27 February 2017

Velisek and colleagues, 2017

Velisek J, Stara A, Zuskova E, Kouba A. 2017. Effects of three triazine metabolites and their mixture at environmentally relevant concentrations on early life stages of marbled crayfish (Procambarus fallax f. virginalis). Chemosphere 175: 440-445. http://dx.doi.org/10.1016/j.chemosphere.2017.02.080


The sensitivity of early life stages of marbled crayfish (Procambarus fallax f. virginalis) to chronic exposure of one out of three triazine metabolites (terbuthylazine 2-hydroxy – T2H, terbuthylazine-desethyl – TD, and atrazine 2-hydroxy – A2H) and their mixture at maximal environmentally real concentrations was evaluated under laboratory conditions. The effects were assessed on the basis of mortality, growth, development, oxidative stress biomarkers, antioxidant enzymes activity and histopathology. Single metabolites (T2H – 0.73 μg/L; TD – 1.80 μg/L; A2H – 0.66 μg/L) and their mixture were not associated with negative effects on mortality, behaviour and early ontogeny, however, two metabolites (TD and A2H) and mixtures caused significantly lower growth and significantly higher catalase activity of early life stages of marbled crayfish. No histopathological changes of gills were observed after exposure to all tested triazine treatments, however, apparent histological differences in structural cells organization such as superiority in numbers of lipid resorptive cells were recorded in after exposition to TD and mixture. In conclusion, this study shows potential risk of using triazine herbicides in agriculture due to effects of their degradation products on non-target organisms.

Keywords: antioxidant enzyme • developmental stage • histopathology • oxidative stress • toxicity test

13 February 2017

Koutnik and colleagues, 2017

Koutnik D, Stara A, Zuskova E, Kouba A, Velisek J. 2017. The chronic effects of terbuthylazine-2-hydroxy on early life stages of marbled crayfish (Procambarus fallax f. virginalis). Pesticide Biochemistry and Physiology 136: 29-33. http://dx.doi.org/10.1016/j.pestbp.2016.08.008


This study assessed the chronic effects of terbuthylazine-2-hydroxy (T2H), one of the main terbuthylazine degradation products, on early life stages of marbled crayfish (Procambarus fallax f. virginalis) by means of mortality, growth rate, early ontogeny, oxidative stress, antioxidant defence and histopathology. The crayfish were exposed to four concentrations of the tested substance as follows: 0.75 μg/l (environmental concentration), 75, 375 and 750 μg/l for 62 days. Concentrations over 75 μg/l caused lower weight compared to the control group. T2H at 750 μg/l caused delay in ontogenetic development. Levels of thiobarbituric acid reactive substances and total superoxide dismutase activity were significantly (p < 0.01) lower in groups exposed to 375 and 750 μg/l T2H. Crayfish in these treatments also showed alteration of tubular system including disintegration of tubular epithelium with complete loss of structure in some places of hepatopancreas and wall thinning up to disintegration of branchial filaments with focal infiltrations of hemocytes. In conclusion, chronic terbuthylazine-2-hydroxy exposure in concentrations up 75 μg/l (100 times higher than environmental concentration) affected growth, ontogenetic development, antioxidant system, caused oxidative stress and pathological changes in hepatopancreas of early life stages of marbled crayfish.

Keywords: triazine • early development • histopathology • oxidative stress •antioxidant enzymes

08 February 2017

Eighteenth Crustaceologentagung

The 18th meeting of German speaking carcinologists (Crustaceologentagung) will be held from 30 March to 2 April 2017 at the Humboldt-Universität zu Berlin. Visit the website (and maybe Google Translate) for more information.

Although now that I think about it, if you need Google Translate to understand the web page, you probably wouldn’t get much out of the meeting.

External links

07 February 2017

How could I miss Croatia?

I’m red-faced. It’s about two years since a short note appeared mentioning the discovery of Marmorkrebs in northern Croatia (Samardžić et al. 2014). This is one I should have caught, too, since it appeared in the newsletter of the International Association of Astacology, of which I am a member! Always read the newsletters of your professional societies, citizens!

I have updated the map of Marmorkrebs introductions with this record, and others (more recent – hadn’t missed them,. just hadn’t added them) in the Czech republic.


Patoka J, Buric M, Kolár V, Bláha M, Petrtýl M, Franta P, Tropek R, Kalous L, Petrusek A, Kouba A. 2016. Predictions of marbled crayfish establishment in conurbations fulfilled: evidences from the Czech Republic. Biologia 71(12): 1380–1385. https://doi.org/10.1515/biolog-2016-0164

Samardžić M, Lucić A, Maguire I, Hudina S. 2014. The first record of the marbled crayfish (Procambarus fallax (Hagen, 1870) f. virginalis) in Croatia. Crayfish News 36(4): 4. http://www.freshwatercrayfish.org/docs/cn/CrayfishNews_36(4)_hr.pdf

06 February 2017

Call for crustacean papers: Fishes

Even though I have been a working professional scientist for some time, there are always more journals than time, so I am always on the lookout for journals that would be appropriate for Marmorkrebs papers.

When I first saw the journal Fishes, I though, “This is not for me, because I don’t study animals with backbones.” But despite the title, Fishes takes papers on invertebrates, too. The journal’s mandate includes “aquatic life science and aquatic animals (fishes, molluscs and crustaceans, both fresh water and marine).”

Fishes caught my eye for a few reasons.

It is a new journal, it is open access, and they are waiving article processing charges for articles published in 2017. Given that the main reason I see people not publishing open access is that people are unable to pay article processing fees, offering free publication as an “introductory offer,” as it were, is interesting to many researcher.

That said, while this journal doesn’t have much of a track record yet, the publisher, MDPI, has a mixed track record at best.

In brief, on the negative column, MDPI journals have published several very poor papers. They have also sent out a lot of unsolicited emails (this post was prompted by one).

On the positives column, MDPI is a member of the Directory of Open Access Journals and the Committe on Publication Ethics. The Fishes editor-in-chief appears to be a real person. Richard Poynder has a thorough article and interview from 2015 covering the debates about whether the Fishes publisher could be rightfully called a “predatory publisher.” Scammers are typically not as transparent as MDPI owner Shu-Kun Lin is in this interview, although some of his answers give me pause.

And publishing articles for free – as Fishes is doing this year – would be an incredibly bad scam.

External links

The Open Access Interviews: Publisher MDPI
Is MDPI a reputable Academic Publisher?

23 January 2017

New International Association for Astacology website

 The new site for the professional society for all things crayfish is now:


The relaunch is looking pretty sharp, I must say! The landing page has a lovely rotating gallery of very high resolution crayfish pictures.

19 January 2017

Falckenhayn, 2016

Falckenhayn C. 2016. The methylome of the marbled crayfish Procambarus virginalis. Doctoral dissertation, Combined Faculties for the Natural Sciences and for Mathematics, University of Heidelberg, Heidelberg. http://archiv.ub.uni-heidelberg.de/volltextserver/22489/1/Falckenhayn_Cassandra_PhDThesis.pdf


DNA methylation in invertebrates seems to play a different role as in mammals and its evolutionary conservation among invertebrates is unclear. Only two studies describe crustacean methylomes giving just a small overview. The parthenogenetic reproducing marbled crayfish display a high environmental adaptability besides its genetic uniformity and thus, possess the necessary attributes of a laboratory model organism. The aim of this work was to characterize the methylome of the marbled crayfish at single-base resolution using whole-genome bisulfite sequencing in an attempt to give new insights into DNA methylation in crustaceans and thus, in the evolutionary conservation among invertebrates. Analysis of the mitochondrial DNA of different marbled crayfish strains revealed a single origin and suggests to consider the marbled crayfish as independent asexual species Procambarus virginalis. Furthermore, since the P. virginalis possess a large genome size, the transcriptome was assembled and comparison to other species revealed a relative good quality of the first draft transcriptome as well as the presence of a conserved DNA methylation system in P. virginalis. Analysis of the CpG depletion in protein-coding sequences and mass spectrometry confirmed historical germline and current DNA methylation in various tissues of P. virginalis. The methylome was characterized by the key features of animal methylomes with methylation targeted to gene bodies. The gene bodies displayed the typical pattern of a mosaically methylated invertebrate genome and a bimodal distribution of their methylation levels. Targeted gene bodies were annotated as housekeeping genes and methylation showed a parabolic relationship to housekeeping gene expression suggesting that the DNA methylation of housekeeping genes might fine-tune their expression. Additionally, repeats were generally hypomethylated and the methylation of repeats depended on their position to gene bodies. Finally, inter-individual and inter-tissue comparison of gene body methylation revealed a high reproducibility of the methylation patterns, while inter-species comparison between P. fallax and P. virginalis displayed an overall hypomethylation in the P. virginalis genes which however, could not explain the by mass spectrometry detected global hypomethylation in P. virginalis. These findings uncovered that the P. virginalis methylome is characterized by tissue-invariant housekeeping gene methylation. This thesis describes novel insights into the evolutionary conservation of gene body and repeat methylation in invertebrates, especially crustaceans, and the preferential methylation of housekeeping genes highlights a functional difference to the tissue-specific methylation in mammals.

Keywords: None provided.