A Neural Circuit Controlling Virgin Female Aggression Induced by Mating-related Cues in Drosophila / 神经科学通报·英文版

Females increase aggression for mating opportunities and for acquiring reproductive resources. Although the close relationship between female aggression and mating status is widely appreciated, whether and how female aggression is regulated by mating-related cues remains poorly understood. Here we report an interesting observation that Drosophila virgin females initiate high-frequency attacks toward mated females. We identify 11-cis-vaccenyl acetate (cVA), a male-derived pheromone transferred to females during mating, which promotes virgin female aggression. We subsequently reveal a cVA-responsive neural circuit consisting of four orders of neurons, including Or67d, DA1, aSP-g, and pC1 neurons, that mediate cVA-induced virgin female aggression. We also determine that aSP-g neurons release acetylcholine (ACh) to excite pC1 neurons via the nicotinic ACh receptor nAChRα7. Together, beyond revealing cVA as a mating-related inducer of virgin female aggression, our results identify a neural circuit linking the chemosensory perception of mating-related cues to aggressive behavior in Drosophila females.

Resveratrol and Sir2 Reverse Sleep and Memory Defects Induced by Amyloid Precursor Protein / 神经科学通报·英文版

Resveratrol (RES), a natural polyphenolic phytochemical, has been suggested as a putative anti-aging molecule for the prevention and treatment of Alzheimer's disease (AD) by the activation of sirtuin 1 (Sirt1/Sir2). In this study, we tested the effects of RES and Sirt1/Sir2 on sleep and courtship memory in a Drosophila model by overexpression of amyloid precursor protein (APP), whose duplications and mutations cause familial AD. We found a mild but significant transcriptional increase of Drosophila Sir2 (dSir2) by RES supplementation for up to 17 days in APP flies, but not for 7 days. RES and dSir2 almost completely reversed the sleep and memory deficits in APP flies. We further demonstrated that dSir2 acts as a sleep promotor in Drosophila neurons. Interestingly, RES increased sleep in the absence of dSir2 in dSir2-null mutants, and RES further enhanced sleep when dSir2 was either overexpressed or knocked down in APP flies. Finally, we showed that Aβ aggregates in APP flies were reduced by RES and dSir2, probably via inhibiting Drosophila β-secretase (dBACE). Our data suggest that RES rescues the APP-induced behavioral deficits and Aβ burden largely, but not exclusively, via dSir2.

Un primer análisis de la investigación en México sobre los determinantes sociales de la salud: 2005-2012 / A first analysis of research on social determinants of health in Mexico: 2005-2012

Objetivo. Examinar la investigación hecha en México sobre los determinantes sociales de la salud (DSS) durante el periodo 2005-2012 con base en la caracterización del sistema nacional de investigación en salud y la producción científica sobre este tema. Material y métodos. Análisis en dos etapas: revisión documental de fuentes oficiales sobre investigación en salud en México y búsqueda sistemática de literatura sobre DSS. Resultados. Los DSS fueron mencionados en el Programa de Acción Específico de Investigación en Salud 2007-2012, pero no figuran en las estrategias y objetivos; en su lugar, se enfatizan primordialmente aspectos de infraestructura y administrativos. En el periodo se publicaron 145 artículos sobre DSS, cuyas temáticas más abordadas fueron "condiciones de salud", "sistemas de salud" y "nutrición y obesidad". Conclusiones. A pesar de que existe investigación en México sobre DSS, la instrumentación de esos hallazgos en políticas de salud no se ha implementado. El Programa Sectorial de Salud 2013-2018 representa una ventana de oportunidad para posicionar resultados de investigación que promuevan políticas de equidad en salud.

Objective. To examine the research on social determinants of health (SDH) produced in Mexico during the period 2005-2012, based on the characterization of the national health research system and the scientific production on this topic. Materials and methods. Two-stage analyses: Review of Mexican documents and official sources on health research and systematic bibliographic review of the literature on SDH. Results. Although SDH were mentioned in the Specific Action Plan for Health Research 2007-2012, they are not implemented in strategies and goals, as the emphasis is put mostly in infrastructure and administrative aspects of research. In the period studied, 145 articles were published on SDH topics such as health conditions, health systems and nutrition and obesity. Conclusions. In spite of the availability of research on SDH in Mexico, the operationalization of such findings into health policies has not been possible. The current Sectorial Program on Health 2013-2018 represents a window of opportunity to position research findings that promote health equity policies.

Mating latency, duration of copulation and fertility in four species of the Drosophila bipectinata complex.

Significant interspecific variations in mean duration of copulation and fertility were observed in four species of the Drosophila bipectinata species complex. However, D. bipectinata showed positive correlation between duration of copulation and fertility. Similarly, D. malerkotliana showed negative correlation between mating latency and duration of copulation. Likewise, D. pseudoananassae showed positive correlation between mating latency and fertility. These results suggest that D. pseudoananassae has distant relatedness from the other three species with respect to mating latency, duration of copulation and fertility which supports the previous findings.

Further understanding of fat biology: Lessons from a fat fly

Obesity is a leading risk factor for insulin resistance, hypertension, hyperlipidemia, and cardiovascular complications, collectively referred to as metabolic diseases. Given the prevalence of obesity and its associated medical problems, new strategies are required to prevent or treat obesity and obesity-related metabolic effects. Here we summarize contributors of obesity, and molecular mechanisms controlling adipogenesis from studies in mammalian systems. We also discuss the possibilities of using Drosophila as a genetic model system to advance our understanding of players in fat biology.

Reproductive relationships and degree of synapsis in the polytene chromosomes of the Drosophila buzzatii species cluster

O processo de especiação ocorre pela evolução de qualquer uma das diversas formas de isolamento reprodutivo entre táxons, incluindo inviabilidade de híbridos. Neste trabalho, linhagens provenientes de populações alopátricas de espécies de Drosophila do cluster buzzatii foram cruzadas experimentalmente com o objetivo de avaliar suas relações reprodutivas e citogenéticas, e contribuir para o entendimento do isolamento reprodutivo neste grupo de espécies intimamente relacionadas. Os cruzamentos dentro de uma mesma linhagem foram altamente férteis, contudo as diferenças na fertilidade e fecundidade encontradas intra e interespecificamente são discutidas neste artigo. Dos 30 cruzamentos interespecíficos, 63% foram parcialmente ou completamente estéreis. Cinqüenta e três por cento dos cruzamentos de F1 interespecíficos (fêmeas e machos F1 cruzados entre si) também foram parcialmente ou completamente estéreis, em contraste com apenas um, em 24 cruzamentos de F1 intra-específicos, que foi parcialmente estéril. A análise dos cromossomos politênicos nos híbridos revelou sinapse completa, exceto nos microcromossomos (VI) e na região proximal do cromossomo X. A divergência intra-específica e o grau variável de pareamento cromossômico, observados neste estudo, revelam parte da complexidade do processo de especiação pertinente ao cluster buzzatii, o que é consistente com diferentes caracteres estudados neste cluster.

Breeding sites of Neotropical Drosophilidae ( Diptera ): IV. living and fallen flowers of Sessea brasiliensis and Cestrum spp. ( Solanaceae )

As fenologias de floração de quatro espécies de Solanaceae (Sessea brasiliensis, Cestrum amictum, C. schlechtendalii e C. sendtnerianum) presentes em um fragmento de Floresta Atlântica de planalto, encravado na cidade de São Paulo, foram determinadas por observações realizadas entre julho de 1993 e junho de 1995. Durante esses dois anos foram coletadas 33.955 flores das quais emergiram 11.021 moscas pertencentes a cinco espécies de Drosophila do grupo flavopilosa (D. cestri, D. cordeiroi, D. hollisae, D. incompta e D. mariaehelenae) e 1.244 moscas pertencentes a quatro espécies Zygothrica (Z. dispar, Z. vittimaculosa, Z. vittinubila e Z. aff. vittipunctata). Adicionalmente, das flores de S. brasiliensis e Cestrum spp. amostradas emergiram pelo menos outros dez táxons menos abundantes de Drosofilídeos e 1.073 microimenópteros parasitóides (Braconidae, Eucoilidae e Pteromalidae). Flores de Cestrum amictum, C. sendtnerianum e Sessea brasiliensis são registradas pela primeira vez como plantas hospedeiras para as espécies neotropicais de Drosophila pertencentes ao grupo flavopilosa. Os resultados aqui apresentados elevam de nove para onze o número de espécies de Cestrum previamente conhecidas como sítios de desenvolvimento larval dessas moscas. Inclui-se ainda uma lista completa das espécies de Solanaceae que já foram registradas nas regiões sudeste e sul do Brasil como plantas hospedeiras de seis espécies de Drosophila do grupo flavopilosa e de quatro espécies de Zygothrica.

Evidence for minority male mating success and minority female mating disadvantage in Drosophila ananassae

Frequency-dependent mating success was tested for three pairs of wild-type and mutant strains of Drosophila ananassae, MY and yellow body color (y), PN and claret eye color (ca), and TIR and cut wing (ct). The two strains of each pair were chosen for their approximately equal mating propensities. Multiple-choice experiments, using different experimental procedures, were employed. The tests were carried out by direct observation in Elens-Wattiaux mating chambers with five different sex ratios (4:16, 8:12, 10:10, 12:8, and 16:4). There was no assortative mating and sexual isolation between the strains, based on 2 x 2 contingency chi2 analysis and isolation estimate values. One-sided rare male mating advantages were found in two experiments, one for ca males and the other for wild-type males (TIR). However, no advantage was found for rare males in the experiment with MY and y flies. Mating disadvantages for rare females were found for sex-linked mutants (y and ct). Two different observational methods (removal or direct observation of mating pairs) imparted no overall significant effects on the outcome of the frequency-dependent mating tests

No evidence for minority male mating advantage in wild type strains of Drosophila ananassae tested in multiple-choice experiments

Minority male mating advantage was tested in wild type strains of Drosophila ananassae through multiple-choice experiments. Mating success of two types of flies present in five different ratios was scored by direct observation in an Elens-Wattiaux mating chamber. We found no evidence for minority male mating advantage in wild type strains of D. ananassae. The relative mating success of two types of females was also compared in the multiple-choice experiments at different ratios; there was no evidence for a rare female effect. Further, there was similarity in the results of experiments employing different methods. The total number of homogamic and heterogamic matings was obtained by combining the data (all five ratios) from each experiment. Homogamic matings were significantly more frequent than heterogamic ones, which demonstrates preferential mating between males and females of the same strain; this was also supported by a lower isolation estimate. There was also a significant difference in the degree of mating preference between the two strains

Female remating, sperm competition and sexual selection in Drosophila

Female remating is fundamental to evolutionary biology as it determines the pattern of sexual selection and sexual conflict. Remating in females is an important component of Drosophila mating systems because it affects sperm usage patterns and sexual selection. Remating is common in females of many species of Drosophila in both natural and laboratory populations. It has been reported in many insect species and also in vertebrates. Female remating is a prerequisite for sperm competition between males, and the consequences of this competition, such as sperm precedence or sperm displacement, have been reported for many species of Drosophila. Female remating is dependent on the amount of sperm stored, the male seminal fluid components, nutrition, the quantity of eggs laid, experimental design and density of flies in laboratory. Remating by a female is an insurance against male sterility and sub-fertility and increases genetic heterogeneity of female offspring. Remating gives greater female productivity in many species of Drosophila. We examined female remating with respect to sperm competition and sexual selection in Drosophila and addressed the possible benefits for females. We also reviewed the role of accessory gland fluid in remating, costs associated with remating, the genetic basis of female remating and some possible mechanisms of sperm competition in the light of last male sperm priority and paternity assurance in Drosophila and other insects. We also suggest future areas of research.

Choice of oviposition site between surface of the medium and paper in four Indian species of Drosophila.

Choice of oviposition site between surface of the medium and paper positioned vertically on the medium by females was studied in four species of Drosophila: D. ananassae, D. bipectinata, D. malerkotliana, and D. biarmipes. Several geographic strains of these species were used. Females of all the four species laid greater proportions of eggs on the surface of medium as compared to surface of the paper. Thus all the four species tested show preference for oviposition on surface of medium. When the comparison is made for oviposition on paper among the four species, D. ananassae lays more eggs on the surface of paper as compared to other three species.

Incipient sexual isolation in the nasuta-albomicans complex of Drosophila: no-choice experiments.

Drosophila nasuta nasuta and Drosophila nasuta albomicans are cross-fertile races of Drosophila. Hybridization between these races in the laboratory has given rise to new races (Cytoraces), among which karyotypic composition differs from one another and also from those of the parental races. In this study, we search for the evidence of incipient reproductive isolation among the parental races and four Cytoraces by assessing the fraction of no-matings, mating latency and copulation duration in all possible types of homo- and heterogamic crosses (N = 4184). In no-choice conditions, the latency time (time to initiation of copulation) is lower in homogamic crosses than in heterogamic crosses for both parental races and Cytoraces. Latency time and copulation duration are negatively correlated, whereas fraction of no matings is positively correlated with latency time. Thus these six closely related races of the nasuta-albomicans complex show the initiation of the earliest stages of pre-zygotic isolation, manifested as a tendency for matings to be initiated earlier and more often, and for a longer duration, among homogamic rather than heterogamic individuals

Latitudinal variation in eclosion rhythm among strains of Drosophila ananassae.

Eclosion rhythm parameters of D. ananassae strains originating between 8 degrees-34 degrees N were highly variable and latitude dependent. In the field under naturally fluctuating light intensity, temperature and R.H., the amplitude of the rhythm was high and the eclosion gate was narrow; however, under the naturally fluctuating light intensity but at constant temperature and R.H., the amplitude of the rhythm was lowered and the width of eclosion gate was widened. The eclosion rhythm entrained to light-dark (LD) cycles ranging from LD 6:18 to LD 18:6, the width of the eclosion gate was decreased and increased in the short and long photoperiods respectively. Among the strains, both the phase angle difference (psi, the time from lights-off in a 24 hr LD cycle to the eclosion median) and the period of free-running rhythm (tau) in constant darkness varied by about 3 hr and the amplitude of the rhythmicity (Amp) by about 10%. Lower latitude was correlated with late psi (r = -0.69), long tau (r = -0.88) and high Amp value (r = -0.95).

Mating activity and fitness of a few wild type strains of Drosophila ananassae.

Courtship time, duration of copulation and fertility were tested in six wild type strains of D. ananassae originating from different geographical localities. The results indicate that there is significant variation among the strains tested with respect to courtship time, duration of copulation and fertility. The strains showing a longer duration of copulation produce more progeny. These findings suggest that there is a positive correlation between duration of copulation and fertility in D. ananassae.

Mode of mating preference and the direction of evolution in Drosophila.

Sexual (or ethological) isolation constitutes the most important class among different means of reproductive isolation in animal species. The phenomenon of sexual isolation has been extensively studied in the genus Drosophila. The degree of sexual isolation and the mode of mating preference are often used to indicate the phylogenetic relationship between the species and also their evolutionary sequence. Asymmetrical or one-sided mating preference observed in a number of Drosophila species groups has been used to elucidate the direction of evolution. Based on the mode of mating preference, different models which are even opposite to each other have been proposed by different investigators to predict the direction of evolution among closely related species. One-sided mating preference observed among the geographical strains of the same species has also been used to predict the direction of evolution. This review documents several cases of asymmetrical mating preference (both inter- and intraspecific) including the interesting cases reported by Indian workers and in the light of these observations of asymmetry in mating preference, the general applicability of different models is discussed.

Quantitative and qualitative analysis of accessory gland secretory proteins in a few species of Drosophila immigrans group.

Quantitative and qualitative analysis of accessory gland proteins in four species of D. immigrans group has been made. Quantitative estimation of these proteins during development of the adult male revealed that there is a gradual increase in the quantity of secretions up to 7 days. The secretions constitute 72, 70, 50 and 54.2% in D.n. nasuta, D.s. neonasuta, D. rubida and D. pararubida respectively. Mating experiments showed that more than 1/3 of this stored secretory protein is transferred into the female reproductive tract during first mating. SDS-PAGE analysis of the accessory gland secretions revealed remarkable simplicity in their patterns, including the absence of age dependent alterations. In all the 4 species analysed, only the low mol. wt. fractions are not glycosylated. It was further observed that the extent of similarity between D.n. nasuta and D.s. neonasuta is greater than between D. rubida and D. pararubida.

Sex-ratio and mating propensity in Drosophila biarmipes.

Mating success between purple eye colour mutant and wild type D. biarmipes was observed in Elens-Wattiaux mating chamber. Multiple-, female-, male- and no-choice techniques were used. The values of isolation estimate in different experiments are above one which provides no evidence for preferential mating between females and males of the same type. The comparison of sexual behaviour of mutant and wild flies clearly indicates that wild type males are more successful in mating than mutant males, and mutant females are more receptive than wild type females. Thus purple eye colour mutation affects mating propensity of both sexes in D. biarmipes. However, the difference in the number of matings of wild and mutant flies is highly significant in multipe- and no-choice experiments in which sex-ratio was 1:1 (equal number of males and females). But the difference is not significant when mating success was scored by female- and male-choice methods in which sex-ratio was 1:2 (one female and two males; one male:two females). Thus it is suggested that mating propensity in D. biarmipes is influenced by sex-ratio.

Oviposition site preference in four species of Drosophila.

Oviposition site preference which is an important aspect of nonsexual behaviour of adult females was studied in four species of Drosophila, viz. D. ananassae, D. bipectinata, D. malerkotliana and D. biarmipes. The number of eggs laid by females in food vials was counted for 20 days. In each species, eggs were counted in both central and peripheral areas of culture medium. Eggs were also separated into two groups: deposited on the surface of food medium and inserted into the surface of culture medium. Greater proportion of eggs was oviposited in peripheral area of food medium and were inserted into the surface of the medium by females of all the four species. However, there are interspecies variations with respect to oviposition site preference. Further, these species show variation with respect to total fecundity. D. ananassae lays maximum number of eggs whereas D. biarmipes shows lowest rate of fecundity.