The Experts below are selected from a list of 255 Experts worldwide ranked by ideXlab platform

Rudiger Krahe - One of the best experts on this subject based on the ideXlab platform.

  • electrocommunication behaviour and non invasively measured androgen changes following induced seasonal breeding in the weakly electric fish apteronotus leptorhynchus
    Hormones and Behavior, 2012
    Co-Authors: Martin Cuddy, Rudiger Krahe, Nadia Aubinhorth
    Abstract:

    Abstract Androgens are known to be involved in reproductive behaviours including courtship and aggression. According to the Challenge Hypothesis, androgen activity upregulates male reproductive behaviour seasonally and also modulates short term adaptation of these behaviours in response to social context. In the weakly electric fish, Apteronotus leptorhynchus, 11-ketotestosterone (11-KT) has been previously implicated in the regulation of electrocommunication behaviours that are believed to have roles in both aggression and courtship. Changes in male 11-KT levels were quantified using a non-invasive measurement technique alongside changes in electrocommunication behaviour following environmental cues that simulated the onset of the breeding season. Males showed an increase in mean electric organ discharge frequency (EODf), which is consistent with earlier results showing a female preference for high EODf. A subset of males with high initial EODfs showed increases in both 11-KT and EODf, which provides support for an EODf-based dominance hierarchy in this species. Males housed in social conditions and exposed to breeding conditioning also showed higher overall electric organ discharge frequencies and 11-KT compared to males housed in isolation. Evidence is presented that another type of electrocommunication signal previously implicated in courtship may also serve as an inter-male signal of submission. Our results are consistent with earlier observations that electrocommunication signals produced during inter-male aggression serve in deterring attacks, and their Pattern of Production further suggested the formation of a dominance hierarchy.

Martin Cuddy - One of the best experts on this subject based on the ideXlab platform.

  • electrocommunication behaviour and non invasively measured androgen changes following induced seasonal breeding in the weakly electric fish apteronotus leptorhynchus
    Hormones and Behavior, 2012
    Co-Authors: Martin Cuddy, Rudiger Krahe, Nadia Aubinhorth
    Abstract:

    Abstract Androgens are known to be involved in reproductive behaviours including courtship and aggression. According to the Challenge Hypothesis, androgen activity upregulates male reproductive behaviour seasonally and also modulates short term adaptation of these behaviours in response to social context. In the weakly electric fish, Apteronotus leptorhynchus, 11-ketotestosterone (11-KT) has been previously implicated in the regulation of electrocommunication behaviours that are believed to have roles in both aggression and courtship. Changes in male 11-KT levels were quantified using a non-invasive measurement technique alongside changes in electrocommunication behaviour following environmental cues that simulated the onset of the breeding season. Males showed an increase in mean electric organ discharge frequency (EODf), which is consistent with earlier results showing a female preference for high EODf. A subset of males with high initial EODfs showed increases in both 11-KT and EODf, which provides support for an EODf-based dominance hierarchy in this species. Males housed in social conditions and exposed to breeding conditioning also showed higher overall electric organ discharge frequencies and 11-KT compared to males housed in isolation. Evidence is presented that another type of electrocommunication signal previously implicated in courtship may also serve as an inter-male signal of submission. Our results are consistent with earlier observations that electrocommunication signals produced during inter-male aggression serve in deterring attacks, and their Pattern of Production further suggested the formation of a dominance hierarchy.

Joseph Francois - One of the best experts on this subject based on the ideXlab platform.

  • Preferential Trade Arrangements and the Pattern of Production and Trade when Inputs are Differentiated
    2005
    Co-Authors: Joseph Francois
    Abstract:

    textabstractThis paper is concerned with rules of origin when intermediate goods are differentiated. An analytical model emphasizes trade Patterns and the relative importance of trade in intermediates given trade preferences. Econometric evidence based on intra-OECD trade in motor vehicles and motor vehicle parts points to a systematic impact of trade costs and FTA membership, following from rules of origin and reduction in border measures, on the role of intermediates and their relative importance in Production and trade. These results are consistent with a conceptual framework involving rules-base trade costs and two-way trade in differentiated intermediate goods and final goods.

  • Preferential Trade Arrangements and the Pattern of Production and Trade when Inputs are Differentiated
    SSRN Electronic Journal, 2005
    Co-Authors: Joseph Francois
    Abstract:

    This paper is concerned with rules of origin when intermediate goods are differentiated. An analytical model emphasizes trade Patterns and the relative importance of trade in intermediates given trade preferences. Econometric evidence based on intra-OECD trade in motor vehicles and motor vehicle parts points to a systematic impact of trade costs and FTA membership, following from rules of origin and reduction in border measures, on the role of intermediates and their relative importance in Production and trade. These results are consistent with a conceptual framework involving rules-base trade costs and two-way trade in differentiated intermediate goods and final goods.

  • Preferential Trade Liberalization in the North Atlantic
    1997
    Co-Authors: Richard E. Baldwin, Joseph Francois
    Abstract:

    This study provides a quantitative assessment of the implications of preferential trade liberalization by the North Atlantic economies. Emphasis is placed on the Pattern of Production and trade in North America and Western Europe, the Pattern of import protection, and the likely trade and income effects of trade liberalization. The potential benefits of preferential trade liberalization are also compared with the potential benefits of post-Uruguay Round most-favoured nation-based reductions in trade barriers. The numerical assessment highlights the impact both on the North Atlantic economies themselves, and on their important regional trading partners.

Nadia Aubinhorth - One of the best experts on this subject based on the ideXlab platform.

  • electrocommunication behaviour and non invasively measured androgen changes following induced seasonal breeding in the weakly electric fish apteronotus leptorhynchus
    Hormones and Behavior, 2012
    Co-Authors: Martin Cuddy, Rudiger Krahe, Nadia Aubinhorth
    Abstract:

    Abstract Androgens are known to be involved in reproductive behaviours including courtship and aggression. According to the Challenge Hypothesis, androgen activity upregulates male reproductive behaviour seasonally and also modulates short term adaptation of these behaviours in response to social context. In the weakly electric fish, Apteronotus leptorhynchus, 11-ketotestosterone (11-KT) has been previously implicated in the regulation of electrocommunication behaviours that are believed to have roles in both aggression and courtship. Changes in male 11-KT levels were quantified using a non-invasive measurement technique alongside changes in electrocommunication behaviour following environmental cues that simulated the onset of the breeding season. Males showed an increase in mean electric organ discharge frequency (EODf), which is consistent with earlier results showing a female preference for high EODf. A subset of males with high initial EODfs showed increases in both 11-KT and EODf, which provides support for an EODf-based dominance hierarchy in this species. Males housed in social conditions and exposed to breeding conditioning also showed higher overall electric organ discharge frequencies and 11-KT compared to males housed in isolation. Evidence is presented that another type of electrocommunication signal previously implicated in courtship may also serve as an inter-male signal of submission. Our results are consistent with earlier observations that electrocommunication signals produced during inter-male aggression serve in deterring attacks, and their Pattern of Production further suggested the formation of a dominance hierarchy.

George A. Kassavetis - One of the best experts on this subject based on the ideXlab platform.

  • Abortive Initiation of Transcription at a Hybrid Promoter AN ANALYSIS of THE SLIDING CLAMP ACTIVATOR of BACTERIOPHAGE T4 LATE TRANSCRIPTION, AND A COMPARISON of THE ς70 AND T4 GP55 PROMOTER RECOGNITION PROTEINS
    The Journal of biological chemistry, 1998
    Co-Authors: E P Geiduschek, George A. Kassavetis
    Abstract:

    Abstract Bacteriophage T4 late promoters are transcribed by an RNA polymerase holoenzyme comprising the Escherichia coli core, E, the phage gene 55-encoded promoter recognition subunit, gp55, and the gene 33-encoded co-activator, gp33. Transcriptional initiation is activated by the T4 gene 45-encoded sliding clamp, which is loaded on to DNA at enhancer-like sites by its clamp-loader. Correct initiation of transcription at late promoters in basal mode requires only RNA polymerase core and gp55 (E·gp55). Dinucleotide-primed abortive initiation of basal and activated T4 late transcription has been compared. Only the trinucleotide non-productive transcript is made at a high rate; all other short transcripts are made at rates of less than one molecule per productive transcript. Gp45 increases abortive trinucleotide synthesis along with productive transcription, although the proportion of productive transcripts is also elevated. Nevertheless, this increase accounts for only a small part of the activation of T4 late transcription that is generated by its activator and co-activator. The Pattern of Production of short transcripts differs subtly between basal and enhanced transcription, indicating that linking the RNA polymerase with its sliding clamp activator only generates minor changes in the transition from abortive to productive RNA chain elongation. The T4 late promoter is converted to a strong ς70 promoter by inserting an appropriate −35 promoter element. A direct comparison at such a hybrid promoter shows ς70 and gp55 generating qualitatively and quantitative different Patterns of abortive initiation at the same start site.