De novo biosynthesis of simple aromatic compounds by an arthropod (Archegozetes longisetosus)

The ability to synthesize simple aromatic compounds is well known from bacteria, fungi and plants, which all share an exclusive biosynthetic route—the shikimic acid pathway. Some of these organisms further evolved the polyketide pathway to form core benzenoids via a head-to-tail condensation of polyketide precursors. Arthropods supposedly lack the ability to synthesize aromatics and instead rely on aromatic amino acids acquired from food, or from symbiotic microorganisms. The few studies purportedly showing de novo biosynthesis via the polyketide synthase (PKS) pathway failed to exclude endosymbiotic bacteria, so their results are inconclusive. We investigated the biosynthesis of aromatic compounds in defence secretions of the oribatid mite Archegozetes longisetosus. Exposing the mites to a diet containing high concentrations of antibiotics removed potential microbial partners but did not affect the production of defensive benzenoids. To gain insights into benzenoid biosynthesis, we fed mites with stable-isotope labelled precursors and monitored incorporation with mass spectrometry. Glucose, malonic acid and acetate, but not phenylalanine, were incorporated into the benzenoids, further evidencing autogenous biosynthesis. Whole-transcriptome sequencing with hidden Markov model profile search of protein domain families and subsequent phylogenetic analysis revealed a putative PKS domain similar to an actinobacterial PKS, possibly indicating a horizontal gene transfer

Ambivalence and Pregnancy: The Effect of Adolescents' Attitudes on Contraception and Pregnancy

It has been argued that adolescents who get pregnant often do not sufficiently appreciate its unfavorable consequences, and that prevention programs should target participants' attitudes towards pregnancy. This study tests whether the nature and certainty of sexually active adolescent girls' attitudes towards pregnancy influence their contraceptive consistency and risk of pregnancy. It also tests whether attitudes towards contraception influence contraceptive consistency. Data are drawn from the National Longitudinal Study of Adolescent Health, a nationwide prospective study of adolescents in grades 7-12. Attitudes towards pregnancy, attitudes towards contraception, knowledge about fertility and other individual characteristics are included in a multivariate model of contraceptive consistency. Those variables, as well as contraceptive consistency itself, are then included in a multivariate model of pregnancy. Net of other factors, girls' attitudes towards getting pregnant did not affect whether they actually became pregnant. However, ambivalence about pregnancy made girls less likely to use contraception. Girls who were most opposed to pregnancy did not differ in contraceptive consistency from those least opposed. Implications for pregnancy prevention efforts are discussed

Ambivalence and Pregnancy: The Effect of Adolescents' Attitudes on Contraception and Pregnancy

It has been argued that adolescents who get pregnant often do not sufficiently appreciate its unfavorable consequences, and that prevention programs should target participants' attitudes towards pregnancy. This study tests whether the nature and certainty of sexually active adolescent girls' attitudes towards pregnancy influence their contraceptive consistency and risk of pregnancy. It also tests whether attitudes towards contraception influence contraceptive consistency. Data are drawn from the National Longitudinal Study of Adolescent Health, a nationwide prospective study of adolescents in grades 7-12. Attitudes towards pregnancy, attitudes towards contraception, knowledge about fertility and other individual characteristics are included in a multivariate model of contraceptive consistency. Those variables, as well as contraceptive consistency itself, are then included in a multivariate model of pregnancy. Net of other factors, girls' attitudes towards getting pregnant did not affect whether they actually became pregnant. However, ambivalence about pregnancy made girls less likely to use contraception. Girls who were most opposed to pregnancy did not differ in contraceptive consistency from those least opposed. Implications for pregnancy prevention efforts are discussed

Measurement of the Omega_c Lifetime

We present the measurement of the lifetime of the Omega_c we have performed using three independent data samples from two different decay modes. Using a Sigma- beam of 340 GeV/c we have obtained clean signals for the Omega_c decaying into Xi- K- pi+ pi+ and Omega- pi+ pi- pi+, avoiding topological cuts normally used in charm analysis. The short but measurable lifetime of the Omega_c is demonstrated by a clear enhancement of the signals at short but finite decay lengths. Using a continuous maximum likelihood method we determined the lifetime to be tau(Omega_c) = 55 +13-11(stat) +18-23(syst) fs. This makes the Omega_c the shortest living weakly decaying particle observed so far. The short value of the lifetime confirms the predicted pattern of the charmed baryon lifetimes and demonstrates that the strong interaction plays a vital role in the lifetimes of charmed hadrons.Comment: 15 pages, including 7 figures; gzipped, uuencoded postscrip

The ancient harbour city of Ainos and its environs – Palaeoenvironmental reconstructions based on sedimentological and microfaunal evidence

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