(3Z)-2-Acetylamino-3-octadecen-1-ol as a potent apoptotic agent against HL-60 cells

(2R,3Z)-, (2R,3E)-, (2S,3Z) and (2S,3E)-2-Acetylamino-3-octadecen-1-ol, and (2R)- and (2S)-2-acetylamino-octadecan-1-ol were prepared using the Wittig olefination of Garner's aldehyde (N-Boc-N,O-isopropylidene-L- or D-serinal) from L- or D-serine. The apoptotic activities of these saturated and unsaturated 2-acetylaminoalcohols were examined in human leukemia HL-60 cells using MTT assay. Among the newly synthesized compounds, the cis-isomers were the most potent. Despite their simple structures, (2R,3Z)- and (2S,3Z)-2-acetylamino-3-octadecen-1-ol showed high and comparable apoptotic activities compared with N-acetyl-D-erythro-sphingosine (D-e-C2-Cer, a well-known inducer of apoptosis). Their apoptotic activities were in the order D-e-C2-Cer approximately L-e-C2-Cer approximately (2R,3Z)- approximately (2S,3Z)->(2R,3E)- approximately (2S,3E)- approximately (2R)- approximately (2S)-derivative. Qualitative analysis of DNA fragmentation caused by these compounds was conducted using agarose gel electrophoresis, and typical DNA fragmentation was found in the cases of (2R,3Z)- and (2S,3Z)-isomers such as C2-Cer, but not trans and saturated isomers. The morphological features of the cells, the proteolytic processing of pro-caspase-3, and the cleavage of PARP as a result of exogenous treatment with (2R,3Z)- and (2S,3Z)-isomers indicated that cell death induced by these compounds was apoptosis. These observations suggest that these newly synthesized compounds, (3Z)-2-Acetylamino-3-octadecen-1-ol, have similar characteristics and apoptosis-inducing activities against HL-60 cells with C2-Cer.     

Binding of FAD to cytochrome b558 is facilitated during activation of the phagocyte NADPH oxidase, leading to superoxide production

The superoxide-producing phagocyte NADPH oxidase can be reconstituted in a cell-free system. The activity of NADPH oxidase is dependent on FAD, but the physiological status of FAD in the oxidase is not fully elucidated. To clarify the role of FAD in NADPH oxidase, FAD-free full-length recombinant p47(phox), p67(phox), p40(phox), and Rac were prepared, and the activity was reconstituted with these proteins and purified cytochrome b(558) (cyt b(558)) with different amounts of FAD. A remarkably high activity, over 100 micromol/s/micromol heme, was obtained in the oxidase with purified cyt b(558), ternary complex (p47-p67-p40(phox)), and Rac. From titration with FAD of the activity of NADPH oxidase reconstituted with purified FAD-devoid cyt b, the dissociation constant K(d) of FAD in cyt b(558) of reconstituted oxidase was estimated as nearly 1 nm. We also examined addition of FAD on the assembly process in reconstituted oxidase. The activity was remarkably enhanced when FAD was present during assembly process, and the efficacy of incorporating FAD into the vacant FAD site in purified cyt b(558) increased, compared when FAD was added after assembly processes. The absorption spectra of reconstituted oxidase under anaerobiosis showed that incorporation of FAD into cyt b(558) recovered electron flow from NADPH to heme. From both K(d) values of FAD and the amount of incorporated FAD in cyt b(558) of reconstituted oxidase, in combination with spectra, we propose the model in which the K(d) values of FAD in cyt b(558) is changeable after activation and FAD binding works as a switch to regulate electron transfer in NADPH oxidase.     

Adjustment of Temporal Call Usage During Vocal Exchange of Coo Calls in Japanese Macaques

Japanese macaques (Macaca fuscata) exchange coo calls with group members to maintain contact. I examined the relationship between the distance between group members and (1) the latency of vocal responses to spontaneous calls, and (2) the latency of spontaneous call repetition in the absence of vocal responses. After a subject monkey's spontaneous call, the latency of vocal response by another group member was longer when the subject was farther from the group members than when the subject was near the group members. Furthermore, subject repeated calls with longer intervals in the absence of vocal response, which suggests that they wait longer for the vocal responses of other group members when the expected response latency is longer. These results reveal that Japanese macaques flexibly alter the timing of their calls based on others’ vocal responses.     

Transesterification of phosphatidylcholine in <Emphasis Type="Italic">sn</Emphasis>-1 position through direct use of lipase-producing <Emphasis Type="Italic">Rhizopus oryzae</Emphasis> cells as whole-cell biocatalyst

The enzymatic process presents an advantage of producing specified phospholipids that rarely exist in nature. In this study, we investigated the regiospecific modification of phosphatidylcholine (PC) in the sn-1 position using immobilized Rhizopus oryzae. In a reaction mixture containing egg yolk PC and exogenous lauric acid (LA) in n-hexane, lipase-producing R. oryzae cells immobilized within biomass support particles (BSPs) showed a much higher transesterification activity than lipase powders. To improve the product yield, several parameters including substrate ratio and reaction time were investigated, resulting in the incorporation of 44.2% LA into the product PC after a 48-h reaction. The analysis of the molecular structure showed that a large proportion of exogenous LA (>90%) was incorporated in the sn-1 position of the enzymatically modified PC. Moreover, the BSP-immobilized R. oryzae maintained its activity for more than 12 batch cycles. The presented results, therefore, suggest the applicability of BSP-immobilized R. oryzae as a whole-cell biocatalyst for the regiospecific modification of phospholipids.     

Kinetic analysis of amyloid protofibril dissociation and volumetric properties of the transition state

We present here the first detailed kinetic analysis of the dissociation reaction of amyloid protofibrils by utilizing pressure as an accelerator of the reaction. The experiment is carried out on an excessively diluted typical protofibril solution formed from an intrinsically denatured disulfide-deficient variant of hen lysozyme with Trp fluorescence as the reporter in the pressure range 3-400 MPa. From the analysis of the time-dependent fluorescence decay and the length distribution of the protofibrils measured on atomic force microscopy, we conclude that the protofibril grows or decays by attachment or detachment of a monomer at one end of the protofibril with a monomer dissociation rate independent of the length of the fibril. Furthermore, we find that the dissociation reaction is strongly dependent on pressure, characterized with a negative activation volume DeltaV(odouble dagger) = -50.5 +/- 1.60 ml mol(-1) at 0.1 MPa and with a negative activation compressibility Deltakappa(double dagger) = -0.013 +/- 0.001 ml mol(-1) bar(-1) or -0.9 x 10(-6) ml g(-1) bar(-1). These results indicate that the protofibril is a highly compressible high-volume state, but that it becomes less compressible and less voluminous in the transition state, most probably due to partial hydration of the existing voids. The system eventually reaches the lowest-volume state with full hydration of the monomer in the dissociated state.     

Efficient plant regeneration of native spearmint (Mentha spicata L.)

Summary Protocols and media constituents for efficient in vitro plant regeneration of Native Spearmint (Mentha spicata L. cultivar ‘Native Spearmint’) have been defined. Adventitious shoots were initiated either directly from morphogenetically competent cells of explants or primary callus. Leaf explants from at least 2-mo.-old in vitro-maintained shoots exhibited the greatest morphogenetic capacity. Explants derived from basal portions of leaves at the bottom of the shoot were most responsive, with up to a 100% regeneration frequency and greater than nine shoots per explant. Highest frequency of meristemoids and morphogenetic callus were initiated from explants cultured onto a basal medium containing Murashige and Skoog (MS) salts, supplemented with 4 mg thidiazuron (TDZ) per L and 25% (vol/vol) coconut water (CW) for 10 to 14 d in darkness. Bud and shoot development required removal of both TDZ and CW from the medium. Shoot propagules were transferred to basal medium supplemented with 0.01 mg α-naphthaleneacetic acid (NAA) per L and grown under low light for about 2 wk to facilitate shoot elongation. Individual shoots about 1 cm tall were dissected and retransferred onto the same medium. Root initiation began within 4 to 6 d and a functional root system developed within 2 to 3 wk. These plantlets were transferred to soil and acclimated successfully for growth and development in a greenhouse. This is the first report of an efficient regeneration system for Native Spearmint based on adventitious organogenesis.     

Enzymatic synthesis of a novel glycolipid biosurfactant, mannosylerythritol lipid-D and its aqueous phase behavior

Mannosylerythritol lipids (MELs) produced by yeasts are one of the most promising glycolipid biosurfactants. In this study, we succeeded in the preparation of a novel MEL homolog having no acetyl groups, namely MEL-D. MEL-D was synthesized by lipase-catalyzed hydrolysis of acetyl groups from a known MEL, and identified as 4-O-[2′,3′-di-O-alka(e)noyl-β-d-mannopyranosyl]-(2R,3S)-erythritol. The obtained MEL-D showed a higher critical aggregation concentration (CAC = 1.2 × 10⁻⁵ M) and hydrophilicity compared to known MELs, retaining an excellent surface tension lowering activity (the surface tension at the CAC was 24.5 mN/m). In addition, we estimated the binary phase diagram of the MEL-D–water system based on a combination of visual inspection, polarized optical microscopy, and SAXS measurement. From these results, MEL-D was found to self-assemble into a lamellar (L_α) structure over all ranges of concentration. Meanwhile, the one-phase L_α region of MEL-D was extended wider than those of known MELs. MEL-D might keep more water between the polar layers in accordance with the extension of the interlayer spacing (d). These results suggest that the newly obtained MEL-D would facilitate the application of MELs in various fields as a lamellar-forming glycolipid with higher hydrate ability.     

In <Emphasis Type="Italic">vitro</Emphasis> synthesis of glycogen: the structure,properties, and physiological function of enzymatically-synthesized glycogen

This review describes a new enzymatic method for in vitro glycogen synthesis and its structure and properties. In this method, short-chain amylose is used as the substrate for branching enzymes (BE, EC 2.4.1.18). Although a kidney bean BE and Bacillus cereus BE could not synthesize high-molecular weight glucan, BEs from 6 other bacterial sources produced enzymatically synthesized glycogen (ESG). The BE from Aquifex aeolicus was the most suitable for the production of glycogen with a weight-average molecular weight (M _w) of 3,000–30,000 k. The molecular weight of the ESG is controllable by changing the concentration of the substrate amylose. Furthermore, the addition of amylomaltase (AM, EC 2.4.1.25) significantly enhanced the efficiency of this process, and the yield of ESG reached approximately 65%. Typical preparations of ESG obtained by this method were subjected to structural analyses. The average chain length, interior chain length, and exterior chain length of the ESGs were 8.2–11.6, 2.0–3.3, and 4.2–7.6, respectively. Transmission electron microscopy and intrinsic viscosity measurement showed that the ESG molecules formed spherical particles. Unlike starch, the ESGs were barely degraded by pullulanase. Solutions of ESG were opalescent (milky-white and slightly bluish), and gave a reddishbrown color on the addition of iodine. These analyses revealed that ESG shares similar molecular shapes and solution properties with natural-source glycogen. Moreover, ESG had macrophage-stimulating activity and its activity depends on the molecular weight of ESG. We successfully achieved large scale production of ESG. ESG could lead to new industrial applications, such as in the food, chemical, and pharmaceutical fields.     

Where Do Neurologists Look When Viewing Brain CT Images? An Eye-Tracking Study Involving Stroke Cases

The aim of this study was to investigate where neurologists look when they view brain computed tomography (CT) images and to evaluate how they deploy their visual attention by comparing their gaze distribution with saliency maps. Brain CT images showing cerebrovascular accidents were presented to 12 neurologists and 12 control subjects. The subjects' ocular fixation positions were recorded using an eye-tracking device (Eyelink 1000). Heat maps were created based on the eye-fixation patterns of each group and compared between the two groups. The heat maps revealed that the areas on which control subjects frequently fixated often coincided with areas identified as outstanding in saliency maps, while the areas on which neurologists frequently fixated often did not. Dwell time in regions of interest (ROI) was likewise compared between the two groups, revealing that, although dwell time on large lesions was not different between the two groups, dwell time in clinically important areas with low salience was longer in neurologists than in controls. Therefore it appears that neurologists intentionally scan clinically important areas when reading brain CT images showing cerebrovascular accidents. Both neurologists and control subjects used the "bottom-up salience" form of visual attention, although the neurologists more effectively used the "top-down instruction" form.