Integrin binding human antibody constant domains--probing the C-terminal structural loops for grafting the RGD motif

Recently, it has been demonstrated that loops of the crystallizable fragment of IgG1 (IgG1-Fc) can be engineered to form antigen-binding sites. In this work C-terminal structural loops in the CH3 domains of homodimeric IgG1-Fc have been functionalized to form integrin-binding sites in order to probe the effect of engineering on structural integrity and thermal stability of IgG1-Fc as well as on binding to the ligands Protein A, CD16 and FcRn, respectively. The peptide sequence GCRGDCL - a disulfide-bridged cyclic heptapeptide that confers binding to human αvβ3 integrin was introduced into AB, CD and/or EF loops and single and double mutants were heterologously expressed in Pichia pastoris. Integrin binding of engineered IgG-Fc was tested using both binding to coated αvβ3 integrin in ELISA or to αvβ3-expressing K562 cells in FACS analysis. Additionally, blocking of αvβ3-mediated cell adhesion to vitronectin was investigated. The data presented in this report demonstrate that bioactive integrin-binding peptide(s) can be grafted on the C-terminal loops of IgG-Fc without impairing binding to effector molecules. Observed differences between the investigated variants in structural stability and integrin binding are discussed with respect to the known structure of IgG-Fc and its structural loops.     

Sexual size dimorphism and timing of spring migration in birds

Sexually selected traits are limited by selection against those traits in other fitness components, such as survival. Thus, sexual selection favouring large size in males should be balanced by higher mortality of larger males. However, evidence from red-winged blackbirds (Agelaius phoeniceus) indicates that large males survive better than small males. A survival advantage to large size could result from males migrating north in early spring, when harsh weather favours large size for energetic reasons. From this hypothesis we predicted that, among species, sex differences in body size should be correlated with sex differences in timing of spring migration. The earlier males migrate relative to females, the larger they should be relative to females. We tested this prediction using a comparative analysis of data collected from 30 species of passerine birds captured on migration. After controlling for social mating system, we found that sexual size dimorphism and difference in arrival dates of males and females were significantly positively correlated. This result is consistent with the hypothesis that selection for survival ability promotes sexual size dimorphism (SSD), rather than opposes SSD as is the conventional view. If both natural selection and sexual selection favour large adult males, then limits to male size must be imposed before males become adults.     

Estimation in independent observer line transect surveys for clustered populations

This paper introduces a framework for animal abundance estimation in independent observer line transect surveys of clustered populations. The framework generalizes an approach given in Chen (1999, Environmental and Ecological Statistics 6, in press) to accommodate heterogeneity in detection caused by cluster size and other covariates. Both parametric and nonparametric estimators for the local effective search widths, given the covariates, can be derived from the framework. A nonparametric estimator based on conditional kernel density estimation is proposed and studied owing to its flexibility in modeling the detection functions. A real data set on harbor porpoise in the North Sea is analyzed.     

Environmental factors influencing zooplankton species composition of lakes in north-central Ontario,Canada

To assess the relative importance of lake chemistry, morphometry and zoogeography on limnetic zooplankton, we collected zooplankton, water, and morphometric data from 132 headwater Canadian Shield lakes in 6 regions across north-central Ontario. A subset of these lakes (n = 52) were fished with gill nets. We clustered lakes based on their zooplankton species composition (presence/absence). Discriminant analysis was employed to determine how well lake characteristics could predict zooplankton community types. Correct classification of zooplankton communities for three models ranged from 72 to 91%. Lake size, lake location, and buffering capacity were ranked as the most important factors separating lake groups. Fish abundance (CPUE) was not significant in distinguishing between zooplankton communities. Though the range of lake sizes was limited (1–110 ha), larger lakes tended to support more species. Lake location (zoogeography) also influenced species composition patterns. Although Algoma lakes tended to be larger (\-x = 18.0 ha, other lakes \-x = 2.5 ha), they supported relatively depauperate zooplankton communities. Buffering capacity was ranked third in the discriminant analysis models, but pH and alkalinity were not significantly different between lake groups.     

Preservation and computer-aided microscopic analysis of planktonic Protozoa and algae

Samples of microplankton and larger nanoplankton (5 to 200 m) are preserved with a combination of Lugol's solution and DaFano's fixative. Organisms are then settled on a gelatin-coated slide, dried and embedded in 40 percent glycerin. Counting and sizing is performed under a microscope using a drawing tube, which facilitates measuring the organisms with a microcomputer-interfaced caliper. An interactive computer program, written in BASIC, allows for estimating the volumes of cells in up to 40 shape/species categories. The program then saves data on a disk, retrieves them, and calculates the results either for individual species (abundance, biomass, and mean cell volume) or as a pooled size spectrum of all organisms measured.     

STRUCTURE,LIFE HISTORY AND SYSTEMATICS OF RHOICOSPHENIA (BACILLARIOPHYTA). V. INITIAL CELL AND SIZE REDUCTION IN RH. CURVATA AND A DESCRIPTION OF THE RHOICOSPHENIACEAE FAM. NOV.1

The initial epivalve of Rhoicosphenia curvata (Kütz.) Grun. differs from vegetative valves in having a strongly arched section, a wide hyaline marginal strip, no pseudosepta, an unthickened margin, and a terminal raphe fissure at the head pole. The initial epivalve is of the D type, with short raphe fissures. The epicingulum consists of three bands as usual, but they are narrower and more delicate than those of vegetative cells. The initial hypovalve and hypocingulum are similar in every way to those of vegetative cells, except for the rounded section of the hypovalve. During size reduction the almost isopolar outline of the initial valves and their immediate descendants gives way to an increasingly strong heteropolarity, and this is accompanied by changes in the relative lengths of the raphe slits and the shape of the central area. Different populations have different gametangium and initial cell sizes, suggesting the presence of races within the species. The structure of the initial cell indicates that Rhoicosphenia is less closely related to the monoraphid genera than to the gomphocymbelloid genera, confirming conclusions reached from studies of the vegetative cell and auxospore formation. Rhoicosphenia should therefore be separated into a new family, the Rhoicospheniaceae, which is described.     

Fruit Traits in Baboon Diet: A Comparison with Plant Species Characteristics in West Africa

Primate fruit choice among plant species has been attributed to different morphological plant and fruit characteristics. Despite a high abundance of animal-dispersed plant species in the savanna–forest mosaic of West Africa, few data are available on the interplay between morphological fruit traits and primate fruit consumers in this ecosystem. We tested whether olive baboons (Papio anubis) at Comoé National Park, north-eastern Ivory Coast, prefer fruit species with particular characteristics relative to the availability of these traits among the woody plant species at the study site. Specifically we were interested in the suites of traits that best predict fruit choice and seed handling by baboons. The baboons ate fruit/seeds from 74 identified plant species, representing 25 percent of the regional pool of woody plant species. They preferred trees to shrubs and lianas as fruit sources. Otherwise, baboons seemed to consume whatever fruit type, color, and size of fruit and seeds available, though they especially included larger fruit into their diet. Against expectations from the African bird–monkey fruit syndrome of brightly colored drupes and berries, baboons ate mostly species having large, dull-colored fruit. Fruit type and color best described whether baboons included a species into their diet, whereas fruit type and seed size best predicted whether baboons predated upon the seeds of their food plant species. As most plant species at the study site had medium-sized to large fruits and seeds, large frugivores like baboons might be particularly important for plant fitness and plant community dynamics in West African savanna–forest ecosystems.     

Comparison of the cardiac effects between quinazoline-based α<Subscript>1</Subscript>-adrenoceptor antagonists on occlusion–reperfusion injury

Quinazoline-based compounds such as prazosin and its congeners including doxazosin, bunazosin, and terazosin are widely used as antihypertensive agents. However, there were many clinical observations showing that using these agents may result in higher risk of cardiovascular accidents in recent years. In this study, we compared the effects of four α-adrenoceptor antagonists: prazosin, doxazosin, bunazosin, and terazosin on occlusion–reperfusion injury. Langendorff-perfused rat hearts were pretreated with these four antagonists, and then the left main coronary artery was occluded. After 30 min occlusion, the hearts were reperfused for 2 h and the infarct sizes were measured. Two of the compounds studied, prazosin and doxazosin, apparently increased infarct size, CK-MB, and LDH activities after 2 h reperfusion. In contrast, bunazosin decreased infarct size and those biochemical indicators of cellular damage compared to control hearts. Although infarct size after reperfusion was differently changed by these four α-adrenoceptor antagonists, TUNEL-positive nuclei and caspase-3 protein expressions of all the groups were not significantly different. We supposed that the different effects of these four agents on infarct size came from the difference in necrosis rather than apoptosis.     

Sample size reestimation by Bayesian prediction

We review a Bayesian predictive approach for interim data monitoring and propose its application to interim sample size reestimation for clinical trials. Based on interim data, this approach predicts how the sample size of a clinical trial needs to be adjusted so as to claim a success at the conclusion of the trial with an expected probability. The method is compared with predictive power and conditional power approaches using clinical trial data. Advantages of this approach over the others are discussed.     

Floral display size and spatial distribution of potential mates affect pollen deposition and female reproductive success in distylous Pulmonaria officinalis (Boraginaceae)

In animal‐pollinated plants, both the spatial distribution of flowering individuals and the number of flowers that an individual displays affect pollen deposition rates and female reproductive success. Heterostylous species are likely to be particularly sensitive to the contingencies of spatial distribution, as they are reproductively subdivided into distinct mating groups, which usually exhibit self‐ and intra‐morph incompatibility and differ in floral morphology. In this paper, we explore the joint effects of both spatial distribution of potential mates and floral display size on morph‐specific pollen deposition rates and seed set patterns in two natural populations of Pulmonaria officinalis, a distylous species with a weak self‐incompatibility system. Both total stigmatic pollen load and the proportion of legitimate pollen decreased with increasing spatial isolation. Legitimate (intermorph) pollen transfer was, however, asymmetric and decreased more rapidly with decreasing proximity to a compatible legitimate mating partner in the S‐morph than in the L‐morph. Total stigmatic pollen loads per flower increased with increasing floral display size, indicating that large plants are disproportionately more visited than smaller individuals. However, because legitimate pollen deposition decreased with increasing floral display size, these results also suggest that larger numbers of flowers increase the degree of geitonogamous pollination. In both the L‐ and S‐morph, seed set significantly decreased with increasing isolation from a legitimate mating partner, but in the L‐morph seed set was less dependent on the spatial distribution of the S‐morph. In addition, seed set significantly increased with floral display size in the L‐morph, but not in the S‐morph. These findings indicate that the spatial distribution of potential mates and variation in floral display size may cause morph‐specific differences in pollen deposition rates and female reproductive success.