[Production and several physiologic properties of Rhodosporidium diobovatum mutants. II. Physiologic properties of the mutants].
Explore the source record for details and available documents.
Carotenoids↗
SEARCH · PubMed Health
Results for “physiological property”
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
The physiological properties of amine-containing neurones in the lobster nervous system.
1. Our previous studies have shown that octopamine and serotonin are found associated with a system of neurones in the connective tissue sheath of the second roots of lobster thoracic ganglia. To try to understand the mechanism of activation of these neurones, we undertook an examination of their general physiological properties. 2. All of the neurones receive excitatory synaptic input that has a cholinergic pharmacology, which suggests that it may be from sensory neurones. A very limited number of cells, possibly one, provdes the total synaptic input to all the cells in the roots of the second and third thoracic segments. 3. The cells within one root are electronically coupled to each other. The extent of coupling varies widely between cells; on occasion the coupling is sufficiently tight for action potentials originating in one cell to trigger action potentials in the neighbouring cell. 4. The majority of the cells show no spontaneous activity at temperatures below 14 degrees C, but become spontaneously active above that temperature. Cells cycle reversibly from silent to continuously active to bursting and back as the temperature is increased and decreased. 5. Octopamine and serotonin both inhibit the bursting activity. The octopamine response is blocked by phentolamine but not by propranolol, while the inhibitory action of serotonin is unaffected by either of these drugs. The amine-inhibition of the firing could be an autoregulatory mechanism for cell activity. 6. The physiological properties described in this paper suggest that the widely dispersed amine-containing neurones in lobsters behave like a neurosecretory organ in terms of their mechanism of activation.
Action Potentials↗
Inactivation of Aspergillus flavus spores by dielectric barrier discharge cold plasma: Kinetics, physiological properties and proteomic analysis.
A. flavus, as a pathogen, poses a grave threat to both human and livestock health, significantly influencing agricultural production as well. This study aimed to investigate the inactivation effect and mechanism of dielectric barrier discharge cold plasma (DBD-CP) on A. flavus spores. The results exhibited that DBD-CP effectively inactivated A. flavus spores by the Weibull + Tail model. Furthermore, the physiological and proteomic analysis revealed that DBD-CP destructed cell wall and membrane integrity, causing cellular protein leakage and increasing membrane penetration of ROS generated from DBD-CP. Although intracellular ROS was excessively accumulated, the protein levels and activities of SOD and CAT were decreased, indicating that intracellular redox homeostasis was disrupted by DBD-CP. Subsequently, DBD-CP treatment induced cellular protein oxidation and changed protein structures, resulting in unstable protein structures. Meanwhile, protein synthesis and degradation in A. flavus spores were disturbed by inhibiting ribosome biogenesis, initiation process and NEDD8-mediated UPS, which did not compensate for the loss of protein caused by oxidative damage and leakage, leading to A. flavus spore inactivation. Besides, DBD-CP could attenuate A. flavus virulence by downregulating hydrolytic enzymes and CFEM-related proteins. This study provides novel insight into the inactivation mechanism of DBD-CP against A. flavus spores, which establishes a basis for the application of DBD-CP in controlling pathogenic fungi contamination in grains and crops, promoting the development of DBD-CP in food and agricultural decontamination.
Spores, Fungal↗
[Morphological and physiological properties of Phoma tracheiphila (mal secco) (author's transl)].
The morphological and physiological characteristics of Phoma tracheiphila, the cause of "Mal Secco" in Mediterranian lemons is discussed. The structure and the characteristics of the spore, mycelium and pigment of this fungus were investigated in liquid and solid media. The growth rate was examined in different media with different pH by dry weight determination. The growth curve of P. tracheiphila was first studied in YPG, (pH 5.6) medium in the stationary and shaking culture conditions. During the course of these studies the microscobic observations and measurements were recorded. The results established that in further studies, it will be necessary to incubate P. tracheiphila at least 5 days for its growth. The optimal pH and temperature scale were found between 5.5--6.0 and 20--25 degrees C respectively.
Citrus↗
The relationship of conduction velocity to other physiological properties of the cat's horizontal canal neurons.
The conduction velocity and other physiological characteristics of the first order horizontal canal afferents were studied in 24 anesthesized cats. From their spontaneous discharge patterns, neurons were classified into three groups: regular, intermediate and irregular; The irregular units tended to have a low resting rate, high sensitivity to angular acceleration, frequently exhibited adaptation during prolonged acceleration, and showed a short latency from the time of electric stimulation of the labyrinth to recording the action potential near Scarpa's ganglion. The regular units tended to have a high resting discharge rate, low sensitivity, were mostly non-adapting, and showed longer latency to electric stimulation. The intermediate neurons had a mixed character of regular and irregular units. Based on the very short conduction times (mean 0.34 msec) and the work of Moxon (1971), we conclude the locus of activation of electrical stimulation is neural rather than the receptor cells. Since the latency is due predominantly to conduction in the first order axon, and since there is a direct linear relation between conduction velocity and fiber diameter in the medullated nerve fibers, it is possible to speculate that the regular cells have thin fibers which innervate the slope of the crista, the irregular neurons have thick fibers which innervate the summit of the crista, and the intermediate units have medium caliber fibers which innervate both the slope and summit of the crista ampullaris.
Action Potentials↗
[Study of the relationship between the trace element content and the physiological properties of Salmonella typhi during submerged cultivation].
The content of trace elements in the cells served as one of the characteristics of physiological condition of the population. The character of the changes in the trace elements content depending on the rate of the microbial multiplication pointed to the importance of the mineral sources of nutrition for the development of the cells analyzed.
Antigens, Bacterial↗
The morphological and physiological properties of a regenerating synapse in the C.N.S. of the leech.
Regeneration of an electrical synapse between particular interneurons in the medicinal leech was traced physiologically and morphologically using intracellular recording the horseradish peroxidase (HRP) injection. The synapse between S-cell interneurons lies in the connective midway between segmental ganglia, so crushing near one ganglion severs only one S-cell's axon. The severed distal stump remains connected to the adjacent uninjured S-cell and continues for weeks to conduct impulses. The injured cell regenerates, while its uninjured "target" neuron in the next ganglion does not grow. After the sprouts of the regenerating neuron cross the crush, one or a few branches grow along the surviving distal stump toward the original synapse. After about one month when the region of original synapse has been reached, regenerating neurons form electrical junctions and stop growing. Thereafter electrical coupling improves in stages. Within two months the regenerated neuron attains full caliber, the stump degenerates and function is normal. In some instances within days or weeks of crushing, the regenerating neuron forms a basket of synapses upon its severed distal stump and then continues growing to synapse with the target. When this occurs, electrical coupling and subsequent impulse transmission between S-cells rapidly resumes. These experiments indicated that the regenerating neuron is guided to its proper synaptic target by recognizing and following its severed distal stump. Sometimes the distal stump itself becomes an intermediate synaptic target.
Animals↗
The physiologic properties and therapeutic potential of coherin.
Coherin, a peptide isolated from the bovine neurohypophysis, has been shown to be an effective therapeutic agent in post-gastric surgery physiologic obstruction and regional ileitis. Of twenty-four patients with post-gastric surgery physiologic obstruction, coherin relieved symptoms in twenty-three, a 96 per cent efficacy rate. The efficacy of coherin with ileitis was based on the fact that ten of twenty-seven patients treated have required coherin on a continuing basis to stay functional. These patients have requested coherin treatment for an average of five years each, and have each on multiple occasions tried to discontinue coherin treatment with prompt return of symptoms and cessation of symptoms when coherin was reinstituted. All of the ileitis patients had previously failed to respond to standard and usual medical treatment.
Animals↗
Influence of genetic and physiological properties of the host cell on the cytopathic expression of herpes simplex virus.
Two plaque morphology variants, a cell aggregating variant and a syncytial variant, were isolated from MDBK cells infected with the MP mutant of herpes simplex virus, type 1. The variants differed in the polypeptides produced in infected MDBK cells. The properties of the variants were stable on passage in cells and both variants produced only syncytia in KB and Hep-2 cells. The physiological state of MDBK cells influenced the cytopathological expression of the infecting virus, so that, under certain conditions, each variant could shift from one type of plaque morphology to the other. However, attempts to correlate this plaque morphology shift with a difference in the glycopolypeptides synthesized in the infected cells were unsuccessful.
Animals↗
Physiological properties of muscle spindles in dorsal neck muscles of the cat.
1. Single-fiber recording was used to examine the properties of 107 spindle endings in cat biventer cervicis (BC) and complexus (CM) muscles. Responses of receptors were examined following muscle contraction and ramp and hold stretch. Twenty-two endings in splenius (SP) were also examined, but their responses could not be quantitated because the anatomy of SP prevented the application of appropriate stretches. 2. Conduction velocitites of spindle afferents ranged from 13 to 90 m/s. Endings with primary response patterns usually had faster conduction velocities than secondary endings, but there was overlap in the conduction velocity ranges of the two subgroups. 3. Most neck spindle afferents could be classified as either primary or secondary by a constellation of physiological criteria including dynamic response pattern, dynamic index, and variability of resting discharge frequency. However, 22 of 107 endings from BC and CM had responses with characteristics intermediate between primary and secondary responses. The possible sources of these characteristics are discussed. 4. Despite the similarity in properties between spindles of different neck muscles, the length sensitivities of CM spindles were high compared to those of BC spindles. CM spindles showed length-related modulation of firing frequency over a more restricted range of initial muscle lengths than did BC spindles. 5. Eight Golgi tendon organs (GTO) were identified by their characteristics responses. Conduction velocities obtained for five GTO afferent nerves ranged from 50 to 67 m/s. Recordings were also made from receptros in deep muscles surrounding the vertebrae. These receptors had properties characteristic of muscle spindles.
Adaptation, Physiological↗
Physiological properties of vertebrate nerve cells in tissue culture.
Vertebrate neurons in tissue culture are providing us with a new model system for studying the complex events which occur during neuronal differentiation, synaptogenesis, and neural network formation. It is already apparent that dissociated embryo neurons are capable of differentiating both morphologically and physiologically along predetermined lines in the absence of external influences. These neurons can form new connections with one another but retain some specificity in their selections. Both simple and complex neural networks can be seen. At the present time, the development of the invitro model system is just being explored. The potential value of a system of this kind at a variety of investigative levels should be appreciated. Questions of a fundamental nature in neurobiology, such as how synapses form, what rules govern such interaction, how cells recognize one another, and the nature of the basic two-, three-, or four-cell circuits that comprise the more complex neurons tissue can be approached with this system. Studies of the neurons and synapses themselves can lead to a more basic understanding of vertebrate nervous system functioning. The development of certain pathophysiological processes and the effects of neuroactive drugs on vertebrate neurons may be studied at the cellular level. Finally, the basic mechanism of some genetic abnormalities which produce abnormal nervous structure and function may be more easily determined in a simplified in vitro model than in the intact central nervous system. The value of any model is not inherent in the elegance of the model itseld, but only in its ability to suggest answers to fundamental questions about the system being modeled. Many fundamental questions about brain mechanisms in mental retardation remain unanswered. Perhaps some day the model of nerve cells in tissue culture will bring us closer to the answers to these questions.
Animals↗
Physiological properties of dissociated muscle fibres obtained from innervated and denervated adult rat muscle.
1. Adult rat flexor digitorum brevis muscles were dissociated by treatment with collagenase and trituration. Several hundred isolated fibres were obtained from each muscle. 2. Most isolated fibres appeared to be intact as judged by some morphological and physiological criteria, although resting membrane potentials were about -60 mV, which is somewhat lower than normal. 3. A small percentage of the muscle fibres were branched. 4. Acetylcholine sensitivity was measured iontophoretically. The sensitivity fell abruptly outside the margin of the end-plate. Extrajunctional sensitivty was detected on all fibres, and declined smoothly away from the end-plate to an undetectable level over a distance of about 200 micron. On a few fibres, ACh sensitivity was mapped circumferentially from the end-plate. It appeared to decline with distance in a manner similar to the longitudinal sensitivity gradient. 5. Fibres dissociated from muscles denervated a week earlier were sensitive to ACh everywhere on their surfaces.
Acetylcholine↗
Structure of the surface of spores and morphological-physiological properties of individual strains of Bacillus megaterium.
The structure of the surface of spores of 10 strains of Bacillus megaterium was investigated by the method of carbon replicas. They were separated into three groups according to the peculiarities of the structural organization of the surface of the spores. The combination of other morphological and physiological-biochemical characteristics of these strains was characteristic of the species Bac. megaterium. Strains with differences in the structure of the spore surface also showed similarities in other peculiarities of carbohydrate and nitrogen metabolism studied in the work, as well as in the primary structure of DNA. The date obtained lead to the conclusion that structural differences in the surface of the spores cannot be considered a sufficient basis for isolating the bacteria studied into separate taxonomic groups.
Bacillus megaterium↗
Degenerating nerve fiber products do not alter physiological properties of adjacent innervated skeletal muscle fibers.
Partial denervation of rat extensor digitorum longus and soleus muscles resulted in the appearance of denervated and innervated surface muscle fibers lying adjacent to one another. The denervated muscle fibers showed the typical signs of denervation while the innervated muscle fibers were similar to those of control muscles. We conclude that denervated fibers do not induce substantial physiological changes in adjacent innervated muscle fibers.
Action Potentials↗
The endosymbionts of Glossina morsitans and G. palpalis: cultivation experiments and some physiological properties.
Pyruvate, malate, and succinate are the main substrates for bacteroid respiration; oxygen uptake can be inhibited by rotenone and antimycin A, but not by cyanide. The symbionts displayed limited growth and survival for over 80 days in a medium with succinate and pyruvate as main substrates, and supplemented with nucleotides. It was not possible to cultivate the endosymbionts of G. morsitans and G. palpalis intracellularly in cell cultures of the tsetse fly or of vertebrates. A high attraction between cells and symbionts was observed in these systems; about 10% of all bacteroids were incorporatedby the cells but they were lysed and digested within 48 h.
Animals↗
Anatomical and physiological properties of ipsilaterally projecting spinothalamic neurons in the second cervical segment of the cat's spinal cord.
Anatomical and electrophysiological methods were used to investigate the projections and response properties of neurons in the second cervical (C2) spinal segment of the cat giving origin to a previously undescribed projection to the ipsilateral thalamus. The method of retrograde axonal transport of horseradish peroxidase (HRP) was used to identify neurons in C2 giving rise to thalamic projections. Following large (3.0 microliter) thalamic HRP injections, a large number of labeled neurons was observed in lateral laminae VII-VIII of C2 ipsilateral to the injections. They occurred as small clusters of cells along the longitudinal axis of C2. Labeled neurons were also observed contralaterally in the lateral cervical nucleus, dorsal horn (especially medial lamina VI), and loosely distributed in the ventral horn. The ipsilaterally projecting neurons were also labeled following small (0.2--0.5 microliter) HRP injections restricted to individual spinothalamic terminal zones (intralaminar nuclei, ventrobasal complex-nucleus ventralis lateralis border zone, medial division of the posterior nuclei), indicating that as a group they project widely throughout the thalamus. Single unit recording methods were used to obtain complementary information on the functional properties of these neurons. The antidromic stimulation method was applied to identify units in C2 projecting to the ipsilateral thalamus in anesthetized, paralyzed cats. Three categories of ipsilaterally projecting C2 units were identified: (1) units not driven by any type of natural stimulation; (2) units having large cutaneous receptive fields (RFs) and wide dynamic response ranges ("widefield"), and (3) units with smaller RFs and varied properties ("other"). Widefield units with bilaterally symmetrical and asymmetrical RFs were observed. Co-stimulation of different portions of an excitatory RF produced summation of the unit response. Inhibitory RF components were identified in one-third of the widefield units. Unit recordings after spinal tract lesions revealed that the afferent input passed via the ipsilateral lateral and/or ventral funiculi. Widefield unit responses to somatosensory stimuli could be inhibited by dorsal column conditioning stimulation. Several "other" units resembled widefield units, while a second group had small RFs restricted to the C2 dermatome. Possible functional roles of the projecting C2 neurons in somatosensory and non-specific systems are discussed.
Animals↗
Physiological properties of the penis retractor muscle of Aplysia.
The properties of the penis retractor muscle of Aplysia have been studied using intracellular, sucrose gap and tension recording. The fibers are of the invertebrate smooth muscle type and exhibit slow contractions which occur spontaneously or in response to stretch in isolated preparations. Individual muscle fibers are innervated by excitatory and inhibitory axons. A variety of sizes of excitatory and inhibitory junctional potentials can be recorded from them. The innervation is probably diffuse and functionally polyneuronal. The fibers are electrically coupled, permeable to potassium and chloride at rest, and exhibit no overshooting active responses. The muscle shows graded responses of depolarization and contraction proportional to strength of nerve stimulation. Facilitation and depression of junctional potentials are seen with various frequencies of nerve stimulation. Post-tetanic potentiation occurs with nerve stimulation at frequencies from 2 to 50 Hz and is suppressed in the presence of increased extracellular calcium concentrations.
Animals↗
Physiological properties of afferents and synaptic reorganization in the rat cerebellum degranulated by postnatal X-irradiation.
Elimination of most granule, basket, and stellate interneurons in the rat cerebellum was achieved by repeated doses of low level x-irradiation applied during the first two weeks of postnatal life. Electrical stimulation of the brain stem and peripheral limbs was employed to investigate the properties of afferent cerebellar pathways and the nature of the reorganized neuronal synaptic circuitry in the degranulated cerebellum of the adult. Direct contacts of mossy fibers on Purkinje cells were indicated by short latency, single spike responses: 1.9 msec from the lateral reticular nucleus of brain stem and 5.4 msec from ipsilpateral forelimb. These were shorter than in normal rats by 0.9 and 2.1 msec, respectively. The topography of projections from peripheral stimulation was approximately normal. Mossy fiber responses followed stimulation at up to 20/sec, whereas climbing fiber pathways fatigued at 10/sec. The latency of climbing fiber input to peripheral limb stimulation in x-irradiated cerebellum was 23 +/- 8 (SD) msec. In x-irradiated rats, the climbing fiber pathways evoked highly variable extracellular burst responses and intracellular EPSPs of different, discrete sizes. These variable responses suggest that multiple climbing fibers contact single Purkinje cells. We conclude that each type of afferent retains identifying characteristics of transmission. However, rules for synaptic specification appear to break down so that: (1) abnormal classes of neurons develop synaptic connections, i.e., mossy fibers to Purkinje cells; (2) incorrect numbers of neurons share postsynaptic targets, i.e., more than one climbing fiber to a Purkinje cell; and (3) inhibitory synaptic actions may be carried out in the absence of the major inhibitory interneurons, i.e., Purkinje cell collaterals may be effective in lieu of basket and stellate cells.
Action Potentials↗