TY  - JOUR
A1  - Dedukh, Dmitrij
A1  - Da Cruz, Irene
A1  - Kneitz, Susanne
A1  - Marta, Anatolie
A1  - Ormanns, Jenny
A1  - Tichopád, Tomáš
A1  - Lu, Yuan
A1  - Alsheimer, Manfred
A1  - Janko, Karel
A1  - Schartl, Manfred
T1  - Achiasmatic meiosis in the unisexual Amazon molly, Poecilia formosa
JF  - Chromosome Research
N2  - Unisexual reproduction, which generates clonal offspring, is an alternative strategy to sexual breeding and occurs even in vertebrates. A wide range of non-sexual reproductive modes have been described, and one of the least understood questions is how such pathways emerged and how they mechanistically proceed. The Amazon molly, Poecilia formosa, needs sperm from males of related species to trigger the parthenogenetic development of diploid eggs. However, the mechanism, of how the unreduced female gametes are produced, remains unclear. Cytological analyses revealed that the chromosomes of primary oocytes initiate pachytene but do not proceed to bivalent formation and meiotic crossovers. Comparing ovary transcriptomes of P. formosa and its sexual parental species revealed expression levels of meiosis-specific genes deviating from P. mexicana but not from P. latipinna. Furthermore, several meiosis genes show biased expression towards one of the two alleles from the parental genomes. We infer from our data that in the Amazon molly diploid oocytes are generated by apomixis due to a failure in the synapsis of homologous chromosomes. The fact that this failure is not reflected in the differential expression of known meiosis genes suggests the underlying molecular mechanism may be dysregulation on the protein level or misexpression of a so far unknown meiosis gene, and/or hybrid dysgenesis because of compromised interaction of proteins from diverged genomes.
KW  - meiosis
KW  - parthenogenesis
KW  - synaptonemal complex
KW  - recombination
KW  - crossing-over
KW  - achiasmatic
KW  - transcriptome
KW  - oogenesis
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-325128
VL  - 30
IS  - 4
ER  - 
TY  - JOUR
A1  - Liu, Ruiqi
A1  - Friedrich, Mike
A1  - Hemmen, Katherina
A1  - Jansen, Kerstin
A1  - Adolfi, Mateus C.
A1  - Schartl, Manfred
A1  - Heinze, Katrin G.
T1  - Dimerization of melanocortin 4 receptor controls puberty onset and body size polymorphism
JF  - Frontiers in Endocrinology
N2  - Xiphophorus fish exhibit a clear phenotypic polymorphism in puberty onset and reproductive strategies of males. In X. nigrensis and X. multilineatus, puberty onset is genetically determined and linked to a melanocortin 4 receptor (Mc4r) polymorphism of wild-type and mutant alleles on the sex chromosomes. We hypothesized that Mc4r mutant alleles act on wild-type alleles by a dominant negative effect through receptor dimerization, leading to differential intracellular signaling and effector gene activation. Depending on signaling strength, the onset of puberty either occurs early or is delayed. Here, we show by Förster Resonance Energy Transfer (FRET) that wild-type Xiphophorus Mc4r monomers can form homodimers, but also heterodimers with mutant receptors resulting in compromised signaling which explains the reduced Mc4r signaling in large males. Thus, hetero- vs. homo- dimerization seems to be the key molecular mechanism for the polymorphism in puberty onset and body size in male fish.
KW  - fluorescence lifetime imaging microscopy
KW  - Förster Resonance Energy Transfer
KW  - Mc4r
KW  - puberty
KW  - Xiphophorus
Y1  - 2023
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-354261
SN  - 1664-2392
VL  - 14
ER  -