A monogalactosyldiacylglycerol synthase found in the green sulfur bacterium Chlorobaculum tepidum reveals important roles for galactolipids in photosynthesis.

Monogalactosyldiacylglycerol (MGDG), which is conserved in almost all photosynthetic organisms, is the most abundant natural polar lipid on Earth. In plants, MGDG is highly accumulated in the chloroplast membranes and is an important bulk constituent of thylakoid membranes. However, precise functions of MGDG in photosynthesis have not been well understood. Here, we report a novel MGDG synthase from the green sulfur bacterium Chlorobaculum tepidum. This enzyme, MgdA, catalyzes MGDG synthesis using UDP-Gal as a substrate. The gene encoding MgdA was essential for this bacterium; only heterozygous mgdA mutants could be isolated. An mgdA knockdown mutation affected in vivo assembly of bacteriochlorophyll c aggregates, suggesting the involvement of MGDG in the construction of the light-harvesting complex called chlorosome. These results indicate that MGDG biosynthesis has been independently established in each photosynthetic organism to perform photosynthesis under different environmental conditions. We complemented an Arabidopsis thaliana MGDG synthase mutant by heterologous expression of MgdA. The complemented plants showed almost normal levels of MGDG, although they also had abnormal morphological phenotypes, including reduced chlorophyll content, no apical dominance in shoot growth, atypical flower development, and infertility. These observations provide new insights regarding the importance of regulated MGDG synthesis in the physiology of higher plants.

Insights into the DNA stabilizing contributions of a bicyclic cytosine analogue: crystal structures of DNA duplexes containing 7,8-dihydropyrido [2,3-d]pyrimidin-2-one.

The incorporation of the bicyclic cytosine analogue 7,8-dihydropyrido[2,3-d]pyrimidin-2-one (X) into DNA duplexes results in a significant enhancement of their stability (3-4 K per modification). To establish the effects of X on the local hydrogen-bonding and base stacking interactions and the overall DNA conformation, and to obtain insights into the correlation between the structure and stability of X-containing DNA duplexes, the crystal structures of [d(CGCGAATT-X-GCG)](2) and [d(CGCGAAT-X-CGCG)](2) have been determined at 1.9-2.9 Å resolutions. In all of the structures, the analogue X base pairs with the purine bases on the opposite strands through Watson-Crick and/or wobble type hydrogen bonds. The additional ring of the X base is stacked on the thymine bases at the 5'-side and overall exhibits greatly enhanced stacking interactions suggesting that this is a major contribution to duplex stabilization.

Archaeological application of airborne LiDAR to examine social changes in the Ceibal region of the Maya lowlands.

Although the application of LiDAR has made significant contributions to archaeology, LiDAR only provides a synchronic view of the current topography. An important challenge for researchers is to extract diachronic information over typically extensive LiDAR-surveyed areas in an efficient manner. By applying an architectural chronology obtained from intensive excavations at the site center and by complementing it with surface collection and test excavations in peripheral zones, we analyze LiDAR data over an area of 470 km2 to trace social changes through time in the Ceibal region, Guatemala, of the Maya lowlands. We refine estimates of structure counts and populations by applying commission and omission error rates calculated from the results of ground-truthing. Although the results of our study need to be tested and refined with additional research in the future, they provide an initial understanding of social processes over a wide area. Ceibal appears to have served as the only ceremonial complex in the region during the transition to sedentism at the beginning of the Middle Preclassic period (c. 1000 BC). As a more sedentary way of life was accepted during the late part of the Middle Preclassic period and the initial Late Preclassic period (600-300 BC), more ceremonial assemblages were constructed outside the Ceibal center, possibly symbolizing the local groups' claim to surrounding agricultural lands. From the middle Late Preclassic to the initial Early Classic period (300 BC-AD 300), a significant number of pyramidal complexes were probably built. Their high concentration in the Ceibal center probably reflects increasing political centralization. After a demographic decline during the rest of the Early Classic period, the population in the Ceibal region reached the highest level during the Late and Terminal Classic periods, when dynastic rule was well established (AD 600-950).

[The effects of an exercise program for the female elderly in the community].

In Mizumaki-cho, Fukuoka, a "School of muscle-building for the elderly" was held by the self-help group "MIZUMAKI Iki-iki senior club" once a week from Sep. 2002 to Mar. 2004. This school program included stretching, aerobics and resistance exercises. In this study, we clarified the effect of exercise for the 38 elderly females in this school. Their average age was 65.8 years old. Blood pressure, BMI, body %Fat, VO2 max, grasping power, time of standing on one leg with eyes open, anteflexion while sitting, time of walking for 10 m and time of standing up from sitting on a chair were measured before starting school, after 6 months, 12 months and 18 months. Every measured value except BMI and VO2 max was improved, and these improvements continued for 18 months. Especially, it was shown that time of standing on one leg with eyes open, time of standing up from sitting on a chair and time of walking for 10 m improved by 121.6%, 112.7%, 30.4%, respectively, compared with each measured value at the start. These improvements might produce the effect of fall prevention for the elderly. From the results of this study, it was clarified that regular exercise builds up the muscles of the female elderly, and continuation of exercise also extends the effect of exercise for the female elderly.

Objective image analysis of the meibomian gland area.

AIMS: To evaluate objectively the meibomian gland area using newly developed software for non-invasive meibography. METHODS: Eighty eyelids of 42 patients without meibomian gland loss (meiboscore=0), 105 eyelids of 57 patients with loss of less than one-third total meibomian gland area (meiboscore=1), 13 eyelids of 11 patients with between one-third and two-thirds loss of meibomian gland area (meiboscore=2) and 20 eyelids of 14 patients with two-thirds loss of meibomian gland area (meiboscore=3) were studied. Lid borders were automatically determined. The software evaluated the distribution of the luminance and, by enhancing the contrast and reducing image noise, the meibomian gland area was automatically discriminated. The software calculated the ratio of the total meibomian gland area relative to the total analysis area in all subjects. Repeatability of the software was also evaluated. RESULTS: The mean ratio of the meibomian gland area to the total analysis area in the upper/lower eyelids was 51.9±5.7%/54.7±5.4% in subjects with a meiboscore of 0, 47.7±6.0%/51.5±5.4% in those with a meiboscore of 1, 32.0±4.4%/37.2±3.5% in those with a meiboscore of 2 and 16.7±6.4%/19.5±5.8% in subjects with a meiboscore of 3. CONCLUSIONS: The meibomian gland area was objectively evaluated using the developed software. This system could be useful for objectively evaluating the effect of treatment on meibomian gland dysfunction.

Topical diquafosol for patients with obstructive meibomian gland dysfunction.

AIMS: To evaluate the effect of topical diquafosol in patients with meibomian gland dysfunction (MGD) using tear film parameters and quantitatively analyse the meibomian gland morphology. SUBJECTS AND METHODS: The subjects were 19 eyes of 10 patients diagnosed with obstructive MGD. All subjects were given 3% diquafosol ophthalmic solution with instructions to use one drop four times a day. Ocular symptoms were scored from 0 to 14. Lid margin abnormalities were scored from 0 to 4. Changes in the meibomian glands were scored using non-contact meibography (meiboscore). Superficial punctate keratopathy (SPK) was scored from 0 to 3. Meibum was graded from 0 to 3. Tear film production was evaluated by Schirmer's test. Quantitative image analysis of the meibomian glands was performed using the original software. RESULTS: 10 patients completed more than 4 months of therapy. Ocular symptoms, lid margin abnormalities, SPK score and meibum grade were decreased. Break-up time and tear film meniscus were increased. Mean ratio of the meibomian gland area was significantly increased after treatment (p<0.0001). CONCLUSIONS: Quantitative image analysis was useful for evaluating the morphological changes of the meibomian glands. Topical diquafosol therapy was effective for patients with obstructive MGD.

Phylogeny of galactolipid synthase homologs together with their enzymatic analyses revealed a possible origin and divergence time for photosynthetic membrane biogenesis.

The photosynthetic membranes of cyanobacteria and chloroplasts of higher plants have remarkably similar lipid compositions. In particular, thylakoid membranes of both cyanobacteria and chloroplasts are composed of galactolipids, of which monogalactosyldiacylglycerol (MGDG) is the most abundant, although MGDG biosynthetic pathways are different in these organisms. Comprehensive phylogenetic analysis revealed that MGDG synthase (MGD) homologs of filamentous anoxygenic phototrophs Chloroflexi have a close relationship with MGDs of Viridiplantae (green algae and land plants). Furthermore, analyses for the sugar specificity and anomeric configuration of the sugar head groups revealed that one of the MGD homologs exhibited a true MGDG synthetic activity. We therefore presumed that higher plant MGDs are derived from this ancestral type of MGD genes, and genes involved in membrane biogenesis and photosystems have been already functionally associated at least at the time of Chloroflexi divergence. As MGD gene duplication is an important event during plastid evolution, we also estimated the divergence time of type A and B MGDs. Our analysis indicated that these genes diverged -323 million years ago, when Spermatophyta (seed plants) were appearing. Galactolipid synthesis is required to produce photosynthetic membranes; based on MGD gene sequences and activities, we have proposed a novel evolutionary model that has increased our understanding of photosynthesis evolution.

A complete terrestrial radiocarbon record for 11.2 to 52.8 kyr B.P.

Radiocarbon ((14)C) provides a way to date material that contains carbon with an age up to ~50,000 years and is also an important tracer of the global carbon cycle. However, the lack of a comprehensive record reflecting atmospheric (14)C prior to 12.5 thousand years before the present (kyr B.P.) has limited the application of radiocarbon dating of samples from the Last Glacial period. Here, we report (14)C results from Lake Suigetsu, Japan (35°35'N, 135°53'E), which provide a comprehensive record of terrestrial radiocarbon to the present limit of the (14)C method. The time scale we present in this work allows direct comparison of Lake Suigetsu paleoclimatic data with other terrestrial climatic records and gives information on the connection between global atmospheric and regional marine radiocarbon levels.

Synthesis of a novel class of glycocluster with a cyclic α-(1→6)-octaglucoside as a scaffold and their binding abilities to concanavalin A.

The synthesis of small glycoclusters with high affinity toward lectins is one of the important subjects in glycotechnology. Although cyclic α-(1→6)-d-octaglucoside (CI8) is an attractive scaffold on which to put glycosyl pendants, the compound has only secondary hydroxyl groups, which are relatively unreactive for substitution reactions. The oxidation of the vicinal diols of CI8 and reductive amination of the resultant dialdehydes with 2-aminoethyl mannoside gave mannose-CI8 conjugates with a variety of average mannose incorporation numbers (2-7). The average numbers were deduced from MALDI-TOF mass and (1)H NMR spectroscopy. The binding ability of mannose-CI8 conjugates to concanavalin A increased with the increasing numbers of average mannose incorporation, reaching a plateau at tetravalence, as estimated from a latex bead-based agglutination lectin assay. Toxicity tests demonstrated the biocompatibility of mannose-CI8 conjugates.

Crystal structures of DNA duplexes stabilized by bicyclic-C residues.

Chemical modification of nucleic acids is being studied extensively as an approach for the development of nucleic acid-based therapies. We found that a nucleotide carrying 7,8-dihydropyrido[2,3-d]pyrimidin-2-one (bicyclic-C or X), which is a cytosine derivative with a propene attached at the N4 and C5 atoms, increases the stability of DNA duplexes. To establish the conformational effects of X on DNA and to obtain insight into the correlation between the structure and stability of X-containing DNA duplexes, the crystal structures of [d(CGCGAATT-X-GCG)](2) and [d(CGCGAAT-X-CGCG)](2) have been determined at 2.9 A resolutions. In both duplexes, the bicyclic-C bases form pairs with the counter bases through hydrogen bonds, and stabilize the duplex formation in part by stacking interactions between X and the subsequent thymine base of the same strand.