Photoluminescence of Tilapia skin collagen: Aggregation-induced emission with clustering triggered emission mechanism and its multiple applications.

There is an urgent need for natural sources of aggregation-induced emission (AIE) materials which have good water solubility, biocompatibility, and can be produced in large quantities. Here, Tilapia skin collagen (Tsc) is a very abundant protein in nature, with solid-phase and solution-state fluorescence emission effect and its multiple applications was explored. Due to Tsc was in high concentration or aggregation state which shown AIE property. This obvious emission can be account for clustering-triggered emission (CTE) mechanism. The photoluminescence property of Tsc not only provide a deeper understanding of the emission characteristics of proteins, but also has important guiding significance for further elucidating the basis of fluorescence properties.

Tratamento de queimaduras de segundo grau profundo em abdômen, coxas e genitália: uso da pele de tilápia como um xenoenxerto / Treatment of deep second-degree burns on the abdomen, thighs, and genitalia: use of tilapia skin as a xenograft

A pele de tilápia possui microbiota não infecciosa e estrutura morfológica semelhante à pele humana. Estudos clínicos fase II, ainda não publicados, mostraram resultados promissores na sua utilização para tratamento de queimaduras. Nos protocolos destes estudos, pacientes com lesões em áreas de dobras de pele, como genitais e região inguinal, foram excluídos, pois achava-se que o biomaterial não aderiria apropriadamente, resultando em um grau de cicatrização inferior. Relato de caso de paciente do sexo feminino, 18 anos, sem comorbidades, com queimaduras de segundo grau profundo em abdômen, região inguinal, parte da genitália e metade superior de ambas as coxas, envolvendo 13,5% da área total da superfície corporal. A pele de tilápia foi aplicada nas lesões levando a uma reepitelização completa com 16 dias de tratamento. Não foram observados efeitos colaterais. A pele de tilápia traz, portanto, a promessa de um produto inovador, de fácil aplicação e alta disponibilidade, que pode se tornar a primeira pele animal nacionalmente estudada e registrada pela Agência Nacional de Vigilância Sanitária, para uso no tratamento de queimaduras. Este relato de caso contribui para reduzir as limitações em relação às áreas anatômicas apropriadas para a aplicação da pele de tilápia, uma vez que, mesmo com a necessidade de reposição de pele, foram obtidos bons resultados com aplicação na genitália e região inguinal.

Tilapia skin has a non-infectious microbiota and a morphological structure similar to human skin. Phase II clinical studies, not yet published, have shown promising results in their use for the treatment of burns. In the protocols of these studies, patients with lesions in areas of skin folds, such as genitals and inguinal regions, were excluded, as it was thought that the biomaterial would not adhere properly, resulting in a lower degree of healing. Case report of a female patient, 18 years old, without comorbidities, with deep second-degree burns in the abdomen, inguinal region, part of the genitalia and upper half of both thighs, involving 13.5% of the total body surface area. Tilapia skin was applied to the lesions leading to a complete re-epithelialization with 16 days of treatment. No side effects were observed. Tilapia skin, therefore, brings the promise of an innovative product, easy to apply, and highly available, which can become the first animal skin nationally studied and registered by the Agência Nacional de Vigilância Sanitária, for use in the treatment of burns. This case report contributes to reduce the limitations concerning the anatomical areas appropriate for the application of tilapia skin, since, even with the need for skin replacement, good results were obtained with application to the genitalia and inguinal region.

Evaluation of decellularized tilapia skin as a tissue engineering scaffold.

Decellularized bovine and porcine tissues have been used as scaffolds to support tissue regeneration but inherit religious restrictions and risks of disease transmission to humans. Decellularized marine tissues are seen as attractive alternatives due to their similarity to mammalian tissues, reduced biological risks, and less religious restrictions. The aim of this study was to derive an acellular scaffold from the skin of tilapia and evaluate its suitability as a tissue engineering scaffold. Tilapia skin was treated with a series of chemical and enzymatic treatments to remove cellular materials. The decellularized tilapia skin (DTS) was then characterized and evaluated in vitro and in vivo to assess its biological compatibility. The results indicated that the decellularization process removed 99.6% of the DNA content from tilapia skin. The resultant DTS was shown to possess a high denaturation temperature of 68.1 ± 1.0°C and a high Young's modulus of 56.2 ± 14.4 MPa. The properties of DTS were also compared against those of crosslinked electrospun tilapia collagen membrane, another form of tilapia-derived collagen scaffold. In vitro studies revealed that both DTS and crosslinked electrospun tilapia collagen promoted cellular metabolic activity, differentiation, and mineralization of murine preosteogenic MC3T3-E1 cells. The rat calvarial defect model was used to evaluate the in vivo performance of the scaffolds, and both scaffolds did not induce hyperacute rejections. Furthermore, they enhanced bone regeneration in the critical defect compared with the sham control. This study suggests that tilapia-derived scaffolds have great potential in tissue engineering applications.

Gonad pathology and intersex severity in pelagic (Tilapia zilli) and benthic (Neochanna diversus and Clarias gariepinus) species from a pesticide-impacted agrarian catchment, south-south Nigeria.

Pesticides are distributed to different degrees in surface water and sediment, thus, risks of toxicity and adverse impacts to physiology of resident species could be determined by their microhabitat (sub-habitat) associations, either water column or sediment. River Owan receives pesticide input from diffuse sources from adjacent farmlands. Surface water, sediment and fish samples [(Pelagic: Tilapia zilli (n = 92) and benthic: Neochanna diversus (n = 59), Clarias gariepinus (n = 68) were collected within the catchment area across seasons for 18-months (August 2016-January 2018) and measured for pesticide levels. Testicular and Ovarian tissue samples across the three species were also examined for pathological alterations. Individual pesticide concentrations in surface water and sediment exceeded international allowable limits, while concentration of pesticide residues in tissues of benthic species was higher compared to pelagic fish. Histopathological assessment revealed a higher incidence of ovarian disruption including atretic follicles, intersex and disorganization of ovarian structure in benthic (bottom-dwelling) fish (C. gariepinus and N. diversus) compared to pelagic (water-column) fish (T. zilli). Males benthic fish species also recorded more severe anomalies, compared to pelagic fish. The damages and anomalies observed in ovarian and testicular tissue indicate chronic responses to pollutant exposure, and implicates the elevation of pesticide concentrations in surface water and sediment above permissible limits. The higher incidence of anomalies recorded for benthic species compared to pelagic species, indicates greater risks of reproductive disruption and could be associated with the microhabitat preferences (water-column or sediment).

Ultrastructure features of the surface of the gills and the lower pharyngeal jaw of the Tilapia Zilli, redbelly tilapia (Coptodon Zillii, Gervais, 1848).

The present investigation was designed to describe the surface ultrastructure of the gill system of tilapia Zilli. The gill system is formed from four gill arches and each gill arch carries a row of gill filaments on its convex border and two rows of the gill rakers on its concave border. The quadrilateral interbranchial septum has elevated part at the level of the third gill arch. By SEM observations, the gill arch was divided into three regions: rostral, middle and caudal region. The caudal region contained two characteristic structures: oval leaf-like structure and rounded-shaped structure. Each oval leaf-like structure carried two lateral rows of the triangular pointed spines separated by a median groove. All surfaces of gill arches, rakers and filaments were covered with a mosaic of the polygonal pavement cells, in addition to the opening of chloride cells and mucous cells. The gill arch and gill raker had only one appearance of taste buds named type I. Meanwhile, the filaments contained two types of different appearance of the taste buds named: type I and type II. Type I was the main common and similar to that present in gill arch and raker and characterized by its blunt end, while type II had hair-like structures that projected from the volcano-shaped depression. The gill rakers were formed from central axis surrounded by two lateral lobulated regions which carry pointed spines, taste buds and the opening of chloride cells. The surface of triangular lower pharyngeal jaw carries numerous teeth-like papillae which originated from the socket-like depression.

Developing a machine vision system for simultaneous prediction of freshness indicators based on tilapia (Oreochromis niloticus) pupil and gill color during storage at 4°C.

The study assessed the feasibility of developing a machine vision system based on pupil and gill color changes in tilapia for simultaneous prediction of total volatile basic nitrogen (TVB-N), thiobarbituric acid (TBA) and total viable counts (TVC) during storage at 4°C. The pupils and gills were chosen and color space conversion among RGB, HSI and L∗a∗b∗ color spaces was performed automatically by an image processing algorithm. Multiple regression models were established by correlating pupil and gill color parameters with TVB-N, TVC and TBA (R2=0.989-0.999). However, assessment of freshness based on gill color is destructive and time-consuming because gill cover must be removed before images are captured. Finally, visualization maps of spoilage based on pupil color were achieved using image algorithms. The results show that assessment of tilapia pupil color parameters using machine vision can be used as a low-cost, on-line method for predicting freshness during 4°C storage.

Isochoric and isobaric freezing of fish muscle.

We have recently shown that, a living organism, which succumbs to freezing to -4 °C in an isobaric thermodynamic system (constant atmospheric pressure), can survive freezing to -4 °C in an isochoric thermodynamic system (constant volume). It is known that the mechanism of cell damage in an isobaric system is the freezing caused increase in extracellular osmolality, and, the consequent cell dehydration. An explanation for the observed survival during isochoric freezing is the thermodynamic modeling supported hypothesis that, in the isochoric frozen solution the extracellular osmolality is comparable to the cell intracellular osmolality. Therefore, cells in the isochoric frozen organism do not dehydrate, and the tissue maintains its morphological integrity. Comparing the histology of: a) fresh fish white muscle, b) fresh muscle frozen to -5 °C in an isobaric system and c) fresh muscle frozen to -5 °C I in an isochoric system, we find convincing evidence of the mechanism of cell dehydration during isobaric freezing. In contrast, the muscle tissue frozen to -5 °C in an isochoric system appears morphologically identical to fresh tissue, with no evidence of dehydration. This is the first experimental evidence in support of the hypothesis that in isochoric freezing there is no cellular dehydration and therefore the morphology of the frozen tissue remains intact.

Histopathological analysis of tilapia gills (Oreochromis niloticus Linnaeus, 1758) exposed to sugarcane vinasse.

Sugarcane vinasse is one of the main residues generated by the transformation of cane into ethanol. Because of the high organic content (COD), high biochemical oxygen demand (BOD), low pH, the large amount that this residue is generated (15l for every liter of ethanol produced) and their use as fertilizer on the sugarcane crop, this residue is potentially polluting to the soil ecossystem and by percolation to water ecossystem too. Thus, this study aimed to assess the toxicity of vinasse by analyzing Oreochromis niloticus gills exposed to different dilutions (1%, 2.5%, 5% and 10%) in two bioassays. The gills were collected, fixed and analyzed using ultra morphological, histological, and histochemical techniques. After exposure to the vinasse, a statistically significant reduction of the ridges present on the surface of pavimentous cells was observed in one of the bioassays; such structures are responsible for mucus retention, which helps to protect the tissue. In addition, an intumescence of the cells was observed in the treatments with vinasse as well as an increase in the amount of chloridric cells. Some striking tissue changes detected in the treatments were epithelial detachment and loss of integrity of secondary lamellae, causing their rupture and consequent hemorrhage. In the first bioassay, the amount of these changes was statistically significant at the 5% dilution, and the focus of hemorrhage was significant at all dilution ratios. In the second bioassay, the epithelial disorganization was statistically significant only at the 2.5% dilution of vinasse. Moreover, for both bioassays performed, a significant increase in mucous cells was observed when compared with the control. Our results demonstrate the toxic action of sugarcane vinasse, which caused histopathological changes in the exposed animals at all four dilution tested. This highlights the need for caution in the disposal of sugarcane vinasse on the soil, especially due to its capacity for being leached or percolated into water resources, which could seriously damage aquatic fauna.

Anatomical and functional gonadotrope networks in the teleost pituitary.

Mammalian pituitaries exhibit a high degree of intercellular coordination; this enables them to mount large-scale coordinated responses to various physiological stimuli. This type of communication has not been adequately demonstrated in teleost pituitaries, which exhibit direct hypothalamic innervation and expression of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in distinct cell types. We found that in two fish species, namely tilapia and zebrafish, LH cells exhibit close cell-cell contacts and form a continuous network throughout the gland. FSH cells were more loosely distributed but maintained some degree of cell-cell contact by virtue of cytoplasmic processes. These anatomical differences also manifest themselves at the functional level as evidenced by the effect of gap-junction uncouplers on gonadotropin release. These substances abolished the LH response to gonadotropin-releasing hormone stimulation but did not affect the FSH response to the same stimuli. Dye transfer between neighboring LH cells provides further evidence for functional coupling. The two gonadotropins were also found to be differently packaged within their corresponding cell types. Our findings highlight the evolutionary origin of pituitary cell networks and demonstrate how the different levels of cell-cell coordination within the LH and FSH cell populations are reflected in their distinct secretion patterns.

Chondrogenic differentiation of human mesenchymal stem cells on fish scale collagen.

Fish collagen has recently been reported to be a novel biomaterial for cell and tissue culture as an alternative to conventional mammalian collagens such as bovine and porcine collagens. Fish collagen could overcome the risk of zoonosis, such as from bovine spongiform encephalopathy. Among fish collagens, tilapia collagen, the denaturing temperature of which is near 37°C, is appropriate for cell and tissue culture. In this study, we investigated chondrogenic differentiation of human mesenchymal stem cells (hMSCs) cultured on tilapia scale collagen fibrils compared with porcine collagen and non-coated dishes. The collagen fibrils were observed using a scanning electronic microscope. Safranin O staining, glycosaminoglycans (GAG) expression, and real-time PCR were examined to evaluate chondrogenesis of hMSCs on each type of collagen fibril. The results showed that hMSCs cultured on tilapia scale collagen showed stronger Safranin O staining and higher GAG expression at day 6. Results of real-time PCR indicated that hMSCs cultured on tilapia collagen showed earlier SOX9 expression on day 4 and higher AGGRECAN and COLLAGEN II expression on day 6 compared with on porcine collagen and non-coated dishes. Furthermore, low mRNA levels of bone gamma-carboxyglutamate, a specific marker of osteogenesis, showed that tilapia collagen fibrils specifically enhanced chondrogenic differentiation of hMSCs in chondrogenic medium, as well as porcine collagen. Accordingly, tilapia scale collagen may provide an appropriate collagen source for hMSC chondrogenesis in vitro.

Endocrine-disruptor molecular responses, occurrence of intersex and gonado-histopathological changes in tilapia species from a tropical freshwater dam (Awba Dam) in Ibadan, Nigeria.

In the present study, the occurrence of endocrine disruptive responses in Tilapia species from Awba Dam has been investigated, and compared to a reference site (Modete Dam). The Awba Dam is a recipient of effluents from University of Ibadan (Nigeria) and several other anthropogenic sources. A total of 132 Tilapia species (Sarotherodon malenotheron (n=57 and 32, males and females, respectively) and Tilapia guineensis (n=23 and 20, males and females, respectively)) were collected from June to September 2014. At the reference site, samples of adult male and female S. melanotheron (48 males and 47 females) and T. guineensis (84 males and 27 females) were collected. Gonads were morphologically and histologically examined and gonadosomatic index (GSI) was calculated. Hepatic mRNA transcriptions of vitellogenin (Vtg) and zona radiata protein (Zrp) genes were analyzed using validated RT-qPCR. Significant increase in Vtg and Zrp transcripts were observed in male tilapias from Awba Dam, compared to males from the reference site. In addition, male tilapias from Awba Dam produced significantly higher Vtg and Zrp mRNA, compared to females in June and July. However, at the natural peak spawning period in August and September, females produced, significantly higher Vtg and Zrp mRNA, compared to males. Fish gonads revealed varying incidence of intersex with a striking presence of two (2) pairs of testes and a pair of ovary in S. melanotheron from Awba Dam. The entire fish population examined at Awba Dam showed a high prevalence of intersex (34.8%), involving phenotypic males and females of both species. Analysis of sediment contaminant levels revealed that As, Cd, Pb, Hg and Ni (heavy metals), monobutyltin cation, 4-iso-nonyphenol and PCB congeners (138, 153 and 180) were significantly higher in Awba Dam, compared to the reference site. Principal component analysis (PCA) showed that fish variables were positively correlated with sediment contaminant burden at Awba Dam, indicating that the observed endocrine disruptive responses are associated with contaminant concentrations. Overall, the occurrence of intersex and elevated expressions of Vtg and Zrp in male fish, suggest that the measured contaminants were eliciting severe endocrine disruptive effects in Awba Dam biota, which is an important source of domestic water supply and fisheries for the University of Ibadan community.

Stock assessment of fishery target species in Lake Koka, Ethiopia.

Effective management is essential for small-scale fisheries to continue providing food and livelihoods for households, particularly in developing countries where other options are often limited. Studies on the population dynamics and stock assessment on fishery target species are thus imperative to sustain their fisheries and the benefits for the society. In Lake Koka (Ethiopia), very little is known about the vital population parameters and exploitation status of the fishery target species: tilapia Oreochromis niloticus, common carp Cyprinus carpio and catfish Clarias gariepinus. Our study, therefore, aimed at determining the vital population parameters and assessing the status of these target species in Lake Koka using length frequency data collected quarterly from commercial catches from 2007-2012. A total of 20,097 fish specimens (distributed as 7,933 tilapia, 6,025 catfish and 6,139 common carp) were measured for the analysis. Von Bertalarffy growth parameters and their confidence intervals were determined from modal progression analysis using ELEFAN I and applying the jackknife technique. Mortality parameters were determined from length-converted catch curves and empirical models. The exploitation status of these target species were then assessed by computing exploitation rates (E) from mortality parameters as well as from size indicators i.e., assessing the size distribution of fish catches relative to the size at maturity (Lm), the size that provides maximum cohort biomass (Lopt) and the abundance of mega-spawners. The mean value of growth parameters L∞, K and the growth performance index ø' were 44.5 cm, 0.41/year and 2.90 for O. niloticus, 74.1 cm, 0.28/year and 3.19 for C. carpio and 121.9 cm, 0.16/year and 3.36 for C. gariepinus, respectively. The 95 % confidence intervals of the estimates were also computed. Total mortality (Z) estimates were 1.47, 0.83 and 0.72/year for O. niloticus, C. carpio and C. gariepinus, respectively. Our study suggest that O. niloticus is in a healthy state, while C. gariepinus show signs of growth overfishing (when both exploitation rate (E) and size indicators were considered). In case of C. carpio, the low exploitation rate encountered would point to underfishing, while the size indicators of the catches would suggest that too small fish are harvested leading to growth overfishing. We concluded that fisheries production in Lake Koka could be enhanced by increasing E toward optimum level of exploitation (Eopt) for the underexploited C. carpio and by increasing the size at first capture (Lc) toward the Lopt, range for all target species.

The response of anosteocytic bone to controlled loading.

The bones of the skeleton of most advanced teleost fish do not contain osteocytes. Considering the pivotal role assigned to osteocytes in the process of modeling and remodeling (the adaptation of external and internal bone structure and morphology to external loads and the repair of areas with micro-damage accumulation, respectively) it is unclear how, and even whether, their skeleton can undergo modeling and remodeling. Here, we report on the results of a study of controlled loading of the anosteocytic opercula of tilapia (Oreochromis aureus). Using a variety of microscopy techniques we show that the bone of the anosteocytic tilapia actively adapts to applied loads, despite the complete absence of osteocytes. We show that in the directly loaded area, the response involves a combination of bone resorption and bone deposition; we interpret these results and the structure of the resultant bone tissue to mean that both modeling and remodeling are taking place in response to load. We further show that adjacent to the loaded area, new bone is deposited in an organized, layered manner, typical of a modeling process. The material stiffness of the newly deposited bone is higher than that of the bone which was present prior to loading. The absence of osteocytes requires another candidate cell for mechanosensing and coordinating the modeling process, with osteoblasts seeming the most likely candidates.

Stock assessment of fishery target species in Lake Koka, Ethiopia / Evaluación de las reservas pesqueras de especies objetivo en el lago Koka, Etiopia

Effective management is essential for small-scale fisheries to continue providing food and livelihoods for households, particularly in developing countries where other options are often limited. Studies on the population dynamics and stock assessment on fishery target species are thus imperative to sustain their fisheries and the benefits for the society. In Lake Koka (Ethiopia), very little is known about the vital population parameters and exploitation status of the fishery target species: tilapia Oreochromis niloticus,common carp Cyprinus carpióand catfish Clarias gariepinus.Our study, therefore, aimed at determining the vital population parameters and assessing the status of these target species in Lake Koka using length frequency data collected quarterly from commercial catches from 2007-2012. A total of 20 097 fish specimens (distributed as 7 933 tilapia, 6 025 catfish and 6 139 common carp) were measured for the analysis. Von Bertalanffy growth parameters and their confidence intervals were determined from modal progression analysis using ELEFAN I and applying the jackknife technique. Mortality parameters were determined from length-converted catch curves and empirical models. The exploitation status of these target species were then assessed by computing exploitation rates (E) from mortality parameters as well as from size indicators i.e., assessing the size distribution of fish catches relative to the size at maturity (L m),the size that provides maximum cohort biomass (Lopt) and the abundance of mega-spawners. The mean value of growth parameters L x, Kand the growth performance index 0' were 44.5 cm, 0.41/year and 2.90 for O. niloticus,74.1 cm, 0.28/year and 3.19 for C. carpioand 121.9 cm, 0.16/year and 3.36 for C. gariepinus,respectively. The 95 % confidence intervals of the estimates were also computed. Total mortality (Z) estimates were 1.47, 0.83 and 0.72/year for O. niloticus, C. carpioand C. gariepinus,respectively. Our study suggest that O. niloticusis in a healthy state, while C. gariepinusshow signs of growth overfishing (when both exploitation rate (E)and size indicators were considered). In case of C. carpio,the low exploitation rate encountered would point to underfishing, while the size indicators of the catches would suggest that too small fish are harvested leading to growth overfishing. We concluded that fisheries production in Lake Koka could be enhanced by increasing Etoward optimum level of exploitation (E opt)for the underexploited C. carpioand by increasing the size at first capture (Lc)toward the L opt range for all target species.

Un manejo pesquero eficiente es fundamental para que las pesquerías artesanales puedan continuar proveyendo alimento y sustento para los hogares, particularmente en los países en vía de desarrollo, en donde otras opciones a menudo son limitadas. Estudios sobre la dinámica poblacional de las especies objetivo de las pesquerías son, por lo tanto, imperativos para mantener las pesquerías y los beneficios para las sociedades. Esto también es válido para los recursos del Lago Koka (Etiopia) en donde hasta ahora se sabe muy poco sobre los parámetros poblacionales vitales y el estatus de las especies objetivo como la tilapia Oreochromis niloticus,la carpa Cyprinus carpioy el bagre Clarias gariepinus.El estudio aquí presentado tiene como objetivo determinar estos parámetros y evaluar el estado de la pesquería de estas especies en el lago Koka, utilizando los datos de frecuencia de tallas obtenidas de capturas trimestrales en el periodo 2007-2012. Un total de 20 097 especímenes fueron medidos (7 933 de tilapia, 6 025 de bagre y 6 139 de carpa). Los parámetros de crecimiento de von Bertalanffy fueron derivados del análisis de progresión de las modas usando ELEFAN I y aplicando la técnica de jackknife. Las tasas de mortalidad fueron estimadas de curvas de capturas basadas en longitudes y usando modelos empíricos. La tasa de explotación (E), se estimó con los parámetros de mortalidad y también considerando indicadores del tamaño a través de la distribución de tallas en las capturas y su relación con la talla de la primera madurez (L m),el tamaño que provee la biomasa máxima del cohorte (L opt)y la abundancia de los "mega-desovantes". Los valores calculados para los parámetros de crecimiento L m, Ky el índice de la capacidad de crecimiento 0' fueron: 44.5 cm, 0.41 año-1 y 2.90 para O. niloticus,74.1 cm, 0.28 año-1 y 3.19 para C. carpióy 121.9 cm, 0.16 año-1 y 3.36 para C. gariepinus,respectivamente. La tasa de mortalidad total (Z) fue estimada en 1.47, 0.83 y 0.72 año-1 para O. niloticus, C. carpioand C. gariepinus,respectivamente. Nuestros resultados sugieren que la población de O. niloticusse encuentra en un estado saludable, mientras C. gariepinusya muestra signos de sobrepesca por crecimiento. En el caso de C. carpiolas tasas de explotación tan bajas (E<0.5) que se encontraron, pueden apuntar a una sub-explotación, mientras que los indicadores de tallas sugieren que las pequeñas tallas obtenidas, pueden conducir a una sobrepesca por crecimiento. Concluimos que la producción pesquera en el lago Koka puede ser mejorada si se incrementa E al nivel E opt para C. carpioy aumenta el tamaño de la primera captura (Lc)al rango de L opt para todas las especies objetivo.

The three-dimensional structure of anosteocytic lamellated bone of fish.

Fish represent the most diverse and numerous of the vertebrate clades. In contrast to the bones of all tetrapods and evolutionarily primitive fish, many of the evolutionarily more advanced fish have bones that do not contain osteocytes. Here we use a variety of imaging techniques to show that anosteocytic fish bone is composed of a sequence of planar layers containing mainly aligned collagen fibrils, in which the prevailing principal orientation progressively spirals. When the sequence of fibril orientations completes a rotation of around 180°, a thin layer of poorly oriented fibrils is present between it and the next layer. The thick layer of aligned fibrils and the thin layer of non-aligned fibrils constitute a lamella. Although both basic components of mammalian lamellar bone are found here as well, the arrangement is unique, and we therefore call this structure lamellated bone. We further show that the lamellae of anosteocytic fish bone contain an array of dense, small-diameter (1-4 µm) bundles of hypomineralized collagen fibrils that are oriented mostly orthogonal to the lamellar plane. Results of mechanical tests conducted on beams from anosteocytic fish bone and human cortical bone show that the fish bones are less stiff but much tougher than the human bones. We propose that the unique lamellar structure and the orthogonal hypomineralized collagen bundles are responsible for the unusual mechanical properties and mineral distribution in anosteocytic fish bone.

Air breathing in Magadi tilapia Alcolapia grahami, under normoxic and hyperoxic conditions, and the association with sunlight and reactive oxygen species.

Observations of the Magadi tilapia Alcolapia grahami in hot, highly alkaline Lake Magadi revealed that they air breathe not only during hypoxia, as described previously, but also during normoxia and hyperoxia. Air breathing under these latter conditions occurred within distinct groupings of fish (pods) and involved only a small proportion of the population. Air breathing properties (duration and frequency) were quantified from video footage. Air breathing within the population followed a diel pattern with the maximum extent of pod formation occurring in early afternoon. High levels of reactive oxygen species (ROS) in the water may be an irritant that encourages the air-breathing behaviour. The diel pattern of air breathing in the field and in experiments followed the diel pattern of ROS concentrations in the water which are amongst the highest reported in the literature (maximum daytime values of 2.53 ­ 8.10 µM H2O2). Interlamellar cell masses (ILCM) occurred between the gill lamellae of fish from the lagoon with highest ROS and highest oxygen levels, while fish from a normoxic lagoon with one third the ROS had little or no ILCM. This is the first record of air breathing in a facultative air-breathing fish in hyperoxic conditions and the first record of an ILCM in a cichlid species.

Acute exposure to pure cylindrospermopsin results in oxidative stress and pathological alterations in tilapia (Oreochromis niloticus).

Cylindrospermopsin (CYN) is increasingly recognized as a potential threat to drinking water safety, due to its ubiquity. This cyanotoxin has been found to cause toxic effects in mammals, and although fish could be in contact with this toxin, acute toxicity studies on fish are nonexistent. This is the first study showing that single doses of CYN pure standard (200 or 400 µg CYN/kg fish bw) by oral route (gavage) generate histopathological effects in fish (Tilapia-Oreochromis niloticus) exposed to the toxin under laboratory condition. Among the morphological changes, disorganized parenchymal architecture in the liver, dilated Bowman's space in the kidney, fibrolysis in the heart, necrotic enteritis in the intestines, and hemorrhages in the gills, were observed. Moreover, some oxidative stress biomarkers in the liver and kidney of tilapias were altered. Thus, CYN exposure induced increased protein oxidation products in both organs, NADPH oxidase activity was significantly increased with the kidney being the most affected organ, and decreased GSH contents were also detected in both organs, at the higher dose assayed.

Biomarker responses and morphological effects in juvenile tilapia Oreochromis mossambicus following sequential exposure to the organophosphate azinphos-methyl.

Pesticides are contaminants of aquatic environments. Such ecosystems in the Western Cape, South Africa are at risk as most organophosphates are highly toxic to fish and other aquatic organisms. The objective of this experimental study was firstly to determine the acute toxicity of azinphos-methyl (AZP) to juvenile fish (Oreochromis mossambicus) and, secondly, to investigate the effects of repeated exposure of fish to an array of sublethal concentrations on morphological parameters such as growth, condition factor and organ-somatic indices. Food consumption and feeding response time were investigated as ecologically relevant behavioral endpoints which could affect growth, reproduction and survival and subsequently causes impacts at the population and/or community level. Finally, acetylcholinesterase (AChE) was used as biomarker to investigate effects at sub-organismal level following sequential exposure to AZP. The aim was to determine how sequential spraying procedures, using different exposure concentrations and intervals, affected fish as reflected by their responses at different organizational levels. A dose-dependent effect on feeding impairment was observed in the feeding response experiment. The correlation found between growth impairment, feeding activity and AChE inhibition therefore indicates that frequency of exposure can play an important role regarding the severity of impacts to non-target organisms. This study provides evidence that AZP has harmful effects on non-target aquatic organisms, such as fish which can be manifested in the early developmental stages. Sequential exposures showed that dosage and frequency of spraying and spraying interval could exacerbate harmful effects. AChE inhibition and organosomatic indices can be used effectively to measure effects.

Biochemical and cellularchanges in Oreochromis niloticus related to the water pollution of a degraded river / Alterações bioquímicas e celulares em Oreochromis niloticus relacionadas com a poluição da água de um rio degradado

The effects of polluted water at three sites in the Marinho River, Brazil, on Oreochromis niloticus (Nile tilápia) were investigated using histological, hematological and biochemical approaches. Fish exposed to the impacted water demonstrated that histological changes in gills were accompanied by nuclear and micronuclei abnormalities in cells. The activity of liver and plasma biomarkers (alkaline phosphatase (ALP), acid phosphatase (ACP), alanine aminotransferase (ALT), aspartate aminotransferase (AST) and liver glutathione S-transferase (GST)) showed an expressive change due to the. The results were also correlated with the highest levels of Cu+2, Zn+2 and Mn+2 in the water. The data of this study evidenced the importance of using a set of biomarkers to quantify pollution in lentic ecosystems. Additionally, histological analyses of gills and erythrocytes have proven to be an important instrument for signaling the impact of pollutants in rivers.

Os efeitos da poluição da água de três locais do Rio Marinho, Brasil, em Oreochromis niloticus foram investigados usando técnicas histológicas, hematológicas e bioquímicas. Peixes expostos à água impactada demonstraram que alterações histológicas nas brânquias foram acompanhadas de anomalias nucleares e micronúcleo nas células. A determinação da atividade de biomarcadores em fígado e plasma de tilápia (fosfatase alcalina (ALP), fosfatase ácida (ACP), alanina aminotransferase (ALT), aspartato aminotransferase (AST) e glutationa S-transferase (GST)) mostrou uma substancial alteração em função da poluição. Os resultados são correlacionados com os níveis mais elevados de Cu+2, Zn+2 e Mn+2 na água. Os dados deste estudo demonstram a importância de utilizar um conjunto de biomarcadores para quantificar a poluição em ecossistemas lênticos. Adicionalmente, as análises histológicas das brânquias e de eritrocitos têm provado ser importante instrumento para sinalizar a impactação de poluentes ao longo de rios.

Early response of protein quality control in gills is associated with survival of hypertonic shock in Mozambique tilapia.

The protein quality control (PQC) mechanism is essential for cell function and viability. PQC with proper biological function depends on molecular chaperones and proteases. The hypertonicity-induced protein damage and responses of PQC mechanism in aquatic organisms, however, are poorly understood. In this study, we examine the short-term effects of different hypertonic shocks on the levels of heat shock proteins (HSPs, e.g., HSP70 and HSP90), ubiquitin-conjugated proteins and protein aggregation in gills of the Mozambique tilapia (Oreochromis mossambicus). Following transfer from fresh water (FW) to 20‰ hypertonicity, all examined individuals survived to the end of experiment. Moreover, the levels of branchial HSPs and ubiquitin-conjugated proteins significantly increased at 3 and 24 h post-transfer, respectively. Up-regulation of HSPs and ubiquitin-conjugated proteins was sufficient to prevent the accumulation of aggregated proteins. However, the survival rate of tilapia dramatically declined at 5 h and all fish died within 7 h after direct transfer to 30‰ hypertonicity. We presumed that this result was due to the failed activation of gill PQC system, which resulted in elevating the levels of aggregated proteins at 3 and 4 h. Furthermore, in aggregated protein fractions, the amounts of gill Na(+)/K(+)-ATPase (NKA) remained relatively low when fish were transferred to 20‰ hypertonicity, whereas abundant NKA was found at 4 h post-transfer to 30‰ hypertonicity. This study demonstrated that the response of PQC in gills is earlier than observable changes in localization of ion-secreting transport proteins upon hypertonic challenge. To our knowledge, this is the first study to investigate the regulation of PQC mechanism in fish and characterize its important role in euryhaline teleost survival in response to hypertonic stress.