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


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

26 July 2016

Incoming: Biology and Ecology of Crayfish

A new crayfish book is out! Biology and Ecology of Crayfish has ten chapters of freshwater crustacean goodness. Marmorkrebs make a few cameo appearances in chapters marked with an asterisk.

  1. Taxonomy and identification. 
  2. Population genetics of crayfish: endangered and invasive species. *
  3. Crayfish growth and reproduction. *
  4. Behavior of freshwater crayfish. 
  5. Chemical ecology of crayfish. 
  6. Parasites, commensals, pathogens and diseases of crayfish. *
  7. Environmental drivers for population success: population biology, population and community dynamics. *
  8. Sampling techniques for crayfish. 
  9. Laboratory methods for crayfish studies. 
  10. The management of invasive crayfish. *

External links

Biology and Ecology of Crayfish (Publisher website)

19 July 2016

Jackson, 2016

Jackson CJ. 2016. Characterization of locomotor response to psychostimulants in the parthenogenetic marbled crayfish (Procambarus fallax forma virginalis): a promising model for studying the epigenetics of addiction. Master’s thesis, Department of Biology, Bowling Green State University, Bowling Green, Ohio. https://etd.ohiolink.edu/!etd.send_file?accession=bgsu1467967151&disposition=inline


Chapter I: Epigenetic regulation has been implicated as an important factor in understanding the molecular mechanisms of drug addiction. This is due to the life -long behavioral changes that commonly afflict addicted individuals long after drug exposure has been extinguished. Invertebrates, such as crayfish, offer excellent model systems to study these molecular mechanisms because they retain the ancestral neural reward circuit that is evolutionarily conserved across taxa, possess relatively few, large neurons, and have an accessible, modularly organized nervous system. The marbled crayfish (Procambarus fallax forma virginalis), in particular, has potential as a model for epigenetic studies because it is parthenogenetic, and thus all individuals are genetic clones. To provide the foundation of this model system for parsing the epigenetic mechanisms of drug addiction, here I characterize the locomotor response of juvenile P. f. f . virginalis exposed to the psychostimulant, d-amphetamine sulfate. Custom video-tracking software was used to record the movement patterns of juveniles exposed to water infused with varying concentrations of d-amphetamine sulfate. ANOVA demonstrated that crayfish locomotion was significantly impacted by drug concentration. These psychostimulant effects, along with the non-invasive mode of drug delivery, which avoids potential epigenetic changes resulting from the stress of direct injection into the hemolymph, set the stage for using P. f. f . virginalis as an animal model for epigenetic studies.

Chapter II: With the rising interest in using invertebrate models for behavioral epigenetic studies, and the tissue- specific nature of epigenetic changes, there is a need for effective methods of extracting genomic DNA from neural tissue. Invertebrates, such as crayfish, represent useful models in which to parse out the basic underlying epigenetic changes because of the relatively simplified anatomical structure of their nervous system. The parthenogenetic marbled crayfish (Procambarus fallax forma virginalis) offers a particularly elegant system because it reproduces asexually and produces large numbers of genetically identical offspring. However, the low DNA yield of fatty neural tissue combined with small sample size represent technical challenges in using invertebrate brains. The present study seeks to support the use of the marbled crayfish as a model for studying the mechanisms of behavioral epigenetics by providing an optimized method for genomic DNA extraction from invertebrate neural tissue.

Keywords: None provided.

22 June 2016

Chucholl, 2016b

Chucholl C. 2016b. The bad and the super-bad: prioritising the threat of six invasive alien to three imperilled native crayfishes. Biological Invasions 18(7): 1967-1988. http://dx.doi.org/10.1007/s10530-016-1141-2


Multiple species invasions and limited resources for management require prioritisation of deleterious effects of invaders on imperilled native species. This study prioritises the threat of six non-indigenous crayfish species (NICS) to three indigenous crayfish species (ICS) in southwestern Germany, a European region with high diversity of crayfish species and freshwater habitats. Using multivariate statistical analyses and niche-based species distribution models, the (1) contemporary and potential range overlap, (2) habitat overlap, and (3) rate of spread of the nine species were assessed. Predicted and contemporary range overlap with ICS was consistently the highest for the alien signal crayfish. Environmental niches of ICS tended to be associated with cooler temperatures (except for white-clawed crayfish), lower Human Influence Index, and higher terrain slope than that of alien Orconectes and Procambarus species, but were mostly similar to that of signal crayfish. Habitat overlap was found to be the highest between signal crayfish and ICS. In contrast to Orconectes and Procambarus species, signal crayfish also invade headwaters, where the most ICS populations occur. Range expansion during the past 15 years was the highest for signal crayfish, followed by Orconectes species. Because of the great potential to invade as-yet isolated refuge areas and spread at a high rate, signal crayfish is of the highest concern for conservation of ICS and should be primarily targeted by prevention and control measures. However, it merely represents the ‘worst of the worst’, since all NICS of North American origin are natural reservoirs of crayfish plague, a fatal disease of ICS.

Keywords: aquatic invaders • risk assessment • Crustacea • distribution models • habitat association

Lipták and colleagues, 2016

Lipták B, Mrugala A, Pekárik L, Mutkovic A, Grula D, Petrusek A, Kouba A. 2016. Expansion of the marbled crayfish in Slovakia: beginning of an invasion in the Danube catchment? Journal of Limnology 75(2): 305-312. http://dx.doi.org/10.4081/jlimnol.2016.1313


The marbled crayfish, Procambarus fallax f. virginalis, is a taxon widely available in the aquarium pet trade, which has been introduced to open waters in several European countries and in Madagascar. Recent studies confirmed this parthenogenetically reproducing crayfish as a high-risk invasive species, and vector of the crayfish plague pathogen, Aphanomyces astaci. It has been first discovered in Slovakia in 2010, but the status of the local population was not studied since then. Due to enlarged sampling area around the first report and one locality, where we presupposed the crayfish occurrence, we identified new marbled crayfish populations. Here, we report presence of three newly established marbled crayfish populations in Slovakia. Two populations are located critically close to the Váh River, a major tributary of the Danube River; one of them being directly connected to the Váh River via a side channel during occasional floods. The third established marbled crayfish population was found at the mouth of a thermal stream flowing into the Nitra River, a tributary of the Váh River. In this stream, crayfish coexist with other exotic fish and gastropod species of aquarium origin. We presume that the reported localities may serve as a source for further expansion of the marbled crayfish in the mid-part of the Danube catchment. Floods, active dispersal (including overland), passive dispersal by zoochory or anthropogenic translocations are among the major drivers facilitating the marbled crayfish colonization. We have not detected the crayfish plague pathogen in any of the studied populations. However, if spreading further, the marbled crayfish will encounter established populations of crayfish plague carriers in the Danube River, in which case they may acquire the pathogen by horizontal transmission and contribute to spread of this disease to indigenous European crayfish species.

Keywords: aquarium pet trade • crayfish plague • freshwater crayfish • Procambarus fallax f. virginalis • species introductions

11 June 2016

Chatila, 2016

Chatila Z. 2016. Lentiviral GFP transfection of the parthenogenic crayfish species, Procambarus fallax: a tool for examining the source of neural precursor cells in crayfish. Undergraduate honors thesis, Neuroscience, Wellesley College. http://repository.wellesley.edu/thesiscollection/345/


The thesis is embargoed online until 22 April 2018. I am attempting to get a copy of the abstract to place here earlier than that.