Evidence for an ancient whole genome duplication in the cycad lineage

Contrary to the many whole genome duplication events recorded for angiosperms (flowering plants), whole genome duplications in gymnosperms (non-flowering seed plants) seem to be much rarer. Although ancient whole genome duplications have been reported for most gymnosperm lineages as well, some are still contested and need to be confirmed. For instance, data for ginkgo, but particularly cycads have remained inconclusive so far, likely due to the quality of the data available and flaws in the analysis. We extracted and sequenced RNA from both the cycad Encephalartos natalensis and Ginkgo biloba. This was followed by transcriptome assembly, after which these data were used to build paralog age distributions. Based on these distributions, we identified remnants of an ancient whole genome duplication in both cycads and ginkgo. The most parsimonious explanation would be that this whole genome duplication event was shared between both species and had occurred prior to their divergence, about 300 million years ago

Factors associated with contraceptive use in a rural area in Western Cape Province

Background. Safe and effective contraceptive use can substantially improve women’s reproductive health. Although the contraceptive prevalence rate (CPR) in South Africa is comparable to rates globally, inequalities in CPR affect poor and rural women. This study aimed to determine the CPR and factors associated with contraceptive use in a rural district of Western Cape Province. Method. Cross-sectional survey data based on 412 face-to-face interviews with female participants between 18 and 44 years of age were collected in 2006 for a primary fetal alcohol syndrome prevention study in a rural district in Western Cape Province. The study used effective contraception (ECC) as the outcome variable. ECC included use of oral contraceptives, condoms, injectables or sterilisation. Independent variables included socio-demographic factors, substance use, psychosocial factors, community factors, childbearing characteristics and partner characteristics. Results. Women were more likely to use ECC if they reported high self-esteem (compared with low or moderate self-esteem (prevalence risk ratio (PRR)=1.23; 95% confidence interval (CI) 0.99 - 1.53); if they strongly or moderately agreed that their culture entitled men to make decisions regarding child-bearing compared with those who disagreed (PRR=1.28; 95% CI 0.96 - 1.71); and if they had one child or more compared with no children (PRR=1.62; 95% CI 1.24 - 2.11). Conclusion. The CPR for sexually active women in this study was low at 39.3%. To promote contraceptive use in similar rural populations, family planning programmes should focus on increasing men’s approval of contraception, improving partner communication around family planning and bolstering women’s confidence in their reproductive decision-making, and particularly their self-esteem. There should be greater focus on nulliparous women

Factors associated with contraceptive use in a rural area in Western Cape Province

BACKGROUND: Safe and effective contraceptive use can substantially improve women's reproductive health. Although the contraceptive prevalence rate (CPR) in South Africa is comparable to rates globally, inequalities in CPR affect poor and rural women. This study aimed to determine the CPR and factors associated with contraceptive use in a rural district of Western Cape Province. METHOD: Cross-sectional survey data based on 412 face-to-face interviews with female participants between 18 and 44 years of age were collected in 2006 for a primary fetal alcohol syndrome prevention study in a rural district in Western Cape Province. The study used effective contraception (ECC) as the outcome variable. ECC included use of oral contraceptives, condoms, injectables or sterilisation. Independent variables included socio-demographic factors, substance use, psychosocial factors, community factors, childbearing characteristics and partner characteristics. RESULTS: Women were more likely to use ECC if they reported high self-esteem (compared with low or moderate self-esteem (prevalence risk ratio (PRR)=1.23; 95% confidence interval (CI) 0.99 - 1.53); if they strongly or moderately agreed that their culture entitled men to make decisions regarding child-bearing compared with those who disagreed (PRR=1.28; 95% CI 0.96 - 1.71); and if they had one child or more compared with no children (PRR=1.62; 95% CI 1.24 - 2.11). CONCLUSION: The CPR for sexually active women in this study was low at 39.3%. To promote contraceptive use in similar rural populations, family planning programmes should focus on increasing men's approval of contraception, improving partner communication around family planning and bolstering women's confidence in their reproductive decision-making, and particularly their self-esteem. There should be greater focus on nulliparous women

Large Modeling Uncertainty in Projecting Decadal Surface Ozone Changes Over City Clusters of China

Climate policies will affect future surface ozone pollution in China. Here, we simulate changes in summertime ozone across China by 2030 under four emission scenarios reflecting different levels of climate action. We also contrast results obtained with two different chemical mechanisms employed in the chemical transport model (WRF-Chem). With emission reductions in ozone precursors introduced by climate policies, both mechanisms show promising ozone mitigation for most parts of China. However, they disagree starkly in China\u27s three main city clusters, where one mechanism projects worsening ozone pollution by 2030 despite the emission reductions. We analyze possible drivers of this important discrepancy, in particular the role of varying ozone chemical regimes affecting its sensitivity to emission changes. We recommend an intercomparison project to examine this critical modeling uncertainty among other models/mechanisms, which would be invaluable for informing local and regional emission control strategies that are based on single-model results

A right-handed isotropic medium with a negative refractive index

The sign of the refractive index of any medium is soley determined by the requirement that the propagation of an electromagnetic wave obeys Einstein causality. Our analysis shows that this requirement predicts that the real part of the refractive index may be negative in an isotropic medium even if the electric permittivity and the magnetic permeability are both positive. Such a system may be a route to negative index media at optical frequencies. We also demonstrate that the refractive index may be positive in left-handed media that contain two molecular species where one is in its excited state.Comment: 4.1 pages, 4 figures, submitted to Physical Review Letter

Production and Titering of Recombinant Adeno-associated Viral Vectors

In recent years recombinant adeno-associated viral vectors (AAV) have become increasingly valuable for in vivo studies in animals, and are also currently being tested in human clinical trials. Wild-type AAV is a non-pathogenic member of the parvoviridae family and inherently replication-deficient. The broad transduction profile, low immune response as well as the strong and persistent transgene expression achieved with these vectors has made them a popular and versatile tool for in vitro and in vivo gene delivery. rAAVs can be easily and cheaply produced in the laboratory and, based on their favourable safety profile, are generally given a low safety classification. Here, we describe a method for the production and titering of chimeric rAAVs containing the capsid proteins of both AAV1 and AAV2. The use of these so-called chimeric vectors combines the benefits of both parental serotypes such as high titres stocks (AAV1) and purification by affinity chromatography (AAV2). These AAV serotypes are the best studied of all AAV serotypes, and individually have a broad infectivity pattern. The chimeric vectors described here should have the infectious properties of AAV1 and AAV2 and can thus be expected to infect a large range of tissues, including neurons, skeletal muscle, pancreas, kidney among others. The method described here uses heparin column purification, a method believed to give a higher viral titer and cleaner viral preparation than other purification methods, such as centrifugation through a caesium chloride gradient. Additionally, we describe how these vectors can be quickly and easily titered to give accurate reading of the number of infectious particles produced

The 18S ribosomal RNA sequence of the sea anemone <i>Ammonia sulcata</i> and its evolutionary position among other eukaryotes

Evolutionary trees based on partial small ribosomal subunit RNA sequences of 22 metazoa species have been published [(1988) Science 239, 748-753]. In these trees, cnidarians (Radiata) seemed to have evolved independently from the Bilateria, which is in contradiction with the general evolutionary view. In order to further investigate this problem, the complete srRNA sequence of the sea anemone Ammonia sulcata was determined and evolutionary trees were constructed using a matrix optimization method. In the tree thus obtained the sea anemone and Bilateria together form a monophyletic cluster, with the sea anemone forming the first line of descent of the metazoan group