bluuebunny/crossref_metadata_2025_split huggingface dataset:
Joint Evolution of Dispersal and Inbreeding Load
Authors: Guillaume Frédéric , Perrin Nicolas 
Published: March 2006

Abstract
Inbreeding avoidance is often invoked to explain observed patterns of dispersal, and theoretical models indeed point to a possibly important role. However, while inbreeding load is usually assumed constant in these models, it is actually bound to vary dynamically under the combined influences of mutation, drift, and selection and thus to evolve jointly with dispersal. Here we report the results of individual-based stochastic simulations allowing such a joint evolution. We show that strongly deleterious mutations should play no significant role, owing to the low genomic mutation rate for such mutations. Mildly deleterious mutations, by contrast, may create enough heterosis to affect the evolution of dispersal as an inbreeding-avoidance mechanism, but only provided that they are also strongly recessive. If slightly recessive, they will spread among demes and accumulate at the metapopulation level, thus contributing to mutational load, but not to heterosis. The resulting loss of viability may then combine with demographic stochasticity to promote population fluctuations, which foster indirect incentives for dispersal. Our simulations suggest that, under biologically realistic parameter values, deleterious mutations have a limited impact on the evolution of dispersal, which on average exceeds by only one-third the values expected from kin-competition avoidance.
Estimating Relatedness Between Individuals in General Populations With a Focus on Their Use in Conservation Programs
Authors: Oliehoek Pieter A , Windig Jack J , van Arendonk Johan A M , Bijma Piter 
Published: March 2006

Abstract
Relatedness estimators are widely used in genetic studies, but effects of population structure on performance of estimators, criteria to evaluate estimators, and benefits of using such estimators in conservation programs have to date received little attention. In this article we present new estimators, based on the relationship between coancestry and molecular similarity between individuals, and compare them with existing estimators using Monte Carlo simulation of populations, either panmictic or structured. Estimators were evaluated using statistical criteria and a diversity criterion that minimized relatedness. Results show that ranking of estimators depends on the population structure. An existing estimator based on two-gene and four-gene coefficients of identity performs best in panmictic populations, whereas a new estimator based on coancestry performs best in structured populations. The number of marker alleles and loci did not affect ranking of estimators. Statistical criteria were insufficient to evaluate estimators for their use in conservation programs. The regression coefficient of pedigree relatedness on estimated relatedness (β2) was substantially lower than unity for all estimators, causing overestimation of the diversity conserved. A simple correction to achieve β2 = 1 improves both existing and new estimators. Using relatedness estimates with correction considerably increased diversity in structured populations, but did not do so or even decreased diversity in panmictic populations.
The Genetic Basis of Postzygotic Reproductive Isolation BetweenDrosophila santomeaandD. yakubaDue to Hybrid Male Sterility
Authors: Moehring Amanda J , Llopart Ana , Elwyn Susannah , Coyne Jerry A , Mackay Trudy F C 
Published: March 2006

AbstractA major unresolved challenge of evolutionary biology is to determine the nature of the allelic variants of “speciation genes”: those alleles whose interaction produces inviable or infertile interspecific hybrids but does not reduce fitness in pure species. Here we map quantitative trait loci (QTL) affecting fertility of male hybrids between D. yakuba and its recently discovered sibling species, D. santomea. We mapped three to four X chromosome QTL and two autosomal QTL with large effects on the reduced fertility of D. yakuba and D. santomea backcross males. We observed epistasis between the X-linked QTL and also between the X and autosomal QTL. The X chromosome had a disproportionately large effect on hybrid sterility in both reciprocal backcross hybrids. However, the genetics of hybrid sterility differ between D. yakuba and D. santomea backcross males, both in terms of the magnitude of main effects and in the epistatic interactions. The QTL affecting hybrid fertility did not colocalize with QTL affecting sexual isolation in this species pair, but did colocalize with QTL affecting the marked difference in pigmentation between D. yakuba and D. santomea. These results provide the basis for future high-resolution mapping and ultimately, molecular cloning, of the interacting genes that contribute to hybrid sterility.
A Genetic and Cytogenetic Map for the Duck (Anas platyrhynchos)
Authors: Huang Yinhua , Zhao Yonghui , Haley Chris S , Hu Shengqiang , Hao Jinping , Wu Changxin , Li Ning 
Published: March 2006

AbstractA genetic linkage map for the duck (Anas platyrhynchos) was developed within a cross between two extreme Peking duck lines by linkage analysis of 155 polymorphic microsatellite markers, including 84 novel markers reported in this study. A total of 115 microsatellite markers were placed into 19 linkage groups. The sex-averaged map spans 1353.3 cM, with an average interval distance of 15.04 cM. The male map covers 1415 cM, whereas the female map covers only 1387.6 cM. All of the flanking sequences of the 155 polymorphic loci—44 monomorphic loci and a further 41 reported microsatellite loci for duck—were blasted against the chicken genomic sequence, and corresponding orthologs were found for 49. To integrate the genetic and cytogenetic map of the duck genome, 28 BAC clones were screened from a chicken BAC library using the specific PCR primers and localized to duck chromosomes by FISH, respectively. Of 28 BAC clones, 24 were detected definitely on duck chromosomes. Thus, 11 of 19 linkage groups were localized to 10 duck chromosomes. This genetic and cytogenetic map will be helpful for the mapping QTL in duck for breeding applications and for conducting genomic comparisons between chicken and duck.
Synthetic Gene Recruitment Reveals Adaptive Reprogramming of Gene Regulation in Yeast
Authors: Stolovicki Elad , Dror Tali , Brenner Naama , Braun Erez 
Published: March 2006

Abstract
The recruitment of a gene to a foreign regulatory system is a major evolutionary event that can lead to novel phenotypes. However, the evolvability potential of cells depends on their ability to cope with challenges presented by gene recruitment. To study this ability, we combined synthetic gene recruitment with continuous culture and online measurements of the metabolic and regulatory dynamics over long timescales. The gene HIS3 from the histidine synthesis pathway was recruited to the GAL system, responsible for galactose utilization in the yeast S. cerevisiae. Following a switch from galactose to glucose—from induced to repressed conditions of the GAL system—in histidine-lacking chemostats (where the recruited HIS3 is essential), the regulatory system reprogrammed to adaptively tune HIS3 expression, allowing the cells to grow competitively in pure glucose. The adapted state was maintained for hundreds of generations in various environments. The timescales involved and the reproducibility of separate experiments render spontaneous mutations an unlikely underlying mechanism. Essentially all cells could adapt, excluding selection over a genetically variable population. The results reveal heritable adaptation induced by the exposure to glucose. They demonstrate that genetic regulatory networks have the potential to support highly demanding events of gene recruitment.
jing Is Required for Wing Development and to Establish the Proximo-Distal Axis of the Leg in Drosophila melanogaster
Authors: Culi Joaquim , Aroca Pilar , Modolell Juan , Mann Richard S 
Published: March 2006

Abstract
The establishment of the proximo-distal (PD) axis in the legs of Drosophila melanogaster requires the expression of a nested set of transcription factors that are activated in discreet domains by secreted signaling molecules. The precise regulation of these transcription factor domains is critical for generating the stereotyped morphological characteristics that exist along the PD axis, such as the positioning of specific bristle types and leg joints. Here we provide evidence that the Zn-finger protein encoded by the gene jing is critical for PD axis formation in the Drosophila legs. Our data suggest that jing represses transcription and that it is necessary to keep the proximal gene homothorax (hth) repressed in the medial domain of the PD axis. We further show that jing is also required for alula and vein development in the adult wing. In the wing, Jing is required to repress another proximal gene, teashirt (tsh), in a small domain that will give rise to the alula. Interestingly, we also demonstrate that two other genes affecting alula development, Alula and elbow, also exhibit tsh derepression in the same region of the wing disc as jing− clones. Finally, we show that jing genetically interacts with several members of the Polycomb (Pc) group of genes during development. Together, our data suggest that jing encodes a transcriptional repressor that may participate in a subset of Pc-dependent activities during Drosophila appendage development.
Assessment and Optimization of Mortality Prediction Tools for Admissions to Pediatric Intensive Care in the United Kingdom
Authors: Brady Anthony R. , Harrison David , Black Stephanie , Jones Sam , Rowan Kathy , Pearson Gale , Ratcliffe Jane , Parry Gareth J. ,   on behalf of the UK PICOS Study Group
Published: March 2006

OBJECTIVE. To assess the Pediatric Risk of Mortality (PRISM, PRISM III-12, and PRISM III-24) systems and the Pediatric Index of Mortality (PIM and PIM2) systems for use in comparing the risk-adjusted mortality of children after admission for pediatric intensive care in the United Kingdom.
METHODS. All PICUs in the United Kingdom were invited to participate. Predicted probability of PICU mortality was calculated using the published algorithms for PIM, PIM2, and PRISM and compared with observed mortality. These scores, along with PRISM III-12 and PRISM III-24, whose algorithms are not published, were optimized for the United Kingdom.
RESULTS. Of 26 PICUs in the United Kingdom, 22 (85%) were recruited, and sufficient prospective data were collected from 18 (69%) units on 10197 (98%) of 10385 admissions between March 2001 and February 2002. All published tools were found to have poor calibration but provided good discriminatory power. After estimation of UK-specific coefficients, only PIM2, PRISM III-12, and PRISM III-24 had satisfactory calibration. All models provided good discriminatory power. Funnel plots for all of the recalibrated models indicated that the risk-adjusted mortality for all units was consistent with random variation.
CONCLUSIONS. PIM2, PRISM III-12, and PRISM III-24 all were found to be suitable for use in a UK PICU setting. All tools provided similar conclusions in assessing the distribution of risk-adjusted mortality in UK PICUs. It now is important that these tools be used to monitor outcome and improve the quality of pediatric intensive care within the United Kingdom.
GENERALIZING THE USE OF DESCRIPTIVE ADJECTIVES THROUGH MODELLING1
Authors: Martin Jerry A. 
Published: March 2006

Two retarded children were exposed to daily imitation training in which teacher or nurse modelled and instructed each child to imitate 12 sentences containing one of six animal names. The subjects were praised for correct verbal imitation. Across three phases of a multiple‐baseline design, sentences varied as to the presence or absence of size and/or color adjectives describing the animals. In probe sessions at another time of day and in a different setting, the experimenter twice asked each subject to describe 12 different animal pictures. The subjects' use of descriptive adjectives (color and/or size) greatly increased during probe sessions as a function of the sentence content (presence or absence of color and/or size adjectives) in modelling and imitation training sessions. Generalization to descriptions of animals also not used in imitation training sentences was also obtained.Generalization to descriptions of animals not used in imitation training sentences was also obtained.
THE EFFECT UPON SIMPLE ANIMAL BEHAVIOR OF DIFFERENT FREQUENCIES OF REINFORCEMENT, PART II: SEPARATE CONTROL OF THE REINFORCEMENT OF DIFFERENT IRTs
Authors: Anger Douglas 
Published: March 2006

Rats' responding was stabilized for over 35 days on 4‐min variable‐interval reinforcement. Reinforcements per hour for 4‐sec wide classes of interresponse times were then separately controlled by adjusting those for each class to the variable‐interval values that had just prevailed. This produced little or no change in interresponse times, indicating that the new procedure was substantially equivalent to a variable‐interval schedule. The variable‐interval schedule produced a high and stable conditional probability of interresponse times in the 0‐ to 4‐sec class, associated with a peak in reinforcements per hour for this class. Reducing the reinforcements per hour for this class while raising that for another class (by 3.3 reinforcements per hour) significantly reduced the conditional probability of 0‐ to 4‐sec interresponse times. Restoring the 3.3 reinforcements per hour to the 0‐ to 4‐sec class significantly elevated the conditional probability of interresponse times in this class. Hence, it is concluded that the distribution of interresponse times produced by a subject during some variable‐interval schedules is determined partly by the relative reinforcement of different interresponse times that the variable‐interval schedule provided.(Reprinted from Part II of the Final Report of Research under Contract DA‐49‐007‐MD‐408 with the Medical Research and Development Board, Office of the Surgeon General, Department of the Army, 31 December 1954. Edwin B. Newman, Responsible Investigator; Douglas Anger, Research Assistant and author of report. Experimental work done in the Psychological Laboratories of Harvard University.)
REVIEW OF B. F. SKINNER'S THE BEHAVIOR OF ORGANISMS1
Authors: Hilgard Ernest R. 
Published: March 2006

As I reread my review nearly 50 years later, I think of the circumstances. I had heard a paper by Fred at the Ithaca meeting of the APA in 1932, and recall the praise by Edna Heidbreder, who was sitting next to me, whose remark was that “He has a clean mind.” The year before his book appeared, I had already cited eight of his published papers in a review of the conditioned response in relation to conventional learning experiments that appeared in the Psychological Bulletin (1937, 34, 61–102). It may be because of that the editor sent me Fred's book to review.When I received the copy of his new book to review, I read it carefully, and soon reported on it orally before Lewis Terman's weekly seminar to get comments and questions before revising my review. I was pleased by Terman's excitement over the originality of Fred's approach.
The Effect of Combination of Recombinant Human Bone Morphogenetic Protein‐2 and Basic Fibroblast Growth Factor or Insulin‐Like Growth Factor‐I on Dental Implant Osseointegration by Confocal Laser Scanning Microscopy
Authors: Lan Jing , Wang Zhifeng , Wang Yining , Wang Jiawei , Cheng Xiangrong 
Published: March 2006

Background: The healing period of bone‐implant osseointegration usually varies from 3 to 6 months or even longer. Failure may occur during this time. This study aimed to investigate whether osseointegration of dental implants can be enhanced by the combination of growth factors.Methods: Sixty‐four implants were coated with polylactic acid and divided into four groups. Group I was applied with 1.0 mg recombinant human bone morphogenetic protein‐2 (rhBMP‐2) and 200 μg recombinant human basic fibroblast growth factor (rhbFGF), group II with 1.0 mg rhBMP‐2 and 250 μg recombinant human insulin‐like growth factor‐I (rhIGF‐I), group III with 1.0 mg rhBMP‐2, and group IV without growth factors as control. In total, 16 rabbits were used, and two osteotomies were drilled on each side of the femur, in which four different groups were randomly placed. Four weeks after implanting, 20 mg calcein green/kg body weight was administered intravenously, and 8 weeks after implanting, 20 mg alizarin/kg body weight was administered intravenously. Twelve weeks after implanting, the animals were sacrificed. The block of bone with implants was embedded in methylmethacrylate and sectioned, and the percentage of new bone surrounding the implant was analyzed by confocal laser scanning microscopy.Results: There was a statistical difference in bone formation between rhBMP‐2–applied groups and the non‐applied group at 4 or 8 weeks, and no significant difference between groups I and II (although bone formation in group II was greater than that in group I at 4 weeks). The bone formation in group II was greater than that in group III at 4 or 8 weeks. The formed bone in group I was also greater than the one in group III at 8 weeks, but there was no difference at 4 weeks.Conclusions: rhBMP‐2 could increase new bone formation, and it acted synergistically with rhbFGF and rhIGF‐I to improve bone‐implant osseointegration. The combination of rhBMP‐2 and rhbFGF (group 1) showed faster growth of new bone than other groups at 8 months.
Effect of a Controlled‐Release Chlorhexidine Chip on Clinical and Microbiological Parameters and Prostaglandin E2 Levels in Gingival Crevicular Fluid
Authors: Mızrak Tansel , Güncü Güliz N. , Çağlayan Feriha , Balcı Tansel Ansal , Aktar Gülseren Samancı , İpek Fikret 
Published: March 2006

Background: The aim of the present study was to determine the effect of a chlorhexidine chip on crevicular prostaglandin E2 (PGE2) levels and on the clinical and microbiological parameters of periodontitis when used as adjunctive therapy to scaling and root planing (SRP) in patients with chronic periodontitis.Methods: This randomized single‐blind study was carried out in parallel design. The test group received SRP plus chlorhexidine chip, whereas the control group received SRP alone. Thirty‐four subjects, aged 20 to 55 years, with chronic periodontitis were recruited. Clinical indices, microbiological samples, and gingival crevicular fluid (GCF) samples were evaluated at baseline and after 1, 3, and 6 months. Microbiological samples were evaluated under a light microscope. GCF PGE2 levels were determined using radioimmunoassay.Results: Significant improvements could be found for all clinical variables in both groups over the study period. The mean changes in probing depth obtained by SRP plus chlorhexidine chip were greater than those obtained by the SRP alone group at 3 and 6 months. In the test group, there was also significant gain in clinical attachment level at 6 months. When data were combined from all groups, significant reductions in GCF PGE2 levels and number of microorganisms were noted at all time points. However, in the test group, reduction was greater at 6 months for crevicular PGE2 level and at 3 and 6 months for proportions of spirochetes.Conclusion: Based on the findings of this study, the chlorhexidine chip reduced GCF PGE2 levels and had positive effects on clinical parameters and subgingival flora when used as adjunctive therapy to SRP in patients with chronic periodontitis.
Effects of a Mineralized Human Cancellous Bone Allograft in Regeneration of Mandibular Class II Furcation Defects
Authors: Tsao Yi‐Pin , Neiva Rodrigo , Al‐Shammari Khalaf , Oh Tae‐Ju , Wang Hom‐Lay 
Published: March 2006

Background: A solvent‐preserved, mineralized human cancellous bone allograft (MBA) was recently developed. However, its effect in regenerating furcation defects remains to be determined. Hence, the aim of the study is to evaluate the effects of this newly introduced MBA, with and without a bioabsorbable collagen membrane, for the treatment of mandibular class II furcation defects.Methods: Thirty subjects with Hamp's Class II buccal or lingual furcation defects in lower molars were randomly assigned to open flap debridement (OFD), MBA, or MBA with a bioabsorbable collagen membrane (guided tissue regeneration [GTR] + MBA) groups. Clinical and defect measurements were obtained at the initial visit and at 6‐month reentry surgeries. The data were analyzed for intra‐ and intergroup comparisons and associations of treatment with probability of clinical improvement.Results: Out of a total of 30 subjects, 27 individuals completed the study. Vertical bone fill (VBF) was −1.6 ± 2.1 mm in OFD, 1.9 ± 1.4 mm in MBA, and 0.7 ± 0.9 mm in GTR + MBA groups. VBF in MBA and GTR + MBA groups was significantly higher than that in the OFD group (P <0.05). Horizontal bone fill (HBF) was 0.2 ± 1.7 mm, 1.1 ± 0.9 mm, and 1.1 ± 0.9 mm for OFD, MBA, and GTR + MBA groups, respectively. However, HBF, recession, clinical attachment level gain, and probing depth reduction at furcations showed no differences among groups.Conclusions: Results obtained from this study indicate that solvent‐preserved, mineralized human cancellous allograft, with or without collagen membrane, can significantly improve bone fill in mandibular Class II furcation defects. In addition, initial vertical defect depth was found to be the only factor that was associated with a higher probability of clinical improvement.
Demographic Variables Affecting Patient Referrals From General Practice Dentists to Periodontists
Authors: Zemanovich Mark Roy , Bogacki Russell E. , Abbott David M. , Maynard J. Gary , Lanning Sharon K. 
Published: March 2006

Background: Within dentistry, a limited body of literature exists regarding the referral relationships between general practitioners (GPs) and specialists. The purpose of this study was to investigate the referral relationship between GPs and periodontists within the state of Virginia.Methods: A survey was developed that focused on the demographic variables in the referral relationship between GPs and periodontists. The survey was mailed to 800 dentists throughout the state of Virginia. Descriptive statistics were completed along with multivariate logistic regression analysis comparing the responses with the number of patients referred per month to periodontists.Results: Female respondents were more likely to refer three or more patients per month to a periodontist than a male respondent (P <0.02). Those dentists who practiced with one other dentist were twice as likely to refer more frequently when compared to solo practitioners or larger group practices (P <0.03). Dentists employing two hygienists were more likely to refer patients than those with fewer hygienists (P <0.02). Those whose practices were >5 miles from the nearest periodontist were more likely to refer patients compared to dentists geographically closer to a periodontist (P <0.02). No other variables had a significant effect on the referral of more patients per month to a periodontist.Conclusions: This study indicates that four demographic variables have a statistical influence on the number of referrals per month from a GP to a periodontist. These variables are as follows: female gender, practicing with one other dentist, employing two or more hygienists, and being >5 miles away from the nearest periodontist.