Soluble Factors Associated with Denervation-induced Skeletal Muscle Atrophy.

Skeletal muscle tissue has the critical function of mechanical support protecting the body. In addition, its functions are strongly influenced by the balanced synthesis and degradation processes of structural and regulatory proteins. The inhibition of protein synthesis and/or the activation of catabolism generally determines a pathological state or condition called muscle atrophy, a reduction in muscle mass that results in partial or total loss of function. It has been established that many pathophysiological conditions can cause a decrease in muscle mass. Skeletal muscle innervation involves stable and functional neural interactions with muscles via neuromuscular junctions and is essential for maintaining normal muscle structure and function. Loss of motor innervation induces rapid skeletal muscle fiber degeneration with activation of atrophy-related signaling and subsequent disassembly of sarcomeres, altering normal muscle function. After denervation, an inflammation stage is characterized by the increased expression of pro-inflammatory cytokines that determine muscle atrophy. In this review, we highlighted the impact of some soluble factors on the development of muscle atrophy by denervation.

Intermittent fasting associated with aerobic exercise improves oxidative parameters and causes muscle damage without compromising the performance of Wistar rats.

OBJECTIVES: The aim of this study was to` investigate the effects of intermittent fasting (IF) and the possible association with aerobic exercise on performance, oxidative, biochemical, and somatic parameters of Wistar rats. METHODS: Forty rats were randomized into the following groups: sedentary (SC) and trained (TC) controls, sedentary intermittent fasting (SIF), and trained intermittent fasting (TIF). The rats were subjected to IF for 15 h every day and aerobic exercise lasting 30 min, five times a week, at a speed of 15 m/min for 4 wk. Performance tests were performed at the beginning and end of the protocol. Glucose and insulin tolerance, somatic parameters, lipidogram, leptin, insulin, malondialdehyde, antioxidant capacity, C-reactive protein, alpha acid glycoprotein, creatine kinase, lactate dehydrogenase, and muscle histology were analyzed. RESULTS: The trained groups had similar performance and significantly improved performance at the end of the experiment. TIF showed lower body weight (-16 g), lean mass (22.49%), homeostatic model assessment for insulin resistance (29%), and lactate dehydrogenase (48%), and higher malondialdehyde (53%) and antioxidant capacity (75%) than the TC group. The SIF and TIF groups showed a fiber area reduction and positivity marking for tumor necrosis factor-α in the muscles. CONCLUSION: Although IF associated with aerobic exercise improved antioxidant capacity caused damage to muscle fibers and lean mass loss, it did not change the performance of the rats.

White epaxial muscle aerobic and anaerobic potential and muscle fiber structure in surface and cave morphotypes of the Mexican cavefish (Astyanax mexicanus).

Proper muscle function and muscle fiber structures that match the environmental demands of organisms are imperative to their success in any ecosystem. The Mexican cavefish, Astyanax mexicanus, has two morphotypes: an obligate cave-dwelling form that lives in thermally insulated caves and an O2 poor environment, and a surface form that lives in a more thermally variable, but O2 rich river environment. As environment can determine physiological adaptations, it is of interest to compare the aerobic and anaerobic metabolic profiles of white muscle metabolism in both morphotypes of this species, as well as their muscle structures. Here, we used white muscle of both morphotypes of the Mexican cavefish to determine citrate synthase (CS) activity as a measure of aerobic potential, and lactate concentration as a measure of anaerobic potential at three different chronic acclimation temperatures (14°C, 25°C, and 31°C). By examining aerobic and anaerobic potential in both morphs, we sought to link environmental thermal flexibility to muscle metabolism. We found that the surface morphotype had higher CS activity and lower lactate concentration, suggesting an overall more efficient usage of aerobic metabolism; whereas the cave morphotype showed lower CS activity and higher lactate concentration, suggesting a stronger reliance on anaerobic pathways. We also measured white muscle histological variables that have been previously linked to whole-animal metabolism: fiber diameter, number of nuclei per mm of fiber and myonuclear domain (MND) of both morphotypes at 25°C to examine cell-level differences in muscle morphology. However, we found no differences in fiber diameter, number of nuclei per mm of fiber or MND between the two morphotypes. Thus, although the cellular morphology is similar in these species, the environmental differences in the evolution of the two morphs has led to differences in their metabolic profiles.

An Early and Sustained Inflammatory State Induces Muscle Changes and Establishes Obesogenic Characteristics in Wistar Rats Exposed to the MSG-Induced Obesity Model.

The model of obesity induced by monosodium glutamate cytotoxicity on the hypothalamic nuclei is widely used in the literature. However, MSG promotes persistent muscle changes and there is a significant lack of studies that seek to elucidate the mechanisms by which damage refractory to reversal is established. This study aimed to investigate the early and chronic effects of MSG induction of obesity upon systemic and muscular parameters of Wistar rats. The animals were exposed to MSG subcutaneously (4 mg·g-1 b.w.) or saline (1.25 mg·g-1 b.w.) daily from PND01 to PND05 (n = 24). Afterwards, in PND15, 12 animals were euthanized to determine the plasma and inflammatory profile and to assess muscle damage. In PND142, the remaining animals were euthanized, and samples for histological and biochemical analyses were obtained. Our results suggest that early exposure to MSG reduced growth, increased adiposity, and inducted hyperinsulinemia and a pro-inflammatory scenario. In adulthood, the following were observed: peripheral insulin resistance, increased fibrosis, oxidative distress, and a reduction in muscle mass, oxidative capacity, and neuromuscular junctions, increased fibrosis, and oxidative distress. Thus, we can conclude that the condition found in adult life and the difficulty restoring in the muscle profile is related to the metabolic damage established early on.

Muscle fiber conduction velocity in situ revisited: A new approach to an ancient technique.

The aim of this study was to measure the muscle fiber conduction velocity (MFCV) in situ in the tibialis anterior muscle in healthy subjects. A total of 36 subjects matched for age and sex were studied. The MFCV was measured with a concentric needle by intramuscular monopolar needle electrical activation at a distance of 50 mm. The mean consecutive difference (MCD) of <5 µs was obtained after a median of 62 muscle fiber action potentials (MFAPs), confirming a direct muscle fiber activation. The measuring latency was at the median point of ascending depolarizing line of the MFAP. The calculated MFCV from 784 MFAPs was 4.10 ± 0.66 m/s, 3.99 ± 0.57 for female subjects (95%, 2.85 to 5.13), and 4.20 ± 0.73 for male subjects (95%, 2.74 to 5.67). The MFCV was 5.22% faster in male subjects. The calculated fast-to-slow MFCV ratio (F/S ratio) was 1.47 for female subjects (95%, 1.27 to 2.54) and 1.67 for male subjects (95%, 1.31 to 3.74). Aging significantly increased the F/S ratio. As the MFCVs mainly depend on the muscle diameter, their assessment is a quick and helpful tool for estimating it. Its variability by the F/S ratio is also a powerful tool in the follow-up of some neuromuscular disorders.

Tipos de fibras de los músculos intrínsecos laríngeos de seres humanos: una revisión de la literatura / Fiber types in human intrinsic laryngeal muscles: a literature review

El estudio de las fibras musculares permite comprender con mejor detalle la composición de los músculos y sus características funcionales. Además, facilita la aplicación de programas de entrenamiento y rehabilitación basados en las vías energéticas que regulan la contracción muscular. Su estudio generalmente va unido al análisis de las cadenas pesadas de miosina (MyHC), las que informan sobre las características y propiedades funcionales del músculo. El objetivo de este trabajo fue sintetizar la evidencia científica disponible sobre la distribución de fibras musculares y de isoformas de cadenas pesadas de miosina de los músculos intrínsecos de la laringe de seres humanos. Se realizó una revisión sistemática de la literatura mediante el análisis de artículos encontrados en las bases de datos PubMed, EBSCOHost y SciELO. Los hallazgos informan sobre la existencia de fibras tónicas lentas y tipo I, II, IIA y IIX/IIB. Además, se reconoce la presencia de las isoformas MyHC-I, MyHC-IIA, MyHC-IIX, MyHC-Fetal, MyHC-L y MyHC-IIB. En conclusión, los músculos intrínsecos de la laringe presentan una mezcla de fibras y de isoformas de MyHC lentas y rápidas,la que obedece a adaptaciones y cambios evolutivos que han permitido, por ejemplo, las características fonatorias que presenta la voz del ser humano.

The study of muscle fibers allows the composition of muscles and their functional characteristics to be understood in greaterdetail. In addition, it makes it possible to applytraining and rehabilitation programs based on the energypathways that regulatemuscle contraction. Studying muscle fibers is generally associated withthe analysis of myosin heavy chains (MHC) which provide information on the functional characteristics and properties of muscles. The objective of this study was to synthesize the available scientific evidence onthe distribution of muscle fibers and myosin heavy chain isoforms present in the intrinsic laryngeal muscles of human beings. A systematic reviewof the literature was carried outand articles found on PubMed, EBSCOHost,and SciELOwere analyzed.The findings showthe presenceof slow-tonic, type I, type II, type IIA, and type IIX/IIB fibers. Additionally,isoforms MHC-I, MHC-IIA, MHC-IIX, MHC-Fetal, MHC-L, and MHC-IIB canbe found. In conclusion, intrinsic laryngeal muscles are composed ofa combination of slow and fast fibers and MHC isoforms, derived from evolutionary adaptations and changes which have given way, among other things, to the phonetic characteristics ofthe human voice.

Compensatory growth of Nile tilapia fingerlings subjected to food restriction and re-feeding at low temperatures / Crescimento compensatório de alevinos de tilápia-do-Nilo submetidos à restrição alimentar e realimentação em temperaturas amenas

This study aims to investigate the effect of different periods of fasting and re-feeding on compensatory responses in Nile tilapia fingerlings and the frequency of muscle fiber distribution. A total of 108 Nile tilapia fingerlings with initial weight of 1.64 ± 0.41 g and mean initial length of 3.60 ± 0.39 cm were used for 55 days. The fish were distributed in a water recirculation system in a completely randomized design with three treatments and four replications: Control - CO - (fish fed until apparent satiation throughout the experimental period); fasting 10 - J10 - (fish fed to apparent satiation for 15 days, followed by 10 days of fasting and re-feeding to satiation for 30 days); and fasting 15 - J15 - (fish fed to apparent satiation for 15 days, followed by 15 days of fasting and re-feeding to satiation for 25 days). Fish from the J15 treatment showed unsatisfactory results in terms of productive performance (p<0.05), such as lower final weight, apparent feed conversion, protein efficiency ratio, and survival, while fish from the J10 treatment achieved the same results as those animals kept in the CO treatment with the exception of the variables of relative weight gain and feed intake. Furthermore, food restriction directly influenced the growth of muscle fibers with a diameter smaller than 20 µm (p<0.05), and fish from the J15 treatment had the lowest frequency of fibers in this diameter class. Therefore, this study concludes that food restriction in short periods (10 days) and at low temperatures can present a compensatory growth, as they alter the process of hyperplasia and hypertrophy of muscle fibers without affecting the morphology of the fibers; however, 15 days of fasting under low temperatures do not compensate for growth and delays the hypertrophic growth of muscle fibers.(AU)

O objetivo do presente estudo é investigar o efeito de diferentes períodos de jejum alimentar e realimentação nas respostas compensatórias em alevinos de tilápias-do-Nilo, e a frequência de distribuição das fibras musculares. Foram utilizados 108 alevinos de tilápia-do-Nilo com peso inicial de 1,64±0,41 g e comprimento inicial médio de 3,60 ± 0,39 cm, durante um período de 55 dias. Os peixes foram distribuídos em um sistema de recirculação de água, em delineamento inteiramente casualizado com três tratamentos e quatro repetições: Controle - CO - (peixes alimentados até a saciedade aparente durante todo período experimental); jejum 10 - J10 - (peixes alimentados até a saciedade aparente por 15 dias, seguidos de 10 dias de jejum e realimentação até a saciedade por 30 dias); e jejum 15 - J15 - (peixes alimentados até a saciedade aparente por 15 dias, seguidos de 15 dias de jejum e realimentação até a saciedade por 25 dias). Os peixes do tratamento J15 apresentaram resultados insatisfatórios de desempenho produtivo (p<0,05), como menor peso final, conversão alimentar aparente, taxa de eficiência proteica e sobrevivência, enquanto os peixes do tratamento J10, atingiram os mesmos resultados daqueles animais mantidos no tratamento CO, com exceção das variáveis de ganho em peso relativo e do consumo de ração. A restrição alimentar influenciou diretamente no crescimento das fibras musculares com diâmetro menor que 20 µm (p<0,05), sendo que os peixes do tratamento J15 apresentaram a menor frequência de fibras nesta classe de diâmetro. Conclui-se que a restrição alimentar em curtos períodos (10 dias) e em temperaturas amenas podem apresentar um crescimento compensatório, alterando o processo de hiperplasia e hipertrofia das fibras musculares, sem afetar a morfologia das fibras, entretanto, 15 dias de jejum e sob temperaturas amenas não ocorre uma compensação no crescimento e atrasa o crescimento hipertrófico das fibras musculares.(AU)

Genomic Predictors of Brisk Walking Are Associated with Elite Sprinter Status.

Brisk walkers are physically more active, taller, have reduced body fat and greater physical fitness and muscle strength. The aim of our study was to determine whether genetic variants associated with increased walking pace were overrepresented in elite sprinters compared to controls. A total of 70 single-nucleotide polymorphisms (SNPs) previously identified in a genome-wide association study (GWAS) of self-reported walking pace in 450,967 European individuals were explored in relation to sprinter status. Genotyping of 137 Russian elite sprinters and 126 controls was performed using microarray technology. Favorable (i.e., high-speed-walking) alleles of 15 SNPs (FHL2 rs55680124 C, SLC39A8 rs13107325 C, E2F3 rs4134943 T, ZNF568 rs1667369 A, GDF5 rs143384 G, PPARG rs2920503 T, AUTS2 rs10452738 A, IGSF3 rs699785 A, CCT3 rs11548200 T, CRTAC1 rs2439823 A, ADAM15 rs11264302 G, C6orf106 rs205262 A, AKAP6 rs12883788 C, CRTC1 rs11881338 A, NRXN3 rs8011870 G) were identified as having positive associations with sprinter status (p < 0.05), of which IGSF3 rs699785 survived correction for multiple testing (p = 0.00004) and was linked (p = 0.042) with increased proportions of fast-twitch muscle fibers of m. vastus lateralis in physically active men (n = 67). Polygenic analysis revealed that individuals with ≥18 favorable alleles of the 15 SNPs have an increased odds ratio of being an elite sprinter when compared to those with ≤17 alleles (OR: 7.89; p < 0.0001). Using UK Biobank data, we also established the association of 14 favorable alleles with low BMI and fat percentage, 8 alleles with increased handgrip strength, and 7 alleles with increased height and fat-free mass. In conclusion, we have identified 15 new genetic markers associated with sprinter status.

Selenium supplementation levels and sources in postlarvae Nile tilapia diet / Níveis de suplementação e Fontes de Selênio na Dieta de pós-larvas de Tilápia do Nilo

Fish larviculture exert great influence in the subsequent phases, in which nutrition is a basic prerequisite for success. Therefore, when it is in an intensified production system, it promotes the limitation of some minerals, making it necessary to supplement selenium in diets for post-larvae. The objective of this study was to evaluate selenium levels and sources in post-larvae Nile tilapia diets on muscle performance and histology. A total of 1,260 post-larvae with an initial average weight of 0.010 g were used, distributed in a completely randomized design in a factorial scheme with four supplementation levels (0.6; 0.9; 1.2 and 1.5 mg of Se/Kg) and two sources (sodium selenite and selenium yeast), plus the negative control, with 35 post-larvae Nile tilapia used per experimental unit. The physical-chemical parameters of water quality were within those recommended for tilapia cultivation. Feed consumption (p < 0.05) and hepatosomatic index (p < 0.05) were affected by the source used. Effects of supplemented selenium levels and sources were not observed for the other performance variables. Higher values for final height, final width, specific development rate and protein efficiency rate were found (p < 0.05) when comparing the control diet with diets containing the sodium selenite source. No effects on muscle fiber morphometry were observed (p > 0.05) in the studied variables. It is concluded that 0.6 mg of selenium in the diet, regardless of the source used, met the mineral requirement for post-larvae Nile tilapia.(AU)

A larvicultura de peixes exerce grande influência nas fases subsequentes, onde a nutrição é um prérequisito básico para o sucesso. Portanto, quando está em sistema de produção intensificada, promove a limitação de alguns minerais, sendo necessária a suplementação de selênio em dietas para pós-larvas. Objetivou-se avaliar níveis e fontes de selênio em dietas para pós-larvas de tilápia do Nilo, sobre o desempenho e histologia muscular. Utilizou-se 1260 pós-larvas, peso médio inicial 0,010 g, distribuídas em delineamento inteiramente casualizado, em esquema fatorial com quatro níveis de suplementação (0,6; 0,9; 1,2 e 1,5 mg/kg de Selênio) e duas fontes (Selenito de sódio e Selênio levedura), mais o controle negativo, utilizou-se 35 pós-larvas por unidade experimental. Os parâmetros físico-químicos de qualidade da água, apresentaram-se dentro do recomendado para tilápias. O consumo de ração (p < 0001) e índice hepatossomático (p < 0,05), foram afetados pela fonte utilizada. Para as demais variáveis de desempenho, não foram observados efeitos dos níveis e das fontes de selênio suplementadas. Quando comparada dieta controle as dietas contendo a fonte selenito de sódio verificou-se (p < 0,05) maiores altura final, largura final, taxa de desenvolvimento especifico e taxa de eficiência proteica. Não foram evidenciados (p > 0,05) efeitos sobre morfometria das fibras musculares nas variáveis estudadas. Conclui-se que 0,6mg de selênio na dieta, independente da fonte utilizada atendeu a necessidade do mineral para pós-larvas de tilápia do Nilo.(AU)

Skeletal muscle type-specific mitochondrial adaptation to high-fat diet relies on differential autophagy modulation.

In obesity, skeletal muscle mitochondrial activity changes to cope with increased nutrient availability. Autophagy has been proposed as an essential mechanism involved in the regulation of mitochondrial metabolism. Still, the contribution of autophagy to mitochondrial adaptations in skeletal muscle during obesity is unknown. Here, we show that in response to high-fat diet (HFD) feeding, distinct skeletal muscles in mice exhibit differentially regulated autophagy that may modulate mitochondrial activity. We observed that after 4 and 40 weeks of high-fat diet feeding, OXPHOS subunits and mitochondrial DNA content increased in the oxidative soleus muscle. However, in gastrocnemius muscle, which has a mixed fiber-type composition, the mitochondrial mass increased only after 40 weeks of HFD feeding. Interestingly, fatty acid-supported mitochondrial respiration was enhanced in gastrocnemius, but not in soleus muscle after a 4-week HFD feeding. This increased metabolic profile in gastrocnemius was paralleled by preserving autophagy flux, while autophagy flux in soleus was reduced. To determine the role of autophagy in this differential response, we used an autophagy-deficient mouse model with partial deletion of Atg7 specifically in skeletal muscle (SkM-Atg7+/- mice). We observed that Atg7 reduction resulted in diminished autophagic flux in skeletal muscle, alongside blunting the HFD-induced increase in fatty acid-supported mitochondrial respiration observed in gastrocnemius. Remarkably, SkM-Atg7+/- mice did not present increased mitochondria accumulation. Altogether, our results show that HFD triggers specific mitochondrial adaptations in skeletal muscles with different fiber type compositions, and that Atg7-mediated autophagy modulates mitochondrial respiratory capacity but not its content in response to an obesogenic diet.

Expression of calpastatin isoforms in three skeletal muscles of Angus steers and their association with fiber type composition and proteolytic potential.

This study aimed to evaluate the expression of calpastatin (CAST) isoforms and their potential associations with fiber type composition (%RA), calpastatin activity (CA) and myofibril fragmentation index (MFI) in three muscles with known differences in tenderness (infraspinatus, triceps brachii and semitendinosus) of Angus steers. Expression of total CAST (CAST-T) and CAST isoforms I, II, III (2-3) and III (2-4) (including or not exon 3) was evaluated by qRT-PCR. CAST expression and CA were significantly higher and MFI was lower in semitendinosus, the muscle with the highest %RA of IIX fibers. Differential expression of isoforms defined the variability in CAST-T among muscles. Semitendinosus had a higher expression of isoforms II and III (2-3), but lower expression of III (2-4) compared to the other two muscles. Relative expression of isoforms II and III that were defined by promoter preference linked to alternative splicing, seem to be the main factors explaining differences in CAST expression and ultimately in MFI among muscles.

La rigidez cadavérica, el espasmo cadavérico y tipos de fibras musculares / The cadaveric rigidity, the cadaveric spasm and types of muscle fibers

La rigidez cadavérica (rigor mortis) es un proceso no muy bien comprendido por la mayoría de los médicos. El conocimiento de la intimidad del proceso de la rigidez cadavérica es de vital importancia ya que es una de las variables que junto con las livideces (livor mortis) y la temperatura (algor mortis) del cadáver ayudan a determinar el cronotanatodiagnóstico, tanatocronodiagnóstico o intervalo postmortal del período inmediato de la muerte. Para entender el mecanismo de la rigidez y el espasmo cadavérico es preciso hacer un repaso de la contracción muscular fisiológica en el vivo. Hay que tener presente que el tipo de fibra muscular predominante modificará las características de la contracción muscular fisiológica en el vivo, y también la rigidez y el espasmo cadavérico. (AU)

The cadaveric rigidity (rigor mortis) is a process which is not very well understood by the majority of the doctors. The knowledge of the intimacy of the cadaveric stiffness process is of vital importance since it is one of the variables that, as well as the postmortem lividity (livor mortis) and the body temperature post mortem (algor mortis) help determine the chronotanatodiagnostic, tanatochronodiagnostic or postmortal interval of the immediate period of death. In order to understand the mechanism of stiffness and cadaveric spasm, it is necessary to review the physiological muscle contraction in vivo. We should keep in mind that the predominant type of muscle fiber will modify the characteristics of physiological muscle contraction in vivo, as well as stiffness and cadaveric spasm. (AU)

Glutamine supplementation versus functional overload in extensor digitorum longus muscle hypertrophy

Background Glutamine levels directly associate with total protein content in cultured skeletal muscle cells, whereas glutamine supplementation enhances skeletal muscle mass in catabolic experimental conditions. Methods We compared the effect of glutamine administration on Extensor Digitorum Longus muscle (EDL) weight, fiber cross-sectional area (CSA), contractile activity, and protein metabolism signaling with a functional overload-induced skeletal muscle hypertrophy protocol. Results Glutamine supplementation raised the predominance of EDL muscle fibers with CSA between 1001 and 2000 μm2 (49.7 %), the p-4E-BP1/total 4E-BP1 ratio, and the effect of overload on resistance to fatigue. The proportion of the EDL muscle fiber CSA distribution for the combination of both treatments was similar to that induced by overload or glutamine separately; 54.3 % muscle fibers with CSA between 1001 and 2000 μm². Glutamine supplementation did not markedly affect the changes induced by overload on protein synthesis signaling pathways, except for a further increase of the p-4E-BP1/total 4E-BP1 ratio. Conclusions The effect of glutamine on EDL muscle fiber CSA distribution and protein synthesis signaling mimicked the response to overload. The association of glutamine and overload induced EDL muscle hypertrophy further increased the resistance to fatigue.

Characterization of Breast Meat Collected from Spent Lohmann Brown Layers in Comparison to Commercial Ross Broilers

The objective of this study was to compare characteristics and properties of breast meat from spent Lohmann Brown layers (SP, 90 weeks old, n = 24) and those of commercial broilers (BR, 6 weeks old, n = 24). The breasts of both SP and BR were collected from a local processing plant, vacuum-packed in a plastic bag, and stored at -18ºC until further analyses. The SP showed a greater water-holding capacity, tougher and chewier texture (p 0.05). Both raw and cooked SP breasts comprised the greater total collagen but lower soluble collagen than those of BR (p 0.05). Muscle fibers of the SP, observed under scanning electron microscope, were small, with average fiber diameter of 37.85±1.40 m, densely packed and surrounded by complex networks of connective tissue. The lower myofibril fragmentation index and alkaline-soluble protein fractions of the SP (p 0.05) suggested lesser degree of postmortem fragmentation and protein denaturation in SP compared to BR. Based on differential scanning calorimetry, multiple endothermic transitions were observed in both raw BR and SP breast samples. While BR thermograms comprise five transitions at 57.7ºC, 64.2ºC, 67.6ºC, 72.3ºC and 77.6ºC with total H of 15.31 J/g dry meat, the SP samples exhibited four transitions at 55.1ºC, 62.1ºC, 70.5ºC and 77.7ºC and total H of 17.62 J/g dry meat. Overall, the findings indicated that cooked meat toughness of SP was attributed by the high total and heat-stable collagen content, densely packing of small muscle fibers, and the superior myofibril integrity.(AU)

Aspectos qualitativos da carcaça e carne ovina são modificados com uso de aspersão de água / Qualitative aspects of the carcass and ovine meat are modified with the use of water spray

O objetivo desta pesquisa foi investigar os aspectos qualitativos da carne ovina, após a submissão ou não de 20 carcaças à aspersão de água. O experimento foi realizado em delineamento em bloco ao acaso, com dois tratamentos com dez carcaças cada e dez repetições. As carcaças foram submetidas e não submetidas à aspersão de água por 10 horas consecutivas em câmara fria. As análises de qualidade instrumental da carne foram determinadas nos músculos Longissimus thoracis et lumborum (LTL), e ocorreram em dois períodos distintos, inicialmente dentro do período de 24 horas post mortem e após 7 meses de congelamento não industrial. Foram analisados pH, coloração de carne e gordura subcutânea, perda por cocção, capacidade de retenção de água, atividade de água, comprimento de sarcômero, força de cisalhamento e medidas corporais da carcaça. Além destas, foram incluídas a mensurações subjetivas de cor e marmoreio e a análise microbiológica (Escherichia coli). Após as análises, foi observado que nas carcaças aspergidas, o músculo LTL modificou o croma dentro de 24 horas post mortem e a tonalidade após o congelamento (7 meses). Além destes, houve aumento na contagem microbiológica (5,9 x 10¹ e 4,3 x 10² UFC/cm²) e no rendimento frigorífico (48,77; 46,28 kg). Contudo, houve maior perda no resfriamento (4,87; 3,27%). Para carcaças não aspergidas, houve maior declínio de pH 2 horas post mortem (pH 6,9) e menor pH final após 24 horas (pH 5,6). Entretanto, após o congelamento não houve diferença significativa (p<0,05) entre os tratamentos. Para as outras análises não foi constatada diferença significativa. O uso ou não de aspersão por 10 horas consecutivas em carcaças ovinas, promove alterações indesejadas nos aspectos qualitativos da carcaça e carne. Neste sentido, não recomendamos o uso prolongado (10 horas) de aspersão em carcaças ovinas.(AU)

The objective of this research was to investigate the qualitative aspects of sheep meat, after the submission or not of 20 carcasses to water spray. The experiment was carried out in a randomized block design, with two treatments with ten carcasses each and ten replicates. The carcasses were submitted and not submitted to water sprinkling for 10 consecutive hours in a cold chamber. Instrumental meat quality analyzes were performed on the Longissimus thoracis et lumborum (LTL) muscles, and occurred in two distinct periods, initially within the 24-hour post-mortem period and after 7 months of non-industrial freezing. The pH, meat and subcutaneous fat staining, cooking loss, water retention capacity, water activity, sarcomere length, shear force and body measurements of the carcass were analyzed. In addition to these, subjective color and marbling measurements and microbiological analysis (Escherichia coli) were included. After the analysis, it was observed that sputum carcasses, LTL muscle modified chroma within 24 hours post mortem and tonality after freezing (7 months). In addition, there was an increase in the microbiological count (5.9 x 10¹ and 4.3 x 10² UFC / cm²) and in the refrigerator yield (48.77, 46.28 kg). However, there was greater loss in cooling (4.87, 3.27%). And in for unprosted carcasses, there was a greater decline in pH 2 hours post mortem (pH 6.9) and lower final pH after 24 hours (pH 5.6). However, after freezing there was no significant difference (p<0.05) between treatments. For the other analyzes, no significant difference was found. The use or not of spraying for 10 consecutive hours in ovine carcasses, promotes unwanted changes in the qualitative aspects of the carcass and meat. In this sense, we do not recommend prolonged use (10 hours) of spraying on ovine carcasses.(AU)

Aspectos qualitativos da carcaça e carne ovina são modificados com uso de aspersão de água / Qualitative aspects of the carcass and ovine meat are modified with the use of water spray

O objetivo desta pesquisa foi investigar os aspectos qualitativos da carne ovina, após a submissão ou não de 20 carcaças à aspersão de água. O experimento foi realizado em delineamento em bloco ao acaso, com dois tratamentos com dez carcaças cada e dez repetições. As carcaças foram submetidas e não submetidas à aspersão de água por 10 horas consecutivas em câmara fria. As análises de qualidade instrumental da carne foram determinadas nos músculos Longissimus thoracis et lumborum (LTL), e ocorreram em dois períodos distintos, inicialmente dentro do período de 24 horas post mortem e após 7 meses de congelamento não industrial. Foram analisados pH, coloração de carne e gordura subcutânea, perda por cocção, capacidade de retenção de água, atividade de água, comprimento de sarcômero, força de cisalhamento e medidas corporais da carcaça. Além destas, foram incluídas a mensurações subjetivas de cor e marmoreio e a análise microbiológica (Escherichia coli). Após as análises, foi observado que nas carcaças aspergidas, o músculo LTL modificou o croma dentro de 24 horas post mortem e a tonalidade após o congelamento (7 meses). Além destes, houve aumento na contagem microbiológica (5,9 x 10¹ e 4,3 x 10² UFC/cm²) e no rendimento frigorífico (48,77; 46,28 kg). Contudo, houve maior perda no resfriamento (4,87; 3,27%). Para carcaças não aspergidas, houve maior declínio de pH 2 horas post mortem (pH 6,9) e menor pH final após 24 horas (pH 5,6). Entretanto, após o congelamento não houve diferença significativa (p<0,05) entre os tratamentos. Para as outras análises não foi constatada diferença significativa. O uso ou não de aspersão por 10 horas consecutivas em carcaças ovinas, promove alterações indesejadas nos aspectos qualitativos da carcaça e carne. Neste sentido, não recomendamos o uso prolongado (10 horas) de aspersão em carcaças ovinas.

The objective of this research was to investigate the qualitative aspects of sheep meat, after the submission or not of 20 carcasses to water spray. The experiment was carried out in a randomized block design, with two treatments with ten carcasses each and ten replicates. The carcasses were submitted and not submitted to water sprinkling for 10 consecutive hours in a cold chamber. Instrumental meat quality analyzes were performed on the Longissimus thoracis et lumborum (LTL) muscles, and occurred in two distinct periods, initially within the 24-hour post-mortem period and after 7 months of non-industrial freezing. The pH, meat and subcutaneous fat staining, cooking loss, water retention capacity, water activity, sarcomere length, shear force and body measurements of the carcass were analyzed. In addition to these, subjective color and marbling measurements and microbiological analysis (Escherichia coli) were included. After the analysis, it was observed that sputum carcasses, LTL muscle modified chroma within 24 hours post mortem and tonality after freezing (7 months). In addition, there was an increase in the microbiological count (5.9 x 10¹ and 4.3 x 10² UFC / cm²) and in the refrigerator yield (48.77, 46.28 kg). However, there was greater loss in cooling (4.87, 3.27%). And in for unprosted carcasses, there was a greater decline in pH 2 hours post mortem (pH 6.9) and lower final pH after 24 hours (pH 5.6). However, after freezing there was no significant difference (p<0.05) between treatments. For the other analyzes, no significant difference was found. The use or not of spraying for 10 consecutive hours in ovine carcasses, promotes unwanted changes in the qualitative aspects of the carcass and meat. In this sense, we do not recommend prolonged use (10 hours) of spraying on ovine carcasses.

Characterization of Breast Meat Collected from Spent Lohmann Brown Layers in Comparison to Commercial Ross Broilers

The objective of this study was to compare characteristics and properties of breast meat from spent Lohmann Brown layers (SP, 90 weeks old, n = 24) and those of commercial broilers (BR, 6 weeks old, n = 24). The breasts of both SP and BR were collected from a local processing plant, vacuum-packed in a plastic bag, and stored at -18ºC until further analyses. The SP showed a greater water-holding capacity, tougher and chewier texture (p 0.05). Both raw and cooked SP breasts comprised the greater total collagen but lower soluble collagen than those of BR (p 0.05). Muscle fibers of the SP, observed under scanning electron microscope, were small, with average fiber diameter of 37.85±1.40 m, densely packed and surrounded by complex networks of connective tissue. The lower myofibril fragmentation index and alkaline-soluble protein fractions of the SP (p 0.05) suggested lesser degree of postmortem fragmentation and protein denaturation in SP compared to BR. Based on differential scanning calorimetry, multiple endothermic transitions were observed in both raw BR and SP breast samples. While BR thermograms comprise five transitions at 57.7ºC, 64.2ºC, 67.6ºC, 72.3ºC and 77.6ºC with total H of 15.31 J/g dry meat, the SP samples exhibited four transitions at 55.1ºC, 62.1ºC, 70.5ºC and 77.7ºC and total H of 17.62 J/g dry meat. Overall, the findings indicated that cooked meat toughness of SP was attributed by the high total and heat-stable collagen content, densely packing of small muscle fibers, and the superior myofibril integrity.

Morphometry of pectoral muscle fiber and intestinal villi of Calidris pusilla during the wintering period in Brazil / Morfometria da fibra muscular peitoral e das vilosidades intestinais de Calidris pusilla durante o período de invernada no Brasil

Migration is an event observed in several animals, such as shorebirds moving between the northern and southern hemispheres, during breeding and wintering intervals. Morphophysiological adaptations are necessary to allow the maintenance of migratory cycles and, therefore, studies with this focus can help clarify biological aspects related to migration. We analyzed the morphology variation in pectoral muscles and intestinal mucosa of Calidris pusilla, during different phases of the wintering period on the coast of Brazil. Fragments of pectoral muscles and duodenal were collected, fixed and processed for histology according to standard procedure, from specimens captured in a locality on the Brazilian coast. Modifications were found in the measured parameters among the three phases of wintering, arrival in Brazil (October, mid-period), January and departure to the Northern Hemisphere - May. The registered structural dynamism characterizes the growth of flight musculature and intestinal changes related to nutrition. Such changes occur temporarily due to the activities of preparation and migration between the northern and southern hemispheres.(AU)

A migração é um evento observado em vários animais, como as aves limícolas que se deslocam entre os hemisférios norte e sul, durante os intervalos de reprodução e invernada. Adaptações morfofisiológicas são necessárias para permitir a manutenção dos ciclos migratórios e, portanto, estudos com esse enfoque podem ajudar a esclarecer aspectos biológicos relacionados à migração. Analisamos a variação morfológica nos músculos peitorais e mucosa intestinal de Calidris pusilla, durante diferentes fases do período de invernada no litoral brasileiro. Fragmentos de músculos peitorais e duodenais foram coletados, fixados e processados ​​para histologia de acordo com o procedimento padrão, a partir de espécimes capturados na localidade da costa brasileira. O dinamismo estrutural registrado caracteriza o crescimento da musculatura de vôo e as alterações intestinais relacionadas à nutrição. As mudanças nos parâmetros medidos entre as três fases do inverno, chegada ao Brasil (outubro, meio período), janeiro e saída para o Hemisfério Norte. Tais mudanças ocorrem temporariamente devido às atividades de preparação e migração entre os hemisférios norte e sul.(AU)

Use of zebrafish ( Danio rerio ) embryos as a model to assess effects of mercury on developing skeletal muscle: a morphometric and immunohistochemical study / Uso de embriones de pez cebra ( Danio rerio ) como modelo para evaluar los efectos del mercurio en el desarrollo del músculo esquelético: un estudio morfométrico e inmunohistoquímico

Exposure to mercury in the environment continues to be a significant worldwide concern, especially for developing embryos and fetuses. While extensive research effort has focused on the effects of mercury on the developing nervous system, much less is known concerning adverse effects of mercury on other organ systems, including the development of skeletal muscle. We exposed developing zebrafish embryos to a range of concentrations of mercuric chloride (100 to 400 µg/liter or ppb) and compared them to control embryos (0 µg/L mercuric chloride). Embryos were examined at 48 hours post fertilization (hpf) for morphometry and morphological deformities of skeletal muscle fibers in the trunk and tail. Embryos exposed to 400 ppb mercuric chloride showed decreased trunk and tail areas compared to control embryos. A dose-dependent reduction in muscle fiber length was observed, and exposure to all concentrations of mercuric chloride used in this study resulted in decreased muscle fiber immunohistochemical staining with anti-myosin antibodies. Irregular muscle fiber diameters, twisted muscle fibers, and degenerated muscle fibers were observed in sections of embryos stained with eosin at the higher exposure concentrations. Evidence presented in this study suggests that exposure to even low concentrations of mercuric chloride adversely affects skeletal muscle fiber development or muscle fiber integrity, or both.

La exposición al mercurio en el medio ambiente sigue siendo una preocupación mundial importante, especialmente para el desarrollo de embriones y fetos. Si bien un amplio esfuerzo de investigación se ha centrado en los efectos del mercurio en el sistema nervioso en desarrollo, se sabe mucho menos sobre los efectos adversos en otros sistemas orgánicos, incluido el desarrollo del músculo esquelético. Expusimos embriones de pez cebra en desarrollo a un rango de concentraciones de cloruro de mercurio (100 a 400 mg / l o ppb) y los comparamos con embriones de control (0 mg / L de cloruro de mercurio). Los embriones se examinaron a las 48 horas después de la fertilización (HPF) pararealizar la morfometría y verificar las deformidades morfológicas de las fibras del músculo esquelético en el tronco y la cola. Los embriones expuestos a 400 ppb de cloruro de mercurio mostraron una disminución de las áreas del tronco y la cola en comparación con los embriones de control. Se observó una reducción dependiente de la dosis en la longitud de la fibra muscular, y la exposición a todas las concentraciones de cloruro de mercurio utilizadas en este estudio, dio como resultado una tinción inmunohistoquímica de fibra muscular disminuida con anticuerpos anti-miosina. Se observaron diámetros irregulares de fibras musculares, fibras musculares retorcidas y fibras musculares degeneradas en secciones de embriones teñidos con eosina en las concentraciones de exposición más altas. La evidencia presentada en este estudio sugiere que la exposición incluso a bajas concentraciones de cloruro mercúrico afecta negativamente el desarrollo de la fibra del músculo esquelético o la integridad de la fibra muscular, o ambas.

Morphometry of pectoral muscle fiber and intestinal villi of Calidris pusilla during the wintering period in Brazil / Morfometria da fibra muscular peitoral e das vilosidades intestinais de Calidris pusilla durante o período de invernada no Brasil

Migration is an event observed in several animals, such as shorebirds moving between the northern and southern hemispheres, during breeding and wintering intervals. Morphophysiological adaptations are necessary to allow the maintenance of migratory cycles and, therefore, studies with this focus can help clarify biological aspects related to migration. We analyzed the morphology variation in pectoral muscles and intestinal mucosa of Calidris pusilla, during different phases of the wintering period on the coast of Brazil. Fragments of pectoral muscles and duodenal were collected, fixed and processed for histology according to standard procedure, from specimens captured in a locality on the Brazilian coast. Modifications were found in the measured parameters among the three phases of wintering, arrival in Brazil (October, mid-period), January and departure to the Northern Hemisphere - May. The registered structural dynamism characterizes the growth of flight musculature and intestinal changes related to nutrition. Such changes occur temporarily due to the activities of preparation and migration between the northern and southern hemispheres.(AU)

A migração é um evento observado em vários animais, como as aves limícolas que se deslocam entre os hemisférios norte e sul, durante os intervalos de reprodução e invernada. Adaptações morfofisiológicas são necessárias para permitir a manutenção dos ciclos migratórios e, portanto, estudos com esse enfoque podem ajudar a esclarecer aspectos biológicos relacionados à migração. Analisamos a variação morfológica nos músculos peitorais e mucosa intestinal de Calidris pusilla, durante diferentes fases do período de invernada no litoral brasileiro. Fragmentos de músculos peitorais e duodenais foram coletados, fixados e processados ​​para histologia de acordo com o procedimento padrão, a partir de espécimes capturados na localidade da costa brasileira. O dinamismo estrutural registrado caracteriza o crescimento da musculatura de vôo e as alterações intestinais relacionadas à nutrição. As mudanças nos parâmetros medidos entre as três fases do inverno, chegada ao Brasil (outubro, meio período), janeiro e saída para o Hemisfério Norte. Tais mudanças ocorrem temporariamente devido às atividades de preparação e migração entre os hemisférios norte e sul.(AU)