Prey capture in protists utilizing microtubule filled processes and surface motility.

Surface motility, which can be visualized by the movement of live prey organisms, polystyrene microspheres or other inert particles, has been shown to occur in a wide variety of microtubule-filled extensions of the protistan cell surface, although the associated functions remain enigmatic. This article integrates an extensive but poorly known body of literature showing that surface motility, associated with microtubule-filled cell extensions such as flagella, axopodia, actinopodia, reticulopodia, and haptonema, plays a crucial role in protistan prey capture. Surface motility has been most extensively studied in Chlamydomonas where it is responsible for flagella-dependent whole cell gliding motility.

The flagellar membrane glycoprotein FMG-1B is necessary for expression of force at the flagellar surface.

In addition to bend propagation for swimming, cells use their flagella to glide along a surface. When polystyrene microspheres are added to cells, they attach to and move along the flagellar surface, thus serving as a proxy for gliding that can be used to assay for the flagellar components required for gliding motility. Gliding and microsphere movement are dependent on intraflagellar transport (IFT).

Laser trap measurements of flagellar membrane motility.

In addition to swimming motility, which is driven by propagation of bends along the flagellum, the unicellular green alga Chlamydomonas exhibits an unusual and alternative form of whole cell locomotion, called gliding motility. In gliding motility, a large flagellar membrane glycoprotein mediates flagellar membrane adhesion to solid substrates. This in turn activates a transmembrane signaling system that initiates the movement of a cross-linked cluster of glycoproteins within the plane of the flagellar membrane by activating and/or recruiting isoforms of the motor proteins kinesin and dynein.

The future of ciliary and flagellar membrane research.

There has been a dramatic shift of attention from the ciliary axoneme to the ciliary membrane, much of this driven by the appreciation that cilia play a widespread role in sensory reception and cellular signaling. This Perspective focuses attention on some of the poorly understood aspects of ciliary membranes, including the establishment of ciliary and periciliary membrane domains, the trafficking of membrane components into and out of these membrane domains, the nonuniform distribution of ciliary membrane components, the regulation of membrane morphogenesis, functional collaboration between the axoneme and the membrane, and the evolving field of therapeutics targeted at the ciliary membrane.

Active learning: A small group histology laboratory exercise in a whole class setting utilizing virtual slides and peer education.

Histology laboratory instruction is moving away from the sole use of the traditional combination of light microscopes and glass slides in favor of virtual microscopy and virtual slides. At the same time, medical curricula are changing so as to reduce scheduled time for basic science instruction as well as focusing on student-centered learning approaches such as small group active learning and peer-instruction. It is important that medical schools resist the temptation to respond to this conjunction of events by turning histology into a self-study activity.

Sensory reception is an attribute of both primary cilia and motile cilia.

A recent cluster of papers has shown that motile cilia in the respiratory and reproductive tracts of humans and other mammals can exhibit sensory functions, a function previously attributed primarily to non-motile primary cilia. This leads to a new paradigm that all cilia and flagella (both motile and primary) can mediate sensory functions. However, examination of the literature shows that evidence of sensory functions of motile cilia and flagella is widespread in studies of invertebrates, and extends as back as far as 1899.

A change to pass/fail grading in the first two years at one medical school results in improved psychological well-being.

Purpose: To measure the impact of a change in grading system in the first two years of medical school, from graded (A, B, C, D, F) to pass/fail, on medical students' academic performance, attendance, residency match, satisfaction, and psychological well-being.

Method: For both the graded and pass/fail classes, objective data were collected on academic performance in the first- and second-year courses, the clerkships, United States Medical Licensing Examination (USMLE) Steps 1 and 2 Clinical Knowledge (CK), and residency placement. Self-report data were collected using a Web survey (which included the Dupuy General Well-Being Schedule) administered each of the first four semesters of medical school.

The reciprocal coordination and mechanics of molecular motors in living cells.

Molecular motors in living cells are involved in whole-cell locomotion, contractility, developmental shape changes, and organelle movement and positioning. Whether motors of different directionality are functionally coordinated in cells or operate in a semirandom "tug of war" is unclear. We show here that anterograde and retrograde microtubule-based motors in the flagella of Chlamydomonas are regulated such that only motors of a common directionality are engaged at any single time.

Targeting proteins to the ciliary membrane.

Most vertebrate cell types display solitary nonmotile cilia on their surface that serve as cellular antennae to sense the extracellular environment. These organelles play key roles in the development of mammals by coordinating the actions of a single cell with events occurring around them. Severe defects in cilia lead to midgestational lethality in mice while more subtle defects lead to pathology in most organs of the body.

From central to rudimentary to primary: the history of an underappreciated organelle whose time has come. The primary cilium.

For the first time, the history of the central flagellum/primary cilium has been explored systematically and in depth. It is a long and informative story about the course of scientific discovery, memory loss and rediscovery. The progress of our story is saltatory, pushed onward by innovations in technology and retarded by socio-scientific issues of linguistic and temporal chauvinism.

Trends in histology laboratory teaching in United States medical schools.

Owing to competition for faculty time among the three major missions of today's academic medical centers, as well as the rapid development of computer-based instructional technologies, laboratory instruction in medical schools in the United States has been undergoing dramatic change. In order to determine recent trends in histology laboratory instruction at U.S.

The ultrastructure of Pyrsonympha and its associated microorganisms.

The termite gut flagellates are of interest because of their unusual motile organelles, their ability to digest cellulose, and their symbiotic relationship with prokaryotes inhabiting the insect gut. This report provides a detailed ultrastructural description of Pyrsonympha from the hind-gut of Reticulitermes flavipes. The motile axostyle is composed of 2,000-4,000 microtubules connected by cross-bridges.