Non-invasive assessment of superficial soft tissue local displacements during movement: A feasibility study

In the movement analysts community, the assessment of the displacement of skin photogrammetric markers relative to the underlying bone (soft tissue displacement, STD) is considered to be a priority. The aim of this study is to present a non-invasive method that allows for the characterization of STD for any marker location, subject, and motor task. In particular, this method provides an estimate of the STD vector in a bone-embedded frame. The body segment under analysis is endowed with the largest possible number of skin markers located over all areas of interest. Any given STD vector is observed from all the marker cluster frames that can be built by suitably combining all the available markers. A subset of the latter frames is identified that is made of frames endowed with uncorrelated local movements. The estimate of a given STD vector is determined through the coherent average of the vectors reconstructed using the above-mentioned independent frames. This estimate is affected by a 180° phase indeterminacy.The proposed method and the underlying hypotheses were validated using markers located on the thighs of two female subjects treated for a total knee replacement. The relevant STD estimates, STD_m, were compared with those directly observed using photogrammetry combined with 2D fluoroscopic projections and the prosthesis CAD model (STD_f). Recordings were made while the volunteers performed step up/down motor tasks.The root mean square value of STD_m was found in the range 2.5–23.0 mm and was consistent with the RMS values of STD_f and with other results reported in the literature and obtained in similarly unconstrained conditions. Moreover, STD_m and STD_f showed a pattern similarity measured by a correlation coefficient equal to 0.83 (±0.13) and by a normalised root mean square distance equal to 27% (±16%).The described estimate of the STD pattern and magnitude, even with the above-mentioned indeterminacies, constitutes valuable information when aiming at optimal marker placement and is an indispensable prerequisite for bone pose estimator design and assessment.     

Jasmonic acid transient accumulation is needed for abscisic acid increase in citrus roots under drought stress conditions

Phytohormones are central players in sensing and signaling numerous environmental conditions like drought stress. In this work, an experimental system based on severe drought was established and hormone profiling together with gene expression of key enzymes involved in abscisic acid (ABA) and jasmonic acid (JA) biosynthesis was studied in roots of citrumelo CPB 4475 (a commercial citrus rootstock) plants. JA concentration transiently increased after a few hours of stress, returning to control levels 30 h after the onset of the condition. A more progressive ABA accumulation was observed, with the onset of this increase at the same time or right after the JA transient accumulation. Molecular data suggested that, at least, part of the hormonal regulation takes place at the biosynthetic level. These observations also pointed to a possible involvement of JA on ABA biosynthesis under stress. To test this hypothesis, JA and ABA biosynthesis were chemically inhibited and subsequently phenotypes rescued by the addition of exogenous hormones. Results showed that the early JA accumulation was necessary for the subsequent ABA increase in roots under stress whereas the opposite could not be stated. The model includes a burst of JA in roots of citrus under severe drought stress conditions that leads to a more progressive ABA accumulation that will induce later plant responses. The present work adds a new level of interaction between JA and ABA at the biosynthetic level that together with the previously described interaction between signal transduction cascades of the two hormones would allow plants to fine‐tune specific responses to different stimuli.     

Ecology of the growth of Anolis nebulosus (Squamata: Dactyloidae) in a seasonal tropical environment in the Chamela region,Jalisco, Mexico

Juvenile growth rates are thought to be restricted by available food resources. In animals that grow throughout the year, such as tropical lizards, growth is therefore predicted to be faster during the rainy season. We test this prediction using a population of Anolis nebulosusby describing the growth trajectories of both sexes using nonlinear regression models, and we then correlate the growth rates of individuals with food available in the environment, precipitation, and temperature. The Von Bertalanffy model fits the growth rates of the females better, while the logistic‐by‐length model fits the males better. According to both models, the males grew faster than females, reaching slightly smaller sizes at adulthood. Males reached sexual maturity when 35 mm long, at an age of seven months, and females matured at 37 mm (SVL), taking nine months to reach this size. In 1989, juvenile males and females grew more in both seasons (rainy and dry) than adults; for 1990, there were no differences by season or between age classes. These results are interesting since in the 1989 and 1990 rainy seasons, practically the same orders of prey and the greatest abundance of prey available in the environment were registered. A possible explanation could be that predation was more intense in 1990 than in 1989. There is little evidence that food, temperature, and humidity affect growth rates of A. nebulosus, refuting our predictions. This is mainly due to the low variation in growth observed in 1990. Therefore we think that the growth of this species reflects a complex combination of ecological and genetic factors.     

Cloning,functional expression,biochemical characterization,and structural analysis of a haloalkane dehalogenase from <Emphasis Type="Italic">Plesiocystis pacifica</Emphasis> SIR-1

A haloalkane dehalogenase (DppA) from Plesiocystis pacifica SIR-1 was identified by sequence comparison in the NCBI database, cloned, functionally expressed in Escherichia coli, purified, and biochemically characterized. The three-dimensional (3D) structure was determined by X-ray crystallography and has been refined at 1.95 Å resolution to an R-factor of 21.93%. The enzyme is composed of an α/β-hydrolase fold and a cap domain and the overall fold is similar to other known haloalkane dehalogenases. Active site residues were identified as Asp123, His278, and Asp249 and Trp124 and Trp163 as halide-stabilizing residues. DppA, like DhlA from Xanthobacter autotrophicus GJ10, is a member of the haloalkane dehalogenase subfamily HLD-I. As a consequence, these enzymes have in common the relative position of their catalytic residues within the structure and also show some similarities in the substrate specificity. The enzyme shows high preference for 1-bromobutane and does not accept chlorinated alkanes, halo acids, or halo alcohols. It is a monomeric protein with a molecular mass of 32.6 kDa and exhibits maximum activity between 33 and 37°C with a pH optimum between pH 8 and 9. The K_m and k_cat values for 1-bromobutane were 24.0 mM and 8.08 s^?1. Furthermore, from the 3D-structure of DppA, it was found that the enzyme possesses a large and open active site pocket. Docking experiments were performed to explain the experimentally determined substrate preferences.     

Carrier-mediated transport of metabolites in purified bean mitochondria

1. The mechanism of transport of Krebs cycle intermediates, phosphateand sulfurcontaining compounds across the membrane of purifiedbean mitochondria was investigated by directly measuring dieexchange between intramitochondrial labelled substrates andexternal anions and by testing die inhibitor sensitivity ofdiese transport processes.
2. The exchange between intramitochondrialphosphate and externalphosphate or sulfite is insensitive toN-ediylmaleimide or butylmalonatewhen either is added alone,but is completely inhibited by N-ethylmaleimideplus butylmalonateor by mersalyl. Internal phosphate is exchangedwith malate,succinate, oxaloacetate, sulfate and thiosulfate;these reactionsare inhibited by butylmalonate but not affectedby N-ethylmaleimide.
3. Internal sulfate is exchanged with malate, malonate, succinate,phosphate and sulfite in a butylmalonate- and mersalyl-sensitivereaction. Also the exchanges of malonate with phosphate, sulfateand sulfite are inhibited by butylmalonate and mersalyl. Onthe other hand, the exchange between intra- and extramitochondrialmalonate is completely inhibited only by the combination ofbutylmalonate and 1,2,3-benzenetricarboxylate.
4. Citrate isexchanged with some di- and tricarboxylates and phosphoenolpyruvate(but not with phosphate, sulfate, oxoglutarate, trans-aconitateand benzenetricarboxylates). These exchanges are inhibited by1,2,3-benzenetricarboxylate, but not by 1,2,4-benzenetricarboxylateor 1,3,5-pentanetricarboxylate.
5. Oxoglutarate is exchangedwith succinate, malate, malonate andoxaloacetate (but not withphosphate, citrate or phosphoenolpyruvate)in a mersalyl-insensitive,butylmalonate- and phenylsuccinate-sensitivereaction.
6. Weconcluded that bean mitochondria contain the following transportsystems: a phosphate carrier inhibited by N-ethylmaleimide ormersalyl, a dicarboxylate carrier inhibited by butylmalonateor mersalyl, a citrate carrier inhibited by 1,2,3-benzenetricarboxylateand an oxoglutarate carrier inhibited by phenylsuccinate orbutylmalonate but insensitive to mersalyl.

(Received June 23, 1976; )