Influence of cortisol on the attachment and metamorphosis of larval Utterbackia imbecillis on bluegill sunfish (Lepomis macrochirus)

The larvae of unionid freshwater mussels (i.e., glochidia) undergo a parasitic stage requiring their attachment to the external epithelia of fish hosts, where they metamorphose into free-living juveniles. We describe the physiological effects in bluegill sunfish (Lepomis macrochirus) of infection with glochidia from the paper pondshell (Utterbackia imbecillis). Glochidia accumulation on bluegill increased dramatically at concentrations of 2000 glochidia liter-1 and above, reaching a maximum attachment density of about 30 glochidia g-1 fish at 4000 glochidia liter-1. Plasma cortisol was the most sensitive indicator of biological effect to glochidial exposure, increasing significantly in hosts exposed to 2000 glochidia liter-1 or greater. Glochidia were 31% more likely to undergo successful juvenile metamorphosis when attached to bluegill with elevated plasma cortisol, largely due to the enhanced survivorship of these larvae during the first 48 h after infection. We tested the hypothesis that glochidial attachment and juvenile metamorphosis were stimulated directly by plasma cortisol in fish hosts. Bluegill were given an intraperitoneal injection of cortisol, then infected with 1000 glochidia liter-1 at 48 h after hormone supplementation. Cortisol-injected fish had a 42% increase in the number of attached glochidia g-1 fish and a 28% increase in larval metamorphosis compared to sham-injected and control fish. We provide evidence that cortisol enhances glochidial metamorphosis on hosts by improving the retention of attached glochidia. This study gives insights into the influence of host physiology on glochidial attachment and juvenile mussel transformation. © 2011 Marine Biological Laborat006Fry

Reciprocal osmotic challenges reveal mechanisms of divergence in phenotypic plasticity in the killifish Fundulus heteroclitus

© 2015. Published by The Company of Biologists Ltd. The killifish Fundulus heteroclitus is an estuarine species with broad physiological plasticity, enabling acclimation to diverse stressors. Previous work suggests that freshwater populations expanded their physiology to accommodate low salinity environments; however, it is unknown whether this compromises their tolerance to high salinity.We used a comparative approach to investigate the mechanisms of a derived freshwater phenotype and the fate of an ancestral euryhaline phenotype after invasion of a freshwater environment. We compared physiological and transcriptomic responses to high-and low-salinity stress in fresh and brackish water populations and found an enhanced plasticity to low salinity in the freshwater population coupled with a reduced ability to acclimate to high salinity. Transcriptomic data identified genes with a conserved common response, a conserved salinity-dependent response and responses associated with population divergence. Conserved common acclimation responses revealed stress responses and alterations in cell-cycle regulation as important mechanisms in the general osmotic response. Salinityspecific responses included the regulation of genes involved in ion transport, intracellular calcium, energetic processes and cellular remodeling. Genes diverged between populations were primarily those showing salinity-specific expression and included those regulating polyamine homeostasis and the cell cycle. Additionally, when populations were matched with their native salinity, expression patterns were consistent with the concept of \u27transcriptomic resilience\u27, suggesting local adaptation. These findings provide insight into the fate of a plastic phenotype after a shift in environmental salinity and help to reveal mechanisms allowing for euryhalinity

Seawater acclimation causes independent alterations in Na \u3csup\u3e+\u3c/sup\u3e/TK\u3csup\u3e+\u3c/sup\u3e- And H\u3csup\u3e+\u3c/sup\u3e-ATPase activity in isolated mitochondria-rich cell subtypes of the rainbow trout gill

Mitochondria-rich cells (MR cells) of the gills of rainbow trout undergo changes in relative distribution and biochemical function during acclimation to partial-strength (10‰) and full-strength (30‰) seawater. In isolated total gill cells, Na+/K+-ATPase activity increased fivefold and H+-ATPase activity decreased fourfold when trout were acclimated to either 10‰ or 30‰ seawater. When total MR gill cells were separated based on differential binding to peanut lectin agglutinin (PNA), the PNA subtypes underwent a change in relative distribution in seawater-acclimated fish. In freshwater, the ratio of PNA-: PNA+ was 65:35 while in seawater the distribution changed to 20:80 PNA-:PNA+. Additionally, differential changes in Na +/K+-ATPase and H+-ATPase activity in each of the independent cell types occurred during seawater acclimation; Na +/K+-ATPase activity in the PNA- cells increased by 197% while in PNA+ cells Na+TK +-ATPase decreased by 57%. However, H+-ATPase activity was decreased in both PNA- (84%) and PNA+ (72%) subtypes during acclimation to seawater

Salinity- and population-dependent genome regulatory response during osmotic acclimation in the killifish (Fundulus heteroclitus) gill

The killifish Fundulus heteroclitus is abundant in osmotically dynamic estuaries and it can quickly adjust to extremes in environmental salinity. We performed a comparative osmotic challenge experiment to track the transcriptomic and physiological responses to two salinities throughout a time course of acclimation, and to explore the genome regulatory mechanisms that enable extreme osmotic acclimation. One southern and one northern coastal population, known to differ in their tolerance to hypo-osmotic exposure, were used as our comparative model. Both populations could maintain osmotic homeostasis when transferred from 32 to 0.4 p.p.t., but diverged in their compensatory abilities when challenged down to 0.1 p.p.t., in parallel with divergent transformation of gill morphology. Genes involved in cell volume regulation, nucleosome maintenance, ion transport, energetics, mitochondrion function, transcriptional regulation and apoptosis showed population- and salinity-dependent patterns of expression during acclimation. Network analysis confirmed the role of cytokine and kinase signaling pathways in coordinating the genome regulatory response to osmotic challenge, and also posited the importance of signaling coordinated through the transcription factor HNF-4 . These genome responses support hypotheses of which regulatory mechanisms are particularly relevant for enabling extreme physiological flexibility. © 2012. Published by The Company of Biologists Ltd

The African Lungfish (\u3cem\u3eProtopterus dolloi\u3c/em\u3e): Ionoregulation and Osmoregulation in a Fish out of Water

Although urea production and metabolism in lungish have been thoroughly studied, we have little knowledge of how internal osmotic and electrolyte balance are controlled during estivation or in water. We tested the hypothesis that, compared with the body surface of teleosts, the slender African lungfish (Protopterus dolloi) body surface was relatively impermeable to water, Na+ and Cl- due to its greatly reduced gills. Accordingly, we measured the tritiated water (3H-H2O) flux in P. dolloi in water and during air exposure. In water, 3H-H2O efflux was comparable with the lowest measurements reported in freshwater teleosts, with a rate constant (K) of 17.6% body water h-1. Unidirectional ion fluxes, measured using 22Na+ and 36Cl-, indicated that Na+ and Cl- influx was more than 90% lower than values reported in most freshwater teleosts. During air exposure, a cocoon formed within 1 wk that completely covered the dorsolateral body surface. However, there were no disturbances to blood osmotic or ion (Na+, Cl-) balance, despite seven- to eightfold increases in plasma urea after 20 wk. Up to 13-fold increases in muscle urea (on a dry-weight basis) were the likely explanation for the 56% increase in muscle water content observed after 20 wk of air exposure. The possibility that muscle acted as a “water reservoir” during air exposure was supported by the 20% decline in body mass observed during subsequent reimmersion in water. This decline in body mass was equivalent to 28 mL water in a 100-g animal and was very close to the calculated net water gain (approximately 32 mL) observed during the 20-wk period of air exposure. Tritiated water and unidirectional ion fluxes on air-exposed lungfish revealed that the majority of water and ion exchange was via the ventral body surface at rates that were initially similar to aquatic rates. The 3H-H2O flux declined over time but increased upon reimmersion. We conclude that the slender lungfish body surface, including the gills, has relatively low permeability to water and ions but that the ventral surface is an important site of osmoregulation and ionoregulation. We further propose that an amphibian-like combination of ventral skin water and ion permeability, plus internal urea accumulation during air exposure, allows P. dolloi to extract water from its surroundings and to store water in the muscle when the water supply becomes limited

Necesidad de conceptos básicos para investigar en Matemática Financiera.

By means of this proposal, it present a reflection on the teaching process of Mathematical Finance, in the various programs of Social Sciences, and the way the teachers with the direction of the course, provide the necessary tools to carry out an investigation in the area detected after absence of basic concepts. The Financial Mathematics, to be regarded as a source course in the exact sciences and not as an instrument of tokenism, and give the opportunity to have their instructors are academic undergraduate and / or graduate in Mathematics.Por medio de esta propuesta, se presenta una reflexión sobre los procesos de enseñanza de Matemática Financiera, en los diversos programas de Ciencias Sociales,y la forma como los profesores que tienen la dirección del curso, brindan las herramientas necesarias para llevar a cabo una investigación en el área, luego de detectarse ausencia de conceptos básicos. La Matemática Financiera, debe ser mirada como un curso de origen en las ciencias exactas y no como un instrumento del formulismo, y dar la oportunidad a que sus instructores tengan formación académica de pregrado y/o posgrado en Matemática

Propuesta de modelo al desarrollo profesional para mejorar la efectividad laboral en docentes de una universidad, Tumbes 2023

La investigación denominada “Propuesta De Modelo Al Desarrollo Profesional Para Mejorar La Efectividad Laboral En Docentes De Una Universidad, Tumbes 2023”, tuvo como objetivo elaborar una propuesta de modelo al desarrollo profesional para mejorar la efectividad laboral en docentes de una universidad, Tumbes 2023. La investigación planteó la hipótesis que afirma que la propuesta de un modelo al desarrollo profesional mejoraría la efectividad laboral en docentes de una universidad, Tumbes 2023. La población de estudio corresponde a 210 docentes universitario en condición de nombrados de una universidad de Tumbes. Es estudio es no experimental, con un nivel propositivo, enfoque cuantitativo y de tipo básico, se desarrolló la técnica de encuesta y como instrumento el cuestionario con respuesta de escala ordinal con medición Likert. El análisis de datos fue a través de frecuencias respecto a los niveles respecto a las dimensiones y la variable efectividad laboral. Los resultados de la Tabla 2 muestra el porcentaje de participación de los docentes en función a los elementos del proceso productivo en donde se pudo evaluar que, existe un nivel medio con un porcentaje de 87,6% (184 docentes universitarios) lo cual refleja su mayor proporción en los indicadores de iniciativa, aspiraciones y participación activa del docente. La propuesta de modelo de desarrollo profesional para mejorar la efectividad laboral, su incorporación atenderá las limitaciones detectadas en la investigación, enfocadas al profesionalismo, incentivar su disciplina e iniciativa a la elaboración de productos de investigación, además de la creación de procesos investigativos, para lograr alcanzar el cumplimiento de sus funciones y la satisfacción de los indicadores de gestión para el fortalecimiento de la investigación en cada escuela profesional

Obstáculos presentes en Modelación Matemática. Caso Ecuaciones Diferenciales en la formación de Ingenieros

By professional experience, it has been observed that the activities of Mathematical Modeling of phenomena and / or engineering processes in one Differential Equations course, have detected some obstacles by the students in the teaching - learning process, which has motivated its identification, being the purpose of this paper. Initially, researches on obstacles in mathematical context, engineering process and mathematical modeling have been mentioned. To carry out the solution of this problem, a survey was conducted with all students who took the Differential Equation course in Engineering programs at the Unidad Central del Valle del Cauca, in the period 2015-2, after performing modeling practices. This Study was carried out using open type questionnaire and its consequent analysis was with a qualitative approach using the grounded theory. Subsequently, the results of carried survey are mentioned, which led to detect different types of obstacles according their origin. Finally, this research will let improve modelling process within triad: student, education and teacher.Con la Modelación Matemática se pueden describir y predecir algunos problemas asociados al medio ambiente, sistemas físicos y mejorar los procesos de ingeniería. Este análisis puede hacerse con ayuda de Ecuaciones Diferenciales mediante la observación de dichos fenómenos. Cuando se desea enseñar Modelación Matemática, a partir  de Ecuaciones Diferenciales como herramienta en la formación de ingenieros, tanto el docente como el alumno respectivos se enfrentan a algunos obstáculos tales como: Cognitivos, Epistemológicos, Didácticos, que pueden presentar dificultades en las actividades diseñadas para tal fin. Por medio de este trabajo se desea identificar algunos de estos obstáculos, mediante análisis cualitativo, usando la técnica de la Teoría Fundamentada, al hacer modelación con estudiantes de Ingeniería, adscritos a un curso de Ecuaciones Diferenciales en la Unidad Central del Valle del Cauca

Necesidad de conceptos básicos para investigar en Matemática Financiera.

By means of this proposal, it present a reflection on the teaching process of Mathematical Finance, in the various programs of Social Sciences, and the way the teachers with the direction of the course, provide the necessary tools to carry out an investigation in the area detected after absence of basic concepts. The Financial Mathematics, to be regarded as a source course in the exact sciences and not as an instrument of tokenism, and give the opportunity to have their instructors are academic undergraduate and / or graduate in Mathematics.Por medio de esta propuesta, se presenta una reflexión sobre los procesos de enseñanza de Matemática Financiera, en los diversos programas de Ciencias Sociales,y la forma como los profesores que tienen la dirección del curso, brindan las herramientas necesarias para llevar a cabo una investigación en el área, luego de detectarse ausencia de conceptos básicos. La Matemática Financiera, debe ser mirada como un curso de origen en las ciencias exactas y no como un instrumento del formulismo, y dar la oportunidad a que sus instructores tengan formación académica de pregrado y/o posgrado en Matemática

Labor docente y calidad educativa de los oficiales alumnos del diplomado en Liderazgo y Gestión del Batallón de Intendencia de la Escuela de Intendencia del Ejército – 2018

El objetivo de la presente investigación fue determinar de qué manera se relaciona la labor docente con la calidad educativa, en la Escuela de Intendencia del Ejército – 2018. El enfoque fue de una investigación cuantitativa, de tipo aplicada y nivel descriptivo correlacional, de diseño no experimental. La población la constituye 12 Tenientes del Diplomado en Liderazgo y Gestión de la Compañía de Intendencia, y la muestra fue censal, a quienes se les aplicó una encuesta de 14 preguntas con una escala de cinco categorías de respuestas referida a ambas variables. Este instrumento tuvo una alta confiabilidad de 0.910. Se realizó el análisis correspondiente a los resultados de la encuesta llegando a la demostración empírica de que un 86.75% apoya o considera positivamente los requerimientos de los indicadores y las dimensiones propuestas en el instrumento; esto fue ampliamente corroborado y contrastado empleando el chi cuadrado. Se concluyó que la labor docente se relaciona directamente con la calidad educativa en la Escuela de Intendencia del Ejército – 2018.The objective of the present investigation was to determine how the teaching work relates to educational quality, in the School of Intendance of the Army - 2018. The focus was on quantitative research, applied type and correlational descriptive level, of non- experimental design. The population consists of 12 Lieutenants of the Diploma in Leadership and Management of the Company of Intendance, and the sample was census, to which a survey of 14 questions was applied with a scale of five categories of answers referred to both variables. This instrument had a high reliability of 0.910. The analysis corresponding to the results of the survey was carried out, arriving at the empirical demonstration that 86.75% positively supports or considers the requirements of the indicators and the dimensions proposed in the instrument; this was widely corroborated and contrasted using chi square. It was concluded that the teaching work is directly related to the quality of education in the School of Intendance of the Army - 2018