bluuebunny/crossref_metadata_2025 huggingface dataset:
In Vivo Imaging of T Cell PrimingA presentation from the 11th Joint Meeting of the Signal Transduction Society (STS), Signal Transduction: Receptors, Mediators and Genes, Weimar, Germany, 1 to 3 November 2007.
Authors: Henrickson Sarah E. , Mempel Thorsten R. , Mazo Irina B. , Liu Bai , Artyomov Maxim N. , Zheng Huan , Peixoto Antonio , Flynn Michael , Senman Balimkiz , Junt Tobias , Wong Hing C. , Chakraborty Arup K. , von Andrian Ulrich H.
Published: June 2008

The rules by which naïve T cells decide whether and how to respond to antigenic stimuli are incompletely understood. Using multiphoton intravital microscopy (MP-IVM) in lymph nodes (LNs), we have shown that CD8
+
T cells are primed by antigen-presenting dendritic cells (DCs) in three consecutive phases. During phase one, T cells undergo brief serial contacts with many DCs for several hours after homing into the LNs. Subsequently, during phase two, T cells engage in prolonged stable interactions with DCs. Finally, in the third phase, T cells return to transient interactions with DCs as they begin to proliferate and eventually leave the LNs. We have examined the influence of antigen dose on the duration of phase one by systematically varying both the number of cognate peptide–major histocompatability (pMHC) complexes per DC and the density of cognate pMHC complex–presenting DCs per LN. The duration of phase one and the kinetics of CD8
+
T cell activation were inversely correlated with both parameters. Very few pMHC complexes were needed for full T cell activation and effector differentiation. Furthermore, there was a sharp threshold of antigen dose below which T cells did not transition to phase two but continued to migrate until they exited the LN, unactivated. The stability of peptide binding to MHC was a critical determinant of this threshold antigen dose in vivo. Our results suggest an integrative mechanism that allows T cells to reach an informed decision about whether to respond, based on the overall antigen dose encountered.
What’s So Exciting About Glia?
Authors: Adler Elizabeth M.
Published: June 2008

Káradóttir
et al
. present intriguing data suggesting that, contrary to long-accepted dogma, a class of glial cells can generate action potentials. Neurons and glia constitute the two classes of cell found in neural tissue, with inability to produce action potentials a defining feature that distinguishes glia from neurons. Káradóttir
et al
. identified oligodendrocyte precursor glial cells (OPCs) in the white matter of cerebellar slices from young rats on the basis of their morphology and expression of the proteoglycan NG2 and the oligodendrocyte transcription factor Olig2. These NG2- and Olig2-expressing cells did not express the neuronal marker NeuN, nor did they express the astrocyte marker S100β; about half were immunoreactive for Na
+
channels. Whole-cell patch clamp analysis revealed two electrophysiologically distinct classes of OPCs: One class exhibited currents mediated by voltage-gated Na
+
and K
+
channels and generated action potentials in response to depolarization, whereas the other (morphologically indistinguishable) class did not. The two classes of OPCs were also present in adult animals. Most of the excitable OPCs exhibited excitatory postsynaptic currents (EPSCs), inhibitory postsynaptic currents (IPSCs), or both, whereas the vast majority of the inexcitable cells did not. Pharmacological analysis indicated that EPSCs reflected glutamatergic input and that IPSCs were a response to GABA. Glutamate and the glutamate antagonist NMDA elicited larger currents in excitable OPCs than in OPCs that lacked Na
+
channels, and the former were also more susceptible to ischemic death (pertinent to conditions such as stroke or spinal cord injury). Otis and Sofroniew provide thoughtful commentary and discuss the possibility that some NG2-expressing glia may have functions other than acting as OPCs.

R. Káradóttir, N. B. Hamilton, Y. Bakiri, D. Attwell, Spiking and nonspiking classes of oligodendrocyte precursor glia in CNS white matter.
Nat. Neurosci
.
11
, 450-456 (2008).
[PubMed]

T. S. Otis, M.V. Sofroniew, Glia get excited.
Nat. Neurosci.
11
, 379-380 (2008).
[PubMed]
Complexity in the Bacterial Community
Authors: Gough Nancy R.
Published: June 2008

Biofilms are organized communities of bacteria that form on surfaces. The bacterial population of a biofilm exhibits enhanced resistance to environmental stress and antibiotics, which has important implications for the clinic and industry. Vlamakis
et al
. integrated genes for fluorescent markers under the control of various specific promoters into
Bacillus subtilis
to visualize cellular differentiation within a biofilm, to follow cell lineage, and to show that the formation of extracellular matrix was necessary for sporulation within a biofilm. Bacteria expressing P

hag
-yfp

were used to visualize motile cells, those expressing P

yqxM
-yfp

revealed matrix-producing cells, and those expressing P

sspB
-yfp

revealed sporulating cells. Biofilms containing the labeled cells were allowed to form for a period of time and then the cells were dispersed and fluorescence was measured by flow cytometry. At early time points (12 hours), most cells were motile; by 24 hours, the matrix-expressing cells were at a maximum; and by 48 hours, sporulation was readily detected. Thin-section microscopy of the biofilm revealed that the motile cells were at the base and edge of the biofilm, whereas the matrix-expressing cells were distributed in patches throughout the biofilm, and sporulation occurred preferentially in distinct regions called the aerial structures. Cell lineage was monitored by time-lapse microscopy of dual-labeled cells, in which pairwise combinations of variant fluorescent proteins under the control of different promoters were expressed. These assays revealed that motile cells gave rise to matrix-producing cells, which then differentiated to produce sporulating cells. Regions of motile cells in the biofilm were separated from regions of sporulating cells, whereas the regions containing matrix-producing and sporulating cells tended to overlap. Production of extracellular matrix was necessary for proper organization. Biofilms formed from
tasA
mutants that could not produce a critical matrix protein exhibited decreased abundance of motile cells, and their location was aberrant compared with a wild-type biofilm. The population of cells expressing P

yqxM
-yfp

was elevated and, despite sporulating in liquid culture, there were no sporulating cells in biofilms formed by
tasA
mutants. Sporulation in the biofilm was restored if sporulation-deficient but matrix-production-competent cells were mixed with matrix-deficient but sporulation-competent cells. Because nutrient depletion is a stimulus that activates Spo0A, which through direct and indirect mechanisms controls both motility and sporulation, the authors suggested that matrix production may create local regions within the biofilm where nutrients are depleted, thus triggering the sporulation pathway through Spo0A activation.

H. Vlamakis, C. Aguilar, R. Losick, R. Kolter, Control of cell fate by the formation of an architecturally complex bacterial community.
Genes Dev.
22
, 945-953 (2008).
[Abstract]
[Full Text]
Science Signaling
Podcast: 08 April 2008
Authors: Adler Elizabeth M. , Foley John F.
Published: June 2008

This conversation is about research highlighted in Editors' Choice titled "Predisposed to a Long Life?" The highlighted article is Y. Suh, G. Atzmon, M.-O. Cho, D. Hwang, B. Liu, D. J. Leahy, N. Barzilai, P. Cohen, Functionally significant insulin-like growth factor I receptor mutations in centenarians.
Proc. Natl. Acad. Sci. U.S.A.
105
, 3438–3442 (2008). (Length: 7 min; file size: 3.29 MB; file format: mp3; location:
http://podcasts.aaas.org/science_signaling/ScienceSignaling_080408.mp3
)
Radioprotection: Taking the Toll Road
Authors: Kiberstis Paula A.
Published: June 2008

Radiation therapy is a well-established and highly effective treatment for certain types of cancer, but it can destroy healthy cells in the body, especially bone marrow cells and cells in the gastrointestinal tract. Burdelya
et al
. have developed a drug that may prevent or reduce these side effects. The drug (a peptide called CBLB502) binds to Toll-like receptor 5 (TLR5) and activates the nuclear factor κB signaling pathway, a pathway that cancer cells often activate to avoid cell death. When mice and rhesus monkeys were treated with CBLB502 shortly before exposure to lethal doses of total body irradiation, the animals exhibited less damage to healthy bone marrow and gastrointestinal cells and survived significantly longer than controls. In tumor-bearing mice, CBLB502 did not compromise the antitumor efficacy of radiation therapy.

L. G. Burdelya, V. I. Krivokrysenko, T. C. Tallant, E. Strom, A. S. Gleiberman, D. Gupta, O. V. Kurnasov, F. L. Fort, A. L. Osterman, J. A. DiDonato, E. Feinstein, A. V. Gudkov, An agonist of Toll-like receptor 5 has radioprotective activity in mouse and primate models.
Science
320
, 226-230 (2008).
[Abstract]
[Full Text]
Just When You Thought It Was Pseudo
Authors: Foley John F.
Published: June 2008

Approximately 10% of all known kinases are thought to be catalytically inactive because they have modifications of conserved motifs in their kinase domains, leading to their being dubbed pseudokinases. The pseudokinase Ca
2+
/calmodulin (CaM)-activated serine-threonine kinase (CASK) has an altered DFG motif in its N-terminal CaM-kinase domain. This motif is important for the binding of Mg
2+
, which helps to coordinate the binding of ATP, the source of the phosphoryl group for the kinase. CASK binds to synaptic adhesion molecules, including neurexin, and deletion of
CASK
in mice leads to synaptic defects and perinatal death. Mukherjee
et
al
. determined the crystal structure of the CaM-kinase domain of recombinant CASK and compared it with those of other kinases. The N- and C-terminal lobes of the CASK CaM-kinase domain in the absence of ATP were arranged in a similar fashion as those of other kinases when in their active states, indicating that CASK adopts a constitutively active conformation. In vitro experiments showed that a fluorescent ATP analog bound to recombinant CASK in the absence of coordinating Mg
2+
and that the addition of Mg
2+
inhibited this interaction. In vitro kinase assays showed that the CASK CaM-kinase domain exhibited autophosphorylation activity, that the kinetics of this phosphorylation were similar to those of true kinases, and that Mg
2+
and other divalent cations inhibited this activity. Overexpression of wild-type CASK but not a catalytically inactive CASK mutant in rat hippocampal neurons resulted in increased phosphorylation of β-neurexin compared with that in control neurons. As Kannan and Taylor discuss in commentary, this study challenges the idea that pseudokinases act merely as inactive scaffold proteins and should stimulate reinvestigation of their potential catalytic activity.

K. Mukherjee, M. Sharma, H. Urlaub, G. P. Bourenkov, R. Jahn, T. C. Südhof, M. C. Wahl, CASK functions as a Mg
2+
-independent neurexin kinase.
Cell
133
, 328-339 (2008).
[PubMed]

N. Kannan, S. S. Taylor, Rethinking pseudokinases.
Cell
133
, 204-205 (2008).
[PubMed]
Distinctive Individual Smells
Authors: Stern Peter
Published: June 2008

Pheromones are critical for social communication in many animals. A lot of information about an animal’s status is represented in the complex pheromone components in urine. In mice, detection of such complex chemical signals by the vomeronasal organ (VNO) plays an important role in triggering endocrine changes and eliciting stereotyped innate behaviors. However, our mechanistic understanding of how VNO neurons encode information about sex and individuals is still far from complete. He
et al
. developed a system to probe neuronal receptor dynamics using genetically encoded fluorescent sensors. They observed distinct populations of VNO neurons that responded specifically to male and to female urine signals. Mouse strain and individual recognition was determined by combinatorial activation across a population of neurons. Such combinatorial activation was unique, allowing each individual animal to be discriminated and recognized.

J. He, L. Ma, S. Kim, J. Nakai, C. R. Yu, Encoding gender and individual information in the mouse vomeronasal organ.
Science
320
, 535-538 (2008).
[Abstract]
[Full Text]
Exploiting Surface Phosphatidylserine
Authors: Ray L. Bryan , Hurtley Stella M.
Published: June 2008

Many animals use the presence of the phospholipid phosphatidylserine (PS), on the outer leaflet of the plasma membrane, as a way to recognize and destroy apoptotic cells by phagocytic engulfment. In this issue, two papers illustrate the differential roles played by PS in normal cells and during virus infection (see the Perspective by Fairn and Grinstein). Darland-Ransom
et al.
identified an enzyme in
Caenorhabditis elegans
, aminophospholipid translocase 1 (TAT-1), which appears normally to restrict PS to the inner side of the plasma membrane. Animals lacking TAT-1 had increased PS on the cell surface, and random cells were lost from the animals in a process that depended on PSR-1, a PS receptor involved in the clearance of apoptotic cells. Mercer and Helenius used live-cell imaging to follow vaccinia virus entry into tissue culture cells. Viruses first bound to actin-rich cell-surface protrusions, filopodia, along which they surfed to the cell body. At the cell body, the incoming virus stimulated its own uptake due to the presence of PS on the viral membrane, mimicking the uptake of apoptotic cell corpses.

M. Darland-Ransom, X. Wang, C.-L. Sun, J. Mapes, K. Gengyo-Ando, S. Mitani, D. Xue, Role of
C. elegans
TAT-1 protein in maintaining plasma membrane phosphatidylserine asymmetry.
Science
320
, 528-531 (2008).
[Abstract]
[Full Text]

J. Mercer, A. Helenius, Vaccinia virus uses macropinocytosis and apoptotic mimicry to enter host cells.
Science
320
, 531-535 (2008).
[Abstract]
[Full Text]

G. D. Fairn, S. Grinstein, A one-sided signal.
Science
320
, 458-460 (2008).
[Summary]
[Full Text]
Notch Signaling in Osteoblasts
Authors: Canalis Ernesto
Published: June 2008

Bone remodeling is the result of the coordinated activity of osteoblasts, which form new matrix, and osteoclasts, which resorb bone. Notch proteins are single-pass transmembrane receptors that determine cell fate. Recent gain-of-function and loss-of-function experiments reveal a suppressive effect of Notch in osteoblast and osteoclast differentiation in development and in the postnatal bone, which establishes a role for Notch signaling in bone remodeling.
Toxin Targets T Cells
Authors: Ray L. Bryan
Published: June 2008

The compound 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, also referred to as dioxin) is a highly toxic environmental pollutant that acts by regulating a ligand-activated transcription factor known as the aryl hydrocarbon receptor (AHR), for which the endogenous regulatory ligand or ligands remain uncertain. Two papers report that the AHR has an important role in controlling T cell differentiation that could help explain increased prevalence of autoimmune diseases in industrialized countries in which exposure to environmental toxins may be a factor. T cells can differentiate into T
reg
cells, which help keep inflammation in check by inhibiting proliferation of effector cells and secretion of inflammatory cytokines, or T
H
17 cells, which generally promote inflammation. Dioxin exposure suppresses immune responses, but the mechanism has been unclear. Quintana
et al
. made the connection of the AHR to T cell differentiation because the regulatory region near a gene that is highly expressed in T
reg
cells (Foxp3) contained an evolutionarily conserved binding site for the AHR. Veldhoen
et al
. noted that T
H
17 cells specifically expressed AHRs. The latter group showed that activation of AHR increased expression of cytokines by T
H
17 cells in vitro and that, in AHR-deficient mice, production of T
H
17 cells was diminished when they induced experimental autoimmune encephalitis in the animals. Quintana
et al
. went on to show that AHR indeed directly regulated expression of Foxp3. Furthermore, in mice, their experiments showed that the AHR could promote either differentiation of T
reg
or T
H
17 cells, depending on the ligand that was used to activate it. The authors note that this ligand-specific modulation of inflammatory responses could make AHR a particularly valuable therapeutic target for modulation of immune function. Stevens and Bradfield provide commentary.

F. J. Quintana, A. S. Basso, A. H. Iglesias, T. Korn, M. F. Farez, E. Bettelli, M. Caccamo, M. Oukka, H. L. Weiner, Control of T
reg
and T
H
17 cell differentiation by the aryl hydrocarbon receptor.
Nature
453
, 65-71 (2008).
[PubMed]

M. Veldhoen, K. Hirota, A. M. Westendorf, J. Buer, L. Dumoutier, J.-C. Renauld, B. Stockinger, The aryl hydrocarbon receptor links T
H
17-cell-mediated autoimmunity to environmental toxins.
Nature
453
, 106-109 (2008).
[PubMed]

E. A. Stevens, C. A. Bradfield, T cells hang in the balance.
Nature
453
, 46-47 (2008).
[PubMed]
Alternative Activation
Authors: Foley John F.
Published: June 2008

The calcium/calmodulin (Ca
2+
/CaM)-dependent protein kinase II (CaMKII) is activated through the binding of Ca
2+
/CaM to its regulatory domain and plays important roles in the nervous system and the heart. CaMKII activity is also increased under pro-oxidant conditions, so Erickson
et al
. investigated whether reactive oxygen species (ROS) might be involved. Exposure of purified CaMKII to hydrogen peroxide (H
2
O
2
) in the presence, but not absence, of Ca
2+
/CaM resulted in prolonged enzyme activity compared with that of untreated CaMKII. Ca
2+
/CaM-dependent autophosphorylation of Thr
287
is known to prevent the reassociation of the enzyme’s autoinhibitory region with its catalytic domain and so enable prolonged enzyme activity. However, the effect of H
2
O
2
on enzyme activity still occurred with a mutant form of CaMKII in which Thr
287
was mutated to alanine. Mutation of Met
281
and Met
282
in the regulatory domain of CaMKII to valines blocked H
2
O
2
-dependent activation, although Thr
287
autophosphorylation was unaffected. This suggests that Thr
287
phosphorylation and Met
281
/Met
282
oxidation are distinct mechanisms that lead to prolonged CaMKII activation in the presence of Ca
2+
/CaM. The authors developed an antibody against oxidized Met
281
/Met
282
residues and found that the hormone angiotensin II (AngII) increased the abundance of oxidized CaMKII in the hearts of wild-type mice compared with that in untreated mice. AngII induced ROS production and apoptosis in treated cardiomyocytes, which was blocked when CaMKII was knocked down by short hairpin RNA. Finally, the abundance of oxidized CaMKII and the incidence of apoptotic cells were higher in the hearts of AngII-treated mice deficient in MsrA, an enzyme that reverses methionine oxidation, than in AngII-treated wild-type mice. As Griffith notes in commentary, the discovery that ROS directly activate CaMKII may help in our understanding of oxidant-dependent diseases of the heart and nervous system.

J. R. Erickson, M.-l. A. Joiner, X. Guan, W. Kutschke, J. Yang, C. V. Oddis, R. K. Bartlett, J. S. Lowe, S. E. O’Donnell, N. Aykin-Burns, M. C. Zimmerman, K. Zimmerman, A.-J. L. Ham, R. M. Weiss, D. R. Spitz, M. A. Shea, R. J. Colbran, P. J. Mohler, M. E. Anderson, A dynamic pathway for calcium-independent activation of CaMKII by methionine oxidation.
Cell
133
, 462-474 (2008).
[PubMed]

L. C. Griffith, CaMKII: New tricks for an old dog.
Cell
133
, 397-399 (2008).
[PubMed]
Mitochondria as Drivers of Metastasis
Authors: Kiberstis Paula A.
Published: June 2008

Most cancer deaths occur when cells in a primary tumor metastasize, yet the mechanisms by which tumor cells acquire metastatic properties remain poorly understood. Ishikawa
et al.
explored the role of mitochondria in this process by taking mouse tumor cell lines with either a high or low propensity to metastasize and swapping their mitochondrial DNA (mtDNA). Interestingly, the recipient cells acquired the metastatic potential of the cells donating the mtDNA. In one tumor cell line examined in detail, the mtDNA conferring high metastatic potential was found to harbor mutations that led to overproduction of reactive oxygen species (ROS), and up-regulation of nuclear genes involved in metastasis. Pretreatment of tumor cells with ROS scavengers reduced their ability to metastasize in mouse models, suggesting a possible avenue for the development of therapies to suppress metastasis.

K. Ishikawa, K. Takenaga, M. Akimoto, N. Koshikawa, A. Yamaguchi, H. Imanishi, K. Nakada, Y. Honma, J.-I. Hayashi, ROS-generating mitochondrial DNA mutations can regulate tumor cell metastasis.
Science
320
, 661-664 (2008).
[Abstract]
[Full Text]
Science Signaling
Podcast: 06 May 2008
Authors: Adler Elizabeth M. , VanHook Annalisa M.
Published: June 2008

This conversation is about research highlighted in Editors' Choice titled, "What’s So Exciting About Glia?" The highlighted article is R. Káradóttir, N. B. Hamilton, Y. Bakiri, D. Attwell, Spiking and nonspiking classes of oligodendrocyte precursor glia in CNS white matter.
Nat. Neurosci
.
11
, 450–456 (2008). (Length: 6 min; file size: 2.61 MB; file format: mp3; location:
http://podcasts.aaas.org/science_signaling/ScienceSignaling_080506.mp3
)
Prion Protein Protection
Authors: Gough Nancy R.
Published: June 2008

When cellular prion protein (PrP
c
) misfolds into the scrapie form (PrP
Sc
), it is responsible for transmissible spongiform encephalopathies; however, the physiological functions of PrP
c
remain unclear. Studies with mice in which the gene encoding PrP is disrupted revealed that PrP
c
may play a neuroprotective role, as well as contribute to spatial learning. Khosravani
et al
. found that neuronal excitability was increased in hippocampal slices from the PrP-null mice--with increased action potential firing in response to a single stimulus, decreased minimal stimulus required to evoke an action potential, and decreased stimulus intensity required to reach a maximum response. This increased neuronal excitability was blocked by bath application of an antagonist of
N
-methyl-D-aspartate (NMDA)-type glutamate receptors. Primary cultures of PrP-null hippocampal neurons had NMDA receptor-mediated currents with longer decay times and larger amplitudes, and transfection of PrP into the cells restored wild-type kinetics to the response to NMDA, suggesting that PrP acutely regulates NMDA receptor signaling and that loss of PrP was not causing a developmental defect. NMDA receptors may be composed of various subunits with different electrophysiological and pharmacological properties. A comparison of the response of the cultured hippocampal neurons to application of an NR2B-selective inhibitor suggested that the wild-type neurons had a larger proportion of NR2B-containing NMDA receptors. The electrophysiological properties of the NMDA-stimulated responses in the PrP-null neurons were similar to those obtained in studies with heterologously expressed NR2D-containing NMDA receptors. Although the distribution and abundance of NR2D subunits appeared unchanged in the hippocampus of the wild-type and PrP-null mice, knockdown of the NR2D subunit by siRNA techniques in the cultured PrP-null neurons accelerated the decay kinetics and reduced the amplitude of the response to application of NMDA. PrP
c
and NR2D subunits coimmunoprecipitated from wild-type mouse hippocampus, suggesting that PrP
c
may interact with the NR2D-containing receptors and inhibit their activity. Thus, in the absence of PrP
c
, these NR2D-containing receptors contribute more to the response to glutamate--leading to a hyperexcitable phenotype. Both in vivo (focal injection) and in culture (bath application), the absence of PrP
c
was associated with increased neuronal death under conditions in which NMDA is toxic. Thus, one function of PrP
c
appears to be to limit the contribution of NR2D-containing NMDA receptors to hippocampal responses to glutamate signals and thus limit hippocampal excitability.

H. Khosravani, Y. Zhang, S. Tsutsui, S. Hameed, C. Altier, J. Hamid, L. Chen, M. Villemaire, Z. Ali, F. R. Jirik, G. W. Zamponi, Prion protein attenuates excitotoxicity by inhibiting NMDA receptors.
J. Cell Biol.
181
, 551-565 (2008).
[Abstract]
[Full Text]
Wholesale Heat Shock
Authors: Ray L. Bryan
Published: June 2008

Exposure to increased temperature can damage cells, and individual cells respond to heat shock by synthesizing protective chaperone proteins that help maintain proper protein folding. Prahlad
et al
. report experiments in the nematode
Caenorhabditis elegans
that show an organism-wide, rather than cell-autonomous, response to heat shock. Synthesis of heat shock proteins was inhibited in animals carrying mutations that disrupt the function of a sensory neuron previously known to respond to increased temperature and influence behavior. The heat shock response was also altered in response to dauer pheromone, which regulates growth and metabolism. Thus,
C. elegans
appears to possess a regulatory system that coordinates the organismal heat shock response with multiple environmental cues.

V. Prahlad, T. Cornelius, R. I. Morimoto, Regulation of the cellular heat shock response in
Caenorhabditis elegans
by thermosensory neurons.
Science
320
, 811-814 (2008).
[Abstract]
[Full Text]
Interfering with Inflammation
Authors: Foley John F.
Published: June 2008

Multiple sclerosis (MS) is an inflammatory autoimmune disease of the central nervous system (CNS), which causes demyelination of axons. Experimental autoimmune encephalomyelitis (EAE) is a mouse model of MS that is induced by immunizing mice with myelin oligodendrocyte glycoprotein (MOG). The best-known treatment for MS is the type I interferon (IFN), IFN-β; however, its mechanism of action is unclear. Prinz
et
al
. found that the abundance of IFN-β was increased in the CNS of MOG-treated mice compared with untreated mice, as measured by enzyme-linked immunosorbent assays, suggesting that local, but not systemic, IFN-β abundance is important in this disease. Treatment of mice deficient in the type I IFN receptor (
Ifnar
–/–
mice) with MOG resulted in worse disease and increased mortality compared with MOG-treated wild-type mice. Histological examination revealed that MOG-treated
Ifnar
–/–
mice had more infiltrating myeloid cells, which included macrophages and microglia, in their spinal cords than did MOG-treated wild-type mice. The authors bred strains of mice that were
Ifnar
-deficient in specific cell types and exposed them to MOG. Whereas deletion of
Ifnar
in CD4
+
T cells, B cells, astrocytes, or oligodendrocytes had little or no effect on disease outcome, deletion of
Ifnar
in myeloid cells led to exacerbated disease and increased mortality compared with that in wild-type mice. This was associated with the increased uptake of degraded myelin protein by
Ifnar
-deficient myeloid cells and the increased abundance of the proinflammatory cytokine tumor necrosis factor-α and the chemokine CCL2, which recruits myeloid cells. As Axtell and Steinman discuss, this study suggests that IFN-β acts on myeloid cells in the CNS to suppress inflammation and the processing of antigenic peptides, which would otherwise exacerbate disease by activating infiltrating T cells and causing further inflammation.

M. Prinz, H. Schmidt, A. Mildner, K.-P. Knobeloch, U.-K. Hanisch, J. Raasch, D. Merkler, C. Detje, I. Gutcher, J. Mages, R. Lang, R. Martin, R. Gold, B. Becher, W. Brück, U. Kalinke, Distinct and nonredundant in vivo functions of IFNAR on myeloid cells limit autoimmunity in the central nervous system.
Immunity
28
, 675-686 (2008).
[PubMed]

R. C. Axtell, L. Steinman, Type 1 interferons cool the inflamed brain.
Immunity
28
, 600-602 (2008).
[PubMed]
The Logic of Neurite Outgrowth
Authors: Ray L. Bryan
Published: June 2008

Cannabinoid receptor 1 (CB1R) regulates neurite outgrowth, has important functions in central nervous system development, and is a drug target for several diseases. Bromberg
et al
. used a combination of transcriptional profiling on DNA arrays with graph theory analysis of known signaling networks to explore the effects of signaling by the CB1R. Unexpectedly, the analysis predicted that the product of the breast cancer susceptibility gene BRCA1 was likely to regulate transcription factors activated during CB1R-stimulated neurite outgrowth. Furthermore, depletion of BRCA1 did indeed inhibit CB1R-stimulated neurite outgrowth. The transcription factor PAX6 was also regulated in response to cannabinoid signaling. This type of network analysis is useful to define the logic of complex signaling decision processes.

K. D. Bromberg, A. Ma'ayan, S. R. Neves, R. Iyengar, Design logic of a cannabinoid receptor signaling network that triggers neurite outgrowth.
Science
320
, 903-909 (2008).
[Abstract]
[Full Text]
Getting the Numbers Right
Authors: Foley John F.
Published: June 2008

The T cell receptor (TCR)-CD3 complex consists of the antigen-binding TCRαβ dimer in noncovalent association with the δ, ε, γ, and ζ subunits of CD3 (see commentary by Malissen). These subunits contain 10 cytoplasmic immunoreceptor tyrosine-based activation motifs (ITAMs), which, when phosphorylated by tyrosine kinases, become docking sites for downstream signaling molecules, resulting in T cell activation and proliferation and cytokine production. Why each TCR contains 10 ITAM motifs is unclear, so Holst
et
al
. investigated the contributions of individual ITAMs to TCR signaling. They transduced bone marrow cells from CD3-deficient mice with retroviruses that expressed either wild-type or ITAM-mutant CD3 subunits. These cells were transferred into T cell-deficient mice to establish 25 groups of mice with varying combinations of wild-type and ITAM-mutant CD3 subunits. The transferred T cells first traveled to the thymus, where they underwent positive and negative selection. The authors analyzed T cell development and proliferation in the recipient mice. Mice that received less than six ITAMs developed autoimmune diseases, as assessed by immunohistochemistry of affected tissues, whereas those mice with more than six ITAMs did not. There was a positive correlation between the number of ITAMs and T cell proliferation but not cytokine production. Regulatory T cell numbers and function were similar in the different groups of mice, leading the authors to conclude that lack of negative selection of self-reactive CD4
+
T cells in the thymus rather than induction of self-reactive cells in the periphery caused autoimmunity. Indeed, lower ITAMs were associated with positive rather than negative selection of self-reactive T cells in other experiments, consistent with the idea that having too few ITAMs results in an insufficiently strong TCR signal to cause negative selection. This study suggests that different numbers of ITAMs are required for different aspects of T cell function, with high numbers required to prevent autoimmunity.

J. Holst, H. Wang, K. D. Eder, C. J. Workman, K. L. Boyd, Z. Baquet, H. Singh, K. Forbes, A. Chruscinski, R. Smeyne, N. S. C. van Oers, P. J. Utz, D. A. A. Vignali, Scalable signaling mediated by T cell antigen receptor-CD3 ITAMS ensures effective negative selection and prevents autoimmunity.
Nat
.
Immunol
.
9
, 658-666 (2008).
[PubMed]

B. Malissen, CD3 ITAMs count!
Nat
.
Immunol
.
9
, 583-584 (2008).
[PubMed]
Route to Specificity
Authors: VanHook Annalisa M.
Published: June 2008

In wild-type yeast, rapamycin represses signaling through TORC1, one of two Tor complexes, both of which are localized to endosomal and vacuolar membranes. Rapamycin-mediated TORC1 repression causes dephosphorylation and nuclear translocation of the GATA transcription factor Gln3, inducing transcription of nitrogen catabolite-repressed (NCR) genes. Gln3 also activates NCR genes in yeast transferred to medium containing a poor nitrogen source. Puria
et al.
(see commentary by Mitchell) report that the nitrogen-limiting and rapamycin signals, both of which are mediated by TORC1, are relayed to Gln3 by distinct mechanisms and that the response to limiting nitrogen conditions depends on Gln3 following a specific route through the cell from Golgi to endosome. In yeast strains that carried a mutation in any one of several genes encoding class C Vps (vacuolar protein sorting) proteins, which are members of a complex that mediates docking and fusion of vesicles with the endosome and vacuole, the response of Gln3 to rapamycin (dephosphorylation, nuclear translocation, and activation of NCR genes) was the same as in wild-type cells, but Gln3 remained cytosolic and NCR genes were not transcribed in response to a shift to low-nitrogen medium. Mutations in class D and, to a lesser extent, class E Vps proteins, all of which are required for Golgi-to-endosome trafficking, phenocopied the class C mutations. In cell fractionation assays of wild-type cell lysates, Gln3 was found in the cytosol and in vesicular, endoplasmic reticulum, and plasma membrane fractions. In class C and D Vps mutants, though, a lesser portion of the Gln3 is detected in the cytosol. Tagged forms of Gln3 and the endosomal marker Vps10 cofractionated from cell lysates and colocalized (by immunocytochemistry) in a punctate pattern consistent with localization to vesicles. Thus, the low-nitrogen transcriptional response mediated by Gln3 appears to rely on specific routing of Gln3 from the Golgi to endosomes, whereas the Gln3-mediated rapamycin response does not share these same trafficking requirements. This implies that TORC1, from its endosomal membrane location, may act on cytoplasmic or endosomal targets specifically. This lends further support to the growing body of evidence that suggests that intracellular vesicles may function as platforms for localizing and concentrating components that confer context specificity to signaling events.

R. Puria, S. A. Zurita-Martinez, M. E. Cardenas, Nuclear translocation of Gln3 in response to nutrient signals requires Golgi-to-endosome trafficking in
Saccharomyces cerevisiae
.
Proc. Natl. Acad. Sci. U.S.A.
105
, 7194-7199 (2008).
[Abstract]
[Full Text]

A. P. Mitchell, A VAST staging area for regulatory proteins.
Proc. Natl. Acad. Sci. U.S.A.
105
, 7111-7112 (2008).
[Full Text]
Cooperation between Prokaryotic (Lde) and Eukaryotic (MRP) Efflux Transporters in J774 Macrophages Infected withListeria monocytogenes: Studies with Ciprofloxacin and Moxifloxacin
Authors: Lismond Ann , Tulkens Paul M. , Mingeot-Leclercq Marie-Paule , Courvalin Patrice , Van Bambeke Françoise
Published: June 2008

Antibiotic efflux is observed in both eukaryotic and prokaryotic cells, modulating accumulation and resistance. The present study examines whether eukaryotic and prokaryotic fluoroquinolone transporters can cooperate in the context of an intracellular infection. We have used (i) J774 macrophages (comparing a ciprofloxacin-resistant cell line overexpressing an MRP-like transporter with wild-type cells with basal expression), (ii)Listeria monocytogenes(comparing a clinical isolate [CLIP21369] displaying ciprofloxacin resistance associated with overexpression of the Lde efflux system with a wild-type strain [EGD]), (iii) ciprofloxacin (substrate of both Lde and MRP) and moxifloxacin (nonsubstrate), and (iv) probenecid and reserpine (preferential inhibitors of MRP and Lde, respectively). The ciprofloxacin MICs for EGD were unaffected by reserpine, while those for CLIP21369 were decreased approximately fourfold (and made similar to those of EGD). Neither probenecid nor reserpine affected the moxifloxacin MICs against EGD or CLIP21369. In dose-response studies (0.01× to 100× MIC) in broth, reserpine fully restored the susceptibility of CLIP21369 to ciprofloxacin (no effect on EGD) but did not influence the activity of moxifloxacin. In studies with intracellular bacteria, reserpine, probenecid, and their combination increased the activity of ciprofloxacin in wild-type and ciprofloxacin-resistant macrophages in parallel with an increase in ciprofloxacin accumulation in macrophages for EGD and an increase in accumulation and decrease in MIC (in broth) for CLIP21369. Moxifloxacin accumulation and intracellular activity were consistently not affected by the inhibitors. A bacterial efflux pump may thus actively cooperate with a eukaryotic efflux transporter to reduce the activity of a common substrate (ciprofloxacin) toward an intracellular bacterial target.
Effects of Minocycline and Valproic Acid Coadministration on Atazanavir Plasma Concentrations in Human Immunodeficiency Virus-Infected Adults Receiving Atazanavir-Ritonavir
Authors: DiCenzo Robert , Peterson Derick R. , Cruttenden Kim , Mariuz Peter , Rezk Naser L. , Hochreiter Jill , Gelbard Harris , Schifitto Giovanni
Published: June 2008

Minocycline and valproic acid are potential adjuvant therapies for the treatment of human immunodeficiency virus (HIV)-associated cognitive impairment. The purpose of this study was to determine whether minocycline alone or in combination with valproic acid affected atazanavir plasma concentrations. Twelve adult HIV-infected subjects whose regimen included atazanavir (300 mg)-ritonavir (100 mg) daily for at least 4 weeks were enrolled. Each subject received atazanavir-ritonavir on day 1, atazanavir-ritonavir plus 100 mg minocycline twice daily on days 2 to 15, and atazanavir-ritonavir plus 100 mg minocycline twice daily and 250 mg valproic acid twice daily on days 16 to 30 with meals. The subjects had 11 plasma samples drawn over a dosing interval on days 1, 15, and 30. The coadministration of minocycline and valproic acid with atazanavir-ritonavir was well tolerated in all 12 subjects (six male; mean [± standard deviation] age was 43.1 [8.2] years). The geometric mean ratios (GMRs; 95% confidence interval [CI]) for the atazanavir area under the concentration-time curve from 0 to 24 h at steady state (AUC
0-24
), the plasma concentration 24 h after the dose (
C
min
), and the maximum concentration during the dosing interval (
C
max
) with and without minocycline were 0.67 (0.50 to 0.90), 0.50 (0.28 to 0.89), and 0.75 (0.58 to 0.95), respectively. Similar decreases in atazanavir exposure were seen after the addition of valproic acid. The GMRs (95% CI) for atazanavir AUC
0-24
,
C
min
, and
C
max
with and without minocycline plus valproic acid were 0.68 (0.43 to 1.06), 0.50 (0.24 to 1.06), and 0.66 (0.41 to 1.06), respectively. Coadministration of neither minocycline nor minocycline plus valproic acid appeared to influence the plasma concentrations of ritonavir (
P
> 0.2). Minocycline coadministration resulted in decreased atazanavir exposure, and there was no evidence that the addition of valproic acid mediated this effect.
Accelerated Control of VisceralLeishmania donovaniInfection in Interleukin-6-Deficient Mice
Authors: Murray Henry W.
Published: June 2008

In patients with visceral leishmaniasis, increased levels of circulating interleukin-6 (IL-6) regularly accompany fully expressed, progressive infections (kala-azar). To experimentally test the role of IL-6, responses to an intracellularLeishmania donovaniinfection in the livers of IL-6−/−and wild-type mice were compared. IL-6−/−mice showed an enhanced control of the infection and earlier, rapid parasite killing along with additional evidence of a stimulated antileishmanial Th1-cell-type response: increased levels of circulating gamma interferon, accelerated granuloma assembly, and heightened responsiveness to chemotherapy. In this model of visceral leishmaniasis, IL-6 appears to act in a suppressive, macrophage-deactivating fashion, which identifies it as a potential target for therapeutic blockade.
Neanthes arenaceodentata (Polychaeta: Annelida), a Proposed Cytogenetic Model for Marine Genetic Toxicology
Authors: Pesch Gerald G. , Pesch Carol E.
Published: June 2008

Genetic toxicants are present in polluted marine environments and may represent a long-term threat to populations of marine organisms. This paper presents details of an in vivo application of sister chromatid exchange (SCE) analysis to a marine polychaete worm Neanthes arenaceodentata. This species exhibits a dose response to mitomycin C (MMC) at concentrations comparable to those eliciting responses in in vivo mammalian systems. A dose of 5 × 10−7 mol/L MMC increased the rate of SCE from a baseline frequency of 0.14/chromosome to 0.5/chromosome. The chromosomes of N. arenaceodentata may provide a useful model for identifying and studying the effects of genetic toxicants in marine environments.Key words: sister chromatid exchange, chromosome, marine worm, polychaete
Bias Evaluation of the Cation-Exchange Method for Sulfate and Chloride
Authors: Stauffer Robert E.
Published: June 2008

The coefficient of variation for sulfate determinations = 1% at the 50-mg∙L−1 level. In the absence of sulfate, the chloride conductance response curve is linear for (0 < Cl < 100 mg∙L−1). The sulfate response curve is mildly nonlinear, being, however, adequately modeled using log K1 (SO42−) = 1.97 (25 °C), where K1 is the proton association constant. The temperature-dependent solubility product Ksp (AgCl) affects the blank correction for unbiased SO4 estimates. The bicarbonate conductance effect is effectively modeled using log K1 (HCO3−) = 6.35 (25 °C). The fluoride effect is adequately modeled using log K1 (F−) = 3.18 (25 °C) for aqueous mixtures of chloride, sulfate, and fluoride. In applying the cation-exchange method to sulfate analyses of alkaline high-Cl, high-F, geothermal waters, positively biased sulfate estimates were obtained; the bias depended on the SO4/F equivalence ratio and on the dilution level (of the natural water), and probably resulted from pH-dependent HF complexing with SiO2 or B(OH)3, both constituents being notably high in geothermal waters. Analytical strategies are discussed allowing procedural optimization for many natural waters.Key words: water analysis, cation exchange, sulfate determination, chloride determination, geothermal waters
Maintenance of Iron Meromixis by Iron Redeposition in a Rapidly Flushed Monimolimnion
Authors: Campbell P. , Torgersen T.
Published: June 2008

Water mass ages determined by the 3H–3He method gave a water renewal time of 2.5 ± 1 yr for the monimolimnion of softwater iron meromictic Lake 120. The water renewal time of the monimolimnion is less than, or equal to, the renewal time of the whole lake. The monimolimnion of Lake 120 was, therefore, not found to be a stratum of "perennially stagnant deep water." The rates of supply to, and degradation of, organic matter in the monimolimnion are responsible, in the first place, for the low redox potential necessary to establish the high concentrations of soluble Fe2+ observed (up to 4.2 mmol∙L−1). However, it was found that the major key to maintenance of high monimolimnetic concentrations of Fe, i.e. maintenance of iron meromixis, is recycling of Fe at the chemocline by an [Formula: see text] "Ferrous Wheel." Up to 90% recycling of iron between chemocline and monimolimnion results in an iron residence time of [Formula: see text] for the whole lake (greater than 4 times the whole lake water renewal time).Key words: meromixis, iron recycling, 3H–3He water ages, water renewal times, chemical budgets, sediment funneling, redox reactions, Experimental Lakes Area (ELA).
Piscivority in a Land-Locked Alewife (Alosa pseudoharengus) Population
Authors: Kohler Christopher C. , Ney John J.
Published: June 2008

Larval fish were a frequent dietary component of alewives (Alosa pseudoharengus) from Claytor Lake, Virginia, USA. Alewives consumed the young of four game and two forage species (maximum 26 mm total length (TL)). Alewife piscivority appeared to be at least partially nocturnal and was more prominent in littoral than in limnetic areas. Predator and prey lengths were positively correlated, although morphological limits on larval fish ingestion by alewives were not severe. Peak occurrence (40–70%, June 1978) of larval fish in alewife stomachs coincided with a precipitous decline in zooplankton density. Zooplankton abundance was higher in early summer 1979, when alewife piscivority was less common. Our findings support the hypothesis that alewife piscivority could have contributed to the collapse of Great Lakes resident fish populations following alewife establishment. Alewife piscivority should be considered in risk–benefit evaluations prior to introducing alewife as a pelagic forage species.Key words: alewife, Alosa pseudoharengus; feeding ecology, larval fish, Great Lakes fisheries, forage introductions
Growth and Survival of Developing Steelhead Trout (Salmo gairdneri) Continuously or Intermittently Exposed to Copper
Authors: Seim W. K. , Curtis L. R. , Glenn S. W. , Chapman G. A.
Published: June 2008

Steelhead trout (Salmo gairdneri) were continuously or intermittently exposed to copper over a 78-d period from 6 d postfertilization through 5 wk postswimup. Copper was introduced into the intermittent exposure chambers for 4.5 h each day. Continuously exposed fish survived and grew better than intermittently exposed fish at the same daily mean copper concentrations. Intermittently exposed fish accumulated significantly more copper than those continuously exposed at the same daily mean concentrations. Results demonstrated that data derived from continuous laboratory exposures should not be directly converted to water quality criteria where toxicant concentrations in natural waters are temporally variable.
Dual Cannulation of Free-Swimming Atlantic Salmon, Salmo salar
Authors: Nichols D. J. , Weisbart M.
Published: June 2008

We describe a technique for enduring (>1 mo) dual cannulation of large, free-swimming Atlantic salmon, Salmo salar. Repeated blood sampling is possible without disturbance of the fish and the technique is suitable for studies that involve administration of radiolabeled substances for kinetic and distribution volume measurements.
Accumulation and Metabolism of Tri-n-butyltin Cation by a Green Alga, Ankistrodesmus falcatus
Authors: Maguire R. J. , Wong P. T. S. , Rhamey J. S.
Published: June 2008

Tributyltin pesticides are increasingly widespread, but their environmental persistence is poorly known. The accumulation and metabolism of tri-n-butyltin cation (Bu3Sn+) by a green alga, Ankistrodesmus falcatus, was determined at 20 °C over a 4-wk period; about 50% of the original Bu3Sn+ was converted to di-n-butyltin (Bu2Sn2+) and small quantities of butyltin (BuSn3+) and inorganic tin. An apparent algal bioconcentration factor of 3 × 104 was estimated for Bu3Sn+.