Interaction of Arabidopsis kinesin-like calmodulin-binding protein with tubulin subunits: modulation by Ca(2+)-calmodulin

Kinesin-like calmodulin-binding protein (KCBP) is a recently identified novel kinesin-like protein that appears to be unique to and ubiquitous in plants. KCBP is distinct from all other known KLPs in having a calmodulin-binding domain adjacent to its motor domain. We have used different regions of KCBP to study its interaction with tubulin subunits and the regulation of this interaction by Ca(2+)-calmodulin. The results show that the carboxy-terminal part of the KCBP, with or without calmodulin-binding domain, binds to tubulin subunits and this binding is sensitive to nucleotides. In the presence of Ca(2+)-calmodulin the motor with calmodulin-binding domain does not bind to tubulin. This Ca(2+)-calmodulin modulation is abolished in the presence of antibodies specific to the calmodulin-binding domain of KCBP. Similar binding studies with the carboxy-terminal part of KCBP lacking the calmodulin-binding domain show no effect of Ca(2+)-calmodulin. These results indicate that Ca(2+)-calmodulin modulates the interaction of KCBP with tubulin subunits and this modulation is due to the calmodulin-binding domain in the KCBP. Calcium-dependent calmodulin modulation of KCBP interaction with tubulin suggests regulation of KCBP function by calcium, the first such regulation of a kinesin heavy chain among all the known kinesin-like proteins.     

Characterization of microtubule binding domains in the Arabidopsis kinesin-like calmodulin binding protein

The kinesin-like calmodulin binding protein (KCBP) is a new member of the kinesin superfamily that appears to be present only in plants. The KCBP is unique in its ability to interact with calmodulin in a Ca2+-dependent manner. To study the interaction of the KCBP with microtubules, we expressed different regions of the Arabidopsis KCBP and used the purified proteins in cosedimentation assays with microtubules. The motor domain with or without the calmodulin binding domain bound to microtubules. The binding of the motor domain containing the calmodulin binding region to microtubules was inhibited by Ca2+-calmodulin. This Ca2+-calmodulin regulation of motor domain interactions with microtubules was abolished in the presence of antibodies specific to the calmodulin binding region. In addition, the binding of the motor domain lacking the calmodulin binding region to microtubules was not inhibited in the presence of Ca2+-calmodulin, suggesting an essential role for the calmodulin binding region in Ca2+-calmodulin modulation. Results of the cosedimentation assays with the N-terminal tail suggest the presence of a second microtubule binding site on the KCBP. However, the interaction of the N-terminal tail region of the KCBP with microtubules was insensitive to ATP. These data on the interaction of the KCBP with microtubules provide new insights into the functioning of the KCBP in plants.     

The role of Staphylococcus epidermidis persistence factors in the infectious process

The species composition of microflora was determined and the etiological role of S. epidermidis was shown in some purulent inflammatory diseases (maxillary sinusitis, urethritis). The role of the complex of S. epidermidis persistence factors in the chronization of the infectious process and the formation of the resident carrier state was established.     

Predictors of early failure of fixation in the treatment of displaced subcapital hip fractures

Malignant hyperthermia is a rare complication in clinical anesthesia, especially associated with the administration of succinylcholine or inhalation anesthetics. A 19-year-old patient, suffering from traumatic mandible fracture, underwent open reduction under general anesthesia. Unfortunately, following administration of succinylcholine, he also suffered severe facial twitch and the first episode of hypercapnia. After adequate management, the symptoms subsided. However, two hours later, the hypercapnia recurred, combined with progressive elevation of body temperature. After administration of intravenous dantrolene 120 mg, the patient's condition became stable and the procedure was completed without sequelae. As the muscle contracture test is not available in Taiwan, the clinical grading scale is presented as an alternative diagnostic method for malignant hyperthermia.     

The novel substituted acylproline-containing dipeptide, GVS-111, promotes the restoration of learning and memory impaired by bilateral frontal lobectomy in rats

The present study investigated the potential benefit of the ethyl ester of N-phenylacetylprolylglycine (GVS-111) on the model of bilateral frontal lobectomy (BFL) in rats. The animals in Experiment 1 were trained in an active avoidance task and subsequently underwent BFL. The animals in Experiment 2 were first assessed in an open field and in a passive avoidance test before the BFL was performed. BFL dramatically decreased performance in the active avoidance test, disturbed habituation of horizontal activity in the open field and diminished the latency to enter the dark compartment in the passive avoidance test. GVS-111, administered in a dose of 0.5 mg/kg/day i.p. for 9 days following the operation, was found to improve performance in both active avoidance and passive avoidance and restored habituation of horizontal activity in the lobectomized animals.     

Differences in susceptibility of Arabidopsis ecotypes to crown gall disease may result from a deficiency in T-DNA integration

We show that among ecotypes of Arabidopsis, there is considerable variation in their susceptibility to crown gall disease. Differences in susceptibility are heritable and, in one ecotype, segregate as a single major contributing locus. In several ecotypes, recalcitrance to tumorigenesis results from decreased binding of Agrobacterium to inoculated root explants. The recalcitrance of another ecotype occurs at a late step in T-DNA transfer. Transient expression of a T-DNA-encoded beta-glucuronidase gusA gene is efficient, but the ecotype is deficient in crown gall tumorigenesis, transformation to kanamycin resistance, and stable GUS expression. This ecotype is also more sensitive to gamma radiation than is a susceptible ecotype. DNA gel blot analysis showed that after infection by Agrobacterium, less T-DNA was integrated into the genome of the recalcitrant ecotype than was integrated into the genome of a highly susceptible ecotype.     

Local arthroscopic bone grafting of a juxta-articular glenoid bone cyst

This report describes a rare, juxta-articular bone cyst of the posterior glenoid that developed after a fracture of the glenoid in a 38-year-old male. The patient had persistent pain, popping and stiffness of his right shoulder for 3 years, and failed to improve after a nonoperative rehabilitation program. At arthroscopy, the senior author transported an autogenous bone graft from the bare area of the humeral head to fill the glenoid cyst arthroscopically. At second-look arthroscopy approximately 1 year after the index procedure, the bone graft had consolidated within the original cystic defect and the surface was covered with fibrocartilage. The graft harvest site posteriorly on the humeral head had healed with a small amount of scar tissue at the articular margin. Comfortable motion and function were restored.