Lyko, 2017

Lyko F. 2017. Ein Krebs für die Krebsforschung. Biologie in unserer Zeit 47(3): 172–177. http://dx.doi.org/10.1002/biuz.201710620

Abstract

Marmorkrebs (or marbled crayfish) is a triploid crayfish known since the mid-1990s, which reproduces parthenogenetically. It originated from the North American decapod species Procambarus fallax and was distributed as a popular aquarium pet. Subsequent anthropogenic releases have resulted in the establishment of several stable populations in the wild that constitute a serious invasive threat. Interestingly, marbled crayfish use a parthenogenetic mode of reproduction that results in the generation of clones with minimal genetic variation. In addition, the animals can be easily bred and manipulated in the laboratory. These features establish marbled crayfish as a novel and innovative model organism for tumor biology, particularly for the analysis of clonal evolution and epigenetic adaptation of tumor genomes.

Keywords: Marmorkrebs • tumor biology • clonal evolution • epigentics

(Note: The main text of the article is in German. Keywords are translated from German.)

Martin and colleagues, 2016

Martin A, Serano JM, Jarvis E, Bruce HS, Wang J, Ray S, Barker CA, O’Connell LC, Patel NH. 2016. CRISPR/Cas9 mutagenesis reveals versatile roles of Hox genes in crustacean limb specification and evolution. Current Biology 26(1): 14-26. https://doi.org/10.1016/j.cub.2015.11.021

Abstract

Crustaceans possess a diverse array of specialized limbs. Although shifts in Hox gene expression domains have been postulated to play a role in generating this limb diversity, little functional data have been provided to understand the precise roles of Hox genes during crustacean development. We used a combination of CRISPR/Cas9-targeted mutagenesis and RNAi knockdown to decipher the function of the six Hox genes expressed in the developing mouth and trunk of the amphipod Parhyale hawaiensis. These experimentally manipulated animals display specific and striking homeotic transformations. We found that abdominal-A (abd-A) and Abdominal-B (Abd-B) are required for proper posterior patterning, with knockout of Abd-B resulting in an animal with thoracic type legs along what would have been an abdomen, and abd-A disruption generating a simplified body plan characterized by a loss of specialization in both abdominal and thoracic appendages. In the thorax, Ubx is necessary for gill development and for repression of gnathal fate, and Antp dictates claw morphology. In the mouth, Scr and Antp confer the part-gnathal, part-thoracic hybrid identity of the maxilliped, and Scr and Dfd prevent antennal identity in posterior head segments. Our results allow us to define the role Hox genes play in specifying each appendage type in Parhyale, including the modular nature by which some appendages are patterned by Hox gene inputs. In addition, we define how changes in Hox gene expression have generated morphological differences between crustacean species. Finally, we also highlight the utility of CRISPR/Cas9-based somatic mutagenesis in emerging model organisms.

Keywords: None provided.

Note: Marmorkrebs appear in Figure 7D, described in the main text with the incomplete species name, “Procambarus fallax.” The Supplemental Experimental Procedures provide the full name, confirming that these are Marmorkrebs.