Time-dependent modulation of pheromone-sensitive trichoid sensilla of the hawkmoth Manduca sexta

The pheromone release and also the male responsiveness to pheromone in nocturnal moths are controlled by circadian pacemakers. In Manduca sexta the circadian rhythm in the calling behaviour of female moths with a maximum at the end of the scotophase is correlated with peaks in the male flight activity. Furthermore circadian changes in the concentration of the biogenic amine octopamine (OA) in the hemolymph and brain modulate the moth´s sensitivity and responsiveness to pheromone. In addition the injection of OA into the hemolymph improved pheromone-source finding in wind tunnel experiments time-dependently. The OA-dependent sensitization of the male behavior might be partly due to central effects and partly due to the augmentation of the pheromone transduction. To investigate the time-dependent modulation of the pheromone transduction of olfactory receptor neurons (ORNs), OA and its precursor tyramine (TA) were applied via the recording electrode in long-term tip recordings of single trichoid sensilla of M. sexta. To search for time-dependent differences the recordings were performed at Zeitgebertime (ZT) 22-1, 1-4 or 8-11 (ZT 0 = lights on). The trichoid sensilla were stimulated with the main pheromone component bombykal (BAL) in a non-adapting protocol for 180 min. The perfusion of the sensillar lymph with OA and TA increased both the sensillar potential (SP) amplitude and the action potential (AP) frequency at ZT 8-11 but not at ZT 22-1. Furthermore the ORNs are adapted on the level of the AP response with beginning of the photophase and the application of OA and TA disadapts the ORNs at ZT 8-11. In addition the endogenous adaptation in the AP distribution in BAL responses at ZT 8-11 was antagonized by OA and TA. OA but not TA also increased the spontaneous AP frequency by increasing the number of bursts and by prolonging the bursts, without affecting the generation of single APs. Furthermore the OA-receptor antagonist epinastine (EPI) decreased the AP frequency strongly at ZT 8-11 and to a lesser extent at ZT 22-1, without affecting the SP. Also the spontaneous AP frequency was reduced by EPI to the same extent at ZT 22-1 and ZT 8-11. At ZT 22-1 EPI shifted the AP distribution in BAL responses from phasic to tonic responses. These results show that OA is the key factor in the time-dependent modulation of the pheromone-sensitivity of ORNs and that OA could be obligatory for the generation of strong and phasic BAL responses and thus could be necessary for a high pulse resolution of the ORNs. Because the majority of OA receptors is positively coupled to adenylyl cyclases it was determined whether cAMP mimics the OA-dependent disadaptation. The membrane-permeable cAMP analogue 8-bromo cAMP (8bcAMP) increased the SP amplitude in recordings at ZT 1-4 and ZT 8-11 but not at ZT 22-1. Furthermore 8bcAMP antagonized an endogenous adaptation in the mean SP amplitude at ZT 1-4 and partly at ZT 8-11. In contrast, 8bcAMP did not affect the normalized initial AP frequency or the distribution of APs in responses and did not antagonize the endogenous shift to lower mean AP frequencies at ZT 8-11. In addition, 8bcAMP increased the spontaneous AP frequency in recordings at ZT 8-11. Furthermore, the ORNs are also adapted on the level of the spontaneous activity with beginning of the photophase and 8bcAMP disadapts the ORNs at ZT 1-4 and ZT 8-11 by increasing both the number of bursts and spikes. In contrast, OA strongly increased the mean spontaneous AP frequency at ZT 8-11 by predominantly increasing the number of bursts. Thus, 8bcAMP only partly mimics the OA-dependent effects. Our results suggest that OA at least activates an adenylyl cyclase, additional OA-dependent effects on the Ca2+-levels are discussed. Because adapting pheromone stimuli cause rises of cyclic guanosine monophosphate (cGMP) in trichoid sensilla of M. sexta, we wanted to determine whether cGMP decreases the pheromone-sensitivity of ORNs in a time-dependent manner. The membrane-permeable cGMP analogue 8-bromo cGMP (8bcGMP) adapted the AP response but not the SP. Perfusion with 8bcGMP decreased the initial AP frequency and the numbers of APs in the first 100 ms of the BAL response. Furthermore, the decrease in the 8bcGMP-dependent AP frequency was stronger in recordings at ZT 8-11 than at ZT 1-4. In addition, at ZT 8-11 8bcGMP enhanced the endogenous shift from phasic to tonic responses. Furthermore 8bcGMP altered the waveform of spontaneous APs by increasing their peak-to-peak amplitude and by prolonging the negative phase. Thus, we hypothesize that additionally to changes in the OA concentration during the photophase, elevated cGMP levels underlie a daytime-dependent decrease in pheromone sensitivity and a decline in the temporal resolution of pheromone pulses

Tackling Overindebtedness Through Financial Education in Ecuador

This thesis examines the growth and development of the financial sector in Ecuador, focusing in particular on the products and services offered to low-income individuals, including, but not limited to microfinance. I examine the current problem of over-indebtedness, and evaluate both the supply/institutional side as well as the demand/client side. I conclude that while the market for microfinance institutions and low-income products and services is highly saturated and very developed, governmental interventions, structural problems and lack of accompanying financial capabilities have limited the effectiveness of the industry, and perpetuated indebtedness. I propose mandatory financial education programs provided by all financial institutions that target low-income clients in particular. This policy recommendation will improve the current microfinance model by increasing client financial knowledge, hence mitigating the harmful consequences of governmental intervention in the financial system

Squamous Cell Carcinoma of the Eyelid with Ocular Metastases in a Domestic Cat

Background: Eye neoplasms are infrequent in felines and usually affect the eyelids. Squamous cell carcinoma (SCC) is a neoplasm that occurs owing to recurrent lesions caused by solar radiation and affects the margins of the ears, eyelids, nose and lips of animals with light-colored coat. The clinical signs consist of ulcerated, crusty lesions that may form masses. The diagnosis is established by means of histopathological analysis, and the prognosis depends on the area affected and tumor infiltration. This work aimed to describe a case of SCC in the eyelid with invasion of the eye and its adnexa in a cat, highlighting clinical aspects and the importance of the anatomopathological examination. Case: A female mixed breed senile cat that had been rescued from the streets was brought in for examination. Dehydration and a low body condition score were observed at the general clinical examination. A physical inspection revealed the presence of an ulcerated periocular lesion on the eyelid; the right eye exhibited increased size and loss of definition of its internal structures. The presence of malodorous cerumen in the right ear canal, a tilted head, and walking in circles to the right were also noted. A dysplastic epithelium along with neutrophilic inflammation was observed at the cytopathological analysis. The treatment instituted consisted of administration of antibacterial and anti-inflammatory drugs, and cleaning of the ear. On the follow-up appointment, 2 days later, the patient’s condition had worsened and in spite of the supportive therapy administered, the animal died. An anatomopathological study of the body identified, in addition to the alterations in the eyelid and the eye mentioned above, a traumatic lesion with perforation of the mandibular bone, and presence of a brownish content with caseous consistency in the right ear canal. After visualization of the microscopic alterations, the diagnosis established was squamous cell carcinoma of the eyelid with metastases in the optical nerve and choroid blood vessels. Discussion: Squamous cell carcinoma is one of the most common epithelial neoplasms in felines, and can occur in any region of the face; however, the eyelids and the eyes are less frequently affected, which confirms that the case reported here is uncommon. SCC has a higher incidence in female cats older than 10 years of age with light-colored coat and highly exposed to ultraviolet radiation. The case reported here exhibited these characteristics, as the patient had been rescued from the streets where exposition to sunlight is intense. The clinical presentation was consistent with that described in other works, with ulcerated crusty lesions on the eyelid and the nose. Vestibular syndrome, as inferred from the tilted head and circular gait (walking in circles to the right), could be explained by internal otitis, which was observed at necropsy. The cytological analysis of the eye lesion demonstrated the presence of a neutrophilic inflammatory process along with a dysplastic or immature squamous epithelium, which prompted for therapy using antimicrobial and anti-inflammatory drugs. The definitive diagnosis was established with basis on the histopathological analysis, which revealed a pattern of neoplastic cells arranged in clusters or strands connected to the epidermal surface, and the presence of “keratin pearls” consistent with SCC affecting not only the eyelid and the eye, but also invading the optical nerve and the choroid blood vessels. The prognosis was unfavorable owing to the advanced stage of the tumor and concomitant diseases. Even though the development of SCC in the eyelid is relatively common, the occurrence of metastasis in the eye adnexa is rare in felines. An anatomopathological study was required to establish the diagnosis of SCC as the patient’s clinical history data were scarce. Keywords: squamous cell carcinoma, feline, eye neoplasm, oncology. Título: Carcionoma de células escamosas em pálpebra com metástase ocular em um gato doméstico. Descritores: carcinoma de células escamosas, felino, neoplasia ocular, oncologia

Pharmacological Investigation of Protein Kinase C- and cGMP-Dependent Ion Channels in Cultured Olfactory Receptor Neurons of the Hawkmoth Manduca sexta

In the hawkmoth Manduca sexta, pheromone stimuli of different strength and duration rise the intracellular Ca2+ concentration in olfactory receptor neurons (ORNs). While second-long pheromone stimuli activate protein kinase C (PKC), which apparently underlies processes of short-term adaptation, minute-long pheromone stimuli elevate cyclic guanosine monophosphate (cGMP) concentrations, which correlates with time courses of long-term adaptation. To identify ion channels involved in the sliding adjustment of olfactory sensitivity, inside-out patch clamp recordings on cultured ORNs of M. sexta were performed to characterize Ca2+-, PKC-, and cGMP-dependent ion channels. Stepping to positive holding potentials in high intracellular Ca2+ elicits different Ca2+-dependent ion channels, namely small-conductance channels (2–20 ps), medium-conductance channels (20–100 ps), and large-conductance channels (>100 ps). Ion channels of 40, 60, and 70 ps opened after PKC activation, whereas 10- and >100-ps channels were observed less frequently. Application of 8-bromo cyclic guanosine monophosphate opened 55- and 70-ps channels and increased the open probability of >100-ps channels, whereas even in the presence of phorbol ester 40-ps channels were inhibited. Thus, cGMP elevations activate a different set of ion channels as compared with PKC and suppress at least one PKC-dependent ion channel

The Stimulatory Gαs Protein Is Involved in Olfactory Signal Transduction in Drosophila

Seven-transmembrane receptors typically mediate olfactory signal transduction by coupling to G-proteins. Although insect odorant receptors have seven transmembrane domains like G-protein coupled receptors, they have an inverted membrane topology, constituting a key difference between the olfactory systems of insects and other animals. While heteromeric insect ORs form ligand-activated non-selective cation channels in recombinant expression systems, the evidence for an involvement of cyclic nucleotides and G-proteins in odor reception is inconsistent. We addressed this question in vivo by analyzing the role of G-proteins in olfactory signaling using electrophysiological recordings. We found that Gαs plays a crucial role for odorant induced signal transduction in OR83b expressing olfactory sensory neurons, but not in neurons expressing CO2 responsive proteins GR21a/GR63a. Moreover, signaling of Drosophila ORs involved Gαs also in a heterologous expression system. In agreement with these observations was the finding that elevated levels of cAMP result in increased firing rates, demonstrating the existence of a cAMP dependent excitatory signaling pathway in the sensory neurons. Together, we provide evidence that Gαs plays a role in the OR mediated signaling cascade in Drosophila

(Digitale) Medienkompetenz in der Stadtbibliothek Kreuztal – Ein Blick in das Projekt „Wissen, Können, Machen“

Digitale Medienkompetenz ist weiterhin ein wichtiger Faktor in der Arbeit einer Öffentlichen Bibliothek. Die Stadtbibliothek Kreuztal hat ein Angebot entwickelt, das alle Altersgruppen erreichen soll und dessen Fokus es ist, digitale Medien nicht nur zu konsumieren, sondern sie zu verstehen, selbst zu gestalten und einen Bezug zu ihnen herzustellen. Die Voraussetzungen, Motivationen, Angebote und Umsetzungsstrategien werden im Folgenden beschrieben.Digital media literacy continues to be an important part of a public libraries work. The public library in Kreuztal developed a project, which is supposed to reach all age groups and which's focus is not to just consume digital media, but to understand, produce and to develop a closer relationship with them. The conditions, motivations, activities and implementation will be covered in the following article.Peer Reviewe

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Time-dependent modulation of pheromonesensitive trichoid sensilla of the hawkmoth Manduca sexta Tageszeitabhängige Modulation von pheromonsensitiven Trichoidsensille

Time-dependent modulation of pheromone-sensitive trichoid sensilla of the hawkmoth Manduca sexta

The pheromone release and also the male responsiveness to pheromone in nocturnal moths are controlled by circadian pacemakers. In Manduca sexta the circadian rhythm in the calling behaviour of female moths with a maximum at the end of the scotophase is correlated with peaks in the male flight activity. Furthermore circadian changes in the concentration of the biogenic amine octopamine (OA) in the hemolymph and brain modulate the moth´s sensitivity and responsiveness to pheromone. In addition the injection of OA into the hemolymph improved pheromone-source finding in wind tunnel experiments time-dependently. The OA-dependent sensitization of the male behavior might be partly due to central effects and partly due to the augmentation of the pheromone transduction. To investigate the time-dependent modulation of the pheromone transduction of olfactory receptor neurons (ORNs), OA and its precursor tyramine (TA) were applied via the recording electrode in long-term tip recordings of single trichoid sensilla of M. sexta. To search for time-dependent differences the recordings were performed at Zeitgebertime (ZT) 22-1, 1-4 or 8-11 (ZT 0 = lights on). The trichoid sensilla were stimulated with the main pheromone component bombykal (BAL) in a non-adapting protocol for 180 min. The perfusion of the sensillar lymph with OA and TA increased both the sensillar potential (SP) amplitude and the action potential (AP) frequency at ZT 8-11 but not at ZT 22-1. Furthermore the ORNs are adapted on the level of the AP response with beginning of the photophase and the application of OA and TA disadapts the ORNs at ZT 8-11. In addition the endogenous adaptation in the AP distribution in BAL responses at ZT 8-11 was antagonized by OA and TA. OA but not TA also increased the spontaneous AP frequency by increasing the number of bursts and by prolonging the bursts, without affecting the generation of single APs. Furthermore the OA-receptor antagonist epinastine (EPI) decreased the AP frequency strongly at ZT 8-11 and to a lesser extent at ZT 22-1, without affecting the SP. Also the spontaneous AP frequency was reduced by EPI to the same extent at ZT 22-1 and ZT 8-11. At ZT 22-1 EPI shifted the AP distribution in BAL responses from phasic to tonic responses. These results show that OA is the key factor in the time-dependent modulation of the pheromone-sensitivity of ORNs and that OA could be obligatory for the generation of strong and phasic BAL responses and thus could be necessary for a high pulse resolution of the ORNs. Because the majority of OA receptors is positively coupled to adenylyl cyclases it was determined whether cAMP mimics the OA-dependent disadaptation. The membrane-permeable cAMP analogue 8-bromo cAMP (8bcAMP) increased the SP amplitude in recordings at ZT 1-4 and ZT 8-11 but not at ZT 22-1. Furthermore 8bcAMP antagonized an endogenous adaptation in the mean SP amplitude at ZT 1-4 and partly at ZT 8-11. In contrast, 8bcAMP did not affect the normalized initial AP frequency or the distribution of APs in responses and did not antagonize the endogenous shift to lower mean AP frequencies at ZT 8-11. In addition, 8bcAMP increased the spontaneous AP frequency in recordings at ZT 8-11. Furthermore, the ORNs are also adapted on the level of the spontaneous activity with beginning of the photophase and 8bcAMP disadapts the ORNs at ZT 1-4 and ZT 8-11 by increasing both the number of bursts and spikes. In contrast, OA strongly increased the mean spontaneous AP frequency at ZT 8-11 by predominantly increasing the number of bursts. Thus, 8bcAMP only partly mimics the OA-dependent effects. Our results suggest that OA at least activates an adenylyl cyclase, additional OA-dependent effects on the Ca2+-levels are discussed. Because adapting pheromone stimuli cause rises of cyclic guanosine monophosphate (cGMP) in trichoid sensilla of M. sexta, we wanted to determine whether cGMP decreases the pheromone-sensitivity of ORNs in a time-dependent manner. The membrane-permeable cGMP analogue 8-bromo cGMP (8bcGMP) adapted the AP response but not the SP. Perfusion with 8bcGMP decreased the initial AP frequency and the numbers of APs in the first 100 ms of the BAL response. Furthermore, the decrease in the 8bcGMP-dependent AP frequency was stronger in recordings at ZT 8-11 than at ZT 1-4. In addition, at ZT 8-11 8bcGMP enhanced the endogenous shift from phasic to tonic responses. Furthermore 8bcGMP altered the waveform of spontaneous APs by increasing their peak-to-peak amplitude and by prolonging the negative phase. Thus, we hypothesize that additionally to changes in the OA concentration during the photophase, elevated cGMP levels underlie a daytime-dependent decrease in pheromone sensitivity and a decline in the temporal resolution of pheromone pulses