09 December 2017

Oleh and colleagues, 2017

Oleh M, Julia K, Zoya S, Olexandra N, Oleh N, Bogdan D. 2017. Parameters of the histological adaptation of Marmorkrebs Procambarus fallax f. virginal (sic) (Decapoda, Cambaridae) to zinc and cadmium ions pollution. World Scientific News 90: 189-202. http://www.worldscientificnews.com/wp-content/uploads/2017/08/WSN-90-2017-189-202.pdf

Abstract

Due to the fact that marbled crayfish (Marmorkrebs) got into the reservoirs of the Dnipropetrovsk region in 2015, it was necessary to study the possibilities of its adaptation to environmental factors of reservoirs for further prediction of its distribution or even acclimatization under conditions of toxicological contamination of the ponds of the steppe Prydniprovya. The article presents the results of studies on the influence of heavy metal ions on marbled crayfish. It was determined that zinc and cadmium ions affect weight indicators, survival and reproduction of experimental crayfish. Experimentally simulated concentrations of heavy metals on the example of zinc – 0.1 mg/l (10 MPC) and cadmium – 0.01 mg/l (2 MPC) allowed detecting the reaction of the excretory system of marbled crayfish. It is determined that under the influence of heavy metal ions the area of glandulocytes cells decreases by 10.4–14.8%. Also, there is a decrease in the cellular nucleus, thus, under the influence of zinc, the nucleus of the secretory cells was 23.6% smaller, and under the influence of cadmium by 17.5%. To study the influence of zinc and cadmium on the glandular cells of the green gland of marbled crayfish, the index of nuclear-cytoplasmic ratio (NCR) was used. The indicator of nuclear-cytoplasmic ratio allows estimating the level of metabolism and detecting the manifestation of compensatory reactions of the organism of experimental crayfish. The value of NCR in the experiment and control was not statistically different and ranged from 0.29 to 0.31 units. This indicates an interproportional reduction in both the cytoplasm of the cells of the green gland and their nuclei, caused by heavy metals exposure. The negative influence of heavy metals on the histostructure of hepatopancreas of marbled crayfish was determined; significant changes in the structure of tissue were noted, heavy metals influenced the shape of the hepatopancerase lobes and the size of the lumen. The worst histological picture of cells of experimental tissues and organs of marbled crayfish was observed in individuals exposed to cadmium ions due to the toxicological effects of this heavy metal. Investigation of the histological structure of tissues and organs of marbled crayfish will allow the development of measures for the determination of biomarkers for the bioindication of the aquatic environment using freshwater crayfish. The results of such studies have an important fundamental and applied significance for understanding the mechanisms of adaptation of crustaceans to the conditions of toxicological burden on aquatic ecosystems.

Keywords: Procambarus fallax f. virginalis Martin et al., 2010 • marbled crayfish • heavy metals • glandulocytes • hepatopancreas

Penk and colleagues, 2017

Penk M, Saul W-C, Dick JTA, Donohue I, Alexander ME, Linzmaier S, Jeschke JM. 2017. A trophic interaction framework for identifying the invasive capacity of novel organisms. Methods in Ecology and Evolution 8(12): 1786–1794. http://dx.doi.org/10.1111/2041-210X.12817

Abstract

1. The likelihood and impacts of invasions by novel organisms (e.g. non-native species, genetically-modified organisms) on the composition and functioning of receiving biological communities hinges on their capacity to exploit resources and/or avoid predation relative to resident counterparts. While assessment of invasion risk based on the comparison of functional responses (per-capita consumption rate as a function of resource density) of novel species with native analogues has been gaining popularity, it may be undermined if alternative prey and potential predators are not represented realistically.

2. Here, we propose a conceptual framework that enables rigorous identification of trophic traits conducive to invasion success by novel organisms – irrespective of their trophic position – and their likely ecological impacts, given their arrival and establishment. We focus on consumption here, but our framework can also be used for autotrophic energy acquisition, and extended to non-trophic and indirect interactions.

3. The framework enables a structured and prioritised selection of subsets of trophic links for invasion risk assessment. It is based on foraging theory and advances in comparative functional responses in invasion ecology. It can even be used in the absence of a resident comparator organism and when resources or predators are only partly known.

4. Our approach enhances the predictive power of species screening, and thus advances prevention and management of invasions under a common framework for all types of novel organisms.

Keywords: Alien species • dietary generalism • ecological novelty • GMO • invasion success • functional responses • predator-prey trophic interactions • risk assessment

Pârvulescu and colleagues, 2017

Pârvulescu L, Togor A, Lele S-F, Scheu S, Șinca D, Panteleit J. 2017. First established population of marbled crayfish Procambarus fallax (Hagen, 1870) f. virginalis (Decapoda, Cambaridae) in Romania. BioInvasions Records 6(4): 357-362. https://doi.org/10.3391/bir.2017.6.4.09

Abstract

The marbled crayfish, Procambarus fallax f. virginialis, is an obligate parthenogenetic crayfish species, its spread in the wild being linked to the aquarium pet-trade. Forty-two adult individuals were found for the first time in Romania in the semi-natural ponds in Băile Felix, near Oradea. Nine ovigerous females were captured as evidence that the population is breeding in the wild. They probably originated from the pet trade and were released by hobbyists into the pond. Microsatellite analysis revealed the same allelic patterns as in a previous study, confirming that these marbled crayfish are parthenogenetic and originate from a single individual. The crayfish plague pathogen Aphanomyces astaci was not present in the population. The site inhabited by this established marbled crayfish population is supplied with water by thermal underground streams, ensuring a constant high temperature. The nearby Peța Natural Reserve protects several endemic species that could be threatened by the further range extension of marbled crayfish. Special protection measures are therefore urgently needed.
Keywords: invasive species • Marmorkrebs • parthenogenesis • pet trade



16 November 2017

Shinji and colleagues, 2017

Shinji J, Miyanishi H, Gotoh H, Lavine M, Lavine L. 2017. The role of the transcription factor Smox during appendage regeneration in the crayfish Procambarus fallax f. virginalis. Presentation SP06-28 at The Japanese Society of Fisheries Science 85th Anniversary-Commemorative International Symposium, “Fisheries Science for Future Generations,” Tokyo University of Marine Science and Technology, 22 to 24 September 2017. https://www.gakkai-web.net/gakkai/jsfs/sympo/usb/data/html/P02.html

Abstract

Regeneration is a common phenomenon among animals. Members of the phylum Arthropoda, comprising over 80% of total animal species, exhibit strong capacities for regeneration, but little is known about the molecular mechanisms mediating this process. In this study, we investigated the role of the activin signaling pathway in limb regeneration in the decapod crustacean Procambarus fallax f. virginalis. We identified and cloned a downstream transcription factor in the activin pathway, Smox. The Smox gene showed 3 splicing variants, but only one of them encoded a complete Smox transcription factor. Gene knockdown of Smox by RNAi induced formation of smaller limb buds and regeneration of complete but smaller pereopods after autotomy. This indicates that activin signaling via Smox functions in regulation of pereopod size. The expression levels of both Smox and the activin receptor babo were closely correlated with molting. The expression level of Smox during the molting cycle increased when the receptor babo was knocked down by RNAi, indicating that Smox and babo transcription are linked. Our study suggests that the Babo-Smox system in activin signaling is conserved in decapods, and supports an evolutionary conservation of this aspect of molecular signaling during regeneration between protostomes and deuterostomes.

Keywords: None provided.

14 November 2017

Gutekunst, 2017

Gutekunst J. 2017. Clonal genome evolution of the marbled crayfish, Procambarus virginalis. Doctoral thesis, Combined Faculties of Natural Sciences and Mathematics, Ruperto-Carola University Heidelberg. Heidelberg, Germany. 88 pp. https://doi.org/10.11588/heidok.00023501

Abstract

Marbled crayfish (Procambarus virginalis) are the only freshwater crayfish known to reproduce by cloning (apomictic parthenogenesis). Notably, among genetically identical offspring raised in the same environment, distinct phenotypic differences can be observed. These unique characteristics establish the marbled crayfish as a particularly interesting laboratory model. Additionally, parthenogenetic reproduction enables the marbled crayfish to rapidly spread and form stable populations, which poses a serious threat in many freshwater habitats. A further understanding of this organism requires the accessibility of its 3.5 Gbp large genome sequence.

This doctoral thesis provides the first de novo genome assembly of the marbled crayfish. Multiple shotgun and long jumping distance libraries were generated from one individual female, with a single base coverage of over 100×. Sequencing data was used for a first genome assembly with a length weighted median scaffold size (N50) of over 40 kbp. The estimated genome wide heterozygosity rate of 0.53% is substantially higher compared to other arthropod genomes. Transcriptome data enabled the refinement of genetic structures. Eventually, a total of 87.8% complete and 7.4% fragmented single-copy arthropod orthologs were identified using the benchmarking software BUSCO. Single nucleotide variations were analyzed to verify clonality in geographically isolated populations. Results indicate an evolution from a single origin. Moreover, detailed insights into genotype distributions support the theory of asexual speciation by autopolyploidization. Comparison of three Procambarus species indicates detectable genetic separation between marbled crayfish and the closest relative Procambarus fallax. Automatic annotation of 21,000 genes using the annotation pipeline MAKER provides a detailed overview of genetic features. For example, a cellulase gene was identified which potentially plays a key role in omnivorousness. Genomic data and several online services are provided by a central web resource.

This thesis provides detailed genetic insights into the unknown but very versatile order of decapod crustaceans. Considered economically and ecologically relevant keystone species, a representative genome sequence provides an important resource for future research.

Keywords: genome • marbled crayfish • Marmorkrebs • Procambarus • assembly • clonal • parthenogenesis • evolution

03 November 2017

The CABI datasheet

The Centre for Agriculture and Biosciences International (CABI) Invasive Species Compendium has “datasheets, maps, images, abstracts and full text on invasive species of the world.”

Their page on Marmorkrebs is generally very thorough!

Their distribution map seems a little out of date, and has a couple of oddities. For instance, there is one dot right in the middle of the continental United States (roughly in Kansas or Nebraska). This is supposed to represent that Marmorkrebs are available in the pet trade throughout the country, and cite Faulkes (2010) as a resource. Strangely, that paper also found Marmorkrebs for sale as pets in Canada... but there is no dot on the map for Canada.

External links

Invasive Species Compendium - Procambarus fallax f. virginalis (Marmorkrebs)

11 September 2017

Ninth International Crustacean Congress annoucement


The 9th International Crustacean Congress (ICC9) will take place 22-25 May 2018, in Washington DC, USA. The conference website is up, and will soon be available through the The Crustacean Society web page. Registration will open shortly.

I think ICC9 will be the latest “Marmorkrebs on the road” spot, and I hope to meet some fellow marbled crayfish enthusiasts there. I have schemes. Oh yes.


External links

ICC9