TY  - JOUR
A1  - Tobler, Michael
A1  - Schlupp, Ingo
A1  - Heubel, Katja U.
A1  - Riesch, Rudiger
A1  - Garcia de Leon, Francisco J.
A1  - Giere, Olav
A1  - Plath, Martin
T1  - Life on the edge: hydrogen sulfide and the fish communities of a Mexican cave and surrounding waters
JF  - Extremophiles : life under extreme conditions
N2  - Most eucaryotic organisms classified as living in an extreme habitat are invertebrates. Here we report of a fish living in a Mexican cave (Cueva del Azufre) that is rich in highly toxic H2S. We compared the water chemistry and fish communities of the cave and several nearby surface streams. Our study revealed high concentrations of H2S in the cave and its outflow (El Azufre). The concentrations of H2S reach more than 300 mu M inside the cave, which are acutely toxic for most fishes. In both sulfidic habitats, the diversity of fishes was heavily reduced, and Poecilia mexicana was the dominant species indicating that the presence of H2S has an all-or-none effect, permitting only few species to survive in sulfidic habitats. Compared to habitats without H2S, P. mexicana from the cave and the outflow have a significantly lower body condition. Although there are microhabitats with varying concentrations of H2S within the cave, we could not find a higher fish density in areas with lower concentrations of H2S. We discuss that P. mexicana is one of the few extremophile vertebrates. Our study supports the idea that extreme habitats lead to an impoverished species diversity.
KW  - extremophile teleosts
KW  - Poecilia mexicana
KW  - cave fish
KW  - hypoxia
KW  - chemoautotrophy
KW  - condition factor
Y1  - 2006
U6  - https://doi.org/10.1007/s00792-006-0531-2
SN  - 1431-0651
VL  - 10
SP  - 577
EP  - 585
PB  - Springer
CY  - Tokyo
ER  - 
TY  - JOUR
A1  - Schedina, Ina Maria
A1  - Groth, Detlef
A1  - Schlupp, Ingo
A1  - Tiedemann, Ralph
T1  - The gonadal transcriptome of the unisexual Amazon molly Poecilia formosa in comparison to its sexual ancestors, Poecilia mexicana and Poecilia latipinna
JF  - BMC Genomics
N2  - Background

The unisexual Amazon molly (Poecilia formosa) originated from a hybridization between two sexual species, the sailfin molly (Poecilia latipinna) and the Atlantic molly (Poecilia mexicana). The Amazon molly reproduces clonally via sperm-dependent parthenogenesis (gynogenesis), in which the sperm of closely related species triggers embryogenesis of the apomictic oocytes, but typically does not contribute genetic material to the next generation. We compare for the first time the gonadal transcriptome of the Amazon molly to those of both ancestral species, P. mexicana and P. latipinna.
Results

We sequenced the gonadal transcriptomes of the P. formosa and its parental species P. mexicana and P. latipinna using Illumina RNA-sequencing techniques (paired-end, 100 bp). De novo assembly of about 50 million raw read pairs for each species was performed using Trinity, yielding 106,922 transcripts for P. formosa, 115,175 for P. latipinna, and 133,025 for P. mexicana after eliminating contaminations. On the basis of sequence similarity comparisons to other teleost species and the UniProt databases, functional annotation, and differential expression analysis, we demonstrate the similarity of the transcriptomes among the three species. More than 40% of the transcripts for each species were functionally annotated and about 70% were assigned to orthologous genes of a closely related species. Differential expression analysis between the sexual and unisexual species uncovered 2035 up-regulated and 564 down-regulated genes in P. formosa. This was exemplary validated for six genes by qRT-PCR.
Conclusions

We identified more than 130 genes related to meiosis and reproduction within the apomictically reproducing P. formosa. Overall expression of these genes seems to be down-regulated in the P. formosa transcriptome compared to both ancestral species (i.e., 106 genes down-regulated, 29 up-regulated). A further 35 meiosis and reproduction related genes were not found in the P. formosa transcriptome, but were only expressed in the sexual species. Our data support the hypothesis of general down-regulation of meiosis-related genes in the apomictic Amazon molly. Furthermore, the obtained dataset and identified gene catalog will serve as a resource for future research on the molecular mechanisms behind the reproductive mode of this unisexual species.
KW  - Differential gene expression
KW  - Gynogenesis
KW  - Hybrid speciation
KW  - Meiosis
KW  - Poecilia formosa
KW  - Poecilia latipinna
KW  - Poecilia mexicana
Y1  - 2018
U6  - https://doi.org/10.1186/s12864-017-4382-2
SN  - 1471-2164
VL  - 19
IS  - 12
SP  - 1
EP  - 18
PB  - BioMed Central
CY  - London
ER  -