01 September 2020

Hossain and colleagues, 2021

Science of the Total Environment cover

Hossain MS, Kubec J, Guo W, Roje S, Ložek F, Grabicová K, Randák T, Kouba A, Buřič M. 2021. A combination of six psychoactive pharmaceuticals at environmental concentrations alter the locomotory behavior of clonal marbled crayfish. Science of The Total Environment 751: 141383. https://doi.org/10.1016/j.scitotenv.2020.141383


Pharmaceutically active compounds (PhACs) are ubiquitous in the aquatic environment worldwide and considered emerging contaminants. Their effects on growth, behavior, and physiological processes of aquatic organisms have been identified even at very low concentrations. Ecotoxicological investigations have primarily focused on single compound exposure, generally at a range of concentrations. In the natural environment, pollutants seldom occur in isolation, but little is known about the effects and risks of combinations of chemicals. This study aimed to investigate the effects of concurrent exposure to six psychoactive PhACs on locomotory behavior and life history traits of clonal marbled crayfish Procambarus virginalis. Crayfish were exposed to ~1 μg L−1 of the antidepressants sertraline, citalopram, and venlafaxine; the anxiolytic oxazepam; the opioid tramadol; and the widely abused psychostimulant methamphetamine. In the absence of shelter, exposed crayfish moved significantly shorter distances and at lower velocity and showed significantly less activity than controls. With available shelter, exposed crayfish moved significantly more distance, showed higher activity, and spent a significantly more time outside the shelter than controls. Molting, mortality, and spawning frequency did not vary significantly between the groups. Hemolymph glucose level did not vary among groups and was not correlated with observed behaviors. Results suggest that environmental concentrations of the tested compounds in combination can alter the behavior of non-target aquatic organisms as individual exposure of these compounds, which may lead to disruption of ecosystem processes due to their reduced caution in stressful conditions. Further research is needed using varied chemical mixtures, exposure systems, and habitats, considering molecular and physiological processes connected to behavior alterations.

Keywords: antidepressant • ethology • emerging contaminant • opioid • Procambarus virginalis

21 August 2020

Benson 2020

Illinois State UNiversity seal
Benson AM. 2020. Identification of innexins contributing to giant-fiber escape responses in marbled crayfish. Master's thesis, School of Biological Sciences, Illinois State University. Stein W, Vidal-Gadea A, advisors. http://doi.org/10.30707/ETD2020.Benson.A


Gap junctions form intercellular pores that coordinate the flow of electrical signals between adjacent cells in the nervous system. While the physiology of electrical synapses has been investigated in sophisticated detail, the molecular underpinnings of electrical signal spread between neurons are not well understood. Even in the crayfish tail flip escape circuit, where electrical synapses have been studied for more than six decades, the gap junction proteins underlying electrical synaptic transmission are unknown. Invertebrate gap junctions are assembled from a diverse family of proteins called innexins (inx), and previous studies have suggested that in each species multiple innexins can contribute to electrical signal spread between cells. In this study, I used the genome and transcriptome assembly of the marbled crayfish, Procambarus virginalis, to identify which innexins are present and expressed in crayfish, and which contribute to the giant fiber tail flip escape response.

My bioinformatics analyses identified 8 putative innexin genes (termed inx1- inx8), only five of which were present in the transcriptome, suggesting that inx6-8 are not necessary for the tail flip. A conserved domain search of inx1 - 5 revealed that only inx1 - 3 contained the sequence signature common to innexins, indicating that inx4 and 5 may not contribute to the functioning of electrical synapses. RNA isolation from the ventral nerve cord (VNC) and brain, which contain distinct giant neurons that mediate the two major crayfish tail-flip responses, further suggested that inx1 - 3 could contribute to the tail flip: the brain expressed two innexins (inx2- 3), whereas the ventral nerve cord expressed three innexins (inx1-3). Basic Local Alignment Search Tool (BLAST) comparisons additionally revealed that inx1 and 2 were homologous to two innexins previously identified to contribute to giant fiber escape responses in insects. To test whether inx1 or 2 contribute to giant fiber tail flips in crayfish, I reduced inx1 and 2 gene expression through RNA interference (RNAi) and measured the behavioral consequences of this diminishment on the tail flip escape response. To elicit RNAi, I created innexin-specific double-stranded RNA (dsRNA) and verified the presence of intact innexin-½ dsRNA at the expected product size of 547 bp.

Animals receiving treatment were injected with 3 µg dsRNA/ g of body weight. A comparison of innexin expression levels between untreated (n = 2), control dsRNA (n = 1), and RNAi (n = 10) treatment groups using quantitative real-time PCR (qPCR) revealed that innexin expression levels diminished two days post-treatment. Behavioral measurements showed that the response latency onset of the tail flip response correlated with innexin expression levels (n = 6). A linear regression revealed a significant correlation between innexin expression and differences in response latency onset for abdominal flexion (p < 0.05, R2 = 0.77) and subsequent extension (p < 0.05, R2 = 0.82). In contrast, the tail flip strength was unaffected by the RNAi treatment (Fig. 20; p > 0.05, R2 = 0.27). Thus, at least one of the two innexins contributes to electrical synaptic transmission in the crayfish tail flip circuit.

Keywords: None provided.

28 July 2020

Marmorkrebs and messed-up childhoods

"What Do You Think You Are?" cover
Brian Clegg is promoting his new book, What Do You Think You Are?, which is coming out next week. As part of his promotion, he has an article in i newspaper about what shapes adult life. (Really, the name of the paper is a single lower case letter i.) The thesis of the article is that your parents and school don’t matter much to your adult life.

Somewhat strangely, Marmorkrebs make an appearance to argue for “chaos” in life outcomes. Clegg writes:

Batches of Marmorkrebs were raised in nearly identical environmental conditions, yet they differed widely. Some were 20 times bigger than others. Some lived twice as long. Their behaviour was totally different. The tiny genetic and environmental differences made a huge difference in outcomes.

The claims here seem to be based on Vogt and colleagues (2008), and they deserve a little examination.

The “nearly identical” environment is bit misleading. Vogt and colleagues noted that the most variation in growth came when crayfish were raised together, and “without shelters, i.e. under conditions of social stress” (emphasis added).

It’s like saying Harry Potter and Dudley Dursley were raised in “nearly identical” conditions. Well, yes, they were generally in the same physical space. But the social reality for the two boys could hardly be more different. Dudley is spoiled. Harry is tolerated at best and harassed at worst.

Similarly, crayfish fight and form hierarchies. Just because crayfish were in the same tank and had ample food does not mean that their experience in the Dursley house – I mean, crayfish tank – is necessarily the same. Nor is it accurate to call that a “tiny” environment difference.

“20 times bigger” is a bit ambiguous. I image that people might imagine one crayfish an inch long and another 20 inches (over a foot and a half) long. But the measurements are mass, not length. Since mass increases with the cube of length, that means one crayfish is about 2.5 longer than another.

I am not sure how different behaviour has to be to count as “totally different.” I’ve watched a lot of crayfish. You can tease differences apart in experiment, but I think most people would have a hard time distinguishing the behaviour of one Marmorkrebs from another. It’s not obvious, like the relaxed dog you see chilling in the dog park and the barky aggro dog you have to keep on the leash.

I don’t know if Marmorkrebs also appear in the book. I hope they do but with perhaps a little more nuance than in this short article.

Related posts

External links
What makes us ourselves? Why your parents might not f*** you up as much as you think


Vogt G, Huber M, Thiemann M, van den Boogaart G, Schmitz OJ, Schubart CD. 2008. Production of different phenotypes from the same genotype in the same environment by developmental variation. The Journal of Experimental Biology 211(4): 510-523. http://jeb.biologists.org/cgi/content/abstract/211/4/510

15 July 2020

Map of Marmorkrebs introductions, now with Austria!

Map of Europe highlighting Austria
I made multiple additions to the big map of Marmorkrebs introductions. The biggest change is the addition of Austria to the list of countries with established Marmorkrebs populations.

The discovery of Marmorkrebs in Salzburg, Austria was published back in 2018 (Latzer and Pekny 2018), but I only just caught up to it today.

Trying to understand that paper (since it was in German) led me to another short abstract describing another Marmorkrebs finding in Austria, this time in Vienna (Moog et al. 2019). This description is brief, so the map position is not precise:

According to Thomas Ofenböck (Municipal Department 45 - Water Management), in August 2018 a single specimen was found in the 22nd district and released in the Mühlwasser.

Released? Oh, that hurts to read.

Finally, I have a more precise position for the location where Marmorkrebs were found in France. Previously, I only had a description of the area from Marc Collas’s tweet. Again, I stumbled upon a much lengthier description of the finding (Collas 2019), which included a map. That allowed me to get a more exact position.

And just to round things out, I added a couple more of sites from Hungary mentioned in Szendőfi and colleagues (2018).

Busy day. Wish I had done this before this year!


Collas M. 2019. Premier signalement de l’écrevisse marbrée (Procambarus virginalis) en Centre de ressources espèces exotiques envahissantes. http://especes-exotiques-envahissantes.fr/premier-signalement-de-lecrevisse-marbree-procambarus-virginalis-en-france/

Latzer D, Pekny R. 2018. Erstnachweis des Marmorkrebses für Österreich in Salzburg. Salzburgs Fischerei 49(3): 24-30. https://issuu.com/lfvs/docs/safisch_3-18

Moog O, Leitner P, Huber T, W. R, Graf W. 2019. Marbled Crayfish (Procambarus virginalis Lykow, (sic) 2017) – a supplement to the list of Aquatic Invertebrate Neozoa in Austria. ECOPROF. https://www.ecoprof.at/index.php/faunaaquaticaaustriaca.html?file=files/ep_downloads/faa/New_Neozoon_Marbled%20Crayfish.pdf

Szendőfi B, Bérces S, Csányi B, Gábris V, Gál B, Gönye Z, Répás E, Seprős R, B. T, Kouba A, Patoka J, Weiperth A. 2018. Egzotikus halfajok és decapodák a Barát‐ és Dera‐patakban, valamint a torkolatuk dunai élőhelyein. Pisces Hungarici 12: 47-51. http://www.haltanitarsasag.hu/ph12/Szendofi_et.al_Pisces.Hungarici_2018.pdf

Collas, 2019

Collas M. 2019. Premier signalement de l’écrevisse marbrée (Procambarus virginalis) en France.   Centre de ressources espèces exotiques envahissantes. http://especes-exotiques-envahissantes.fr/premier-signalement-de-lecrevisse-marbree-procambarus-virginalis-en-france/

(Approximate English translation of title: First report of the marbled crayfish (Procambarus virginalis) in France)


Without abstract. Translated excerpt: 

Following surveys carried out by the Moselle fishing federation, P. virginalis has just been reported for the first time in a natural environment in France, in a body of water in the context of ballast pits on the Moselle catchment area, near Metz. This morphological identification was confirmed by molecular analysis using a mitochondrial gene.

Keywords: None provided.

Moog and colleagues, 2019

Moog O, Leitner P, Huber T, W. R, Graf W. 2019. Marbled Crayfish (Procambarus virginalis Lykow, (sic) 2017) – a supplement to the list of Aquatic Invertebrate Neozoa in Austria. ECOPROF. https://www.ecoprof.at/index.php/faunaaquaticaaustriaca.html?file=files/ep_downloads/faa/New_Neozoon_Marbled%20Crayfish.pdf


The marbled crayfish (Procambarus virginalis Lykow (sic), 2017) is added to the list of aquatic invertebrate neozoa in Austria. The scientifically proven first evidence of marbled crayfish in Austria took place in June 2018 and was published by Latzer & Pekny (2018). The occurrence of the marbled crayfish is so far known only from two ponds in Salzburg (Karlsbader Weiher and pond FBZ I/135; Latzer & Pekny, 2018) and one finding in Vienna. According to Thomas Ofenböck (Municipal Department 45 - Water Management), in August 2018 a single specimen was found in the 22nd district and released in the Mühlwasser. The Mühlwasser is a former branch of the Danube at Stadlau (Vienna, 22. District); since 1875, there is no connection to the river anymore. Although the establishment status of the marble crayfish is unknown, there are two reasons for its inclusion in the list of Austrian aquatic neozoa. 1) the management of the Salzburg state fishing association (Salzburger Landesfischereiverband) must assume that the population cannot be eradicated (personal communication Mrs. Daniela Latzer, Salzburg); 2) an establishment (in the sense of permanent, reproducing populations) is to be assumed since the species reproduces parthenogenetically.

Keywords: None provided.

Latzer and Pekny, 2018

Salzburgs Fischerei 49(3) cover featuring Marmorkrebs
Latzer D, Pekny R. 2018. Erstnachweis des Marmorkrebses für Österreich in Salzburg. Salzburgs Fischerei 49(3): 24-30. https://issuu.com/lfvs/docs/safisch_3-18


Der landesfremde Marmorkrebs wurde nun erstmals in Österreich, und zwar in Salzburg gefunden: dieser Krebs ist auch als sog. „Klon-Krebs" bekannt. Es kommen nur weibliche Tiere vor, die sich parthenogenetisch, also per Jungfernzeugung, fortpflanzen.

Keywords: None provided.

Approximate English translation of abstract:

The foreign marbled crayfish was now in Austria for the first time, specifically found in Salzburg: this crayfish is also known as the “clone crayfish.” Only females come from these animals, which reproduce parthenogenetically, i.e. by means of virgin generation.