Rapid effects of aromatase inhibition on male reproductive behaviors in Japanese quail

Non-genomic effects of steroid hormones on cell physiology have been reported in the brain. However, relatively little is known about the behavioral significance of these actions. Male sexual behavior is activated by testosterone partly through its conversion to estradiol via the enzyme aromatase in the preoptic area (POA). Brain aromatase activity (AA) changes rapidly which might in turn be important for the rapid regulation of behavior. Here, acute effects of Vorozole, an aromatase inhibitor, injected IP at different doses and times before testing (between 15 and 60 min), were assessed on male sexual behavior in quail. To limit the risk of committing both types of statistical errors (I and II), data of all experiments were entered into a meta-analysis. Vorozole significantly inhibited mount attempts (P < 0.05, size effect [g] = 0.527) and increased the latency to first copulation (P < 0.05, g = 0.251). The treatment had no effect on the other measures of copulatory behavior. Vorozole also inhibited appetitive sexual behavior measured by the social proximity response (P < 0.05, g = 0.534) or rhythmic cloacal sphincter movements (P < 0.001, g = 0.408). Behavioral inhibitions always reached a maximum at 30 min. Another aromatase inhibitor, androstatrienedione, induced a similar rapid inhibition of sphincter movements. Radioenzyme assays demonstrated that within 30 min Vorozole had reached the POA and completely blocked AA measured in homogenates. When added to the extracellular milieu, Vorozole also blocked within 5 min the AA in POA explants maintained in vitro. Together, these data demonstrate that aromatase inhibition rapidly decreases both consummatory and appetitive aspects of male sexual behavior.     

Learning enhances female control over reproductive investment in the Japanese quail

The adaptive significance of learning is supported by studies showing its positive effects on mating behaviour, but they rarely go beyond fertilization success. Here we studied how learning contributes to qualitative reproductive investment, by testing the hypothesis that mating in the context that predicts male appearance has positive effects on female reproductive investment compared with unsignalled mating. Using Japanese quail (Coturnix japonica), we found that effects of mating in the context predicting mating opportunity depend on female body condition and receptivity, while the outcome of unexpected mating depends on male behaviour. In particular, among females mated with the familiar male in the context predicting that he will appear, female condition positively affected the number of fertilized eggs and egg mass and more receptive females tended to produce more sons. Additionally, conditioned females laid heavier eggs for daughters than for sons. In contrast, in females that were mated unexpectedly and with a novel male, the number of fertilized eggs was highly dependent on male behaviour and was negatively related to maternal body condition. Egg mass was not related to body condition, and there were no indications of sex allocation. This is, to our knowledge, the first study demonstrating how female body condition and behaviour interact with the context of mating in shaping maternal reproductive investment.     

Yeast as a model system for studying endocytosis.

Endocytosis is the membrane trafficking process by which plasma membrane components and extracellular material are internalized into cytoplasmic vesicles and delivered to early and late endosomes, eventually either recycling back to the plasma membrane or arriving at the lysosome/vacuole. The budding yeast Saccharomyces cerevisiae has proven to be an invaluable system for identifying proteins involved in endocytosis and elucidating the mechanisms underlying internalization and postinternalization events. Through genetic studies in yeast and biochemical studies in mammalian cells, it has become apparent that multiple cellular processes are linked to endocytosis, including actin cytoskeletal dynamics, ubiquitylation, lipid modification, and signal transduction. In this review, we will highlight the most exciting recent findings in the field of yeast endocytosis. Specifically, we will address the involvement of the actin cytoskeleton in internalization, the role of ubiquitylation as a regulator of multiple steps of endocytosis in yeast, and the sorting of endocytosed proteins into the recycling and vacuolar pathways.     

Age-related reproductive decline in the male Japanese quail

A series of experiments was conducted to study the decline in reproduction associated with age in the male Japanese quail. In Experiment 1, eggs were collected from pairs that were 28, 56, 107, and 149 weeks of age. Pairs that were 56 weeks of age or older showed a sharp drop in fertility and hatchability. Subsequent experiments were designed to study the endocrine and behavioral basis for this decline in the male. In Experiment 2, males that were between 23 and 70 weeks of age were tested for mating behavior, plasma testosterone was measured, and testes wet weight was determined. There were no significant differences between the age groups. However, samples taken from an additional group of males 168 weeks of age showed significantly (P < 0.05) lower serum testosterone and testes weight. Therefore, the third experiment was designed to include age groups of males between 4 and 126 weeks of age in order to further examine this decline in males older than 70 weeks of age. There was a significant (P < 0.05) drop in this number of males showing sexual behavior and of those males showing sexual behavior; the quantity of mating activity also declined. Plasma testosterone was reduced in the older groups; however, the change was not significant. In addition, the size of the cloacal gland, an androgen-dependent organ, declined with age (P < 0.05). These results argue that the age-related reproductive decline may have behavioral as well as endocrine basis. Possibly, the behavioral changes may result from altered receptor sensitivity at the level of areas of the brain, which control reproductive behavior, and at the level of the testes, which affect hormone production and spermatogenesis.     

Japanese quail (Coturnix japonica) as a laboratory animal model

For the past 50 years, the Japanese quail (Coturnix japonica) has been a popular animal model in numerous fields of research. The quail's 16-d developmental period and its easily accessible embryo make C. japonica a convenient model for studies of developmental biology. Because its lifespan is relatively short and its physiology is comparable to that of humans, the adult quail is useful for studies of aging and disease. The authors describe the Japanese quail as an animal model and, drawing on their experience raising a quail colony at the California Institute of Technology, present detailed guidelines for the husbandry of the species.     

Yeast as a model system for studying lipid homeostasis and function

Lipids are essential eukaryotic cellular constituents. Lipid metabolism has a strong impact on cell physiology, and despite good progress in this area, many important basic questions remain unanswered concerning the functional diversity of lipid species and on the mechanisms that cells employ to sense and adjust their lipid composition. Combining convenient experimental tractability, a large degree of conservation of metabolic pathways with other eukaryotes and the relative simplicity of its genome, proteome and lipidome, yeast represents the most advantageous model organism for studying lipid homeostasis and function. In this review we will focus on the importance of yeast as a model organism and some of the innovative advantages for the lipid research field.     

The Dugesia ryukyuensis database as a molecular resource for studying switching of the reproductive system

The planarian Dugesia ryukyuensis reproduces both asexually and sexually, and can switch from one mode of reproduction to the other. We recently developed a method for experimentally switching reproduction of the planarian from the asexual to the sexual mode. We constructed a cDNA library from sexualized D. ryukyuensis and sequenced and analyzed 8,988 expressed sequence tags (ESTs). The ESTs were analyzed and grouped into 3,077 non-redundant sequences, leaving 1,929 singletons that formed the basis of unigene sets. Fifty-six percent of the cDNAs analyzed shared similarity (E-value<1E -20) with sequences deposited in NCBI. Highly redundant sequences encoded granulin and actin, which are expressed in the whole body, and other redundant sequences encoded a Vasa-like protein, which is known to be a component of germ-line cells and is expressed in the ovary, and Y-protein, which is expressed in the testis. The sexualized planarian expressed sequence tag database (http://planaria.bio.keio.ac.jp/planaria/) is an open-access, online resource providing access to sequence, classification, clustering, and annotation data. This database should constitute a powerful tool for analyzing sexualization in planarians.     

Volvox carteri as a model for studying the genetic and cytological control of morphogenesis

The green alga Volvox carteri has a very simple and regular adult form that arises through a short sequence of well-defined morphogenetic steps. A mature gonidium (asexual reproductive cell) initiates a stereotyped sequence of rapid cleavage divisions that will produce all of the cells found later in an adult. A predictable subset of these divisions are asymmetric and result in production of a small set of germ cells in a precise spatial pattern. Throughout cleavage, all intracellular components are held in predictable spatial relationships by a cytoskeleton of unusually regular structure, while neighboring cells are also held in fixed spatial relationships by an extensive network of cytoplasmic bridges that form as a result of incomplete cytokinesis. As a result of these two orienting mechanisms combined, dividing cells are arranged around the anterior-posterior axis of the embryo with precise rotational symmetry. These relationships are maintained by the cytoplasmic bridge system when the embryo that was inside out at the end of cleavage turns right-side out in the gastrulation-like process of inversion. Inversion is driven by a cytoskeleton-mediated sequence of cell shape changes, cellular movements and coordinated contraction. Then, by the time the cytoplasmic bridges begin to break down shortly after inversion, a preliminary framework of extracellular matrix (ECM) has been formed. The ECM traps the cells and holds them in the rotational relationships that were established during cleavage, and that must be maintained in order for the adult to be able to swim. Transposon tagging is now being used to clone and characterize the genes regulating these morphogenetic processes.     

Stimulus control of social behaviour in male Japanese quail,Coturnix coturnix japonica

Three experiments were conducted to identify stimuli that control social proximity behaviour and suppression of crowing in male Japanese quail. Visual access to a conspecific female through a narrow window stimulated both social proximity and suppression of crowing in male quail. These responses did not occur when male conspecifics, birds of other species, or an empty cage were visible through the window. Taxidermically prepared models of female and male quail elicited differential social proximity behaviour and crowing suppression similar to the differential responses elicited by live female and male conspecifics. Thus, static visual cues of female quail were sufficient to stimulate social proximity behaviour and suppression of crowing in males. Much of the behaviour elicited by female and male models was controlled by visual cues provided by the head and neck, which contain most of the sexually dimorphic feathers. Visual features of the head and neck appeared to be additive in their effects on social behaviour.     

Manifestations of social stress in grouped Japanese quail

Physiological manifestations of social stress in stable and unstable (resident and visitor) pairs of adult male Japanese quail (Coturnix coturnix japonica) were compared after 7, 14, 21 and 28 days of regrouping. Unstable pairs had reduced body and relative testes (mg/100 g) weights. Plasma cholesterol was increased significantly in unstable pairs, and adrenal cholesterol was reduced significantly by daily regrouping of unstable pairs. Twelve consecutive days of ACTH treatment (2, 4 or 8 IU/100 g body wt given intramuscularly) to birds in stable pairs induced a decrease in body and relative testes weights. The results were similar to those found in birds subjected to daily regrouping.     

ICF syndrome cells as a model system for studying X chromosome inactivation

Mutations in the DNMT3B DNA methyltransferase gene cause the ICF immunodeficiency syndrome. The targets of this DNA methyltransferase are CpG-rich heterochromatic regions, including pericentromeric satellites and the inactive X chromosome. The abnormal hypomethylation in ICF cells provides an important model system for determining the relationships between replication time, CpG island methylation, chromatin structure, and gene silencing in X chromosome inactivation.     

Influenza as a model system for studying the cross-species transfer and evolution of the SARS coronavirus

Severe acute respiratory syndrome coronavirus (SARS-CoV) moved into humans from a reservoir species and subsequently caused an epidemic in its new host. We know little about the processes that allowed the cross-species transfer of this previously unknown virus. I discuss what we have learned about the movement of viruses into humans from studies of influenza A, both how it crossed from birds to humans and how it subsequently evolved within the human population. Starting with a brief review of severe acute respiratory syndrome to highlight the kinds of problems we face in learning about this viral disease, I then turn to influenza A, focusing on three topics. First, I present a reanalysis of data used to test the hypothesis that swine served as a "mixing vessel" or intermediate host in the transmission of avian influenza to humans during the 1918 "Spanish flu" pandemic. Second, I review studies of archived viruses from the three recent influenza pandemics. Third, I discuss current limitations in using molecular data to study the evolution of infectious disease. Although influenza A and SARS-CoV differ in many ways, our knowledge of influenza A may provide important clues about what limits or favours cross-species transfers and subsequent epidemics of newly emerging pathogens.     

Drosophila as a model system for studying lifespan and neuroprotective activities of plant-derived compounds

The fruit fly, Drosophila melanogaster, has been intensively used as a genetic model system for basic and applied research on human neurological diseases because of advantages over mammalian model systems such as ease of laboratory maintenance and genetic manipulations. Disease-associated gene mutations, whether endogenous or transgenically-inserted, often cause phenotypes in vivo that are similar to the clinical features of the human disorder. The Drosophila genome is simpler than that of mammals, in terms of gene and chromosome number, but nonetheless demonstrates extraordinary phylogenetic conservation of gene structure and function, especially notable among the genes whose mutations cause neurodevelopmental, neuropsychiatric, or neurodegenerative disorders. In addition, its well-established neuroanatomical, developmental, and molecular genetic research techniques allow many laboratories worldwide to study complex biological and genetic processes. Based on these merits of the Drosophila model system, it has been used for screening lifespan expansion and neuroprotective activities of plant extracts or their secondary metabolites to counteract pathological events such as mitochondrial damage by oxidative stress, which may cause sporadic neurodegenerative diseases. In this review, we have summarized that the fruit fly can be used for early-stage drug discovery and development to identify novel plant-derived compounds to protect against neurodegeneration in Alzheimer's disease and Parkinson's disease, and other neurological disorders caused by oxidative stress. Thus, the Drosophila system can directly or indirectly contribute to translational research for new therapeutic strategies to prevent or ameliorate neurodegenerative diseases.     

Variability of yolk testosterone concentrations during the reproductive cycle of Japanese quail

Deposition of yolk androgens can vary among females as well as within eggs of one female. Numerous external and internal factors can contribute to this variability. In our study, we investigated the systemic variation of yolk testosterone concentrations during the laying cycle of Japanese quail reared in stable environmental and social conditions. Testosterone was analysed in three eggs collected per female at the beginning, top and the end of a reproductive period and the extent of inter- and intra-female differences in yolk deposition of this androgen was quantified. Yolk testosterone concentrations and the yolk testosterone content decreased from the early to the latest stage of reproductive period. Testosterone concentrations in the egg yolk as well as the age-dependent pattern significantly differed among individual females. We found high repeatability of yolk testosterone among 3 eggs of individual females together with high repeatability between 3 stages of the reproductive cycle. Testosterone in the egg yolk correlated positively with eggshell weight. Our results suggest that precocial birds with long laying sequences display higher inter-female differences in yolk testosterone concentrations compared with intra-individual variability. The decreased testosterone deposition with age may influence the development and behaviour of the young hatched at different stages of the female's reproductive cycle.     

A nonlinear model for studying oscillations in the blood pressure control system

The idea that physiological systems sometimes include oscillations as part of their control function is a relatively new idea; the paper discusses the role of such oscillations in the regulation of arterial blood pressure and how they can be studied by modelling techniques. A nonlinear model is proposed which can be related directly to the physiology. This is seen as an important step because mainly previous studies of biological oscillations have used lumped equations, e.g. the Van der Pol equation, which do not possess this property. On the basis of the model, the oscillatory behaviour of the blood pressure control system is analysed by the application of the dual input describing function technique, a powerful analytical method which has wide application to the study of nonlinear oscillatory phenomena in physiology.The final section of the paper considers the digital simulation of the model by Z transform techniques and how the simulation can be used to study the interaction of respiratory and blood pressure control systems.