Restoring natural capital

As scientists and practitioners committed to ecological restoration, we found the analogy you made in your April issue1 between restoring natural capital (RNC)2 and new forms of cancer treatment3 to be an extremely powerful one. To a certain degree, RNC and ecological restoration in general, are indeed related to ecosystem degradation in the way that tumor ecology-based treatments are related to traditional cancer therapies, e.g., combined radiation and chemotherapy.

What is clearly common to both approaches is that ecological restoration and cancer therapy are optimistic interventions with multiple payoffs to individuals and societies.4 Like cancer therapy, however, RNC is expensive. It is also time- and energy-consuming, and requires sustained commitment of the highest order. It is risky; there is no sure outcome in any given case, as your sidebar on South Africa's Working for Water program demonstrated.

Both RNC and cancer therapy are...


1. R. Gallagher, "Concepts that click," The Scientist, 20(4):13, April 2006.2. P. Woodworth, "What price ecological restoration?" The Scientist, 20(4):39-45, April 2006.3. M. Bissell, "The ecology of tumors," The Scientist, 20(4):31-8, April 2006.4. A.F. Clewell, J. Aronson, "Motivations for the restoration of ecosystems," Conserv Biol, 20:420-8, 2006

Rafts and rubbish

Re: Lipid rafts.1 It is obvious to anyone who understands the association of sphingomyelin with cholesterol that the misnamed rafts are simply domains with extremely high curvature. They are not rafts, but actually spherical structures just under the membrane, serving as depots for the trafficking of membrane materials. That is why the G-proteins and others are associated with them. These depots are integral to maintaining the membrane area by having in-out function. But any attempts at isolation cause them to fuse into the membrane or fall off, hence their recognition as "rafts." The whole of this area needs a completely revolutionary rethink to get out of the misguided dogmas.

Gerry A. Smith
Department of Biochemistry
University of Cambridge

1. J.U. Adams, "Lipid rafts' failure to launch," The Scientist, 20(6):67, June 2006.

Upgrading to TIRF

Re: Upgrade your lab to TIRF.1 Using a TILL Photonics system is one way to convert a Zeiss Axiovert 200 into a total internal reflection fluorescence (TIRF) microscope. However, we feel that the Zeiss TIRF slider - available starting at $15,000, compared to $30,000 to $60,000 for the Photonics upgrade and less than the "upwards of $100,000" that you report for turnkey systems - offers certain advantages.

First, the Zeiss slider inserts into the field stop plane and guides the laser into the beam path, unlike the TILL TIRF condenser, which does not offer field and aperture stop planes. If you use the TILL condenser and later want to consider an ApoTome or any other stop slider, you will have to reinstall the original beam path. The TILL condenser also renders the mercury arc lamp and high-speed shutter obsolete; instead you need to add a fiber-guided light source and a shutter for epifluorescence. Neither of these is true for the Zeiss slider.

The Zeiss slider also allows illumination and manipulation techniques to be performed simultaneously or sequentially; features TIRF controls located within reach of your arm at the side of the stand, not at the back; and does not require readjustments for various wavelengths. Finally, the TIRF slider can easily be removed, without losing adjustments, and its compact design means that the TIRF slider does not add to the footprint of the system.

Laser safety is another important factor, and Zeiss offers an integrated laser safety system for TIRF, including incubation. Beam angle and divergence adjustment is performed under laser safety conditions. Laser safety is available for upgrade on most Axiovert 200 versions and in combination with existing customer lasers.

Bruene Venus
Carl Zeiss MicroImaging

1. J.M. Perkel, "Upgrade your lab to TIRF," The Scientist, 20(6):72-3, June 2006.

Nikon provides two low cost, high performance TIRF illuminators, which offer significant support and integration advantages over the system featured in your article:1 the White Light TIRF Illuminator and the TIRF-2 Illuminator for laser TIRF.

The White Light TIRF works by producing a thin sheet of light out of the objective lens that is then steered with a knob on the illuminator to undergo TIRF at the specimen-coverslip interface. Because this system utilizes an Hg lamp for illumination, it costs thousands of dollars less than a comparable laser based system, and is intrinsically multi-spectral and immune to the interference fringes associated with coherent laser illumination. The system produces images and data similar to laser-based TIRF systems and can be added to a Nikon TE2000 inverted research microscope for less than $10,000.

For users requiring laser-based TIRF, Nikon offers the TIRF-2 illuminator featuring an extremely high signal-to-noise ratio, making it ideal for a variety of applications including the observation of single molecules. This system, including the illuminator and a shutter controlled, laser safe two laser unit, can be added to a Nikon inverted microscope for about $40,000.

Nikon's new 60X and 100X TIRF objectives have numerical apertures of 1.49, close to the theoretical limit of 1.51, affording extremely bright, high contrast images and the thinnest possible evanescent field for TIRF. Additionally, Nikon is the only manufacturer providing such objectives with temperature-calibrated correction collars, which allow for the easy correction of temperature-induced spherical aberrations. This is critically important for TIRF microscopy of live cells, typically performed at physiological rather than ambient temperature. Each of these objects can be purchased for less than $10,000.

Stan Schwartz
Vice President, Nikon Instruments
Melville, NY

Cockroaches everywhere

Re: Cockroaches: Nature's petri dish.1 May this otherwise lowly group of critters be elevated to a metagenomic status. There will be much hissing after this work is done. Housekeeping genes aside, cockroaches offer the prospect of microbial diversity analysis, versatile biocatalyst discovery (e.g., from wood-dwelling cockroaches), an understanding of hydrogenosome in hydrogen production (as reported for the anaerobic ciliate Nyctotherus ovalis that inhabits the hindgut of cockroaches2), tolerance to dessication, elevated radiation resistance compared to human, and, they are armed with an arsenal of antimicrobial resistance genes. Cockroaches can apparently go without food for a month (besides remaining alive headless for up to a week), hold their breath for some 45 minutes, and have the ability to slow down their heart rate. It is gratifying to see that some EST analyses have already began.3,4

Peter C.K. Lau
Biotechnology Research Institute
Montreal, Canada


1. S. Pincock, "Cockroaches: nature's petri dish," The Scientist, 20(6):17-8, June 2006.2. B. Boxma et al., "An anaerobic mitochondrion that produces hydrogen," Nature, 434:74-9, 2005.3. H.S. Chung et al., "Expressed sequence tags analysis of Blattella germanica," Korean J Parasitol, 43:149-56, 2005.4. F.G. Noriega et al., "Comparative genomics of insect juvenile hormone biosynthesis," Insect Biochem Mol Biol, 36:366-74, April 2006.

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