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PubMed2003

Molecular phylogenetics of Houstonia (Rubiaceae): descending aneuploidy and breeding system evolution in the radiation of the lineage across North America.

Nuclear and chloroplast DNA sequence variation was used to infer evolutionary relationships within and among members of Houstonia (Rubiaceae) and other closely related genera in North America. Sequences from the internal transcribed spacer (ITS) of the nrDNA and a cpDNA intron in the trnL gene were used to reconstruct phylogenetic relationships of 30 species of Houstonia and closely related genera. The data suggest that the North American species of Houstonia are not monophyletic, but belong to the same lineage as Stenaria. The radiation of this lineage has been accompanied by changes in the basic chromosome number of the major clades through descending aneuploidy. This loss of chromosomes was also associated with northward colonization of North America. However, other characters, such as an annual versus perennial habit, heterostylous and homostylous breeding systems, and the evolution of self fertilization, seem to be labile throughout the lineage, originating multiple times throughout the evolutionary history of the lineage.

Aneuploidy↗
PubMed2006

Impulsive responding on the peak-interval procedure.

The pattern of responding on a peak-interval timing task allows one to make inferences regarding the sources of variation that contribute to interval timing behavior. Non-temporal factors such as impulsivity may impact the validity of these inferences. Rats were trained on a 15s peak-interval procedure (PI) or a mixed 15s behaviorally dependent variable-interval, 15s peak-interval procedure (bdVIPI) for an extended number of sessions. Extended training on the PI revealed a bi-modal distribution in the times at which subjects started responding for temporally predictable reinforcement, suggesting that multiple processes contribute to the behavioral pattern obtained in this procedure. Training on the bdVIPI eliminated the early mode of this bi-modal distribution, thereby decreasing the variation in start times. These results suggest that alternative response options can modulate the influence of impulsivity in timing tasks.

Animals↗
PubMed1996

Phylogenetic analysis of apiaceae subfamily apioideae using nucleotide sequences from the chloroplast rpoC1 intron.

Phylogenetic relationships among 25 members of Apiaceae (Umbelliferae) subfamily Apioideae, representing 7 of the 8 tribes and 8 of the 10 subtribes traditionally recognized in the subfamily, and 5 outgroups from Apiaceae subfamilies Hydrocotyloideae and Saniculoideae and allied families Araliaceae and Pittosporaceae have been inferred from nucleotide sequence variation in the intron of the chloroplast gene RNA polymerase C1 (rpoC1). Sequence divergence values in pairwise comparisons of unambiguous positions among all taxa ranged from 0 to 11.3% of nucleotides and averaged 3.8%. Trees derived from rpoC1 intron sequences estimated using maximum parsimony or maximum likelihood methods are of essentially similar topology, and indicate that (1) subfamily Apioideae, with Heteromorpha as its most basal element, is monophyletic and is a sister-group to Eryngium, the only representative examined of Apiaceae subfamily Saniculoideae, (2) Aralia (Araliaceae) arises from within a paraphyletic Apiaceae subfamily Hydrocotyloideae (represented by Centella and Hydrocotyle) and this clade is a sister-group to Apioideae+Saniculoideae, (3) there is a major phylogenetic division within Apioideae (excluding the basal Heteromorpha), with one clade comprising the genus Smyrnium and those taxa traditionally grouped in tribes Dauceae, Scandiceae, and Laserpitieae, and the other clade comprising all other examined taxa, and (4) relationships within each of these 2 major clades of Apioideae are largely equivocal owing to the low levels of nucleotide sequence divergence observed. Although rpoC1 intron sequences can provide valuable characters for addressing phylogenetic relationships among the outgroups and distantly related members of Apioideae, they have little power for resolving relationships among closely related taxa.

Base Sequence↗
PubMed1999

A molecular phylogeny of Lilium in the internal transcribed spacer region of nuclear ribosomal DNA.

Phylogenetic relationships among 55 species of Lilium, Cardiocrinum giganteum, and Nomocharis saluenensis were inferred from nucleotide sequence variations in the internal transcribed spacer (ITS) regions of 18S-25S nuclear ribosomal DNA. The phylogeny derived from ITS sequences estimated using maximum-likelihood methods indicated that (1) most of the species construct their own clade according to the classification based on morphological features at the section level; (2) section Daurolirion is not independent of Sinomartagon, and it is appropriate to integrate two sections as Sinomartagon; (3) it is appropriate that L. henryi and L. bulbiferum are classified into subsection 6a and Sinomartagon-Daurolirion, respectively; (4) subsection 6b is much closer to Sinomartagon than subsection 6a and Archelirion, and it arose directly from Sinomartagon; and (5) Lilium is much closer to Nomocharis than Cardiocrinum. Phylogenetic estimation using sequences of the ITS region is suitable at the levels of genus, section, and most of subsection.

Base Sequence↗
PubMed1995

Do children have a theory of race?

In recent years a number of studies have detailed young children's enriched, domain-specific, and theory-like understanding in several cognitive domains, including naive biology, naive psychology, and reasoning about physical objects. With few exceptions, students of cognition have not considered the possibility that the acquisition and representation of social categories may also be governed by a specialized faculty for understanding. Rather, most accounts of children's social categorization assume that the classification of the human realm is derived from observations of superficial differences in appearance and does not include expectations of deeper commonalities among category members. Five experiments are reported that challenge this view. The results indicate that young children's inferences about human racial variation involve domain-specific reasoning that parallels but is distinct from common sense understanding of naive biology. These findings have implications for our understanding of the transfer of knowledge across domains and for determining the appropriate level of description of domain-specific devices.

Adult↗
PubMed2000

Review of nitrogen and phosphorus metabolism in seagrasses.

Within the past few decades, major losses of seagrass habitats in coastal waters impacted by cultural eutrophication have been documented worldwide. In confronting a pressing need to improve the management and protection of seagrass meadows, surprisingly little is known about the basic nutritional physiology of these critical habitat species, or the physiological mechanisms that control their responses to N and P gradients. The limited available evidence to date already has revealed, for some seagrass species such as the north temperate dominant Zostera marina, unusual responses to nutrient enrichment in comparison to other vascular plants. Seagrasses derive N and P from sediment pore water (especially ammonium) and the water column (most nitrate). The importance of leaves versus roots in nutrient acquisition depends, in part, on the enrichment conditions. For example, a shift from reliance on sediment pore water to increased reliance on the overlying water for N and P supplies has been observed under progressive water-column nutrient enrichment. Seagrasses may be N-limited in nutrient-poor waters with sandy or (less so) organic sediments, and P-limited in carbonate sediments. On the basis of data from few species, seagrasses appear to have active uptake systems for NO(3)(-) and PO(4)(-3), but NH(4)(+) uptake may involve both low- and high-affinity systems. P(i) uptake affinities reported thus far are much lower than values for active ammonium uptake, but comparable to values for nitrate uptake by leaf tissues. Beyond such basic information, seagrass species have shown considerable variation in nutritional response. Dominance of acropetal versus basipetal nutrient translocation appears to vary among species as an innate trait. While some species follow classic Michaelis-Menten kinetics for N(i) uptake, others have exhibited sustained linear uptake with limited or negligible product feedback inhibition, perhaps in adaptation to oligotrophic environments. Zostera marina also is able to maintain nitrate reductase (NR) activity during dark periods if adequate carbohydrate reserves and substrate are available. Thus, this species can respond to nitrate pulses throughout a diel cycle, rather than being limited as most plants to nitrate uptake during the light period. Further adaptations may have occurred for seagrasses in extremely nitrate-depauperate conditions. For example, Halophila decipiens and H. stipulacea lack inducible NR and apparently have lost the ability to reduce nitrate; and a biphasic rather than hyperbolic P(i) uptake curve, with 'surge' uptake, has been described for Zostera noltii. Many seagrasses respond favorably to low or moderate N and/or P enrichment. However, excessive N(i) loading to the water column can inhibit seagrass growth and survival, not only as an indirect effect by stimulating algal overgrowth and associated light reduction, but-for some species-as a direct physiological effect. The latter direct impact has been most pronounced for plants growing in sandy (nutrient-poor) sediments, and is exacerbated by elevated temperatures and/or light reduction. Ammonia toxicity, known for many vascular plants, has been reported in seagrasses Ruppia drepanensis and Z. marina (125 µM water-column NH(4)(+), 5 weeks). Z. marina has shown to be inhibited, as well, by pulsed water-column nitrate enrichment (as low as 3.5-7 µM NO(3)(-), 3-5 weeks), which is actively taken up without apparent product feedback inhibition. Inhibition by elevated nitrate has also been reported, with description of the underlying physiological mechanisms, in certain macroalgae and microalgae. In Z. marina, this effect has been related to the high, sustained energy demands of nitrate uptake, and to inducement of internal carbon limitation by the concomitant 'carbon drain' into amino acid assimilation. In contrast, nitrate enrichment can stimulate growth of Z. marina when the sediment, rather than the water column, is the source. Because seagrass species have shown considerable variation in nutritional response, inferences about one well-studied species, from one geographic location, should not be applied a priori to that species in other regions or to seagrasses in general. Most of the available information has been obtained from study of a few species, and the basic nutritional physiology of many seagrasses remains to be examined and compared across geographic regions. Nonetheless, the relatively recent gains in general understanding about the physiological responses of some seagrass species to nutrient gradients already have proven valuable in both basic and applied research. For example, physiological variables such as tissue C:N:P content have begun to be developed as integrative indicators of nutrient conditions and anthropogenic nutrient enrichment. To strengthen insights for management strategies to optimize seagrass survival in coastal waters adjacent to exponential human population growth and associated nutrient inputs, additional emphasis is critically needed to assess the role of variable interactions-among inorganic as well as organic N, P and C, environmental factors such as temperature, light, and other community components-in controlling the physiology, growth and survival of these ecologically important marine angiosperms.

Journal Article↗
PubMed1999

Temporal and spatial biomonitoring of heavy metals in Hong Kong coastal waters using Tetraclita squamosa.

The barnacle Tetraclita squamosa (Crustacea: Cirripedia) was collected from 11 sites in the coastal waters of Hong Kong during three consecutive seasons, i.e. summer 1996, winter 1996-1997 and summer 1997. Barnacle soft tissues were analysed for cadmium, copper, manganese, iron and zinc using inductively coupled plasma atomic emission spectrophotometry. Analysis of covariance allowed inter-seasonal (temporal) and inter-site (spatial) comparisons of soft tissue metal concentrations to be made, from which bioavailabilities to T. squamosa have been inferred. Inter-seasonal variation was not greater than intra-seasonal and, therefore, seasonal variation in soft tissue metal concentrations can be considered relatively unimportant. Data were, however, characterised by high temporal variability. Spatial variation in metal bioavailabilities were consistent with earlier studies: cadmium soft tissue concentrations were elevated in barnacles collected from low salinity western waters, while copper and zinc concentrations were elevated in the urban-fringed central waters, in particular at one site, i.e. Aberdeen. In general, metal concentrations were much lower in barnacles collected from eastern water sites.

Journal Article↗
PubMed2003

Stable isotopic evidence for methane seeps in Neoproterozoic postglacial cap carbonates.

The Earth's most severe glaciations are thought to have occurred about 600 million years ago, in the late Neoproterozoic era. A puzzling feature of glacial deposits from this interval is that they are overlain by 1-5-m-thick 'cap carbonates' (particulate deep-water marine carbonate rocks) associated with a prominent negative carbon isotope excursion. Cap carbonates have been controversially ascribed to the aftermath of almost complete shutdown of the ocean ecosystems for millions of years during such ice ages--the 'snowball Earth' hypothesis. Conversely, it has also been suggested that these carbonate rocks were the result of destabilization of methane hydrates during deglaciation and concomitant flooding of continental shelves and interior basins. The most compelling criticism of the latter 'methane hydrate' hypothesis has been the apparent lack of extreme isotopic variation in cap carbonates inferred locally to be associated with methane seeps. Here we report carbon isotopic and petrographic data from a Neoproterozoic postglacial cap carbonate in south China that provide direct evidence for methane-influenced processes during deglaciation. This evidence lends strong support to the hypothesis that methane hydrate destabilization contributed to the enigmatic cap carbonate deposition and strongly negative carbon isotopic anomalies following Neoproterozoic ice ages. This explanation requires less extreme environmental disturbance than that implied by the snowball Earth hypothesis.

Animals↗
PubMed2006

Episodic growth of the Gondwana supercontinent from hafnium and oxygen isotopes in zircon.

It is thought that continental crust existed as early as 150 million years after planetary accretion, but assessing the rates and processes of subsequent crustal growth requires linking the apparently contradictory information from the igneous and sedimentary rock records. For example, the striking global peaks in juvenile igneous activity 2.7, 1.9 and 1.2 Gyr ago imply rapid crustal generation in response to the emplacement of mantle 'super-plumes', rather than by the continuous process of subduction. Yet uncertainties persist over whether these age peaks are artefacts of selective preservation, and over how to reconcile episodic crust formation with the smooth crustal evolution curves inferred from neodymium isotope variations of sedimentary rocks. Detrital zircons encapsulate a more representative record of igneous events than the exposed geology and their hafnium isotope ratios reflect the time since the source of the parental magmas separated from the mantle. These 'model' ages are only meaningful if the host magma lacked a mixed or sedimentary source component, but the latter can be diagnosed by oxygen isotopes, which are strongly fractionated by rock-hydrosphere interactions. Here we report the first study that integrates hafnium and oxygen isotopes, all measured in situ on the same, precisely dated detrital zircon grains. The data reveal that crust generation in part of Gondwana was limited to major pulses at 1.9 and 3.3 Gyr ago, and that the zircons crystallized during repeated reworking of crust formed at these times. The implication is that the mechanisms of crust formation differed from those of crustal differentiation in ancient orogenic belts.

Journal Article↗
PubMed2002

Assessing sanitary landfill stabilization using winter and summer waste streams in simulated landfill cells.

This study was undertaken to provide a better understanding and to further define the stabilization processes involved in a typical municipal landfill representative of the city of Calgary, Canada, area. The objectives of this study were: (1) to characterize the composition of the solid waste constituents entering the landfill site, (2) to assess the relative decomposition of various waste components in the simulated test cells, (3) to parametize selected chemical and physical changes occurring during the stabilization process and (4) to determine water absorptive capacity of the different waste constituents. The results of the long term landfill stabilization using simulated landfill cell systems filled with winter and summer waste streams, respectively, have illustrated the potential changes that may occur with time with such systems. Based on the results, it can be inferred that the seasonal variation in waste composition deposited in a landfill will likely effect the rate of decomposition and settlement, chemical and physical characteristics of the leachate, moisture sorbing capacity of the site as well as variation in seasonal contaminants. Assuming that the results from the simulated landfills used during this study can be extrapolated to larger-scale landfill operations, it seems that summer waste streams pose a higher pollution threat to the environment than winter waste streams. The several trends observed in this study and the conclusions reported herein would have wide applications in landfill management.

Adsorption↗
PubMed2005

Widespread recombination throughout Wolbachia genomes.

Evidence is growing that homologous recombination is a powerful source of genetic variability among closely related free-living bacteria. Here we investigate the extent of recombination among housekeeping genes of the endosymbiotic bacteria Wolbachia. Four housekeeping genes, gltA, dnaA, ftsZ, and groEL, were sequenced from a sample of 22 strains belonging to supergroups A and B. Sequence alignments were searched for recombination within and between genes using phylogenetic inference, analysis of genetic variation, and four recombination detection programs (MaxChi, Chimera, RDP, and Geneconv). Independent analyses indicate no or weak intragenic recombination in ftsZ, dnaA, and groEL. Intragenic recombination affects gltA, with a clear evidence of horizontal DNA transfers within and between divergent Wolbachia supergroups. Intergenic recombination was detected between all pairs of genes, suggesting either a horizontal exchange of a genome portion encompassing several genes or multiple recombination events involving smaller tracts along the genome. Overall, the observed pattern is compatible with pervasive recombination. Such results, combined with previous evidence of recombination in a surface protein, phage, and IS elements, support an unexpected chimeric origin of Wolbachia strains, with important implications for Wolbachia phylogeny and adaptation of these obligate intracellular bacteria in arthropods.

Bacterial Proteins↗
PubMed2002

Phylogeny of Gaertnera Lam. (Rubiaceae) based on multiple DNA markers: evidence of a rapid radiation in a widespread, morphologically diverse genus.

Phylogenetic relationships among 28 of the 68 species of the paleotropical genus Gaertnera (Rubiaceae) and two related genera were inferred from nucleotide sequence variation in four nuclear DNA (nDNA) markers: the internal transcribed spacers of nuclear rDNA (ITS), the large and small copies of phosphoenolpyruvate carboxylase (PepC-large and PepC-small), and triose phosphate isomerase (Tpi). Phylogenetic analysis of the combined nDNA dataset suggested that Gaertnera is monophyletic, but genetic variation among species was insufficient to reconstruct well-supported relationships within the genus. This was counter to expectations based on the very distinct morphologies and widespread distribution of the genus (West Africa to Sulawesi). Molecular clock analyses suggested variable dates of origin for Gaertnera depending upon the calibration method used. The most plausible calibration implies that Gaertnera migrated to Africa during the early Tertiary, possibly via a boreotropical land bridge and suggests that Gaertnera started to radiate 5.21 +/- 0.14 million years ago. This implies that range expansion in the group has occurred via a number of long-distance dispersal events rather than vicariance. The molecular clock estimate in turn estimated an unusually rapid lineage diversification rate within the radiation of 0.717-0.832 species/million years, comparable to those estimated for radiations on oceanic islands. Although low interspecific competition levels may have contributed to the diversification of Gaertnera on Mauritius, the mechanisms driving the rapid radiation of the group in other parts of its range remain elusive.

Base Sequence↗
PubMed2004

Lifetime fitness of short- and long-distance dispersing great reed warblers.

Dispersal is of prime importance for many evolutionary processes and has been studied for decades. The reproductive consequences of dispersal have proven difficult to study, simply because it is difficult to keep track of dispersing individuals. In most previous studies evaluating the fitness effects of dispersal, immigrants at a study locality have been lumped into one category and compared to philopatric individuals. This is unfortunate, because there are reasons to believe that immigrants with long and short dispersal distances may differ substantially in reproductive success. In the present study, we used a combination of capture-recapturing and multilocus microsatellite genotyping to categorize great reed warblers at our Swedish study site as philopatric individuals or short- or long-distance dispersing immigrants. We then performed novel comparisons of lifetime reproductive success (LRS) and survival rates of these three dispersal categories. The birds belonged to cohorts 1987-1996, and data for their LRS were gathered between 1988 and 2003. The analyses showed that philopatric males attracted more females, produced more fledglings and recruits throughout their lives, and survived better than immigrants. Among the immigrant males, those categorized as long-distance dispersers had lowest LRS and survival probability. Models that included covariates of potential importance showed that the difference in LRS between dispersal categories was partly caused by corresponding variation in number of breeding years at our study site. These results indicate that short- and, in particular, long-distance dispersers were of poor phenotypic quality, but it may also be proposed that immigrants attracted few females because they were poorly adapted to the local social environment. In females, the number of local recruits corrected for the number of breeding years (as well as for number of fledglings) differed between dispersal categories in a pattern that suggests an intermediate optimal dispersal distance. Short-distance dispersers recruited more offspring per year (and per fledgling) than both philopatric individuals and long-distance dispersers. Data suggest that the low LRS of philopatric females was related to costs of inbreeding. The low LRS of long-distance dispersing females may have resulted from their offspring being especially prone to disperse outside the study area, but also other potential explanations exist, such as local maladaptation. Our study highlights the importance of separating immigrant birds on the basis of their genetic similarity to the local study population when analyzing variation in LRS and inferring realized gene flow.

Animals↗
PubMed2006

Late Quaternary history of Hippophaë rhamnoides L. (Elaeagnaceae) inferred from chalcone synthase intron (Chsi) sequences and chloroplast DNA variation.

Fossil pollen records indicate that Hippophaë rhamnoides (Sea Buckthorn) was widespread on late- and early postglacial raw soils throughout much of central and northern Europe, but that Early Holocene reforestation restricted populations to northern coastal habitats, or along mountain streams in the Alps, Pyrenees, and Carpathians. We used sequence variation at the nuclear chalcone synthase intron (Chsi), in conjunction with chloroplast DNA-restriction fragment length polymorphism data, to investigate the intraspecific phylogeny, phylogeographic structure, and expansion demographic history of this dioecious and wind-pollinated shrub at its range-wide scale in Europe and Asia Minor. Four major Chsi phylogroups of unresolved relationships were identified with estimated divergences approximately 172,000 years ago. Large-scale phylogeographic structures of nuclear and cytoplasmic markers were congruent in identifying (i) southeastern Europe as the most likely source of colonization into central Europe and Scandinavia, and (ii) the area just north of the Alps as a contact zone between populations from the Alps and the east/central European-Scandinavian lineage. Coalescence-based analyses (i.e. nested clade analysis and mismatch distributions) of Chsi variation were able to detect at least four major episodes of population growth, all within about the last 40,000 years. In particular, these analyses identified a nearly synchronized timing of population expansions in various parts of the species' range in central-eastern Europe/Asia Minor, most likely correlating with the Younger Dryas Stadial ( approximately 13,000-11,600 years ago). It remains to be established whether the phylogeographic history of H. rhamnoides, and particularly its rapid response to the rapid environmental changes of the Younger Dryas cold snap, is unique to the species, or whether it is shared with other cold-tolerant shrub (or grassland) species known from late-glacial raw soils in Europe.

Acyltransferases↗
PubMed2004

Methods for the analysis of bleeding outcomes in randomized trials of PLT transfusion triggers.

BACKGROUND: A number of methodologic challenges arise in the analysis of bleeding data from clinical trials of PLT transfusion triggers. It is important to understand the assumptions and role of the various methods of analysis to interpret published trials and to design future studies appropriately. STUDY DESIGN AND METHODS: The methods of analysis used for testing the effectiveness and safety of transfusion strategies are reviewed from several recent PLT transfusion trigger trials. The underlying assumptions of these methods are discussed, as well as the clinical interpretations of the resulting summary statistics. Four methods of analysis were applied to data from a large PLT transfusion trigger study to illustrate the differences in the interpretations that can arise from various approaches. RESULTS: PLT transfusion trigger trials of patients with leukemia have based their primary analyses on 1) simple dichotomous classifications of whether or not at least 1 day of clinically important bleeding was experienced; 2) the time to the first day of clinically important bleeding; and 3) the proportion of days at risk with clinically important bleeding. Recurrent event methods provide a robust alternative approach to the analysis of this kind of data and should be considered if interest is in capturing the overall burden of bleeding over time. These four methods differ in the extent to which they utilize information on the number of days with bleeding and the temporal variation in bleeding patterns. Inferences drawn regarding the relative safety and efficacy of different transfusion triggers can vary depending on the method of analysis. CONCLUSION: To rigorously design and analyze future PLT transfusion studies based on bleeding outcomes, it is important to have a clear understanding of the interpretation of the different ways of analyzing bleeding outcomes. The analysis strategy should be selected based on the clinical question being addressed.

Hemorrhage↗
PubMed2001

Bioacoustic spatial perception by humans: a controlled laboratory measurement of spatial resolution without distal cues.

The angular spatial resolution of a wide-angle air sonar using a continuous transmission frequency-modulated radiation, with the output coupled binaurally to the auditory system of a user, was measured under restrained controlled conditions. This was done to determine the effect of adding a narrow central field of view of 9 deg to a wide-angle sonar. The target objects were three equidistant vertical rods initially spaced apart by 10 deg. This was varied down to a spacing of 4 deg. Ten nonvisual subjects achieved an angular resolution of 6 deg. Four of these ten subjects continued learning to achieve an unexpected spatial resolution of 4 deg within the 9 deg central field. A mean error of approximately 1 deg in direction accuracy was achieved. It is inferred that the unique variations in the octave band ultrasonic echoes within the narrow field, and the invariance of the on-axis echo as one's head is turned, enables this angular resolution and accuracy to be achieved within the wide binaural field of view of 50 deg. This ability to resolve specula objects within a narrow angular resolution element of 9 deg is linked to the bat's ability to seemingly resolve object glints within a distal resolution element of less than 2 wavelengths.

Acoustic Stimulation↗
PubMed1997

Phylogenetic and genomic relationships in the genus Glycine Willd. based on sequences from the ITS region of nuclear rDNA.

Phylogenetic relationships among all 18 species of the genus Glycine were inferred from nucleotide sequence variation in the internal transcribed spacer (ITS) region of nuclear ribosomal DNA. Pairwise sequence divergence values ranged from 0.2% (a single nucleotide) between Glycine max and Glycine soja to 8.6% between Glycine hirticaulis and Glycine falcata. The length of the ITS1 and ITS2 sequences ranged from 215 to 238 nucleotides and from 205 to 222 nucleotides, respectively, and that of 5.8S was 168 nucleotides across all the species. Phylogenetic analyses of the ITS region clearly resolved all the genomic groups that were established previously based on cytogenetic and biochemical studies. Based on this study, we assign new genome symbols: HH to Glycine arenaria, H1H1 to Glycine hirticaulis, H2H2 to Glycine pindanica, II to Glycine albicans, and I1I1 to Glycine lactovirens. Parsimony analysis of the entire ITS region, using subgenus Soja as outgroup, resulted in a trichotomy consisting of the clades: G. falcata (F genome), Glycine cyrtoloba and Glycine curvata (C genome), and all other species (A, B, D, E, H, and I genomes) of the subgenus Glycine.

Base Sequence↗
PubMed1986

Nocturnal periodic breathing at altitudes of 6,300 and 8,050 m.

Nocturnal periodic breathing was studied in eight well-acclimatized subjects living at an altitude of 6,300 m [barometric pressure (PB) 350-352 Torr] for 3-5 wk and in four subjects during one night at 8,050 m altitude (PB 281-285 Torr). The measurements at 6,300 m included tidal volume by inductance plethysmography, arterial O2 saturation by ear oximetry (calibrated by arterial blood samples), electrocardiogram (ECG), and electrooculogram. At 8,050 m, periodic breathing was inferred from the cyclical variation in heart rate obtained from a night-long ECG record. All subjects at 6,300 m altitude showed well-marked periodic breathing with apneic periods. Cycle length averaged 20.5 s with 7.9 s apnea. Minimal arterial O2 saturation averaged 63.4% corresponding to a PO2 of approximately 33 Torr, i.e., approximately 6 Torr lower than the normal value at rest during daytime. This was probably the most severe hypoxemia of the 24-h period. At 8,050 m altitude, the cycle length averaged 15.4 s, much longer than predicted by a theoretical model. Cyclical variations in heart rate caused by periodic breathing occurred in all subjects, but abnormal cardiac rhythms such as ventricular premature contractions were uncommon. The severe arterial hypoxemia caused by periodic breathing may be an important determinant of tolerance to these great altitudes.

Adult↗