Maria Paz Fernandez

Barnard College of Columbia University · Neuroscience and Behavior

Human generated environmental change profoundly affects organisms that reside across diverse ecosystems. Although nervous systems evolved to flexibly sense, respond, and adapt to environmental change, it is unclear whether the rapid rate of environmental change outpaces the adaptive capacity of complex nervous systems. Here, we explore neural syste...

Daily behavioral and physiological rhythms are controlled by the 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 in Drosophila include the transcriptional activators Clock (Clk) and cycle (cyc). Whil...

Inhibitors of enzymes that inactivate amine neurotransmitters (dopamine, serotonin), such as catechol-O-methyltransferase (COMT) and monoamine oxidase (MAO), are thought to increase neurotransmitter levels and are widely used to treat Parkinson's disease and psychiatric disorders, yet the role of these enzymes in regulating behavior remains unclear...

Aggression is an innate behavior that likely evolved in the framework of defending or obtaining resources. This complex social behavior is influenced by genetic, environmental, and internal factors. Drosophila melanogaster remains an effective and exciting model organism with which to unravel the mechanistic basis of aggression due to its small but...

Here, we highlight three different assays that are used to study Drosophila aggression. The advantages and disadvantages of each assay are discussed, as examining different aspects of aggressive behavior presents distinct challenges to researchers. This is because aggression is not a singular behavioral unit. Rather, aggression is the result of int...

The circadian clock orchestrates daily changes in physiology and behavior to ensure internal temporal order and optimal timing across the day. In animals, a central brain clock coordinates circadian rhythms throughout the body and is characterized by a remarkable robustness that depends on synaptic connections between constituent neurons. The clock...

The problem of entrainment is central to circadian biology. In this regard, Drosophila has been an important model system. Owing to the simplicity of its nervous system and the availability of powerful genetic tools, the system has shed significant light on the molecular and neural underpinnings of entrainment. However, much remains to be learned r...

Peripheral sensory neurons are the gateway to the environment across species. In Drosophila, olfactory and gustatory senses are required to initiate courtship, as well as for the escalation of courtship patterns that lead to copulation. To be successful, copulation must last long enough to ensure the transfer of sperm and seminal fluid that ultimat...

The circadian clock orchestrates daily changes in physiology and behavior to ensure internal temporal order and optimal timing across the day. In animals, a central brain clock orchestrates circadian rhythms throughout the body and is characterized by a remarkable resilience that depends on synaptic connections between constituent neurons. The cloc...

The problem of entrainment is central to circadian biology. In this regard, Drosophila has been an important model system. Owing to the simplicity of its nervous system and the availability of powerful genetic tools, the system has shed significant light on the molecular and neural underpinnings of entrainment. However, much remains to be learned r...

Peripheral sensory neurons are the gateway to the environment across species. In Drosophila , olfactory and gustatory senses are required to initiate courtship, as well as for the escalation of courtship patterns that lead to copulation. To be successful, copulation must last long enough to ensure the transfer of sperm and seminal fluid that ultima...

Aggressive behavior is thought to have evolved as a strategy for gaining access to resources such as territory, food, and potential mates. Across species, secondary sexual characteristics such as competitive aggression and territoriality are considered male-specific behaviors. However, although female–female aggression is often a behavior that is d...

This protocol describes a standardized method for analyzing Drosophila behavioral rhythmicity under light dark cycles, temperature ramps, and free running conditions. The protocol constitutes a step-by-step guide from generation of appropriate Drosophila genetic crosses to behavioral experiments. We also provide an open-source computational framewo...

Many animal species show aggression to gain mating partners and to protect territories and other resources from competitors. Both male and female fruit flies of the species Drosophila melanogaster exhibit aggression in same-sex pairings, but the strategies used are sexually dimorphic. We have begun to explore the biological basis for the differing...

In competition for food, mates and territory, most animal species display aggressive behavior through visual threats and/or physical attacks. Such naturally-complex social behaviors have been shaped by evolution. Environmental pressure, such as the one imposed by dietary regimes, forces animals to adapt to specific conditions and ultimately to deve...

Networks of circadian timekeeping in the brain display marked daily changes in neuronal morphology. In Drosophila melanogaster, the striking daily structural remodeling of the dorsal medial termini of the small ventral lateral neurons has long been hypothesized to mediate endogenous circadian timekeeping. To test this model, we have specifically ab...

Networks of circadian timekeeping in the brain display marked daily changes in neuronal morphology. In Drosophila melanogaster, the striking daily structural remodeling of the dorsal medial termini of the small ventral lateral neurons has long been hypothesized to mediate endogenous circadian timekeeping. To test this model, we have specifically ab...

Male courtship in Drosophila melanogaster is a sexually dimorphic innate behavior that is hardwired in the nervous system. Understanding the neural mechanism of courtship behavior requires the anatomical and functional characterization of all the neurons involved. Courtship involves a series of distinctive behavioral patterns, culminating in the fi...

Aggression is used by essentially all species of animals to gain access to desired resources, including territory, food, and potential mates: Fruit flies are no exception. In Drosophila, both males and females compete in same sex fights for resources, but only males establish hierarchical relationships. Many investigators now study aggression using...

Monoamine serotonin (5HT) has been linked to aggression for many years across species [1-3]. However, elaboration of the neurochemical pathways that govern aggression has proven difficult because monoaminergic neurons also regulate other behaviors [4, 5]. There are approximately 100 serotonergic neurons in the Drosophila nervous system, and they in...

Chemosensory pheromonal information regulates aggression and reproduction in many species, but how pheromonal signals are transduced to reliably produce behavior is not well understood. Here we demonstrate that the pheromonal signals detected by Gr32a-expressing chemosensory neurons to enhance male aggression are filtered through octopamine (OA, in...

Upon encountering a conspecific in the wild, males have to rapidly detect, integrate and process the most relevant signals to evoke an appropriate behavioral response. Courtship and aggression are the most important social behaviors in nature for procreation and survival: for males, making the right choice between the two depends on the ability to...

Appropriate displays of aggression rely on the ability to recognize potential competitors. As in most species, Drosophila males fight with other males and do not attack females. In insects, sex recognition is strongly dependent on chemosensory communication, mediated by cuticular hydrocarbons acting as pheromones. While the roles of chemical and ot...

Synchronized flies were examined in the automated behavioral paradigm, as explained in the legend to Table S1. The table includes all the experiments described in Figures 3 and 5. (0.05 MB DOC)

Frontal adult head semi-thin sections (1 µm thick) were stained with methylene blue and examined by light microscopy. Representative sections are included. Young (0–3 day old) and old (30 day old) flies were analyzed for each genotype. Heterozygous enarev flies show no signs of degeneration throughout adulthood. The C309 driver was employed to redu...

Progressive degeneration in elav>enarev individuals does not result in an impaired climbing ability. In a longitudinal assay the geotactic response of flies of the indicated genotypes was examined. The performance in this paradigm decreased as the flies aged for all genotypes; no significant differences were observed between elav>enarev and control...

Flies were entrained to 12∶12h LD cycles for 4 days and then released into DD. Free-running behavior was monitored for 10 additional days. Period values were determined using Clocklab employing Chi-Squared periodogram analysis taking into account only rhythmic individuals. The age and number (n) of flies are indicated for each genotype. Percentage...

Author Summary Circadian systems evolved as a mechanism that allows organisms to adapt to the environmental changes in light and dark which occur as a consequence of the rotation of Earth. Because of its unique repertoire of genetic tools, Drosophila is a well established model for the study of the circadian clock. Although the biochemical compone...

Axonal Arborizations of Small LNvs Extend Mostly in the Latero-Medial and Dorso-Ventral Axis 3-D reconstructions were analyzed to rule out the possible contribution of significant branching in the antero-posterior direction. All of the images included throughout the manuscript are contained within the x–y projections (x-axis, latero-medial; y-axis,...

Structural Plasticity Persists in Older Male and Female Flies Left panel: Representative confocal images of pdf>mCD8-GFP male and female brains, from six day-old (A) or 12 day-old (B) flies, are shown. Flies were fixed and dissected at CT2 and CT14 in DD2. Right panel: The quantitation of the total number of intersections between the concentric rin...

Quantitation of the Daily Reorganization in the PDF Terminals at the Dorsal Protocerebrum (A) Representative confocal images of pdf>mCD8-GFP brains dissected at circadian time CT2 and CT14 in DD2. Six evenly spaced (10 μm) concentric rings centered at the point where the first dorsal ramification opens up were drawn on each brain hemisphere. The nu...

The PDF Signal along the Midline Disappears with Aging Brains from newly eclosed (less than 1 d old, upper panels) and 3–4 d old (lower panels) flies were dissected at ZT2 after five days of LD cycles and incubated with anti-PDF and anti-GFP antisera. Pupae and recently eclosed flies displayed an intense PDF signal along the midline and the area su...

Drosophila is a well-established model to study the molecular basis of neurodegenerative diseases. We carried out a misexpression screen to identify genes involved in neurodegeneration examining locomotor behavior in young and aged flies. We hypothesized that a progressive loss of rhythmic activity could reveal novel genes involved in neurodegenera...

Great efforts have been directed to the dissection of the cell-autonomous circadian oscillator in Drosophila. However, less information is available regarding how this oscillator controls rhythmic rest-activity cycles. We have identified a viable allele of roundabout, robo(hy), where the period of locomotor activity is shortened. From its role in a...

Previous work in Drosophila has defined two populations of circadian brain neurons, morning cells (M-cells) and evening cells (E-cells), both of which keep circadian time and regulate morning and evening activity, respectively. It has long been speculated that a multiple oscillator circadian network in animals underlies the behavioral and physiolog...

Substantial progress has been made in elucidating the molecular processes that impart a temporal control to physiology and behavior in most eukaryotes. In Drosophila, dorsal and ventral neuronal networks act in concert to convey rhythmicity. Recently, the hierarchical organization among the different circadian clusters has been addressed, but how m...

Human circadian rhythms are entrained by the environmental light-dark cycle. In this study we have recorded diurnal and seasonal variations in a Mapuche native com-munity of Neuquén (Patagonia, Argentina), where environmental variables including photoperiod, temperature and rainfall vary substantially throughout the year and could be considered as...