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Results for “vegetative phase change”

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13 recordsLinked to original sources

PubMed2026

The DELAYED ABAXIAL TRICHOMES Helitron has dual functions in vegetative and pollen development in Arabidopsis thaliana.

Transposons drive genetic diversity and evolution by altering the genomic landscape over time. Here, we describe DELAYED ABAXIAL TRICHOMES (DAB), a Helitron/RC transposable element in Arabidopsis thaliana that has a role in vegetative phase change and gametogenesis. A genome-wide association study (GWAS) for the timing of abaxial trichome development (an adult leaf trait) in A. thaliana revealed a conserved haplotype of polymorphisms within DAB that delays abaxial trichome production. CRISPR-Cas9-induced deletions of DAB are gametophytic pollen-lethal, indicating that this locus is also required for pollen production. DAB produces 24-nucleotide siRNAs with sequence complementarity to genes involved in embryogenesis, gametogenesis, and seed development. DAB also impacts the expression of ARGONAUTE genes, genes involved in RNA-directed DNA methylation (RdDM), as well as genes in several key genetic pathways. This global effect on gene expression suggests that DAB may have functions beyond those identified in this study.

Arabidopsis↗

PubMed1977

[Neuropathology of Chagas' disease].

CNS involvement includes: 1) acute phase: scattered focal meningoencephalitic lesions, meningeal and cerebral edema, disseminated microgranulomas containing microgliocytes and situated in relation to cerebral blood vessels, and moderate cerebral fluid pleocytosis. Acute chagasic meningoencephalitis is always fatal, and does not become chronic, as occurres with the myocardial lesions; 2) chronic phase: tromboembolic phenomena due to the chronic myocarditis, and cerebral and cerebelar atrophy of obscure pathogenesis and without inflammatory changes. B) vegetative nervous system involvement includes: 1) acute phase: neuronal destruction, with neuronal loss of varying intensity; 2) chronic phase: visceral dilatation due to neuronal loss during the acute phase.

Autonomic Nervous System↗

PubMed1977

[Studies on cardio-circulatory effects of carpipramine. Results of a double-blind study (author's transl)].

For eight weeks 30 psychotic patients with a healthy cardiovascular system received 3 X 50 mg 1-[3-(10,11-dihydro=5H-dibenz[b,f]-azepin-5-yl]-propyl]-4-piperidiono-piperdine-4-carboxamide dihydrochloride-monohydrate (carpipramine) per day with a placebo phase of three weeks either previous to the medication of succeeding it. In addition there was a group of similar patients without any medication. From this study it was concluded that carpipramide has no depressive effect on the cardiovascular system. The differences in blood pressure and heart rate after the change from medication to placebo indicate a certain vegetative lability in this phase. In the ECG, no irregularities of the atrioventricular and intraventricular conduction and its repolarisation in form of a lengthening were observed; only the WPW-syndrome noticed with one patient might be related to the medication since it occurred at the end of the three weeks during which carpipramine had been administered.

Adult↗

PubMed1976

Biogenesis of mitochondrial membranes in Neurospora crassa during cellular differentiation: ultrastructural changes accompanying differentiation.

The ultrastructural characteristics of Neurospora cells during dedifferentiation and redifferentiation of conidiospores into vegetative cells have been determined. This germination process occurs between 2 and 5 h after inoculation; by 3-5 h, approximately 50% of the cells have germinated. The cells enter the exponential phase of dry-weight gain between 4 and 5 h after inoculation. Several unusual structures are observed in Neurospora cells during germination. Whorled structures are frequently seen in the cytoplasm during germination, and occasionally at other times. They appear to be derived from the cytoplasmic membrane. Whorled structures of different appearance were observed in the mitochondria between 2 and 4 h after inoculation. Their number was related to the level of metabolizable carbohydrate, and was higher in 15% glucose-than in 2% sucrose-supplemented medium, and very low in medium containing 15% mannitol, or 2% sucrose+13% 2-deoxyglucose, or no added carbohydrate. The mitochondrial inclusions were osmiophilic and could be removed by treatment with 90% aqueous acetone in the cold, indicating that they were composed at least in part of lipid. The strong dependence of the number of mitochondrial inclusions on time and on carbohydrate supplementation, suggests that there is a physiological basis for these structures and that they reflect changes occurring in the mitochondria at times significant to cellular differentiation.

Carbohydrate Metabolism↗

PubMed1977

[Diagnosis of formes frustes of a rheumatic lesion of the nervous system in children].

In 77,9 +/- 3,5% of the children with an active phase of rheumatic fever, developing with a prevalent lesion of the heart and joints, symptoms of animal and vegetative nervous system lesions were found. The neurological symptoms correlated with changes of the brain bioelectrical activity. The authors point to some dynamics of symptoms under the influence of anti-rheumatic treatment. Normalization of the brain bioelectrical activity, a regress of symptoms of the vegetative nervous system and muscular hypotonia are somewhat behind the clinical recovery. The existence of pathological activity on the EEG in children after an arrest of clinical symptoms of rheumatic fever may indicate to the possible subsequent development of chorea, the diencephalic syndrome, cerebrasthenic syndrome in these children.

Adolescent↗

PubMed2025

Molecular mechanisms and breeding strategies for heat tolerance in vegetable crops under global warming.

Extreme heat driven by climate change poses a catastrophic threat to global vegetable production, undermining nutritional security because of the heightened physiological sensitivity and succulent tissues of these crops. This review synthesizes the multistage impacts of heat stress across critical developmental phases-from germination to reproduction-emphasizing morphological impairments (such as leaf wilting and floral abortion) and physiological disruptions (including photosynthetic inhibition and oxidative damage). We systematically dissect thermotolerance mechanisms in vegetables, highlighting transcriptional reprogramming by HSFs, WRKY, and NAC transcription factors; chaperone-mediated proteostasis via HSPs; epigenetic remodeling; Ca2+-ROS signaling pathways; and the role of phase separation dynamics. Importantly, we propose six strategic pathways to develop heat-resilient vegetables: harnessing natural variation through pan-genome-driven allele mining; employing biotechnological interventions such as CRISPR-mediated editing and synthetic promoters; engineering multistress tolerance by targeting conserved 'core response' pathways; exploiting epigenetic memory to achieve transgenerational resilience; optimizing source-sink dynamics with ''Climate-Responsive Carbon Optimization; and applying plant growth regulators and nanotechnology to enhance thermotolerance. Together, these strategies chart a clear roadmap for climate-smart vegetable breeding and call for interdisciplinary collaboration to translate molecular discoveries into practical breeding approaches for sustainable food systems under escalating thermal extremes.

Journal Article↗

PubMed1979

Changes in cyclic AMP binding and protein kinase activities during growth and differentiation of Blastocladiella emersonii.

Multiple protein kinases in the water mould Blastocladiella emersonii are described. A cyclic AMP-independent protein kinase which prefentially phosphorylates casein remains unchanged during vegetative growth of the cells and in the two phases of differentiation: germination and sporulation. In contrast, cyclic AMP-dependent protein kinase activity and cyclic AMP binding components are induced during the sporulation.

Blastocladiella↗

PubMed1979

Changes in sporulation potential during the growth cycle of Bacillus subtilis.

The sporulation potential of Bacillus subtilis as a function of position in the cell cycle was determined by transferring cells from growth medium to sporulation medium at various times during growth. Growth was induced by incubating heat-activated spores in rich medium or by diluting stationary phase vegetative cultures with fresh growth medium. The results supported earlier observations that sporulation potential is cell cycle dependent. The rise in sporulation potential was studied by exposing cultures to the inhibitors of cell wall and protein synthesis, vancomycin and chloramphenicol. The delay in the appearance of the peak of sporulation potential caused by these inhibitors compared with the reported lack of effect of nalidixic acid, indicates that the appearance of sporulation potential requires synthesis of a macromolecular component other than deoxyribonucleic acid. The effect of nalidixic acid in preventing the decline of the sporulation potential was compared with the effect of high temperature on a mutant temperature sensitive for the initiation of DNA replication. It was found that prevention of chromosome completion with nalidixic acid maintained a high sporulation potential, whereas prevention of chromosome re-initiation in the temperature sensitive mutant did not affect the decline in sporulation potential as the cells enter stationary phase.

Bacillus subtilis↗

PubMed1977

Two polypeptides associated with the ribonucleic acid polymerase core of Bacillus subtilis during sporulation.

The ribonucleic acid (RNA) polymerase from log-phase and sporulating cells of Bacillus subtilis was analyzed to determine whether any structural changes occurred during sporulation. The elution pattern of RNA polymerase from a deoxyribonucleic acid (DNA)-cellulose column revealed that sporulating cells at stages III and IV contained a new RNA polymerase fraction in addition to the vegetative holoenzyme (alpha2betabeta'sigma). Stage III cells contained the vegetative holoenzyme and a new enzyme with the composition alpha2betabeta'delta1; the molecular weight of delta1 was 28,000. Stage IV cells contained the vegetative holoenzyme, the delta1-containing enzyme, and another enzyme with the composition alpha2betabeta'delta2. The delta2 factor had a molecular weight of around 20,000. The delta-containing enzymes have a higher affinity for the DNA-cellulose column and a higher specific activity on various templates than vegetative holoenzyme. The simultaneous appearance of these enzymes with vegetative holoenzymes in sporulating cells is consistent with the data found previously with DNA-RNA hybridization studies, which showed that sporulating cells contained both vegetative and sporulation messenger RNAs.

Bacillus subtilis↗

PubMed1979

Studies on the proton transport at system II in trypsin-treated spinach chloroplasts.

The proton transport coupled with the DCMU-insensitive oxygen evolution mediated by K3[Fe(CN)6] in trypsin-treated chloroplasts (Renger, G. (1976) FEBS Lett. 69, 225--230) has been investigated with the aid of the pH indicator bromcresol purple. It was found that (1) the proton uptake from the outer aqueous phase observed in normal chloroplasts is completely suppressed by mild trypsin treatment; (2) a rather slow proton release into the external phase is detected which is insensitive to DCMU; (3) in the presence of DCMU, the extent of the proton release depends on the incubation time with trypsin in a similar manner as the average oxygen yield per flash. The results are interpreted by the assumption, that: (i) the reduced primary electron acceptor of System II, X 320-, does not become protonated, and (ii) the external acidification is caused by a passive efflux of protons, which are released by the watersplitting enzyme system Y into the inner phase of the thylakoids. The pK value of X 320- in trypsinated chloroplasts is estimated to be below 4.5. A possible pK shift caused by a modification of the proteinaceous barrier, which earlier (Renger, G. (1976) Biochim. Biophys. Acta 440, 287--300) was postulated to cover up the primary electron acceptor X 320, is discussed. Furthermore, the watersplitting enzyme system Y is inferred to be sensitive to deletereous attack from the outer aqueous phase mainly by secondary structural effects. Trypsination does not change the direction of the proton release in system Y.

Chloroplasts↗

PubMed1978

[Tele-electrosubcorticogram study of reactions to vestibular stimulation in neurosurgical clinical practice].

In connection with stereotactic examinations and operations, mainly in certain forms of epilepsy, the electro-subcorticogram under, vestibular stimulations was recorded by telemetry. The amount of informat ion obtained was analysed by electronic data processing. A number of vegetative parameters and the electro-oculogram could be recorded at the same time. Regular bioelectric reaction of the desynchronisation type or of the oscillation depression type were found. In the presence of focal or generalised convulsions, a weakening of the epileptic discharges were observed under labyrinthine stimulation. Also the sense of rotation leads to special influences. The method is also of importance for the postoperative phase as it represents an adaptation of the requirements of modern living conditions (acute accelerations, breaking and changes in direction). Finally, information about the dominance of interfocal relations can also be obtained.

Electroencephalography↗

PubMed1975

Chemotaxis and binding of cyclic AMP in cellular slime molds.

To obtain more information about how cyclic AMP mediates cell aggregation as found in some species of the cellular slime molds, we determined the maximal binding activity of cyclic AMP in different species under various environmental conditions. The binding of cyclic AMP is limited to amoebae using this cyclic nucleotide as chemotactic agent. Maximal binding activity proved to coincide with a maximal chemotactic response and to be related to the length of the period between the vegetative and the aggregative phase. Of the species studied, Dictyostelium discoideum has the highest cellular density of cyclic AMP receptors and is the most sensitive to cyclic AMP as attractant. At 15 degrees C, aggregation begins later, chemotaxis takes effect over a greater distance, and the maximal binding activity is higher than 22 degrees C. The number of cyclic AMP receptors is independent of temperature. The delay in the onset of aggregation and the increased chemotactic response in darkness is not due to a change in the maximal binding activity. The binding of cyclic AMP and its inactivation is discussed in the light of cell aggregation.

Cell Aggregation↗

PubMed1978

Asymmetric transcription during post-germinative development of Bacillus subtilis spores.

The relative transcription from L and H strands of Bacillus subtilis DNA during consecutive stages of spore outgrowth was determined and compared to the transcription pattern during log-phase growth of vegetative cells. Pulses of [3H] uridine were administered during early, middle and late outgrowth phases of germination and the RNAs isolated. The asymmetry ratio of H/L as determined by hybridization at saturating RNA/DNA inputs showed a gradual decrease. During the period studied (10-90 and 90-160 min post-induction), about 50 and 35%, respectively, of the radioactive RNA consisted of ribosomal RNA transcripts. The decrease in the H/L asymmetry ratio was due predominantly to the appearance and accumulation of L strand transcripts and not to either changes in the quantity of H strand transcripts nor to fluctuation in the rate of rRNA synthesis.

Bacillus subtilis↗