@article {68117, title = {An essential experimental control for functional connectivity mapping with optogenetics.}, journal = {bioRxiv}, year = {2022}, month = {2022 May 28}, abstract = {

To establish functional connectivity between two candidate neurons that might form a circuit element, a common approach is to activate an optogenetic tool such as Chrimson in the candidate pre-synaptic neuron and monitor fluorescence of the calcium-sensitive indicator GCaMP in a candidate post-synaptic neuron. While performing such experiments, we found that low levels of leaky Chrimson expression can lead to strong artifactual GCaMP signals in presumptive postsynaptic neurons even when Chrimson is not intentionally expressed in any particular neurons. Withholding all-trans\ retinal, the chromophore required as a co-factor for Chrimson response to light, eliminates GCaMP signal but does not provide an experimental control for leaky Chrimson expression. Leaky Chrimson expression appears to be an inherent feature of current Chrimson transgenes, since artifactual connectivity was detected with Chrimson transgenes integrated into three different genomic locations (two insertions tested in larvae; a third insertion tested in the adult fly). These false-positive signals may complicate the interpretation of functional connectivity experiments. We illustrate how a no-Gal4 negative control improves interpretability of functional connectivity assays. We also propose a simple but effective procedure to identify experimental conditions that minimize potentially incorrect interpretations caused by leaky Chrimson expression.

}, doi = {10.1101/2022.05.26.493610}, url = {https://doi.org/10.1101/2022.05.26.493610}, author = {David Tadres and Hiroshi M. Shiozaki and Ibrahim Tastekin and David L. Stern and Matthieu Louis} } @article {45807, title = {The evolution of sociality in aphids: a clone{\textquoteright}s-eye view}, journal = {The evolution of social behavior in insects and arachnids.}, year = {1997}, month = {03/1997}, pages = {150-165}, abstract = {

A number of aphid species produce individuals, termed soldiers, that defend the colony by attacking predators. Soldiers have either reduced or zero direct reproductive fitness. Their behavior is therefore altruistic in the classical sense: an individual is behaving in a way that incurs reproductive costs on itself and confers reproductive benefits on another. However, comparison with the better{\textendash}known eusocial insects (Hymenoptera, Isoptera) indicates that there are important differences between clonal and sexual social animals.

Here we take a clone{\textquoteright}s{\textendash}eye view and conclude that many facets of aphid sociality are best thought of in terms of resource allocation: for example, the choice between investment in defense and reproduction. This view considerably simplifies some aspects of the problem and highlights the qualitatively different nature of genetic heterogeneity in colonies of aphids and of other social insects. In sexually reproducing social insects, each individual usually has a different genome, which leads to genetic conflicts of interest between individuals. In social aphids, all members of a clone have identical genomes, barring new mutations, and there should be no disagreement among clonemates about investment decisions. Genetic heterogeneity within colonies can arise, but principally through clonal mixing, and this means that investment decisions will vary between different clones rather than among all individuals.

}, isbn = {9780511721953}, doi = {10.1017/CBO9780511721953.008}, url = {http://ebooks.cambridge.org/chapter.jsf?bid=CBO9780511721953\&cid=CBO9780511721953A015}, author = {David L. Stern and William A. Foster} }