bluuebunny/crossref_metadata_2025 huggingface dataset:
Histone H3 K36 methylation is mediated by a trans-histone methylation pathway involving an interaction between Set2 and histone H4
Authors: Du Hai-Ning , Fingerman Ian M. , Briggs Scott D.
Published: October 2008

Set2-mediated H3 K36 methylation is an important histone modification on chromatin during transcription elongation. Although Set2 associates with the phosphorylated C-terminal domain (CTD) of RNA polymerase II (RNAPII), the mechanism of Set2 binding to chromatin and subsequent exertion of its methyltransferase activity is relatively uncharacterized. We identified a critical lysine residue in histone H4 that is needed for interaction with Set2 and proper H3 K36 di- and trimethylation. We also determined that the N terminus of Set2 contains a histone H4 interaction motif that allows Set2 to bind histone H4 and nucleosomes. A Set2 mutant lacking the histone H4 interaction motif is able to bind to the phosphorylated CTD of RNAPII and associate with gene-specific loci but is defective for H3 K36 di- and trimethylation. In addition, this Set2 mutant shows increased H4 acetylation and resistance to 6-Azauracil. Overall, our study defines a new interaction between Set2 and histone H4 that mediates trans-histone regulation of H3 K36 methylation, which is needed for the preventative maintenance and integrity of the genome.
Mouse ES cells express endogenous shRNAs, siRNAs, and other Microprocessor-independent, Dicer-dependent small RNAs
Authors: Babiarz Joshua E. , Ruby J. Graham , Wang Yangming , Bartel David P. , Blelloch Robert
Published: October 2008

Canonical microRNAs (miRNAs) require two processing steps: the first by the Microprocessor, a complex of DGCR8 and Drosha, and the second by a complex of TRBP and Dicer. dgcr8Δ/Δ mouse embryonic stem cells (mESCs) have less severe phenotypes than dicer1Δ/Δ mESCs, suggesting a physiological role for Microprocessor-independent, Dicer-dependent small RNAs. To identify these small RNAs with unusual biogenesis, we performed high-throughput sequencing from wild-type, dgcr8Δ/Δ, and dicer1Δ/Δ mESCs. Several of the resulting DGCR8-independent, Dicer-dependent RNAs were noncanonical miRNAs. These derived from mirtrons and a newly identified subclass of miRNA precursors, which appears to be the endogenous counterpart of shRNAs. Our analyses also revealed endogenous siRNAs resulting from Dicer cleavage of long hairpins, the vast majority of which originated from one genomic locus with tandem, inverted short interspersed nuclear elements (SINEs). Our results extend the known diversity of mammalian small RNA-generating pathways and show that mammalian siRNAs exist in cell types other than oocytes.
RMI, a new OB-fold complex essential for Bloom syndrome protein to maintain genome stability
Authors: Xu Dongyi , Guo Rong , Sobeck Alexandra , Bachrati Csanad Z. , Yang Jay , Enomoto Takemi , Brown Grant W. , Hoatlin Maureen E. , Hickson Ian D. , Wang Weidong
Published: October 2008

BLM, the helicase mutated in Bloom syndrome, associates with topoisomerase 3α, RMI1 (RecQ-mediated genome instability), and RPA, to form a complex essential for the maintenance of genome stability. Here we report a novel component of the BLM complex, RMI2, which interacts with RMI1 through two oligonucleotide-binding (OB)-fold domains similar to those in RPA. The resulting complex, named RMI, differs from RPA in that it lacks obvious DNA-binding activity. Nevertheless, RMI stimulates the dissolution of a homologous recombination intermediate in vitro and is essential for the stability, localization, and function of the BLM complex in vivo. Notably, inactivation of RMI2 in chicken DT40 cells results in an increased level of sister chromatid exchange (SCE)—the hallmark feature of Bloom syndrome cells. Epistasis analysis revealed that RMI2 and BLM suppress SCE within the same pathway. A point mutation in the OB domain of RMI2 disrupts the association between BLM and the rest of the complex, and abrogates the ability of RMI2 to suppress elevated SCE. Our data suggest that multi-OB-fold complexes mediate two modes of BLM action: via RPA-mediated protein–DNA interaction, and via RMI-mediated protein–protein interactions.
Myc’s broad reach
Authors: Eilers Martin , Eisenman Robert N.
Published: October 2008

The role of the myc gene family in the biology of normal and cancer cells has been intensively studied since the early 1980s. myc genes, responding to diverse external and internal signals, express transcription factors (c-, N-, and L-Myc) that heterodimerize with Max, bind DNA, and modulate expression of a specific set of target genes. Over the last few years, expression profiling, genomic binding studies, and genetic analyses in mammals and Drosophila have led to an expanded view of Myc function. This review is focused on two major aspects of Myc: the nature of the genes and pathways that are targeted by Myc, and the role of Myc in stem cell and cancer biology.
Histone H2B ubiquitination: the cancer connection
Authors: Espinosa Joaquín M.
Published: October 2008

Post-translational modifications of histones play a critical role in gene expression control. Ultimately, cancer is a disease of aberrant gene expression. Accordingly, several histone-modifying enzymes have been described as proto-oncogenes or tumor suppressors. Recent reports, including one from Shema and colleagues (pp. 2664– 2676) in the October 1, 2008, issue of Genes and Development, indicate that deregulation of histone H2B monoubiquitination may contribute to cancer development.
Sus1 is recruited to coding regions and functions during transcription elongation in association with SAGA and TREX2
Authors: Pascual-García Pau , Govind Chhabi K. , Queralt Ethel , Cuenca-Bono Bernardo , Llopis Ana , Chavez Sebastián , Hinnebusch Alan G. , Rodríguez-Navarro Susana
Published: October 2008

Gene transcription, RNA biogenesis, and mRNA transport constitute a complicated process essential for all eukaryotic cells. The transcription/export factor Sus1 plays a key role in coupling transcription activation with mRNA export, and it resides in both the SAGA and TREX2 complexes. Moreover, Sus1 is responsible for GAL1 gene gating at the nuclear periphery, which is important for its transcriptional status. Here, we show that Sus1 is required during transcription elongation and is associated with the elongating form of RNA Polymerase II (RNAP II) phosphorylated on Ser5 and Ser2 of the C-terminal domain (CTD). In addition, Sus1 copurifies with the essential mRNA export factors Yra1 and Mex67, which bind to the mRNA cotranscriptionally. Consistently, ChIP analysis reveals that Sus1 is present at coding regions dependent on transcription in a manner stimulated by Kin28-dependent CTD phosphorylation. Strikingly, eliminating the TREX2 component Sac3 or the SAGA subunit Ubp8 partially impairs Sus1 targeting to coding sequences and upstream activating sequences (UAS). We found, unexpectedly, that Sgf73 is necessary for association of Sus1 with both SAGA and TREX2, and that its absence dramatically reduces Sus1 occupancy of UAS and ORF sequences. Our results reveal that Sus1 plays a key role in coordinating gene transcription and mRNA export by working at the interface between the SAGA and TREX2 complexes during transcription elongation.
mTOR inhibition reverses acquired endocrine therapy resistance of breast cancer cells at the cell proliferation and gene‐expression levels
Authors: Ghayad Sandra E. , Bieche Ivan , Vendrell Julie A. , Keime Celine , Lidereau Rosette , Dumontet Charles , Cohen Pascale A.
Published: October 2008

Activation of the Akt/mammalian target of rapamycin (mTOR) pathway has been shown to be associated with resistance to endocrine therapy in estrogen receptor alpha (ERα)‐positive breast cancer patients. Utmost importance is attached to strategies aimed at overcoming treatment resistance. In this context, this work aimed to investigate whether, in breast cancer cells, the use of an mTOR inhibitor would be sufficient to reverse the resistance acquired after exposure to endocrine therapy. The ERα‐positive human breast adenocarcinoma derived‐MCF‐7 cells used in this study have acquired both cross‐resistance to hydroxy‐tamoxifen (OH‐Tam) and to fulvestrant and strong activation of the Akt/mTOR pathway. Cell proliferation tests in control cells demonstrated that the mTOR inhibitor rapamycin enhanced cell sensitivity to endocrine therapy when combined to OH‐Tam or to fulvestrant. In resistant cells, rapamycin used alone greatly inhibited cell proliferation and reversed resistance to endocrine therapy by blocking the agonist‐like activity of OH‐Tam on cell proliferation and bypassing fulvestrant resistance. Reversion of resistance by rapamycin was associated with increased ERα protein expression levels and modification of the balance of phospho‐ser167 ERα/total ERα ratio. Pangenomic DNA array experiments demonstrated that the cotreatment of resistant cells with fulvestrant and rapamycin allowed the restoration of 40% of the fulvestrant gene‐expression signature. Taken together, data presented herein strongly support the idea that mTOR inhibitor might be one of the promising therapeutic approaches for patients with ERα‐positive endocrine therapy‐resistant breast cancers. (Cancer Sci 2008; 99: 1992–2003)
A commonNOS1APgenetic polymorphism is associated with increased cardiovascular mortality in users of dihydropyridine calcium channel blockers
Authors: Becker Matthijs L. , Visser Loes E. , Newton‐Cheh Christopher , Hofman Albert , Uitterlinden André G. , Witteman Jacqueline C. M. , Stricker Bruno H. Ch.
Published: October 2008

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

• Neuronal nitric oxide synthase (nNOS) regulates intracellular calcium handling

• A polymorphism in theNOS1APgene (rs10494366), a regulator of nNOS, is associated with QTc prolongation

• Calcium channel blockers also affect calcium handling by blocking the L‐type calcium channel

WHAT THIS STUDY ADDS

• We assessed the association between the polymorphism rs10494366 in theNOS1APgene and mortality in calcium channel blocker users

• The TG and GG genotype are associated with increased cardiovascular mortality in dihydropyridine calcium channel blocker users

AIM

Recently, a polymorphism in theNOS1APgene (rs10494366), a regulator of neuronal nitric oxide synthase (nNOS), was associated with QTc prolongation. Both nNOS and calcium channel blockers (CCBs) regulate intracellular calcium levels and have an important role in cardiovascular homeostasis. The aim was to investigate whether this polymorphism is associated with cardiovascular mortality in users of CCBs.

METHODS

The data from the Rotterdam study, a population‐based closed cohort study of Caucasian individuals of ≥55 years of age, were used. We identified 1113 participants in the Rotterdam Study who were prescribed CCBs for the first time between 1991 and 2005. All‐cause and cardiovascular mortality was assessed in participants who were prescribed CCBs with differentNOS1APrs10494366 genotypes using Cox proportional hazard models.

RESULTS

In participants starting on dihydropyridine CCBs (amlodipine, nifedipine and others) all‐cause mortality (n = 79) risks were higher in participants with the TG [hazard ratio (HR) 2.57, 95% confidence interval (CI) 1.24, 5.34] or the GG genotype (HR 3.18, 95% CI 1.18, 8.58) than in participants with the referent TT genotype. Cardiovascular mortality (n = 54) risks were 3.51 (95% CI 1.41, 8.78) for the TG genotype and 6.00 (95% CI 1.80, 20.0) for the GG genotype. No differences in all‐cause mortality or cardiovascular mortality were seen in participants starting with the nondihydropyridine CCBs verapamil or diltiazem.

CONCLUSION

The minor G allele of rs10494366 in theNOS1APgene is associated with increased all‐cause and cardiovascular mortality in Caucasian users of dihydropyridine CCBs. The mechanism underlying the observed association is unknown.
Immunomodulation by mercuric chloridein vitro: application of different cell activation pathways
Authors: Hemdan N Y A , Lehmann I , Wichmann G , Lehmann J , Emmrich F , Sack U
Published: October 2008

Evidence is emerging that exposure to mercury (Hg) may elicit many pathological manifestations, including immunomodulation. We tested whether changing cellular activation pathways may affect the immunomodulation by Hg. Human cell cultures were set up where isolated peripheral blood mononuclear cells, activated by monoclonal antibodies (MoAb: anti-CD3/-CD28/-CD40) or heat-killed Salmonella enterica serovar Enteritidis (hk-SE), exposed to mercuric chloride (HgCl2) for 24 h. Cell vitality was assessed by MTT assay, and modulation of cytokine profiles were monitored by enzyme-linked immunosorbent assay (ELISA), intracellular cytokine staining and reverse transcription–polymerase chain reaction (RT–PCR). Results show that Hg doses above 15 ng/ml significantly reduced cell vitality (P < 0·05). Lower doses elicited distinct effects on T helper 1 (Th1) and Th2 cytokine expression depending on cellular activation pathways. In MoAb-stimulated cells, interferon (IFN)-γ, tumour necrosis factor (TNF)-α and interleukin (IL)-6 production was reduced. Doses up to 0·150 and 0·5 µg/ml increased IL-10 and IL-4 production, respectively, resulting in significantly reduced Th1/Th2 ratios. Stimulation by hk-SE, however, elevated Th1/Th2 ratios due to induction of IFN-γversus IL-10 production. Taken together, we conclude that low-level exposure to Hg, in the absence of inflammation, polarizes the immune response toward Th2, but not in the case of Th1-polarized responses elicited by Salmonella antigens that can be promoted instead. This demonstrates differential in vitro effects of Hg on the Th1/Th2 balance produced by different stimuli, which may have important experimental and scientific implications.
Respiratory syncytial virus replication is prolonged by a concomitant allergic response
Authors: Hassantoufighi A , Oglesbee M , Richter B W M , Prince G A , Hemming V , Niewiesk S , Eichelberger M C
Published: October 2008

Epidemiological studies show an association between early exposure to respiratory syncytial virus (RSV) and the development or exacerbation of asthma. This idea is supported by studies in mice that demonstrate worsened airway hyper-reactivity (AHR) when RSV-infected animals are exposed to allergen. The effect of allergen on RSV disease, however, has not been reported. Cotton rats (Sigmodon hispidus) that have been used as a model to study RSV pathogenesis were sensitized to extracts of Aspergillus fumigatus (Af), a common household mould. The allergic response to Af included eosinophilia, formation of granulomas and induction of Th2 type cytokines. RSV infection prior to allergen challenge resulted in exacerbation of the inflammatory response as well as increased airway responsiveness to methacholine. The exacerbated response was indeed dependent on virus replication. Virus replication in turn was influenced by the allergic response, with persistence in the noses for 2 days longer in animals challenged with allergen. This diminished clearance corresponded to decreased induction of mRNA for IFN-γ, a Th1-type cytokine that is characteristic of viral infection. Treatment of RSV-infected Af-challenged animals with recombinant IFN-γ reduced the allergic inflammatory response as well as the relative levels of Th1 and Th2 cytokine mRNA. However, this treatment did not reduce airway reactivity, showing that these pathologic and physiologic measures of exacerbated disease are independent. We speculate that the reciprocal effect of the allergic response on viral immunity may benefit the host by limiting exacerbation of physiologic responses that are IFN-γ-dependent.
Differential activation of NF-κB and gene expression in oral epithelial cells by periodontal pathogens
Authors: Milward M R , Chapple I L C , Wright H J , Millard J L , Matthews J B , Cooper P R
Published: October 2008

To investigate the molecular effects of the periodontopathogens Fusobacterium nucleatum (FN) and Porphyromonas gingivalis (PG) on the oral epithelium, the H400 oral epithelial cell line was cultured in the presence of non-viable bacteria. Following confirmation of the presence of transcripts for the bacterial pattern recognition receptors in H400 cells, Toll-like receptors -2, -4 and -9, and components of the NF-κB signalling pathway, immunocytochemical analyses were performed showing that NF-κB was activated within 1 h of exposure to both periodontopathogens. A significantly greater number of NF-κB nuclear translocations were apparent following H400 cell exposure to FN as compared with PG. Gene expression analyses indicated that transcripts known to be regulated by the NF-κB pathway, including cytokines/chemokines TNF-α, IL-1β, IL-8, MCP-1/CCL2 and GM-CSF, were up-regulated following 4 and 24 h of exposure to both periodontopathogens. In addition, H400 periodontopathogen exposure resulted in differential regulation of transcripts for several cytokeratin gene family members. Consistent with the immunocytochemical data, microarray results indicated that FN induced a greater number of gene expression changes than PG following 24 h of exposure, 609 and 409 genes, respectively. Ninety-one genes were commonly differentially expressed by both periodontopathogens and represented biological processes commonly associated with periodontitis. Gene expression analyses by reserve transcriptase-polymerase chain reaction (RT-PCR) of molecules identified from the microarray data sets, including Heme oxygenase-1, lysyl oxidase, SOD2, CCL20 and calprotectin components, confirmed their differential expression profiles induced by the two periodontopathogens. FN and PG have clearly different molecular effects on oral epithelial cells, potentially highlighting the importance of the composition of the plaque biofilm in periodontitis pathogenesis.
Protective role of mannan-binding lectin in a murine model of invasive pulmonary aspergillosis
Authors: Kaur S , Gupta V K , Thiel S , Sarma P U , Madan T
Published: October 2008

Innate immune molecules such as lung collectins and serum pentraxins have evolved as important host defence proteins against Aspergillus fumigatus, a medically important opportunistic fungal pathogen. Mannan-binding lectin (MBL), an opsonin and lectin complement pathway activator, constitutes another vital player of innate immunity against several pathogenic organisms in the serum. Studies have reported significant binding of MBL to A. fumigatus; however, the protective role of MBL against A. fumigatus-mediated invasive disease remains elusive. Henceforth, we investigated the contribution of externally administered recombinant human (rh) MBL towards anti-fungal defence in invasive pulmonary aspergillosis (IPA) by in vivo and in vitro studies. In murine models of IPA with corticosteroid-induced immunosuppression, rhMBL-treated mice showed 80% survival compared to untreated IPA mice with no survivors. Treated IPA mice also showed a marked increase in tumour necrosis factor (TNF)-α and interleukin (IL)-1α and a significant decrease in pulmonary fungal hyphae and IL-10. In vitro, rhMBL-bound A. fumigatus conidia showed a dose-dependent increase in the deposition of C4b, the first product of the lectin pathway. There was an enhanced uptake of A. fumigatus conidia by the polymorphonuclear cells (PMNs) in the presence of rhMBL that increased further in the presence of MBL supplemented with MBL-deficient serum. However, an increase in the oxidative burst of PMNs and A. fumigatus killing were observed only when MBL was supplemented with MBL-deficient serum. The study suggests a therapeutic role of ex vivo-administered MBL in host defence against aspergillosis, possibly through MBL-mediated complement activation and other protective mechanisms aimed both directly at the pathogen, and indirectly through modulation of the host inflammatory responses.
Administration of anti-type II collagen antibody sustains footpad swelling of mice caused by a delayed-type hypersensitivity reaction and induces severe arthritis
Authors: Tanaka D , Kagari T , Doi H , Shimozato T
Published: October 2008

Delayed-type hypersensitivity (DTH) is an immune reaction induced by antigen. In the mice footpads at which DTH is elicited, transient swellings which usually peaks at 24–48 h after the antigen challenge are observed. We found that the footpad swellings of mice are sustained for at least 7 days after the antigen challenge if the mice were injected with anti-type II collagen monoclonal antibody (anti-CII MoAb) before the antigen challenge. A histological section of the swelled hindpaw revealed that severe joint inflammation and bone destruction was induced. These features were not observed in the footpads of the DTH-induced mice. Analysis of the inflammatory reaction induced by both the DTH and the anti-CII MoAb injection, here named as DTH arthritis, revealed the following: (1) DTH arthritis is elicited in an antigen-specific manner; and (2) the development of DTH arthritis is mediated by antigen-specific T cells, especially CD4+ T cells.
Evidence for involvement of TNFR1 and TIMPs in pathogenesis of post-kala-azar dermal leishmaniasis
Authors: Ansari N A , Katara G K , Ramesh V , Salotra P
Published: October 2008

Semi-quantitative RT–PCR was exploited to analyse the intralesional cytokine gene expression in 14 post-kala-azar dermal leishmaniasis (PKDL) and 10 kala-azar (KA) patients. The data provided evidence for both inflammatory and non-inflammatory responses, as reflected by elevated tumour necrosis factor (TNF)-α and interleukin (IL)-10 in PKDL lesions compared with normal skin tissue (n = 6). The ratio of TNF-α : IL-10 message was 2·66 in PKDL cases, substantially higher than in KA (1·18). Investigation of TNF-α receptors (TNFR1 and TNFR2) revealed a significant down-regulation of TNFR1 transcript in both PKDL and KA compared with control. In the presence of elevated levels of TNF-α transcript, interference with type 1 effector activity in PKDL may be due to minimal expression of the TNFR1 gene. Investigation of matrix metalloproteinases, known to be induced by TNF-α, and the tissue inhibitors of matrix metalloproteinases (TIMPs), provided evidence for the roles of TIMP-1 and TIMP-3 in the pathogenesis of PKDL.
Effects of freeze–thaw on C and N release from soils below different vegetation in a montane system: a laboratory experiment
Authors: VESTGARDEN LIVE SEMB , AUSTNES KARI
Published: October 2008

Unstable snow cover and more frequent freeze–thaw events have been predicted for montane areas in southern Norway, where stable winters are common today. These systems are important contributors to the flux of carbon (C) and nitrogen (N) to air and water. Here we quantify and compare the effects of freeze–thaw on C and N release from soils collected below Calluna, Molinia or Sphagnum. Intact organic soil cores were subjected to four different freeze–thaw regimes for four consecutive 2‐week periods: (1) slow cycling (SC) with one long freezing event during each 2‐week period, (2) fast cycling (FC) with four short freezing events during each 2‐week period, (3) permanent frost (PF) and (4) permanent thaw (PT). The freezing temperature was −5 °C and the thawing temperature was 5 °C. Before start of treatment, at the end of each 2‐week period, and during postincubation periods, carbon dioxide (CO2) emission as well as leachable dissolved organic C (DOC), dissolved organic N (DON), ammonium (NH4), nitrate (NO3) and absorbance at 254 nm were measured. In soils from all three vegetations, PF increased the release of CO2, DOC, DON and NH4 compared with PT. SC caused some scattered effects whereas FC only resulted in some increase in NO3 release below Molinia. Generally, the emission of CO2 and leaching of DOC, DON and NH4 increased in the following order: Sphagnum < Calluna < Molinia. The release of NO3 was greatest below Calluna. Our data suggest that vegetation cover and composition seem at least as important as increased soil frost for future winter fluxes of CO2, DOC, DON and dissolved inorganic N (DIN) from the soil to air and water. The freezing period needs to be sufficiently long to give significant effects.
Interactive effects of water table and precipitation on net CO2assimilation of three co‐occurringSphagnummosses differing in distribution above the water table
Authors: ROBROEK BJORN J. M. , SCHOUTEN MATTHIJS G. C. , LIMPENS JUUL , BERENDSE FRANK , POORTER HENDRIK
Published: October 2008

Sphagnum cuspidatum,S. magellanicumandS. rubellumare three co‐occurring peat mosses, which naturally have a different distribution along the microtopographical gradient of the surface of peatlands. We set out an experiment to assess the interactive effects of water table (low: −10 cm and high: −1 cm) and precipitation (present or absent) on the CO2assimilation and evaporation of these species over a 23‐day period. Additionally, we measured which sections of the moss layer were responsible for light absorption and bulk carbon uptake. Thereafter, we investigated how water content affected carbon uptake by the mosses. Our results show that at high water table, CO2assimilation of all species gradually increased over time, irrespective of the precipitation. At low water table, net CO2assimilation of all species declined over time, with the earliest onset and highest rate of decline forS. cuspidatum. Precipitation compensated for reduced water tables and positively affected the carbon uptake of all species. Almost all light absorption occurred in the first centimeter of theSphagnumvegetation and so did net CO2assimilation. CO2assimilation rate showed species‐specific relationships with capitulum water content, with narrow but contrasting optima forS. cuspidatumandS. rubellum. Assimilation byS. magellanicumwas constant at a relatively low rate over a broad range of capitulum water contents. Our study indicates that prolonged drought may alter the competitive balance between species, favoring hummock species over hollow species. Moreover, this study shows that precipitation is at least equally important as water table drawdown and should be taken into account in predictions about the fate of peatlands with respect to climate change.
N2O emission rates in a California meadow soil are influenced by fertilizer level, soil moisture and the community structure of ammonia‐oxidizing bacteria
Authors: AVRAHAMI SHARON , BOHANNAN BRENDAN J. M.
Published: October 2008

The response of nitrous oxide (N2O) emission rates and β‐proteobacterial ammonia‐oxidizing (AOB) communities to manipulations of temperature, soil moisture and nitrogenous fertilizer concentration were studied for 16–20 weeks in a multifactorial laboratory experiment using a California meadow soil. Interactions among these three environmental factors influenced the N2O emission rates, and two patterns of N2O emission rates due to nitrification (NitN2O) were observed. First, in soils receiving low or moderate amounts of fertilizer, the rates decreased sharply in response to increasing soil moisture and temperature. Second, in soils receiving high amounts of fertilizer, the rates were influenced by an interaction between soil moisture and temperature, such that at 20 °C increasing soil moisture resulted in an increase in the rates, and at 30 °C the highest rate was observed at moderate soil moisture. We used path analysis to identify the interrelationships that best explain these two patterns. Path analysis revealed that in the high fertilizer (HF) treatment, the major path by which ammonia influenced NitN2O rates was indirect through an influence on the abundance of one particular phylogenetic group (AOB ‘cluster 10’). In contrast, in the low and moderate fertilizer treatments soil moisture influenced the rates both directly (the major path) and indirectly through AOB community structure. Although terminal restriction fragment length polymorphism (T‐RFLP) analysis revealed shifts in the community structure of AOB in all treatments, the shifts at HF concentrations were particularly striking, with dominance by three different phylogenetic groups under different combinations of the three environmental factors. The high emission rates observed at the lowest soil moistures suggest that bacterial nitrifiers may use denitrification as a stress response.
Elevated methylmercury in High ArcticDaphniaand the role of productivity in controlling their distribution
Authors: CHÉTELAT JOHN , AMYOT MARC
Published: October 2008

Mercury is a contaminant of concern in polar regions due to long‐range atmospheric transport of this metal from southern latitudes followed by intense deposition on snow. We surveyed zooplankton in 16 lakes and ponds in the Canadian Arctic Archipelago (74–76°N) to determine methylmercury (MeHg) content and the role of environmental characteristics and taxonomic composition on accumulation processes. Zooplankton communities containingDaphnia(mainlyD. middendorffiana) had on average five times the MeHg content of copepod‐dominated communities. The percent biomass ofDaphniabest explained MeHg variation in bulk zooplankton compared with water chemistry and morphometric variables. Water‐column concentrations of MeHg were low at most study sites (mainly ≤0.07 ng L−1), andDaphniastrongly bioaccumulated mercury through species‐specific processes. As we observedDaphniain more productive water bodies (i.e., ponds, a eutrophied lake), we then tested the role of productivity in determining the distribution of this keystone herbivore using a broad‐scale literature dataset of 47 High Arctic lakes (65–77°N).Daphniadensity was positively related to the amount of organic carbon in the water column in both dissolved and particulate fractions [dissolved organic carbon (DOC) partial,P< 0.001; particulate organic carbon (POC) partial,P=0.032]. The strong influence of DOC suggests that bacterial production is an important energy source for ArcticDaphnia. Our findings indicate that productivity influences the MeHg content of zooplankton communities through its control of species composition; specifically, low productivity limits the presence of mercury‐richDaphniain many copepod‐dominated lakes of the High Arctic. Aquatic productivity is expected to increase with climate warming, and we present a conceptual model that predicts how environmental drivers could extend the distribution ofDaphniain lakes and alter the movement of mercury in food webs of the Canadian High Arctic.
Optical techniques to determine thermal effects on proteins
Authors: Kongraksawech Teepakorn , Vázquez‐Landaverde Pedro , Rodrigo‐Garcia Joaquín , Torres José A. , Huerta‐Ruelas Jorge
Published: October 2008

Optical rotation (OR) and transmitted light (TL) measurements were conducted on 1%, 2.5% and 5% (w/v) bovine serum albumin (BSA) in 0.01 m phosphate buffer at pH 7 and ionic strength 0.08. Denaturation temperatures (Td) obtained from OR measurements were consistent with reported differential scanning calorimetry values. Protein concentration did not affect Td in agreement with most reports. Changes in TL reflecting gel formation and protein aggregation were influenced by BSA concentration. Sugar concentration in the range used in this study (0–5%) did not affect the thermal stability of BSA. The lack of difference in sucrose, trehalose and sorbitol effects on the thermal stability of BSA was consistent with some but not all reports. The optical system used to study protein denaturation had acceptable accuracy (consistency with published Td values) and precision (coefficient of variation under 3.5%) levels.
Antioxidant activity and dietary fibre of Prensal Blanc white grape (Vitis vinifera) by‐products
Authors: Llobera Antonia , Cañellas Jaime
Published: October 2008

Stem and pomace of a white grape (Vitis vinifera) variety, Prensal Blanc, were studied for the first time: general composition and dietary fibre components together with the total soluble polyphenol content and antioxidant activity. Both by‐products present high contents of total dietary fibre (TDF), 790 g kg−1 d.m. (stem) and 716 g kg−1 d.m. (pomace). Values of the soluble dietary fibres in relation to TDF differed: 5% (stem) and 14.4% (pomace). Similar values of Klason lignin were found: 229 g kg−1 (stem) and 278 g kg−1 (pomace), however, the pomace exhibited more than twice the content of the condensed tannins (168 g kg−1) with regard to the stem (79 g kg−1). Notable were the high resistant protein contents of both by‐products. Stem and pomace showed appreciable amounts of total soluble polyphenols (87 g kg−1 against 35 g kg−1 respectively). The free radical scavenging capacity of the former by‐products was determined using the 2,2‐diphenyl‐1‐picrylhydrazyl radical (DPPH) method, obtaining EC50 values of 0.79 g d.m. g−1 DPPH (stem) and 1.32 g d.m. g−1 DPPH (pomace). These data shows that both vinification by‐products from the Prensal Blanc variety are a good source of dietary fibre and have antioxidant properties.
Physico‐chemical and sensory attributes in conjunction with multivariate analysis of two potato (Solanum tuberosum L.) cultivars after 90 days of storage: an exploratory authentication study
Authors: Arvanitoyannis Ioannis S. , Vaitsi Olga , Mavromatis Athanasios
Published: October 2008

Two cultivars of potato (Spunta and Agria), were studied in terms of their physico‐chemical and sensory characteristics. These cultivars were cultivated in three geographical regions of Greece (Macedonia, North Greece; Thessaly, Central Greece; Peloponnese, South Greece) and were stored for 90 days after harvesting. The physico‐chemical characteristics of the tubers determined, were pH, total acidity, firmness, dry matter and content in Ν, in Κ, P, Cu, Mn, Zn and Fe. The sensory characteristics measured for raw tubers of potato after storage, were skin colour, skin brightness, internal colour, surface roughness, odour intensity, moistness, surface wrinkling and stains while the sensory characteristics measured for the boiled tubers of potato were odour intensity, moistness, special taste, sweet taste, aftertaste persistence, metal taste, pastiness, mastication, flavour intensity, elasticity and overall acceptability. The application of multivariate analysis (principal component analysis, cluster analysis and discriminant analysis), revealed a variety of relations between the various parameters and resulted in satisfactory grouping either per geographical region or per cultivar.
Effects of operating practices on performance of a fixed‐bed convection dryer and quality of dried longan
Authors: Nagle Marcus , González‐Azcárraga Juan Carlos , Phupaichitkun Sarawut , Mahayothee Busarakorn , Haewsungcharern Methinee , Janjai Serm , Leis Hermann , Müller Joachim
Published: October 2008

Bulk layer shifting during industrial drying of whole longan was evaluated. Analysis of drying conditions and product quality of samples from different areas of the dryer was conducted. The study found that both temperature and air velocity were non‐uniformly distributed during drying, which affected drying kinetics and product quality. High humidity and convective cooling of the drying air passing through the bulk caused condensation on fruits surfaces in the upper layer during the initial hours of drying. Those samples towards the sides of dryer, those initially in the upper layers, and especially those near the air inlet showed consistently lower quality. Four shifting schemes were tested, one of which was found to be exceptional in terms of end‐product uniformity. Issues concerning the improvement of industrial longan drying are addressed and an optimal shifting procedure is proposed.
The effect of thermal treatment on β‐glucosidase inactivation in vanilla bean (Vanilla planifolia Andrews)
Authors: Márquez Ofelia , Waliszewski Krzysztof N.
Published: October 2008

The conditions for enzyme activity (pH and temperature) and kinetic parameters for the thermal inactivation of β‐glucosidase enzyme in vanilla beans have been investigated. The maximum enzyme activity was detected at pH 6.5 and 38 °C. The values obtained for Vmax and Km were 62.05 units and 2.07 mm, respectively. When hot water treatment (the most practical method of vanilla bean killing) was applied, β‐glucosidase treated at pH 6.0 and 60 °C for 3 min lost 51% of activity, while at 70 °C for 90 s the enzyme lost 60% of activity and at 80 °C for 30 s the enzyme lost 48% of its activity. When vanilla beans were cured in an oven at 60 °C for 36 to 48 h all β‐glucosidase activity was lost.
Effect of different chemical compounds as coadjutants of 4‐hexylresorcinol on the appearance of deepwater pink shrimp (Parapenaeus longirostris) during chilled storage
Authors: Martínez‐Alvarez Oscar , Gómez‐Guillén Carmen , Montero Pilar
Published: October 2008

Different chemical compounds (kojic acid, cumic acid, phytic acid, sodium metabisulphite, magnesium carbonate, sorbic acid and different protease inhibitors) were used as coadjutants in 4‐hexylresorcinol (4‐HR)‐based melanosis‐inhibiting formulas tested for inhibiting melanosis in pink shrimp (Parapenaeus longirostris). The experiment was performed on board ship. Increasing concentrations of 4‐HR delayed the occurrence of melanosis during storage. However, 4‐HR could not prevent the appearance of a yellow‐greenish colouration in the cephalothorax that diminishes the consumer acceptability of shrimps. The incorporation of protease inhibitors (ethylenediaminetetraacetic acid, disodium dihydrogen pyrophosphate, iodoacetic acid, egg white and phenylmethylsulphonyl fluoride) into the 4‐HR‐based mixtures improved the acceptability after storage, suggesting that protease activity post‐mortem contributes to the reduction in the final acceptability of crustaceans.
Antifungal activity of biopolymers containing natamycin and rosemary extract against Aspergillus niger and Penicillium roquefortii
Authors: Türe Hasan , Eroğlu Erdal , Soyer Ferda , Özen Banu
Published: October 2008

Antimicrobial agent‐releasing films have been proposed as an effective way of inhibiting chiefly surface spoilage of food products. Antifungal activities of natamycin (NA), rosemary extract (RE) and NA + RE were tested against Aspergillus niger and Penicillium roquefortii with agar disc diffusion assay. NA, RE and NA + RE were also included into biopolymers made from gluten and methyl cellulose. Minimum inhibitory concentrations (MIC) of NA in both films were 2 and 1 mg NA per 10 g film solution against A. niger and P. roquefortii, respectively. RE did not show any inhibitory antifungal activity alone. Although NA incorporated into both films at a concentration of 1.5 mg NA per 10 g film solution was not effective against A. niger, combination of NA at the same concentration with RE in the films inhibited the growth of this mould. NA in solution or in biopolymers is very effective in inhibiting the growth of selected organisms, and RE acted synergistically with NA to prevent the growth of A. niger when incorporated into both films.
Image analysis and quality attributes of malting barley grain dried with infrared radiation and in a spouted bed
Authors: Konopka Iwona , Markowski Marek , Tańska Małgorzata , Żmojda Marta , Małkowski Mateusz , Białobrzewski Ireneusz
Published: October 2008

The impact of drying two spring barley cultivars (Mauritia and Prestige) in a spouted‐bed and in infrared radiation (IR) dryers on grain dimensions, colour, pigment content, vitality and malt quality was investigated. The results indicate that the investigated drying methods led to kernel dimension changes. Kernel shrinkage was typical of spouted bed drying, while kernel expansion was observed after IR drying at the intensity of 900 W m−2. An increase in the intensity of yellowness (b*) on the surface of dried grain and a decrease in the yellowness intensity of kernel cross‐section were also observed. The aforementioned changes were associated with the decomposition of carotenoids (endosperm colour) and reduction of soluble proanthocyanidin and total phenolic compounds (surface colour). The drying processes also lowered germination energy and capacity, in addition to susceptibility to moisture diffusion into the endosperm. These adverse results were cultivar dependent and affected the quality of malt and wort only to a limited extent. The main changes were an increase in the Kolbach index in malt from Mauritia cv., and a fluctuation of the diastatic power of malt that did not exceed ±3%. Generally, drying of barley grain in spouted bed should be conducted at an inlet air temperature of 40 °C and using an IR drier at a radiation intensity of 600 W m−2.
Effect of thermochemical treatment on the structure of inulin and its gelling properties
Authors: Glibowski Pawel , Wasko Adam
Published: October 2008

The aim of this study was to investigate rheological properties of inulin gels and the changes in the inulin structure after heating the high polymerised inulin (DP ≥ 23) solutions at different pH. The 20% inulin solutions were heated at pH 3, 5 and 7 at 60 and 80 °C followed by 21 h storage at 5 and 25 °C. Rheological properties evaluation indicated that the increase in the heating time and temperature significantly (P ≤ 0.05) influenced on the inulin structure. Reducing sugars, cryoscopy and HPLC analysis revealed that chemical structure of inulin is stable in neutral and slightly acidic conditions (pH 5). Gelation of the high polymerised inulin solution after heating at pH 7 and 80 °C could be inhibited after dissolving the inulin crystallites which act like seeding crystals. At lower temperatures in which, not all crystallites were dissolved; it was feasible for the solutions to form firm inulin gels.
Competency measurements: testing convergent validity for two measures
Authors: Cowin Leanne S. , Hengstberger‐Sims Cecily , Eagar Sandy C. , Gregory Linda , Andrew Sharon , Rolley John
Published: October 2008

Title.  Competency measurements: testing convergent validity for two measures

Aim.  This paper is a report of a study to investigate whether the Australian National Competency Standards for Registered Nurses demonstrate correlations with the Finnish Nurse Competency Scale.

Background.  Competency assessment has become popular as a key regulatory requirement and performance indicator. The term competency, however, does not have a globally accepted definition and this has the potential to create controversy, ambiguity and confusion. Variations in meaning and definitions adopted in workplaces and educational settings will affect the interpretation of research findings and have implications for the nursing profession.

Method.  A non‐experimental cross‐sectional survey design was used with a convenience sample of 116 new graduate nurses in 2005. The second version of the Australian National Competency Standards and the Nurse Competency Scale was used to elicit responses to self‐assessed competency in the transitional year (first year as a Registered Nurse).

Findings.  Correlational analysis of self‐assessed levels of competence revealed a relationship between the Australian National Competency Standards (ANCI) and the Nurse Competency Scale (NCS). The correlational relation between ANCI domains and NCS factors suggests that these scales are indeed used to measure related dimensions. A statistically significant relationship (r = 0·75) was found between the two competency measures.

Conclusion.  Although the finding of convergent validity is insufficient to establish construct validity for competency as used in both measures in this study, it is an important step towards this goal. Future studies on relationships between competencies must take into account the validity and reliability of the tools.
The mother–daughter guilt dynamic: effects of type 1 diabetes during life transitions
Authors: Rasmussen Bodil , Dunning Trisha , Cox Helen , O’Connell Beverly
Published: October 2008

Aim.  The aim of the study was to explore and describe the strategies young women with type 1 diabetes used to manage life transitions. The paper describes one aspect of how guilt dynamic often operates between mothers and daughters and how the women managed the guilt dynamic to create stability in their lives.

Background.  When a child is diagnosed with diabetes, major transitional changes occur in the relationships between the mother and her child. The changes affect the psychological and social aspects of their lives and have a major impact on how young women manage their diabetes. A guilt dynamic between mothers and young women with diabetes emerged as a major theme in a larger study that investigated how young women with diabetes managed life transitions. Although the literature indicates that mothers of chronically ill children experience guilt feelings towards their children, little research was identified that addressed the emotional dynamics between mothers and daughters with diabetes.

Design.  Using grounded theory method, interviews were conducted with 20 women with type 1 diabetes and five mothers during 2002 and 2003. Constant comparative analysis was used to analyse the data and develop an in‐depth understanding of the experience of living with diabetes during life transitions.

Findings.  The findings revealed that guilt feelings created a two‐way dependency between mothers and their daughters with diabetes. The two‐way dependency involved feelings of being a burden to each other, difficulty balancing responsibilities for diabetes management, difficulty relinquishing emotional and social dependency especially during life transitions. In addition, these issues were rarely discussed openly with each other or with health professionals. The findings provide additional information about the human experience of the mother–daughter relationship and the effect on coping with diabetes in the context of life transitions.

Conclusions.  Understanding the impact diabetes has on the emotional and social well being of both women with type 1 diabetes and their mothers is critical in planning appropriate support for both groups. Most importantly, it is critical to understand the guilt dynamic that operates during young women with diabetes’ life transitions when the daughters’ dependency on their mother’s control and responsibility for diabetes management undergo changes resulting in emotional responses, especially guilt feelings.

Relevance to clinical practice.  Health professionals need to understand the emotional and social impact of the guilt dynamics between young women with type 1 diabetes and their mothers. Adequate and appropriate support can minimize the guilt feelings and enhance stability and quality of life for both mothers and their daughters, especially during major life transitions, such as motherhood.