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PubMed2000

Sexual dimorphism in diverse metazoans is regulated by a novel class of intertwined zinc fingers.

Sex determination is regulated by diverse pathways. Although upstream signals vary, a cysteine-rich DNA-binding domain (the DM motif) is conserved within downstream transcription factors of Drosophila melanogaster (Doublesex) and Caenorhabditis elegans (MAB-3). Vertebrate DM genes have likewise been identified and, remarkably, are associated with human sex reversal (46, XY gonadal dysgenesis). Here we demonstrate that the structure of the Doublesex domain contains a novel zinc module and disordered tail. The module consists of intertwined CCHC and HCCC Zn(2+)-binding sites; the tail functions as a nascent recognition alpha-helix. Mutations in either Zn(2+)-binding site or tail can lead to an intersex phenotype. The motif binds in the DNA minor groove without sharp DNA bending. These molecular features, unusual among zinc fingers and zinc modules, underlie the organization of a Drosophila enhancer that integrates sex- and tissue-specific signals. The structure provides a foundation for analysis of DM mutations affecting sexual dimorphism and courtship behavior.

Alleles↗

PubMed2000

Changes in egg composition of American kestrels exposed to dietary polychlorinated biphenyls.

Changes in the quality of eggs of birds exposed to polychlorinated biphenyls (PCBs) have been described, but have never been directly attributed to PCBs. Polychlorinated biphenyl residues in eggs have been associated with reduced reproductive success and embryonic deformities in wild birds. Egg size and composition, specifically the amount of albumen, yolk, and water in an egg, also influence the growth and viability of embryos and hatchlings, and consequently the reproductive success of birds. To deter mine whether PCB exposure of adult birds affected the size and composition of their eggs, 25 pairs of captive American kestrels (Falco sparverius) were fed a mixture of PCB-spiked (1248:1254:1260) food to give an approximate exposure of 7 mg/kg body weight/d, beginning 1 mo prior to pairing, and continuing throughout the courtship, egg-laying, and incubation periods. This dietary level in the adult female kestrels resulted in mean total PCB residues in the eggs of 34.1 microg/g wet weight (geometric mean), which is environmentally relevant. PCB residues in eggs increased with the time of female exposure to the contaminated diet and laying date. Variation in egg size within PCB clutches was significantly greater than within control clutches, although absolute egg mass and volume did not differ markedly by treatment. Only infertile eggs and only one egg per clutch were used for egg composition analysis. Yolks in the PCB-contaminated eggs were heavier, with less wet and dry albumen relative to control eggs. Water content and eggshell thickness were not significantly affected by PCB exposure. These results suggest that eggs from the PCB treatment have relatively more lipid and less protein available for embryonic development. Changes in egg composition were not associated with egg size, lay date, ambient temperature, humidity, or precipitation, which are factors known to affect these variables in bird eggs. The PCB-induced changes in egg composition described here provide insight into possible mechanisms contributing to reduced reproductive performance in wild birds exposed to PCBs.

Administration, Oral↗

PubMed2000

Comparison of sexual behaviors between male homosexuals and male heterosexuals in Taiwan.

BACKGROUND: Homosexuality and sexual behavior have attracted great attention in the acquired immunodeficiency syndrome (AIDS) epidemic. This study primarily explores the risky behaviors and patterns of sexual behavior of male homosexuals in Taiwan. METHODS: Comparison study methodology was adopted. Ninety-two male homosexuals, as the study group, were recruited from gay bars and gay organizations, and 91 male heterosexuals, with similar ages and educational levels, were recruited as a control group for comparison. Semi-structured interviews were carried out and anonymous questionnaires were self-administered. RESULTS: (1) The mean age at the time of first sexual intercourse of the study group was younger than that of the control group. (2) The rate of having two or more sexual partners in the study group was significantly higher. (3) However, the rate of condom use during recent intercourse was higher in the control group than in the study group. (4) Sexual knowledge and attitudes toward sexuality in the study group were more open, but their sexual desires, as rated by the questionnaire, were more suppressed than those of the control group. (5) In terms of courtship, the study group was less constrained by the social values of marriage and tended to separate sex from love. CONCLUSION: Similar to western studies, our study found that the study group in Taiwan adopted more risky sexual behaviors. Each group had its particular sexual behavioral pattern and subculture of sexuality. However, a longitudinal follow-up study with ethnographic perspective is necessary for a more sophisticated understanding of the trends and changes of sexual behavior in homosexuals.

Adolescent↗

PubMed2000

Corticosteroid actions from neuronal membrane to behavior: neurophysiological mechanisms underlying rapid behavioral effects of corticosterone.

Investigation of the rapid suppression of male courtship clasping behavior by corticosterone in roughskin newts (Taricha granulosa) has led to the identification of a specific neuronal membrane receptor for this stress steroid. This paper describes studies of the neurophysiological effects of the rapid, membrane receptor mediated action of corticosterone on neurons that are involved in the control of clasping. In freely behaving newts, medullary neurons, including reticulospinal neurons, process clasp-triggering sensory signals and participate in control of clasping movements. Corticosterone injection causes these brainstem neurons to show selective depression of clasping-related sensorimotor function. These corticosterone effects appear in 3-10 min and are closely associated with the simultaneous depression of clasping. In addition to these functionally specific effects, corticosterone simultaneously causes widespread, primarily depressive effects on neuronal activity and excitability in the medulla and elsewhere in the brain. Thus, the membrane actions of corticosterone lead to diverse neural effects, including changes in membrane excitability as well as specific, network-level actions that are apparent only during behavior. These rapid corticosterone effects strongly interact with actions of the neuropeptides vasotocin and corticotropin-releasing factor, such that the form and magnitude of the steroid's effects depend on the prevailing neuroendocrine state of the brain.

Adrenal Cortex Hormones↗

PubMed2000

Sidestepping the altar.

Following several ugly corporate divorces, more hospitals and healthcare systems are deciding to drop their merger plans. They're realizing that it just doesn't make sense to make the trip to the altar, even after long courtships. "Mergers in and of themselves have not been a panacea," one analyst said. "In fact, the reality of mergers has pointed out a lot of shortcomings in the executions, or perhaps in the expectations."

Decision Making, Organizational↗

PubMed2000

Newt prolactin and its involvement in reproduction.

The amino acid sequence of newt (Cynops pyrrhogaster) prolactin deduced from the nucleotide sequence of its cDNA showed a relatively high homology with sequences of chicken and sea turtle prolactins as well as with those of anuran prolactins. Cynops prolactin receptor transcripts were detected in various tissues and organs, suggesting that prolactin plays multiple roles in urodeles. Urodele prolactin was purified from the pituitaries of C. pyrrhogaster. Antiserum against this prolactin was used for radioimmunoassay of plasma prolactin and immunoneutralization experiments. Endogenous prolactin was shown to induce migration to water, courtship behavior, and cessation of spermatocytogenesis in the Cynops newt. The hormone was found to be involved in the development of cloacal glands such as the lateral and abdominal glands, growth of the tail and Mauthner neurons, secretion of oviducal jelly, and enhanced synthesis of a female attracting pheromone (sodefrin), and responsiveness of the olfactory epithelium to sodefrin. In most of these cases, prolactin was found to act synergistically or antagonistically with sex steroids. We also discovered that hypersecretion of prolactin in the newts subjected to cold temperature was induced by hypothalamic stimulation rather than release from hypothalamic inhibition.

Amino Acid Sequence↗

PubMed2001

[Genetic bases for heterogeneity of a population of omnivorous Archips podana Scop. leaf roller moths (Lepidoptera: Tortricidae) by morphological and behavioral traits].

Inheritance of morphological characters related to male and female genitalia was examined in Archips podana Scop. The position and number of aedeagus prongs had a monogenic diallelic mode of inheritance. In contrast to homozygous for P1 (prong A) and heterozygous (prong A + B) males, males homozygous for P2 (prong B) were characterized by much more active courtship. The gene correlates with a set of characters controlling individual ecology, exploring behavior of females, and feeding on different cultures. Morphological adult type 0 is an extremely weak form of phenotype B. Exploring activity of adults having phenotype B is the highest at the ratio of cis-tetradecenol to the other components of the female sex pheromone that leads to a somewhat lower activity of males of other phenotypes. In females, no regularities in inheritance of phenotypic characters were revealed. A hypothesis on a mechanism for maintenance of population stability for the given phenotypes is advanced and a possible mechanism for microevolution of a polymorphic species is proposed.

Animals↗

PubMed2001

[Learning ability and memory formation in the Drosophila mutants with defective central complex and mushroom bodies].

Drosophila proved to be a very convenient model for genetic dissection of learning and memory in a number of experimental paradigms. A battery of mutations affecting either different subdomains of the central complex (CC) or of the mushroom bodies (MBs) enable the elucidation of the role of these central brain structures in different forms of learning and memory formation. We tested the CC mutants cexKS181 and ccbKS127 and MBs mutants mud1, mbm1 and cxbN71 for their ability for learning and memory formation in the conditioned courtship suppression paradigm. All the mutants were able to learn but demonstrated different memory defects. While the ccbKS127 mutant was normal in respect to memory formation, the cexKS181 mutant was defective in 30-min. and 3-hour memory; mud1 demonstrated a reduced 3-hour memory.

Animals↗

PubMed2001

[Comparative study of four P-insertional memory-deficient Drosophila mutants].

The previously suggested physiological model of conditioned courtship suppression in Drosophila was experimentally supported through investigation into the behaviour of the mutant males in two tests: the memory retention test and the retraining test. The mutations disrupted both types of the conditioned connections predicted by the model: association between conditioned and unconditioned stimuli and association between the conditioned stimulus and the aversive motivational system mediating the response to the unconditioned stimulus. The third category of mutants (P95, P124) appears to disrupt the function of the aversive motivational system.

Animals↗

PubMed1975

[Studies on the Sexual Behavior of Cyrtophora cicatrosa (Stolíczka)(Araneae, Araneidae)].

Courtship and copulation behaviour of the tropical spider Cyrtophora cicatrosa were observed in the laboratory. They are described and compared with the behaviour of C. citricola. Emphasis is placed on the roles of pheromones and web tapping, and on the species' different ways of overcoming the problems resulting from extreme sexual dimorphism.

Animal Communication↗

PubMed2001

Drosophila bipectinata species complex.

The Drosophila bipectinata species complex belongs to the ananassae subgroup of the melanogaster species group (Genus Drosophila, Subgenus Sophophora). The members of the complex are: D. bipectinata, D. parabipectinata, D. malerkotliana, and D. pseudoananassae. Of the four species, D. bipectinata is most widely distributed. Females are indistinguishable, but males are distinguishable by their sex-comb teeth number and pattern and by abdominal colouration. Chromosomal inversions have been detected in these species. In natural populations of D. bipectinata the frequency of inversions and the level of inversion heterozygosity were found to be very low but in laboratory stocks inversions persisted for more than 20 generations due to heterotic buffering. On an average 9.3 fixed interspecific inversions separate each species pair. Non-random association between linked inversions indicated epistatic interaction in natural populations of D. bipectinata. Certain spontaneous mutations were detected and mapped for the first time in D. bipectinata. Low frequency of spontaneous male recombination has also been reported in D. bipectinata. Sexual isolation study in the complex indicated strong preference for homogamic mating. The results also indicated incomplete sexual isolation among different members of this complex. The isolation estimate among six different geographic populations of D. bipectinata ranged from 0.54 - 0.92 representing positive assortative mating which is an evidence for incipient sexual isolation. Incipient sexual isolation was also found within D. malerkotliana and D. parabipectinata . Chromosomal, hybridization and allozyme studies revealed close phylogenetic relationship among the four species of the bipectinata complex. Mitochondrial DNA study revealed net nucleotide difference (delta) between these species to be very small (0.0002 +/- 0.0008) reflecting closeness. Evidence for genetic control of sexual activity and existence of sexual selection in D. bipectinata has been shown on the basis of mating propensity tests carried out on geographic strains, their hybrids and diallel crosses. Significant variation was found among the strains tested with respect to courtship time, duration of copulation and fertility. A positive correlation between duration of copulation and fertility in D. bipectinata was found. Evidence for rare-male mating advantage was also found in D. bipectinata. A positive response to selection for high and low mating activity provided evidence for polygenic control of this phenomenon in D. bipectinata. Bilateral outgrowths on thorax, a unique phenotype, reported for the first time in D. bipectinata has been shown to affect mate recognition ability. Results of the study on pupation site preference (larval behaviour) and oviposition site preference (non-sexual behaviour) have also been included.

Animals↗

PubMedDate not supplied

[Reproduction of the bird Mimus gilvus (Passeriformes: Mimidae) in Maracaibo, Venezuela].

Four pairs of the poorly understood tropical mockingbird Mimus gilvus were captured and color banded at a grassland in Maracaibo, Venezuela in June 1997. Throughout the following 8 months, individuals were observed two days per week for 4 hours each. We recorded courtship behaviour, nest construction, incubation, parental care, territory defense and timing of reproductive cycle. Pairs lived in defined territories defended primarily by the male. Both sexes participated in nest building which began at the start of two rainy seasons: April and October. Between April and June, 80% of nests were parasited by the shiny cowbird (Molothrus bonariensis). No parasitism was recorded in the later nesting season. Consequently, breeding success for the April and October seasons was 20% and 83% respectively. Only the female incubated and the mean clutch size was 2.2 eggs.

Animals↗

PubMed1975

[Reproduction of Bothrops moojeni Hoge in captivity].

It is stated that there are sufficient different morphological characteristics in order to distinguish the sexes with a certain practice, but that each of these characteristics by itself does not alone represent a completely valid criterium. These observations have shown in the periods of reproduction a chifting of six months after six years of captivity. Then the various phases of sexual behaviour are related: the male-fight, the courtship, the conquest of the partner by sexual display and finally the copulation. It is established moreover that the period between the copulation and parturition does not necessarily constitute the duration of gestation, which seems in fact shorter because of retarded fertilizations. However, there is quite a constant average of a period of gestation of 200 days. There follows a complete inventory of the 29 copulations and 67 layings that were observed.

Aggression↗

PubMed2002

Domesticated birds as a model for the genetics of speciation by sexual selection.

In theory, even populations occupying identical environments can diverge in sexually selected traits, as a consequence of different mutational input. I evaluate the potential of this process by comparing the genetics of breeds of domesticated birds to what is known about the genetics of differences among species. Within domesticated species there is a strong correlation of time since domestication with the number of breeds. Descendants of the rock dove, Columba livia (the oldest domesticate) show differences in courtship, vocalizations, body shape, feather ornaments (crests and tails) and colors and color patterns. When nine other domesticated species are included there is a striking hierarchy, with more recent domesticates having a nested subset of these traits: the youngest domesticated species have breeds distinguished only by color. This suggests that selection of new, visible, mutations is driving the process of breed diversification, with mutations that appeal to the breeder happening the most frequently in color. In crosses among related species, color, feather ornaments and many vocalizations and displays show both intermediate dominance and pure dominance. Although the number of loci affecting each of these traits is typically unknown, limited evidence of the genetics of species' differences suggests that some differences are due to the substitution of single genes of major effect. While neither the genetics of breeds nor the genetics of species provide a perfect model for the genetics of speciation, similarities between the two are sufficiently striking to infer that major, visible, mutations can provide the impetus underlying new directions of sexual selection.

Acoustic Stimulation↗

PubMed2003

[Male reproductive behavior in Drosophila melanogaster strains with different alleles of the flamenco gene].

The allelic state of gene flamenco has been determined in a number of Drosophila melanogaster strains using the ovoD test. The presence of an active copy of gypsy in these strains was detected by restriction analysis. Then male reproduction behavior was studied in the strains carrying a mutation in gene flamenco. In these experiments mating success has been experimentally estimated in groups of flies. It has been demonstrated that the presence of mutant allele flamMS decreases male mating activity irrespective of the presence or absence of mutation white. The active copy of gypsy does not affect mating activity in the absence of the mutation in gene flamenco. Individual analysis has demonstrated that that mutation flamMS results in characteristic changes in courtship: flamMS males exhibit a delay in the transition from the orientation stage to the vibration stage (the so-called vibration delay). The role of locus flamenco in the formation of male mating behavior in Drosophila is discussed.

Alleles↗

PubMed1992

Mating termination in the male cricket.

The study indicates that the male cricket Gryllus bimaculatus extrudes the spermatophore in response to mechanical stimulation of specialized sensilla in the cavity enclosed by the epiphallus and terminates mating as revealed by spermatophore protrusion. The spermatophore extrusion, however, needs an increase in body tonus during cavity hair stimulation which is produced by male's copulatory actions in response to key stimuli on the dorsum, epiproct and cerci. At the same time, male's sexual excitation raised by courtship facilitates spermatophore extrusion. This is the first demonstration that mating can be artificially switched off in male insects.

Afferent Pathways↗

PubMed2003

Behavioral genetics of Drosophila ananassae.

Drosophila ananassae has a unique status among Drosophila species because of certain peculiarities in its genetic behavior. The most unusual feature of this species is its relatively high frequency of spontaneous male recombination. The results of studies on non-sexual behavior, such as phototactic responses, eclosion rhythm, and preferences for oviposition and pupation sites, lead us to suggest that this behavior is under polygenic control, with a substantial amount of additive genetic variation. Sexual isolation has been reported in D. ananassae with the degree of such isolation being stronger in isofemale lines than in natural populations. The significant variations seen in the mating propensity of several isofemale strains, inversion karyotypes and wild type strains, the diminishing effects of certain mutations on the sexual activity of males, and the positive responses to selection for high and low mating propensity point to a genetic control of sexual behavior in D. ananassae. Males contribute more to variation and thus are more subject to intrasexual selection than females. There is a positive correlation between sternopleural bristle number, mating propensity and fertility in D. ananassae. This correlation between morphometric traits and mating success suggests that larger flies are more successful in mating than smaller ones. There is also evidence for adaptive plasticity and a trade-off between longevity and productivity in D. ananassae. Rare, specific courtship song parameters that provide males with a mating advantage have also been reported in different geographic strains of D. ananassae. The remating behavior of males and females, sperm displacement, and the bi-directional selection for female remating speed indicate that post-mating behavior in this species may also be under genetic control. The occurrence of size assortative mating further indicates that there is size-dependent sexual selection in D. ananassae.

Animals↗

PubMed2005

Finally, after 16 years of trying to tie the knot, Ohio city's two acute-care hospitals have put half a century of competition behind them.

It was a long, dramatic courtship. Finally, after 16 years and two frustrating tries, Springfield, Ohio's two acute-care hospitals have completed their merger, ending a half-century of competition. City leaders call the deal a testament to the two hospitals' boards and leaders. A. David Jimenez, left, an executive at Catholic Healthcare Partners, says that ultimately, it is the community that must come first.

Catholicism↗