Investigation of Novel Circuits Involved in Virgin Female Receptivity of Drosophila melanogaster

Courtship is a behavior that allows the display of fitness of one sex to the other and gates possible subsequent mating. This behavior is crucial for reproduction and has strong innate components in all animals. Courtship in Drosophila melanogaster consists of a series of highly stereotyped actions that the male performs towards the female. He sings with vibrations of the wings, touches and licks her abdomen, while she evaluates the information presented to her.(...)

Nutritional plasticity and evolutionary divergence in the Drosophila ovary

The environment can modify developmental trajectories and generate a range of distinct phenotypes without altering an organism’s genome, a widespread phenomenon called developmental plasticity. The past decades have seen a resurgent interest in understanding how developmental plasticity contributes to evolutionary processes, as it can produce phenotypic variation among individuals and facilitate diversification among populations that inhabit distinct ecological niches. To better understand the importance of plastic responses for evolutionary change, we need to explore how the environment alters development to produce phenotypic variation and then compare this to how genetic variation influences these same developmental processes.(...)

The Role of the Fbox Protein CG6758 in Xbp1s Induced Retinal Degeneration in Drosophila

The Unfolded Protein Response (UPR) is a signaling pathway that is activated by an accumulation of unfolded or misfolded proteins in the endoplasmic reticulum (ER) that causes ER stress. The activation of the UPR aims to restore ER homeostasis by attenuation of ER client protein translation, increased transcription of ER chaperones and ER associated degradation (ERAD) factors. If ER stress is too long or too strong, cells may die. The main signaling branch of the UPR is mediated by the ER transmembrane protein IRE1 and the transcription factor Xbp1. The active, spliced form of Xbp1 (Xbp1spliced) acts as a transcription factor with protective function against toxic protein aggregation. However, overexpression of Xbp1spliced in the developing Drosophila eye causes degeneration of the eye (“glossy” eye phenotype).(...)

Estudio de los mecanismos moleculares involucrados en la inmunosupresión observada durante la infección con Trypanosoma cruzi: Rol de la vía PD-1/PD1-L y E3 ubiquitina ligasas. Molecular mechanismns involved in the immunosupression during Tryapanosoma cruzi infection. Role of PD1-PD1-L pathway and E3 ubiquitin ligases.

Trypanosoma cruzi es el agente causal de la enfermedad de Chagas, un problema de salud importante en América Latina, así como también en América Central, ya que causa infección crónica afectando a millones de personas [1]. Durante esta enfermedad se han descripto varias alteraciones de la respuesta inmune, entre ellas una severa inmunosupresión durante la etapa aguda de la infección, tanto en humanos como en ratones. Células T provenientes de ratones infectados activadas in vitro, muestran reducción en la respuesta proliferativa a mitógenos, característica de un estado de inmunosupresión [2-4]. La falla del sistema inmune durante estadios tempranos de la infección probablemente colabore con la diseminación y el establecimiento del parásito. Un gran número de estudios se han focalizado en la identificación de mecanismos moleculares responsables del fenómeno de inmunosupresión, entre los mecanismos citados se ha demostrado presencia de células supresoras [5-9], factores inmunosupresores presentes en el parásito [2, 3, 10-13], producción excesiva de óxido nítrico [14], disminuida producción de IL-2 y reducida expresión del receptor de IL2 en células de bazo de animales infectados [9, 15-17]. Muchos de estos mecanismos han sido exhaustivamente investigados, sin embargo no está del todo claro si existen mecanismos adicionales involucrados en la inmunosupresión de la célula T. Adicionalmente, en los últimos años nuevas moléculas que median la regulación negativa de la célula T, entre las cuales están PD-1/PD1-L [18], arginasa [19] y E3 ubiquitina ligasas [20-22], han sido reportadas durante inmunosupresión en diversas infecciones. Trypanosoma cruzi, the etiological agent of Chagas’ disease, is parasite causing chronic infections in human and other mammalian species. There is an important immunosupresion during the acute phase of the infection that contribute to the dissemination and installation of the parasite. Several studies have been focused on identifying the mechanisms involved in the immunosupresion; however it is not clear if there are additional mechanisms implicated. In addition, during the last years new molecules involved in the negative T cell regulation such as PD-1/PD1-L pathway and E3 ubiquitin ligases (E3-Ub-Lig) have been reported. It has been demonstrated, that E3-Ub-Lig control the amount and localization of intracellular signal mediators, limiting T cell activation. Moreover, these mechanisms mediate the immunosupresion observed during several infections leading to the persistence of the pathogen in the host. In this project the role of E3-Ub-Lig on the T cell immunosupresion and hipo-response mechanisms observed during T. cruzi infection will be studied. On the other hand, it has been reported that some pathogens release proteins with E3-Ub-Lig activity modifying the ubiquitination process to promote their survival and replication in the host. Recently, a protein with E3-Ub-Lig activity was identified in T. cruzi, however its target molecule has not been discovered yet. Therefore, one of the aims of this project consists on studying different potential target molecules for this novel E3-Ub-Lig. In addition, during the last years, important progress has been done about the biological rol of PD-1/PD1-L pathway on the regulation of the immune response in several infections. However, it is not well known how PD-1/PD1-L pathway transduces signals at intracelular level to block T cell response. Because of this, it is interesting to study if there is any relation between the PD-1/PD1-L pathway and E3-Ub-Lig on the mechanism of T cell immunosupression during T. cruzi infection.

Untersuchungen zur Quartärstruktur neuronaler nikotinischer Acetylcholinrezeptoren von Drosophila melanogaster

Fruitfly, Drosophila melanogaster, neuronal nicotinic acetylcholine receptor, receptor subunit, quarternary structure

Strukturbasierte Analyse calciumcoordinierender Proteine an der Synapse

Magdeburg, Univ., Fak. für Naturwiss., Diss., 2009

Assessing the role of Piccolo and Bassoon zinc finger domains on synapse vesicle recycling and maintenance

Magdeburg, Univ., Fak. für Naturwiss., Diss., 2013

E3 ubiquitin ligase Praja1 inhibits the development of a neuronal phenotype in PC12 cells

Magdeburg, Univ., Med. Fak., Diss., 2015

Two new species of the Drosophila serido sibling set (Diptera, Drosophilidae)

Drosophila antonietae sp. nov. and D. gouveai sp. nov. are members of the D. buzzatii cluster of the D. repleta species group of the genus Drosophila. They can be distinguished from their cryptic species, D. borborema Vilela & Sene, 1977, D. koepferae Fontdevila & Wasserman, 1988, D. serido Vilela & Sene, 1977, and D. seriema Tidon-Sklorz & Sene, 1995 by morphological, genetic and ecological criteria.

Gonadal hybrid dysgenesis in Drosophila sturtevanti (Diptera, Drosophilidae)

The occurrence of hybrid dysgenesis was investigated in Drosophila sturtevanti Duda, 1927 using diagnostic crosses similar to those used for induction of dysgenics traits in D. melanogaster. Reciprocal test crosses were made, at 27° C, between an old laboratory strain of D. sturtevanti (COL, from Colombia), assumed to be an M'-like strain, and eight freshly collected strains from several natural populations. The gonadal dysgenesis indices were under 10% in most of crosses, except in hybrids of COL with I27, a strain from Minas Gerais (Brazil), in which the index values were moderate in both directions of crosses (25.71 and 12.87). The smallest productivity was also observed in hybrids of females COL mated to I27 males. No causal relationship between the observed gonadal dysgenesis and mobilization of P element or another transposable element could be effectively established.

Temperature, urbanization and body color polymorphism in South Brazilian populations of Drosophila kikkawai (Diptera, Drosophilidae)

Body color polymorphism of urban populations of cosmopolite fly Drosophila kikkawai Burla, 1954 was investigated in relation to its possible association with environmental temperature. Samples of D. kikkawai were collected in spring, summer, autumn and winter between 1987 to 1988, in zones with different levels of urbanization in the southern Brazilian city of Porto Alegre, Rio Grande do Sul. A clear association was observed between darker flies and both seasons with low temperatures and areas of low urbanization (where temperature is generally lower than in urbanized areas). Results of preliminary laboratory experiments involving six generations of flies grown in chambers at temperatures of 17º and 25ºC confirmed this tendency to a relationship between body color and temperature, with allele frequency of the main gene involved in body pigmentation changing over time.

Three new andean species of Drosophila (Diptera, Drosophilidae) of the mesophragmatica group

Three new species of mesophragmatica group, Drosophila amaguana, Drosophila shyri and Drosophila ruminahuii from Pasochoa Forest Reserve, northern Ecuadorian Andes, are described. The two subgroups currently composing the mesophragmatica group are renamed as the mesophragmatica subgroup to which the first two species have been added, and the viracochi subgroup to which the latter species has been added. These subgroups are defined based on the direction of the basal scutellar setae, which are divergent in the species of the former subgroup and convergent in the latter.

Ciclos de vida y componentes de la aptitud de Drosophila inca y D. yangana (Diptera, Drosophilidae)

Se describen los ciclos de vida de Drosophila inca Dobzhansky & Pavan, 1943 y D. yangana Rafael & Vela, 2003 los cuales son muy similares; la viabilidad observada es diferente ya que la mortalidad en estagios larvarios y de pupación de D. yangana es superior debido a la alimentación inadecuada. La duración promedia desde huevo hasta adulto es 22 días a 21 - 23°C para ambas especies.

Seasonal variation in natural populations of Drosophila spp. (Diptera) in two woodlands in the State of São Paulo, Brazil

The composition and the seasonality of the natural populations of Drosophila species in relation to the climatic variables temperature and rainfall were analyzed from September 1998 through October 1999 by monthly collections, in two woodlands in the Northwest of the State of São Paulo, Brazil. The diversity dominance component curves were inclined, reflecting low diversity and high dominance of few species. Among the 25 species recorded, Drosophila sturtevanti Duda, 1927 was the most frequent and abundant. On the opposite to data in literature, D. paranaensis Barros, 1950 abundance and frequency were greater than those from D. mercatorum Patterson & Wheeler, 1942. A positive correlation between abundance and rainfall was observed for D. nebulosa Sturtevant, 1916. These data are indicative of changes in the populations structure due to new adaptive strategies arised in response to environmental modifications.