Salinity reduction benefits European eel larvae: Insights at the morphological and molecular level

European eel (Anguilla anguilla) is a euryhaline species, that has adapted to cope with both, hyper- and hypo-osmotic environments. This study investigates the effect of salinity, from a morphological and molecular point of view on European eel larvae reared from 0 to 12 days post hatch (dph). Offspring reared in 36 practical salinity units (psu; control), were compared with larvae reared in six scenarios, where salinity was decreased on 0 or 3 dph and in rates of 1, 2 or 4 psu/day, towards iso-osmotic conditions. Results showed that several genes relating to osmoregulation (nkcc2α, nkcc2β, aqp1dup, aqpe), stress response (hsp70, hsp90), and thyroid metabolism (thrαA, thrαB, thrβB, dio1, dio2, dio3) were differentially expressed throughout larval development, while nkcc1α, nkcc2β, aqp3, aqp1dup, aqpe, hsp90, thrαA and dio3 showed lower expression in response to the salinity reduction. Moreover, larvae were able to keep energy metabolism related gene expression (atp6, cox1) at stable levels, irrespective of the salinity reduction. As such, when reducing salinity, an energy surplus associated to reduced osmoregulation demands and stress (lower nkcc, aqp and hsp expression), likely facilitated the observed increased survival, improved biometry and enhanced growth efficiency. Additionally, the salinity reduction decreased the amount of severe deformities such as spinal curvature and emaciation but also induced an edematous state of the larval heart, resulting in the most balanced mortality/deformity ratio when salinity was decreased on 3 dph and at 2 psu/day. However, the persistency of the pericardial edema and if or how it represents an obstacle in further larval development needs to be further clarified. In conclusion, this study clearly showed that salinity reduction regimes towards iso-osmotic conditions facilitated the European eel pre-leptocephalus development and revealed the existence of highly sensitive and regulated osmoregulation processes at such early life stage of this species

Cleaner wrasse indirectly affect the cognitive performance of a damselfish through ectoparasite removal

Cleaning organisms play a fundamental ecological role by removing ectoparasites and infected tissue from client surfaces. We used the well-studied cleaning mutualisms involving the cleaner wrasse, Labroides dimidiatus, to test how client cognition is affected by ectoparasites and whether these effects are mitigated by cleaners. Ambon damselfish (Pomacentrus amboinensis) collected from experimental reef patches without cleaner wrasse performed worse in a visual discrimination test than conspecifics from patches with cleaners. Endoparasite abundance also negatively influenced success in this test. Visual discrimination performance was also impaired in damselfish experimentally infected with gnathiid (Crustacea: Isopoda) ectoparasites. Neither cleaner absence nor gnathiid infection affected performance in spatial recognition or reversal learning tests. Injection with immune-stimulating lipopolysaccharide did not affect visual discrimination performance relative to saline-injected controls suggesting that cognitive impairments are not due to an innate immune response. Our results highlight the complex, indirect role of cleaning organisms in promoting the health of their clients via ectoparasite removal and emphasize the negative impact of parasites on host’s cognitive abilities

Letztere Freundes Pflicht Welche Bey dem seeligen Ableben Herrn Heinrich August Töpffers, Pastoris an der Kirchen zur H. Dreyeinigkeit auch Prof. publ. Theol. Ev. Luther. und Metaphysices am Hochfürstl. Anhaltischen Gesamt Gymnasio Seines ... Schwagers Am Tage Seiner Leichen- und Gedächtniß-Predigt Mit betrübtesten Hertzen und Worten abstatten sollen M. Johann George Junack, Erb- und Gerichts-Herr zu Görtzke, auch Pastor zu Eichholtz

Autopsie nach Ex. der ULB Sachsen-AnhaltVorlageform des Erscheinungsvermerks: Zerbst Gedruckt bey Gottfried Heinrich Bernuthen, Hochfürstl. Anhaltzerbstischen Hofundregierungsbuchdrucker

Sex steroid dynamics and mRNA transcript profiles of growth- and development-related genes during embryogenesis following induced follicular maturation in European eel

Hormones and mRNA transcripts of maternal origin deposited in the egg may affect early embryonic development in oviparous species. These hormones include steroids, such as estradiol-17β (E2), testosterone (T), 11-ketotestosterone (11-kt), 17α,20ß-dihydroxy-4-pregnen-3-one (DHP), and cortisol, which also play an important role in fish reproduction. In European eel, Anguilla anguilla, which does not reproduce naturally in captivity, vitellogenesis in female broodstock is commonly induced by administration of salmon or carp pituitary extract (PE) as an exogenous source of gonadotropins, while follicular maturation is stimulated by a priming dose of PE followed by provision of DHP as a maturation inducing hormone. In this regard, the main purpose of the present study was to evaluate effects of induced follicular maturation on reproductive success in European eel, focusing on maternal transfer and dynamics of steroids and mRNA transcripts of growth- and development-related genes throughout embryogenesis. The results showed that maternal blood plasma concentrations of E2, T and DHP were reflected in the unfertilized eggs. Moreover, a negative relationship between concentrations of E2 and DHP in eggs and embryos and quality parameters measured as fertilization success, cleavage abnormalities, embryonic survival, and hatch success was found. Concomitant mRNA transcript abundance analysis including genes involved in stress response (hsp70, hsp90), somatotropic axis (gh, igf1, igf2a, igf2b), lipid (cpt1a, cpt1b, pigf5) and thyroid metabolism (dio1, dio2, dio3, thrαb, thrβa, thrβb) varied among unfertilized egg batches. For the majority of genes, mRNA abundance increased during the maternal-to-zygotic transition in connection to activation of the transcription of the embryos own genome. mRNA abundance of dio1, cpt1a and cpt1b throughout embryogenesis was related to embryonic developmental competence. Notably, mRNA abundance of dio3 was positively associated with E2 concentrations, while the mRNA abundance of thrαb was negatively related to T concentrations in the unfertilized eggs, which may suggest an interaction between the thyroid and steroid hormone systems. Altogether, maternal plasma concentrations of E2 and DHP were reflected in the eggs, with high concentrations of these steroids in the eggs being negatively associated with embryonic developmental competence. Additionally, high transcript levels of two of the investigated genes (dio1, cpt1b) were positively associated with embryonic developmental competence. This study reveals maternal transfer of steroids and mRNA transcripts to the eggs, which may be significant contributors to the variability in embryonic survival observed in European eel captive reproduction

Trauriges Denckmahl, Welches zu Ehren Der Weyland Hoch-Edlen, Hochachtbaren Viel- Ehr- und Tugendbegabten Frauen, Frauen Johannen Magdalenen, gebohrnen Müllerin, Des Tit. Hochwürdigen, Magnifici und Hochgelahrten Herrn, Herrn Andreä Töpffers, Der Heil. Schrifft Hochberühmten Doctoris, Sr. Hoch-Fürstl. Durchl. zu Anhalt-Zerbst Hochverordneten Consistorial-und Kirchen-Raths, Hochbetrauten Ober-Hof-Predigers und Beicht-Vaters, der Kirchen zu St. Barthol. Hochverdienten Past. Prim. und der Anhalt-Zerbstischen Diœces Hochansehnl. Superintendentens, hertzlich-geliebtesten Frau Ehe-Liebsten, Nachdem Dieselbe den 5. Nov. A. 1720. ... verschieden, und darauf den 10. dieses zu Ihrer Ruhe-Stäte gebracht wurde, In hertzlicher Betrübniß und ergebenster Schuldigkeit aufrichten wollen Ihro Hochwürdigen Magnificence gehorsamste Diener, M. Lebrecht Gottlieb Bühlau, George Christoph Croll, M. Johann George Junack, Minist. Candd.

Gedächtnisgedicht auf Johanna Magdalena Töpffer, geb. Müller, +5. Nov. 1720Vorlageform des Erscheinungsvermerks: Zerbst, druckts Samuel Tietze, Hoch-Fürstl. Anh. Hof- und Regier. Buchdrucker