Arapaima gigas is a large air-breathing fish found in Amazonian rivers, a characteristic that gives this species an advantage in oxygen-deprived waters. It shows high potential for aquaculture in the Amazon region due to its fast growth rate that approaches 10–15 kg/year. The aim of this study was to explore the composition of the intestinal bacterial community of Arapaima gigas reared in Ecuador using 16S rRNA gene high-throughput sequencing. The analysis revealed significant differences in alpha diversity indices (p < 0.05) and differential distribution of minor components of the intestinal microbiome between small and large fish. However, components with greater relative abundance, such as Cetobacterium, are found in similar proportions.

Atlantic salmon (Salmo salar) is a carnivorous fish species whose productive performance tends to be suboptimal when fed low-cost carbohydrate rich meals. It is of interest to study the dynamics of gut microbiota communities in salmonids fed high carbohydrate diets since gut microbes are referred to as key players that influence the metabolism and physiology of the host. A study was conducted to determine the effect of feeding a high carbohydrate diet to Atlantic salmon in gut microbiota communities. A medium carbohydrate (15% wheat starch)/medium protein (MC/MP) diet or a high carbohydrate (30% wheat starch)/low protein (HC/LP) diet was fed to triplicate tanks (28 fish each) during four weeks. We conducted an in-depth characterization of the distal intestine digesta microbiota using high-throughput sequencing of the V4 region of the 16S rRNA gene. Firmicutes, Actinobacteria and Proteobacteria were the major phyla determined in either experimental group. Phylum Planctomycetes, class Planctomycetia, order Planctomycetales and genus Lactococcus were significantly more abundant in fish fed the HC/LP diet compared with fish fed the MC/MP diet. Our study suggests feeding a carbohydrate rich meal to salmon exerts a low impact on the structure of gut microbial communities, affecting mostly low-abundance bacteria capable of metabolizing anaerobically carbohydrates as a major energy-yielding substrate.

Precarious labour research has highlighted the multidimensional factors shaping migrants’ vulnerability to labour exploitation. This article takes a different approach by attending to the possible reciprocity in labour relations– despite unequal power dynamics– particularly when workplaces are small and involve daily interactions between migrant workers and migrant employers. Methodology is based on observations in Chinese-run retail shops and restaurants in Santiago, and interviews with Chinese employers and their Latin American migrant employees of diverse backgrounds. Proposing the concept of “precarious labour relations”, we examine the independent and shared uncertainties between migrant employers and workers who are differently marginalized through race/migrant status axes in Chile. Analyzing dynamics of hierarchy, (mis)trust, and reciprocity in how these actors negotiate precarity and security as workers and/or migrants, we complicate dichotomies of exploitation and resistance in migrant labour research, by foregrounding the multidimensional relationship between employers and workers when both are racialized migrants and minorities.

Multicultural commercial neighbourhoods are key spaces where individuals learn to relate to cultural difference in increasingly diverse cities worldwide. Host countries’ pre-existing social dynamics and environmental conditions mutually shape everyday interactions between people from different ethnonational backgrounds within specific spaces. This article examines two kinds of community-making practices consisting of both intra-ethnic and inter-ethnic exchanges and collaborations, under conditions of shared insecurity in a multicultural commercial neighbourhood in Santiago, Chile. Drawing on ethnic Chinese experiences and responses to crime, we discuss how inhabitants of multicultural sites create more hospitable spaces by building and overcoming boundaries with co-ethnics, other migrants and ‘locals’. Our ethnographic study finds that Chinese residents engaged in what we term ‘strategic ethnic groupism’, which aims to prompt the solidarity of an ‘ethnic-based’ collective in order to politically organise towards long-term solutions. Yet, simultaneously, with other migrants and citizens, the Chinese negotiated everyday intercultural conviviality through creating relations of trust and care to address more immediate insecurity concerns. Discussing both strategies, this article contributes to understanding the productive frictions between ethnicity, community and belonging, under shared conditions of insecurity, in multicultural urban spaces.

Intestinal microbiota has been involved in several processes that benefit the host, such as digestion, nutrient metabolism, resistance to pathogens colonization and immune function. In this study, we investigated the diversity, composition and functional prediction of microbiota of reared Seriolella violacea (palm ruff) in the same cohort sampled at different times (7-, 8- and 9-month-old). Microbial community structure analyses, using 16S rRNA amplicon sequencing, revealed that the intestinal microbiota was dominated by the phyla Firmicutes, Proteobacteria, Fusobacteria and Tenericutes. At the genus level, Candidatus Arthromitus was the most abundant in all sampled timepoints, representing in average 78% of the bacterial community (ranging from 18 to 98%), corresponding to segmented filamentous bacteria, which are interesting because they have been associated with the maturation of immune responses in the gut and protecting the host from bacterial infections. The comparisons of the intestinal microbiota among the three groups showed differences in abundance of bacterial taxa and also in alpha diversity indexes (Shannon and Simpson), as well as beta diversity metrics (weighted and unweighted UniFrac). Potential functions of the intestinal microbiota of palm ruff were retrieved using Philipin and Tax4fun and these analyses revealed high levels of genes for sugar metabolism. To our knowledge, this study represents the first description of the intestinal microbiota of S. violacea.

El presente artículo tiene como objetivo revisar la literatura vinculada a los estudios sobre cuidados transnacionales, específicamente a la población adulta que queda en el país de origen cuando los hijos emigran. Para esto, se ha realizado una búsqueda, revisión y sistematización de la literatura internacional (libros y artículos) y de revistas de estudios migratorios, de género y familia. Planteamos que en esta discusión convergen dos ejes analíticos. El primero de ellos proviene de los estudios sobre familias migrantes transnacionales y el segundo, de los estudios sobre cuidados. A través de la revisión de la literatura identificamos los principales aportes que cada uno de estos ejes entrega al análisis de los cuidados de las personas mayores en contextos migratorios transnacionales y revisamos a su vez algunas ausencias y puntos ciegos con el objetivo de puntualizar agendas emergentes de investigación en esta temática.