Evaluation of the antimicrobial activity of Eucalyptus radiata essential oil against Escherichia coli strains isolated from meat products.

The present study sought to evaluate the antimicrobial and anti-adherent potential of Eucalyptus radiata essential oil against food-borne strains of Escherichia coli. The study was performed using the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC). In addition, the disk diffusion technique was used to evaluate the association of Eucalyptus radiata essential oil with synthetic antimicrobials. The Minimum Inhibitory Adherence Concentration (MIC) was also performed. The results revealed that E. radiata showed antimicrobial activity against the E. coli strains tested, with MIC values ranging from 500 µg/mL to 1000 µg/mL and MBC values ranging from 500 µg/mL to 1,024 µg/mL. As for the associations, it was observed that E. radiata oil exhibited a synergistic effect for some antibiotics, especially Ceftriaxone, with greater interference from the essential oil. Furthermore, it was effective in inhibiting the adherence of bacterial strains of E. coli, showing a more significant antibiofilm effect than the antibacterial agent 0.12% chlorhexidine digluconate. In summary, the essential oil of E. radiata showed antimicrobial potential against strains of E. coli of food origin, and can therefore, through in-depth studies, be used alone or in association with synthetic antimicrobials to combat infections caused by this pathogen.

Genetic diversity based on multivariate techniques in elephant grass genotypes for bioenergy.

The use of biomass for energy production constitutes a promising strategy that warrants the search for new sources of biomass. Elephant grass has been gaining notoriety due to its high dry matter yield and rapid growth. The present study was carried out to quantify the genetic divergence of nine elephant grass half-sib families in order to identify genotypes with greater genetic divergence and productive potential for hybridization, using the hierarchical clustering methodology based on principal components. Half-sib families were generated using genotypes from the Active Germplasm Bank of Elephant Grass. The experiment was laid out in a randomized-block design with nine half-sib families, three replicates, and eight plants per plot. A total of 216 genotypes of elephant grass were evaluated. Principal component (PC), biplot, and hierarchical clustering analyses for diversity estimation were conducted using R software. The first two PCs of biplot analysis accounted for 64% of the cumulative variation. Dry matter yield was the most important trait for genotype discrimination (0.89), followed by plant height (0.67) and stem diameter (0.61) in PC1. In this analysis, the distances between accessions were considered and there were no family links, which indicates the existence of wide variability within the evaluated families, since genotypes belonging to the same family were not grouped together, but rather distributed into different groups. Crosses between genotypes of group three and genotypes of groups one and two are recommended for the development of high-yielding genotypes when aiming at energy production.

Bone marrow mesenchymal/fibroblastic stromal cells induce a distinctive EMT-like phenotype in AML cells.

The development of epithelial-to-mesenchymal transition (EMT) like features is emerging as a critical factor involved in the pathogenesis of acute myeloid leukaemia (AML). However, the extracellular signals and the signalling pathways in AML that may regulate EMT remain largely unstudied. We found that the bone marrow (BM) mesenchymal/fibroblastic cell line HS5 induces an EMT-like migratory phenotype in AML cells. AML cells underwent a strong increase of vimentin (VIM) levels that was not mirrored to the same extent by changes of expression of the other EMT core proteins SNAI1 and SNAI2. We validated these particular pattern of co-expression of core-EMT markers in AML cells by performing an in silico analysis using datasets of human tumours. Our data showed that in AML the expression levels of VIM does not completely correlate with the co-expression of core EMT markers observed in epithelial tumours. We also found that vs epithelial tumours, AML cells display a distinct patterns of co-expression of VIM and the actin binding and adhesion regulatory proteins that regulate F-actin dynamics and integrin-mediated adhesions involved in the invasive migration in cells undergoing EMT. We conclude that the BM stroma induces an EMT related pattern of migration in AML cells in a process involving a distinctive regulation of EMT markers and of regulators of cell adhesion and actin dynamics that should be further investigated. Understanding the tumour specific signalling pathways associated with the EMT process may contribute to the development of new tailored therapies for AML as well as in different types of cancers.

Re-estimation of juvenile Isurus oxyrinchus growth in the Mexican Pacific through a multimodel inference approach and verification of growth band periodicity.

An update of the age and growth for juveniles of the short fin mako shark (I. oxyrinchus) from the Mexican Pacific is presented, based on the analysis of growth band counts from dorsal vertebrae of 198 individuals [110 females, 74-231 cm of total length (TL) and 88 males, 72-231 cm TL) caught during 2008-2018. New available information on vertebral growth band periodicity (biannual deposition in juveniles) and the convenience of using vertebrae form the dorsal region over the cervical region to count growth bands, as well as a multimodel approach, were used. The von Bertalanffy (VB) growth model, Gompertz, logistic and two parameters of VB (2-VB) were fitted to the length-at-age. Only ages ≤6 years were used for the fitting of the models and their performance was compared with the small-sample bias-corrected form of the Akaike information criterion (AICc), their differences ( ∆ i ) and weights ( w i ). Following a multimodel inference approach, the model averaged asymptotic length ( L ¯ inf ), length-at-age 0 ( L ¯ 0 ) and their unconditional standard error ( SE ¯ ), were estimated for each sex scenario using the three-parameter version of each model. The precision of growth band counts was acceptable for the different methods used and by two different readers. The centrum edge analysis (CEA) and marginal increment analysis (MIA) did not support the hypothesis of biannual band pair formation for juveniles, likewise for adults the periodicity could not be verified due to the small sample of large animals. Age was estimated assuming the formation of two pairs of growth bands per year during the first 5 years and one pair of bands per year afterwards considering direct validation information. The estimated ages in years ranged from 0-14 for females and 0-6 for males. The Kimura likelihood ratio test showed no differences in the growth curves of juveniles by sex (P > 0.05). According to the AICc, the 2-VB model better fitted the length-at-age data for combined sexes (Linf = 386.4 cm, k = 0.12 years-1 , L0 = 70 cm). The model averaged L ¯ inf and L ¯ 0 were 378.3 cm ( SE ¯ = 64.5 ) and 69.5 cm ( SE ¯ = 6.3 ), respectively. The growth parameters determined for juveniles of I. oxyrinchus are similar to those estimated in other regions, showing relatively fast growth rate as previously reported, medium longevity in comparison to other shark species and natural mortality close to that reported in the last stock assessment for the North Pacific Ocean. These life-history parameters should be considered to evaluate the population in the region and to develop better fishery management and conservation measures.

Mandibular condylar process remodeling in rats with different bite-altering devices.

The objective was to compare different dental splint models and materials for inducing abnormal loading on the gross morphology and histological appearance of the mandibular condylar processes of Sprague Dawley rats. Three different types of dental splints (resin molar, aluminum incisor, stainless-steel incisor) were placed unilaterally to induce occlusal perturbation for 4 weeks. At that time, mandibular condylar processes were assessed by gross appearance and histology. Quantitative measurements were also conducted on the hematoxylin and eosin images for condyle shape. The results showed that although the condylar cartilage was affected by all splint types, the resin molar splint was associated with the most extensive mandibular condylar process remodeling, which was primarily a slant (skewness) of the lateral aspect of the condylar process. Additionally, quantitative measurements on the histological specimens demonstrated that the split and tilt angle of the left (ipsilateral) condylar processes in the resin molar group (124.8 ± 12.7° and 104.1 ± 12.7°, respectively) increased significantly (p < 0.05) when compared to right (contralateral) condylar processes (104.7 ± 5.8°and 91.6 ± 4.4°, respectively). However, no changes were noted on the thickness of the fibrocartilage layer at medial, central, and lateral regions of the condylar process. Another major finding is the high variability of morphology of the naïve animals. Future studies will assess the impact of longer durations of splinting, age, and sex on the remodeling of the mandibular condylar process, allowing for the development of diagnostics and therapies.

Use of antioxidants and time of cold storage: effects over viability parameters and enzymatic levels in semen of rainbow trout (Oncorhynchus mykiss, Walbaum, 1792) / Uso de antioxidantes e tempo de armazenamento a frio: efeitos sobre parâmetros de viabilidade e níveis enzimáticos no sêmen da truta arco-íris (Oncorhynchus mykiss, Walbaum, 1792)

Abstract The cold storage of milt implies potentials alterations in its quality because the storage generates as main process, free radicals that produce spermatozoa membrane lipids damage with the consequent motility and fertilising capacity disruptions. To decrease the damage generated by free radicals the cells have antioxidant defences (proteins, enzymes, and low molecular weight substances). The objective of the present study evaluated the time storage effect and different antioxidants prepared in spermatic diluents on sperm viability of O. mykiss milt stored at 4°C. The two-way ANOVA denoted that the time storage and antioxidant influence have significant effects separated or combined on viability parameters (sperm motility and viability, proteins concentrations and superoxide dismutase enzymatic activity in seminal plasma). In contrast, only the storage time affected the fertilising capacity and catalase enzymatic activity in seminal plasma. The resulting analysis can conclude that the antioxidant presence improves the viability of cold stored milt, especially the transport conditions and the antioxidants allow the fecundity despite motility decrease.

Resumo O armazenamento a frio de leite implica potenciais alterações em sua qualidade, pois gera como processo principal radicais livres que provocam danos aos lipídios da membrana dos espermatozoides, com as consequentes alterações na motilidade e na capacidade de fertilização. Para diminuir os danos causados pelos radicais livres, as células têm defesas antioxidantes (proteínas, enzimas e substâncias de baixo peso molecular). O presente estudo avaliou o efeito do tempo de armazenamento e diferentes antioxidantes preparados em diluentes espermáticos no armazenamento de viabilidade de O. mykiss milt a 4°C. A ANOVA de duas vias denotou que o armazenamento no tempo e a influência antioxidante têm efeitos significativos separados ou combinados nos parâmetros de viabilidade (motilidade espermática, viabilidade espermática, concentrações de proteínas e atividade enzimática da superóxido dismutase no plasma seminal), enquanto apenas o tempo de armazenamento afetou a capacidade de fertilização e atividade enzimática da catalase no plasma seminal. A análise resultante pode concluir que a presença de antioxidante melhora a viabilidade do leite frio, especialmente as condições de transporte, e os antioxidantes permitem a fecundidade apesar da diminuição da motilidade.

Use of antioxidants and time of cold storage: effects over viability parameters and enzymatic levels in semen of rainbow trout (Oncorhynchus mykiss, Walbaum, 1792) / Uso de antioxidantes e tempo de armazenamento a frio: efeitos sobre parâmetros de viabilidade e níveis enzimáticos no sêmen da truta arco-íris (Oncorhynchus mykiss, Walbaum, 1792)

The cold storage of milt implies potentials alterations in its quality because the storage generates as main process, free radicals that produce spermatozoa membrane lipids damage with the consequent motility and fertilising capacity disruptions. To decrease the damage generated by free radicals the cells have antioxidant defences (proteins, enzymes, and low molecular weight substances). The objective of the present study evaluated the time storage effect and different antioxidants prepared in spermatic diluents on sperm viability of O. mykiss milt stored at 4°C. The two-way ANOVA denoted that the time storage and antioxidant influence have significant effects separated or combined on viability parameters (sperm motility and viability, proteins concentrations and superoxide dismutase enzymatic activity in seminal plasma). In contrast, only the storage time affected the fertilising capacity and catalase enzymatic activity in seminal plasma. The resulting analysis can conclude that the antioxidant presence improves the viability of cold stored milt, especially the transport conditions and the antioxidants allow the fecundity despite motility decrease.

O armazenamento a frio de leite implica potenciais alterações em sua qualidade, pois gera como processo principal radicais livres que provocam danos aos lipídios da membrana dos espermatozoides, com as consequentes alterações na motilidade e na capacidade de fertilização. Para diminuir os danos causados pelos radicais livres, as células têm defesas antioxidantes (proteínas, enzimas e substâncias de baixo peso molecular). O presente estudo avaliou o efeito do tempo de armazenamento e diferentes antioxidantes preparados em diluentes espermáticos no armazenamento de viabilidade de O. mykiss milt a 4°C. A ANOVA de duas vias denotou que o armazenamento no tempo e a influência antioxidante têm efeitos significativos separados ou combinados nos parâmetros de viabilidade (motilidade espermática, viabilidade espermática, concentrações de proteínas e atividade enzimática da superóxido dismutase no plasma seminal), enquanto apenas o tempo de armazenamento afetou a capacidade de fertilização e atividade enzimática da catalase no plasma seminal. A análise resultante pode concluir que a presença de antioxidante melhora a viabilidade do leite frio, especialmente as condições de transporte, e os antioxidantes permitem a fecundidade apesar da diminuição da motilidade.

Use of antioxidants and time of cold storage: effects over viability parameters and enzymatic levels in semen of rainbow trout (Oncorhynchus mykiss, Walbaum, 1792)

Abstract The cold storage of milt implies potentials alterations in its quality because the storage generates as main process, free radicals that produce spermatozoa membrane lipids damage with the consequent motility and fertilising capacity disruptions. To decrease the damage generated by free radicals the cells have antioxidant defences (proteins, enzymes, and low molecular weight substances). The objective of the present study evaluated the time storage effect and different antioxidants prepared in spermatic diluents on sperm viability of O. mykiss milt stored at 4°C. The two-way ANOVA denoted that the time storage and antioxidant influence have significant effects separated or combined on viability parameters (sperm motility and viability, proteins concentrations and superoxide dismutase enzymatic activity in seminal plasma). In contrast, only the storage time affected the fertilising capacity and catalase enzymatic activity in seminal plasma. The resulting analysis can conclude that the antioxidant presence improves the viability of cold stored milt, especially the transport conditions and the antioxidants allow the fecundity despite motility decrease.

Resumo O armazenamento a frio de leite implica potenciais alterações em sua qualidade, pois gera como processo principal radicais livres que provocam danos aos lipídios da membrana dos espermatozoides, com as consequentes alterações na motilidade e na capacidade de fertilização. Para diminuir os danos causados pelos radicais livres, as células têm defesas antioxidantes (proteínas, enzimas e substâncias de baixo peso molecular). O presente estudo avaliou o efeito do tempo de armazenamento e diferentes antioxidantes preparados em diluentes espermáticos no armazenamento de viabilidade de O. mykiss milt a 4°C. A ANOVA de duas vias denotou que o armazenamento no tempo e a influência antioxidante têm efeitos significativos separados ou combinados nos parâmetros de viabilidade (motilidade espermática, viabilidade espermática, concentrações de proteínas e atividade enzimática da superóxido dismutase no plasma seminal), enquanto apenas o tempo de armazenamento afetou a capacidade de fertilização e atividade enzimática da catalase no plasma seminal. A análise resultante pode concluir que a presença de antioxidante melhora a viabilidade do leite frio, especialmente as condições de transporte, e os antioxidantes permitem a fecundidade apesar da diminuição da motilidade.

Omnidirectional flat bands in chiral magnonic crystals.

The magnonic band structure of two-dimensional chiral magnonic crystals is theoretically investigated. The proposed metamaterial involves a three-dimensional architecture, where a thin ferromagnetic layer is in contact with a two-dimensional periodic array of heavy-metal square islands. When these two materials are in contact, an anti-symmetric exchange coupling known as the Dzyaloshinskii-Moriya interaction (DMI) arises, which generates nonreciprocal spin waves and chiral magnetic order. The Landau-Lifshitz equation and the plane-wave method are employed to study the dynamic magnetic behavior. A systematic variation of geometric parameters, the DMI constant, and the filling fraction allows the examination of spin-wave propagation features, such as the spatial profiles of the dynamic magnetization, the isofrequency contours, and group velocities. In this study, it is found that omnidirectional flat magnonic bands are induced by a sufficiently strong Dzyaloshinskii-Moriya interaction underneath the heavy-metal islands, where the spin excitations are active. The theoretical results were substantiated by micromagnetic simulations. These findings are relevant for envisioning applications associated with spin-wave-based logic devices, where the nonreciprocity and channeling of the spin waves are of fundamental and practical scientific interest.

Spermatological characteristics and effects of cryopreservation in Lebranche mullet spermatozoa (Mugil liza Valenciennes, 1836): First report of ultra-rapid freezing.

The present study investigated the spermatological characteristics of raw semen of Lebranche mullet (Mugil liza), namely pH, and sperm density, and motility; and subsequently evaluated the effects of different times of exposure to cryoprotectants, and the application of an ultra-rapid freezing protocol, on sperm motility and plasma membrane integrity. Semen samples were analyzed undiluted (control) and diluted 1:50 v/v in CF-HBSS + 10% Dimethyl sulfoxide + 30% Ethylene glycol + 94.58 gL-1 Trehalose dehydrate (n = 15). Two treatments - diluted semen samples in cryoprotective medium without ultra-rapid freezing (T1), and diluted semen in cryoprotective medium with ultra-rapid freezing (T2) - were evaluated at 0, 2, 4, 6 and 8 min. The frozen samples were thawed at 37ºC for 60 s. The spermatological characteristics recorded for the semen were: pH: 7.57 ± 0.21; sperm density: 30.4 ± 2.9 × 109 sperm mL-1; motility: 82 ± 4.9%. Sperm motility presented differences after 2 min exposure to cryoprotectants (70.0 ± 2.7%) and ultra-rapid freezing (66.5 ± 5.8%) compared to the control group (98.5 ± 1.9% and 98.5 ± 2.1%, respectively; p < 0.05). On the other hand, the plasma membrane integrity of the spermatozoa after 2 min exposure to cryoprotectants (64.0 ± 8.6%) and ultra-rapid freezing (62.5 ± 5.2%) presented no differences compared to the control group (69.5 ± 3.9% and 70.0 ± 3.5%, respectively p > 0.05); however, differences were observed in the parameters evaluated after longer exposure and cryopreservation times. This is the first report evaluating the effects of different times of exposure to cryoprotectants and direct ultra-rapid freezing in liquid nitrogen on Mugil liza sperm. Our results demonstrated the protocol of sperm ultra-freezing is safe within a time´s window of 2 min of exposure to cryoprotectants, after which a toxicity effect on sperm can be observed.

Lemmel syndrome: an extraordinary cause of obstructive jaundice-a case report.

Lemmel syndrome is created by a periampullary duodenal diverticulum. It is identified incidentally in 22% of the population, <10% present with jaundice, pain in the right flank and alteration of bilirubins, transaminases and/or pancreatic enzymes. Its diagnosis and therapeutic management can be carried out successfully with endoscopic retrograde cholangiopancreatography (ERCP), although some cases will require surgical management. We present the case of a 72-year-old male with recurrent obstructive jaundice and suspected choledocholithiasis managed with ERCP, identifying Lemmel syndrome. We recognize the importance of considering this extraordinary cause of obstructive jaundice in order to be able to make a diagnosis and offer timely treatment.

Community structure of benthic invertebrates in the Allipén River basin, North Patagonia, Araucania region (38º S, Chile) / Estrutura da comunidade de invertebrados bentônicos na bacia do rio Allipén, Patagônia Norte, Região da Araucanía (38º S, Chile)

One of the biological indicators most used to determine the health of a fluvial ecosystem are the benthic macroinvertebrates. The presence of recurrent species in a wide gradient of latitudes, dominates the biogeographic pattern of the benthic macroinvertebrates in Chilean fresh waters, nevertheless the knowledge on the communitarian ecology of these in the Chilean rivers continues to be scarce. Null models became a powerful statistical tool for describing the ecological mechanisms that drive the structure of an ecological community and the underlying patterns of diversity. The objective of this study was to determine the community structure of benthic invertebrates in the Allipén River by describing their composition, richness and abundance of species through richness models and null models based on presence/absence. The results reveal a high family richness and low diversity, three phyla, five classes, 11 orders and 28 families were identified in the study area during the four seasons of the year. The Arthropoda phylum was the most representative in abundance and richness. Regarding to richness, Trichoptera (7 families) and Diptera (6 families) followed by Ephemeroptera (3 families) were the orders that showed the greatest diversity of families, however, a low diversity with a H'≤ 1.5 nit was registered in the study area. We demonstrated through the null models, the randomization in the species associations corresponding to the three analyzed sites. The information provided here contributes to the understanding of the ecological patterns of the invertebrate communities in the Allipén River, establishing the basis for more complex ecological studies.

Um dos indicadores biológicos mais utilizados para determinar a saúde de um ecossistema fluvial são os macroinvertebrados bentônicos. A presença de espécies recorrentes em um amplo gradiente de latitudes domina o padrão biogeográfico dos macroinvertebrados bentônicos nas águas doces do Chile; no entanto, o conhecimento sobre a ecologia comunitária destes nos rios chilenos continua escasso. Os modelos nulos se tornaram uma poderosa ferramenta estatística para descrever os mecanismos ecológicos que orientam a estrutura de uma comunidade ecológica e os padrões subjacentes da diversidade. O objetivo deste estudo foi determinar a estrutura da comunidade de invertebrados bentônicos no rio Allipén, descrevendo sua composição, riqueza e abundância de espécies através de modelos de riqueza e modelos nulos baseados na presença / ausência. Os resultados revelam alta riqueza de espécies e baixa diversidade, sendo identificados três filos, cinco classes, 11 ordens e 28 famílias na área de estudo durante as quatro estações do ano. O filo de Arthropoda foi o mais representativo em abundância e riqueza. Em relação à riqueza, Trichoptera (7) e Diptera (6) seguidos por Ephemeroptera (3) foram as ordens que mostraram a maior diversidade de famílias, no entanto, uma baixa diversidade com H'≤ 1,5 nit foi registrada na área de estudo. Demonstramos através dos modelos nulos, a randomização nas associações de espécies correspondentes aos três locais analisados. As informações aqui fornecidas contribuem para a compreensão dos padrões ecológicos das comunidades de invertebrados no rio Allipén, estabelecendo a base para estudos ecológicos mais complexos.

Community structure of benthic invertebrates in the Allipén River basin, North Patagonia, Araucania region (38º S, Chile) / Estrutura da comunidade de invertebrados bentônicos na bacia do rio Allipén, Patagônia Norte, Região da Araucanía (38º S, Chile)

One of the biological indicators most used to determine the health of a fluvial ecosystem are the benthic macroinvertebrates. The presence of recurrent species in a wide gradient of latitudes, dominates the biogeographic pattern of the benthic macroinvertebrates in Chilean fresh waters, nevertheless the knowledge on the communitarian ecology of these in the Chilean rivers continues to be scarce. Null models became a powerful statistical tool for describing the ecological mechanisms that drive the structure of an ecological community and the underlying patterns of diversity. The objective of this study was to determine the community structure of benthic invertebrates in the Allipén River by describing their composition, richness and abundance of species through richness models and null models based on presence/absence. The results reveal a high family richness and low diversity, three phyla, five classes, 11 orders and 28 families were identified in the study area during the four seasons of the year. The Arthropoda phylum was the most representative in abundance and richness. Regarding to richness, Trichoptera (7 families) and Diptera (6 families) followed by Ephemeroptera (3 families) were the orders that showed the greatest diversity of families, however, a low diversity with a H'≤ 1.5 nit was registered in the study area. We demonstrated through the null models, the randomization in the species associations corresponding to the three analyzed sites. The information provided here contributes to the understanding of the ecological patterns of the invertebrate communities in the Allipén River, establishing the basis for more complex ecological studies.

Um dos indicadores biológicos mais utilizados para determinar a saúde de um ecossistema fluvial são os macroinvertebrados bentônicos. A presença de espécies recorrentes em um amplo gradiente de latitudes domina o padrão biogeográfico dos macroinvertebrados bentônicos nas águas doces do Chile; no entanto, o conhecimento sobre a ecologia comunitária destes nos rios chilenos continua escasso. Os modelos nulos se tornaram uma poderosa ferramenta estatística para descrever os mecanismos ecológicos que orientam a estrutura de uma comunidade ecológica e os padrões subjacentes da diversidade. O objetivo deste estudo foi determinar a estrutura da comunidade de invertebrados bentônicos no rio Allipén, descrevendo sua composição, riqueza e abundância de espécies através de modelos de riqueza e modelos nulos baseados na presença / ausência. Os resultados revelam alta riqueza de espécies e baixa diversidade, sendo identificados três filos, cinco classes, 11 ordens e 28 famílias na área de estudo durante as quatro estações do ano. O filo de Arthropoda foi o mais representativo em abundância e riqueza. Em relação à riqueza, Trichoptera (7) e Diptera (6) seguidos por Ephemeroptera (3) foram as ordens que mostraram a maior diversidade de famílias, no entanto, uma baixa diversidade com H'≤ 1,5 nit foi registrada na área de estudo. Demonstramos através dos modelos nulos, a randomização nas associações de espécies correspondentes aos três locais analisados. As informações aqui fornecidas contribuem para a compreensão dos padrões ecológicos das comunidades de invertebrados no rio Allipén, estabelecendo a base para estudos ecológicos mais complexos.

Community structure of benthic invertebrates in the Allipén River basin, North Patagonia, Araucania region (38º S, Chile)

Abstract One of the biological indicators most used to determine the health of a fluvial ecosystem are the benthic macroinvertebrates. The presence of recurrent species in a wide gradient of latitudes, dominates the biogeographic pattern of the benthic macroinvertebrates in Chilean fresh waters, nevertheless the knowledge on the communitarian ecology of these in the Chilean rivers continues to be scarce. Null models became a powerful statistical tool for describing the ecological mechanisms that drive the structure of an ecological community and the underlying patterns of diversity. The objective of this study was to determine the community structure of benthic invertebrates in the Allipén River by describing their composition, richness and abundance of species through richness models and null models based on presence/absence. The results reveal a high family richness and low diversity, three phyla, five classes, 11 orders and 28 families were identified in the study area during the four seasons of the year. The Arthropoda phylum was the most representative in abundance and richness. Regarding to richness, Trichoptera (7 families) and Diptera (6 families) followed by Ephemeroptera (3 families) were the orders that showed the greatest diversity of families, however, a low diversity with a H 1.5 nit was registered in the study area. We demonstrated through the null models, the randomization in the species associations corresponding to the three analyzed sites. The information provided here contributes to the understanding of the ecological patterns of the invertebrate communities in the Allipén River, establishing the basis for more complex ecological studies.

Resumo Um dos indicadores biológicos mais utilizados para determinar a saúde de um ecossistema fluvial são os macroinvertebrados bentônicos. A presença de espécies recorrentes em um amplo gradiente de latitudes domina o padrão biogeográfico dos macroinvertebrados bentônicos nas águas doces do Chile; no entanto, o conhecimento sobre a ecologia comunitária destes nos rios chilenos continua escasso. Os modelos nulos se tornaram uma poderosa ferramenta estatística para descrever os mecanismos ecológicos que orientam a estrutura de uma comunidade ecológica e os padrões subjacentes da diversidade. O objetivo deste estudo foi determinar a estrutura da comunidade de invertebrados bentônicos no rio Allipén, descrevendo sua composição, riqueza e abundância de espécies através de modelos de riqueza e modelos nulos baseados na presença / ausência. Os resultados revelam alta riqueza de espécies e baixa diversidade, sendo identificados três filos, cinco classes, 11 ordens e 28 famílias na área de estudo durante as quatro estações do ano. O filo de Arthropoda foi o mais representativo em abundância e riqueza. Em relação à riqueza, Trichoptera (7) e Diptera (6) seguidos por Ephemeroptera (3) foram as ordens que mostraram a maior diversidade de famílias, no entanto, uma baixa diversidade com H 1,5 nit foi registrada na área de estudo. Demonstramos através dos modelos nulos, a randomização nas associações de espécies correspondentes aos três locais analisados. As informações aqui fornecidas contribuem para a compreensão dos padrões ecológicos das comunidades de invertebrados no rio Allipén, estabelecendo a base para estudos ecológicos mais complexos.

Use of antioxidants and time of cold storage: effects over viability parameters and enzymatic levels in semen of rainbow trout (Oncorhynchus mykiss, Walbaum, 1792).

The cold storage of milt implies potentials alterations in its quality because the storage generates as main process, free radicals that produce spermatozoa membrane lipids damage with the consequent motility and fertilising capacity disruptions. To decrease the damage generated by free radicals the cells have antioxidant defences (proteins, enzymes, and low molecular weight substances). The objective of the present study evaluated the time storage effect and different antioxidants prepared in spermatic diluents on sperm viability of O. mykiss milt stored at 4°C. The two-way ANOVA denoted that the time storage and antioxidant influence have significant effects separated or combined on viability parameters (sperm motility and viability, proteins concentrations and superoxide dismutase enzymatic activity in seminal plasma). In contrast, only the storage time affected the fertilising capacity and catalase enzymatic activity in seminal plasma. The resulting analysis can conclude that the antioxidant presence improves the viability of cold stored milt, especially the transport conditions and the antioxidants allow the fecundity despite motility decrease.

Arsenic in Tissues and Prey Species of the Scalloped Hammerhead (Sphyrna lewini) from the SE Gulf of California.

The bioaccumulation of arsenic (As) in the muscle, liver, kidneys, and brain of the shark Sphyrna lewini was measured in 40 juvenile specimens from southeast Gulf of California. Additionally, the biomagnification factor was calculated through prey items from stomach contents of the analyzed specimens. The concentrations of As (mg kg-1, wet weight) were higher in the muscle (10.1 ± 0.3) and liver (9.4 ± 0.5) than in the brain (4.5 ± 0.3) and kidneys (4.2 ± 0.2), which may be attributed to the biological functions of each tissue. Positive correlations were found between the levels of As in muscle and liver with the biological parameters of S. lewini. Hammerhead sharks feed mainly of teleost fishes with low As values (Clupeidae fishes, 1.1 ± 0.5; Sciaenidae fishes, 1.0 ± 0.6; Scomber japonicus, 1.2 ± 0.6; and Etropus crossotus 2.1 ± 0.4) compared with the predator, indicating biomagnification. Inorganic arsenic (Asi) in muscle was estimated as 3% of the total As, although muscle consumption is unlikely to represent a risk (HQ < 1) in humans. Moreover, the probabilities of developing cancer were estimated as low (3.99 × 10-5 to 3.32 × 10-6). To avoid health risks related to As, a weekly ration must not exceed 69.3 and 484.8 g in children and adults, respectively.

Community structure of benthic invertebrates in the Allipén River basin, North Patagonia, Araucania region (38º S, Chile).

One of the biological indicators most used to determine the health of a fluvial ecosystem are the benthic macroinvertebrates. The presence of recurrent species in a wide gradient of latitudes, dominates the biogeographic pattern of the benthic macroinvertebrates in Chilean fresh waters, nevertheless the knowledge on the communitarian ecology of these in the Chilean rivers continues to be scarce. Null models became a powerful statistical tool for describing the ecological mechanisms that drive the structure of an ecological community and the underlying patterns of diversity. The objective of this study was to determine the community structure of benthic invertebrates in the Allipén River by describing their composition, richness and abundance of species through richness models and null models based on presence/absence. The results reveal a high family richness and low diversity, three phyla, five classes, 11 orders and 28 families were identified in the study area during the four seasons of the year. The Arthropoda phylum was the most representative in abundance and richness. Regarding to richness, Trichoptera (7 families) and Diptera (6 families) followed by Ephemeroptera (3 families) were the orders that showed the greatest diversity of families, however, a low diversity with a H'≤ 1.5 nit was registered in the study area. We demonstrated through the null models, the randomization in the species associations corresponding to the three analyzed sites. The information provided here contributes to the understanding of the ecological patterns of the invertebrate communities in the Allipén River, establishing the basis for more complex ecological studies.

The spotted ratfish Hydrolagus colliei as a potential biomonitor of mercury and selenium from deep-waters of the northern Gulf of California.

The purpose of this work was to use the deep-water chimaera Hydrolagus colliei to examine the bioaccumulation and availability of Hg and Se in its deep-water habitat; the Se:Hg molar ratio was calculated to establish baseline information of the species and its associated ecosystem. The organisms were collected from northern Gulf of California. Hg levels in muscle were higher than liver and the opposite pattern happened with Se concentrations. Female had total lengths and weights higher than male but there were not found differences between elements concentrations by sex. Hg in muscle was correlated with weight. Molar Se:Hg ratio in muscle was the lowest compared to the liver. It was hypothesized that Hg and Se uptake to H. colliei were by its feeding habits because is a dominant species component of the demersal ecosystem and that play and important functional role in the control of oceanic ecosystem structure and function.

Arsenic in the top predators sailfish (Istiophorus platypterus) and dolphinfish (Coryphaena hippurus) off the southeastern Gulf of California.

Distribution of arsenic (As) in tissues and gonads of the Indo-Pacific sailfish Istiophorus platypterus and the dolphinfish Coryphaena hippurus from the SE Gulf of California was evaluated. The bioaccumulation patterns of As were the same in the two species. In I. platypterus, As levels (mg kg-1, wet weight) were gonads (7.4 ± 1.1) > liver (3.1 ± 0.1) > kidney (2.7 ± 0.1) > muscle (1.6 ± 0.1); in C. hippurus, As (mg kg-1) levels were gonads (4.3 ± 0.6) > liver (3.2 ± 0.2) > kidney (2.3 ± 0.1) > muscle (1.2 ± 0.1). Differences in As distribution could be attributed to the biological functions of tissues. The hypothesis was confirmed that biomagnification was evidenced by the fact that As levels were lower in prey species than in predators. Intake of muscle from either fish did not represent a risk to humans if recommended portions a week are not exceeded, adults as much as 1802.4 g and 2454.1 g and children 257.5 and 350.6 g, for sailfish and dolphinfish, respectively. In addition, the likelihood of developing cancer due to consumption of edible tissues from either of these top predators was in the acceptable range (6.4 × 10-5 to 27.3 × 10-6 for a population that consumes 50 g of muscle in a week) but if a conservative combined slope factor is used the probabilities to develop bladder and lung cancer increments from 1.1 × 10-3 to 9.1 × 10-5.