Upgrading CO2 to sustainable aromatics via perovskite-mediated tandem catalysis.

The directional transformation of carbon dioxide (CO2) with renewable hydrogen into specific carbon-heavy products (C6+) of high value presents a sustainable route for net-zero chemical manufacture. However, it is still challenging to simultaneously achieve high activity and selectivity due to the unbalanced CO2 hydrogenation and C-C coupling rates on complementary active sites in a bifunctional catalyst, thus causing unexpected secondary reaction. Here we report LaFeO3 perovskite-mediated directional tandem conversion of CO2 towards heavy aromatics with high CO2 conversion (> 60%), exceptional aromatics selectivity among hydrocarbons (> 85%), and no obvious deactivation for 1000 hours. This is enabled by disentangling the CO2 hydrogenation domain from the C-C coupling domain in the tandem system for Iron-based catalyst. Unlike other active Fe oxides showing wide hydrocarbon product distribution due to carbide formation, LaFeO3 by design is endowed with superior resistance to carburization, therefore inhibiting uncontrolled C-C coupling on oxide and isolating aromatics formation in the zeolite. In-situ spectroscopic evidence and theoretical calculations reveal an oxygenate-rich surface chemistry of LaFeO3, that easily escape from the oxide surface for further precise C-C coupling inside zeolites, thus steering CO2-HCOOH/H2CO-Aromatics reaction pathway to enable a high yield of aromatics.

Clinical practice guideline for transurethral plasmakinetic resection of prostate for benign prostatic hyperplasia (2021 Edition).

Benign prostatic hyperplasia (BPH) is highly prevalent among older men, impacting on their quality of life, sexual function, and genitourinary health, and has become an important global burden of disease. Transurethral plasmakinetic resection of prostate (TUPKP) is one of the foremost surgical procedures for the treatment of BPH. It has become well established in clinical practice with good efficacy and safety. In 2018, we issued the guideline "2018 Standard Edition". However much new direct evidence has now emerged and this may change some of previous recommendations. The time is ripe to develop new evidence-based guidelines, so we formed a working group of clinical experts and methodologists. The steering group members posed 31 questions relevant to the management of TUPKP for BPH covering the following areas: questions relevant to the perioperative period (preoperative, intraoperative, and postoperative) of TUPKP in the treatment of BPH, postoperative complications and the level of surgeons' surgical skill. We searched the literature for direct evidence on the management of TUPKP for BPH, and assessed its certainty generated recommendations using the grade criteria by the European Association of Urology. Recommendations were either strong or weak, or in the form of an ungraded consensus-based statement. Finally, we issued 36 statements. Among them, 23 carried strong recommendations, and 13 carried weak recommendations for the stated procedure. They covered questions relevant to the aforementioned three areas. The preoperative period for TUPKP in the treatment of BPH included indications and contraindications for TUPKP, precautions for preoperative preparation in patients with renal impairment and urinary tract infection due to urinary retention, and preoperative prophylactic use of antibiotics. Questions relevant to the intraoperative period incorporated surgical operation techniques and prevention and management of bladder explosion. The application to different populations incorporating the efficacy and safety of TUPKP in the treatment of normal volume (< 80 ml) and large-volume (≥ 80 ml) BPH compared with transurethral urethral resection prostate, transurethral plasmakinetic enucleation of prostate and open prostatectomy; the efficacy and safety of TUPKP in high-risk populations and among people taking anticoagulant (antithrombotic) drugs. Questions relevant to the postoperative period incorporated the time and speed of flushing, the time indwelling catheters are needed, principles of postoperative therapeutic use of antibiotics, follow-up time and follow-up content. Questions related to complications incorporated types of complications and their incidence, postoperative leukocyturia, the treatment measures for the perforation and extravasation of the capsule, transurethral resection syndrome, postoperative bleeding, urinary catheter blockage, bladder spasm, overactive bladder, urinary incontinence, urethral stricture, rectal injury during surgery, postoperative erectile dysfunction and retrograde ejaculation. Final questions were related to surgeons' skills when performing TUPKP for the treatment of BPH. We hope these recommendations can help support healthcare workers caring for patients having TUPKP for the treatment of BPH.

Efficacy and Safety of Mulberry Twig Alkaloids Tablet for Treatment of Type 2 Diabetes: A Randomized, Double-Blind, Placebo-Controlled Multicenter Clinical Study.

OBJECTIVE: To assess the efficacy and safety of mulberry twig alkaloids (Sangzhi alkaloids, SZ-A) for treatment of type 2 diabetes in a randomized, double-blind, placebo-controlled multicenter clinical trial. METHODS: A total of 200 patients were randomized to receive SZ-A (n=100) or placebo (n=100) for 16 weeks. The data analysis system for electronic data capture clinical trial central randomization system was used for randomization and dispensing of drugs. The primary outcome was the change in glycosylated hemoglobin (HbA1c) level. The secondary outcome included the proportions of cases with HbA1c <7.0% and HbA1c <6.5%, fasting blood glucose (FBG), postprandial blood glucose (PBG), area under curve for the PBG (AUC0-2h), body weight, and body mass index (BMI). Adverse events (AEs), severe adverse events (SAEs), treatment-related adverse events (TAEs), gastrointestinal disorders (GDs), blood pressure, routine blood tests, and liver and kidney function were monitored. RESULTS: Compared with baseline, the change of HbA1c at week 16 was -0.80% (95% CI: -0.98% to -0.62%) and -0.09% (95% CI: -0.27% to 0.09%) in SZ-A group and placebo group, respectively. The proportion of patients with HbA1c <7% and <6.5% was higher in the SZ-A group than in the placebo group (46.8% vs. 21.6% and 29.9% vs. 10.8%). The observed values and changes in FBG, 1 h-PBG, 2 h-PBG, and AUC0-2h differed significantly between groups (P<0.001), but differences were not significant in body weight and BMI (P>0.05). The incidence rates of AEs, TAEs, and GDs differed significantly between groups (P=0.010, P=0.005, and P=0.006, respectively), whereas the incidence rates of SAEs showed no significant differences between groups (P=1.000). CONCLUSION: SZ-A are effective and safe for treatment of type 2 diabetes. The protocol was registered in http://www.chictr.org.cn/showproj.aspx?proj=60117 (ChiCTR2000038550).

Efficacy of quercetin, oleanolic acid, icariin on apoptosis and mitogen-activated protein kinases signaling pathways in hippocampal neurons of Sprague-Dawley rats cultured with high glucose medium.

OBJECTIVE: To investigate the effect of quercetin, oleanolic acid, icariin and their compatibility on the apoptosis of hippocampal neurons of Sprague-Dawley (SD) rats cultured with high glucose medium and the possible mechanism. METHODS: The extracts were purchased from China Food and Drug Control Institute and Sellect. Hippocampus was obtained from newborn 24 h SD rats. After culturing the hippocampus in different medium for 72 h, flow cytometry was used to detect the apoptosis of hippocampal neurons, and Western blot was utilized to test the expressions of p-p38, p38, p-c-Jun N-terminal kinase (JNK) and JNK. RESULTS: Compared with the control group (CG), the neuronal apoptosis rate and the ratios of p-p38/p38 and p-JNK/JNK were significantly increased in the high glucose group (GG) (P < 0.01); Compared with the GG, the apoptosis rate and the ratios of p-p38/p38 and p-JNK/JNK were significantly decreased in other drug groups (P < 0.01); Compared with the monomer groups respectively, the apoptosis rate and the ratios of p-p38/p38 and p-JNK/JNK in the two-drug groups and the three-drug group all decreased (P < 0.01); Compared with the two-drug groups, the neuronal apoptosis rate and the ratio of p-JNK/JNK of the three-drug group decreased (P < 0.05). CONCLUSION: Under the condition of high glucose, the quercetin, oleanolic acid and icariin can alleviate the apoptosis of hippocampus neurons, reduce the phosphorylation of p38 and JNK in p38 mitogen-activated protein kinases and JNK signaling pathway. And the efficacy of the three drugs in combination with each other can be strengthened.

Berberine alleviates oxidative stress in rats with osteoporosis through receptor activator of NF-kB/receptor activator of NF-kB ligand/osteoprotegerin (RANK/RANKL/OPG) pathway.

Previous studies suggested that oxidative stress is related to the onset and development of osteoporosis. Moreover, it was demonstrated that berberine has a protective effect against oxidative stress-induced injuries. In this study, we aimed to investigate the effect and mechanism of action of berberine on rats with induced osteoporosis. Sixty 8-week-old female Wistar rats were randomly divided into the following 6 groups: control saline-treated, osteoporosis saline-treated, 3 osteoporosis berberine-treated groups (Ber 5, 10, and 20 mg/kg/body weight, respectively), and osteoporosis alendronate-treated (ALD) group. Osteoporosis was induced by bilateral ovariectomy. All treatments were performed for 8 weeks. The bone mineral density (BMD), serum alkaline phosphatase (ALP), osteocalcin, calcium, phosphorus, superoxide dismutase (SOD), methylenedioxyamphetamine (MDA), and glutathione peroxidase (GSH-Px) level was determined in the rat femur tissue. The gene and protein expression of osteoprotegerin (OPG) and receptor activator of nuclear factor kappa-B ligand (RANKL) was analyzed by quantitative reverse transcription PCR and Western blot, respectively. The BMD, SOD and GSH⁃Px levels, and the expression of OPG were significantly lower in osteoporosis compared to control group (all p < 0.05). The serum levels of osteocalcin, ALP, and MDA, and the expression of RANKL were significantly higher in osteoporosis compared to control group (all p < 0.05). Berberine, especially the high doses of berberine, effectively increased SOD, GSH⁃Px, and OPG levels as well as decreased serum osteocalcin, ALP, MDA and RANKL levels in berberine-treated osteoporosis groups (all p < 0.05). To conclude, oxidative stress may promote the development of osteoporosis in rats through the RANK/RANKL/OPG pathway. The antioxidative effect of berberine reduces the development of osteoporosis in rats to some extent.

Acrolein Scavenger Hydralazine Prevents Streptozotocin-Induced Painful Diabetic Neuropathy and Spinal Neuroinflammation in Rats.

Diabetes-induced neuropathic pain (DNP) substantially influences people's life qualities. Hyperglycemia-induced excess free radicals have been considered as the most critical mechanisms underlying DNP. As an unsaturated aldehyde and a reactive product of lipid peroxidation, acrolein plays critical roles in diabetic nephropathy and inflammatory pain. We sought to determine whether acrolein is involved in DNP in this study. Diabetes was induced by a single intraperitoneal (i.p.) injection of 60 mg/kg streptozotocin (STZ). An acrolein scavenger hydralazine (5 mg/kg) was administered through a daily injection for 4 weeks, starting immediately within 30 min after STZ injection. Western blot showed that hydralazine could effectively inhibit STZ-induced upregulation of acrolein in the spinal dorsal horn on day 7-28 after STZ injection. Behavioral tests showed that STZ injection induced significant mechanical allodynia and thermal hyperalgesia, which could be alleviated by hydralazine. Immunofluorescent histochemistry and Western blot showed that STZ induced significant microglial activation. ELISA data indicated upregulation of inflammatory cytokines IL-1ß and TNF-α expression in the spinal dorsal horn. Furthermore, hydralazine effectively attenuated microglial activation and expression of inflammatory mediators. Our data indicate that acrolein might be involved in the development of neuroinflammation and behavioral consequences of DNP. Anat Rec, 2017. © 2017 Wiley Periodicals, Inc. Anat Rec, 300:1858-1864, 2017. © 2017 Wiley Periodicals, Inc.

The prevention and treatment effects of tanshinone IIA on oestrogen/androgen-induced benign prostatic hyperplasia in rats.

Benign prostatic hyperplasia (BPH) is one of the major diseases of the urinary system in elderly men. Tanshinone IIA (Tan IIA) is the active ingredient extracted from the traditional Chinese medicine Salvia, and it has effects of anti-oxidation, anti-inflammation, vascular smooth muscle relaxation and tumour growth inhibition. The present study aimed to investigate the therapeutic potential of Tan IIA in the prevention and treatment of BPH. In a rat model of oestradiol/testosterone-induced BPH, Tan IIA inhibited the increase in the thickness of the peri-glandular smooth muscle layer, suppressed the expression of proliferating cell nuclear antigen (PCNA) in both prostate epithelial cells and stromal cells, downregulated the expression of androgen receptor (AR), oestrogen receptor α (ERα), cyclin B1 (CCNB1) and cyclin D1 (CCND1), and effectively prevented the development of the disorder. In vitro, Tan IIA inhibited the proliferation of human prostate stromal cell line WPMY-1 and epithelial cell line RWPE-1 in a dose- and time-dependent manner. In WPMY-1 cells, Tan IIA treatment arrested the cell cycle at the G2/M phase and downregulated the expression of CCNB1. However, in RWPE-1 cells, Tan IIA treatment arrested cell cycle at the G0/G1 phase and reduced the expression of CCND1. Tan IIA also reduced the expression of ERα and AR in WPMY-1 and RWPE-1 cells. These results suggest that Tan IIA can inhibit the growth of prostate stromal and epithelial cells both in vivo and in vitro by a mechanism that may involve arresting the cell cycle and downregulating ERα and AR expression.

[Effects of qishenyiqi gutta pills on calcium/calmodulin dependent protein kinase II in rats with renal hypertension].

OBJECTIVE: To explore the effects of qishenyiqi gutta pills on myocardial hypertrophy of left ventricle and calcium/calmodulin dependent protein kinase II (CAMK II) in rats with renal hypertension and elucidate its intervention mechanism for myocardial hypertrophy. METHODS: A total of 50 Wistar rats were randomly divided into 5 groups of sham-operation, control, high-dose qishenyiqi gutta pills, low-dose qishenyiqi gutta pills and valsartan (n = 10 each). The rat model of myocardial hypertrophy with renal hypertension was established by the 2-kidney 1-clip (2K1C) method. The experimental animals were divided into control, high-dose, low-dose and valsartan groups. At Week 5 postoperation, valsartan group received an oral dose of valsartan (30 mg×kg(-1)×d(-1)), high-dose and low-dose groups took qishenyiqi gutta pills (250 and 125 mg×kg(-1)×d(-1)) while sham-operation and control groups had the same dose of normal saline solution. Tail arterial pressure was detected weekly and continued for 8 weeks. At the end of Week 12, the animals were sacrificed to harvest myocardial tissue of left ventricle for detecting left ventricular mass index (LVMI). The collagen volume fraction (CVF) of myocardium was examined by Van Gieson staining, the activities of superoxide dismutase (SOD) and reactive oxygen species (ROS) were detected by enzyme-linked immunosorbent assay (ELISA) and the expression of CAMK II was detected by immunohistochemistry and Western blot. RESULTS: (1) Blood pressures were significantly higher in high-dose, low-dose and control groups than those in sham-operation and valsartan groups ((167.66 ± 11.48), (166.72 ± 13.51), (174.34 ± 14.52) vs (119.57 ± 6.30), (131.80 ± 12.49) mm Hg, P < 0.01). The changes of blood pressure had no significant difference between high-dose and low-dose groups. (2) LVMI and CVF increased significantly in high-dose, low-dose and valsartan groups versus sham-operation group (LVMI: (1.98 ± 0.16), (2.09 ± 0.14), (1.97 ± 0.17) vs (1.74 ± 0.17) g/kg; CVF: 0.94% ± 0.22%, 2.53% ± 0.61%, 0.81% ± 0.20% vs 0.45% ± 0.13%) (P < 0.01, P < 0.05), but decreased significantly versus control group (LVMI: (1.98 ± 0.16), (2.09 ± 0.14), (1.97 ± 0.17) vs (2.28 ± 0.28) g/kg; CVF: 0.94% ± 0.22%, 2.53% ± 0.61%, 0.81% ± 0.20% vs 4.73% ± 1.04%) (P < 0.01, P < 0.05). (3) The expression of CAMK II was significantly higher in high-dose, low-dose, valsartan and control groups than that in sham-operation group (65.9%, 95.3%, 84.8%, 160.1% vs 67.7%). And it was significantly lower in high-dose, low-dose and valsartan groups than that in control group (65.9%, 95.3%, 84.8% vs 160.1%). There was no statistical difference among high-dose, low-dose and valsartan groups. CONCLUSIONS: Qishenyiqi gutta pills may retard myocardial hypertrophy of left ventricle in rats with renal hypertension. And the mechanism is probably be correlated with its antioxidant activity and inhibited expression of myocardial CAMK II.

[Study on efficacy of zaoren anshen capsules in treating senile insomnia and changes in its hemorheology].

OBJECTIVE: To observe the effect of Zaoren Anshen capsules in treating senile insomnia and changes in its hemorheology. METHOD: A total of 120 patients with senile insomnia were randomly divided into the Zaoren Anshen capsules group (five capsules, n = 60) and the Alprazolam group (0.8 mg, n = 60) for treatment and control observation. Pittsburgh sleep quality index (PSQI) was used for evaluating clinical efficacy in the first and fourth week before and after treatment. RESULT: The Zaoren Anshen capsules group had lower higher scores in PSQI (5.91 +/- 1.37) than that before treatment (13.49 +/- 3.87), with great statistical significant in difference (P < 0.01). The alprazolam group had lower higher scores in PSQI than that before treatment, with great statistical significant in difference (P < 0.01). apart from higher PSQI scores in the Zaoren Anshen capsules group than that of the Alprazolam group after treatment for one week (P < 0.05), the comparison between the Zaoren Anshen capsules group and the alprazolam group before and after treatment for four weeks showed no statistical significance. As for hemorheological parameters, the difference in the whole blood viscosity (including high-shear, middle-shear and low-shear) of patients in the Zaoren Anshen capsules showed great statistical significance before and after treatment (P < 0.01), and so did the plasma viscosity (P < 0.05). Zaoren Anshen capsules showed less adverse reactions than alprazolam. CONCLUSION: Zaoren Anshen capsules have similar effect in treating senile insomnia with alprazolam, with less adverse reactions. They are so suitable for patients with senile insomnia that they can improve hemorheological indicators of patients with senile insomnia and have good effect in promoting circulation and removing stasis.

Two new anthraquinone glycosides from the roots of Rheum palmatum.

Two new anthraquinone glycosides, named 1-methyl-8-hydroxyl-9,10-anthraquinone-3-O-ß-D-(6'-O-cinnamoyl)glucopyranoside (1) and rhein-8-O-ß-D-[6'-O-(3''-methoxyl malonyl)]glucopyranoside (2), have been isolated from the roots of Rheum palmatum, together with seven known compounds, rhein-8-O-ß-D-glucopyranoside (3), physcion-8-O-ß-D-glucopyranoside (4), chrysophanol-8-O-ß-D-glucopyranoside (5), aleo-emodin-8-O-ß-D-glucopyranoside (6), emodin-8-O-ß-D-glucopyranoside (7), aleo-emodin-ω-O-ß-D-glucopyranoside (8), and emodin-1-O-ß-D-glucopyranoside (9). Their structures were elucidated on the basis of chemical and spectral analysis.

Effects of Bushen Huoxue formula on the learning and memory function and the cerebral neurotransmitters in diabetic mice.

OBJECTIVE: To observe the effects of Bushen Huoxue Formula (Formula for reinforcing the kidney and activating blood circulation) on the learning and memory function and the cerebral neurotransmitters in diabetic mice. METHODS: Forty ICR mice were randomized into the normal control group, model group, Nimotop group and Chinese medicine group, 10 mice in each group. Tail intravenous injection of alloxan was applied to prepare diabetic model. Four weeks later, intragastric administration of Bushen Huoxue Formula for the Chinese medicine group, Nimotop for the Nimotop group, and isometric distilled water for the other two groups were respectively given for 8 weeks. The changes in the blood sugar level were observed; the learning and memory function was detected by Morris labyrinth test; and the contents of norepinephrine (NE), dopamine (DA), 5-hydroxyltryptamine (5-HT) and 5-hydroxyl indole acetic acid (5-HIAA) in cerebral cortex were determined in mice of all the groups. RESULTS: The blood sugar levels in the diabetic model mice significantly increased as compared with those of the normal control group determined 72 h and 12 weeks later (P < 0.05 or P < 0.01). Latencies for Morris labyrinth test in the Nimotop group and the Chinese medicine group were significantly shortened as compared with that in the model group (P < 0.01). The contents of cortical NE in the Chinese medicine group was significantly higher than that in the model group (P < 0.01). CONCLUSION: Bushen Huoxue Formula can improve the learning and memory function in the diabetic mice, and the mechanism is possibly related with change of the cortical NE content.

[Effect of Ningzhi capsule on blood lipid spectrum in type 2 diabetes mellitus patients complicated with hyperlipidemia].

OBJECTIVE: To observe the effect of Ningzhi Capsule (NZC) on blood lipid spectrum in type 2 diabetes mellitus patients complicated with hyperlipemia (DM-HL). METHODS: Adopting randomized, parallel and controlled trail method, a total of 70 DM-HL patients of qi-yin deficiency and phlegm-blood stagnant syndrome type were randomized into two groups. The original medication for lowering blood sugar and blood pressure was unchanged, the trial group received oral administration of NZC 5 tablets, 3 times a day, while the control group received Lipanthgl or Simvastatin depending on their different constituents of blood lipids. After 6 months of treatment, sixty subjects completed the trail while two patients dropped out due to side effect and 8 patients lost follow-up (4 in each group). Levels of blood lipids, blood routine, liver and kidney function and symptoms in patients were detected and compared. RESULTS: After treatment, levels of total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL-C), apoprotein B, and lipoprotein a (LPa) lowered, while levels of high-density lipoprotein (HDL-C) and apoprotein A raised in the trial group as compared with those before treatment (P < 0.05, P < 0.01), but showed no difference between the two groups after treatment except HDL level (P > 0.05). Scores of symptoms were also lowered significantly in the trial group (P < 0.01). In the observation period, no abnormal findings in blood and urine routine examination as well as in liver and renal function were found. CONCLUSION: NZC could lower the blood lipid spectrum and improve the TCM symptoms in DM-HL patients without any adverse reaction.

Adenosine is crucial for deep brain stimulation-mediated attenuation of tremor.

Deep brain stimulation (DBS) is a widely used neurosurgical approach to treating tremor and other movement disorders. In addition, the use of DBS in a number of psychiatric diseases, including obsessive-compulsive disorders and depression, is currently being tested. Despite the rapid increase in the number of individuals with surgically implanted stimulation electrodes, the cellular pathways involved in mediating the effects of DBS remain unknown. Here we show that DBS is associated with a marked increase in the release of ATP, resulting in accumulation of its catabolic product, adenosine. Adenosine A1 receptor activation depresses excitatory transmission in the thalamus and reduces both tremor- and DBS-induced side effects. Intrathalamic infusion of A1 receptor agonists directly reduces tremor, whereas adenosine A1 receptor-null mice show involuntary movements and seizure at stimulation intensities below the therapeutic level. Furthermore, our data indicate that endogenous adenosine mechanisms are active in tremor, thus supporting the clinical notion that caffeine, a nonselective adenosine receptor antagonist, can trigger or exacerbate essential tremor. Our findings suggest that nonsynaptic mechanisms involving the activation of A1 receptors suppress tremor activity and limit stimulation-induced side effects, thereby providing a new pharmacological target to replace or improve the efficacy of DBS.

Thermal rearrangement of {[2-(Arylmethylene)cyclopropyl]methyl}(phenyl)sulfanes and selanes.

{[2-(Arylmethylene)cyclopropyl]methyl}(phenyl)sulfanes and {[2-(arylmethylene)cyclopropyl]methyl}(phenyl)selanes, generated in situ from 2-(arylmethylene)cyclopropylcarbinols with sodium benzenethiolate and sodium benzeneselenolate, could undergo rearrangement upon heating to afford (2-arylmethylidenebut-3-enyl)(phenyl)sulfanes and (2-arylmethylidenebut-3-enyl)(phenyl)selanes, in good to excellent yields as mixtures of E- and Z-isomers, respectively. A radical rearrangement was proposed on the basis of control experiments for this process.

Reflection on development of integrated traditional Chinese and Western medicine / 中国中西医结合杂志

After half a century of self-innovation, the integrated traditional Chinese and Western medicine has witnessed the great progress in both clinical and basic research. However, the theoretical system of the integrative medicine does not break through the limitations of traditional Chinese medicine and Western medicine, which hinders its implication in experimental study and clinical work. In view of the current situation, to develop the integration of traditional Chinese and Western medicine further, efforts should be made in such aspects as educational system construction, talent personnel training, improving the level of clinical practice and corresponding basic research as well as the establishing the basic theoretical system.

How pollen tubes grow.

Sexual reproduction of flowering plants depends on delivery of the sperm to the egg, which occurs through a long, polarized projection of a pollen cell, called the pollen tube. The pollen tube grows exclusively at its tip, and this growth is distinguished by very fast rates and reaches extended lengths. Thus, one of the most fascinating aspects of pollen biology is the question of how enough cell wall material is produced to accommodate such rapid extension of pollen tube, and how the cell wall deposition and structure are regulated to allow for rapid changes in the direction of growth. This review discusses recent advances in our understanding of the mechanism of pollen tube growth, focusing on such basic cellular processes as control of cell shape and growth by a network of cell wall-modifying enzymes, molecular motor-mediated vesicular transport, and intracellular signaling by localized gradients of second messengers.

Pollen-specific pectin methylesterase involved in pollen tube growth.

Pollen tube elongation in the pistil is a crucial step in the sexual reproduction of plants. Because the wall of the pollen tube tip is composed of a single layer of pectin and, unlike most other plant cell walls, does not contain cellulose or callose, pectin methylesterases (PMEs) likely play a central role in the pollen tube growth and determination of pollen tube morphology. Thus, the functional studies of pollen-specific PMEs, which are still in their infancy, are important for understanding the pollen development. We identified a new Arabidopsis pollen-specific PME, AtPPME1, characterized its native expression pattern, and used reverse genetics to demonstrate its involvement in determination of the shape of the pollen tube and the rate of its elongation.