CRISPR-Cas9 targeted disruption of the yellow ortholog in the housefly identifies the brown body locus

ABSTRACTThe classic brown body (bwb) mutation in the housefly Musca domestica impairs normal melanization of the adult cuticle. In Drosophila melanogaster, a reminiscent pigmentation defect results from mutations in the yellow gene encoding dopachrome conversion enzyme (DCE). Here, we demonstrate that the bwb locus structurally and functionally represents the yellow ortholog of Musca domestica, MdY. In bwb Musca strains, we identified two mutant MdY alleles that contain lesions predicted to result in premature truncation of the MdY open reading frame. We targeted wildtype MdY by CRISPR-Cas9 RNPs and generated new mutant alleles that fail to complement existing MdY alleles, genetically confirming that MdY is the bwb locus. We further found evidence for Cas9-mediated interchromosomal recombination between wildtype and mutant bwb alleles. Our work resolves the molecular identity of the classic bwb mutation in Musca domestica and establishes the feasibility of Cas9-mediated genome editing in the Musca model.

The Effects of Stimulation of Ear Acupuncture Points on the Body's Pain Threshold

Six ear acupuncture points, one non-acupuncture ear point, and the body locus Ho-Ku (LI-4) were electrically stimulated in order to compare the effects of stimulation on the body's pain threshold at selected loci on various points on the body by measurement with a radiation heat-type Pain Meter on 5 subjects. The ear points, with the exception of the non-acupuncture ear point, were found to be effective even in peripheral body regions in varying degrees. Ear stimulation did not increase the threshold as rapidly as Ho-Ku. In all cases where the pain threshold was raised, the effect persisted after electrical stimulation had stopped.

Body Locus and Form Perception

Forms were drawn on the palms, forearms, or biceps of 42 subjects, with vision excluded. Subjects were then required to make a visual match to the drawn forms. It was expected that the accuracy of form recognition would be a direct function of the sensitivity of the receptor surface. Thus the palm was expected to yield more accurate form recognition than the forearm or bicep. Form recognition was significantly worse on the forearm than on other skin locations. The adequacy of a skin surface as an information transducer does not appear to be a simple function of cutaneous sensitivity since there was no significant difference in the accuracy of form recognition between the palm and bicep.

Tactile Pattern Recognition and Body Loci

Experimentation was conducted to compare tactile pattern recognition on three body loci—back, abdomen, and inner thigh. Five blind subjects, experienced users of a tactile vision substitution system which displays images picked up by a television camera through patterns of vibratory stimulation on the skin, were asked to identify letter images displayed on three body regions. Though the previous experience had been limited to stimulation on the back, recognition accuracy and latency were significantly better on the abdomen. The results indicate that immediate transfer of previous learning occurs when body locus of stimulation is shifted, and further suggest that neural networks for tactile pattern recognition do not include specific peripheral neural receptors.