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PubMedDate not supplied

Grown gall plant tumors of abnormal morphology, induced by Agrobacterium tumefaciens carrying mutated octopine Ti plasmids; analysis of T-DNA functions.

Ti plasmid mutants derived from Agrobacterium tumefaciens strain Ach5 that induce tumors of abnormal morphology have been analyzed. On tobacco, A. tumefaciens mutant strain LBA4060 induces tumors that specifically give rise to shoots. Shoots continue to grow from in vitro cultured bacteria-free tumor tissue derived from such tumors. The mutant character is shown to be correlated with the insertion of an A. tumefaciens IS element, IS60, into the left arm of the T-region of the octopine Ti plasmid. Evidence is presented showing that IS60 is transferred into the plant cell DNA as part of the T-DNA. A second Ti plasmid insertion mutant A. tumefaciens strain LBA4210, with a Tn904 transposon in the center of the T-region, induces tumors that specifically exhibit a root development on tobacco plants. T-DNA has been detected in sterile amorphous crown-gall tissue derived from these tumors. The transposon Tn904 insertion was shown to result a changed "core" T-DNA. Abnormal tumor morphologies induced by these mutant strains have been observed also on Kalanchoë stems. On tomato plants the mutants induce small unorganized tumors while on Nicotiana rustica unorganized tumors, nearly equal in size to those caused by the wild-type strain have been induced. LBA4060 was shown to be avirulent on Kalanchoë leaves and LBA4210 was weakly virulent. Infection of Kalanchoë leaves or tomato plants with a mixture of separately grown cultures of both mutants resulted in the formation of more or less normal tumors. The exposure of a tomato plant to naphthalene acetic acid (NAA), a synthetic auxin, during development of tumors induced by LBA4060 stimulated tumor formation. Tumor growth induced by LBA4210 was found to be stimulated by kinetin.

Cloning, Molecular↗
PubMed2026

Establishment of an in vitro culture and regeneration protocol for the native Chilean grass Polypogon australis Brong.

Polypogon australis Brong. is a native Chilean grass frequently found colonizing metal-rich mine tailings, yet it lacks an established in vitro regeneration system to support controlled physiological and biotechnological studies. Here, we report a reproducible protocol for seed germination, callus induction, and plant regeneration using coleoptile-mesocotyl explants. Surface-sterilized seeds were germinated on Murashige and Skoog (MS) medium supplemented with sucrose, achieving a cumulative germination percentage of 47.67 ± 3.15% after 15 days. The coleoptile-mesocotyl explant proved highly responsive to culture on callus induction medium (CIM) supplemented with dicamba, resulting in a callus induction frequency of 30.55 ± 11.96% after 3-5 weeks. Induced calli were predominantly embryogenic, with embryogenic calli representing 65.42 ± 8.61% of the total callus population. Embryogenic calli regenerated complete plantlets with a regeneration efficiency of 45.0 ± 23.3%. Organogenic structures, including primary shoots and roots, developed directly from embryogenic calli maintained on callus induction medium (CIM) supplemented with dicamba, without transfer to a specialized regeneration medium containing organogenesis-promoting growth regulators. After the initiation of organogenesis, cultures were exposed to a 16 h light/8 h dark photoperiod while remaining on CIM, and regenerated plantlets were subsequently transferred to MS+10 S medium for further growth and elongation. This study establishes the first complete in vitro regeneration system for P. australis, providing a practical framework for future physiological studies, large-scale propagation, genetic transformation, and genome engineering applications in this ecologically relevant native Chilean grass.

Regeneration↗
PubMed1995

Purification and characterization of phospholipase D (PLD) from rice (Oryza sativa L.) and cloning of cDNA for PLD from rice and maize (Zea mays L.).

Phospholipase D (PLD) was purified to high homogeneity from rice bran (Oryza sativa L.). Two peaks of PLD activity were resolved by Mono Q anion-exchange chromatography. The molecular mass of PLD in both peaks was 82 kDa on SDS-PAGE and 78 kDa in gel filtration. Antibodies raised against the protein in one of the peaks precipitated the enzyme activities in both peaks. Enzymatic characteristics of PLD in the two peaks were identical except for a difference of 0.1 in the isoelectric points. Sequence analysis covering more than 10% of the amino acids of the proteins and peptide mapping did not detect any difference in the primary structure of the proteins. A cDNA for PLD was isolated from rice and it encoded a protein of 812 residues. The N-terminal sequences of purified PLDs matched the deduced amino acid sequence starting from residue 47. A Northern blot showed this gene was expressed in leaves, roots, developing seeds and cultured cells, and a Southern blot detected a single band of rice genomic DNA hybridizing to the cDNA. A cDNA for PLD was also isolated from maize. The similarity of the deduced amino acid sequences of PLD was 90% between rice and maize, 73% between the cereals and castor bean.

Amino Acid Sequence↗
PubMed2016

Characterization of Class III Peroxidases from Switchgrass.

Class III peroxidases (CIIIPRX) catalyze the oxidation of monolignols, generate radicals, and ultimately lead to the formation of lignin. In general, CIIIPRX genes encode a large number of isozymes with ranges of in vitro substrate specificities. In order to elucidate the mode of substrate specificity of these enzymes, we characterized one of the CIIIPRXs (PviPRX9) from switchgrass (Panicum virgatum), a strategic plant for second-generation biofuels. The crystal structure, kinetic experiments, molecular docking, as well as expression patterns of PviPRX9 across multiple tissues and treatments, along with its levels of coexpression with the majority of genes in the monolignol biosynthesis pathway, revealed the function of PviPRX9 in lignification. Significantly, our study suggested that PviPRX9 has the ability to oxidize a broad range of phenylpropanoids with rather similar efficiencies, which reflects its role in the fortification of cell walls during normal growth and root development and in response to insect feeding. Based on the observed interactions of phenylpropanoids in the active site and analysis of kinetics, a catalytic mechanism involving two water molecules and residues histidine-42, arginine-38, and serine-71 was proposed. In addition, proline-138 and gluntamine-140 at the 137P-X-P-X140 motif, leucine-66, proline-67, and asparagine-176 may account for the broad substrate specificity of PviPRX9. Taken together, these observations shed new light on the function and catalysis of PviPRX9 and potentially benefit efforts to improve biomass conservation properties in bioenergy and forage crops.

Amino Acid Sequence↗
PubMed1991

Teeth for the future.

The main dietary influences on teeth are, with the exception of ingested fluoride, local rather than systemic. The frequent use of carbohydrates which can be rapidly fermented by dental plaque micro-organisms is the major factor in dental decay. Sweetened and/or highly acidic soft drinks or medicines sweetened with sugars may damage the teeth. Similarly infant's comforters also have their dangers if they provide prolonged exposure of the teeth to cariogenic conditions. Although dental caries is primarily a disease of children many adults still develop new lesions and adults who have lost gingival tissue through periodontal disease may develop root surface caries. Pathological conditions of the oral mucosa can arise from nutritional disorders or inappropriate dietary habits. Health education is most effective when it carries a positive message so encouraging patients to eat the right kind of tasty snacks and to round off meals with sugar-free products or a modicum of cheese should in healthier eating without conflicting with general health guidelines.

Adult↗
PubMed1995

Changes in the vascular network of the oral epithelium and reduced enamel epithelium during tooth eruption.

The purpose of this study was to examine the vascular network beneath the reduced enamel epithelium (REE) and oral epithelium (OE) during tooth eruption. Using the corrosive-resin casting method, vascular resin casts were prepared from premolar and molar teeth of the dog and examined by scanning electron microscopy. The vascular network beneath the REE is arranged in two layers, an inner layer consisting of a dense capillary network and an outer layer composed primarily of arterioles and venules. Throughout tooth eruption, the configuration of the vessels of the inner layer is continually changing from a network of capillary loops to a fishnet pattern, whereas the arrangement of the vessels of the outer layer remains fairly constant. When the crown emerges into the oral cavity, leakage of resin from the vessels provides evidence of increased vascular permeability, suggesting the presence of inflammation within the marginal gingiva. When root development is nearly complete, the vascular network adjacent to the REE becomes continuous with that of the OE. The inner margin of the free gingiva receives its blood supply from this network, and the vessels of this network also give off branches which anastomose with the capillary network of the periodontal ligament.

Animals↗
PubMed1994

Effects of tetracycline-containing gel and a mixture of tetracycline and citric acid-containing gel on non-surgical periodontal therapy.

The purpose of this study was to assess the clinical and microbiological effects of a newly developed root conditioning gel system containing tetracycline or a mixture of tetracycline and citric acid on non-surgical periodontal therapy. Sixty-four (64) single-rooted teeth with a probing depth of 4 to 6 mm were randomly subjected to one of the following four treatments; 1) root planing alone (RP group); 2) tetracycline-containing gel alone (TCG group); 3) root planing plus tetracycline-containing gel (RP + TCG group); or 4) root planing plus a mixture of tetracycline and citric acid-containing gel (RP + TC-CAG group). Probing depth, attachment level, and tooth mobility were measured and the presence of dental plaque and gingival inflammation was recorded at baseline and after 2, 4, 8, and 12 weeks. Subgingival plaque samples from each site were collected at the same visits and examined with phase contrast microscopy for proportions of motile rods and spirochetes. Plaque index, gingival sulcus bleeding index (SBI), probing depth, and attachment level decreased significantly in all groups compared to the baseline values (P < 0.05). A significant decrease in probing pocket depth was noted after 12 weeks in RP + TC-CAG group compared to the other groups (P < 0.05). Significantly more gain in attachment was detected in the RP + TC-CAG group compared to the TCG group (P < 0.05). Tooth mobility scores also decreased later in the study. A significant decrease in the proportion of motile rods was found primarily in the RP + TC-CAG group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Evaluation of machine, technician, and interpreter effects on ultrasonic measures of backfat and longissimus muscle area in beef cattle.

Before slaughter, 44 Hereford-sired steers were measured ultrasonically for backfat (UFAT) and longissimus muscle area (ULMA) between the 12th and 13th ribs by three technicians (TECH) using two different machines (MACH) on two consecutive days (DAY). Each TECH interpreted (INT) his own images in addition to other TECH images. The absolute values of the difference between the 2 DAY's ultrasound measurements for ULMA (magnitude of LMAR) and UFAT (magnitude of FATR) were analyzed with a model including fixed effects of MACH and TECH with a random effect of steer and all interactions. For both magnitude of LMAR and magnitude of FATR, MACH x TECH was significant (P < .10). Correlations between the 2 DAY's measurements ranged from .36 to .90 and .69 to .90 for ULMA and UFAT, respectively. Simple statistics to quickly evaluate TECH and MACH were developed. Root mean squared errors (RMSE) and error standard deviations (ESD) between repeated measurements ranged from 3.89 to 11.32 and 3.93 to 11.34 cm2 for ULMA and .12 to .20 cm and .12 to .20 cm for UFAT, respectively. For accuracy, the absolute values of the difference between the ultrasound and carcass measurement for fat (magnitude of FATD) and longissimus muscle area (magnitude of LMAD) were analyzed with a model accounting for fixed effects of DAY, TECH, and MACH and a random effect of steer with all higher-order interactions. For magnitude of LMAD, TECH x MACH was a significant source of variation (P < .001). Also, a similar model was fit that included the fixed effects of TECH, MACH, and INT and a random effect of steer with all interactions. The MACH x INT interaction was found to be significant for magnitude of LMAD (P < .05). From this research, TECH and MACH differences do exist. Ultrasound is a valid means of measuring carcass traits in live steers if appropriate personnel and equipment are selected.

Adipose Tissue↗
PubMed1996

Influence of the antineoplastic agent cyclophosphamide on dental development in rat molars.

The effect of cyclophosphamide (Cy) on tooth development was studied in molars of 18 young Sprague-Dawley rats. Doses of 30 mg/kg body weight of Cy dissolved in 1 ml 0.9% NaCl were administered to 18 experimental rats and 1 ml 0.9% NaCl to 18 control rats at 10 and 13 days of age. The most obvious changes in the experimental teeth could be seen in the developing pulp of the third molar and developing roots of the first and second molars. Wide cell-free areas appeared in the third molar 2 days after the last injection; later these areas turned into mineralized osteodentin. Similar areas could be observed also in the roots of the first and second molars. These changes were related to the developmental stage of the area.

Animals↗
PubMed1992

Evolutionary biology and pathology of vitamin D.

There is mounting evidence that essentially all fungi, plants and animals living on earth produce provitamin D. It is likely that once exposed to sunlight, these provitamins are converted to previtamin D. It is unclear why fungi, phytoplankton, zooplankton and plants have the capacity to produce such large quantities of provitamin D. It is likely, however, that provitamin D and possibly vitamin D play an important biologic role in these organisms. Buchala and Schmid found, for example, that vitamin D3 promoted adventitious root development. It may be that provitamin D has a more fundamental function in lower life forms. Provitamin D and its photoproducts have UV absorption spectra that overlap with the ultraviolet absorption spectra from ultraviolet radiation-sensitive macromolecules including DNA, RNA and proteins. Thus, provitamin D and photoisomers could serve as a photon sink, and therefore, act as a natural sunscreen to protect lower life forms from the damaging effects of the high energy ultraviolet radiation that they are exposed to. It is more clear, however, that amphibians, reptiles, birds, mammals and humans all require vitamin D and that the vitamin D must be metabolized to 1,25(OH)2D3 before it can carry-out its physiologic functions on calcium and bone metabolism. The intense research activities during the past decade on the antiproliferative and differentiation activities of 1,25(OH)2D3 has opened a new chapter for this vitamin/hormone. 1,25(OH)2D3 and its analogs are being developed for the treatment of psoriasis, breast cancer, and leukemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

A study of natal teeth in Hong Kong Chinese.

The purpose of this study was to review cases of natal teeth in babies born between January 1984 and December 1988 at the Queen Elizabeth Hospital Hong Kong. There were 53678 births at the hospital during this period and 48 babies had natal teeth, a prevalence of 1:1118. The 48 babies had 72 natal teeth, all mandibular central incisors. The natal teeth in two babies were supernumerary teeth of a predeciduous dentition. Twenty nine natal teeth were extracted because they were hypermobile, three were extracted because they traumatized the ventral surface of the babies's tongue, and 16 were not extracted. The subjects were reviewed one day after the initial examination, and then after 1 week, 1 month and at 6-month intervals. No appreciable space loss occurred following the extractions. Root development occurred in teeth that were not extracted, but the crowns were hypoplastic in three cases.

Female↗
PubMed1990

Management of teeth with open apexes and necrotic pulps: representative cases.

This paper briefly reviews the pros and cons of five methods used to treat a tooth with a necrotic pulp and an open apex (incompletely developed root), and presents representative treatments of open apex cases. These treatments include customized cone, short-fill, periapical surgery, apexification, and one-visit apexification.

Adult↗
PubMed1988

[Morphological characteristics of inter-radicular space of the first and second lower permanent molars].

In this study, 537 extracted molars (261 first and 276 second molars) with well developed roots were examined to assess the width of the interradicular space and the shape of the furcation vault. The roots were set widely apart in 91.6% of the first and 64.8% of the second permanent molars, while the roots set closely together were observed in 8.4% and 27.9% of the first and second molars, respectively. Fuseg roots were found in second molars only, in 7.2% of cases. A flat furcation fornix was detected in 18.3% of the first and 14.0% of the second molars, whereas a convex shape was observed in 20.7% of the first and 10.5% of the second molars, respectively (P less than 0.001). A convex shape of furcation was found in 8.0% of the first and 27.3% of the second molars, respectively (P less than 0.001). Interradicular ridge was present in a very high percentage (52.9% of the first and 48.0% of the second molars). A concave shape of furcation fornix was statistically more frequent in molars with closely set roots for the first and second permanent molars (P less than 0.001). It seemed that the width of the interradicular space had no influence on the prevalence of interradicular bridges, regardless of type of molars involved.

Humans↗
PubMed1987

Staged salvage reconstruction of grade-IV and V spondylolisthesis.

Sixteen patients who had Grade-IV or V spondylolisthesis underwent a staged reconstruction for the salvage of a failed result of previous procedures. The indications for operation were incapacitating pain, radicular pain, pseudoclaudication, or the inability to stand upright. All patients had shown progression of the deformity after the previous surgery. At an average length of follow-up of fifty-two months, all patients had resumed normal activities and were free of the pain and symptoms of spinal stenosis. The complications included delayed union in six patients and a traumatic pseudarthrosis in one patient. In all of these patients a solid fusion was obtained after additional surgery. In five patients, neuropathy of the fifth lumbar-nerve root developed after surgery; it resolved in three patients. From this work, it is concluded that staged reconstructive surgery is feasible in patients who have Grade-IV or V spondylolisthesis with incapacitating pain and deformity that interfere with normal function. The benefits outweighed the risks in this very select group of patients.

Adolescent↗
PubMed1996

A mutation in protein phosphatase 2A regulatory subunit A affects auxin transport in Arabidopsis.

The phytohormone auxin controls processes such as cell elongation, root hair development and root branching. Tropisms, growth curvatures triggered by gravity, light and touch, are also auxin-mediated responses. Auxin is synthesized in the shoot apex and transported through the stem, but the molecular mechanism of auxin transport is not well understood. Naphthylphthalamic acid (NPA) and other inhibitors of auxin transport block tropic curvature responses and inhibit root and shoot elongation. We have isolated a novel Arabidopsis thaliana mutant designated roots curl in NPA (rcn1). Mutant seedlings exhibit altered responses to NPA in root curling and hypocotyl elongation. Auxin efflux in mutant seedlings displays increased sensitivity to NPA. The rcn1 mutation was transferred-DNA (T-DNA) tagged and sequences flanking the T-DNA insert were cloned. Analysis of the RCN1 cDNA reveals that the T-DNA insertion disrupts a gene for the regulatory A subunit of protein phosphatase 2A (PP2A-A). The RCN1 gene rescues the rcn1 mutant phenotype and also complements the temperature-sensitive phenotype of the Saccharomyces cerevisiae PP2A-A mutation, tpd3-1. These data implicate protein phosphatase 2A in the regulation of auxin transport in Arabidopsis.

Amino Acid Sequence↗