Photoreceptor-specific efficiencies of β-carotene,zeaxanthin and lutein for photopigment formation deduced from receptor mutant Drosophila melanogaster

Summary Drosophila rearing media had only -carotene, zeaxanthin or lutein as precursors for photopigment chromophores. Zeaxanthin and lutein are potentially optimum sources of the 3-hydroxylated retinoids of visual and accessory photopigments. Mutants made the electroretinogram in white (w) eyes selective for compound eye photoreceptors R1–6, R7 and R8: R1–6 domiantes w's electroretinogram; R7/8 generates w;ora's (ora = outer rhabdomeres absent); R8 generates w sev;- ora's (sev = sevenless). Microspectrophotometry revealed R1-6's visual pigment. In w, all 3 carotenoids yielded monotonic dose-responses for sensitivity (Fig. 4) or visual pigment (Fig. 7). An ultraviolet sensitivity peak from R1-6's sensitizing pigment was present at high but not low doses (Fig. 1). In w;ora, all 3 carotenoids gave similar spectra dominated by R7's high ultraviolet sensitivity (Fig. 2). For w sev;ora, all spectra were the shape expected for R8, peaking around 510 nm (Fig. 3). The sensitivity dose-response was at its ceiling except for low doses in w;ora (Fig. 5) and zero supplementation in w sev;ora (Fig. 6). Hence, without R1-6, most of our dose range mediated maximal visual pigment formation. In Drosophila, -carotene, zeaxanthin and lutein mediate the formation of all major photopigments in R1-6, R7 and R8.Abbreviations ERG electroretinogram - MSP microspectrophotometry - HPLC high pressure liquid chromatography - n.a. numerical aperture - w, sev, ora Drosophila mutants - y, p, r marg types of R7 and R8     

Stereochemical course of the hydroboration of highly hindered steroidal olefins. A ready synthesis of 14 beta- and 8 alpha,14 beta-steroids

Hydroboration of 5 alpha-cholest-8-ene, 5 alpha,14 beta-cholest-8-ene and 5 alpha,14 beta-cholest-7-ene provides a simple route to oxygenated steroids with 14 beta- and 8 alpha,14 beta- unnatural stereochemistry.     

Synthesis of 7 alpha,12 alpha-dihydroxy-3 alpha- [2-(beta-D-glucopyranosyl)acetyl]-5 beta-cholan-24-oic acid

A C-glucoside of cholic acid was synthesized by the introduction of an acetyl group at position 3 alpha and direct one-pot C-glucosidation using 2,3,4,6-tetra-O-benzyl-alpha-D-glucopyranosyl chloride.     

Ultrasonic characteristics of frozen liver

The recent development of new ultrasound probes has made real-time intraoperative monitoring of cryosurgery, and thermocouple placement a possibility. It is shown that frozen tissue and thermocouple needles have acoustic characteristics that enable them to be easily visualized by ultrasound examination. Further in vivo animal studies are needed to examine temperature characteristics of visualized cryolesions, to develop scanning techniques, and to correlate ultrasonic findings with histologic changes in tissue.     

Thyroid antibodies as a risk factor for Down syndrome and other trisomies.

To test whether the presence of thyroid antibodies in a parent is a risk factor for meiotic nondisjunction, we measured the levels of thyroid antibodies in serum samples drawn during early pregnancy from 101 gravidas who delivered a child with a trisomy, from 11 gravidas who had had a trisomic child in a previous pregnancy, and from 44 of their husbands. For each case mother, three controls were randomly selected from the same population and matched for age, race, sex of the child, and hospital of birth. Cases and controls came from two longitudinal populations, the Child Health and Development Studies (CHDS) and the national Collaborative Perinatal Project (CPP), together comprising more than 70,000 live births. All cases with both a definite diagnosis of trisomy-Down syndrome (DS) or other-and available serum were included. Overall, there was no association between the presence of thyroid antibodies in a mother and a trisomy in her offspring (odds ratio [OR] = .98, confidence interval [CI] = .54-1.85). The lack of association was seen in all three subgroups (DS only, other trisomies, and DS in a previous pregnancy), in all ethnic groups, and in the age groups of white mothers either less than 30 years of age (OR = .80, CI = .40-1.6) or greater than or equal to 30 years of age (OR = 1.26, CI = .82-1.9). In the CHDS population, case fathers, as compared with control fathers, did not have a higher prevalence of thyroid antibodies.(ABSTRACT TRUNCATED AT 250 WORDS)     

Insecticide resistance in Bemisia tabaci from Cyprus

Abstract A comprehensive study on the Bemisia tabaci (biotype B) resistance to neonicotinoid insecticides imidacloprid, acetamiprid and thiamethoxam, and pyrethroid bifenthrin was conducted in Cyprus. The resistance level to eight field‐collected B. tabaci populations was investigated. The activities of enzymes involved in metabolic detoxification and the frequencies of pyrethroid and organophosphates target site resistance mutations were determined. Moderate to high levels of resistance were detected for imidacloprid (resistance factor [RF] 77–392) and thiamethoxam (RF 50–164) while low resistance levels were observed for acetamiprid (RF 7–12). Uniform responses by the Cypriot whiteflies could be observed against all neonicotinoid insecticides. No cross‐resistance between the neonicotinoids was detected as well as no association with the activity of the P450 microsomal oxidases. Only imidacloprid resistance correlated with carboxylesterase activity. Low to extremely high resistance was observed for insecticide bifenthrin (RF 49–1 243) which was associated with the frequency of the resistant allele in the sodium channel gene but not with the activity of the detoxification enzymes. Finally, the F331W mutation in the acetylcholinesterase enzyme ace1 gene was fixed in all B. tabaci populations from Cyprus.