23 September 2016

Then we take Berlin

A new article in Verbundjournal reports that Marmorkrebs are establishing themselves in lakes around the German capital of Berlin.

It’s a passing reference in an article by grad student Stefan Linzmaier, who is studying Marmorkrebs as an example of how an invasive species impacts the ecology of a system. I will not claim that I am entirely clear of all the details of Stefan’s ongoing research, since I am reading the article through the help of Google Translate, which can have... interesting interpretations of text.

The map of Marmorkrebs introductions has been updated accordingly. Hat tip to Gerhard Scholtz.

References

Linzmaier S. 2016. Vom Aquarium in den See. Verbundjournal 106: 14-15. http://www.fv-berlin.de/oeffentlichkeitsarbeit/verbundjournal-1/pdfs/verbund106.pdf

22 September 2016

Yazicioglu and colleagues, 2016

Yazicioglu B, Reynolds J, Kozák P. 2016. Different aspects of reproduction strategies in crayfish: a review. Knowledge and Management of Aquatic Ecosystems 417: 33. http://dx.doi.org/10.1051/kmae/2016020

Abstract

Study of the reproductive strategy of crayfish species is of great importance in the current astacological world. Crayfish are among the largest freshwater invertebrates, and as keystone species, they are able to regulate the structure of the benthic fauna in the freshwaters, demonstrating different ecological strategies and life spans ranging up to 20+ years. In order to bring together the various pieces of information related to this issue, this overview of published scientific reports was conducted. The majority of crayfish species studied show sexual dimorphism, with approximately equal numbers of males and females. However, over some decades numerous observations have been made for a few species that may have different modes of reproduction, such as hermaphroditism or intersex (e.g. Cherax quadricarinatus, Samastacus spinifrons, Parastacus virilastacus and Pacifastacus leniusculus) and parthenogenesis (only Procambarus fallax f. virginalis). A recent study showed a new case of parthenogenesis as apomictic parthenogenesis (only Orconectes limosus). In addition, there are many investigations into the reproduction biology of crayfish, including using eyestalk ablation or androgenic gland ablation under various lab conditions and hybridization under natural conditions (e.g. Astacus astacus X Astacus leptodactylus, Orconectes rusticus X Orconectes propinquus). There are also some chemical factors which could possibly affect the reproduction system of crayfish in the wild.

Keywords: Crustacea • parthenogenesis • intersex • hybridization


16 September 2016

The two sides of marbled crayfish

The International Association for Astacology meeting was recently held in Spain, and a nice press release about the two major lines of research on Marmorkrebs: as an unwanted invasive, and as a wanted model organism. I draw similar comparisons in my own chapter.

Between Google Translate and a little guesswork, I think the press release reads something like this:

  • This North American species is reshaping ecosystems by killing fish or molluscs on the one hand, and on the other hand, is used for studies related to cancer thanks to their particular genetics.
  • Researchers Pavel Kozák and Frank J. Lyko presented studies about this crustacean at the 21st International Symposium of Astacology.

The marble crayfish (Procamborus (sic) fallax) is a curious exotic species, as has been disclosed during the 21st International Symposium of Astacology, which takes place at the Royal Botanical CSIC Garden. Like the strange case of Dr. Jekyll and Mr. Hyde, it shows two sides: a positive, because thanks to their particular genetics, it is used for cancer-related studies; and the other less pleasant, because it is an invasive species that is ravaging different ecosystems.

Researchers Pavel Kozák from the Faculty of Fisheries and Protection of Waters of the University of South Bohemia in the Czech Republic, and Frank J. Lyko, from the Cancer Research Center of Heidelberg in Germany, are working on two projects related to marbled crayfish. They presented their studies on this species from the point of view of ecology and reproduction (Kozák) and genetics (Lyko).

According to the Czech researcher, his project initially focused on the impact of invasive species on native species of crayfish, but as the project continued, this deepened to include the interaction between this invasive species and their impact on other invasive species, such as amphibians or fish.

The researcher Kozák focuses on two significant events. “First, marbled crayfish are destroying fish, molluscs, and macroinvertebrates, and ultimately, it is reshaping the entire ecosystem. Second, this invasive species is more powerful than other larger species, thus refuting the claim that the larger species tend to be more aggressive.”

Meanwhile, the German researcher Frank J. Lyko notes that the genetics of marbled crayfish reproduction, i.e., the females create clones of themselves, “is a model species to implement our work on cancer, since there is only one genome to study, hence its importance for medical science.”

Devastating effects

However, Lyko coincides with his Czech colleague Kozák in the “devastating effects” of marbled crayfish, such as in Madagascar where they have destroyed almost all the habitat where they have been, before making the leap to other countries. The first crayfish in Europe were found in Germany in 1995, and by 2010, it was established in nature, especially Central Europe. In the short term, also has changed the habitat of this area.

The two researchers also agree that, given that its eradication is impossible, citizens of the areas where this species is found be educated to know how easily it reproduces and the consequences of their invasion. They also requested legislation regulating the introduction of new species and greater control of ornamental trade, both in physical stores and the sale online, because it is very easy to get this species for aquariums, and their reproduction is immediate and unlimited.

Finally, for Czech researcher Pavel Kozák, this highlighted the work of the Royal Botanic Garden-CSIC of Madrid, which conducts research related to crayfish plague and supports students doing projects on astacology.

When I went to the International Association of Astacology meeting in Missouri in 2010, I think I was one of the first to talk about Marmorkrebs at that venue. At least, several people told me it was news to them. It is nice to see more research at this preeminent crayfish meeting on Marmorkrebs, and making its way into the public.

External links

Cangrejo mármol, una curiosa especie invasora con dos caras (Roughly: Marbled crayfish, a curious invasive species with two faces)

11 September 2016

Shinji and colleagues, 2016

Shinji J, Miyanishi H, Gotoh H, Kaneko T. 2016. Appendage regeneration after autotomy is mediated by Baboon in the crayfish Procambarus fallax f. virginalis Martin, Dorn, Kawai, Heiden and Scholtz, 2010 (Decapoda: Astacoidea: Cambaridae). Journal of Crustacean Biology 36(5): 649-657. http://dx.doi.org/10.1163/1937240x-00002458

Abstract

Autotomy is an adaptive response in which animals escape from predators by shedding their own appendages. It is made possible by the presence of an efficient mechanism for regeneration. Decapod crustaceans frequently exhibit excellent abilities to regenerate complete pereopods in just a few molts following autotomy. The molecular basis of regeneration pereopods in decapods remains unclear. We identified the primary structure of Baboon (Babo), a type I TGF-β superfamily receptor involved in the activin pathway, in the crayfish, Procambarus fallax f. virginalis Martin, Dorn, Kawai, Heiden and Scholtz, 2010. Molecular cloning revealed that babo possesses three splice variants. The expression levels of the functional babo transcript did not show increases during regeneration. RNA interference (RNAi) targeting a common region of the babo sequence, however, caused a reduction in regenerated pereopod lengths. No loss or reduction in a specific article was observed. Instead, the regenerated legs were smaller but retained the morphology and proportions of regenerated legs from control animals. Babo thus appears to control the growth, but not the pattern, of legs during the regeneration process in decapod crustaceans.

Keywords: signaling • marmorkrebs • marbled crayfish • receptor • TGF-β • activin

10 September 2016

Oleha and colleagues, 2016

Oleha M, Elena F, Alexandra N. 2016. Impact of low-molecule acidic peptides on growth and histological structure of inner organs of marbled crayfish Procambarus fallax (Hagen, 1870) f. virginalis. International Letters of Natural Sciences 56: 1-6. http://dx.doi.org/10.18052/www.scipress.com/ILNS.56.1

Abstract

The results of studies on the effects of low molecular weight acidic solution peptides on the growth and development of the marbled crayfish artificial cultivation. An increasing weights of juvenile freshwater crayfish under the influence of dietary supplement “Albuvir” drug. With the use of histological methods of research, found the impact of 0.01% solution of the drug on the state of the marbled crayfish lobules of hepatopancreas and fat cells. Developed a method for growing juvenile freshwater crayfish with “Albuvir”, which allows to increase the weight gain of crustaceans on 24.3–27.2% and reduce the level of cannibalism at 20%.

Keywords: Albuvir • marbled crayfish • Marmorkrebs • Procambarus fallax

15 August 2016

Kato and colleagues, 2016

Kato M, Hiruta C, Tochinai S. 2016. The behavior of chromosomes during parthenogenetic oogenesis in Marmorkrebs Procambarus fallax f. virginalis. Zoological Science 33(4): 426-430. http://dx.doi.org/10.2108/zs160018

Abstract

Parthenogenetic oogenesis varies among and even within species. Based on cytological mechanisms, it can largely be divided into apomixis (ameiotic parthenogenesis) producing genetically identical progeny, and automixis (meiotic parthenogenesis) producing genetically non-identical progeny. Polyploidy is common in parthenogenetic species, although the association between parthenogenesis and polyploidy throughout evolution is poorly understood. Marmorkrebs, or the marbled crayfish, was first identified as a parthenogenetic decapod and was tentatively named as Procambarus fallax f. virginalis. Previous studies revealed that Marmorkrebs is triploid and produces genetically identical offspring, suggesting that apomixis occurs during parthenogenetic oogenesis. However, the behavior of chromosomes during the process of oogenesis is still not well characterized. In this study, we observed parthenogenetic oogenesis around the time of ovulation in P. fallax f. virginalis by histology and immunohistochemistry. During oogenesis, the chromosomes were separated into two groups and behaved independently from each other, and one complete division corresponding to mitosis (the second meiosis-like division) was observed. This suggests that parthenogenetic oogenesis in Marmorkrebs exhibits gonomery, a phenomenon commonly found in apomictic parthenogenesis in polyploid animals.

Keywords: parthenogenesis • apomixis • chromosome behavior • oogenesis • Marmorkrebs • gonomery

27 July 2016

Nominations for 2017 Gherardi Prize

It is once again time to work on applications for the Francesca Gherardi Memorial Prize! You are eligible if:

  • You study aquatic invasive species;
  • You’re young (less than 40);
  • Don’t have a permanent position (a grad student or post-doc, usually)

Applications are due 30 November 2016.
External links

Francesca Gherardi Memorial Prize