Consumer characteristics and preferences for mobulid gill plates in China.

Mobulid species are endangered globally, and the market trade for gill plates is believed to be a major threat. Successful conservation and the sustainable use of mobulids therefore require an objective understanding of consumer characteristics and preferences for gill plates. Previous studies focused on qualitative descriptions, and reliable quantitative analyses are currently lacking. We used a latent class choice experiment method and a semistructured questionnaire to provide important new quantitative information about gill plate consumer characteristics and the heterogeneous nature of demand for gill plates. From May to July 2019, we conducted a field study in Guangzhou, the primary consumption hub for mobulid gill plates in mainland China. Utilizing a simple random sampling method, we engaged in face-to-face interviews with 428 consumers of gill plates in the major trading markets in Guangzhou. Our results showed that 59.8% of consumers of gill plates were over 40 years old, 62.6% were female, 80.7% had annual household incomes of <200,000 yuan, and 84.5% recognized the medical and health value of gill plates and purchased them. About seventy-two percent of consumers preferred to purchase imported and less expensive gill plates from unprotected species, but they had a strong preference for large gill plates from protected species, such as Mobula birostris. This contradiction arose from consumers' lack of knowledge of mobulids and their conservation status. We found, for example, female consumers over 40 years old had the least understanding of conservation status of mobulid species and the link between size of gill plates and rarity of mobulids. This suggests there may be opportunities to promote mobulid conservation through education and marketing targeted at this demographic. Consumers who had a positive preference for gill plates from protected species (regardless of price) (10%) may be harder to influence. Overall, we believe education alone is not enough and that the conservation of mobulids would benefit from an integrated approach that involves conservation education and strengthened trade regulations, such as the introduction of traceability systems and a stiffer legal framework for consumption of protected species.

Características y preferencias de los consumidores de placas branquiales de mobúlidos en China Resumen Las especies de mobúlidos están en peligro de extinción en todo el mundo y se considera al mercado de placas branquiales como una amenaza principal. Por lo tanto, la conservación exitosa y el uso sustentable de los mobúlidos requiere del entendimiento objetivo de las características y preferencias de los consumidores de estas placas branquiales. Los estudios previos se han enfocado en descripciones cualitativas, por lo que actualmente no hay suficientes análisis cuantitativos confiables. Usamos un método de experimento de elección de clase latente y un cuestionario semiestructurado para proporcionar información cuantitativa nueva e importante sobre las características de los consumidores de placas branquiales y la naturaleza heterogénea de la demanda de estas placas. Realizamos un estudio de campo entre mayo y julio de 2019 en Guangzhou, el principal centro de consumo de placas branquiales de mobúlidos en el interior de China. Utilizamos un método de muestreo aleatorio simple para entrevistar cara-a-cara a 428 consumidores de placas branquiales en los principales mercados de Guangzhou. Nuestros resultados mostraron que el 59.8% de los consumidores son mayores a 40 años, 62.6% son mujeres, 80.7% tienen un ingreso doméstico anual mayor a 200,000 yuan y 84.5% reconocieron el valor médico y para la salud que tienen las placas branquiales, razones por las que las compran. El 72% de los consumidores prefirió comprar las placas importadas y menos caras de especies no protegidas, aunque tuvieron una mayor preferencia por las placas más grandes de las especies protegidas, como Mobula birostris. Esta contradicción se debe a la falta de conocimiento que tienen los consumidores sobre los mobúlidos y su estado de conservación. Descubrimos que, por ejemplo, las consumidoras de más de 40 años tienen el menor conocimiento del estado de conservación de los mobúlidos y la conexión entre el tamaño de las placas branquiales y la rareza de la especie. Lo anterior sugiere que podría haber oportunidad de promover la conservación de los mobúlidos por medio de la educación y la mercadotecnia enfocada en este grupo demográfico. Podría ser más difícil influir sobre el 10 % de los consumidores, el cual tiene una preferencia positiva por las placas branquiales de las especies protegidas (sin importar el precio). En general creemos que la educación por sí sola no es suficiente y que la conservación de los mobúlidos se beneficiaría de una estrategia integrada que involucre la educación para la conservación y regulaciones de mercado fortalecidas, como la introducción de los sistemas de trazabilidad y un marco legal más rígido para el consumo de las especies protegidas.

Molecular dynamics simulations of ligand-induced backbone conformational changes in the binding site of the periplasmic lysine-, arginine-, ornithine-binding protein.

The periplasmic lysine-, arginine-, ornithine-binding protein (LAOBP) traps its ligands by a large hinge bending movement between two globular domains. The overall geometry of the binding site remains largely unchanged between the open (unliganded) and closed (liganded) forms, with only a small number of residues exhibiting limited movement of their side chains. However, in the case of the ornithine-bound structure, the backbone peptide bond between Asp11 and Thr12 undergoes a large rotation. Molecular dynamics simulations have been used to investigate the origin and mechanism of this backbone movement. Simulations allowing flexibility of a limited region and of the whole binding site, with and without bound ligands, suggest that this conformational change is induced by the binding of ornithine, leading to the stabilisation of an energetically favourable alternative conformation.

Molecular modelling prediction of ligand binding site flexibility.

We have investigated the efficacy of generating multiple sidechain conformations using a rotamer library in order to find the experimentally observed ligand binding site conformation of a protein in the presence of a bound ligand. We made use of a recently published algorithm that performs an exhaustive conformational search using a rotamer library to enumerate all possible sidechain conformations in a binding site. This approach was applied to a dataset of proteins whose structures were determined by X-ray and NMR methods. All chosen proteins had two or more structures, generally involving different bound ligands. By taking one of these structures as a reference, we were able in most cases to successfully reproduce the experimentally determined conformations of the other structures, as well as to suggest alternative low-energy conformations of the binding site. In those few cases where this procedure failed, we observed that the bound ligand had induced a high-energy conformation of the binding site. These results suggest that for most proteins that exhibit limited backbone motion, ligands tend to bind to low energy conformations of their binding sites. Our results also reveal that it is possible in most cases to use a rotamer search-based approach to predict alternative low-energy protein binding site conformations that can be used by different ligands. This opens the possibility of incorporating alternative binding site conformations to improve the efficacy of docking and structure-based drug design algorithms.