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PubMed2005

Influence of inorganic nitrogen and pH on the elongation of maize seminal roots.

BACKGROUND AND AIMS: Root absorption and assimilation of inorganic nitrogen usually alters rhizosphere pH, but the immediate influence of such pH changes on root elongation as well as that of exogenous inorganic nitrogen itself has been uncertain. METHODS: A differential extensiometer that monitored on a real-time, continuous basis root elongation in an intact 3-d-old maize plant was developed. Treatments included root media at pH 6.5 or 5.6 that lacked nitrogen and ones at pH 6.5 that contained 100 mmol m(-3) NH(4)(+) or NO(3)(-). KEY RESULTS: Acidifying the root medium from pH 6.5 to 5.6 nearly doubled the elasticity of the seminal root, but slightly decreased its elongation. Plasticity of the root apex was not detectable in all treatments. The presence of ammonium or nitrate in the medium stimulated elongation by 29 % or 14 %, respectively. Addition of an osmoticum to the medium had no effect on root elongation in the absence of inorganic nitrogen, but diminished the stimulation of elongation in the presence of ammonium and nitrate. This indicates that these ions or their by-products serve partially as osmolytes. CONCLUSIONS: In nutrient solution, root elongation of a maize seedling--even one with ample nitrogen reserves--depended most strongly on exogenous inorganic nitrogen, and less so, if at all, on either the pH of the bulk nutrient solution or the mechanical properties of cell walls.

Cell Wall↗
PubMed1996

Dorsal root ganglion neurons require functional neurotrophin receptors for survival during development.

Neurotrophins are the most profound known regulators of survival in the developing peripheral nervous system. Within dorsal root ganglia, the signalling receptors for the different members of the neurotrophin family are distributed in distinct patterns suggesting regulation of different functional classes of sensory neurons. Abnormalities observed in neurotrophin receptor mutant mice have confirmed this idea. Both trkA (-/-) and trkC (-/-) mice have striking neurological defecits referrable to subpopulations of DRG neurons which have distinct axon projections in the periphery. These results thus generalize concepts of dependence on target-derived factors based on extensive work with the prototypical neurotrophin, nerve growth factor. Further analysis of these animals also provides evidence for more complex developmental mechanisms including dependence on locally synthesized neurotrophins at early developmental stages and plasticity of neurotrophin receptor expression.

Animals↗
PubMed1994

On corruption.

This paper begins with the premise that in most individuals and in most cultures there is an inevitable force that presses toward the production of corruption as time passes, a force that requires vigilant resistance. Corruption is here defined as a falling away from the ego ideal of the individual or the ideals of the culture, which results in certain unfortunate and maladaptive changes in attitude and behavior of both the group and the individual. Support is given to the premise by a brief review of the work of Robert Hutchins and of Oswald Spengler, both of whom were eloquent and learned advocates of the premise, although, perhaps for personal reasons, they were too pessimistic. There follows a discussion of the metapsychology of corruption both in individuals and in cultures, both from an ego psychology point of view and from a self psychology point of view. Freud's paper on narcissism and Kohut's "psychology of the self in the narrow sense" are taken as starting points. Using the terms of the former, a divestment of the ego ideal of narcissistic libido is described, along the lines of, and somewhat parallel to, Freud's concept of secondary narcissism. Using Kohut's early concept of a separate line of development for narcissism, it is suggested that a similar separate line of development can exist for "corruption" in both individuals and cultures. At the root of this development are the repeated narcissistic wounds inevitable in the course of individual life and in the life of a culture as it tries to live up to its ideals. Resistance to the demoralizing effects of the vicissitudes of life is an important function of the ego, and depends on the strength of the ego, of the cohesiveness of the sense of self, and of a conscious awareness of the dangerous pressures toward corruption that pervade our civilization and resolve not to be swept up by these pressures. This leads to the main point of the paper, focus on the status of the ego ideal of the psychoanalyst or, conversely, his or her level of "corruption," whether conscious or unconscious. It is maintained that this level and the particular value system of the analyst, as well as the level of energy invested in living up to his or her value system, is communicated subtly to both one's students and patients, and has a vital role in the treatment process.(ABSTRACT TRUNCATED AT 250 WORDS)

Cultural Characteristics↗
PubMed1997

Development and clinical evaluation of a root coverage procedure using a collagen barrier membrane.

The use of guided tissue regeneration (GTR) procedures in the treatment of gingival recession has shown promising results and is gaining clinical acceptance. The purpose of this study was to assess the use of a bioabsorbable collagen membrane as a barrier device in root coverage treatment of gingival recession defects. The study consisted of 10 patients with 10 defects of either Miller Class I or II description and gingival recession > or =2.5 mm. Clinical measurements taken at baseline included plaque index (PI) and gingival index (GI), clinical attachment level (CAL) measured with an automated probe and reference stent, recession depth (RD; mean = 3.19 +/- 0.26 mm), recession width (RW; 3.95 +/- 0.41 mm), probing depth (PD; 2.3 +/- 0.2 mm), and width of keratinized tissue (KT; 2.4 +/- 0.3 mm); measurements were repeated at 1, 2, and 4 weeks and 3 and 6 months post-treatment. During the surgical procedure, a mucoperiosteal flap was elevated and the respective root thoroughly planed. The collagen membrane was cut to cover the defect and surrounding bone, positioned over the root, and secured with 5-0 gut interdental sutures. The flap was coronally positioned to cover the membrane and sutured with 5-0 silk. Data were analyzed using the Student paired t-test to compare pre- and postsurgery measurements. The nonparametric Wilcoxon matched pairs test was used to analyze the significance of PI and GI at different time intervals. A statistically significant (P < 0.01) reduction in RD (-1.66 +/- 0.25 mm) was observed at 6 months, representing 51.6% total attainable root coverage. Clinically, a statistically significant mean gain of 1.34 +/- 0.47 mm CAL and 0.90 +/- 0.32 mm KT was observed at 6 months. No statistical differences were found in PD and RW between baseline and 6 months postoperatively. PI and GI remained low and showed no statistically significant change (P < 0.05) throughout the study period. Results from this study suggest that a collagen membrane can be used successfully as a barrier device in GTR-based root coverage procedures.

Absorption↗
PubMed2004

Plant regeneration from epicotyl explant of Jatropha curcas.

In vitro epicotyl explants from Jatropha curcas were cultured on MS medium with indole-3-butyric acid (IBA) and 6-benzyladenine (BA). Adventitious buds were directly induced from the surface of epicotyl explants under the condition with the combinations of IBA 0.1 mg/L and BA 0.2-0.7 mg/L. Of which IBA 0.1 mg/L and BA 0.5 mg/L induced the highest regeneration frequency. Shoot regeneration from callus required the combinations of IBA 0.5 mg/L with BA 0.1 mg/L, IBA 0.5 mg/L with BA 0.2 mg/L and IBA 1.0 mg/L with BA 0.5 mg/L, and the most suitable combination was IBA 1.0 mg/L and BA 0.5 mg/L. The health adventitious buds and regenerated shoots could be rooted on growth regulator-free MS medium. Regenerated plants with well developed shoots and roots were successfully transferred to greenhouse, without visible detectable variation.

Adenine↗
PubMed2026

Expression of cotton GhMYB109 complements non-hair cell fate in the root epidermis of the Arabidopsis thaliana werewolf mutant.

Root cell fate and patterning in plants are orchestrated by the expression of cell-type-specific genes, including WEREWOLF (WER). Phylogenetic analysis of WER, functional WER homologs in Type III species (Rhodiola rosea and Boehmeria nivea), and related R2R3 MYB proteins identified in the cotton genome revealed that GhMYB109-a known regulator of fiber development in cotton ovules-clustered in a clade with Arabidopsis thaliana WER. To determine whether GhMYB109 is a functional homolog of WER, we expressed GhMYB109 under the control of the CaMV 35S promoter in the Arabidopsis thaliana wer-1 mutant and analyzed root epidermal cell patterning by counting root hairs. GhMYB109 expression significantly decreased the percentage of root hairs at both H and N positions. We found that most epidermal cells in the cotton root develop into root hairs (Type I pattern) although the cotton genome contains a functional WER homolog, GhMYB109. Additionally, GhMYB109 has been reported not to be expressed in cotton roots. These support the idea that GhMYB109 is a functional homolog of WER and that Arabidopsis thaliana and cotton diverged in root epidermal morphology through modifications in cis-regulatory elements rather than a functional divergence of their WER-like R2R3 MYB transcription factors.

Arabidopsis thaliana↗
PubMed2006

Surgical repositioning of a developing maxillary permanent central incisor in a horizontal position: spontaneous eruption and root formation.

This report describes the surgical repositioning of a developing maxillary permanent central incisor in a horizontal position, followed by spontaneous eruption and root formation without orthodontic traction. Surgical exposure of the right central incisor was achieved. A 7-year-old boy referred for orthodontic consultation. Radiographic examination showed the crown of a maxillary right central incisor to be positioned horizontally with root formation at the initial stage. The surgically repositioned incisor (by a close-eruption surgical flap technique) spontaneously erupted into correct alignment after 2 years 3 months. The erupted incisor remained vital and responded normally to percussion, mobility and sensitivity testing. The soft tissue, periodontal attachment, gingival contour and probing depths were normal. Follow-up radiographs confirmed the continued development of the root, with revascularization of the pulp and a normal appearance of the periodontal space and lamina dura. There was, however, shorter root formation and a narrower root cavity compared with the contralateral incisor. As a result, no orthodontic traction and alignment were required. This method of surgical repositioning is a viable alternative to the traditional approach of extraction or surgical exposure followed by orthodontic traction for a developing maxillary permanent central incisor in a horizontal position.

Child↗
PubMed2003

Agrobacterium tumefaciens-mediated transformation of Indian mulberry, Morus indica cv. K2: a time-phased screening strategy.

An efficient and reproducible protocol for the production of transgenic plants was developed for Morus indica cv. K2 by Agrobacterium tumefaciens-mediated transformation. The hypocotyls, cotyledon, leaf and leaf callus explants precultured for 5 days on regeneration medium were co-cultivated with a bacterial suspension at 10(9) cells/ml for 3 days in the dark. Infectivity of A. tumefaciens strain LBA4404 was more than that of strains GV2260 and A281, and among the various plasmids tried, pBI121 and pBI101:Act1 transformed nearly 100% of the explants followed closely by p35SGUSINT. About 90-100% of the explants tested positive in the beta-glucuronidase (GUS) histochemical assay performed after 3 days of co-cultivation. This high level of transient expression, however, decreased to 20-25% after 15 days. Gus activity was most stable in the callus explants, which emerged as the explant of choice for transformation. The transformed explants were selected on 50-75 mg/l kanamycin for 1 month, and 25-50% of the explants developed adventitious buds. On the basis of kanamycin-resistant shoots produced from the total number of explants inoculated, the transformation efficiency was 44%. After 1 month, 40% of these shoots displayed high gus activity as assessed by the GUS fluorometric assay. On a selection-free root induction medium, 80% of the shoots developed roots and 90% of the potted plantlets acclimatized to the growth room conditions. The 3-month-old regenerates showed gus and nptII(neomycin phosphotransferase II) gene activity as assayed by the GUS fluorometric assay and nptII enzyme assay, followed by PCR polymerase chain reaction (54.5%) analysis after 6-months. Transgene integration into the nuclear genome of 1-year-old regenerates was confirmed in 10 of the 18 transformants tested by Southern analysis. The transformation efficiency as defined by the number of transgenic plants produced from the total number of explants co-cultivated was 6%.

Agrobacterium tumefaciens↗
PubMed2004

Nitric oxide synthase expression and cell changes in dorsal root ganglia and spinal dorsal horn of developing and adult Rana esculenta indicate a role of nitric oxide in limb metamorphosis.

Metamorphosis of amphibians requires reconfiguration of sensory and locomotor neural networks. In view of such plastic changes and implications of nitric oxide (NO) in neural developmental shaping, we examined via histochemistry and immunohistochemistry its synthetic enzyme nitric oxide synthase (NOS) in dorsal root ganglia (DRGs) and dorsal horn of the developing and adult frog Rana esculenta. In limb DRGs, NOS positivity was first and selectively detected just before limb bud appearance, increased during metamorphosis, and was then down-regulated. In adulthood, NOS was expressed in some DRG neurons at all segmental levels. Similar features were detected in the dorsal horn neuropil. In limb DRGs, cell counts in Nissl-stained sections revealed a twofold increase of differentiated neurons during metamorphosis and an additional twofold increase in adulthood. Perikaryal sizes in limb DRGs did not vary during metamorphosis but increased and were more heterogeneous in the adult frog, probably reflecting adaptation to body size. NOS and cell changes during metamorphosis were much less marked in DRGs at other levels. Carbocyanine tracing documented selective labeling of NOS-expressing hindlimb DRG neurons from the spinal nerve at the time of initiation of hindlimb movements. The findings show that, in limb DRG neurons, NOS parallels cell differentiation and limb development during metamorphosis. The data also provide evidence of NOS expression in DRG cells innervating the hindlimbs when sensorimotor circuits become functionally mature. This study indicates a key role of NO production in the maturation of sensory functions that subserves in amphibians the transition from swimming to tetrapod locomotion.

Animals↗
PubMed1987

Development of the spinal nerves of the larval lamprey: IV. Spinal nerve roots of 21-mm larval and adult lampreys, with special reference to the relation of meninges with the root sheath and the perineurium.

Spinal nerve roots of 21-mm larval and adult lampreys were electron microscopically studied. In 21-mm larval lampreys, each ventral and dorsal rootlet contains axons of various diameters enclosed together as groups in individual troughs of a Schwann cell cytoplasm, lying in direct contact with one another, and is further ensheathed entirely by a basal lamina. Dorsal roots possess visceral axons, while ventral roots lack them. In adult lampreys the ventral and dorsal roots possess individual sheaths for larger somatic axons, each being surrounded by a single Schwann cell and the basal lamina and separated from one another by a considerable amount of connective tissue. Visceral fibers are present in both the dorsal and ventral roots of adult lampreys. They aggregate to form fascicles that lie among somatic axons, being separated from them. Two layers of the meningeal tissue invaginate to form a root sheath around the distal portion of individual dorsal and ventral roots of 21-mm larval lampreys. In adult lampreys the sheath is similarly formed but extends over most of the dorsal and ventral roots. The perineurium is not developed in 21-mm larval lampreys, but is present and ensheaths only the proximal portion of spinal nerve trunks outside the meninges in adult lampreys: it is completely absent along most of the length of peripheral nerves. In both larval and adult lampreys, the outer cell layer of the root sheath is open-ended near the middle of nerve roots with respect to the extramedullary connective tissue space. Similar loosening of the cellular barrier is seen along blood vessels. Thus, the outer meningeal fibrous layer is directly continuous with the extra medullary connective tissue space by way of the inner fibrous layer of the root sheath.

Animals↗
PubMed1992

Molecular genetic approaches to plant development.

Higher plant morphogenesis has received renewed interest over the past few years. The improvement of molecular genetic approaches to generate tagged developmental mutants, for instance by T-DNA insertion, facilitated the isolation and characterization of the altered genes. Here we present recent progress on flower and root morphogenesis in the small crucifer Arabidopsis thaliana. The current model of Arabidopsis flower development is presented. We report on FLOWER1 (Fl1), which is a T-DNA-tagged ap2 allele. Our observations indicate that this Fl1 mutant has, besides the homeotic Ap2 phenotype, an aberrant seed coat, suggesting that this gene has also a function late in flower development. Furthermore, we present a brief summary about root development and focus on the super root (Sur) mutant, which is an ethyl methanesulfonate-induced mutant that produces excess lateral roots. Root explants of the Sur mutant, that do not develop further than the 4-leaf stage, can be induced to produce normal-looking shoots and flowers by addition of only cytokinin to the medium. The phenotype of Sur and its relation to the action of phytohormones is discussed.

Morphogenesis↗
PubMedDate not supplied

[Effect of a peony root preparation on the status of the insulin and hemostatic system in animals during development of alloxan diabetes].

Administration of peony roots preparations provides the stable prophylactic effect against the development of experimental alloxan diabetes. This preparation and its complex with aspirin conserves the normal hemostatic system status and moderates the insular system disturbances. These preparations provide greater survival of animals.

Animals↗
PubMedDate not supplied

Risk factors for neo-aortic root enlargement and aortic regurgitation following arterial switch operation.

The objectives of this study were to evaluate changes in dimension of the neo-aortic annulus, aortic root, and aortic anastomosis following arterial switch operation (ASO) and to identify risk factors for developing abnormal neo-aortic root enlargement and aortic regurgitation (AR). Prior studies report development of neo-aortic root dilatation and AR in a small subset of patients after ASO. Predisposing factors for neo-aortic root dilatation and development of moderate/severe AR are poorly understood. We performed a retrospective review of all patients with d-transposition of the great arteries (d-TGA) or double-outlet right ventricle with subpulmonary ventricular septal defect (VSD) who underwent ASO from May 1986 to January 2001. Serial echocardiograms were reviewed to measure neo-aortic annulus, root, and anastomosis diameter (z scores) and to determine progression of AR. Potential risk factors were assessed for developing neo-aortic root enlargement and AR. There were 119 patients (44 female and 75 male): 73 patients had simple d-TGA, 36 had d-TGA with ventricular septal defect, and 10 had a Taussig-Bing heart. The median duration of follow-up was 65 months (range, 12-180). The median neo-aortic root (z = 0.55+/-2.2; p < 0.01) and aortic annulus dimensions (z = 1.57+/-1.75; p < 0.01) were significantly increased over the study period. Aortic anastomosis diameter correlated with growth of the ascending aorta (z = 0.55+/-1.24). Development of severe neo-aortic root enlargement was associated with prior pulmonary artery (PA) banding (p < 0.01), the presence of a VSD (p = 0.03), and Taussig-Bing anatomy (p < 0.01) but was independent of coronary arterial anatomy, coronary arterial transfer technique, or associated lesions (p > 0.05). At latest follow-up, there was no or trivial AR in 88 patients, mild AR in 29 patients, and moderate to severe AR in 3 patients. Risk factors for developing mild or worse AR included severe or rapid neo-aortic root dilatation (p < 0.01). Only 3 patients required surgical intervention for AR. Despite the significant prevalence of neo-aortic root enlargement at intermediate follow-up after ASO, there is a low incidence of significant AR. Prior PA banding, the presence of VSD, and Taussig-Bing anatomy are risk factors for severe root enlargement. Surgical intervention for AR was rare (2%), however, serial surveillance of such patients is vital to monitor for neo-aortic root enlargement and potential aortic valve dysfunction.

Anastomosis, Surgical↗