Ontogeny of the pupal salivary, hypopharyngeal and mandibular glands and the role of apoptosis during metamorphosis in Apis mellifera

abstract: Amongst the most studied of the social insects, the honey bee has a prominent place due to its economic importance and influence on human societies. Honey bee colonies can have over 50,000 individuals, whose activities are coordinated by chemical signals called pheromones. Because these pheromones are secreted from various exocrine glands, the proper development and function of these glands are vital to colony dynamics. In this thesis, I present a study of the developmental ontogeny of the exocrine glands found in the head of the honey bee. In Chapter 2, I elucidate how the larval salivary gland transitions to an adult salivary gland through apoptosis and cell growth, differentiation and migration. I also explain the development of the hypopharyngeal and the mandibular gland using apoptotic markers and cytoskeletal markers like tubulin and actin. I explain the fundamental developmental plan for the formation of the glands and show that apoptosis plays an important role in the transformation toward an adult gland.Dissertation/ThesisMasters Thesis Biology 201

How spatial constraints on efficacy and dynamic signaling alignment shape animal communication

Effective communication is important to the survival and reproduction of many organisms. Signal transmission and reception have spatial constraints that interact to determine effectiveness. Signals are often best perceived from specific angles, and sensory systems may be limited in their ability to detect or interpret incoming stimuli from certain directions. Alignment between these directional biases can be critical to effective communication. Misalignment of either signal or sensor may disrupt signal perception. Signals also degrade during the distance traveled from signaler to receiver. Thus, how animals position themselves during communication may be under selection. Despite this, we know little about the spatial arrangement of signalers and receivers, what behaviors influence positioning, or the causes and consequences of variation in positioning. To address this fundamental gap in knowledge, I developed a geometric framework for studying the spatial constraints of communication and how they shape positioning across visual, sound, and chemical signaling. To investigate respective roles of signaler and receiver in managing these spatial constraints, I then characterized the spatial dynamics of visual signaling in the jumping spider Habronattus pyrrithrix. Males perform an elaborate courtship dance which includes arm waves and colorful ornaments; the latter are not visible from the side. The female can only perceive colors of male displays when they are presented in her frontal field of view. I recorded relative positions and orientations of both actors throughout courtship and established the role of each sex in maintaining signaling alignment. Finally, I tested how males control female orientation, and respond to signaling challenges. Using video playback, I asked how males’ arm-waving display and the visual environment determine how effectively they attracted female attention, as well as how males respond to variation in their signaling environment. These studies reveal that signaling alignment is frequently disrupted by females turning away from males, but that male arm-waving effectively re-captures her attention. Males also modulate displays in response to changing spatial and environmental conditions. Overall, this dissertation reveals the widespread role of spatial constraints in driving signaling behavior, and demonstrates that the spatial arrangement of signaler and receiver must be managed dynamically through behavioral responses

Visual and Chemosensory Pathways Associated With Male Courtship Decisions in Drosophila melanogaster

Successful mating in diverse animal species often depends on ritualistic sequences of spatially and temporally coordinated behavioral elements. Yet, the sensory cues and neural circuits that mediate optimal mating display patterns are largely unknown. The courtship ritual in Drosophila melanogaster consists of a well-studied sequence of behavioral elements — including orienting, chasing, tapping, singing, and licking — that are known to depend on several sensory modalities, including both vision and chemosensation. However, the specific sensory inputs utilized by males to direct the spatial and temporal transitions between different elements of the courtship ritual are not well understood. In this thesis, I therefore first develop a new computational tool to quantitatively characterize male courtship behaviors with a high spatial and temporal resolution. Subsequently, I use this tool, in conjunction with genetic and microscopy approaches to map the visual and chemosensory neural pathways that drive some of the patterned behavioral elements of the male courtship ritual. I demonstrate that whereas visual circuits are important for mediating both spatial and temporal components of male mating behaviors, chemosensory circuits are mostly required for enhancing the duration and intensity of courtship bouts. Further, I identify a male-specific axonal architecture present in subpopulations of foreleg chemosensory neurons which is important for helping to sustain mating behaviors. This thesis examines the inputs, processing centers, and neural architectures required for the proper organization of innate mating behaviors and should provide insight into understanding how animals transform sensory stimuli into complex behavioral outputs, which is a major goal in modern neuroscience

Odors Pulsed at Wing Beat Frequencies are Tracked by Primary Olfactory Networks and Enhance Odor Detection

Each down stroke of an insect's wings accelerates axial airflow over the antennae. Modeling studies suggest that this can greatly enhance penetration of air and air-born odorants through the antennal sensilla thereby periodically increasing odorant-receptor interactions. Do these periodic changes result in entrainment of neural responses in the antenna and antennal lobe (AL)? Does this entrainment affect olfactory acuity? To address these questions, we monitored antennal and AL responses in the moth Manduca sexta while odorants were pulsed at frequencies from 10–72 Hz, encompassing the natural wingbeat frequency. Power spectral density (PSD) analysis was used to identify entrainment of neural activity. Statistical analysis of PSDs indicates that the antennal nerve tracked pulsed odor up to 30 Hz. Furthermore, at least 50% of AL local field potentials (LFPs) and between 7–25% of unitary spiking responses also tracked pulsed odor up to 30 Hz in a frequency-locked manner. Application of bicuculline (200 μM) abolished pulse tracking in both LFP and unitary responses suggesting that GABAA receptor activation is necessary for pulse tracking within the AL. Finally, psychophysical measures of odor detection establish that detection thresholds are lowered when odor is pulsed at 20 Hz. These results suggest that AL networks can respond to the oscillatory dynamics of stimuli such as those imposed by the wing beat in a manner analogous to mammalian sniffing

Response and transcriptional regulation of rice SUMOylation system during development and stress conditions

Modification of proteins by the reversible covalent addition of the small ubiquitin like modifier (SUMO) protein has important consequences affecting target protein stability, sub-cellular localization, and protein-protein interactions. SUMOylation involves a cascade of enzymatic reactions, which resembles the process of ubiquitination. In this study, we characterized the SUMOylation system from an important crop plant, rice, and show that it responds to cold, salt and ABA stress conditions on a protein level via the accumulation of SUMOylated proteins. We also characterized the transcriptional regulation of individual SUMOylation cascade components during stress and development. During stress conditions, majority of the SUMO cascade components are transcriptionally down regulated. SUMO conjugate proteins and SUMO cascade component transcripts accumulated differentially in various tissues during plant development with highest levels in reproductive tissues. Taken together, these data suggest a role for SUMOylation in rice development and stress responses

Keeping track of worm trackers

C. elegans is used extensively as a model system in the neurosciences due to its well defined nervous system. However, the seeming simplicity of this nervous system in anatomical structure and neuronal connectivity, at least compared to higher animals, underlies a rich diversity of behaviors. The usefulness of the worm in genome-wide mutagenesis or RNAi screens, where thousands of strains are assessed for phenotype, emphasizes the need for computational methods for automated parameterization of generated behaviors. In addition, behaviors can be modulated upon external cues like temperature, O2 and CO2 concentrations, mechanosensory and chemosensory inputs. Different machine vision tools have been developed to aid researchers in their efforts to inventory and characterize defined behavioral “outputs”. Here we aim at providing an overview of different worm-tracking packages or video analysis tools designed to quantify different aspects of locomotion such as the occurrence of directional changes (turns, omega bends), curvature of the sinusoidal shape (amplitude, body bend angles) and velocity (speed, backward or forward movement)

Maximum Power Point Tracking Algorithm for Advanced Photovoltaic Systems

Photovoltaic (PV) systems are the major nonconventional sources for power generation for present power strategy. The power of PV system has rapid increase because of its unpolluted, less noise and limited maintenance. But whole PV system has two main disadvantages drawbacks, that is, the power generation of it is quite low and the output power is nonlinear, which is influenced by climatic conditions, namely environmental temperature and the solar irradiation. The natural limiting factor is that PV potential in respect of temperature and irradiation has nonlinear output behavior. An automated power tracking method, for example, maximum power point tracking (MPPT), is necessarily applied to improve the power generation of PV systems. The MPPT methods undergo serious challenges when the PV system is under partial shade condition because PV shows several peaks in power. Hence, the exploration method might easily be misguided and might trapped to the local maxima. Therefore, a reasonable exploratory method must be constructed, which has to determine the global maxima for PV of shaded partially. The traditional approaches namely constant voltage tracking (CVT), perturb and observe (P&O), hill climbing (HC), Incremental Conductance (INC), and fractional open circuit voltage (FOCV) methods, indeed some of their improved types, are quite incompetent in tracking the global MPP (GMPP). Traditional techniques and soft computing-based bio-inspired and nature-inspired algorithms applied to MPPT were reviewed to explore the possibility for research while optimizing the PV system with global maximum output power under partially shading conditions. This paper is aimed to review, compare, and analyze almost all the techniques that implemented so far. Further this paper provides adequate details about algorithms that focuses to derive improved MPPT under non-uniform irradiation. Each algorithm got merits and demerits of its own with respect to the converging speed, computing time, complexity of coding, hardware suitability, stability and so on

Cell-to-cell variability in the yeast pheromone response: high throughput screen identifies genes with different effects on transmitted signal and response

Populations of isogenic cells often respond coherently to signals despite differences in protein abundance and cell state. Our previous work in the Saccharomyces cerevisiae pheromone response system (PRS) uncovered processes that reduced cell-to-cell variation in signal and response. To understand these and other processes that controlled variation, we generated a whole-genome collection of haploid strains with deletions in non-essential genes and used high-throughput flow cytometry to screen more than 1000. We identified 50 'variation genes' required for normal cell-to-cell variability in signal and response. Some genes affected only signal variability, signal strength, or system output, defining these quantities as separable 'axes' of system behavior. Two genes affected cytoplasmic microtubule function