Enhanced pyruvic acid yield in an osmotic stress-resistant mutant of Yarrowia lipolytica

BACKGROUND: Pyruvic acid (PA), a vital α-oxocarboxylic acid, plays an important role in energy and carbon metabolism. The oleaginous yeast Yarrowia lipolytica (Y. lipolytica) has considerable potential for the production of PA. An increased NaCl concentration reportedly increases the biomass and PA yield of Y. lipolytica. RESULTS: To increase the yield of PA, the NaCl-tolerant Y. lipolytica A4 mutant was produced using the atmospheric and room temperature plasma method of mutation. The A4 mutant showed growth on medium containing 160 g/L NaCl. The PA yield of the A4 mutant reached 97.2 g/L at 120 h (0.795 g/g glycerol) in a 20-L fermenter with glycerol as the sole carbon source, which was 28.9% higher than that of the parental strain. CONCLUSION: The PA yield from Y. lipolytica can be improved by increasing its NaCl tolerance.

Study on volatile components of Lonicerae Japonicae Flos in bud stage extended type / 中国中药杂志

Volatile components of Lonicerae Japonicae Flos in bud stage extended type Beihua 1 were determined by the headspace solid-phase micro-extraction, compared with traditional cultivar Damaohua. There are fifty-two volatile compounds were identified and the relative content of the volatiles was calculated by the area normalization method. Thirty-nine compounds were found in Beihua 1, whereas thirty-three components in Damaohua. Total twenty identical compounds existed in Beihua 1 and Damaohua. The contents of alcohols and hydrocarbons of Beihua 1 were higher significantly than that of Damaohua, while significantly lower than that of Damaohua in ketones content. Besides, twenty components were only detected in Beihua 1, such as methyl nicotinate, hexadecanoic acid, methyl ester,acetophenone, nonanoic acid.

Comparison of membrane current of vascular smooth muscle cells in brain artery of spontaneously hypertensive rats and Wistar rats / 中国应用生理学杂志

<p><b>OBJECTIVE</b>To investigate the difference in membrane current of vascular smooth muscle cells (VSMCs) in brain artery (BA) of spontaneously hypertensive rats (SHR) and Wistar rats.</p><p><b>METHODS</b>We compared the properties of spontaneous transient outward K+ currents (STOCs), the density and composition of current of VSMCs in BA of SHR and Wistar rats by whole-cell patch clamp technique.</p><p><b>RESULTS</b>(1) When the command voltage was 0, + 20, + 40 and + 60 mV respectively, the current densities of VSMCs in BA of SHR and Wistar rats were significant different (P < 0.01). (2) The whole-cell current of VSMCs was partly inhibited by 1 mmol/L4-AP (voltage-gated K+ channel blocker) or 1 mmol/L TEA (big conductance Ca(2+)-activated K+ channel blocker) respectively. (3) The frequency and amplitude of STOCs in SHR were faster and bigger than those in Wistar rats. 1 mmol/L TEA almostly inhibited the STOCs, but not by 4-AP.</p><p><b>CONCLUSION</b>These results suggest that the current densities of VSMCs in BA of SHR and Wistar rats are significant different, the outward current of VSMCs in BA of SHR and Wistar rats are composed by Kv and BK(Ca). SHR express more STOCs mediated by BK(Ca), than Wistar rats.</p>

The characteristics of resting membrane potential on smooth muscle cells and endothelial cells in guinea pigs cochlea spiral artery / 中国应用生理学杂志

<p><b>OBJECTIVE</b>A variety of inner ear disease is related to microcirculation disturbance of inner ear, but smooth muscle cells (SMC) and endothelial cells (EC) of the spiral modiolar artery (SMA), which is the main blood supply to the inner ear, physiological feature is not very clear.</p><p><b>METHODS</b>In this study, two-intracellular microelectrode recording technique and cell staining techniques to study the SMC and EC resting membrane potential characteristics and communication links between cells of SMA.</p><p><b>RESULTS</b>Study found that SMC and EC have high and low resting membrane potential state, two state of the resting membrane potential of cells to ACh and high K+ response is completely different. The different types of cells, EC-EC, SMC-SMC and SMC-EC, can simultaneously record by two-microelectrode, two cell resting membrane potential can also be a double-high RP, double-low RP and one high- and one low- RP. Experiment recorded in one high- and one low- RP are the SMC-EC types, and ECs initial membrane potential are high potential, SMCs membrane potential are low initial potential. The double-high and double-low RP can be SMC-SMC or EC-EC or SMC-EC types.</p><p><b>CONCLUSION</b>The results show that SMC and EC in the 0.3 - 0.5 mm range, similar type of cells have very good communication, can function together to maintain good and consistent, heterogeneous cell performance is more different.</p>

The distribution and mechanism of coronary arteriole cell resting membrane potential in guinea pigs / 中国应用生理学杂志

<p><b>OBJECTIVE</b>To investigate the distribution and mechanism of coronary arteriole (CA) cell resting membrane potential (RP) in guinea pigs.</p><p><b>METHODS</b>Cell RP was recorded by intracellular microelectrode in isolated guinea pig coronary arteriole (diameter < 100 microm).</p><p><b>RESULTS</b>(1) Experiments were carried out in 112 cells with a mean RP of (-65 +/- 4.2)mV, the distribution of coronary arteriole cell RP fitted by Gaussian function was bimodal, one peak was -43 mV termed high RP, the other was -74 mV termed low RP. 10 mmol/L K+ and 3 micromol/ L acetylcholine(ACh) induced hyperpolarization in high-RP cells with (-7.4 +/- 0.87) mV (n = 13) and (-15 +/- 1.24) mV (n = 16) respectively, and induced depolarization in low-RP cells with (9.6 +/- 1.2) mV (n = 23) and (8.7 +/- 0.69) mV (n = 15) respectively. (2) The inward rectifier K+ channel (K(ir)) blocker Ba2+ caused concentration-dependent depolarization in low-RP cells with an EC50 of 120 micromol/L 100 micromol/L Ba2+ or higher could shift low-RP cells to high-RP state, the response of these cells to high K+ and ACh became a hyperpolarization.</p><p><b>CONCLUSION</b>The distribution of coronary vascular cell RP is bimodal, high K+ and ACh induce different responses in low and high RP cells. The two RP states are exchangeable mainly due to all-or-none conductance changes of K(ir).</p>

Acute hypoxia increases outward current and decreases gap junction of VSMCs in guinea-pig anterior inferior cerebellar artery / 生理学报

The aim of the present study was to investigate the effects of acute hypoxia on the electrophysiological properties of vascular smooth muscle cells (VSMCs) in arteriole. Guinea-pig anterior inferior cerebellar artery (AICA) segments were isolated, and outer layer connective tissue was removed by collagenase A digestion and microforceps. By perfusion with physical saline solution containing no glucose and low oxygen, VSMC model of acute hypoxia was established. The model was studied by whole-cell patch clamp recording technique. Results were shown as below: (1) Acute hypoxia induced an outward current with amplitude of (36.4 ± 9.2) pA at holding potential of -40 mV, and the rest potential (RP) of the VSMCs was hyperpolarized from (-33.2 ± 1.9) mV to (-38.4 ± 1.5) mV. Acute hypoxia increased the outward current of VSMCs in a voltage-dependent manner, this enhancing effect being more pronounced at potentials ranging from 0 to +40 mV. The whole-cell membrane current of VSMCs induced by step command (+40 mV) increased from (650 ± 113) pA to (1 900 ± 197) pA. In the presence of 1 mmol/L tetraethylammonium (TEA), the enhancement of the VSMC membrane current by acute hypoxia was significantly reduced. (2) Acute hypoxia increased the membrane resistance (R(input)) of the VSMCs in AICA from (234 ± 63) MΩ to (1 211 ± 201) MΩ, and decreased the membrane capacitance (C(input)) from (279.3 ± 83.2) pF to (25.4 ± 1.9) pF. In the presence of 30 μmol/L 18β-glycyrrhetinic acid (18βGA) and 10 mmol/L TEA, the effects of acute hypoxia on the membrane current of VSMCs were nearly abolished. These results suggest that acute hypoxia causes vascular hyperpolarization and vasodilation, possibly by activating big conductance Ca(2+)-activated K(+) channels (BK(Ca)) of the VSMCs, and inhibits gap junctions between VSMCs, thus improving microcirculation and localizing the hypoxia-induced damage.

18β-glycyrrhetinic acid inhibits outward current of vascular smooth muscle cells of arterioles / 生理学报

The aim of the present study was to investigate the effect of 18β-glycyrrhetinic acid (18βGA) on the membrane current of vascular smooth muscle cells (VSMCs) in arteriole. Guinea pig anterior inferior cerebellar artery (AICA) and mesenteric artery (MA) were isolated, and single VSMCs were harvested using digestion with papain and collagenase IA. Outward currents of the VSMCs were recorded by whole-cell patch clamp technique. Results were shown as below: (1) 1 mmol/L 4-AP and 1 mmol/L TEA both could partially inhibit the whole-cell current of VSMCs in arterioles. (2) 18βGA inhibited the outward current of VSMCs in a concentration-dependent manner. The inhibitory rates of 10, 30 and 100 μmol/L 18βGA on the membrane current of VSMCs (+40 mV) were (25.3 ± 7.1)%, (43.1 ± 10.4)% and (68.4 ± 3.9)% respectively in AICA, and (13.2 ± 5.6)%, (34.2 ± 4.0)% and (59.3 ± 7.3)% respectively in MA. There was no significant difference between the inhibitory effects of 18βGA on AICA and MA. 18βGA also inhibited the outward current of VSMCs in a voltage-dependent manner. 18βGA induced a more pronounced inhibition of the outward current from 0 to +40 mV, especially at +40 mV. (3) With the pretreatment of 10 mmol/L TEA, the inhibitory effect of 18βGA on the membrane current of VSMCs was significantly abolished. These results suggest that the outward current of VSMCs in arterioles is mediated by voltage-dependent K(+) channels (K(v)) and big conductance calcium-activated K(+) channels (BK(Ca)), which can be inhibited by 18βGA in concentration- and voltage-dependent way.

Changes of GABA-activated currents in isolated dorsal root ganglion neurons in rats with neuropathic pain / 中国应用生理学杂志

<p><b>OBJECTIVE</b>To investigate the changes of GABA-activated currents in isolated dorsal root ganglion neurons in rats with neuropathic pain.</p><p><b>METHODS</b>The neuropathic pain model was established by chronic constriction injury (CCI) 7 days before electrophysiological-recording. The rat DRG neurons were enzymatically dissociated. Whole-cell patch clamp technique was used to record GABA-activated currents. The changes of currents of injured side and opposite side were expected to compare with control group.</p><p><b>RESULTS</b>(1) The currents of injured side of CCI group were notablely decreased compared with control group (GABA concentration, 0.1-1000 micromol/L). (2) By the contrast, opposite side currents of CCI group increased significantly compared with those in injured side and control group (GABA concentration, 0.01-1000 micromol/L).</p><p><b>CONCLUSION</b>The data indicates that the chronic constriction injury change both the function of GABAA receptors of injury side and opposite side. The decrease of pre-synaptic inhibition of GABA may be the possible reason of neuropathic pain.</p>