bluuebunny/crossref_metadata_2025_split huggingface dataset:
Parasite-mediated selection and the role of sex and diapause in Daphnia
Authors: Duncan A.B. , Mitchell S. E. , Little T.J. 
Published: June 2006

Abstract
To gain insight into parasite-mediated natural selection, we studied a natural population of the crustacean Daphnia magna during a severe epidemic of the bacterial parasite Pasteuria ramosa. We also investigated the relationship between susceptibility and the production of resting eggs, which are only produced during the sexual phase of reproduction. Live host samples were taken before and after this epidemic and resistance to P. ramosa was examined in the laboratory. Host clones collected after the epidemic were more resistant to P. ramosa than were those collected pre-epidemic, which is consistent with parasite-mediated selection. In our study population, asexually reproducing females were observed across the entire study period, but females carrying resting eggs were observed only prior to the epidemic. For hosts isolated in this pre-epidemic period, we found evidence that those carrying resting eggs (at the time of collection) were more susceptible than those that were reproducing asexually. This was especially apparent for measures of parasite growth, although not all measures of infection success conclusively supported this pattern. Nevertheless, the data suggest that some genotypes invest heavily in diapause at the expense of immunocompetence. Sex could therefore inhibit the evolution of resistance because each spring new genotypes will hatch from resting eggs that are relatively susceptible as they were not exposed to the previous years bout of parasite-mediated selection.
Do operational sex ratios influence sex allocation in viviparous lizards with temperature-dependent sex determination?
Authors: Allsop D. J. , Warner D. A. , Langkilde T. , Du W. , Shine R. 
Published: June 2006

Abstract
Under certain environmental situations, selection may favour the ability of females to adjust the sex ratio of their offspring. Two recent studies have suggested that viviparous scincid lizards can modify the sex ratio of the offspring they produce in response to the operational sex ratio (OSR). Both of the species in question belong to genera that have also recently been shown to exhibit temperature-dependent sex determination (TSD). Here we test whether pregnant montane water skinks (Eulamprus tympanum) utilise TSD to select offspring sex in response to population wide imbalances in the OSR, by means of active thermoregulation. We use a combination of laboratory and field-based experiments, and conduct the first field-based test of this hypothesis by maintaining females in outdoor enclosures of varying OSR treatments throughout pregnancy. Although maternal body temperature during pregnancy was influenced by OSR, the variation in temperature was not great enough to affect litter sex ratios or any other phenotypic traits of the offspring.
Imbalanced genomic imprinting in brain development: an evolutionary basis for the aetiology of autism
Authors: Badcock C. , Crespi B. 
Published: June 2006

Abstract
We describe a new hypothesis for the development of autism, that it is driven by imbalances in brain development involving enhanced effects of paternally expressed imprinted genes, deficits of effects from maternally expressed genes, or both. This hypothesis is supported by: (1) the strong genomic-imprinting component to the genetic and developmental mechanisms of autism, Angelman syndrome, Rett syndrome and Turner syndrome; (2) the core behavioural features of autism, such as self-focused behaviour, altered social interactions and language, and enhanced spatial and mechanistic cognition and abilities, and (3) the degree to which relevant brain functions and structures are altered in autism and related disorders. The imprinted brain theory of autism has important implications for understanding the genetic, epigenetic, neurological and cognitive bases of autism, as ultimately due to imbalances in the outcomes of intragenomic conflict between effects of maternally vs. paternally expressed genes.
Selection on body size and sexual size dimorphism differs between host species in a seed-feeding beetle
Authors: Fox C. W. , Czesak M. E. 
Published: June 2006

Abstract
Sexual size dimorphism varies substantially among populations and species but we have little understanding of the sources of selection generating this variation. We used path analysis to study how oviposition host affects selection on body size in a seed-feeding beetle (Stator limbatus) in which males contribute large ejaculates (nuptial gifts) to females. Females use nutrients in these ejaculates for egg production. Male body size, which affects ejaculate size, affects female fecundity and is thus under fecundity selection similar in magnitude to the fecundity selection on female body size. We show that when eggs are laid on a host on which larval mortality is low (seeds of Acacia greggii) fecundity predicts fitness very well and fecundity selection is the major source of selection on both male and female adult size. In contrast, when eggs are laid on a host on which larval mortality is high (seeds of Parkinsonia florida) fecundity poorly predicts fitness such that fecundity selection is relaxed on both male and female size. However, because egg size affects larval mortality on this poor host (P. florida) there is selection on female size via the female size → egg size → fitness path; this selection via egg size offsets the reduction in fecundity selection on female, but not male, body size. Thus, differences in host suitability (due to differences in larval mortality) affect the relative importance of two sources of selection on adult body size; fecundity selection on both male and female body size is lower on the poor quality host (P. florida) relative to the high quality host (A. greggii) whereas selection on female body size via effects of egg size on offspring survival (body size → egg size → fitness) is greater on the poor quality host relative to the high quality host. Because selection via the egg size path affects only females the difference in larval survival between hosts shifts the relative magnitude of selection on female vs. male size. Researchers working on other study systems should be alerted to the possible importance of subtle, but consequential, indirect selection on their study organisms.
Fitness effects of X chromosome drive in the stalk-eyed fly, Cyrtodiopsis dalmanni
Authors: Wilkinson G. S. , Johns P. M. , Kelleher E. S. , Muscedere M. L. , Lorsong A. 
Published: June 2006

Abstract
Sex-ratio (SR) males produce predominantly female progeny because most Y chromosome sperm are rendered nonfunctional. The resulting transmission advantage of XSR chromosomes should eventually cause population extinction unless segregation distortion is masked by suppressors or balanced by selection. By screening male stalk-eyed flies, Cyrtodiopsis dalmanni, for brood sex ratio we found unique SR alleles at three X-linked microsatellite loci and used them to determine if SR persists as a balanced polymorphism. We found that XSR/XST females produced more offspring than other genotypes and that SR males had lower sperm precedence and exhibited lower fertility when mating eight females in 24 h. Adult survival was independent of SR genotype but positively correlated with eye span. We infer that the SR polymorphism is likely maintained by a combination of weak overdominance for female fecundity and frequency dependent selection acting on male fertility. Our discovery of two SR haplotypes in the same population in a 10-year period further suggests that this SR polymorphism may be evolving rapidly.
Postzygotic incompatibilities between the pupfishes,Cyprinodon elegansandCyprinodon variegatus
Authors: Tech C. 
Published: June 2006

AbstractI examined the intrinsic postzygotic incompatibilities between two pupfishes, Cyprinodon elegans and Cyprinodon variegatus. Laboratory hybridization experiments revealed evidence of strong postzygotic isolation. Male hybrids have very low fertility, and the survival of backcrosses into C. elegans was substantially reduced. In addition, several crosses produced female-biased sex ratios. Crosses involving C. elegans females and C. variegatus males produced only females, and in backcrosses involving hybrid females and C. elegans males, males made up approximately 25% of the offspring. All other crosses produced approximately 50% males. These sex ratios could be explained by genetic incompatibilities that occur, at least in part, on sex chromosomes. Thus, these results provide strong albeit indirect evidence that pupfish have XY chromosomal sex determination. The results of this study provide insight on the evolution of reproductive isolating mechanisms, particularly the role of Haldane's rule and the ‘faster-male’ theory in taxa lacking well-differentiated sex chromosomes.
Projection of the Grüneberg ganglion to the mouse olfactory bulb
Authors: Roppolo Daniele , Ribaud Virginie , Jungo Véronique Pauli , Lüscher Christian , Rodriguez Ivan 
Published: June 2006

AbstractIn mammals, sensory neurons from the main olfactory and vomeronasal systems project their axons to the olfactory bulbs in the brain. We here report that a cluster of neurons, distinct from these two systems, located at the very tip of the mouse nose and called the Grüneberg ganglion expresses the mature olfactory‐sensory neuron‐specific marker olfactory marker protein (OMP), but is unlikely to express known odorant or pheromone receptors. The ganglion is present at birth and maintained during adult life. Tracing experiments indicate that these neurons target ipsilaterally to a specific set of glomeruli located on the caudal part of the olfactory bulb, and that this connection is necessary for the survival of the ganglion. The glomerular targets are structures previously proposed to be associated with suckling behaviour. These observations strongly suggest that this peculiar olfactory neuronal population plays a sensory role, possibly linked to chemoperception.
Contribution of the corpus callosum to bilateral representation of the trunk midline in the human brain: an fMRI study of callosotomized patients
Authors: Fabri M. , Polonara G. , Mascioli G. , Paggi A. , Salvolini U. , Manzoni T. 
Published: June 2006

AbstractHuman brain studies have shown that the cutaneous receptors of trunk regions close to the midline are represented in the first somatosensory cortex (SI) of both hemispheres. The present study aims to establish whether in humans, as in non‐human primates, the bilateral representation of the trunk midline in area SI depends on the corpus callosum. Data were obtained from eight callosotomized patients: three with complete callosal resection, one with a partial posterior resection including the splenium and the callosal trunk, and four with partial anterior resections sparing the splenium and in one case also the posterior part of the callosal trunk. The investigation was carried out with functional magnetic resonance imaging. Unilateral tactile stimulation was applied by rubbing ventral trunk regions close to the midline (about 20 × 10 cm in width) with a soft cotton pad (frequency 1 Hz). Cortical activation foci elicited by unilateral stimulation of cutaneous regions adjacent to the midline were detected in the contralateral post‐central gyrus (PCG), in a region corresponding to the trunk ventral midline representation zone of area SI, as described in a previous study of intact subjects. In most patients, activation foci were also found in the ipsilateral PCG, again as in subjects with an intact corpus callosum. The data confirm that the skin regions adjacent to the trunk midline are represented bilaterally in SI, and indicate that ipsilateral activation is at least partially independent of the corpus callosum.
Regulation of NMDA receptor trafficking and function by striatal‐enriched tyrosine phosphatase (STEP)
Authors: Braithwaite Steven P. , Adkisson Michael , Leung John , Nava Adrian , Masterson Brett , Urfer Roman , Oksenberg Donna , Nikolich Karoly 
Published: June 2006

AbstractRegulation ofN‐methyl‐d‐aspartate (NMDA) receptors is critical for the normal functioning of the central nervous system. There must be precise mechanisms to allow for changes in receptor function required for learning and normal synaptic transmission, but within tight constraints to prevent pathology. Tyrosine phosphorylation is a major means by which NMDA receptors are regulated through the equilibrium between activity of Src family kinases and tyrosine phosphatases. Identification of NMDA receptor phosphatases has been difficult, the best candidate being striatal‐enriched tyrosine phosphatase (STEP). Here we demonstrate that STEP is a critical regulator of NMDA receptors and reveal that the action of this tyrosine phosphatase controls the constitutive trafficking of NMDA receptors and leads to changes in NMDA receptor activity at the neuronal surface. We show that STEP binds directly to NMDA receptors in the absence of other synaptic proteins. The activity of STEP selectively affects the expression of NMDA receptors at the neuronal plasma membrane. The result of STEP's action upon the NMDA receptor affects the functional properties of the receptor and its downstream signaling. These effects are evident when STEP levels are chronically reduced, indicating that there is no redundancy amongst phosphatases to compensate for altered STEP function in the CNS. STEP may have evolved specifically to fill a pivotal role as the NMDA receptor phosphatase, having a distinct and restricted localization and compartmentalization, and unique activity towards the NMDA receptor and its signaling pathway.
Adult large pine weevils Hylobius abietis feed on silver birch Betula pendula even in the presence of conifer seedlings
Authors: Toivonen Riitta , Viiri Heli 
Published: June 2006

Abstract1 The feeding preference of the adult pine weevil Hylobius abietis (L.) (Coleoptera: Curculionidae) for Betula pendula Roth was studied in no‐choice and paired‐choice feeding experiments.2 In the first no‐choice test, large quantities of silver birch bark in Petri dishes were consumed; on average, the daily consumption of each weevil was 67 mm2.3 In the second no‐choice test, the weevils were offered 1‐year‐old silver birch seedlings for 6 days. Initially, the weevils fed mostly on the stem bases; later, they moved upward to feed on other parts of the stems. In addition to the main shoots, scars caused by gnawing were also found on leaf bases, blades, veins and petioles. Feeding resulted in the death of the main stems in 15% of the seedlings.4 In the paired‐choice tests, the conifers were preferred to silver birch, even though a large amount of silver birch was also consumed in the presence of conifers.5 In the paired‐choice tests, equal amounts of Scots pine and Norway spruce were always consumed. When hybrid aspen was offered, only small amounts were gnawed.
White pine weevil performances in relation to budburst phenology and traumatic resin duct formation in Norway spruce
Authors: Poulin Julie , Lavallée Robert , Mauffette Yves , Rioux Danny 
Published: June 2006

Abstract1 As the phenological window hypothesis was reported to be significant in influencing the fitness of many herbivores feeding on tree foliage, could it also explain the performance of an insect such as the white pine weevil Pissodes strobi mainly attacking the bark phloem of conifers?2 Under field conditions, adult weevils were caged on Norway spruce trees presenting a natural variation in their shoot growth phenology.3 We evaluated white pine weevil biological performances, including oviposition, the number of emerged insects, survival, adult mean weight and tree defense responses as reflected by the production of induced resin canals.4 None of the white pine weevil biological parameters was significantly affected by Norway spruce phenology.5 The number of eggs per hole, the number of oviposition holes per leader, the number of emerged adults and their mean weight were not affected by host phenology.6 The intensity of the traumatic response observed was variable and not correlated with budburst phenology.7 Trees with higher traumatic responses, forming two or more layers of traumatic ducts, had lower adult emergence and estimated survival.8 The distance between the first layer of traumatic resin ducts and the start of the annual ring was not correlated with the number of emerged weevils.9 Norway spruce, which is an exotic tree in North America and a relatively recent host for the white pine weevil, might not possess the defense mechanisms necessary to fight off the white pine weevil.
Assessment of psychological aspects during systemic provocation tests in patients with pseudoallergic drug reactions
Authors: Hermes B , Hein UR , Henz BM 
Published: June 2006

AbstractBackground  Basic mechanisms of pseudoallergic drug reactions as well as a possible role of the psyche are currently unknown.Objective  Examination of psychological status and reactions during diagnostic provocation tests in patients with previous pseudoallergic reactions to drugs.Subjects and methods  Ten inpatients, admitted for provocation tests, were studied in a double‐blind, placebo‐controlled setting, with inventories of anxiety and depression being measured at baseline and psychological reactions and symptoms being recorded daily by patients and the attending physician.Results  Patients reported more than twice as many symptoms as the physician, independent of the type of exposure. While the basic psychological profile of the patients was normal, anxiety trait and state values were high during testing, with a significant increase depending on whether the patients thought they had received a drug or a placebo. Similarly, frequency of symptoms was dependent on the patients’ perception of the type of exposure.Conclusion  These findings demonstrate a high level of anxiety during systemic provocation tests in patients with previous pseudoallergic drug reactions, raising serious questions as to the diagnostic validity of the routine application of this testing.
Odontogenic myxoma: a diagnosis to add to the list of facial tumours in infants
Authors: Boussault P , Boralevi F , Raux‐Rakotomalala F , Chauvel A , Taïeb A , Léauté‐Labrèze C 
Published: June 2006

AbstractThe differential diagnosis of a midfacial mass in a child includes a great variety of tumours. Odontogenic myxoma is a benign tumour arising from the mesenchymal portion of the odontogenic apparatus that is usually seen in adolescents and adults.
Nicaraguan Sign Language and Theory of Mind: the issue of critical periods and abilities
Authors: Morgan Gary , Kegl Judy 
Published: June 2006

Background: Previous studies in the literature report that deaf individuals who experience late access to language perform poorly on false belief tests of Theory of Mind (ToM) compared with age‐matched deaf and hearing controls exposed to language early.Methods: A group of 22 deaf Nicaraguans (aged 7 to 39 years) who learned Nicaraguan Sign Language (ISN) at different ages were tested on a false belief and a nonverbal cartoon retell task designed to elicit talk about the contents of character's mental states.Results: Access to sign language by 10 years of age with possible advantages in language fluency was a strong predictor of performance on both the false belief task and mental state narrative task. However, a comparison of performance on the two tests indicated that children and adults who learned sign after the age of 10 were still able to demonstrate a more general ability to use mental state expressions in narratives. Results are discussed in terms of late access to language and critical periods for the parallel development of Theory of Mind and language.Conclusions: The findings point to age 10 years as a crucial period when lack of language exposure can lead to long‐lasting deficits in false belief abilities. Late exposure to sign language does not, however, rule out all aspects of the ability to consider others’ mental states. This paper also highlights the need to take into consideration a variety of communication responses when evaluating deaf children's ToM reasoning.
Psychosocial outcomes at 15 years of children with a preschool history of speech‐language impairment
Authors: Snowling Margaret J. , Bishop D.V.M. , Stothard Susan E. , Chipchase Barry , Kaplan Carole 
Published: June 2006

Background:  Evidence suggests there is a heightened risk of psychiatric disorder in children with speech‐language impairments. However, not all forms of language impairment are strongly associated with psychosocial difficulty, and some psychiatric disorders (e.g., attention deficit/hyperactivity disorder (ADHD)) are more prevalent than others in language‐impaired populations. The present study assessed the psychosocial adjustment in adolescence of young people with history of speech‐language impairment, and investigated specific relationships between language deficits and psychiatric disorders.Methods:  Seventy‐one young people (aged 15–16 years) with a preschool history of speech‐language impairment were assessed using a psychiatric interview (K‐SADS) supplemented by questionnaires probing social encounters and parental reports of behaviour and attention. Their psycho‐social adjustment was compared with that of a cross‐sectional control group of age‐matched controls.Results:  Overall the rate of psychiatric disorder was low in the clinical sample and children whose language delay had resolved by 5.5 years had a good outcome. For those whose language difficulties persisted through the school years, there was a raised incidence of attention and social difficulties. These difficulties were partially independent and associated with different language profiles. The group with attention problems showed a profile of specific expressive language difficulties; the group with social difficulties had receptive and expressive language difficulties; and the group with both attention and social difficulties was of low IQ with global language difficulties.Conclusions:  Amongst children with speech‐language delays at 5.5 years, those with more severe and persistent language difficulties and low nonverbal IQ are at higher risk of psychiatric morbidity in adolescence.
Enhancing Patient Safety through Organizational Learning: Are Patient Safety Indicators a Step in the Right Direction?
Authors: Rivard Peter E. , Rosen Amy K. , Carroll John S. 
Published: June 2006

Objective. To assess the potential contribution of the Agency for Healthcare Research and Quality Patient Safety Indicators (PSIs) to organizational learning for patient safety improvement.Principal Findings. Patient safety improvement requires organizational learning at the system level, which entails changes in organizational routines that cut across divisions, professions, and levels of hierarchy. This learning depends on data that are varied along a number of dimensions, including structure‐process‐outcome and from granular to high‐level; and it depends on integration of those varied data. PSIs are inexpensive, easy to use, less subject to bias than some other sources of patient safety data, and they provide reliable estimates of rates of preventable adverse events.Conclusions. From an organizational learning perspective, PSIs have both limitations and potential contributions as sources of patient safety data. While they are not detailed or timely enough when used alone, their simplicity and reliability make them valuable as a higher‐level safety performance measure. They offer one means for coordination and integration of patient safety data and activity within and across organizations.