Diverse functions of the ecdysone receptor (EcR) in the panoistic ovary of the German cockroach.

Ecdysone regulates essential processes in insect life. Perhaps the most well-known of these are related to metamorphosis. However, ecdysone is also required to regulate the proliferation and differentiation of germ cells in the ovary. The role of ecdysone in insect oogenesis has been studied in depth in holometabolan species with meroistic ovaries, such as Drosophila melanogaster, while in hemimetabolan species with panoistic ovaries their functions are still poorly understood. In the present work, we studied the role of ecdysone in the ovary of the last nymphal instar of the cockroach Blattella germanica by using RNA interference to reduce the levels of the ecdysone receptor (EcR), and thereby deplete the expression of ecdysteroidogenic genes in the prothoracic gland. However, the expression of ecdysteroidogenic genes was upregulated in the ovary, resulting in cell overproliferation in the germarium, which appeared swollen. By analysing the expression of genes that respond to ecdysone, we found that when the source of 20E is the nymphal ovary, EcR appears to repress 20E-associated genes bypassing early genes signalling.

Eyes absent in the cockroach panoistic ovaries regulates proliferation and differentiation through ecdysone signalling.

Eyes absent (Eya), is a protein structurally conserved from hydrozoans to humans, for which two basic roles have been reported: it can act as a transcription cofactor and as a protein tyrosine phosphatase. Eya was discovered in the fly Drosophila melanogaster in relation to its function in eye development, and the same function was later reported in other insects. Eya is also involved in insect oogenesis, although studies in this sense are limited to D. melanogaster, which has meroistic ovaries, and where eya mutations abolish gonad formation. In the present work we studied the function of eya in the panoistic ovary of the cockroach Blattella germanica. We show that eya is essential for correct development of panoistic ovaries. In B. germanica, eya acts at different level and in a distinct way in the germarium and the vitellarium. In the germarium, eya contributes to maintain the correct number of somatic and germinal cells by regulating the expression of steroidogenic genes in the ovary. In the vitellarium, eya facilitates follicle cells proliferation and contributes to regulate the cell program, in the context of basal ovarian follicle maturation. Thus, eya-depleted females of B. germanica arrest the growth and maturation of basal ovarian follicles and become sterile.

Efficacy of the rhesus rotavirus-based quadrivalent vaccine in infants and young children in Venezuela.

BACKGROUND: Rotaviruses are the principal known etiologic agents of severe diarrhea among infants and young children worldwide. Although a rhesus rotavirus-based quadrivalent vaccine is highly effective in preventing severe diarrhea in developed countries, in developing countries its efficacy has been less impressive. We thus conducted a catchment study in Venezuela to assess the efficacy of the vaccine against dehydrating diarrhea. METHODS: In this randomized, double-blind, placebo-controlled trial, 2207 infants received three oral doses of the quadrivalent rotavirus vaccine (4x10(5) plaque-forming units per dose) or placebo at about two, three, and four months of age. During approximately 19 to 20 months of passive surveillance, episodes of gastroenteritis were evaluated at the hospital. RESULTS: The vaccine was safe, although 15 percent of the vaccinated infants had febrile episodes (rectal temperature, > or =38.1 degrees C) during the six days after the first dose, as compared with 7 percent of the controls (P<0.001). However, the vaccine gave 88 percent protection against severe diarrhea caused by rotavirus and 75 percent protection against dehydration, and produced a 70 percent reduction in hospital admissions. Overall, the efficacy of the vaccine against a first episode of rotavirus diarrhea was 48 percent. Horizontal transmission of vaccine virus was demonstrated in 15 percent of the vaccine recipients and 13 percent of the placebo recipients with rotavirus-positive diarrhea. CONCLUSIONS: In this study in a developing country, the quadrivalent rhesus rotavirus-based vaccine induced a high level of protection against severe diarrheal illness caused by rotavirus.