Continuous measurements of stable isotopes of carbon dioxide and water vapour in an urban atmosphere: isotopic variations associated with meteorological conditions.

Isotope ratios of carbon dioxide and water vapour in the near-surface air were continuously measured for one month in an urban area of the city of Nagoya in central Japan in September 2010 using laser spectroscopic techniques. During the passages of a typhoon and a stationary front in the observation period, remarkable changes in the isotope ratios of CO2 and water vapour were observed. The isotope ratios of both CO2 and water vapour decreased during the typhoon passage. The decreases can be attributed to the air coming from an industrial area and the rainout effects of the typhoon, respectively. During the passage of the stationary front, δ13C-CO2 and δ18O-CO2 increased, while δ2H-H2Ov and δ18O-H2Ov decreased. These changes can be attributed to the air coming from rural areas and the air surrounding the observational site changing from a subtropical air mass to a subpolar air mass during the passage of the stationary front. A clear relationship was observed between the isotopic CO2 and water vapour and the meteorological phenomena. Therefore, isotopic information of CO2 and H2Ov could be used as a tracer of meteorological information.

In situ measurement of CO2 and water vapour isotopic compositions at a forest site using mid-infrared laser absorption spectroscopy.

We conducted continuous, high time-resolution measurements of CO2 and water vapour isotopologues ((16)O(12)C(16)O, (16)O(13)C(16)O and (18)O(12)C(16)O for CO2, and H2(18)O for water vapour) in a red pine forest at the foot of Mt. Fuji for 9 days from the end of July 2010 using in situ absorption laser spectroscopy. The δ(18)O values in water vapour were estimated using the δ(2)H-δ(18)O relationship. At a scale of several days, the temporal variations in δ(18)O-CO2 and δ(18)O-H2O are similar. The orders of the daily Keeling plots are almost identical. A possible reason for the similar behaviour of δ(18)O-CO2 and δ(18)O-H2O is considered to be that the air masses with different water vapour isotopic ratios moved into the forest, and changed the atmosphere of the forest. A significant correlation was observed between δ(18)O-CO2 and δ(13)C-CO2 values at nighttime (r(2)≈0.9) due to mixing between soil (and/or leaf) respiration and tropospheric CO2. The ratios of the discrimination coefficients (Δa/Δ) for oxygen (Δa) and carbon (Δ) isotopes during photosynthesis were estimated in the range of 0.7-1.2 from the daytime correlations between δ(18)O-CO2 and δ(13)C-CO2 values.

A hierarchical Bayesian model to estimate the unobservable predation rate on sawfly cocoons by small mammals.

Predation by small mammals has been reported as an important mortality factor for the cocoons of sawfly species. However, it is difficult to provide an accurate estimate of newly spun cocoons and subsequent predation rates by small mammals for several reasons. First, all larvae do not spin cocoons at the same time. Second, cocoons are exposed to small mammal predation immediately after being spun. Third, the cocoons of the current generation are indistinguishable from those of the previous generation. We developed a hierarchical Bayesian model to estimate these values from annual one-time soil sampling datasets. To apply this model to an actual data set, field surveys were conducted in eight stands of larch plantations in central Hokkaido (Japan) from 2009 to 2012. Ten 0.04-m(2) soil samples were annually collected from each site in mid-October. The abundance of unopened cocoons (I), cocoons emptied by small-mammal predation (M), and empty cocoons caused by something other than small-mammal predation (H) were determined. The abundance of newly spun cocoons, the predation rate by small mammals before and after cocoon sampling, and the annual rate of empty cocoons that remained were estimated. A posterior predictive check yielded Bayesian P-values of 0.54, 0.48, and 0.07 for I, M, and H, respectively. Estimated predation rates showed a significant positive correlation with the number of trap captures of small mammals. Estimates of the number of newly spun cocoons had a significant positive correlation with defoliation intensity. These results indicate that our model showed an acceptable fit, with reasonable estimates. Our model is expected to be widely applicable to all hymenopteran and lepidopteran insects that spin cocoons in soil.

Long-acting genipin derivative protects retinal ganglion cells from oxidative stress models in vitro and in vivo through the Nrf2/antioxidant response element signaling pathway.

Previously, we reported that genipin, a herbal iridoid, had neuritogenic and neuroprotective actions on PC12 cells. Although nitric oxide (NO)-activated signalings were proposed to be neuritogenic, the neuroprotective action of genipin remains to be elucidated. From the standpoint of NO activation, we tested a possible protective mechanism through the nitrosative Kelch-like ECH-associated protein (Keap1)/NF-E2-related factor 2 (Nrf2)-antioxidant response element pathway in rat retinal ganglion cells (RGC-5 cells) in culture, and in vivo, against hydrogen peroxide and optic nerve injury (ONI), respectively, using a long-acting (1R)-isoPropyloxygenipin (IPRG001). IPRG001 induced NO generation and the expressions of antioxidative enzymes, such as heme oxygenase-1 (HO-1), in RGC-5 cells. The protective action of IPRG001 depended on HO-1 and NO induction. We found that S-nitrosylation of Keap1 by IPRG001 may contribute to translocation of Nrf2 to the nucleus and triggered transcriptional activation of antioxidative enzymes. Furthermore, apoptotic cells were increased and 4-hydroxy-2-nonenal was accumulated in rat retina following ONI. Pre-treatment with IPRG001 almost completely suppressed apoptosis and accumulation of 4-hydroxy-2-nonenal in RGCs following ONI accompanied by HO-1 induction. These data demonstrate for the first time that IPRG001 exerts neuroprotective action in RGCs in vitro and in vivo, through the Nrf2/antioxidant response element pathway by S-nitrosylation against oxidative stress.

Growth-associated protein43 (GAP43) is a biochemical marker for the whole period of fish optic nerve regeneration.

In adult visual system, goldfish can regrow their axons and fully restore their visual function even after optic nerve transection. The optic nerve regeneration process in goldfish is very long and it takes about a half year to fully recover visual function via synaptic refinement. Therefore, we investigated time course of growth-associated protein 43 (GAP43) expression in the goldfish retina for over 6 months after axotomy. In the control retina, very weak immunoreactivity could be seen in the retinal ganglion cells (RGCs). The immunoreactivity of GAP43 started to increase in the RGCs at 5 days, peaked at 7-20 days and then gradually decreased at 30-40 days after axotomy. The weak but significant immunoreactivity of GAP43 in the RGCs continued during 50-90 days and slowly returned to the control level by 180 days after lesion. The levels of GAP43 mRNA showed a biphasic pattern; a short-peak increase (9-folds) at 1-3 weeks and a long plateau increase (5-folds) at 50-120 days after axotomy. Thereafter, the levels declined to the control value by 180 days after axotomy. The changes of chasing behavior of pair of goldfish with bilaterally axotomized optic nerve also showed a slow biphasic recovery pattern in time course. Although further experiment is needed to elucidate the role of GAP43 in the regrowing axon terminals, the GAP43 is a good biochemical marker for monitoring the whole period of optic nerve regeneration in fish.

Wideband digital frequency detector with subtraction-based phase comparator for frequency modulation atomic force microscopy.

We have developed a wideband digital frequency detector for high-speed frequency modulation atomic force microscopy (FM-AFM). We used a subtraction-based phase comparator (PC) in a phase-locked loop circuit instead of a commonly used multiplication-based PC, which has enhanced the detection bandwidth to 100 kHz. The quantitative analysis of the noise performance revealed that the internal noise from the developed detector is small enough to provide the theoretically limited noise performance in FM-AFM experiments in liquid. FM-AFM imaging of mica in liquid was performed with the developed detector, showing its stability and applicability to true atomic-resolution imaging in liquid.

Purpurin is a key molecule for cell differentiation during the early development of zebrafish retina.

Recently, we cloned purpurin cDNA as an upregulated gene in the axotomized fish retina. The retina-specific protein was secreted from photoreceptors to ganglion cell layer during an early stage of optic nerve regeneration in zebrafish retina. The purpurin worked as a trigger molecule for axonal regrowth in adult injured fish retina. During zebrafish development, purpurin mRNA first appeared in ventral retina at 2 days post-fertilization (dpf) and spread out to the outer nuclear layer at 3 dpf. Here, we investigated the role of purpurin for zebrafish retinal development using morpholino gene knockdown technique. Injection of purpurin morpholino into the 1-2 cell stage of embryos significantly inhibited the transcriptional and translational expression of purpurin at 3 dpf. In the purpurin morphant, the eyeball was significantly smaller and retinal lamination of nuclear and plexiform layers was not formed at 3 dpf. Retinal cells of purpurin morphants were still proliferative and undifferentiated at 3 dpf. The visual function of purpurin morphant estimated by optomotor response was also suppressed at 5 dpf. By contrast, the control morphants with random sequence morpholino showed retinal lamination with distinct layers and differentiated cells at 3 dpf. These results strongly suggest that purpurin is a key molecule for not only optic nerve regeneration in adult but also cell differentiation during early development in embryo.

Changes of phospho-growth-associated protein 43 (phospho-GAP43) in the zebrafish retina after optic nerve injury: a long-term observation.

The major model animal of optic nerve regeneration in fish is goldfish. A closely related zebrafish is the most popular model system for genetic and developmental studies of vertebrate central nervous system. A few challenging works of optic nerve regeneration have been done with zebrafish. However, knowledge concerning the long term of optic nerve regeneration apparently lacks in zebrafish. In the present study, therefore, we followed changes of zebrafish behavior and phosphorylated form of growth-associated protein 43 (phospho-GAP43) expression in the zebrafish retina over 100 days after optic nerve transection. Optomotor response was fast recovered by 20-25 days after axotomy whereas chasing behavior (a schooling behavior) was slowly recovered by 80-100 days after axotomy. The temporal pattern of phospho-GAP43 expression showed a biphasic increase, a short-peak (12 folds) at 1-2 weeks and a long-plateau (4 folds) at 1-2 months after axotomy. The recovery of optomotor response well correlated with projection of growing axons to the tectum, whereas the recovery of chasing behavior well correlated with synaptic refinement of retinotectal topography. The present data strongly suggest that phospho-GAP43 plays an active role in both the early and late stages of optic nerve regeneration in fish.

A comprehensive analysis of allelic methylation status of CpG islands on human chromosome 11q: comparison with chromosome 21q.

It was generally believed that autosomal CpG islands (CGIs) escape methylation. However, our comprehensive analysis of allelic methylation status of 149 CGIs on human chromosome 21q revealed that a sizable fraction of them are methylated on both alleles even in normal blood cells. Here, we performed a similar analysis of 656 CGIs on chromosome 11q, which is gene-rich in contrast with 21q. The results indicate that 11q contains less methylated CGIs, especially those with tandem repeats and those in the coding or 3'-untranslated regions (UTRs), than 21q. Thus, methylation status of CGIs may substantially differ from one chromosome to another.

A computer image processing system for quantification of zebrafish behavior.

The tropical zebrafish (Danio rerio) has frequently been used for investigating developmental biology. Here, we developed a computer image processing system for quantifying zebrafish behavior. We could acquire an image of zebrafish freely moving in an aquarium using a CCD camera through a graphic I/O board. To acquire the image of moving zebrafish in real time, we required high spatial (256 x 256 pixels) and temporal (10 frames/s) resolution. Such a high speed of data analysis was accomplished using a skipping search method. By using a small aquarium, trackings of newborn zebrafish could be traced. The velocity of adult zebrafish (7.2 cm/s) was far faster than that of newborn zebrafish (1.8 cm/s). Furthermore, by separation of occluded images of two fish, we could acquire images of the two zebrafish. They behaved as in a school in which one fish chased the other. The chasing was defined by the distance, angle and approach of the two fishes. The chasing ratio of pairs of zebrafish was 37%, whereas those of pairs of different fish were significantly reduced to less than 20%. The present image processing system is a very useful tool for quantitatively scoring the schooling behavior of multiple fish.