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13 recordsLinked to original sources
PubMed2025

Comparative genomic analysis of Acer tsinglingense and A. davidii provides insights into nervonic acid biosynthesis, population evolution and genome vulnerability of endangered A. tsinglingense.

Global biodiversity is facing threats from climate change, habitat fragmentation, and anthropogenic activities-pressures that particularly endanger endemic and narrowly distributed species. In this study, the high-quality chromosome-level genomes of two ecologically divergent maples were assembled: the endangered and range-restricted Acer tsinglingense (791.40 Mb) and its widespread congener Acer davidii (1291.99 Mb). Phylogenomic analysis indicates that the two species diverged ~16.3 million years ago, with A. tsinglingense showing notable gene family expansions in secondary metabolite pathways. Notably, the 3-ketoacyl-CoA synthase gene family, which is involved in nervonic acid biosynthesis, underwent significant expansion and tandem duplication in A. tsinglingense, exhibiting high expression in buds. Population genomic analysis revealed that, compared with the widely distributed A. davidii, A. tsinglingense possesses lower genetic diversity, higher harmful mutation load, and signatures of a severe population bottleneck during the Late Pleistocene. Genome-environment association analysis further identified climate-adaptive genomic variations linked to five key environmental factors and projected potential genomic offsets under future climate scenarios. The southern lineage of A. tsinglingense exhibited greater climate sensitivity and genomic vulnerability under strong selective pressures, underscoring its importance as a conservation priority. Our research reveals that metabolic specializations in A. tsinglingense (such as the synthesis of nervonic acid) may confer competitive advantages in specific habitats. However, factors including its restricted distribution, historical population bottlenecks, and accumulated genetic load severely constrain its evolutionary potential to cope with rapid climate change. These findings emphasize the importance of elucidating the genomic basis and mechanisms of endangerment in metabolically specialized and threatened plant species to inform effective conservation strategies.

Genome, Plant↗
PubMed1977

The 5,5-dimethyloxazolidine-2[14C],4-dione distribution technique and the measurement of intracellular pH in Acer pseudoplatanus cells.

The intracellular pH of suspension-cultured Acer pseudoplatanus cells, was estimated from the distribution of 5,5-dimethyloxazolidine-2[14C],4-dione (DMO) between the culture medium and the cells. The metabolization of DMO in this biological system introduces an error in the calculated intracellular pH value. Three methods are given to overcome this difficulty and to estimate the equilibrium between intracellular and extracellular DMO molecules. A preliminary study has shown that the intracellular pH remains constant about 6.5 when the extracellular pH increases from 5.6 to 7.3.

Cells, Cultured↗
PubMedDate not supplied

The molecular weight of rRNA precursor molecules and their processing in higher plant cells.

Actively dividing callus cells of higher plants (Petroselinum crispum, Daucus carota, Acer pseudoplatanus) were used to detect the primary gene product of rDNA in vivo. Parsley and carrot cells were labelled with [32P]orthophosphate. Under non-denaturing conditions, in both cases only one high molecular weight rRNA precursor was present on polyacrylamide gels. Its molecular weight did not exceed 2.5 x 10(6) dalton. Under denaturing conditions, 2.0--2.1 x 10(6) dalton were determined on formamide gels. This rRNA precursor was already present after a labelling period of 5--10 min. In parsley cells labelled mature rRNA (25S and 18S) arrived in the cytoplasm 45 min after onset of incubation. In Acer pseudoplatanus incubated with [3H]uridine two rapidly labelled components did emerge from polyacrylamide gels without formamide; their molecular weights were 2.3 and 3.2--3.4 x 10(6) dalton. After electrophoresis in formamide, the larger component disappeared, thus indicating that it would be an intermolecular aggregate of different RNAs. From these results we have no evidence for the existence of rRNA precursors exceeding the molecular weight of 2.5 x 10(6) dalton.

Cells, Cultured↗
PubMed1979

Contrasting oxygen-effects in the inactivation of ribonuclease A by N.3, (SCN).-2 and .OH radicals.

N.3 exhibits higher efficiency than .OH in the inactivation of RNase in de-acerated (neutral) aqueous solution. In O2-saturated solution the .OH-induced inactivation is enhanced, but N.3 and (SCN).-2 become remarkably inefficient. Our results suggest that semi-oxidized tyrosine, the predominant initial defect induced by N.3 and (SCN).-2 but not by .OH2 can be re-reduced upon reaction with O.-2 or cysteine.

Chemical Phenomena↗
PubMed1979

Partial base-methylation and other structural differences in the 17 S ribosomal RNA of sycamore cells during growth in cell culture.

Sycamore (Acer pseudoplatanus L.) cytoplasmic rRNA was investigated in rapidly dividing cells, cells starting mitosis after the lag phase of growth (4 days) induced by deconditioning of the culture medium and also in growth-arrested cells from 10 day-old cultures deprived of exogenous auxin (i.e. exponential, early exponential and 2,4-dichlorophenoxyacetic acid (2,4-D)-deprived cultures). rRNA was extracted and purified from mixed 14C-labelled exponential cultures and 3H-labelled early exponential cultures. A 14C-labelled exponential culture and a 3H-labelled 2,4-D-deprived culture were analyzed in the same way. The 17 S rRNA molecules from both early exponential and 2,4-D-deprived cultures displayed a lower electrophoretic mobility on polyacrylamide gels than those from exponential cultures. Alkaline and acid hydrolysates of purified 17 S rRNA labelled on the phosphate groups or the methyl groups were analyzed on ion-exchange resins. There was no change in the extent of ribose methylation of the molecule from the three different cultures. However, the base methylation of the 17 S rRNA was decreased in early exponential cultures and in 2,4-D-deprived cultures. Part of the molecules synthesized in early exponential cultures specifically lacked 7-methylguanine, N6-methyladenine and N6,N6-dimethyladenine. The possible significance of these changes in the 17 S rRNA were discussed.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1978

Measurement of intracellular pH and aspects of its control in higher plant cells cultivated in liquid medium.

The 5,5-dimethyloxazolidine-2,4-dione (DMO) method for the determination of intracellular pH has been adapted to Acer pseudoplatanus cells cultivated in liquid medium. DMO is metabolized by these cells and this parameter has to be taken into account in the measurement of the intracellular concentration of free DMO. As the cells contain a large acidic vacuolar compartment, the intracellular pH estimated from the DMO technique is an overall pHi', the dependence of which on various cytoplasmic and vacuolar characteristics has been discussed. Important modifications of these overall pHi values under the influence of CO2 or NH4+ have been measured. These pHi modifications strongly affect the regulation of cell division through the control of the intracellular concentration of hormones of the auxin type.

Acid-Base Equilibrium↗
PubMed1979

Studies on the methylation of cytoplasmic ribosomal RNA from cultured higher plant cells.

The methylation of cytoplasmic ribosomal RNA of cultured sycamore cells (Acer pseudoplatanus L.) was investigated. Labelled 17-S and 26-S rRNA were prepared from cells that had been incubated with either [32P]phosphate, [Me-3H]methionine or [Me-14C]methionine. Ion-exchange resin chromatography of 0.3 M KOH or 1 M HCl hydrolysates and two-dimensional chromatographic analyses of phosphodiesterase plus phosphatase digests of 17-S and 26-S rRNA were performed. 17-S and 26-S rRNA contain 49 and 91 methyl groups per molecule, respectively. These values were verified in sevemral ways. The high degree of methylation of sycamore rRNA, particularly for the 26-S rRNA, contrasts with the situation in all other investigated organisms. Several methylated bases were identified. 7-Methylguanine and 5-methylcytosine both occur in 17-S and 26-S rRNA. N6-Methyladenine and N6,N6-dimethyladenine are restricted to the 17-S rRNA while 3-methyluracil and 1-methyladenine occur in the 26-S rRNA. One hypermodified uridine was also tentatively identified in the small rRNA. In 17-S rRNA, there is one copy of 7-methylguanine, N6-methyladenine and hypermodified uridine and two copies of N6,N6-dimethyladenine. 3-Methyluracil, 1-methyladenine and 5-methylcytosine occur twice, twice and three times, respectively, in 26-S rRNA. 7-Methylguanine and 5-methylcytosine are only in submolar amounts in the 26-S and 17-S rRNA, respectively. There are 40 +/- 2 and 83 +/- 3 2'-O-methylriboses per 17-S and 26-S rRNA molecule, respectively. In addition to the four 2'-O-methylnucleosides, one 2'-O-methylpseudouridine is present in the 17-S rRNA. Several lines of evidence argues for a non-random distribution of the methylriboses. In particular, one and seven Nm-Nm-Np structures occur in the 17-S and 26-S rRNA, respectively. The data are discussed comparatively with the methylation pattern of Escherichia coli, yeast and HeLa cell rRNA.

Methionine↗
PubMed1977

The occurrence of materials cross-reacting with anti-A and -B agglutinins in fruit or seed extracts of higher plants.

Fourteen species of higher plants were found to contain materials in their fruit or seed extracts which were heat stable, inhibitory for and capable of absorbing anti-H, -A and -B agglutinins and also lectins. The majority of species exhibiting a high grade of such cross-reactivity belonged to two genera, Viburnum of the Caprifoliaceae and Acer of the Aceraceae. Gel diffusion patterns indicated, however, that the A- and B-like activities of the Viburnum fruits were somewhat distinct serologically from blood group A and B substances of human origin.

ABO Blood-Group System↗
PubMed1975

Fungal growth and acid production during fermentation and refermentation of organic acid treated corn silages.

Chopped corn (35% dry matter) treated with either propionic, formic, 60% propionic plus 40% formic, or 80% propionic plus 20% acetic acids at 0, .5, 1, and 2%, was placed in polyethylene bags inside metal drums, and evacuated. During fermentation silages were sampled and temperatures determined. On day 40 of fermentation silages were placed in open containers at 25 C and were sampled during refermentation. All samples were analyzed for volatile and lactic acids, pH, and number and type of fungi. Lactate fermentation was totally inhibited at 2% addition of all acids, but formic acid was more effective than propionic acid at .5 and 1%. Acerate production was equally depressed by both propionic and formic additions. Heating, growth of fungi, and days until spoilage were delayed by all acid additions during refermentation, with propionic more effectivethan formic. The large increases in lactate and acetate of treated silages during refermentation reflect a protection of soluble sugars during fermentation and subsequent use by microbes after exposure to air. Silages treated with more than 1%propionic (as propionic or a mixture) did not increase in fungal colonies during refermentation. At initiation of fermentation yeasts werehigher than other fungi but decreases by day 40. During refermentation, yeasts again grew. Geotrichum comprised 35% on day 40 of refermentation but was lower at other times. Aspergillus proliferated during refermentation and few Penicillium were detected.

Acetates↗
PubMed1979

Light and electron microscopic investigation of in vitro starch synthesis in chromoplasts.

Chromoplasts having a globular inner structure in the petals of Forsythia suspensa can form starch grains in their stroma when incubated with glucose solution. The same result was obtained with chromoplasts, similar in structure, from Laburnum anagyroides and Ranunculus acer. Fibrillar chromoplasts in tepals of Lilium croceum are able to synthesize starch in vitro, not, however, from glucose but from glucose-1-phosphate. This starch differs from the above mentioned both in respect of electron microscopic structure and digestibility with alpha-amylase, a feature presumably caused by the relatively high activity of the branching (Q) enzyme. The substrate specificity of Lilium-starch synthesis can be explained by blocking of the phosphorylation of glucose in the cytoplasm, rather than by the selective permeability of the plasmalemma.

Microscopy, Electron↗
PubMed1979

Fusarium oxysporum endophthalmitis.

A 27-year-old man sustained a thorn injury to his left eye and a culture-proven Fusarium oxysporum endophthalmitis developed. This was successfully treated with a vitrectomy, intravitreal and intravenous amphotericin B, and oral flucytosine. The patient maintains 20/20 vision at this time in his left eye. We recommend combined therapy for this filamentous fungal infection.

Adult↗
PubMed1979

Pseudo-orbital apex syndrome.

A 48-year-old man had symptoms and signs of the orbital apex syndrome. All orbital and systemic studies were unrevealing . The computed tomoggraphy scan showed a cystic lesion external to the pons. The lesion proved to be a cholesteotoma originating in the peduncular fossa area, comprising the oculomotor nerve proximally and extending anteriorly in a finger-like projection to involve the ipsilateral optic nerve.

Cranial Nerve Neoplasms↗
PubMed1979

Ocular myasthenia gravis mimicking pseudointernuclear ophthalmoplegia and variable esotropia.

A 70-year-old man with known vascular disease, who had bilateral internuclear ophthalmoplegia, and an 18-month-old girl with a long-term variable esotropia culminating in a postinfectious oculopharyngeal neuropathy both responded with a positive edrophonium chloride (Tensilon) test, strongly suggesting the diagnosis of myasthenia gravis. Both subsequently received maintenance doses of neostigmine methylsulfate (Prostigmin).

Aged↗