The perfume of reproduction in birds: chemosignaling in avian social life.

This article is part of a Special Issue "Chemosignals and Reproduction". Chemical cues were probably the first cues ever used to communicate and are still ubiquitous among living organisms. Birds have long been considered an exception: it was believed that birds were anosmic and relied on their acute visual and acoustic capabilities.

Behavioral effects of brain-derived estrogens in birds.

In birds as in other vertebrates, estrogens produced in the brain by aromatization of testosterone have widespread effects on behavior. Research conducted with male Japanese quail demonstrates that effects of brain estrogens on all aspects of sexual behavior, including appetitive and consummatory components as well as learned aspects, can be divided into two main classes based on their time course. First, estrogens via binding to estrogen receptors regulate the transcription of a variety of genes involved primarily in neurotransmission.

Period 2 regulates neural stem/progenitor cell proliferation in the adult hippocampus.

Background: Newborn granule neurons are generated from proliferating neural stem/progenitor cells and integrated into mature synaptic networks in the adult dentate gyrus of the hippocampus. Since light/dark variations of the mitotic index and DNA synthesis occur in many tissues, we wanted to unravel the role of the clock-controlled Period2 gene (mPer2) in timing cell cycle kinetics and neurogenesis in the adult DG.

Results: In contrast to the suprachiasmatic nucleus, we observed a non-rhythmic constitutive expression of mPER2 in the dentate gyrus.

Cell "circadian" cycle: new role for mammalian core clock genes.

In mammals, 24 hours rhythms are organized as a biochemical network of molecular clocks that are operative in all tissues, with the master clock residing in the hypothalamic suprachiasmatic nucleus (SCN). The core pacemakers of these clocks consist of auto-regulatory transcriptional/post-transcriptional feedback loops. Several lines of evidence suggest the existence of a crosstalk between molecules that are responsible for the generation of circadian rhythms and molecules that control the cell cycle progression.

The underestimated role of olfaction in avian reproduction?

Until the second half of the 20th century, it was broadly accepted that most birds are microsmatic if not anosmic and unable to detect and use olfactory information. Exceptions were eventually conceded for species like procellariiforms, vultures or kiwis that detect their food at least in part based on olfactory signals. During the past 20-30 years, many publications have appeared indicating that this view is definitely erroneous.

SK channel blockade promotes burst firing in dorsal raphe serotonergic neurons.

Previous in vivo studies have shown that blockade of small-conductance Ca(2+)-activated potassium (SK) channels enhances burst firing in dopaminergic neurons. As bursting has been found to be physiologically relevant for the synaptic release of serotonin (5-HT), we investigated the possible role of SK channels in the control of this firing pattern in 5-HT neurons of the dorsal raphe nucleus. In these cells, bursts are usually composed of doublets consisting of action potentials separated by a small interval (< 20 ms).

Site-specific effects of anosmia and cloacal gland anesthesia on Fos expression induced in male quail brain by sexual behavior.

In rats, expression of the immediate early gene, c-fos observed in the brain following male copulatory behavior relates mostly to the detection of olfactory information originating from the female and to somatosensory feedback from the penis. However, quail, like most birds, are generally considered to have a relatively poorly developed sense of smell. Furthermore, quail have no intromittent organ (e.

Proteomic changes in rat hippocampus and adrenals following short-term sleep deprivation.

Background: To identify the biochemical changes induced by sleep deprivation at a proteomic level, we compared the hippocampal proteome of rats either after 4 hours of sleep or sleep deprivation obtained by gentle handling. Because sleep deprivation might induce some stress, we also analyzed proteomic changes in rat adrenals in the same conditions. After sleep deprivation, proteins from both tissues were extracted and subjected to 2D-DIGE analysis followed by protein identification through mass spectrometry and database search.

Estradiol, a key endocrine signal in the sexual differentiation and activation of reproductive behavior in quail.

In Japanese quail, estrogen's effects on sexual behavior can be divided into three classes based on the underlying mechanisms and time-course of action and release. During embryonic life, the embryonic ovary secretes large amounts of estrogens. In contrast to what is observed in mammals where sexual differentiation essentially proceeds via masculinization of the males, in quail, females are demasculinized by their endogenous ovarian estrogens, an effect that can be blocked by injection of an aromatase inhibitor and mimicked in male embryos by an injection of estradiol.

Rapid action on neuroplasticity precedes behavioral activation by testosterone.

Testosterone has been shown to increase the volume of steroid-sensitive brain nuclei in adulthood in several vertebrate species. In male Japanese quail the volume of the male-biased sexually dimorphic medial preoptic nucleus (POM), a key brain area for the control of male sexual behavior, is markedly increased by testosterone. Previous studies assessed this effect after a period of 8-14 days but the exact time course of these effects is unknown.

Expression of reelin, its receptors and its intracellular signaling protein, Disabled1 in the canary brain: relationships with the song control system.

Songbirds produce learned vocalizations that are controlled by a specialized network of neural structures, the song control system. Several nuclei in this song control system demonstrate a marked degree of adult seasonal plasticity. Nucleus volume varies seasonally based on changes in cell size or spacing, and in the case of nucleus HVC and area X on the incorporation of new neurons.

Sleep architecture of the melanin-concentrating hormone receptor 1-knockout mice.

Growing amounts of data indicate involvement of the posterior hypothalamus in the regulation of sleep, especially paradoxical sleep (PS). Accordingly, we previously showed that the melanin-concentrating hormone (MCH)-producing neurons of the rat hypothalamus are selectively activated during a PS rebound. In addition, intracerebroventricular infusion of MCH increases total sleep duration, suggesting a new role for MCH in sleep regulation.

Doublecortin as a marker of adult neuroplasticity in the canary song control nucleus HVC.

It is established that in songbirds the size of several brain song control nuclei varies seasonally, based on changes in cell size, dendritic branching and, in nucleus HVC, the incorporation of newborn neurons. In the developing and adult mammalian brain, the protein doublecortin (DCX) is expressed in postmitotic neurons and, as a part of the microtubule machinery, required for neuronal migration. We recently showed that in adult canaries, DCX-immunoreactive (ir) cells are present throughout the telencephalon, but the link between DCX and the active neurogenesis observed in songbirds remained uncertain.

Adenylate kinase-independent thiamine triphosphate accumulation under severe energy stress in Escherichia coli.

Background: Thiamine triphosphate (ThTP) exists in most organisms and might play a role in cellular stress responses. In E. coli, ThTP is accumulated in response to amino acid starvation but the mechanism of its synthesis is still a matter of controversy.

Absence of gonadotropin-releasing hormone 1 and Kiss1 activation in alpha-fetoprotein knockout mice: prenatal estrogens defeminize the potential to show preovulatory luteinizing hormone surges.

Sex differences in gonadal function are driven by either cyclical (females) or tonic (males) hypothalamic GnRH1 release and, subsequently, gonadotrophin (LH and FSH) secretion from the pituitary. This sex difference seems to depend on the perinatal actions of gonadal hormones on the hypothalamus. We used alpha-fetoprotein (AFP) knockout mice (Afp(-/-)) to study the mechanisms by which estrogens affect the sexual differentiation of the GnRH1 system.

Enhanced neural activation in brain regions mediating sexual responses following exposure to a conditioned stimulus that predicts copulation.

Stimuli associated with sexual behavior increase reproductive success if presented prior to copulation. In Japanese quail, inseminations that take place in a context that predicts the arrival of a female are more likely to result in fertilized eggs. We demonstrate here that in male Japanese quail a sexual conditioned stimulus (CS) also enhances activity in two brain regions that mediate sexual behavior, the medial preoptic area and the medial part of the bed nucleus of the stria terminalis.

Regulation of nestin expression by thrombin and cell density in cultures of bone mesenchymal stem cells and radial glial cells.

Background: Bone marrow stromal cells and radial glia are two stem cell types with neural phenotypic plasticity. Bone marrow mesenchymal stem cells can differentiate into osteocytes, chondrocytes and adipocytes, but can also differentiate into non-mesenchymal cell, i.e.

New insights into peripherin expression in cochlear neurons.

Peripherin is an intermediate filament protein that is expressed in peripheral and enteric neurons. In the cochlear nervous system, peripherin expression has been extensively used as a differentiation marker by preferentially labeling the type II neuronal population at adulthood, but yet without knowing its function. Since the expression of peripherin has been associated in time with the process of axonal extension and during regeneration of nerve fibers in other systems, it was of interest to determine whether peripherin expression in cochlear neurons was a static phenotypic trait or rather prone to modifications following nerve injury.

A theoretical experimental method to determine the locus of desensitization.

Consider a ligand-gated channel with n agonist binding sites which can undergo desensitization. We present a theoretical experimental procedure for pinpointing the principal receptor state from which there is a transition to the desensitized state. The method is based on the observation that the dependence of the slope of the time constant of desensitization vs agonist concentration, at low concentrations, represents the state from which desensitization occurs.

Thiamine diphosphate adenylyl transferase from E. coli: functional characterization of the enzyme synthesizing adenosine thiamine triphosphate.

Background: We have recently identified a new thiamine derivative, adenosine thiamine triphosphate (AThTP), in E. coli. In intact bacteria, this nucleotide is synthesized only in the absence of a metabolizable carbon source and quickly disappears as soon as the cells receive a carbon source such as glucose.

Topography in the preoptic region: differential regulation of appetitive and consummatory male sexual behaviors.

Several studies have suggested dissociations between neural circuits underlying the expression of appetitive (e.g., courtship behavior) and consummatory components (i.

Sexual behavior activity tracks rapid changes in brain estrogen concentrations.

Estrogens are classically viewed as hormones that bind to intracellular receptors, which then act as transcription factors to modulate gene expression; however, they also affect many aspects of neuronal functioning by rapid nongenomic actions. Brain estrogen production can be regulated within minutes by changes in aromatase (estrogen synthase) activity as a result of calcium-dependent phosphorylations of the enzyme. To determine the effects of rapid changes in estrogen availability on male copulatory behavior, we mimicked in male mice the rapid upregulation and downregulation of brain estrogen concentration that should occur after inactivation or activation of aromatase activity.

Differential c-fos expression in the brain of male Japanese quail following exposure to stimuli that predict or do not predict the arrival of a female.

We investigated the effects of presenting a sexual conditioned stimulus on the expression of c-fos in male Japanese quail. Eight brain sites were selected for analysis based on previous reports of c-fos expression in these areas correlated with sexual behaviour or learning. Males received either paired or explicitly unpaired presentations of an arbitrary stimulus and visual access to a female.