Regulation and structure of YahD, a copper-inducible α/β serine hydrolase of Lactococcus lactis IL1403

Lactococcus lactis IL1403 is a lactic acid bacterium that is used widely for food fermentation. Copper homeostasis in this organism chiefly involves copper secretion by the CopA copper ATPase. This enzyme is under the control of the CopR transcriptional regulator. CopR not only controls its own expression and that of CopA, but also that of an additional three operons and two monocistronic genes. One of the genes under the control of CopR, yahD, encodes an α/β-hydrolase. YahD expression was induced by copper and cadmium, but not by other metals or oxidative or nitrosative stress. The three-dimensional structure of YahD was determined by X-ray crystallography to a resolution of 1.88 Å. The protein was found to adopt an α/β-hydrolase fold with the characteristic Ser-His-Asp catalytic triad. Functional testing of YahD for a wide range of substrates for esterases, lipases, epoxide hydrolases, phospholipases, amidases and proteases was, however, unsuccessful. A copper-inducible serine hydrolase has not been described previously and YahD appears to be a new functional member of this enzyme famil

Phage capsid nanoparticles with defined ligand arrangement block influenza virus entry

Multivalent interactions at biological interfaces occur frequently in nature and mediate recognition and interactions in essential physiological processes such as cell-to-cell adhesion. Multivalency is also a key principle that allows tight binding between pathogens and host cells during the initial stages of infection. One promising approach to prevent infection is the design of synthetic or semisynthetic multivalent binders that interfere with pathogen adhesion1,2,3,4. Here, we present a multivalent binder that is based on a spatially defined arrangement of ligands for the viral spike protein haemagglutinin of the influenza A virus. Complementary experimental and theoretical approaches demonstrate that bacteriophage capsids, which carry host cell haemagglutinin ligands in an arrangement matching the geometry of binding sites of the spike protein, can bind to viruses in a defined multivalent mode. These capsids cover the entire virus envelope, thus preventing its binding to the host cell as visualized by cryo-electron tomography. As a consequence, virus infection can be inhibited in vitro, ex vivo and in vivo. Such highly functionalized capsids present an alternative to strategies that target virus entry by spike-inhibiting antibodies5 and peptides6 or that address late steps of the viral replication cycle

Impact of Third-Party Enforcement of Contracts in Agricultural Markets - A Field Experiment in Vietnam

We study the effect of alleviating information asymmetry regarding product quality that is widespread in developing-country agricultural markets. Opportunistic buyers may underreport quality levels back to farmers to reduce the price they have to pay. In response, farmers may curb investment, negatively affecting farm productivity. In an experiment, we entitle randomly selected smallholder dairy farmers in Vietnam to independently verify milk testing results. Treatment farmers use 13 percent more inputs and also increase their output. We show that the buying company had initially not underreported product quality, which is why third-party monitoring led to a Pareto improvement in the supply chain

Impact of Third-Party Enforcement of Contracts in Agricultural Markets–A Field Experiment in Vietnam

Asymmetry of information is a fundamental problem in agricultural markets. Production contracts remain incomplete if product quality attributes measured by the buying company remain unobservable for the selling farmer. Opportunistic buyers would report lower than actual output quality, negatively affecting farmers’ compensation given it is directly linked to quality. When farmers factor in the buyer’s opportunistic behavior, underinvestment may occur, negatively affecting farm productivity. Using the example of the Vietnamese dairy industry, a field experiment is conducted in which randomly selected dairy farmers are entitled to independently verify milk testing results. Farm-level output data are complemented with household information from two rounds of comprehensive surveys conducted before and at the end of the intervention. We find a 10 percent higher use of inputs for treatment farmers, also resulting in significantly higher dairy output; welfare levels increase for a specific subgroup of farmers. As the buying company had not underreported output quality despite the existing information asymmetry, third-party enforcement enabled the company to credibly signal its fair type to farmers, leading to a Pareto improvement in the supply chain. While producers benefit directly from higher farm productivity, buying companies are better off due to lower per-unit transaction costs when procuring the farm output

Impact of Third-Party Enforcement of Contracts in Agricultural Markets – A Field Experiment in Vietnam

We study the effect of alleviating information asymmetry regarding product quality that is widespread in developing-country agricultural markets. Opportunistic buyers may underreport quality levels back to farmers to reduce the price they have to pay. In response, farmers may curb investment, negatively affecting farm productivity. In an experiment, we entitle randomly selected smallholder dairy farmers in Vietnam to independently verify milk testing results. Treatment farmers use 13 percent more inputs and also increase their output. We show that the buying company had initially not underreported product quality, which is why third-party monitoring led to a Pareto improvement in the supply chain

Contract farming and smallholder incentives to produce high quality: experimental evidence from the Vietnamese dairy sector

In emerging markets for high-value food products in developing countries, processing companies search for efficient ways to source raw material of consistent quality. One widely embraced approach is contract farming. But relatively little is known about the appropriate design of contracts, especially in a small farm context. We use the example of the Vietnamese dairy sector to analyze the effectiveness of existing contracts between a processor and smallholder farmers in terms of incentivizing the production of high quality milk. A framed field experiment is conducted to evaluate the impact of two incentive instruments, a price penalty for low quality and a bonus for consistent high quality milk, on farmers’ investment in quality-improving inputs. Statistical analysis suggests that the penalty drives farmers into higher input use, resulting in better output quality. The bonus payment generates even higher quality milk. We also find that input choice levels depend on farmers’ socio- economic characteristics such as wealth, while individual risk preferences seem to be less important. Implications for the design of contracts with smallholders are discussed

Experimental evidence from the Vietnamese dairy sector

PRIFPRI3; ISI; GRP23; CRP2MTID; PIMCGIAR Research Program on Policies, Institutions, and Markets (PIM

Impact of third-party enforcement of contracts in agricultural markets—A field experiment in Vietnam

Chapter 11 (Saenger et al.) provides a perfect example of a randomized controlled impact evaluation. The authors conducted a randomized controlled trial and field experiment with dairy farmers and a milk-processing company in Vietnam. Their approach, designed ex ante, is a theoretically ideal approach to constructing a valid counterfactual and to ensuring that there is no selection bias, given that the farmers are randomly assigned to treatment (beneficiaries) and control groups. This randomization ensures that all farmers have the same chance of participating in the program and that the distribution of the two groups’ characteristics (both observed and unobserved) are statistically indistinguishable. The authors tested whether the quality-control procedures used by the processing company were leading farmers to underinvest. The risk on the farmers’ part came from the possibility that the company would manipulate the process and say that the milk delivered was of low quality and therefore deserved a lower price. By introducing vouchers for third-party quality measurement, the program improved the company’s credibility with the farmers. With this increased trust, the farmers then had more incentive to invest in techniques to improve milk quality and increase revenue. This chapter is unique in that it focuses on the mechanisms and incentives for different value-chain actors to contract with one another. The authors’ proposed contract-farming designs make both parties better off, rather than trying to cut out the intermediary or encourage smallholders to take over other capacities in the value chain.PRIFPRI1; CRP2; C Improving markets and tradeMTID; PIMCGIAR Research Program on Policies, Institutions, and Markets (PIM

Impact of third-party contract enforcement in agricultural markets—A field experiment in Vietnam

PRIFPRI3; ISI; CRP2; C.2 Institutions and Infrastructure for market development; flagship 3MTID; PIMCGIAR Research Program on Policies, Institutions, and Markets (PIM

Regulation and structure of YahD, a copper-inducible / serine hydrolase of Lactococcus lactis IL1403

Lactococcus lactis IL1403 is a lactic acid bacterium that is used widely for food fermentation. Copper homeostasis in this organism chiefly involves copper secretion by the CopA copper ATPase. This enzyme is under the control of the CopR transcriptional regulator. CopR not only controls its own expression and that of CopA, but also that of an additional three operons and two monocistronic genes. One of the genes under the control of CopR, yahD, encodes an α/β-hydrolase. YahD expression was induced by copper and cadmium, but not by other metals or oxidative or nitrosative stress. The three-dimensional structure of YahD was determined by X-ray crystallography to a resolution of 1.88 Å. The protein was found to adopt an α/β-hydrolase fold with the characteristic Ser-His-Asp catalytic triad. Functional testing of YahD for a wide range of substrates for esterases, lipases, epoxide hydrolases, phospholipases, amidases and proteases was, however, unsuccessful. A copper-inducible serine hydrolase has not been described previously and YahD appears to be a new functional member of this enzyme family