Differential lethality following treatment with ionizing radiations of various energies inDrosophila

Summary Male and female gametes ofDrosophila were treated with various doses of ionizing radiations: X-rays at different energy, and gamma-rays from 2 sources given singly and in 2 temporal sequences. The induced lethality was assessed in successive developmental stages by scoring the number of eggs, larvae and adults. The results clearly show that the effects of various radiations appear in terms of difference among developmental stages and/or between treated sexes/genotypes. It is suggested that the various energies affected different gene functions which are not completely independent, as supported by the non-additive effects of the two temporal sequences.Acknowledgments. The authors wish to thank Prof. D.L. Palenzona for valuable discussion and criticism and Mrs C. Brunaleschi and Mr E. Boschieri for their technical assistance.     

Differential lethality following treatment with ionizing radiations of various energies in Drosophila

Male and female gametes of Drosophila were treated with various doses of ionizing radiations: X-rays at different energy, and gamma-rays from 2 sources given singly and in 2 temporal sequences. The induced lethality was assessed in successive developmental stages by scoring the number of eggs, larvae and adults. The results clearly show that the effects of various radiations appear in terms of difference among developmental stages and/or between treated sexes/genotypes. It is suggested that the various energies affect different gene functions which are not completely independent, as supported by the non-additive effects of the two temporal sequences.     

Preferential destruction of chloroplast nucleoids in zygotes in green algaeDictyosphaeria cavernosa andAcetabularia calyculus

Summary The preferential destruction of chloroplast nucleoids in young zygotes in the coenocytic algaDictyosphaeria cavernosa and the giant unicellular algaAcetabularia calyculus was studied by high resolution epifluorescent microscopy. The chloroplast nucleoids (DNA) in the chloroplast from one of the parents were preferentially destroyed soon after the mating of male and female gametes.     

L'acide borique,inhibiteur de la copulation gamétique chezAllomyces

Summary Addition of a tiny crystal of boric acid to a drop of buffered water containing male and female gametes ofEuallomyces javanicus completely inhibits copulation in this water mold.Pure gametophytic growth can thus be secured by addition of 1/15,000 boric acid to the starch-yeast extract medium.

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Communication annoncée mais non présentée au VIII^e Congrès international de Botanique, Paris 1954.     

The potency of male accessory gland material in the mosquito (Aedes aegypti)

Summary Injections of male accessory gland material fromAedes aegypti into the hemocoeles of virgin female mosquitoes indicate that the potency of the secretion is equivalent to the amount of semen which a male normally places within the female. This estimation is far less than had been previously calculated. It is suggested that the termmatrone for male accessory gland material is inappropriate since it does not convert a maid into a matron but prevents reinsemination of an impregnated female.Scientific Article No. A2098, Contribution No. 5054 of the Maryland Agricultural Experiment Station.     

Germline development in vertebrates and invertebrates

In all animals information is passed from parent to offspring via the germline, which segregates from the soma early in development and undergoes a complex developmental program to give rise to the adult gametes. Many aspects of germline development have been conserved throughout the animal kingdom. Here we review the unique properties of germ cells, the initial determination of germ cell fates, the maintenance of germ cell identity, the migration of germ cells to the somatic gonadal primordia and the proliferation of germ cells during development in vertebrates and invertebrates. Similarities in germline development in such diverse organisms as Drosophila melanogaster, Caenorhabditis elegans, Xenopus laevis and Mus musculus will be highlighted. Received 11 December 1998; received after revision 25 January 1999; accepted 25 January 1999     

Parallels between sexual strategies and other allocation strategies

Allocation strategies in which a limited resource is apportioned among alternative activities are applicable to diverse structural, genetical and behavioral topics, including male versus female investments. In a model of sex allocation strategies, the absolute fitness of individuals are calculated by summing the production of male and female gametes or offspring, each weighted by its reproductive value. The ESS is obtained by examining the fitness advantage of one phenotype over another. An analogous method is used to obtain a general model of allocation strategies that incorporates some widespread features. Allocation strategies are affected by the sizes and shapes of the reward curves, stochastic factors, and constraints on the allocations permitted. A number of parallels among diverse types of allocation strategies, including the occurrence of fixed, conditional and mixed strategies, and matching rules, are discussed.     

Parallels between sexual strategies and other allocation strategies

Summary Allocation strategies in which a limited resource is apportioned among alternative activities are applicable to diverse structural, genetical and behavioral topics, including male versus female investments. In a model of sex allocation strategies, the absolute fitnesses of individuals are calculated by summing the production of male and female gametes or offspring, each weighted by its reproductive value. The ESS is obtained by examining the fitness advantage of one phenotype over another. An analogous method is used to obtain a general model of allocation strategies that incorporates some widespread features. Allocation strategies are affected by the sizes and shapes of the reward curves, stochastic factors, and constraints on the allocations permitted. A number of parallels among diverse types of allocation strategies, including the occurrence of fixed, conditional and mixed strategies, and matching rules, are discussed.     

2-Phenylethanol,a presumed sexual stimulant produced by the male cabbage looper moth,Trichoplusia ni

Summary A sex pheromone produced by male cabbage looper moths,Trichoplusia ni (Hübner), has been isolated from the genital scent brushes and identified as 2-phenylethanol. It is shown conclusively to elicit specific behavioural responses in the female (such as wing vibration and abdominal elevation), as determined by a novel behavioural laboratory bioassay. This is taken as further evidence that the male pheromone ofT. ni acts as a sexual stimulant (aphrodisiac) prior to mating. 2-Phenylethanol represents the first identification of a genital scent brush pheromone in the family Noctuidae, and of a male pheromone in the subfamily Plusiinae.Mention of a proprietary product in this paper does not constitute a recommendation or an endorsement of the product by the U. S. Department of Agriculture.     

Intrapopulational genetic variation in the hybridization betweenDrosophila melanogaster females andD. simulans males

Summary Intrapopulational variation on interspecific crossing ability betweenD. melanogaster andD. simulans has been measured. When themelanogaster females andsimulans males were crossed, hybridization ranged from 3 to 34%, the female component of variation being more important than the male component. This point is discussed in relation with the role played by each sex in sexual isolation.     

Sexual behavior mutants revisited: molecular and cellular basis of Drosophila mating

The study of Drosophila melanogaster by a combination of forward genetics with specific mutants, and reverse genetics, in which a given gene is expressed in an appropriate brain area to test its effect on behavior, provides a unique opportunity to explore the causal relationship between a particular gene, its function in the cell and the behavioral outcome at the organismic level. Enhanced male-to-male courtship has been shown to occur as a result of mutations in several different genes. For example, the Voila mutant exhibits intense GAL4 reporter expression in the tarsal gustatory sensilla, suggesting the importance of tapping by a male on the female abdomen with his forelegs. Feminization of parts of the antennal lobe and mushroom body by targeted expression of a female-determining gene transformer ⁺ (tra ⁺) drives the male to court other males. Mutations in the tra target gene fruitless (fru), which is expressed in the antennal lobe as well as the suboesophageal ganglion (the gustatory inputs are processed here), also induce homosexual courtship in males. These results suggest that sensory inputs mediated and/or processed by the tarsal receptors, suboesophageal ganglion, antennal lobe and mushroom body contribute to the regulation of male–female courtship. Mosaic analysis localized the neural center for male courtship behavior to the posterior dorsal brain, in which the sensory information processed by the aforementioned neural structures may be integrated. Another mosaic study mapped the neural center for female sexual behavior, as measured by her receptiveness to copulation, to the anterior dorsal brain. The issue as to how the mutations that reduce female sexual receptiveness, e.g. dissatisfaction (dsf), spinster (spin) and chaste (cht), affect the structure and/or function of this neural center deserves to be addressed urgently. Received 27 April 1999; received after revision 21 June 1999; accepted 8 July 1999     

Un nouveau type de détermination chromosomique du sexe chez les mammifèresEllobius lutescens Th. etMicrotus (Chilotus) oregoni Bachm. (Muridés-Microtinés)

Summary (1)Ellobius lutescens andMicrotus oregoni show the same type of sex-chromosomes. The diploid number is odd in both sexes, seventeen.(2) The odd element ofEllobius is morphologically alike in the male and in the female. InM. oregoni, the odd element of the male is acrocentric, that of the female metacentric.(3) Following a hypothesis ofWhite, it seems very probable that the heterochromosome of the male is built of the primitiveY (short arm) and the primitiveX (long arm) linked together. In the female of the same species (M. oregoni), the sex-chromosome represents both theX fused together.(4) Only the half of the Zygotes may develope, the other half being lethal.(5) The close kinship betweenEllobius andM. oregoni is certain, a parallel evolution appearing as highly improbable.     

Gamete formation reflects the sexual pheromone hierarchy ofDictyostelium giganteum

Summary Sexual development inDictyostelium giganteum begins with the appearance of small, amoeboid gametes that fuse to produce mainly binucleate cells which differentiate into zygote giant cells. The data presented here show that the number of gametes produced by each strain (WS589>WS606>WS607>WS588) is directly related to its position in this hierarchy.This work was supported by a grant (A6807) from the Natural Sciences and Engineering Research Council of Canada.     

Regulation of male sex determination: genital ridge formation and Sry activation in mice

Sex determination is essential for the sexual reproduction to generate the next generation by the formation of functional male or female gametes. In mammals, primary sex determination is commenced by the presence or absence of the Y chromosome, which controls the fate of the gonadal primordium. The somatic precursor of gonads, the genital ridge is formed at the mid-gestation stage and gives rise to one of two organs, a testis or an ovary. The fate of the genital ridge, which is governed by the differentiation of somatic cells into Sertoli cells in the testes or granulosa cells in the ovaries, further determines the sex of an individual and their germ cells. Mutation studies in human patients with disorders of sex development and mouse models have revealed factors that are involved in mammalian sex determination. In most of mammals, a single genetic trigger, the Y-linked gene Sry (sex determination region on Y chromosome), regulates testicular differentiation. Despite identification of Sry in 1990, precise mechanisms underlying the sex determination of bipotential genital ridges are still largely unknown. Here, we review the recent progress that has provided new insights into the mechanisms underlying genital ridge formation as well as the regulation of Sry expression and its functions in male sex determination of mice.     

A new pattern of hermaphroditism (inducible hermaphroditism) in populations ofOphryotrocha labronica (Annelida Polychaeta)

Summary A new kind of hermaphroditism, which is called inducible hermaphroditism, has been discovered in the otherwise gonochoristic populations ofOphryotrocha labronica of the Gulf of Naples and of the Lagune of Venice. Inducible hermaphrodites, which are fertile in both the male and female phases, represent 25.8% and 31.8% of the Naples and Venice strains respectively. Inducible hermaphrodites are obtained when pairs between adult females — or female phase hermaphrodites — and juveniles are formed. Crosses between inducible hermaphrodites, in different sex phases, pure male and female individuals give progenies whose sex ratios are clearly correlated with the sex genotypes of the parents.     

Ontogenetische Änderungen im Gehalt an Isoxanthopterin bei verschiedenen Genotypen vonDrosophila melanogaster

Summary The content of isoxanthopterine in different developmental stages and different genotypes ofDrosophila melanogaster has been investigated. In male pupae of the red eyed wild type the isoxanthopterine reaches a high concentration which is maintained during the whole period of imaginal life. It could be shown that the mutantsw (white) andbw (brown) though they are unable to synthesize the red eye pigment do nonetheless accumulate considerable quantities of isoxanthopterine during metamorphosis. This isoxanthopterine, however, disappears gradually from the body ofw andbw during the first 3 days of imaginal life till nothing of it is left in adult flies. The transitory appearance of isoxanthopterine in the two mutants, sets new problems with regard to the pleiotropic effect of thew- andbw-loci in pigment synthesis.     

Octopamine levels during the moult cycle and adult development in the migratory locust,Locusta migratoria

Summary Octopamine content of the head of the locustLocusta migratoria has been determined during the last larval stage, moulting and adult life of 3 groups of insects: female and male gregarious, solitary and CO₂ solitarized. An important difference was found between these 3 groups. Octopamine contents increased in the middle of the larval life and during the adult life. The moulting time is characterized by a sharp decrease of the octopamine content which becomes identical in the 3 groups of insects. The relation between octopamine content, hormone cycles and motility is discussed.     

Effect of progesterone on male and female sex behavior induced by steroid hormones in adult ovariectomized ewes]

Ovariectomized adult Ewes daily treated with I/M injections of testosterone propionate (10 mg/day) or oestradiol benzoate (200 microgram/day) show male-like sexual behaviour and simultaneously a permanent female receptivity. Additional daily treatment with 100 mg of progresterone results in a rapid decrease in male sexual responses both when Ewes are treated with testosterone and with oestradiol. No effect is observed on the female receptivity. Cyproterone acetate (100 mg/day) given to Ewes in addition to daily injection of testosterone propionate (10 mg/day) has effects similar to those of progesterone. These results show that progesterone has antiandrogen and antioestrogen properties and that this hormone administered at high doses is able to inhibit male activity.     

Consequences of experimental triploidy on the fertility and sexual differentiation of a normally amphigonic and diploid lombrician, Eisenia foetida Sav]

The fertility of experimental triploid worms has been studied in Eisenia foetida Sav. This study has led us to the conclusion that the female germ line is abortive while the male germ line may as an exception take part in fertilization. Histological controls have confirmed the differentiating ability of the male line and the break in the development of the female line.     

Chemical components of the rectal gland secretions of maleDacus cucurbitae,the melon fly

Summary The volatile constituents of the rectal gland secretion of maleDacus cucurbitae have been shown to contain 2-methoxy-N-3-methylbutyl acetamide together with 2 other amides, 3 pyrazine derivatives and 2-ethoxybenzoic acid. Excised male rectal glands have been demonstrated to elicit strong responses from female melon flies.Acknowledgment. We thank Dr P. Howse for valuable discussions and advice.