Hyperplastic and hypertrophic growth of lateral muscle in blackspot seabream Pagellus bogaraveo from hatching to juvenile

To understand better the growth mechanisms in the economically important fish Pagellus bogaraveo, in terms of muscle fibre hyperplasia v. hypertrophy, the lateral muscle of this fish was studied morphometrically from hatching to juvenile comparing rostral and caudal locations. Fish were sampled at 0, 5, 23, 40, 70, 100, 140 and 180 days. Fibre types were first identified by succinate dehydrogenase (SDH) and immunostaining with a polyclonal antibody against fish slow myosin (4-96). Morphometric variables were then measured in transverse body sections, at both post-opercular and post-anal locations, to estimate the following variables: total muscle area [A (muscle)], total fibre number [N (fibres)], fibre number per unit area of muscle [N-A (fibres, muscle)] and cross-sectional fibre area [a (fibres)] of the two main muscle fibre types (white and red). Overall, growth throughout the various stages resulted from increases both in the number and in the size of muscle fibres, paralleled by an expansion of the [A (muscle)]. Nonetheless, that increase was not significant between 0-5 days on one hand and 100-140 days, on the other hand. On the contrary, the [N-A (fibres, muscle)] declined as the body length increased. Analysis of the muscle growth kinetics suggested that, within the important time frame studied, hyperplasia gave the main relative contribution to the increase of white muscle [A (white muscle)], whereas red muscle [A (red muscle)] mainly grew by hypertrophy, with both phenomena occurring at a faster pace posteriorly in the body. Finally, when comparing rostral and caudal locations, a greater [N (fibres)] and [A (muscle)] of the posterior white and red fibres were the consistent features. It was also observed that the proportion of the cross-sectional area of the myotomal muscle comprised of white muscle was greater in the anterior part of the fish

Expression of the myosin light chains 1, 2 and 3 in the muscle of blackspot seabream (Pagellus bogaraveo, Brunnich), during development

Previous studies on the histochemistry and immunoreactivity of fibres in lateral muscle of blackspot seabream indicated that there is a developmental transition in the composition of myofibnllar proteins, which presumably reflects changes in contractile function as the fish grows We hypothesize that the phenomenon underscores age and spatial differences in the expression of myosin light chains (MLC), not studied yet in this species In this study, we examined selected stages in the post-hatching development of the muscle of blackspot seabream hatching (0 days), mouth opening (5 days), weaning (40 days) and juveniles (70 days) The spatial expression of embryonic MLC 1 (MLC1), 2 (MLC2) and 3 (MLC3) was studied by in situ hybndization Overall, MLC expression patterns were overlapping and restricted to the fast muscle At hatching and mouth opening, all MLC types were highly expressed throughout the musculature in fast muscle The expression levels in fast muscle remained high until weaning when germinal zones appeared on the dorsal and ventral areas The germinal zones were characterized by small-diameter fast fibres with high levels of MLC expression This pattern persisted up to day 70, when the germinal zones disappeared and expression of MLCs was observed only in the smaller cells of the fast muscle mosaic These results support our hypothesis and, together with previous imuno-and histochemistry results, allow a better understanding of the mechanism of muscle differentiation and growth in fish beyond larval stages, and form- the basis for further comparative and experimental studies with this economically relevant specie

Dietary protein content influences both growth and size distribution of anterior and posterior muscle fibres in juveniles of Pagellus bogaraveo (Brunnich)

Muscle cellularity was studied in Pagellus bogaraveo juveniles fed on diets with different protein contents. Measured in transversal body sections, at both post-opercular and post-anal locations, the morphometric variables estimated were: total muscle area (A), total number of fibres (N), number of fibres per unit area of muscle (N(A)) and cross-sectional fibre area ((a) over bar), of the two main muscle fibre types. At the end of the experiment fish fed on diets having more than 40% of protein displayed significantly higher body weight. Fish fed on protein-rich diets exhibited greater (a) over bar and N. For fish fed on 30 and 50% protein diets the morphometric parameters measured grew linearly with the fish weight. High-protein diets favoured muscle hyperplasia. When comparing rostral and caudal locations, a greater N and a smaller (a) over bar of posterior red fibres were the consistent differences found-a fact, to our knowledge, so far unreported for fish

Modulação da proliferação fibroblástica e da resposta inflamatória pela terapia a laser de baixa intensidade no processo de reparo tecidual Modulation of fibroblast proliferation and inflammatory response by low-intensity laser therapy in tissue repair process

FUNDAMENTOS: Ao longo dos anos, diversos estudos têm sido realizados para compreender o processo de reparo tecidual, bem como os possíveis efeitos da terapia a laser no processo de cicatrização de feridas. OBJETIVOS: Investigar o comportamento de feridas cutâneas provocadas na região dorsal de ratos Wistar (Rattus norvegicus), que foram submetidos ao tratamento com laser de baixa intensidade, com 3,8 J/cm² de dosagem, 15mW de potência e tempo de aplicação de 15s. MÉTODOS: Os animais (n = 12) foram divididos em dois grupos, um controle e outro tratado com laser. Foram realizadas, no grupo tratado, três aplicações (imediatamente após o ato cirúrgico, 48 horas e sete dias após a realização das feridas cirúrgicas). Dez dias após o ato cirúrgico foram colhidas amostras das lesões de ambos os grupos para realização de estudo histopatológico e histomorfométrico. RESULTADOS: Foram evidenciados aumentos da neovascularização e da proliferação fibroblástica, e diminuição da quantidade de infiltrado inflamatório nas lesões cirúrgicas submetidas à terapia com laser. CONCLUSÃO: Os resultados em conjunto sugerem que a terapia a laser de baixa intensidade é um método eficaz no processo de modulação da reparação tecidual, contribuindo significativamente para a cicatrização tecidual mais rápida e organizada.<br>BACKGROUND: Several studies have been performed to understand the tissue repair process as well as the possible effects of laser therapy in wound healing. OBJECTIVES: To study the behavior of skin wounds induced in the dorsal region of Wistar rats (Rattus norvegicus), which were submitted to the low-intensity laser therapy at 3.8 J/cm² dosage, 15mW potency, during 15 seconds. MATERIAL AND METHODS: The animals (n=12) were divided into two groups - control and laser-treated. The latter comprised three applications (immediately after surgery, 48 hours and 7 days after induction of surgical wounds). Ten days after surgery samples of the wounds were collected and submitted to histopathological and histomorphometric studies. RESULTS: Neovascularization, fibroblast proliferation and reduced inflammatory infiltrate in surgical wound submitted to laser therapy were demonstrated. CONCLUSION: Taken together, the results suggest that low-intensity laser therapy is an effective method to modulate tissue repair, thus significantly contributing to a faster and more organized healing process