Stem Surface Research Articles

Development of Parasitic Organs of a Stem Holoparasitic Plant in Genus Cuscuta.

Parasitic plants infect a broad range of plant species including economically important crops. They survive by absorbing water, minerals, and photosynthates from their hosts. To support their way of life, parasitic plants generally establish parasitic organs that allow them to attach to their hosts and to efficiently absorb substances from the vascular system of the host. Here, we summarize the recent progress in understanding the mechanisms underlying the formation of these parasitic organs, focusing on the process depicted in the stem holoparasitic genus, Cuscuta. An attachment structure called “holdfast” on the stem surface is induced by the light and contact stimuli. Concomitantly with holdfast formation, development of an intrusive structure called haustorium initiates in the inner cortex of the Cuscuta stem, and it elongates through apoplastic space of the host tissue. When haustoria reaches to host vascular tissues, they begin to form vascular conductive elements to connect vascular tissue of Cuscuta stem to those of host. Recent studies have shown parasite-host interaction in the interfacial cell wall, and regulation of development of these parasitic structures in molecular level. We also briefly summarize the role of host receptor in the control of compatibility between Cuscuta and hosts, on which occurrence of attachment structure depends, and the role of plant-to-plant transfer of long-distance signals after the establishment of conductive structure.

An advanced species of the fern Botryopteris Renault from the Permian of southwestern China

We describe a new species of the Paleozoic fern genus Botryopteris in volcanic tuffs from the Lopingian (upper Permian) aged Junlian Formation in SW China's Sichuan Province. The species has a large stem and stele compared to those of some other species of the genus. Xylem strands of the leaf trace and rachis are “ω”-shaped in cross section and comprise two long lateral arms and a single, shorter median arm. Parenchyma is distributed among the stem metaxylem tracheids and is more common in the central region of the stele that comprises a parenchymatized protostele. Several mesarch protoxylem strands, decurrent from leaf traces, are visible in each cross section of the protostele. Root traces originate from the lateral side of the leaf trace within the stem cortex. The stem surface is covered by thick, multiseriate, multicellular trichomes. Botryopteris multifolia sp. nov. represents the stratigraphically youngest known species of the genus and has a combination of derived evolutionary characteristics including its large stem size, parenchymatized protostele, elaborate trichome structure, roots originating from leaf traces, and the construction of xylem strand of the leaf trace and rachis with distinctive pinna trace formation and emission. It is more similar in leaf anatomy to the Gondwanan species B. nollii from the Permian of Brazil and less like late Pennsylvanian botryopterids from Euramerica. Finally, we consider the evolutionary implications of features shared between Permian members of the botryopterids and catenalean-type plants including members of the Osmundales stem group family Guaireaceae (Shuichengella, Zhongmingella, Tiania) and the enigmatic early ferns Rastropteris and Catenopteris.

Removal of colour using banana stem adsorbent in textile wastewater

The potential use of banana stem adsorbent has been investigated via batch adsorption experiment. A series of batch experiment was carried out to determine the effect of various adsorbent dosage ( 0.2 – 1.4 g) and various contact time ( 15 – 120 minutes). Analysis on adsorption isotherm was done using Langmuir and Freundlich model. In addition to it, the behaviour and mechanism of adsorption was analysed using kinetic model, namely Pseudo-first order and pseudo second order kinetic. The result shows that more than 90% of colour was removed at optimum dosage of 1 g of banana stem adsorbent in 100 mL synthetic dye at optimum contact time of 90 minutes. Analysis of isotherm models showed that the adsorption of colour by banana stem adsorbent was fitted to Freundlich with coefficient of determination, r1 of 0.917. Adsorption kinetics of colour showed that Pseudo-second order fit better (r2 = 0.99) than Pseudo-first order (r2 = 0.94) kinetic model. From the result, it was indicated that the adsorption of colour occurred by multilayer on a heterogeneous surface of the banana stem through the chemical reaction process. As a conclusion, the use of banana stem adsorbent has good potential for colour removal in textile wastewater treatment because of low cost of the media. Thus, it is an alternative to overcome problems related to an excessive of colour in dye wastewater treatment plant.

Characterization of Excreted Salt from the Recretohalophytes Distichlis spicata and Spartina pectinata

Recretohalophytes are salt‐tolerant plants that excrete excess salts through specialized glands on their leaf surfaces. They have the potential to be applied as a phytotechnology to remediate salt‐impacted soils by removing the salt from the soil and allowing it to be mobilized on the wind (haloconducted) and hence dispersed over a wide area where the salt ions will act as nutrients rather than pollutants. This study is the first to characterize the excreted salts of two recretohalophytic grasses, Spartina pectinata Bosc ex Link and Distichlis spicata (L.) Greene using scanning electron microscopy (SEM). At above‐optimal conditions for salt excretion (i.e., >65% humidity and >26°C), salt appeared on the stem and leaf surfaces as a sap‐like excretion that could not be easily mobilized. The mean diameter of the salt crystals excreted by S. pectinata (31 ± 24 μm) is significantly smaller than the diameter of those excreted by D. spicata (49 ± 22 μm) (p < 0.05). Spartina pectinata excreted significantly more salt crystals per unit area of plant surface (60 ± 41 crystals mm−2) than D. spicata (27 ± 16 crystals mm−2). These salt crystal characteristics can now be used to assist with determining the optimal species for haloconduction, and in particulate dispersal modeling systems to help determine the fate of the excreted salts once they become airborne by wind.Core Ideas Recretohalophytes excrete salts that disperse via winds through “haloconduction.” The mean diameter of excreted salt crystals varied by plant species. The mean number of salt crystals per unit of leaf area varied by plant species. Air particulate modeling can use this to assess the effectiveness of salt dispersal. Salt excretion and dispersal may prove to be a useful form of salt remediation.

Human Stem Cell Responses and Surface Characteristics of 3D Printing Co-Cr Dental Material

Recently, the selective laser melting (SLM) method of manufacturing three dimensional (3D) dental prosthetics by applying a laser to metal powder has been widely used in the field of dentistry. This study investigated human adipose derived stem cell (hADSC) behavior on a 3D printed cobalt-chrome (Co-Cr) alloy and its surface characteristics and compared them those of a nickel-chrome (Ni-Cr) alloy. Alloys were divided into four groups according to the material and manufacturing methods. Co-Cr disks were manufactured with three different methods: a conventional casting method, a metal milling method, and an SLM method. Ni-Cr disks were manufactured with a conventional casting method. The surface roughness and compositions of the disks were assessed. hADSCs were then cultured on the disks. Cell morphologies on the disks were analyzed by a field emission scanning electron microscope (FE-SEM). Cell proliferation was assessed with a bromodeoxyuridine (BrdU) assay kit. Cell viability was evaluated with a water-soluble tetrazolium salt (WST) assay kit. There were no differences in surface roughness between all groups. The cells were well attached to the disks, and morphologies of the cells were similar. The cell proliferation and viability of the Ni-Cr disks were significantly lower than the other groups. However, the Co-Cr disks showed no differences in their different fabricating methods. In conclusion, the biocompatibility of 3D printed Co-Cr alloys showed comparable results compared to that of the conventional casting method, and these alloys were more biocompatible than Ni-Cr alloys.

Pythium ultimum Causing Black Stem Rot of Brassica oleracea var. alboglabra in China

Brassica oleracea var. alboglabra, locally known as gailan, is an important leafy vegetable crop of China, widely cultivated in southern provinces. During 2016 to 2018, stem rot disease was seen in some agricultural fields around Guangzhou city of Guangdong province, China. Plants were affected by the disease at all growth stages. Black necrotic lesions developed and extended upward from the base of the stem on diseased plants. Symptoms first appeared as black lesions covering the stem surface. Under severe infestation, the infected stems got cracked and the whole plant collapsed. Mycelial masses were seen on the infected stem surface of some of the infected plants. Onset of rain increased disease incidence each year, and it reached up to 30% in severely infested fields. A large number of oospores were seen in infected plant tissues microscopically. Infected tissues were taken from the margins of the diseased stem and cut into small pieces (5 × 5 mm). This plant material was surface sterilized by 2% sodium hypochlorite solution, rinsed in sterile water several times, and placed on to V8 medium plates. Fungi were purified by successive subculturing on fresh media plates using the hyphal tipping technique. The fungi were rapidly growing with coenocytic mycelia. Light microscopy showed terminal and intercalary sporangia, thick-walled aplerotic oospores, and globose intercalary and terminal hyphal swellings. The diameters of 20 sporangia and oospores were 19.7 to 27.3 μm (mean 22.18 μm; SD 2.4) and 16.5 to 23.9 μm (mean 19.02 μm; SD 1.8), respectively. Morphological characters were consistent with Pythium ultimum Trow (Van der Plaats-Niterink 1981; Watanabe 2002). Genomic DNA was extracted from mycelial masses using a Dzup fungal DNA extraction kit (Sangon Biotechnology, Shanghai, China). Molecular identifications were performed by amplifying the internal transcribed spacer region (ITS) using primers ITS1/ITS4 (White et al. 1990) of five pathogen isolates. BLAST analysis showed that all the isolates shared 99% nucleotide identity with the previously submitted P. ultimum sequences (GenBank accessions KU210389, KU210177, and AY243070). The nucleotide sequence has been assigned GenBank accession number MK615615. Pathogenicity tests were performed on plants of B. oleracea of variety Dasun using five different pathogen isolates (VRI-1 to VRI-5). Pathogen isolates were considered as the treatments, and each treatment consisted of 12 individual plants. Uninoculated potato dextrose agar (PDA) was included as the control. The experiment was performed as a randomized complete block design and repeated twice. Plants were raised in plastic pots filled with sterilized commercial potting mix. Two weeks after emergence, plants were inoculated with quarter-strength PDA medium pieces (5 × 5 mm) colonized with different isolates of P. ultimum separately. The inoculum was placed 5 to 10 mm away from the plants. Plants were incubated in a growth room at 25 ± 2°C and 16-h/8-h photoperiod. Symptoms developed within 10 days after inoculation. Infected plants showed reduced growth and dark brown lesions on stem that coalesced and turned into a rotted mass. All five pathogen isolates caused disease, and none of the pathogen isolates showed disease incidence less than 80%. Stems of diseased plants showed numerous oospores when observed under a microscope. Control plants remained healthy and uninfected. The same pathogen was consistently reisolated from infected tissues of plants. Pathogen identity was reconfirmed by both molecular and morphological methods. To our knowledge, this is the first report of Pythium stem rot of B. oleracea var. alboglabra caused by P. ultimum in China. This disease can be of great economic loss because the whole aboveground portion of this plant is of economic importance and is consumed as a salad or cooked as a vegetable. Timely measures must be taken to manage this disease. This disease may increase in incidence in rainy seasons.

Biomechanical Performance of the Cemented Hip Stem with Different Surface Finish

The integrity of the cemented fixation interface is responsible for the long-term longevity of artificial hip prostheses. Metallic stems with roughened surfaces are considered to provide stronger adhesion with cement. However, clinical studies have reported that roughened stems show a lower survival rate than polished stems. These studies clearly reveal that the causes of artificial stem loosening are very complicated and multifaceted. Therefore, this study was conducted to investigate the mechanical effect of stem surface finish in cemented hip replacement. To accomplish this, a series of cement–metal specimens were tested configurations to assess the mechanical characteristics of the cement–metal interface specimens. A finite elemental model of cemented femoral prostheses was then created, in which the cement–stem interface was assumed to be in different bonding states according to the experimentally measured interface properties. The failure probabilities of the cement mantle and cemented interface under physiological loadings were evaluated. Experimental results indicate that the polished metal produced higher interfacial tensile and lower shearing strengths than the roughened metal. The polished stems were predicted to induce a lower failure probability of cement mantle and higher integrity of the cement–stem interface when compared to the roughened stem. Overall, current results provide significant evidence to support the clinical outcomes of cemented hip prostheses with different stem surface finishes.

Microstructural and histochemical analysis of aboveground organs of Centaurea cyanus used in herbal medicine

Centaurea cyanus L. is a valuable source of many different bioactive substances. It is used in herbal medicine, but the structure of its organs used as raw material and secretory tissues has been insufficiently examined. The aim of this paper was to investigate the microstructure of C. cyanus flowers, bracts, stems and leaves with particular emphasis on secretory structures. Moreover, the main classes of secondary metabolites present in the secretion were identified and the taxonomic value of some micromorphological and anatomical features was analysed. Histochemical, micromorphological and ultrastructural analyses of aboveground organs of C. cyanus were carried out using light, fluorescence, scanning and transmission electron microscopy. The analyses revealed the presence of petal papillae and a characteristic cuticular pattern on the petals, stamens and stylar hairs. There were four types of non-glandular trichomes on the bracts, leaves and stem surfaces. The epidermal cells of the bracts contained prismatic calcium oxalate crystals. Two kinds of secretory structures, i.e. glandular trichomes and ducts, were observed in the C. cyanus organs. The glandular trichomes were located on the bract and stem surfaces, and the ducts were detected in the leaves and stems. Ultrastructural analyses of the epithelium of the ducts showed the presence of strongly osmiophilic insoluble phenolic material in vacuoles as well as moderately osmiophilic insoluble lipidic material in elaioplasts and vesicles. The results of histochemical assays showed a heterogeneous nature of the duct secretion, which contained essential oil, lipids, flavonoids, tannins and terpenes containing steroids.

Glandular trichomes in the tree-basil (Ocimum gratissimum L., Lamiaceae): Morphological features with emphasis on the cytoskeleton

The morphology, histochemistry and ultrastructure of glandular trichomes have been studied in several plant species and their subcellular features are closely related to the composition of the secretion produced. Recent studies have proposed a fundamental role for cytoskeletal elements in the intracellular processes of secretion, culminating with storage of the exudate in cellular compartments or its extracellular release. However, this topic has been poorly studied in plant secretory cells. Ocimum gratissimum L. (Lamiaceae) is an aromatic species widely utilized as a condiment and in popular medicine. Here, we analyzed the distribution, morphology and histochemistry of the glandular trichomes in O. gratissimum, highlighting the distribution of the microtubules and actin filaments in the different glandular morphotypes. Glandular trichomes were observed in the stem, leaves, bracts, sepals and adaxial surface of the petals. Three morphotypes of glandular trichomes were identified and found to secrete different categories of chemical compounds. Plastids devoid of grana and smooth endoplasmic reticulum were abundant in cells secreting lipophilic substances. In these cells, microtubules were intensively labeled. Cells producing mainly hydrophilic compounds were characterized by the presence of dictyosomes with vesicles sprouting. Actin filaments were strongly marked in these cells. Our convergent techniques in microscopy enabled us to establish an association among the glandular morphotypes, their subcellular aspects, the prevalence of the different cytoskeletal elements in their cells and the composition of the secretion produced by them.

Systematic Study on TiO₂ Crystallization via Hydrothermal Synthesis in the Presence of Different Ferrite Nanoparticles as Nucleation Seeds.

In the present work, the crystallization of anatase TiO₂ nanoparticles (NPs), using different ferrite nanoparticles with different chemical composition, dimensions and shape as nucleation seeds, was investigated. In particular, CoFe₂O₄, NiFe₂O₄ and Fe₃O₄ NPs with a volume ratio equal to 1:1000 with respect of TiO₂ amount, were used in order to investigate the synthesis of nanocrystalline tetragonal anatase TiO₂ by a hydrothermal synthesis. In addition, Lu₂O₃ nanoparticles were also used to detect the effect of a non-magnetic nanoparticle on the synthesis and nanocrystallization of titania. For each sample, a deep physical characterization was performed by XRD (with a Rietveld refinement of the structural data), FE-SEM, STEM, HRTEM, DSC analysis and BET surface area measurement. Furthermore, for some samples, the photocatalytic activity was investigated by degradation of methylene blue in aqueous medium, in the framework of a standard ISO 10678:2010 protocol. The hydrothermal synthesis was performed with a 3 hours' thermal treatment, at a pressure of approximatively 9 bar and a temperature significantly lower (Tmax═150 °C) than the usual temperature necessary to obtain crystalline anatase TiO₂ (Tcryst═350 °C). The results give evidence that the mere presence of a nucleation seeds in the hydrothermal reactor, without any particular need for the composition and morphology, leads to crystalline anatase TiO₂ nanoparticles with high photocatalytic performances.

Conquering the Rock-A Retrospective Single-Center Experience of the Transapical Petrosal Transtentorial (Kawase) Approach: Operative Technique and Impact on Cranial Nerve Function.

Since its description in 1985, the transapical petrosal transtentorial or Kawase approach has become a viable option of approaching lesions located in and around the apex of the petrous bone, Meckel's cave, and the anterolateral surface of the brain stem while preserving cranial nerve function. At the Brain Tumor Center, Erasmus MC, 25 patients were treated using the Kawase approach between 2004 and 2018 for various indications, including petroclival meningiomas, chondrosarcomas, pontine cavernomas, trigeminal schwannomas, and posterior circulation aneurysms. Hearing preservation was achieved in all patients; new abducens nerve and trochlear nerve palsies were present in three and six patients, respectively, of which a total of eight required ophthalmological correction. Seven patients experienced a cerebrospinal fluid fistula postoperatively, but this complication appeared self-limiting in all cases, with one patient experiencing secondary meningitis. After modifying our closure technique, the rate of fistulas dropped to zero. The observed direct postoperative mortality was 4% (one patient), although not related to the approach itself. In conclusion, the Kawase approach is a highly complex, but essential middle fossa approach, extremely robust, and able to serve a wide array of pathologies together with its extensions. It is very accurate for performing hearing preservation surgery, but not without caveats and inherent risk of complications.

Expression of Gp78/Autocrine Motility Factor Receptor and Endocytosis of Autocrine Motility Factor in Human Thyroid Cancer Cells.

Gp78/autocrine motility factor receptor (Gp78/AMFR) is a cancer-associated endoplasmic reticulum-localized E3 ubiquitin ligase and also the cell surface receptor for autocrine motility factor (AMF). The study objective was to determine the association between Gp78/AMFR and AMF endocytosis in thyroid cancer cells. Gp78/AMFR expression and AMF internalization were measured in differentiated thyroid cancer (DTC) and anaplastic thyroid cancer (ATC) cell lines and in freshly resected human papillary thyroid cancers (PTC) relative to benign thyroid tissue. Spheroid-like aggregates generated from explants of cancer, goiter, and collateral thyroid tissue were assessed for expression of cancer stem cell markers, surface Gp78/AMFR and AMF endocytosis. DTC cell lines showed elevated total and surface Gp78/AMFR and AMF internalization relative to ATC lines. Gp78/AMFR, Oct-4 and Sox-2 protein expression, Gp78/AMFR surface expression and AMF internalization were elevated in PTC-derived aggregates relative to fibroblasts. Elevated levels of Gp78/AMFR expression and AMF internalization in PTC were associated with expression of cancer stem cell markers. Gp78/AMFR expression and AMF uptake are more closely associated with DTC compared to benign thyroid lesions or ATC and with PTC-derived cancer stem-like cells.

Leaf and stem epicuticular wax structures in Lonicera species (Caprifoliaceae)

Epicuticular waxes are found on the surface of the plant epidermis as crystal structures which show morphological diversity and may be useful in plant systematics. The aim of this study was to recognise the diversity of the epicuticular wax cover on leaves and stems of Lonicera species (Caprifoliaceae) and to estimate the taxonomic value of wax traits. Adaxial and abaxial sides of the leaves and the stem surface in 35 taxa were investigated through a scanning electron microscope (SEM). The assessment was prepared on the basis of the presence or absence of basic types of wax structures and their dimensions, using categorical response analysis, multiple correspondence analysis and cluster analysis.In the analysed species, we found differences in the wax layer structure on the surfaces of the leaves and stems. Apart from the smooth layer, tubules and platelets can be found. Tubules are considerably more frequent than platelets. In many cases, the same plant part produces more than just one wax type.Our analysis indicates that wax structures are not very informative for the taxonomy of Lonicera, because we observed only a weak correspondence between the presence or absence of some types of wax tubules and the infrageneric classification of the genus. However, in particular cases these new data can be used for species identification.

Changes in the morphology of microgrooved stem tapers with differing assembly conditions

BackgroundFretting and corrosion at the head-stem taper junction has been cited as a potential clinical concern. Material loss measurement is a vital tool for quantifying changes due to in vitro, in vivo, and/or ex-vivo implant experience. Material loss measurement requires reconstruction of pre-implantation geometry to delineate damage. This is straightforward in principle for plain machined tapers, integrating between a fitted interpolated cone and the measured data. Mathematical filtration methods have been developed to remove this texture and facilitate measurement. The extent to which the assembly process could influence filtration accuracy is not currently known. MethodsAn engagement/ disengagement study was performed on 27 head/ stem pairs using 2, 4, and 8kN impact loads. Impact was delivered in three locations; axial, 10o anterior, and 10o anteroproximal. Pull-off force was measured, and stems were measured pre and post assembly using a Talyrond 365 roundness measurement machine. ResultsAn increase in the plastic deformation of microgrooves and pull-off force was noted with increasing assembly loads. Off-axis impaction resulted in reduced pull-off strength and reduced uniform microgroove distortion. Volumetric change between pre and post assembly was below the noise threshold on stem and head surfaces. DiscussionThe measurement method was shown to be capable of capturing linear microgroove deformation of 1 μm peak – peak and volume loss above 0.1mm3. Lower peak load was noted when impacting a seated head when compared with engagement of discrete heads and stems, under the same assembly conditions.

Study on properties of copper-containing austenitic antibacterial stainless steel

ABSTRACTThe influence of different solution temperature and ageing temperature on the antibacterial and mechanical properties of antibacterial stainless steels with different copper contents was studied in depth by the control variable method. On the front side, the precipitation of the copper-rich phase is reflected by the hardness and antibacterial properties through TEM, STEM and side surfaces. As a result, it was found that lath martensite exists after the antibacterial heat treatment, and the precipitated copper-rich phase is approximately 15 nm in distribution and is in parallel with the matrix.

Characterization of Human Mesenchymal Stem Cells from Different Tissues and Their Membrane Encasement for Prospective Transplantation Therapies.

Human mesenchymal stem cells can be isolated from various organs and are in studies on therapeutic cell transplantation. Positive clinical outcomes of transplantations have been attributed to both the secretion of cytokines and growth factors as well as the fusion of donor cells with that of the host. We compared human mesenchymal stem cells from six different tissues for their transplantation-relevant potential. Furthermore, for prospective allogenic transplantation we developed a semipermeable hollow-fiber membrane enclosure, which would prevent cell fusion, would provide an immune barrier, and would allow for easy removal of donor cells from patients after recovery. We investigated human mesenchymal stem cells from adipose tissue, amniotic tissue, bone marrow, chorionic tissue, liver, and umbilical cord. We compared their multilineage differentiation potential, secretion of growth factors, and the expression of genes and surface markers. We found that although the expression of typical mesenchymal stem cell-associated gene THY1 and surface markers CD90 and CD73 were mostly similar between mesenchymal stem cells from different donor sites, their expression of lineage-specific genes, secretion of growth factors, multilineage differentiation potential, and other surface markers were considerably different. The encasement of mesenchymal stem cells in fibers affected the various mesenchymal stem cells differently depending on their donor site. Conclusively, mesenchymal stem cells isolated from different tissues were not equal, which should be taken into consideration when deciding for optimal sourcing for therapeutic transplantation. The encasement of mesenchymal stem cells into semipermeable membranes could provide a physical immune barrier, preventing cell fusion.

Three-Dimensional Surface Reconstruction of the Human Cochlear Nucleus: Implications for Auditory Brain Stem Implant Design.

Objective The auditory brain stem implant (ABI) is a neuroprosthesis placed on the surface of the cochlear nucleus (CN) to provide hearing sensations in children and adults who are not candidates for cochlear implantation. Contemporary ABI arrays are stiff and do not conform to the curved brain stem surface. Recent advancements in microfabrication techniques have enabled the development of flexible surface arrays, but these have only been applied in animal models. Herein, we measure the surface curvature of the human CN and adjoining regions to assist in the design and placement of next-generation conformable clinical ABI arrays. Three-dimensional (3D) reconstructions from ultrahigh T1-weighted brain magnetic resonance imaging (MRI) sequences and histologic reconstructions based on postmortem adult human brain stem specimens were used. Design This is a retrospective review of radiologic data and postmortem histologic axial sections. Setting This is set at the tertiary referral center. Participants Data were acquired from healthy adults. Main Outcome Measures The main outcome measures are principal curvature values (Kmin and Kmax) and global radius of curvature. Results The CN was successfully extracted and rendered as a 3D surface in all cases. Significant curvatures of the CN in both histologic and radiographic reconstructions were found with global radius of curvature ranging from 2.08 to 8.5 mm. In addition, local curvature analysis revealed that the surface is highly complex. Conclusion Detailed rendering of the human CN is feasible using histology and 3D MRI reconstruction and highlights complex surface topography that is not recapitulated by contemporary stiff ABI arrays.

Frequency of plant visits by the generalist ant Lasius niger depends on the surface microstructure of plant stems

The aim of this study was to analyze the visiting frequency of generalist ants to plants with different surface textures of their stems. We performed an experiment in which Lasius niger ants were attracted by sweet drops to flower stems of five plant species bearing different surface structures: Alchemilla mollis (wax projections and long tread-shaped trichomes), Lilium lancifolium (without wax, with ribbon-shaped trichomes and cuticular folds), Salvia nemorosa (without wax, with trichomes of various lengths and cuticular folds), Tulipa gesneriana (wax projections, no trichomes), and Paeonia lactiflora (neither of above surface features). As control samples, dry, smooth bamboo sticks were placed in the vicinity of experimental plant stems. Using cryo scanning electron microscopy, the micromorphology of stem surfaces was examined. The present study demonstrates that, on the one hand, ants avoid climbing wax-covered stems, if trichomes are lacking. On the other hand, some trichome-bearing stems having specific trichome micromorphologies were also ignored by ants. The strongest attractiveness was revealed in glossy stems and stems covered with soft/floppy trichomes. This experiment supports the hypothesis that when exposed to a diversity of plant stems in the field, generalist ants choose substrates where their locomotion is less hampered by obstacles or slipperiness of surface. Presumably, additional locomotory efforts needed to master climbing on “greasy” or “spiny” stems lead to an increase of costs-to-benefits ratio. However, since every type of stem surface was visited at least once during the experiment, it does not automatically mean that ants are not capable of walking on such challenging surfaces.

Cemented Femoral Component Use in Hip Arthroplasty.

Elderly patients undergoing both elective and nonelective hip arthroplasty contribute markedly to health care spending, and the current aging population is likely to require even more resources. Several national joint replacement registries show a lower risk of revision surgery in patients older than 75 years who received cemented femoral components compared with cementless implants for primary total hip arthroplasty. Despite a higher incidence of early periprosthetic femoral fracture, noncemented femoral components are being used with increasing frequency in elderly patients worldwide. Improvements in cementing technique and modifications to cemented stem design over several decades allow surgeons to obtain femoral component fixation in poor-quality bone with a relatively low risk of complications. Achieving durable cemented stem fixation requires the surgeon to understand the basic handling properties of cement, how to prepare the femoral bone, and differences in stem design and surface finish.

Paris lihengiana (Melanthiaceae: Parideae), a new species from Yunnan, China

Paris lihengiana (Melanthiaceae), a new species from Yunnan Province, China, is described and illustrated based on evidence from morphological characters and molecular phylogeny. It differs from other species of Paris in its pubescent stem, pedicel and abaxial leaf surface, as well as other characters. Molecular phylogenetic analysis of 33 taxa in Paris was conducted based on nuclear ribosomal ITS and six plastid markers. Paris lihengiana is supported as a new species by both morphological characters and molecular data.