Accessory genes are variably present among members of a species and are a reservoir of adaptive functions. In bacteria, differences in gene distributions among individuals largely result from mobile elements that acquire and disperse accessory genes as cargo. In contrast, the impact of cargo-carrying elements on eukaryotic evolution remains largely unknown. Here, we show that variation in genome content within multiple fungal species is facilitated by Starships, a novel group of massive mobile elements that are 110 kb long on average, share conserved components, and carry diverse arrays of accessory genes. We identified hundreds of Starship-like regions across every major class of filamentous Ascomycetes, including 28 distinct Starships that range from 27-393 kb and last shared a common ancestor ca. 400 mya. Using new long-read assemblies of the plant pathogen Macrophomina phaseolina, we characterize 4 additional Starships whose past and ongoing activities contribute to standing variation in genome structure and content. One of these elements, Voyager, inserts into 5S rDNA and contains a candidate virulence factor whose increasing copy number has contrasting associations with pathogenic and saprophytic growth, suggesting Voyager activity underlies an ecological trade-off. We propose that Starships are eukaryotic analogs of bacterial integrative and conjugative elements based on parallels between their conserved components and may therefore represent the first known agents of active gene transfer in eukaryotes. Our results suggest that Starships have shaped the content and structure of fungal genomes for millions of years and reveal a new concerted route for evolution throughout an entire eukaryotic phylum.

Ten morphological groups of plant-parasitic nematodes (spiral, lesion, lance, dagger, stunt, pin, ring, stubby-root, cyst, and miscellaneous tylenchids) were detected in corn fields in Ohio, but the presence and population density of these groups varied among fields. Binary and ordinal logistic regression models were fitted to the data to estimate the odds of each group being present, and the lesion, lance, spiral, and pin nematode population densities being at moderate-high risk levels based on soil region, cropping sequence, tillage, and soil pH, silt content, and electrical conductivity. All covariates were associated with at least one nematode group, but soil region had the greatest and most consistent effect. Dagger and ring nematodes were more likely to be present in region 6 than in any of the other regions, whereas lance, stunt, pin, stubby-root, and spiral nematodes were more likely to be present in regions 1 to 5 than 6. Spiral, lance, and pin nematode population densities were more likely to be at moderate-high risk levels in regions 3 and 4 than in region 6. Fields under conservation tillage were two times more likely to have moderate-high risk lance nematode population densities than fields under conventional tillage. Similarly, pin nematode population densities were two times more likely to be at moderate-high risk levels in fields under rotation than in continuous corn. For every unit increase in soil pH, the odds of the spiral nematode population density being at moderate-high risk levels increased by 43%, but the odds of the lesion and pin nematode population densities being at the same risk level decreased by 63 and 29%, respectively. The predicted probability of lesion and lance population densities being at moderate-high risk levels decreased as the silt content of the soil increased. These finding will be useful for developing future nematode sampling protocols and for assessing the risk associated with nematodes in corn fields in Ohio.

Soil samples were collected from 425 corn fields in 28 Ohio counties between growth stages V3 and V6 during the 2013 and 2014 growing seasons. Ten morphological groups of plant-parasitic nematodes, namely spiral, lesion, lance, dagger, stunt, pin, ring, stubby-root, cyst, and “tylenchids” (several genera morphologically similar to members of the subfamily Tylenchinae [NCBI Taxonomy] including Cephelenchus, Filenchus, Malenchus, and Tylenchus) were identified. Eight species belonging to six of these groups were characterized. Spiral, tylenchids, lesion, pin, lance, stunt, and dagger nematodes were detected in 94, 96, 80, 57, 48, 48, and 37% of the fields, respectively, whereas the stubby-root, cyst, and ring nematodes were present in fewer than 14% of the samples. Averaged across fields, the spiral, tylenchids, and pin nematodes had the highest mean population densities. For all groups, incidence and population density varied among counties, and in some cases, among soil regions and cropping practices. Both population parameters were heterogeneous at multiple spatial scales, with the lowest heterogeneity among soil regions and the highest among fields within county and soil region. Estimated variances at the soil region level were not significantly different from zero for most of the nematodes evaluated. Stunt and lance were two of the most variable groups at all tested spatial scales. In general, the population densities were significantly more heterogeneous at the field level than at the county level. Findings from this study will be useful for developing sampling protocols and establishing on-farm trials to estimate losses and evaluate nematode management strategies.

Introducción: La aflatoxina M1 (AFM1) es un metabolito tóxico derivado de la aflatoxina B. Su ingestión en lactantes se ha relacionado con retraso en el crecimiento, aumento de susceptibilidad a enfermedades infecciosas, reducción de la eficiencia en la inmunización y cirrosis. En Paraguay se recomienda lactancia exclusiva hasta los 6 meses, sin embargo se comercializan diferentes marcas de fórmulas infantiles dirigidas a lactantes menores de 6 meses. Objetivo: Detectar y cuantificar la presencia de AFM1 en fórmulas para lactantes comercializadas en el Área Metropolitana. Materiales y Métodos: Se adquirieron fórmulas fluidas (n=18) y en polvo (n=91) para lactantes de 0 a 12 meses de farmacias y supermercados del Área Metropolitana de Asunción y fueron analizados mediante el ensayo de inmunoafinidad ligado a enzimas (ELISA). Resultados: 9,75% (0 a 6 meses) y 2% (6 a 12 meses) de las fórmulas lácteas en polvo y 100% de las fórmulas fluidas resultaron positivas para AFM1. La mediana de contenido de AFM1 en formulas en polvo fue de 1820 ng/kg y 510 ng/kg en las marcas A y B. En las fórmulas líquidas fue de 31,8 ng/kg y 33,6 ng/kg para las dos marcas analizadas respectivamente, p=0,0001. Conclusiones: Se detectó AFM1 en todas las fórmulas líquidas analizadas, y en el 2 y 9,7% de las fórmulas en polvo de las marcas Ay B respectivamente Los niveles de AFM1 fueron mayores en las fórmulas en polvo. Conflicto de interés: Los autores declaran no poseer conflicto de interés Recibido: 16/11/2020 Aceptado: 12/02/2021