Karyotype and genome size of Iberochondrostoma almacai (Teleostei, Cyprinidae) and comparison with the sister-species I.lusitanicum

This study aimed to define the karyotype of the recently described Iberian endemic Iberochondrostoma almacai, to revisit the previously documented chromosome polymorphisms of its sister species I.lusitanicum using C-, Ag-/CMA3 and RE-banding, and to compare the two species genome sizes. A 2n = 50 karyotype (with the exception of a triploid I.lusitanicum specimen) and a corresponding haploid chromosome formula of 7M:15SM:3A (FN = 94) were found. Multiple NORs were observed in both species (in two submetacentric chromosome pairs, one of them clearly homologous) and a higher intra and interpopulational variability was evidenced in I.lusitanicum. Flow cytometry measurements of nuclear DNA content showed some significant differences in genome size both between and within species: the genome of I. almacai was smaller than that of I.lusitanicum (mean values 2.61 and 2.93 pg, respectively), which presented a clear interpopulational variability (mean values ranging from 2.72 to 3.00 pg). These data allowed the distinction of both taxa and confirmed the existence of two well differentiated groups within I. lusitanicum: one that includes the populations from the right bank of the Tejo and Samarra drainages, and another that reunites the southern populations. The peculiar differences between the two species, presently listed as “Critically Endangered”, reinforced the importance of this study for future conservation plans

Mechanosensing is critical for axon growth in the developing brain.

During nervous system development, neurons extend axons along well-defined pathways. The current understanding of axon pathfinding is based mainly on chemical signaling. However, growing neurons interact not only chemically but also mechanically with their environment. Here we identify mechanical signals as important regulators of axon pathfinding. In vitro, substrate stiffness determined growth patterns of Xenopus retinal ganglion cell axons. In vivo atomic force microscopy revealed a noticeable pattern of stiffness gradients in the embryonic brain. Retinal ganglion cell axons grew toward softer tissue, which was reproduced in vitro in the absence of chemical gradients. To test the importance of mechanical signals for axon growth in vivo, we altered brain stiffness, blocked mechanotransduction pharmacologically and knocked down the mechanosensitive ion channel piezo1. All treatments resulted in aberrant axonal growth and pathfinding errors, suggesting that local tissue stiffness, read out by mechanosensitive ion channels, is critically involved in instructing neuronal growth in vivo.This work was supported by the German National Academic Foundation (scholarship to D.E.K.), Wellcome Trust and Cambridge Trusts (scholarships to A.J.T.), Winston Churchill Foundation of the United States (scholarship to S.K.F.), Herchel Smith Foundation (Research Studentship to S.K.F.), CNPq 307333/2013-2 (L.d.F.C.), NAP-PRP-USP and FAPESP 11/50761-2 (L.d.F.C.), UK EPSRC BT grant (J.G.), Wellcome Trust WT085314 and the European Research Council 322817 grants (C.E.H.); an Alexander von Humboldt Foundation Feodor Lynen Fellowship (K.F.), UK BBSRC grant BB/M021394/1 (K.F.), the Human Frontier Science Program Young Investigator Grant RGY0074/2013 (K.F.), the UK Medical Research Council Career Development Award G1100312/1 (K.F.) and the Eunice Kennedy Shriver National Institute Of Child Health & Human Development of the National Institutes of Health under Award Number R21HD080585 (K.F.).This is the author accepted manuscript. The final version is available from Nature Publishing Group via https://doi.org/10.1038/nn.439

Primary Postnatal Dorsal Root Ganglion Culture from Conventionally Slaughtered Calves

Neurological disorders in ruminants have an important impact on veterinary health, but very few host-specific in vitro models have been established to study diseases affecting the nervous system. Here we describe a primary neuronal dorsal root ganglia (DRG) culture derived from calves after being conventionally slaughtered for food consumption. The study focuses on the in vitro characterization of bovine DRG cell populations by immunofluorescence analysis. The effects of various growth factors on neuron viability, neurite outgrowth and arborisation were evaluated by morphological analysis. Bovine DRG neurons are able to survive for more than 4 weeks in culture. GF supplementation is not required for neuronal survival and neurite outgrowth. However, exogenously added growth factors promote neurite outgrowth. DRG cultures from regularly slaughtered calves represent a promising and sustainable host specific model for the investigation of pain and neurological diseases in bovines

Garden ponds as potential introduction pathway of ornamental crayfish

The private stocking of ornamental crayfish in garden ponds was discussed in previous studies, but there is a lack of detailed analysis for better understanding of this introduction pathway. The Czech Republic is one of leading EU countries in trade with ornamental crayfish and private garden ponds are popular among people. The crayfish keepers in the country were interviewed by self-administered questionnaire to gather data about principal characteristics of the keepers and detailed information about crayfish breeding that are of interest for conservation managers. Besides of releasing crayfish into garden ponds, alarming illegal behavior such as releasing of juvenile crayfish into the wild, and capturing of indigenous crayfish from wild populations, were registered. Therefore focusing on public education to increase awareness of possible unwanted consequences of crayfish release and introduction of an obligation to inform customers about hazardousness of non-indigenous crayfish species for retailers and wholesalers is recommended

Establishment risk from pet-trade freshwater turtles in the European Union

The pet-turtle market has grown in recent years and become an important pathway for the introduction of alien species in Europe. The import of Trachemys scripta elegans has been banned by European Commission Regulation due to its species’ expanding territory and negative impact on native species. Since the demand from hobby breeders persists, however, blocking imports of this popular subspecies opens up the possibility for the introduction of other potentially invasive turtles. We determined those turtle species most common in the pet trade within the Czech Republic, which is the most important producer, importer and exporter of ornamental aquatic animals in the EU. The determination of establishment risk for the EU as a whole was then individually evaluated for turtle species based on known establishment models. Chelydra serpentina, Apalone spinifera, Apalone mutica, and Sternotherus odoratus were considered most problematic, because these species have serious establishment risk and are imported to the EU in substantial numbers. Also localities in the EU were identified where probability is highest for establishment of non-native turtles

Imports of ornamental crayfish: the first decade from the Czech Republic’s perspective

The import of aquarium animals has been increasing worldwide in recent years. Despite its contribution to world trade and the economy, this trade also comprises one of the main pathways for the introduction of non-indigenous animals. In the past decade, crayfish has become a popular pet as well as a potential threat to the environment upon its escape or release. Since the Czech Republic is one of the world’s leading importer, exporter, and producer of aquatic ornamental animals, we prepared a detailed analysis of crayfish imports. The present paper provides a complete list of countries supplying ornamental crayfish and examines trends of their prices and imported quantities during the past decade (2003–2012). Indonesia has been identified as the leading supplier in recent years. The annual average price of imported crayfish has varied over the evaluated period within the range of €0.76–4.72 per individual and it is rising annually by €0.15. The quantity of live crayfish imported for aquarium purposes has not been affected significantly by the price per individual and it has grown rapidly. Therefore a constant monitoring of this pet trade sector is strongly recommended for the future

Establishment risk from pet-trade freshwater turtles in the European Union

The pet-turtle market has grown in recent years and become an important pathway for the introduction of alien species in Europe. The import of Trachemys scripta elegans has been banned by European Commission Regulation due to its species’ expanding territory and negative impact on native species. Since the demand from hobby breeders persists, however, blocking imports of this popular subspecies opens up the possibility for the introduction of other potentially invasive turtles. We determined those turtle species most common in the pet trade within the Czech Republic, which is the most important producer, importer and exporter of ornamental aquatic animals in the EU. The determination of establishment risk for the EU as a whole was then individually evaluated for turtle species based on known establishment models. Chelydra serpentina, Apalone spinifera, Apalone mutica, and Sternotherus odoratus were considered most problematic, because these species have serious establishment risk and are imported to the EU in substantial numbers. Also localities in the EU were identified where probability is highest for establishment of non-native turtles

Imports of ornamental crayfish: the first decade from the Czech Republic’s perspective

The import of aquarium animals has been increasing worldwide in recent years. Despite its contribution to world trade and the economy, this trade also comprises one of the main pathways for the introduction of non-indigenous animals. In the past decade, crayfish has become a popular pet as well as a potential threat to the environment upon its escape or release. Since the Czech Republic is one of the world’s leading importer, exporter, and producer of aquatic ornamental animals, we prepared a detailed analysis of crayfish imports. The present paper provides a complete list of countries supplying ornamental crayfish and examines trends of their prices and imported quantities during the past decade (2003–2012). Indonesia has been identified as the leading supplier in recent years. The annual average price of imported crayfish has varied over the evaluated period within the range of €0.76–4.72 per individual and it is rising annually by €0.15. The quantity of live crayfish imported for aquarium purposes has not been affected significantly by the price per individual and it has grown rapidly. Therefore a constant monitoring of this pet trade sector is strongly recommended for the future