Carmichael’s Concise Review Coming Events
2011 Neuroscience 2011 November 12–16, 2011 Washington, DC
www.sfn.org
MRS Fall Meeting 2011 November 28–December 2, 2011 Boston, MA
www.mrs.org
American Society for Cell Biology December 3–7, 2011 Denver Convention Center, CO
www.ascb.org/meetings
2012
ASU Winter School—HREM January 4–7, 2012 Tempe, AZ
http://le-csss.asu.edu/winterschool
SPIE—Photonics West January 21–26, 2012 San Francisco, CA
http://spie.org
High-Throughput Structural Biology January 22–27, 2012 Keystone Resort, CO
www.keystonesypmposia.org
10th Asia-Pacifi c Microscopy Conference February 5–9, 2012 Perth, Australia
www.apmc-10.org
PITTCON March 11–15, 2012 Orlando, FL
www.pittcon.org
Microscopy & Microanalysis 2012 July 29–August 2, 2012 Phoenix, AZ
2013
Microscopy & Microanalysis 2013 August 4–8, 2013 Indianapolis, IN
2014
Microscopy & Microanalysis 2014 August 3–7, 2014 Hartford, CT
2015
Microscopy & Microanalysis 2015 August 2–6, 2015 Portland, OR
More Meetings and Courses Check the complete calendar near the back of this magazine and in the MSA journal Microscopy and Microanalysis.
8
Elaborate Helmets are Actually Appendages!
Stephen W. Carmichael Mayo Clinic, Rochester, MN 55905
carmichael.stephen@
mayo.edu
Of the winged insects, adults have one or two pairs of wings. During the past
250 million years of insect evolution, there have been no exceptions to this. In a fascinating study, Benjamin Prud’homme, Caroline Minervino, Mélanie Hocine, Jessica Cande, Aïcha Aouane, Héloïse Dufour, Victoria Kassner, and Nicolas Gompel may have found something resembling an exception [1]. Treehoppers (specifi cally the family Membracidae) are characterized by
a “helmet,” which has been thought to be part of the animal’s camoufl age (Figure 1). T e helmet expands dorsally over most of the body length and has diversifi ed to extremes within the family resembling natural forms ranging from thorns or seeds to animal droppings or aggressive ants. Without their helmets, treehoppers are very similar to cicadas. T e helmet has been considered to be an expansion of the pronotum, an outgrowth of the cuticle of the fi rst thoracic segment. T e anatomy and evolutionary origin of the helmet remain controversial.
Using diff erent microscopy methods, specifi cally scanning electron microscopy and light microscopy (including confocal), Prud’homme et al. showed that the helmet is attached to the fi rst thoracic segment by a complex articulation. A jointed articulation distinguishes an appendage from a simple outgrowth. T ey found that the attachment points consisted of thin, non-sclerotized (that is, fl exible) cuticle fl anked by thicker, sclerotized cuticle. T is confi guration of fl exible and hard cuticle defi nes cuticular joints that connect appendages to the body. In insects with two pairs of wings, this is the type of joint that connects the wings to the second and third thoracic segments. Because the helmet is attached to the fi rst thoracic segment by jointed articulations, it follows that it is a dorsal appendage of that segment. T is was completely unexpected in extant insects! Unlike most appendages, which
are obviously paired, the helmet appears to be a single structure in tree- hoppers, both in adult and nymphal stages. However, Prud’homme et al. found that the helmet originates from two bilateral primordia that later fuse along the dorsal midline. T e helmet is therefore a dorsal appendage of the fi rst thoracic segment with a bilateral origin. Additional anatomical obser- vations made with microscopes suggest that the helmet is a fused pair of wing serial homologues.
Figure 1: Three examples of the wide variety of treehopper helmets.
doi:10.1017/S1551929511001210
www.microscopy-today.com • 2011 November
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