Desiccation-time limits of photosynthetic recovery in Equisetum hyemale (Equisetaceae) spores

The chlorophyllous spores of Equisetum survive desiccation, yet cannot tolerate this quiescent state for more than ~2 wk. The hypothesis that spore viability of Equisetum hyemale L. is limited by inhibition of photosynthetic recovery was tested using chlorophyll a fluorescence and oxygen-exchange analyses. Experimental spores were desiccated at 2% relative humidity and 25C for time periods of 24 h, 1 wk, and 2 wk, and then rehydrated at 200 mmol photons/m2s (PAR) and 25C for up to 24 h. Spores desiccated for 24 h recovered photosynthetic competence very rapidly during rehydration, reaching the O2 compensation point in 6.3 ~ 0.3 (mean +/- SE) min. Recovery of photosynthetic performance of spores desiccated for 1 wk was slower, as judged by significantly slower increases of (1) photochemical efficiency of photosystem (PS) II, (2) PS II quinoneB-reducing center concentration, (3) quinoneB concentration, (4) water-oxidation activity, (5) rate of light-induced O2 evolution, and (6) apparent quantum yield of net O2 exchange. Photosystem-II and whole-spore photosynthetic competence of 2-wk desiccated spores was increasingly impaired, and did not recover during rehydration. Origin fluorescence yield and dark respiration were not affected by desiccation time following rehydration. The results suggest that the extremely short viability of disseminated spores of Equisetum hyemale is due to the inability to recover losses of water oxidation and photosystem II-core function following 2 wk of desiccation.     

Characterisation of polyphenols by HPLC-PAD-ESI/MS and antioxidant activity in Equisetum telmateia

The antioxidant activity of an aqueous extract (infusion) and respective ethyl acetate fraction of Equisetum telmateia Ehrh. (Equisetaceae), a plant used in traditional medicine for its anti-inflammatory and diuretic properties, has been evaluated by DPPH, TEAC and TBARS assays. A high and significant antioxidant activity was detected in the ethyl acetate fraction. Analysis of the aqueous extract and the ethyl acetate fraction by HPLC-PAD-ESI/MS allowed the identification of the major phenolic compounds as flavan-3-ol, kaempferol and phenolic acid derivatives. Among the flavan-3-ols, A-type proanthocyanidins and afzelechin derivatives were detected as well as the more common B-type procyanidins, B2 and C1, whose identification was further confirmed by HPLC using detection involving chemical reaction with p-dimethylamino-cinnamaldehyde. The results suggest that the anti-inflammatory activity of E. telmateia could be due, at least in part, to the presence of compounds with antioxidant activity.     

Biomechanics and functional anatomy of hollow-stemmed sphenopsids. I. Equisetum giganteum (Equisetaceae)

The hollow stem of Equisetum giganteum owes its mechanical stability to an outer ring of strengthening tissue, which provides stiffness and strength in the longitudinal direction, but also to an inner lining of turgid parenchyma, which lends resistance to local buckling. With a height >2.5 m isolated stems are mechanically unstable. However, in dense stands individual stems support each other by interlacing with their side branches, the typical growth habit of semi-self-supporters.     

Phylogeny and Biogeography of Thuja L. （Cupressaceae）, an Eastern Asian and North American Disjunct Genus

In order to develop better insights into biogeographic patterns of eastern Asian and North American disjunct plant genera, sequences of nuclear ribosomal DNA internal transcribed spacer (nr DNAITS) region were used to estimate interspecific relationships of Thuja L. (Cupressaceae) and infer its biogeography based on the phylogeny. According to the phylogenetic analysis, two clades were recognized. The first clade included Thuja plicata D. Don (western North America) and T. koraiensis Nakai (northeastern Asia), and the second one contained T. occidentalis (Gord.) Cart. (Japan). The ancestral area of Thuja was inferred to be eastern Asia, and two dispersal events were responsible for the modern distribution of Thuja in North America. Both the North Atlantic land bridge and Bering land bridge were possible routes for the migration of ancestral populations to North America.     

Phylogeny and Biogeography of Thuja L. (Cupressaceae), an Eastern Asian and North American Disjunct Genus

In order to develop better insights into biogeographic patterns of eastern Asian and North American disjunct plant genera, sequences of nuclear ribosomal DNA internal transcribed spacer (nr DNA ITS) region were used to estimate interspecific relationships of Thuja L. (Cupressaceae) and infer its biogeography based on the phylogeny. According to the phylogenetic analysis, two clades were recognized. The first clade included Thuja plicata D. Don (western North America) and T. koraiensis Nakai (northeastern Asia), and the second one contained T. occidentalis (Gord.) Carr. (Japan). The ancestral area of Thuja was inferred to be eastern Asia, and two dispersal events were responsible for the modern distribution of Thuja in North America. Both the North Atlantic land bridge and Bering land bridge were possible routes for the migration of ancestral populations to North America.     

Diterpene composition of Cupressus dupreziana and Cupressus sempervirens

The heartwood of Cupressus dupreziana and C. sempervirens were shown to contain similar mixtures of diterpenes.     

Seedbed and moisture availability determine safe sites for early Thuja occidentalis (Cupressaceae) regeneration

Regeneration of many late-successional tree species depends on specialized safe sites. The primary objective was to investigate the roles of seedbed and moisture retention as dimensions of safe sites for the early regeneration of drought-sensitive northern white cedar (Thuja occidentalis). We hypothesized that rates of germination, survival, and growth of T. occidentalis are unlikely to differ among seedbed types under conditions of abundant water, but that differences are likely to emerge as water becomes more limited. In a 67-d greenhouse experiment, cedar seeds were sown on logs, leaf litter, and soil of cedar and paper birch (Betula papyrifera) canopy origin. Seedbeds were subjected to three water treatments. Among the water treatments, highest germination rates occurred within the high water treatment, although germination on cedar litter was comparable to that of the low water treatment. Higher germination and survival rates occurred on decayed logs than other natural seedbeds for medium (P = 0.001) and low (P < 0.0001) water treatments. Germination on birch logs occurred at higher rates than on cedar logs within the low water treatment (P = 0.04). Seedling growth for the medium water treatment was lower on leaf litter than any other type of seedbed (P < 0.01). Results generally demonstrated that the interplay between seedbed and moisture retention is a component of safe sites for T. occidentalis regeneration.     

Three 2-oxoglutarate-dependent dioxygenase activities of Equisetum arvense L. forming flavone and flavonol from (2S)-naringenin

Equisetum arvense L. (Equisetaceae-horsetail) accumulates various flavones and flavonols in infertile shoot. Enzyme assays conducted with crude extracts of the green tissue revealed chalcone synthase activity and also three further activities assigned to flavonoid biosynthesis and identified as flavone synthase I, flavanone 3β-hydroxylase and flavonol synthase. The latter three activities were characterized as soluble, 2-oxoglutarate-dependent dioxygenases by their typical cofactor requirements and peculiar inhibition. Notably, this is the first report of flavone synthase I which had been considered to be restricted solely to species of the Apiaceae from a distant plant taxon.     

Volatile oils of mature and juvenile leaves of Juniperus horizontalis: Chemosystematic significance

Comparison of 39 terpenoids between young (juvenile) foliage and mature (adult) foliage from naturally growing plants of Juniperus horizontalis revealed no significant differences. Canonical variate analysis of the terpenoids of J. scopulorum and J. virginiana along with the mature foliage of J. horizontalis and co-plotting juvenile foliage showed a slight loosening of the J. horizontalis group but not enough to blur taxonomic distinctions. These results stand in sharp contrast with the previous work on J. scopulorum and appear to be due to the indeterminant growth pattern seen in J. horizontalis.     

Nomenclatural transfer of Chamaecyparis obtusa (Siebold & Zucc.) Endl. 'Sanderi' (Cupressaceae) to Thuja orientalis L. 'Sanderi' on the basis of phytochemical data

The longstanding problem of the true identity of the juvenile conifer clone usually known as Chamaecyparis obtusa 'Sanderi' has been solved by comparing gas chromatograms of solvent extracts of foliage specimens. Forty-seven species of the northern Cupressaceae were compared with 'Sanderi' but close similarity was shown only by juvenile forms of Thuja orientalis. All other species studied showed significant, usually major, differences.     

No differential consequences of reproduction according to sex in Juniperus communis var. depressa (Cupressaceae)

In dioecious plant species, males and females are thought to have dissimilar allocation patterns. Females are believed to invest more in reproduction and less in growth and maintenance than males. This differential investment between sexes could result in distinct growth patterns and contrasting survival rates, thereby affecting the sex ratio of a population and the age and size distribution of males and females, possibly leading to habitat segregation according to sex. These effects might become more apparent under particularly limiting conditions, such as in nutrient-deficient soils or in climatically stressed environments. To verify these predictions, growth patterns, microsite characteristics, and age and size distribution of male and female individuals were compared, and population sex ratio was determined in three populations of the dioecious shrub Juniperus communis var. depressa (Cupressaceae, Pinophyta) along a short latitudinal gradient on the eastern coast of Hudson Bay (Northern Québec, Canada). We found that the northernmost population had a male-biased sex ratio, but that the southernmost one had a higher proportion of females. Our results failed to reveal any significant differences in radial growth patterns, mean sensitivity, annual elongation of the main axis, and size and age frequency distribution between males and females in any population. Furthermore, there was no evidence of microhabitat segregation according to sex as indicated by the lack of differences in the physicochemical characteristics of the substrate under males and females. Clearly, the expected ecological consequences of a presumed greater investment of females in reproduction were not apparent even under the very stressful conditions prevailing on subarctic dunes. Many factors could reduce differences in the cost of reproduction between males and females, such as the number and quality of reproductive structures produced annually by individuals of each sex, the possible photosynthetic activity of the immature female cones, and the complexity of the source/sink relationship within individuals. Alternatively, there may be no differences between sexes in their reproductive investment.     

A rapid procedure to detect in situ DNA/RNA hybrids

We developed a new method for detecting DNA/RNA hybrids formed $\text{in}\text{situ}$ using $\text{anti-}\text{DNA}\text{RNA}$ antibodies and the Peroxidase-antiperoxidase immunohistochemical procedure. Using RNA synthesised $\text{in}\text{vitro}$ from cloned $\text{Drosophila}$ histone genes (pDm 500H), we localized by this procedure, the histone genes to the 39 D-E region of the left arm of the second chromosome. This method has several advantages compared to conventional procedures.     

Mycoplasma contamination of membrane associated measles antigens. Inability to demonstrate in vitro lymphocyte responsiveness to measles.

A marked suppression of protein synthesis including IgA was demonstrated in BALB/c mouse thymocytes incubated in short-term tissue culture in the presence of anti-mouse α chain antibodies. In C57BL mouse thymocytes a suppression of protein synthesis including IgM was obtained by incubating the cells in tissue culture containing anti-mouse μ chain antibodies. The association of anti-α chain antibodies or anti-κ chain antibodies, at 4 °, to the Ig subunits on the surface of BALB/c mouse thymocytes was demonstrated following radioiodination of the antibody treated cells. The anti-mouse Ig antibodies attached to the surface α chains or κ chains at 4 ° were radioiodinated on the cell surface, rendering the corresponding surface mouse Ig subunits inaccessible to radioiodination by lactoperoxidase. The α chains or κ chains complexed with their specific antibodies were independently removed from the cell surface upon heating to 37 °. However, it was found that each of the antibodies attached first to its Ig subunit on the cell surface interferes with the subsequent binding of antibodies to the second subunit. The antibody-surface Ig complexes, although cleared from the cell membrane at 37 °, were not released into the culture medium, leading to the conclusion that these complexes were endocytosed.     

A sensitive transgenic plant system to detect toxic inorganic compounds in the environment

We describe a transgenic plant-based assay to study the genetic effects of heavy metals. Arabidopsis thaliana plants carrying a beta-glucuronidase (GUS) marker gene either with a point mutation or as a recombination substrate were used to analyze the frequency of somatic point mutations and homologous recombination in whole plants. Transgenic test plants sown on media contaminated by the salts of the heavy metals Cd2+, Pb2+, Ni2+, Zn2+, Cu2+, and As2O3 exhibited a pronounced uptake-dependent increase in the frequencies of both somatic intrachromosomal recombination and point mutation. The test was applied to monitor the genotoxicity of soils sampled in sites contaminated with several heavy metals. Our results indicate that this is a highly sensitive system for monitoring metal contamination in soils and water.     

Determination and quantification of monoterpenoids secreted into the medium of cell cultures of thuja occidentalis

Cell cultures of Thuja occidentalis excrete monoterpenoids into the culture medium. Highly volatile monoterpene hydrocarbons were only detectable in the presence of Miglyol, a water-insoluble non-toxic trap for lipophilic compounds. In the presence of Miglyol the levels of oxygenated monoterpenoids were two-fold higher than in dichloromethane-extracts of culture media. The cells excrete up to 3 mg regular monoterpenoids/g dry wt/day. Continuous extraction of lipophilic compounds by Miglyol also allowed quantification of a Tris—thujaplicinato—(Fe III)-complex.