Pic of the moment: 31 October 2008

Boo!

A monster crayfish for Hallowe'en!

Although I lived in Australia for a couple of years, one of my few regrets is that I never got to Tasmania, where this beast lives. Astacopsis gouldi is the biggest crayfish -- indeed, the biggest freshwater invertebrate -- in the world.

From old news story here.

The devil herself

Thread title is taken from a caption underneath a picture of Marmorkrebs in an excellent post over at the Amphidrome blog about the recent discovery of Marmorkrebs in Madagascar. In particular, it notes of the native Madagascar crayfish species, which belong to the genus Astacoides:

(H)abitat loss and overharvesting have hit (Astacoides) crosnieri and A. petiti hard enough to earn them endangered status on the IUCN Red List.

Many good references there, too.

The obstacles to asexuality

One of the few things about the origin of Marmorkrebs that appears indisputable is that it evolved from a sexually reproducing species. An new review paper in BioEssays examines some of the obstacles that an organism has to overcome to switch from sexual to asexual reproduction. As such, it surely lays our a lot of the conceptual groundwork for research on the origin of Marmorkrebs.

Engelstädter J. 2008. Constraints on the evolution of asexual reproduction. BioEssays 30(11-12): 1138-1150. http://dx.doi.org/10.1002/bies.20833

Vogt, 2008c

Vogt G. 2008. How to minimize formation and growth of tumours: Potential benefits of decapod crustaceans for cancer research. International Journal of Cancer 123: 2727–2734.
http://dx.doi.org/10.1002/ijc.23947

Abstract

Tumours have only rarely been observed in the decapod crustaceans, a large animal group of more than 10,000 species that includes the commercially important and well investigated shrimp, lobsters, crayfish and crabs. Analysis of the literature and information from cancer and diseases data bases revealed a total of 15 incidences, some of them being questionable. Even in the long-lived species, which can reach life spans of almost 100 years, neoplasias are virtually unknown. The data published so far suggest that the strikingly different frequencies of carcinogenesis between decapods and other well investigated animal groups like mammals, fish, insects and molluscs is based on differences of the metabolic pathways for carcinogens, the immune systems, and the regulation of stem cells. Therefore, representatives of the Decapoda may serve as useful models to study how organisms can successfully prevent or control spontaneously and environmentally induced cell proliferation. A particularly promising candidate for in-depth investigation of these topics is the marbled crayfish, a rather new clonal lineage that is presently being introduced as a laboratory model in development and epigenetics.

Keywords: neoplasia • Decapoda • Crustacea • stem cells • detoxification of carcinogens • age-related cancer • immune system • epigenetics • marbled crayfish

Artistic merits

An artist with the handle Marmorkrebs has a piece on the deviantART website.

From small acorns

I haven't been blogging a lot, because I'm teaching some very time consuming classes this semester (one in particular is wailing on me). So just a quick one for now...

I wanted to pass on a tip from Frederike Alwes (coauthor of this paper), who informed me that Marmorkrebs like oak leaves in their tanks, both as food and for making the water perhaps a bit more acidic. We're trying it out in our lab now.