Terminal heat stress in Indian mustard (Brassica juncea L.): Variation in dry matter accumulation, stem reserve mobilization, carbohydrates translocation and their correlation with seed yield

The rapeseed mustard is one of the most important sources of edible oil in India and contributes 28.6% in total oilseed production. The mustard growing areas in India are experiencing the vast diversity in the agro climatic conditions. Here, we studied forty-nine advanced breeding lines of Brassica juncea L. for two consecutive years (2016-18) to examine the variations in the remobilization of assimilates from flowering to maturity stage and their contribution to seed filling under stressed environment. Further, we investigated the impact of high temperature on dry matter accumulation and partitioning from source to sink in Brassica germplasm. The synchronization between the seed filling stage and the onset of heat spell is critical event that determines the overall yield. Imbalances caused due to miss-matching of above events created hindrance in source-sink translocation, thus resulted in yield losses. Amount of remobilized dry matter, remobilization efficiency and remobilization percentage increased significantly, while the dry matter accumulation, total carbohydrates content and seed yield per plant declined in the late sown genotypes during both crop seasons. Reduced accumulation of photo assimilates under stress and higher sink demand resulted in more number of shriveled seeds leading to yield depression. The higher remobilization efficiency in late sown genotypes was strongly associated with dry matter at flowering that consequently tended to affect the final seed weight. This study will provide insights for better understanding of source-sink relationships in Indian mustard under heat stress and the differential remobilization efficiencies in the advanced breeding lines.

Effects of immobilization and remobilization on the ankle joint in Wistar rats

A sprained ankle is a common musculoskeletal sports injury and it is often treated by immobilization of the joint. Despite the beneficial effects of this therapeutic measure, the high prevalence of residual symptoms affects the quality of life, and remobilization of the joint can reverse this situation. The aim of this study was to analyze the effects of immobilization and remobilization on the ankle joint of Wistar rats. Eighteen male rats had their right hindlimb immobilized for 15 days, and were divided into the following groups: G1, immobilized; G2, remobilized freely for 14 days; and G3, remobilized by swimming and jumping in water for 14 days, performed on alternate days, with progression of time and a series of exercises. The contralateral limb was the control. After the experimental period, the ankle joints were processed for microscopic analysis. Histomorphometry did not show any significant differences between the control and immobilized/remobilized groups and members, in terms of number of chondrocytes and thickness of the articular cartilage of the tibia and talus. Morphological analysis of animals from G1 showed significant degenerative lesions in the talus, such as exposure of the subchondral bone, flocculation, and cracks between the anterior and mid-regions of the articular cartilage and the synovial membrane. Remobilization by therapeutic exercise in water led to recovery in the articular cartilage and synovial membrane of the ankle joint when compared with free remobilization, and it was shown to be an effective therapeutic measure in the recovery of the ankle joint.

Remobilização por alongamento estático cíclico em músculo sóleo de ratos imobilizados em encurtamento / Remobilization by cycle static stretching in soleus muscle of rats immobilized in shortening position

A fibra muscular tem grandes propriedades plásticas, respondendo a diferentes estímulos com o aumento ou diminuição de sua massa, comprimento e número de sarcômeros em série. O objetivo deste estudo foi analisar os efeitos do alongamento passivo estático em 3 séries diárias de 30 s e da remobilização livre, por um período de duas semanas, no músculo sóleo de ratos imobilizado em posição de encurtamento. Para isso, foram utilizados 12 ratos (Wistar) divididos em 2 grupos: G1 (n=6) - músculo sóleo esquerdo (MSE) imobilizado e solto na gaiola (GIS); G2 (n=6) - MSE imobilizado e alongado diariamente (GIA). Foram comparadas as variações encontradas entre o MSE e o MSD (direito) de cada grupo. As variáveis foram: peso muscular, comprimento muscular, número de sarcômeros em série e comprimento de sarcômeros. Os resultados das variáveis analisadas, comparando o MSE com o MSD foram: peso muscular: GIS=-23,16 por cento, (p=0,0007), GIA-32,43 por cento (p=0,0008); comprimento muscular: GIS=-5,47 por cento (p=0,0120); GIA=-9,99 por cento (p=0,0034); número de sarcômeros em série: GIS=-15,42 por cento (p=0,0047); GIA=-8,08 por cento (p=0,0008); comprimento do sarcômero: GIS=11,16 por cento (p=0,0142); GIA=-1,92 por cento (p=0,3783). Através desses resultados, pode-se concluir que nem o alongamento, nem a remobilização livre promovem a restauração na estrutura dos músculos esqueléticos submetidos à imobilização prolongada.

Muscle fibers have great plastic properties, responding to different stimuli with their weight increase or reduction, length and serial sarcomere number. The aim of this study was to analyze the static passive stretching in 3 daily bouts of 30 s and the free remobilization effects for two weeks, in the soleus muscle of rats immobilized in shortening position. For this purpose, 12 rats (Wistar) were used and divided in 2 groups: G1 (n=6) - left soleus muscle (LSM) immobilized and free in the cage (GIF); G2 (n=6) - LSM immobilized and stretched daily (GIS). The variations found between the LSM and RSM (right) of each group have been compared. The variables were: soleus muscle weight, length, serial sarcomeres number and sarcomere length. The results comparing LSM with RSM were: muscle weight: GIF=-23.16 percent, (p=0.0007), GIS-32.43 percent (p=0.0008); muscle length: GIF=-5.47 percent (p=0.0120); GIS=-9.99 percent (p=0.0034); serial sarcomere number: GIF=-15.42 percent (p=0.0047); GIS=-8.08 percent (p=0.0008); sarcomere length: GIF=11.16 percent (p=0.0142); GIS=-1.92 percent (p=0.3783). It can be concluded through these results that neither the stretching nor the free remobilization promotes restoration in the skeletal muscles structure submitted to prolonged immobilization.

Estimulação elétrica neuromuscular em cães com atrofia muscular induzida / Neuromuscular electric stimulation in dogs with induced muscle atrophy

Empregou-se a estimulação elétrica neuromuscular (EENM) de baixa freqüência no músculo quadríceps femoral de cães com atrofia induzida e avaliou-se a ocorrência de ganho de massa nessa musculatura. Foram utilizados oito cães com pesos entre 15 e 30kg, distribuídos aleatoriamente em dois grupos denominados de I ou controle e II ou tratado. A articulação femorotibiopatelar esquerda foi imobilizada por 30 dias pelo método de transfixação percutânea tipo II, com retirada de aparelho de imobilização após esse período. Decorridas 48 horas da remoção, foi realizada a EENM nos cães do grupo II, cinco vezes por semana, com intervalo de 24 horas cada sessão, pelo período de 60 dias. Foram avaliadas a circunferência da coxa, a goniometria do joelho, a análise clínica da marcha, as enzimas creatina-quinase (CK) e aspartato-amino-transferase (AST) e a morfometria das fibras musculares em cortes transversais do músculo vasto lateral colhido mediante biópsia muscular. A EENM foi empregada no músculo quadríceps femoral na freqüência de 50Hz, duração de pulso de 300 milisegundos e relação de tempo on/off de 1:2. Quanto à morfometria das fibras do músculo vasto lateral, no grupo tratado houve aumento significativo (P<0,05) da área transversal aos 90 dias em relação ao dia zero. A EENM de baixa freqüência ocasiona hipertrofia do músculo vasto lateral em cães após a imobilização rígida temporária da articulação do joelho.

Low frequency neuromuscular electrical stimulation (NMES) was used on the femoral quadriceps of dogs with induced muscular atrophy and the occurrence of gain in mass in these muscles was evaluated. Eight dogs from 15 to 30kg were randomly distributed in two groups named I, or control; and II, or treated. For the induction of muscular atrophy, the left femoral-tibial-patellar joint was immobilized for 30 days by percutaneous transfixation type II. After 30 days, the immobilization device was removed. The NMES treatment began 48 hours after the removal of the immobilization device of the dogs of group II, and it was carried out five times per week with an interval of 24 hours between each session, for 60 days. The following parameters were measured: thigh circumference, goniometry of the knee, clinical gait analysis, creatine kinase (CK) and aspartate aminotransferase (AST) enzymes, and morphometry of the muscular fibers in transversal cuts of the vastus lateralis muscle collected through muscular biopsy. The NMES was applied on the femoral quadriceps at a frequency of 50 Hz, with pulse duration of 300 milliseconds, and the on/off time was at a proportion of 1:2. Regarding the morphometry of the vastus lateralis fibers, a significant increase (P<0.05) in the transversal area of the treated group at 90 days was observed when compared with that identified at the time of immobilization. Thus, it can be concluded that low frequency NMES brings about hypertrophy of the vastus lateralis muscle in dogs after temporary rigid immobilization of the knee joint.