Reduced juvenile hormone synthesis in mosquitoes with low teneral reserves reduces ovarian previtellogenic development in Aedes aegypti.

We investigated the relationship among nutritional reserves, previtellogenic ovary development and juvenile hormone (JH) synthesis in Aedes aegypti female mosquitoes. By raising larvae under different nutritional regimes, two adult phenotypes (large and small females) were generated, which differed significantly in size at eclosion (measured by wing length). We measured the total amount of protein, lipids and glycogen in newly emerged (teneral) large and small females. Teneral reserves were significantly lower in small females. Maximum previtellogenic ovary development occurred only if enough teneral nutrients were present. Maximum previtellogenic ovary development was stimulated in small females with low teneral nutrients by topically applying a JH analog. The biosynthetic activity of Ae. aegypti corpora allata (CA) was studied in vitro using a radiochemical method. JH synthesis was significantly reduced in females emerged with low teneral reserves and stimulated by sugar feeding. These results establish that the CA synthesizes enough JH to activate ovary maturation only in the presence of large nutrient reserves.

Free amino acids are important for the retention of protein and non-protein meals by the midgut of Aedes aegypti females.

There is a relationship between the normal progress of digestion and the retention or elimination of the proteins ingested with the meal by Aedes aegyti females. The addition of soybean trypsin inhibitor (STI) to a protein meal prevented digestion and resulted in a rapid elimination of the undigested proteins. The addition of a mix of free amino acids to a protein meal together with STI resulted in a significant increase in the retention of the undigested proteins during the first 10-15 hrs after feeding. The effect of the free amino acids on the retention of the proteins was concentration-dependent between 250 microg/ml and 5 mg/ml. Free amino acids were also important for the retention of non-protein meals. When females were fed a meal containing FITC-dextran (20 kD), most of this compound was eliminated into the feces by 10 hrs; the addition of free amino acid resulted in a significant increase in the retention of the FITC-dextran by the midgut during the first 15 hrs after feeding. The presence of free amino acids in the midgut lumen seems to be an important signal used by the mosquito to regulate the retention of the meal.

Wilm's Tumour in a horseshoe kidney

Wilms'tumor (nephroblastoma) is a common childhood tumour, with a reported annual incidence in the United States of 7.8 cases per million of population aged one to 14 years. Horseshoe-shaped kidney is a congenital malformation with a recognized risk of complications, yet an associated nephroblastic is exceeding rare. A case of this simultaneous but unsuspected occurrence of a Wilms' tumour co-existing within a horseshoe kidney, and diagnostic dilemma encountered is presented. (Au)