The characteristics of 5’deiodinase (5’D) were studied in the postmitochondrial fraction (PMF) of liver homogenates from adult and developing ring doves (Streptopelia risoria). The 5’D assays were performed in the presence of abundant substrate, reverse triiodothyronine (rT3), cofactor (dithiothreitol) and trace amounts of I¹²⁵-rT3. 5’D activity was measured as I¹²⁵ released from the labelled rT3 during the assay incubation time. The 5’D assay was validated for all ages studied to assure that the initial reaction velocity of the enzyme was measured. Using the validated assay conditions the following characteristics were found in adult doves: the apparent K_m was 0.44 μM rT3, V_max was 255 pmol rT3 degraded/min-mg PMF protein. The 5’D activity was completely inhibited by 1.0 mM PTU and 50% inhibited by the addition of 18.0 μM thyroxine (T4) in the presence of 4.0 μM rT3. Activity was maximal at pH 8.04 and at 37.5 C. The K_m of the enzyme did not change throughout development (1 day prehatch to adult). The 5’D specific activity (rT3 degraded/min-mg PMF protein) was highest during early development (1 day prehatch to 7 days post-hatch), after which it gradually decreased with increasing age. The liver 5’D activity/gram of body weight was highest during the first seven days posthatch. This period of high potential triiodothyronine (T3) production corresponds with the observed period of greatest increase in plasma thyroid hormone concentrations during the first 6-8 days posthatch in ring doves. These results are the first demonstration of initial velocity 5’D activity during development in an altricial bird species and demonstrate a correlation between hepatic 5’D activity and plasma thyroid hormone concentrations during development in ring doves. / Master of Science

Pigeons were trained on a zero-delay identity match-to-sample task. Experiment 1 started with every correct match reinforced with grain access and subsequent conditions include higher fixed-ratio values. Experiment 2 included the same fixed-ratio values as experiment 1 with and without a limited hold (LH) on the opportunity to select a comparison stimulus. Prior research suggested that trials after reinforcement would have an increased likelihood of error, and that these errors would be reduced in LH conditions. Results confirmed this expected error pattern and in most LH conditions errors were reduced early in the ratio.

In two experiments pigeons were exposed to VI and FI schedules and viii schedules approximating both VI and FI schedules. In experiment I, the probabilities of the VI and FI components in a Mixed FI VI schedule were manipulated to create schedule contingencies approximating simple VI or FI. In experiment II, the minimum and maximum inter-reinforcement intervals were manipulated to create schedule contingencies approximating simple VI or FI. The major finding of both of these experiments was that maximal control by the dimension of time occurred as FI contingencies were approximated. Control by any one temporal value in experiment I depended on its temporal separation from 100 seconds and the probability of reinforcement associated with 100 seconds. Control by any one temporal value in experiment II depended on its temporal separation from the minimum inter-reinforcement interval and 100 seconds. The results were discussed in terms of interval schedule control as a form of stimulus control. A third experiment was performed to examine possible relationships between the pause in FI performance and the subsequent scallop. The baseline condition was contaminated by a procedure which may have produced effects which overrode experimental manipulations. Finally, an experiment was suggested to demonstrate behavioral contrast along a temporal dimension. The argument that interval schedule control is a form of stimulus control rested on analogy and inference. A demonstration of behavioral contrast along a temporal dimension would demonstrate more directly that time is similar to other dimensions. Hence, the same principles could be used to explain schedule control as are used to explain stimulus control.

The purpose of this study was to develop behavior by the pigeon illustrative of S+ and S- rules and to examine if behavior consistent with a concept rule interpretation developed. In order to examine this possibility six groups of pigeons (N=31) were provided different histories of autoshaping. Histories involved the identity of the color of the lighted center key and one side key of three horizontally mounted pigeon keys. Center key onset was followed three seconds later by onset of either outer key. Outer key onset was followed six seconds later by food presentation (explicitly paired) or 45 seconds later, during the inter-trial interval (explicitly unpaired). The foregoing reinforcement conditions were factored into two stimulus conditions, one where the center and side keys were lit by the same hue (identity) and one where the center and side key were lit by different hues (nonidentity). Two groups received identity stimulus sequences with explicitly unpaired food presentation. Two groups were exposed to nonidentity stimulus sequences with explicitly unpaired food presentation. One group received sessions combining exposure to both the explicitly paired identity and explicitly unpaired nonidentity trials. One group received no pretraining. Following pretraining, all birds were placed in a simultaneous matching-to-sample task utilizing the same hues used during pretraining. After reaching criterion on matching-to-sample, on a random ratio 3 schedule of reinforcement, birds were exposed to transfer tests, with a novel hue, to assess for S+ rules, S- rules, and a concept rule. The results indicated that there were no significant differences among groups in terms of their acquisition of matching-to-sample or in terms of their performance on transfer tests. All birds' responding during transfer conditions provided evidence of S+ rules, but neither demonstration of S- rules nor concept rule performance was evidenced. During autoshaping, birds in the identity, explicitly paired groups responded primarily to the center key, suggesting that the stimulus on the outer key was not a salient stimulus for the identity discrimination. For birds in the nonidentity, explicitly unpaired groups neither the center nor outer key controlled responding. For the group combining identity, explicitly paired and nonidentity, explicitly unpaired trials, the birds failed to form a discrimination between types of trials.

Four pigeons had discrimination training that required the choice of a left side-key following completion of a fixed-ratio 10 an the center key, and a right side-key response after fixed-ratio 20. Correct choices were reinforced on various fixed-interval, fixed-ratio, random-interval, and random-ratio schedules. When accuracy was examined across quarters of intervals (fixed-interval schedules) or quarters of median interreinforcerrent intervals (fixed-ratio schedules), accuracy was usually laver in the second quarter than in the first, third, or fourth quarters. When accuracy was examined across quarters of ratios (fixed-ratio schedules) or quarters of median number of correct interreinforcement trials (fixed-interval schedules), accuracy increased across quarters. These accuracy patterns did not occur m random-interval or random-ratio schedules. The results indicate that, when choice patterns differed on fixed-interval and fixed-ratio schedules, these differences were due to the methods of data analyses.

Linfection par le circovirus du pigeon (PiCV) observée régulièrement chez le jeune pigeon voyageur et de chair a été décrite dans le monde entier et est généralement considérée comme un facteur important du déclenchement du syndrome de la maladie des jeunes pigeons (YPDS). En utilisant un test sensible damplification en chaîne par polymérase (PCR), la présence de lacide désoxyibonucléique (ADN) viral du PiCV a été mise en évidence chez 13 embryons sur les 66 examinés. Par contre, aucune mise en évidence de lADN viral na été possible à partir des écouvillons de jabot prélevés chez 64 pigeons adultes nourrissant des jeunes âgés de 1 à 10 jours. LADN circoviral a également été détecté chez un nombre élevé de sujets adultes (30 sur 39 pigeons examinés) et a été le plus souvent détecté dans les organes respiratoires, incluant la trachée, le pharynx et les poumons, puis dans les tissus de la rate, des reins et du foie. Il a également été détecté dans lovaire et/ou les testicules de quelques sujets. Les tests réalisés sur des écouvillons cloacaux et pharyngés et des échantillons de sang récoltés immédiatement avant leuthanasie des pigeons adultes nont pas permis de détecter tous les oiseaux trouvés positifs lors des examens réalisés post mortem. Des tests complémentaires réalisés par PCR sur des écouvillons cloacaux prélevés séquentiellement sur 19 jeunes pigeons ont montré que 4 sujets excrétaient du virus à lâge de 15 jours pour un seul au moment du sevrage, à lâge de 28 jours. Par contre la détection de lADN viral dans les écouvillons cloacaux a atteint 100 % chez les jeunes âgés de 51 jours. Lors de la vaccination de jeunes pigeons naturellement infectés au moyen du Colombovac Paratyphus®, aucun signe clinique ni aucune différence statistique nont pu être mis en évidence entre le nombre de pigeons vaccinés et de témoins non vaccinés quant aux écouvillons et échantillons sanguins prélevés sur les oiseaux vivants et trouvés positifs par PCR, ainsi que sur les tissus examinés lors de lautopsie. Une méthode PCR quantitative basée sur la technologie SYBR Green a été développée et la validation de cette méthode sur divers échantillons tissulaires issus de jeunes pigeons présentant des symptômes du YPDS a révélé des quantités importantes de copies de génome dans certains tissus, jusque 2,88 x 10^8 copies par milligramme de foie, 5,57 x 10^8 par milligramme de rate et jusque 2,07 x 10^9 copies par milligramme de bourse de Fabricius (BF). Pour le foie, la BF et le sérum, la charge virale était significativement plus élevée chez les pigeons malades que chez les oiseaux apparemment en bonne santé. De lADN circoviral a également été mis en évidence en grande quantité dans le sperme (jusque 1,0 x 10^7 copies par éjaculat) et sur les écouvillons cloacaux prélevés chez de jeunes pigeons (jusque 3,6 x 10^10 copies par écouvillon)confirmant par un apport chiffré les observations faites lors des deux premières études sur la transmission verticale et horizontale du virus. Lanalyse de sérums de pigeons prélevés en 1991 en Belgique a montré la présence du virus six ans avant le premier diagnostic histologique. Un test dimmunofluorescence indirecte (IIF) basé sur la détection de la protéine de capside du PiCV obtenue en utilisant le système baculoviruscellules dinsecte et permettant la titration des anticorps dirigés contre la capside du PiCV a été développé. Vingt-sept des 28 sérums examinés et provenant de pigeons naturellement infectés par le PiCV, dont 4 présentaient des symptômes du YPDS, ont été trouvés positifs à des titres exprimés en logarithme de base 2 variant de 4 à 8 unités. Seul un jeune pigeon malade âgé de 4 semaines était dépourvu danticorps mesurés par IIF. Enfin, la mise au point dun vaccin plasmidique codant la protéine de capside du PiCV a été réalisée en clonant le gène ORF C1 du PiCV dans le plasmide pcDNA 3.1/H5-HIS/TOPO. Lexpression de la protéine de capside a été mise en évidence par IIF après transfection de cellules PK15. Deux groupes de 5 souris femelles, âgées de 6 à 8 semaines (BALB/c) ont été immunisées par voie intramusculaire (IM), dont un groupe vacciné avec le plasmide adjuvé par le phosphate daluminium. Après 2 et 4 immunisations les anticorps ont été mesurés par IIF et il a été noté que ladjuvant avait stimulé la réponse immunitaire de manière conséquente. Ces résultats constituent un premier pas encourageant pour lobtention dun vaccin potentiel chez le pigeon. En conclusion, limportance du mode de transmission verticale du circovirus du pigeon essentiellement via loeuf embryonné a été démontrée. Néanmoins, la plupart des jeunes sinfectent dans le colombier pendant la période de postsevrage. Les tests réalisés sur les futurs reproducteurs ne permettent pas lexclusion des pigeons adultes infectés des programmes de reproduction et rendent donc léradication du virus difficile. La vaccination au moyen du Colombovac Paratyphus® ne doit pas être considérée comme un facteur modifiant le déroulement de linfection par le PiCV. La détection de quantités relativement importantes dADN viral pourrait être corrélée au statut clinique du pigeonneau infecté par le PiCV. Le rôle de limmunité humorale spécifique devra être précisé quant à lexpression ou non de linfection. Enfin, les modalités dapplication du vaccin plasmidique, testé sur souris, doivent encore être déterminées expérimentalement chez le pigeon.

Thesis (Ph. D.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains vii, 109 p. : ill. Includes abstract. Includes bibliographical references (p. 101-109).

No description available.

This thesis examines whether juvenile feral pigeons, Columba livia, form sibling alliances when competing for access to a defensible food source. When tested as a flock at a non-depletable column feeder, with room for either one or two birds to feed, siblings associated with each other more often than expected by chance. Frequency of aggression between siblings at these feeders tended to be lower than expected on the basis of their association. Removal experiments showed that sibling presence had a positive effect on relative feeding success at the single column feeder: a juvenile who lost to another juvenile on a one-to-one basis tended, in the presence of its sibling, to lose less badly to, or even beat, that same juvenile. In contrast, presence of the winner's sibling tended not to affect the relative feeding success of competitors. These results support the hypothesis that pigeon siblings form aggressive alliances when competing for food that is defensible.

Thesis (Ph. D.)--University of California, San Diego, 2007. / Title from first page of PDF file (viewed January 9, 2008). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 77-80).