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PubMed1998

Intrarenal blood flow: microvascular anatomy and the regulation of medullary perfusion.

1. The microcirculation of the kidney is arranged in a manner that facilitates separation of blood flow to the cortex, outer medulla and inner medulla. 2. Resistance vessels in the renal vascular circuit include arcuate and interlobular arteries, glomerular afferent and efferent arterioles and descending vasa recta. 3. Vasoactive hormones that regulate smooth muscle cells of the renal circulation can originate outside the kidney (e.g. vasopressin), can be generated from nearby regions within the kidney (e.g. kinins, endothelins, adenosine) or they can be synthesized by adjacent endothelial cells (e.g. nitric oxide, prostacyclin, endothelins). 4. Vasoactive hormones released into the renal inner medullary microcirculation may be trapped by countercurrent exchange to act upon descending vasa recta within outer medullary vascular bundles. 5. Countercurrent blood flow within the renal medulla creates a hypoxic environment. Relative control of inner versus outer medullary blood flow may play a role to abrogate the hypoxia that arises from O2 consumption by the thick ascending limb of Henle. 6. Cortical blood flow is autoregulated. In contrast, the extent of autoregulation of medullary blood flow appears to be influenced by the volume status of the animal. Lack of medullary autoregulation during volume expansion may be part of fundamental processes that regulate salt and water excretion.

Animals↗

PubMed1993

Selective zonal change of the renomedullary interstitial cells in hypokalemic rats.

Electron microscopic morphometry was undertaken to quantitate the morphological change of the renomedullary interstitial cells (RIC) of hypokalemic rats by using large montages. Two weeks of potassium depletion resulted in an increase of the RIC, which were restricted to the interbundle region of the inner stripe of the outer medulla. The increase of the RIC is characterized by a preferential increase in volume density (+340.0%; P < 0.01) and numerical density (+61.4%; P < 0.01) in the interbundle region but not in the vascular bundle of the inner stripe or in the inner medulla. The increased RIC in the interbundle region of the inner stripe demonstrated an increase of lipid droplets, which are known to contain prostaglandin precursors. The selective zonal change of RIC with increased lipid droplets is a characteristic lesion of hypokalemic rats and suggests an enhanced vasoactive function of RIC associated with hypokalemic nephropathy.

Animals↗

PubMedDate not supplied

KNOX homeobox genes potentially have similar function in both diploid unicellular and multicellular meristems, but not in haploid meristems.

Members of the class 1 knotted-like homeobox (KNOX) gene family are important regulators of shoot apical meristem development in angiosperms. To determine whether they function similarly in seedless plants, three KNOX genes (two class 1 genes and one class 2 gene) from the fern Ceratopteris richardii were characterized. Expression of both class 1 genes was detected in the shoot apical cell, leaf primordia, marginal part of the leaves, and vascular bundles by in situ hybridization, a pattern that closely resembles that of class 1 KNOX genes in angiosperms with compound leaves. The fern class 2 gene was expressed in all sporophyte tissues examined, which is characteristic of class 2 gene expression in angiosperms. All three CRKNOX genes were not detected in gametophyte tissues by RNA gel blot analysis. Arabidopsis plants overexpressing the fern class 1 genes resembled plants that overexpress seed plant class 1 KNOX genes in leaf morphology. Ectopic expression of the class 2 gene in Arabidopsis did not result in any unusual phenotypes. Taken together with phylogenetic analysis, our results suggest that (a) the class 1 and 2 KNOX genes diverged prior to the divergence of fern and seed plant lineages, (b) the class 1 KNOX genes function similarly in seed plant and fern sporophyte meristem development despite their differences in structure, (c) KNOX gene expression is not required for the development of the fern gametophyte, and (d) the sporophyte and gametophyte meristems of ferns are not regulated by the same developmental mechanisms at the molecular level.

Arabidopsis↗

PubMed2006

Study of the antifungal ability of Bacillus subtilis strain PY-1 in vitro and identification of its antifungal substance (iturin A).

A Bacillus strain, denoted as PY-1, was isolated from the vascular bundle of cotton. Biochemical, physiological and 16S rDNA sequence analysis proved that it should belong to Bacillus subtilis. The PY-1 strain showed strong ability against many common plant fungal pathogens in vitro. The antibiotics produced by this strain were stable in neutral and basic conditions, and not sensitive to high temperature. From the culture broth of PY-1 strain, five antifungal compounds were isolated by acidic precipitation, methanol extraction, gel filtration and reverse-phase HPLC. Advanced identification was performed by mass spectrometry and nuclear magnetic resonance spectroscopy. These five antifungal compounds were proved to be the isomers of iturin A: A2, A3, A4, A6 and A7. In fast atom bombardment mass spectrometry/mass spectrometry collision-induced dissociation spectra, fragmentation ions from two prior linear acylium ions were observed, and the prior ion, Tyr-Asn-Gln-Pro-Asn-Ser-betaAA-Asn-CO+, was first reported.

Antifungal Agents↗

PubMed1977

The traumatic bone cyst.

A case is reported of traumatic cyst lying in the molar region of the mandible. It extended to the inferior border of the mandible and extended the buccal alveolar bone. The cystic cavity contained the inferior neuro-vascular bundle yellow serous fluid, and a small amount of gas. The wall of the cavity was lined with loosely arranged connective tissue with numerous capillaries. Healing was uneventful and clinical and radiographic examinations revealed restoration of bone structure and normal contours.

Adolescent↗

PubMed2026

The CsTBH-CsROP2 Module Regulates Waterlogging Tolerance via Auxin-Mediated Adventitious Root Formation in Cucumber.

Cucumber (Cucumis sativus L.) requires frequent irrigation due to its shallow root system and high transpiration rate of the aboveground parts. However, it is also prone to waterlogging damage. Therefore, understanding its response to waterlogging is crucial for breeding waterlogging-tolerant varieties. Although Rho of Plants GTPases play well-established roles in regulating development and stress signalling, their functions in plant adaptation to waterlogging stress has yet to be fully elucidated. Here, we identified nine CsROP genes in the cucumber genome, which exhibit evolutionary diversification but retain conserved functional domains. Functional analysis revealed that CsROP2 acts as a negative regulator of adventitious root formation. It modulates auxin accumulation in hypocotyl vascular bundles, thereby suppressing adventitious root development and enhancing waterlogging sensitivity. The HD-Zip I transcription factor CsTBH directly binds the CsROP2 promoter and activates its expression. Our study uncovers a CsTBH-CsROP2 module that governs adventitious rooting and waterlogging tolerance by modulating auxin homeostasis. These findings provide new insights into the crosstalk between developmental programmes and stress signalling pathways and offer potential genetic targets for improving stress resilience in cucumber and other crops.

CsROP2↗

PubMed2025

Multi-Omics insights into OsZFP252-OsGA20ox5 mediated drought tolerance in rice through stomatal and vascular regulation.

Rice growth is highly dependent on water availability, and drought stress significantly impacts its entire life cycle. However, previous studies lack systematic investigations into drought-responsive candidate genes across the full life cycle of rice. This study integrates transcriptomic and phenotypic data from two rice lines, IR64 (drought-sensitive) and DK151 (drought-tolerant), under varied environmental conditions at distinct growth stages. Using k-means clustering, 13 369 genes were categorized into 17 distinct expression patterns, revealing drought-responsive genes specifically upregulated or downregulated under drought stress. Weighted co-expression network analysis (WGCNA) further identified four gene modules strongly correlated with drought-related phenotypes, co-localizing 2859 drought-responsive genes through both approaches. Proteomics and metabolomics were supplemented at the booting stage, where phenotypic and transcriptomic differences under drought were most pronounced. Integrated omics results demonstrate gibberellin (GA) and abscisic acid (ABA) pathways play a key role during drought tolerance in rice, and 79 high-confidence drought-resistant candidate genes were prioritized from the 2859 drought-responsive genes. Among these, Gibberellin 20-oxidase 5 (OsGA20ox5) was identified as a key negative regulator of drought tolerance. Furthermore, the transcription factor zinc finger protein 252 (OsZFP252) directly binds to the OsGA20ox5 promoter, repressing its expression and enhancing ABA biosynthesis, thereby improving drought tolerance by increasing stomatal closure and expanding vascular bundle water transport capacity. Notably, the drought-tolerant haplotype 2-4 (Hap2-4) of OsGA20ox5 provides valuable insights for drought-resistant breeding.

Oryza↗

PubMed1980

Progression of epiphytic microflora in wheat and alfalfa silages as observed by scanning electron microscopy.

Wheat and alfalfa silages were examined by scanning electron microscopy and standard methods of microbial enumeration. Epiphytic microflora were present at levels of 10 to 10/g in the fresh-cut plants. This flora was initially observed microscopically primarily on the surfaces. After 4 days of fermentation, lactic acid bacteria were observed on the surface in high concentrations near open stomata and throughout the interior mesophyll air sac spaces. At 4 days, populations on interior surfaces were restricted to the exterior surfaces of the air sacs. After 8 days the mesophyllic cells showed marked deterioration, and bacteria were observed on their inner surfaces. At 32 days, the end of the fermentation, vascular bundles and epidermal cells remained intact whereas stomata and mesophyllic cells were collapsed and often contained microorganisms. It is concluded that the interior of the leaves offers substantial nutritional and environmental advantages to epiphytic flora and is an important if not major deterioration site in fermented products. Since little deterioration of exterior surfaces was observed, these sites may play a minor role in supplying nutrients for microbial growth.

Journal Article↗

PubMed2000

Colonization of corn, Zea mays, by the entomopathogenic fungus Beauveria bassiana.

Light and electron microscopy were used to describe the mode of penetration by the entomopathogenic fungus Beauveria bassiana (Balsamo) Vuillemin into corn, Zea mays L. After inoculation with a foliar spray of conidia, germinating hyphae grew randomly across the leaf surface. Often a germ tube formed from a conidium and elongated only a short distance before terminating its growth. Not all developing hyphae on the leaf surface penetrated the cuticle. However, when penetration did occur, the penetration site(s) was randomly located, indicating that B. bassiana does not require specific topographic signals at an appropriate entry site as do some phytopathogenic fungi. Long hyphal structures were observed to follow the leaf apoplast in any direction from the point of penetration. A few hyphae were observed within xylem elements. Because vascular bundles are interconnected throughout the corn plant, this may explain how B. bassiana travels within the plant and ultimately provides overall insecticidal protection. Virulency bioassays demonstrate that B. bassiana does not lose virulence toward the European corn borer, Ostrinia nubilalis (Hübner), once it colonizes corn. This endophytic relationship between an entomopathogenic fungus and a plant suggests possibilities for biological control, including the use of indigenous fungal inocula as insecticides.

Animals↗

PubMed1987

Nitrogen-fixing nodules induced by Agrobacterium tumefaciens harboring Rhizobium phaseoli plasmids.

Rhizobium phaseoli CFN299 forms nitrogen-fixing nodules in Phaseolus vulgaris (bean) and in Leucaena esculenta. It has three plasmids of 185, 225, and 410 kilobases. The 410-kilobase plasmid contains the nitrogenase structural genes. We have transferred these plasmids to the plasmid-free strain Agrobacterium tumefaciens GMI9023. Transconjugants containing different combinations of the R. phaseoli plasmids were obtained, and they were exhaustively purified before nodulation was assayed. Only transconjugants harboring the 410-kilobase plasmid nodulate P. vulgaris and L. esculenta. Nodules formed by all such transconjugants are able to reduce acetylene. Transconjugants containing the whole set of plasmids from CFN299 nodulate better and fix more nitrogen than the transconjugants carrying only the Sym plasmid. Microscopic analysis of nodules induced by A. tumefaciens transconjugants reveals infected cells and vascular bundles. None of the A. tumefaciens transconjugants, not even the one with the whole set of plasmids from CFN299, behaves in symbiosis like the original R. phaseoli strain; the transconjugants produce fewer nodules and have lower acetylene reduction (25% as compared to the original R. phaseoli strain) and more amyloplasts per nodule. More than 2,000 bacterial isolates from nodules of P. vulgaris and L. esculenta formed by the transconjugants were analyzed by different criteria. Not a single rhizobium could be detected. Our results show that R. phaseoli plasmids may be expressed in the A. tumefaciens background and direct the formation of effective, differentiated nodules.

Conjugation, Genetic↗

PubMed1988

Scanning electron microscope studies of Agrobacterium tumefaciens attachment to Zea mays, Gladiolus sp., and Triticum aestivum.

Scanning electron microscope studies demonstrated that cells of Agrobacterium tumefaciens strains attach to cells on the cut surfaces of corn and wheat seedlings and to gladiolus disks. Bacterial cells attached to these monocots in the same manner as they attached to the dicots tested. Of the strains tested, A66 and T37 covered more of the cut surfaces of these monocots in a nonrandom fashion than did cells of other isolates. These bacteria attached to cells of intact monocotyledonous plants and had the greatest affinity for tissues located within the vascular bundles. They attached in large numbers to cells in these areas in all three monocots tested.

Bacterial Adhesion↗

PubMed2003

In situ characterization of Cymbidium Ringspot Tombusvirus infection-induced posttranscriptional gene silencing in Nicotiana benthamiana.

In plants, posttranscriptional gene silencing (PTGS) is an ancient and effective defense mechanism against viral infection. A number of viruses encode proteins that suppress virus-activated PTGS. The p19 protein of tombusviruses is a potent PTGS suppressor which interferes with the onset of PTGS-generated systemic signaling and is not required for viral replication or for viral movement in Nicotiana benthamiana. This unique feature of p19 suppressor allowed us to analyze the mechanism of PTGS-based host defense and its viral suppression without interfering with other viral functions. In contrast to the necrotic symptoms caused by wild-type tombusvirus, the infection of p19-defective mutant virus results in the development of a typical PTGS-associated recovery phenotype in N. benthamiana. In this report we show the effect of PTGS on the viral infection process for N. benthamiana infected with either wild-type Cymbidium Ringspot Tombusvirus (CymRSV) or a p19-defective mutant (Cym19stop). In situ analyses of different virus-derived products revealed that PTGS is not able to reduce accumulation of virus in primary infected cells regardless of the presence of p19 PTGS suppressor. We also showed that both CymRSV and Cym19stop viruses move systemically in the vasculature, with similar efficiencies. However, in contrast to the uniform accumulation of CymRSV throughout systemically infected leaves, the presence of Cym19stop virus was confined to and around the vascular bundles. These results suggest that the role of p19 is to prevent the onset of mobile signal-induced systemic PTGS ahead of the viral infection front, leading to generalized infection.

Gene Expression Regulation↗

PubMed1979

Structure of nitrogen-fixing nodules formed by Rhizobium on roots of Parasponia andersonii Planch.

The structure of nitrogen-fixing nodules produced by Rhizobium infection of the non-legume Parasponia andersonii was examined by light and electron (both SEM and TEM) microscopy. Comparisons were made with the nodules previously described on P. rugosa. Like the nodules on different non-legumes formed by other types of endophytes, the Rhizobium nodules on Parasponia resembled modified roots by having a central vascular bundle surrounded by an endophyte-infected zone. The intimate association between the Rhizobium and the host nodule cell was compared with the Rhizobium association found in legumes. The rhizobia were not released from the infection thread as happens in the legume. The infection thread, which propagates the Rhizobium infection to new cells, was transformed within a nodule cell from a darkly stained (light microscopy) or very electron-dense (TEM) structure to a number of thread types. The walls of the threads varied greatly in thickness and often the thread structures were without rigid walls and were only enclosed by a plasma membrane. If the rhizobia are transformed into bacteroids, as in the legumes, it would have to occur when the threads had reached their mature size, when bacterial division had ceased. Nitrogen fixation was considered to occur in all thread types.

Nitrogen Fixation↗

PubMed1986

Renal medullary blood flow: its measurement and physiology.

The vasculature of the mammalian renal medulla is complex, having neither discrete input nor output. There is also efficient countercurrent exchange between ascending and descending vasa recta in the vascular bundles. These considerations have hampered measurement of medullary blood flow since they impose pronounced constraints on methods used to assess flow. Three main strategies have been used: (i) indicator extraction; (ii) erythrocyte velocity tracking; and (iii) indicator dilution. These are discussed with respect to their assumptions, requirements, and limitations. There is a consensus that medullary blood flow is autoregulated, albeit over a narrower pressure range than is total renal blood flow. When normalized to gram tissue weight, medullary blood flow in the dog is similar to that in the rat, on the order of 1 to 1.5 mL X min-1 X g-1. This is considerably greater than estimated by the radioiodinated albumin uptake method which has severe conceptual and practical problems. From both theoretical and experimental evidence it seems that urinary concentrating ability is considerably less sensitive to changes in medullary blood flow than is often assumed.

Animals↗

PubMed1981

The extremity soft-tissue lesion: a comparative study of ultrasound, computed tomography, and xeroradiography.

Twenty-five extremity soft-tissue lesions were evaluated by ultrasound (US), computed tomography (CT), and xeroradiography (XR). The lesion was detected by CT in 20 of 25 cases. In five cases, a soft-tissue tumor was not identified by CT due to small lesion size, isodensity, or the inability to distinguish scar tissue from recurrent tumor. Of the three modalities, the vascular bundle was most reliably defined by CT. In 20 of 25 cases, the lesion was detected by XR, but the size was accurately determined in only 13 cases.

Adolescent↗

PubMed1995

Effect of norepinephrine and acetylcholine on outer medullary descending vasa recta.

To examine their responsiveness to norepinephrine (NE) and acetylcholine (ACh), outer medullary descending vasa recta (OMDVR) have been dissected from vascular bundles of the rat and perfused in vitro. Abluminal application of NE produced graded vasoconstriction in a concentration range of 10(-9)-10(-6) M. When applied with NE, ACh at concentrations of 10(-8)-10(-5) M dilated NE-preconstricted OMDVR. In contrast, ACh applied in the absence of NE caused vasoconstriction. ACh-induced vasodilation was blocked by addition of the nitric oxide synthase inhibitor N omega-nitro-L-arginine (L-NNA, 2 x 10(-4) M). L-NNA in the absence of ACh enhanced NE-induced vasoconstriction. Supraphysiological (10(-3) M) L-arginine (L-Arg) reversed the effects of L-NNA, and abluminal application of L-NNA alone resulted in OMDVR vasoconstriction. At concentrations of 10(-6)-10(-3) M, abluminal application of L-Arg produced graded vasodilation of NE-constricted OMDVR. These results suggest that adrenergic and cholinergic innervation could influence OMDVR vasomotor tone to modulate total and regional blood flow to the renal medulla. The data also favor a role for the activity of constitutively expressed nitric oxide synthase to modulate OMDVR vasoactivity.

Acetylcholine↗

PubMed1998

Response of isolated rat descending vasa recta to bradykinin.

Outer medullary descending vasa recta (OMDVR) were dissected from the outer medullary vascular bundles of young rats, perfused in vitro, and loaded with fura 2 for measurement of intracellular calcium concentration ([Ca2+]i) by fluorescent ratio imaging. Fluorescent video images revealed that fura 2 selectively loads into endothelial cells but not pericytes. Bradykinin (BK), at concentrations > 10(-11) M, elicited an increase in [Ca2+]i from baseline values in the range from 50 to 100 nM to peak values of 600-800 nM followed by a sustained plateau of 150-250 nM. The vasopressin V1-receptor agonist [Phe2,Ile3,Orn8]vasopressin constricted OMDVR but yielded no observable [Ca2+]i response, a finding that is consistent with an endothelial cell origin for the fura 2 fluorescent signal. The BK [Ca2+]i response was blocked by the selective BK B2-receptor antagonists D-Arg-[Hyp3,Thi5.8,D-Phe7]BK and D-Arg-[Hyp3,D-Phe7,Leu8]BK but not the B1 antagonist des-Arg9-[Leu8]BK. BK vasodilated microperfused OMDVR that had been preconstricted with 10(-8) M angiotensin II. We conclude that the [Ca2+]i response of OMDVR endothelia can be selectively studied with fura 2, that BK increases endothelial [Ca2+]i via the B2 receptor, and that BK can vasodilate descending vasa recta.

Angiotensin II↗

PubMed1985

Urinary concentrating ability: insights from comparative anatomy.

It appears difficult to build a coherent picture of the concentrating system of the mammalian renal medulla. This may be due to the diversity of the factors involved and to considerable interspecies differences. Several morphological adaptations that may be critical in the improvement of water conservation are described. They include variations in the length of the papilla, number of nephrons, percentage of long-looped nephrons, nephron heterogeneity, development of pelvic fornices, confluence of collecting ducts, vascular bundles in the inner stripe of the outer medulla, thin descending limb epithelium, and relative development of the three medullary zones. The organization of the medullary circulation is described; the medulla includes several functionally different compartments favoring preferential exchanges by the juxtaposition of certain tubules and vessels. This may improve the efficiency of certain recycling routes and hence the insulation of the different compartments. As discussed in section III, a better inner medullary insulation may be key, not (or not only) in achieving a high urine concentration but mainly in reducing the time required to reach this high concentration. This overview of the multiple interspecies variations in medullary organization underlines the importance, among other factors, of the inner stripe architecture and of the internephron differences in the process of urine concentration.

Amphibians↗