A simple method for maintaining high multiplication of Narcissus shoot cultures in vitro

A simple method for stimulating and maintaining high in vitro multiplication of Narcissus shoot clump cultures was developed. Shoot clumps were subjected either to normal cutting where leaves were trimmed to 20 mm in length at the beginning of each culture passage or to severe cutting where shoot clumps were cut down to the basal plate region removing all green tissue. Severe cutting at the beginning of each culture passage initially doubled the leaf multiplication, compared to normal cutting, but the difference between cutting treatments declined in successive passages. The improvement in leaf multiplication was maintained when shoot clumps were subjected to severe cutting only at every other culture passage, with no cutting in the alternate recovery passages. In vitro multiplication was increased by severe cutting in all seven Narcissus cultivars which were tested.Abbreviations NAA-1 naphthylacetic acid - BAP benzylaminopurine     

Rapid change in cyclic 3′,5′-AMP concentration triggered by a light-off or light-on signal in Anabaena cylindrica

In a nitrogen-fixing cyanobacterium, Anabaena cylindrica, an immediate light-to-dark transition caused an increase in cAMP concentration within 1 min. Conversely, a dark-to-light transition caused a rapid fall in cellular cAMP concentration. The concentration of cyclic 35-GMP(cGMP) was several times lower than that of cAMP and was not largely affected by a light-off or light-on signal.     

Correlation between loss of turgor and accumulation of abscisic acid in detached leaves

Mature leaves of Phaseolus vulgaris L. (red kidney bean), Xanthium strumarium L. (cocklebur), and Gossypium hirsutum L. (cotton) were used to study accumulation of abscisic acid (ABA) during water stress. The water status of individual, detached leaves was monitored while the leaves slowly wilted, and samples were cut from the leaves as they lost water. The leaf sections were incubated at their respecitive water contents to allow ABA to build up or not. At least 8 h were required for a new steady-state level of ABA to be established. The samples from any one leaf covered a range of known water potentials (), osmotic pressures (), and turgor pressures (p). The and p values were calculated from pressure-volume curves, using a pressure bomb to measure the water potentials. Decreasing water potential had little effect on ABA levels in leaves at high turgor. Sensitivity of the production of ABA to changes in progressively increased as turgor approached zero. At p=1 bar, ABA content averaged 4 times the level found in fully turgid samples. Below p=1 bar, ABA content increased sharply to as much as 40 times the level found in unstressed samples. ABA levels rose steeply at different water potentials for different leaves, according to the at which turgor became zero. These differences were caused by the different osmotic pressures of the leaves that were used; must cqual - for turgor to be zero. Leaves vary in , not only among species, but also between plants of one and the same species depending on the growing conditions. A difference of 6 bars (calculated at =0) was found between the osmotic pressures of leaves from two groups of G. hirsutum plants; one group had previously experienced periodic water stress, and the other group had never been stressed. When individual leaves were subsequently wilted, the leaves from stress-conditioned plants required a lower water potential in order to accumulate ABA than did leaves from previously unstressed plants. On the basis of these results we suggest that turgor is the critical parameter of plant water relations which controls ABA production in water-stressed leaves.Abbreviations ABA abscisic acid - me-ABA abscisic-acid methyl ester - leaf water potential - osmotic pressure - p volumeaveraged turgor - volumetric modulus of elasticity     

Pollen selection for Alternaria resistance in oilseed brassicas: responses of pollen grains and leaves to a toxin of A. brassicae

Summary The effects of destruxin B, a host-specific toxin of Alternaria brassicae that causes black spot disease in oilseed brassicas, were studied on in vitro pollen germination and pollen-tube growth of Brassica campestris var brown sarson, B. juncea, B. napus cvs Westar and Cresor, B. nigra and Sinapis alba. Pollen grains of B. nigra, B. juncea and B. campestris were the most sensitive and those of S. alba the least sensitive to the toxin. Effects of the toxin were also studied on the leaves of these species, and the degree of sensitivity of leaves of different species was comparable to that of their pollen grains. The results on the responses of pollen grains as well as leaves to the toxin are in agreement with the degree of susceptibility/resistance of these species to A. brassicae reported in the literature, indicating that the genes imparting susceptibility/restistance are expressed in the pollen, a prerequisite for pollen selection. Results are also presented which show that the toxin fed to the cut end of isolated inflorescence axis is readily taken up by the developing pollen and results in the inhibition of germination of susceptible pollen. This technique offers a simple and effective method for application of selection pressure to eliminate pollen grains susceptible to the toxin from effecting fertilization.     

Satellited chromosomes,systematics and phylogeny inTaraxacum (Asteraceae)

A survey is made of the occurrence, nature and frequency of satellited chromosomes in the agamospermous genusTaraxacum. Species belonging to the 10 sections thought to be most primitive in the genus lack satellited chromosomes. In most other sections, a characteristic satellited chromosome is seen with a large euchromatic region distal to the presumed nucleolar oraniser region (NOR). In sections of a precursor type, there is always one chromosome of this Taraxacum type per haploid genome. In sections thought to be of an advanced type the number of such satellited chromosomes is very unstable, sometimes even within the same tissue. In sectionHamata, two such satellited chromosomes are invariably found in triploids. This finding strongly supports the integrity of this section, suggests that the species of the section are monophyletic, and have evolved from a single ancestor subsequent to the occurrence of obligate agamospermy. In three sections of the genus, satellited chromosomes of the conventional type with a very small distal euchromatic region distal to the NOR are reported for the first time in the genus.     

Linkage analysis for 18 enzyme loci in Pinus rigida Mill.

Summary Estimates of recombination frequency among enzyme loci of pitch pine revealed two new linkages, Mdh3:Pgm2 (=0.01) and Pep1:Mdh4 (=0.38), and confirmed two previously established linkages. Tighter linkage (=0.30) was ruled out for nearly all gene pairs examined. In general, the Bayesian approach used in this study to test for linkage performed better than alternative methods.This work was supported by the School of Natural Resources, College of Agricultural and Life Sciences, University of Wisconsin, Madison, WI, and by McIntyre-Stennis, project no. 142-C385     

Identification of phosphate granules occurring in seedling tissue of two palm species (Phoenix dactylifera and Washingtonia filifera)

Haustoria of two palm species, Phoenix dactylifera L. (date) and Washingtonia filifera (Lindl.) Wendl were carefully dissected from seeds, and the ultrastructural characteristics of the large, electron-opaque granules present in the cells of this tissue were compared using standard aldehyde and OsO₄ fixations. In Washingtonia, the granules were smaller than those in date and were more variable in size and presence of non-opaque inclusions. All granules appeared to be membrane bounded although they often filled the bounded space. No protein, lipid, carbohydrate or tannins were found in the granules by standard staining procedures. The granules stained positively with two different metallic-phosphate stains which contained either bismuth or lead. Energy dispersive X-ray microprobe analysis, done on aldehyde-fixed granules and those stained with both phosphate stains, confirmed the fact that phosphorus and calcium were present in the granules. The granules also bound the metallic stains as expected. All procedures consistently confirmed the presence of phosphate in the granules. The data are most consistent with the hypothesis that the granules are composed of polyphosphate.Abbreviations and symbols EDAX energy-dispersive X-ray microanalysis - K K shell peak - K K shell peak - L L shell peak - L L shell peak - M M shell peak     

Response of liquid flow resistance to soil drying in seedlings of four deciduous angiosperms

Summary Soil-leaf resistance to liquid water flow (R) in moist and drying soil was compared in three-month-old seedlings of two drought tolerant (white [Quercus alba L.], post oak [Q. stellata Wangenh.]) and two drought sensitive forest species (sugar maple [Acer saccharum Marsh.], black walnut [Juglans nigra L.]). At high soil moisture (_s–0.3 MPa), R was higher in J. nigra than in the other species, and as soil water was depleted R increased most in this species. In contrast, the lowest resistance at all levels of soil moisture was observed in Q. stellata. At _s of –1.5 MPa, R of drought-sensitive J. nigra and A. saccharum was about twice as high as that of the two drought-tolerant Quercus species. The difference in R between the two Quercus species was much smaller than that between this pair and the other two species. These differences among species in flow resistance may be attributable to: 1) variation in the balance between root surface area and leaf area, 2) variation in the inherent absorption capacity of the root systems and in xylem water conducting systems or 3) differences in root permeability, shrinkage and mortality in severely stressed seedlings. As the soil dried, seedlings of all species exhibited pronounced reductions in transpiration rate, which prevented development of large water potential gradients between leaves and the soil. Reduction in transpiration in J. nigra was especially pronounced, resulting in a decrease in the soil-to-leaf water potential gradient in dry soil despite high flow resistance. The observed differences among species in flow resistance are correlated with natural distribution patterns.     

Response of effective quantum yield of photosystem 2 to in situ temperature in three alpine plants

The response of effective quantum yield of photosystem 2 (F/F_m) to temperature was investigated under field conditions (1 950 m a.s.l.) in three alpine plant species with contrasting leaf temperature climates. The in situ temperature response did not follow an optimum curve but under saturating irradiances [PPFD >800 µìmol(photon) m^–2s^–1] highest F/F_m occurred at leaf temperatures below 10°C. This was comparable to the temperature response of antarctic vascular plants. Leaf temperatures between 0 and 15°C were the most frequently (41 to 56%) experienced by the investigated species. At these temperatures, F/F_m was highest in all species (data from all irradiation classes included) but the species differed in the temperature at which F/F_m dropped below 50% (Soldanella pusilla >20°C, Loiseleuria procumbens >25°C, and Saxifraga paniculata >40°C). The in situ response of F/F_m showed significantly higher F/F_m values at saturating PPFD for the species growing in full sunlight (S. paniculata and L. procumbens) than for S. pusilla growing under more moderate PPFD. The effect of increasing PPFD on F/F_m, for a given leaf temperature, was most pronounced in S. pusilla. Despite the broad diurnal leaf temperature amplitude of alpine environments, only in S. paniculata did saturating PPFD occur over a broad range of leaf temperatures (43 K). In the other two species it was half of that (around 20 K). This indicates that the setting of environmental scenarios (leaf temperature×PPFD) in laboratory experiments often likely exceeds the actual environmental demand in the field.This revised version was published online in March 2005 with corrections to the page numbers.     

A monoclonal antibody chromosome marker analysis used to locate a loose smut resistance gene in wheat chromosome 6A

Many genes have been located in wheat chromosomes, yet little is known about the location of genes for resistance to Ustilago tritici, which causes loose smut. Crosses were made between the loose smut susceptible alien substitution lines Cadet 6Ag(6A) and Rescue 6Ag(6A) (lines in which Agropyron chromosome 6 is substituted by wheat chromosome 6A) and four cultivars resistant to U. tritici race T19: Cadet, Kota, Thatcher and TD18. The segregating progeny were tested for reaction to race T19 and for the level of binding with a monoclonal antibody specific to a chromosome 6A-coded seed protein. The antibody, which does not bind to seed protein extracts in the absence of the 6A chromosome, was used as a chromosome marker. An association was established between resistance to race T19 and the presence of chromosome 6A for each of the cultivars tested, indicating that resistance to race T19 resides in chromosome 6A. Ustilago tritici race T19 resistance in Cadet appears to be located in the short arm of chromosome 6A, based on the evaluation of the Cadet 6A long ditelosomic stock, which was susceptible, and the Cadet 6A-short: 6-Agropyron- short alien translocation stock, which was resistant.     

The ability of acidic pH,growth inhibitors,and glucose to increase the proton motive force and energy spilling of amino acid-fermenting <Emphasis Type="Italic">Clostridium sporogenes</Emphasis> MD1 cultures

Clostridium sporogenes MD1 grew rapidly with peptides and amino acids as an energy source at pH 6.7. However, the proton motive force (p) was only –25 mV, and protonophores did not inhibit growth. When extracellular pH was decreased with HCl, the chemical gradient of protons (ZpH) and the electrical membrane potential () increased. The p was –125 mV at pH 4.7, even though growth was not observed. At pH 6.7, glucose addition did not cause an increase in growth rate, but increased to –70 mV. Protein synthesis inhibitors also significantly increased . Non-growing, arginine-energized cells had a of –80 mV at pH 6.7 or pH 4.7, but was not detected if the F₁F₀ ATPase was inhibited. Arginine-energized cells initiated growth if other amino acids were added at pH 6.7, and and ATP declined. At pH 4.7, ATP production remained high. However, growth could not be initiated, and neither nor the intracellular ATP concentration declined. Based on these results, it appears that C. sporogenes MD1 does not need a large p to grow, and p appears to serve as a mechanism of ATP dissipation or energy spilling.Mandatory disclaimer: Proprietary or brand names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by the USDA implies no approval of the product, and exclusion of others that may be suitable.     

<Emphasis Type="Italic">MICA</Emphasis> response to gliadin in intestinal mucosa from celiac patients

MHC class I chain-related gene A (MICA), a putative independent susceptibility gene in autoimmune diseases, encodes a surface protein present in epithelial cells that binds to NKG2D, an activating receptor of NK, and T cells, and could function as a stress-inducible activator of the innate immune response. There is no evidence of a long-term implication of MICA in the celiac autoimmune process. However, it could be that gliadin activation of MICA occurs only during the initial stages of the disease. In order to determine whether MICA is activated in response to gliadin in patients with celiac disease (CD), small intestinal mucosa biopsy samples from ten long-standing celiac patients on a gluten-free diet and from five non-celiac individuals were incubated with and without gliadin for 4 h. Total RNA was purified and MICA, IFNG and NKG2D mRNA were quantified by fluorescent real-time RT-PCR. Expression levels were calculated relative to GAPDH. MICA expression was detected in both patients and controls, but incubation with gliadin induced a strong increase in samples from the treated CD group compared with the non-CD controls (P=0.028), while no differences were observed for IFNG or NKG2D mRNA levels. The gliadin-provoked over-expression of MICA in normalized tissues from CD patients suggests a role for this stress-induced activator of the immune response in the early stages of organ-specific autoimmune destruction, probably preceding the onset of inflammation.     

Seasonal water potential changes and proline accumulation in mediterranean shrubland species

We studied the water relations of 6 shrub and 3 tree species typical of the mediterranean climate region of central Spain to identify differential responses to water stress between and within species, and to determine if free proline concentration in leaves could be used as a water stress indicator. Predawn and midday water potentials (w) on a seasonal basis, relative water content (RWC), leaf mass per area, foliar nitrogen and free proline concentrations were measured. The lowest water potentials were observed at the end of the summer, with recovery to higher water potentials in the fall and winter seasons. Species differed regarding the annual w fluctuation. Thymus zygis, Halimium viscosum, Genista hirsuta and Juniperus oxycedrus exhibited the most negative midday and predawn w (both less than -6 MPa) with a large magnitude of response to changing conditions in soil moisture of the upper horizon of the soil. Lavandula pedunculata and Cistus ladanifer showed a moderate response. Quercus rotundifolia, Quercus faginea and Retama sphaerocarpa showed a modest response. The w of different size individuals of Quercus rotundifolia and Cistus ladanifer were compared. The annual w fluctuation was greater in small individuals as compared to large individuals. In every species, there was an increase in proline concentration of bulk leaf tissues when predawn w dropped below -5 MPa. Small plants of Cistus ladanifer reached lower water potentials and also higher concentration of proline than bigger plants. Proline could possibly be used as a drought stress indicator in every species except Q. rotundifolia. It is suggested that in addition to water stress avoidance due to deep root systems, some mechanisms of water stress tolerance may operate among shrub and tree species of central Spain.     

Dissection of a pollen-specific promoter from maize by transient transformation assays

We have previously reported the isolation and characterization of a gene (Zm 13) from Zea mays which shows a pollen-specific pattern of expression. Stably transformed tobacco plants containing a reporter gene linked to portions of the Zm 13 5 flanking region show correct temporal and spatial expression of the gene. Here we present a more detailed analysis of the 5 regions responsible for expression in pollen by utilizing a transient expression system. Constructs containing the -glucuronidase (GUS) gene under the control of various sized fragments of the Zm13 5 flanking region were introduced into Tradescantia and Zea mays pollen via high-velocity microprojectile bombardment, and monitored both visually and with a fluorescence assay. The results suggest that sequences necessary for expression in pollen are present in a region from –100 to –54, while other sequences which amplify that expression reside between –260 and –100. The replacement of the normal terminator with a portion of the Zm13 3 region containing the putative polyadenylation signal and site also increased GUS expression. While the –260 to –100 region contains sequences similar to other protein-binding domains reported for plants, the –100 to –54 region appears to contain no significant homology to other known promoter fragments which direct pollen-specific expression. The microprojectile bombardment of Tradescantia pollen appears to be a good test system for assaying maize and possibly other monocot promoter constructs for pollen expression.     

New structures of the O-specific polysaccharides of Proteus. 3. Polysaccharides containing non-carbohydrate organic acids

Four new Proteus O-specific polysaccharides were isolated by mild acid degradation from the lipopolysaccharides of P. penneri 28 (1), P. vulgaris O44 (2), P. mirabilis G1 (O3) (3), and P. myxofaciens (4), and their structures were elucidated using NMR spectroscopy and chemical methods. They were found to contain non-carbohydrate organic acids, including ether-linked lactic acid and amide-linked amino acids, and the following structures of the repeating units were established: 3)--L-QuipNAc-(13)--D-GlcpNAc-(16)--D-GlcpNAc-(1 (S)-Lac-(2–3) (1) 4)--D-GlcpA-(13)--D-GalpNAc-(14)--D-Glcp-(13)--D-Galp-(14)--D-GalpNAc-(1 L-Ala-(2–6) (2) 3)--D-GalpNAc-(16)--D-GalpNAc-(14)--D-GlcpA-(1 L-Lys-(2–6)--D-GalpA-(14) (3) 4)--D-GlcpA-(16)--D-GalpNAc-(16)--D-GlcpNAc-(13)--D-GlcpNAc-(1 (R)-aLys-(2–6) (4) where (S)-Lac and (R)-aLys stand for (S)-1-carboxyethyl (residue of lactic acid) and N-[(R)-1-carboxyethyl]-L-lysine (alaninolysine), respectively. The data obtained in this work and earlier serve as the chemical basis for classification of the bacteria Proteus.     

Synthesis of an H type 2 and a Y (Ley) glycoside from thioglycoside intermediates

The trisaccharide 2-(p-trifluoroacetamidophenyl)ethyl 2-acetamido-2-deoxy-4-O-[2-O-(-l-fucopyranosyl)--d-galactopyranosyl]--d-glucopyranoside 1 and the tetrasaccharide 2-(p-trifluoroacetamidophenyl)ethyl 2-acetamido-2-deoxy-3-O-(-l-fucopyranosyl)-4-O-[2-O-(-l-fucopyranosyl)--d-galactopyranosyl]--d-glucopyranoside 2 were synthesized. Thioglycosides, suitably protected, activated directly with methyl trifluoromethanesulfonate or dimethyl(methylthio)sulfonium tetrafluoroborate or activated after bromine treatment with halophilic reagents, were used as glycosyl donors in the construction of the glycosidic linkages.Abbreviations DMTSB dimethyl(methylthio)sulfonium tetrafluoroborate - Phth phthaloyl - MBn p-methoxybenzyl - ClBn p-chlorobenzyl     

Adventitious shoot regeneration from leaf explants of tissue cultured and greenhouse-grown raspberry

Adventitious shoot regeneration was observed using leaf-petiole explants from shoot-proliferating cultures of Comet red raspberry (Rubus idaeus L.). A maximum regeneration rate of 70% (3.7 shoots/explant) was obtained using 4.5–9.1 M (1–2 mg l^–1) N-phenyl-N-1,2,3-thiadiazol-5-ylurea (thidiazuron or TDZ) with 2.5–4.9 M (0.5–1 mg l^–1) 1H-indole-3-butanoic acid (IBA) or 2.3 M (0.5 mg l^–1) TDZ with 4.9 M (1 mg l^–1) IBA in modified Murashige-Skoog medium. TDZ was more effective than N-(phenylmethyl)-1H-purin-6-amine (BA) at promoting regeneration in combinations tested with IBA (maximum 50% regeneration rate; 1.8 shoots/explant). Variation in the agar concentration or incubation temperature, orientation or scoring of the leaf-petiole explants and use of separate leaf or petiole explants had no effect on shoot regeneration. Incubation in the dark for 1, 2 or 3 weeks prior to growth in the light did not influence the percent regeneration rate but depressed the number of adventitious shoots. Explant source, from micropropagated shoots or greenhouse-grown plants, had an effect on shoot regeneration that was genotype dependent. Only 8 of 22 (36%) raspberry cultivars were capable of regeneration from leaf explants derived from greenhouse-grown plants.     

Carbon assimilation, nitrogen, and photochemical efficiency of different Himalayan tree species along an altitudinal gradient

In the area of Jumla region in Western Nepal, measurements of saturated leaf net photosynthetic rate (P_sat), nitrogen content, leaf fluorescence, carbon isotopic composition, and water status were performed on woody coniferous (Pinus wallichiana, Picea smithiana, Abies spectabilis, Juniperus wallichiana, Taxus baccata), evergreen (Quercus semecarpifolia, Rhododendron campanulatum), and deciduous broadleaved species (Betula utilis, Populus ciliata, Sorbus cuspidata) spreading from 2 400 m up to the treeline at 4 200 m a.s.l. With the exception of J. wallichiana, P_sat values were lower in coniferous than broadleaved species. Q. semecarpifolia, that in this area grows above the coniferous belt between 3 000 and 4 000 m, showed the highest P_sat at saturating irradiance and the highest leaf N content. This N content was higher and P_sat lower than those of evergreen oak species of tempe forests at middle and low altitudes. For all species, P_sat and N content were linearly correlated, but instantaneous nitrogen use efficiency was lower than values measured in lowland and temperate plant communities. The values of carbon isotopic composition, estimated by ₁₃C, showed the same range reported for temperate tree species. The ranking of ₁₃C values for the different tree types was conifers < evergreen broadleaved13C were found along the altitudinal gradient. Quantum yield of photochemistry at saturating irradiance, measured by leaf fluorescence (F/F_m), was highest in J. wallichiana and lowest in T. baccata. Overall, photochemical efficiency was more strongly related to species than to altitude. Interestingly, changes of .F/F_m along the altitudinal gradient correlated well with the reported altitudinal distribution of the species.This revised version was published online in March 2005 with corrections to the page numbers.     

Sex determination in Sarotherodon (tilapia)

Summary The simplest possible model of the sex determination process adding autosomal influence to a minimal number of sex chromosomes was developed to explain matings of Tilapia (Sarotherodon) species. Eighteen different genotypes, each having two autosomes (AA, Aa, or aa) and two sex chromosomes (WX, WY, WW, XY, XX or YY) involved in sex determination, are predicted by the theory. Their sex (10 males and 8 females) were determined using a series of directed graphs, showing the relative strength of the chromosome pairs, developed on the basis of Chen's sex ratio results (Chen 1969). This theoretical model predicts eight different sex ratios (01, 13, 35, 11, 97, 53, 31, 10 ); three of them are not predicted by the WXYZ theory. The greatest part of these sex ratios have been obtained experimentally in extensive series of crosses between related species of Tilapia and their hybrids, carried out by several authors. The theory succeeds in explaining all of Chen's results, including those ratios 53 and 01 seen in certain crosses but not predicted by the WXYZ theory. The importance of the autosomes is seen in comparisons of the genotype pairs (AaWY, aaWY), (AaXY, aaXY) and (AAWW, AaWW) in which the first genotype in each case is male while the second is female as proven by the sex ratio results. The members of the pair differ only in the substitution of one autosome for the other. To test the theory, experiments consisting of hormonal sex reversion and a series of crosses are proposed. Finally, theoretical and practical implications of the theory are discussed.     

Systematic implications of the flavonoids and chromosomes ofFlyriella (Compositae—Eupatorieae)

The leaves of five species ofFlyriella were found to contain from one to four glycosides of quercetin and its 4- and 7,4-methyl ethers. These patterns are distinct from those observed for more than seventy species ofBrickellia and support morphological and chromosomal data which indicate thatFlyriella should not be treated as an element ofBrickellia. Alternative treatments are briefly considered.