bluuebunny/crossref_metadata_2025_split huggingface dataset:
Levels of Glycine Betaine in Growing Cells and Spores of
Bacillus
Species and Lack of Effect of Glycine Betaine on Dormant Spore Resistance
Authors: Loshon Charles A. , Wahome Paul G. , Maciejewski Mark W. , Setlow Peter 
Published: April 2006

ABSTRACT

Bacteria of various
Bacillus
species are able to grow in media with very high osmotic strength in part due to the accumulation of low-molecular-weight osmolytes such as glycine betaine (GB). Cells of
Bacillus
species grown in rich and minimal media contained low levels of GB, but GB levels were 4- to 60-fold higher in cells grown in media with high salt. GB levels in
Bacillus subtilis
cells grown in minimal medium were increased ∼7-fold by GB in the medium and 60-fold by GB plus high salt. GB was present in spores of
Bacillus
species prepared in media with or without high salt but at lower levels than in comparable growing cells. With spores prepared in media with high salt, GB levels were highest in
B. subtilis
spores and ≥20-fold lower in
B. cereus
and
B. megaterium
spores. Athough GB levels in
B. subtilis
spores were elevated 15- to 30-fold by GB plus high salt in sporulation media, GB levels did not affect spore resistance. GB levels were similar in wild-type
B. subtilis
spores and spores that lacked major small, acid-soluble spore proteins but were much lower in spores that lacked dipicolinic acid.
Identification of Nudix Hydrolase Family Members with an Antimutator Role in
Mycobacterium tuberculosis
and
Mycobacterium smegmatis
Authors: Dos Vultos T. , Blázquez J. , Rauzier J. , Matic I. , Gicquel B. 
Published: April 2006

ABSTRACT

Mycobacterium tuberculosis
and
Mycobacterium smegmatis
MutT1, MutT2, MutT3, and Rv3908 (MutT4) enzymes were screened for an antimutator role. Results indicate that both MutT1, in
M. tuberculosis
and
M. smegmatis
, and MutT4, in
M. smegmatis
, have that role. Furthermore, an 8-oxo-guanosine triphosphatase function for MutT1 and MutT2 is suggested.
A comparative cytological analysis of fungal endophytes in the sporophyte rhizomes and vascularized gametophytes of Tmesipteris and Psilotum
Authors: Duckett Jeffrey G. , Ligrone Roberto 
Published: April 2006

This article describes the results of a light and electron microscopic study of the fungal endophytes and vascular anatomy in the rhizomes and gametophytes of Tmesipteris and Psilotum. The parenchymatous cortical cells of the rhizomes and subterranean gametophytes of Tmesipteris and Psilotum contain intracellular aseptate glomeromycotean fungi resembling the “Paris-type” of arbuscular mycorrhizas found in seed plants. The fungi differentiate into multinucleate vesicles and hyphal coils, both containing bacteria-like structures and accumulating lipid masses and crystals as they age. After several cycles of infection in the same cell, degenerate hyphae form amorphous masses encased by host wall material. Nearly identical host–fungus cytology between the autotrophic sporophytes and the heterotrophic gametophytes suggests that these psilophyte associations are exploitative of the fungus in both generations. Following the description of tracheids nearly 60 years ago in the gametophytes of Psilotum, vascular elements are described for the first time in the haploid generation of Tmesipteris. Close similarities between the water- and food-conducting elements in both generations, viz. vessel elements with scalariform perforation plates and sieve cells with refractive spherules and lacking callose at all stages in their develoment, add support to the homologous theory of the alternations of generations. Mitochondrial aggregations, cross-linked by small electron-opaque rods, are common in the stelar cells of both generations and appear to be a unique feature of the psilophyte clade.
The effect of Frankia and Paxillus involutus on the performance of Alnus incana subsp. rugosa in mine tailings
Authors: Markham John H. 
Published: April 2006

The purpose of this study was to determine whether symbiotic nitrogen-fixing bacteria and mycorrhizal fungi act synergistically to improve plant performance when grown on heavy metal mine tailings. Seedlings were inoculated with Frankia, Paxillus involutus (Batsch) Fr., or a combination of both and grown in 100% peat, a 1:1 mix of peat and tailings, or 100% tailings for 20 weeks. Mortality of plants grown on pure tailings (15.0%) and peat–tailings (17.9%) was significantly greater than mortality of plants grown on peat (3.5%). The rate of nodulation and mycorrhizae formation decreased from 90.0% and 66.7%, respectively, on the peat, to 11.9% and 2.6% on the tailings. Frankia-inoculated plants grown on peat–tailings showed twice the mortality rate (38.5%) of any other inoculation treatment. Plants grown on media containing tailings had greater root/shoot ratios than plants grown on peat. Inoculating plants grown in the presence of tailings with either Frankia and (or) P. involutus increased root thickness. Inoculating plants with both symbionts increased colonization rates and shoot yield on the peat and peat–tailings media, suggesting that these symbionts act synergistically to improve plant performance. However, inoculating plants with Frankia decreased shoot relative growth rate in the early part of the experiment when plants were not fixing nitrogen, which, coupled with the higher mortality effect, suggests that nodule development is a stress for plants. It may be advisable that plants have fully functioning nodules before transplanting if they are to be used in revegetation programs.
Aluminum accumulation in the roots of Melastoma malabathricum, an aluminum-accumulating plant
Authors: Watanabe Toshihiro , Misawa Seiji , Osaki Mitsuru 
Published: April 2006

Generally, plants that have Al levels of at least 1000 mg·kg–1 in their leaves are defined as Al accumulators. These plants are often found in very acid soils in the tropics. The mechanisms of Al uptake in strong Al accumulators are still unclear. In this study, we investigated the characteristics of Al uptake and accumulation in the roots of Melastoma malabathricum L., an Al-accumulating plant that grows in acidic soils in the tropics. Melastoma malabathricum roots hardly absorb any La, possibly because of lower affinity of the root apoplast to La than to Al. Exposure to La did not affect the concentration of citrate in the roots; however, application of Al increased the citrate level considerably, corresponding with the amount of Al accumulation in the symplast. 27Al NMR analysis revealed that Al complexes with oxalate, but not with citrate, in the roots of M. malabathricum. This investigation revealed that oxalate, which occurs constitutively at high concentrations, is a ligand for Al accumulation in both root and shoot tissue, and that citrate, the synthesis of which is induced by Al application, is a ligand mainly used for Al translocation from the roots to the shoots.
Coordinated variation in ecophysiological properties among life stages and tissue types in an invasive perennial forb of semiarid shrub steppe
Authors: Hill Judson P. , Germino Matthew J. 
Published: April 2006

Semiarid lands of North America are vulnerable to invasion by exotic forbs that frequently have an extended phenology compared with native herbaceous species. We hypothesized that photosynthetic stems, rosette leaves, and cauline leaves of Centaurea maculosa Lam. (knapweed) would differ in ecophysiological specialization and that these differences would enhance plant carbon uptake across seasonal variations in microclimate. Photosynthesis, water relations, and morphological features of C. maculosa were measured under natural variations in temperature and soil water, and under manipulated light environments, in adults compared with seedlings having only rosette leaves. Carbon gain was greater in adults than in seedlings owing to high photosynthesis in cauline and rosette leaves when water was abundant. Otherwise, photosynthesis was relatively lower but persistent through drought in all tissues and ages until senescence. Photosynthesis decreased with water stress in all tissues except stems. Stems comprised up to 36% of photosynthetic area following senescence of rosette leaves during seasonal drought. Seedlings expressed shade acclimation compared with rosette and especially cauline leaves of adults, although adult rosette leaves had flexible photosynthetic light responses. Contrasting ecophysiological specializations of photosynthetic tissues enhance carbon gain of adult C. maculosa as light, water, and temperature vary during its relatively long growth season.
The biology ofStellaria longipes(Caryophyllaceae)
Authors: Chinnappa C.C. , Donald Gillian M. , Sasidharan Rashmi , Emery R.J. Neil 
Published: April 2006

During the past 30 years of research on Stellaria longipes Goldie, much has been learned about the taxonomy, cytology, reproductive biology, genetic variation, and phenotypic plasticity of this highly successful, circumpolar species. The conclusion that a S. longipes complex exists where two diploid progenitors ( Stellaria longifolia Muhl. (2n = 26) and Stellaria porsildii Chinnappa (2n = 26)) hybridized to produce polyploid S. longipes (2n = 52, 2n = 78, 2n = 104) was determined following extensive cytological and morphological studies. Interspecific hybridization is also common with S. borealis (2n = 52). The genetic variation and phenotypic plasticity contributing to the population differentiation within the S. longipes complex was investigated using isozyme, RFLP, and RAPD analyses, and comparative morphological studies. In later years, the focus shifted to elucidating the physiological and molecular aspects regulating the stem elongation plasticity observed in response to different temperatures, photoperiods, and different red/far red ratios. The roles of the phytohormones, ethylene, gibberellins, and abscisic acid were investigated in alpine and prairie ecotypes of S. longipes, and the phytochrome multigene family members were cloned. The presence of multigene families and a complex phytohormone interaction are postulated to underlie the extensive phenotypic plasticity observed in S. longipes.
Computed tomography scanning for three-dimensional imaging and complexity analysis of developing root systems
Authors: Lontoc-Roy Melinda , Dutilleul Pierre , Prasher Shiv O. , Han Liwen , Smith Donald L. 
Published: April 2006

To improve our understanding of the role of root systems in soil-based resource acquisition by plants and eventually model it completely, root system complexity must be quantified, in addition to other morphometric traits. In this note, we introduce a new approach in which computed tomography (CT) scan data are collected on crop root systems in three-dimensional (3-D) space nondestructively and noninvasively, thus allowing for repeated measurements and a relevant complexity analysis of root systems. The experimental crop is maize ( Zea mays L.). Four potted seedlings were CT scanned under wet soil conditions on the day of emergence, and each of the two following days. Specifically, a high-resolution X-ray CT scanner formerly used for medical purposes produced 3 × 500 CT images of 0.1 mm thick cross-sections for each seedling. The fractal dimension of each root system on each day was estimated on a skeletonized 3-D image reconstructed from CT scan data. We found that the mean fractal dimension value was not significantly greater than 1 on day 1 (1.015 ± 0.015), contrary to days 2 and 3 (1.037 ± 0.015, 1.065 ± 0.016). Our results, including original 3-D images, provide support for a novel type of root system studies based on the collection and advanced analysis of CT scan data.
Calcium oxalate crystal macropatterns in leaves of species from groups Glycine and Shuteria (Glycininae; Phaseoleae; Papilionoideae; Fabaceae)
Authors: Cervantes-Martinez Teresa , Horner Harry T. , Palmer Reid G. , Hymowitz Theodore , Brown A.H.D. 
Published: April 2006

Calcium oxalate crystal macropatterns in leaves were characterized for 69 species (and two Glycine tomentella cytotypes) from 14 of 16 genera in two legume groups, Glycine and Shuteria, to determine whether they share a common macropattern. A leaf clearing method was used to visualize the crystals. All 69 species (and two Glycine tomentella cytotypes) displayed prismatic crystals associated with leaf veins and vein endings. In contrast, mesophyll crystals occurred in 76.8% of 69 species and two G. tomentella cytotypes, and varied from a few to many. Conversely, only 40.9% of 22 Glycine species (in group Glycine) lacked mesophyll crystals, while 8.7% of 23 species of six genera associated with Glycine (in group Glycine) lacked mesophyll crystals. Thus 24.4% of 45 species of seven combined genera in group Glycine lacked mesophyll crystals. With seven genera in group Shuteria, 20.8% of 24 species lacked mesophyll crystals. The consistently present vein crystals varied in size and shape, so their length–width (Stubby versus Long) crystal ratios were determined for primary, secondary, and tertiary veins, and vein endings. Two trends were evident: Long-crystal ratios increased from primary veins to vein endings in species in both groups, and the perennial and annual Glycine species showed this condition to a greater extent than all the non-Glycine species. In some cases, taxonomically closely associated species were quite similar in their macropattern and presence or absence of mesophyll crystals. These results should be of value to future studies dealing with taxonomy and phylogeny of species in these two leguminous groups.
Proximate factors causing mast seeding in Fagus crenata: the effects of resource level and weather cues
Authors: Kon Hirokazu , Noda Takashi , Terazawa Kazuhiko , Koyama Hiromasa , Yasaka Michiyasu 
Published: April 2006

To examine the proximate factors causing mast seeding in Fagus crenata Blume in Hokkaido, northern Japan, we analyzed a 13-year time series of seed production in relation to both previous reproduction and weather conditions. In an autocorrelation analysis we observed a significant negative correlation in 1-year time lags for the log-transformed total seed crop. This indicates that internal resource dynamics are important for mast seeding. A strong negative correlation was observed between the total seed crop and minimum temperature from late April to mid-May in the year preceding flowering. The critical minimum temperature from late April to mid-May for total seed crop at all five sites was about 1.0 °C higher than the 22-year (1979–2000) mean of the minimum temperatures, above which very few seeds were produced. These results show that a weather cue triggers the cessation of reproduction in F. crenata. Regression models that included reproduction in the previous year and minimum temperature explained 57.8%–83.1% of the total seed crop at the five study sites. Therefore, resource dynamics and weather cues are clearly involved in mast seeding in F. crenata.
The effects of the smut fungus Microbotryum bistortarum on survival and growth of Polygonum viviparum in Svalbard, Norway
Authors: Tojo Motoaki , Nishitani Satomi 
Published: April 2006

The effect of the smut fungus Microbotryum bistortarum (de Candolle) K. Vánky on Polygonum viviparum L. was investigated in the High Arctic region, Svalbard, Norway, from 2000 to 2004. Ninety-two plants in a field plot were monitored for disease occurrence, plant survival, and plant growth. The disease, initially identified in 20 plants, only spread to one additional plant in 4 years. Once infected, the plants remained infected. Although a few of the 71 uninfected plants disappeared or died without any apparent signs of disease, the majority remained healthy without smut throughout the study. The percent survival among smut-infected plants was significantly lower than that of healthy plants in 2004 (P < 0.001). The number of bulbils, the number of flowers, and the size of the largest leaves of smut-infected plants were significantly lower than those of healthy plants. These results suggest infection by M. bistortarum can negatively impact populations of P. viviparum in the High Arctic region by lowering plant growth and longevity. Teliospore surface characteristics and germination patterns of the High Arctic specimens of M. bistortarum were also documented.
Evolutionary analysis of Pinus leiophylla: a study using an Intron II sequence fragment of mitochondrial nad1
Authors: Mendoza Carlos Fabián Vargas , Rodríguez-Banderas Abril 
Published: April 2006

A phylogenetic analysis was done using a mitochondrial marker to study the relationship between Pinus leiophylla Schiede & Deppe and Californian, Mesoamerican, European, and Asian pines. The type II intron between the nad1 b and c exons was chosen for the analysis. Nineteen otus (15 species with mitotypes in two species) from the Pinus and Picea genera were used. Amplification using the two primers generated an approximately 1000 bp product, depending on species. Parsimony branch and bound analysis resulted in 135 shortest trees with 1323 steps (CI = 0.9131 and RI = 0.9511). The strict consensus tree showed P. leiophylla associated with Eurasian pines. Though unusual, it is not the first time this association has been proposed. Given these results, P. leiophylla is likely one of the oldest pine species in the Americas and probably arose from a Eurasian ancestor that initially invaded North America at between 25°N and 35°N latitude and later colonized Mexico.
Maturation temperature regulates germinability and chemical constituents of Scotch thistle (Onopordum acanthium) cypselas
Authors: Qaderi Mirwais M. , Cavers Paul B. , Hamill Allan S. , Downs Michael P. , Bernards Mark A. 
Published: April 2006

The effects of maturation temperature on germinability and chemical constituents of Scotch thistle ( Onopordum acanthium L.) cypselas (fruits) were determined as part of our ongoing investigation into the causes of intermittent germination in this species. Mature cypselas were collected from plants that were grown under higher (28 or 30 °C) and lower (20 or 22 °C) temperature regimes in greenhouses in 2000 and 2001. Two collections were made, from early- and late-ripening capitula. Germinability and the amounts of moisture, wax, phenolic compounds, and lignin were determined for cypselas from all collections. Cypselas that matured in the first year had lower amounts of moisture and wax than second-year cypselas, but did not differ in amounts of other components. Cypselas that matured under the higher temperatures generally had lower amounts of moisture, wax, and phenolic compounds, faster germination, and higher germination percentages. Early-matured cypselas had higher amounts of moisture and wax, faster germination, and higher germination percentages, but lower amounts of phenolic compounds. However, maturation temperature and collection date did not affect lignin content. Consistent and significant differences in germination patterns and chemical constituents between cypselas that matured under contrasting temperatures confirmed that maturation temperature altered the germinability of O. acanthium cypselas. Thus, under field conditions, cypselas that mature under low temperatures can have stronger dormancy and exhibit greater intermittency in germination/emergence patterns than those that mature under high temperatures.
Annual growth of the spring ephemeral Erythronium americanum as a function of temperature and mycorrhizal status
Authors: Lapointe Line , Lerat Sylvain 
Published: April 2006

The capacity of the spring ephemeral Erythronium americanum L. to grow and absorb nutrient either as nonmycorrhizal (NM) or mycorrhizal (M) plants under the low temperature regime characteristic of its growth period was investigated. Specimens of E. americanum were collected in the field as either NM (early September) or as M plants (late October). Both groups of plants were submitted to different nutrient regimes during the hypogeous growth period at 5 °C, and during the subsequent epigeous growth period conducted at temperature regimes of either 12 °C day : 10 °C night or 17 °C day : 15 °C night. Nutrient regime influenced bulb nutrient content only during the epigeous growth period. The presence of mycorrhizas did not influence nutrient content, but favoured a greater bulb biomass at the final harvest (epigeous growth period), as did the lower temperature regime. Net nutrient uptake was not reduced at lower temperatures and appeared to follow plant demand. These findings confirm that E. americanum is adapted to perform better under a low temperature regime and that mineral nutrition in this species occurs mainly in spring in response to active growth. Arbuscular mycorrhizal fungi benefit E. americanum maybe through less expensive nutrient uptake or sustained carbon sink demand.
Seed size variation in cold and freezing tolerance during seed germination of winterfat (Krascheninnikovia lanata) (Chenopodiaceae)
Authors: Wang Ruojing , Bai Yuguang , Low Nicholas H. , Tanino Karen 
Published: April 2006

Native plants have adaptations to their local environments and elucidation of these traits has implications in both agronomy and restoration ecology. Winterfat ( Krascheninnikovia lanata (Pursh) A.D.J. Meeuse & Smit) is a native perennial shrub in North America capable of germinating at low temperatures. The effect of seed size on germination ability at low and subzero temperatures and the physiological mechanisms were investigated. Winterfat seeds achieved 50%–72% germination at –3 °C, a temperature slightly above the base temperature estimated using thermal time models. Small seeds required a longer time to reach 50% germination at subzero temperatures than large seeds. Large seeds maintained stable water uptake rate for both the seed and the embryo when temperatures decreased from 5 to –1 °C. In contrast, faster water uptake and greater relative K+leakage in small seeds indicated possible damage to membrane integrity at subzero temperatures. Carbohydrate conversion efficiency (Rq/RCO2) of large seeds was significantly higher than that of small seeds at 10 °C but not at 20 °C. Higher cold resistance in large seeds was also correlated with higher concentrations of glucose, raffinose, and sucrose. This study revealed the potential basis of the low-temperature germination advantage of large seeds and provided the first direct evidence of germination under freezing temperatures in winterfat.
Photosynthesis and physiological traits of evergreen broadleafed saplings during winter under different light environments in a temperate forest
Authors: Miyazawa Yoshiyuki , Kikuzawa Kihachiro 
Published: April 2006

Photosynthetic traits of the evergreen broadleafed species Camellia japonica L. and Quercus glauca Thunb. were continuously investigated during autumn and winter using saplings that grew in different light environments (gap, deciduous canopy understory, and evergreen canopy understory) in a temperate forest. Light-saturated rates of net photosynthesis in midwinter and spring were lower than those in autumn. Photosynthetic capacity, scaled to a common leaf temperature of 25 °C, increased or remained stable after autumn and then decreased in spring in most leaves. Photosynthetic traits per unit leaf area were different among leaves in different light environments of both Camellia and Quercus during most periods. However, photosynthetic traits per unit leaf mass did not differ among leaves in different light environments, suggesting that differences in photosynthetic traits were mainly due to different leaf mass per area among leaves. Photosynthetic rates under light availability typical in the environment were lower in winter than in autumn in leaves in the sun in a gap but were not different in leaves in the shade under evergreen canopy trees. Thus, the importance of winter carbon gain for annual carbon gain is small in leaves in a gap but is large in leaves under evergreen canopy trees.