bluuebunny/crossref_metadata_2025 huggingface dataset:
Making the life of heavy metal-stressed plants a little easier
Authors: Gratão Priscila L. , Polle Andrea , Lea Peter J. , Azevedo Ricardo A.
Published: June 2005

The contamination of soils and water with metals has created a major environmental problem, leading to considerable losses in plant productivity and hazardous health effects. Exposure to toxic metals can intensify the production of reactive oxygen species (ROS), which are continuously produced in both unstressed and stressed plants cells. Some of the ROS species are highly toxic and must be detoxified by cellular stress responses, if the plant is to survive and grow. The aim of this review is to assess the mode of action and role of antioxidants in protecting plants from stress caused by the presence of heavy metals in the environment.
Diel and seasonal changes in fluorescence rise kinetics of three scleractinian corals
Authors: Hill Ross , Ralph Peter J.
Published: June 2005

The effect of diel oscillations in light on the photosynthetic response of three coral species during summer and winter was studied. Fast induction curves revealed detailed information on primary photochemistry as well as redox states of electron acceptors in photosystem II (PSII). The comparison between seasons revealed that similar physiological mechanisms were operating in response to high-light conditions throughout the year and that environmental variables, such as temperature, had no measurable effect between seasons. A diurnal hysteresis was seen in both seasons in Fv / Fm as well as in the fast induction curves, where photosynthetic capacity was lower in the afternoon than in the morning when light intensities were the same. This suggests the operation of dynamic down regulation, following exposure to midday high light. Fast induction curve analysis revealed a decline in the O, J, I and P steps towards midday and a rapid recovery by the late afternoon. The decrease in J and its rapid recovery indicated a drop in the rate of QA reduction as a result of an increase in non-photochemical quenching (NPQ). The P step increased in amplitude in the first hours of sunlight, which suggests an increased oxidation of the plastoquinone (PQ) pool and a greater capacity for electron transport. Similarly, a rise in Fv / Fm was observed within the first hour of sunlight. This response was attributed to the dark reduction of the PQ pool, induced by night time anaerobic conditions and possibly oxygen-dependent chlororespiration, which would lead to a state 2 transition. The early morning removal of chlororespiration and hypoxic conditions would have returned the photosystems to state 1, resulting in the increased photochemical efficiency of the zooxanthellae.
Evaluation of native and introduced grasses for low-input pastures in temperate Australia: experimental approach, site and genotype descriptions
Authors: Norton M. R. , Mitchell M. L. , Kobelt E. , Hall E.
Published: June 2005

This paper describes the experimental methodology, sites, seasonal conditions and germplasm used in the Australian Native and Low Input Grass Network (NLIGN). In 1998, eight sites were established across the temperate pastoral zone of southern Australia. These were located at Armidale, Binya, Sutton and Trangie in NSW; Springhurst in Victoria; Jericho in Tasmania; Flaxley in South Australie and Kendenup in Western Australia. A total of 62 lines were evaluated, of which, 29 were Australian native grasses and 33 were introduced. With differences in seed size among species and a lack of information on dormancy and germination characteristics of the native plants, seedlings were transplanted into the field on weed-mat as spaced plants. Lines were compared over a 3-year period from 1998 to 2001. Methods used for determination of forage production, persistence and palatability are described. Information detailing the original collection sites of the germplasm, a list of NLIGN sites where each genotype was evaluated, as well as a detailed description of sites and seasonal conditions is also presented.
Evaluation of native and introduced grasses for low-input pastures in temperate Australia: rationale and scope
Authors: Whalley R. D. B. , Friend D. A. , Sanford P. , Mitchell M. L.
Published: June 2005

The historical approach to pasture improvement in the high rainfall zone of temperate Australia has been to add introduced herbaceous legumes and to replace perennial native grasses with introduced species requiring high inputs of fertiliser for maintenance. The application of this high-input approach on land with low capability has lead to the loss of perennial grasses, erosion, soil acidification and increasing salinity on the lower slopes. This model of pasture improvement has not been successful on the margins of the wheat belt and in semi-arid regions. The Native and Low-input Grasses Network (NLIGN) was established in 1996 to coordinate research on grasses suitable for land with low capability and for semi-arid regions. The NLIGN multi-site evaluation project was initiated to test promising lines (accessions) of native and introduced grasses for low-input pastures at eight sites across southern Australia.
The broad objective of the project was to identify native and/or introduced perennial grass lines that had possible commercial potential for low-input pastures. This objective was achieved in an initial 3-year evaluation phase, which began in 1998 and tested lines for persistence, production and palatability.
The Rabbit in Subalpine South-eastern Australia. I. Population Structure and Productivity
Authors: Dunsmore DJ
Published: June 2005

An unconfined, almost completely tagged rabbit population on a site of about 100 ha was studied by observation and trapping for 5 years. The commencement of the study coincided approximately with the incorporation of the area into the Kosciusko National Park, the elimination of grazing by domestic livestock, and the cessation of the previously almost annual burning of the area.
During the 5-yr study the fecundity of the rabbits declined to little more than half the initial level. This was not a result of the concurrently increasing age of the population, which was shown to be quite unrelated. It was also shown that the 1yr old rabbits were less fecund than the older rabbits, whose fecundity remained constant.
Although it appeared subjectively to be so, the area was not uniformly suitable for the survival of rabbits. In one of its four subdivisions adult survival was much better than in the others; and in one of the others it was much the worst.
During the study there was considerable immigration to the area, presumably balanced by migration. Females tended to remain where they were born and in no case changed from one breeding group to another. Males were considerably less sedentary than the females.
The Distribution of Rattus villosissimus (Waite) during Plague and Non-plague Years
Authors: Carstairs JL
Published: June 2005

In September 1968 a questionnaire was sent to 1000 properties in Central Australia in an attempt to determine:

(1) the distribution of R. villosissimus; (2) the dates and extent of past plagues of this species;

(3) the direction and extent of mass movements of rats;

(4) local factors which might account for the outbreak of plagues.

In all, 289 replies were received. They confirmed the dates of past plagues and revealed a hitherto unrecorded plague in 1948. They showed that some plagues lasted for several years and that some were more widespread than others, and they suggested that there are 'refuge' areas on the Barkly Tableland of the Northern Territory, near Richmond and Julia Creek in Queensland and in the Lake Eyre Basin, where rats survive between plagues and build up into plague numbers during favourable conditions.

The relationship between rainfall and the outbreak of rat plagues, and the role of predators
during a plague, are discussed. It is suggested that the plaguing behaviour and mass movements of R. t;illosissimus ensure the survival of the species in a potentially lethal environment where the extinction of local populations is probably not uncommon.
Comparison of Avian Communities between Wet and Semiarid Habitats of Eastern Australia
Authors: Kikkawa J
Published: June 2005

The composition of bird species in three distinct habitats of subtropical eastern Australia was examined in terms of the degree of species association, niche occupation and clutch size.

In spite of low species diversity in the wet formations, the birds of this habitat tended to show characteristics of tropical forest birds. These included stronger association of species, relative abundance of treenesting frugivores and small clutch size. In contrast, the semiarid formations supported a greater diversity of bird species with somewhat loose species association, a large representation of graminivores, and a larger mean clutch size with greater variation. At least in the subtropical region of eastern Australia, the bird species diversity does not appear to be related to the stability of environment.
Sexual Cycles of Pigeons in a Tropical Environment.
Authors: Frith HJ , Braithwaite LW , Wolfe TO
Published: June 2005

The sexual cycles of two genera of frugivorous rain-forest pigeons, Ducula and Ptilinopus, and two ground-feeding pigeons of the open woodland, Geopelia humeralis and G. striata, have been studied at latitude 9D 29'S. in New Guinea.

In P, iozonus, P. magnificus, G. humevalis and G. striata some males were sexually active and some females had enlarged follicles in each month of the year and so some individuals, at all times, were capable of breeding; there was an indication that this situation was general in the two genera.

In the rain-forest species more birds had enlarged gonads in the late dry season and wet season than at other times. Both sexes of G. stviata had peak gonad size in the late wet and early dry seasons; G. humevalis maintained peak activity throughout the dry season; both species had small gonads in the late dry season.

The cycles of gonad size of fruit pigeons and ground-feeding pigeons corresponded to the
probable cycle of food abundance in the two habitats. There was no evidence of an effect of
photoperiod in Geopelia but it could not be excluded in males of Ptilinopus.
A Study of the Biology of the Wild Rabbit in Climatically Different Regions in Eastern Australia VI.* Changes in Numbers and Distribution related to Climate and Land Systems in Semiarid North-Western New South Wales.
Authors: Myers K , Parker BS
Published: June 2005

This paper describes a dramatic fall in rabbit populations in a large area of semiarid north-western New South Wales, due to a severe drought, and the increase in numbers which followed.

The reduction in numbers differed markedly in different land systems. The areas which supported rabbit populations throughout the study were limited to the proximity of swamps in sandy habitats, and close to drainage channels in stony habitats; populations became extinct over large areas of sandy habitats.

In the stony habitats populations increased very rapidly in the 12 months following the breaking of the drought, whereas in the sandy habitats it took c. 3 y before a noticeable increase. The difference was probably a result of differences in survival, due mainly to the effects of predation and to the
availability of open warrens. In sandy habitats drift sand buried untenanted warrens very rapidly.

The environment affected not only rabbits but also their main predators, the fox and the cat. No cats and very few foxes were observed in stony habitats. The main activities of both species were confined to refuge areas in sandy habitats.
The most significant correlation between indices of rabbit numbers and indices of use of rabbit warrens was the number of active burrows per unit area of habitat.
Observations on Breeding Biologyof some New Guinea Murid Rodents
Authors: Dwyer PD
Published: June 2005

Breeding records are given for 10 murine rodents from the Eastern Highlands District of Papua New Guinea. Reduced breeding activity through the dry season is apparent for Rattus exulans, R. ruber and Melomys rufescens, with a cessation of breeding at this time in R, niobe, R. verecundus, M. levipes, M. rubex, Pogonomys sylvestris, P. mollipilosus and probably Pogonomelomys sevia.

Available evidence suggests that M. rubex varies in reproductive performance between years. Mean litter size is low in all species with mean live embryo counts from 3.09 in R. exulans to 1.09 in M. levipes and 0.75 in P. sevia. Pregnancy concurrent with lactation appears to be frequent in M. rufescens and perhaps P. sevia, and was noted on occasion in R, exulans, R, verecundus and
M. levipes.
Psedomys gracilicaudatus (Gould): Range Extension and Notes on a Little-known Australian Murid Rodent
Authors: Borsboom AC
Published: June 2005

Specimens of P. gracilicaudatus are recorded from the Townsville area, extending the known Queensland range about 320 km north-west from the Mackay district, its previous northern limit.

Descriptions of the trapping sites, trapping method and pelage, as well as measurements, are given.
Changes in Numbers of Rabbits and their Burrows in a Subalpine Environment in South-eastern New South Wales.
Authors: Myers K , Parker BS , Dunsmore JD
Published: June 2005

Patterns of distribution and use of rabbit warrens in 540 acres (219 ha) of subalpine habitat during 1963 and 1966-71 are described. The numbers of rabbits and of burrows in which they live can fluctuate independently of each other. It is demonstrated in a marked population that careful measurement of changes in burrow use can be used to estimate changes in the numbers of rabbits using the burrows.

The most favourable habitat for rabbits in subalpine regions is raised areas on the floor and sides of valleys in open alpine grasslands, where there are projecting granite tors and moraine-like materials.
Breeding, Moult and Food of the Squatter Pigeon in North-Eastern Queensland.
Authors: Crome FHJ
Published: June 2005

Squatter pigeons (Geophaps scripta) shot in north-eastern Queensland were mainly graminivorous. The most important seed eaten was of Stylosanthes humilis, a plant of improved pasture.
Remains of Mammals, Including Notomys Longicaudatus (Gould) (Rodentia:Muridae), in Owl Pellets From the Flinders Ranges, S.a.
Authors: Smith MJ
Published: June 2005

Owl pellets were collected at 3 sites in the northern Flinders Ranges, S. Australia, from deposits in caves. Food items included rodents and marsupials that are no longer found there and some of which are thought to be extinct. There were remains of Mus musculus among them, indicating that the other species had lived in the Flinders Ranges at least until the 19th century.
Effects of hatchery shading and nest depth on the development and quality of Chelonia mydas hatchlings: implications for hatchery management in Peninsular, Malaysia
Authors: van de Merwe Jason , Ibrahim Kamarruddin , Whittier Joan
Published: June 2005

One of the decisions made by hatchery managers around the world is what degree of shading and nest depth are required to maximise the production of high-quality hatchlings at optimal sex ratios. The primary objectives of this study were to determine the effects of (1) hatchery shading and nest depth on nest temperatures and emergence lag, and (2) nest temperatures and nest depth on hatchling sex ratio and quality. In 2001, 26 Chelonia mydas clutches from Ma’Daerah beach, Terengganu, Malaysia, were relocated alternatively at depths of 50 cm and 75 cm into a 70%-shaded and a 100%-shaded hatchery. Data loggers were placed into the centre of each relocated clutch to record the temperature every hour over the course of incubation. When the hatchlings emerged, a sample of the clutch was run, measured and weighed and a separate sample was examined histologically for sex characteristics. Nest temperatures ranged between 28°C and 30°C and generally showed increases over the second half of incubation due to metabolic heating of the clutch. There was no significant correlation found between nest temperature and any of the hatchling parameters measured. Hatchlings from 75-cm-deep nests had a longer emergence lag (46.4 (±10.2) h) than hatchlings from 50-cm-deep nests. Hatch and emergence success were similar to those of natural populations and hatchling sex ratios were male dominant, with an average of 72% males. There was a poor correlation between mean middle-third incubation temperatures and sex ratio. Hatchlings from 75-cm-deep nests had similar running speeds but lower condition index than their conspecifics from 50-cm-deep nests.
Seasonal range variation of Tadarida australis (Chiroptera:Molossidae) in Western Australia: the impact of enthalpy
Authors: Bullen R. D. , McKenzie N. L.
Published: June 2005

The Australian bat Tadarida australis has a peculiar geographical niche that involves a continental-scale movement of over 10° of latitude in Western Australia. Its range expands northward by up to 1200 km for the winter and contracts southward for the summer. Its summer range limit correlates with an interaction of temperature and humidity, best summarised by atmospheric enthalpy. Its winter distribution is expanded northward within the enthalpy threshold, but appears to be further restricted in some areas by an unknown factor that may be biotic. We propose a potential competitor and a potential predator that may have strongly negative interactions in these regions. The 1% of records that are beyond the enthalpy envelope are from the change-over months and may be an artefact of year-to-year climatic variation. Three climatic thresholds enclose the enthalpy envelope: average annual rainfall >10 mm per month and <50 mm per month, and average overnight minimum temperature <20°C. Current literature relates migration of temperate-zone bats to resource availability as a consequence of changing season. We identify a tight correlation with atmospheric enthalpy that points to dissipation of flight muscle heat as a limiting factor.
A single-molecule diode
Authors: Elbing Mark , Ochs Rolf , Koentopp Max , Fischer Matthias , von Hänisch Carsten , Weigend Florian , Evers Ferdinand , Weber Heiko B. , Mayor Marcel
Published: June 2005

We have designed and synthesized a molecular rod that consists of two weakly coupled electronic π -systems with mutually shifted energy levels. The asymmetry thus implied manifests itself in a current–voltage characteristic with pronounced dependence on the sign of the bias voltage, which makes the molecule a prototype for a molecular diode. The individual molecules were immobilized by sulfur–gold bonds between both electrodes of a mechanically controlled break junction, and their electronic transport properties have been investigated. The results indeed show diode-like current–voltage characteristics. In contrast to that, control experiments with symmetric molecular rods consisting of two identical π -systems did not show significant asymmetries in the transport properties. To investigate the underlying transport mechanism, phenomenological arguments are combined with calculations based on density functional theory. The theoretical analysis suggests that the bias dependence of the polarizability of the molecule feeds back into the current leading to an asymmetric shape of the current–voltage characteristics, similar to the phenomena in a semiconductor diode.
The cysteine-rich region of respiratory syncytial virus attachment protein inhibits innate immunity elicited by the virus and endotoxin
Authors: Polack Fernando P. , Irusta Pablo M. , Hoffman Scott J. , Schiatti M. Paula , Melendi Guillermina A. , Delgado M. Florencia , Laham Federico R. , Thumar Bhagvanji , Hendry R. Michael , Melero Jose A. , Karron Ruth A. , Collins Peter L. , Kleeberger Steven R.
Published: June 2005

The attachment protein (glycoprotein) of respiratory syncytial virus (RSV) has long been associated with disease potentiation and respiratory symptoms. The glycoprotein has a conserved cysteine-rich region (GCRR) whose function is unknown and which is not necessary for efficient viral replication. In this report, we show that the GCRR is a powerful inhibitor of the innate immune response against RSV, and that early secretion of glycoprotein is critical to modulate inflammation after RSV infection. Importantly, the GCRR is also a potent inhibitor of cytokine production mediated by several TLR agonists, indicating that this peptide sequence displays broad antiinflammatory properties. These findings have important implications for RSV pathogenesis and describe an inhibitor of TLR-mediated inflammatory responses that could have clinical applications.
Probing π-coupling in molecular junctions
Authors: Seferos Dwight S. , Trammell Scott A. , Bazan Guillermo C. , Kushmerick James G.
Published: June 2005

Charge transport characteristics for metal–molecule–metal junctions containing two structurally related π-conjugated systems were studied to probe π–π interactions in molecular junctions. The first molecule contains a typical π-conjugated framework derived from phenylene vinylene units, whereas the second has the phenylene vinylene structure interrupted by a [2.2]paracyclophane (pCp) core. Electrochemical investigations were used to characterize the defects and packing density of self-assembled monolayers of the two molecules on gold surfaces and to enable quantitative comparison of their transport characteristics. Current–voltage measurements across molecular junctions containing the two species demonstrate that the pCp moiety yields a highly conductive break in through-bond π-conjugation. The observed high conductivity is consistent with density functional theory calculations, which demonstrate strong through-space π–π coupling across the pCp moiety.
Vibrational inelastic scattering effects in molecular electronics
Authors: Ness H. , Fisher A. J.
Published: June 2005

We describe how to treat the interaction of traveling electrons with localized vibrational modes in nanojunctions. We present a multichannel scattering technique, which can be applied to calculate the transport properties for realistic systems, and we show how it is related to other methods that are useful in particular cases. We apply our technique to describe recent experiments on the conductance through molecular junctions.
Arranging matter by magnetic nanoparticle assemblers
Authors: Yellen Benjamin B. , Hovorka Ondrej , Friedman Gary
Published: June 2005

We introduce a method for transporting colloidal particles, large molecules, cells, and other materials across surfaces and for assembling them into highly regular patterns. In this method, nonmagnetic materials are manipulated by a fluid dispersion of magnetic nanoparticles. Manipulation of materials is guided by a program of magnetic information stored in a substrate. Dynamic control over the motion of nonmagnetic particles can be achieved by reprogramming the substrate magnetization on the fly. The unexpectedly large degree of control over particle motion can be used to manipulate large ensembles of particles in parallel, potentially with local control over particle trajectory.
Richness of plant–insect associations in Eocene Patagonia: A legacy for South American biodiversity
Authors: Wilf Peter , Labandeira Conrad C. , Johnson Kirk R. , Cúneo N. Rubén
Published: June 2005

South America has some of the most diverse floras and insect faunas that are known, but its Cenozoic fossil record of insects and insect herbivory is sparse. We quantified insect feeding on 3,599 leaves from the speciose Laguna del Hunco flora (Chubut, Argentina), which dates to the early Eocene climatic optimum (52 million years ago) and compared the results with three well preserved, rich, and identically analyzed early- and middle-Eocene floras from the following sites in North America: Republic, WA; Green River, UT; and Sourdough, WY. We found significantly more damage diversity at Laguna del Hunco than in the North American floras, whether measured on bulk collections or on individual plant species, for both damage morphotypes and feeding groups. An ancient history of rich, specialized plant–insect associations on diverse plant lineages in warm climates may be a major factor contributing to the current biodiversity of South America.
Seeing what is not there shows the costs of perceptual learning
Authors: Seitz Aaron R. , Nanez Jose E. , Holloway Steven R. , Koyama Shinichi , Watanabe Takeo
Published: June 2005

Perceptual learning is an improvement in one's sensory abilities after training and is thought to help us to better adapt to the sensory environment. Here, we show that perceptual learning also can lead to misperceptions, such that subjects actually perceive stimuli when none are physically presented. After learning, subjects not only showed enhanced performance when tested with the motion direction of the trained stimulus but also often reported seeing dots moving in the trained direction when no stimulus was displayed. We further show that these misperceptions are not attributable to a response bias. These results show that there are costs as well as benefits to perceptual learning and that performance enhancements for a specific feature also can be accompanied by misperceptions of the visual environment.
Charge transport in DNA in solution: The role of polarons
Authors: Conwell Esther M.
Published: June 2005

Since the discovery a decade ago of rapid photoinduced electron transfer in DNA over a distance >4 nm, a large number of experiments and theories have been advanced in the attempt to characterize the transfer, mainly of a radical cation or hole. Particularly influential experiments were carried out by Giese [Giese, B. (2000)
Acc. Chem. Res.
33, 631–636] on the sequence G(A)
n
GGG, where G is guanine and A is adenine. These experiments were interpreted as showing that for
n
> 3, after the holes tunnel through the first three As, they hop onto the bridge of As, where they are localized on a single A and travel further by hopping between neighboring As. Recent experiments of Barton and coworkers [Shao, F., O'Neill, M. A. & Barton, J. K. (2004)
Proc. Natl. Acad. Sci. USA
101, 17914–17919] have, however, established that the hole wavefunctions are delocalized. One of the mechanisms based on delocalized hole wavefunctions that had been investigated, both experimentally and theoretically, is transport by polarons. For one type of polaron, the properties are determined by polarization of the surrounding medium (water and ions, in this case). Theory predicts that this type of polaron is delocalized over approximately four bases in DNA. Transport by these polarons could explain the results of Giese
et al.
[Giese, B., Amaudrut, J., Köhler, A.-K., Spormann, M. & Wessely, S. (2001)
Nature
412, 318–320], recent experimental results of O'Neill and Barton [O'Neill, M. A. & Barton, J. K. (2004)
J. Am. Chem. Soc.
126, 11471–11483] concerning the size of the region over which the hole is delocalized, and other experimental observations.
Collecting duct-specific deletion of peroxisome proliferator-activated receptor γ blocks thiazolidinedione-induced fluid retention
Authors: Zhang Hui , Zhang Aihua , Kohan Donald E. , Nelson Raoul D. , Gonzalez Frank J. , Yang Tianxin
Published: June 2005

The peroxisome proliferator-activated receptor subtype γ (PPARγ) ligands, namely the synthetic insulin-sensitizing thiazolidinedione (TZD) compounds, have demonstrated great potential in the treatment of type II diabetes. However, their clinical applicability is limited by a common and serious side effect of edema. To address the mechanism of TZD-induced edema, we generated mice with collecting duct (CD)-specific disruption of the PPARγ gene. We found that mice with CD knockout of this receptor were resistant to the rosiglitazone- (RGZ) induced increases in body weight and plasma volume expansion found in control mice expressing PPARγ in the CD. RGZ reduced urinary sodium excretion in control and not in conditional knockout mice. Furthermore, RGZ stimulated sodium transport in primary cultures of CD cells expressing PPARγ and not in cells lacking this receptor. These findings demonstrate a PPARγ-dependent pathway in regulation of sodium transport in the CD that underlies TZD-induced fluid retention.
A cysteine-sulfinic acid in peroxiredoxin regulates H
2
O
2
-sensing by the antioxidant Pap1 pathway
Authors: Vivancos Ana P. , Castillo Esther A. , Biteau Benoît , Nicot Carine , Ayté José , Toledano Michel B. , Hidalgo Elena
Published: June 2005

The
Schizosaccharomyces pombe
transcription factor Pap1 regulates antioxidant-gene transcription in response to H
2
O
2
. Pap1 activation occurs only at low, but not elevated, H
2
O
2
concentrations that instead strongly trigger the mitogen-activated protein kinase Sty1 pathway. Here, we identify the peroxiredoxin Tpx1 as the upstream activator of Pap1. We show that, at low H
2
O
2
concentrations, this oxidant scavenger can transfer a redox signal to Pap1, whereas higher concentrations of the oxidant inhibit the Tpx1-Pap1 redox relay through the temporal inactivation of Tpx1 by oxidation of its catalytic cysteine to a sulfinic acid. This cysteine modification can be reversed by the sulfiredoxin Srx1, its expression in response to high doses of H
2
O
2
strictly depending on active Sty1. Thus, Tpx1 oxidation to the cysteine-sulfinic acid and its reversion by Srx1 constitutes a previously uncharacterized redox switch in H
2
O
2
signaling, restricting Pap1 activation within a narrow range of H
2
O
2
concentrations.
Phenotype–genotype correlation in Hirschsprung disease is illuminated by comparative analysis of the RET protein sequence
Authors: Kashuk Carl S. , Stone Eric A. , Grice Elizabeth A. , Portnoy Matthew E. , Green Eric D. , Sidow Arend , Chakravarti Aravinda , McCallion Andrew S.
Published: June 2005

The ability to discriminate between deleterious and neutral amino acid substitutions in the genes of patients remains a significant challenge in human genetics. The increasing availability of genomic sequence data from multiple vertebrate species allows inclusion of sequence conservation and physicochemical properties of residues to be used for functional prediction. In this study, the
RET
receptor tyrosine kinase serves as a model disease gene in which a broad spectrum (≥116) of disease-associated mutations has been identified among patients with Hirschsprung disease and multiple endocrine neoplasia type 2. We report the alignment of the human RET protein sequence with the orthologous sequences of 12 non-human vertebrates (eight mammalian, one avian, and three teleost species), their comparative analysis, the evolutionary topology of the RET protein, and predicted tolerance for all published missense mutations. We show that, although evolutionary conservation alone provides significant information to predict the effect of a
RET
mutation, a model that combines comparative sequence data with analysis of physiochemical properties in a quantitative framework provides far greater accuracy. Although the ability to discern the impact of a mutation is imperfect, our analyses permit substantial discrimination between predicted functional classes of RET mutations and disease severity even for a multigenic disease such as Hirschsprung disease.
Delays in
Pseudomonas aeruginosa
quorum-controlled gene expression are conditional
Authors: Yarwood Jeremy M. , Volper Esther M. , Greenberg E. Peter
Published: June 2005

Acyl-homoserine lactone (acyl-HSL) signaling is thought to mediate quorum sensing in many species of Proteobacteria. The opportunistic human pathogen
Pseudomonas aeruginosa
uses acyl-HSLs to regulate hundreds of genes, including many that code for extracellular virulence factors. The idea that the
P. aeruginosa
acyl-HSLs serve as quorum-sensing signals has been questioned recently because microarray experiments show that the addition of signals to cultures of
P. aeruginosa
does not advance the onset of transcription for most acyl-HSL-dependent genes. We show that, under specific conditions, the expression of many acyl-HSL-dependent genes can be triggered at low culture density by signal addition. If complex medium is conditioned by growth of a non-acyl-HSL-producing
P. aeruginosa
, signals can eliminate the delay in expression of a battery of acyl-HSL-dependent genes. Furthermore, for one representative gene,
lasB
, there is no delay when signals are added to
P. aeruginosa
growing in conditioned complex medium or in minimal medium. We conclude that complex medium contains an inhibitor or inhibitors that can prevent induction of many, but not all, acyl-HSL-regulated genes and that the inhibitor is consumed by
P. aeruginosa
. Our results show that acyl-HSL signals can trigger expression of a large number of acyl-HSL-dependent genes regardless of growth phase. In this way, signaling in
P. aeruginosa
appears similar to quorum signaling in other Proteobacteria.
G protein β interacts with the glucocorticoid receptor and suppresses its transcriptional activity in the nucleus
Authors: Kino Tomoshige , Tiulpakov Anatoly , Ichijo Takamasa , Chheng Ly , Kozasa Tohru , Chrousos George P.
Published: June 2005

Extracellular stimuli that activate cell surface receptors modulate glucocorticoid actions via as yet unclear mechanisms. Here, we report that the guanine nucleotide-binding protein (G protein)–coupled receptor-activated WD-repeat Gβ interacts with the glucocorticoid receptor (GR), comigrates with it into the nucleus and suppresses GR-induced transactivation of the glucocorticoid-responsive genes. Association of Gγ with Gβ is necessary for this action of Gβ. Both endogenous and enhanced green fluorescent protein (EGFP)–fused Gβ2 and Gγ2 proteins were detected in the nucleus at baseline, whereas a fraction of EGFP-Gβ2 and DsRed2-GR comigrated to the nucleus or the plasma membrane, depending on the exposure of cells to dexamethasone or somatostatin, respectively. Gβ2 was associated with GR/glucocorticoid response elements (GREs) in vivo and suppressed activation function-2–directed transcriptional activity of the GR. We conclude that the Gβγ complex interacts with the GR and suppresses its transcriptional activity by associating with the transcriptional complex formed on GR-responsive promoters.
Spatial regulation of CLASP affinity for microtubules by Rac1 and GSK3β in migrating epithelial cells
Authors: Wittmann Torsten , Waterman-Storer Clare M.
Published: June 2005

Proteins that in cells specifically bind to growing microtubule plus ends (+TIPs) are thought to play important roles in polarization of the cytoskeleton. However, most +TIPs do not show a bias of their microtubule-binding behavior toward different subcellular regions. Here, we examine the dynamics of the +TIP CLASP in migrating PtK1 epithelial cells. We find that, although CLASPs track microtubule plus ends in the cell body, they dynamically decorate the entire microtubule lattice in the leading edge lamella and lamellipodium. Microtubule lattice binding is mediated by the COOH-terminal region of the CLASP microtubule-binding domain and is regulated downstream of Rac1. Phosphorylation of sites in the NH2-terminal part of the microtubule-binding domain by glycogen synthase kinase 3β likely regulates the affinity of CLASPs for microtubule lattices. These results demonstrate the striking difference of the microtubule cytoskeleton in the lamella as compared with the cell body and provide the first direct observation of subcellular regulation of a microtubule-associated protein in migrating cells.
A positive feedback loop between Dumbfounded and Rolling pebbles leads to myotube enlargement in Drosophila
Authors: Menon Sree Devi , Osman Zalina , Chenchill Kho , Chia William
Published: June 2005

In Drosophila, myoblasts are subdivided into founders and fusion-competent myoblasts (fcm) with myotubes forming through fusion of one founder and several fcm. Duf and rolling pebbles 7 (Rols7; also known as antisocial) are expressed in founders, whereas sticks and stones (SNS) is present in fcm. Duf attracts fcm toward founders and also causes translocation of Rols7 from the cytoplasm to the fusion site. We show that Duf is a type 1 transmembrane protein that induces Rols7 translocation specifically when present intact and engaged in homophilic or Duf–SNS adhesion. Although its membrane-anchored extracellular domain functions as an attractant and is sufficient for the initial round of fusion, subsequent fusions require replenishment of Duf through cotranslocation with Rols7 tetratricopeptide repeat/coiled-coil domain-containing vesicles to the founder/myotube surface, causing both Duf and Rols7 to be at fusion sites between founders/myotubes and fcm. This implicates the Duf–Rols7 positive feedback loop to the occurrence of fusion at specific sites along the membrane and provides a mechanism by which the rate of fusion is controlled.
Leukotriene B4, an activation product of mast cells, is a chemoattractant for their progenitors
Authors: Weller Charlotte L. , Collington Sarah J. , Brown Jeremy K. , Miller Hugh R.P. , Al-Kashi Adam , Clark Peter , Jose Peter J. , Hartnell Adele , Williams Timothy J.
Published: June 2005

Mast cells are tissue-resident cells with important functions in allergy and inflammation. Pluripotential hematopoietic stem cells in the bone marrow give rise to committed mast cell progenitors that transit via the blood to tissues throughout the body, where they mature. Knowledge is limited about the factors that release mast cell progenitors from the bone marrow or recruit them to remote tissues. Mouse femoral bone marrow cells were cultured with IL-3 for 2 wk and a range of chemotactic agents were tested on the c-kit+ population. Cells were remarkably refractory and no chemotaxis was induced by any chemokines tested. However, supernatants from activated mature mast cells induced pronounced chemotaxis, with the active principle identified as leukotriene (LT) B4. Other activation products were inactive. LTB4 was highly chemotactic for 2-wk-old cells, but not mature cells, correlating with a loss of mRNA for the LTB4 receptor, BLT1. Immature cells also accumulated in vivo in response to intradermally injected LTB4. Furthermore, LTB4 was highly potent in attracting mast cell progenitors from freshly isolated bone marrow cell suspensions. Finally, LTB4 was a potent chemoattractant for human cord blood–derived immature, but not mature, mast cells. These results suggest an autocrine role for LTB4 in regulating tissue mast cell numbers.
Properties and protective value of the secondary versus primary T helper type 1 response to airborne Mycobacterium tuberculosis infection in mice
Authors: Jung Yu-Jin , Ryan Lynn , LaCourse Ronald , North Robert J.
Published: June 2005

Mice immunized against Mycobacterium tuberculosis (Mtb) infection by curing them of a primary lung infection were compared with naive mice in terms of the ability to generate a Th1 cell immune response and to control growth of an airborne Mtb challenge infection. Immunized mice generated and expressed Th1 cell immunity several days sooner than naive mice, as demonstrated by an earlier increase in the synthesis in the lungs of mRNA for Th1 cytokines and for inducible nitric oxide synthase, an indicator of macrophage activation. This Th1 cytokine/mRNA synthesis was accompanied by an earlier accumulation of Mtb-specific Th1 cells in the lungs and the presence of CD4 T cells in lesions. An earlier generation of immunity was associated with an earlier inhibition of Mtb growth when infection was at a 1-log lower level. However, inhibition of Mtb growth in immunized, as well as in naive, mice was not followed by resolution of the infection, but by stabilization of the infection at a stationary level. The results indicate that there is no reason to believe that the secondary response to an Mtb infection is quantitatively or qualitatively superior to the primary response.
IT AND PRODUCTIVITY IN U.S. MANUFACTURING: DO COMPUTER NETWORKS MATTER?
Authors: ATROSTIC B. K. , NGUYEN SANG V.
Published: June 2005

The link between information technology and productivity is clear. Yet how computers affect productivity is not well understood. Ours is the first study using data for approximately 30,000 U.S. manufacturing plants to examine the effect of computer networks on productivity. We find a positive and significant relationship between computer networks and plant labor productivity. Plants with lower productivity in earlier periods are also more likely to have a computer network, supporting the hypothesis that plants use networks to catch up. The positive network effect remains significant when we account for endogenous computer networks. (JEL L6, O3)
EXTERNAL THREAT AND COLLECTIVE ACTION
Authors: NIOU EMERSON M. S. , Tan Guofu
Published: June 2005

This article studies how players allocate their endowed resources between productive and conflictual activities in the context of rivalry between two groups. We show that the suboptimality and exploitation propositions established by Olson (1965) do not necessarily apply when external threat is endogenized. We also illustrate that it does not always pay to take an offensive stance. When competing with an offensive group, it might be better for members of a defensive group to remain defensive. Furthermore, in the context of rivalry between two groups, free riding can actually benefit everyone in the system. (JELD70,D74)
PREDICTING INFLATION: DOES THE QUANTITY THEORY HELP?
Authors: BACHMEIER LANCE J. , SWANSON NORMAN R.
Published: June 2005

Various inflation forecasting models are compared for the period 1979–2003 using a simulated out‐of‐sample forecasting framework. Our findings are (1) M2 has marginal predictive content for inflation; (2) it is necessary to allow for the possibility that money, prices, and output are cointegrated; and (3) cointegration vector parameter estimation error is important when making out‐of‐sample forecasts. Consistent with previous work, we find a structural break in the early 1990s, but the break was easily detected and would not have affected out‐of‐sample inflation forecasts. Two Monte Carlo experiments that lend credence to our findings are also reported on.(JEL E31, C32)
“NEW” PUBLIC INVESTMENT AND/OR PUBLIC CAPITAL MAINTENANCE FOR GROWTH? THE CANADIAN EXPERIENCE
Authors: KALAITZIDAKIS PANTELIS , KALYVITIS SARANTIS
Published: June 2005

The article revisits the relationship between growth and public productive expenditures by investigating the growth impact of “new” public investment along with maintenance expenditures in public capital. We sketch out the importance of these components of public capital expenditures for growth and then use survey data from Canada to assess the impact of these variables on Canadian growth. We find evidence that the Canadian economy would benefit from a fall in total public capital expenditures and from a reallocation between new public investment and maintenance expenditures. We also identify the growth impact of the associated sectoral public capital expenditures. (JEL E22, E62, H21, H54)
CHANGE‐POINT ANALYSIS OF THE GROWTH EFFECTS OF STATE BANKING DEREGULATION
Authors: FREEMAN DONALD G.
Published: June 2005

This article uses recent developments in change‐point analysis to demonstrate that stronger income growth rates previously associated with state bank branch deregulation were in all cases temporary rather than permanent. In addition, patterns of temporal ordering across regions suggest that in many states deregulation was a response to economic conditions rather than the reverse. (JEL E44, G28)
BELIEFS ABOUT OTHER‐REGARDING PREFERENCES IN A SEQUENTIAL PUBLIC GOODS GAME
Authors: COATS JENNIFER C. , NEILSON WILLIAM S.
Published: June 2005

Experimental evidence is used to deduce players' beliefs about their opponents' concern for others. The experiment is a sequential public good provision game with a provision point and two different refund rules. A theory is constructed to show how early contributions should change with the refund rule depending on the first mover's beliefs about subsequent players' other‐regarding preferences. The evidence rejects the hypothesis that early players believe that their opponents are inequality averse and also rejects the hypothesis that early players are concerned with security. The evidence is consistent with beliefs in spite, reciprocity, or a concern for security. (JEL H41, C90, D63, D64)
ON THE NATURE OF RECIPROCAL MOTIVES
Authors: COX JAMES C. , DECK CARY A.
Published: June 2005

Data from 692 subjects in 11 experimental treatments provide a systematic exploration of the existence and nature of reciprocal behavior in two‐person games. The experimental design discriminates between motivations of reciprocity and (nonreciprocal) other‐regarding preferences. The existence of positive reciprocity is found to be dependent on the level of social distance but not the level of monetary payoff. The larger context in which a decision is made is found to have a significant effect on negative reciprocity. These findings on payoff levels, social distance, decision context, and reciprocity have implications for both theoretical modeling and experimental design. (JEL C70, C91, D63, D64)
PRICE COMPETITION UNDER COST UNCERTAINTY: A LABORATORY ANALYSIS
Authors: ABBINK KLAUS , BRANDTS JORDI
Published: June 2005

We study the relation between the number of firms and price‐cost margins under price competition with uncertainty about competitors' costs. We report an experiment in which two, three, and four identical firms repeatedly interact in this environment. In line with the theoretical prediction, market prices decrease with the number of firms, but on average stay above marginal costs. Pricing is more aggressive than in equilibrium. Absolute and relative surplus increases with the number of firms. Total surplus is close to the equilibrium level, because enhanced consumer surplus through lower prices is counteracted by occasional displacements of the most cost‐efficient firm. (JEL C90, C72, D43, D83, L13)
COMBINING MONETARY AND SOCIAL SANCTIONS TO PROMOTE COOPERATION
Authors: NOUSSAIR CHARLES , TUCKER STEVEN
Published: June 2005

We employ an experimental approach to consider the impact of a combination of formal and informal sanctions on contribution levels for a specific type of public good. We find that when both sanctions are available, contributions and overall welfare are higher than when only one of the two sanctioning systems is available. The availability of an array of sanctions of varying severity appears to enhance welfare. (JEL C92)
Resisting realist petrification in George Sand's
Lélia
and Balzac's
Sarrasine
Authors: Harkness Nigel
Published: June 2005

This article considers how George Sand's
Lélia
, which first appeared in 1833 and was extensively rewritten before being republished in 1839, might be read as constituting Sand's critical manifesto on realism. My argument investigates the links between
Lélia
and Balzac's
Sarrasine
(1831), which Barthes reads in S/Z as a paradigmatic realist text. This comparison brings out a network of images and structures common to the two novels: petrification, the enigma of sexual identity, the gaze of the male artist, the codes of sculpture and painting, and binary oppositions such as life/death, real/artificial, and plenitude/emptiness. But if, in Balzac's text, this network functions to underpin realist representation, Sand undermines these structures, and the 1839
Lélia
becomes a veritable literary battlefield which opposes the petrifying male gaze and the heroine's resistance to the fixity and corporeal imprisonment that this entails.
Lélia
can thus be interpreted as constituting a self-conscious dismantling and refusal of the gendered structures of the realist text. Moreover, this analysis rewrites Barthes's interpretation of the conclusion of
Sarrasine
, reading it as the playing out not of a ‘contamination of castration’, but of a ‘contamination of petrification’ whose repercussions can be traced to Balzac's later novel
Béatrix.