NS1 DNA vaccination protects against Zika infection through T cell-mediated immunity in immunocompetent mice

The causal association of Zika virus (ZIKV) with microcephaly, congenital malformations in infants, and Guillain-Barré syndrome in adults highlights the need for effective vaccines. Thus far, efforts to develop ZIKV vaccines have focused on the viral envelope. ZIKV NS1 as a vaccine immunogen has not been fully explored, although it can circumvent the risk of antibody-dependent enhancement of ZIKV infection, associated with envelope antibodies. Here, we describe a novel DNA vaccine encoding a secreted ZIKV NS1, that confers rapid protection from systemic ZIKV infection in immunocompetent mice. We identify novel NS1 T cell epitopes in vivo and show that functional NS1-specific T cell responses are critical for protection against ZIKV infection. We demonstrate that vaccine-induced anti-NS1 antibodies fail to confer protection in the absence of a functional T cell response. This highlights the importance of using NS1 as a target for T cell-based ZIKV vaccines.

Low-temperature, high-performance solution-processed metal oxide thin-film transistors formed by a ‘sol–gel on chip’ process

At present there is no ‘ideal’ thin-film transistor technology for demanding display applications, such as organic light-emitting diode displays, that allows combining the low-temperature, solution-processability offered by organic semiconductors with the high level of performance achievable with microcrystalline silicon1. N-type amorphous mixed metal oxide semiconductors, such as ternary oxides Mx1My2Oz, where M1 and M2 are metals such as In, Ga, Sn, or Zn, have recently gained momentum because of their high carrier mobility and stability2, 3 and good optical transparency, but they are mostly deposited by sputtering. So far no route is available for forming high-performance mixed oxide materials from solution at low process temperatures <250 °C. Ionic mixed metal oxides should in principle be ideal candidates for solution-processable materials because the conduction band states derived from metal s-orbitals are relatively insensitive to the presence of structural disorder and high charge carrier mobilities are achievable in amorphous structures2. Here we report the formation of amorphous metal oxide semiconducting thin-films using a ‘sol–gel on chip’ hydrolysis approach from soluble metal alkoxide precursors, which affords unprecedented high field-effect mobilities of 10 cm2 V−1 s−1, reproducible and stable turn-on voltages Von≈0 V and high operational stability at maximum process temperatures as low as 230 °C.

Relationships among three pathways for resource acquisition and their contribution to plant performance in the emergent aquatic Plant Lythrum salicaria (L.)

Three pathways for resource acquisition exist in the emergent aquatic plant, Lythrum salicaria (L.); a subterranean root system, a free-floating adventitious root system, and arbuscular mycorrhiza (AM) fungal hyphae colonizing subterranean roots. This study examined the relationship(s) among these pathways and their contribution to plant performance. If the free-floating adventitious root system and/or AM fungi contribute to plant growth in wetland habitats, we predicted that their absence would result in a significant reduction in plant performance. Furthermore, if a reduction in resource uptake, effected by an absence of free-floating adventitious roots and/or AM fungi, is compensated for by increased allocation to remaining pathway(s) for resource uptake, we predicted altered patterns of resource allocation among shoots and the remaining pathway(s) for resource uptake. Contrary to our predications, plants experiencing adventitious root removal and/or grown in the absence of AM fungi generally had greater biomass and total shoot height than controls. Similarly, while levels of AM colonization and subterranean root biomass displayed a treatment effect, the observed responses did not correspond with our predictions. This was also true for shoot : subterranean root dry weight ratios. Our results indicate that there is interaction among the 3 pathways for resource acquisition in L. salicaria and an effect on plant performance. The adaptive significance of these characteristics is unclear, highlighting the potential difficulties in extrapolating from terrestrial to aquatic plant species and among aquatic plant species with potentially different life history strategies.

Structural characteristics of root–fungal interactions for five ericaceous species in eastern Canada

A combination of light microscopy (including differential interference contrast) and laser scanning confocal microscopy was used to document the colonization patterns of epidermal cells and details of intracellular hyphal complexes of five native ericaceous hosts: Vaccinium oxycoccos L. (bog cranberry), Ledum groenlandicum Oeder. (Labrador tea), Vaccinium myrtilloides L. (velvet-leaf blueberry), Kalmia angustifolia L. (sheep laurel), and Gaultheria procumbens L. (wintergreen). Colonization patterns, hyphal complex morphology, and the structure of thick-walled epidermal cells varied considerably among hosts. Multiple hyphal connections were observed between adjacent epidermal cells, indicating that one fungal entry point may result in the colonization of more than one epidermal cell. Further field observations combined with fungal isolations from field-collected plants, identification, and reinoculation studies of other species in the large Ericaceae family are required to determine the full range of structural details in ericoid mycorrhizas.Key words: ericoid mycorrhizas, hair roots, intracellular hyphal complexes, confocal microscopy.

Structural features of mycorrhizal associations in two members of the Monotropoideae, Monotropa uniflora and Pterospora andromedea

Species in the subfamily Monotropoideae (family Ericaceae) are achlorophyllous and myco-heterotrophic. They have become highly specialized in that each plant species is associated with a limited number of fungal species which in turn are linked to autotrophic plants. This study provides an updated and comprehensive examination of the anatomical features of two species that have recently received attention with respect to their host-fungal specificity. Root systems of Monotropa uniflora and Pterospora andromedea collected from the field were characterized by light microscopy and scanning electron microscopy. All roots of both species were associated with fungi, each root having a well-developed mantle, paraepidermal Hartig net, and intracellular "fungal pegs" within epidermal cells. The mantle of M. uniflora was multi-layered and numerous outer mantle hyphae developed into cystidia of two distinct morphologies. Large calcium oxalate crystals were present, primarily on the mantle surface. The outer mantle of P. andromedea was more loosely organized, lacked cystidia, and had smaller plate-like as well as cylindrical crystals on the surface and between outer mantle hyphae. Fungal pegs in M. uniflora originated from inner mantle hyphae that penetrated the outer tangential wall of epidermal cells; in P. andromedea, these structures were initiated either from inner mantle hyphae or Hartig net hyphae and penetrated radial walls of epidermal cells. With respect to function, fungal pegs occurred frequently in both host species and, although presumed to be the sites of active nutrient exchange, no direct evidence exists to support this. Differences between these two monotropoid hosts, resulting from the mycorrhizal fungi with which each associates, are discussed.

Mechanistic toxicogenomic analysis of WAY-144122 administration in Sprague–Dawley rats

Application of global gene expression analysis in the study of mechanisms of toxicity could provide a more comprehensive interpretation of the molecular basis of drug action. WAY-144122 has pharmacological activity against several targets improving insulin responsiveness and favorably altering lipid profiles. Normal rats treated with suprapharmacological doses of WAY-144122 for 28 days exhibited drug-related effects in the liver and ovary. To determine the molecular mechanism underlying these effects, we employed global gene expression profiling to measure RNA levels in these target organs obtained from WAY-144122-treated rats administered test article for 1, 3, 7, and 14 days. Genes altered in expression by WAY-144122 were functionally categorized and related to their biological activity. In the liver, WAY-144122 caused a widespread up-regulation of genes involved in lipid mobilization, peroxisomal proliferation, and fatty acid beta-oxidation. In the ovary, we observed reduced expression of genes encoding luteinizing hormone receptor, follistatin, and enzymes in the estradiol synthesis pathway. Transcriptional changes in both organs precede histopathological effects. Profiling analysis allowed us to formulate hypotheses for molecular mechanisms underlying the physiological observations. In the liver, transcriptional changes suggest that WAY-144122 induced increased metabolic activity and peroxisomal proliferation resulting in increased liver weight and hepatocellular hypertrophy. We propose decreased estradiol synthesis as the underlying mechanism for the observed follicular atrophy in the ovary. Importantly, in this study, we have identified potential molecular mechanisms of drug effect in expression profiles before observation of physiological changes.

Pharmacogenomic analysis of rhIL-11 treatment in the HLA-B27 rat model of inflammatory bowel disease

Recombinant human interleukin-11 (rhIL-11) reduces the clinical signs and histological lesions of inflammatory bowel disease (IBD) in transgenic rats expressing the human major histocompatability complex (MHC) class I allele, HLA-B27. To elucidate the pharmacogenomic effects of rhIL-11 in this model, we examined the global gene expression pattern in inflamed colonic tissue before and following rhIL-11 treatment using oligonucleotide microarrays. In total, 175 disease-related genes were identified. Increased expression of genes involved in antigen presentation, cell death and inflammation, and decreased expression of metabolic genes was associated with disease. A total of 27 disease-related genes returned to normal expression levels following rhIL-11 treatment including the MHC class II gene RT1-DMbeta. rhIL-11 induced the expression of four intestinal epithelial growth factors. These gene expression patterns indicate that treatment of inflammatory bowel disease with rhIL-11 affects class II antigen processing and colonic epithelial cell proliferation and metabolism.

Phosphorus, arbuscular mycorrhizal fungi and performance of the wetland plant Lythrum salicaria L. under inundated conditions

The role of arbuscular mycorrhizal (AM) fungi in aquatic and semi-aquatic environments is poorly understood, although they may play a significant role in the establishment and maintenance of wetland plant communities. We tested the hypothesis that AM fungi have little effect on plant response to phosphorus (P) supply in inundated soils as evidenced by an absence of increased plant performance in inoculated (AM+) versus non-inoculated (AM-) Lythrum salicaria plants grown under a range of P availabilities (0-40 mg/l P). We also assessed the relationship between P supply and levels of AM colonization under inundated conditions. The presence of AM fungi had no detectable benefit for any measures of plant performance (total shoot height, shoot dry weight, shoot fresh weight, root fresh weight, total root length or total root surface area). AM+ plants displayed reduced shoot height at 10 mg/l P. Overall, shoot fresh to dry weight ratios were higher in AM+ plants although the biological significance of this was not determined. AM colonization levels were significantly reduced at P concentrations of 5 mg/l and higher. The results support the hypothesis that AM fungi have little effect on plant response to P supply in inundated conditions and suggest that the AM association can become uncoupled at relatively high levels of P supply.

Clinical care of gambling disorders: training, experience, and competence among VHA psychologists

Problem gambling is a common, highly destructive disorder which is often overlooked by clinicians. Levels of clinical training, clinical experience, and professional competence for providing clinical services for problem gambling were examined in a survey of 181 clinical psychologists working in the Veterans Healthcare Administration (VHA). The results suggest that the majority of clinical psychologists have little or no formal training and little or no past or current clinical experience in the treatment of disordered gambling, nor do they see themselves as competent to evaluate or treat patients with disordered gambling. Most have not referred patients for treatment of problem gambling and do not know of a competent provider to whom they can refer. There is an identifiable subgroup, representing 9% of respondents, who do have more training, provide services, and see themselves as competent to provide care for patients with problem gambling. The amount of formal training is positively correlated with care provided and self-ratings of competence. Despite the lack of training and experience, most respondents expressed interest in receiving additional training. These data suggest that to improve rates of diagnosis and treatment of patients with problem gambling in mental health settings, additional training needs to be made available for mental health providers as a group, with specialized training for clinicians interested in specializing in this area.

Characterization of the interaction between the dark septate fungus Phialocephala fortinii and Asparagus officinalis roots

Phialocephala fortinii Wang & Wilcox is a member of root-inhabiting fungi known collectively as dark septate endophytes (DSE). Although very common and distributed worldwide, few studies have documented their interaction with roots on a structural basis. The objective of this study was to determine the early colonization events and formation of microsclerotia of P. fortinii in roots of Asparagus officinalis L., a species known to have DSE. A loose network of hyphae accumulated at the root surface, and coils formed around root hairs and external to epidermal cells overlying short cells of the dimorphic, suberized exodermis. Root penetration occurred via swollen, appressorium-like structures into epidermal cells where coiling of hyphae occurred along the periphery of the cells. Hyphae penetrated from the epidermis into short exodermal cells and from these into cortical cells. Hyphae colonized the cortex up to the endodermis and sometimes entered the vascular cylinder. Some root tips were colonized as well. Microsclerotia in epidermal and exodermal short cells accumulated glycogen, protein, and polyphosphate. Energy-dispersive X-ray spectroscopy on distinct bodies visible in microsclerotial hyphae revealed high levels of phosphorus.

Subcutaneous or oral administration of rhIL-11 modulated the contact hypersensitivity response

Recombinant human interleukin 11 (rhIL-11) is a multifunctional cytokine with immunomodulatory activity on both T cells and macrophages. The effects of rhIL-11 in a murine model of contact hypersensitivity (CHS) response have been studied. The CHS response is a T cell-mediated response directed against chemically modified self-proteins following epidermal exposure to haptens. CHS is generated in two phases. The sensitization phase involves dermal dendritic cell recognition of haptenized proteins and antigen presentation. The effector phase involves T cell recognition and activation. In mice sensitized with oxazolone, CHS was induced by secondary challenge to the right ear and measured by ear swelling 24 h later. rhIL-11 significantly suppressed CHS as measured by ear swelling and tissue myeloperoxidase activity when injected subcutaneously for 5 days from the day of sensitization or when administered only on the day before and the day of challenge, but was not effective when administered prior to or on the day of sensitization. These results indicate that subcutaneously administered rhIL-11 may modulate the effector phase of CHS. Administration of rhIL-11 as an oral gavage prior to sensitization also reduced CHS. However oral administration of rhIL-11 after sensitization had no effect. These results suggest that orally and subcutaneously administered rhIL-11 may act through different mechanisms to affect CHS.

Defining mechanisms of action of interleukin-11 on the progression of radiation-induced oral mucositis in hamsters

Oral ulcerative mucositis is a common toxicity associated with drug and radiation therapy for cancer. It impacts on quality of life and economic outcomes, as well as morbidity and mortality. Mucositis is often associated with dose limitations for chemotherapy or is a cause for dose interruption for radiation. The complexity of mucositis as a biological process has only been recently appreciated. It has been suggested that the condition represents a sequential interaction of oral mucosal cells and tissues, pro-inflammatory cytokines and local factors such as saliva and the oral microbiota. The recognition that the pathophysiology of mucositis is a multifactorial process was partially suggested by the observation that interleukin-11 (IL-11), a pleotropic cytokine, favorably altered the course of chemotherapy-induced mucositis in an animal model. In the current study, we evaluated a series of biologic and morphologic outcomes to determine their roles and sequence in the development of experimental radiation-induced mucositis and to evaluate the effects of IL-11 in attenuating them. Our results suggest that IL-11 favorably modulates acute radiation-induced mucositis by attenuating pro-inflammatory cytokine expression. Data are also presented which help define the pathobiological sequence of mucositis.

IL-12-Dependent enhancement of CTL response to weak class I-restricted peptide immunogens requires coimmunization with T helper cell immunogens

The effect of in vivo administration of rmIL-12 on the CTL response to immunization with a weakly immunogenic class I-restricted peptide emulsified in incomplete Freund's adjuvant was investigated. In the absence of IL-12, peptide-specific CTL responses were significantly greater following coimmunization with class I-restricted peptide and T helper cell antigens than following immunization with the class I-restricted peptide alone. IL-12-dependent enhancement of the CTL response to peptide immunization was demonstrated in the presence of, but not in the absence of, coimmunization with T helper cell antigen. These findings indicate that IL-12 enhancement of the CTL response to weak class I-restricted immunogens is T helper cell dependent. Treatment with rmIL-12 also enhanced the CTL response to immunization with cDNA encoding both CTL and T helper cell epitopes. These findings are relevant to the design of vaccines containing tumor-associated class I-restricted peptides currently being tested as an immunotherapy for cancer patients.

Molecular effects of recombinant human interleukin-11 in the HLA-B27 rat model of inflammatory bowel disease

Recombinant human interleukin-11 (rhIL-11) is a pleiotropic cytokine with effects on multiple cell types. In addition to thrombopoietic activity, rhIL-11 has demonstrated anti-inflammatory activity in vitro and in vivo. rhIL-11 treatment reduces clinical signs and histologic lesions of colitis in transgenic rats expressing the human major histocompatibility complex (MHC) Class I allele, HLA-B27. We have investigated the effects of rhIL-11 at the molecular and cellular level in this model of inflammatory bowel disease. RT-PCR analysis of colonic RNA revealed that treatment with rhIL-11 down-regulated expression of proinflammatory cytokines including TNF-alpha, IL-1beta, and IFN-gamma. rhIL-11 also reduced the level of myeloperoxidase activity in the cecum indicating reduced inflammation. After stimulation in vitro with anti-CD3 antibody, spleen cell cultures derived from rhIL-11-treated rats produced less IFN-gamma, TNF-alpha, and IL-2 than cultures derived from vehicle-treated rats. These molecular and cellular effects correlated with amelioration of disease as measured by stool character and histologic lesion scores. These findings suggest that rhIL-11 acts to reduce inflammation through modulation of multiple proinflammatory mediators including products of activated T cells. This study has identified pharmacodynamic markers of rhIL-11 anti-inflammatory activity in vivo and supports rhIL-11 therapy to treat inflammatory bowel disease.

Murine Hoxc-9 gene contains a structurally and functionally conserved enhancer

Reporter gene analysis of the Hoxc-9 genomic region in transgenic mice allowed us to identify a positional enhancer in the Hoxc-9 intron that drives expression in the posterior neural tube of midgestation mouse embryos in a Hoxc-9-related manner. Sequence comparison to the chicken Choxc-9 intron revealed the existence of two highly conserved sequence elements (CSEs) in a similar spatial arrangement. These structural similarities in the mammalian and avian lineage are mirrored by conserved function of the chicken Choxc-9 intron in transgenic mice. Deletion analysis of the two introns suggests that full activity of both enhancers depends on cooperation between the two CSEs located close to the respective 5' and 3' splice sites. Following the paradigm of phylogenetically conserved developmental control mechanisms, the Hoxc-9 intragenic enhancer was tested in Drosophila. Our data show that the mouse Hoxc-9 enhancer acts in a conserved fashion in transgenic flies, conferring posteriorly restricted reporter gene expression to the developing central nervous system in third instar larvae. This finding indicates that the Hoxc-9 intragenic enhancer is involved in transcriptional regulatory circuits conserved between vertebrates and arthropods.

Interleukin-11 induces intestinal epithelial cell growth arrest through effects on retinoblastoma protein phosphorylation

Recombinant human (rh) interleukin (IL)-11 has been shown to reduce gastrointestinal mucosal injury after chemotherapy or irradiation in several animal models. As reduction of cellular proliferation can be cytoprotective, we have examined the effect of rhIL-11 compared with transforming growth factor (TGF)-beta 1 on the proliferation and cell cycle progression of a rat intestinal cell line, IEC-6. IEC-6 cells treated with rhIL-11 or rhTGF-beta 1 exhibited a reduced proliferative rate as measured by cell counts and [3H]thymidine incorporation. The presence of neutralizing anti-TGF-beta 1 antibodies did not block the antiproliferative effect of rhIL-11 indicating that the rhIL-11 activity was not mediated through the induction of endogenous TGF-beta 1 production. Growth inhibition correlated with delayed entry into S phase of the cell cycle. Cell cycle arrest was associated with suppression of retinoblastoma protein phosphorylation. Transient cell cycle arrest is a possible mechanism by which rhIL-11 may protect intestinal epithelial cells from damage induced by chemotherapy or radiation therapy. This study provides a rationale for the clinical use of rhIL-11 to preserve the integrity of the gastrointestinal mucosa during cancer treatment regimens.

The cuticle on Psilotum gametophytes

The surfaces of Psilotum gametophytes from soil and axenic culture were examined with electron microscopy and histochemistry. A lipid layer, which gave a positive reaction for all lipid stains employed, covers the surface of these gametophytes. In apical regions the lipid coating is almost as thick as the wall it coats. The wall was not stained with lipid stains but did stain for polysaccharides, cellulose, pectin, and polyphenols materials. The surface of gemmae from gametophytes grown in axenic culture was examined with electron microscopy. In young areas the lipid was amorphous, but it had a lamellate outer area in older regions of the gemmae. The surface of Psilotum gametophytes range from white in the apical region to dark brown in older areas. The browning of the surface resulted from the incorporation of tanniniferous materials into the surface wall of the older region. The cuticle along with the tanniniferous materials in the wall make the surface of these subterranean gametophytes resistant to decay and may protect them from certain biota in the soil. The cuticle may help these long-lived gametophytes to withstand any periodic drying of the soil. Key words: Psilotum, gametophyte, cuticle.

Colonization of Orchis morio protocorms by a mycorrhizal fungus: effects of nitrogen nutrition and glyphosate in modifying the responses

Effects of nitrogen nutrition and application of glyphosate (as Roundup™) on the interactions between protocorms of Orchis morio and a mycorrhizal Rhizoctonia species were investigated. Protocorms for all experiments were raised clonally in liquid culture. Split plates were used to separate the direct effects of composition of the media from effects mediated via the fungus. Mycorrhizal interactions, including coil formation and prolonged protocorm growth, were established when a relatively low nitrogen supply to the fungus (as NH4)2SO4) was combined with a high carbohydrate supply. Rejection of the fungus, associated with phenolic production, wall thickening, and lack of protocorm growth, was observed with high-carbon, high-nitrogen medium. Low carbohydrate supply, with either high or low nitrogen supply, was associated with breakaway parasitism, symptoms of soft rot, and lack of subsequent protocorm growth. Application of glyphosate at 0.5 or 1.0 mM had no effect on fungal growth and at 1.0 mM did not cause death of asymbiotic protocorms, but resulted in failure of mycorrhizal initiation. Coils were never formed and the fungus ramified through the tissues of the protocorms. The parasitism induced by glyphosate differed from breakaway parasitism, and there were no symptoms of soft rot. Assays for activity of phenylalanine ammonia lyase (PAL) and for orchinol were carried out to assess the effects of the treatments on the shikimic acid pathway. Low activity of PAL and low quantities of orchinol (together with another unidentified phenolic compound) were detected in asymbiotic protocorms. Concentrations of both were increased in the presence of the fungus, but no significant differences were observed in the various symbiotic responses in the absence of glyphosate. This is the first report of the presence of orchinol in orchid protocorms. Previous work has always been carried out on tubers, which are not usually colonized by the mycorrhizal fungi. Application of glyphosate resulted in increases in both PAL activity and orchinol production. The results are discussed in the context of orchid–fungus interactions and the mechanism of glyphosate action. Key words: orchid, mycorrhiza, parasitism, cell walls, glyphosate, phenylalanine ammonia lyase (PAL), orchinol.

The murine Hoxc cluster contains five neighboring AbdB-related Hox genes that show unique spatially coordinated expression in posterior embryonic subregions

A common feature of the murine Abdominal B (AbdB) -related Hox genes, located in the 5' regions of the four Hox clusters, appears to be a function in patterning the developing limb. As a prerequisite for studying the role of the AbdB-related Hoxc genes during limb development, we have isolated and mapped the three predicted AbdB-related Hoxc-11, -12, and -13 loci, thus defining the 5' end of the Hoxc cluster. Sequence comparisons based on the homeobox sequences of presumably all murine AbdB-related Hox genes strongly support the concept of a two step process in their evolution. As expected, Hoxc-11, -12 and -13 exhibit nested and extremely posteriorly restricted expression domains, whose anterior boundaries reflect their map positions, in accordance with the colinearity rule. A limited comparison of the primary expression domains of all five AbdB-related Hoxc genes in the developing hindlimb revealed nested and increasingly restricted domains of expression in the mesenchyme for only Hoxc-9, -10 and -11. However, separate localized expression was detected for Hoxc-9, -10, -11, -12 and possibly -13 in distal epidermal regions of the developing hind- and forelimb, whereas no expression of any of the five genes was observed in mesenchymal tissues of the developing forelimb. These data suggest a specific role for the AbdB-related Hoxc genes in patterning the hindlimb and pelvic girdle, which is separate from a second role relevant for both hind- and forelimb development.

The computer enhancement of a medical office

For several years small businesses have struggled to take advantage of the promised capabilities of the microcomputer. Limited by processor power and hindered by unyielding software these promises have gone largely unfulfilled. However, recent advances in processor speed and a new generation of user friendly software have made the microcomputer a true ally for improving the operating efficiency of an office. Now, economical computing platforms can be linked together and run with off-the-shelf software to enhance the capabilities of any medical business.

Further evidence for a correlation between nodulation genotypes in alfalfa (Medicago sativa L.) and mycorrhiza formation

The vesicular-arbuscular (VA) mycorrhizal status of three alfalfa (Medicago sativa L.) nodulation genotypes (nod⁺ fix⁺ , nod⁺ fix^- and nod^- fix^- ) was investigated using pot cultures of three fungal species from two genera (Glomus monosporum Gerd. & Trappe, Glomus fasciculatum (Thaxter) Gerd. & Trappe emend. Walker & Koske and Gigaspora margarita Becker & Hall). Roots of the nod⁺ fix⁺ genotype developed complete VA mycorrhizas with each fungus. Roots of the nod⁺ fix^- and nod^- fix^- genotypes did not develop normal VA mycorrhizal symbioses. Roots of the nod^- fix^- genotype had significantly more appressoria than roots of the other genotypes. Aborted appressoria were unable to penetrate the cortical cells of roots of nod⁺ fix^- and nod^- fix^- genotypes. Measurement of appressorium length, width and approximate contact area revealed significant differences in the size of appressoria produced by each VA mycorrhizal fungus on each alfalfa nodulation genotype. Histological studies of nod⁺ fix⁺ and nod^- fix^- genotypes colonized by Glomus versiforme (Karsten) Berch showed the presence of electron-dense material in aborted appressoria on roots of the nod^- fix^- genotype but not in appressoria on roots of the nod⁺ fix⁺ genotype.

Effect of temperature on sclerotium induction in Paxillus involutus

Paxillus involutus (Batsch.: Fr.) Fr., an ectomycorrhizal fungus, is capable of forming sclerotia, resistant vegetative propagules. Sclerotia were induced in vitro on agar-solidified modified Melin Norkrans medium by exposure of the mycelium to temperatures between 6 and 14 °C. The number and size of sclerotia varied greatly with temperature. Mycelium exposed to either 6 or 8 °C produced many smaller sclerotia (less than 1.0 mm in diameter) lacking droplets of exudate, whereas mycelium exposed to temperatures between 10 and 14 °C formed fewer, larger sclerotia (1.0 mm or more in diameter) with abundant exudate. Sclerotia were not induced from mycelium grown in liquid medium at 10 or 25 °C or from mycelium on agar-solidified medium maintained at 25 °C under a variety of conditions, including changes in medium composition and volume. Key words: sclerotia, Paxillus involutus, temperature, ectomycorrhiza, in vitro.

Ultrastructural and genetic characterization of a mutant exhibiting starch accumulation and premature leaf senescence in Medicago sativa

A mutant was isolated from irradiated seed of alfalfa, Medicago sativa L. cv. Excalibur. The mutant plant, Ex-139, displayed symptoms of premature senescence in the leaf palisade mesophyll. The leaves emerged as a normal phenotype, but light microscopy revealed that they rapidly began to accumulate starch in plastids of some cells in the palisade mesophyll. This accumulation of starch was followed by general cellular autolysis leading to the formation of necrotic regions in the palisade mesophyll. The adjacent epidermal and spongy mesophyll cells were not structurally affected. The mutant otherwise exhibited normal growth and development and was fertile. Inheritance studies indicated that the trait was transmitted to the progeny, preferentially but not exclusively, through the female, which suggests that either there is differential selection among male and female gametes or the trait is controlled by extranuclear DNA. This mutant should be useful in the study of the link between senescence and carbohydrate metabolism and in alfalfa genetics. Key words: starch metabolism, plastid, chloroplast genome, biparental inheritance.

Hox-3.6: isolation and characterization of a new murine homeobox gene located in the 5′ region of the Hox-3 cluster

Most members of the murine Hox gene system can be grouped into two subclasses based on their structural similarity to either one of the Drosophila homeotic genes Antennapedia (Antp) or Abdominal B (AbdB). All the AbdB-like genes reported thus far are located in the 5' region of their respective cluster. We describe here the isolation, structural characterization and spatio-temporal expression pattern of a new AbdB-like homeobox gene designated Hox-3.6 that is located in the 5' region of the Hox-3 cluster. Hox-3.6 has an extreme posterior expression domain in embryos of 12.5 days of gestation, a feature that has thus far only been observed for the 5' most genes of the Hox-4 cluster. Like the other members of the AbdB subfamily, Hox-3.6 exhibits spatially restricted expression in the hindlimb bud, but the expression domain is antero-proximal in contrast to the postero-distal domain reported for its cognate gene Hox-4.5. Structural analysis of the 5' region revealed the presence of a 35 bp sequence which shares homology and relative 5' position with an upstream sequence present in its two nearest downstream neighbors, Hox-3.2 and -3.1.

Adaptations of root structure in relation to biotic and abiotic factors

Roots are discussed less frequently than other plant organs in terms of their phylogenetic origin and evolutionary specialization because of limited paleobotanical information and few broad comparative studies of root structure and development. There is considerable diversity, however, in root structure among the major groups of vascular plants. Roots of many extinct and extant seedless vascular plants have a simple apical meristem (i.e., an apical cell), limited secondary growth, and in some genera, branching is accomplished by a true dichotomy of the apical meristem. Roots of seed plants evolved more complex apical meristems, branching from subterminal tissues, and in some groups extensive vascular cambium activity. Evolutionary developments related to nutrient availability include symbiotic interactions with soil fungi to form mycorrhizae, soil bacteria and cyanobacteria to form nitrogen-fixing nodules, and the modification of branching to form cluster roots. Concomitant with these specializations, root hair frequency and structure are often modified. All roots possess a suberized layer, the endodermis, and in many species, particularly among the angiosperms, a specialized suberized exodermis is present. Roots of aquatic species have evolved mechanisms either to tolerate or to avoid anaerobiosis. Roots growing in continuously wet environments possess constitutive aerenchyma whereas roots of periodically flooded plants are able to respond by forming lysigenous or schizogenous aerenchyma. Key words: roots, evolution, adaptations, structure, symbioses.

Seed reserves and early symbiotic protocorm development of Platanthera hyperborea (Orchidaceae)

Seeds of the terrestrial orchid Platanthera hyperborea consist of a thin testa and a simple embryo without a cotyledon. Epidermal and parenchyma cells of the embryo contained lipid and protein as storage reserves. Many of the protein bodies had globoid crystals identified by their P, Ca2+, Mg2+, and K+ content. Germination occurred with either Rhizoctonia cerealis or Ceratorhiza goodyerae-repentis as the fungal symbiont on Warcup's medium. The fungus entered through dead suspensor cells and triggered protocorm development and concomitant utilization of lipid and protein reserves. Fungal hyphae formed pelotons with protocorm cells initially, and these went through stages of vacuolation and collapse. Some hyphae stored small numbers of polyphosphate bodies. Clumps of degenerated hyphae were usually encased within material that stained positive with aniline blue, presumably callose. Key words: Platanthera, orchid, seed, protocorm, endophytic fungus.

Studies on Cenococcum geophilum. II. Sclerotium morphology, germination, and formation in pure culture and growth pouches

Cenococcum geophilum sclerotium morphology, germination, and formation in pure culture and growth pouches is described. On agar, germination of most field-collected sclerotia occurred within 30 days. In vitro attempts to initiate sclerotia succeeeded to varying degrees for 20 of the 22 isolates (collected in three main habitats in Oregon) in agar or peat – vermiculite but not in liquid culture. Sclerotium formation was initiated in 1-month-old cultures by branching, lateral growth, and subsequent septation of hyphae. Surface cells of compact hyphae of young sclerotia elongated, became irregularly arranged, and melanized. In growth pouches, sclerotium initials developed on the paper wick from a hyphal mat formed from convoluted hyphae. Mature sclerotia appeared as small spherical structures with linear hyphae radiating out from the surface. Sections revealed a well-differentiated rind and a medulla with pseudoparenchymatous organization. Numerous nuclei and vacuoles were distributed in both rind and medullary hyphae. Key words: Cenococcum, sclerotium, initiation, in vitro.

Structure and development of Pinus banksiana – Wilcoxina ectendomycorrhizae

Seedlings of Pinus banksiana were grown in growth pouches and inoculated with Wilcoxina mikolae var. mikolae, Wilcoxina mikolae var. tetraspora, and Wilcoxina rehmii. Ectendomycorrhizae formed between P. banksiana and W. mikolae var. mikolae developed rapidly following inoculation. The mantle was of variable width, and a large amount of mucigel was evident on the root surface. Intracellular penetration of the cortical cells by hyphae occurred one to two cells distal to Hartig net formation. Both light and transmission electron microscopy revealed labyrinthic growth of Hartig net hyphae that were densely cytoplasmic during early penetration stages but became vacuolate as the association aged. Intracellular colonization of the cortex was extensive, with the hyphae highly branched and surrounded by an interfacial matrix and cortical cell plasma membrane. The external morphology and anatomy of ectendomycorrhizae formed between W. mikolae var. tetraspora and W. rehmii and P. banksiana were similar to those described for W. mikolae var. mikolae. Key words: ectendomycorrhizae, Wilcoxina, Pinus banksiana, intracellular, Hartig net, E-strain.

Structure of ectomycorrhizae formed by Wilcoxina mikolae var. mikolae with Picea mariana and Betula alleghaniensis

The structure of ectomycorrhizae synthesized between the E-strain fungus, Wilcoxina mikolae var. mikolae and two tree species, Picea mariana and Betula alleghaniensis, was characterized by light microscopy and scanning electron microscopy. For both mycorrhizal types, mantle formation was visible on lateral roots within 10 days of inoculation. Picea mariana ectomycorrhizae had a very thin mantle whereas B. alleghaniensis ectomycorrhizae had a mantle consisting of several layers. For both mycorrhizal types, the innermost mantle hyphae were embedded in a considerable amount of mucigel on the root surface. A well-developed Hartig net with labyrinthic growth occurred in both types of mycorrhizae. Betula alleghaniensis ectomycorrhizae had a paraepidermal Hartig net, and the root epidermal cells were radially elongate at an oblique angle. The Hartig net of P. mariana ectomycorrhizae penetrated the epidermis and all layers of the cortex. The cytoplasmic density of the intercellular hyphae was greatest towards the root apex. Ectomycorrhizal associations formed by E-strain fungi were similar to ectomycorrhizae formed by other fungi. Key words: E-strain, ectomycorrhizae, Wilcoxina, Picea, Betula, Hartig net.

Interactions between three alfalfa nodulation genotypes and two Glomus species

Seedlings of a non-nodulating alfalfa (Medicago sativa L.) genotype (nod^- fix^- ) and an ineffectively nodulating alfalfa genotype (nod⁺ fix^- ) exhibited resistance to vesiscular-arbuscular mycorrhizal (VA mycorrhizal) colonization, when grown in pot cultures inoculated with either Glomus versiforme (Daniels and Trappe) Berth or Glomus intraradices Schenck and Smith. Appressoria, showing considerable variation in size and shape, developed on the root surface, but failed to form any internal structures such as arbuscules and vesicies. Wild-type (nod⁺ fix^- ) alfalfa seedlings developed normal colonization. This phenomenon will be extremely useful in studying the processes of recognition and compatibility between plant species and VA mycorrhizal fungal species.

Effect of phosphorus nutrition on morphological characteristics of vesicular-arbuscular mycorrhizal colonization of maize

The morphology of the colonization of maize (Zea mays L.) by the vesicular arbuscular mycorrhizal fungus Glomus versiforme (Daniels and Trappe) Berch was determined quantitatively to establish the stage at which colonization was limited in response to increased P nutrition. Harvests were taken 14, 19, 24 and 29 d after planting maize in a calcined clay medium to which nutrient solution containing 0.16, 0.8 or 2.4 mM P was added daily. The fraction of the root length containing arbuscules (FAC) 19 d after planting was 0.4 with 0.16 mM P, 0.3, with 0.8 mM P and 0.17 with 2.4 mM P. Corresponding shoot P concentrations were 1.5, 2.0 and 3.2 mg g^-l . Increased shoot P concentration reduced the number of appressoria per unit root length, but this accounted for only a part of the reduction in FAC. Increased root length did not account for the effect of shoot P concentration on FAC. The length of arbuscular colonized root length (total root length × FAC) per appressorium was strongly reduced in response to increased shoot P concentration. It was concluded that the reduction in FAC was mediated primarily through an inhibition of intra-radical development.

Later events in suppression of Fusarium root rot of red pine seedlings by the ectomycorrhizal fungus Paxillus involutus

Colonization of primary roots of red pine (Pinus resinosa Ait.) seedlings by two isolates of the fungal pathogen Fusarium oxysporum Schlecht. emend Snyd. & Hans. f.sp. pini in a sterile, soil-free system and a nonsterile rooting medium was suppressed for 2 months if the roots were exposed to the ectomycorrhizal fungus Paxillus involutus (Batsch.) Fr. for 1 week before being inoculated with the pathogen. Roots of protected seedlings harboured only a few hyphae of the pathogen. These were either vacuolated or filled with slightly electron-dense substances and did not penetrate host cells. In contrast, roots of seedlings not inoculated by P. involutus were extensively colonized by F. oxysporum, and host tissue vacuolation and disorganization occurred. Papillae, consisting of either small protuberances or elongate projections, were infrequently formed in response to infection. Chlamydospores of F. oxysporum that formed in the sterile system had numerous lipid deposits and amorphous thick walls but few mitochondria and little endoplasmic reticulum. Key words: biological control, ectomycorrhiza, Fusarium, Pinus resinosa, disease suppression.

Transfer cells in the sporophyte–gametophyte junction of Lycopodium appressum

The sporophyte–gametophyte interface in cultured Lycopodium appressum gametophytes consists of a sporophytic foot embedded in gametophyte tissue. Foot cells and contiguous gametophytic cells develop extensive wall ingrowths, making them transfer cells. Transfer cells in the foot of young sporophytes and in adjacent gametophyte cells have elongated, narrow wall ingrowths forming a labrynthine wall–membrane apparatus, numerous mitochondria, and plastids with variable amounts of starch. Transfer cells in older interfaces have thickened wall ingrowths, few mitochondria, plastids with numerous plastoglobuli and little starch, and a large central vacuole. Plasmodesmata do not develop between cells of sporophyte and gametophyte generations and these are, therefore, isolated symplastically during all stages of sporophyte development. Key words: Lycopodium, foot, haustorium, transfer cells, ultrastructure.

Digital imaging techniques in dermatology

Digital imaging is a versatile technique that has been infrequently used in dermatology to record visual images. We have used this technology for 10 patients to follow cutaneous lesions, including alopecia mucinosa, psoriasis, and dysplastic nevi. The setup included a personal computer, digitizer board, monitor, video camera, and lights. An introduction to electronic (digital) imaging is given and some of the many possible applications in dermatology are discussed.

Early effects of the ectomycorrhizal fungus Paxillus involutus on the root rot organism Fusarium associated with Pinus resinosa

Infection of Pinus resinosa Ait. seedlings in a sterile test tube culture system by Fusarium oxysporum f.sp. pini Schlecht. emend. Snyd. & Hans., which was determined microscopically by the presence of the fungus within root tissues, was significantly reduced within the first 6 days of infection after prior inoculation with the ectomycorrhizal fungus Paxillus involutus (Batsch) Fr. Hyphae and conidia of the pathogen were swollen and filled with osmiophilic material when P. involutus was also present in the rhizosphere of P. resinosa seedlings. Germination of F. oxysporum conidia was suppressed when they were placed in holes in P. involutus cultures on modified Melin Norkrans medium in Petri plates but was restored with removal of conidia from plates. Suppressed, ungerminated conidia had thick cell walls and large cytoplasmic inclusions. Staining using Calcofluor White M2R New revealed changes in the binding properties of septal wall material. Key words: Paxillus, Fusarium, ectomycorrhiza, disease suppression, anatomy.

Synthesis of mycorrhizae between protocorms of Goodyera repens (Orchidaceae) and Ceratobasidium cereale

Seeds of Goodyera repens were germinated on cellulose agar in the presence of Ceratobasidium cereale. Many seeds germinated to form protocorms, which were colonized by fungal hyphae. Hyphae were common around the suspensor and epidermal hairs. Newly colonized protocorm cells contained intact hyphae with few vacuoles and many mitochondria. Hyphae were separated from protocorm cell cytoplasm by matrix materials and the protocorm cell plasma membrane. Hyphae underwent progressive vacuolation and eventual lysis. Degenerating hyphae stained faintly with cellufluor, whereas degenerated hyphae and hyphal clumps stained intensely. Clumps of degenerated hyphae were isolated from protocorm cell cytoplasm by the plasma membrane and an aniline blue positive layer, which is most likely callose. Protocorm cells containing isolated clumped hyphae were frequently recolonized by hyphae.

Structure and ontogeny of Betula alleghaniensis – Pisolithus tinctorius ectomycorrhizae

The ontogeny and ultrastructure of ectomycorrhizae synthesized between Betula alleghaniensis (yellow birch) and Pisolithus tinctorius, a broad host range fungus, were studied to determine the structural modifications in both symbionts during ectomycorrhiza establishment. A number of stages, including initial contact of hyphae with the root surface, early mantle formation, and mature mantle formation, were distinguished. Interactions between hyphae and root hairs were frequent. As a paraepidermal Hartig net developed, root epidermal cells elongated in a radial direction, but wall ingrowths were not formed. Repeated branching of Hartig net hyphae resulted in extensive fine branches and the compartmentalization of hyphal cytoplasm. Nuclei and elongated mitochondria were frequently located in the narrow cytoplasmic compartments, and [Formula: see text] thickenings developed along walls of cortical cells in primary roots.

Disease suppression by the ectomycorrhizal fungus Paxillus involutus: contribution of oxalic acid

Seedlings of Pinus resinosa Ait. grown in test tubes were inoculated with the ectomycorrhizal fungus Paxillus involutus Fr. Oxalic acid was identified as one of the ethanol-soluble fungistatic and (or) fungitoxic components of the rhizosphere after fractionation by high performance liquid chromatography, paper chromatography, and gel filtration. Simultaneous inoculation of P. resinosa seedlings with authentic oxalic acid and a spore suspension of Fusarium oxysporum f.sp. pini protected the seedlings against Fusarium root rot and decreased the sporulation of F. oxysporum in the rhizosphere when compared with controls lacking oxalic acid. Quantitation of oxalic acid showed a five fold increase in production by Pax. involutus in tubes containing P. resinosa seedlings when compared with tubes lacking seedlings. The synthesis of oxalic acid by Pax. involutus is, therefore, stimulated by P. resinosa root exudate.

The time-course of disease suppression and antibiosis by the ectomycorrhizal fungus Paxillus involutus

Seedlings of Pinus resinosa Ait. grown in test tubes were inoculated with the ectomycorrhizal fungus Paxillus involutus Fr. and, one day later, with a spore suspension of the root pathogenic fungus Fusarium oxysporum Schlecht emend, Sny. & Hans f.sp. pini. Controls consisted of seedlings inoculated with plugs of sterile modified Melin Norkrans medium and F. oxysporum. Seedling survival was counted, sporulation of F. oxysporum was measured, and ethanol extractions of the rhizosphere were made, 1, 2, 3, 4, 5, 6, 8, 10 and 14 d after inoculation with the pathogen. The ethanol extractives were concentrated and assayed for fungitoxic activity by measuring the germination of F. oxysporum microconidia. Dead seedlings were first observed 3 d after inoculation with the pathogen. Sporulation of F. oxysporum was reduced significantly 3 d after seedling inoculation with P. involutus when compared with controls lacking P. involutus. The fungitoxic activity of the rhizosphere of the seedlings inoculated with P. involutus was greater than the fungitoxic activity of the rhizosphere of control seedlings, increasing strongly 2.4 d after inoculation with the pathogen. Suppression of Fusarium root rot by P. involutus may, therefore, be the result of antibiosis by this ectomycorrhizal fungus.

Ontogeny of Alnus rubra – Alpova diplophloeus ectomycorrhizae. I. Light microscopy and scanning electron microscopy

Ectomycorrhizae synthesized between Alpova diplophloeus and Alnus rubra are of two morphological types: one with a mantle formed along the entire length of the lateral roots and the other, the clavate type, with the mantle confined to the apical portion of the laterals. The morphology of the mycorrhiza is dependent on the stage of lateral root elongation at the time of colonization by fungal hyphae. Clavate mycorrhizae form on lateral roots that have already elongated at the time of fungal colonization. Fungal hyphae interact with root hairs at the base of clavate mycorrhizae. Mantles of both types are fairly compact with few extramatrical hyphae. Hartig net hyphae, which branch profusely primarily in the radial direction, are confined to the epidermis and midway along the radial walls of the outer layer of cortical cells. Second-order lateral root primordia are initiated in the mature Hartig net zone. Cells in the outer layer of the cortex of mycorrhizal roots collapse during fixation, indicating the possible presence of a barrier in the cell wall blocking the ingress of fixative.

Ontogeny of Alnus rubra – Alpova diplophloeus ectomycorrhizae. II. Transmission electron microscopy

Ultrastructural features of the two symbionts in ectomycorrhizae formed between Alnus rubra and Alpova diplophloeus change with developmental stage. In the root cap – meristem zone, hyphae penetrate between vacuolated root cap cells and become appressed to epidermal cells containing small vacuoles, plastids with starch, numerous Golgi bodies, mitochondria, and endoplasmic reticulum cisternae. In the young Hartig net zone, hyphae with few vacuoles penetrate between vacuolated epidermal cells that still contain numerous Golgi bodies but now have plastids with small starch grains. Hartig net hyphae begin to branch and eventually form a complex branching system in the mature Hartig net zone. Hartig net hyphae in the basal portion of the ectomycorrhizae synthesize lipid and finally become vacuolated.