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PubMed2004

Roles for Class III HD-Zip and KANADI genes in Arabidopsis root development.

Meristems within the plant body differ in their structure and the patterns and identities of organs they produce. Despite these differences, it is becoming apparent that shoot and root apical and vascular meristems share significant gene expression patterns. Class III HD-Zip genes are required for the formation of a functional shoot apical meristem. In addition, Class III HD-Zip and KANADI genes function in patterning lateral organs and vascular bundles produced from the shoot apical and vascular meristems, respectively. We utilize both gain- and loss-of-function mutants and gene expression patterns to analyze the function of Class III HD-Zip and KANADI genes in Arabidopsis roots. Here we show that both Class III HD-Zip and KANADI genes play roles in the ontogeny of lateral roots and suggest that Class III HD-Zip gene activity is required for meristematic activity in the pericycle analogous to its requirement in the shoot apical meristem.

Arabidopsis↗
PubMed2000

A Krüppel-like zinc finger protein is involved in nitrogen-fixing root nodule organogenesis.

Mechanisms regulating plant host differentiation of the nitrogen-fixing root nodules remain mostly unknown. Sinorhizobium meliloti induces this process in Medicago sativa in which the Mszpt2-1 gene is expressed in vascular bundles of roots and nodules. This gene codes for a Krüppel-like zinc finger protein, a class of transcription factors involved in many animal developmental processes. Expression of Mszpt2-1 in yeast cells conferred osmotic tolerance. Antisense plants grew normally but developed nonfunctional nodules, in which differentiation of the nitrogen-fixing zone and bacterial invasion were arrested. Hence, a vascular bundle-associated Krüppel-like gene is required for the formation of the central nitrogen-fixing zone of the root nodule.

Amino Acid Sequence↗
PubMed2005

Cochleata: getting to the root of legume nodules.

The homeotic mutant of Pisum sativum, cochleata, has stipules replaced by alternative leaf components, abnormal flowers and reduced fertility. Although the root system dry weight, root lengths and nodule numbers of cochleata are similar to those of its wild type, the nodulation phenotype of the mutant is unique. The nodules typically dichotomously branch and multiple callus and root structures emerge from their meristems. These nodule-roots incorporate a peripheral vascular bundle of the nodule into their own central vascular cylinder. Both the nodules and roots of the hybrid structures appear functional. Roles for COCHLEATA in development are discussed.

Mutation↗
PubMed1993

A new classification of vascularized flaps in plastic and reconstructive surgery.

Advances during the last 15 years in microsurgical technique and in our understanding of vascular anatomy have led to the development of two new branches of plastic and reconstructive surgery. The first is the transfer of free composite flaps with microvascular anastomoses. The second is transposition of island flaps solely on a proximal or distal vascular bundle. Both types of operations require an adequate vascular pedicle to provide sufficient blood circulation for flap viability and survival in the recipient site.

Adolescent↗
PubMed1990

Histochemical analysis of CaMV 35S promoter-beta-glucuronidase gene expression in transgenic rice plants.

The cauliflower mosaic virus promoter is commonly used to drive transcription of chimeric genes in transgenic plants, including the cereals. To determine the tissue and cell types of cereal plants that the promoter functions in, transgenic rice plants containing a CaMV 35S promoter/GUS chimeric gene were analyzed for GUS activity. Insertion of a 35S/GUS chimeric gene at low copy number into chromosomal DNA of plants regenerated from electroporated protoplasts was confirmed by gel blot hybridization analysis of uncut and endonuclease-digested DNA. Quantitative measurement showed that GUS activity was some tenfold higher in rice leaves than in tobacco leaves whereas activities obtained for rice roots were similar to those reported for tobacco roots. Histochemical localization of GUS activity confirmed that the CaMV 35S promoter functions in cells of the leaf epidermis, mesophyll and vascular bundle. It is also active in the cortex and vascular cylinder of the root, but only marginally active in the root epidermis. The generally similar distribution and levels of GUS activity obtained in differentiated tissue of stably transformed rice plants indicates the value of the CaMV 35S promoter as a positive control for studies in gene activity in transgenic monocots and dicots.

Cloning, Molecular↗
PubMed2006

Experimental study of vascularized tissue-engineered bone grafts.

BACKGROUND: Vascularized bone grafting has become a useful method for treatment of large bone defects and infected nonunions that lack adequate blood supply. This method has disadvantages, however, such as donor-site complications. To overcome these disadvantages, the authors developed a new method for creating vascularized tissue-engineered bone grafts in an experimental model. METHODS: Fisher rat bone marrow mesenchymal stem cells were cultured for 2 weeks in fully opened, interconnected, porous hydroxyapatite ceramic. The composites of mesenchymal stem cells and hydroxyapatite were implanted in the medial calf region together with the saphenous vascular bundle in syngeneic rats. Two weeks after implantation, the vascular pedicle with the implants was exposed and covered with silicone rubber to prevent vascular invasion through surrounding tissues (vascularized mesenchymal stem cell/hydroxyapatite implants). In addition, nonvascularized mesenchymal stem cell/hydroxyapatite implants were created with a ligated vascular pedicle. Implants of vascularized hydroxyapatite alone were prepared as a control. All implants were retrieved 4 weeks after surgery. RESULTS: Histologically, de novo bone formations were observed in the vascularized implants. This was in contrast with only necrotic tissue observed in the nonvascularized implants. Bone formation was not observed entirely in the vascularized hydroxyapatite-alone implants. For biochemical analysis, alkaline phosphatase activity and osteocalcin content of the vascularized mesenchymal stem cell/hydroxyapatite implants were significantly higher than those of the nonvascularized mesenchymal stem cell/hydroxyapatite and vascularized hydroxyapatite-alone implants. CONCLUSION: The results of this study indicated that the vascularized tissue-engineered bone grafts could be transferred as free vascularized grafts to lesions that lack adequate blood supply.

Alkaline Phosphatase↗
PubMed1981

Photosynthetic Characteristics of Portulaca grandiflora, a Succulent C(4) Dicot : CELLULAR COMPARTMENTATION OF ENZYMES AND ACID METABOLISM.

The succulent, cylindrical leaves of the C(4) dicot Portulaca grandiflora possess three distinct green cell types: bundle sheath cells (BSC) in radial arrangement around the vascular bundles; mesophyll cells (MC) in an outer layer adjacent to the BSC; and water storage cells (WSC) in the leaf center. Unlike typical Kranz leaf anatomy, the MC do not surround the bundle sheath tissue but occur only in the area between the bundle sheath and the epidermis. Intercellular localization of photosynthetic enzymes was characterized using protoplasts isolated enzymatically from all three green cell types.Like other C(4) plants, P. grandiflora has ribulose 1,5-bisphosphate carboxylase and the decarboxylating enzyme, NADP(+)-malic enzyme, in the BSC. Unlike other C(4) plants, however, phosphoenolpyruvate carboxylase, pyruvate, Pi dikinase, and NADP(+)-malate dehydrogenase of the C(4) pathway were present in all three green cell types, indicating that all are capable of fixing CO(2) via phosphoenolpyruvate carboxylase and regenerating phosphoenolpyruvate. Other enzymes were about equally distributed between MC and BSC similar to other C(4) plants. The enzyme profile of the WSC was similar to that of the MC but with reduced activity in most enzymes, except mitochondrion-associated enzymes.Intracellular localization of enzymes was studied in organelles partitioned by differential centrifugation using mechanically ruptured mesophyll and bundle sheath protoplasts. Phosphoenolpyruvate carboxylase was a cytosolic enzyme in both cells; whereas, ribulose 1,5-bisphosphate carboxylase and NADP(+)-malic enzyme were exclusively compartmentalized in the bundle sheath chloroplasts. NADP(+)-malate dehydrogenase, pyruvate, Pi dikinase, aspartate aminotransferase, 3-phosphoglycerate kinase, and NADP(+)-triose-P dehydrogenase were predominantly localized in the chloroplasts while alanine aminotransferase and NAD(+)-malate dehydrogenase were mainly present in the cytosol of both cell types. Based on enzyme localization, a scheme of C(4) photosynthesis in P. grandiflora is proposed.Well-watered plants of P. grandiflora exhibit a diurnal fluctuation of total titratable acidity, with an amplitude of 61 and 54 microequivalent per gram fresh weight for the leaves and stems, respectively. These changes were in parallel with changes in malic acid concentration in these tissues. Under severe drought conditions, diurnal changes in both titratable acidity and malic acid concentration in both leaves and stems were much reduced. However, another C(4) dicot Amaranthus graecizans (nonsucculent) did not show any diurnal acid fluctuation under the same conditions. These results confirm the suggestion made by Koch and Kennedy (Plant Physiol. 65: 193-197, 1980) that succulent C(4) dicots can exhibit an acid metabolism similar to Crassulacean acid metabolism plants in certain environments.

Journal Article↗
PubMed1999

An auxin-dependent distal organizer of pattern and polarity in the Arabidopsis root.

Root formation in plants involves the continuous interpretation of positional cues. Physiological studies have linked root formation to auxins. An auxin response element displays a maximum in the Arabidopsis root and we investigate its developmental significance. Auxin response mutants reduce the maximum or its perception, and interfere with distal root patterning. Polar auxin transport mutants affect its localization and distal pattern. Polar auxin transport inhibitors cause dramatic relocalization of the maximum, and associated changes in pattern and polarity. Auxin application and laser ablations correlate root pattern with a maximum adjacent to the vascular bundle. Our data indicate that an auxin maximum at a vascular boundary establishes a distal organizer in the root.

Arabidopsis↗
PubMedDate not supplied

[Comparative angioarchitectonics of the kidneys of several rodents].

Studies have been made on kidney angioarchitectonics in 3 rodent species (allied taxonomically, but significantly different in their habitat) - the albino rat, the gerbil Meriones erythrourus and the aquatic rodent must-rat Ondatra zibetica - after the injection of the vessels with India ink and subsequent microphotometric analysis of unstained sections. The general pattern of vascular system of the kideny is similar in all the species studied. However, significant differences were found in vascularisation of the cortex and especially of the outer and inner medulla. In M. erythrourus, vascularisation of the papilla is approximately 2 1/2 times more intense than that of the cortex; large vascular bundles in the outer medulla are separated from both interbundle plexus and vascular system of the papilla; the glomeruli differ in their size; arterial sphincters are more numerous in the cortex. In O. zibetica, vascularisation of the papilla is somewhat 3 times less intense as compared to that of the cortex; medullar bundles are diffuse; the structure of the glomeruli is more uniform. With respect to its kidney angioarchitectonics, the albino rat occupies intermediate position. The observed differences are discussed in relation to ecological specialization of the species studied, indicating the important role of vascular system of the kidney in the formation of concentrating capacity of the latter.

Animals↗
PubMed1995

Isolation, chemical structures and biological activity of the lipo-chitin oligosaccharide nodulation signals from Rhizobium etli.

Rhizobium etli is a microsymbiont of plants of the genus Phaseolus. Using mass spectrometry we have identified the lipo-chitin oligosaccharides (LCOs) that are produced by R. etli strain CE3. They are N-acetylglucosamine pentasaccharides of which the non-reducing residue is N-methylated and N-acylated with cis-vaccenic acid (C18:1) or stearic acid (C18:0) and carries a carbamoyl group at C4. The reducing residue is substituted at the C6 position with O-acetylfucose. Analysis of their biological activity on the host plant Phaseolus vulgaris shows that these LCOs can elicit the formation of nodule primordia which develop to the stage where vascular bundles are formed. The formation of complete nodule structures, including an organized vascular tissue, is never observed. Considering the very close resemblance of the R. etli LCO structures to those of R. loti (I. M. López-Lara, J. D. J. van den Berg, J. E. Thomas Oates, J. Glushka, B. J. J. Lugtenberg, H. P. Spaink, Mol Microbiol 15: 627-638, 1995) we tested the ability of R. etli strains to nodulate various Lotus species and of R. loti to nodulate P. vulgaris. The results show that R. etli is indeed able to nodulate Lotus plants. However, several Lotus species are only nodulated when an additional flavonoid independent transcription activator (FITA) nodD gene is provided. Phaseolus plants can also be nodulated by R. loti bacteria, but only when the bacteria contain a FITA nodD gene. Apparently, the type of nod gene inducers secreted by the plants is the major basis for the separation of Phaseolus and Lotus into different cross inoculation groups.

Acetylglucosamine↗
PubMed2003

[Microvascular denudation of the femoral artery of the mouse as a model for restenosis].

OBJECTIVE: To present technique and results of a microvascular denudation of the common femoral artery of the mouse as a model for inducing intimal hyperplasia in interventional radiology. MATERIALS AND METHODS: Under general anesthesia introduced by intraperitoneal injection, 14 B6129F1 hybrid mice (7 females and 7 males) at a mean age of 12.1 +/- 1.8 weeks and a mean weight of 28 +/- 2.8 grams had a groin incision of the vascular bundle directly distal to the inguinal ligament in preparation of placing a vascular clamp. Thereafter, the femoral artery was dissected distal to the origin of the epigastric artery and a loop prepared for a ligation proximal to the planned arteriotomy. Through an arteriotomy performed free-hand with a pair of micro scissors, a 0.010" (= 0.25 mm) guidewire was introduced into the vessel and advanced to the aortic bifurcation. The guide-wire was moved back and forth three times. The same procedure was performed on the other side as sham-operation, i.e., without introduction and passage of a guidewire. The resulting changes of the vessel wall were evaluated by histology and morphometry. RESULTS: Four weeks after intervention, the mean intima-to-media-ratio (IMR) was 1.80 +/- 0.28. A significant difference was observed between the sexes, with an IMR of 1.41 +/- 0.29 in females and an IMR of 2.24 +/- 0.45 in males (p = 0.0173). The neointima led to an overall luminal loss of 50.2% +/- 8.3% without significant sex difference (p = 0.09), but the average luminal loss was still more severe in females, amounting to 43.9% in comparison to 56.1% in males. This technique induces a significant neointima formation in a reproducible manner. The internal elastic membrane was preserved in all vessels. CONCLUSION: This technique is an excellent model to examine the differences between genetically modified mice to clarify the role of putative key molecules in the pathophysiology of restenosis.

Angioplasty, Balloon↗
PubMed2003

Increased resistance to pod shatter is associated with changes in the vascular structure in pods of a resynthesized Brassica napus line.

The architecture of the pod wall and dehiscence zone (DZ) was studied in populations of a resynthesized, shatter-resistant, oilseed rape line, DK142, and the commercial cultivar Apex. The dimensions of the pod wall and its component tissues were significantly larger in DK142. However, the variation in the pod architecture of Apex, DK142 and F2 populations derived from crosses of DK142 and Apex was found to have little or no role in pod shatter. By contrast, variation in the dimensions of the DZ characters correlated strongly and positively with shatter resistance. The size of the main vascular bundle (MVBV) of DK142 as it exited the valve and joined the vascular tissue of the replum was, on average, 60% larger than in Apex, the DZ was 40% wider and there was a high preponderance of vascular tissue other than the MVBV. The variation in the size of the MVBV accounted for much of the variation in shatter resistance of all populations, including shatter-susceptible Apex. The DZ width was also found to be important in explaining the limited range of shatter values in Apex, but in populations of DK142 and F2, where the amount of vascular intrusion into the DZ was much greater, the variation in DZ width was not important. The importance of the vascular tissue to shatter resistance was further highlighted by a novel microfracture test (MFT). By contrast, no significant difference between DK142 and Apex in the ease of separation of the thin-walled DZ cells was detected using the MFT.

Brassica napus↗
PubMed2005

hca: an Arabidopsis mutant exhibiting unusual cambial activity and altered vascular patterning.

By screening a T-DNA population of Arabidopsis mutants for alterations in inflorescence stem vasculature, we have isolated a mutant with a dramatic increase in vascular tissue development, characterized by a continuous ring of xylem/phloem. This phenotype is the consequence of premature and numerous cambial cell divisions in both the fascicular and interfascicular regions that result in the loss of the alternate vascular bundle/fiber organization typically observed in Arabidopsis stems. The mutant was therefore designated high cambial activity (hca). The hca mutation also resulted in pleiotropic effects including stunting and a delay in developmental events such as flowering and senescence. The physiological characterization of hca seedlings in vitro revealed an altered auxin and cytokinin response and, most strikingly, an enhanced sensitivity to cytokinin. These results were substantiated by comparative microarray analysis between hca and wild-type plants. The genetic analysis of hca indicated that the mutant phenotype was not tagged by the T-DNA and that the hca mutation segregated as a single recessive locus, mapping to the long arm of chromosome 4. We propose that hca is involved in mechanisms controlling the arrangement of vascular bundles throughout the plant by regulating the auxin-cytokinin sensitivity of vascular cambial cells. Thus, the hca mutant is a useful model for examining the genetic and hormonal control of cambial growth and differentiation.

Arabidopsis↗
PubMed2002

Cell death processes during expression of hybrid lethality in interspecific F1 hybrid between Nicotiana gossei Domin and Nicotiana tabacum.

Hybrid lethality, a type of reproductive isolation, is a genetically controlled event appearing at the seedling stage in interspecific hybrids. We characterized the lethality of F(1) hybrid seedlings from Nicotiana gossei Domin and Nicotiana tabacum cv Bright-Yellow 4 using a number of traits including growth rate, microscopic features of tissues and cells, ion leakage, DNA degradation, reactive oxygen intermediates including superoxide radical (O(2)(-)) and hydrogen peroxide (H(2)O(2)), and expression of stress response marker genes. Lethal symptoms appeared at 4 d after germination in the basal hypocotyl and extended toward both the hypocotyl and root of the plants grown at 26 degrees C. Microscopic analysis revealed a prompt lysis of cell components during cell death. Membrane disruption and DNA degradation were found in the advanced stage of the lethality. The death of mesophyll cells in the cotyledon was initiated by the vascular bundle, suggesting that a putative factor inducing cell death diffused into surrounding cells from the vascular tissue. In contrast, these symptoms were not observed in the plants grown at 37 degrees C. Seedlings grown at 26 degrees C generated larger amounts of reactive oxygen intermediate in the hypocotyl than those grown at 37 degrees C. A number of stress response marker genes were expressed at 26 degrees C but not at 37 degrees C. We proposed that a putative death factor moving systemically through the vascular system induced a prompt and successive lysis of the cytoplasm of cells and that massive cell death eventually led to the loss of the hybrid plant.

Apoptosis↗
PubMed1973

Floral stimulus movement in perilla and flower inhibition caused by noninduced leaves.

Photoperiodic control of flowering in the short day plant Perilla involves the transmission of a floral stimulus from induced leaves to the shoot apex. We have studied the basipetal movement of this stimulus and of (14)C-labeled assimilates in plants with an induced leaf (donor) grafted into the uppermost internode of a vegetative plant in which the axillary shoots at various nodes along the stem function as receptors.In agreement with earlier autoradiographic studies by Chailakhyan and Butenko (Transl. Fiziol. Rast. 1957, 4:426-438), a quantitative relationship was found between flower formation and the transport of labeled assimilates from the donor leaf into receptor shoots. The presence of noninduced leaves (i.e., leaves maintained on long day) on the receptor plant prevents flowering and assimilate import by shoots in the axils of the long day leaves and by shoots at nodes in the same orthostichy lower down on the stem. All these vegetative shoots import assimilates from the long day leaves.Both the floral stimulus and the inhibitory effects of long day leaves are translocated basipetally over long distances and in specific parts of the vascular system which correspond to specific orthostichies of the stem. Movement in the xylem of the stain safranin indicates that assimilates from the long day leaves and from the donor can be transported in distinct regions of the vascular bundles in the stem. The pattern of assimilate distribution evidently depends on the pattern of vascular anatomy and on the relative contribution by the various sources of assimilates.A light intensity close to that saturating for photosynthesis saturates long day inhibition of flowering. Moreover, under the appropriate experimental conditions, inhibition is not only caused by leaves in long day, but also by those in short day or darkness.Apparently the floral stimulus moves in parallel with the assimilates in the phloem of Perilla, so that the pattern of assimilate distribution from different leaves determines the pattern of movement of the floral stimulus. It is, therefore, concluded that long day inhibition of flowering in Perilla is the result of competition between assimilate streams originating in the donor and long day leaves. A specific transmissible inhibitor is most likely not involved in the control of flowering in Perilla.

Journal Article↗
PubMed2000

The arterial communication between the gastrocnemius muscle heads: a fresh cadaveric study and clinical implications.

The purpose of this investigation was to describe the anatomy of the communicating (anastomotic) vessels between the gastrocnemius muscle heads and to record the extent of their supply potential. Ensuing clinical implications are discussed. Fourteen fresh cadaveric gastrocnemius muscles were examined. Detailed dissections of the communicating vessels were facilitated after injections of methylene blue or cadaveric blood solutions through the medial, lateral, or both sural arteries. The extent of the arterial cross-supply between the muscles' heads through these vessels was determined in-eight specimens after methylene blue perfusions through the lateral sural arteries, while one specimen was examined after injection of methylene blue and yellow ink through the lateral and medial sural arteries, respectively. Communicating vessels were detected in all 14 specimens. A mean number of 5.8 vascular bundles and single vessels was found. The bundles consisted of arterioles and, as all indications suggested, of concomitant venules as well. Regarding arterial cross-supply, it was clearly evident that each head could be vascularized solely from the contralateral one, mostly through these bundles. However, even if only a part of the bundles was preserved intact, vasculature was not affected.

Adult↗
PubMed1984

Experimental study of tissue graft vascularization by means of vascular implantation and subcutaneous burying.

A new method to salvage severed composite-tissue segments (denuded hindleg) by vascular implantation associated with subcutaneous burying was successfully undertaken in rabbits. The implantation of vascular bundle can preserve more viability of the fresh segment than burying alone and serves as the vascular pedicle for later transplantation. A devitalized segment can also be vascularized by this method, although no survival or regeneration of preexisting tissues could be found.

Amputation, Traumatic↗
PubMed2002

The white clover enod40 gene family. Expression patterns of two types of genes indicate a role in vascular function.

Enod40 is one of the genes associated with legume nodule development and has a putative role in general plant organogenesis. We have isolated a small enod40 gene family from white clover (Trifolium repens), with three genes designated Trenod40-1, Trenod40-2, and Trenod40-3, all containing the conserved enod40 regions I and II. Trenod40-1 and Trenod40-2 share over 90% homology in the transcribed regions and high levels of similarity in their upstream regulatory sequences. Trenod40-1 and Trenod40-2 are similar to the enod40 genes of legumes forming indeterminate nodules (group II) and are predominantly expressed in nodules. Trenod40-3 shares only 32.8% identity with Trenod40-1 and Trenod40-2 within the transcribed region. Trenod40-3 is similar to the enod40 genes of legumes with determinate nodules (group I) and is not predominantly expressed in nodules. To our knowledge, this is the first report of both group I- and group II-type enod40 genes being expressed in a single legume species. In situ hybridization studies revealed that Trenod40 genes were highly expressed in non-symbiotic tissues, particularly in stolon nodes during nodal root and lateral shoot development. High levels of Trenod40 transcripts were also present in the vascular bundles of mature plant organs, mainly at sites of intensive lateral transport, suggesting a role in vascular tissue function. The expression pattern of Trenod40 genes was analyzed further using Trenod40 promoter-gus fusions in transgenic white clover and tobacco (Nicotiana tabacum), indicating that white clover and tobacco share the regulatory mechanisms for Trenod40-1/2 promoters and some aspects of Trenod40-3 regulation.

Base Sequence↗