bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling the self-organized phosphatidylinositol lipids signaling system in chemotactic cells based on quantitative image analysis
Authors: Shibata Tatsuo , Nishikawa Masatoshi , Matsuoka Satomi , Ueda Masahiro
Published: August 2012

The phosphatidylinositol (PtdIns) lipids reaction is a key signaling event; this signal is responsible for gradient sensing in eukaryotic cell chemotaxis. The self-organization activity of the PtdIns lipids reaction induces an inherent polarity even in the absence of an external chemoattractant gradient by producing a localized PtdIns 3,4,5-trisphosphate [PtdIns(3,4,5)P3]-enriched domain on the membrane. Experimentally, we found that such a domain could exhibit two types of behavior: 1) persistent domain formation that travels on the membrane and 2) stochastic formation of transient domains. Taking advantage of the simultaneous visualization of PtdIns(3,4,5)P3 and its enzyme, phosphatase and a tensin homolog (PTEN), the inter-dependence of their spatiotemporal dynamics was demonstrated statistically. Based on this statistical analysis, we developed a theoretical model for the self-organization of PtdIns lipids signaling that can accurately reproduce both persistent and transient domain formation; these types of formations can be explained by the oscillatory and excitability properties of the system, respectively.
Adenosine triphosphate (ATP) inhibits IP3-evoked Ca2+ release in smooth muscle via P2Y1 receptors
Authors: MacMillan D. , Kennedy C. , McCarron J.G.
Published: August 2012

Adenosine 5′-triphosphate (ATP) mediates a variety of biological functions following nerve-evoked release, via activation of either G protein-coupled P2Y- or ligand-gated P2X-receptors. In smooth muscle, ATP, acting via P2Y receptors (P2YR), may act as an inhibitory neurotransmitter. The underlying mechanism(s) remain unclear, but have been proposed to involve the production of inositol 1,4,5-trisphosphate (IP3) by phospholipase C (PLC), to evoke Ca2+ release from the internal store and stimulation of Ca2+-activated potassium (KCa) channels to cause membrane hyperpolarization. This mechanism requires Ca2+ release from the store. However, in the present study, ATP evoked transient Ca2+ increases in only ∼10% of voltage-clamped single smooth muscle cells. These results do not support activation of KCa as the major mechanism underlying inhibition of smooth muscle activity. Interestingly, ATP inhibited IP3-evoked Ca2+ release in cells that did not show a Ca2+ rise in response to purinergic activation. The reduction in IP3-evoked Ca2+ release was not mimicked by adenosine and therefore, cannot be explained by hydrolysis of ATP to adenosine. The reduction in IP3-evoked Ca2+ release was, however, also observed with its primary metabolite, ADP, and blocked by the P2Y1R antagonist, MRS2179, and the G protein inhibitor, GDPβS, but not by PLC inhibition. The present study demonstrates a novel inhibitory effect of P2Y1R activation on IP3-evoked Ca2+ release, such that purinergic stimulation acts to prevent IP3-mediated increases in excitability in smooth muscle and promote relaxation.
In parallelinterconnectivity of the dorsal longitudinal anastomotic vessels requires both VEGF signaling and circulatory flow
Authors: Zygmunt Tomasz , Trzaska Sean , Edelstein Laura , Walls Johnathon , Rajamani Saathyaki , Gale Nicholas , Daroles Laura , Ramírez Craig , Ulrich Florian , Torres-Vázquez Jesús
Published: August 2012

Blood vessels deliver oxygen, nutrients, hormones and immunity factors throughout the body. To perform these vital functions, vascular cords branch, lumenize and interconnect. Yet, little is known about the cellular, molecular and physiological mechanisms that control how circulatory networks form and interconnect. Specifically, how circulatory networks merge by interconnecting in parallel along their boundaries remains unexplored. To examine this process we studied the formation and functional maturation of the plexus that forms between the Dorsal Longitudinal Anastomotic Vessels (DLAVs) in the zebrafish. We find that the migration and proliferation of endothelial cells within the DLAVs and their Segmental (Se) vessel precursors drives DLAV plexus formation. Remarkably, the presence of Se vessels containing only endothelial cells of the arterial lineage is sufficient for DLAV plexus morphogenesis, suggesting that endothelial cells from the venous lineage make a dispensable or null contribution to this process. The discovery of a circuit that integrates the inputs of circulatory flow and Vascular Endothelial Growth Factor (VEGF) signaling to modulate aortic arch angiogenesis, together with the expression of components of this circuit in the trunk vasculature, prompted us to interrogate the role of these inputs and their relationship during DLAV plexus formation. We find that circulatory flow and VEGF signaling make additive contributions to DLAV plexus morphogenesis, rather than acting as essential inputs with equivalent contributions as they do during aortic arch angiogenesis. Our observations underscore the existence of context-dependent differences in the integration of physiological stimuli and signaling cascades during vascular development.
Syndecan-1 controls cell migration by activating Rap1 to regulate focal adhesion disassembly
Authors: Altemeier William A. , Schlesinger Saundra Y. , Buell Catherine A. , Parks William C. , Chen Peter
Published: August 2012

After injury, residual epithelial cells coordinate contextual clues from cell-cell and cell-matrix interactions to polarize and migrate over the wound bed. Protrusion formation, cell body translocation and rear retraction is a repetitive process that allows the cell to move across the substratum. Fundamental to this process is the assembly and disassembly of focal adhesions that facilitate cell adhesion and protrusion formation. Here, we identified syndecan-1 as a regulator of focal adhesion disassembly in migrating lung epithelial cells. Syndecan-1 altered the dynamic exchange of adhesion complex proteins, which in turn regulates migration speed. Moreover, we provide evidence that syndecan-1 controls this entire process through Rap1. Thus, syndecan-1 restrains migration in lung epithelium by activating Rap1 to slow focal adhesion disassembly.
AtTPR7 is a chaperone docking protein of the Sec translocon in Arabidopsis
Authors: Schweiger Regina , Müller Nina C. , Schmitt Manfred J. , Soll Jürgen , Schwenkert Serena
Published: August 2012

Chaperone assisted sorting of post-translationally imported proteins is a general mechanism among all eukaryotic organisms. Interaction of some preproteins with the organellar membranes is mediated by chaperones, which are recognized by membrane bound tetratricopeptide repeat (TPR) domain containing proteins. We have characterized AtTPR7 as an endoplasmic reticulum (ER) protein in plants and propose a potential function for AtTPR7 in post-translational protein import. Our data demonstrate that AtTPR7 interacts with the heat shock proteins HSP90 and HSP70 via a cytosolic exposed TPR domain. We further show by in vitro and in vivo experiments that AtTPR7 is associated with the Arabidopsis Sec63 homologue, AtERdj2. Interestingly, AtTPR7 can functionally complement a Δsec71 yeast mutant which is impaired in post-translational protein transport. These data strongly suggest that AtTPR7 not only has a role in chaperone binding but also in post-translational protein import into the ER, pointing to a general mechanism of chaperone mediated post-translational sorting between the ER, mitochondria and chloroplasts in plant cells.
Class E compartments form in response to ESCRT dysfunction in yeast due to hyperactivity of the Vps21 Rab GTPase
Authors: Russell Matthew Robert Geoffrey , Shideler Tess , Nickerson Daniel Patrick , West Matt , Odorizzi Greg
Published: August 2012

The endosomal sorting complexes required for transport (ESCRTs) mediate the budding of intralumenal vesicles (ILVs) at late endosomes. ESCRT dysfunction causes drastic changes in endosome morphology, which are manifested in Saccharomyces cerevisiae by the formation of aberrant endosomes known as class E compartments. Except for the absence of ILVs, the mechanistic basis for class E compartment biogenesis is unknown. We used electron microscopy to examine endosomal morphology in response to transient ESCRT inactivation and recovery in yeast expressing the temperature-sensitive mutant vps4ts allele. Our results show class E compartments accumulate 4-fold the amount of membrane normally present at MVBs and that MVBs can form directly from class E compartments upon recovery of ESCRT function. We found class E compartment formation requires Vps21, which is orthologous to the Rab5A GTPase in metazoans that promotes fusion of endocytic vesicles with early endosomes and homotypic fusion of early endosomes with one another. We also determined that class E compartments accumulate GTP-bound Vps21 and its effector, CORVET. Ypt7, the yeast ortholog of Rab7 that in metazoans promotes fusion of late endosomes with lysosomes, also accumulates at class E compartments but without its effector, HOPS, signifying that Ypt7 at class E compartments is dysfunctional. These results suggest that failure to complete Rab5-Rab7 conversion is a consequence of ESCRT dysfunction, which results in Vps21 hyperactivity that drives the class E compartment morphology. Indeed, genetic disruption of Rab conversion without ESCRT dysfunction autonomously drives the class E compartment morphology without blocking ILV budding.
Myosin heavy chain kinases play essential roles in Ca2+, but not cAMP, chemotaxis and the natural aggregation of Dictyostelium discoideum
Authors: Wessels Deborah , Lusche Daniel F. , Steimle Paul A. , Scherer Amanda , Kuhl Spencer , Wood Kristen , Hanson Brett , Egelhoff Thomas T. , Soll David R.
Published: August 2012

Behavioral analyses of the deletion mutants of the four known myosin II heavy chain (Mhc) kinases of D. discoideum revealed that all played a minor role in the efficiency of basic cell motility, but none played a role in chemotaxis in a spatial gradient of cAMP generated in vitro. However, each of the two kinases MhckA and MhckC, was essential for chemotaxis in a spatial gradient of Ca2+, shear induced directed movement, and reorientation in the front of waves of cAMP during natural aggregation. The mutant phenotypes of mhckA− and mhckC− were highly similar to that of the Ca2+ channel/receptor mutant iplA− and the myosin II phosphorylation mutant 3XALA, which produces constitutively unphosphorylated myosin II. These results demonstrate that IplA, MhckA and MhckC play a selective role in chemotaxis in a spatial gradient of Ca2+, but not cAMP and suggest that Ca2+ chemotaxis plays a role in the orientation of cells in the front of cAMP waves during natural aggregation.
Impact of a selfish B chromosome on chromatin dynamics and nuclear organization in Nasonia
Authors: Swim Megan M. , Kaeding Kelsey E. , Ferree Patrick M.
Published: August 2012

B chromosomes are centric chromosomal fragments present in thousands of eukaryotic genomes. Because most B chromosomes are non-essential, they can be lost without consequence. In order to persist, however, some B chromosomes can impose strong forms of intra-genomic conflict. An extreme case is the Paternal Sex Ratio (PSR) B chromosome in the jewel wasp Nasonia vitripennis. Transmitted solely via the sperm, PSR ‘imprints’ the paternal chromatin so that it is destroyed during the first mitosis of the embryo. Due to the haplo-diploid reproduction of N. vitripennis, PSR-induced loss of the paternal chromatin converts embryos that should become females into PSR-transmitting males. This conversion is key to the persistence of PSR, although the underlying mechanisms are largely unexplored. We (i) assessed how PSR affects the paternal chromatin and (ii) investigated how PSR is transmitted efficiently at the cellular level. We found that PSR does not affect progression of the paternal chromatin through the cell cycle but, instead, alters its normal Histone H3 phosphorylation and loading of the Condensin complex. PSR localizes to the outer periphery of the paternal nucleus, a position that we propose is crucial for it to escape from the defective paternal set. In sperm, PSR consistently localizes to the extreme anterior tip of the elongated nucleus, while the normal wasp chromosomes localize broadly across the nucleus. Thus, PSR may alter or bypass normal nuclear organizational processes to achieve its position. These findings provide new insights into how selfish genetic elements can impact chromatin-based processes for their survival.
Atlantic cod (Gadus morhua L.) in situ cardiac performance at cold temperatures: long-term acclimation, acute thermal challenge and the role of adrenaline
Authors: Lurman Glenn J. , Petersen Lene H. , Gamperl A. Kurt
Published: August 2012

The resting and maximum in situ cardiac performance of Newfoundland Atlantic cod (Gadus morhua L.) acclimated to 10, 4 and 0°C were measured at their respective acclimation temperatures, and when acutely exposed to temperature changes: i.e. hearts from 10°C fish cooled to 4°C, and hearts from 4°C fish measured at 10°C and 0°C. Intrinsic heart rate (fH) decreased from 41 beats min-1 (bpm) at 10°C to 33 bpm at 4°C and to 25 bpm at 0°C. However, this degree of thermal dependency was not reflected in maximal cardiac output. Qmax values were ~44, ~37 and ~34 ml min-1 kg-1 at 10, 4 and 0°C, respectively. Further, cardiac scope showed a slight positive compensation between 4 and 0°C (Q10 = 1.7), and full, if not a slight over compensation between 10 and 4°C (Q10 = 0.9). The maximal performance of hearts exposed to an acute decrease in temperature (i.e. from 10°C to 4°C and 4°C to 0°C) was comparable to that measured for hearts from 4 and 0°C acclimated fish, respectively. In contrast, 4°C acclimated hearts significantly out-performed 10°C acclimated hearts when tested at a common temperature of 10°C (in terms of both Qmax and power output). Only minimal differences in cardiac function were seen between hearts stimulated with basal (5 nM) vs. maximal (200 nM) levels of adrenaline, the effects of which were not temperature dependant. These results: 1) show that maximum performance of the isolated cod heart is not compromised by exposure to cold temperatures; and 2) support data from other studies which show that, in contrast to salmonids, cod cardiac performance/myocardial contractility is not dependent upon humoral adrenergic stimulation.
Comparative intralimb coordination in avian bipedal locomotion
Authors: Stößel Alexander , Fischer Martin S.
Published: August 2012

Analyses of how intralimb coordination during locomotion varies within and across different taxa are necessary for understanding the morphological and neurological basis for locomotion in general. Previous findings suggest that intralimb proportions are the major source of kinematic variation that governs intralimb coordination across taxa. Also, independence of kinematics from habitat preference and phylogenetic position has been suggested for mammals. This leads to the hypothesis that among equally-sized bird species exhibiting equal limb proportions similar kinematics can be observed. To test this hypothesis, the bipedal locomotion of two distantly related ground-dwelling bird species (Eudromia elegans and Coturnix coturnix) and of a less terrestrial species (Corvus monedula) was investigated by means of a biplanar high-speed x-ray videographic analysis. Birds were exhibiting similar intralimb proportions and were filmed over a broad range of speed while moving on a treadmill. Joint- and limb element angles, as well as pelvic rotations, were quantified. Regarding fore-aft motions of the limb joints and elements, a congruent pattern of intralimb coordination was observed among all experimental species. The sample of species suggests that it is largely independent of their habitat preference and systematic position and it seems to be related to demands for coping with an irregular terrain with a minimum of necessary control. Hence, the initial hypothesis was confirmed. However, this congruence is not found when looking at medio-lateral limb motions and pelvic rotations, showing distinct differences between ground-dwellers (e.g., largely restricted to a parasagittal plane) and Corvus (e.g., an increased mobility of the hip joint).
Nocturnal light environments and species ecology: implications for nocturnal color vision in forests
Authors: Veilleux Carrie C , Cummings Molly E
Published: August 2012

While variation in the color of light in terrestrial diurnal and twilight environments has been well documented, relatively little work has examined the color of light in nocturnal habitats. Understanding the range and sources of variation in nocturnal light environments has important implications for nocturnal vision, particularly following recent discoveries of nocturnal color vision. In this study, we measured nocturnal irradiance in a dry forest/woodland and a rainforest in Madagascar over 34 nights. We found that a simple linear model including additive effects of lunar altitude, lunar phase and canopy openness successfully predicted total irradiance flux measurements across 242 clear sky measurements (r=0.85; p<0.0001). However, the relationship between these variables and spectral irradiance was more complex, as interactions between lunar altitude, lunar phase and canopy openness were also important predictors of spectral variation. Further, in contrast to diurnal conditions, nocturnal forests and woodlands share a yellow-green-dominant light environment with peak flux at 560 nm. To explore how nocturnal light environments influence nocturnal vision, we compared photoreceptor spectral tuning, habitat preference and diet in 32 nocturnal mammals. In many species, long-wavelength-sensitive cone spectral sensitivity matched the peak flux present in nocturnal forests and woodlands, suggesting a possible adaptation to maximize photon absorption at night. Further, controlling for phylogeny, we found that fruit/flower consumption significantly predicted short-wavelength-sensitive cone spectral tuning in nocturnal mammals (p=0.002). These results suggest that variation in nocturnal light environments and species ecology together influence cone spectral tuning and color vision in nocturnal mammals.
Flexibility in locomotor-feeding integration during prey capture in varanid lizards: effects of prey size and velocity
Authors: Montuelle Stéphane J , Herrel Anthony , Libourel Paul-Antoine , Daillie Sandra , Bels Vincent L
Published: August 2012

Feeding movements are adjusted in response to food properties, and this flexibility is essential for omnivorous predators as food properties vary routinely. In most lizards, prey capture is no longer considered to solely rely on the movements of the feeding structures (jaws, hyolingual apparatus), but instead is understood to require the integration of the feeding system with the locomotor system (i.e., coordination of movements). Here, we investigate flexibility in the coordination pattern between jaw, neck and forelimb movements in omnivorous varanid lizards feeding on four prey types varying in length and mobility: grasshoppers, live newborn mice, adult mice and dead adult mice. We test for bivariate correlations between 3D locomotor and feeding kinematics, and compare the jaw-neck-forelimb coordination patterns across prey types. Our results reveal that locomotor-feeding integration is essential for the capture of evasive prey, and that different jaw-neck-forelimb coordination patterns are used to capture different prey types. Jaw-neck-forelimb coordination is indeed significantly altered by the length and speed of the prey, indicating that a similar coordination pattern can be finely tuned in response to prey stimuli. These results suggest feed-forward as well as feedback modulation of the control of locomotor-feeding integration. As varanids are considered to be specialized in the capture of evasive prey (although they retain their ability to feed on a wide variety of prey items), flexibility in locomotor-feeding integration in response to prey mobility is proposed to be a key component in their dietary specialization.
Disrupted flow sensing impairs hydrodynamic performance and increases the metabolic cost of swimming in the yellowtail kingfish,Seriola lalandi
Authors: Yanase Kazutaka , Herbert Neill , Montgomery John
Published: August 2012

The yellowtail kingfish, Seriola lalandi, shows a distribution of anaerobic and aerobic (red and pink) muscle fibres along the trunk that is characteristic of active pelagic fishes. The athletic capacity of S. lalandi is also shown by its relative high standard metabolic rate and optimal (i.e. least cost) swimming speed. To test the hypothesis that lateral line afferent information contributes to efficient locomotion in an active pelagic species, the swimming performance of S. lalandi was evaluated after unilateral disruption of trunk superficial neuromasts (SN). Unilaterally disrupting the superficial neuromasts (SN) of the lateral line impaired both swimming performance and energetic efficiency. The critical swimming speed (mean Ucrit±S.D., N=12) for unilaterally SN-disrupted fish was 2.11±0.96 L s-1, which was significantly slower than the 3.66±0.19 L s-1 Ucrit of sham SN-disrupted fish. The oxygen consumption (in mg O2 kg-1 min-1) of the unilaterally SN-disrupted fish in a speed range of 1.0–2.2 L s-1 was significantly greater than that of the sham SN-disrupted fish. The lowest gross cost of transport (GCOT) for SN-disrupted fish was 0.18±0.06 J N-1 m-1, which was significantly greater than the 0.11±0.03 J N-1 m-1 GCOT of sham SN-disrupted fish. The factorial metabolic scope (mean±S.D., N=6) of the unilaterally SN-disrupted fish (2.87±0.78) was significantly less than that of sham controls (4.14±0.37). These data show that an intact lateral line is important to the swimming performance and efficiency of carangiform swimmers, but the functional mechanism of this effect remains to be determined.
Parental hypoxic exposure confers offspring hypoxia resistance in zebrafish (Danio rerio)
Authors: Ho Dao H. , Burggren Warren W.
Published: August 2012

Maternal influences are a potentially important component of transgenerational transfer of phenotype in vertebrates. This study on zebrafish (Danio rerio) examined how chronic hypoxic exposure on adults affected the phenotype of their offspring. Separate adult populations were exposed to hypoxia (13.1 kPa O2) or normoxia (21.1 kPa O2) for periods ranging from 1 to 12 weeks. Adults were then returned to normoxia and bred within experimental groups. Adult fecundity and egg characteristics (volume of egg, yolk and perivitelline fluid) were assessed. Subsequently, larval body length, time to loss of equilibrium in severe hypoxia (~4 kPa O2), and critical thermal minima (CTMin) and maxima (CTMax) were measured at 6, 9, 12, 15, 18, 21 and 60 days post fertilization (dpf). Adult fecundity was depressed by hypoxic exposure. Egg component volumes were also depressed in adults exposed to 1-2 weeks of hypoxia, but returned to control levels following longer hypoxic exposure. Adult hypoxic exposures of >1 week resulted in longer body lengths in their larval offspring. Time to loss of equilibrium in severe hypoxia (i.e. hypoxic resistance) in control larvae decreased from 6 to 12 dpf, remaining constant thereafter. Notably, hypoxic resistance from 6-18 dpf was ~15% lower in larvae whose parents were exposed to just 1 week of chronic hypoxia, but resistance was significantly increased by ~24-30% in 6-18 dpf in larvae from adults exposed to 2, 3 or 4 weeks of hypoxia. CTMin (~39.5°C) and CTMax (~10-12 °C) were unchanged by parental hypoxic exposure. This study demonstrates that parental hypoxic exposure in adult zebrafish has profound epigenetic effects on the morphological and physiological phenotype of their offspring.
Gill remodelling during terrestrial acclimation reduces aquatic respiratory function of the amphibious fishKryptolebias marmoratus
Authors: Turko Andrew J. , Cooper Chris A. , Wright Patricia A.
Published: August 2012

The skin-breathing amphibious fish Kryptolebias marmoratus experiences rapid environmental changes when moving between water- and air-breathing, but remodelling of respiratory morphology is slower (~1 week). We tested the hypotheses that (1) there is a trade-off in respiratory function of gills displaying aquatic versus terrestrial morphologies, and (2) rapidly increased gill ventilation is a mechanism to compensate for reduced aquatic respiratory function. Gill surface area, which varied inversely to the height of the interlamellar cell mass, was increased by acclimating fish for 1 week to air or low ion water, or decreased by acclimating fish for 1 week to hypoxia (~20% dissolved oxygen saturation). Fish were subsequently challenged with acute hypoxia and gill ventilation or oxygen uptake was measured. Fish with reduced gill surface area increased ventilation at higher dissolved oxygen levels, showed an increased critical partial pressure of oxygen, and suffered impaired recovery compared to brackish water control fish. These results indicate that hyperventilation, a rapid compensatory mechanism, was only able to maintain oxygen uptake during moderate hypoxia in fish that had remodelled their gills for land. Thus, fish moving between aquatic and terrestrial habitats may benefit from cutaneously breathing oxygen-rich air, but upon return to water must compensate for a less efficient branchial morphology (mild hypoxia) or suffer impaired respiratory function (severe hypoxia).
Mild desiccation rapidly increases freeze tolerance of the goldenrod gall fly, Eurosta solidaginis: evidence for drought-induced RCH
Authors: Levis Nicholas A. , Yi Shu-Xia , Lee Richard E.
Published: August 2012

Overwintering insects may experience extreme cold and desiccation stress. Both freezing and desiccation require cells to tolerate osmotic challenge as solutes become concentrated in the hemolymph. Not surprisingly, physiological responses to low temperature and desiccation share common features and may confer cross-tolerance against these stresses. Freeze-tolerant larvae of the goldenrod gall fly, Eurosta solidaginis (Fitch) (Diptera: Tephritidae), experience extremely dry and cold conditions in winter. To determine whether mild desiccation can improve freeze tolerance at organismal and cellular levels, we assessed survival, hemolymph osmolality, and glycerol levels of control and desiccated larvae. Larvae that lost only 6-10% of their body mass, in as little as 6 h, had markedly higher levels of freeze tolerance. Mild, rapid desiccation increased freezing tolerance at -15°C in September- (33.3±6.7 to 73.3±12%) and at -20°C in October-collected (16.7±6.7 to 46.7±3.3%) larvae. Similarly, 6 h of desiccation improved in vivo survival by 17-43% in fat body, Malpighian tubule, salivary gland, and tracheal cells at -20°C. Desiccation, also, enhanced intrinsic levels of cold tolerance in midgut cells frozen ex vivo (38.7±4.6 to 89.2±5.5 %). Whereas hemolymph osmolality increased significantly with desiccation treatment from 544±16 to 720±26 mOsm, glycerol levels did not differ between control and desiccated groups. The rapidity with which a mild desiccation stress increased freeze tolerance closely resembles the rapid cold-hardening (RCH) response, which occurs during brief sub-lethal chilling, and suggests that drought stress can induce RCH.
Photosensitizer Dye Nanoparticle-coated Membranes for Singlet Oxygen Generation under Atmospheric Conditions
Authors: Ito Daiki , Takahashi Yukiko , Saito Hironobu , Nosaka Yoshio
Published: August 2012

A simple and easily controllable immobilization method for photosensitizer dyes and the resulting photosensitizer dye nanoparticle-coated membranes (PDNMs) that generate singlet oxygen (1O2) under atmospheric conditions were demonstrated. A 100% porphyrin nanoparticles layer that is less than 1 µm thick on a membrane filter caused quantitative 1O2 production under illumination. The thin layer promotes effective light absorption as well as significantly slowed deactivation of 1O2 by supporting materials. Moreover, the PDNMs were highly resistant to photobleaching of dye itself.
Conformational Regulation of Cyclophanes by Formation of Pseudorotaxane Based on a Charge-transfer Complex
Authors: Tsuge Akihiko , Nakamura Katsuji , Moriguchi Tetsuji , Araki Koji
Published: August 2012

Cyclophanes consisting of diethylene glycol-substituted oligothiophene units as a component have been synthesized. Formation of pseudorotaxane arising from complexation of the cyclophanes and the cyclobis(paraquat-p-phenylene) (CBPQT4+) has been confirmed. It has also been discovered that conformational properties of the cyclophanes are strongly affected by the formation of pseudorotaxane.
Comment on Poirier: Dogma or Doubt?
Authors: Pagan Adrian
Published: August 2012

[This paper responds to “Frequentist and Subjectivist Perspectives on the Problems of Model Building in Economics,” by Dale J. Poirier, in this same issue.] Poirier appeals to the latent statistician that he hopes is lurking behind every economist. Like a good fundamentalist preacher he demands, “Do you believe in the Likelihood Principle?” As with most doctrines, we give it a quick glance and reply, “Amen, brother.” From there on we are trapped and led inexorably, via the creed of the likelihood principle (LP), to the one true religion of Bayesianism. Before I begin my critique, let me compliment the preacher on his sermon. I doubt if one could find a more engaging, beguiling, or coherent account of the strengths of following the Bayesian methodology. Next I provide a personal testimony concerning what bothers me about the dogmas of the recommended religion.
The Subjectivist Response
Authors: Poirier Dale J
Published: August 2012

[This paper responds to comments on “Frequentist and Subjectivist Perspectives on the Problems of Model Building in Economics,” by Dale J. Poirier.] It is a rare opportunity to have one's research discussed in print by as eminent and contemplative a group of researchers as my three discussants. To each I wish to express my gratitude for his thought-provoking comments. I will address the discussants' comments in an order which I believe reflects a decreasing degree of common ground in our views.
The Status of Master's Programs in Economics
Authors: Thornton Robert J , Innes Jon T
Published: August 2012

It is the purpose of this article to report the results of a recent survey which we undertook concerning the content and structure of master's programs in economics. During the fall of 1985, questionnaires were sent to the 221 United States colleges and universities listed in Peterson's Graduate Programs in the Humanities and Social Sciences (1985) as having graduate programs in economics. One hundred sixty-nine responses were received from master's program directors, a response rate of 76 percent. We have attempted to judge the composite picture of the current master's degree in economics that emerges from our survey results. We discuss program numbers and admissions prerequisites; course requirements; comprehensive examinations; the master's thesis; time spent and post-masters's pursuits; and the master's degree as a “consolation degree.”
Puzzles: Penny Stocks, Discount Brokers, Better Bidding, and More
Authors: Nalebuff Barry
Published: August 2012

In presenting economic puzzles, I have three goals in mind: some puzzles are chosen to stimulate research; others offer examples that will help undergraduate and graduate teaching; all should provide quality distractions during seminars. This feature begins with reader's comments on the first “Puzzles.” Next are several speed puzzles, with answers provided at the end. Here we have two Fischer Black problems in finance and a dot game from Richard Zeckhauser. Following are several longer puzzles, for which readers are challenged to submit their own answers. This issue's longer problems give you a chance to think about strategies for staying ahead (in sailboat racing to R&D racing) and not losing your head at an auction. The responses will be discussed in a future issue.
Anomalies: The Winner's Curse
Authors: Thaler Richard H
Published: August 2012

Next time that you find yourself a little short of cash for lunch, try the following experiment in your class. Take a jar and fill it with coins, noting the total value of the coins. Now auction off the jar to your class (offering to pay the winning bidder in bills to control for penny aversion). Chances are very high that the following results will be obtained: (1) the average bid will be significantly less than the value of the coins (bidders are risk averse); (2) the winning bid will exceed the value of the jar. Therefore, you will have money for lunch, and your students will have learned first-hand about the “winner's curse.” The winner's curse cannot occur if all the bidders are rational, so evidence of a winner's curse in market settings would constitute an anomaly. However, acting rationally in a common value auction can be difficult. Solving for the optimal bid is not trivial. Thus, it is an empirical question whether bidders in various contexts get it right or are cursed. I will present some evidence, both from experimental and field studies, suggesting that the winner's curse may be a common phenomenon.
Takeovers: Their Causes and Consequences
Authors: Jensen Michael C
Published: August 2012

Economists have accumulated considerable evidence and knowledge on the effects of the takeover market. Here, I focus on current aspects of the controversy. My assessment is that the market for corporate control is creating large benefits for shareholders and for the economy as a whole by loosening control over vast amounts of resources and enabling them to move more quickly to their highest-valued use. This is a healthy market in operation, on both the takeover side and the divestiture side, and it is playing an important role in helping the American economy adjust to major changes in competition and regulation of the past decade.
Corporate Takeovers: The Efficiency Arguments
Authors: Scherer F. M
Published: August 2012

In recent years, the tender offer takeover has been praised and damned with a ferocity suggesting that the survival of capitalism is at stake. The truth, as in most disputes with substantial metaphysical content, is more prosaic. Some takeovers enhance economic efficiency, some degrade it, and the balance of effects, though not fully known, is most likely a close one. In this essay I try to lay bare the debate's foundations and bring it back to earth with an injection of evidence.
In Honor of Sandy Grossman, Winner of the John Bates Clark Medal
Authors: Kreps David M
Published: August 2012

Sandy Grossman, Professor of Economics at Princeton University, is the winner of the John Bates Clark Medal for 1987, given to “that American economist under forty who is adjudged to have made a significant contribution to economic thought and knowledge.” I have been invited by the editors to review some of the contributions that Grossman has made to economics. My review will concentrate on two of the major themes in Grossman's work: models of rational expectations equilibria in situations where there is privately held information; and models of the modern corporation, emphasizing incentives for managers. The concluding section briefly mentions some other themes and remarks on the broad impact Grossman has had on the community of economists.
A Seller's (& Buyer's) Guide to the Job Market for Beginning Academic Economists
Authors: Carson Richard , Navarro Peter
Published: August 2012

In an effort to increase the stock of information available to sellers and buyers in the academic job market for beginning Ph.D. economists, this paper presents the findings of a survey of the 1985-86 hiring process by economics departments. The findings are based on a stratified random sample of all economics departments ranked in the top 20, and 380 other economics departments. Sellers in this job market, typically graduate students in the final stages of their doctoral dissertations, will find answers to questions like: Will a phone call from a candidate or faculty advisor increase the probability of securing a job interview? How many weeks before the AEA meetings are requests for interviews sent out? How long does a typical job interview last and what criteria are applied? How soon after the meetings interview is a candidate likely to be invited to give a seminar at a school? Are elements of the job offer such as salary, teaching load, and summer research money negotiable? How long does a candidate have to accept or reject an offer? The benefits of these survey results will not, however, be limited to sellers.
Puzzles: Cider in Your Ear, Continuing Dilemma, The Last Shall Be First, and More
Authors: Nalebuff Barry
Published: August 2012

In presenting economic puzzles, I have three goals in mind: some puzzles are chosen to stimulate research; others offer examples that will help undergraduate and graduate teaching; all should provide quality distractions during seminars. As usual, this feature begins with several speed puzzles; answers can be found at the end of the problems. Following are several longer puzzles, for which readers are challenged to submit their own answers. The puzzles in this issue focus on betting and voting, and once again include a prisoners' dilemma problem. The column ends with reader mail, including the submitted solutions to “The Best Location in Manhattan,” Puzzle 4 in the Summer 1987 issue of this journal.
The Role of Intergenerational Transfers and Life Cycle Saving in the Accumulation of Wealth
Authors: Modigliani Franco
Published: August 2012

The purpose of this paper is to review what economists know at present about the following question: How large a portion of the existing wealth is the result of a bequest motive, that is, of accumulation for the specific purpose of leaving bequests? But first I will clarify why an answer to this question is of interest.
Distinguished Lecture on Economics in Government: Thinking About International Economic Coordination
Authors: Feldstein Martin S
Published: August 2012

I am not opposed to international cooperation in all economic matters, but in this lecture, I stress the counterproductive consequences of the international coordination of macroeconomic policy. I believe that many of the claimed advantages of cooperation and coordination are wrong, that there are substantial risks and disadvantages to the types of coordination that are envisioned, and that an emphasis on international coordination can distract attention from the necessary changes in domestic policy. Moreover, the attempt to pursue coordination in a wide range of macroeconomic policies is likely to result in disagreements and disappointments that reduce the prospects for cooperation in those more limited areas of trade, defense, and foreign assistance where international cooperation is actually necessary. In stressing the limited scope for the international coordination of macroeconomic policy and exchange rates, I do not wish to imply that such action is never appropriate. There are some small and very interdependent countries where such coordination should undoubtedly be the general rule. There are also some conditions when the potential gains from coordination are such that all countries could expect to benefit from participation. But the active coordination of the macroeconomic policies and of exchange rates among the United States, Japan, and Germany will generally be inappropriate. Moreover, as I shall explain in these remarks, the United States is particularly unsuited to participate in an ongoing process of economic coordination.
Symposium on Public and Private Unionization
Authors: Lazear Edward P
Published: August 2012

Understanding the source of the decline of private sector unions and concomitant rise of public sectors unions is essential. Without that knowledge, the welfare effects of the changes cannot be ascertained. The two essays that follow take us a long way down the road toward that understanding.
The Rise and Fall of Unions: The Public Sector and the Private
Authors: Reder Melvin W
Published: August 2012

This paper has a single purpose: to explain why unionism (interpreted as percentage of union adherents among eligible employees) has been declining in the private sector for the past 30 to 35 years, but, for most of this period, has been increasing in the public sector. To provide this explanation, I offer an ad hoc theory. For the private sector, the paper tries to account for differences in the trends of union adherence during five “epochs”: before 1917; 1917 to 1920; 1920 to 1933; 1933 to the early 1950s; and since the early 1950s. In the public sector, two epochs are distinguished: before and after 1960. Finally, I distinguish between the public and private sectors since 1960.
Puzzles: Sylvia, Ice Cream and more
Authors: Farrell Joseph
Published: August 2012

This installment of Puzzles includes answers to all the puzzles presented. The puzzles are titled: “Competition as a Welfare Minimum”; “Externalities Galore”; “The Utility of Ice Cream”; “Congestion Pricing”; and “Are There Pareto Improvements?”
Comments on the Market Crash: Six Months After
Authors: Leland Hayne , Rubinstein Mark
Published: August 2012

Six months after the market crash of October 1987, we are still sifting through the debris searching for its cause. Two theories of the crash sound plausible -- one based on a market panic and the other based on large trader transactions -- though there is other evidence that is difficult to reconcile. If we are to believe the market panic theory or the Brady Commission's theory that the crash was primarily caused by a few large traders, we must strongly reject the standard model. We need to build models of financial equilibrium which are more sensitive to real life trading mechanisms, which account more realistically for the formation of expectations, and which recognize that, at any one time, there is a limited pool of investors available with the ability to evaluate stocks and take appropriate action in the market.
Comment on the Modigliani-Miller Propositions
Authors: Ross Stephen A
Published: August 2012

[This is a comment on “The Modigliani-Miller Propositions after Thirty Years” by Merton H. Miller in this same issue.] What a treat it is to have the opportunity to read Merton Miller's ruminations on the MM Propositions. A comment on Miller and Modigliani's work can easily become a discussion of any facet of modern finance. I will focus on the two areas of arbitrage and taxation. Since the original MM analysis, economists have learned an enormous amount about the role played by no arbitrage conditions in financial markets. Taxation is where the real world meets the theory. At first blush, the corporate deduction for interest seemed to doom the MM analysis to an academic curiosity, since it appeared to give debt an obvious cost advantage over equity. It was the genius of Miller to see that the arbitrage analysis went much too deeply into the workings of the financial markets and the economy as a whole to be easily unseated by even something as powerful as the tax code.
Nobel Laureate: On James Buchanan's Contributions to Public Economics
Authors: Romer Thomas
Published: August 2012

The 1986 Nobel Prize in economic science was awarded to James Buchanan. What the Nobel committee recognized in making its award was Buchanan's central role in the gradual transformation of the way economists and political scientists study governments and their relationship to the governed. In this essay, I will focus on Buchanan's contributions to public economics, especially his linking of economic and political concerns. Table 1 lists the 21 works by James Buchanan cited in this essay.
Puzzles: Blockades, Carrier Missions, Secret Intelligence, and More
Authors: Nalebuff Barry
Published: August 2012

As usual, this feature begins with several speed puzzles; answers can be found at the end of the problems. Following is one longer puzzle for which readers are challenged to submit their own answer. The puzzles in this issue focus on everything from diversifying strategies in naval warfare to ordering in restaurants to finding the quickest way around Delhi. The column ends with reader mail, including submitted solutions to Schelling's Poison Pill and the fairest way to score a contest.
Anomalies: The Ultimatum Game
Authors: Thaler Richard H
Published: August 2012

This paper discusses simple ultimatum games, two-stage bargaining ultimatum games, and multistage ultimatum games. Finally, I discuss ultimatums in the market. Any time a monopolist (or monopsonist) sets a price (or wage), it has the quality of an ultimatum.
Symposium on the Slowdown in Productivity Growth
Authors: Fischer Stanley
Published: August 2012

The growth slowdown that began in the late 1960s or early 1970s is the most significant macroeconomic development of the last two decades. The four papers in this symposium address the question of the causes of the growth slowdown and, to a lesser extent, what might be done about it.
The Productivity Slowdown, The Oil Shocks, and the Real Cycle
Authors: Olson Mancur
Published: August 2012

Five facts stand out about economic performance in the United States since World War II. The first is that, for most of the postwar period, the U.S. has had a slower rate of economic growth than the other major developed democracies except Great Britain, and much lower rates of growth than Germany, Japan, and Italy. The second is that the United States has fallen far behind in many mass production industries in which it used to lead the world, whereas it is ahead of other nations in many new and especially high-technology industries. The third is that most of the older heartland of American industry -- roughly the area north and east of an arc drawn from Baltimore to St. Louis to Milwaukee -- has declined dramatically in comparison with the South and the West. The fourth is the near cessation of the growth of productivity since the early 1970s in the United States as well as in other developed countries. The fifth is the shift from the unexpectedly good macroeconomic performance of the 1950s and 1960s to the simultaneous and theoretically anomalous increases in unemployment and inflation rates in the 1970s. This article attempts to show, with distinctive quantitative estimates, that the familiar attempts to trace the productivity slowdown to higher energy prices cannot be right, but that the oil shocks had a significant indirect impact on the productivity slowdown. I argue that this roundabout impact becomes evident only when we introduce a fresh perspective on macroeconomics that also helps to explain the anomalous emergence of stagflation in the 1970s. Auspiciously, all five prominent facts are explained within the same parsimonious framework.
Business Ascendancy and Economic Impasse: A Structural Retrospective on Conservative Economics, 1979–87
Authors: Bowles Samuel , Gordon David M , Weisskopf Thomas E
Published: August 2012

Conservatives have been waging economic revolution since the late Carter years. Have they succeeded? Ronald Reagan and the early architects sought their place in the history books as institutional innovators, not economic tinkerers. Viewed in this perspective, the conservative economic agenda has sought—and is often recognized as an attempt—to change the rules of the game. One might therefore properly ask: Did conservative economic leadership under Paul Volcker and Ronald Reagan succeed in transforming the underlying structure of the U.S. economy? If so, what have been the macroeconomic effects of this transformation? Answering this question requires a somewhat unusual economic model, one which identifies and develops quantitative indicators of the key dimensions of the institutional environment of the economy and estimates the relationship of these dimensions to the behavior of key economic variables such as profitability and investment. We present here such a social structural model of macroeconomic performance.