bluuebunny/crossref_metadata_2025_split huggingface dataset:
Neuropeptide Y and Luteinizing Hormone Releasing Hormone Synergize to Stimulate the Development of Cellular Follicle‐Stimulating Hormone in the Hamster Adenohypophysis
Authors: Woller Michael J. , Campbell Gary T. , Blake Charles A. 
Published: September 2006

AbstractLuteinizing hormone releasing hormone (LHRH) stimulates the development of cellular FSH immunoreactivity in the perinatal hamster adenohypophysis. Because neuropeptide Y (NPY) can act directly on rat adenohypophysial cells to stimulate FSH and LH release and potentiate the stimulatory effect of LHRH on FSH and LH release, we investigated the effects of NPY alone and in combination with a low, ineffective dose of LHRH on inducing cellular FSH immunoreactivity in the neonatal hamster adenohypophysis. Neonatal female pituitary glands were grafted beneath the right renal capsules of hypophysectomized‐ovariectomized adult hamster hosts with a catheter implanted in the external jugular vein. After treatment, hosts were decapitated and graft tissue was stained for FSH and LH immunoreactivity. The mean percentage of adenohypophysial cells that stained for FSH was low (2.8%) in grafts in hosts infused continuously with heparinized saline vehicle for 7 days. In other hosts, peptides were pulsed through the catheter every 12 h for 7 days. The mean percentage of FSH cells also was low after pulsing 6 ng LHRH or 2 μg NPY but increased substantially when the two peptides were pulsed simultaneously. No differences in the mean percentage of LH cells existed between any of the groups. The results demonstrate that NPY and LHRH can synergize to induce cellular FSH immunoreactivity in the neonatal female hamster.
Bipolar localization of the group II intron Ll.LtrB is maintained in Escherichia coli deficient in nucleoid condensation, chromosome partitioning and DNA replication
Authors: Beauregard Arthur , Chalamcharla Venkata R. , Piazza Carol Lyn , Belfort Marlene , Coros Colin J. 
Published: September 2006

SummaryGroup II introns are mobile genetic elements that invade their cognate intron‐minus alleles via an RNA intermediate, in a process known as retrohoming. They can also retrotranspose to ectopic sites at low frequency. In Escherichia coli, retrotransposition of the lactococcal group II intron, Ll.LtrB, occurs preferentially within the Ori and Ter macrodomains of the E. coli chromosome. These macrodomains migrate towards the poles of the cell, where the intron‐encoded protein, LtrA, localizes. Here we investigate whether alteration of nucleoid condensation, chromosome partitioning and replication affect retrotransposition frequencies, as well as bipolar localization of the Ll.LtrB intron integration and LtrA distribution in E. coli. We thus examined these properties in the absence of the nucleoid‐associated proteins H‐NS, StpA and MukB, in variants of partitioning functions including the centromere‐like sequence migS and the actin homologue MreB, as well as in the replication mutants ΔoriC, seqA, tus and topoIV ts. Although there were some dramatic fluctuations in retrotransposition levels in these hosts, bipolar localization of integration events was maintained. LtrA was consistently found in nucleoid‐free regions, with its localization to the cellular poles being largely preserved in these hosts. Together, these results suggest that bipolar localization of group II intron retrotransposition results from the residence of the intron‐encoded protein at the poles of the cell.
Virulence of Agrobacterium tumefaciens requires phosphatidylcholine in the bacterial membrane
Authors: Wessel Mirja , Klüsener Sonja , Gödeke Julia , Fritz Christiane , Hacker Stephanie , Narberhaus Franz 
Published: September 2006

SummaryPhosphatidylcholine (PC, lecithin) has long been considered a solely eukaryotic membrane lipid. Only a minority of all bacteria is able to synthesize PC. The plant‐transforming bacterium Agrobacterium tumefaciens encodes two potential PC forming enzymes, a phospholipid N‐methyltransferase (PmtA) and a PC synthase (Pcs). We show that PC biosynthesis and tumour formation on Kalanchoë plants was impaired in the double mutant. The virulence defect was due to a complete lack of the type IV secretion machinery in the Agrobacterium PC mutant. Our results strongly suggest that PC in bacterial membranes is an important determinant for the establishment of host–microbe interactions.
Biochemical and genetic characterization of an early step in a novel pathway for the biosynthesis of aromatic amino acids and p‐aminobenzoic acid in the archaeon Methanococcus maripaludis
Authors: Porat Iris , Sieprawska‐Lupa Magdalena , Teng Quincy , Bohanon Fredrick J. , White Robert H. , Whitman William B. 
Published: September 2006

Summary Methanococcus maripaludis is a strictly anaerobic, methane‐producing archaeon and facultative autotroph capable of biosynthesizing all the amino acids and vitamins required for growth. In this work, the novel 6‐deoxy‐5‐ketofructose‐1‐phosphate (DKFP) pathway for the biosynthesis of aromatic amino acids (AroAAs) and p‐aminobenzoic acid (PABA) was demonstrated in M. maripaludis. Moreover, PABA was shown to be derived from an early intermediate in AroAA biosynthesis and not from chorismate. Following metabolic labelling with [U‐13C]‐acetate, the expected enrichments for phenylalanine and arylamine derived from PABA were observed. DKFP pathway activity was reduced following growth with aryl acids, an alternative source of the AroAAs. Lastly, a deletion mutant of aroA′, which encodes the first step in the DKFP pathway, required AroAAs and PABA for growth. Complementation of the mutants by an aroA′ expression vector restored the wild‐type phenotype. In contrast, a deletion of aroB′, which encodes the second step in the DKFP pathway, did not require AroAAs or PABA for growth. Presumably, methanococci contain an alternative activity for this step. These results identify the initial reactions of a new pathway for the biosynthesis of PABA in methanococci.
Experimental African trypanosomiasis: lack of effective CD1d‐restricted antigen presentation
Authors: SHI M. Q. , WANG C.‐R. , WEI G. J. , PAN W. L. , APPLEYARD G. , TABEL H. 
Published: September 2006

SUMMARY BALB/c mice are highly susceptible to African trypanosomiasis, whereas C57BL/6 mice are relatively resistant. Other investigators have reported that the synthesis of IgG antibodies to purified membrane form of variant surface glycoprotein (mfVSG) of Trypanosoma brucei is CD1 restricted. In this study, we examine the role of the CD1d/NKT cell pathway in susceptibility and resistance of mice to infection by African trypanosomes. Administration of anti‐CD1d antibodies to Trypanosoma congolense‐infected BALB/c mice neither affects the parasitemia nor the survival time. Correspondingly, CD1d–/– and CD1d+/+ BALB/c mice infected with T. congolense or T. brucei show no differences in either parasitaemia or survival time. The course of disease in relative resistant C57BL/6 mice infected with T. congolense is also not affected by the absence of CD1d. Parasitaemia, survival time, and plasma levels of IgG2a and IgG3 parasite‐specific antibodies in infected CD1d–/– C57BL/6 are not different from those of infected CD1d+/+ C57BL/6 mice. We conclude that CD1d‐restricted immune responses do not play an important role in susceptibility/resistance of mice infected with virulent African trypanosomes. We speculate that virulent trypanosomes have an evasion mechanism that prevents the induction of a parasite‐specific, CD1d‐restricted immune response by the host.
Mitochondria as a connected population: ensuring continuity of the mitochondrial genome during plant cell dedifferentiation through massive mitochondrial fusion
Authors: Sheahan Michael B. , McCurdy David W. , Rose Ray J. 
Published: September 2006

SummaryMitochondrial fusion in plants and its role in development are poorly understood. Cultured tobacco mesophyll protoplasts provide an excellent experimental system for visualizing mitochondrial dynamics. Before protoplasts first divide, mitochondria undergo a phase of extensive elongation before fission causes an increase in number, followed by actin filament (AF)‐dependent dispersion that distributes mitochondria uniformly throughout the cytoplasm. Here, by fusing protoplasts containing either green fluorescent protein‐ or MitoTracker‐labelled mitochondria, we show that elongation results from fusion during early (4–8 h) protoplast culture. This massive mitochondrial fusion (MMF) leads to near‐complete mixing of the mitochondrial population within 24 h. Staining isolated mitochondria with 4′,6‐diamidino‐2‐phenylindole (DAPI) revealed that in freshly prepared protoplasts mitochondrial nucleoids were unequally distributed, with many mitochondria failing to stain with DAPI, suggesting the presence of an incomplete mitochondrial genome. Following MMF, nucleoids were distributed evenly throughout the population, thereby ensuring continuity of the mitochondrial genome in daughter cells. Massive mitochondrial fusion appears to be specific to dedifferentiation, since it also occurs in mesophyll protoplasts of Arabidopsis and Medicago but not in protoplasts from already dedifferentiated cells such as BY‐2 or callus cultures. Efficient MMF requires an inner membrane electrical gradient, cytoplasmic protein synthesis, microtubules and functional kinesin but not ATP or AFs, indicating fundamental differences from mitochondrial fusion in non‐plant systems. Our studies reveal that individual mitochondria are connected over time by fusion events, a finding that allows a clearer interpretation of how novel mitochondrial genotypes develop following cell fusion, and indicates that developmentally regulated fusion ensures continuity of the mitochondrial genome.
The genetics and genomics of the drought response in Populus
Authors: Street Nathaniel Robert , Skogström Oskar , Sjödin Andreas , Tucker James , Rodríguez‐Acosta Maricela , Nilsson Peter , Jansson Stefan , Taylor Gail 
Published: September 2006

SummaryThe genetic nature of tree adaptation to drought stress was examined by utilizing variation in the drought response of a full‐sib second generation (F2) mapping population from a cross between Populus trichocarpa (93‐968) and P. deltoides Bart (ILL‐129) and known to be highly divergent for a vast range of phenotypic traits. We combined phenotyping, quantitative trait loci (QTL) analysis and microarray experiments to demonstrate that ‘genetical genomics’ can be used to provide information on adaptation at the species level. The grandparents and F2 population were subjected to soil drying, and contrasting responses to drought across genotypes, including leaf coloration, expansion and abscission, were observed, and QTL for these traits mapped. A subset of extreme genotypes exhibiting extreme sensitivity and insensitivity to drought on the basis of leaf abscission were defined, and microarray experiments conducted on these genotypes and the grandparent species. The extreme genotype groups induced a different set of genes: 215 and 125 genes differed in their expression response between groups in control and drought, respectively, suggesting species adaptation at the gene expression level. Co‐location of differentially expressed genes with drought‐specific and drought‐responsive QTLs was examined, and these may represent candidate genes contributing to the variation in drought response.
Regulation of hormone metabolism in Arabidopsis seeds: phytochrome regulation of abscisic acid metabolism and abscisic acid regulation of gibberellin metabolism
Authors: Seo Mitsunori , Hanada Atsushi , Kuwahara Ayuko , Endo Akira , Okamoto Masanori , Yamauchi Yukika , North Helen , Marion‐Poll Annie , Sun Tai‐ping , Koshiba Tomokazu , Kamiya Yuji , Yamaguchi Shinjiro , Nambara Eiji 
Published: September 2006

SummaryIn a wide range of plant species, seed germination is regulated antagonistically by two plant hormones, abscisic acid (ABA) and gibberellin (GA). In the present study, we have revealed that ABA metabolism (both biosynthesis and inactivation) was phytochrome‐regulated in an opposite fashion to GA metabolism during photoreversible seed germination in Arabidopsis. Endogenous ABA levels were decreased by irradiation with a red (R) light pulse in dark‐imbibed seeds pre‐treated with a far‐red (FR) light pulse, and the reduction in ABA levels in response to R light was inhibited in a phytochrome B (PHYB)‐deficient mutant. Expression of an ABA biosynthesis gene, AtNCED6, and the inactivation gene, CYP707A2, was regulated in a photoreversible manner, suggesting a key role for the genes in PHYB‐mediated regulation of ABA metabolism. Abscisic acid‐deficient mutants such as nced6‐1, aba2‐2 and aao3‐4 exhibited an enhanced ability to germinate relative to wild type when imbibed in the dark after irradiation with an FR light pulse. In addition, the ability to synthesize GA was improved in the aba2‐2 mutant compared with wild type during dark‐imbibition after an FR light pulse. Activation of GA biosynthesis in the aba2‐2 mutant was also observed during seed development. These data indicate that ABA is involved in the suppression of GA biosynthesis in both imbibed and developing seeds. Spatial expression patterns of the AtABA2 and AAO3 genes, responsible for last two steps of ABA biosynthesis, were distinct from that of the GA biosynthesis gene, AtGA3ox2, in both imbibed and developing seeds, suggesting that biosynthesis of ABA and GA in seeds occurs in different cell types.
PICKLE is required for SOLITARY‐ROOT/IAA14‐mediated repression of ARF7 and ARF19 activity during Arabidopsis lateral root initiation
Authors: Fukaki Hidehiro , Taniguchi Naohide , Tasaka Masao 
Published: September 2006

SummaryLateral root (LR) formation in Arabidopsis is regulated by auxin signaling through AUXIN RESPONSE FACTOR transcriptional activators, ARF7 and ARF19, and auxin/indole‐3‐acetic acid (Aux/IAA) repressors, including SOLITARY‐ROOT (SLR)/IAA14. Previous studies have strongly suggested that, in the gain‐of‐function slr‐1 mutant, stabilized mutant IAA14 (mIAA14) protein inactivates ARF7/19 functions, thereby completely blocking LR initiation. However, the mechanism of inactivation is still unknown. We have now identified an extragenic suppressor mutation of slr‐1, suppressor of slr2 (ssl2), which specifically restores LR formation in the slr‐1 mutant, and have found that SSL2 negatively regulates the auxin‐induced pericycle cell divisions required for LR initiation. The SSL2 gene encodes PICKLE (PKL), a homologue of the animal chromatin‐remodeling factor CHD3/Mi‐2, and LR formation restored in pkl/ssl2 slr‐1 mutants depends on ARF7/19 functions, suggesting that ARF7/19‐dependent transcription takes place if there is a pkl/ssl2 mutation in slr‐1. In animals, Mi‐2 represses transcription as a subunit of the NuRD/Mi‐2 complex containing histone deacetylases (HDACs). Inhibition of HDAC activity by trichostatin A also results in LR formation in the slr‐1 mutant, but not in the slr‐1 arf7 arf19 triple mutant, suggesting that normal HDAC activity is required for the mIAA14‐mediated inactivation of ARF7/19 functions in LR initiation. Taken together, our data suggest that PKL/SSL2‐mediated chromatin remodeling negatively regulates auxin‐mediated LR formation in Arabidopsis.
Identification of plant cytoskeleton‐interacting proteins by screening for actin stress fiber association in mammalian fibroblasts
Authors: Abu‐Abied Mohamad , Golomb Lior , Belausov Eduard , Huang Shanjin , Geiger Benjamin , Kam Zvi , Staiger Christopher J. , Sadot Einat 
Published: September 2006

SummaryTaking advantage of the high conservation of the cytoskeleton building blocks actin and tubulin between plant and animal kingdoms, we developed a functional genomic screen for the isolation of new plant cytoskeleton‐binding proteins that uses a mammalian cell expression system. A yellow fluorescent protein (YFP)‐fusion cDNA library from Arabidopsis was inserted into rat fibroblasts and screened for fluorescent chimeras localizing to cytoskeletal structures. The high‐throughput screen was performed by an automated microscope. An initial set of candidate genes identified in the screen was isolated, sequenced, the full‐length cDNAs were synthesized by RT‐PCR and tested by biochemical approaches to verify the ability of the genes to bind actin directly. Alternatively, indirect binding via interaction with other actin‐binding proteins was studied. The full‐length cDNAs were transferred back to plants as YFP chimeras behind the CAMV‐35S promoter. We give here two examples of new plant cytoskeletal proteins identified in the pilot screen. ERD10, a member of the dehydrin family of proteins, was localized to actin stress fibers in rat fibroblasts. Its direct binding to actin filaments was confirmed by several biochemical approaches. Touch‐induced calmodulin‐like protein, TCH2, was also localized to actin stress fibers in fibroblasts, but was unable to bind actin filaments directlyin vitro. Nevertheless, it did bind to the IQ domains of Arabidopsis myosin VIII in a calcium‐dependent manner. Further evidence for a cytoskeletal function of ERD10 was obtainedin planta; GFP‐ERD10 was able to protect the actin cytoskeleton from latrunculin‐mediated disruption inNicotiana benthamianaleaves.
Characterizing the composition and evolution of homoeologous genomes in hexaploid wheat through BAC‐end sequencing on chromosome 3B
Authors: Paux Etienne , Roger Delphine , Badaeva Ekatherina , Gay Georges , Bernard Michel , Sourdille Pierre , Feuillet Catherine 
Published: September 2006

SummaryBread wheat (Triticum aestivum) is one of the most important crops worldwide. However, because of its large, hexaploid, highly repetitive genome it is a challenge to develop efficient means for molecular analysis and genetic improvement in wheat. To better understand the composition and molecular evolution of the hexaploid wheat homoeologous genomes and to evaluate the potential of BAC‐end sequences (BES) for marker development, we have followed a chromosome‐specific strategy and generated 11 Mb of random BES from chromosome 3B, the largest chromosome of bread wheat. The sequence consisted of about 86% of repetitive elements, 1.2% of coding regions, and 13% remained unknown. With 1.2% of the sequence length corresponding to coding sequences, 6000 genes were estimated for chromosome 3B. New repetitive sequences were identified, including a Triticineae‐specific tandem repeat (Fat) that represents 0.6% of the B‐genome and has been differentially amplified in the homoeologous genomes before polyploidization. About 10% of the BES contained junctions between nested transposable elements that were used to develop chromosome‐specific markers for physical and genetic mapping. Finally, sequence comparison with 2.9 Mb of random sequences from the D‐genome of Aegilops tauschii suggested that the larger size of the B‐genome is due to a higher content in repetitive elements. It also indicated which families of transposable elements are mostly responsible for differential expansion of the homoeologous wheat genomes during evolution. Our data demonstrate that BAC‐end sequencing from flow‐sorted chromosomes is a powerful tool for analysing the structure and evolution of polyploid and highly repetitive genomes.
Effect of manufacturing process parameters on virus inactivation by dry heat treatment at 80 °C in factor VIII
Authors: Roberts P. L. , Dunkerley C. , McAuley A. , Winkelman L. 
Published: September 2006

Background and Objectives  Dry heat treatment at 80 °C for 72 h is used as a virus inactivation step for some coagulation factor concentrates such as Bio Products Laboratory's (BPL) factor VIII 8Y. In the current study, the effect of this process has been tested on a range of viruses. In addition the effect of various manufacturing process parameters on virus inactivation has been investigated.Materials and Methods  Samples of product intermediate were obtained from manufacturing, spiked with virus and subjected to freeze drying and dry heat treatment. Virus inactivation was determined by infectivity assay.Results  Freeze drying followed by dry heat treatment was effective for inactivating a wide range of enveloped and nonenveloped viruses. Sucrose or protein concentration had no effect on virus inactivation. Product presentation or the interruption of heat treatment also had no effect. The inactivation of some of the viruses was greater at higher residual water content but under such conditions the stability of the product was reduced.Conclusion  This virus inactivation step was effective for a wide range of viruses and over the range of process conditions encountered in manufacturing. This demonstrates the robustness of this process step.
Optische Aufheller in der Pilzdiagnostik
Authors: Schroeder J. , Schaffrinski Meike , Rüchel R. 
Published: September 2006

ZusammenfassungDie kontrastreiche Fluoreszenzfärbung mit Optischen Aufhellern aus der Gruppe der Diaminostilbene erlaubt eine schnelle, unkomplizierte Darstellung von Pilzelementen in klinischen Untersuchungsmaterialien und damit einen ersten Schritt zur Diagnose einer Mykose. Eine mikroskopische Differenzierung der verschiedenen Pilz‐Gattungen ist allerdings nur begrenzt möglich; diese bedarf vielmehr weiterführender Techniken wie z.B. der Immunhistochemie oder der in situ Hybridisierung.
Cardiac troponin levels in asymptomatic patients on the renal transplant waiting list
Authors: ROBERTS MATTHEW A , MACMILLAN NEIL , HARE DAVID L , RATNAIKE SUJIVA , SIKARIS KEN , FRAENKEL MARGARET B , IERINO FRANCESCO L 
Published: September 2006

SUMMARY:Aims:  Cardiac troponin levels predict mortality and cardiovascular events in asymptomatic patients receiving dialysis and may be a useful clinical tool to stratify high‐risk asymptomatic individuals.Methods:  The present study examined levels of troponins I (cTnI) and T (cTnT) in patients with chronic renal impairment, patients receiving dialysis and renal transplant recipients. Patients receiving dialysis on the renal transplant waiting list were compared with those excluded from the list based on medical criteria. Median levels were compared using the Kruskal–Wallis test and proportions compared by chi‐squared.Results:  Median troponin levels were higher in patients on dialysis than transplant recipients. Comparing patients receiving dialysis not listed compared with those listed for renal transplant, median cTnI levels were significantly higher (0.03 versus 0.02 µg/L, P < 0.01) whereas median cTnT levels were not. Patients listed for transplantation were younger, had less clinical cardiovascular disease and lower C‐reactive protein than those awaiting renal transplantation. The proportion of patients with elevated cTnT was not substantially different between patients awaiting renal transplantation (38%) and those excluded (52%). Levels of cTnI and cTnT were inversely related to renal function in predialysis and transplant patients, but were not related to time on dialysis for those receiving dialysis therapy.Conclusion:  As patients awaiting renal transplantation are clinically screened for cardiovascular disease but have frequently elevated cardiac troponin levels, troponin may be a useful clinical tool to identify high‐risk asymptomatic patients on dialysis prior to renal transplantation. The influence of renal function on the interpretation of cardiac troponin and risk prediction requires further evaluation.