Activation of sea urchin sperm flagellar dynein ATPase activity by salt-extracted axonemes

When 21S dynein ATPase [EC 3.6.1.3] from sea urchin sperm flagellar axonemes was mixed with the salt-extracted axonemes, the ATPase activity was much higher than the sum of ATPase activities in the two fractions, as reported previously (Gibbons, I.R. & Fronk, E. (1979) J. Biol. Chem. 254, 187-196). This high ATPase level was for the first time demonstrated to be due to the activation of the 21S dynein ATPase activity by the axonemes. The mode of the activation was studied to get an insight into the mechanism of dynein-microtubule interaction. The salt-extracted axonemes caused a 7- to 8-fold activation of the 21S dynein ATPase activity at an axoneme : dynein weight ratio of about 14 : 1. The activation was maximal at a low ionic strength (no KCl) at pH 7.9-8.3. Under these conditions, 21S dynein rebound to the salt-extracted axonemes. The maximal binding ratio of 21S dynein to the axonemes was the same as that observed in the maximal activation of 21S dynein ATPase. The sliding between the outer doublet microtubules in the trypsin-treated 21S dynein-rebound axonemes took place upon the addition of 0.05-0.1 mM ATP in the absence of KCl. During the sliding, the rate of ATP hydrolysis was at the same level as that of the 21S dynein activated by the salt-extracted axonemes. However, it decreased to the level of 21S dynein alone after the sliding. These results suggested that an interaction of the axoneme-rebound 21S dynein with B-subfibers of the adjacent outer doublet microtubules in the axoneme causes the activation of the ATPase activity.     

Application of enzyme-linked immunosorbent assay for mass examination of strongyloidiasis in okinawa, Japan

The enzyme-linked immunosorbent assay was tested to evaluate whether it could be applicable in screening for mass examination of strongyloidiasis. A total of 2906 inhabitants in three areas (858 in Gushikawa Village, 849 in Nakazato Village and 1199 in Sashiki Town) were screened by the enzymatic assay and approximately 11–30% (11.8% in Gushikawa, 17.0% in Nakazato and 27.7% in Sashiki) were considered to be antibody positive. In the parasitological follow-up examinations of those who were antibody positive, actual infection was found in more than half (51%) the subjects. The overall infection rates estimated from the results reached 5.8% in Gushikawa, 9.1% in Nakazato and 14.0% in Sashiki (mean = 10.4%). The infection rates were significantly higher than those in previous surveys conducted in the same areas. The ELISA technique was found to be useful for strongyloidiasis screening and for seroepidemiological purposes in Okinawa.     

Possible involvement of protein kinase C and calcium in GSH efflux from Hep G2 cells.

We investigated the effects of protein kinase C modulations and calcium mobilization on GSH efflux in Hep G2 cells. GSH efflux from Hep G2 cells was increased by a phorbol ester. Staurosporine, an inhibitor of protein kinase C, diminished phorbol ester-stimulated GSH efflux from the cells. GSH efflux was negatively correlated with extracellular calcium concentrations. Verapamil enhanced GSH efflux, whereas ATP decreased GSH efflux. The latter effect was diminished in the absence of extracellular calcium. Protein kinase C and calcium mobilization may be crucial factors in GSH efflux from human hepatocytes.     

Conservation of DNA sequences for plasmid-mediated citrate utilization within the enterobacteria.

Southern blot DNA-DNA hybridization experiments with a cloned Cit+ DNA fragment as a probe showed that the plasmid-mediated Cit+ determinants from four Cit plasmids (R726, pOH3001, pOH3035, and pOH30221) were all homologous. Sequences homologous to the plasmid-borne Cit+ gene were also found in total bacterial DNA isolated from Salmonella paratyphi B, Salmonella enteritidis, Salmonella typhimurium LT-2, Citrobacter freundii, ATCC 8090, Citrobacter amalonaticus ATCC 25405, Klebsiella pneumoniae I and IID 977, and Enterobacter aerogenes ATCC 13048. The DNA digest from C. amalonaticus ATCC 25405 contained a 1.4-kilobase BamHI-HincII DNA fragment that was strongly homologous with and identical in size to the plasmid Cit+ probe.     

Comparison of mortality and feeding behavior of the false cleanerfish Aspidontus taeniatus and the lance blenny A. dussumieri regarding the effects of mimicry

Journal of Ethology - Many examples of mimicry have been reported in coral reef fishes of which the most well known is the mimicry of the bluestreak cleaner wrasse, Labroides dimidiatus by the...     

Neuronal dystonin isoform 2 is a mediator of endoplasmic reticulum structure and function

Dystonin/Bpag1 is a cytoskeletal linker protein whose loss of function in dystonia musculorum (dt) mice results in hereditary sensory neuropathy. Although loss of expression of neuronal dystonin isoforms (dystonin-a1/dystonin-a2) is sufficient to cause dt pathogenesis, the diverging function of each isoform and what pathological mechanisms are activated upon their loss remains unclear. Here we show that dt(27) mice manifest ultrastructural defects at the endoplasmic reticulum (ER) in sensory neurons corresponding to in vivo induction of ER stress proteins. ER stress subsequently leads to sensory neurodegeneration through induction of a proapoptotic caspase cascade. dt sensory neurons display neurodegenerative pathologies, including Ca(2+) dyshomeostasis, unfolded protein response (UPR) induction, caspase activation, and apoptosis. Isoform-specific loss-of-function analysis attributes these neurodegenerative pathologies to specific loss of dystonin-a2. Inhibition of either UPR or caspase signaling promotes the viability of cells deficient in dystonin. This study provides insight into the mechanism of dt neuropathology and proposes a role for dystonin-a2 as a mediator of normal ER structure and function.     

Differences in resource storage pattern between Laminaria longissima and Laminaria diabolica (Laminariaceae; Phaeophyta) reflecting their morphological characteristics

The kelps Laminaria longissima and L. diabolica, belonging to the groups of L. angustata and L. japonica, respectively, differ greatly in their morphological characteristics although their geographical distributions overlap widely along the eastern coast of Hokkaido. To clarify the interaction between the morphological and physiological characteristics of the two species, and their link with environmental variables, hatchery-raised young sporophytes of L. longissima and L. diabolica collected from Hokkaido were cultivated simultaneously under similar conditions in Matsushima Bay, Miyagi, from January to July 2004. Seasonal morphological characteristics, gross photosynthetic rate, nutrient uptake rates, and resource contents were examined. The blade lengths of L. longissima and L. diabolica reached a maximum of 329.9 cm and 256.7 cm, respectively, in April to May, and decreased to 284.4 cm and 68.6 cm, respectively, in July. The total elongation length of L. longissima (412.5 cm) was similar to that of L. diabolica (373.8 cm). However, the total erosion length of L. longissima (145.9 cm) was approximately half that of L. diabolica (302.9 cm). The gross photosynthetic rate and uptake rates of NH₄-N, NO₃-N, and PO₄-P of the two species were similar. However, the carbon, nitrogen, and phosphorus contents were transferred and stored in the whole blade tissues in the case of L. longissima, but in the meristem of L. diabolica from May to June. These results suggest that morphological differences are a response to different resource storage patterns. The storage patterns of L. longissima and L. diabolica are likely to be genetically fixed characteristics, which have evolved in adaptation to the specific habitat environments of the groups of L. angustata and L. japonica. The low water temperature and rich nutrients provided by the Oyashio Current are conducive to storage of resources in the whole blade tissues and a large surface area retained for photosynthesis and nutrient uptake in the L. angustata group. Conversely, high temperature and poor nutrients, or large fluctuations in these parameters, provided by the Tsushima Warm Current are more conducive to intensive storage of resources in the meristem for maturation and further growth in the L. japonica group. L. diabolica retains the storage pattern of the L. japonica group but grows in regions affected by the Oyashio Current, allowing it to become the widest distributed Laminaria species.     

Improving goniometer accuracy by compensating for individual transducer characteristics

Flexible goniometers are useful for direct movement measurements. Crosstalk due to rotation between the endblocks is well known. However, even without any rotation, some crosstalk can occur. The objective of this study was to elucidate the effect of, and compensate for, the inherent crosstalk in biaxial goniometers, with specific relevance for applications with one dominating movement direction. Six biaxial goniometers (M110, Biometrics Ltd., Gwent, UK) were evaluated. A precision jig, for simulating pure flexion/extension angles, was constructed. Each sensor produced a consistent and specific crosstalk pattern, when tested over a ±100° range of motion. A procedure for correction for the inherent crosstalk of individual goniometer, based on polynomial adjust, is presented. The method for compensation, which reduced the root mean square error from, on average for the six goniometers, 3.7° (range 1.8–10.1°) to 0.35° (0.12–0.55°), might be required for obtaining valid goniometer measurements, e.g. of valgus/varus of the knee during gait flexion/extension movements.