[Nuevo artículo] Kisspeptin and GnRH interactions in the reproductive brain of teleosts

Mechaly Kisspeptin

Nuevo Artículo de investigación:
Kisspeptin and GnRH interactions in the reproductive brain of teleosts

Gustavo M. Somoza, Alejandro S. Mechaly, Vance L. Trudeau

Highlights
In teleost fish hypophysiotropic Gnrh neurons do not express Kisspeptin receptors
gnrh mutants and those with triple gnrh3/2 kiss mutations can reproduce.
In these fish, a compensatory response appears to maintain reproduction.
Kiss, Gnrh and other neuropeptides interact to regulate fish reproduction.
Abstract:

It is well known that gonadotropin-releasing hormone (Gnrh) has a key role in reproduction by regulating the synthesis and release of gonadotropins from the anterior pituitary gland of all vertebrates. About 25 years ago, another neuropeptide, kisspeptin (Kiss1) was discovered as a metastasis suppressor of melanoma cell lines and then found to be essential for mammalian reproduction as a stimulator of hypothalamic Gnrh and regulator of puberty onset. Soon after, a kisspeptin receptor (kissr) was found in the teleost brain. Nowadays, it is known that in most teleosts the kisspeptin system is composed of two ligands, kiss1 and kiss2, and two receptors, kiss2r and kiss3r. Even though both kisspeptin peptides, Kiss1 and Kiss2, have been demonstrated to stimulate gonadotropin synthesis and secretion in different fish species, their actions appear not to be mediated by Gnrh neurons as in mammalian models. In zebrafish and medaka, at least, hypophysiotropic Gnrh neurons do not express Kiss receptors. Furthermore, kisspeptinergic nerve terminals reach luteinizing hormone cells in some fish species, suggesting a direct pituitary action. Recent studies in zebrafish and medaka with targeted mutations of kiss and/or kissr genes reproduce relatively normally. In zebrafish, single gnrh mutants and additionally those having the triple gnrh3 plus 2 kiss mutations can reproduce reasonably well. In these fish, other neuropeptides known to affect gonadotropin secretion were up regulated, suggesting that they may be involved in compensatory responses to maintain reproductive processes. In this context, the present review explores and presents different possibilities of interactions between Kiss, Gnrh and other neuropeptides known to affect reproduction in teleost fish. Our intention is to stimulate a broad discussion on the relative roles of kisspeptin and Gnrh in the control of teleost reproduction.

 

Palabras clave

Gonadotropin-releasing hormone (Gnrh)
Kisspeptin (Kiss)
Brain
Pituitary
Reproduction
teleost
Fish

https://doi.org/10.1016/j.ygcen.2020.113568

[Nuevo artículo] Contribución de hongos micorrícicos nativos a la nutrición fosforada

Ciencia del Suelo

Nuevo artículo: Ciencia del Suelo. Vol. 38 Nro Julio

Contribución de hongos micorrícicos nativos a la nutrición fosforada y su impacto en la partición de fotoasimilados de soja

Valeria S. Faggioli, Cabello Marta, Melchiorre N Mariana & , Fernanda Covacevich

Resumen:

Estrategias de asociaciones entre plantas con hongos micorrícicos arbusculares (HMA) podrían ser utilizadas para garantizar una eficiente nutrición de fósforo (P). Sin embargo, se desconoce si prácticas usuales de largo plazo destinadas a la producción de soja en nuestro país, han deprimido el potencial de colonización y de pro- moción de crecimiento vegetal por las comunidades de HMA nativos. Nuestro objetivo fue cuantificar el aporte en crecimiento, absorción de P y partición de fotoasimilados en soja aportados por HMA nativos de monocultivo de soja de larga duración ante oferta diferencial de P. Se instaló un ensayo en invernáculo durante 60 días con 4 tratamientos (con “+“ y sin “-“ HMA nativos de un monocultivo de soja de larga duración instalado en Córdoba; con “+“ y sin “–“ fertilización con P por aplicación semanal de 15,5 mgP maceta-1). Los HMA nativos coloniza- ron las raíces de soja y favorecieron su crecimiento aun cuando la oferta de P no fue limitante. La colonización micorrícica intra y extra-radical, así como la oferta de P, favorecieron el crecimiento, la acumulación de P y el contenido y la partición de azúcares en las plantas de soja. Las plantas crecidas en presencia de micorrizas (+HMA) sin oferta de P (-P) mostraron mayor acumulación de materia seca y P. Aunque no se evidenció incre- mento significativo en la absorción de P por las micorrizas, las plantas en la condición +HMA y +P mostraron respuesta positiva a la micorrización en el crecimiento aéreo. Las plantas que crecieron ante +P y -HMA no fueron las de mayor crecimiento. Esto resalta la importancia de favorecer prácticas de manejo que, combinadas con la fertilización moderada destinada a la reposición de nutrientes, favorezca el mantenimiento de poblaciones de HMA nativas que pueden contribuir a un uso más eficiente de la fertilidad del suelo y favorecer el crecimiento del cultivo de soja.

Palabras clave:
Simbiosis micorrícica
Carbohidratos
Colonización
Fósforo

[Nuevo artículo] Soil survey reveals a positive relationship between aggregate stability and anaerobically mineralizable nitrogen

Nuevo artículo de investigación:

Ecological Indicators. Vol. 117, October 2020, 106640

Soil survey reveals a positive relationship between aggregate stability and anaerobically mineralizable nitrogen

Gisela V. García, Nicolás Wyngaard, Nahuel I. Reussi Calvo, Silvina San Martino, Fernanda Covacevich, Guillermo A. Studdert

Highlights
• Anaerobically mineralizable N (AN) was proposed as Mollisols health indicator (SHI).
• AN is positively related to total (SOC) and particulate (POC) organic carbon.
• Regardless of soil texture, AN does positively relate to aggregate stability.
• AN is proven to be an adequate and sensitive SHI for loam textured Mollisols.
Abstract:
Soil health status should be monitored to allow planning sustainable management, but indicators available do not encourage frequent soil health evaluation because of the complexity, time-consumption, and expensiveness of the methodologies. Aggregate stability (AS) is a good soil physical health indicator associated with soil (SOC) and particulate (POC) organic carbon but is difficult to monitor. Anaerobically mineralizable nitrogen (AN) has been proposed as soil health indicator because is cheap, simple, and safe to measure, is sensitive to soil-use changes, is also related to soil (SOC) and particulate (POC) organic carbon, and is frequently determined by farmers in Mollisols of the Southeastern Argentinean Pampas to support soil fertility diagnosis. We hypothesize that AN is positively related to and can be used as indicator of AS. Soil samples were taken at 0–5 and 5–20 cm depths from 46 sites throughout the southeastern Buenos Aires province, Argentinean Pampas. In each site, we sampled Mollisols under continuous cropping (CC) and others that had not been disturbed for many years (pseudo-pristine, PRIS). We determined texture, SOC, mineral-associated organic C, POC, AS and AN. We also calculated variable values for 0–20 cm. Soil organic carbon, POC, AN and AS were reduced by continuous cropping. Anaerobically mineralizable N was positively related to SOC (R2 = 0.74, 0.46, and 0.62 at 0–5, 5–20, and 0–20 cm) and POC (R2 = 0.73, 0.33, and 0.60, respectively). An important proportion of the total variability in AS was explained by SOC (R2 = 0.77, 0.65, and 0.73 at 0–5, 5–20, and 0–20 cm, respectively), POC (R2 = 0.75, 0.63, and 0.73, respectively), and AN (R2 = 0.78, 0.69, and 0.81, respectively). The AS increased with the increase of SOC, POC, and AN at all three depths, with slopes that did not differ between CC and PRIS, but with intercepts that differed. Neither sand nor clay contents significantly contributed to explain the variations in AS as a function of SOC, POC, and AN. An independent validation of the regression model relating AS and AN at 0–20 cm was done and the output was very good (RPIQ (ratio of performance to interquartile distance) = 2.20). Results support our hypothesis because AN was positively related to AS. Consequently, AN would be a good indicator of AS, SOC, and POC. Based on our results, we consider that a simple and cheap soil analysis as AN can not only be used to diagnose soil fertility, but to monitor soil physical and biochemical health status.

Palabras clave

Soil health indicator
Total organic carbon
Particulate organic carbon

https://doi.org/10.1016/j.ecolind.2020.106640

Defensa de Tesis Doctoral Lic. Rocío de la Paz López

Tesis doctoral Lopez

Rocío de la Paz López defenderá su trabajo de Tesis para optar al título de Doctora en Ciencias Biológicas, titulado: «Desarrollo de sistemas de control biológico para el manejo integrado de mosquitos vectores»

Autor: Lic. Rocío de la Paz Lopez

Director: Dra. Corina Berón

Jurados:

Dr. Luis Adrían Díaz
Dr. Marcelo Facundo Berretta
Dra. Liesel Brenda Gende

Martes 30 de junio 17 hs
Aula virtual – FCEyN – UNMdP
Pueden seguir la transmisión desde: https://youtu.be/Hblin9If2uw

Defensa de Tesis Doctoral Lic. Camila D. Coronel

Lic. Camila D Coronel

El próximo jueves 25 de junio la Lic. en Biotecnología Camila Denise Coronel defenderá su tesis doctoral titulada: «Biotecnología algal: simulación de productividad de biomasa y vectores de energía en fotobiorreactores ambientales» realizada bajo la dirección del Dr. Leonardo Curatti.

Jueves 25 de junio, 17 hs.

Información para acceder a la transmisión en directo en la entrada completa.