bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetic diversity and virulence potential of environmental
Vibrio cholerae
population in a cholera-endemic area
Authors: Faruque Shah M. , Chowdhury Nityananda , Kamruzzaman M. , Dziejman Michelle , Rahman M. Hasibur , Sack David A. , Nair G. Balakrish , Mekalanos John J.
Published: February 2004

To understand the evolutionary events and possible selection mechanisms involved in the emergence of pathogenic
Vibrio cholerae
, we analyzed diverse strains of
V. cholerae
isolated from environmental waters in Bangladesh by direct enrichment in the intestines of adult rabbits and by conventional laboratory culture. Strains isolated by conventional culture were mostly (99.2%) negative for the major virulence gene clusters encoding toxin-coregulated pilus (TCP) and cholera toxin (CT) and were nonpathogenic in animal models. In contrast, all strains selected in rabbits were competent for colonizing infant mice, and 56.8% of these strains carried genes encoding TCP alone or both TCP and CT. Ribotypes of toxigenic O1 and O139 strains from the environment were similar to pandemic strains, whereas ribotypes of non-O1 non-O139 strains and TCP
-
nontoxigenic O1 strains diverged widely from the seventh pandemic O1 and the O139 strains. Results of this study suggest that (
i
) the environmental
V. cholerae
population in a cholera-endemic area is highly heterogeneous, (
ii
) selection in the mammalian intestine can cause enrichment of environmental strains with virulence potential, (
iii
) pathogenicity of
V. cholerae
involves more virulence genes than currently appreciated, and (
iv
) most environmental
V. cholerae
strains are unlikely to attain a pandemic potential by acquisition of TCP and CT genes alone. Because most of the recorded cholera pandemics originated in the Ganges Delta region, this ecological setting presumably favors extensive genetic exchange among
V. cholerae
strains and thus promotes the rare, multiple-gene transfer events needed to assemble the critical combination of genes required for pandemic spread.
Development of a specific system for targeting protein to metallophilic macrophages
Authors: Taylor Philip R. , Zamze Susanne , Stillion Richard J. , Wong Simon Y. C. , Gordon Siamon , Martinez-Pomares Luisa
Published: February 2004

The cysteine-rich domain (CR) of the mannose receptor binds sulfated glycoprotein CR ligand (CRL) expressed by subpopulations of myeloid cells in secondary lymphoid organs (CRL+cells). In naïve mice, these CRL+cells, metallophilic macrophages (Mφ) in spleen and subcapsular sinus Mφ in lymph nodes, are located strategically for antigen capture and are adjacent to B cell follicles, but their role in the immune response is unknown. We have exploited the lectin activity of CR to develop a highly specific system for targeting protein to CRL+Mφ. We demonstrate that the sulfated carbohydrates recognized by CR are exposed to the extracellular milieu and mediate highly specific targeting of CR-containing proteins. This model will allow the dissection of the role of metallophilic Mφ in an immune responsein vivo.
Incipient Alzheimer's disease: Microarray correlation analyses reveal major transcriptional and tumor suppressor responses
Authors: Blalock Eric M. , Geddes James W. , Chen Kuey Chu , Porter Nada M. , Markesbery William R. , Landfield Philip W.
Published: February 2004

The pathogenesis of incipient Alzheimer's disease (AD) has been resistant to analysis because of the complexity of AD and the overlap of its early-stage markers with normal aging. Gene microarrays provide new tools for addressing complexity because they allow overviews of the simultaneous activity of multiple cellular pathways. However, microarray data interpretation is often hindered by low statistical power, high false positives or false negatives, and by uncertain relevance to functional endpoints. Here, we analyzed hippocampal gene expression of nine control and 22 AD subjects of varying severity on 31 separate microarrays. We then tested the correlation of each gene's expression with MiniMental Status Examination (MMSE) and neurofibrillary tangle (NFT) scores across all 31 subjects regardless of diagnosis. These well powered tests revealed a major transcriptional response comprising thousands of genes significantly correlated with AD markers. Several hundred of these genes were also correlated with AD markers across only control and incipient AD subjects (MMSE > 20). Biological process categories associated with incipient AD-correlated genes were identified statistically (easeprogram) and revealed up-regulation of many transcription factor/signaling genes regulating proliferation and differentiation, including tumor suppressors, oligodendrocyte growth factors, and protein kinase A modulators. In addition, up-regulation of adhesion, apoptosis, lipid metabolism, and initial inflammation processes occurred, and down-regulation of protein folding/metabolism/transport and some energy metabolism and signaling pathways took place. These findings suggest a new model of AD pathogenesis in which a genomically orchestrated up-regulation of tumor suppressor-mediated differentiation and involution processes induces the spread of pathology along myelinated axons.
Rho activity critically and selectively regulates endothelial cell organization during angiogenesis
Authors: Hoang Mien V. , Whelan Mary C. , Senger Donald R.
Published: February 2004

The mechanisms that control organization of endothelial cells (ECs) into new blood vessels are poorly understood. We hypothesized that the GTPase Rho, which regulates cytoskeletal architecture, is important for EC organization during neovascularization. To test this hypothesis, we designed a highly versatile mouse skin model that used vascular endothelial growth factor-expressing cells together with packaging cells producing retroviruses encoding RhoA GTPase mutants. In this animal model, dominant negative N19RhoA selectively impaired assembly of ECs into new blood vessels; and, in contrast, active V14RhoA stimulated ECs to form blood vessels with functional lumens.
In vitro
, dominant negative N19RhoA reduced EC actin stress fibers and prevented ECs from contracting and reorganizing into precapillary cords within collagen gels. In contrast, active V14RhoA promoted EC stress fiber formation, contractility, and organization into cords. Neither N19RhoA nor V14RhoA significantly affected EC proliferation or migration
in vitro
; and, similarly, neither mutant significantly affected EC density during angiogenesis
in vivo
. Thus, these studies identify a critical and selective role for Rho activity in regulating EC assembly into new blood vessels, and they identify both negative and positive manipulation of Rho activity, respectively, as strategies for suppressing or promoting the organizational stages of neovascularization.
Structure of the receptor-binding domain of human thrombopoietin determined by complexation with a neutralizing antibody fragment
Authors: Feese Michael D. , Tamada Taro , Kato Yoichi , Maeda Yoshitake , Hirose Masako , Matsukura Yasuko , Shigematsu Hideki , Muto Takanori , Matsumoto Atsushi , Watarai Hiroshi , Ogami Kinya , Tahara Tomoyuki , Kato Takashi , Miyazaki Hiroshi , Kuroki Ryota
Published: February 2004

The cytokine thrombopoietin (TPO), the ligand for the hematopoietic receptor c-Mpl, acts as a primary regulator of megakaryocytopoiesis and platelet production. We have determined the crystal structure of the receptor-binding domain of human TPO (hTPO
163
) to a 2.5-Å resolution by complexation with a neutralizing Fab fragment. The backbone structure of hTPO
163
has an antiparallel four-helix bundle fold. The neutralizing Fab mainly recognizes the C–D crossover loop containing the species invariant residue Q111. Titration calorimetric experiments show that hTPO
163
interacts with soluble c-Mpl containing the extracellular cytokine receptor homology domains with 1:2 stoichiometry with the binding constants of 3.3 × 10
9
M
–1
and 1.1 × 10
6
M
–1
. The presence of the neutralizing Fab did not inhibit binding of hTPO
163
to soluble c-Mpl fragments, but the lower-affinity binding disappeared. Together with prior genetic data, these define the structure–function relationships in TPO and the activation scheme of c-Mpl.
Negative regulation of eosinophil recruitment to the lung by the chemokine monokine induced by IFN-γ (Mig, CXCL9)
Authors: Fulkerson Patricia C. , Zimmermann Nives , Brandt Eric B. , Muntel Emily E. , Doepker Matthew P. , Kavanaugh Jessica L. , Mishra Anil , Witte David P. , Zhang Hongwei , Farber Joshua M. , Yang Ming , Foster Paul S. , Rothenberg Marc E.
Published: February 2004

Experimental analysis of allergic airway inflammation (AAI) in animals and humans is associated with coordinate gene induction. Using DNA microarray analysis, we have identified a large panel of AAI signature genes. Unexpectedly, the allergen-challenged lung (a T helper 2 microenvironment) was found to be associated with the expression of T helper 1-associated CXCR3 ligands, monokine induced by IFN-γ (Mig), and IFN-γ-inducible protein of 10 kDa (IP-10). Here we report that Mig functions as a negative regulator of murine eosinophils. Whereas Mig was not able to induce chemotaxis of eosinophils, pretreatment with Mig induced a dose-dependent inhibition of chemoattractant-induced eosinophil transmigrationin vitro. Moreover, i.v. administration of low doses of Mig (≈10–30 μg/kg) induced strong and specific dose-dependent inhibition of chemokine-, IL-13-, and allergen-induced eosinophil recruitment and, conversely, neutralization of Mig before allergen challenge increased airway eosinophilia. Importantly, Mig also inhibited a CCR3-mediated functional response in eosinophils. These results indicate that the ultimate distribution and function of inflammatory cells within the allergic lung is dictated by a balance between positively and negatively regulatory chemokines. The identification of a naturally occurring eosinophil inhibitory chemokine pathwayin vivoprovides a strategic basis for future therapeutic consideration.
Modification of
Helicobacter pylori
outer membrane protein expression during experimental infection of rhesus macaques
Authors: Solnick Jay V. , Hansen Lori M. , Salama Nina R. , Boonjakuakul Jenni K. , Syvanen Michael
Published: February 2004

Clinical isolates of
Helicobacter pylori
show marked diversity, which may derive from genomic changes that occur during the often lifelong association of the bacterium with its human host. We used the rhesus macaque model, together with DNA microarrays, to examine genomic changes in
H. pylori
that occur early during experimental infection. Microarray analysis showed that
H. pylori
recovered from challenged macaques had deleted
babA
, a member of a large family of paralogous outer membrane proteins (OMPs) that mediates attachment of
H. pylori
to the Lewis B blood group antigen on gastric epithelium. In some cases the
babA
gene was replaced by
babB
, an uncharacterized OMP that is closely related to
babA
. In other cases the
babA
gene was present but was not expressed because of alteration in dinucleotide CT repeats in the 5′ coding region. In either case, strains lacking
babA
did not adhere to Lewis B, which is expressed on macaque gastric epithelium. Absence of
babA
and duplication of
babB
was also seen in
H. pylori
isolates derived from human clinical samples, suggesting that this gene conversion event is not unique to experimentally infected rhesus monkeys. These results demonstrate in real time with a relevant animal model that
H. pylori
regulates OMP expression
in vivo
by using both antigenic variation and phase variation. We suggest that changes in
babA
and
babB
after experimental infection of macaques represent a dynamic response in the
H. pylori
outer membrane that facilitates adherence to the gastric epithelium and promotes chronic infection.
Propagation of infectious human papillomavirus type 16 by using an adenovirus and Cre/LoxP mechanism
Authors: Lee John H. , Yi Su Min P. , Anderson Mary E. , Berger Kristi L. , Welsh Michael J. , Klingelhutz Aloysius J. , Ozbun Michelle A.
Published: February 2004

Human papillomavirus type 16 (HPV16) infection is a major risk factor for the development of squamous cell cancers of the cervix and of the head and neck. A major barrier to understanding the progression from initial infection to cancer has been the lack of
in vitro
models that allow infection, replication, and persistence of the viral genome as an episome in differentiated epithelial cells. To overcome this barrier, we designed an adenoviral delivery vector that contained a full HPV16 genome flanked by LoxP homologous recombination sites and a fluorescent reporter that was expressed only after the HPV genome was excised by Cre recombinase. This system delivered circular HPV16 genomes to cervical epithelial cells and well differentiated human airway epithelia. After delivery, the HPV16 genome replicated and persisted as an episome in cervical keratinocytes. These cells developed an immortalized phenotype and a dysplastic epithelial appearance. Moreover, induction of differentiation led to the expression of late genes and production of infectious HPV16 virions. This work provides a means of introducing biologically active HPV genomes into epithelial cells, which are normally difficult to transfect. These methods allow the study of HPV genome replication and gene expression in the earliest stages of HPV genome establishment, and they may provide a means to study nononcogenic HPV viral types.
Liver-specific deletion of negative regulator Pten results in fatty liver and insulin hypersensitivity
Authors: Stiles Bangyan , Wang Ying , Stahl Andreas , Bassilian Sara , Lee W. Paul , Kim Yoon-Jung , Sherwin Robert , Devaskar Sherin , Lesche Ralf , Magnuson Mark A. , Wu Hong
Published: February 2004

In the liver, insulin controls both lipid and glucose metabolism through its cell surface receptor and intracellular mediators such as phosphatidylinositol 3-kinase and serine-threonine kinase AKT. The insulin signaling pathway is further modulated by protein tyrosine phosphatase or lipid phosphatase. Here, we investigated the function of phosphatase and tension homologue deleted on chromosome 10 (PTEN), a negative regulator of the phosphatidylinositol 3-kinase/AKT pathway, by targeted deletion of
Pten
in murine liver. Deletion of
Pten
in the liver resulted in increased fatty acid synthesis, accompanied by hepatomegaly and fatty liver phenotype. Interestingly,
Pten
liver-specific deletion causes enhanced liver insulin action with improved systemic glucose tolerance. Thus, deletion of
Pten
in the liver may provide a valuable model that permits the study of the metabolic actions of insulin signaling in the liver, and PTEN may be a promising target for therapeutic intervention for type 2 diabetes.
Crosslinking snapshots of bacterial chemoreceptor squads
Authors: Studdert Claudia A. , Parkinson John S.
Published: February 2004

The team signaling model for bacterial chemoreceptors proposes that receptor dimers of different detection specificities form mixed trimers of dimers. These receptor “squads” then recruit the cytoplasmic signaling proteins CheA and CheW to form ternary signaling teams, which typically cluster at the poles of the cell. We devised cysteine-directed
in vivo
crosslinking approaches to ask whether mixed receptor squads could form in the absence of CheA and CheW and, if so, whether the underlying structural interactions conformed to trimer-of-dimers geometry. One approach used cysteine reporters at positions in the serine (Tsr) and aspartate (Tar) receptors that should form disulfide-linked Tsr≈Tar products when juxtaposed at the interface of a mixed trimer. Another approach used a cysteine reporter with trigonal geometry near the trimer contact region and a trifunctional maleimide reagent with a spacer length appropriate for capturing the three axial subunits in a trimer of dimers. Both approaches detected mixed receptor-crosslinking products in cells lacking CheA and CheW. Under these conditions, receptor methylation and ligand-binding state had no discernable effect on crosslinking efficiencies. Crosslinking with the trigonal reporter was rapid and did not increase with longer treatment times or higher reagent concentrations, suggesting that this method produces a short-exposure snapshot of the receptor population. The extent of crosslinking indicated that most of the cell's receptor molecules were organized in higher-order groups. Crosslinking in receptor trimer contact mutants correlated with their signaling behaviors, suggesting that trimers of dimers are both structural and functional precursors of chemoreceptor signaling teams in bacteria.
Cotranscriptional recruitment of the serine-arginine-rich (SR)-like proteins Gbp2 and Hrb1 to nascent mRNA via the TREX complex
Authors: Hurt Ed , Luo Ming-juan , Röther Susanne , Reed Robin , Sträßer Katja
Published: February 2004

The TREX (transcription/export) complex couples transcription elongation to the nuclear export of mRNAs. In this article, we show that the poly(A)
+
RNA-binding proteins Gbp2 and Hrb1, which resemble the serine-arginine-rich (SR) family of splicing factors found in higher eukaryotes, are specifically associated with the yeast TREX complex. We also show that Gbp2 and Hrb1 interact with Ctk1, a kinase that phosphorylates the C-terminal domain of RNA polymerase II during transcription elongation. Consistent with these findings, Gbp2 and Hrb1 associate with actively transcribed genes throughout their entire lengths. By using an RNA immunoprecipitation assay, we show that Gbp2 and Hrb1 also are bound to transcripts that are derived from these genes. We conclude that recruitment of the SR-like proteins Gbp2 and Hrb1 to mRNA occurs cotranscriptionally by means of association with the TREX complex and/or Ctk1.
Ceramidase expression facilitates membrane turnover and endocytosis of rhodopsin in photoreceptors
Authors: Acharya Usha , Mowen Michael Beth , Nagashima Kunio , Acharya Jairaj K.
Published: February 2004

Transgenic expression of ceramidase suppresses retinal degeneration in
Drosophila
arrestin and phospholipase C mutants. Here, we show that expression of ceramidase facilitates the dissolution of incompletely formed and inappropriately located elements of rhabdomeric membranes in

ninaE
I17

mutants lacking the G protein receptor Rh1 in R1–R6 photoreceptor cells. Ceramidase expression facilitates the endocytic turnover of Rh1. Although ceramidase expression aids the removal of internalized rhodopsin, it does not affect the turnover of Rh1 in photoreceptors maintained in dark, where Rh1 is not activated and thus has a slower turnover and a long half-life. Therefore, the phenotypic consequence of ceramidase expression in photoreceptors is caused by facilitation of endocytosis. This study provides mechanistic insight into the sphingolipid biosynthetic pathway-mediated modulation of endocytosis and suppression of retinal degeneration.
GATA-3 deficiency abrogates the development and maintenance of T helper type 2 cells
Authors: Pai Sung-Yun , Truitt Morgan L. , Ho I-Cheng
Published: February 2004

T helper type 2 (Th2) cells secrete IL-4, IL-5, IL-10, and IL-13 and mediate allergic and asthmatic disease. GATA-3 is a Th2-specific transcription factor that appears in overexpression studies and transgenic systems to function as a Th2 lineage determinant. Because GATA-3 is also crucial for development of the T lineage and throughout thymic development, direct demonstration that GATA-3 is required for Th2 development by targeted deletion has been lacking. Using a conditional knockout approach, we found that GATA-3 is required for optimal Th2 cytokine productionin vitroandin vivo. Our data also show that GATA-3 expression must be sustained to maintain the Th2 phenotype.
Arthritis suppressor genes TIA-1 and TTP dampen the expression of tumor necrosis factor α, cyclooxygenase 2, and inflammatory arthritis
Authors: Phillips Kristine , Kedersha Nancy , Shen Lily , Blackshear Perry J. , Anderson Paul
Published: February 2004

TIA-1 and TTP are AU-rich element-binding proteins that prevent the pathological overexpression of tumor necrosis factor α (TNF-α). TIA-1 inhibits the translation of TNF-α transcripts, whereas TTP promotes the degradation of TNF-α transcripts. Here we show that TIA-1 and TTP function as arthritis suppressor genes: TIA-1
–/–
mice develop mild arthritis, TTP
–/–
mice develop severe arthritis, and TIA-1
–/–
TTP
–/–
mice develop very severe arthritis. Peritoneal macrophages derived from all three genotypes overexpress cyclooxygenase 2 and TNF-α. Surprisingly, lipopolysaccharide-activated TIA-1
–/–
TTP
–/–
macrophages secrete less TNF-α protein than either TIA-1
–/–
or TTP
–/–
macrophages. In these mice, arthritogenic cytokine may be produced by neutrophils that accumulate in the bone marrow and peripheral blood. Our results suggest that TIA-1 and TTP are genetic modifiers of inflammatory arthritis that can alter the spectrum of cells that produce arthritogenic cytokines.
Genetic diversity and insecticide resistance of Myzus persicae (Hemiptera: Aphididae) populations from tobacco in Chile: evidence for the existence of a single predominant clone
Authors: Fuentes-Contreras E. , Figueroa C.C. , Reyes M. , Briones L.M. , Niemeyer H.M.
Published: February 2004

The tobacco-feeding race of Myzus persicae (Sulzer), formerly known as M. nicotianae Blackman, was introduced into Chile during the last decade. In order to evaluate the genetic diversity and insecticide resistance status of Chilean tobacco aphid populations, a field survey was conducted in 35 tobacco fields covering a 300 km latitudinal survey. The populations sampled were characterized using microsatellite markers and morphometric multivariate analysis. Insecticide resistance levels were assessed through a microplate esterase assay and the mutation status of the kdr gene. All samples collected corresponded to the same anholocyclic aphid genotype, and showed morphological variation within the range expected for the tobacco-feeding race of M. persicae. Esterase activity showed the level and variability expected for an R1 clone lacking mutations in the sodium channels (susceptible kdr), thus corresponding to a type slightly resistant to organophosphate and carbamate, and susceptible to pyrethroid insecticides.
A bioassay to evaluate the activity of chemical stimuli from grape berries on the oviposition of Lobesia botrana (Lepidoptera: Tortricidae)
Authors: Maher N. , Thiéry D.
Published: February 2004

A two-choice bioassay was developed to evaluate the role of host-plant berry compounds on the oviposition site acceptance of the generalist moth Lobesia botrana (Denis & Shiffermüller). A key feature was the lining of the bioassay arena with felt which focused oviposition on the test substrates. Initial experiments comparing substrates with different physical features indicated that smooth textures and spherical shapes with interstices favour oviposition. Artificial oviposition substrates were thus constructed with glass spheres in order to test the behavioural activity of grapevine berry extracts. Only polar extracts obtained by soaking berries in methanol or water stimulated oviposition (more eggs were laid on the extract-treated substrate than on the control substrate), whereas more apolar ones obtained with chloroform or hexane had no significant effect. The prior removal of epicuticular waxes from grape berries before extraction did not enhance the stimulatory activity of the methanol extract. The oviposition response to this extract was dose-dependent. It is concluded that polar compounds present on grape berries act as oviposition stimulants for L. botrana.
Estimating population density of the Formosan subterranean termite, Coptotermes formosanus(Isoptera: Rhinotermitidae) using the effective sampling area of in-ground monitoring stations
Authors: Puche H. , Su N.-Y.
Published: February 2004

The effective sampling area of a monitoring station, α, was calculated for several Coptotermes formosanus Shiraki colonies in Broward County, Florida, USA. A simple mark–recapture protocol provided data on termite station catch within a foraging range of a colony. Average recapture probability was 0.005 close to the releae point (< 5 m) and declined to 0.0008 at a distance of 51 to 60 m. The relation between the log % termites recaptured was fitted with log distance, to determine P(x), the average proportion of captured termites that started at distance x from the release point. The effective sampling area was estimated by using P(x) and the equation, α 2 π∫{ x P(x)} dx. Integrating this equation, an average estimate α that ranged from 0.607 to 14.5 m2 was obtained. Factors influencing the variation of α among the colonies are discussed. The effective sampling area estimated should be taken as a reliable estimator that translates subterranean termite catches into termite population density.
Host plant age and population development of a cereal aphid, Metopolophium dirhodum (Hemiptera: Aphididae)
Authors: Honek A. , Martinkova Z.
Published: February 2004

The sudden decline following the peak in population abundance of aphids on crops of small grain cereals is attributed to the joint effect of natural enemies and plant senescence. To distinguish between these causes, a four year experiment was established in which the numbers of Metopolophium dirhodum (Walker) infesting spring wheat plots sown from April to June at c. 14 day intervals were determined. Aphid abundance in replicates sown at successive dates peaked within a period of 5–9 days (106–171 day degrees above a base temperature of 0°C) although their sowing dates varied by 62–97 days (727–1106 day degrees). At the time of the aphid population peaks, plants in the different sowings differed in age (11–99 days), developmental stage (stage 15–65 on the Zadoks scale), leaf nitrogen content and shoot mass. Maximum abundance of M. dirhodum decreased with sowing date because the time available for its population increase was shorter on late than early sowings. The abundance of M. dirhodum on spring wheat was similar to its abundance on winter wheat. After reaching peak abundance, aphids declined in numbers within 3–7 days. The effect of host plant ageing on the M. dirhodumdecline thus appeared small. Natural enemies (largely mycoses), and timing of alata production may have contributed to the aphid decline.
Role of modified CDC miniature light-traps as an alternative method for sampling adult anophelines (Diptera: Culicidae) in the National Mosquito Surveillance Programme in India
Authors: Sadanandane C. , Jambulingam P. , Subramanian S.
Published: February 2004

The efficiency of modified CDC miniature light-traps for sampling adult mosquitoes was evaluated in comparison with indoor resting, outdoor resting, indoor man-landing and outdoor man-landing collections in the hilly district of Koraput, Orissa, India. Overall, light-traps captured 78% of adult mosquitoes collected by all methods. Of the 16 anopheline species recorded in the study area, light-traps effectively sampled 13, contributing about 72% of the total anophelines collected by all methods. Light-traps also caught a large number of female Culex vishnui Theobald (96%). As fully-fed mosquitoes were predominant (82%) and caught alive, light-traps can be used to catch large numbers of vector mosquitoes for studies on vector prevalence, distribution, vector incrimination and also for laboratory bioassays. Light-trap and indoor resting collections revealed similar seasonal trends in numbers of Anopheles culicifacies Giles, A. fluviatilis James, A. jeyporiensis James, A. vagus Doenitz, and A. splendidus Koidzumi. Age-structure of the samples did not vary significantly between the two methods. Light-traps could be used as an alternative to daytime indoor resting collections to monitor the seasonal fluctuations in the abundance and parity rates of these species. The light-trap collections correlated with indoor and outdoor man-landing collections of A. jeyporiensis and the outdoor man-landing collections of A. maculatusTheobald in measuring seasonal trends. Light-trap collections can thus be used as a substitute for man-landing collections of A. jeyporiensis and A. maculatus.
Comparing mark–recapture and constant removal protocols for estimating forager population size of the subterranean termite Coptotermes lacteus (Isoptera: Rhinotermitidae)
Authors: Evans T.A.
Published: February 2004

Forager population sizes of colonies of Coptotermes lacteus(Froggatt) in New South Wales were estimated using two methods: mark–recapture and constant removal, in two disturbed habitats: a pine plantation and cleared farmland. Mark–recapture population estimates were unrealistic and unreliable: they could be improbably large, over 200 million foragers, and they varied enormously between samples for each colony without any pattern. The constant removal population estimates could also be unrealistic: they could be negative or quite different when calculated using regression and maximum likelihood methods. However, the unrealistic results could be predicted reliably, and explained by the lack of re-contact with the sampling devices (bait stations) – a violation of an assumption of the method. This happened more frequently in the plantation than in the farmland, probably because of the greater abundance of alternative food sources in the plantation. Of the two methods, constant removal provided reasonable forager population estimates, relative to direct counts, at least some of the time, plus a mechanism by which reliability could be tested, whereas mark–recapture provided neither. Further refinement and testing of constant removal methods are urged to provide a more reliable population estimation technique for termites.
Cross talk between physical activity and appetite control: does physical activity stimulate appetite?
Authors: Blundell J. E. , Stubbs R. J. , Hughes D. A. , Whybrow S. , King N. A.
Published: February 2004

Physical activity has the potential to modulate appetite control by improving the sensitivity of the physiological satiety signalling system, by adjusting macronutrient preferences or food choices and by altering the hedonic response to food. There is evidence for all these actions. Concerning the impact of physical activity on energy balance, there exists a belief that physical activity drives up hunger and increases food intake, thereby rendering it futile as a method of weight control. There is, however, no evidence for such an immediate or automatic effect. Short (1–2 d)-term and medium (7–16 d)-term studies demonstrate that men and women can tolerate substantial negative energy balances of ≤4MJ energy cost/d when performing physical activity programmes. Consequently, the immediate effect of taking up exercise is weight loss (although this outcome is sometimes difficult to assess due to changes in body composition or fluid compartmentalization). However, subsequently food intake begins to increase in order to provide compensation for about 30% of the energy expended in activity. This compensation (up to 16 d) is partial and incomplete. Moreover, subjects separate into compensators and non-compensators. The exact nature of these differences in compensation and whether it is actually reflective of non-compliance with protocols is yet to be determined. Some subjects (men and women) performing activity with a cost of ≤4 MJ/d for 14 d, show no change in daily energy intake. Conversely, it can be demonstrated that when active individuals are forced into a sedentary routine food intake does not decrease to a lower level to match the reduced energy expenditure. Consequently, this situation creates a substantial positive energy balance accompanied by weight gain. The next stage is to further characterize the compensators and non-compensators, and to identify the mechanisms (physiological or behavioural) that are responsible for the rate of compensation and its limits.
Promyelocytic leukemia nuclear bodies associate with transcriptionally active genomic regions
Authors: Wang Jayson , Shiels Carol , Sasieni Peter , Wu Pei Jun , Islam Suhail A. , Freemont Paul S. , Sheer Denise
Published: February 2004

The promyelocytic leukemia (PML) protein is aggregated into nuclear bodies that are associated with diverse nuclear processes. Here, we report that the distance between a locus and its nearest PML body correlates with the transcriptional activity and gene density around the locus. Genes on the active X chromosome are more significantly associated with PML bodies than their silenced homologues on the inactive X chromosome. We also found that a histone-encoding gene cluster, which is transcribed only in S-phase, is more strongly associated with PML bodies in S-phase than in G0/G1 phase of the cell cycle. However, visualization of specific RNA transcripts for several genes showed that PML bodies were not themselves sites of transcription for these genes. Furthermore, knock-down of PML bodies by RNA interference did not preferentially change the expression of genes closely associated with PML bodies. We propose that PML bodies form in nuclear compartments of high transcriptional activity, but they do not directly regulate transcription of genes in these compartments.
Phosphorylation of paxillin by p38MAPK is involved in the neurite extension of PC-12 cells
Authors: Huang Cai , Borchers Christoph H. , Schaller Michael D. , Jacobson Ken
Published: February 2004

Cell adhesions play an important role in neurite extension. Paxillin, a focal adhesion adaptor protein involved in focal adhesion dynamics, has been demonstrated to be required for neurite outgrowth. However, the molecular mechanism by which paxillin regulates neurite outgrowth is unknown. Here, we show that paxillin is phosphorylated by p38MAPK in vitro and in nerve growth factor (NGF)–induced PC-12 cells. Ser 85 (Ser 83 for endogenous paxillin) is identified as one of major phosphorylation sites by phosphopeptide mapping and mass spectrometry. Moreover, expression of the Ser 85 → Ala mutant of paxillin (paxS85A) significantly inhibits NGF-induced neurite extension of PC-12 cells, whereas expression of wild-type (wt) paxillin does not influence neurite outgrowth. Further experiments indicate that cells expressing paxS85A exhibit small, clustered focal adhesions which are not normally seen in cells expressing wt paxillin. Although wt paxillin and paxS85A have the same ability to bind vinculin and focal adhesion kinase, wt paxillin more efficiently associates with Pyk2 than paxS85A. Thus, phosphorylation of paxillin is involved in NGF-induced neurite extension of PC-12 cells, probably through regulating focal adhesion organization.
Chronological aging leads to apoptosis in yeast
Authors: Herker Eva , Jungwirth Helmut , Lehmann Katharina A. , Maldener Corinna , Fröhlich Kai-Uwe , Wissing Silke , Büttner Sabrina , Fehr Markus , Sigrist Stephan , Madeo Frank
Published: February 2004

During the past years, yeast has been successfully established as a model to study mechanisms of apoptotic regulation. However, the beneficial effects of such a cell suicide program for a unicellular organism remained obscure. Here, we demonstrate that chronologically aged yeast cultures die exhibiting typical markers of apoptosis, accumulate oxygen radicals, and show caspase activation. Age-induced cell death is strongly delayed by overexpressing YAP1, a key transcriptional regulator in oxygen stress response. Disruption of apoptosis through deletion of yeast caspase YCA1 initially results in better survival of aged cultures. However, surviving cells lose the ability of regrowth, indicating that predamaged cells accumulate in the absence of apoptotic cell removal. Moreover, wild-type cells outlast yca1 disruptants in direct competition assays during long-term aging. We suggest that apoptosis in yeast confers a selective advantage for this unicellular organism, and demonstrate that old yeast cells release substances into the medium that stimulate survival of the clone.
Mutagenesis of the putative sterol-sensing domain of yeast Niemann Pick C–related protein reveals a primordial role in subcellular sphingolipid distribution
Authors: Malathi Krishnamurthy , Higaki Katsumi , Tinkelenberg Arthur H. , Balderes Dina A. , Almanzar-Paramio Dorca , Wilcox Lisa J. , Erdeniz Naz , Redican Francis , Padamsee Mahajabeen , Liu Ying , Khan Sohail , Alcantara Frederick , Carstea Eugene D. , Morris Jill A. , Sturley Stephen L.
Published: February 2004

Lipid movement between organelles is a critical component of eukaryotic membrane homeostasis. Niemann Pick type C (NP-C) disease is a fatal neurodegenerative disorder typified by lysosomal accumulation of cholesterol and sphingolipids. Expression of yeast NP-C–related gene 1 (NCR1), the orthologue of the human NP-C gene 1 (NPC1) defective in the disease, in Chinese hamster ovary NPC1 mutant cells suppressed lipid accumulation. Deletion of NCR1, encoding a transmembrane glycoprotein predominantly residing in the vacuole of normal yeast, gave no phenotype. However, a dominant mutation in the putative sterol-sensing domain of Ncr1p conferred temperature and polyene antibiotic sensitivity without changes in sterol metabolism. Instead, the mutant cells were resistant to inhibitors of sphingolipid biosynthesis and super sensitive to sphingosine and C2-ceramide. Moreover, plasma membrane sphingolipids accumulated and redistributed to the vacuole and other subcellular membranes of the mutant cells. We propose that the primordial function of these proteins is to recycle sphingolipids and that defects in this process in higher eukaryotes secondarily result in cholesterol accumulation.
Greatwall kinase
Authors: Yu Jiangtao , Fleming Shawna L. , Williams Byron , Williams Erika V. , Li ZeXiao , Somma Patrizia , Rieder Conly L. , Goldberg Michael L.
Published: February 2004

Mutations in the Drosophila gene greatwall cause improper chromosome condensation and delay cell cycle progression in larval neuroblasts. Chromosomes are highly undercondensed, particularly in the euchromatin, but nevertheless contain phosphorylated histone H3, condensin, and topoisomerase II. Cells take much longer to transit the period of chromosome condensation from late G2 through nuclear envelope breakdown. Mutant cells are also subsequently delayed at metaphase, due to spindle checkpoint activity. These mutant phenotypes are not caused by spindle aberrations, by global defects in chromosome replication, or by activation of a caffeine-sensitive checkpoint. The Greatwall proteins in insects and vertebrates are located in the nucleus and belong to the AGC family of serine/threonine protein kinases; the kinase domain of Greatwall is interrupted by a long stretch of unrelated amino acids.
Amylin inhibits bone resorption while the calcitonin receptor controls bone formation in vivo
Authors: Dacquin Romain , Davey Rachel A. , Laplace Catherine , Levasseur Régis , Morris Howard A. , Goldring Steven R. , Gebre-Medhin Samuel , Galson Deborah L. , Zajac Jeffrey D. , Karsenty Gérard
Published: February 2004

Amylin is a member of the calcitonin family of hormones cosecreted with insulin by pancreatic β cells. Cell culture assays suggest that amylin could affect bone formation and bone resorption, this latter function after its binding to the calcitonin receptor (CALCR). Here we show that Amylin inactivation leads to a low bone mass due to an increase in bone resorption, whereas bone formation is unaffected. In vitro, amylin inhibits fusion of mononucleated osteoclast precursors into multinucleated osteoclasts in an ERK1/2-dependent manner. Although Amylin +/− mice like Amylin-deficient mice display a low bone mass phenotype and increased bone resorption, Calcr +/− mice display a high bone mass due to an increase in bone formation. Moreover, compound heterozygote mice for Calcr and Amylin inactivation displayed bone abnormalities observed in both Calcr +/− and Amylin +/− mice, thereby ruling out that amylin uses CALCR to inhibit osteoclastogenesis in vivo. Thus, amylin is a physiological regulator of bone resorption that acts through an unidentified receptor.
Specific Regulation of T Helper Cell 1–mediated Murine Colitis by CEACAM1
Authors: Iijima Hideki , Neurath Markus F. , Nagaishi Takashi , Glickman Jonathan N. , Nieuwenhuis Edward E. , Nakajima Atsushi , Chen Daohong , Fuss Ivan J. , Utku Nalan , Lewicki Daniel N. , Becker Christoph , Gallagher Thomas M. , Holmes Kathryn V. , Blumberg Richard S.
Published: February 2004

Carcinoembryonic antigen-related cellular adhesion molecule 1 (CEACAM1) is a cell surface molecule that has been proposed to negatively regulate T cell function. We have shown that CEACAM1 is associated with specific regulation of T helper cell (Th)1 pathways, T-bet–mediated Th1 cytokine signaling, and Th1-mediated immunopathology in vivo. Mice treated with anti–mouse CEACAM1-specific monoclonal antibody (mAb) CC1 during the effector phase exhibited a reduced severity of trinitrobenzene sulfonic acid colitis in association with decreased interferon (IFN)-γ production. Although oxazolone colitis has been reported as Th2 mediated, mice treated with the CC1 mAb or a CEACAM1-Fc chimeric protein exhibited a reduced severity of colitis in association with a significant reduction of IFN-γ and T-bet activation, whereas signal transducer and activator of antigen 4 activation was unaffected. Both interleukin-4 and IFN-γ gene–deficient mice exhibited less severe colitis induction by oxazolone. Direct ligation of T cells in vitro with the murine hepatitis virus spike protein, a natural ligand for the N-domain of CEACAM1, inhibited the differentiation of naive cells into Th1 but not Th2 cells and activation of Th1 but not Th2 cytokine production. These results indicate that CEACAM1 isoforms are a novel class of activation-induced cell surface molecules on T cells that function in the specific regulation of Th1-mediated inflammation such as that associated with inflammatory bowel disease.
CpG-matured Murine Plasmacytoid Dendritic Cells Are Capable of In Vivo Priming of Functional CD8 T Cell Responses to Endogenous but Not Exogenous Antigens
Authors: Salio Mariolina , Palmowski Michael J. , Atzberger Ann , Hermans Ian F. , Cerundolo Vincenzo
Published: February 2004

Plasmacytoid dendritic cells (PDCs) are a unique leukocyte population capable of secreting high levels of type I interferon (IFN) in response to viruses and bacterial stimuli. In vitro experiments have shown that upon maturation, human and murine PDCs develop into potent immunostimulatory cells; however, their ability to prime an immune response in vivo remains to be addressed. We report that CpG-matured murine PDCs are capable of eliciting in naive mice antigen-specific CTLs against endogenous antigens as well as exogenous peptides, but not against an exogenous antigen. Type I IFN is not required for priming, as injection of CpG-matured PDCs into type I IFN receptor–deficient mice elicits functional CTL responses. Mature PDCs prime CTLs that secrete IFN-γ and protect mice from a tumor challenge. In contrast, immature PDCs are unable to prime antigen-specific CTLs. However, mice injected with immature PDCs are fully responsive to secondary antigenic challenges, suggesting that PDCs have not induced long-lasting tolerance via anergic or regulatory T cells. Our results underline the heterogeneity and plasticity of different antigen-presenting cells, and reveal an important role of mature PDCs in priming CD8 responses to endogenous antigens, in addition to their previously reported ability to modulate antiviral responses via type I IFN.
N-linked Glycosylation Is Required for Optimal Function of Kaposi's Sarcoma Herpesvirus–encoded, but Not Cellular, Interleukin 6
Authors: Dela Cruz Charles S. , Lee Yoomi , Viswanathan Srinivas R. , El-Guindy Ayman S. , Gerlach Jennifer , Nikiforow Sarah , Shedd Duane , Gradoville Lyn , Miller George
Published: February 2004

Kaposi's sarcoma–associated herpesvirus interleukin-6 (vIL-6) is a structural and functional homologue of the human cytokine IL-6 (hIL-6). hIL-6 and vIL-6 exhibit similar biological functions and both act via the gp130 receptor subunit to activate the Janus tyrosine kinase (JAK)1 and signal transducer and activator of transcription (STAT)1/3 pathway. Here we show that vIL-6 is N-linked glycosylated at N78 and N89 and demonstrate that N-linked glycosylation at site N89 of vIL-6 markedly enhances binding to gp130, signaling through the JAK1-STAT1/3 pathway and functions in a cytokine-dependent cell proliferation bioassay. Although hIL-6 is also N-glycosylated at N73 and multiply O-glycosylated, neither N-linked nor O-linked glycosylation is necessary for IL-6 receptor α–dependent binding to gp130 or signaling through JAK1-STAT1/3. As distinct from vIL-6, unglycosylated hIL-6 is as potent as glycosylated hIL-6 in stimulating B cell proliferation. These findings highlight distinct functional roles of N-linked glycosylation in viral and cellular IL-6.
Interleukin 18 Acts on Memory T Helper Cells Type 1 to Induce Airway Inflammation and Hyperresponsiveness in a Naive Host Mouse
Authors: Sugimoto Takaaki , Ishikawa Yuriko , Yoshimoto Tomohiro , Hayashi Nobuki , Fujimoto Jiro , Nakanishi Kenji
Published: February 2004

Interleukin (IL)-18 was originally regarded to induce T helper cell (Th)1-related cytokines. In general, factors favoring interferon (IFN)-γ production are believed to abolish allergic diseases. Thus, we tested the role of IL-18 in regulation of bronchial asthma. To avoid a background response of host-derived T cells, we administered memory type Th1 or Th2 cells into unsensitized mice and examined their role in induction of bronchial asthma. Administration of antigen (Ag) induced both airway inflammation and airway hyperresponsiveness (AHR) in mice receiving memory Th2 cells. In contrast, the same treatment induced only airway inflammation but not AHR in mice receiving memory Th1 cells. However, these mice developed striking AHR when they were coadministered with IL-18. Furthermore, mice having received IFN-γ–expressing Th1 cells sorted from polarized Th1 cells developed severe airway inflammation and AHR after intranasal administration of Ag and IL-18. Thus, Th1 cells become harmful when they are stimulated with Ag and IL-18. Newly polarized Th1 cells and IFN-γ–expressing Th1 cells, both of which express IL-18 receptor α chain strongly, produce IFN-γ, IL-9, IL-13, granulocyte/macrophage colony-stimulating factor, tumor necrosis factor α, regulated on activation, normal T cell expressed and secreted, and macrophage inflammatory protein 1α upon stimulation with Ag, IL-2, and IL-18 in vitro. Thus, Ag and IL-18 stimulate memory Th1 cells to induce severe airway inflammation and AHR in the naive host.
Deficiency of the Cyclin Kinase Inhibitor p21(WAF-1/CIP-1) Promotes Apoptosis of Activated/Memory T Cells and Inhibits Spontaneous Systemic Autoimmunity
Authors: Lawson Brian R. , Baccala Roberto , Song Jianxun , Croft Michael , Kono Dwight H. , Theofilopoulos Argyrios N.
Published: February 2004

A characteristic feature of systemic lupus erythematosus is the accumulation of activated/memory T and B cells. These G0/G1-arrested cells express high levels of cyclin-dependent kinase inhibitors such as p21, are resistant to proliferation and apoptosis, and produce large amounts of proinflammatory cytokines. Herein, we show that ablation of p21 in lupus-prone mice allows these cells to reenter the cell cycle and undergo apoptosis, leading to autoimmune disease reduction. Absence of p21 resulted in enhanced Fas/FasL-mediated activation-induced T cell death, increased activation of procaspases 8 and 3, and loss of mitochondrial transmembrane potential. Increased apoptosis was also associated with p53 up-regulation and a modest shift in the ratio of Bax/Bcl-2 toward the proapoptotic Bax. Proliferation and apoptosis of B cells were also increased in p21−/− lupus mice. Thus, modulation of the cell cycle pathway may be a novel approach to reduce apoptosis-resistant pathogenic lymphocytes and to ameliorate systemic autoimmunity.