Intracytoplasmic sperm injection (ICSI) in fishes

Sperm from zebrafish, Danio rerio, and Nile tilapia, Oreochromis niloticus, were microinjected directly into egg cytoplasm to evaluate the potential for developing a novel method of fertilization. In zebrafish, the sperm of two lines (wild-type and gold, long-fin) were injected with or without activation into activated and non-activated eggs. No significant difference (P = 0.997) in fertilization by intracytoplasmic sperm injection (ICSI) was observed between the two lines or when the sperm were activated or not (P = 0.057). There was significance difference in fertilization between activated and non-activated eggs (P = 0.010). The highest fertilization rate was achieved by injection of activated sperm into non-activated eggs (35%). From a total of 188 zebrafish eggs injected, 31 (16%) were fertilized, 10 (5%) developed as abnormal larvae and 3 (2%) developed normally and hatched. Damage of maternal chromosomes by the injection procedure could have caused the developmental abnormalities observed after ICSI. This was investigated by fluorescence microscopy using a DNA-specific stain (Hoechst 33324). Fixed and stained animal poles of zebrafish 30 sec after artificial insemination revealed that female chromosomes were located ~40 mm from the sperm injection site (micropyle). Staining of the animal pole after sperm injection showed no disruption of the formation of the second polar body or its extrusion. Evaluation of two sperm injection sites in zebrafish showed no difference in fertilization rate (P = 0.8264) or reduction of abnormal development. Nile tilapia eggs placed in Hanks\u27 balanced salt solution retained their viability for at least 3 hours after collection. Of a total of 160 Nile tilapia eggs injected with fresh sperm, 16 (10%) were fertilized, 10 (6%) developed abnormally to neurula and 5 (3%) developed normally and hatched, two of which reached adulthood. From 45 eggs injected with cryopreserved sperm, 9 (20%) were fertilized but none developed beyond blastula stage. Injections of sperm fixed in methanol did not yield fertilization. These results demonstrate for the first time that injection of single sperm cells into the cytoplasm of a fish egg allows fertilization and subsequent development of normal larvae to hatching and beyond

Investigation of the Role of BCR/ABL1 in Neutrophil Extracellular Trap (NET) Formation in Chronic Myeloid Leukemia (CML)

Neutrophil extracellular traps (NETs) represent a rather newly discovered antimicrobial mechanism first described by Brinkmann and co-workers in 2004. NETs are extracellular structures composed of decondensed chromatin decorated with granule proteins released from neutrophils to trap and kill invading microorganisms. In addition to their role in defense, excessive NET formation has been linked to the pathogenesis of several diseases including cardiovascular diseases, autoimmune diseases (e.g. lupus erythematous), infectious diseases (e.g. sepsis and covid-19), and cancer. However, the role of NETs in chronic myeloid leukemia (CML) has been sparsely explored. More information about the involvement of NETs in CML may provide increased understanding with respect to disease development and response to current therapy consisting of tyrosine kinase inhibitors (TKIs). Also, additional knowledge about NETs in general could facilitate potential development of novel anti-NET therapeutics. In this thesis, the NET forming capabilities of a CML cell line model and neutrophils isolated from CML patients together with the effects of tyrosine kinase inhibitors were investigated. The CML cell line Kcl-22 was intended used as a model system for NET formation in CML. First for the generation of neutrophils through cell differentiation followed by induction of these differentiated cells to produce NETs. However, it was discovered that the Kcl-22 cells did not differentiate towards neutrophils, although, subsequent detection of NET-like structures was observed in the Kcl-22 cell line after exposure to various differentiation agents and the NET stimulation compounds PMA and ionomycin. Successful induction of extracellular traps (ETs), decreased expression of CD15, and increased expression of CD33, together with an overall lack of segmented nuclei, suggested that these cells most likely had differentiated towards mast cells and that the ETs observed were mast cell extracellular traps (MCETs). In primary neutrophils, isolated from the peripheral blood of CML patients, NETs were observed ex vivo, both with and without exposure to stimulating agents. NET formation capacity of primary neutrophils derived from CML patients was compared to neutrophils derived from healthy individuals. Through immunofluorescence and fluorescence microscopy NETs formed by neutrophils from CML patients appeared increased in number and size compared to neutrophils from healthy donors. In addition, attempts to quantify NETs in primary neutrophils, by ELISA and manual counting, were performed comparing NET formation in neutrophils from CML patients to neutrophils from healthy donors to detect differences. BCR-ABL1 is the hallmark and oncogenic driver of CML and was investigated for a potential role in NET formation. The BCR-ABL1 activity, measured by phospho-BCR-ABL1, was demonstrated to be completely inhibited by treatment with the TKIs ponatinib and ABL001 in Kcl-22 cells, however, their capability to form ETs was not affected. Additionally, no altered NET formation was observed in primary neutrophils derived from one CML patient after TKI treatment. Together, this indicated that BCR-ABL1 does not play a direct role in NET formation. In conclusion, this thesis has shown that CML cells can form extracellular traps and that BCR-ABL1 does not seem to influence the amount of NET formation in CML primary neutrophils or ET formation in the Kcl-22 cell line.Masteroppgave i biomedisinBMED395MAMD-MEDB

Uso actual y potencialidades del producto local canario. Estudio de su consumo en hoteles de cuatro y cinco estrellas en la isla de Tenerife

Máster Universitario en Dirección y Planificación del TurismoThis study is deeply connected with the investigation carried out by GMR (Gestión del Medio Rural Canarias), which attempts to establish the level of knowledge that tourists have about the local product of the Canary Islands, its level of consumption and also its relation with the touristic sector in the isle of Tenerife. For that purpose, this study takes into account the analysis of the 2017 Tourist Expenditure Survey, which focuses on the role and importance of gastronomy within the touristic experience, as well as the relevance of the local product with respect to that experience. Furthermore, this study has carried out different questionnaires and interviews to collect specific data related with the actual consumption of local product within four and five stars hotels, allowing to portray the resources, capacities and limitations that the hotel sector has when choosing between foreign and canarian local products.El presente estudio se desarrolla como encargo motivado por la necesidad de un conocimiento más extenso por parte la entidad de Gestión del Medio Rural Canarias (GMR), sobre el nivel de consumo y conocimiento existentes del producto local canario, así como su vinculación con el sector turístico-alojativo en la isla de Tenerife. Para ello, este trabajo parte del análisis de la Encuesta de Gasto Turístico de 2017, la cual precisa el contexto actual de la gastronomía dentro del turismo, así como el papel que le otorga el turista a ésta y al producto local canario dentro de su experiencia turística. Seguidamente, a través del diseño y realización de cuestionarios y entrevistas, se obtienen datos específicos sobre consumo real en hoteles de cuatro y cinco estrellas de la isla, que permiten visualizar los recursos, limitaciones y capacidades que posee el sector hotelero ante la elección del producto local canario frente a otros

The role of predation risk in structuring life-history traits of crucian carp (Carassius carassius) in a series of small boreal lakes

Predation is a major evolutionary force determining life-history traits in prey by directand indirect mechanisms. This study focuses on life-history trait variation in cruciancarp (Carassius carassius), a species well known for developing a deep body as aninducible morphological defence against predation risk. Here, the authors tested vari-ation in growth and reproductive traits in 15 crucian carp populations in lakes along apredation risk gradient represented by increasingly efficient predator communities.Lakes were located in south-eastern Norway and were sampled in summer 2018 and2019. The authors expected crucian carp to attain higher growth rate, larger size, andlater age at maturity with increasing predation risk. In the absence of predators, theyexpected high adult mortality, early maturity and increased reproductive effortcaused by strong intraspecific competition. They found that the life-history traits ofcrucian carp were clearly related to the presence of piscivores: with increasing preda-tion risk, fish grew in body length and depth and attained larger asymptotic lengthand size at maturity. This growth was evident at young age, especially in productivelakes with pike, and it suggests that fish quickly outgrew the predation window byreaching a size refuge. Contrary to the authors’predictions, populations had similarage at maturity. High-predation lakes also presented low density of crucian carp. Thissuggests that fish from predator lakes may experience high levels of resource avail-ability due to reduced intraspecific competition. Predation regulated life-history traitsin crucian carp populations, where larger size, higher longevity and size at maturitywere observed in lakes with large gaped predators.publishedVersio

Rapid recovery of normal gill morphology and blood physiology in brown trout (Salmo trutta) after short-term exposure to toxic concentrations of aqueous aluminium under non-steady state chemical conditions

Freshwater acidification is characterised by elevated concentrations of aqueous aluminium. Global emissions of acidifying agents are reduced due to international agreements, and freshwater acidification has shifted from chronic to a more episodic character. The recovery of fish populations in acidified areas is likely to depend on the individual’s ability to recover from short-time aluminium exposures. We exposed brown trout (Salmo trutta) to an Al-rich medium, nominal concentration 600 µg L–1, for 0.5, 2, 6, 8 and 11 hours, before transfer to circumneutral Al-poor water for recovery. As controls, fish were either exposed for 11 hours to an acidified Al-poor medium or to untreated water. Some mortality during the first 24 hours of the recovery period occurred in fish exposed for 11, 8 and 6 hours to aluminium. No mortality during recovery was observed in the remaining groups. Aluminium exposure led to increased haematocrit and plasma lactate concentration, decreased plasma chloride concentration, deposition of aluminium on gill surfaces, and morphological alteration of the gill structures. The responses depended on exposure time. Aluminium deposited on the gill disappeared and plasma lactate levels were at control levels after 1 day in the recovery water, while haematocrit and plasma chloride levels were at control levels after 14 days of recovery. Gills in fish exposed to aluminium for 11 hours were almost fully recovered after 14 days. We conclude that the toxic response in brown trout exposed to an acutely toxic aluminium challenge is reversible. Moreover, the first 24 hours after aluminium exposures is the most critical period for the fish recovery. Further, it takes no more than 14 days for brown trout to fully recover from an acute toxic aluminium exposure, and only 1 day if the aluminium challenge is moderate.publishedVersio

Detección de periodos alcistas y bajistas en mercados financieros

En este trabajo de fin de grado realizamos una aproximación a los diferentes términos y métodos más utilizados en la detección de periodos alcistas y bajistas en los mercados financieros. Desde un punto de vista práctico, tendremos como objetivo principal analizar la evolución de las rentabilidades del índice americano S&P durante un periodo temporal concreto (1944-2015), utilizando el método del algoritmo de fechas y el método de las Cadenas de Markov mediante un lenguaje de programación específico, para así obtener sus diferentes periodos alcistas y bajistas. Posteriormente corroboraremos la exactitud con la que ambos métodos identifican los periodos bajistas, con las crisis globales de mayor relevancia. El estudio realizado y que plasmamos en este trabajo, creemos que aporta una perspectiva práctica del análisis de activos financieros para la detección de sus fases según las rentabilidades obtenidas, y que pueden ser determinantes a la hora de diseñar estrategias de inversión o desinversión en base al mejor conocimiento de las fases alcista y bajista del mercado financiero en base a sus datos históricosIn this paper, we have focused initially from a theoretical point of view, performing an approach to the different terms and methods most used in the bull and bear detection of the financial markets. From a practical point of view, our main objective will be to analyse the returns evolution of the American S&P Index through a specific programming language, in order to obtain its bull and bear periods. Subsequently, we will corroborate the accuracy with which both methods identify their bear periods, with the most relevant global crisis. We believe that the study carried out and presented in this paper provides a practical perspective on the analysis of financial assets, for the detection of their phases according to the returns obtained, which can be decisive when making an investment or disinvestment based on their historical data