Major Vascular Bundles Research Articles

Comparative venation costs of monocotyledon and dicotyledon species in the eastern Colorado steppe.

Leaf vein network cost (total vein surface area per leaf volume) for major veins and vascular bundles did not differ between monocot and dicot species in 21 species from the eastern Colorado steppe. Dicots possessed significantly larger minor vein networks than monocots. Across the tree of life, there is evidence that dendritic vascular transport networks are optimized, balancing maximum speed and integrity of resource delivery with minimal resource investment in transport and infrastructure. Monocot venation, however, is not dendritic, and remains parallel down to the smallest vein orders with no space-filling capillary networks. Given this departure from the "optimized" dendritic network, one would assume that monocots are operating at a significant energetic disadvantage. In this study, we investigate whether monocot venation networks bear significantly greater carbon/construction costs per leaf volume than co-occurring dicots in the same ecosystem, and if so, what physiological or ecological advantage the monocot life form possesses to compensate for this deficit. Given that venation networks could also be optimized for leaf mechanical support or provide herbivory defense, we measured the vascular system of both monocot and dicots at three scales to distinguish between leaf investment in mechanical support (macroscopic vein), total transport and capacitance (vascular bundle), or exclusively water transport (xylem) for both parallel and dendritic venation networks. We observed that vein network cost (total vein surface area per leaf volume) for major veins and vascular bundles was not significantly different between monocot species and dicot species. Dicots, however, possess significantly larger minor vein networks than monocots. The 19 species subjected to gas-exchange measurement in the field displayed a broad range of Amax and but demonstrated no significant relationships with any metric of vascular network size in major or minor vein classes. Given that monocots do not seem to display any leaf hydraulic disadvantage relative to dicots, it remains an important research question why parallel venation (truly parallel, down to the smallest vessels) has not arisen more than once in the history of plant evolution.

Bark wings are related to the primary vascular system: the case of Piptadenia gonoacantha (Leguminosae)

Abstract Bark wings are projections commonly interpreted as plant protective structures against herbivory. Their location in stems has been typically thought to be random, something that here we dispute, using Piptadenia gonoacantha as a case study. We collected stem samples from several specimens in different developmental stages from natural populations in the Brazilian Atlantic rainforest. These stems were studied in detail under light microscopy to determine the formation of bark wings and their possible correlation with other anatomical features. Stems of P. gonoacantha are deeply lobed during primary growth, with each lobe containing a large vascular bundle, alternating with smaller vascular bundles in the interlobes. On top of these lobes, prickles develop, being composed of epidermal tissue and the cortex beneath. Some of the eight lobes merge and a phellogen is installed on top of them, which starts to produce a large sheath of phellem, which will become the conspicuous bark wings of Piptadenia. The phellogen switches on and off, leaving marks resembling growth rings. The bark wings in Piptadenia have very specific positioning, always in the front of five to eight major vascular bundles, indicating that bark wings appear always in very precise locations.

INTERNAL STEM ANATOMY OF SIX BROMUS SPECIES GROWN IN DUHOK PROVINCE, KURDISTAN REGION. IRAQ

The stems of six species of Bromus (B. scoparius L., B. lanceolatus Roth., B. sterilis L., B. madritensis L., B. squarrosus L. and B. danthoniae Trin.) which belongs to Poaceae family grown in Duhok province, Kurdistan region, Iraq were examined anatomically. The samples of Bromus species have been collected from Duhok city in spring 2022. The research was carried out at Biology department, Faculty of science, University of Zakho. The study aims to distinguish between the anatomical differences among the Bromus species since they share phenotypic traits that make it difficult to distinguish them apart. The samples were fixed in formalin- acetic-acid alcohol (FAA) and cross sections were prepared, examined using compound light microscope and photographed at different power. The highest number and measures of the vascular bundles, thicknesses of cuticle, epidermis, hypodermis, and the diameters of the minor and major vascular bundles (stele) were recorded in the B. danthoniae. while, the highest dimeters of metaxylem and cross section of stem were appeared in B. scoparius and B. sterilis, respectively. On the other hand, the lowest number and measures of the above-mentioned features were fluctuated among the Bromus sterilis, B. lanceolatus, B. madritensis. The cross sections indicated that there were valuable differences in both qualitative and quantitative values of the anatomical features among the species.

Physiological and anatomical response of rice (Oryza sativa L.) ‘Hom Mali Daeng’ at different salinity stress levels

Abstract Soil salinity is a severe global stressor causing adverse impacts on irrigated land and drastically reducing crop yields, especially in rice, an important economic crop of Thailand. In this study, the impacts of salt stress on the anatomical and physiological features of 28-day-old rice (Oryza sativa L.) ‘Hom Mali Daeng’ were determined. Various NaCl concentrations (0, 50, 100, 150, and 200 mM) were applied every 2 days, with watering for 2 weeks. The results revealed that salinity stress inhibited the growth of rice. Leaf number, root size, fresh weight, and dry weight were significantly reduced. The electrolyte leakage percentage and malondialdehyde (MDA) content increased after treatment with high NaCl concentrations, while the SPAD unit and chlorophyll content were not significantly different between the control and NaCl treatments. Leaf anatomy changes were studied using freehand section and peeling techniques after salinity stress treatment. Lamina thickness in all treatments decreased, while cell wall and cuticle thickness increased. Stomatal density in all treatments significantly increased. Major vascular bundle, vessel, and phloem area of the 100 mM NaCl treatment were different when compared with the control and other treatments. The results provide information about the physiological and anatomical adaptation of ‘Hom Mali Daeng’ rice, which will be useful for further research in this and other rice cultivars.

Taxonomic relevance of petiole anatomical and micro-morphological characteristics of Clematis L. (Ranunculaceae) taxa from South Korea.

We assessed the micro-morphological and anatomical structures of the petioles of 19 Clematis taxa from South Korea. The petiole surface features were observed with the help of stereomicroscopy and scanning electron microscopy, and the anatomical features are studied via microtomy and light microscopy. The results of this study showed that the presence/absence and abundance of trichomes, petiole cross-section outlines, upper surface wings and grooves, and the number of vascular bundles were useful for species discrimination in Clematis. Among the studied taxa, C. hexapetala was the only species with a glabrous petiole surface. Two types of trichomes were observed in the other 18 taxa: long, non-glandular and flagelliform trichomes and short, glandular capitate trichomes. We found four to six major vascular bundles and a maximum of eight interfascicular vascular bundles (C. heracleifolia and C. urticifolia) in the 19 taxa. A cluster analysis based on UPGMA identified six clusters with 18 nodes. Although the number of taxa investigated was limited, taxa from the sections Tubulosae, Viorna, and Astragene clustered with each other in the UPGMA phenogram due to the overall similarity of petiole features. Based on this observation, we can conclude that most of the petiole features are limited to the species level, and thus, the data obtained could be used as descriptive and/or diagnostic features for particular taxa, which may be useful for the investigation of problematic taxa in the genus.

Limb Preservation Using Vascular Reconstruction in Patients with Large Extremity Soft Tissue Sarcomas: Results of Multi-Modality Therapy

Management of extremity sarcoma has shifted from amputation to limb salvage surgery with improvements in surgical techniques and multimodality treatment protocols. For tumors involving major neurovascular bundles, it has not been accepted as a routine practice uniformly due to fear of oncological outcomes, postoperative morbidity, and lack of expertise in microvascular surgery. We analyzed our experience of limb salvage surgery with vascular reconstruction for extremity sarcomas. Retrospective analysis of patients with extremity sarcomas undergoing limb salvage surgery through vascular reconstruction was done. The feasibility, surgical, oncological, and functional outcomes of these patients was studied. Out of 176 patients undergoing limb preserving surgery for extremity sarcoma, limb salvage using vascular resection and reconstruction was done in 14 patients. Mean age of these 14 patients was 35.4 years (19–49). Arterial reconstruction was done in 7 patients, venous in 5, and in 2 patients both arterial and venous reconstructions were performed. All the 14 patients had tumor-free margins, and none had immediate post-operative graft failure requiring amputation. Post radiation graft exposure occurred in one patient. Involvement of major vascular bundle in extremity sarcomas should not always be considered a contraindication for limb preservation. Optimal oncological outcome with preserved limb function can be achieved by arteriovenous reconstructive procedures. In places with limited resources, autologous grafts are preferred because of constraints of availability and cost.

Hydroxyproline-Rich Glycoproteins as Markers of Temperature Stress in the Leaves of Brachypodium distachyon.

Plants frequently encounter diverse abiotic stresses, one of which is environmental thermal stress. To cope with these stresses, plants have developed a range of mechanisms, including altering the cell wall architecture, which is facilitated by the arabinogalactan proteins (AGP) and extensins (EXT). In order to characterise the localisation of the epitopes of the AGP and EXT, which are induced by the stress connected with a low (4 °C) or a high (40 °C) temperature, in the leaves of Brachypodium distachyon, we performed immunohistochemical analyses using the antibodies that bind to selected AGP (JIM8, JIM13, JIM16, LM2 and MAC207), pectin/AGP (LM6) as well as EXT (JIM11, JIM12 and JIM20). The analyses of the epitopes of the AGP indicated their presence in the phloem and in the inner bundle sheath (JIM8, JIM13, JIM16 and LM2). The JIM16 epitope was less abundant in the leaves from the low or high temperature compared to the control leaves. The LM2 epitope was more abundant in the leaves that had been subjected to the high temperatures. In the case of JIM13 and MAC207, no changes were observed at the different temperatures. The epitopes of the EXT were primarily observed in the mesophyll and xylem cells of the major vascular bundle (JIM11, JIM12 and JIM20) and no correlation was observed between the presence of the epitopes and the temperature stress. We also analysed changes in the level of transcript accumulation of some of the genes encoding EXT, EXT-like receptor kinases and AGP in the response to the temperature stress. In both cases, although we observed the upregulation of the genes encoding AGP in stressed plants, the changes were more pronounced at the high temperature. Similar changes were observed in the expression profiles of the EXT and EXT-like receptor kinase genes. Our findings may be relevant for genetic engineering of plants with increased resistance to the temperature stress.

In Vivo Flow Cytometry of Extremely Rare Circulating Cells

Circulating tumor cells (CTCs) are of great interest in cancer research, but methods for their enumeration remain far from optimal. We developed a new small animal research tool called “Diffuse in vivo Flow Cytometry” (DiFC) for detecting extremely rare fluorescently-labeled circulating cells directly in the bloodstream. The technique exploits near-infrared diffuse photons to detect and count cells flowing in large superficial arteries and veins without drawing blood samples. DiFC uses custom-designed, dual fiber optic probes that are placed in contact with the skin surface approximately above a major vascular bundle. In combination with a novel signal processing algorithm, DiFC allows counting of individual cells moving in arterial or venous directions, as well as measurement of their speed and depth. We show that DiFC allows sampling of the entire circulating blood volume of a mouse in under 10 minutes, while maintaining a false alarm rate of 0.014 per minute. In practice, this means that DiFC allows reliable detection of circulating cells below 1 cell per mL. Hence, the unique capabilities of DiFC are highly suited to biological applications involving very rare cell types such as the study of hematogenous cancer metastasis.

The Early Phylogenetic Diversification of Cornales: Permineralized Cornalean Fruits from the Campanian (Upper Cretaceous) of Western North America

Premise of research. Two permineralized fruits have been found within a single calcareous concretion from the Upper Cretaceous (upper Campanian) Spray Formation of Vancouver Island, British Columbia. These fossils provide additional evidence for the initial phylogenetic diversification of Cornales, the earliest diverging asterid lineage.Methodology. Specimens were prepared using the cellulose acetate peel technique.Pivotal results. A new cornalean species, Suciacarpa xiangae sp. nov., is characterized on the basis of a well-preserved fruit specimen. This fruit is represented by a large ovoid tetralocular sclerenchymatous endocarp. Locules are crescent shaped in transverse section and accompanied by short dorsal germination valves. Valves consist of small isodiametric sclereids as well as a large number of large secretory cavities. The septum and central axis are composed of transversely oriented and interwoven fibers and elongate sclereids. There is no major central vascular bundle; however, there are num...

Temperature and light drive manganese accumulation and stress in crops across three major plant families

Environmental change is giving rise to conditions that exacerbate the solubilisation of manganese (Mn) in soil, and genetics underpins plant response to Mn oversupply. Here, Mn accumulation in foliage was investigated at the cellular level via controlled studies and fieldwork. Manganese sensitive and tolerant wheat (Triticum aestivum L.) and soybean (Glycine max Merr.) lines were given heat and Mn stress treatments exclusive of solar radiation, while the field study focused on a canola (Brassica napus L.) cultivation affected by seasonal Mn toxicity. Foliar Mn concentrations in wheat and soybean increased with Mn treatment, a response augmented by heat. Wheat under maximum stress exhibited a phenotypic difference in cellular Mn accumulation well before visible symptoms were manifested. Large cells peripheral to major vascular bundles of the sensitive line contained highly localised Mn. Excess foliar Mn in soybean was located primarily in the dermal apoplastic tissues of both cultivars, with symplastic localisation only in the Mn-sensitive cultivar. In soybean leaves, the dark patches formed due to Mn treatment had greatly elevated concentrations of co-localised Mn, calcium (Ca), phosphorus (P) and carbon (C) and were depleted in oxygen (O) and potassium (K), compared to adjacent tissues. In stressed field canola, Mn was localised most highly in the cell layers closest to the leaf upper surfaces directly exposed to solar radiation, and worse affected by chlorosis compared to the undersides. These chlorotic tissues had Mn concentrations several-fold those of green tissues. Although the spatial distribution patterns of Mn deposited in leaf cells showed some phenotypic variation, environmental factors contributed to Mn accumulation and stress. The key findings of this study highlight that climate and plant Mn toxicity are linked inextricably, and in so doing add meaningful commentary to discussion around apoplastic vs symplastic Mn toxicity mechanisms in plants.

External Compression Versus Intravascular Injection: A Mechanistic Animal Model of Filler-Induced Tissue Ischemia.

Soft tissue ischemia is a devastating and unpredictable complication following dermal filler injection. Multiple mechanisms to explain this complication have been proposed, including vascular compression, vessel damage, and intraarterial filler emboli. To elucidate the mechanism of injury, the authors introduce a mouse model, imaged with optical microangiography and laser speckle contrast imaging technologies, to demonstrate in vivo microvascular response to soft tissue and intravascular filler injection. To determine the effect of external vascular compression on distal perfusion, the authors attempted to occlude vessels with subcutaneous hyaluronic acid gel (HAG) bolus injections into the pinna of hairless mice. The authors also performed suture ligation of a major vascular bundle. Following these interventions, laser speckle and optical microangiography were performed serially over 1 week follow up. To determine the effect of intravascular HAG injection, the authors devised and validated a novel method of cannulating the mouse external carotid artery for intraarterial access to the pinna vasculature. Using this model, the authors performed intraarterial HAG injections and completed optical microangiography and laser speckle contrast imaging. Despite large HAG bolus injections directly adjacent to vascular bundles, the authors were unable to induce compressive occlusion of the mouse pinna vessels. Vascular occlusion was successfully performed with suture ligation, but optical microangiography and laser speckle contrast imaging confirmed undisturbed distal capillary bed perfusion. With intravascular HAG injection, large segments of pinna showed distinct perfusion reduction along a vascular distribution when compared with preinjection images, most noticeably at the capillary level. The novel mouse pinna model combining intravascular access and in vivo microvascular perfusion imaging has furthered the understanding of the mechanism of filler-induced tissue ischemia. Distal capillary perfusion was maintained despite external vascular compression. Intraarterial HAG filler injection, however, resulted in large areas of capillary nonperfusion and is the most likely etiology for filler-induced tissue necrosis that is observed clinically.

Extreme nickel hyperaccumulation in the vascular tracts of the tree Phyllanthus balgooyi from Borneo.

Phyllanthus balgooyi (Phyllanthaceae), one of >20 nickel (Ni) hyperaccumulator plant species known in Sabah (Malaysia) on the island of Borneo, is remarkable because it contains >16wt% Ni in its phloem sap, the second highest concentration of Ni in any living material in the world (after Pycnandra acuminata (Sapotaceae) from New Caledonia with 25wt% Ni in latex). This study focused on the tissue-level distribution of Ni and other elements in the leaves, petioles and stem of P.balgooyi using nuclear microprobe imaging (micro-PIXE). The results show that in the stems and petioles of P.balgooyi Ni concentrations were very high in the phloem, while in the leaves there was significant enrichment of this element in the major vascular bundles. In the leaves, cobalt (Co) was codistributed with Ni, while the distribution of manganese (Mn) was different. The highest enrichment of calcium (Ca) in the stems was in the periderm, the epidermis and subepidermis of the petiole, and in the palisade mesophyll of the leaf. Preferential accumulation of Ni in the vascular tracts suggests that Ni is present in a metabolically active form. The elemental distribution of P.balgooyi differs from those of many other Ni hyperaccumulator plant species from around the world where Ni is preferentially accumulated in leaf epidermal cells.

Morphological, Anatomical and Physiological Leaf Trait Plasticity ofSesleria nitida(Poaceae) in OpenvsShaded Conditions

An expression of plants response to light availability is their shade tolerance which refers to the capacity of a given plant to tolerate low light levels. Survival in a shaded environment can determine phenotypic consequences at morphological and/or physiological levels and such changes may be crucial to survive in heterogeneous and variable conditions. However, the potential plastic response of a given plant trait may be large but the observed plasticity may be lowered by resource limitations or environmental stress factors. In this context, the aim of this research was to analyze morphological, anatomical and physiological leaf traits variations of Sesleria nitida Ten. growing in different light conditions. In particular, plants growing in open (PO) and shade (PU) conditions were analyzed. The results show a 35% higher specific leaf area (SLA) in PU than in PO due to a 94% larger leaf area (LA). The higher height and width of the central and the major lateral vascular bundle in PO than in PU contribute to a higher net photosynthesis (PN) in sun than in shade conditions. Moreover, the 33% higher ratio between respiration (RD) and PN (RD/PN) in PU than in PO highlights the greater proportion of the carbon consumed by RD in the shade population requiring a greater metabolic effort for growth and maintenance. S. nitida in the shaded environment might be favored by the soil pH being a neutro-basophilous species and the larger soil water content (SWC) and mineral content contributing to maintain a positive carbon balance in this limiting condition. The plasticity analysis for open vs. the understory plants (mean plasticity index = 0.32) highlights the leaf trait variations useful to maintain a positive carbon balance where light availability is the main limiting factor. Knowledge of the capacity of S. nitida to first colonize and then modify its phenotype in response to the shade condition can contribute to a better understanding of its ecology.

POSTERIOR INTEROSSEOUS FLAP IN PEDIATRIC HAND RECONSTRUCTIONS

Purpose: to assess early and long-term results of the pediatric hand reconstructions with posterior interosseous flap, including those in children younger than 3 years old. Materials and methods: results of the hand reconstructions with posterior interosseous artery reverse flap were studied in 10 children (4 males and 6 females) aged from 1 year and 1 month to 13 years old. In 4 cases flap coverage were performed due to acquired posttraumatic hand deformity, in 6 cases reconstruction was assumed for congenital hand deformities. Combined procedures consisted of posterior interosseous artery flap coverage and other types of microsurgical reconstructions were suggested in 4 patients. Preoperative color doppler visualization of the posterior interosseous vessels were mandatory. All flaps were risen under 3.5x-4.5x magnification. Results: all flaps survived completely in 3 weeks postoperatively. There were no postoperative complications such as flap’s arterial or venous insufficiency, deep infection, or posterior interosseous nerve palsy. Nearly whole group (9 of 10) of patients and/or their parents were satisfied with the esthetic view of the reconstructed hand and donor site of the forearm 1 year postoperatively. Conclusion: posterior interosseous flap is a reliable and versatile option in pediatric hand reconstructions, providing excellent skin coverage with good color match and texture. Preservation of major vascular bundles of the forearm (radial and ulnar arteries) during flap harvest gives a possibility to perform a simultaneous microsurgical reconstructions of the hand (e.g. free toe transfer).

Centrolobium tomentosum: macro-and microscopic diagnosis of the leaf and stem

Centrolobium tomentosum Guillemin ex Benth., Fabaceae, known as "araribá-rosa", is a large tree that is widespread throughout Brazil. The bark of its stem is used in folk medicine as an astringent and the leaves are employed as a poultice for wounds and bruises. The aim of this study was to contribute to the pharmacognostic quality control of this medicinal species through a macro- and microscopic diagnosis of its leaves and stems. Mature leaves and young stems were collected at Embrapa (Colombo, PR) and analyzed using standard microtechniques. The leaves are opposite or alternate, compound, imparipinnate, oblong-lanceolate and hypostomatic with paracytic stomata. The mesophyll is dorsiventral and the midrib is biconvex with a collateral vascular bundle in a circular arrangement. The petiolule is circular and its vascular system is composed of two major vascular bundles in the middle, with smaller bundles between them. The rachis has a structure similar to the petiole, and these parts have a sclerenchymatic sheath shaped in multiple arcs, which surrounds a collateral vascular bundle that is centrally located. The stem has a uniseriate epidermis with peripheral phellogen and a sclerenchymatic sheath composed of many arcs, which surrounds the phloem. The stems and leaves also have non-glandular and glandular trichomes, phenolic compounds and idioblasts made of calcium oxalate crystals. This manuscript has an important role in the morpho-anatomical diagnosis of the Brazilian flora.

Permineralized Fagus Nuts from the Eocene of Vancouver Island, Canada

Sixty trigonal fagaceous fruits have been identified in the calcareous nodules from the Eocene Appian Way locality of Vancouver Island, British Columbia, Canada. The anatomically preserved fruits are known at various developmental stages. In transverse section, fruits are triangular, with lateral ridges that vary in shape from rounded to sharply angled. In longitudinal section, the nuts show a broad base and a tapered apex. The ovary is partitioned into three locules at the apex, and placentation is axile, with two ovules per locule. Locules merge near the base, giving the appearance of a three‐lobed ovarian cavity. This area is occupied by a single seed at maturity. The inner wall of the endocarp is tomentose. Major vascular bundles in the mesocarp occur midway between and at the lateral ridges of the nut. The nut is wingless and has an exocarp of dense sclerenchyma interrupted at the ridges by dehiscence lines that traverse the entire fruit wall. The nut surface is glabrous, except near the distal end, where trichomes emerge in proximity to three styles and surrounding perianth remnants. These nuts are assigned to the genus Fagus L. and represent the first permineralized Fagaceae of subfamily Fagoideae in the fossil record. Fagus schofieldii sp. nov. provides the earliest evidence of winglessness in Fagoideae and supports the possibility of a North American origin for the genus.

Ficus rubiginosa 'variegata', a chlorophyll-deficient chimera with mosaic patterns created by cell divisions from the outer meristematic layer.

Sections leaves of Ficus rubiginosa 'Variegata' show that it is a chimera with a chlorophyll deficiency in the second layer of the leaf meristem (GWG structure). Like other Ficus species, it has a multiseriate epidermis on the adaxial and abaxial sides of the leaf, formed by periclinal cell divisions as well as anticlinal divisions. The upper and lower laminae of the leaf often exhibit small dark and light green patches of tissue overlying internal leaf tissue. The distribution of chlorophyll in transverse sections of typical leaves was determined by fluorescence microscopy. Patches of dark and light green tissue which arise in the otherwise colourless palisade and spongy mesophyll tissue in the entire leaf are due to further cell divisions arising from the bundle sheath which is associated with major vascular bundles or from the green multiseriate epidermis. Leaves produced in winter exhibit more patches of green tissue than leaves which expand in mid-summer. Many leaves produced in summer have no spotting and appear like a typical GWG chimera. There is a strong relationship between the number of patches on the adaxial side of leaves and the number on the abaxial side, showing that the cell division in upper and lower layers of leaves is strongly coordinated. In both winter and summer, there are fewer patches on the abaxial side of leaves compared with the adaxial side, indicating that periclinal and anticlinal cell divisions from the outer meristematic layer are less frequent in the lower layers of leaf tissue. Most of the patches are small (<1 mm in longest dimension) and thus the cell divisions which form them occur late in leaf development. Leaves which exhibit large patches generally have them on both sides of the leaves. In this cultivar, the outer meristematic layer appears to form vascular bundle sheaths and associated internal leaf tissue in the entire leaf lamina.

Physical strength and its relation to leaf anatomical characteristics of nine forage grasses

Nine species of forage grasses (five C3 species and four C4 species) were planted in a controlled-environment glasshouse. The C3 plants were Festuca arundinacea Schreb, Dactylis glomerata L., Phleum pratense L., Lolium perennel L. and Poa pratensis L.; the C4 plants were Chloris gayana Kunch., Cynodon dactylon (L.) Pers., Paspalum dilatatum Poir. and Sorghum halenpense (L.) Pers. The number of major vascular bundles and minor vascular bundles, cross-sectional area, the area and proportion of sclerenchyma in a cross-section, thickness of leaf blade, and tensile and shear strength were investigated in order to determine the relationship between physical strength and anatomical characteristics. Physical strength and anatomical characteristics of leaf blades showed significant (P &lt; 0.01) variation between species. Significant correlations were detected between tensile strength and cross-sectional area in forage grasses except Festuca arundinacea. Festuca arundinacea, Dactylis glomerata, Phleum pratense, Chloris gayana and Sorghum halenpense showed significant correlations of tensile strength with the number of major vascular bundles. Festuca arundinacea, Dactylis glomerata and Lolium perennel showed significant correlations of shear strength with cross-sectional area. Festuca arundinacea, Dactylis glomerata and Paspalum dilatatum showed significant correlations of shear strength with the number of major vascular bundles. The proportion of sclerenchyma in a cross-section showed poor correlations with tensile and shear strength. Thickness of leaf blade showed poor correlations with tensile and shear strength except in Dactylis glomerata. Physical strength and anatomical characteristics of leaf blades of the C3 group differed significantly (P &lt; 0.01) when compared with the C4 group except for cross-sectional area. Tensile and shear strength showed significant correlations with cross-sectional area, sclerenchyma area and the number of vascular bundles when all nine species were treated as one group.

Chronic lower limb oedema

Contrary to popular belief, little fluid is reabsorbed by the capillary and most of it is returned to the circulation via the lymphatic. Lymph drainage begins in thin-walled, superficial initial lymphatics with wide (14 nm) oblique intercellular junctions that function as flap valves. They freely allow passage of fluid and protein into the lymphatic but prevent back flow. The initial lymphatics unite to form collecting vessels which feed into afferent lymph trunks alongside major vascular bundles. These have muscular contractile walls and semilunar valves to direct lymph flow centrally. Approximately eight litres of fluid a day pass through the afferent lymphatics. The afferent lymphatics drain into lymph nodes, where approximately four litres of fluid are absorbed daily by the nodal microcirculation, the remainder passing on to the thoracic duct via efferent lymphatics1. The duct empties into the left subclavian vein at its junction with the jugular vein.

Transmission of viral RNA and DNA to maize kernels by vascular puncture inoculation

Vascular puncture inoculation (VPI) is an effective technique for transmission of maize viruses without using arthropods or other biological vectors. It involves using a jeweler's engraving tool to push minuten pins through a droplet of virus inoculum toward the major vascular bundle in the scutellum of germinating kernels. Here, VPI is shown to be useful for introducing RNA and DNA viral genomes into maize. Maize dwarf mosaic potyvirus (MDMV) virions, MDMV genomic RNA, foxtail mosaic potexvirus (FoMV) genomic RNA and maize streak geminivirus (MSV) DNA were introduced into kernels by VPI, and infection rates determined. At high concentrations, both MDMV virion and genomic RNA preparations produced 100% infection of susceptible maize. However, MDMV genomic RNA was transmitted with about 100-fold lower efficiency than virions. FoMV genomic RNA and MSV DNA were transmitted at lower efficiency than the MDMV RNA, and the highest transmission rates were about 50%. Ribonuclease A pretreatment prevented genomic MDMV and FoMV RNA transmission, but not MDMV virion transmission indicating the viral RNA was the infectious entity. Proteinase K (ProK) pretreatment reduced transmission of MDMV RNA suggesting that integrity of the viral genomic protein bound covalently to the viral RNA may be important for efficient transmission.