bluuebunny/crossref_metadata_2025 huggingface dataset:
Season of burn and nutrient losses in a longleaf pine ecosystem
Authors: Boring L. R. , Hendricks J. J. , Wilson C. A. , Mitchell R. J.
Published: December 2004

Fire regulates the structure and function of longleaf pine ecosystems, including potential nutrient controls on productivity, forest floor and groundcover nutrient pools, and nutrient availability. Little is known about comparative influences of seasonality of fire, litter types, and mass on N and P balance and soil processes in longleaf pine ecosystems. This study primarily addresses the hypothesis that nutrient volatilization during growing season burning, due to combustion of live biomass, exceeds losses from winter burning of standing dead plant litter. Summer and winter burns were conducted experimentally in different groundcover types with ambient, double-ambient and no litter loadings to contrast 2–3 years of litter accumulation with very low and high fuels. As a comparison, the seasonal burns were repeated with fuel and temperature measurements on sites that had actual fuel accumulations ranging from 1 to 3 years following the last fire. Peak fire temperatures and duration of burning were similar, but with high variation across groundcover types and seasons due to variation in fuel moisture content. The highest pine litter loadings produced maximum mineral soil/litter interface temperatures that never exceeded 700°C. Groundcovers without pine litter burned incompletely and with low temperatures. Biomass and N content were greater in summer groundcover than winter groundcover, and were greater in wiregrass than old-field groundcover. More N was lost from growing season burning as biomass had higher N in green foliage at that time. With ambient litter loadings, mass losses were 88–94% of total litter and groundcover. Percentages of N lost were comparable (80–90% across all groundcovers and seasons), but amounts of N lost were below that estimated to be replenished by legume N fixation and regional atmospheric deposition over a dormant season prescribed fire cycle. Net N balances with growing season fire were generally negative only if growing season burning was projected exclusively over the long-term. P content was not significantly different among groundcovers, but summer standing stocks were higher than winter. No P losses were detected with any experimental treatments and, following burning, all P was returned to soil pools, attributable to soil surface temperatures remaining largely below 700°C. We conclude that frequent, dormant season, or even variable season burning should not seriously deplete long-term nitrogen balance of longleaf pine ecosystems.
Living with fire: homeowner assessment of landscape values and defensible space in Minnesota and Florida, USA
Authors: Nelson Kristen C. , Monroe Martha C. , Johnson Jayne Fingerman , Bowers Alison
Published: December 2004

Homeowners’ preferences for vegetation and defensible space near their homes were documented for wildfire-prone areas in Florida and Minnesota (USA) through 80 in-depth interviews and home site visits. The dominant preference for ‘natural’ landscapes was articulated as valuing vegetated views, wildlife, recreation, quiet, solitude, and privacy. Homeowners recognized wildfire risk but varied in their perceptions of effective wildfire prevention measures and willingness to take actions to reduce their risk. Most supported prescribed burns, especially if fire experts who understand the local ecology and fire behavior conduct the burns.
Site environment characterization of downed woody fuels in the Rincon Mountains, Arizona: regression tree approach
Authors: Sánchez-Flores Erick , Yool Stephen R.
Published: December 2004

Characterization of forest fuels is key to successful implementation of any fire management system. Great strides have been made in the characterization of forest canopy fuels by the use of remote sensing technology. Remote sensing of surface fuels is, however, limited by the physical intervention of the overlaying canopy. This limitation underscores the importance of exploring alternative approaches that relate site environment characteristics to the production and accumulation of understory fuels. This study predicts downed woody fuel loadings based on variables such as topography, fire history, and vegetation type in the forested area of the Rincon Mountains in southern Arizona. We used classification and regression trees (CART) to make these predictions. Results show that fine woody fuel loadings are predicted best by vegetation type and slope. Coarse woody fuels are predicted best by differences in elevation.
Neurofibromatosis 2 (NF2) tumor suppressor merlin inhibits phosphatidylinositol 3-kinase through binding to PIKE-L
Authors: Rong Rong , Tang Xiaoling , Gutmann David H. , Ye Keqiang
Published: December 2004

Neurofibromatosis 2 (NF2) is a tumor suppressor, although the molecular mechanism accounting for this effect remains unknown. Here, we show that merlin exerts its activity by inhibiting phosphatidylinositol 3-kinase (PI3-kinase), through binding to PIKE-L. Wild-type merlin, but not patient-derived mutant (L64P), binds PIKE-L and inhibits PI3-kinase activity. This suppression of PI3-kinase activity results from merlin disrupting the binding of PIKE-L to PI3-kinase. In addition, merlin suppression of PI3-kinase activity as well as schwannoma cell growth is abrogated by a single PIKE-L point mutation (P187L) that cannot bind merlin but can still activate PI3-kinase. Knocking down PIKE-L with RNA interference abolishes merlin's tumor-suppressive activity. Our data support the hypothesis that PIKE-L is an important mediator of merlin growth suppression.
Microevolution and history of the plague bacillus,
Yersinia pestis
Authors: Achtman Mark , Morelli Giovanna , Zhu Peixuan , Wirth Thierry , Diehl Ines , Kusecek Barica , Vogler Amy J. , Wagner David M. , Allender Christopher J. , Easterday W. Ryan , Chenal-Francisque Viviane , Worsham Patricia , Thomson Nicholas R. , Parkhill Julian , Lindler Luther E. , Carniel Elisabeth , Keim Paul
Published: December 2004

The association of historical plague pandemics with
Yersinia pestis
remains controversial, partly because the evolutionary history of this largely monomorphic bacterium was unknown. The microevolution of
Y. pestis
was therefore investigated by three different multilocus molecular methods, targeting genomewide synonymous SNPs, variation in number of tandem repeats, and insertion of IS
100
insertion elements. Eight populations were recognized by the three methods, and we propose an evolutionary tree for these populations, rooted on
Yersinia pseudotuberculosis
. The tree invokes microevolution over millennia, during which enzootic pestoides isolates evolved. This initial phase was followed by a binary split 6,500 years ago, which led to populations that are more frequently associated with human disease. These populations do not correspond directly to classical biovars that are based on phenotypic properties. Thus, we recommend that henceforth groupings should be based on molecular signatures. The age of
Y. pestis
inferred here is compatible with the dates of historical pandemic plague. However, it is premature to infer an association between any modern molecular grouping and a particular pandemic wave that occurred before the 20th century.
The ingestion of saturated fatty acid triacylglycerols acutely affects insulin secretion and insulin sensitivity in human subjects
Authors: Manco Melania , Bertuzzi Alessandro , Salinari Serenella , Scarfone Antonino , Calvani Menotti , Greco Aldo V. , Mingrone Geltrude
Published: December 2004

To assess the effects of acute dietary saturated fat intake on glucose-induced insulin secretion rate (ISR), measured by the C-peptide deconvolution method, and on insulin clearance and sensitivity, five obese and five normal-weight women (controls) were studied after either a 100g oral butter load or a 100ml water load. At 120min after the oral load a hyperglycaemic clamp was performed over 180min. A dramatic increase of ISR occurred after butter compared with the water challenge in the controls (1305·6 (SE 124·1)v.616·1 (SE 52·5) pmol/min;P<0·01) and to a lesser degree in the obese subjects (1975·0 (SE 44·1)v.1417·5 (SE 56·0) pmol/min;P<0·05). Insulin sensitivity was impaired after butter (0·60×10−2(SE 0·11×10−2)v.2·26×10−2(SE 0·32×10−2) ml/min per kgFFMper (pmol/l);P<0·01) in the controls but not in the obese group. Insulin clearance during the clamp was reduced after butter compared with after the water load only in the controls (0·89 (SE 0·22)v.1·70 (SE 0·15) litres/min;P<0·01). The data are consistent with the hypothesis that acute excess lipid availability may lead to a compensatory elevation in glucose-induced insulin secretion as a result of the decline in insulin sensitivity and a reduced insulin clearance.
Effect of an abrupt switch from a milk-based to a fibre-based diet on gastric emptying rates in pigs: difference between origins of fibre
Authors: Boudry Gaëlle , Guérin Sylvie , Malbert Charles Henri
Published: December 2004

A characteristic dietary feature at weaning is a switch from a milk-based to plant-based diet, i.e. from a non-fibrous to a fibrous diet. The present study aimed to evaluate the effects of such an abrupt dietary switch on gastric emptying rate in pigs maintained on a milk substitute after weaning. Eighteen piglets were kept on a milk substitute for 5 weeks after weaning and were then switched to wheat-based or barley-based diets or kept on the milk substitute (six piglets per group). All piglets were fasted for 1d before the switch and daily food intake was then increased linearly to reach initial values within 3d. The gastric emptying rate was measured by γ-scintigraphy before and after the switch. Corpo-antral peristalsis was also evaluated by the use of high-frequency scintigraphic frames. The gastric emptying rate of the wheat-based diet was accelerated on days 1 to 3 after the switch, but was similar to that in the milk-substitute group thereafter. This acceleration was concomitant with an enhanced frequency of corpo-antral waves on days 2 and 3. Conversely, the gastric emptying rate of the barley-based diet tended to be enhanced on day 2, but was delayed on days 4 and 5, without any change in frequency of corpo-antral waves. We conclude that a switch from a non-fibrous to a fibrous diet alters the gastric emptying rate differently depending on the type of dietary fibre.
Dietary patterns, insulin sensitivity and adiposity in the multi-ethnic Insulin Resistance Atherosclerosis Study population
Authors: Liese Angela D. , Schulz Mandy , Moore Charity G. , Mayer-Davis Elizabeth J.
Published: December 2004

Epidemiological investigations increasingly employ dietary-pattern techniques to fully integrate dietary data. The present study evaluated the relationship of dietary patterns identified by cluster analysis with measures of insulin sensitivity (SI) and adiposity in the multi-ethnic, multi-centre Insulin Resistance Atherosclerosis Study (IRAS, 1992–94). Cross-sectional data from 980 middle-aged adults, of whom 67% had normal and 33% had impaired glucose tolerance, were analysed. Usual dietary intake was obtained by an interviewer-administered, validated food-frequency questionnaire. Outcomes included SI, fasting insulin (FI), BMI and waist circumference. The relationship of dietary patterns to log(SI+1), log(FI), BMI and waist circumference was modelled with multivariable linear regressions. Cluster analysis identified six distinct diet patterns – ‘dark bread’, ‘wine’, ‘fruits’, ‘low-frequency eaters’, ‘fries’ and ‘white bread’. The ‘white bread’ and the ‘fries’ patterns over-represented the Hispanic IRAS population predominantly from two centres, while the ‘wine’ and ‘dark bread’ groups were dominated by non-Hispanic whites. The dietary patterns were associated significantly with each of the outcomes first at the crude, clinical level (P<0·001). Furthermore, they were significantly associated with FI, BMI and waist circumference independent of age, sex, race or ethnicity, clinic, family history of diabetes, smoking and activity (P<0.004), whereas significance was lost for SI. Studying the total dietary behaviour via a pattern approach allowed us to focus both on the qualitative and quantitative dimensions of diet. The present study identified highly consistent associations of distinct dietary patterns with measures of insulin resistance and adiposity, which are risk factors for diabetes and heart disease.
Evidence for fetal programming of obesity with a focus on putative mechanisms
Authors: Wild Sarah H. , Byrne Christopher D.
Published: December 2004

Obesity is associated with insulin resistance, the metabolic syndrome (a clustering of three or more of increased waist circumference, blood pressure, fasting glucose and fasting plasma triacylglycerol levels and reduced HDL levels), and a marked increase in the risk of type 2 diabetes and CHD. The impact of obesity differs between individuals, particularly between men and women and between ethnic groups. For example, in South Asians, although overall obesity is less prevalent, central obesity and the metabolic syndrome are more prevalent than in Europeans and this pattern is associated with the development of type 2 diabetes and CHD at an earlier age. It is important to examine individual risk factors contributing to obesity because they may have a different impact in population subgroups. Many factors contribute to the aetiology of obesity and there is increasing evidence to suggest that altered early development is one such factor and is associated with abnormal fat accumulation, the metabolic syndrome and type 2 diabetes in later life. The present review presents this evidence and discusses some of the mechanisms that may be involved in the pathogenesis of the programming of obesity.
Pros and cons of L-arginine supplementation in disease
Authors: Vissers Yvonne L. J. , Debats Iris B. J. G. , Luiking Yvette C. , Jalan Rajiv , van der Hulst René R. W. J. , Dejong Cornelis H. C. , Deutz Nicolaas E. P.
Published: December 2004

The amino acid arginine and one of its metabolites NO have gathered broad attention in the last decade. Although arginine is regarded as a conditionally essential amino acid in disease, L-arginine supplementation in severe illness has not found its way into clinical practice. This might be due to the invalid interpretation of results from studies with immune-enhancing diets containing L-arginine amongst other pharmaconutrients. However, not much attention is given to research using L-arginine as a monotherapy and the possibility of the alternative hypothesis: that L-arginine supplementation is beneficial in disease. The present review will discuss data from studies in healthy and diseased animals and patients with monotherapy of L-arginine to come to an objective overview of positive and negative aspects of L-arginine supplementation in disease with special emphasis on sepsis, cancer, liver failure and wound healing.
VHL-box and SOCS-box domains determine binding specificity for Cul2-Rbx1 and Cul5-Rbx2 modules of ubiquitin ligases
Authors: Kamura Takumi , Maenaka Katsumi , Kotoshiba Shuhei , Matsumoto Masaki , Kohda Daisuke , Conaway Ronald C. , Conaway Joan Weliky , Nakayama Keiichi I.
Published: December 2004

The ECS (Elongin B/C-Cul2/Cul5-SOCS-box protein) complex is a member of a family of ubiquitin ligases that share a Cullin-Rbx module. SOCS-box proteins recruit substrates to the ECS complex and are linked to Cullin-Rbx via Elongin B/C. VHL has been implicated as a SOCS-box protein, but lacks a C-terminal sequence (downstream of the BC box) of the SOCS box. We now show that VHL specifically interacts with endogenous Cul2-Rbx1 in mammalian cells, whereas SOCS-box proteins associate with Cul5-Rbx2. We also identify LRR-1 and FEM1B as proteins that share a region of homology with VHL (the VHL box, including the BC box and downstream residues) and associate with Cul2-Rbx1. ECS complexes can thus be classified into two distinct protein assemblies, that is, those that contain a subunit with a VHL box (composed of the BC box and a downstream Cul2 box) that interacts with Cul2-Rbx1, and those that contain a subunit with a SOCS box (BC box and downstream Cul5 box) that interacts with Cul5-Rbx2. Domain-swapping analyses showed that the specificity of interaction of VHL-box and SOCS-box proteins with Cullin-Rbx modules is determined by the Cul2 and Cul5 boxes, respectively. Finally, RNAi-mediated knockdown of the Cul2-Rbx1 inhibited the VHL-mediated degradation of HIF-2α, whereas knockdown of Cul5-Rbx2 did not affect it. These data suggest that the functions of the Cul2-Rbx1 and Cul5-Rbx2 modules are distinct.
Release of initiation factors from 48S complexes during ribosomal subunit joining and the link between establishment of codon-anticodon base-pairing and hydrolysis of eIF2-bound GTP
Authors: Unbehaun Anett , Borukhov Sergei I. , Hellen Christopher U.T. , Pestova Tatyana V.
Published: December 2004

The 40S subunit in 48S complexes formed at the initiation codon of mRNA is bound to eukaryotic initiation factor (eIF) 3, eIF1, eIF1A, and an eIF2/GTP/Met-\batchmode
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ternary complex and can therefore not join a 60S subunit directly to form an 80S ribosome. We report that eIF5-induced hydrolysis of eIF2-bound GTP in 48S complexes led to release of eIF2-GDP but not eIF3 or eIF1. eIF5B did not influence factor release in the absence of 60S subunits. Therefore eIF3 and eIF1 dissociate from 40S subunits during, rather than before, the eIF5B-mediated subunit joining event. In the absence of eIF1, eIF5-stimulated hydrolysis of eIF2-bound GTP occurred at the same rate in 43S pre-initiation and 48S initiation complexes. GTP hydrolysis in 43S complexes assembled with eIF1 was much slower than in 43S or 48S complexes assembled without eIF1. Establishment of codon-anticodon base-pairing in 48S complexes relieved eIF1's inhibition. Thus, in addition to its role in initiation codon selection during 48S complex formation, eIF1 also participates in maintaining the fidelity of the initiation process at a later stage, hydrolysis of eIF2-bound GTP, by inhibiting premature GTP hydrolysis and by linking establishment of codon-anticodon base-pairing with GTP hydrolysis.
The induction of sexual development and virulence in the smut fungus Ustilago maydis depends on Crk1, a novel MAPK protein
Authors: Garrido Elia , Voß Ute , Müller Philip , Castillo-Lluva Sonia , Kahmann Regine , Pérez-Martín José
Published: December 2004

MAP kinases (mitogen-activated protein kinases) are activated by dual phosphorylation on specific threonine and specific tyrosine residues that are separated by a single residue, and the TXY activation motif is a hallmark of MAP kinases. In the fungus Ustilago maydis, which causes corn smut disease, the Crk1 protein, a kinase previously described to have roles in morphogenesis, carries a TXY motif that aligns with the TXY of MAP kinases. In this work, we demonstrate that Crk1 is activated through a mechanism that requires the phosphorylation of this motif. Our data show that Fuz7, a MAPK kinase involved in mating and pathogenesis in U. maydis, is required to activate Crk1, most likely through phosphorylation of the TXY motif. Consistently, we found that Crk1 is also required for mating and virulence. We investigated the reasons for sterility and avirulence of crk1-deficient cells, and we found that Crk1 is required for transcription of prf1, a central regulator of mating and pathogenicity in U. maydis. Crk1 belongs to a wide conserved protein group, whose members have not been previously defined as MAP kinases, although they carry TXY motifs. On the basis of our data, we propose that all of these proteins constitute a new family of MAP kinases.
The application of a monoclonal antibody to CD62L on paraffin‐embedded tissue samples in the assessment of the cutaneous T‐cell infiltrates
Authors: Magro Cynthia M. , Sachdeva Mandi P. , Crowson A. Neil , Barusevicius Alan , Baran Peter N. , Kovatich Albert J.
Published: December 2004

Background:  A reduction in the expression of the pan T‐cell markers CD7 and CD62L supports an endogenous T‐cell dyscrasia. Previously, clone availability for CD62L restricted its application to frozen tissue sections.

Materials and methods:  A nonavidin/biotin technique to examine CD3, CD62L, and CD7 in paraffin formalin‐fixed tissue in non‐neoplastic and neoplastic T‐cell infiltrates.

Results:  In the reactive group, CD62L manifested a 15 and 22% reduction in epidermal and dermal staining, respectively; there was a 42 and 31% reduction in epidermal and dermal CD7 staining. In lymphomatoid hypersensitivity, CD62L showed a 24 and 9% reduction in epidermal and dermal staining, respectively; CD7 staining demonstrated reduced staining by 70 and 66% in the epidermis and dermis. In the non‐lymphomatous endogenous T‐cell dyscrasia and lymphoma categories, an 80% diminution in CD62L and CD7 expression was seen.

Conclusions:  CD62L can be successfully applied in formalin‐fixed tissue and exhibits enhanced specificity compared to CD7 in the evaluation of cutaneous T‐cell infiltrates. Both CD62L and CD7 in paraffin‐embedded, formalin‐fixed tissue are useful diagnostic adjuncts, especially in regard to the discrimination of lymphomatoid hypersensitivity reactions from true endogenous T‐cell dyscrasia.
Cutaneous carcinosarcoma: adnexal vs. epidermal types define high‐ and low‐risk tumors. Results of a meta‐analysis
Authors: Tran Tien Anh , Muller Sigfrid , Chaudahri Prakash J. , Carlson J. Andrew
Published: December 2004

Objective:  We report four cases of cutaneous carcinosarcoma (CS) and perform a meta‐analysis of the cutaneous CS literature.

Results:  CS occurred in elderly patients (mean of 80 years) on sun‐damaged skin, and were keratotic papules of short duration. They did not recur after excision. CS exhibited basal cell carcinoma mixed with atypical fibroxanthoma cell populations. Immunophenotyping revealed vimentin+/keratin– spindle cells and vimentin–/keratin+ epithelial cells. Three cases exhibited p53 protein expression of both carcinomatous and sarcomatous components. Literature review identified 38 cases of cutaneous CS that could be broadly classified into two distinct groups. Epidermal‐derived (basal or squamous cell carcinoma epithelial component) CS arose on the sun‐damaged skin of the head and neck of elderly males (mean age 72 years) and had a 70% 5‐year disease‐free survival. In contrast, adnexal CS (spiradenocarcinoma, porocarcinoma, proliferating tricholemmal cystic carcinoma, or matrical carcinoma) occurred in younger patients (mean age 58 years), showed recent growth in a long‐standing nodule and had a 25% 5‐year disease‐free survival. Age less than 65 years, recent growth, long‐standing skin tumor, and tumor size greater than 2 cm significantly correlated with poor outcome.

Conclusions:  Cutaneous CS is an aggressive skin cancer with high risk for advanced disease. Significant risk factors exist whose identification will allow for better management of CS patients.
Pilomatrix carcinomas contain mutations in CTNNB1, the gene encoding β‐catenin
Authors: Lazar Alexander J. F. , Calonje Eduardo , Grayson Wayne , Dei Tos Angelo P. , Mihm Martin C. , Redston Mark , McKee Phillip H.
Published: December 2004

Abstract:  Mutations in β‐catenin are present in benign pilomatrixomas. β‐catenin is a downstream effector in the WNT‐signalling pathway, acting as a signal for differentiation and proliferation. Mutations in CTNNB1, the gene encoding β‐catenin, are present in a wide variety of benign and malignant neoplasms. We examined β‐catenin in a series of pilomatrix carcinomas (15 cases) by using immunohistochemistry and DNA sequencing of exon 3 from CTNNB1, and compared these to a series of benign pilomatrixomas (13 cases). All 11 pilomatrix carcinomas available for examination showed nuclear localization of β‐catenin and mutations in exon 3 similar to those demonstrated in benign pilomatrixomas. Two of 11 pilomatrix carcinomas showed significant nuclear accumulation of p53, whereas this was absent in all 13 benign pilomatrixomas. Expression of nuclear cyclin D1 was similar in both benign pilomatrixomas and pilomatrix carcinomas. Clinical follow‐up from the 15 malignant cases reported in this study and by others indicates that wide excision offers superior control of local recurrence, compared to simple excision. Immunohistochemical and molecular analysis of β‐catenin reveals that both pilomatrix carcinomas and benign pilomatrixomas harbour mutations in β‐catenin. This implies a common initial pathogenesis and is compatible with the proposition that pilomatrix carcinomas may at least on occasion arise from their benign counterparts.
Primary Cutaneous Immunocytoma Presenting with Diffuse Subclinical Involvement and Demonstrating Kappa and Lambda Light Chain Restrictions
Authors: Lorenzo C. , Breneman D.
Published: December 2004

A 37 year‐old man with primary cutaneous immunocytoma with lambda light chain restriction involving the left shoulder was treated with Rituxan with clinical resolution. Four years later, he presented with a six‐month history of diffuse asymptomatic erythema. Physical examination revealed three grouped papules on the right upper arm and an irregular sclerotic patch with slight erythema superiorly on the left shoulder at the site of the initial tumor. There was no diffuse erythema. Biopsies were obtained from a papule on the right upper arm, the sclerotic patch on the left shoulder, and clinically uninvolved skin on the right anterior thigh. All three specimens showed a variably dense, predominantly periadnexal and perivascular dermal infiltrate of plasma cells and lymphocytes. The specimen from the right arm demonstrated kappa light chain restriction. The specimen from the right thigh showed lambda light chain restriction. Physical examination six weeks later demonstrated mottled erythema on the anterior thighs. Two biopsies were obtained from the right thigh. One showed immunocytoma. The other was unremarkable. The patient's primary cutaneous immunocytoma demonstrated two unusual findings: (1) histologic presence of tumor in clinically uninvolved and minimally involved skin; and (2) the presence of two distinct monoclonal populations.
Virus‐Associated Trichodysplasia Spinulosa
Authors: Wyatt AJ , Sachs D , Began D , Shia J , Delgado R , Busam KJ
Published: December 2004

Background:  Virus‐associated trichodysplasia spinulosa (VATD) is a relatively new entity associated with a distinctive histologic picture of distended follicles with excessive production of inner root sheath material. Only two patients have thus far been reported. Both had developed the condition after a kidney transplant. Observation: We report two additional cases of VATD. One is a nineteen year‐old man with a history of acute lymphocytic leukemia, who developed a papular facial eruption as well as madarosis. The other is a nine year‐old boy, who presented with facial papules after a kidney transplant. Histologic examination of both cases reveals characteristic findings for trichodysplasia spinulosa, but also indicates a spectrum of histologic alterations. Ultrastructural studies confirm the presence of a variable number of intranuclear viral particles. Conclusions: Our cases illustrate the histologic spectrum seen in association with VATD. The severity of histologic alterations corresponds to the viral load seen by electron microscopy. This report documents for the first time that VATD can be found in patients without a solid organ transplant. Increased awareness of the distinct histologic picture associated with VATD will likely lead to more frequent diagnosis of this under‐recognized entity.
Personnel Selection with Top‐Score‐Referenced Banding: On the Inappropriateness of Current Procedures
Authors: Bobko Philip , Roth Philip L.
Published: December 2004

The method of selecting among job applicants using statistically based banding has been proposed over the last 10 years as a way to increase workforce diversity. The method continues to be reviewed by academics and considered by practitioners. Although the goal of increasing workforce diversity is important, statistical banding of scores remains controversial. We present a set of unique, statistically and theoretically based criticisms of a form of banding (top‐score‐referenced banding) that is widely used in hundreds of jobs in the public sector throughout the United States. We suggest that even within the premises of such banding, the wrong formula is used to estimate the standard error of measurement and standard error of the difference. One consequence is that too many individuals are labeled as essentially equal with respect to test scores. A related consequence is that test scores within a single band are statistically different and should therefore be treated as such for selection purposes. A more logically and statistically defensible procedure for responding to diversity concerns is to continue to attend to adverse impact issues at each step of the recruiting and test development process.
Job Type and Recruiters' Inferences of Applicant Personality Drawn from Resume Biodata: Their Relationships with Hiring Recommendations
Authors: Cole Michael S. , Feild Hubert S. , Giles William F. , Harris Stanley G.
Published: December 2004

Using data collected from 244 recruiters who reviewed resumes and made dispositional inferences and hiring recommendations for 122 entry‐level job applicants, we found that type of job opening (Holland's Conventional vs. Enterprising jobs) moderated relationships between recruiter inferences of applicant personality traits and recruiter judgments of applicant employability. Results showed Conscientiousness correlated with employability ratings for Conventional jobs (e.g., accounting) while extraversion was most associated with employability ratings for Enterprising jobs (e.g., marketing).
Rubella virus infection dysregulates the pattern of p63 expression
Authors: BUZÁS KRISZTINA , MICZÁK ANDRÁS , DEGRÉ MIKLOS , MEGYERI KLÁRA
Published: December 2004

The effect of rubella virus (RV) on the expression of the p63 isoforms was investigated in Vero cells. The levels of all the TAp63 isoforms were elevated, while the expression of a ∼73 kDa isoform corresponding to ΔNp63α was downregulated in Vero cells infected with the To‐336 strain of RV. A ∼66 kDa isoform corresponding to TAp63β was the predominant protein species in RV‐infected cells. Semi‐quantitative end‐point dilution RT‐PCR analysis, with TAp63β isoform‐specific primers, detected a 4‐fold rise in the TAp63β mRNA level following virus infection. Taken together, our data demonstrate that RV infection alters the stoichiometric ratio of the p63 isoforms. The dysregulated pattern of p63 expression observed in RV‐infected cells may represent a mechanism whereby RV exerts its pro‐apoptotic effect.
Resource Letter GP-1: Granular physics or nonlinear dynamics in a sandbox
Authors: Kakalios James
Published: December 2004

This Resource Letter provides a guide to the literature on the statics and dynamics of granular media. Journal article and book references are provided for the following topics: Packing, Angle of Repose, Avalanches and Granular Flow, Hoppers and Jamming, Vertically Vibrated Induced Phenomena, Avalanche Stratification, and Axial Segregation.
A Sensor of the Two-Component System CpxA Affects Expression of the Type III Secretion System through Posttranscriptional Processing of InvE
Authors: Mitobe Jiro , Arakawa Eiji , Watanabe Haruo
Published: December 2004

The chief function of the Cpx two-component system is perceiving various cell envelope stresses, but CpxR is also known to regulate the expression of the type III secretion system (TTSS) of
Shigella sonnei
through transcription of the primary regulator
virF
. Here, we have isolated novel
cpxA
mutants that exhibited decreased TTSS expression from
Escherichia coli
HW1273, which carries the virulence plasmid of
S. sonnei
. The
cpxA
deletion strain of HW1273 expressed β-galactosidase activity levels from the
virF-lacZ
fusion similar to those of HW1273. However, the second regulator InvE (VirB) and the TTSS component IpaB proteins were apparently expressed at a low level. In the
cpxA
strain, β-galactosidase activity levels from the
invE-lacZ
transcriptional fusion remained similar to those of HW1273, whereas the β-galactosidase activity level from the translational fusion of
invE-lacZ
was reduced to 21% of that of HW1273. Therefore, the deletion of the
cpxA
gene influenced TTSS expression chiefly at the posttranscriptional processing of InvE. In addition, the
cpxA
deletion strain of
S. sonnei
showed the same phenotype. These results indicate that the Cpx two-component system is involved in virulence expression through posttranscriptional processing of the regulatory protein InvE, a novel feature of the Cpx two-component system in posttranscriptional processing and virulence expression of
Shigella
.
Identification and Characterization of a Regulatory Sequence Recognized by
Mycobacterium tuberculosis
Persistence Regulator MprA
Authors: He Hongjun , Zahrt Thomas C.
Published: December 2004

Establishment and maintenance of persistent, latent infection by
Mycobacterium tuberculosis
are dependent on expression of the
mprA-mprB
regulatory system. Previously, MprA and MprB were shown to participate in phosphotransfer reactions characteristic of two-component signaling systems. To begin identifying downstream effector genes regulated by
mprA-mprB
during persistent stages of infection, a search for the regulatory sequence(s) recognized by response regulator MprA was carried out. Here, evidence is presented demonstrating that MprA recognizes a 19-bp sequence comprising two loosely conserved 8-bp direct repeat subunits separated by 3 nucleotides. This motif, termed the MprA box, is found upstream of the
mprA
coding sequence and that of downstream gene
pepD
(
Rv0983
). Protein phosphorylation was not required for binding to this DNA sequence by MprA in vitro; however, phosphorylation enhanced DNA binding by MprA and was required for the regulation of
mprA
and
pepD
by MprA in vivo. Binding of MprA to the MprA box was dependent on conserved nucleotides contained within repeat subunits and on the spacer length separating these repeats. In addition, recognition of this sequence proceeded via tandem binding of two monomers of MprA. Identification of the genetic determinants regulated by MprA will ultimately enhance our understanding of the mechanisms utilized by
M. tuberculosis
to undergo latency.
Inactivation of
swmA
Results in the Loss of an Outer Cell Layer in a Swimming
Synechococcus
Strain
Authors: McCarren J. , Heuser J. , Roth R. , Yamada N. , Martone M. , Brahamsha B.
Published: December 2004

The mechanism of nonflagellar swimming of marine unicellular cyanobacteria remains poorly understood. SwmA is an abundant cell surface-associated 130-kDa glycoprotein that is required for the generation of thrust in
Synechococcus
sp. strain WH8102. Ultrastructural comparisons of wild-type cells to a mutant strain in which the gene encoding SwmA has been insertionally inactivated reveal that the mutant lacks a layer external to the outer membrane. Cryofixation and freeze-substitution are required for the preservation of this external layer. Freeze fracturing and etching reveal that this additional layer is an S-layer. How the S-layer might function in motility remains elusive; however, this work describes an ultrastructural component required for this unique type of swimming. In addition, the work presented here describes the envelope structure of a model swimming cyanobacterium.
The Elastic Properties of the
Caulobacter crescentus
Adhesive Holdfast Are Dependent on Oligomers of
N
-Acetylglucosamine
Authors: Li Guanglai , Smith Christopher S. , Brun Yves V. , Tang Jay X.
Published: December 2004

The aquatic bacterium
Caulobacter crescentus
attaches to solid surfaces through an adhesive holdfast located at the tip of its polar stalk, a thin cylindrical extension of the cell membrane. In this paper, the elastic properties of the
C. crescentus
stalk and holdfast assembly were studied by using video light microscopy. In particular, the contribution of oligomers of
N
-acetylglucosamine (GlcNAc) to the elasticity of holdfast was examined by lysozyme digestion.
C. crescentus
cells attached to a surface undergo Brownian motion while confined effectively in a harmonic potential. Mathematical analysis of such motion enabled us to determine the force constant of the stalk-holdfast assembly, which quantifies its elastic properties. The measured force constant exhibits no dependence on stalk length, consistent with the theoretical estimate showing that the stalk can be treated as a rigid rod with respect to fluctuations of the attached cells. Therefore, the force constant of the stalk-holdfast assembly can be attributed to the elasticity of the holdfast. Motions of cells in a rosette were found to be correlated, consistent with the elastic characteristics of the holdfast. Atomic force microscopy analysis indicates that the height of a dried (in air) holdfast is approximately one-third of that of a wet (in water) holdfast, consistent with the gel-like nature of the holdfast. Lysozyme, which cleaves oligomers of GlcNAc, reduced the force constant to less than 10% of its original value, consistent with the polysaccharide gel-like nature of the holdfast. These results also indicate that GlcNAc polymers play an important role in the strength of the holdfast.
Transcriptional Control by A-Factor of Two Trypsin Genes in
Streptomyces griseus
Authors: Kato Jun-ya , Chi Won-Jae , Ohnishi Yasuo , Hong Soon-Kwang , Horinouchi Sueharu
Published: December 2004

AdpA is the key transcriptional activator for a number of genes of various functions in the A-factor regulatory cascade in
Streptomyces griseus
, forming an AdpA regulon. Trypsin-like activity was detected at a late stage of growth in the wild-type strain but not in an A-factor-deficient mutant. Consistent with these observations, two trypsin genes,
sprT
and
sprU
, in
S. griseus
were found to be members of the AdpA regulon; AdpA activated the transcription of both genes by binding to the operators located at about −50 nucleotide positions with respect to the transcriptional start point. The transcription of
sprT
and
sprU,
induced by AdpA, was most active at the onset of sporulation. Most trypsin activity exerted by
S. griseus
was attributed to SprT, because trypsin activity in an
sprT
-disrupted mutant was greatly reduced but that in an
sprU
-disrupted mutant was only slightly reduced. This was consistent with the observation that the amount of the
sprT
mRNA was much greater than that of the
sprU
transcript. Disruption of both
sprT
and
sprU
(mutant Δ
sprTU
) reduced trypsin activity to almost zero, indicating that no trypsin genes other than these two were present in
S. griseus
. Even the double mutant Δ
sprTU
grew normally and developed aerial hyphae and spores over the same time course as the wild-type strain.
Role of the Two Catalytic Domains of DSR-E Dextransucrase and Their Involvement in the Formation of Highly α-1,2 Branched Dextran
Authors: Fabre Emeline , Bozonnet Sophie , Arcache Audrey , Willemot René-Marc , Vignon Michel , Monsan Pierre , Remaud-Simeon Magali
Published: December 2004

The
dsrE
gene from
Leuconostoc mesenteroides
NRRL B-1299 was shown to encode a very large protein with two potentially active catalytic domains (CD1 and CD2) separated by a glucan binding domain (GBD). From sequence analysis, DSR-E was classified in glucoside hydrolase family 70, where it is the only enzyme to have two catalytic domains. The recombinant protein DSR-E synthesizes both α-1,6 and α-1,2 glucosidic linkages in transglucosylation reactions using sucrose as the donor and maltose as the acceptor. To investigate the specific roles of CD1 and CD2 in the catalytic mechanism, truncated forms of
dsrE
were cloned and expressed in
Escherichia coli
. Gene products were then small-scale purified to isolate the various corresponding enzymes. Dextran and oligosaccharide syntheses were performed. Structural characterization by
13
C nuclear magnetic resonance and/or high-performance liquid chromatography showed that enzymes devoid of CD2 synthesized products containing only α-1,6 linkages. On the other hand, enzymes devoid of CD1 modified α-1,6 linear oligosaccharides and dextran acceptors through the formation of α-1,2 linkages. Therefore, each domain is highly regiospecific, CD1 being specific for the synthesis of α-1,6 glucosidic bonds and CD2 only catalyzing the formation of α-1,2 linkages. This finding permitted us to elucidate the mechanism of α-1,2 branching formation and to engineer a novel transglucosidase specific for the formation of α-1,2 linkages. This enzyme will be very useful to control the rate of α-1,2 linkage synthesis in dextran or oligosaccharide production.
Timing and Localization of Rhamnolipid Synthesis Gene Expression in
Pseudomonas aeruginosa
Biofilms
Authors: Lequette Yannick , Greenberg E. P.
Published: December 2004

Pseudomonas aeruginosa
biofilms can develop mushroom-like structures with stalks and caps consisting of discrete subpopulations of cells. Self-produced rhamnolipid surfactants have been shown to be important in development of the mushroom-like structures. The quorum-sensing-controlled
rhlAB
operon is required for rhamnolipid synthesis. We have introduced an
rhlA-gfp
fusion into a neutral site in the
P. aeruginosa
genome to study
rhlAB
promoter activity in rhamnolipid-producing biofilms. Expression of the
rhlA-gfp
fusion in biofilms requires the quorum-sensing signal butanoyl-homoserine lactone, but other factors are also required for expression. Early in biofilm development
rhlA-gfp
expression is low, even in the presence of added butanoyl-homoserine lactone. Expression of the fusion becomes apparent after microcolonies with a depth of >20 μm have formed and, as shown by differential labeling with
rfp
or fluorescent dyes,
rhlA-gfp
is preferentially expressed in the stalks rather than the caps of mature mushrooms. The
rhlA-gfp
expression pattern is not greatly influenced by addition of butanoyl-homoserine lactone to the biofilm growth medium. We propose that rhamnolipid synthesis occurs in biofilms after stalks have formed but prior to capping in the mushroom-like structures. The differential expression of
rhlAB
may play a role in the development of normal biofilm architecture.
Localization of MreB inRhodobacter sphaeroidesunder Conditions Causing Changes in Cell Shape and Membrane Structure
Authors: Slovak Peter M. , Wadhams George H. , Armitage Judith P.
Published: December 2004

MreB is thought to be a bacterial actin homolog that defines the morphology of rod-shaped bacteria.Rhodobacter sphaeroideschanges shape, from a rod to coccobacillus, and undergoes extensive cytoplasmic membrane invagination when it switches from aerobic to photoheterotrophic growth. The role of MreB in definingR. sphaeroidesshape was therefore investigated. Attempts at deleting or insertionally inactivatingmreBwere unsuccessful under all growth conditions. Immunofluorescence microscopy showed MreB localized to mid-cell in elongating cells under both aerobic and photoheterotrophic conditions. Three-dimensional reconstruction showed that MreB formed a ring at mid-cell. MreB remained at mid-cell as septation began but localized to new sites in the daughter cells before the completion of septation. MreB localized to putative septation sites in cephalexin-treated filamentous cells. Genomic single-copymreBwas replaced withgfp-mreB, and green fluorescent protein (GFP)-MreB localized in the same pattern, as seen with immunofluorescence microscopy. Some of the cells expressing GFP-MreB were abnormal, principally displaying an increase in cell width, suggesting that the fusion was not fully functional in all cells. GFP-MreB localized to swellings at mid-cell in cells treated with the penicillin-binding protein 2 inhibitor amdinocillin. These data suggest that MreB is essential inR. sphaeroides, performing a role at mid-cell in elongating cells, and in early septation, putatively in the cytoplasmic control of the peptidoglycan synthetic complexes.
Comparative Analysis of the Development of Swarming Communities ofBacillus subtilis168 and a Natural Wild Type: Critical Effects of Surfactin and the Composition of the Medium
Authors: Julkowska Daria , Obuchowski Michal , Holland I. Barry , Séror Simone. J.
Published: December 2004

The natural wild-typeBacillus subtilisstrain 3610 swarms rapidly on the synthetic B medium in symmetrical concentric waves of branched dendritic patterns. In a comparison of the behavior of the laboratory strain 168 (trp) on different media with that of 3610, strain 168 (trp), which does not produce surfactin, displayed less swarming activity, both qualitatively (pattern formation) and in speed of colonization. On E and B media, 168 failed to swarm; however, with the latter, swarming was arrested at an early stage of development, with filamentous cells and rafts of cells (characteristic of dendrites of 3610) associated with bud-like structures surrounding the central inoculum. In contrast, strain 168 apparently swarmed efficiently on Luria-Bertani (LB) agar, colonizing the entire plate in 24 h. However, analysis of the intermediate stages of development of swarms on LB medium demonstrated that, in comparison with strain 3610, initiation of swarming of 168 (trp) was delayed and the greatly reduced rate of expansion of the swarm was uncoordinated, with some regions advancing faster than others. Moreover, while early stages of swarming in 3610 are accompanied by the formation of large numbers of dendrites whose rapid advance involves packs of cells at the tips, strain 168 advanced more slowly as a continuous front. Whensfp+was inserted into the chromosome of 168 (trp) to reestablish surfactin production, many features observed with 3610 on LB medium were now visible with 168. However, swarming of 168 (sfp+) still showed some reduced speed and a distinctive pattern compared to swarming of 3610. The results are discussed in terms of the possible role of surfactin in the swarming process and the different modes of swarming on LB medium.
Identification of an Amino Acid Position That Determines the Substrate Range of Integral Membrane Alkane Hydroxylases
Authors: van Beilen Jan B. , Smits Theo H. M. , Roos Franz F. , Brunner Tobias , Balada Stefanie B. , Röthlisberger Martina , Witholt Bernard
Published: December 2004

Selection experiments and protein engineering were used to identify an amino acid position in integral membrane alkane hydroxylases (AHs) that determines whether long-chain-length alkanes can be hydroxylated by these enzymes. First, substrate range mutants of the
Pseudomonas putida
GPo1 and
Alcanivorax borkumensis
AP1 medium-chain-length AHs were obtained by selection experiments with a specially constructed host. In all mutants able to oxidize alkanes longer than C
13
, W55 (in the case of
P. putida
AlkB) or W58 (in the case of
A. borkumensis
AlkB1) had changed to a much less bulky amino acid, usually serine or cysteine. The corresponding position in AHs from other bacteria that oxidize alkanes longer than C
13
is occupied by a less bulky hydrophobic residue (A, V, L, or I). Site-directed mutagenesis of this position in the
Mycobacterium tuberculosis
H37Rv AH, which oxidizes C
10
to C
16
alkanes, to introduce more bulky amino acids changed the substrate range in the opposite direction; L69F and L69W mutants oxidized only C
10
and C
11
alkanes. Subsequent selection for growth on longer alkanes restored the leucine codon. A structure model of AHs based on these results is discussed.