intron 1 (57% AU) in these dicot nuclei can be dramatically enhanced by increasing the degree of U1 snRNA complementarity at the 5′ splice site. This indicates that the 5′ splice site plays a significant role in defining the splicing efficiency of an intron in dicot nuclei and that, most importantly, the remainder of this monocot intron contains no elements which inhibit its accurate recognition in dicot nuclei. Deletions in intron 3 (66% AU) which effectively move the 3′ boundary between AU‐rich intron and GC‐rich exon sequences strongly activate a cryptic upstream splice site; those which do not reposition this boundary activate a downstream cryptic splice site. This suggests that 3′ splice site selection in dicot nuclei is extremely flexible and not dependent on strict sequence requirements but rather on the transition points between introns and exons. Our results are consistent with a model in which potential splice sites are selected if they are located upstream (5′ splice site) or downstream (3′ splice site) of AU transition points and not if they are embedded within AU‐rich sequences.
A non‐specific lipid transfer protein from Arabidopsis is a cell wall protein
Authors: Thoma Sharon , Kaneko Yasuko , Somerville Chris 
Published: March 2003

SummaryLipid transfer proteins (LTPs), mediate the transfer of phospholipids between membranes in vitro. However, the in vivo function of LTPs is not known. To determine the precise location of a non‐specific LTP from Arabidopsis, a cDNA clone was used to produce an Arabidopsis LTP:protein A fusion. Antibodies raised against the fusion were used to localize the Arabidopsis LTP by immunoelectron microscopy. LTP was found to be located in the cell wall, mainly in epidermal cells. This location appears to be inconsistent with the proposed role of the protein in intracellular lipid transfer.
K+ channels of stomatal guard cells: bimodal control of the K+ inward‐rectifier evoked by auxin
Authors: Blatt Michael R. , Thiel Gerhard 
Published: March 2003

SummaryThe influence of the auxins indole‐3‐acetic acid (IAA) and 1‐napthylene acetic acid (NAA) on K+ channels and their control was examined in stomatal guard cells of Vicia faba L. Intact guard cells were impaled with multibarrelled microelectrodes to record membrane potentials and to monitor K+ channel currents under voltage clamp during exposures to 0.1–100 µM IAA and NAA. Following impalements, challenge with either IAA or NAA in the presence of 10 mM KCl resulted in the concerted modulation of at least four different currents with distinct kinetic characteristics and concentration dependencies. Equivalent concentrations of benzoic acid were wholly without effect. Most striking, current carried by inward‐rectifying K+ channels (IK,in) exhibited a bimodal response to both IAA and NAA which was reversed on washing the auxins from the bathing medium. The steady‐state current was augmented 1.3‐ to 2‐fold at concentrations between 0.1 and 10 µM and antagonized at concentrations near 30 µM and above. Auxin agonism of IK,in was time‐ and voltage‐independent. By contrast, IK,in inactivation at the higher auxin concentrations was marked by a voltage‐dependence and slowing of the kinetics for current activation. Inactivation of IK,in by the auxins was relieved when cytoplasmic pH (pHi) was clamped near 7.0 in the presence of 30 mM Na+‐butyrate. In addition to the control of IK,in, current carried by a second class of (outward‐rectifying) K+ channels rose in a monotonic and largely voltage‐independent manner with auxin concentrations about 10 µM and above, and IAA and NAA also activated an inward‐going current with a voltage dependence characteristic of guard cell anion channels. Further changes in background current were consistent with a limited activation of the H+‐ATPase. Over the concentration range examined, the auxins evoked membrane hyperpolarizations and depolarizations of up to ±12–19 mV, depending on the free‐running membrane potential prevailing before auxin additions. Prolonging exposures to 100 µM auxin beyond 3–5 min frequently elicited rapid transitions to voltages near EK as well as regenerative action potentials. However, in every case the voltage response was a predictable consequence of auxin action on the K+ channels and, at 100 µM auxin, on the anion current. These results demonstrate a control of K+ channel activity by auxin, consistent with the roles of these channels in mediating K+ flux for stomatal movements; the data associate a bimodal characteristic with the activity of IK,in, implicating pHi as a putative intermediate in its control, and offer strong evidence for a multiplicity of signal cascades evoked by auxin; finally, they highlight a coordinate modulation of transport activities by auxin, thereby drawing a close analogy to the pattern of stimulus‐response coupling in abscisic acid.
Developmental control of small heat shock protein expression during pea seed maturation
Authors: DeRocher Amy Elizabeth , Vierling Elizabeth 
Published: March 2003

SummaryPlants synthesize four classes of small heat shock proteins (sHSPs); two classes are targeted to the plastid and endoplasmic reticulum, respectively, and two are found in the cytoplasm. In this paper, we describe a new role for the two classes of cytoplasmic HSPs in maturing embryos of developing seeds. The expression of each class of sHSPs was examined in pea seeds grown under non‐stress conditions using Western and Northern analysis. Class I and class II cytoplasmic sHSPs are coordinately expressed in the embryo and accumulate to levels seen in moderately heat‐stressed leaves. Their induction in cotyledons coincides with the mid‐maturation phase of seed development, and induction in axes roughly coincides with abscission of the seed from the ovary wall. Both classes of sHSPs persisted in cotyledons for 4 days after the onset of imbibition, but disappeared from axes shortly after germination. Neither class of cytoplasmic sHSP is expressed in non‐embryonic organs associated with the seed. The timing and organ specificity of sHSP expression is paralleled by the expression of the corresponding mRNAs. Neither the plastid nor the endoplasmic reticulum sHSPs were consistently expressed during seed development, but both could be induced by heat‐stressing the developing seed. Developmental regulation of the cytoplasmic sHSPs is evidence that these proteins function not only in responding to heat‐stress but also during seed development and/or germination.
Association of a 76 kDa polypeptide with soluble starch synthase I activity in maize (cv B73) endosperm
Authors: Mu Chen , Harn Chee , Ko Yuan‐Tih , Singletary George W. , Keeling Peter L. , Wasserman Bruce P. 
Published: March 2003

SummarySoluble starch synthase (SSS) I was purified 361‐fold from hand‐dissected endosperm tissue of inbred maize (Zea mays, cv. B73) to specific activities ranging between 5 and 9 µmol min−1 mg−1. A key to this purification protocol was the introduction of a size‐exclusion chromatography step, a size‐based fractionation which provided abundant levels of desalted SSS forms I and II. The native molecular masses calculated for SSS forms I and II were 75.5 kDa and 180 kDa, respectively. SSSI was then further purified by hydrophobic interaction chromatography on Phenyl‐Superose and by FPLC on Mono Q. Analysis of column peaks by SDS—PAGE and scanning densitometry revealed that a 76 kDa polypeptide is strongly correlated with SSSI activity. Antibodies were then generated against a 76 kDa polypeptide extracted from starch granules. These antibodies, which were monospecific for the soluble 76 kDa polypeptide, neutralized greater than 90% of SSSI activity, and precipitated the 76 kDa protein. These results establish the 76 kDa protein as an SSSI in the B73 line of inbred maize. An immunologically similar 76 kDa protein also appears to be tightly associated with the starch granule.
Production of the Escherichia coli betaine‐aldehyde dehydrogenase, an enzyme required for the synthesis of the osmoprotectant glycine betaine, in transgenic plants
Authors: Holmström Kjell‐Ove , Welin Björn , Mandal Abul , Kristiansdottir Ingileif , Teeri Teemu H. , Lamark Trond , Strøm Arne R. , Palva E. Tapio 
Published: March 2003

SummaryIn several organisms osmotic stress tolerance is mediated by the accumulation of the osmoprotective compound glycine betaine. With the ambition to transfer the betaine biosynthetic pathway into plants not capable of synthesizing this osmoprotectant, the Escherichia coli gene betB encoding the second enzyme in the pathway, betaine‐aldehyde dehydrogenase was introduced into Nicotiana tabacum. The betB structural gene was fused to the promoter of ats1a, a gene coding for the small subunit of Rubisco in Arabidopsis thaliana. Two types of constructs were made, either encoding the N‐terminal transit peptide for chloroplast targeting or without the targeting signal for cytoplasmic localization of the BetB polypeptide. Analysis of transgenic N. tabacum plants harboring these constructs showed that in both cases the transgenes were expressed. Northern analysis of the plants demonstrated the accumulation of betB‐related mRNA of the correct size. The production and processing of the corresponding polypeptides could be demonstrated by immunoblotting using polyclonal antisera raised against the BetB polypeptide. The transit peptide encoded by ats1a was able to direct BetB to the chloroplast, as suggested by the presence of the correctly processed BetB polypeptide in the chloroplast fraction. High betaine‐aldehyde dehydrogenase activity was detected in transgenic plants, both in those where the chimeric gene product was targeted to the chloroplast and those where it remained in the cytoplasm. The transgenic tobacco acquired resistance to the toxic intermediate, betaine aldehyde, in the betaine biosynthetic pathway indicating that the bacterial enzyme is biologically active in its new host. Furthermore, these transgenic plants were able to convert exogenously supplied betaine aldehyde efficiently to glycine betaine.