39 research outputs found

    The Effects of Breeding Protocol in C57BL/6J Mice on Adult Offspring Behaviour

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    Animal experiments have demonstrated that a wide range of prenatal exposures can impact on the behaviour of the offspring. However, there is a lack of evidence as to whether the duration of sire exposure could affect such outcomes. We compared two widely used methods for breeding offspring for behavioural studies. The first involved housing male and female C57Bl/6J mice together for a period of time (usually 10–12 days) and checking for pregnancy by the presence of a distended abdomen (Pair-housed; PH). The second involved daily introduction of female breeders to the male homecage followed by daily checks for pregnancy by the presence of vaginal plugs (Time-mated; TM). Male and female offspring were tested at 10 weeks of age on a behavioural test battery including the elevated plus-maze, hole board, light/dark emergence, forced swim test, novelty-suppressed feeding, active avoidance and extinction, tests for nociception and for prepulse inhibition (PPI) of the acoustic startle response. We found that length of sire exposure (LSE) had no significant effects on offspring behaviour, suggesting that the two breeding protocols do not differentially affect the behavioural outcomes of interest. The absence of LSE effects on the selected variables examined does not detract from the relevance of this study. Information regarding the potential influences of breeding protocol is not only absent from the literature, but also likely to be of particular interest to researchers studying the influence of prenatal manipulations on adult behaviour

    Fly Photoreceptors Encode Phase Congruency

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    More than five decades ago it was postulated that sensory neurons detect and selectively enhance behaviourally relevant features of natural signals. Although we now know that sensory neurons are tuned to efficiently encode natural stimuli, until now it was not clear what statistical features of the stimuli they encode and how. Here we reverse-engineer the neural code of Drosophila photoreceptors and show for the first time that photoreceptors exploit nonlinear dynamics to selectively enhance and encode phase-related features of temporal stimuli, such as local phase congruency, which are invariant to changes in illumination and contrast. We demonstrate that to mitigate for the inherent sensitivity to noise of the local phase congruency measure, the nonlinear coding mechanisms of the fly photoreceptors are tuned to suppress random phase signals, which explains why photoreceptor responses to naturalistic stimuli are significantly different from their responses to white noise stimuli

    Spermatozoal sensitive biomarkers to defective protaminosis and fragmented DNA

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    Human sperm DNA damage may have adverse effects on reproductive outcome. Infertile men possess substantially more spermatozoa with damaged DNA compared to fertile donors. Although the extent of this abnormality is closely related to sperm function, the underlying etiology of ensuing male infertility is still largely controversial. Both intra-testicular and post-testicular events have been postulated and different mechanisms have been proposed to explain the presence of damaged DNA in human spermatozoa. Three among them, i.e. abnormal chromatin packaging, oxidative stress and apoptosis, are the most studied and discussed in the present review. Furthermore, results from numerous investigations are presented, including our own findings on these pathological conditions, as well as the techniques applied for their evaluation. The crucial points of each methodology on the successful detection of DNA damage and their validity on the appraisal of infertile patients are also discussed. Along with the conventional parameters examined in the standard semen analysis, evaluation of damaged sperm DNA seems to complement the investigation of factors affecting male fertility and may prove an efficient diagnostic tool in the prediction of pregnancy outcome

    cynDAZ: a cynomolgus monkey homologue of the human deleted-in-azoospermia (DAZ) gene.

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    A gene on the human Y chromosome, specifically deleted in azoospermic patients (DAZ: deleted in azoospermia), and a DAZ homologue (DAZH) on human chromosome 3, have been recently described. In the present work we report the isolation and characterization of the corresponding DAZH gene of the cynomolgus monkey (Macaca fascicularis), which we have named cynDAZLA (cynomolgus DAZ-like autosomal). Reverse transcription-polymerase chain reaction was used to amplify the monkey DAZ homologue, and sequence analysis revealed an open reading frame of 888 bp encoding 295 amino acids. Northern blot hybridization of different tissues to a probe derived from the cynDAZLA cDNA detected a transcript of 3.5 kb that, in the male, was expressed only in the testis. Comparison of the cynDAZLA sequence to autosomal DAZ homologues from human, mouse and Drosophila showed two RNA-recognition motifs (RRM) and the presence of only one DAZ consensus repeat compared with the seven repeats found in the human DAZ gene on the Y chromosome. The homology of the cynDAZLA cDNA compared with the human DAZH and mouse dazla cDNAs is 97.97 and 87.46% respectively. The identification of the monkey cynDAZLA enables further studies regarding the putative functions of DAZH, such as onset of expression and hormonal dependence of this gene

    The metaphysical detective story in Paul Auster's The New York trilogy and Thomas Pynchon's The crying of lot 49

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    While the first two chapters of the thesis provide the necessary theoretical framework concerning the classical detective story and the metaphysical detective story, in the third chapter this framework is employed to analyze the particular themes that are present in The New York Trilogy and The Crying of Lot 49. To explain the metaphysical detective story, a step back to the classical detective story as its predecessor is required. To sum up the oppositions expressed in criticism dealing with this subject, the contrast between these two genres has been defined in terms of high art and popular art (Todorov), art and kitsch (Holquist), ontological dominant and epistemological dominant (McHale), postmodern and positivistic mode of thinking (Spanos). The metaphysical detective story takes the conventions of the classical detective story and distorts them in order to betray the reader's expectations. Since the popular genres are constituted by their corresponding sets of conventions which need to be familiar, any change in them causes the work to lose its status as part of the genre. In this case, the classical detective story has served as a point of departure for many authors who transformed it into a completely different genre which had no longer anything to do with popular literature. Classical detective..
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