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PubMed2004

Chromatographic analysis of sugars applied to the characterisation of monofloral honey.

The control of the floral quality of honey has become a priority issue as a result of the number of abuses observed and the relative ease of getting around existing control methods. We conducted chromatographic analyses of honey sugars to determine new criteria for authenticating an origin. The work involved creating databases by analysing a large number of authentic honeys from seven monofloral varieties, followed by statistical processing of the results by a principal components analysis. Differences in composition could thus be demonstrated, such as the presence of trisaccharides in fir honey, that provide an additional tool for authenticating unknown commercial honeys.

Animals↗

PubMed2003

Use of a coupled biological system to treat a chemically complex air stream.

The use of biological systems to remove contaminants from waste streams has been well documented. However, when dealing with complex waste streams, the use of one biological treatment system may not be the best alternative. When treating a complex waste stream, the use of "treatment trains" or "coupled systems" may be advantageous compared with any single biological technology. This article demonstrated that a coupled system was effective in biodegrading a chemically complex mixture of volatile organic compounds (VOCs). A bench-scale system consisting of a liquid bioreactor and a biofilter was used for the biodegradation of acetone, methanol, methyl ethyl ketone, naphthalene, alpha-pinene, and toluene. The bioreactor contained an inert solid support that immobilized a microbial population. The biofiltration portion of the system utilized the same microbial inoculum but employed Douglas fir bark as its solid support. Successful biodegradation of the complex VOC mixture was accomplished with this coupled system with an average VOC removal efficiency of 96% and VOC loading rates as high as 79 g/m3/h for inlet concentrations of > 8,000 ppmv. At elevated flow rates the liquid reactor demonstrated limited removal of some compounds, such as alpha-pinene and toluene, while maintaining excellent removal of other compounds, such as methanol and acetone. The biofilter portion of the system proved very successful in degrading the remaining toluene and alpha-pinene, thus complementing the removal from the bioreactor. This study demonstrates that coupled biological systems may be utilized for a chemically complex VOC-laden air stream that previously may not have been considered for biological treatment.

Air Pollution↗

PubMed2004

Characterization of humus microbial communities in adjacent forest types that differ in nitrogen availability.

To address the link between soil microbial community composition and soil processes, we investigated the microbial communities in forest floors of two forest types that differ substantially in nitrogen availability. Cedar-hemlock (CH) and hemlock-amabilis fir (HA) forests are both common on northern Vancouver Island, B.C., occurring adjacently across the landscape. CH forest floors have low nitrogen availability and HA high nitrogen availability. Total microbial biomass was assessed using chloroform fumigation-extraction and community composition was assessed using several cultivation-independent approaches: denaturing gradient gel electrophoresis (DGGE) of the bacterial communities, ribosomal intergenic spacer analysis (RISA) of the bacterial and fungal communities, and phospholipid fatty acid (PLFA) profiles of the whole microbial community. We did not detect differences in the bacterial communities of each forest type using DGGE and RISA, but differences in the fungal communities were detected using RISA. PLFA analysis detected subtle differences in overall composition of the microbial community between the forest types, as well as in particular groups of organisms. Fungal PLFAs were more abundant in the nitrogen-poor CH forests. Bacteria were proportionally more abundant in HA forests than CH in the lower humus layer, and Gram-positive bacteria were proportionally more abundant in HA forests irrespective of layer. Bacterial and fungal communities were distinct in the F, upper humus, and lower humus layers of the forest floor and total biomass decreased in deeper layers. These results indicate that there are distinct patterns in forest floor microbial community composition at the landscape scale, which may be important for understanding nutrient availability to forest vegetation.

Bacteria↗

PubMed2006

Relationships between stand composition and ectomycorrhizal community structure in boreal mixed-wood forests.

We investigated the community structure of ectomycorrhizal fungi under varying overstory tree compositions in the southern mixed-wood boreal forest of Quebec. Sampling took place at two locations of differing postfire ages and nine 100-m2 plots were sampled per location. The dominant overstory tree species in the plots were trembling aspen (Populus tremuloides Michx.), white birch (Betula papyrifera Marsh.) or white spruce [Picea glauca (Moench) Voss], and balsam fir [Abies balsamea (L.) Mill.]. Mycorrhizae were analyzed using morphological as well as molecular methods, employing fungal-specific primers to amplify ribosomal DNA for subsequent cloning and sequencing. A total of 1800 mycorrhizal root tips collected from the 18 plots were morphologically classified into 26 morphotypes, with Cenococcum geophilum dominating (36% of root tips). A second set of root tips, selected from the same 18 samples on which the morphological analysis was based, were analyzed using molecular methods. From this analysis, 576 cloned polymerase chain reaction products were screened by restriction fragment length polymorphism analysis and a total of 207 unique types were found. No one type dominated the system and 159 occurred only once. Sequence analysis of the types that occurred more than once revealed that Piloderma sp., Russula sp., Cortinarius sp., and Lactarius sp. were the most common mycorrhizae. The ectomycorrhizal fungal community structure revealed by the rDNA analysis differed from that observed using morphological methods. Canonical correspondence analyses of the sequenced restriction types and % overstory composition indicate that the distributions of ectomycorrhizal fungi are influenced by the relative proportions of host tree species. The distinct fungal assemblages found in the different plots supported by the different combinations of host tree species provides further support for the need to conserve stand diversity in the southern boreal forest.

DNA, Fungal↗

PubMed2000

Temporal and Spatial Distribution of the nifH Gene of N(2) Fixing Bacteria in Forests and Clearcuts in Western Oregon.

Decomposition of plant litter is a primary mechanism of nutrient recycling and redistribution in most terrestrial ecosystems. Previously we demonstrated by a nested PCR protocol that 20 distinctive nifH (the gene encoding nitrogenase reductase) HaeIII restriction fragment length polymorphism (RFLP) patterns were derived from bulk DNA associated with samples of plant litter and soil collected at one Douglas Fir (DF) forest [33]. Five of the nifH DNA patterns (II-VI) were dominant types in DF litter with characteristic fragments of 237-303 bp length, whereas samples from soil contained primarily seven other patterns 131-188 bp length (IX-XV). Here we report that the 237-303 bp fragments characteristic for forest litter could generally not be detected in plant litter or soil samples collected in clearcuts that adjoin the forest sites. The same fragments (237-303 bp) were also found in the litter at this DF forest site over 16 months and were consistently found in litter at 12 other DF forest or recent (<2 yrs) clearcut sites. However, trace to none of these fragments were detected in 6 clearcut (5-10 yrs) or different forest types (oak, alder) collected over a 200 km east-west direction in western Oregon, USA. Data suggest that the logging practice in DF forests that creates a clearcut removes a unique gene pool of nitrogen-fixing microorganisms. These organisms could potentially contribute more to nitrogen fixation in forest litter than litter from natural or invasive plants that grow in clearcuts [26]. </hea

Journal Article↗

PubMed2003

Identification of Ty1-copia retrotransposons in three ectomycorrhizal basidiomycetes: evolutionary relationships and use as molecular markers.

We amplified by PCR and sequenced 46 partial Ty1- copia reverse transcriptase (RT) sequences from the ectomycorrhizal basidiomycetes Pisolithus and Laccaria bicolor and the host tree Eucalyptus globulus. Phylogenetic analyses indicated that these sequences represent a new class of Ty1- copia RT, characteristic of basidiomycetes but related to plant Ty1- copia retrotransposons. To generate fingerprints of L. bicolor strains, outward facing PCR primers annealing to RTs were designed. This method, which is a modification of the inter-retrotransposon amplified polymorphism (IRAP) analysis, enables the detection of polymorphisms or changes within the insertion sites of Ty1- copia elements in the genome. Using this method, we investigated whether the transposition of Ty1- copia elements was related to the somaclonal variation observed in L. bicolor S238, an inoculant strain used in French Douglas-fir plantations. Data indicated that no differences in the IRAP fingerprints were detected in phenotypic variants of L. bicolor S238. We reported here for the first time the presence of Ty1- copia retrotransposon sequences in basidiomycetes, which resulted in suitable targets for developing new molecular markers.

Amino Acid Sequence↗

PubMed2004

Gibberellin inhibitors improve embryogenic tissue initiation in conifers.

Somatic embryogenesis (SE), the most promising technology to multiply high-value coniferous trees from advanced breeding and genetic engineering programs, is expected to play an important role in increasing productivity, sustainability, and uniformity of future forests in the United States. For commercial use, SE technology must work with a variety of genetically diverse trees. Initiation in loblolly pine (LP; Pinus taeda L.), our main focus species, is often recalcitrant for desirable genotypes. Initiation of LP, slash pine (SP; Pinus elliottii), Douglas-fir (DF; Pseudotsuga menziesii), and Norway spruce (NS; Picea abies) were improved through the use of paclobutrazol, a gibberellin synthesis inhibitor. Paclobutrazol was effective at concentrations ranging from 0.25 mg/l to 3.0 mg/l (0.85-10.2 microM) and optimal in LP at 1.0 mg/l. Using control media (no paclobutrazol) and 0.33-1.0 mg/l paclobutrazol, initiation percentages in LP, SP, DF, and NS were improved from 37.7% to 44.2% (across experiments), 19.3% to 28.5%, 16.9% to 23.7%, and 38.8% to 48.5%, respectively. Other gibberellin inhibitors such as flurprimidol, chlormequat-Cl, and daminozide also caused statistically significant increases in LP initiation when added to the medium at concentrations of 0.34, 10.0, and 1.0 microM, respectively. No detrimental effects on subsequent embryo development were observed when 29 new initiations from medium without GA inhibitor and 28 new initiations from medium containing paclobutrazol were tracked through culture capture, liquid culture establishment, cotyledonary embryo development, and germination.

Culture Techniques↗

PubMed2004

Thuja plicata exclusion in ectomycorrhiza-dominated forests: testing the role of inoculum potential of arbuscular mycorrhizal fungi.

The ability of trees dependent on arbuscular mycorrhizal (AM) fungi to establish in ectomycorrhizal forests is unknown. On northern Vancouver Island, Canada, there are sharp boundaries between mixed red cedar (Thuja plicata)-hemlock (Tsuga heterophylla) (CH) stands, and stands of hemlock and amabilis fir (Abies amabilis) (HA). We tested differences in AM colonization of red cedar between ectomycorrhiza-dominated (HA) stands and stands containing red cedar (CH), across a range of light levels. We used a soil bioassay approach to determine whether there was sufficient AM fungal inoculum in the HA tree stands to colonize red cedar seedlings. Seeds of hemlock and red cedar were sown in forest floor samples collected from the two types of forests, and shade treatments ranging from < 1 to 53% of full sunlight were imposed. After 6 months, seedling survival and root and shoot biomass were quantified, and red cedar seedlings were sampled for AM fungal colonization. Hemlock survival and growth did not differ between soil types, suggesting there was no substrate-associated limitation to its establishment in either forest type. Red cedar colonization by AM fungi was significantly correlated with light levels in CH soils but arbuscular mycorrhizas were absent in roots of red cedar seedlings grown in HA soil. Red cedar survival and relative growth rate were significantly greater in the CH than in HA soil; higher growth was due primarily to greater shoot growth in CH soils at high light levels. The low soil inoculum potential for red cedar in ectomycorrhiza-dominated stands may account for the virtual exclusion of red cedar seedlings from these forests.

Abies↗

PubMed2005

Environmental sensitivity of gas exchange in different-sized trees.

The carbon isotope signature (delta13C) of foliar cellulose from sunlit tops of trees typically becomes enriched as trees of the same species in similar environments grow taller, indicative of size-related changes in leaf gas exchange. However, direct measurements of gas exchange in common environmental conditions do not always reveal size-related differences, even when there is a distinct size-related trend in delta13C of the very foliage used for the gas exchange measurements. Since delta13C of foliage predominately reflects gas exchange during spring when carbon is incorporated into leaf cellulose, this implies that gas exchange differences in different-sized trees are most likely to occur in favorable environmental conditions during spring. If gas exchange differs with tree size during wet but not dry conditions, then this further implies that environmental sensitivity of leaf gas exchange varies as a function of tree size. These implications are consistent with theoretical relationships among height, hydraulic conductance and gas exchange. We investigated the environmental sensitivity of gas exchange in different-sized Douglas-fir (Pseudotsuga menziesii) via a detailed process model that specifically incorporates size-related hydraulic conductance [soil-plant-atmosphere (SPA)], and empirical measurements from both wet and dry periods. SPA predicted, and the empirical measurements verified, that differences in gas exchange associated with tree size are greatest in wet and mild environmental conditions and minimal during drought. The results support the hypothesis that annual net carbon assimilation and transpiration of trees are limited by hydraulic capacity as tree size increases, even though at particular points in time there may be no difference in gas exchange between different-sized trees. Maximum net ecosystem exchange occurs in spring in Pacific Northwest forests; therefore, the presence of hydraulic limitations during this period may play a large role in carbon uptake differences with stand-age. The results also imply that the impacts of climate change on the growth and physiology of forest trees will vary depending on the age and size of the forest.

Carbon Dioxide↗

PubMed2006

Forest encroachment into a Californian grassland: examining the simultaneous effects of facilitation and competition on tree seedling recruitment.

Competition and facilitation are both considered major factors affecting the structure of plant assemblages, yet few studies have quantified positive, negative, and net effects simultaneously. In this study, we investigated the positive, negative, and net effects of tree saplings on the encroachment of two tree species, Douglas fir (Pseudotsuga menziesii) and tanoak (Lithocarpus densiflora), into a coastal California grassland. The study involved three components: sampling the spatial distributions of P. menziesii and L. densiflora in the grasslands, a field experiment examining seedling survival in different grassland environments, and a greenhouse experiment examining the effects of soil moisture on early seedling performance. The field experiment was conducted over a 2-year period, using Pseudotsuga in 2002 and both species in 2003. Seedlings were separated into four treatment groups: those planted in open grassland, in shaded grassland, under artificial (plastic) conifer saplings, and under natural Pseudotsuga saplings. Air temperature, relative humidity, soil moisture, incident radiation levels and fog water inputs were measured for each treatment group in 2003. In the greenhouse experiment, Pseudotsuga and Lithocarpus seedlings were grown for 13 weeks in watering treatments simulating the summer soil moisture conditions of the open grasslands and under Pseudotsuga saplings. Surveys of naturally established seedlings found that Lithocarpus occurred only under Pseudotsuga saplings, while most Pseudotsuga seedlings were located near but not directly under conspecific saplings. In the field experiment, positive effects of tree saplings were much larger than negative effects, resulting in strong net facilitation of seedling establishment. Survival for both species was always higher under the plastic and live trees than in the open or shade plots. The primary mechanism facilitating seedling survival appeared to be increased soil moisture caused by input of fog precipitation coupled with reduced microsite evaporation. The greenhouse experiment further showed that soil moisture strongly affected seedling performance, with both species having much higher photosynthetic rates in the higher moisture treatment. In the lower moisture treatment, Pseudotsuga seedlings had higher photosynthetic rates and stomatal conductance than Lithocarpus, suggesting they may be able to better tolerate the environmental conditions found in the open grasslands. Our combined results suggest that rate and patterning of woody plant encroachment can be strongly influenced by facilitation and that fog precipitation may play a key role in plant interactions.

California↗

PubMed1993

Evaluation of the penetration depth of transdermally applied 3% GA MHPh 2Na-10% lidocaine gel in man.

In order to estimate the penetration depth of transdermal 3% GA MHPh 2Na-10% lidocaine gel mixture, the following physiological functions of the skin were examined before and after a 60 min occulusive application of the gel in 16 adult volunteers. Thermal sweat expulsins ceased completely on the gel-treated ventral surface of one forearm in all the firs 5 subjects, though it continued on the untreated contrast area of the other forearm. Sympathetic skin response (SSR) was also no longer induced on the gel-treated middle finger in 1 of another 3 subjects and was severely depressed in the other 2 subjects, while the SSR on the untreated index finger appeared constantly. Vasomotion of the skin circulation on another 3 subjects, remained unaffected on both the gel-treated and the untreated fingers. Extraction of a leg-hair in the treated area did not induce pain sensation in all the last 5 subjects. In addition to the transcellular main roots, some of the transcutaneously applied gel seems to penetrate deeply into the skin through the appendageal roots such as the eccrine sweat glands and the pilosebaceous glands.

Journal Article↗

PubMed2006

Methods to control ectomycorrhizal colonization: effectiveness of chemical and physical barriers.

We conducted greenhouse experiments using Douglas-fir (Pseudotsuga menziesii var. glauca) seedlings where chemical methods (fungicides) were used to prevent ectomycorrhizal colonization of single seedlings or physical methods (mesh barriers) were used to prevent formation of mycorrhizal connections between neighboring seedlings. These methods were chosen for their ease of application in the field. We applied the fungicides, Topas (nonspecific) and Senator (ascomycete specific), separately and in combination at different concentrations and application frequencies to seedlings grown in unsterilized forest soils. Additionally, we assessed the ability of hyphae to penetrate mesh barriers of various pore sizes (0.2, 1, 20, and 500 microm) to form mycorrhizas on roots of neighboring seedlings. Ectomycorrhizal colonization was reduced by approximately 55% with the application of Topas at 0.5 g l(-1). Meshes with pore sizes of 0.2 and 1 microm were effective in preventing the formation of mycorrhizas via hyphal growth across the mesh barriers. Hence, meshes in this range of pore sizes could also be used to prevent the formation of common mycorrhizal networks in the field. Depending on the ecological question of interest, Topas or the employment of mesh with pore sizes <1 microm are suitable for restricting mycorrhization in the field.

Dose-Response Relationship, Drug↗

PubMed2006

Watershed nitrogen and mercury geochemical fluxes integrate landscape factors in long-term research watersheds at Acadia National Park, Maine, USA.

This paper is an overview of this special issue devoted to watershed research in Acadia National Park (Acadia NP). The papers address components of an integrated research program on two upland watersheds at Acadia NP, USA (44 degrees 20' N latitude; 68 degrees 15' E longitude). These watersheds were instrumented in 1998 to provide a long-term foundation for regional ecological and watershed research. The research was initiated as part of EPA/NPS PRIMENet (Park Research and Intensive Monitoring of Ecosystems Network), a system of UV-monitoring stations and long-term watershed research sites located in US national parks. The initial goals at Acadia NP were to address research questions about mercury, acid rain, and nitrogen saturation developed from prior research. The project design was based on natural differences in forests and soils induced by an intense wildfire in one watershed in 1947. There is no evidence of fire in the reference watershed for several hundred years. We are testing hypotheses about controls on surface water chemistry, and bioavailability of contaminants in the contrasting watersheds. The unburned 47-ha Hadlock Brook watershed is 70% spruce-fir mature conifer forest. In contrast, burned 32-ha Cadillac Brook watershed, 4 km northeast of the Hadlock watershed, is 20% regenerating mixed northern hardwoods and 60% shrub/rocky balds. Differences in atmospheric deposition are controlled primarily by forest stand composition and age. The watersheds are gauged and have water chemistry stations at 122 m (Cadillac) and 137 m (Hadlock); watershed maximum elevations are 468 and 380 m, respectively. The stream water chemistry patterns reflect, in part, the legacy of the intense fire, which, in turn, controls differences in forest vegetation and soil characteristics. These factors result in higher nitrogen and mercury flux from the unburned watershed, reflecting differences in atmospheric deposition, contrasting ecosystem pools of nitrogen and mercury, and inferred differences in internal cycling and bioavailabilty.

Acid Rain↗

PubMed2006

Paleoecological assessment of watershed history in PRIMENet watersheds at Acadia National Park, USA.

Paleoecological reconstructions of forest stand histories for two upland watersheds at Acadia National Park in Maine were completed to support related watershed chemistry studies. The project hypothesis was that forest type and fire history influence long-term cycling and storage of atmospheric mercury and nitrogen within watersheds. The reconstructions document differences in major vegetation composition and disturbance between the burned and unburned watersheds during the past several centuries. Pollen and charcoal stratigraphies from organic sediment accumulations in forested wet depressions indicate that the present experimental design of contrasting disturbance and forest histories has persisted during recent centuries. The unburned watershed has been dominated by spruce (Picea rubens) and fir (Abies balsamea) for 500 years or more and has not recently burned or been substantially cleared. The burned watershed is dominated by a heterogeneous forest of patchy hardwood, mixed wood, and softwood stands. A large portion of this watershed burned severely in 1947 and probably more than once in the 1800s, and has supported heterogeneous successional forests for 200 years or longer. Overall, these results support the underlying premise that the experimental design of this watershed research can be used to infer landscape controls on biogeochemical processes.

Abies↗

PubMed2006

Temporal changes in the inequality of early growth of Cunninghamia lanceolata (Lamb.) Hook.: a novel application of the Gini coefficient and Lorenz asymmetry.

Growth within tree populations varies among individuals due to changes in biotic and abiotic factors. The degree of such variation, defined as growth inequality, serves as a useful indicator of the uniformity of growth within a population in response to the prevalent environmental conditions. By application of the Gini coefficient (G), an index for inequality, we characterized the early growth inequality of ninety crosses of Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) and their open-pollinated parental lines. Tree cumulative height was measured annually for 8 consecutive years. Both the crosses and parental lines exhibited temporal changes in growth inequality. The inequality of total height among the crosses decreased logarithmically with age by nearly 3-fold after 13 growing seasons, suggesting that tree height became less variable among the crosses as trees grew larger. Interestingly, the Lorenz asymmetry, an index reflecting the shape of the Lorenze curve from which G is derived, revealed that the inequality of annual height increment among the crosses resulted from an alternate contribution of the fast-growing and slow-growing trees. Among parental lines, two provenances with the smallest and the largest overall inequality in total height showed a similar pattern of changes in annual growth inequality, and the provenance differences were consistent over time. Compared to the other provinces, a local provenance exhibited less variation in total height among individual trees as reflected by a smaller value of inequality, and was better adapted to the field conditions. Our results demonstrated the sensitivity and usefulness of the Gini coefficient and Lorenz asymmetry for the analysis of growth inequality in non-natural populations. Growth inequality is a potentially useful evaluation criterion for early selection. Given comparable initial growth, provenances/families with lower growth inequality values would likely outperform those with higher growth inequality, and eventually tree size of the latter would be more variable due to greater variations among individual trees. Assessment of growth inequality at early ages will advance our understanding of variability of tree growth within a population, facilitate forest genetics improvement programs, and enhance the efficiency of tree breeding.

China↗

PubMed2001

Fatty acid composition of Pinaceae as taxonomic markers.

Following our previous review on Pinus spp. seed fatty acid (FA) compositions, we recapitulate here the seed FA compositions of Larix (larch), Picea (spruce), and Pseudotsuga (Douglas fir) spp. Numerous seed FA compositions not described earlier are included. Approximately 40% of all Picea taxa and one-third of Larix taxa have been analyzed so far for their seed FA compositions. Qualitatively, the seed FA compositions in the three genera studied here are the same as in Pinus spp., including in particular the same delta5-olefinic acids. However, they display a considerably lower variability in Larix and Picea spp. than in Pinus spp. An assessment of geographical variations in the seed FA composition of P. abies was made, and intraspecific dissimilarities in this species were found to be of considerably smaller amplitude than interspecific dissimilarities among other Picea species. This observation supports the use of seed FA compositions as chemotaxonomic markers, as they practically do not depend on edaphic or climatic conditions. This also shows that Picea spp. are coherently united as a group by their seed FA compositions. This also holds for Larix spp. Despite a close resemblance between Picea and Larix spp. seed FA compositions, principal component analysis indicates that the minor differences in seed FA compositions between the two genera are sufficient to allow a clear-cut individualization of the two genera. In both cases, the main FA is linoleic acid (slightly less than one-half of total FA), followed by pinolenic (5,9,12-18:3) and oleic acids. A maximum of 34% of total delta5-olefinic acids is reached in L. sibirica seeds, which appears to be the highest value found in Pinaceae seed FA. This apparent limit is discussed in terms of regio- and stereospecific distribution of delta5-olefinic acids in seed triacylglycerols. Regarding the single species of Pseudotsuga analyzed so far (P. menziesii), its seed FA composition is quite distinct from that of the other two genera, and in particular, it contains 1.2% of 14-methylhexadecanoic (anteiso-17:0) acid. In the three genera studied here, as well as in most Pinus spp., the C18 delta5-olefinic acids (5,9-18:2 and 5,9,12-18:3 acids) are present in considerably higher amounts than the C20 delta5-olefinic acids (5,11-20:2 and 5,11,14-20:3 acids).

Biomarkers↗

PubMed1979

Lepromatous iridocyclitis diagnosed by anterior chamber paracentesis.

A 34-year-old man with a three-month history of intraocular inflammation after ocular trauma with a fir branch, had an acute unilateral fulminant iridocyclitis. The iris had a thick, gray, cheesy membrane composed of nodular lepromata. The patient denied a history of Hansen's disease, despite the dermatologic and facial features that suggested the diagnosis. Anterior chamber paracentesis and scleral nodule biopsy demonstrated Mycobacterium lepra. The iridocyclitis resolved after treatment with dapsone, corticosteroids, and rifampin.

Adult↗

PubMed1975

An evolutionary comparison of plant histones.

Histones were extracted from chromatin of the following: a moss (Polytrichum juniperinum); the primitive vascular plants Psilotum nudum and Equisetum arvense; a fern (Polypodium vulgare); the gymnosperms fir (Abies concolor), yew (Taxus canadensis) and Gingko biloba; the dicotyledonous angiosperms tobacco (Nicotiana tabacum) and maple (Acer saccharinum); and the monocotyledonous angiosperms corn (Zea mays) and lily (Lilium longiflorum). The histones were subjected to polyacrylamide gel electrophoresis and compared to standard histones of pea (Pisum sativum) and cow (Bos taurus). All species have histones of the exact electrophoretic mobility of histones F2a1 and F3 of cow and pea. All species have histones of low electrophoretic mobility assumed to be F1 histones. None of the plant histones displayed electrophoretic mobility between F3 and F2a1 while animal histone fractions F2b and F2a2 do migrate to this position. No animal histone fraction was found to migrate between F3 and F1 while a major plant fraction, designated "F2b-like" was found to migrate to this position in all plant species studied except for the moss and Psilotum. A band of similar mobility was strikingly absent from the histones of these two species.

Biological Evolution↗