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At least 253 records · Page 14Linked to original sources
PubMed1994

Light inactivation of Arabidopsis photomorphogenic repressor COP1 involves a cell-specific regulation of its nucleocytoplasmic partitioning.

Arabidopsis COP1 acts as a repressor of photomorphogenesis in darkness, and light stimuli abrogate this suppressive action. COP1, when fused to beta-glucuronidase (GUS), is enriched in the nucleus in darkness, but not in the light, in hypocotyl cells of Arabidopsis seedlings and epidermal cells of onion bulbs. In Arabidopsis hypocotyl cells, the nuclear GUS-COP1 level changes in response to dark-light transitions and quantitatively correlates with the extent of repression of photomorphogenic development. In root cells, GUS-COP1 is constitutively nuclear, consistent with an established role of COP1 in suppressing root chloroplast development in both light and darkness. We conclude that COP1 acts inside the nucleus to suppress photomorphogenesis and that light inactivation of COP1 involves a cell type-specific control of its nucleocytoplasmic partitioning.

Allium↗
PubMed1991

Phenotypically normal transgenic T-cyt tobacco plants as a model for the investigation of plant gene expression in response to phytohormonal stress.

The tumour-inducing T-DNA gene 4 (T-cyt gene) of the nopaline Ti plasmid pTiC58 was cloned and introduced into tobacco cells by leaf disc transformation using Agrobacterium plasmid vectors. Tobacco shoots exposed to elevated cytokinin levels were unable to develop roots and lacked apical dominance. Using exogenously applied phytohormone manipulations we were able to regenerate morphologically normal transgenic tobacco plants which differed in endogenous cytokinin levels from normal untransformed plants. Although T-cyt gene mRNA levels, as revealed by dot-blot hybridization data, in these rooting plants were only about half those in primary transformed shoots the total amount of cytokinins was much lower than in crown gall tissue or cytokinin-type transformed shoots as reported by others. Nevertheless the cytokinin content in T-cyt plants was about 3 times greater than in control tobacco plants. Elevated cytokinin levels have been shown to change the expression of several plant genes, including some nuclear genes encoding chloroplast proteins. Our results show that the mRNA levels of chloroplast rbcL gene increase in cytokinin-type transgenic tobacco plants as compared with untransformed plants. Data obtained suggest that T-cyt transgenic plants are a good model for studying plant gene activity in different parts of the plant under endogenous cytokinin stress.

Agrobacterium tumefaciens↗
PubMed1990

Electromyographic activity in the shoulder-neck region according to arm position and glenohumeral torque.

The electromyographical (EMG) response to isometric ramp contractions of the right arm, the left arm, and both arms was studied using four pairs of surface electrodes above the right upper trapezius muscle (UT) of six men and six women. Contractions were made against gravity with the active arm(s) in eight positions, ranging from flexion to abduction. To describe arm positions, new, simple terminology was developed. Root mean square (rms)-converted EMG-signals were normalized (EMGnorm) with respect to a reference contraction. The EMGnorm corresponding to a 15 N.m torque in the right glenohumeral (GH) joint was strongly related to the position of the right arm (P less than 0.001). The shape of this relationship depended on the electrode position (P less than 0.001). The ratio between EMGnorm at 30 N.m and 15 N.m GH torques was related to arm position (P less than 0.001) and differed between electrodes (P less than 0.001). A left-side GH torque resulted in right-side (contralateral) EMG activity, typically corresponding to 20%-30% of that obtained during similar right-side GH torque. Bilateral GH torque implied 0%-50% increase in EMG activity as compared to that obtained with the right arm alone. The results have shown that signals from one pair of surface electrodes above UT cannot be taken as representative of the EMG activity from electrodes located elsewhere above UT. The EMG recordings reflected a complex pattern of muscular activation, significantly related to both outwardly visible factors (arm position, GH torque), and within-body servosystems (motor control reflexes).

Adult↗
PubMed1996

Characterization and identification of a human dentin phosphophoryn.

The present study further characterizes an extract from immature, human tooth apicies from which an intact dentin phosphoprotein has been identified. Third molar apicies from developing roots were decalcified in 10% EDTA until Ca2+ was undetectable in the decalcifying solution. The crude extract was run on 7.5% SDS-PAGE and stained with "Stains-All." Four distinct bands were found and the molecular weights were 140, 60, 50, and 34 k. When run on a SDS-PAGE under nonreducing conditions the 60, 50, and 34 k bands were absent. These results suggest that the lower molecular weight bands may be subunits of the larger protein. The extract was then further purified by adding CaCl2 and MgCl2 to precipitate the phosphoprotein. The precipitate was subjected to a DEAE-Sepharose CL6B column and eluted by 0-0.7 M NaCl gradient solution. The amino acid composition of the purified phosphoprotein was determined and the extract was found to be rich in serine and aspartic acid residues. The N-terminal peptide Asp-Asp-Pro was identified. The sequence of the three amino acids is identical to rat incisor phosphoprotein.

Amino Acid Sequence↗
PubMed2025

Genome-wide identification and analysis of paclobutrazol-resistance gene family in cotton and the positive role of GhPRE3 in salt stress and drought stress resistance.

Compared with other transcription factors, much less studies have been performed on paclobutrazol-resistance (PRE), a subgroup of the extensive bHLH transcription factor gene family, and the research in cotton was also limited. By utilizing the PRE genes and their conserved domains identified in Arabidopsis, a total of 23, 22, 11, and 12 PRE genes were identified from two major cultivated cotton species and their two ancestors, respectively. The cotton PRE gene family was categorized into three subgroups based on evolutionary tree analysis. Motif and intron analyses indicated that the PRE gene has remained highly conserved throughout evolution. Collinearity analysis indicated that gene duplication, particularly through fragment replication, has significantly contributed to the expansion of the cotton PRE family. An exploration of the conserved elements within the PRE gene family uncovered numerous elements associated with plant stress resistance. Additionally, cotton transcriptome and qRT-PCR analysis showed that PRE genes were associated with a variety of abiotic stresses, including salt, drought, and cold treatments. Subcellular localization experiments indicated that the GhPRE3 gene is associated with membrane proteins. Finally, we selected the GhPRE3 gene for a VIGS experiment, which revealed that under salt stress and drought stress conditions, the wilting of leaves in the GhPRE3-silenced plants was significantly more severe than that observed in the control group, with T-AOC levels notably lower and MDA levels significantly higher. Overexpression of GhPRE3 enhanced seed germination and root development in transgenic Arabidopsis thaliana under salt stress and drought stresses. This suggests that GhPRE3 plays a positive regulatory role in cotton tolerance to salt and drought stressed, providing a reference for molecular genetic breeding of cotton with salt and drought tolerance.

Gossypium↗
PubMed1983

Competence and determination in the process of in vitro shoot organogenesis.

Leaf explants of Convolvulus arvensis produce shoots when cultured on Murashige and Skoog salts, sucrose, vitamins and 0.05 mg/liter IAA plus 7.0 mg/liter 2-isopentenyl adenine. Shoot-inducing, root-inducing, or callus-inducing medium (SIM, RIM, or CIM) will cause small amounts of callus to form at the cut edges of the explant. This first-formed callus is developmentally interchangeable: SIM induces shoots in callus formed on CIM or SIM with equal effect and efficiency. Once induction begins in competent callus, the callus is no longer interchangeable. Under the continued influence of SIM, cells, or groups of cells become determined for shoot formation. This determination is strongly canalized for shoot formation: subsequent transfer to root-inducing medium does not affect the formation of shoots by the explant. The control of organogenesis by the auxin/cytokinin balance must occur between the time the tissue becomes competent and the time it is determined for shoot (or root) development. It is not known whether this control is a single or multiple phenomenon.

Cell Differentiation↗
PubMed1978

A microangiographic study of vascular changes in replanted and autotransplanted teeth of young dogs.

The purpose of the present investigation was to study the revascularization process of the pulp of replanted and autotransplanted teeth with incomplete root development in dogs. A barium-sulfate injection method combined with contact microradiography was used. Ingrowth of apparently new vessels was seen during the first postoperative days. After 10 days, visible vessels were seen in the apical half of the pulp, and after 30 days, in the whole pulp. Branches and apparently also anastomoses between pulpal vessels were seen after 10 days but were especially numerous after 30 days. One hundred eighty days postoperatively, only one of fifteen teeth was devoid of visible vessels, indicating pulpal necrosis. Thirteen of the remaining fourteen teeth exhibited visible vessels throughout the entire length of the pulp. It seems, therefore, that replanted and autotransplanted teeth with open apices have a high potential for repair. The revascularization of the pulp appeared to occur mainly by ingrowth of new vessels. In some instances, however, anastomoses seemed to form to pre-existing vessels in the pulp.

Animals↗
PubMed1981

Calcific bridging of dental pulp caused by iatrogenic hypercalcemia. Report of a case.

A case of renal osteodystrophy treated with high doses of vitamin D is presented. The treatment, carried out when the patient was between 3 1/4 and 6 years of age, induced hypercalcemia (up to 13.9 mg./dl.) which resulted in dentinal bridging corresponding chronologically to the part of the root developing at this age. Dentinal bridging associated with iatrogenic hypercalcemia has not been reported previously.

Calcinosis↗
PubMed1985

Eruption of rootless teeth in congenital renal disease.

Eruption of rootless mandibular premolars and other dental defects in a girl suffering from congenital kidney disease are described. The successful management of these excessively mobile teeth allowed them to develop roots of sufficient length. Hypotheses of tooth emergence are viewed in the light of these rootless eruptions.

Bicuspid↗
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↗
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↗
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↗