Lung clearance index in adults with non-cystic fibrosis bronchiectasis

Background

Lung clearance index (LCI) is a measure of abnormal ventilation distribution derived from the multiple breath inert gas washout (MBW) technique. We aimed to determine the clinical utility of LCI in non-CF bronchiectasis, and to assess two novel MBW parameters that distinguish between increases in LCI due to specific ventilation inequality (LCI_vent) and increased respiratory dead space (LCI_ds).

Methods

Forty-three patients with non-CF bronchiectasis and 18 healthy control subjects underwent MBW using the sulphur hexafluoride wash-in technique, and data from 40 adults with CF were re-analysed. LCI_vent and LCI_ds were calculated using a theoretical two-compartment lung model, and represent the proportional increase in LCI above its ideal value due to specific ventilation inequality and increased respiratory dead space, respectively.

Results

LCI was significantly raised in patients with non-CF bronchiectasis compared to healthy controls (9.99 versus 7.28, p < 0.01), and discriminated well between these two groups (area under receiver operating curve = 0.90, versus 0.83 for forced expiratory volume in one second [% predicted]). LCI, LCI_vent and LCI_ds were repeatable (intraclass correlation coefficient > 0.75), and correlated significantly with measures of spirometric airflow obstruction.

Conclusion

LCI is repeatable, discriminatory, and is associated with spirometric airflow obstruction in patients with non-CF bronchiectasis. LCI_vent and LCI_ds are a practical and repeatable alternative to phase III slope analysis and may allow a further level of mechanistic information to be extracted from the MBW test in patients with severe ventilation heterogeneity.     

Does the silver moss Bryum argenteum exhibit sex-specific patterns in vegetative growth rate,asexual fitness or prezygotic reproductive investment?

Background and Aims

Expected life history trade-offs associated with sex differences in reproductive investment are often undetected in seed plants, with the difficulty arising from logistical issues of conducting controlled experiments. By controlling genotype, age and resource status of individuals, a bryophyte was assessed for sex-specific and location-specific patterns of vegetative, asexual and sexual growth/reproduction across a regional scale.

Methods

Twelve genotypes (six male, six female) of the dioecious bryophyte Bryum argenteum were subcultured to remove environmental effects, regenerated asexually to replicate each genotype 16 times, and grown over a period of 92 d. Plants were assessed for growth rates, asexual and sexual reproductive traits, and allocation to above- and below-ground regenerative biomass.

Key Results

The degree of sexual versus asexual reproductive investment appears to be under genetic control, with three distinct ecotypes found in this study. Protonemal growth rate was positively correlated with asexual reproduction and sexual reproduction, whereas asexual reproduction was negatively correlated (appeared to trade-off) with vegetative growth (shoot production). No sex-specific trade-offs were detected. Female sex-expressing shoots were longer than males, but the sexes did not differ in growth traits, asexual traits, sexual induction times, or above- and below-ground biomass. Males, however, had much higher rates of inflorescence production than females, which translated into a significantly higher (24x) prezygotic investment for males relative to females.

Conclusions

Evidence for three distinct ecotypes is presented for a bryophyte based on regeneration traits. Prior to zygote production, the sexes of this bryophyte did not differ in vegetative growth traits but significantly differed in reproductive investment, with the latter differences potentially implicated in the strongly biased female sex ratio. The disparity between males and females for prezygotic reproductive investment is the highest known for bryophytes.     

Ferreting out stem cells from their niches

Over the past decade, it has become increasingly clear that many tissues have regenerative capabilities. The challenge has been to find the stem cells or progenitors that are responsible for tissue renewal and repair. The revolution in technological advances that permit sophisticated spatial, temporal and kinetic analyses of stem cells has allowed stem cell hunters to ferret out where stem cells live, and to monitor when they come and go from these hiding places.     

Mannitol in six autotrophic stramenopiles and Micromonas

Mannitol plays a central role in brown algal physiology since it represents an important pathway used to store photoassimilate. Several specific enzymes are directly involved in the synthesis and recycling of mannitol, altogether forming the mannitol cycle. The recent analysis of algal genomes has allowed tracing back the origin of this cycle in brown seaweeds to a horizontal gene transfer from bacteria, and furthermore suggested a subsequent transfer to the green micro-alga Micromonas. Interestingly, genes of the mannitol cycle were not found in any of the currently sequenced diatoms, but were recently discovered in pelagophytes and dictyochophytes. In this study, we quantified the mannitol content in a number of ochrophytes (autotrophic stramenopiles) from different classes, as well as in Micromonas. Our results show that, in accordance with recent observations from EST libraries and genome analyses, this polyol is produced by most ochrophytes, as well as the green alga tested, although it was found at a wide range of concentrations. Thus, the mannitol cycle was probably acquired by a common ancestor of most ochrophytes, possibly after the separation from diatoms, and may play different physiological roles in different classes.Key words: algae, stramenopiles, mannitol cycle, primary metabolism, osmotic stress, evolutionBrown algae produce mannitol directly from the photoassimilate fructose-6-phosphate. Its metabolism occurs through the mannitol cycle, which involves four enzymatic reactions: (1) the reduction of fructose-6-phosphate (F6P) to mannitol-1-phosphate (M1P) via the activity of an M1P dehydrogenase (M1PDH); (2) the production of mannitol from M1P via an M1P phosphatase (M1Pase); (3) the oxidation of mannitol via the activity of a mannitol-2-dehydrogenase (M2DH) yielding fructose; and (4) the phosphorylation of fructose yielding F6P and involving a hexokinase (HK).^1,2 The first completed draft of a brown algal genome enabled the identification of candidate genes for each of these steps.³ As these genes were not found in the genomes of the diatoms Thalassiosira pseudonana and Phaeodactylum tricornutum, mannitol metabolism in stramenopiles was considered a trait typical for brown algae. The corresponding genes were thought to have been acquired horizontally from bacteria and subsequently transferred to some green algae.⁴ Recently, however, homologs of several genes of the cycle were also found in the genome of the pelagophyte Aureococcus anophagefferens⁵ and an EST library produced for the dictyochophyte Pseudochattonella farcimen (Dittami et al. personal communication). These observations prompted us to examine the presence of mannitol in a range of strains covering different classes of autotrophic stramenopiles (ochrophytes). In addition, because of the identification of genes encoding enzymes for the production of mannitol through the mannitol cycle in the green alga Micromonas, one strain of this genus was also included in our analysis.     

ONTOGENETIC ANALYSIS OF TREE ROOTS IN ACER RUBRUM AND BETULA PAPYRIFERA

The development of long (6-20 m) tree roots was reconstructed from serial transverse sections taken 10-20 cm apart. Measurements of primary xylem diameter showed that the tips of long roots of red maple (Acer rubrum L.) and paper birch (Betula papyrifera Marsh.) are initially small, but they increase in diameter with increasing distance from the stem. A repeating pattern of the width of the first annual ring marks length increments of long roots. The pattern of ring width is paralleled by a pattern of primary xylem diameter. Our interpretation is that primary xylem diameter increases during spring and early summer, stays constant during late summer and decreases in autumn. After injuries to large root tips, new large lateral tips are formed that replace the parent tip. Thus, a single long root is actually formed by a succession of these replacement roots. In a series of sections there may be sudden changes in primary xylem diameter as the successive sections pass from parent root to replacement root at points of injury. These changes in birch are associated with changes in a number of protoxylem poles.     

高温油藏内源微生物及其提高采收率潜力研究

大港孔店油田油藏特征、流体和微生物性质分析结果表明, 属于高温生态环境, 地层水矿化度较低, 氮、磷浓度低, 而且缺乏电子受体, 主要的有机物来源是油气。油田采用经过除油处理的油藏产出水回注方式开发, 油层中存在的微生物类型主要是厌氧嗜热菌, 包括发酵菌(102个/mL~105个/mL), 产甲烷菌(103个/mL); 好氧菌主要存在于注水井周围。硫酸盐还原菌(SRB)还原速率0.002 mg S2-/(L·d) ~18.9 mg S2-/(L·d), 产甲烷菌产甲烷速率0.012 mgCH4/(L·d)~16.2 mgCH4/(L·d)。好氧菌能够氧化油形成生物质, 部分氧化产物为挥发性脂肪酸和表面活性剂。产甲烷菌在油氧化菌液体培养基中产生CH4, CO2为好氧微生物和厌氧微生物的共同代谢产物。这些产物具有提高原油流动性的作用。用示踪剂研究了注入水渗流方向。通过综合分析, 油藏微生物具有较大的潜力, 基于激活油层菌的提高采收率方法在该油田是可行的。     

A mitotically stable marker chromosome negative for whole chromosome libraries, centromere probes and chromosome specific telomere regions: a novel class of supernumerary marker chromosome?

A two year-old child presented with mild developmental delay. On karyotype analysis, a supernumerary small marker chromosome (SMC) was found in all cells examined. This SMC was approximately the size of an isochromosome 18p, being symmetrical with a central constriction. C-banding and silver staining were negative and FISH with all chromosome-specific paints, centromere probes and telomere probes showed no hybridization to the SMC; telomere repeat sequences were however present on both arms. Comparative genomic hybridization showed no amplification of any chromosome region. Flow sorting of the SMC and reverse painting onto normal metaphase spreads showed no hybridization to any chromosome, whereas reverse painting onto the patient's own metaphases showed hybridization to the SMC only. This SMC may thus represent either a complex amplicon of different genomic regions, or a multifold amplification of a very small region, with a neocentromere comprising an active kinetochore but no alphoid DNA. Prognostic implications for the proband were difficult to assess due to the absence of reports of similar marker chromosomes in the literature.     

Evolutionary trend in feeding habits of <Emphasis Type="Italic">Girella</Emphasis> (Perciformes: Girellidae)

Although some Girella species are herbivorous, having basically tricuspid teeth, some are omnivorous. To determine the evolutionary trends in feeding habits of Girella, the phylogenetic relationships of several species of Girella were estimated by partially sequencing the mitochondrially encoded NADH dehydrogenase subunit 2 gene, and the dentition and adductor mandibulae complex of each species were examined. The cladogram determined from the mitochondrial DNA analysis indicated that multiple tooth-rows containing incisor-like teeth existed in adults of the ancestral species of Girella, species with a single tooth-row of tricuspid teeth in the adult stage having diverged subsequently on several occasions. The tendinous connections between each section of the adductor mandibulae complex are believed to have been simple in the ancestral species, more complicated connections also having diverged later on several occasions. Multiple tooth-rows containing incisor-like teeth and the simple adductor mandibulae complex are deduced as adaptations to herbivory; on the other hand, a single tooth-row of tricuspid teeth and the complicated adductor mandibulae complex are deduced as adaptations to omnivory. Therefore, the ancestral species of Girella is suggested as having been adapted to herbivory, with species adapted to omnivory having diverged on several subsequent occasions.     

Conservation of heterochromatin protein 1 function

Heterochromatin represents a cytologically visible state of heritable gene repression. In the yeast, Schizosaccharomyces pombe, the swi6 gene encodes a heterochromatin protein 1 (HP1)-like chromodomain protein that localizes to heterochromatin domains, including the centromeres, telomeres, and the donor mating-type loci, and is involved in silencing at these loci. We identify here the functional domains of swi6p and demonstrate that the chromodomain from a mammalian HP1-like protein, M31, can functionally replace that of swi6p, showing that chromodomain function is conserved from yeasts to humans. Site-directed mutagenesis, based on a modeled three-dimensional structure of the swi6p chromodomain, shows that the hydrophobic amino acids which lie in the core of the structure are critical for biological function. Gel filtration, gel overlay experiments, and mass spectroscopy show that HP1 proteins can self-associate, and we suggest that it is as oligomers that HP1 proteins are incorporated into heterochromatin complexes that silence gene activity.