Sugarcane root length density and distribution from root intersection counting on a trench-profile

Root length density (RLD) is a critical feature in determining crops potential to uptake water and nutrients, but it is difficult to be measured. No standard method is currently available for assessing RLD in the soil. In this study, an in situ method used for other crops for studying root length density and distribution was tested for sugarcane (Saccharum spp.). This method involved root intersection counting (RIC) on a Rhodic Eutrudox profile using grids with 0.05 x 0.05 m and modeling RLD from RIC. The results were compared to a conventional soil core-sampled method (COR) (volume 0.00043 m³). At four dates of the cropping season in three tillage treatments (plowing soil, minimum tillage and direct planting), with eight soil depths divided in 0.1 m soil layer (between 0-0.6 and 1.6-1.8 m) and three horizontal distances from the row (0-0.23, 0.23-0.46 and 0.46-0.69 m), COR and RIC methods presented similar RLD results. A positive relationship between COR and RIC was found (R² = 0.76). The RLD profiles considering the average of the three row distances per depth obtained using COR and RIC (mean of four dates and 12 replications) were close and did not differ at each depth of 0.1 m within a total depth of 0.6 m. Total RLD between 0 and 0.6 m was 7.300 and 7.100 m m-2 for COR and RIC respectively. For time consumption, the RIC method was tenfold less time-consuming than COR and RIC can be carried out in the field with no need to remove soil samples. The RLD distribution in depth and row distance (2-D variability) by RIC can be assessed in relation to the soil properties in the same soil profiles. The RIC method was suitable for studying these 2-D (depth and row distance in the soil profile) relationships between soil, tillage and root distribution in the field.A densidade de comprimento de raízes (DCR) é uma característica importante para determinar o potencial de absorção de água e nutrientes das plantas, mas é difícil de ser medida. Nenhum método padrão está atualmente disponível para avaliar a DCR no solo. Neste estudo, um método in situ usado em outras culturas para estudo da densidade de comprimento e distribuições das raízes foi testado para a cana-de-açúcar (Saccharum spp.). O método envolveu contagem de intersecções de raízes (CIR) no perfil de um Latossolo Vermelho eutroférrico, usando grade com quadrículas de 0.05 x 0.05 m, modelizando a DCR a partir da CIR. Os resultados foram comparados com o método do trado cilíndrico (TRA) (volume de 0.00043 m-3). Em quatro épocas durante o ciclo em três manejos do solo (plantio convencional, cultivo mínimo e plantio direto), em oito profundidades divididas a cada 0.1 m (entre 0 - 0.6 e 1.6 - 1.8 m) e três distâncias horizontais em relação à linha de plantio (0 - 0.23, 0.23 - 0.46 e 0.46 - 0.69 m), os métodos TRA e CIR apresentaram resultados de DCR similares. Encontrou-se positiva entre TRA e CIR (R² = 0,76). As DCRs nos perfis, considerando as médias das três distâncias da linha por profundidade, obtida utilizando-se de TRA e CIR (média de quatro datas e 12 repetições), foram próximas e não diferiram a cada 0.1 m de profundidade até 0.6 m de profundidade. A DCR total entre 0 e 0.6 m foi de 7.300 e 7.100 m m-2 para TRA e CIR, respectivamente. Para o tempo de realização, o método CIR foi 10 vezes mais rápido do que TRA e o método CIR pode ser realizado no campo, sem necessidade de remover amostras de solo. A distribuição da DCR em profundidade e distância da linha (variabilidade 2D) pelo método CIR pode ser avaliada em relação às propriedades do solo nos mesmos perfis do solo. O método CIR foi apropriado para estudos dessas relações 2D (profundidade e distância da linha no perfil do solo) entre solo, manejo e distribuição de raízes no campo

Physical performance and physical activity in the later stage post-stroke

Aims: The overall purpose of this thesis was to increase knowledge about physical performance and activity in the later stage post-stroke by measuring walking performance in different environments coupled to muscle strength, cardiorespiratory fitness evaluation and self-reported physical activity. Methods: The studies reported in the thesis included a total of 83 subjects with prior stroke living in the community and 144 clinically healthy subjects from the same area. In study I, walking performance (speed and distance) were assessed indoors and outdoors in 36 subjects after stroke, who were divided into slow and fast walkers. Study II evaluated the relationship between muscle strength in the lower extremities and walking performance (speed and distance) in 41 subjects after stroke and 144 healthy reference participants. The correlation between maximal exercise capacity measured during one-legged bicycling test and the 6-minute walking test (6MWT) were examined in 34 subjects after stroke in study III. The influences of motor function and balance on the 6MWT were also investigated. Study IV compared self-reported physical activity in 70 persons with stroke compared to 141 healthy subjects and explored the relationship between this and physical measures. Results: There were no differences in the short and long distance walking test for the slow walkers between different environments. However, those who walked faster walked a longer distance in the outdoor setting. The actual distance walked in the 6MWT was significantly shorter than the distance predicted by 30-meter walking test (30mWT) for both groups in the indoor environment. The parametric model provided evidence for a non-linear relationship between walking performance and strength index. The model explained 37% of the variance in self-selected speed in the stroke group and 20% in the healthy group, and 63% and 38%, respectively, in maximum walking speed. For the 6MWT, the model explained 44% of the variance in the stroke group. Low to moderate correlations were found between the 6MWT and one-legged bicycling measurements in the paretic leg, such as VO2peak, Wmax and total exercise time. There was a moderate to high correlation between specific stroke impairments and the walking test. The self-reported physical activity was moderately correlated with walking speed. A regression model with the self-reported physical activity as the dependent variable and age and self-selected walking speed as independent variables explained approximately 30% of the variation in the stroke group. In both groups, only the walking speed showed a significant contribution to the model. Conclusions: The environment has an impact on walking performance. Walking speed measured over a short distance seemed to overestimate long distance walking capacity for the slow walkers, despite the environment. A non-linear relationship was found between muscle strength in the lower extremity and walking performance. For those that are weak, changes in muscle strength have a stronger impact on walking. It seems that factors other than cardiorespiratory fitness influence the 6MWT. HR and SBP indicate cardiovascular stress, but the use of only the 6MWT distance as an indicator for cardiorespiratory fitness cannot be recommended. Physical performance including walking performance, muscle strength, cardiorespiratory fitness and self-reported physical activity was below the level of healthy controls. As low levels of physical activity are regarded as a large health-threatening problem in the general population, it is of major importance to find ways to promote physical activity for persons with disabilities

Lumbar disc degeneration is linked to a carbohydrate sulfotransferase 3 variant

Lumbar disc degeneration (LDD) is associated with both genetic and environmental factors and affects many people worldwide. A hallmark of LDD is loss of proteoglycan and water content in the nucleus pulposus of intervertebral discs. While some genetic determinants have been reported, the etiology of LDD is largely unknown. Here we report the findings from linkage and association studies on a total of 32,642 subjects consisting of 4,043 LDD cases and 28,599 control subjects. We identified carbohydrate sulfotransferase 3 (CHST3), an enzyme that catalyzes proteoglycan sulfation, as a susceptibility gene for LDD. The strongest genome-wide linkage peak encompassed CHST3 from a Southern Chinese family-based data set, while a genome-wide association was observed at rs4148941 in the gene in a meta-analysis using multiethnic population cohorts. rs4148941 lies within a potential microRNA-513a-5p (miR-513a-5p) binding site. Interaction between miR-513a-5p and mRNA transcribed from the susceptibility allele (A allele) of rs4148941 was enhanced in vitro compared with transcripts from other alleles. Additionally, expression of CHST3 mRNA was significantly reduced in the intervertebral disc cells of human subjects carrying the A allele of rs4148941. Together, our data provide new insights into the etiology of LDD, implicating an interplay between genetic risk factors and miRNA.Link_to_subscribed_fulltex