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Daily behavioral and physiological rhythms are controlled by the brain’s circadian timekeeping system, a synchronized network of neurons that maintains endogenous molecular oscillations. These oscillations are based on transcriptional feedback loops of clock genes, which inDrosophilainclude the transcriptional activatorsClock (Clk)andcycle (cyc). While the mechanisms underlying this molecular clock are very well characterized, the roles that the core clock genes play in neuronal physiology and development are much less understood. TheDrosophilatimekeeping center is composed of ~150 clock neurons, among which the four small ventral lateral neurons (sLN_vs) are the most dominant pacemakers under constant conditions. Here, we show that downregulating the clock genecycspecifically in thePdf-expressing neurons leads to decreased fasciculation both in larval and adult brains. This effect is due to a developmental role ofcyc, as both knocking downcycor expressing a dominant negative form ofcycexclusively during development lead to defasciculation phenotypes in adult clock neurons.Clkdownregulation also leads to developmental effects on sLNv morphology. Our results reveal a non-circadian role forcyc, shedding light on the additional functions of circadian clock genes in the development of the nervous system. 

Abstract Background The incidence of tick-borne disease has increased dramatically in recent decades, with urban areas increasingly recognized as high-risk environments for exposure to infected ticks. Green spaces may play a key role in facilitating the invasion of ticks, hosts and pathogens into residential areas, particularly where they connect residential yards with larger natural areas (e.g. parks). However, the factors mediating tick distribution across heterogeneous urban landscapes remain poorly characterized. Methods Using generalized linear models in a multimodel inference framework, we determined the residential yard- and local landscape-level features associated with the presence of three tick species of current and growing public health importance in residential yards across Staten Island, a borough of New York City, in the state of New York, USA. Results The amount and configuration of canopy cover immediately surrounding residential yards was found to strongly predict the presence of Ixodes scapularis and Amblyomma americanum , but not that of Haemaphysalis longicornis . Within yards, we found a protective effect of fencing against I. scapularis and A. americanum, but not against H. longicornis . For all species, the presence of log and brush piles strongly increased the odds of finding ticks in yards. Conclusions The results highlight a considerable risk of tick exposure in residential yards in Staten Island and identify both yard- and landscape-level features associated with their distribution. In particular, the significance of log and brush piles for all three species supports recommendations for yard management as a means of reducing contact with ticks. Graphical Abstract 

Abstract The incidence of tick-borne diseases has increased in recent decades and accounts for the majority of vector-borne disease cases in temperate areas of Europe, North America, and Asia. This emergence has been attributed to multiple and interactive drivers including changes in climate, land use, abundance of key hosts, and people’s behaviors affecting the probability of human exposure to infected ticks. In this forum paper, we focus on how land use changes have shaped the eco-epidemiology of Ixodes scapularis-borne pathogens, in particular the Lyme disease spirochete Borrelia burgdorferi sensu stricto in the eastern United States. We use this as a model system, addressing other tick-borne disease systems as needed to illustrate patterns or processes. We first examine how land use interacts with abiotic conditions (microclimate) and biotic factors (e.g., host community composition) to influence the enzootic hazard, measured as the density of host-seeking I. scapularis nymphs infected with B. burgdorferi s.s. We then review the evidence of how specific landscape configuration, in particular forest fragmentation, influences the enzootic hazard and disease risk across spatial scales and urbanization levels. We emphasize the need for a dynamic understanding of landscapes based on tick and pathogen host movement and habitat use in relation to human resource provisioning. We propose a coupled natural-human systems framework for tick-borne diseases that accounts for the multiple interactions, nonlinearities and feedbacks in the system and conclude with a call for standardization of methodology and terminology to help integrate studies conducted at multiple scales.