bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular investigations into a globally important carbon pool: permafrost‐protected carbon in Alaskan soils
Authors: WALDROP M. P. , WICKLAND K. P. , WHITE III R. , BERHE A. A. , HARDEN J. W. , ROMANOVSKY V. E. 
Published: December 2009

AbstractThe fate of carbon (C) contained within permafrost in boreal forest environments is an important consideration for the current and future carbon cycle as soils warm in northern latitudes. Currently, little is known about the microbiology or chemistry of permafrost soils that may affect its decomposition once soils thaw. We tested the hypothesis that low microbial abundances and activities in permafrost soils limit decomposition rates compared with active layer soils. We examined active layer and permafrost soils near Fairbanks, AK, the Yukon River, and the Arctic Circle. Soils were incubated in the lab under aerobic and anaerobic conditions. Gas fluxes at −5 and 5 °C were measured to calculate temperature response quotients (Q10). The Q10 was lower in permafrost soils (average 2.7) compared with active layer soils (average 7.5). Soil nutrients, leachable dissolved organic C (DOC) quality and quantity, and nuclear magnetic resonance spectroscopy of the soils revealed that the organic matter within permafrost soils is as labile, or even more so, than surface soils. Microbial abundances (fungi, bacteria, and subgroups: methanogens and Basidiomycetes) and exoenzyme activities involved in decomposition were lower in permafrost soils compared with active layer soils, which, together with the chemical data, supports the reduced Q10 values. CH4 fluxes were correlated with methanogen abundance and the highest CH4 production came from active layer soils. These results suggest that permafrost soils have high inherent decomposability, but low microbial abundances and activities reduce the temperature sensitivity of C fluxes. Despite these inherent limitations, however, respiration per unit soil C was higher in permafrost soils compared with active layer soils, suggesting that decomposition and heterotrophic respiration may contribute to a positive feedback to warming of this eco region.
Slow response of soil organic matter to the reduction in atmospheric nitrogen deposition in a Norway spruce forest
Authors: DÖRR NICOLE , KAISER KLAUS , MIKUTTA ROBERT , GUGGENBERGER GEORG 
Published: December 2009

AbstractGlobal nitrogen (N) deposition rates in terrestrial environments have quadrupled since preindustrial times, causing structural and functional changes of ecosystems. Different emission reduction policies were therefore devised. The aim of our study was to investigate if, and over what timescale, processes of soil organic matter (OM) transformation respond to a decline in atmospheric N deposition. A N‐saturated spruce forest (current N deposition: 34 kg ha−1 yr−1; critical N load: 14 kg ha−1 yr−1), where N deposition has been reduced to 11.5 kg ha−1 yr−1 since 1991, was studied. Besides organic C and organic and inorganic N, noncellulosic carbohydrates, amino sugars and amino acids were determined. A decline in organic N in litter indicated initial effects at plant level. However, there were no changes in biomarkers upon the reduction in N deposition. In addition, inorganic N was not affected by reduced N deposition. The results showed that OM cycling and transformation processes have not responded so far. It was concluded that no direct N deposition effects have occurred due to the large amount of stored organic N, which seems to compensate for the reduction in deposited N. Obviously, the time span of atmospheric N reduction (about 14.5 years) is too short compared with the mean turnover time of litter to cause indirect effects on the composition of organic C and N compounds. It is assumed that ecological processes, such as microbial decomposition or recycling of organic N and C, react slowly, but may start within the next decade with the incorporation of the new litter.
Differential effect of specific gr/gr deletion subtypes on spermatogenesis in the Chinese Han population
Authors: Yang Y. , Ma M. , Li L. , Su D. , Chen P. , Ma Y. , Liu Y. , Tao D. , Lin L. , Zhang S. 
Published: December 2009

SummaryAs a common variation in the azoospermia factor c (AZFc) region of Y chromosome, the gr/gr deletion is regarded as a significant risk factor for spermatogenic impairment, whereas the association of the deletion’s phenotypic expression with Y‐chromosomal background is still a subject of debate. To further investigate the contribution of the deletion to spermatogenic impairment in different Y‐chromosomal haplogroups, the partial AZFc deletion was detected with AZFc‐specific sequence tagged sites, gene dosage and gene copy analyses of deleted in azoospermia (DAZ), chromodomain Y1 (CDY1) and basic protein Y2 (BPY2) in 1426 azoo/oligozoospermic and 672 normozoospermic men from a Chinese population. The haplogrouping was performed in 231 deletion carriers with 12 polymorphic loci of Y chromosome. As a result, five gr/gr rearrangement types in eight Y haplogroups were observed, in which the simple gr/gr deletion was the most common type, and its frequency was significantly higher in men with azoo/oligozoospermia relative to normozoospermia. Also the distribution of gr/gr‐rearranged Y haplogroups was significantly different between the two groups, in which gr/gr‐deleted haplogroups C and DE were more common in men with azoo/oligozoospermia. In the 6 gr/gr copy deletion haplotypes, the frequencies of DAZ1/DAZ2+CDY1a or CDY1b deletion were significantly higher in men with azoo/oligozoospermia, while all DAZ3/DAZ4+CDY1b+BPY2.2 or 2.3 deletions were found only in haplogroup Q1 without any distribution difference between the azoo/oligozoospermic and normozoospermic groups. This study provided further evidence for the existence of multiple subtypes of gr/gr deletion and indicates that gr/gr‐DAZ1/DAZ2 deletion is a significant risk factor. However, the association of the phenotypic variation of gr/gr deletion with Y‐chromosomal haplogroups is not definite yet, because of the limited amounts of the deletions observed in each of the haplogroups and the lack of the quantitative trait analyses such as sperm density analysis. The fact that a common gr/gr copy deletion haplotype was found exclusively in the Y hgr Q1, without pathogenic consequences, implies the importance of haplogrouping and of copy deletion typing prior to genetic counselling of deletion carriers of Chinese descent.
Effectiveness of a presentation on infant oral health care for parents
Authors: ROTHE VINCENT , KEBRIAEI AMY , PITNER SHERYL , BALLUFF MARY , SALAMA FOUAD 
Published: December 2009

Purpose.  The aim of this study was to evaluate an infant oral health education programme, using a pre–post test design, for parents attending a paediatric clinic.Methods.  The subjects were parents attending the well baby appointments at 3, 6, and 9 months of age. The study participants were men and women, all with an infant between 3 and 12 months of age. A 16 question assessment in the form of a questionnaire was completed immediately before and after the introduction of a 30 min educational intervention in the form of a PowerPoint presentation and a video of infant oral hygiene for parents. The parents completed the questionnaire twice (pre–post test design) in the same visit. Recruited parents attended only one presentation. The presentation educated parents about infant oral health and provided anticipatory guidance.Results.  Forty‐seven parents or caretakers participated in the study. On the pre‐test 28% had a score of 70% or less, and on the post‐test 87% got a score of 88% or better. On the pre‐test, 72% had a score of 70% or higher, and on the post‐test 87% got a score of 88% or higher. Most parents (80%) reported that the presentation was helpful and indicated that the information would change the way they care for their baby’s teeth at home.Conclusion.  This study demonstrated the effectiveness of a 30 min PowerPoint and Video presentation in improving the oral health knowledge of parents caring for an infant.
Periodontal disease in mothers indicates risk in their children
Authors: PÄHKLA ENE‐RENATE , JÕGI EERIK , NURK ALLAN , PISAREV HETI , KOPPEL TAIVE , NAABER PAUL , SAAG MARE , LÕIVUKENE KRISTA 
Published: December 2009

Introduction.  It is well established that severe periodontitis clusters in families, but there are no data about the relationship between mothers with chronic periodontitis and their children’s periodontal status.Objective.  To evaluate a risk for periodontal diseases in children of periodontally diseased and healthy mothers.Methods.  Four study groups were included: (I) 20 female patients with untreated generalized severe chronic periodontitis, (II) their children (34), (III) 13 periodontally healthy mothers and (IV) their children (13). Material was collected from years 2004–2006. The clinical examination included registration of visible plaque index, modified gingival index and, bleeding sites on probing. Periodontal microbiological samples were obtained from all study subjects and the isolates were identified according to morphology and biochemical profiles; similar interfamilial pathogens were compared by PCR‐technique.Results.  The children of diseased mothers more frequently had periodontal diseases, especially gingivitis. In addition, clinical parameters of gingival inflammation were more expressed and oral hygiene was worse in this group of children. VPI and VPI% of the diseased and healthy mothers differed significantly. The most common oral pathogens were P. intermedia/nigrescens and A. actinomycetemcomitans. The children of healthy mothers harboured pathogens less frequently than the children of diseased mothers. The sharing of P. intermedia/nigrescens was more frequent (5 families) than A. actinomycetemcomitans (2 families).Conclusion.  Maternal indicators, such as periodontitis, hygiene habits, and periodontal microflora are risk factors for childhood periodontal diseases, and might be predictive of future childhood and adolescent periodontitis.
Both genes in the Marinomonas mediterranea lodAB operon are required for the expression of the antimicrobial protein lysine oxidase
Authors: Gómez Daniel , Lucas‐Elío Patricia , Solano Francisco , Sanchez‐Amat Antonio 
Published: December 2009

SummaryThe melanogenic marine bacterium Marinomonas mediterranea synthesizes a novel antimicrobial protein (LodA) with lysine‐epsilon oxidase activity (EC 1.4.3.20). Homologues to LodA have been detected in several Gram‐negative bacteria, where they are involved in biofilm development. Adjacent to lodA is located a second gene, lodB, of unknown function. This genomic organization is maintained in all the microorganisms containing homologues to these genes. In this work we show that lodA and lodB constitute an operon. Western blot analysis and enzymatic determinations revealed that LodA is secreted to the external medium when the culture reaches the stationary phase. LodB, on the other hand, has only been detected inside cells, but it is not secreted. The expression of the lysine‐epsilon oxidase (LOD) activity in M. mediterranea requires functional copies of both genes since mutants lacking either lodA or lodB do not show any LOD activity. The active form of LodA containing the quinonic cofactor is intracellularly generated in a process that takes place only in the presence of LodB, suggesting that the latter is involved in this process. Moreover, in the absence of one of the proteins, the stability of the partner protein is compromised leading to a marked decrease in its cellular levels.
The role of configuration and coupling in autoregulatory gene circuits
Authors: Wu Kang , Rao Christopher V. 
Published: December 2009

SummaryAutoregulatory gene circuits can be physically encoded within the genome in a number of different configurations. By physical encoding, we mean the orientation and relative proximity of the genes within the circuit. In this work, we quantified the behaviour of an inducible, negatively autoregulated gene circuit arranged in different transcriptional configurations using the tetRA circuit from Tn10 as our basis. Mathematical modelling predicted that circuits arranged in configurations where the expression of the transcription factor is decoupled from its target genes afforded more flexibility relative to configurations where expression is coupled. We found that these decoupled configurations reduced the concentration of transcription factor needed to regulate inducible expression from the circuit. As lower concentrations of transcription factor were required, these decoupled configurations could also be activated at much lower concentrations of the inducer. We experimentally validated these predictions in Escherichia coli by comparing the response of synthetic circuits based on the tetRA circuit arranged in different configurations. Collectively, these results provide one example of how the arrangement of a gene circuit within the genome can affect its behaviour.
Borrelia burgdorferi locus BB0795 encodes a BamA orthologue required for growth and efficient localization of outer membrane proteins
Authors: Lenhart Tiffany R. , Akins Darrin R. 
Published: December 2009

SummaryThe outer membrane (OM) of the pathogenic diderm spirochete, Borrelia burgdorferi, contains integral β‐barrel outer membrane proteins (OMPs) in addition to its numerous outer surface lipoproteins. Very few OMPs have been identified in B. burgdorferi, and the protein machinery required for OMP assembly and OM localization is currently unknown. Essential OM BamA proteins have recently been characterized in Gram‐negative bacteria that are central components of an OM β‐barrel assembly machine and are required for proper localization and insertion of bacterial OMPs. In the present study, we characterized a putative B. burgdorferi BamA orthologue encoded by open reading frame bb0795. Structural model predictions and cellular localization data indicate that the B. burgdorferi BB0795 protein contains an N‐terminal periplasmic domain and a C‐terminal, surface‐exposed β‐barrel domain. Additionally, assays with an IPTG‐regulatable bb0795 mutant revealed that BB0795 is required for B. burgdorferi growth. Furthermore, depletion of BB0795 results in decreased amounts of detectable OMPs in the B. burgdorferi OM. Interestingly, a decrease in the levels of surface‐exposed lipoproteins was also observed in the mutant OMs. Collectively, our structural, cellular localization and functional data are consistent with the characteristics of other BamA proteins, indicating that BB0795 is a B. burgdorferi BamA orthologue.
Two CDC42 paralogues modulate Cryptococcus neoformans thermotolerance and morphogenesis under host physiological conditions
Authors: Ballou Elizabeth R. , Nichols Connie B. , Miglia Kathleen J. , Kozubowski Lukasz , Alspaugh J. Andrew 
Published: December 2009

SummaryThe precise regulation of morphogenesis is a key mechanism by which cells respond to a variety of stresses, including those encountered by microbial pathogens in the host. The polarity protein Cdc42 regulates cellular morphogenesis throughout eukaryotes, and we explore the role of Cdc42 proteins in the host survival of the human fungal pathogen Cryptococcus neoformans. Uniquely, C. neoformans has two functional Cdc42 paralogues, Cdc42 and Cdc420. Here we investigate the contribution of each paralogue to resistance to host stress. In contrast to non‐pathogenic model organisms, C. neoformans Cdc42 proteins are not required for viability under non‐stress conditions but are required for resistance to high temperature. The paralogues play differential roles in actin and septin organization and act downstream of C. neoformans Ras1 to regulate its morphogenesis sub‐pathway, but not its effects on mating. Cdc42, and not Cdc420, is upregulated in response to temperature stress and is required for virulence in a murine model of cryptococcosis. The C. neoformans Cdc42 proteins likely perform complementary functions with other Rho‐like GTPases to control cell polarity, septin organization and hyphal transitions that allow survival in the environment and in the host.
Staphylococcus intermediusbinding to immobilized fibrinogen, fibronectin and cytokeratinin vitro
Authors: Schmidt Vanessa , Nuttall Tim , Fazakerley Jennie , McEwan Neil 
Published: December 2009

AbstractBacterial adhesion is a key step in colonization of the skin.Staphylococcus intermediusadheres strongly to canine and feline corneocytes, and adhesion is greater to corneocytes from dogs affected with atopic dermatitis, but comparatively little is known about adhesion‐receptor interaction compared toS. aureus. The aim of this study was to compare the binding ofS. intermediusisolates from healthy (n = 21) and atopic dogs (n = 33) to immobilized human fibronectin and epidermal cytokeratin and canine fibrinogenin vitro.Staphylococcus intermediusand the positive controlS. aureusP1 exhibited concentration‐dependent binding to all three protein layers. The negative controlS. aureusNewman strain andS. hominisdid not bind. The majority ofS. intermediusisolates adhered strongly, and there was no significant difference between isolates from atopic and healthy dogs or from lesional or nonlesional skin of atopic dogs (fibronectinP = 0.971 and 0.837; fibrinogenP = 0.811 and 0.564; cytokeratinP = 0.409 and 0.564). These results suggest thatS. intermediusmay possess specific microbial components recognizing adhesive matrix molecules, likeS. aureus, that bind to the substrates used in this study. Adherence and therefore colonization and infection in canine atopic dermatitis, however, are more likely to be related to host factors rather than the possession of specific virulence factors.
Canine hair‐follicle keratinocytes enriched with bulge cells have the highly proliferative characteristic of stem cells
Authors: Kobayashi Tetsuro , Shimizu Atsushi , Nishifuji Koji , Amagai Masayuki , Iwasaki Toshiroh , Ohyama Manabu 
Published: December 2009

AbstractHomeostasis of the epidermis and skin appendages is maintained by tissue‐specific stem cells. In mice and humans, two populations of epithelial stem cells have been identified: one in the basal layer of the interfollicular epidermis and another in the bulge area of hair follicles. However, our understanding of canine epithelial stem cells is extremely limited. In this study, in vitro colony‐forming assays were performed to locate highly proliferative keratinocytes in canine skin. Their phenotypic resemblance to epithelial stem cells in other species was also assessed. When equal numbers of epidermal or hair‐follicle keratinocytes were cultured, colonies derived from follicular keratinocytes were significantly larger both in total numbers and size, than those derived from epidermal keratinocytes. In addition, immunoreactivity for CD34, a putative bulge stem‐cell marker in the mouse, was predominantly detected in follicular keratinocytes. Thus in dogs, follicular keratinocytes were distinct from epidermal keratinocytes in proliferative capacity and CD34 expression. Using microdissection, highly proliferative keratinocytes were located within the middle portion of hair follicles, including the bulge area. Immunohistochemical study revealed that keratin 15, an established marker of bulge stem cells in mice and humans, was also predominantly expressed in the canine bulge area. Flow cytometry analysis revealed high numbers of keratin‐15‐positive cells in the highly proliferative keratinocyte compartment. Of note, keratin 15high cells possessed the phenotypic characteristics of putative stem cells. This study represents the first in vitro identification and isolation of highly proliferative canine keratinocytes, which represent candidate epithelial stem cells.
Advances in the pathogenesis of canine leishmaniosis: epidemiologic and diagnostic implications
Authors: Saridomichelakis Manolis N. 
Published: December 2009

AbstractCanine leishmaniosis caused byLeishmania infantum(Syn.L. chagasi) is an important zoonosis with a complex pathogenesis. Parasite transmission occurs via female sandflies that inject promastigotes into the skin of the host. The interaction between the parasite and skin immune system is influenced by the repeated infectious bites and the simultaneous intradermal injection of sandfly saliva. Amastigotes are transported via infected macrophages to the regional lymph nodes and finally dissemination may occur. The outcome of the infection depends on host factors (genetic background, cell‐mediated and humoral immune response, cytokine milieu, concurrent diseases) and parasite virulence. Resistance may be breed‐associated; it is characterized by low to undetectable antibody production and effective cell‐mediated immunity, and is orchestrated by cytokines such as interleukin‐2, interferon‐gamma and tumour necrosis factor‐alpha. Susceptibility may be genetically determined or acquired (advanced age, concurrent diseases); in these dogs, parasite multiplication goes unrestricted and overproduction of specific and nonspecific antibodies occurs, leading to multiple organ pathology. Resistance or susceptibility is not an all‐or‐nothing phenomenon and many intermediate phenotypes may be found. From a diagnostic point of view, although clinical cases are readily identified using microscopy and serology, investigation should not stop at this point and an extensive search for underlying diseases is advised, especially in aged dogs. Conversely, microscopy and conventional serology are frequently negative in asymptomatic infected dogs; to identify such dogs, polymerase chain reaction, evaluation of cutaneous delayed‐type hypersensitivity,in vitrolymphocyte proliferation test toLeishmaniaantigen, and Western blotting may be employed.
Colonization and infection of the human host by staphylococci: adhesion, survival and immune evasion
Authors: Foster Timothy J. 
Published: December 2009

AbstractThe natural habitat of Staphylococcus aureus in humans is the moist squamous epithelium of the anterior nares. Several bacterial surface proteins are implicated in promoting adhesion to desquamated epithelial cells. Clumping factor B (ClfB) and iron‐regulated surface determinant A both promote nasal colonization in rodent models, and in the case of ClfB, humans. One of the ligands involved in adhesion is cytokeratin 10. Reduction in nasal colonization can be achieved by active and passive immunization. S. aureus is well endowed with secreted and surface components that compromise innate immune responses, particularly the function of neutrophils. S. aureus secretes proteins that reduce migration of neutrophils from the bloodstream to the site of infection by impeding diapedesis and receptors for chemotactic molecules. Several secreted proteins interfere with complement C3 and C5 convertases, thus reducing the level of C3b opsonin and the chemotactic peptide C5a. Host proteases are recruited to the cell surface to enhance destruction of opsonic C3b and IgG. Surface components ClfA, protein A and polysaccharide capsule compromise the recognition of opsonins on the bacterial cell surface. If engulfed by neutrophils the intracellular bacterium can resist reactive oxygen intermediates, nitric oxide radicals, defensin peptides and bactericidal proteins. A prior infection by S. aureus does not induce complete protective immunity. This could be due to immunosuppression caused by expression of superantigen proteins that disrupt normal activation of T cells and B cells during antigen presentation. By studying the molecular pathogenesis of S. aureus infections markers might be found for investigating S. pseudintermedius infections of dogs.