To each his own: no evidence of gyrodactylid parasite host switches from invasive poeciliid fishes to Goodea atripinnis, the most dominant endemic freshwater goodeid fish in the Mexican Highlands

Background: Goodeid topminnows are live-bearing fishes endemic to the Mexican Highlands (Mesa Central, MC). Unfortunately, in the MC, environmental degradation and introduced species have pushed several goodeid species to the brink of extinction. Invasive fishes can introduce exotic parasites, and the most abundant goodeid, blackfin goodea Goodea atripinnis Jordan, is parasitised by six exotic helminths. Poeciliids are widely dispersed invasive fishes, which exert negative ecological effects on goodeids. Poeciliids host several species of the monogenean genus Gyrodactylus von Nordmann, 1832, including pathogenic, invasive parasites. Here, we looked for evidence of Gyrodactylus species switching hosts from poeciliids to goodeids.  Methods: Fish were collected in rivers draining the MC into both sides of the continental divide. Hosts were screened for gyrodactylid parasites in localities where G. atripinnis and poeciliids occurred sympatrically. Gyrodactylus specimens were characterised morphologically (attachment apparatus) and molecularly (internal transcribed spacer region, ITS). A Bayesian phylogenetic tree using ITS sequences established relationships between gyrodactylids collected from goodeid fishes and those from parasites infecting poeciliids.  Results: Gyrodactylids were collected from G. atripinnis in six localities on both sides of the watershed where exotic poeciliids occurred sympatrically. Morphological and molecular analyses indicated the presence of four undescribed species of Gyrodactylus infecting this goodeid host. Gyrodactylus tomahuac n. sp., the most abundant and geographically widespread species, is described here. The other three Gyrodactylus spp. are not described, but their ITS sequences are used as molecular data presented here, are the only available for gyrodactylids infecting goodeid fishes. Morphological and molecular data suggest that two distinct groups of gyrodactylids infect goodeids, one of which shares a common ancestor with gyrodactylids parasitizing poeciliids.  Conclusions: No evidence was found of gyrodactylids switching hosts from invasive poeciliids to endemic goodeids, nor vice versa. Moreover, considering that G. atripinnis is known to host both Gyrodactylus lamothei Mendoza-Palmero, Sereno-Uribe & Salgado-Maldonado, 2009 and Gyrodactylus mexicanus Mendoza-Palmero, Sereno-Uribe & Salgado-Maldonado, 2009, with the addition of G. tomahuac n. sp. and the three undescribed Gyrodactylus spp. reported, at least six gyrodactylids may infect this host. This would make monogeneans the second most abundant parasite group infecting G. atripinnis, which to date is known to harbour 22 helminth species: nine digeneans, five nematodes, four cestodes, three monogeneans and one acanthocephalan

Genetic Evidence for Multiple Sources of the Non-Native Fish Cichlasoma urophthalmus (Günther; Mayan Cichlids) in Southern Florida

The number and diversity of source populations may influence the genetic diversity of newly introduced populations and affect the likelihood of their establishment and spread. We used the cytochrome b mitochondrial gene and nuclear microsatellite loci to identify the sources of a successful invader in southern Florida, USA, Cichlasoma urophthalmus (Mayan cichlid). Our cytochrome b data supported an introduction from Guatemala, while our microsatellite data suggested movement of Mayan Cichlids from the upper Yucatán Peninsula to Guatemala and introductions from Guatemala and Belize to Florida. The mismatch between mitochondrial and nuclear genomes suggests admixture of a female lineage from Guatemala, where all individuals were fixed for the mitochondrial haplotype found in the introduced population, and a more diverse but also relatively small number of individuals from Belize. The Florida cytochrome b haplotype appears to be absent from Belize (0 out of 136 fish screened from Belize had this haplotype). Genetic structure within the Florida population was minimal, indicating a panmictic population, while Mexican and Central American samples displayed more genetic subdivision. Individuals from the Upper Yucatán Peninsula and the Petén region of Guatemala were more genetically similar to each other than to fish from nearby sites and movement of Mayan Cichlids between these regions occurred thousands of generations ago, suggestive of pre-Columbian human transportation of Mayan Cichlids through this region. Mayan Cichlids present a rare example of cytonuclear disequilibrium and reduced genetic diversity in the introduced population that persists more than 30 years (at least 7–8 generations) after introduction. We suggest that hybridization occurred in ornamental fish farms in Florida and may contribute their establishment in the novel habitat. Hybridization prior to release may contribute to other successful invasions

Genetic Evidence for Multiple Sources of the Non-Native Fish \u3ci\u3eCichlasoma urophtalmus\u3c/i\u3e (Günther; Mayan Cichlids) in Southern Florida

The number and diversity of source populations may influence the genetic diversity of newly introduced populations and affect the likelihood of their establishment and spread. We used the cytochrome b mitochondrial gene and nuclear microsatellite loci to identify the sources of a successful invader in southern Florida, USA, Cichlasoma urophthalmus (Mayan cichlid). Our cytochrome b data supported an introduction from Guatemala, while our microsatellite data suggested movement of Mayan Cichlids from the upper Yucatán Peninsula to Guatemala and introductions from Guatemala and Belize to Florida. The mismatch between mitochondrial and nuclear genomes suggests admixture of a female lineage from Guatemala, where all individuals were fixed for the mitochondrial haplotype found in the introduced population, and a more diverse but also relatively small number of individuals from Belize. The Florida cytochrome b haplotype appears to be absent from Belize (0 out of 136 fish screened from Belize had this haplotype). Genetic structure within the Florida population was minimal, indicating a panmictic population, while Mexican and Central American samples displayed more genetic subdivision. Individuals from the Upper Yucatán Peninsula and the Petén region of Guatemala were more genetically similar to each other than to fish from nearby sites and movement of Mayan Cichlids between these regions occurred thousands of generations ago, suggestive of pre-Columbian human transportation of Mayan Cichlids through this region. Mayan Cichlids present a rare example of cytonuclear disequilibrium and reduced genetic diversity in the introduced population that persists more than 30 years (at least 7–8 generations) after introduction. We suggest that hybridization occurred in ornamental fish farms in Florida and may contribute their establishment in the novel habitat. Hybridization prior to release may contribute to other successful invasions

Impacto do exercício sobre o metabolismo dos lipídeos e da dislipidemia

The chronic practice of exercise induces a series of cellular and organismal adaptations that modify the way the human body metabolizes all macronutrients, including lipids. Endurance exercise and resistance exercise elicit different responses that result in differential effects on lipid and lipoprotein metabolism. These effects are quantitatively and qualitatively different and mediated by distinct signaling pathways. In this review, we summarize relevant evidence on the impact of exercise on lipid and lipoprotein metabolism, and finalize with some practical recommendations on exercise practice for patients with dyslipidemia in the primary care settingLa práctica crónica del ejercicio induce una serie de adaptaciones celulares y orgánicas que modifican la forma en que el cuerpo humano metaboliza todos los macronutrientes, incluidos los lípidos. El ejercicio de duración y el ejercicio de resistencia provocan diferentes respuestas que resultan en efectos diferenciales sobre el metabolismo de los lípidos y las lipoproteínas. Estos efectos son cuantitativa y cualitativamente diferentes y mediados por distintas vías de  señalización. Esta revisión, resume la evidencia pertinente sobre la repercusión del ejercicio en el metabolismo de los lípidos y las lipoproteínas, y finaliza con algunas recomendaciones sobre la práctica del ejercicio para los pacientes con dislipidemia en el ámbito de la atención primariaA prática crônica de exercício induz uma série de adaptações celulares e orgânicas que modificam a maneira pela qual o corpo humano metaboliza todos os macronutrientes, incluindo os lipídios. O exercício de duração e o exercício de resistência provocam diversas respostas que resultam em efeitos diferenciais no metabolismo de lipídios e lipoproteínas. Estes efeitos são quantitativa e qualitativamente distintos e mediados por diferentes vias de sinalização. Nesta revisão, se resume as evidências relevantes sobre o impacto do exercício no metabolismo de lipídios e das lipoproteínas e conclui, com algumas recomendações sobre a prática de exercícios para pacientes com dislipidemia no campo da atenção primári

Influencia de variables clínicas y lipídicas en la magnitud de la lipemia postpradial de sujetos con y sin hipertrigliceridemia

Introducción. La lipemia postprandial se caracteriza porel aumento de la permanencia en circulación delipoproteínas ricas en triglicéridos que pueden produciraterosclerosis siendo esta una importante causa de muerteen nuestro medio.Objetivo. Evaluar el efecto de variables lipídicas yantropométricas en la magnitud de la lipemia postprandialde sujetos con y sin hipertrigliceridemia.Material y métodos. Se estudiaron 48 sujetos de uno yotro género, con triglicéridos basales mayores a 200mg/dL,que ingirieron una carga lipídica estandarizada (desayunocon 30g de grasa) y fueron seguidos durante siete horasrecolectando sangre total cada hora para determinar lostriglicéridos postprandiales y con estos datos hallar lamagnitud de la lipemia postprandial. Este dato secorrelacionó con variables clínicas como la edad, el índicede masa corporal, la circunferencia de la cintura, entreotras y con variables lipídicas como colesterol total,colesterol de HDL y LDL y triglicéridos basales.Resultados. Se encontró alteración en el aclaramiento detriglicéridos postprandiales en sujetos que tenían una concentraciónbasal de triglicéridos por encima de 186 mg/dl.Las variables clínicas que más correlacionaron con la magnitudde la lipemia postprandial fueron la edad (p=0.009)y el perímetro de la cintura (p=0.043), mientras que lasvariables lipídicas mejor relacionadas con la lipemiapostprandial fueron la concentración de triglicéridosbasales (p

Crop residue grazing and tillage systems effects on soil physical properties and corn (Zea Mays L.) performance

Crop-livestock systems under no till (NT) could negatively affect soil physical properties and crop performance, due to the additive effects of reduced soil cover and cattle trampling due to livestock grazing, and the absence of tillage. We evaluated the effects of four grazing strategies and of a shallow tillage (ST) on soil physical properties and corn (Zea mays L.) performance for a mollisol after 15 years under crop-livestock systems under NT in Argentina. Grazing strategies evaluated were: closure (C), one grazing (OG), high stocking rate (HR) and farmer's management (FM), and the tillage systems were: NT and ST. Bulk density (BD), penetration resistance (PR), hydraulic conductivity (ks), plant population, surface root distribution, aboveground dry matter accumulation, aboveground total N (TN) accumulation and corn yield were evaluated. High stocking rate and FM increased RP. On the other hand, ST decreased PR and BD and increased ks. Corn yield was higher under ST than under NT, and under HR than under the other grazing strategies. Total N accumulation was higher under HR than under the rest of grazing strategies. Rational grazing management and use of tillage systems on resilient soils could have prevented soil physical properties be affected beyond critical thresholds.Facultad de Ciencias Agrarias y Forestale

Crop residue grazing and tillage systems effects on soil physical properties and corn (Zea Mays L.) performance

Crop-livestock systems under no till (NT) could negatively affect soil physical properties and crop performance, due to the additive effects of reduced soil cover and cattle trampling due to livestock grazing, and the absence of tillage. We evaluated the effects of four grazing strategies and of a shallow tillage (ST) on soil physical properties and corn (Zea mays L.) performance for a mollisol after 15 years under crop-livestock systems under NT in Argentina. Grazing strategies evaluated were: closure (C), one grazing (OG), high stocking rate (HR) and farmer's management (FM), and the tillage systems were: NT and ST. Bulk density (BD), penetration resistance (PR), hydraulic conductivity (ks), plant population, surface root distribution, aboveground dry matter accumulation, aboveground total N (TN) accumulation and corn yield were evaluated. High stocking rate and FM increased RP. On the other hand, ST decreased PR and BD and increased ks. Corn yield was higher under ST than under NT, and under HR than under the other grazing strategies. Total N accumulation was higher under HR than under the rest of grazing strategies. Rational grazing management and use of tillage systems on resilient soils could have prevented soil physical properties be affected beyond critical thresholds.Facultad de Ciencias Agrarias y Forestale

Response of two Citrullus amarus accessions to isolates of three species of Meloidogyne and their graft compatibility with watermelon

[EN] The response of two Citrullus amarus accessions, BGV0005164 and BGV0005167, was assessed against different Meloidogyne arenaria, Meloidogyne incognita, and Meloidogyne javanica isolates in pot experiments and against M. incognita in plastic greenhouse. In the pot experiments, plants were inoculated with a second-stage juvenile per cm(3) of sterile sand and maintained in a growth chamber at 25 degrees C for 50 days. The watermelon cv. Sugar Baby was included as a susceptible control for comparison. At the end of the experiments, the number of egg masses and eggs per plant was determined, and the reproduction index was calculated as the percentage of the number of eggs produced in the C. amarus accessions with regard to that produced in the susceptible cv. Sugar Baby. In the plastic greenhouse experiment, the ungrafted watermelon cv. Sugar Baby and watermelons grafted onto each of the C. amarus accessions and onto the watermelon rootstock cv. Robusta were cultivated from May to August 2016 in plots with nematode densities from 46 to 1392 J2 per 250 cm(3) of soil at transplantation. At the end of the experiment, the galling index and the number of eggs per plant were determined, and the reproduction index was calculated. Additionally, the compatibility of the two accessions with the watermelon cv. Sugar Baby and the effect on fruit quality (weight, size, shape, firmness, pH, total soluble solids, and flesh color) were assessed under a hydroponic system in a greenhouse. The commercial rootstocks cv. Cobalt and cv. Robusta were also included. All the Meloidogyne isolates produced less egg masses and eggs per plant on the accessions than on Sugar Baby. Both accessions performed as resistant against M. arenaria, and from highly to moderately resistant to M. incognita and M. javanica in pot experiments. In the plastic greenhouse experiment, both C. amarus accessions performed as resistant to M. incognita. Both C. amarus accessions were compatible with the watermelon cv. Sugar Baby, but only the BGV0005167 accession did not influence the fruit quality. Then, the BGV0005167 accession is a promising rootstock for managing the three tropical root-knot nematode species without influencing watermelon fruit quality.The authors thank MINECO and FEDER for funding projects AGL2013-49040-C2-1-R, AGL2014-53398-C2-2-R-AR, AGL2017-89785-R, and AGL2017-85563-C2-1-R-AR. H. A. Garcia-Mendivil acknowledges CONACYT for suport through a pre-doctoral grant.Garcia-Mendivil, HA.; Munera, M.; Giné, A.; Escudero, N.; Picó Sirvent, MB.; Gisbert Domenech, MC.; Sorribas, FJ. (2019). Response of two Citrullus amarus accessions to isolates of three species of Meloidogyne and their graft compatibility with watermelon. Crop Protection. 119:208-213. https://doi.org/10.1016/j.cropro.2019.02.005S20821311

COVID-19 y fisiopatología de la diabetes

La COVID-19, causada por la infección con el coronavirus SARS-CoV-2, es la pandemia actual sobre la que conocemos poco desde el punto de vista biológico y patológico, y cuyo pronóstico es ensombrecido por la presencia concomitante de diabetes mellitus (DM). Motivados por esto, realizamos una búsqueda bibliográfica para analizar la información disponible acerca de la fisiopatología de esta enfermedad en personas con DM. Encontramos que las personas con DM presentan alteraciones en la quimiotaxis de neutrófilos, la producción de citocinas proinflamatorias, la fagocitosis y la activación de linfocitos T, que en conjunto disminuyen la capacidad de respuesta contra cualquier patógeno, incluido el SARS-CoV-2. A ello se suma que los productos avanzados de glicosilación alteran la afinidad y la capacidad opsonizante de los anticuerpos. En cuanto al grupo de virus con tropismo por vías respiratorias, la hiperglucemia favorece su proliferación a nivel tisular. El virus SARS-CoV-2 entra a las células gracias a la proteína S (Spike), que se utiliza como receptor de la enzima convertidora de angiotensina tipo 2 (ECA-2), una glucoproteína transmembrana que se expresa no solo en el epitelio respiratorio, sino también en el miocardio y los islotes pancreáticos. La hiperglucemia aumenta la expresión de ECA-2 en la membrana celular, lo que potencializa el riesgo de infección en el caso en que la célula entre en contacto con el virus. Además, las células de personas con DM expresan niveles aumentados de la proteasa furina, que cliva la proteína S y permite el ingreso del virus a las células. Esto facilita la diseminación de la infección y el cuadro más grave que se observa en la clínica. Existe también evidencia de expresión aumentada de ECA-2 en personas con diabetes mellitus que reciben tratamiento con inhibidores de la enzima convertidora de la angiotensina o antagonistas del receptor tipo 1 de angiotensina II. Así, en el paciente con DM, se conjugan una mayor predisposición al contagio con una inmunidad humoral y celular desregulada en una combinación destructiva que desemboca en una COVID-19 más grave y letal