Biosynthesis and distribution of ecdysone and 20-OH-ecdysone in Aedes aegypti

The distribution and biosynthesis of ecdysone and 20-hydroxyecdysone (20-OH-ecdysone) was followed in sugar- and blood-fed female Aedes aegypti. In both sugar- and early blood-fed animals most of the ecdysteroid determined by radioimmunoassay was found outside the ovary. Twenty-four to 40 h after blood feeding, however, ecdysteroid was distributed between ovary and carcass in the ratio of 1:1.5. Ecdysteroid titer reached a plateau between 18 to 40 h after the blood meal and decreased thereafter. Analysis of the ecdysteroid titer using thin layer chromatography (TLC) and high performance liquid chromatography (HPLC) revealed that both 20-OH-ecdysone and ecdysone were synthesized after the blood meal. The ratio of 20-OH-ecdysone to ecdysone remained essentially constant and fluctuated in parallel throughout egg development. Chromatography of the early ecdysteroid peak (8 h after feeding) using TLC and HPLC indicated that although it cross-reacted with ecdysteroid antibodies, it did not have the same elution times as ecdysone and 20-OH-ecdysone and is, therefore, probably a precursor of these ecdysteroids. Injections of egg development neurosecretory hormone (EDNH) preparation purified to near homogeneity, into ligated abdomens, induced ecdysteroid synthesis only if the abdomens were first treated with methoprene (12.5 pg). Methoprene at this concentration did not stimulate ecdysteroid synthesis in these abdomens. When blood-fed females were treated with [4-¹⁴C] cholesterol and analyzed using TLC and HPLC procedures, both [¹⁴C]labeled ecdysone and [¹⁴C]labeled 20-OH-ecdysone were synthesized in the ratio of 1:1.5. This report is the first to show that both ecdysone and 20-OH-ecdysone are synthesized in vivo in female A. aegypti.     

Heterozygous expression of insulin-dependent diabetes mellitus (IDDM) determinants in the HLA system.

HLA phenotypes of cases with insulin-dependent diabetes mellitus (IDDM) and identity by descent of HLA haplotypes in affected sib-pairs support an intermediate model in which morbid risk is increased by one HLA-linked IDDM determinant, and greatly increased by two determinants, which may be qualitatively different in DR3 and DR4 haplotypes. Linkage analysis allowing for gametic disequilibrium reveals no recombination in pedigrees with a DR3/DR4 propositus, but spurious recombination in the remaining pedigrees. This evidence favors interaction of unlinked IDDM determinants to produce affection in a small proportion of heterozygotes for an HLA-linked determinant. Partition of data by HLA type of the propositus (ideally by DR and the complement types jointly) is a powerful method to resolve etiological heterogeneity for HLA-associated diseases.     

Association of genetic polymorphisms with embryonic mortality in the chicken

Summary Association of the egg-white genotypes of dams with the mortality of their embryos was studied in 1966 in the pure and crossbred embryos of dams of two relatively noninbred Light Sussex substrains, 6D and 6F. These had been derived two generations earlier, in 1964, by equal division of strain 6, which we previously studied in 1962; while the sires of the crosses came from two Rhode Island Red/New Hampshire substrains, 5D and 5F, similarly derived. The effects were estimated parametrically for the three loci Tf, II and III singly and in two- and three-way interaction.In the first week of incubation, Tf had an additive effect in all matings, while II (and perhaps III) had a near-additive effect in the pure matings only. There was an additive X additive interaction effect of II X III in the last six days of incubation, which was consistent over all matings except 5F X 6F. The only effect to influence the total mortality over the whole of incubation was the three-way additive X additive X additive interaction, and there was substantial agreement in this over the matings. Some triple homozygotes were superior and others inferior to the genotypes with one or more loci heterozygous.This evidence of multiple interaction between loci affecting fitness is discussed in relation to hypotheses for the maintenance of genetic variability in populations.     

Microsomal-catalyzed hydroperoxide-dependent C-oxidation of amines

Organic hydroperoxides are capable of supporting the C-oxidation of several different amines in the presence of hepatic microsomes. Evidence is presented that indicates that microsomal cytochrome P-450 acts as the catalyst. Removal of the NADPH-cytochrome $\text{c}$ oxidoreductase or essential phospholipid from microsomes does not significantly affect the peroxidase activity. Of the amine substrates C-oxidized by organic hydroperoxides in the presence of microsomes, only aminopyrine and dimethylaniline are rapidly oxidized by hydroperoxides in the presence of catalase. The catalase-mediated reaction can also be distinguished from the microsomal-catalyzed reaction by the use of differential inhibitors.     

Effects of freezing and hardening on the sulfhydryl groups of protein fractions from cabbage leaves

Disc electrophoresis was used to separate water soluble proteins from hardy, non-hardy, and frost killed cabbage (Brassica oleracea var. capitata) leaves. Amidoschwarz staining failed to reveal any new bands as a result of hardening although the relative amounts of proteins in individual bands changed. Sulfhydryl groups in the protein bands were stained with 2,2-dihydroxy-6,6-dinaphthyl disulfide and labeled with ¹⁴C p-chloromercuribenzoate. Significant decreases in the sulfhydryl content of the total water soluble protein were found during hardening and as a result of frost death. The decrease during hardening was paralleled by a significant increase in the water soluble protein. There was a significant increase in the sulfhydryl content per unit high molecular weight protein but a decrease in the sulfhydryl content per total protein as a result of frost death. This was interpreted as evidence for intermolecular disulfide bond formation during freezing.