02556nas a2200277 4500008004100000022002500041245011800066210006900184260001600253300001000269490000800279520169400287653002801981653001302009653002002022653002602042653002602068653001302094100001702107700002102124700002302145700001902168700002102187700002202208856004802230 2016 eng d a0378-1909, 1573-513300aReproduction and development in some species of the weakly electric genus Campylomormyrus (Mormyridae, Teleostei)0 aReproduction and development in some species of the weakly elect cDec-07-2016 a49-680 v1003 a

Reproduction in captivity of four species of the mormyrid genus Campylomormyrus was investigated. Cyclical reproduction was provoked by changing water conductivity (C) alone: decreasing C led to gonadal recrudescence, an increase induced gonad regression. Data on the reproduction and development of three species are presented. All three species are indeterminate fractional spawners. Spawning intervals ranged from 6 to 66 days in C. rhynchophorus, 10–75 days in C. tshokwe, and 18 days in C. compressirostris (calculated values). Fecundities (eggs per fractional spawning) ranged from 70 to 1570 eggs in C. rhynchophorus, 100–1192 in C. tshokwe, and 38–246 in C. compressirostris. Spawnings/ovipositions occurred during the second half of the night; no parental care was observed; no special spawning substrates were necessary. C. compressirostris successfully spawned in breeding groups, C. rhynchophorus as pair. Agonistic behavior in the C. tshokwe pair forced us to divide the breeding tank; therefore, only ovipositions occurred. However, injection of an artificial GnRH hormone allowed us to obtain ripe eggs and sperm and to perform successful artificial reproduction. All three species produce yolky, slightly sticky eggs. Egg diameter ranges from 2.3–3.0 mm. Hatching occurred on day 3, feeding started on day 11. Transition from larval to juvenile stage occurred at around 20 mm total length (TL). At this size C. rhynchophorus developed a higher body than the two other species and differences between the species in the melanin pigmentation of the unpaired fins occurred. Between 32 and 35 mm TL the upper and lower jaws started to elongate.

10aArtificial reproduction10aBehavior10aCampylomormyrus10aCyclical reproduction10aEnvironmental factors10aOntogeny1 aNguyen, Linh1 aPaul, Christiane1 aMamonekene, Victor1 aBartsch, Peter1 aTiedemann, Ralph1 aKirschbaum, Frank uhttp://dx.doi.org/10.1007/s10641-016-0554-102056nas a2200265 4500008004100000022001300041245015000054210006900204260001600273520114000289653002001429653002801449653002001477653001501497653002801512653002501540100002301565700002201588700002201610700002701632700002301659700002101682700002101703856006601724 2016 eng d a1055790300aSpecies delimitation and phylogenetic relationships in a genus of African weakly-electric fishes (Osteoglossiformes, Mormyridae, Campylomormyrus)0 aSpecies delimitation and phylogenetic relationships in a genus o cJan-04-20163 a

African weakly-electric fishes (Mormyridae) are able to communicate through species-specific electric signals; this feature might have favoured the evolutionary radiation observed in this family (over 200 species) by acting as an effective pre-zygotic isolation mechanism. In the present study we used mitochondrial (cytb) and nuclear (rps7, scn4aa) markers in order to reconstruct a species-phylogeny and identify species boundaries for the genus Campylomormyrus, by applying inference methods based on the multispecies coalescent model. Additionally, we employed 16 microsatellite markers, landmark-based morphometric measurements, and electro-physiological analyses as independent lines of evidence to the results obtained from the sequence data. The results show that groups that are morphologically different are also significantly divergent at the genetic level, whereas morphologically similar groups, displaying dissimilar electric signals, do not show enough genetic diversity to be considered separate species. Furthermore, the data confirm the presence of a yet undescribed species within the genus Campylomormyrus.

10aCampylomormyrus10aGeometric morphometrics10aMicrosatellites10aMormyridae10aMultispecies-coalescent10aSpecies-delimitation1 aLamanna, Francesco1 aKirschbaum, Frank1 aErnst, Anja, R.R.1 aFeulner, Philine, G.D.1 aMamonekene, Victor1 aPaul, Christiane1 aTiedemann, Ralph uhttp://linkinghub.elsevier.com/retrieve/pii/S105579031630078103057nas a2200169 4500008004100000245015700041210006900198260001600267490000700283520243400290100002302724700002202747700002202769700002502791700002102816856005002837 2015 eng d00aCross-tissue and cross-species analysis of gene expression in skeletal muscle and electric organ of African weakly-electric fish (Teleostei; Mormyridae)0 aCrosstissue and crossspecies analysis of gene expression in skel cJan-12-20150 v163 a

Background: African weakly-electric fishes of the family Mormyridae are able to produce and perceive weak electric signals (typically less than one volt in amplitude) owing to the presence of a specialized, muscle-derived electric organ (EO) in their tail region. Such electric signals, also known as Electric Organ Discharges (EODs), are used for objects/prey localization, for the identification of conspecifics, and in social and reproductive behaviour. This feature might have promoted the adaptive radiation of this family by acting as an effective pre-zygotic isolation mechanism. Despite the physiological and evolutionary importance of this trait, the investigation of the genetic basis of its function and modification has so far remained limited. In this study, we aim at: i) identifying constitutive differences in terms of gene expression between electric organ and skeletal muscle (SM) in two mormyrid species of the genus Campylomormyrus: C. compressirostris and C. tshokwe, and ii) exploring cross-specific patterns of gene expression within the two tissues among C. compressirostris, C. tshokwe, and the outgroup species Gnathonemus petersii.
Results: Twelve paired-end (100 bp) strand-specific RNA-seq Illumina libraries were sequenced, producing circa 330 M quality-filtered short read pairs. The obtained reads were assembled de novo into four reference transcriptomes. In silico cross-tissue DE-analysis allowed us to identify 271 shared differentially expressed genes between EO and SM in C. compressirostris and C.tshokwe. Many of these genes correspond to myogenic factors, ion channels and pumps, and genes involved in several metabolic pathways. Cross-species analysis has revealed that the electric organ transcriptome is more variable in terms of gene expression levels across species than the skeletal muscle transcriptome.
Conclusions: The data obtained indicate that: i) the loss of contractile activity and the decoupling of the excitation-contraction processes are reflected by the down-regulation of the corresponding genes in the electric organ’s transcriptome; ii) the metabolic activity of the EO might be specialized towards the production and turn-over of membrane structures; iii) several ion channels are highly expressed in the EO in order to increase excitability; iv) several myogenic factors might be down-regulated by transcription repressors in the EO.

1 aLamanna, Francesco1 aKirschbaum, Frank1 aWaurick, Isabelle1 aDieterich, Christoph1 aTiedemann, Ralph uhttp://www.biomedcentral.com/1471-2164/16/668