Many marine fish and invertebrates show a dual life history where settled adults produce dispersing larvae. The planktonic nature of the early larval stages suggests a passive dispersal model where ocean currents would quickly cause panmixis over large spatial scales and prevent isolation of populations, a prerequisite for speciation. However, high biodiversity and species abundance in coral reefs contradict this panmixis hypothesis. Although ocean currents are a major force in larval dispersal, recent studies show far greater retention than predicted by advection models. We investigated the role of animal behavior in retention and homing of coral reef fish larvae resulting in two important discoveries: (i) Settling larvae are capable of olfactory discrimination and prefer the odor of their home reef, thereby demonstrating to us that nearby reefs smell different. (ii) Whereas one species showed panmixis as predicted from our advection model, another species showed significant genetic population substructure suggestive of strong homing. Thus, the smell of reefs could allow larvae to choose currents that return them to reefs in general and natal reefs in particular. As a consequence, reef populations can develop genetic differences that might lead to reproductive isolation.coral reef ͉ olfaction ͉ population genetics

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Instructor Talk—noncontent language used by instructors in classrooms—is a recently defined and promising variable for better understanding classroom dynamics. Having previously characterized the Instructor Talk framework within the context of a single course, we present here our results surrounding the applicability of the Instructor Talk framework to noncontent language used by instructors in novel course contexts. We analyzed Instructor Talk in eight additional biology courses in their entirety and in 61 biology courses using an emergent sampling strategy. We observed widespread use of Instructor Talk with variation in the amount and category type used. The vast majority of Instructor Talk could be characterized using the originally published Instructor Talk framework, suggesting the robustness of this framework. Additionally, a new form of Instructor Talk—Negatively Phrased Instructor Talk, language that may discourage students or distract from the learning process—was detected in these novel course contexts. Finally, the emergent sampling strategy described here may allow investigation of Instructor Talk in even larger numbers of courses across institutions and disciplines. Given its widespread use, potential influence on students in learning environments, and ability to be sampled, Instructor Talk may be a key variable to consider in future research on teaching and learning in higher education.

Killing by Entamoeba histolytica requires parasite adherence to host galactose-and N-acetyl-D-galactosamine (Gal/GalNAc)-containing cell surface receptors. A 260-kDa heterodimeric E. histolytica Gal/GalNAc lectin composed of heavy (Hgl) and light (Lgl) subunits has been previously described. Here we present the cloning and characterization of Igl, a 150-kDa intermediate subunit of the Gal/GalNAc lectin. Igl, Hgl, and Lgl colocalized on the surface membrane of trophozoites. Two unlinked copies of genes encoding Igl shared 81% amino acid sequence identity (GenBank accession no. AF337950 and AF337951). They encoded cysteine-rich proteins with amino-and carboxy-terminal hydrophobic signal sequences characteristic of glycosylphosphatidylinositol (GPI)-anchored membrane proteins. The igl genes lacked carbohydrate recognition domains but were members of a large family of amebic genes containing CXXC and CXC motifs. These data indicate that Igl is part of the parasite's multimolecular Gal/GalNAc adhesin required for host interaction.Carbohydrate-protein interactions initiate the contact-dependent cytotoxicity for which Entamoeba histolytica was named. Parasite recognition of host galactose (Gal) and Nacetyl-D-galactosamine (GalNAc) residues initiates trophozoite adherence to human colonic mucin, colonic epithelium, neutrophils and erythrocytes, certain bacteria, and a variety of cultured cell lines (3-7, 16, 19-22, 27, 36-38). Contact-dependent killing of target cells is Ͼ90% inhibited by Gal and GalNAc (34,37,41). Additionally, Chinese hamster ovary (CHO) cell glycosylation-deficient mutants lacking terminal Gal/GalNAc residues on N-and O-linked sugars are nearly totally resistant to amebic adherence and cytolytic activity (23,24,39).The E. histolytica 260-kDa Gal/GalNAc lectin is a heterodimer of transmembrane heavy (170 kDa) (Hgl) and GPIanchored light (35 or 31 kDa) (Lgl) glycoproteins linked by disulfide bonds. It was originally identified by galactose affinity chromatography and with adherence-inhibitory monoclonal antibodies (MAbs) (30,43). Both Hgl and Lgl are encoded by gene families (28,35). Antibodies that block or augment parasite Gal/GalNAc binding activity map to the cysteine-rich region (amino acids 356 to 1143) of Hgl (25), and this region (when expressed in Escherichia coli) contains a functional carbohydrate recognition domain (14, 33). The cytoplasmic tail of Hgl has homology to the cytoplasmic domain of ␤2 and ␤7 integrins, including regions implicated in binding of the intracellular signaling molecules Shc and Grb2. Overexpression of the cytoplasmic tail results in a dominant negative effect on endogenous lectin activity, with decreased adherence, cytotoxicity, and in vivo virulence (44).The 150-kDa lectin intermediate subunit (Igl) was originally identified as a trophozoite surface antigen recognized by MAbs which block trophozoite adherence to mammalian cells in vitro (9)(10)(11)42). The EH3015 MAb specific for Igl significantly inhibits adherence of amebae to erythrocytes and CHO cells, erythrop...

Active-learning pedagogies have been repeatedly demonstrated to produce superior learning gains with large effect sizes compared with lecture-based pedagogies. Shifting large numbers of college science, technology, engineering, and mathematics (STEM) faculty to include any active learning in their teaching may retain and more effectively educate far more students than having a few faculty completely transform their teaching, but the extent to which STEM faculty are changing their teaching methods is unclear. Here, we describe the development and application of the machine-learning-derived algorithm Decibel Analysis for Research in Teaching (DART), which can analyze thousands of hours of STEM course audio recordings quickly, with minimal costs, and without need for human observers. DART analyzes the volume and variance of classroom recordings to predict the quantity of time spent on single voice (e.g., lecture), multiple voice (e.g., pair discussion), and no voice (e.g., clicker question thinking) activities. Applying DART to 1,486 recordings of class sessions from 67 courses, a total of 1,720 h of audio, revealed varied patterns of lecture (single voice) and nonlecture activity (multiple and no voice) use. We also found that there was significantly more use of multiple and no voice strategies in courses for STEM majors compared with courses for non-STEM majors, indicating that DART can be used to compare teaching strategies in different types of courses. Therefore, DART has the potential to systematically inventory the presence of active learning with ∼90% accuracy across thousands of courses in diverse settings with minimal effort.active learning | evidence-based teaching | science education | lecture | assessment C urrent college STEM (science, technology, engineering, and mathematics) teaching in the United States continues to be lecture-based and is relatively ineffective in promoting learning (1, 2). Undergraduate instructors continue to struggle to engage, effectively teach, and retain postsecondary students, both generally and particularly among women and students of color (3, 4). Federal analyses suggest that a 10% increase in retention of undergraduate STEM students could address anticipated STEM workforce shortfalls (5). Replacing the standard lecture format with more active teaching strategies has been shown to increase