Analysis of molecular markers for metamorphic competency and their response to starvation or feeding in the mosquito, Aedes aegypti (Diptera: Culicidae)

The nutritional condition of fourth instar larvae of the yellow fever mosquito, Aedes aegypti, governs female longevity and egg production, both are key determinants of pathogen transmission. As well, nutrition provisions larval growth and development and attains its greatest pace in the last larval instar in preparation for metamorphosis to an adult. These developmental processes are regulated by a complex endocrine interplay of juvenile hormone, neuropeptides, and ecdysteroids that is nutrition sensitive. We previously determined that feeding for only 24h post-ecdysis was sufficient for fourth instar Ae. aegypti larvae to reach critical weight and accumulate sufficient nutritional stores to commit to metamorphosis. To understand the genetic basis of metamorphic commitment in Ae. aegypti, we profiled the expression of 16 genes known to be involved in the endocrine and nutritional regulation of insect metamorphosis in two ways. The first set is a developmental profile from the beginning of the fourth instar to early pupae, and the second set is for fourth instars starved or fed for up to 36 h. By comparing the two sets, we found that seven of the genes (AaegCYP302, AaegJHE43357, AaegBrCZ4, AaegCPF1-2, AaegCPR-7, AaegPpl, and AaegSlif) were expressed during metamorphic commitment in fourth instars and in fed but not starved larvae. Based on these results, the seven genes alone or in combination may serve as molecular indicators of nutritional and metamorphic status of fourth instar Ae. aegypti larvae and possibly other mosquito species in field and laboratory studies to gauge sub-lethal effects of novel and traditional cultural or chemical controls.

Understanding reentry to out-of-home care for reunified infants

Although many children placed in out-of-home care are reunified with their families of origin, a significant portion reenter care, reflecting continued family problems and weaknesses within the child welfare system. For infants, the stability of reunification is particularly crucial, given their developmental stage. This study reviewed the case records of 88 randomly selected infants who had been reunified with their families. Thirty-two percent of those infants reentered care within four to six years of their reunification. The identification of factors predictive of reentry into care has both policy and practice implications.

Variability of human hepatic UDP-glucuronosyltransferase activity

The availability of a unique series of liver samples from human subjects, both control patients (9) and those with liver disease (6; biliary atresia (2), retransplant, chronic tyrosinemia type I, tyrosinemia, Wilson's disease) allowed us to characterize human hepatic UDP-glucuronosyltransferases using photoaffinity labeling, immunoblotting and enzymatic assays. There was wide inter-individual variation in photoincorporation of the photoaffinity analogs, [32P]5-azido-UDP-glucuronic acid and [32P]5-azido-UDP-glucose and enzymatic glucuronidation of substrates specific to the two subfamilies of UDP-glucuronosyltransferases. However, the largest differences were between subjects with liver disease. Glucuronidation activities toward one substrate from each of the UDP-glucuronosyltransferases subfamilies, 1A and 2B, for control and liver disease, respectively, were 1.7-4.5 vs 0.4-4.7 nmol/mg x min for hyodeoxycholic acid (2B substrate) and 9.2-27.9 vs 8.1-75 nmol/mg x min for pchloro-m-xylenol (1A substrate). Microsomes from a patient with chronic tyrosinemia (HL32) photoincorporated [32P]5-azido-UDP-glucuronic acid at a level 1.5 times higher than the other samples, was intensely photolabeled by [32P]5-azido-UDP-glucose and had significantly higher enzymatic activity toward p-chloro-m-xylenol. Immunoblot analysis using anti-UDP-glucuronosyltransferase antibodies demonstrated wide inter-individual variations in UDP-glucuronosyltransferase protein with increased UDP-glucuronosyltransferase protein in HL32 microsomes, corresponding to one of the bands photolabeled by both probes. Detailed investigation of substrate specificity, using substrates representative of both the 1A (bilirubin, 4-nitrophenol) and 2B (androsterone, testosterone) families was carried out with HL32, HL38 (age and sex matched control) and HL18 (older control). Strikingly increased (5-8-fold) glucuronidation activity was seen in comparison to HL18 only with the phenolic substrates. The results indicate that one or more phenol-specific UDP-glucuronosyltransferase 1A isoforms are expressed at above normal levels in this tyrosinemic subject.

Variability of human hepatic UDP-glucuronosyltransferase activity

The availability of a unique series of liver samples from human subjects, both control patients (9) and those with liver disease (6; biliary atresia (2), retransplant, chronic tyrosinemia type I, tyrosinemia, Wilson's disease) allowed us to characterize human hepatic UDP-glucuronosyltransferases using photoaffinity labeling, immunoblotting and enzymatic assays. There was wide inter-individual variation in photoincorporation of the photoaffinity analogs, [32P]5-azido-UDP-glucuronic acid and [32P]5-azido-UDP-glucose and enzymatic glucuronidation of substrates specific to the two subfamilies of UDP-glucuronosyltransferases. However, the largest differences were between subjects with liver disease. Glucuronidation activities toward one substrate from each of the UDP-glucuronosyltransferases subfamilies, 1A and 2B, for control and liver disease, respectively, were 1.7-4.5 vs 0.4-4.7 nmol/mg x min for hyodeoxycholic acid (2B substrate) and 9.2-27.9 vs 8.1-75 nmol/mg x min for pchloro-m-xylenol (1A substrate). Microsomes from a patient with chronic tyrosinemia (HL32) photoincorporated [32P]5-azido-UDP-glucuronic acid at a level 1.5 times higher than the other samples, was intensely photolabeled by [32P]5-azido-UDP-glucose and had significantly higher enzymatic activity toward p-chloro-m-xylenol. Immunoblot analysis using anti-UDP-glucuronosyltransferase antibodies demonstrated wide inter-individual variations in UDP-glucuronosyltransferase protein with increased UDP-glucuronosyltransferase protein in HL32 microsomes, corresponding to one of the bands photolabeled by both probes. Detailed investigation of substrate specificity, using substrates representative of both the 1A (bilirubin, 4-nitrophenol) and 2B (androsterone, testosterone) families was carried out with HL32, HL38 (age and sex matched control) and HL18 (older control). Strikingly increased (5-8-fold) glucuronidation activity was seen in comparison to HL18 only with the phenolic substrates. The results indicate that one or more phenol-specific UDP-glucuronosyltransferase 1A isoforms are expressed at above normal levels in this tyrosinemic subject.

c-src gene product in developing rat brain is enriched in nerve growth cone membranes

Differentiating rat neurons express high levels of the protooncogene product pp60c-src, a 60-kDa tyrosine kinase of unknown function encoded by c-src. pp60c-src was found to be concentrated at least 9-fold in membranes from a subcellular fraction of nerve growth cones, the motile tips of outgrowing neuronal processes. Indirect immunofluorescence staining of cultured chick retinal explants showed pp60c-src in neuronal growth cones and processes, with the antigen particularly concentrated in growth cones of long neurites. pp60c-src in growth cone membranes was an active tyrosine-specific protein kinase with elevated tyrosine-specific protein kinase activity and reduced electrophoretic mobility characteristic of the form of pp60c-src in central nervous system neurons. pp60c-src was present at lower levels in subcellular fractions from mature rat brain but synaptosomal membranes were not enriched. Preferential localization of an active form of pp60c-src in nerve growth cone membranes and persistence of pp60c-src in mature neurons suggest that this tyrosine kinase is important in growth cone-mediated neurite extension and synaptic plasticity.