Polydatin Beneficial Effects in Zebrafish Larvae Undergoing Multiple Stress Types.

Polydatin is a polyphenol, whose beneficial properties, including anti-inflammatory and antioxidant activity, have been largely demonstrated. At the same time, copper has an important role in the correct organism homeostasis and alteration of its concentration can induce oxidative stress. In this study, the efficacy of polydatin to counteract the stress induced by CuSO4 exposure or by caudal fin amputation was investigated in zebrafish larvae. The study revealed that polydatin can reduced the stress induced by a 2 h exposure to 10 µM CuSO4 by lowering the levels of il1b and cxcl8b.1 and reducing neutrophils migration in the head and along the lateral line. Similarly, polydatin administration reduced the number of neutrophils in the area of fin cut. In addition, polydatin upregulates the expression of sod1 mRNA and CAT activity, both involved in the antioxidant response. Most of the results obtained in this study support the working hypothesis that polydatin administration can modulate stress response and its action is more effective in mitigating the effects rather than in preventing chemical damages.

Light and Primary Production Shape Bacterial Activity and Community Composition of Aerobic Anoxygenic Phototrophic Bacteria in a Microcosm Experiment.

Phytoplankton is a key component of aquatic microbial communities, and metabolic coupling between phytoplankton and bacteria determines the fate of dissolved organic carbon (DOC). Yet, the impact of primary production on bacterial activity and community composition remains largely unknown, as, for example, in the case of aerobic anoxygenic phototrophic (AAP) bacteria that utilize both phytoplankton-derived DOC and light as energy sources. Here, we studied how reduction of primary production in a natural freshwater community affects the bacterial community composition and its activity, focusing primarily on AAP bacteria. The bacterial respiration rate was the lowest when photosynthesis was reduced by direct inhibition of photosystem II and the highest in ambient light condition with no photosynthesis inhibition, suggesting that it was limited by carbon availability. However, bacterial assimilation rates of leucine and glucose were unaffected, indicating that increased bacterial growth efficiency (e.g., due to photoheterotrophy) can help to maintain overall bacterial production when low primary production limits DOC availability. Bacterial community composition was tightly linked to light intensity, mainly due to the increased relative abundance of light-dependent AAP bacteria. This notion shows that changes in bacterial community composition are not necessarily reflected by changes in bacterial production or growth and vice versa. Moreover, we demonstrated for the first time that light can directly affect bacterial community composition, a topic which has been neglected in studies of phytoplankton-bacteria interactions.IMPORTANCE Metabolic coupling between phytoplankton and bacteria determines the fate of dissolved organic carbon in aquatic environments, and yet how changes in the rate of primary production affect the bacterial activity and community composition remains understudied. Here, we experimentally limited the rate of primary production either by lowering light intensity or by adding a photosynthesis inhibitor. The induced decrease had a greater influence on bacterial respiration than on bacterial production and growth rate, especially at an optimal light intensity. This suggests that changes in primary production drive bacterial activity, but the effect on carbon flow may be mitigated by increased bacterial growth efficiencies, especially of light-dependent AAP bacteria. Bacterial activities were independent of changes in bacterial community composition, which were driven by light availability and AAP bacteria. This direct effect of light on composition of bacterial communities has not been documented previously.

Correction to: Effects of Lactogen 13, a New Probiotic Preparation, on Gut Microbiota and Endocrine Signals Controlling Growth and Appetite of Oreochromis niloticus Juveniles.

The original version of this article unfortunately contained mistakes in Authors First name/Family name order. Please refer to this paper as Gioacchini et al. and not as Giorgia et al.

Effects of Lactogen 13, a New Probiotic Preparation, on Gut Microbiota and Endocrine Signals Controlling Growth and Appetite of Oreochromis niloticus Juveniles.

In the present study, Nile tilapia Oreochromis niloticus was used as experimental model to study the molecular effects of a new probiotic preparation, Lactogen 13 (Lactobacillus rhamnosus IMC 501® encapsulated with vegetable fat matrices by spray chilling and further indicated as probiotic microgranules), on growth and appetite during larval development. Probiotic microgranules were administered for 30 days to tilapia larvae starting from first feeding. Molecular analysis using high-throughput sequencing revealed that the probiotic could populate the gastrointestinal tract and modulate the microbial communities by significantly increasing the proportion of Lactobacillus as well as reducing the proportion of potential pathogens such as members of the Family Microbacteriaceae, Legionellaceae, and Weeksellaceae. Morphometric analysis evidenced that body weight and total length significantly increased after probiotic treatment. This increase coincided with the modulation of genes belonging to the insulin-like growth factors (igfs) system and genes involved on myogenesis, such as myogenin, and myogenic differentiation (myod). Alongside the improvement of growth, an increase of feed intake was evidenced at 40 days post-fertilization (dpf) in treated larvae. Gene codifying for signals belonging to the most prominent systems involved in appetite regulation, such as neuropeptide y (npy), agouti-related protein (agrp), leptin, and ghrelin were significantly modulated. These results support the hypothesis that gastrointestinal (GI) microbiota changes due to probiotic administration modulate growth and appetite control, activating the endocrine system of tilapia larvae.

Aplicação de ultra-som terapêutico na cartilagem de crescimento do coelho / Application of therapeutic ultrasound to the rabbit growth plate

A aplicação do ultra-som terapêutico é tradicionalmente contra-indicada nas adjacências da cartilagem de crescimento, pelo temor de que possa provocar algum efeito lesivo. Como não há confirmação experimental ou clínica de que esse efeito possa ocorrer, foi objetivo deste trabalho investigar uma possível ação do ultra-som terapêutico aplicado nas adjacências da cartilagem de crescimento. Foram usados coelhos albinos da raça Nova Zelândia, jovens, fêmeas, distribuídos em dois grupos, sendo que em ambos foi aplicado ultra-som nas adjacências da cartilagem de crescimento proximal da tíbia direita e a tíbia esquerda mantida como controle. A freqüência foi de 1,0MHz, pulso de 2:8 e intensidade de 0,5W/cm2, aplicados durante cinco minutos em dez dias consecutivos. No grupo 1 (20 coelhas), os animais foram sacrificados três dias após o término do período da aplicação do ultra-som e a cartilagem de crescimento foi avaliada morfometricamente do ponto de vista histológico e com microscopia de luz ultravioleta para o estudo da neoformação óssea marcada com tetraciclina. No grupo 2 (10 coelhas), os animais foram mantidos vivos até o final do crescimento e realizada a morfometria macroscópica pelo alinhamento frontal dos joelhos e região proximal da tíbia, pelo uso de radiografias e medidas diretas nas peças. A morfometria, tanto da espessura global da cartilagem, como das suas camadas e a contagem de células, não mostrou diferença entre os lados. A avaliação do crescimento ósseo também não mostrou diferenças. Da mesma forma, os dados obtidos pela morfometria macroscópica foram semelhantes entre os lados. Como resultado final, não foram observadas diferenças entre o lado tratado e lado controle ou constatado algum efeito lesivo do ultra-som.