Digoxigenin [KLH]

Objective. Joint pain is the major clinical symptom of arthritis that affects millions of people. Controlling the excitability of knee-innervating dorsal root ganglion (DRG) neurons (knee neurons) could potentially provide pain relief. We undertook this study to evaluate whether the newly engineered adeno-associated virus (AAV) serotype, AAV-PHP.S, can deliver functional artificial receptors to control knee neuron excitability following intraarticular knee injection. Methods. The AAV-PHP.S virus, packaged with dTomato fluorescent protein and either excitatory (G(q)) or inhibitory (G(i)) designer receptors exclusively activated by designer drugs (DREADDs), was injected into the knee joints of adult mice. Labeling of DRG neurons with AAV-PHP.S from the knee was evaluated using immunohistochemistry. The functionality of G(q)- and G(i)-DREADDs was evaluated using whole-cell patch clamp electrophysiology on acutely cultured DRG neurons. Pain behavior in mice was assessed using a digging assay, dynamic weight bearing, and rotarod performance, before and after intraperitoneal administration of the DREADD activator, Compound 21. Results. We showed that AAV-PHP.S can deliver functional genes into similar to 7% of lumbar DRG neurons when injected into the knee joint in a similar manner to the well-established retrograde tracer, fast blue. Short-term activation of AAV-PHP.S-delivered G(q)-DREADD increased excitability of knee neurons in vitro (P = 0.02 by unpaired t-test), without inducing overt pain in mice when activated in vivo. By contrast, in vivo G(i)-DREADD activation alleviated digging deficits induced by Freund's complete adjuvant-mediated knee inflammation (P = 0.0002 by repeated-measures analysis of variance [ANOVA] followed by Holm-Sidak multiple comparisons test). A concomitant decrease in knee neuron excitability was observed in vitro (P = 0.005 by ANOVA followed by Holm-Sidak multiple comparisons test). Conclusion. We describe an AAV-mediated chemogenetic approach to specifically control joint pain, which may be utilized in translational arthritic pain research.

The weight of post-flight ant queens reflects how much stored resources are available to overpass the new colony foundation phase.Acromyrmexqueens must dig the nest and forage during this period to cultivate the symbiotic fungus for larvae feeding, implying even higher energetic costs. But if the activities of foraging and excavating were excluded from this phase, would it be possible to mitigate the effect of the queen's post-flight weight on its survival and productivity? In this context, we tracked the survival of 1128 queens already classified into Featherweight, Lightweight, Welterweight and Heavyweight until the emergence of the first workers. Also, for 476 queens we registered the productivity, the proportion of queens that regurgitated the symbiotic fungus, of those that transported it to leaf surface, as well as the proportion that presented some pathogenic fungus on their body surface after death. After the 2nd week, 45% of queens had died and the post-flight weight influenced survival chances, with featherweight queens presenting the highest mortality rate but not the lowest productivity. Here we add the queen's post-flight weight, the absence of symbiotic fungus and, less remarkably, the contamination by pathogenic fungus as other variables that should likewise be considered as factors that reduce the success rate of colony foundation. We highlight that the post-flight weight did not influence the productivity, so when the queen survives, the offspring production is not affected, giving queens of different weights the same chance to become successful at colony foundation.