Experiments and observations of prothonotary warblers indicate a lack of adaptive responses to brood parasitism

It has been suggested that prothonotary warblers, Protonotaria citrea, respond adaptively to brood parasitism by brown-headed cowbirds, Molothrus ater, even though they lack historical habitat and range overlap with cowbirds. I studied behaviours functioning as potential defences against brood parasitism in the prothonotary warbler, a cavity-nesting host species. Opening sizes preferred by prothonotary warblers were not small enough to exclude cowbirds, and warblers were parasitized heavily in nests with larger openings. Male and female prothonotary warblers were always away from their nests before sunrise when cowbirds laid eggs in their nests. Prothonotary warblers infrequently (∼6% of 560 nests) deserted nests that were parasitized during the egg-laying period, but frequently (56% of 151 nests) deserted nests that were parasitized before a female warbler laid her first egg. Prothonotary warblers also deserted 60-70% of nests where a cowbird egg, warbler egg or die were experimentally added before egg laying. However, the experimental addition of one of these three objects during the egg-laying period did not elicit desertion. The desertion of parasitized nests was not affected by nest site availability as has been reported elsewhere in the literature. This lack of a response to brood parasitism by prothonotary warblers may be an example of evolutionary lag, because it is likely that they have only recently been exposed to widespread parasitism, and they accept parasitism at a high cost to their own reproductive success. Copyright 2003 Published by Elsevier Science Ltd on behalf of The Association for the Study of Animal Behaviour.      

Plant-mediated alteration of the peritrophic matrix and baculovirus infection in lepidopteran larvae

The peritrophic matrix (PM) lines the midgut of most insects, providing protection to the midgut epithelial cells while permitting passage of nutrients and water. Herein, we provide evidence that plant-mediated alteration of the PM contributes to the well-documented inhibition of fatal infection by Autographa californica multiple nucleopolyhedrovirus (AcMNPV) of Heliothis virescens F. larvae fed cotton foliage. We examined the impact of the PM on pathogenesis using a viral construct expressing a reporter gene (AcMNPV-hsp70/lacZ) orally inoculated into larvae with either intact PMs or PMs disrupted by Trichoplusia ni granulovirus occlusion bodies containing enhancin, known to degrade insect intestinal mucin. Larvae possessing disrupted PMs displayed infection foci (lacZ signaling) earlier than those with intact PMs. We then examined PMs from larvae fed artificial diet or plant foliage using electron microscopy; foliage-fed larvae had significantly thicker PMs than diet-fed larvae. Moreover, mean PM width was inversely related to both the proportion of larvae with lacZ signaling at 18 h post-inoculation and the final percentage mortality from virus. Thus, feeding on foliage altered PM structure, and these foliage-mediated changes reduced baculoviral efficacy. These data indicate that the PM is an important factor determining the success of an ingested pathogen in foliage-fed lepidopteran larvae.     

Comprehensive resequence analysis of a 136 kb region of human chromosome 8q24 associated with prostate and colon cancers

Recently, genome-wide association studies have identified loci across a segment of chromosome 8q24 (128,100,000–128,700,000) associated with the risk of breast, colon and prostate cancers. At least three regions of 8q24 have been independently associated with prostate cancer risk; the most centromeric of which appears to be population specific. Haplotypes in two contiguous but independent loci, marked by rs6983267 and rs1447295, have been identified in the Cancer Genetic Markers of Susceptibility project (), which genotyped more than 5,000 prostate cancer cases and 5,000 controls of European origin. The rs6983267 locus is also strongly associated with colorectal cancer. To ascertain a comprehensive catalog of common single-nucleotide polymorphisms (SNPs) across the two regions, we conducted a resequence analysis of 136 kb (chr8: 128,473,000–128,609,802) using the Roche/454 next-generation sequencing technology in 39 prostate cancer cases and 40 controls of European origin. We have characterized a comprehensive catalog of common (MAF > 1%) SNPs within this region, including 442 novel SNPs and have determined the pattern of linkage disequilibrium across the region. Our study has generated a detailed map of genetic variation across the region, which should be useful for choosing SNPs for fine mapping of association signals in 8q24 and investigations of the functional consequences of select common variants. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Comparing and Combining Landsat Satellite Imagery and Participatory Data to Assess Land-Use and Land-Cover Changes in a Coastal Village in Papua New Guinea

In regions lacking socio-economic data, pairing satellite imagery with participatory information is essential for accurate land-use/cover (LULC) change assessments. At the village scale in Papua New Guinea we compare swidden LULC classifications using remote sensing analyses alone and analyses that combine participatory information and remotely sensed data. These participatory remote sensing (PRS) methods include participatory land-use mapping, household surveys, and validation of image analysis in combination with remotely sensed data. The classifications of the swidden area made using only remote sensing analysis show swidden areas are, on average, two and a half times larger than land managers reported for 1999 and 2011. Classifications made using only remote sensing analysis are homogeneous and lack discrimination among swidden plots, fallow land, and non-swidden vegetation. The information derived from PRS methods allows us to amend the remote sensing analysis and as a result swidden areas are more similar to actual swidden area found when ground-truthing. We conclude that PRS methods are needed to understand swidden system LULC complexities.     

Prevalence of blood circulation misconceptions among prospective elementary teachers

Research shows that misconceptions about human blood circulation and gas exchange persist across grade levels. The purpose of this study was twofold: 1) to investigate the prevalence and persistence of blood circulation misconceptions among prospective elementary teachers and 2) to evaluate the effectiveness of learning activities for discovering what students know and can explain about blood circulation and lung function. The context was an undergraduate introduction to biology course taught by two professors across three semesters at a state university. Independent reviewers identified five categories of erroneous ideas about blood circulation. Many categories still presented problems to students at the end of the course: 70% of prospective elementary teachers did not understand the dual blood circulation pathway, 33% were confused about blood vessels, 55% had wrong ideas about gas exchange, 19% had trouble with gas transport and utilization, and 20% did not understand lung function. Results show that an interview about a drawing as a final exam was significantly better at revealing different errors and a higher frequency of erroneous ideas compared with an essay exam. There is an urgent need for instructional tools to help undergraduate students realize the discrepancies between their own ideas about blood circulation and those of the scientific community.     

Methods for etiologic and early marker investigations in the PLCO trial

With the rapid development of biomarkers and new technologies, large-scale biologically-based cohort studies present expanding opportunities for population-based research on disease etiology and early detection markers. The prostate, lung, colorectal and ovarian cancer (PLCO) screening trial is a large randomized trial designed to determine if screening for these cancers leads to mortality reduction for these diseases. Within the Trial, the PLCO etiology and early marker study (EEMS) identifies risk factors for cancer and other diseases and evaluates biologic markers for the early detection of disease. EEMS includes 155,000 volunteers who provide basic risk factor information. Serial blood samples are collected at each of six screening rounds (including one collection for cryopreserved whole blood) from screening arm participants (77,000 subjects) and buccal cells are collected from those in the control arm of the trial. Etiologic studies consider environmental (e.g., diet), biochemical, and genetic factors. Early detection studies focus on blood-based biologic markers of early disease. Clinical epidemiology is also an important component of the PLCO trial.     

Use of antibiotic resistance analysis for representativeness testing of multiwatershed libraries

The use of antibiotic resistance analysis (ARA) for microbial source tracking requires the generation of a library of isolates collected from known sources in the watershed. The size and composition of the library are critical in determining if it represents the diversity of patterns found in the watershed. This study was performed to determine the size that an ARA library needs to be to be representative of the watersheds for which it will be used and to determine if libraries from different watersheds can be merged to create multiwatershed libraries. Fecal samples from known human, domesticated, and wild animal sources were collected from six Virginia watersheds. From these samples, enterococci were isolated and tested by ARA. Based on cross-validation discriminant analysis, only the largest of the libraries (2,931 isolates) were found to be able to classify nonlibrary isolates as well as library isolates (i.e., were representative). Small libraries tended to have higher average rates of correct classification, but were much less able to correctly classify nonlibrary isolates. A merged multiwatershed library (6,587 isolates) was created and was found to be large enough to be representative of the isolates from the contributing watersheds. When isolates that were collected from the contributing watersheds approximately 1 year later were analyzed with the multiwatershed library, they were classified as well as the isolates in the library, suggesting that the resistance patterns are temporally stable for at least 1 year. The ability to obtain a representative, temporally stable library demonstrates that ARA can be used to identify sources of fecal pollution in natural waters.     

E-selectin and ICAM-1 are incorporated into detergent-insoluble membrane domains following clustering in endothelial cells

The homeobox gene Cdx1 is a regulator of intestinal epithelial cell proliferation and differentiation. Using a transfection approach, we showed here that the oncogenic activation of the beta-catenin pathway stimulates the endogenous expression of the Cdx1 mRNA as well as the activity of the Cdx1 promoter in cancer cells of the human colon. Reciprocally, the paralogue homeobox gene Cdx2 exerts an inhibitory effect on the basal and on the beta-catenin-stimulated activity of the Cdx1 promoter. The inhibitory effect of CDX2 requires the intact homeodomain. It is not dependent on canonical CDX binding sites in the Cdx1 promoter nor on the cis-elements specifically targeted by the beta-catenin/Tcf complex. We conclude that the oncogenically activated beta-catenin and CDX2 have opposite and independent effects on the Cdx1 homeobox gene.     

Refinement of the 6p21.3 quantitative trait locus influencing dyslexia: linkage and association analyses

Reading disability (RD), or dyslexia, is the most common learning disability with a prevalence rate of ~5%–10% in school-age children. RD is highly heritable with evidence of a neurobiological origin. Linkage studies have identified several quantitative trait loci (QTLs) for RD. The QTL on chromosome 6p21.3 has been independently replicated by several groups and spans a 16.4-Mb (13.8 cM) interval from D6S109 to D6S291. In this study, we performed sib-pair linkage analyses with Haseman–Elston and DeFries–Fulker methods to define more accurately the QTL interval. Linkage was assessed by using five quantitative phenotypes, including a composite measure of reading performance and four component phenotypes. When probands were selected for severe scores, single- and multi-point analyses showed significant linkage with all five phenotypes, converging over an interval of ~3.24 Mb spanning D6S1597 to D6S1571. Maximal linkage converged at marker D6S1554 across phenotypes. Out of 12 genes in the linkage interval, ten clustered within ~680 kb and were selected for association analysis based on central nervous system expression and putative function. Marker-trait associations were assessed by using QTDT (a general test of association for quantitative traits) and the family-based association test (FBAT), and haplotype analysis was performed by using FBAT and the GeneHunter Transmission/Disequilibrium Test TDT. Marker associations were detected in five of the ten genes, results that were corroborated by our haplotype TDT analysis. The results of the association study have thereby allowed us to significantly reduce the number of possible candidate genes and to prioritize genes for further mutation screening.