China’s methadone maintenance treatment program was initiated in 2004 as a small pilot project in just eight sites. It has since expanded into a nationwide program encompassing more than 680 clinics covering 27 provinces and serving some 242 000 heroin users by the end of 2009. The agencies that were tasked with the program’s expansion have been confronted with many challenges, including high drop-out rates, poor cooperation between local governing authorities and poor service quality at the counter. In spite of these difficulties, ongoing evaluation has suggested reductions in heroin use, risky injection practices and, importantly, criminal behaviours among clients, which has thus provided the impetus for further expansion. Clinic services have been extended to offer clients a range of ancillary services, including HIV, syphilis and hepatitis C testing, information, education and communication, psychosocial support services and referrals for treatment of HIV, tuberculosis and sexually transmitted diseases. Cooperation between health and public security officials has improved through regular meetings and dialogue. However, institutional capacity building is still needed to deliver sustainable and standardized services that will ultimately improve retention rates. This article documents the steps China made in overcoming the many barriers to success of its methadone program. These lessons might be useful for other countries in the region that are scaling-up their methadone programs.

Glyphosate, the most commonly used herbicide in the world, controls a wide range of plant species, mainly because plants have little capacity to metabolize (detoxify) glyphosate. Massive glyphosate use has led to world-wide evolution of glyphosateresistant (GR) weed species, including the economically damaging grass weed Echinochloa colona. An Australian population of E. colona has evolved resistance to glyphosate with unknown mechanisms that do not involve the glyphosate target enzyme 5enolpyruvylshikimate-3-P synthase. GR and glyphosate-susceptible (S) lines were isolated from this population and used for resistance gene discovery. RNA sequencing analysis and phenotype/genotype validation experiments revealed that one aldoketo reductase (AKR) contig had higher expression and higher resultant AKR activity in GR than S plants. Two full-length AKR (EcAKR4-1 and EcAKR4-2) complementary DNA transcripts were cloned with identical sequences between the GR and S plants but were upregulated in the GR plants. Rice (Oryza sativa) calli and seedlings overexpressing EcAKR4-1 and displaying increased AKR activity were resistant to glyphosate. EcAKR4-1 expressed in Escherichia coli can metabolize glyphosate to produce aminomethylphosphonic acid and glyoxylate. Consistent with these results, GR E. colona plants exhibited enhanced capacity for detoxifying glyphosate into aminomethylphosphonic acid and glyoxylate. Structural modeling predicted that glyphosate binds to EcAKR4-1 for oxidation, and metabolomics analysis of EcAKR4-1 transgenic rice seedlings revealed possible redox pathways involved in glyphosate metabolism. Our study provides direct experimental evidence of the evolution of a plant AKR that metabolizes glyphosate and thereby confers glyphosate resistance.

Many of the important changes in evolution are regulatory in nature. Sequenced bacterial genomes point to flexibility in regulatory circuits but we do not know how regulation is remodeled in evolving bacteria. Here, we study the regulatory changes that emerge in populations evolving under controlled conditions during experimental evolution of Escherichia coli in a phosphate-limited chemostat culture. Genomes were sequenced from five clones with different combinations of phenotypic properties that coexisted in a population after 37 days. Each of the distinct isolates contained a different mutation in 1 of 3 highly pleiotropic regulatory genes (hfq, spoT, or rpoS). The mutations resulted in dissimilar proteomic changes, consistent with the documented effects of hfq, spoT, and rpoS mutations. The different mutations do share a common benefit, however, in that the mutations each redirect cellular resources away from stress responses that are redundant in a constant selection environment. The hfq mutation lowers several individual stress responses as well the small RNA–dependent activation of rpoS translation and hence general stress resistance. The spoT mutation reduces ppGpp levels, decreasing the stringent response as well as rpoS expression. The mutations in and upstream of rpoS resulted in partial or complete loss of general stress resistance. Our observations suggest that the degeneracy at the core of bacterial stress regulation provides alternative solutions to a common evolutionary challenge. These results can explain phenotypic divergence in a constant environment and also how evolutionary jumps and adaptive radiations involve altered gene regulation.

The majority of plant viruses are vectored by arthropods via persistent-circulative or noncirculative transmission. Previous studies have shown that specific binding sites for noncirculative viruses reside within the stylet or foregut of insect vectors, whereas the transmission mechanisms of circulative viruses remain ambiguous. Here we report the critical roles of whitefly primary salivary glands (PSGs) in the circulative transmission of two begomoviruses. The Middle East Asia Minor 1 (MEAM1) species of the whitefly Bemisia tabaci complex efficiently transmits both Tomato yellow leaf curl China virus (TYLCCNV) and Tomato yellow leaf curl virus (TYLCV), whereas the Mediterranean (MED) species transmits TYLCV but not TYLCCNV. PCR and fluorescence in situ hybridization experiments showed that TYLCCNV efficiently penetrates the PSGs of MEAM1 but not MED whiteflies. When a fragment of the coat protein of TYLCCNV was exchanged with that of TYLCV, mutated TYLCCNV accumulated in the PSGs of MED whiteflies, while mutant TYLCV was nearly undetectable. Confocal microscopy revealed that virion transport in PSGs follows specific paths to reach secretory cells in the central region, and the accumulation of virions in the secretory region of PSGs was correlated with successful virus transmission. Our findings demonstrate that whitefly PSGs, in particular the cells around the secretory region, control the specificity of begomovirus transmission. IMPORTANCEOver 75% of plant viruses are transmitted by insects. However, the mechanisms of virus transmission by insect vectors remain largely unknown. Begomoviruses and whiteflies are a complex of viruses and vectors which threaten many crops worldwide. We investigated the transmission of two begomoviruses by two whitefly species. We show that specific cells of the whitefly primary salivary glands control viral transmission specificity and that virion transport in the glands follows specific paths to reach secretory cells in the central region and then to reach the salivary duct. Our results indicate that the secretory cells in the central region of primary salivary glands determine the recognition and transmission of begomoviruses. These findings set a foundation for future research not only on circulative plant virus transmission but also on other human and animal viruses transmitted by arthropod vectors.