bluuebunny/crossref_metadata_2025 huggingface dataset:
BH3-only protein Puma contributes to death of antigen-specific T cells during shutdown of an immune response to acute viral infection
Authors: Fischer Silke F. , Belz Gabrielle T. , Strasser Andreas
Published: February 2008

During acute T cell immune responses to viral infection, antigen-specific T cells first proliferate and differentiate into effector cells, but after pathogen clearance most are deleted by apoptosis. The developmentally programmed death of antigen-specific T cells during shutdown of a T cell response is mediated by the Bcl-2-regulated apoptotic pathway and partly depends on the proapoptotic BH3-only protein Bim. However, loss of Bim enhanced survival of antigen-activated T cells to a lesser extent than Bcl-2 overexpression, indicating that other proapoptotic factors must contribute to T cell killing. In this study, we investigated the contributions of several BH3-only proteins to the shutdown of an acute T cell immune responsein vivo. After infection with human herpes simplex virus (HSV-1), mice lacking Noxa, Bid, or Bad had a normal increase and subsequent decline in the numbers of antigen-specific CD8+T cells. In contrast, Puma-deficient mice showed an abnormally prolonged persistence of antigen-specific CD8+T cells in the spleen, associated with enhancedin vitrosurvival of these cells in the absence of cytokines. Puma was dispensable for viral clearance and also did not play a role in proliferation or activation of HSV-1-specific CD8+T cellsin vivo. Collectively, these findings show that Puma contributes to the death of antigen-specific T cells during shutdown of an immune response.
ESCRT factors restrict mycobacterial growth
Authors: Philips Jennifer A. , Porto Maura C. , Wang Hui , Rubin Eric J. , Perrimon Norbert
Published: February 2008

Nearly 1.7 billion people are infected with
Mycobacterium tuberculosis
. Its ability to survive intracellularly is thought to be central to its success as a pathogen, but how it does this is poorly understood. Using a
Drosophila
model of infection, we identify three host cell activities, Rab7, CG8743, and the ESCRT machinery, that modulate the mycobacterial phagosome. In the absence of these factors the cell no longer restricts growth of the non-pathogen
Mycobacterium smegmatis
. Hence, we identify factors that represent unique vulnerabilities of the host cell, because manipulation of any one of them alone is sufficient to allow a nonpathogenic mycobacterial species to proliferate. Furthermore, we demonstrate that, in mammalian cells, the ESCRT machinery plays a conserved role in restricting bacterial growth.
A giant frog with South American affinities from the Late Cretaceous of Madagascar
Authors: Evans Susan E. , Jones Marc E. H. , Krause David W.
Published: February 2008

Madagascar has a diverse but mainly endemic frog fauna, the biogeographic history of which has generated intense debate, fueled by recent molecular phylogenetic analyses and the near absence of a fossil record. Here, we describe a recently discovered Late Cretaceous anuran that differs strikingly in size and morphology from extant Malagasy taxa and is unrelated either to them or to the predicted occupants of the Madagascar–Seychelles–India landmass when it separated from Africa 160 million years ago (Mya). Instead, the previously undescribed anuran is attributed to the Ceratophryinae, a clade previously considered endemic to South America. The discovery offers a rare glimpse of the anuran assemblage that occupied Madagascar before the Tertiary radiation of mantellids and microhylids that now dominate the anuran fauna. In addition, the presence of a ceratophryine provides support for a controversial paleobiogeographical model that posits physical and biotic links among Madagascar, the Indian subcontinent, and South America that persisted well into the Late Cretaceous. It also suggests that the initial radiation of hyloid anurans began earlier than proposed by some recent estimates.
6-Ethynylthieno[3,2-d]- and 6-ethynylthieno[2,3-d]pyrimidin-4-anilines as tunable covalent modifiers of ErbB kinases
Authors: Wood Edgar R. , Shewchuk Lisa M. , Ellis Byron , Brignola Perry , Brashear Ronald L. , Caferro Thomas R. , Dickerson Scott H. , Dickson Hamilton D. , Donaldson Kelly H. , Gaul Michael , Griffin Robert J. , Hassell Anne M. , Keith Barry , Mullin Robert , Petrov Kimberly G. , Reno Michael J. , Rusnak David W. , Tadepalli Sarva M. , Ulrich John C. , Wagner Craig D. , Vanderwall Dana E. , Waterson Alex G. , Williams Jon D. , White Wendy L. , Uehling David E.
Published: February 2008

Analysis of the x-ray crystal structure of mono-substituted acetylenic thienopyrimidine 6 complexed with the ErbB family enzyme ErbB-4 revealed a covalent bond between the terminal carbon of the acetylene moiety and the sulfhydryl group of Cys-803 at the solvent interface. The identification of this covalent adduct suggested that acetylenic thienopyrimidine 6 and related analogs might also be capable of forming an analogous covalent adduct with EGFR, which has a conserved cysteine (797) near the ATP binding pocket. To test this hypothesis, we treated a truncated, catalytically competent form of EGFR (678–1020) with a structurally related propargylic amine (
8
). An investigation of the resulting complex by mass spectrometry revealed the formation of a covalent complex of thienopyrimidine 8 with Cys-797 of EGFR. This finding enabled us to readily assess the irreversibility of various inhibitors and also facilitated a structure–activity relationship understanding of the covalent modifying potential and biological activity of a series of acetylenic thienopyrimidine compounds with potent antitumor activity. Several ErbB family enzyme and cell potent 6-ethynyl thienopyrimidine kinase inhibitors were found to form covalent adducts with EGFR.
Asymmetric segregation of protein aggregates is associated with cellular aging and rejuvenation
Authors: Lindner Ariel B. , Madden Richard , Demarez Alice , Stewart Eric J. , Taddei François
Published: February 2008

Aging, defined as a decrease in reproduction rate with age, is a fundamental characteristic of all living organisms down to bacteria. Yet we know little about the causal molecular mechanisms of aging within the
in vivo
context of a wild-type organism. One of the prominent markers of aging is protein aggregation, associated with cellular degeneracy in many age-related diseases, although its
in vivo
dynamics and effect are poorly understood. We followed the appearance and inheritance of spontaneous protein aggregation within lineages of
Escherichia coli
grown under nonstressed conditions using time-lapse microscopy and a fluorescently tagged chaperone (IbpA) involved in aggregate processing. The fluorescent marker is shown to faithfully identify
in vivo
the localization of aggregated proteins, revealing their accumulation upon cell division in cells with older poles. This accretion is associated with >30% of the loss of reproductive ability (aging) in these cells relative to the new-pole progeny, devoid of parental inclusion bodies, that exhibit rejuvenation. This suggests an asymmetric strategy whereby dividing cells segregate damage at the expense of aging individuals, resulting in the perpetuation of the population.
Independent genesis of chimeric TRIM5-cyclophilin proteins in two primate species
Authors: Virgen Cesar A. , Kratovac Zerina , Bieniasz Paul D. , Hatziioannou Theodora
Published: February 2008

The host range of retroviruses is influenced by antiviral proteins such as TRIM5, a restriction factor that recognizes and inactivates incoming retroviral capsids. Remarkably, in Owl monkeys (omk), a cyclophilin A (CypA) cDNA has been transposed into the TRIM5 locus, resulting in the expression of a TRIM5-CypA fusion protein (TRIMCyp) that restricts retroviral infection based on the retroviral capsid-binding specificity of CypA. Here, we report that the seemingly improbable genesis of TRIMCyp has, in fact, occurred twice, and pigtailed macaques (pgt) express an independently generated TRIMCyp protein. The omkTRIMCyp and pgtTRIMCyp proteins restrict infection by several lentiviruses, but their specificities are distinguishable. Surprisingly, pgtTRIMCyp cannot bind to or restrict HIV-1 capsids as a consequence of a point mutation close to the Cyp:capsid-binding interface that was acquired during or after transposition of pgtCypA. However, the same mutation confers on pgtTRIMCyp the ability to restrict FIV in the presence of cyclosporin A, a drug that normally abolishes the interaction between pgtTRIMCyp or omkTRIMCyp and lentiviral capsids. Overall, an intuitively unlikely evolutionary event has, in fact, occurred at least twice in primates and represents a striking example of convergent evolution in divergent species.
Fine structure of the promoter–σ region 1.2 interaction
Authors: Haugen Shanil P. , Ross Wilma , Manrique Michele , Gourse Richard L.
Published: February 2008

We recently proposed that a nontemplate strand base in the discriminator region of bacterial promoters, the region between the −10 element and the transcription start site, makes sequence-specific contacts to region 1.2 of the σ subunit of
Escherichia coli
RNA polymerase (RNAP). Because rRNA promoters contain sequences within the discriminator region that are suboptimal for interaction with σ1.2, these promoters have the kinetic properties required for regulation by the RNAP-binding factors DksA and ppGpp. Here, we use zero-length cross-linking and mutational, kinetic, and footprinting studies to map RNAP interactions with the nontemplate strand bases at the junction of the −10 element and the discriminator region in an unregulated rRNA promoter variant and in the λP
R
promoter. Our studies indicate that nontemplate strand bases adjacent to the −10 element bind within a 9-aa interval in σ1.2 (residues 99–107). We also demonstrate that the downstream-most base on the nontemplate strand of the −10 hexamer cross-links to σ region 2, and not to σ1.2. Our results refine models of RNAP–DNA interactions in the promoter complex that are crucial for regulation of transcription initiation.
Discovery of a selective inhibitor of oncogenic B-Raf kinase with potent antimelanoma activity
Authors: Tsai James , Lee John T. , Wang Weiru , Zhang Jiazhong , Cho Hanna , Mamo Shumeye , Bremer Ryan , Gillette Sam , Kong Jun , Haass Nikolas K. , Sproesser Katrin , Li Ling , Smalley Keiran S. M. , Fong Daniel , Zhu Yong-Liang , Marimuthu Adhirai , Nguyen Hoa , Lam Billy , Liu Jennifer , Cheung Ivana , Rice Julie , Suzuki Yoshihisa , Luu Catherine , Settachatgul Calvin , Shellooe Rafe , Cantwell John , Kim Sung-Hou , Schlessinger Joseph , Zhang Kam Y. J. , West Brian L. , Powell Ben , Habets Gaston , Zhang Chao , Ibrahim Prabha N. , Hirth Peter , Artis Dean R. , Herlyn Meenhard , Bollag Gideon
Published: February 2008

BRAF

V600E

is the most frequent oncogenic protein kinase mutation known. Furthermore, inhibitors targeting “active” protein kinases have demonstrated significant utility in the therapeutic repertoire against cancer. Therefore, we pursued the development of specific kinase inhibitors targeting B-Raf, and the V600E allele in particular. By using a structure-guided discovery approach, a potent and selective inhibitor of active B-Raf has been discovered. PLX4720, a 7-azaindole derivative that inhibits B-Raf
V600E
with an IC
50
of 13 nM, defines a class of kinase inhibitor with marked selectivity in both biochemical and cellular assays. PLX4720 preferentially inhibits the active B-Raf
V600E
kinase compared with a broad spectrum of other kinases, and potent cytotoxic effects are also exclusive to cells bearing the V600E allele. Consistent with the high degree of selectivity, ERK phosphorylation is potently inhibited by PLX4720 in B-Raf
V600E
-bearing tumor cell lines but not in cells lacking oncogenic B-Raf. In melanoma models, PLX4720 induces cell cycle arrest and apoptosis exclusively in B-Raf
V600E
-positive cells. In B-Raf
V600E
-dependent tumor xenograft models, orally dosed PLX4720 causes significant tumor growth delays, including tumor regressions, without evidence of toxicity. The work described here represents the entire discovery process, from initial identification through structural and biological studies in animal models to a promising therapeutic for testing in cancer patients bearing B-Raf
V600E
-driven tumors.
The
Foldback
-like element
Galileo
belongs to the
P
superfamily of DNA transposons and is widespread within the
Drosophila
genus
Authors: Marzo Mar , Puig Marta , Ruiz Alfredo
Published: February 2008

Galileo
is the only transposable element (TE) known to have generated natural chromosomal inversions in the genus
Drosophila
. It was discovered in
Drosophila buzzatii
and classified as a
Foldback
-like element because of its long, internally repetitive, terminal inverted repeats (TIRs) and lack of coding capacity. Here, we characterized a seemingly complete copy of
Galileo
from the
D. buzzatii
genome. It is 5,406 bp long, possesses 1,229-bp TIRs, and encodes a 912-aa transposase similar to those of the
Drosophila melanogaster 1360
(
Hoppel
) and
P
elements. We also searched the recently available genome sequences of 12
Drosophila
species for elements similar to
Dbuz\Galileo
by using bioinformatic tools.
Galileo
was found in six species (
ananassae
,
willistoni
,
peudoobscura
,
persimilis
,
virilis
, and
mojavensis
) from the two main lineages within the
Drosophila
genus. Our observations place
Galileo
within the
P
superfamily of cut-and-paste transposons and extend considerably its phylogenetic distribution. The interspecific distribution of
Galileo
indicates an ancient presence in the genus, but the phylogenetic tree built with the transposase amino acid sequences contrasts significantly with that of the species, indicating lineage sorting and/or horizontal transfer events. Our results also suggest that
Foldback
-like elements such as
Galileo
may evolve from DNA-based transposon ancestors by loss of the transposase gene and disproportionate elongation of TIRs.
Immunologic and clinical effects of antibody blockade of cytotoxic T lymphocyte-associated antigen 4 in previously vaccinated cancer patients
Authors: Hodi F. Stephen , Butler Marcus , Oble Darryl A. , Seiden Michael V. , Haluska Frank G. , Kruse Andrea , MacRae Suzanne , Nelson Marybeth , Canning Christine , Lowy Israel , Korman Alan , Lautz David , Russell Sara , Jaklitsch Michael T. , Ramaiya Nikhil , Chen Teresa C. , Neuberg Donna , Allison James P. , Mihm Martin C. , Dranoff Glenn
Published: February 2008

Cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) functions as a negative regulator of endogenous and vaccine-induced antitumor immunity. The administration of fully human anti-CTLA-4 blocking monoclonal antibodies to advanced-cancer patients increases immune-mediated tumor destruction in some subjects. Nonetheless, patients that respond also frequently manifest serious inflammatory pathologies, raising the possibility that the therapeutic and toxic effects of CTLA-4 blockade might be linked. Here we show that periodic infusions of anti-CTLA-4 antibodies after vaccination with irradiated, autologous tumor cells engineered to secrete GM-CSF (GVAX) generate clinically meaningful antitumor immunity without grade 3 or 4 toxicity in a majority of metastatic melanoma patients. The application of this sequential immunotherapy to advanced ovarian carcinoma patients also revealed that tumor destruction and severe inflammatory pathology could be dissociated, although further refinements are required to increase clinical responses and to minimize toxicity in this population. The extent of therapy-induced tumor necrosis was linearly related to the natural logarithm of the ratio of intratumoral CD8
+
effector T cells to FoxP3
+
regulatory T cells (Tregs) in posttreatment biopsies. Together, these findings help clarify the immunologic and clinical effects of CTLA-4 antibody blockade in previously vaccinated patients and raise the possibility that selective targeting of antitumor Tregs may constitute a complementary strategy for combination therapy.
Ultrasonic vocalization impairment of Foxp2 (R552H) knockin mice related to speech-language disorder and abnormality of Purkinje cells
Authors: Fujita Eriko , Tanabe Yuko , Shiota Akira , Ueda Masatsugu , Suwa Kiyotaka , Momoi Mariko Y. , Momoi Takashi
Published: February 2008

Previous studies have demonstrated that mutation in the forkhead domain of the forkhead box P2 (FOXP2) protein (R553H) causes speech-language disorders. To further analyze FOXP2 function in speech learning, we generated a knockin (KI) mouse for Foxp2 (R552H) [Foxp2 (R552H)-KI], corresponding to the human FOXP2 (R553H) mutation, by homologous recombination. Homozygous Foxp2 (R552H)-KI mice showed reduced weight, immature development of the cerebellum with incompletely folded folia, Purkinje cells with poor dendritic arbors and less synaptophysin immunoreactivity, and achieved crisis stage for survival 3 weeks after birth. At postnatal day 10, these mice also showed severe ultrasonic vocalization (USV) and motor impairment, whereas the heterozygous Foxp2 (R552H)-KI mice exhibited modest impairments. Similar to the wild-type protein, Foxp2 (R552H) localized in the nuclei of the Purkinje cells and the thalamus, striatum, cortex, and hippocampus (CA1) neurons of the homozygous Foxp2 (R552H)-KI mice (postnatal day 10), and some of the neurons showed nuclear aggregates of Foxp2 (R552H). In addition to the immature development of the cerebellum, Foxp2 (R552H) nuclear aggregates may further compromise the function of the Purkinje cells and cerebral neurons of the homozygous mice, resulting in their death. In contrast, heterozygous Foxp2 (R552H)-KI mice, which showed modest impairment of USVs with different USV qualities and which did not exhibit nuclear aggregates, should provide insights into the common molecular mechanisms between the mouse USV and human speech learning and the relationship between the USV and motor neural systems.
JNK MAP kinase activation is required for MTOC and granule polarization in NKG2D-mediated NK cell cytotoxicity
Authors: Li Changlin , Ge Baoxue , Nicotra Matthew , Stern Joel N. H. , Kopcow Hernan D. , Chen Xi , Strominger Jack L.
Published: February 2008

Interaction of the activating receptor NKG2D with its ligands is a major stimulatory pathway for cytotoxicity of natural killer (NK) cells. Here, the signaling pathway involved after NKG2D ligation is examined. Either incubation of the NKG2D-bearing human NKL tumor cell line with K562 target cells or cross-linking with NKG2D mAb induced strong activation of the mitogen-activated protein (MAP) kinases. Selective inhibition of JNK MAP kinase with four different means of inhibition greatly reduced NKG2D-mediated cytotoxicity toward target cells and furthermore, blocked the movement of the microtubule organizing center (MTOC), granzyme B (a component of cytotoxic granules), and paxillin (a scaffold protein) to the immune synapse. NKG2D-induced activation of JNK kinase was also blocked by inhibitors of Src protein tyrosine kinases and phospholipase PLCγ, upstream of JNK. Similarly, a second MAP kinase pathway through ERK was previously shown to be required for NK cell cytotoxicity. Thus, activation of two MAP kinase pathways is required for cytotoxic granule and MTOC polarization and for cytotoxicity of human NK cells when NKG2D is ligated.
NEMO recognition of ubiquitinated Bcl10 is required for T cell receptor-mediated NF-κB activation
Authors: Wu Chuan-Jin , Ashwell Jonathan D.
Published: February 2008

The mechanism by which the Carma1–Bcl10–MALT1 (CBM) complex couples T cell antigen receptor (TCR) signaling to IκB kinase (IKK) and NF-κB activation is not known. Here, we show that Bcl10 undergoes K63-linked polyubiquitination in response to T cell activation and subsequently binds NEMO, the regulatory subunit of IKK. This interaction requires the ubiquitin-binding activity of NEMO. The sites of Bcl10 ubiquitination were mapped to K31 and K63. Mutation of these residues did not affect TCR signaling-induced CBM complex assembly but prevented Bcl10 ubiquitination, NEMO binding, and NF-κB activation. Therefore, the regulated ubiquitination of Bcl10 and its recognition by NEMO are a critical link between the CBM complex, IKK recruitment, and NF-κB activation.
A systems biology approach identifies the biochemical mechanisms regulating monoterpenoid essential oil composition in peppermint
Authors: Rios-Estepa Rigoberto , Turner Glenn W. , Lee James M. , Croteau Rodney B. , Lange B. Markus
Published: February 2008

The integration of mathematical modeling and experimental testing is emerging as a powerful approach for improving our understanding of the regulation of metabolic pathways. In this study, we report on the development of a kinetic mathematical model that accurately simulates the developmental patterns of monoterpenoid essential oil accumulation in peppermint (Mentha×piperita). This model was then used to evaluate the biochemical processes underlying experimentally determined changes in the monoterpene pathway under low ambient-light intensities, which led to an accumulation of the branchpoint intermediate (+)-pulegone and the side product (+)-menthofuran. Our simulations indicated that the environmentally regulated changes in monoterpene profiles could only be explained when, in addition to effects on biosynthetic enzyme activities, as yet unidentified inhibitory effects of (+)-menthofuran on the branchpoint enzyme pulegone reductase (PR) were assumed. Subsequentin vitroanalyses with recombinant protein confirmed that (+)-menthofuran acts as a weak competitive inhibitor of PR (Ki= 300 μM). To evaluate whether the intracellular concentration of (+)-menthofuran was high enough for PR inhibitionin vivo, we isolated essential oil-synthesizing secretory cells from peppermint leaves and subjected them to steam distillations. When peppermint plants were grown under low-light conditions, (+)-menthofuran was selectively retained in secretory cells and accumulated to very high levels (up to 20 mM), whereas under regular growth conditions, (+)-menthofuran levels remained very low (<400 μM). These results illustrate the utility of iterative cycles of mathematical modeling and experimental testing to elucidate the mechanisms controlling flux through metabolic pathways.
Acute regulation of aquaporin-2 phosphorylation at Ser-264 by vasopressin
Authors: Fenton Robert A. , Moeller Hanne B. , Hoffert Jason D. , Yu Ming-Jiun , Nielsen Søren , Knepper Mark A.
Published: February 2008

By phosphoproteome analysis, we identified a phosphorylation site, serine 264 (pS264), in the COOH terminus of the vasopressin-regulated water channel, aquaporin-2 (AQP2). In this study, we examined the regulation of AQP2 phosphorylated at serine 264 (pS264–AQP2) by vasopressin, using a phospho-specific antibody (anti-pS264). Immunohistochemical analysis showed pS264–AQP2 labeling of inner medullary collecting duct (IMCD) from control mice, whereas AQP2 knockout mice showed a complete absence of labeling. In rat and mouse, pS264–AQP2 was present throughout the collecting duct system, from the connecting tubule to the terminal IMCD. Immunogold electron microscopy, combined with double-labeling confocal immunofluorescence microscopy with organelle-specific markers, determined that the majority of pS264 resides in compartments associated with the plasma membrane and early endocytic pathways. In Brattleboro rats treated with [deamino-Cys-1,
d
-Arg-8]vasopressin (dDAVP), the abundance of pS264–AQP2 increased 4-fold over controls. Additionally, dDAVP treatment resulted in a time-dependent change in the distribution of pS264 from predominantly intracellular vesicles, to both the basolateral and apical plasma membranes. Sixty minutes after dDAVP exposure, a proportion of pS264–AQP2 was observed in clathrin-coated vesicles, early endosomal compartments, and recycling compartments, but not lysosomes. Overall, our results are consistent with a dynamic effect of AVP on the phosphorylation and subcellular distribution of AQP2.
Single mutations convert an outward K
+
channel into an inward K
+
channel
Authors: Li Legong , Liu Kun , Hu Yong , Li Dongping , Luan Sheng
Published: February 2008

Shaker-type K
+
channels in plants display distinct voltage-sensing properties despite sharing sequence and structural similarity. For example, an
Arabidopsis
K
+
channel (SKOR) and a tomato K
+
channel (LKT1) share high amino acid sequence similarity and identical domain structures; however, SKOR conducts outward K
+
current and is activated by positive membrane potentials (depolarization), whereas LKT1 conducts inward current and is activated by negative membrane potentials (hyperpolarization). The structural basis for the “opposite” voltage-sensing properties of SKOR and LKT1 remains unknown. Using a screening procedure combined with random mutagenesis, we identified in the SKOR channel single amino acid mutations that converted an outward-conducting channel into an inward-conducting channel. Further domain-swapping and random mutagenesis produced similar results, suggesting functional interactions between several regions of SKOR protein that lead to specific voltage-sensing properties. Dramatic changes in rectifying properties can be caused by single amino acid mutations, providing evidence that the inward and outward channels in the Shaker family from plants may derive from the same ancestor.
A virocidal amphipathic α-helical peptide that inhibits hepatitis C virus infection
in vitro
Authors: Cheng Guofeng , Montero Ana , Gastaminza Pablo , Whitten-Bauer Christina , Wieland Stefan F. , Isogawa Masanori , Fredericksen Brenda , Selvarajah Suganya , Gallay Philippe A. , Ghadiri M. Reza , Chisari Francis V.
Published: February 2008

An amphipathic α-helical peptide (C5A) derived from the membrane anchor domain of the hepatitis C virus (HCV) NS5A protein is virocidal for HCV at submicromolar concentrations
in vitro
. C5A prevents
de novo
HCV infection and suppresses ongoing infection by inactivating both extra- and intracellular infectious particles, and it is nontoxic
in vitro
and
in vivo
at doses at least 100-fold higher than required for antiviral activity. Mutational analysis indicates that C5A's amphipathic α-helical structure is necessary but not sufficient for its virocidal activity, which depends on its amino acid composition but not its primary sequence or chirality. In addition to HCV, C5A inhibits infection by selected flaviviruses, paramyxoviruses, and HIV. These results suggest a model in which C5A destabilizes viral membranes based on their lipid composition, offering a unique therapeutic approach to HCV and other viral infections.
HSP90/70 chaperones are required for rapid nucleosome removal upon induction of the GAL genes of yeast
Authors: Floer Monique , Bryant Gene O. , Ptashne Mark
Published: February 2008

Induction of transcription of the GAL genes of yeast by galactose is a multistep process: Galactose frees the activator Gal4 of its inhibitor, Gal80, allowing Gal4 to recruit proteins required to transcribe the GAL genes. Here, we show that deletion of components of either the HSP90 or the HSP70 chaperone machinery delays this induction. This delay remains when the galactose-signaling pathway is bypassed, and it cannot be explained by a chaperone requirement for DNA binding by Gal4. Removal of promoter-bound nucleosomes is delayed in a chaperone mutant, and our findings suggest an involvement of HSP90 and HSP70 in this early step in gene induction.
miR-17-92 cluster accelerates adipocyte differentiation by negatively regulating tumor-suppressor Rb2/p130
Authors: Wang Qiang , Li Yan Chun , Wang Jinhua , Kong Juan , Qi Yuchen , Quigg Richard J. , Li Xinmin
Published: February 2008

Adipogenesis involves cell proliferation and differentiation, both of which have been shown to be regulated by micro (mi)RNA. During mouse preadipocyte 3T3L1 cell differentiation, we found that miR-17-92, a miRNA cluster that promotes cell proliferation in various cancers, was significantly up-regulated at the clonal expansion stage of adipocyte differentiation. Stable transfection of 3T3L1 cells with miR-17-92 resulted in accelerated differentiation and increased triglyceride accumulation after hormonal stimulation. By using a luciferase reporter assay, we demonstrated that miR-17-92 directly targeted the 3′ UTR region of Rb2/p130, accounting for subsequently reduced Rb2/p130 mRNA and protein quantities at the stage of clonal expansion. siRNA-mediated knock-down of Rb2/p130 at the same stage of clonal expansion recapitulated the phenotype of overexpression of miR-17-92 in the stably transfected 3T3L1 cells. These data indicate that miR-17-92 promotes adipocyte differentiation by targeting and negatively regulating Rb2/p130.
Paralemmin-1, a Modulator of Filopodia Induction Is Required for Spine Maturation
Authors: Arstikaitis Pamela , Gauthier-Campbell Catherine , Carolina Gutierrez Herrera Rosario , Huang Kun , Levinson Joshua N. , Murphy Timothy H. , Kilimann Manfred W. , Sala Carlo , Colicos Michael A. , El-Husseini Alaa
Published: February 2008

Dendritic filopodia are thought to participate in neuronal contact formation and development of dendritic spines; however, molecules that regulate filopodia extension and their maturation to spines remain largely unknown. Here we identify paralemmin-1 as a regulator of filopodia induction and spine maturation. Paralemmin-1 localizes to dendritic membranes, and its ability to induce filopodia and recruit synaptic elements to contact sites requires protein acylation. Effects of paralemmin-1 on synapse maturation are modulated by alternative splicing that regulates spine formation and recruitment of AMPA-type glutamate receptors. Paralemmin-1 enrichment at the plasma membrane is subject to rapid changes in neuronal excitability, and this process controls neuronal activity-driven effects on protrusion expansion. Knockdown of paralemmin-1 in developing neurons reduces the number of filopodia and spines formed and diminishes the effects of Shank1b on the transformation of existing filopodia into spines. Our study identifies a key role for paralemmin-1 in spine maturation through modulation of filopodia induction.
Evolution of pleiotropic alleles for maturation and size as a consequence of predation
Authors: Basolo Alexandra L
Published: February 2008

Understanding life-history evolution requires knowledge about genetic interactions, physiological mechanisms and the nature of selection. For platyfish,
Xiphophorus maculatus
, extensive information is available about genetic and physiological mechanisms influencing life-history traits. In particular, alleles at the pituitary locus have large and antagonistic effects on age and size at sexual maturation. To examine how predation affects the evolution of these antagonistic traits, I examined pituitary allele evolution in experimental populations differing in predation risk. A smaller size, earlier maturation allele increased in frequency when predators were absent, while a larger size, later maturation allele increased in frequency when predators were present. Thus, predation favours alleles for larger size, at the cost of later maturation and reproduction. These findings are interesting for several reasons. First, predation is often predicted to favour early reproduction at smaller sizes. Second, few studies have shown how selection acts on alleles that affect age and size at sexual maturation. Finally, many studies assume that trade-offs between these life-history traits result from antagonistic pleiotropy, with alleles that positively affect one trait negatively affecting another, yet this is rarely known. This study unequivocally demonstrates that genetically based trade-offs affect life-history evolution in platyfish.
Long-term viability of coronary artery smooth muscle cells on poly(
l
-lactide-
co
-ϵ-caprolactone) nanofibrous scaffold indicates its potential for blood vessel tissue engineering
Authors: Dong Yixiang , Yong Thomas , Liao Susan , Chan Casey K , Ramakrishna S
Published: February 2008

Biodegradable polymer nanofibres have been extensively studied as cell culture scaffolds in tissue engineering. However, long-term
in vitro
studies of cell–nanofibre interactions were rarely reported and successful organ regeneration using tissue engineering techniques may take months (e.g. blood vessel tissue engineering). Understanding the long-term interaction between cells and nanofibrous scaffolds (NFS) is crucial in material selection, design and processing of the tissue engineering scaffolds. In this study, poly(
l
-lactide-
co
-ϵ-caprolactone) [P(LLA-CL)] (70 : 30) copolymer NFS were produced by electrospinning. Porcine coronary artery smooth muscle cells (PCASMCs) were seeded and cultured on the scaffold to evaluate cell–nanofibre interactions for up to 105 days. A favourable interaction between this scaffold and PCASMCs was demonstrated by cell viability assay, scanning electron microscopy, histological staining and extracellular matrix (ECM) secretion. Degradation behaviours of the scaffolds with or without PCASMC culture were determined by mechanical testing and gel permeation chromatography (GPC). The results showed that the PCASMCs attached and proliferated well on the P(LLA-CL) NFS. Large amount of ECM protein secretion was observed after 50 days of culture. Multilayers of aligned oriented PCASMCs were formed on the scaffold after two months of
in vitro
culture. In the degradation study, the PCASMCs were not shown to significantly increase the degradation rate of the scaffolds for up to 105 days of culture. The
in vitro
degradation time of the scaffold could be as long as eight months by extrapolating the results from GPC. These observations further supported the potential use of the P(LLA-CL) nanofibre in blood vessel tissue engineering.
High strain rate properties of a polymer-bonded sugar: their dependence on applied and internal constraints
Authors: Siviour C.R , Laity P.R , Proud W.G , Field J.E , Porter D , Church P.D , Gould P , Huntingdon-Thresher W
Published: February 2008

This paper describes research performed on a polymer-bonded sugar (PBS) consisting of 66% caster sugar in a hydroxyl-terminated polybutadiene (HTPB) binder The mechanical response of the PBS and pure HTPB to applied loading at a strain rate of approximately 2000 s−1at temperatures from −80 to +22°C is presented. The materials were also characterized using dynamic mechanical analysis, X-ray tomography and quasi-static loading. These measurements are required for the development of intermediate strain rate constitutive models of polymer-bonded explosives, for which PBSs are a commonly used mechanical simulant.

The current constitutive modelling suffers from a lack of experimental data on well-characterized composites and binders, especially at intermediate strain rates. This is particularly important for understanding the effects of mixing two materials. Applications of such modelling include explosive safety and fundamental understanding of the various deformation mechanisms. In this paper, the dependences of strength and deformation mechanism on temperature, and, in particular, the glass transition temperature of the binder, are shown. Physical damage plays an important role; X-ray tomography scans support debonding as the primary form of damage during room-temperature deformation. These results are in agreement with previous investigations and are discussed in this context.
Adhesion of an elastic plate to a sphere
Authors: Majidi Carmel , Fearing Ronald S
Published: February 2008

Stationary principles and the von Kármán plate theory are used to study the adhesion of thin elastic plates to a rigid sphere. Contact requires both flexural and membrane strains that can lead to partial or complete delamination. Interestingly, whereas a large area plate might spontaneously delaminate from the sphere, dividing this plate into many smaller plates with equivalent thickness eliminates membrane strains and may allow complete contact. The theoretical predictions are compared to experimental results for low density polyethylene on a smooth glass sphere. The peel strength is estimated with a modified Kendall peel equation.
Restricted dispersal reduces the strength of spatial density dependence in a tropical bird population
Authors: Burgess Malcolm D , Nicoll Malcolm A.C , Jones Carl G , Norris Ken
Published: February 2008

Spatial processes could play an important role in density-dependent population regulation because the disproportionate use of poor quality habitats as population size increases is widespread in animal populations—the so-called buffer effect. While the buffer effect patterns and their demographic consequences have been described in a number of wild populations, much less is known about how dispersal affects distribution patterns and ultimately density dependence. Here, we investigated the role of dispersal in spatial density dependence using an extraordinarily detailed dataset from a reintroduced Mauritius kestrel (
Falco punctatus
) population with a territorial (despotic) breeding system. We show that recruitment rates varied significantly between territories, and that territory occupancy was related to its recruitment rate, both of which are consistent with the buffer effect theory. However, we also show that restricted dispersal affects the patterns of territory occupancy with the territories close to release sites being occupied sooner and for longer as the population has grown than the territories further away. As a result of these dispersal patterns, the strength of spatial density dependence is significantly reduced. We conclude that restricted dispersal can modify spatial density dependence in the wild, which has implications for the way population dynamics are likely to be impacted by environmental change.
On status badges and quality signals in the paper waspPolistes dominulus: body size, facial colour patterns and hierarchical rank
Authors: Cervo R , Dapporto L , Beani L , Strassmann J.E , Turillazzi S
Published: February 2008

To establish a dominance order, social animals often rely on indicators of fighting to avoid costly aggressive encounters. In some species, individuals use colour patterns to signal their social status. Recent studies claimed that facial markings in the eusocial paper waspPolistes dominulusare status badges that allow co-foundresses to form a linear hierarchy based on individual quality. Here, we evaluated facial patterns in natural populations ofP. dominulus, in its native range, to observe whether the marks reflect overall wasp quality in different contexts. We used the same measures of clypeus patterns used by earlier studies, but did not find that they functioned as status badges. Our analyses showed no evidence that visual markers are related to: (i) size, (ii) probability of surviving winter, (iii) social rank in spring associations, or (iv) health status (assessed by the presence of strepsipteran endoparasites). Size, however, is important. Larger wasps are more likely to survive the winter and to acquire the dominant position in spring associations. Larvae infected with endoparasites become smaller adult wasps. These findings suggest that body size is a reliable quality indicator on which wasps build their social networks, and that clypeus patterning is not involved.
Out of Amazonia again and again: episodic crossing of the Andes promotes diversification in a lowland forest flycatcher
Authors: Miller Matthew J , Bermingham Eldredge , Klicka John , Escalante Patricia , do Amaral Fabio S. Raposo , Weir Jason T , Winker Kevin
Published: February 2008

Most Neotropical lowland forest taxa occur exclusively on one side of the Andes despite the availability of appropriate habitat on both sides. Almost all molecular phylogenies and phylogenetic analyses of species assemblages (i.e. area cladograms) have supported the hypothesis that Andean uplift during the Late Pliocene created a vicariant barrier affecting lowland lineages in the region. However, a few widespread plant and animal species occurring in lowland forests on both sides of the Andes challenge the generality of this hypothesis. To understand the role of the Andes in the history of such organisms, we reconstructed the phylogeographic history of a widespread Neotropical flycatcher (
Mionectes oleagineus
) in the context of the other four species in the genus. A molecular phylogeny based on nuclear and mitochondrial sequences unambiguously showed an early basal split between montane and lowland
Mionectes
. The phylogeographic reconstruction of lowland taxa revealed a complex history, with multiple cases in which geographically proximate populations do not represent sister lineages. Specifically, three populations of
M. oleagineus
west of the Andes do not comprise a monophyletic clade; instead, each represents an independent lineage with origins east of the Andes. Divergence time estimates suggest that at least two cross-Andean dispersal events post-date Andean uplift.
A quadruplex real-time PCR assay for the detection of Yersinia pestis and its plasmids
Authors: Stewart Alvin , Satterfield Benjamin , Cohen Marissa , O'Neill Kim , Robison Richard
Published: February 2008

Yersinia pestis, the aetiological agent of the plague, causes sporadic disease in endemic areas of the world and is classified as a National Institute of Allergy and Infectious Diseases Category A Priority Pathogen because of its potential to be used as a bioweapon. Health departments, hospitals and government agencies need the ability to rapidly identify and characterize cultured isolates of this bacterium. Assays have been developed to perform this function; however, they are limited in their ability to distinguish Y. pestis from Yersinia pseudotuberculosis. This report describes the creation of a real-time PCR assay using Taqman probes that exclusively identifies Y. pestis using a unique target sequence of the yihN gene on the chromosome. As with other Y. pestis PCR assays, three major genes located on each of the three virulence plasmids were included: lcrV on pCD1, caf1 on pMT1 and pla on pPCP1. The quadruplex assay was validated on a collection of 192 Y. pestis isolates and 52 near-neighbour isolates. It was discovered that only 72 % of natural plague isolates from the states of New Mexico and Utah harboured all three virulence plasmids. This quadruplex assay proved to be 100 % successful in differentiating Y. pestis from all near neighbours tested and was able to reveal which of the three virulence plasmids a particular isolate possessed.
Streptococcus equi subsp. zooepidemicus meningitis
Authors: Jovanović M. , Stevanović G. , Tošić T. , Stošović B. , Zervos M. J.
Published: February 2008

A 72-year-old woman was hospitalized for Streptococcus equi subsp. zooepidemicus meningitis. The same organism was cultured from her two horses. She denied contact with horses, but had a practice of consuming unpasteurized milk from a cow. The cow was in the same stable as the horses, and the ill woman's son milked the cow.
A comparative study of three different PCR assays for detection of Mycoplasma genitalium in urogenital specimens from men and women
Authors: Edberg Andreas , Jurstrand Margaretha , Johansson Eva , Wikander Elisabeth , Höög Anna , Ahlqvist Thomas , Falk Lars , Jensen Jørgen Skov , Fredlund Hans
Published: February 2008

The aim of this study was to compare conventional 16S rRNA gene PCR, real-time 16S rRNA gene PCR and real-time Mycoplasma genitalium adhesin protein (MgPa) gene PCR as detection methods for M. genitalium infection. The study also determined the prevalence of M. genitalium in male and female patients attending a sexually transmitted infections clinic in a rural area in the west of Sweden. First void urine (FVU) and/or urethral swabs were collected from 381 men, and FVU and/or cervical swabs and/or urethral swabs were collected from 298 women. A total of 213 specimens were used in the PCR comparative study: 98 consecutively sampled specimens from patients enrolled in the prevalence study, 36 consecutively sampled specimens from patients with symptoms of urethritis and 79 specimens from patients positive for M. genitalium by real-time MgPa gene PCR in the prevalence study. A true-positive M. genitalium DNA specimen was defined as either a specimen positive in any two PCR assays or a specimen whose PCR product was verified by DNA sequencing. The prevalence of M. genitalium infection in men and women was 27/381 (7.1 %) and 23/298 (7.7 %), respectively. In the PCR comparative study, M. genitalium DNA was detected in 61/76 (80.3 %) of true-positive specimens by conventional 16S rRNA gene PCR, in 52/76 (68.4 %) by real-time 16S rRNA gene PCR and in 74/76 (97.4 %) by real-time MgPa gene PCR. Real-time MgPa gene PCR thus had higher sensitivity compared with conventional 16S rRNA gene PCR and had considerably increased sensitivity compared with real-time 16S rRNA gene PCR for detection of M. genitalium DNA. Real-time MgPa gene PCR is well suited for the clinical diagnosis of M. genitalium.
Legionnaires' disease in immunocompromised patients: a case report of Legionella longbeachae pneumonia and review of the literature
Authors: Kümpers Philipp , Tiede Andreas , Kirschner Philip , Girke Jutta , Ganser Arnold , Peest Dietrich
Published: February 2008

In addition to Legionella pneumophila, about 20 Legionella species have been documented as human pathogens. The majority of infections by non-pneumophila
Legionella species occur in immunocompromised and splenectomized patients. Here, we report a case of ‘classical’ lobar pneumonia caused by Legionella longbeachae in a splenectomized patient receiving corticosteroids for chronic immune thrombocytopenia. Tests for Legionella antigen were negative. L. longbeachae was immediately detected in bronchoalveolar fluid by PCR and subsequently confirmed by culture on legionella-selective media. The features of Legionnaires' disease in immunocompromised patients with special emphasis on significance and detection of non-pneumophila species are reviewed.
Analysis of meticillin-susceptible and meticillin-resistant biofilm-forming Staphylococcus aureus from catheter infections isolated in a large Italian hospital
Authors: Petrelli Dezemona , Repetto Antonella , D'Ercole Stefania , Rombini Silvia , Ripa Sandro , Prenna Manuela , Vitali Luca Agostino
Published: February 2008

Several characteristics were analysed in 37 Staphylococcus aureus isolates from nosocomial catheter infections: the PFGE profile after SmaI digestion of chromosomal DNA, the ability to form a biofilm on a polystyrene surface, antibiotic susceptibility patterns (penicillin, oxacillin, erythromycin, tetracycline, clindamycin, telithromycin, gentamicin, ciprofloxacin, quinupristin/dalfopristin, rifampicin, vancomycin and linezolid), and the presence of genetic determinants of antibiotic resistance and biofilm formation. All strains but three (92 %) were able to grow on a plastic surface as a biofilm. An almost complete association was found between phenotypes and genotypic traits of antibiotic resistance, whilst PFGE profiling showed the highly polyclonal composition of the set of strains under study. Sixteen isolates (43 %) were meticillin-resistant and were subjected to staphylococcal cassette chromosome mec (SCCmec) and cassette chromosome recombinase (ccr) complex type determination by multiplex PCR. Only a subgroup of six strains belonged to the archaic clone PFGE type and bore the SCCmec/ccrAB type I structure. Among the remaining strains some presented small rearrangements of the SCCmec/ccrAB genetic locus, whilst others could barely be traced back to a known structural type. These observations suggest that, at the local level and at a particular site of infection, S. aureus may show great genetic variability and escape the general rule of expansion of the S. aureus pandemic clones.