Nanoparticulate systems for brain delivery of drugs.

This review examines how birds use the annual cycle in photoperiod to ensure that seasonal events—breeding, molt, and song production—happen at the appropriate time of year. Differences in breeding strategies between birds and mammals reflect basic differences in biology. Avian breeding seasons tend to be of shorter duration and more asymmetric with respect to changes in photoperiod. Breeding seasons can occur at the same time each year (predictable) or at different times (opportunistic), depending on the food resource. In all cases, there is evidence for involvement of photoperiodic control, nonphotoperiodic control, and endogenous circannual rhythmicity. In predictable breeders (most nontropical species), photoperiod is the predominant proximate factor. Increasing photoperiods of spring stimulate secretion of gonadotropin-releasing hormone (GnRH) and consequent gonadal maturation. However, breeding ends before the return of short photoperiods. This is the consequence of a second effect of long photoperi...

Photoperiodic Control of Seasonality in Birds

This article reviews various procedures used in the analysis of circadian rhythms at the populational, organismal, cellular and molecular levels. The procedures range from visual inspection of time plots and actograms to several mathematical methods of time series analysis. Computational steps are described in some detail, and additional bibliographic resources and computer programs are listed.

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Procedures for numerical analysis of circadian rhythms.

Purpose. It has recently been suggested that the poly(butylcyanoacrylate) (PBCA) nanoparticle drug delivery system has a generalized toxic effect on the blood-brain barrier (BBB) (8) and that this effect forms the basis of an apparent enhanced drug delivery to the brain. The purpose of this study is to explore more fully the mechanism by which PBCA nanoparticles can deliver drugs to the brain.

Direct evidence that polysorbate-80-coated poly(butylcyanoacrylate) nanoparticles deliver drugs to the CNS via specific mechanisms requiring prior binding of drug to the nanoparticles.

Drug delivery to the central nervous system by polymeric nanoparticles: what do we know?

As soon as they hatch, gallinaceous chicks follow broody hens. This matriarchal unit presents a temporal organization of activity. The ontogeny of this ultradian rhythm of activity was followed in Japanese quail during their first 3 weeks of life. Under controlled laboratory conditions, 12 groups of four chicks were recorded using an activity monitoring system. They were observed between the ages of 2 and 17 days. Chicks in groups presented an ultradian rhythm of activity, with a period that increased significantly from 14.3 +/- 1.4 minutes when chicks were 2 days old to 26.0 +/- 1.9 minutes when they were 16 days old. The increase of ultradian periodicity was particularly pronounced during their first and third weeks of life. Finally, the ultradian period was correlated positively with body weight of the chicks.

Ontogeny of the ultradian rhythm of activity in Japanese quail.

The function of ultradian rhythms is not yet clearly elucidated. In particular, short-term rhythms are expressed during early ontogeny, especially in broods of precocial birds. We investigated the relationship between the clarity of the ultradian rhythm of the activity/rest cycle of a group of young Japanese quail (Coturnix japonica) and the level of social synchronisation and spatial cohesion between the birds within that group. The subjects were descended from two lines selected for either very pronounced rhythmic or arrhythmic circadian activity. We found a positive relationship between the clarity of the ultradian rhythm of the activity/rest cycle when birds were young and the clarity of the circadian rhythm of feeding activity when birds were older, but still immature. The temporal organisation of the behaviour of the chicks from these two lines was observed in outdoor aviaries, when they were 4, 8, 12 and 15 days old. The mean ultradian period expressed by groups of 12 chicks was variable, with a mi...

Ultradian rhythm of activity in Japanese quail groups under semi-natural conditions during ontogeny: Functional aspects and relation to circadian rhythm

In European quail, individual birds can be discriminated by using only three parameters describing the long-distance vocalizations used during pair bonding. In the male vibrato these parameters are: the total duration of the vibrato, the duration of the second syllable and the highest energy component of the fundamental. For the male triplet, the necessary parameters are: the interval between the highest frequency points of syllables 1 and 2, of syllables 2 and 3, and the frequency of the inflexion point of the third syllable. Individual females can usually be identified by three rally call parameters; these being the interval between syllables 1 and 2, the interval between the lowest frequency points, and the frequency of maximal amplitude in the second syllable of the rally call. Comparison based on these three parameters for each form of vocalization showed that more than 80% of individuals were correctly discriminated thus permitting fairly reliable counts of populations in the field. Intra-individual...

Individual differences in the long-distance vocalizations used during pair bonding in European quail (Coturnix coturnix)

Temporal characteristics of migratory behavior in birds are usually studied at the species and population levels, and rarely at the individual level. Variations among species and populations of the seasonal onset of migratory behavior have been widely investigated, but very little is known about its daily organization or whether birds are conservative in their behavior. The determination of intra‐ and inter‐individual variability is important for the study of genetic variations and can reveal the existence of different adaptation capacities within populations. This laboratory study analyzed intra‐ and inter‐individual variability of daily initiation and time course of nocturnal restlessness in partial‐migrant European quail (Coturnix coturnix coturnix). Thirty‐five quail were selected randomly from a captive stock, and their spring activity was recorded under natural daylenghs. Eighteen of the thirty‐five quail presented behavioral profiles of migrant birds. Migrant birds initiated their nocturnal activit...

Stable Individual Profiles of Daily Timing of Migratory Restlessness in European Quail

In conditions of constant darkness, interindividual variability in the clarity of circadian rhythmicity was observed in sexually immature young quail, with birds classified as more or less rhythmic or arrhythmic The relative clarity of this circadian rhythm was observed on the actograms by measurement of the autocorrelation coefficient ratio over 12 cycles Autocorrelation coefficients were calculated from sequential series of total activity over 12-minute periods Crosses of selected phenotypes with different clarities of rhythmicity were conducted in order to study the possibility of selection of this characteristic From a random population (N = 42, twice), pairs of the most rhythmic birds (3 families), and pairs of arrhythmic birds (4 families) were reared Autocorrelation coefficient ratios of Fl birds from rhythmic families (N = 54) were greater than those of Fl birds (N = 48) from arrhythmic families (t-test, p < 0001) These ratios in offspring were significantly correlated with that of the mean

Catherine Guyomarc'h

Papers

Ontogeny of the ultradian rhythm of activity in Japanese quail.

Ultradian rhythm of activity in Japanese quail groups under semi-natural conditions during ontogeny: Functional aspects and relation to circadian rhythm

Individual differences in the long-distance vocalizations used during pair bonding in European quail (Coturnix coturnix)

Stable Individual Profiles of Daily Timing of Migratory Restlessness in European Quail

Circadian rhythm of activity in Japanese quail in constant darkness: variability of clarity and possibility of selection.