Biology subjects

Klann, M.

Publications and source records attributed to Klann, M..

4 recordsLinked to original sources

bioRxiv2025

Cell-cell communication as underlying principle governing color pattern formation in fishes

The diverse pigmentation patterns of animals are crucial for predation avoidance and behavioral display, yet mechanisms underlying this diversity remain poorly understood. In zebrafish, Turing models have been proposed to explain stripe patterns, but it is unclear if they apply to other fishes. In anemonefish (Amphiprion ocellaris), we identified gja5b, a gene orthologous to zebrafish leopard and encoding a connexin involved in pigment cell communication, as responsible for the Snowflake phenotype. Using CRISPR/Cas9 and transgenesis, we recapitulate the Snowflake phenotype and show expression of gja5b in iridophores. A matching allele was recovered in zebrafish, revealing complementary requirements in both species. Our findings highlight conserved roles of gap junction mediated communication in pigment patterning across divergent teleosts.

developmental biology↗

bioRxiv2020

Sense organ formation and identity are controlled by divergent mechanisms in insects

Insects and other arthropods utilise external sensory structures for mechanosensory, olfactory and gustatory reception. These sense organs have characteristic shapes related to their function, and in many cases are distributed in a fixed pattern so that they are identifiable individually. In Drosophila melanogaster, the identity of sense organs is regulated by specific combinations of transcription factors. In other arthropods, however, sense organ subtypes cannot be linked to the same code of gene expression. This raises the questions of how sense organ diversity has evolved in arthropods, and if the D. melanogaster subtype identity principle is representative for insects. To address these questions, we analyse sense organ development in another insect, the flour beetle Tribolium castaneum. We show that in contrast to D. melanogaster, T. castaneum sense organs cannot be categorised based on their requirement for individual or combinations of the conserved sense organ transcription factors such as cut and pox-neuro and members of the Achaete-Scute (Tc ASH, Tc asense) and Atonal family (Tc atonal, Tc cato, Tc amos). Rather, these genes are required for the specification of sense organ precursors and the development and differentiation of sensory cell types in diverse external sensilla. Based on our findings and past research, we present an evolutionary scenario suggesting that sensory organs have diversified from a default state through subsequent recruitment of sensory genes to the different sense organ specification processes. A specific role for genes in subtype identity has evolved as a secondary effect of the function of these genes in individual or subsets of sense organs, which can largely not be aligned with morphological or functional categories.

evolutionary biology↗

bioRxiv2020

microRNA-dependent control of sensory neuron function regulates posture behaviour in Drosophila

All what we see, touch, hear, taste or smell must first be detected by the sensory elements in our nervous system. Sensory neurons, therefore, represent a critical component in all neural circuits and their correct function is essential for the generation of behaviour and adaptation to the environment. Here we report that a gene encoding the evolutionarily conserved microRNA (miRNA) miR-263b, plays a key behavioural role in Drosophila through effects on the function of larval sensory neurons. Several independent experiments support this finding. First, miRNA expression analysis by means of a miR-263b reporter line, and fluorescent-activated cell sorting coupled to quantitative PCR, both demonstrate expression of miR-263b in Drosophila larval sensory neurons. Second, behavioural tests in miR-263b null mutants show defects in self-righting: an innate and evolutionarily conserved posture control behaviour that allows the larva to return to its normal position if turned upside-down. Third, competitive inhibition of miR-263b in sensory neurons using a miR-263b sponge leads to self-righting defects. Fourth, systematic analysis of sensory neurons in miR-263b mutants shows no detectable morphological defects in their stereotypic pattern. Fifth, genetically-encoded calcium sensors expressed in the sensory domain reveal a reduction in neural activity in miR-263b null mutants. Sixth, miR-263b null mutants show a reduced touch-response behaviour and a compromised response to sound, both characteristic of larval sensory deficits. Furthermore, bioinformatic miRNA target analysis, gene expression assays, and behavioural phenocopy experiments suggest that miR-263b might exert its effects - at least in part - through repression of the bHLH transcription factor atonal. Altogether, our study suggests a model in which miRNA-dependent control of transcription factor expression affects sensory function and behaviour. Building on the evolutionary conservation of miR-263b, we propose that similar processes may modulate sensory function in other animals, including mammals.

neuroscience↗

bioRxiv2018

Functional role of pax6 in eye and central nervous system development in the annelid Capitella teleta

The transcription factor Pax6 is an important regulator of early animal development. Loss of function mutations of pax6 in a range of animals results in a reduction or complete loss of the eye, a reduction of a subset of neurons, and defects in axon growth. There are no studies focusing on the role of pax6 during development of any lophotrochozoan representative, however, expression of pax6 in the developing eye and nervous system in a number of species suggest that pax6 plays a highly conserved role in eye and nervous system formation. We investigated the functional role of pax6 during development of the marine annelid Capitella teleta. Expression of pax6 transcripts in C. teleta larvae is similar to patterns found in other animals, with distinct subdomains in the brain and ventral nerve cord as well as in the larval and adult eye. To perturb pax6 function, two different splice-blocking morpholinos were used. Larvae resulting from injections with either morpholino show a reduction of the pax6 transcript, and development of both the larval eyes and the central nervous system architecture are highly disrupted. Preliminary downstream target analysis confirms disruption in expression of some components of the retinal gene regulatory network, as well as disruption of genes involved in nervous system development. Results from this study, taken together with studies from other species, reveal an evolutionarily conserved role for pax6 in eye development, and in neural specification and development.

developmental biology↗