bluuebunny/crossref_metadata_2025_split huggingface dataset:
Does temperature limit the invasion of Impatiens glandulifera and Heracleum mantegazzianum in the UK?
Authors: Willis S. G. , Hulme P. E. 
Published: March 2003

Summary 1. Impatiens glandulifera Royle and Heracleum mantegazzianum Sommier et Levier are widespread, non‐indigenous plant species in the UK. A variety of correlational analyses suggest that their spatial extent is limited by climate, although no experimental studies have tested this hypothesis. This paper reports the first detailed experimental examination of the impact of climate on the performance of the two species. 2. Seeds of each species were sown, in each of 2 years, in replicated plots along an elevational gradient (10–600 m a.s.l.) in north‐east England. Both species germinated readily at all elevations, even in areas well above their current limits within the study area. The plants were, however, smaller at higher altitudes. Impatiens glandulifera also produced fewer seeds with increasing elevation. 3. Plant performance was assessed in relation to actual and interpolated climate data along the elevational transect. For H. mantegazzianum, the timing of germination was correlated most strongly with the pre‐emergence heat sum; for I. glandulifera this relationship was significant in one year only. Maximum height of both species was correlated with increasing post‐emergence heat sum, as was pod production by I. glandulifera. The biomass of second‐year H. mantegazzianum plants varied non‐linearly with post‐emergence heat sum. For both species, overwinter survival of seeds was not related to winter temperature or frost days. Overwinter survival of first‐year H. mantegazzianum plants declined with increasing frost incidence. 4. The results suggest that, of the two species, only I. glandulifera is currently most limited by temperature, although this is not the only factor determining the distribution of the species.
In situ water absorption by tree fine roots measured in real time using miniature sap‐flow gauges
Authors: Coners H. , Leuschner C. 
Published: March 2003

Summary

Root water uptake is a key process in the circulation of water in forest ecosystems. Until recently, water absorption by tree fine roots could not be measured in situ in undisturbed soil.
We present a new technique that allows continuous recording of the water absorption of fine root endings in mature stands without altering soil structure, hydrology or mycorrhizal infection.
The approach combines miniature sap‐flow gauges mounted on small‐diameter tree roots (3–4 mm) with a complete extraction and visual surface analysis of the adjacent absorbing fine root endings. This technique yields continuous data on water absorption per fine root surface area, and allows analysis of the spatial heterogeneity of root water uptake in the rhizosphere of forests.
We present the results of laboratory and field calibration experiments with Fagus sylvatica L. roots (3–4 mm), which show a good agreement between gauge flow data and synchronous gravimetric flow measurements for flows between 2 and >50 g h−1. Gauge readings were unreliable during low flows (<2 g h−1) at night. In these periods, which cover ≈10% of daily flow, we used an empirically derived linear relationship between root temperature difference and flow.
Measurements on F. sylvatica root endings during 10 summer days showed daily water absorption maxima ranging between 0·20 (rainy days) and 0·58 mmol m−2 root surface area s−1 (bright or overcast days). The corresponding daily maxima of leaf transpiration rate were ≈10 times higher (2–4 mmol m−2 leaf area s−1).
The combination of miniature sap‐flow gauges and determination of fine root surface area provides a promising tool for analysing water absorption by tree root systems in situ.
Predicted and observed maximum prey size – snake size allometry
Authors: King R. B. 
Published: March 2003

Summary

For gape‐limited predators such as snakes, it should be possible to predict the relationship between maximum prey size and body size from the relationship between maximum prey size and gape size and between gape size and body size. Such predictions were generated for Water Snakes, Nerodia sipedon L., using a data subset and then tested with a larger data set.
Gape size was computed based on jaw length and width and cyclical regression was used to identify prey of maximum size for snakes of a given gape or mass.
Predicted and observed maximum prey cross‐section–snake mass allometry were in good agreement. Predicted maximum prey mass–snake mass allometry somewhat exceeded observed allometry which did not differ from 1.
Observed minimum prey size–snake size allometry was significantly greater than 0, indicating that larger snakes drop small prey from their diets.
Gape size–body size allometry in two other natricine snakes (Thamnophis sirtalis, Storeria dekayi) suggest that patterns of ontogenetic change in prey size should differ among species in predictable ways.
Sex differences in gape size–snake size allometry suggest that sex differences in maximum prey size should increase with increasing snake size, even when linear measures of head dimensions do not.
Senescence and food limitation in a slowly ageing spider
Authors: Moya‐Laraño J. 
Published: March 2003

Summary

Evidence for reproductive senescence in invertebrate natural populations is scant probably because most groups are short‐lived or because they lack natural markers of age.
Lycosa tarantula (L.) (the Mediterranean Tarantula) (Araneae, Lycosidae) is a slowly ageing burrowing wolf spider, in which females can reproduce for two consecutive seasons. Females in their first reproductive season (1Y) can easily be distinguished from females in their second reproductive season (2Y) because the lack of pilosity in the latter.
The diet of 1Y and 2Y females was supplemented and their reproductive performance was compared with that of control, non‐food supplemented females. The predictions were that senescent 2Y females would show a worse reproductive performance than 1Y females, and that they would not be able to improve their performance relative to 1Y after food supplementation.
The predictions were met. Older females gained less mass, laid smaller egg sacs, produced fewer spiderlings and, if food supplemented, invested a smaller fraction of their mass in egg sacs. Although 2Y females foraged less actively than younger females, 2Y did not improve their performance relative to 1Y following food supplementation. This pattern of changes provides evidence for reproductive senescence in a natural spider population.
Sendai virus C proteins are categorically nonessential gene products but silencing their expression severely impairs viral replication and pathogenesis
Authors: Kurotani Atsushi , Kiyotani Katsuhiro , Kato Atsushi , Shioda Tatsuo , Sakai Yuko , Mizumoto Kiyohisa , Yoshida Tetsuya , Nagai Yoshiyuki 
Published: March 2003

Background:The P/C mRNA of Sendai virus (SeV), a prototypic member of the family Paramyxoviridae in the Mononegavirales superfamily comprising a large number of nonsegmented negative strand RNA viruses, encodes a nested set of accessory proteins, C′, C, Y1 and Y2, referred to collectively as C proteins, initiating, respectively, at ACG/81 and AUGs/114, 183, 201 in the +1 frame relative to the ORF of phospho (P) protein, the smaller subunit of RNA polymerase. Among them, C is the major species expressed in infected cells at a molar ratio which is several‐fold higher than the other three. However, their function has remained an enigma. It has not even been established whether or not the C proteins are essential for viral replication. Many other viruses in Mononegavirales encode C‐like proteins, but their roles also remain to be defined.Results:By taking advantage of a recently developed reverse genetics system to recover infectious SeV from cDNA, we created mutants in which C protein frames were variously silenced. C/C′(−) viruses which did not express C and C′, but did express Y1 and Y2, were severely attenuated in replication in tissue culture cells of various species and tissues, as well as in embryonated chicken eggs. More notably, they were almost totally incapable of growing productively in—and hence nonpathogenic for mice—the natural host. Both gene expression and genome replication appeared to be impaired in C/C′(−) viruses. Additionally silencing the Y1 and Y2 expression was also possible, and a critically impaired but viable clone, the 4C(−) virus, was isolated which expressed none of the four C proteins.Conclusion:SeV C proteins are categorically nonessential gene products, but greatly contribute to full replication capability in vitro and are indispensable for in vivo multiplication and pathogenesis. This study represents the first comprehensive functional assessment of the accessary C protein for Mononegavirales.
The mediator for stringent control, ppGpp, binds to the β‐subunit of Escherichia coli RNA polymerase
Authors: Chatterji Dipankar , Fujita Nobuyuki , Ishihama Akira 
Published: March 2003

BackgroundInhibition of transcription of rRNA in Escherichia coli upon amino acid starvation is thought to be due to the binding of ppGpp to RNA polymerase. However, the nature of this interaction still remains obscure.ResultsHere, the azido‐derivative of ppGpp was synthesized from azido‐GDP and [γ‐32P]ATP by way of the phosphate transfer reaction of the RelA enzyme. The product was subsequently characterized by one and two‐dimensional chromatography. The resulting compound [32P]azido‐ppGpp, where the azido group is attached to the base moiety, was purified to homogeneity and was photo‐crosslinked to Escherichia coli RNA polymerase. SDS‐PAGE analysis of the azido‐ppGpp‐bound enzyme, tryptic digestion and Western blot analysis suggested that azido‐ppGpp binds to the β‐subunit of RNA polymerase.ConclusionIt was observed that both the N‐terminal and C‐terminal domains of the β‐subunit were labelled with azido‐ppGpp in the native enzyme. However, under denaturing conditions only the C‐terminal part from amino acid residue 802 to residue 1211/1216/1223 was predominantly crosslinked to azido‐ppGpp. The excess of unlabelled ppGpp competes with azido‐ppGpp for binding to the enzyme. azido‐ppGpp inhibits single‐round transcription at the stringent promoter like rrnBP1. In addition, ribosomal protein genes were also found to be inhibited by N3ppGpp. On the other hand, transcription at the lac UV5 promoter remained unaffected upon the addition of azido‐ppGpp.
Synergistic regulation of inducible nitric oxide synthase gene by CCAAT/enhancer‐binding protein β and nuclear factor‐κB in hepatocytes
Authors: Sakitani Kazushige , Nishizawa Mikio , Inoue Kyoichi , Masu Yasuo , Okumura Tadayoshi , Ito Seiji 
Published: March 2003

BackgroundNitric oxide (NO) has diverse activities under physiological and pathophysiological conditions in many types of cells. In cultured hepatocytes, NO is produced by inducible NO synthase (iNOS) in response to interleukin (IL)‐1β. Cis‐controlling elements and transcription factors which were involved in iNOS gene expression in hepatocytes have been unclear.ResultsWe measured the transcriptional activity of the human iNOS gene promoter fused to the firefly luciferase gene in primary cultured rat hepatocytes. The luciferase assay of 5′ deleted promoters revealed that the region from −365 to the transcription initiation site is required for the promoter activity of the iNOS gene. Mutations of a CCAAT/enhancer‐binding protein (C/EBP)‐binding site, namely the A‐activator‐binding site (AABS), and a nuclear factor (NF)‐κB‐binding site within this region, markedly decreased the promoter activity. Transfection of C/EBPβ liver‐enriched activator protein (LAP) or NF‐κB (RelA + p50) activated the iNOS promoter, and transfection of LAP and NF‐κB further activated it synergistically. In addition, either mutation of AABS and the NF‐κB‐binding site markedly reduced the basal promoter activity and the transactivation by LAP, NF‐κB, and a combination of LAP and NF‐κB. Electrophoretic mobility shift assays showed that C/EBPβ was bound to AABS.ConclusionThese results demonstrate that C/EBPβ may involve iNOS gene expression synergistically with NF‐κB in primary cultured rat hepatocytes.
A core region of the mafK gene IN promoter directs neurone‐specific transcription in vivo
Authors: Motohashi Hozumi , Ohta Jun , Douglas Engel James , Yamamoto Masayuki 
Published: March 2003

Background:MafK serves as a required subunit of erythroid transcription factor NF‐E2 and also functions with various heterodimeric CNC family proteins. MafK expression begins in early mesoderm and is observed in mesenchymal and haematopoietic cells, as well as in neurones during mouse development. In mesodermal descendants, MafK mRNA begins with a distal first exon (called IM), whereas the mRNA in neurones begins with a proximal first exon (IN).Results:To elucidate the mechanisms that underlie the tissue‐specific transcription of the mafK gene, and to gain insights into the functions of MafK during neural development, we analysed the activity of the mafK IN promoter. A detailed investigation of mafK expression in the embryonic spinal cord revealed that IN‐initiated mRNA is expressed in the ventral side of the spinal cord. Transient transfection analysis of reporter plasmids bearing the IN promoter and upstream regions revealed that the ‘core’ region of this promoter (nt −67 to −9) is active and that its integrity is crucial for this activity. The core region was also capable of directing the tissue‐specific transcription of a reporter gene in neural cells of the spinal cord in transgenic mice in vivo.Conclusion:These results demonstrate that the specific expression of mafK in neural cells is determined, at least in part, by the core region of the IN promoter.
Cloning and characterization of two neural‐salient serine/arginine‐rich (NSSR) proteins involved in the regulation of alternative splicing in neurones
Authors: Komatsu Masaaki , Kominami Eiki , Arahata Kiichi , Tsukahara Toshifumi 
Published: March 2003

BackgroundIn neurones, alternative splicing regulates the functions of many gene products. However, the molecular basis of neural‐specific splicing, and how splicing regulation is modulated in different neurones remains to be determined.ResultsWe cloned two new SR proteins, Neural‐salient SR proteins (NSSR) 1 and 2, which are present at higher levels in brain and testis. During the differentiation, NSSR 1 is detected only in the neuronal stage. Both the purified recombinant NSSR 1 and 2 proteins enhance the in vitro splicing activity of nuclear extract. Moreover, recombinant NSSR 1 protein enhances the assembly of ribonucleoprotein complexes with S100 fraction. Over‐expression of NSSR 2 prevents the inclusion of either the Flip or Flop exons in the splicing of the GluR‐B gene, resulting in an increase in the abnormal exon‐skipping product. In contrast, transient transfection with NSSR 1 promotes the inclusion of the Flip exon so that the abnormal product is spliced to the mature spliced form. This suppression of exon skipping by NSSR 1 is observed even with co‐transfection of NSSR 2.ConclusionsNSSR 1 and 2 were cloned from mouse cDNA libraries. Results indicate that NSSR 1 may play a crucial role in the regulation of alternative splicing in neurones.
Molecular mechanism of a cross‐talk between oestrogen and growth factor signalling pathways
Authors: Kato Shigeaki , Masuhiro Yoshikazu , Watanabe Michiko , Kobayashi Yoko , Takeyama Ken‐ichi , Endoh Hideki , Yanagisawa Junn 
Published: March 2003

Oestrogen (E2) plays significant roles in variety of biological events such as the development and maintenance of female reproductive organs, bone and lipid metabolisms. More recently, from study of knock‐out mice deficient in oestrogen receptor (ER) α and ERβ it turned out that normal spermatogenesis requires the E2 actions. Furthermore, this female steroid hormone is also well known to be deeply involved in many pathophysiological events such as osteoporosis and cancer development in female reproductive organs. It is particularly well known that most breast cancer is dependent on E2 in its development. Such E2 actions are thought to be mediated through two subtypes of ERs. Growth factors have been shown to synergize in this E2 signalling pathway, although the actual molecular mechanism largely remains unknown.Recently, we found that the MAP kinase activated by growth factors phosphorylates the Ser118 residue of the human ERα A/B domain and this phosphorylation potentiates the N‐terminal transactivation function (AF‐1) of human ERα, indicating the possible molecular mechanism of a novel cross‐talk between E2 and growth factor signalling pathways. More recently, we have identified a coactivator associating with the hERα AF‐1 in a MAPK‐mediated phosphorylation‐dependent manner. In this review, the molecular mechanism of this cross‐talk is discussed in terms of the transactivation function of ERs, and their coactivators.
The colorectal tumour suppressor APC is present in the NMDA‐receptor‐PSD‐95 complex in the brain
Authors: Yanai Hiroyuki , Satoh Kiyotoshi , Matsumine Akihiko , Akiyama Tetsu 
Published: March 2003

BackgroundThe synaptic protein PSD‐95/SAP90 interacts with ion channels such as the N‐methyl‐ D‐aspartate‐receptor (NMDA‐R) via its PDZ domain, and is involved in their clustering. Moreover, it interacts with signalling molecules and plays an important role in coupling NMDA‐R to pathways that control synaptic plasticity and learning.ResultsWe report that PSD‐95 interacts with the adenomatous polyposis coli (APC) tumour suppressor protein via its PDZ domain. Furthermore, we found that PSD‐95, NMDA‐R and APC are contained in the same complex in vivo. PSD‐95‐NMDA‐R–APC association was found to require two cysteine residues conserved in the amino‐terminus of PSD‐95 that are known to be critical for its multimerization.ConclusionOur findings suggest that the PSD‐95‐NMDA‐R‐APC complex forms due to the multimerization of PSD‐95 monomers, each of which can associate with either NMDA‐R or APC. It is possible that APC is involved in the regulation of ion channel clustering and/or organization of signalling molecules.
Localized phosphorylation of vimentin by Rho‐kinase in neuroblastoma N2a cells
Authors: Nakamura Yu , Hashimoto Ryota , Amano Mutsuki , Nagata Koh‐ichi , Matsumoto Naohiko , Goto Hidemasa , Fukusho Eriko , Mori Hiroshi , Kashiwagi Yujiro , Kudo Takashi , Inagaki Masaki , Takeda Masatoshi 
Published: March 2003

BackgroundVimentin, which is one of the intermediate filaments, is the major cytoskeletal component in developing neurones or neuroblastoma cells. Rho‐associated kinase (Rho‐kinase), is rich in neurones and is found downstream of Rho. It is involved in the agonist‐induced neurite retraction of neuronal cells, and phosphorylates vimentin at Ser‐38 and Ser‐71 resulting in in vitro disassembly of the filaments.ResultsWe have investigated the distribution of vimentin phosphorylated by Rho‐kinase in N2a neuroblastoma cells using site‐specific phosphorylation‐dependent antibodies. TM71 immunoreactivity, which specifically indicates Ser‐71 phosphorylation on vimentin, was found in some neurites of dibutyryl cAMP‐differentiated N2a cells. Transfection of the constitutively active form of Rho‐kinase, CAT, significantly elevated TM71 immunoreactivity, and induced neurite retraction or cell rounding. Conversely, transfection of the dominant negative form of Rho‐kinase, RB/PH(TT), or treatment of 10 μM Y‐27632, a Rho‐kinase specific inhibitor, abolished TM71 immuno‐reactivity, and induced irregular neurite outgrowth. In contrast, 20 n
M okadaic acid (OA) induced neurite retraction and specifically elevated TM71 immunoreactivity. In the OA‐induced neurite retraction, tubulin disappeared in retracting neurites, where vimentin and actin remained co‐localized. Furthermore, the OA‐induced elevation of TM71 immunoreactivity and neurite retraction were completely blocked by pretreatment with 10 μM Y‐27632, or by the ectopic expression of RB/PH(TT).ConclusionsThis study suggests that the localized phosphorylation of vimentin by Rho‐kinase in neurites was closely related with the cellular morphology of N2a cells, and that the Rho‐kinase activity towards vimentin was balanced with OA‐sensitive phosphatases.
MSI‐1, a neural RNA‐binding protein, is involved in male mating behaviour in Caenorhabditis elegans
Authors: Yoda Akinori , Sawa Hitoshi , Okano Hideyuki 
Published: March 2003

Neural RNA‐binding proteins are thought to play important roles in neural development and the functional regulation of postmitotic neurones by mediating post‐transcriptional gene regulation. RNA‐binding proteins belonging to the Musashi family are highly expressed in the nervous system; however, their roles are poorly understood.We identified a Caenorhabditis elegans Musashi homologue, MSI‐1, whose RNA‐recognition motifs show extensive similarity to those of Drosophila and vertebrate Musashi proteins. We isolated a msi‐1 mutant and found males with this mutation to have a mating defect. C. elegans male mating behaviour includes a distinct series of steps: response to contact, backing, turning, vulva location, spicule insertion, and sperm transfer. msi‐1 is required for the turning and vulva location steps. Like other Musashi family members, MSI‐1 is expressed specifically in neural cells, including male‐specific neurones required for turning and vulva location. However, msi‐1 was not expressed in proliferating neural progenitors in C. elegans, unlike the Musashi family genes in other systems.Our results suggest that msi‐1 is expressed specifically in postmitotic neurones in C. elegans. msi‐1 is required for full development of male mating behaviour, possibly through regulation of msi‐1 expressing neurones.
Allele‐specific detection of nascent transcripts by fluorescence in situ hybridization reveals temporal and culture‐induced changes in Igf2 imprinting during pre‐implantation mouse development
Authors: Ohno Mizuki , Aoki Nao , Sasaki Hiroyuki 
Published: March 2003

BackgroundGenomic imprinting causes parental‐origin‐specific monoallelic transcription of a subset of mammalian genes in the embryo and adult. There is conflicting evidence, however, for the monoallelic transcription of some imprinted genes, such as Igf2, in pre‐implantation embryos.ResultsWe have developed an allele‐specific fluorescence in situ hybridization method which involves a pair of oligonucleotide probes designed to detect an intronic polymorphism. The method, called ASO‐RNA‐FISH, enabled us to distinguish allelic nascent Igf2 transcripts in the cell nuclei of early mouse embryos, avoiding signals from the stored oocyte‐specific transcripts. Igf2 transcription was first detectable in two‐cell embryos, and biallelic transcription was predominant up to the morula stage. Then, the maternal allele became silenced during the blastocyst stage. When embryos were cultured in vitro, however, a strong bias to maternal transcription was observed up to the morula stage.ConclusionASO‐RNA‐FISH revealed that a transition of Igf2 from biallelic to monoallelic transcription occurs in the blastocyst stage. This developmental regulation was modified temporarily by in vitro culture, suggesting a possible link between altered imprinting and abnormalities of the foetuses experienced in vitro culture. ASO‐RNA‐FISH is therefore a powerful technique for the study of allele‐specific gene expression.