Search

Simultaneous hermaphrodites offer the chance to study antagonistic coevolution between the sexes when individuals function in both roles. Traumatic mating by hypodermic insemination has repeatedly evolved in hermaphroditic taxa, but evidence for the fitness costs of such male-advantage traits is lacking. When reared in isolation, specimens of the sea slug Alderia willowi (Opisthobranchia: Sacoglossa) initially laid clutches of unfertilized eggs but 4 days later began self-fertilizing; this is only the third report of selfing inan Alderia if penetration of the body wall bypasses internal mechanisms that promote outcrossing. Selfing specimens and slugs reared inpairs had reduced fecundity compared to isolated slugs laying unfertilized clutches, suggesting that hypodermic insemination imposes a cost of mating. Egg production increased for field-caught slugs separated after mating compared to slugs held in pairs, a further indication that accessibility to mates imposes a fitness cost to the female function. Such antagonism can confer a competitive advantage to slugs mating in the male role but diminish reproduction in the female role among hermaphrodites capable of long-term sperm storage. Alderia willowi is also a rare case of poecilogony, with adults producing either plankitotrophic or lecithotrophic larvae. Our rearing studies revealed that most slugs switched between expressed development models at some point; such reproductive flexibility within individuals is unprecedented, even among poecilogonous species., Introduction Sexually antagonistic traits that confer a male advantage are commonplace in animals (Rice, 1996; Partridge and Hurst, 1998; Arnqvist and Rowe, 2005). Physical features include genital armature and other [...]

Epizoochory is the mode of seed dispersal where a diaspore (disseminating plant propagule) is disseminated on the external surface of an animal. While the structures that facilitate diaspore adherence are diverse, epizoochory is considered to be relatively rare (approximately 10% of angiosperms), but is commonly utilized by several invasive plant species. We experimentally sought species specific associations between the adherence and retention of eight common plant species' diaspores and five mammalian furs, plus human clothing. We sought relationships between both fur and diaspore characteristics in both the adherence and retention of diaspores. Diaspores of Geum aleppicum were the only ones interacting significantly better with one kind of substrate (mouse fur) than diaspores of all other plant species by being retained well in mouse fur. Alternatively, bison fur behaved as a 'generalist' disperser, by consistently accommodating the adherence and retention of a wide range of diaspore morphologies. Finally, exotic plant species displayed a higher tendency than natives to adhere to a variety of mammal fur types, indicating a more flexible dispersal strategy for the invasive habit., INTRODUCTION Effective dispersal by plants is attained if propagules reach habitats favorable for survival, growth and reproduction (Stamp, 1989). Ridley (1930) recognized anemochory (dispersal by wind), hydroehory (dispersal by water) [...]

ABSTRACT As interest and efforts in ecological restoration of native bivalve populations grow, the genetic implications of various restoration strategies are often unclear to resource managers and restoration practitioners, even [...]

The ρ statistic is commonly used to infer chronological dates for molecular lineages, especially from mitochondrial DNA sequences obtained in anthropological contexts. Since this approach was described 12 years ago, it has been applied to estimate molecular dates in more than 200 studies, including some published in top-tier journals. However, this method has not been well evaluated, and the accuracy of dates obtained from the ρ statistic remains unknown, especially for genetic data collected from populations with complex demographic histories. Here, molecular dates inferred from ρ are compared against coalescent expectations from a range of demographic models. This exercise reveals considerable inaccuracy. Molecular dates based on ρ have a slight downward bias with large asymmetric variance and commonly exhibit substantial type I error rates, where the true age of a lineage falls outside the 95% confidence bounds derived from the variance of ρ. Furthermore, demography proves to be a strong confounding factor in estimating molecular dates accurately, especially for populations in which bottlenecks, founder events, and size changes have played important historical roles. Therefore considerable caution should be applied to inferences made from molecular dates based on the ρ statistic, many of which may be misleading and warrant considerable skepticism. KEY WORDS: GENETIC DATING, MOLECULAR CHRONOLOGY, ρ STATISTIC, MITOCHONDRIAL DNA., A common aim in many genetic studies is determining chronological ages from sequence data. Routine questions include estimating the time to the most recent common ancestor (TMRCA) (Cox et al. [...]

Abstract: Taylorella asinigenitalis sp. nov is a nonpathogenic gram-negative bacterium recently isolated from the genital tract of male donkeys. The bacterium is phenotypically indistinguishable from Taylorella equigenitalis, a pathogen that [...]

The academic success of students in introductory science courses is influenced by a variety of factors, the most important of which is academic motivation (Moore, 2005, 2006, 2007; Thomas & [...]

Abstract: It is well known that standard peptides, which comprise proteinogenic amino acids, can act as specific chemical probes to target proteins with high affinity. Despite this fact, a number [...]

Abstract: Although home-based cardiac rehabilitation (CR) programs have been shown to produce significant increases in exercise capacity, obtaining patient adherence to these programs has been challenging. It is therefore critical [...]

Keywords: glucocorticoid receptor; nuclear translocation; high content screening; green fluorescent proteins; androgen receptor 1029 Original ArticlesA High-Content Glucocorticoid Receptor Translocation Assay for Compound Mechanism-of-Action Evaluation SAGE Publications, Inc.200710.1177/1087057107309353 MicheleAgler Lead [...]

Byline: Oliver Durr (Genedata AG, Basel, Switzerland, oliver.duerr@genedata.com); Francois Duval (Merck Serono International SA, Geneva, Switzerland); Anthony Nichols (Merck Serono International SA, Geneva, Switzerland); Paul Lang (Merck Serono International SA, [...]

Byline: Richard E. Herman (Nastech Pharmaceutical Company, Inc., Bothell, Washington); Ekaterina G. Makienko (Nastech Pharmaceutical Company, Inc., Bothell, Washington); Mary G. Prieve (Nastech Pharmaceutical Company, Inc., Bothell, Washington); Mark Fuller [...]

Byline: Shaun P. Falk (Department of Pharmacology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin); Andrew T. Ulijasz (Department of Pharmacology, University of Wisconsin School of Medicine [...]

Keywords: p53; ubiquitination; high-throughput screening; mdm2; time-resolved fluorescence resonance energy transfer 1050 A High-Throughput Screen Measuring Ubiquitination of p53 by Human mdm2 SAGE Publications, Inc.200710.1177/1087057107308556 Monique F.Murray GlaxoSmithKline (GSK) Screening [...]

Efforts by state and local officials to enact balanced treatment laws represent attempts to displace the methodological naturalism of science with theological supernaturalism. Advocates of creation science and intelligent design [...]

Recent data from the National Center for Education Statistics (2002) noted that students with disabilities make up 13.2% of the student population in public schools. Due to recent federal government [...]

Abstract: We describe transitions between exercise stages of change in people with coronary artery disease (CAD) over a 6-month period following a CAD-related hospitalization and evaluate constructs from Protection Motivation [...]

Nonequilibrium capillary electrophoresis of equilibrium mixtures (NECEEM) is a new separation-based affinity method. It has kinetic capabilities exceeding those of surface plasmon resonance (SPR) and does not require immobilization of [...]

Summary For herbal medicinal products the methodology of observational cohort studies (observational studies, drug monitoring studies, Anwendungsbeobachtung) represents a useful addition to clinical trials. The key objectives are the documentation [...]

The aim of the present study was to investigate the extent and mode of inheritance of hand osteoarthritis (OA) using a large sample of ethnically homogeneous pedigrees. Two types of segregation analysis (SA) models were examined. Type I models used the data adjusted for potential significant covariates, particularly age and sex, prior to genetic analysis. Type II models incorporated effects of the potential covariates into major gene penetrance functions, permitting an account of the genotype covariate-specific effect on study variables. The results of this study strongly supported the hypothesis of a major gene effect and additional multifactorial component. The best-fitting model was the Mendelian one with an additive type of inheritance. The estimates obtained using the standard three-factor variance decomposition analysis suggest that age (72.8%) and major gene (14.5%) are the main sources of interindividual differences in the development of hand OA. The contribution of the putative major gene on age- and sex-adjusted OA phenotype variation was 55% in the present study. KEY WORDS: OSTEOARTHRITIS, SEGREGATION ANALYSIS, GENETICS, Osteoarthritis (OA) is a process of joint disintegration that is characterized by changes in the synovium, cartilage loss, and reactive new bone formation at joint margins, the latter primarily by [...]

This study aimed to provide data on lateral preferences among older subjects, to analyze age differences, and to determine interrelations between lateral preferences. Four functional preferences (handedness, footedness, eyedness, earedness) and three postural lateral preferences (hand-clasping, arm-folding, leg-crossing) were assessed in 628 Germans (252 men, 376 women) aged between l9 and 90 years. Sex differences, age differences, and associations between lateralities were analyzed applying chi-square tests. Logistic regression analyses considering age, sex, and interactions between variables were applied to analyze combined effects on laterality measures. Right-sided preference for handedness, footedness, eyedness, earedness, and leg-crossing characterized 86.8%, 77.1%, 70.9%, 67.8%, and 56.6%, respectively, of subjects, while a left-sided preference for hand-clasping and arm folding characterized 56.4% and 60.2%, respectively, of all participants. Results are within the range of other populations . Only footedness differed between the sexes: there were more left-footed men. Older cohorts showed a rightward shift in handedness, eyedness, earedness, and leg-crossing, the opposite for arm-folding. No age-related differences exist in footedness or hand-clasping. Logistic regression models indicate no interaction between age and sex for each laterality measure. The four functional lateralities are significantly interrelated. All also are positively associated with leg-crossing. Conversely, the postural lateralities generally are not correlated, although leg-crossing and arm-folding are, inversely. The observed relationships among lateralities support the hypothesis that handedness, footedness, legcrossing, and earedness might be aspects of a larger phenotype that is independent of hand-clasping and arm-folding. KEY WORDS: LATERAL PREFERENCES, INCIDENCES. INTERRELATIONS, AGE DIFFERENCES, ELDERLY, GERMANS, It is well established that differences in lateral preferences exist in humans. The term lateral preference refers to the asymmetrical use of paired limbs or sense organs. Human individuals differ [...]

BECAUSE THE DELIBERATE RELEASE OF DISEASE AMONG US LIVESTOCK COULD HAVE ENORMOUS CONSEQUENCES, SCIENTISTS AND POLICYMAKERS MUST SEEK TO PREVENT SUCH A TERRORIST ACT OR MITIGATE ITS EFFECTS One lesson [...]

Kellenberger, Stephan, and Laurent Schild. Epithelial Sodium Channel/Degenerin Family of Ion Channels: A Variety of Functions for a Shared Structure. Physiol Rev 82: 735-767-2002; 10.1152/physrev.00007-2002.--The recently discovered epithelial sodium channel [...]

Agriculture is a defining characteristic of human civilization. Its development as a means of providing sustenance marked the transition from a nomadic existence to an urban lifestyle. And no other [...]

Abstract Infections with mold pathogens have emerged as an increasing risk faced by patients under sustained immunosuppression. Species of the Aspergillus family account for most of these infections, and in [...]

Because both biological phenomena and the measurements researchers make in studying them are often quite variable, methods of statistical analysis have much to offer science. Statistical analysis has many aspects, [...]

The 21st century is an exciting time for biological scientists and other researchers interested in complex systems. Relating biodiversity to ecological function and sustainability, understanding the dynamics of coupled human [...]

In the 20th century geneticists began to unravel some of the simpler aspects of the etiology of inherited diseases in humans. The theory of linkage analysis was developed and applied long before the advent of molecular biology, but only the technological advances of the second half of the 20th century made large-scale gene mapping with a dense genome-spanning set of markers a reality. More recently, the primary topic of interest has shifted from simple Mendelian diseases, for which genotypes of some gene are the cause of disease, to more complex diseases, for which genotypes of some set of genes together with environmental factors merely alter the probability that an individual gets the disease, although individual factors are typically insufficient to cause the disease outright. To this end, a great deal of dogma has evolved about the best way to skin this cat, although to date success has been minimal with any approach. We postulate that the main reason for this is a lack of attention to experimental design. Once the data have been ascertained, the most powerful statistical methods will not be able to salvage an inappropriately designed study (Andersen 1990). Each phenotype and/or population mandates its own individually tailored study design to maximize the chances of successful gene mapping. We suggest that careful consideration of the available data from real genotype-phenotype correlation studies (as opposed to oversimplified theoretically tractable models), and the practical feasibility of different ascertainment schemes dictate how one should proceed. In this review we review the theory and practice of gene mapping at the close of the 20th century, showing that most methods of linkage and linkage disequilibrium analysis are similar in a fundamental sense, with the differences being related more to study design and ascertainment than to technical details of the underlying statistical analysis. To this end, we propose a new focus in the field of statistical genetics that more explicitly highlights the primacy of study design as the means to increase power for gene mapping. KEY WORDS: LINKAGE, LINKAGE DISEQUILIBRIUM, LIKELIHOOD ANALYSIS, EXPERIMENTAL DESIGN, ASCERTAINMENT, COMPLEX DISEASE, The development of statistical genetics in the 20th century can be loosely divided into 3 categories: (1) theoretical development of statistical methods, (2) technological advances leading to application of those [...]

The measurement and interpretation of phenotypic and genetic correlations and covariances has been gaining an increasingly central role in the study of evolutionary processes. The study of developmental and functional [...]

I. Abstract A phylogenetic analysis of the grass family (Poaceae) was conducted using two character sets, one representing variation in 364 mapped and cladistically informative restriction sites from all regions [...]

After leaving Germany's Max Planck Institute for Developmental Biology in 1995, Mary Mullins strolled slowly through the airport. Boarding a plane bound for the United States, she gingerly made her [...]

Β-galactosidase activity is known to exist in Drosophila melanogaster, but a detailed analysis of the tissue-specific patterns of activity has not previously been reported. Such an analysis is of particular interest because Drosophila is commonly used for making transformants that carry fusion genes in which the E. coli Β-galactosidase gene, lacZ, is used as a reporter gene. When these transformants are analyzed for Β-galactosidase activity by using chromogen X-gal staining, the method does not distinguish true fusion-gene activity from endogenous Β-galactosidase activity or from the Β-galactosidase activity of bacterial contaminants. Therefore, detailed maps of endogenous Β-galactosidase activity in this organism would help to prevent errors in data interpretation and would indicate which stages were most appropriate for experiments with the lacZ transformants. We have constructed such maps by applying X-gal staining methods to serial frozen sections and whole mounts of larval, prepupal, pupal, and adult stages of D. melanogaster reared under axenic conditions. Results showed endogenous Β-galactosidase activity in a variety of organs including the larval intestine, spiracles, lymph glands, cellular epidermis, and eye-antenna imaginal discs; the pupal cellular epidermis, lymph glands, imaginal tissues, fat body, and spiracle; and the adult pericardial cells, thoracic nephrocytes, ventriculus, and reproductive system. The good correlation between staining and metamorphic remodeling and phagocytic activity indicates that endogenous Β-galactosidase is physiologically interesting., Introduction The glycosidase Β-galactosidase is known to occur in a variety of microorganisms, plants, and animals (Wallenfels and Weil, 1972), and the fruit fly Drosophila melanogaster is no exception (Knipple [...]

Some of the major questions in evolutionary paleobiology concern the origin and fate of biological innovations, the pace of evolution, clade replacements, patterns of origination and extinction, and other large-scale [...]

Since 1973, when Herbert and Irene Baker first documented the widespread occurrence of amino acids in plant nectars, a wide variety of studies have shown that: 1) plants with different [...]

The study of form and function in organisms has a long and distinguished ,story, dating at least from the sixth century B.C., the time of the first recorded methodical investigations [...]

There is widespread interest in obtaining genetic samples from human populations worldwide for various studies of human genetic diversity. Many samples exist today only in the form of small, rare, irreplaceable, or archival samples, such as material from ancient bone, hair bulbs, or remnants of samples collected in the field decades ago for the purpose of protein and blood type analysis. Here, we describe the application of an approach to amplify DNA, which we call adapter attachment and amplification (AAA). This approach is useful for amplifying the genome in a reasonably representative way from small amounts of starting material using standard PCR-based methods. We apply a version of these methods to DNA extracted from washed red blood cells collected in the 1960s and 1970s in the Amazon basin. AAA and similar approaches may make the analysis of archival samples possible without exhausting that irreplaceable material and may lead to greatly improved efficiency in collecting and using new anthropological genetic samples., The study of human genetic diversity (i.e., variation at specific loci subject to Mendelian inheritance) in the human species as a whole has a history that goes back nearly a [...]

How scientists frame their questions often controls their answers. For example, suppose two biologists 30 years ago were observing the same phenomenon, the protozoan Amoeba, and they both ask the [...]

Soltis, D. E., P. E. Soltis, and B. G. Milligan. 1992c. Intraspecific chloroplast DNA variation: systematic and phylogenetic implications. Pages 117-150 in P. S. Soltis, D. E. Soltis, and J. [...]

Abstract. - Empirical studies of mimicry have rarely been conducted under natural conditions. Field investigations of some lepidopteran systems have provided a bridge between experiments examining artificial situations and the [...]

KEY WORDS: conjugation, transduction, transformation, electroporation, mapping, whole genome analysis, physical and genetic maps CONTENTS INTRODUCTION AND HISTORICAL PERSPECTIVE 660 THE AIMS OF GENETIC ANALYSIS 661 The Historical Approach to [...]

A biology teacher has developed a rare and troubling neurologic disorder. The signs and symptoms are well controlled with medications but the side effects are unpleasant. He hears of an [...]

Ecology focuses on tangible organisms; ecological complexity results from the myriad of patterns with which the many different types of organisms interact in their environments. Yet ecology is by no [...]

Use of Tropical Rainforests by Native Amazonians Indigenous peoples have lived in the rainforest of Amazonia for a long times, probably thousands of years. They were once more numerous and [...]

Landscape Conservation in a Forested Wetland Watershed More than one-half of the 40 million ha of wetlands in the coterminus United States is forested (Frayer et al. 1983). Most of [...]

Although nonparametric statistical methods have a role to play in the analysis of data, often their virtues are overstated and their deficiencies overlooked. A recent Special Feature in Ecology advocated nonparametric methods because of an erroneously stated advantage that they require no assumptions regarding the distribution underlying the observations. The present paper points out some often-ignored features of nonparametric tests comparing two means, and advocates parameter estimation as a preferred alternative to hypothesis testing in many situations., Key words: hypothesis testing; nonparametric methods; normal distribution, parameter estimation; Wilcoxon-Mann-Whitney test vs. t test. How often have you read something like, 'Our data were not normally distributed, so we [...]

Written dissemination of information is an essential part of science. As biologists, we all are or will be authors. But our commitment to publication does not end there; we also [...]