Colby–Sawyer College

About: Colby–Sawyer College is a education organization based out in New London, New Hampshire, United States. It is known for research contribution in the topics: Population & Cadherin. The organization has 72 authors who have published 100 publications receiving 3724 citations. The organization is also known as: Colby-Sawyer & Colby Junior College.

Force measurements in E-cadherin–mediated cell doublets reveal rapid adhesion strengthened by actin cytoskeleton remodeling through Rac and Cdc42

Abstract: We have used a modified, dual pipette assay to quantify the strength of cadherin-dependent cell-cell adhesion. The force required to separate E-cadherin-expressing paired cells in suspension was measured as an index of intercellular adhesion. Separation force depended on the homophilic interaction of functional cadherins at the cell surface, increasing with the duration of contact and with cadherin levels. Severing the link between cadherin and the actin cytoskeleton or disrupting actin polymerization did not affect initiation of cadherin-mediated adhesion, but prevented it from developing and becoming stronger over time. Rac and Cdc42, the Rho-like small GTPases, were activated when E-cadherin-expressing cells formed aggregates in suspension. Overproduction of the dominant negative form of Rac or Cdc42 permitted initial E-cadherin-based adhesion but affected its later development; the dominant active forms prevented cell adhesion outright. Our findings highlight the crucial roles played by Rac, Cdc42, and actin cytoskeleton dynamics in the development and regulation of strong cell adhesion, defined in terms of mechanical forces.

The Capsella rubella genome and the genomic consequences of rapid mating system evolution

Abstract: The shift from outcrossing to selfing is common in flowering plants(1,2), but the genomic consequences and the speed at which they emerge remain poorly understood. An excellent model for understanding the evolution of self fertilization is provided by Capsella rubella, which became self compatible <200,000 years ago. We report a C. rubella reference genome sequence and compare RNA expression and polymorphism patterns between C. rubella and its outcrossing progenitor Capsella grandiflora. We found a clear shift in the expression of genes associated with flowering phenotypes, similar to that seen in Arabidopsis, in which self fertilization evolved about 1 million years ago. Comparisons of the two Capsella species showed evidence of rapid genome-wide relaxation of purifying selection in C. rubella without a concomitant change in transposable element abundance. Overall we document that the transition to selfing may be typified by parallel shifts in gene expression, along with a measurable reduction of purifying selection.

An atlas of over 90,000 conserved noncoding sequences provides insight into crucifer regulatory regions

Abstract: Despite the central importance of noncoding DNA to gene regulation and evolution, understanding of the extent of selection on plant noncoding DNA remains limited compared to that of other organisms. Here we report sequencing of genomes from three Brassicaceae species (Leavenworthia alabamica, Sisymbrium irio and Aethionema arabicum) and their joint analysis with six previously sequenced crucifer genomes. Conservation across orthologous bases suggests that at least 17% of the Arabidopsis thaliana genome is under selection, with nearly one-quarter of the sequence under selection lying outside of coding regions. Much of this sequence can be localized to approximately 90,000 conserved noncoding sequences (CNSs) that show evidence of transcriptional and post-transcriptional regulation. Population genomics analyses of two crucifer species, A. thaliana and Capsella grandiflora, confirm that most of the identified CNSs are evolving under medium to strong purifying selection. Overall, these CNSs highlight both similarities and several key differences between the regulatory DNA of plants and other species.

Identifying the educational implications of chronic illness in school children.

Abstract: Children and adolescents with chronic illness such as asthma, diabetes, and cancer are at the intersection of the health and education systems. At school, their health needs may be attended to by a school nurse, while their educational needs may be overlooked. This article helps school personnel become more proactive in identifying the educational implications of chronic illness in school children. The confusing array of terms used to refer to this population by health professionals and educators are clarified, and estimates of the size of the population are provided. The potential impact of some common disease processes, treatments, and medications are reviewed, as are the risks of chronic absenteeism. Suggestions for how school and health professionals can identify and work with this group of children are offered.