Dos biomarcadores de la plasticidad de la expresión génica en corales Pocillopora del arrecife Carrizales, Pacífico Tropical Mexicano

Background. Gene expression (GE) plasticity is an acclimation response that allows organisms to adjust rapidly to environmental changes, providing an adaptive advantage. GE biomarkers are emerging as a valua-ble tool for linking the organism’s physiological plasticitywith the synergetic effects of large-scale climatic conditions and local impacts such as temperature and nutrients. Objectives. In this study, we investigate the GE plasticity of the 70-kDa heat shock protein (hsp70) and the carbonic anhydrase enzyme (CA) to confirm the ability of those two genes as biomarkers of the Cellular Stress Response and Cellular Homeostasis Res-ponse, respectively. Methods. Using qPCR, we evaluate the GE plasticity of coral colonies from Pocillopora capitata, Pocillopora damicornis,and Pocillopora verrucosa at the Carrizales reef (Colima coast of Mexico) naturally exposed to environmental changes in the Sea Surface Temperature (SST), productivity and nutrients using the cellular density of Symbiodiniaceae and chlorophyll content as health indices. Results. Our results clearly show GE plasticity in the hsp70 for Pocillopora verrucosa and Pocillopora damicornis related to a daily environmental change in temperature and nutrients. On the other hand, the CA gene expression shows no change in response to daily variations. However, there was a significantly high expression of CA and a lower expression of hsp70 in Pocillopora capitata. Furthermore, we found no significant differences in the health in-dices, suggesting some degree of physiological plasticity in Pocillopora corals like its extensive morphological plasticity that could reflect different adaptation capacities to low temperatures and high nutrients during the spring season in the central Mexican Pacific. Conclusions. Evaluating the phenotypic plasticity (morphology and molecular physiology) could help identify coral colonies with a more significant potential to survive en-vironmental stressors. The latter is an essential consideration for managing, conserving, and restoring coral reefs in the Mexican Pacific.Antecedentes. La plasticidad de la expresión génica (GE) es una respuesta inmediata de aclimatación al cambio ambiental que puede proporcionar una ventaja adaptativa. Los biomarcadores de GE están emer-giendo como una herramienta valiosa para vincular la plasticidad fisiológica del organismo con los efectos sinérgicos del cambio climático y el impacto local como la temperatura y nutrientes. Objetivos. Investigamos la plasticidad de la expresión de genes que codifican para la proteína de choque térmico de 70-kDa (hsp70) y la enzima anhidrasa carbónica (CA) para confirmar su utilidad como biomarcadores de la respuesta de estrés y de homeostasis celular, respectivamente. Métodos. Evaluamos la GE mediante qPCR en colonias de corales Pocilloporacapitata, Pocillopora damicornis y Pocillopora verrucosa del arrecife Carrizales (Colima, México) expuestas a un cambio natural en la temperatura de la superficie del mar (SST), productividad pri-maria y nutrientes utilizando la densidad de Symbiodiniaceae y el contenido de clorofila como indicadores de salud. Resultados. La plasticidad de la GE de hsp70 en Pocillopora damicornis y Pocillopora verrucosa se asocia con la variación diaria de temperatura y nutrientes, mientras que el gen de la CA no muestra cambios de expresión relacionada con esta variabilidad. Sin embargo, en Pocillopora capitata se encontró una expresión significativamente mayor de CA y una menor expresión de hsp70. Estos resultados reflejan un grado de plasticidad fisiológica en corales Pocillopora similar a la extensa plasticidad morfológica dentro de este género, lo que podría sugerir diferentes capacidades de adaptación a la temporada primave-ral de bajas temperaturas y alto contenido de nutrientes en la región. Conclusiones. Evaluar la plasticidad fenotípica (morfología y fisiolo-gía molecular) podría ser útil para identificar colonias de corales con un mayor potencial de sobrevivencia al estrés ambiental. Lo anterior resulta relevante para la conservación, manejo y restauración de los arrecifes de coral del Pacífico mexicano.   &nbsp

Somatic growth effects of intramuscular injection of growth hormone in androgen-treated juvenile Nile tilapia, Oreochromis niloticus (Perciformes: Cichlidae)

Little is known about the effects of the interaction of growth hormone (GH) with 17 a-methyltestosterone (17-MT) during fish growth. We evaluated this in the present study to assess the effect on fish growth. Fish in two batches of juvenile tilapia (Oreochromis niloticus) (approximately 5.0cm in length) were randomly assigned in triplicate to three treatments and a control group, distributed among 12 fiberglass tanks of 1 000L capacity (50 fish per tank) in an experiment covering a period of six weeks. The experimental groups were: a) fish treated with 17-MT and GH in mineral oil (RGH); b) fish treated with 17-MT and mineral oil without the addition of GH (R); c) fish treated with GH in mineral oil but not 17-MT (NGH); and d) fish of the control group, which were treated with mineral oil but not 17-MT or GH (N). The GH was injected into the fish at a rate of 0.625mg/g body weight. Morphometric data were recorded at the beginning of the experiment (T) and at 15, 30 and 45 days (T, T and T), and various indicators of growth were assessed: condition factor (K); survival percentage (S), feed conversion rate (FCR), percentage weight gain (WG) and (v) daily weight gain. The optimum dietary level was calculated assuming 5% food conversion to total weight in each group. During the experiment, the fish were provided with a commercial food containing 45% protein. The data showed that GH injection resulted in a greater weight gain in fish treated with 17-MT (the RGH treatment group), being particularly significant increase in weight during T and T (pActualmente, durante el crecimiento de los peces existe poco conocimiento sobre los efectos de la interacción de la hormona del crecimiento (HC) con 17 &#945;-metiltestosterona (17-MT). En el presente estudio los peces en dos lotes de tilapia (Oreochromis niloticus) (5.0cm de longitud), fueron asignados al azar por triplicado a tres tratamientos y un grupo control, distribuidos en 12 tanques de fibra de vidrio de 1 000 litros (50 peces por tanque), en un período de seis semanas. Los tratamientos fueron: a) peces tratados con 17-MT+HC en aceite mineral (RGH), b) peces tratados con 17-MT+aceite mineral sin la adición de HC (R), c) los peces que no fueron tratados con 17-MT-tratado+HC en aceite mineral (NGH), y d) los peces que no fueron tratados con 17-MT+aceite mineral (N). La hormona de crecimiento humano recombinante (Humatrope, Eli Lilly & Co., Windlesham, Inglaterra), se inyectó en el pez con una dosis de 0.625mg por gramo de peso corporal. Los datos morfométricos se registraron al comienzo del experimento (T) y en los días 15, 30 y 45 (T, T y T), Se registraron diversos indicadores de crecimiento: factor de condición (K), porcentaje de supervivencia (S), la tasa de conversión alimenticia (FCR), porcentaje de ganancia de peso (GP) y el aumento de peso al día. El nivel óptimo dietético fue calculado suponiendo 5% de conversión de alimentos al peso total de cada grupo. Durante el experimento fue usada una dieta comercial con el 45% de proteína. De los resultados presentados, es evidente que la inyección de HC dio lugar a una mayor ganancia de peso en el 17-MT-los peces tratados (el grupo de tratamiento RGH), y la diferencia fue significativa, tanto en T y T (p<0.05) para ambas comparaciones. De manera similar, los altos valores de K se presentaron en los tratamientos R y RGH durante los primeros días de cultivo. Esto puede haber sido asociado con un mejor estado nutricional que afectó tanto el desarrollo de peso y la longitud del cuerpo del pez, como resultado del efecto aditivo de 17-MT y GH. Los tratamientos no andrógenos y los grupos tratados con andrógenos y con HC mostraron un mayor incremento en la ganancia de peso por día, los mayores valores de K y menores tasas de conversión del alimento, lo que sugiere una mayor eficiencia de la alimentación en los peces tratados con hormonas. Peces en el tratamiento RGH mostraron el mayor crecimiento, lo que sugiere una posible interacción entre el 17 de &#945;-metiltestosterona (17-MT) y hormona de crecimiento inyectada

Factores asociados a la respuesta de Pocillopora spp. (Anthozoa: Scleractinia) durante un proceso de restauración en la costa del Pacífico mexicano

During a restoration process of Pocillopora spp., using opportunity corals (CO) several biotic attributes were assessed at two sites bi-monthly over a year and concentrations of mycosporin type amino acids (MAAs) and levels of chlorophyll a (Chl a) were determined. Specifically, in the last sampling analysis it was performed an analysis of malonaldehyde (MDA) and the RNA/DNA and protein/DNA relationships were calculated, as an index of oxidative stress and transcriptional activity in symbiont and coral tissue of all morphotypes. At Carrizales site (SC) the coral clusters (RC) used as a method of restoration, promoted the integration of CO showing signs of recovery and high survival rates (90%); however, in Juluapan site (SJ), a lack of response to biotic and molecular indicators associated with recovery was observed. Therefore, CO from Carrizales were not able to acclimate to a place where different conditions prevail. High concentrations of Chl a, AAMs and a high RNA/DNA ratio were characteristic of a healthy condition of coral which in turn, were associated with higher specimen’s survival and restoration.Durante un proceso de restauración de Pocillopora spp., usando corales de oportunidad (CO), fueron evaluados diversos atributos bióticos en dos sitios a lo largo de un año, de manera bimensual fueron determinadas las concentraciones de aminoácidos tipo micosporina (AAMs) y niveles de clorofila a (Cl a). De manera específica, en el último muestreo se realizó un análisis de malonaldehido (MDA) y se calcularon las relaciones ARN/ADN y proteína/ADN como indicadores de estrés oxidativo y actividad trascripcional en simbionte y cnidario de todos los morfotipos. En sitio Carrizales (SC) la técnica de restauración de ramilletes coralinos (RC) promovió la integración de COs registrando signos de recuperación y altas tasas de supervivencia (90%); no obstante, en el Sitio Juluapan (SJ), se observó una falta de respuesta a los indicadores bióticos y moleculares asociados a la recuperación. Por lo tanto, los CO provenientes de Carrizales no fueron capaces de aclimatarse a un sitio en el que imperan distintas condiciones ambientales. Altas concentraciones de Cl a, AAMs, y una alta relación ARN/ADN fueron características de una condición saludable de corales, que a su vez, estuvieron asociados a los indicadores de restauración y mejor supervivencia observada

Factores asociados a la respuesta de Pocillopora spp. (Anthozoa: Scleractinia) durante un proceso de restauración en la costa del Pacífico mexicano

During a restoration process of Pocillopora spp., using opportunity corals (CO) several biotic attributes were assessed at two sites bi-monthly over a year and concentrations of mycosporin type amino acids (MAAs) and levels of chlorophyll a (Chl a) were determined. Specifically, in the last sampling analysis it was performed an analysis of malonaldehyde (MDA) and the RNA/DNA and protein/DNA relationships were calculated, as an index of oxidative stress and transcriptional activity in symbiont and coral tissue of all morphotypes. At Carrizales site (SC) the coral clusters (RC) used as a method of restoration, promoted the integration of CO showing signs of recovery and high survival rates (90%); however, in Juluapan site (SJ), a lack of response to biotic and molecular indicators associated with recovery was observed. Therefore, CO from Carrizales were not able to acclimate to a place where different conditions prevail. High concentrations of Chl a, AAMs and a high RNA/DNA ratio were characteristic of a healthy condition of coral which in turn, were associated with higher specimen's survival and restoration.Durante un proceso de restauración de Pocillopora spp., usando corales de oportunidad (CO), fueron evaluados diversos atributos bióticos en dos sitios a lo largo de un año, de manera bimensual fueron determinadas las concentraciones de aminoácidos tipo micosporina (AAMs) y niveles de clorofila a (Cl a). De manera específica, en el último muestreo se realizó un análisis de malonaldehido (MDA) y se calcularon las relaciones ARN/ADN y proteína/ADN como indicadores de estrés oxidativo y actividad trascripcional en simbionte y cnidario de todos los morfotipos. En sitio Carrizales (SC) la técnica de restauración de ramilletes coralinos (RC) promovió la integración de COs registrando signos de recuperación y altas tasas de supervivencia (90%); no obstante, en el Sitio Juluapan (SJ), se observó una falta de respuesta a los indicadores bióticos y moleculares asociados a la recuperación. Por lo tanto, los CO provenientes de Carrizales no fueron capaces de aclimatarse a un sitio en el que imperan distintas condiciones ambientales. Altas concentraciones de Cl a, AAMs, y una alta relación ARN/ADN fueron características de una condición saludable de corales, que a su vez, estuvieron asociados a los indicadores de restauración y mejor supervivencia observada

Somatic growth effects of intramuscular injection of growth hormone in androgen-treated juvenile Nile tilapia, Oreochromis niloticus (Perciformes: Cichlidae)

Little is known about the effects of the interaction of growth hormone (GH) with 17 a-methyltestosterone (17-MT) during fish growth. We evaluated this in the present study to assess the effect on fish growth. Fish in two batches of juvenile tilapia (Oreochromis niloticus) (approximately 5.0cm in length) were randomly assigned in triplicate to three treatments and a control group, distributed among 12 fiberglass tanks of 1 000L capacity (50 fish per tank) in an experiment covering a period of six weeks. The experimental groups were: a) fish treated with 17-MT and GH in mineral oil (RGH); b) fish treated with 17-MT and mineral oil without the addition of GH (R); c) fish treated with GH in mineral oil but not 17-MT (NGH); and d) fish of the control group, which were treated with mineral oil but not 17-MT or GH (N). The GH was injected into the fish at a rate of 0.625mg/g body weight. Morphometric data were recorded at the beginning of the experiment (T) and at 15, 30 and 45 days (T, T and T), and various indicators of growth were assessed: condition factor (K); survival percentage (S), feed conversion rate (FCR), percentage weight gain (WG) and (v) daily weight gain. The optimum dietary level was calculated assuming 5% food conversion to total weight in each group. During the experiment, the fish were provided with a commercial food containing 45% protein. The data showed that GH injection resulted in a greater weight gain in fish treated with 17-MT (the RGH treatment group), being particularly significant increase in weight during T and T (p<0.05). High values of K were found in the R and RGH treatments during the initial days of the experiment, which may have been a consequence of the better nutritional status affecting both weight gain and growth in body length, as a result of the additive effects of 17-MT and GH. The fish in groups not treated with 17-MT and treated with 17-MT and added GH showed greater increases in WG per day, higher K values and lower FCRs than fish in the other groups, which suggests that greater feed efficiency occurred in the hormone-treated fish. Fish in the RGH treatment showed the most growth, suggesting a possible interaction between 17-MT and injected GH

Response to pH stress in the reef-building coral Pocillopora capitata (Anthozoa: Scleractinia)

To evaluate the metabolic response of the symbiotic coral Pocillopora capitata to reduced seawater pH in an in vitro system, 112 branches of P. capitata with no apparent damage from bleaching were collected from the La Boquita (LB) coral community. Two pH treatments were evaluated: a) pH 7.85/7.95 (Treatment C1), b) 7.60/7.70 (Treatment C2), and 8.00/8.40 pH control treatment (CC). The coral branches were randomly assigned to experimental units (n= 38 per treatment). Samples were taken at 2 separate times for biochemical analysis and qualitative assessment of microstructural aspects with scanning electron microscopy: initial time, sample taken at 12 h (T1); end time, samples from the final day of exposure (Tf, day 7 of the experiment). Unlike the symbiont tissue, the biochemical analysis of the host tissue revealed that P. capitata displayed an immediate response as reflected in the RNA/DNA and protein/DNA ratios as well as in the concentrations of RNA and protein, particularly in the initial hours of the experiment in treatment C2. Qualitative microstructural analysis primarily identified effects in treatment C2 which was influenced by the presence of micro surface detachments in the terminal regions of the skeletal fibers.Para evaluar la respuesta metabólica del coral simbiótico Pocillopora capitata a la reducción del pH del agua de mar en un sistema in vitro, 112 ramas de P. capitata se obtuvieron de la comunidad de corales La Boquita (LB) sin exhibir algún daño aparente de blanqueamiento. Se evaluaron 2 tratamientos de pH: a) 7,85/7,95 pH (Tratamiento C1), b) 7,60/7,70 (Tratamiento C2 ) y 8,00/8,40 pH tratamiento de control (CC). Las ramas de coral fueron asignadas aleatoriamente a unidades experimentales (n= 38 por tratamiento). Las muestras fueron tomadas en 2 tiempos para el análisis bioquímico y para evaluar cualitativamente los aspectos microestructurales por microscopía electrónica de barrido: tiempo inicial, muestra tomada en 12 h (T1); tiempo final, muestras del último día de la exposición (Tf, día 7 del experimento). A diferencia del tejido simbionte, el análisis bioquímico del tejido del coral reveló que P. capitata muestra una respuesta inmediata reflejada en los coeficientes de ARN/ADN y proteína/ADN, así como en las concentraciones de ARN y proteína, particularmente en el tratamiento de C2 en las horas iniciales del experimento. El análisis microestructural cualitativo identificó principalmente efectos en el tratamiento C2, que fue influenciado por la presencia de disgregaciones micro-superficiales en las regiones terminales de las fibras esqueléticas

Gene expression plasticity in Pocillopora corals from 2 locations on the Carrizales Reef, Pacific coast of Mexico

The greatest threat scleractinian corals face today is accelerated climate change. Assuming that most scleractinians are incapable of genetic adaptation to rapid global changes, the alternative response would be phenotypic plasticity, which is classically described as acclimatization. With the purpose of establishing a baseline for the study of acclimatization in corals of the Pacific coast of Mexico, we assessed the molecular and physiological response of 36 colonies of 3 Pocillopora morphospecies (Pocillopora cf. capitata, Pocillopora cf. damicornis, and Pocillopora cf. verrucosa) located at 2 sites (east and west) on Carrizales Reef. Our results show higher incidence of light and chlorophyll concentrations in seawater samples from the west side, suggesting the presence of at least 2 microenvironments with more and less light in the reef. In response, coral morphospecies from the west side showed higher gene expression and significant differences in pigment concentrations, endosymbiont densities, and metabolic markers (RNA, DNA, and proteins). Given the present concern about the future of coral reefs, we consider that the present study could be used as a baseline for the study of the physiological and molecular plasticity of Pocillopora corals in Mexican waters, so conservation strategies could be developed for key morphospecies in coral reefs on the Pacific coast of Mexico