[Nitrogen Removal Characteristics and Metabolism Mechanism of High-Efficiency Cold-Tolerant Heterotrophic Nitrification-Aerobic Denitrification Bacterium Glutamicibacter sp. WS1 for Various Nitrogen Sources at Low Temperature].

For resolving the problems of poor nitrogen removal efficiency and substandard effluent quality in wastewater treatment plants during winter, a cold-tolerant strain Glutamicibacter sp. WS1, with heterotrophic nitrification-aerobic denitrification ability, was isolated from activated sludge. The functional genes for nitrogen conversion of strain WS1 were amplified by PCR, and the nitrogen removal characteristics of the strain were verified under different nitrogen sources at 15℃. In addition, the effects of environmental factors on the aerobic denitrification performance of the strain were explored at low temperature. Finally, a reasonable nitrogen metabolism pathway of strain WS1 was resolved based on functional genes and nitrogen balance analysis. The results showed that strain WS1 contained functional genes related to nitrogen conversion, including amoA, napA, nirS, and nirK genes. Notably, nirS and nirK genes coexisted in the strain. At the low temperature of 15℃, with NH4+-N, NO3--N, NO2--N+NO3--N, and NH4+-N+NO3--N as nitrogen sources, the corresponding removal efficiencies of strain WS1 were 100%, 98.10%, 99.87%+100%, and 100%+94.92%, respectively. The optimal denitrification performance of the strain was achieved with sodium citrate as the carbon source, C/N of 16, pH of 8, DO of 4.5-6.8 mg·L-1, and temperature of 30℃. In addition, the NO3--N removal efficiency of strain WS1 reached 92.50% under low temperature (15℃) and low C/N (10) conditions. Based on the results of PCR amplification and nitrogen balance analysis, heterotrophic nitrification-aerobic denitrification/aerobic denitrification and assimilation were the main pathways for nitrogen substrate removal by strain WS1, in which most of the inorganic nitrogen (47%-56%) was converted to gaseous nitrogen through heterotrophic nitrification-aerobic denitrification/aerobic denitrification. Strain WS1 has broad application prospects in the treatment of low-temperature nitrogenous wastewater.

Guided isolation of secondary metabolites from Nectria sp. MHHJ-3 by molecular network strategy.

The fungus Nectria sp. MHHJ-3 was isolated from Illigera rhodantha. A molecular networking-guided the secondary metabolites investigation of Nectria sp. MHHJ-3 led to the isolation of ten metabolites (1-10), including two new naphthalenone derivatives, nectrianaphthalenones A (1) and B (2), and two new steroids, nectriasteroids A (3) and B (4). Their structures were elucidated by extensive spectroscopic analysis including the HRESIMS, 1D/2D NMR and electronic circular dichroism (ECD) spectra. A plausible biosynthetic pathway for 1-2 was proposed. Compounds 1 and 2 exhibited moderate acetylcholinesterase (AChE) inhibitory activities. Compounds 3 and 4 showed significant cytotoxic activity against selected tumor cells. Particularly, compound 3 exhibited the strongest activity against A549 cells with an IC50 value of 13.73 ± 0.03 µM, which was at the same grade with that of positive control cisplatin.

JNK modulates RAGE/ß-catenin signaling and is essential for allergic airway inflammation in asthma.

As a leading cause of occupational asthma, toluene diisocyanate (TDI)-induced asthma is an inflammatory disease of the airways with one of the most significant characteristics involving inflammation, in which the receptor of advanced glycation end products (RAGE) plays an extremely important role. However, the mechanism underlying the upregulation of RAGE is still unknown. The aim of the present study was to examine whether JNK mediates ß-catenin stabilization via activation of RAGE in asthma. Herein from the results by analyzing the blood from healthy donors and patients with asthma, it was found that the expression of RAGE and p-JNK is highly correlated and elevated concomitantly with the severity of bronchial asthma. Additionally, upon sensitizing and challenging the mice with TDI, we found that RAGE inhibitor (FPS-ZM1) and JNK inhibitor (SP600125) significantly reduced the TDI-induced asthma inflammation in vivo. Furthermore, SP600125 also considerably restored RAGE and p-JNK expression. Besides, the in vitro results from TDI-HSA treatment of 16HBE cells reveal that therapeutic inhibition of JNK reduced TDI driving RAGE expression and ß-catenin translocation, while treatment with Anisomycin, a JNK agonist, showed the opposite effect. Moreover, genetic knockdown of RAGE does not contribute to JNK phosphorylation, indicating that JNK functions upstream of RAGE. Collectively, these findings highlight a role for JNK signaling in RAGE/ß-catenin regulation and have important therapeutic implications for the treatment of TDI induced asthma.

Dosimetric Predictors of Radiation Gastritis Due to Postoperative Intensity Modulated Irradiation Therapy in Patients with Esophageal Squamous Cell Carcinoma After Radical Esophagectomy.

Objective: To explore the association between the incidence of acute radiation gastritis attributed to postoperative intensity modulated irradiation therapy (IMRT) and the dose volume of intrathoracic stomach of patients with esophageal squamous cell carcinoma (ESCC) after radical esophagectomy. Methods: The authors retrospectively collected the data of 49 ESCC patients who participated in postoperative IMRT treatment after radical esophagectomy, and analyzed the incidence of acute radiation gastritis during the treatment. Results: Among all the 49 patients, acute grade ≥2 radiation gastritis was observed in 19 patients (39%). Receiver operating characteristic (ROC) curve analysis showed that the physical variables, such as stomach Dmax, Dmean, length of the whole stomach received 5-40 Gy (LSTT5-LSTT40), and V10-V50, were associated with acute radiation gastritis. Patients were grouped according to cutoff values in physical indicators obtained from the ROC curve. Other than V5, the incidence of acute grade ≥2 radiation gastritis was significantly higher in the group with indicators above cutoff values than that below cutoff values, and the between-group difference was statistically significant in terms of physical indicators. Multivariate analysis suggested that LSTT5 and V40 could be acted as indicators to predict the incidence of acute grade ≥2 radiation gastritis. Conclusions: In the postoperative IMRT treatment for ESCC patients, protection of intrathoracic stomach is strongly recommended. Dose-volume histogram is a preferable predictive indicator for the occurrence of acute radiation gastritis, especially for the stomach LSTT5 and V40. Nevertheless, a larger sample size is needed to provide insight into the relevant study.

An electrochemical sensor based on poly(procaterol hydrochloride)/carboxyl multi-walled carbon nanotube for the determination of bromhexine hydrochloride.

Poly(procaterol hydrochloride) (p-ProH) polymeric film was successfully deposited onto the carboxyl multi-walled carbon nanotube (CMWCNT) modified glass carbon electrode (GCE) to construct a p-ProH/CMWCNT composite modified GCE. Due to the synergistic effect of p-ProH and CMWCNT in the composite, the developed sensor can enormously enhance the oxidation peak current of bromhexine hydrochloride (BrH) at ca. + 0.90 V. Based on this appearance, an electrochemical method was established for the sensitive and selective determination of BrH with differential pulse voltammetry (DPV). Various conditions affecting the peak current response of BrH were studied and optimized. Under the best conditions, the oxidation peak current of BrH is linear to its concentration in two linear dynamic ranges of 0.2-1.0 µmol L-1 (R = 0.9948) and 1.0-8.0 µmol L-1 (R = 0.9956), with a detection limit of 0.1 µmol L-1 (S/N = 3). Interference experiment indicated that the as-prepared electrochemical sensor showed wonderful selectivity to the recognition of BrH and was free from disturbance of many other electro-active substances such as dopamine, ascorbic and uric acid. Finally, the practicability of the BrH sensor was verified by the satisfactory results acquired from the BrH determination in pharmaceutical preparation and human serum.

Encapsulation of Phosphotungstic Acid into Metal-Organic Frameworks with Tunable Window Sizes: Screening of PTA@MOF Catalysts for Efficient Oxidative Desulfurization.

Clean fuels with extremely low sulfur content are highly desirable due to environmental concerns. Herein, three water-stable and eco-friendly metal-organic frameworks with tunable window diameters, denoted as MOF-808X, have been employed as PTA solid supports. An array of PTA@MOF-808X composites were facilely synthesized via the encapsulation strategy. With tunable window sizes and adjustable PTA loading amounts, the obtained PTA@MOF-808X composites were screened for catalytic oxidative desulfurization (ODS) with H2O2 serving as oxidant. The experiments found that 42%PTA@MOF-808A had the highest catalytic ODS activity and could completely remove dibenzothiophene (DBT) in a model fuel with an initial sulfur content of 1000 ppm within 30 min, which falls far below the acceptable limits for fuel standards (10 ppm). Further investigations revealed that this high catalytic activity could be attributed to the cooperative catalysis of metal clusters in the host framework and the guest PTA molecules. Moreover, 42%PTA@MOF-808A could be facilely recovered and reused for at least five runs without loss of catalytic activity. Having a combination of eco-sustainability, high stability, high catalytic activity, and good recyclability, 42%PTA@MOF-808A therefore represents a new benchmark material for catalytic ODS and provides a new perspective for ultradeep desulfurization.

MOF-808: A Metal-Organic Framework with Intrinsic Peroxidase-Like Catalytic Activity at Neutral pH for Colorimetric Biosensing.

Natural enzyme mimetics with high catalytic activity at nearly neutral pH values are highly desired for their applications in biological systems. Herein for the first time a stable MOF, namely MOF-808, has been shown to possess high intrinsic peroxidase-like catalytic activity under acidic, neutral, and alkaline conditions. As a novel peroxidase mimetic, MOF-808 can effectively catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine when H2O2 serves as oxidant, accompanied by a significant color variation in the solution. The catalytic activity and the color variation were greatly dependent on H2O2 concentration, and thus MOF-808 can be applied to the colorimetric sensing of H2O2. The H2O2 detection limit is 4.5 µM, and the linear range is 10 µM to 15 mM. In view of the significant inhibition effect produced by ascorbic acid, a facile and sensitive approach for colorimetric sensing of ascorbic acid was successfully established. The AA detection limit is 15 µM, and the linear range is 30-1030 µM. Further investigation found that the catalytic activity of MOF-808 could be mainly ascribed to the Zr-OH(OH2) groups. Such active Zr-OH(OH2) groups can be effectively shielded by gluconic acid, and subsequently the catalytic activity of MOF-808 was significantly suppressed. With these findings, a facile and selective colorimetric assay for glucose sensing has been successfully explored via combination of the glucose oxidation with the TMB oxidation. The glucose detection limit is 5.7 µM, and the linear range is 5.7-1700 µM. MOF-808 is one of the best colorimetric biosensors among the peroxidase mimics reported for H2O2, AA, and glucose detection.

Simultaneous voltammetry detection of dopamine and uric acid in human serum and urine with a poly(procaterol hydrochloride) modified glassy carbon electrode.

In the present study, procaterol hydrochloride (ProH) was successfully electropolymerized onto a glass carbon electrode (GCE) with simply cyclic voltammetry scans to construct a poly(procaterol hydrochloride) (p-ProH) membrane modified electrode. Compared with the bare GCE, much higher oxidation peak current responses and better peak potentials separation could be obtained for the simultaneous oxidation of dopamine (DA) and uric acid (UA), owning to the excellent electrocatalytic ability of the p-ProH membrane. And it's based on that a square wave voltammetry (SWV) method was developed to selective and simultaneous measurement of DA and UA. Under the optimum conditions, the linear dependence of oxidation peak current on analyte concentrations were found to be 1.0-100 µmol/L and 2-100 µmol/L, giving detection limits of 0.3 µmol/L and 0.5 µmol/L for DA and UA, separately. The as prepared modified electrode shows simplicity in construction with the merits of good reproducibility, high stability, passable selectivity and nice sensitivity. Finally, the proposed p-ProH membrane modified electrode was successfully devoted to the detection of DA and UA in biological fluids such as human serum and urine with acceptable results.

High Incidence of Incidental Prostate Cancer in Transurethral Resection of Prostate Specimens in China. The Value of Pathologic Review.

OBJECTIVE: To identify the incidence and clinicopathologic features of prostate cancer incidentally detected in patients undergoing transurethral resection of the prostate (TURP) for benign prostatic hyperplasia (BPH), and to estimate the clinical value of pathologic review of all TURP specimens. STUDY DESIGN: A pathologic review was performed on all TURP specimens for each patient from May 1, 2004, to June 30, 2014, in our institute. A total of 1,024 men (ages 46-98) were identified by pathology specimen. Those with a known diagnosis of prostate cancer prior to TURP (n = 16) were excluded from the analysis. The tumor volume, Gleason score, pathologic stage, serum prostate-specific antigen (PSA) level, and follow-up data were evaluated for those who were found to have prostate cancer. RESULTS: A total of 87 (8.6%) patients (ages 50-88) were found to have prostate cancer. Significant prostate cancer was found in 25 patients. From May 1, 2004, to May 31, 2009, 30 (6.1%) patients (ages 57-83) were found to have prostate cancer. From June 1, 2009, to June 30, 2014, 57 (11.0%) patients (ages 50-88) were found to have prostate cancer. CONCLUSION: Our series demonstrates that 8.6% of patients were found to have prostate cancer and that the incidence was increasing in recent years. Even in some patients with T1a disease, the tumors were significant. The pathologic review of TURP specimens is valuable in China.

Analysis of failure patterns in patients with resectable esophageal squamous cell carcinoma receiving chemoradiotherapy.

PURPOSE: This study investigates the failure pattern after chemoradiotherapy of patients with resectable esophageal squamous cell carcinoma (ESCC). MATERIALS AND METHODS: We retrospectively analyzed 92 patients with T1-2, N0-1, and M0 ESCC. These patients were inoperable because of poor performance, comorbidities, poor tumor region, or refusal of operation. RESULTS: Among the 92 patients, 29 cases displayed simple locoregional recurrence, 12 cases displayed simple distant metastasis, and 6 cases displayed distant metastasis with locoregional recurrence. Univariate analysis shows that the incidence of recurrence in the middle thoracic region was significantly higher than other regions (χ2 = 14.415, P = 0.001). For the 18 patients with distant metastasis, incidence of distant metastasis in the lower thoracic region was significantly higher than the other regions (= 39.359, P < 0.001). Among 35 cases with regional recurrence, 7 cases reached complete remission (14.6%) and 28 cases reached partial remission (PR; 63.6%) (χ2= 23.435, P < 0.001). Multivariate analysis shows that the patient age, tumor node metastasis (TNM) stage, and short-term efficacy were independent factors for locoregional recurrence. Patient age, TNM stage, X-ray length of the lesions, and short-term efficacy were the independent factors for distant metastases. CONCLUSION: The incidence of locoregional recurrence and distant metastasis in patients with upper thoracic esophageal cancer was lower than those who had middle thoracic and lower thoracic esophageal cancer. The incidence of locoregional recurrence and distant metastasis in patients who achieved complete response after treatment was low.

Radiation dose to the lymph drainage area in esophageal cancer with involved-field irradiation.

The aim of this study was to quantify the radiation dose to the corresponding lymph drainage area in esophageal cancer using three-dimensional conformal radiation therapy (3D-CRT) with involvED-field IRradiation (IFI) and to analyze associated factors. A retrospective analysis oF 81 patients with esophageal cancer was conducted. According to the location of the lesions, the lymph drainage area was delineated and the dosimetric parameters were calculated. The 1-, 3-, 5- and 8-year survival rates of the patients were 67.90, 33.33, 20.99 and 11.11%, respectively. Based on the dose-volume histogram in the treatment plan, we calculated the volume percentage of the planning target volume including clinically positive lymph nodes (PTV-N) receiving radiation doses of 30, 35, 40, 45 and 50 Gy (VPTV-N30-50). The median values of VPTV-N30-50 were 73, 70, 67, 64 and 58%, respectively. The prescribed dose size exhibited no correlation with VPTV-N30-35, but did exhibit a significant correlation with VPTV-N40-50; the radiation field was not correlated with VPTV-N30-45, but exhibited a significant correlation with VPTV-N50; The length of the lesion on esophageal barium meal X-ray and the PTV were significantly correlated with VPTV-N30-50. The analysis of variance revealed that the VPTV-NX value in the upper thoracic segment was higher compared with that in the middle and lower thoracic segments; VPTV-N30-35 values differed significantly according to the different locations of the lesions, whereas VPTV-N40-50 values exhibited no significant differences. The value of VPTV-NX exerted no significant effect on long-term patient survival. Therefore, the corresponding lymph drainage area of esophageal cancer IS subjected to a certain Radiation dose when patients undergo 3D-CRT with IFI, which may play a role in the prevention of regional nodal metastasis. However, this hypothesis requires confirmation by further clinical studies.

A One-Step Real-Time RT-PCR Assay for the Detection and Quantitation of Sugarcane Streak Mosaic Virus.

Sugarcane mosaic disease is caused by the Sugarcane streak mosaic virus (SCSMV; genus Poacevirus, family Potyviridae) which is common in some Asian countries. Here, we established a protocol of a one-step real-time quantitative reverse transcription PCR (real-time qRT-PCR) using the TaqMan probe for the detection of SCSMV in sugarcane. Primers and probes were designed within the conserved region of the SCSMV coat protein (CP) gene sequences. Standard single-stranded RNA (ssRNA) generated by PCR-based gene transcripts of recombinant pGEM-CP plasmid in vitro and total RNA extracted from SCSMV-infected sugarcane were used as templates of qRT-PCR. We further performed a sensitivity assay to show that the detection limit of the assay was 100 copies of ssRNA and 2 pg of total RNA with good reproducibility. The values obtained were approximately 100-fold more sensitive than those of the conventional RT-PCR. A higher incidence (68.6%) of SCSMV infection was detected by qRT-PCR than that (48.6%) with conventional RT-PCR in samples showing mosaic symptoms. SCSMV-free samples were verified by infection with Sugarcane mosaic virus (SCMV) or Sorghum mosaic virus (SrMV) or a combination of both. The developed qRT-PCR assay may become an alternative molecular tool for an economical, rapid, and efficient detection and quantification of SCSMV.

Incidental prostate cancer in Asian men: high prevalence of incidental prostatic adenocarcinoma in Chinese patients undergoing radical cystoprostatectomy for treatment of bladder cancer and selection of candidates for prostate-sparing cystectomy.

BACKGROUND: Previous studies report a low prevalence of incidental prostate cancer in Chinese patients (3-7%). We evaluated incidental prostatic adenocarcinoma (PCa) and urothelial carcinoma (UCa) involvement of the prostate in cystoprostatectomy specimens. METHODS: We analyzed 340 cystoprostatectomy specimens from patients who underwent radical cystoprostatectomy for the treatment of bladder cancer in China from 2004 to 2014. None of the patients had known prostate cancer prior to cystoprostatectomy. RESULTS: Overall, 180 (53%) patients had either PCa or UCa in the prostate. We found that 95 (28%) had PCa and 115 (34%) had UCa involvement of prostate. The rate of incidental prostate cancer was 21% and 31%, respectively, from two study periods (2004-2008 and 2009-2014). Among the 95 patients with PCa, 19 (20%) had Gleason score of ≥7, nine (10%) had PCa tumor volume >0.5 cc, and eight (8.4%) had extracapsular extension. Of the 115 with prostatic UCa, 61 had prostatic urethra and/or periurethral prostatic duct involvement only, while 54 had prostatic stromal invasion. Age (odds ratio [OR] = 1.04, P = 0.001), increasing stage of bladder tumor (OR = 1.28, P = 0.005), multifocal tumors of bladder (OR = 3.22, P < 0.001), carcinoma in situ (CIS) in the bladder (OR = 5.52, P < 0.001), and bladder neck involvement (OR = 6.12, P < 0.001) were strongly associated with prostatic UCa. CONCLUSIONS: The rate of incidental PCa in cystoprostatectomy specimens in China has increased over the last decade. Patients with advanced age, elevated serum PSA level, advanced bladder tumor stage, multifocal bladder tumors, CIS in the bladder, and tumor location at the bladder neck should be excluded as candidates for prostate-sparing cystectomy.

Adult renal cell carcinoma with rhabdoid differentiation: incidence and clinicopathologic features in Chinese patients.

Renal cell carcinoma (RCC) with rhabdoid differentiation is a recently described variant of RCC, which has seldom been reported in China. This form of differentiation has been generally associated with a poor prognosis and is often present in tumors with a poorly differentiated morphology. The development of a rhabdoid morphology appears to represent a common dedifferentiation pathway for renal parenchymal malignancies. The aim of this study is to evaluate the incidence and clinicopathologic features of RCC rhabdoid differentiation in Chinese adult patients and to further investigate its origin. We reviewed 723 cases of RCC obtained between January 2012 and March 2014 in Peking University First Hospital. From these cases, 10 (1.4%) were found to have areas of classic rhabdoid morphology. Immunohistochemistry for vimentin, cytokeratin (CK) (pan-cytokeratin (AE1/AE3), CK20, CK5/6, CK7, and CK8/18), RCC, CD10, Pax-2, Pax-8, CD117, desmin, muscle-specific actin, CD68, p53, and Ki-67 was performed in each case using the labeled streptavidin-biotin method. Rhabdoid differentiation was identified in association with clear cell RCC, papillary RCC (II type), and sarcomatoid RCC. We compared the morphologic and immunohistochemical features between rhabdoid and nonrhabdoid components. In our cases, rhabdoid differentiation was characterized by the presence of cohesive large epithelioid cells with abundant pink cytoplasm and central eosinophilic intracytoplasmic inclusions and 1 or more large, oval, eccentric, or irregular nuclei containing prominent nucleoli. Most of the rhabdoid areas showed a solid growth pattern. In our series, RCC with rhabdoid differentiation had an aggressive biological behavior, and rhabdoid components were most likely associated with high-grade tumors of advanced stage. In all cases, the rhabdoid and nonrhabdoid tumoral areas without sarcomatoid differentiation exhibited the very similar immunophenotype as follows: vimentin (+/-), AE1/AE3 (+), CK8/18(+), CK7(+/-), CK5/6 (-), CK20 (-), RCC (focal +), CD10 (focal +), Pax-2 (+), Pax-8 (+), CD117 (+/-), desmin (-), muscle-specific actin (-), and CD68 (-). On p53 and Ki-67 immunohistochemistry, the positive rate of rhabdoid cells for both p53 and Ki-67, similar to sarcomatoid cells, was higher than that of nonrhabdoid tumor cells without sarcomatoid differentiation. Our results indicate that the incidence rate of rhabdoid differentiation in Chinese adult RCC patients is lower than that of foreign reports. We support that the rhabdoid and nonrhabdoid tumor cells originate from the same clone, and the rhabdoid components present high proliferative activity and indicate a poor prognosis.

[Incidence and pathological features of incidental prostate cancer and clinical significance thereof].

OBJECTIVE: To investigate the morbidity and pathological features of incidental prostate cancer and their clinical significance. METHODS: 1483 prostate specimens obtained during operation, including transurethral resection of prostate (TURP) and total resection of the prostate, for the diagnoses of benign prostatic hypertrophy (BPH) or bladder cancer between January 1999 and August 2005 underwent pathological examination and 34beta12 and p63 immunohistochemical staining so as to detect incidental prostate cancer. The volume of incidental prostate cancer was calculated by the image analysis system. The clinical data were analyzed retrospectively. Comparison between the clinical and pathological feature of incidental prostate cancer was made. RESULTS: 53 cases of incidental prostate cancer, with the Gleason scores from 2 (1+1) to 9 (4+5) and the volumes from 0.18 to 1440.00 mm(3) were detected. The morbidity of incidental prostate cancer was 3.6%. The volume of 47 cases (88.7%) were less than 0.5 cm(3) as the threshold of insignificant cancer, and the volumes of 6 cases (11.3%) were more than 0.5 cm(3). All incidental prostate cancers of clinical significance were detected in the TURP samples. Among the incidental prostate cancers found in the TURP samples 20% were clinically significant cancers. The clinically significant incidental cancers were located in the central or transitional zone with the Gleason scores of 3 + 4 (2 cases), 4 + 2 (1 case), or 4 + 5 (3 cases). These clinically significant cancers were of diffuse distribution, and their preoperative clinical features were negative in palpation/image examination, elevation of serum PSA, and negative in puncture examination. CONCLUSION: Nowadays, the morbidity of incidental prostate cancer is lower than that of 1980s'. Among the incidental cancers 11.3% were of clinical significance. That the preoperative clinical examination cannot find these clinical significant cancers is partially caused by the pathological features of these tumors.

Distribution changes of calcium and programmed cell death in the pistil of litchi (Litchi chinensis Sonn.) flower during its development.

Potassium pyroantimonate precipitation method was used for investigating calcium distribution and cell ultrastructure change during development of pistils of litchi male and female flower. The results showed that at the megasporocyte stage of female flowers, calcium precipitates was located mainly at cell wall and intercellular space of inner integument near the micropyle and style cells, and to a lesser extent in vacuoles. Vascular tissues also contained much calcium precipitates. In inner integument cells near the micropyle of male flowers, the vacuole contained most of the calcium precipitates. Calcium precipitates in style cell and vascular tissues of male flowers was sparse and seldom seen. After meiosis of megasporocyte, pistils of female flowers continued to grow and those of male flowers aborted. In female flowers, calcium precipitates concentration became lower and calcium precipitates was probably transported to the places for future pollen bourgeoning and fertilization. Cell wall calcium precipitates concentration increased in the inner integument cells near the micropyle. Calcium precipitates concentration increased from topper style cells to lower ones. In male flowers, inner integument cells near the micropyle underwent the programmed cell death (PCD): flow of calcium from vacuoles into nucleus might had triggered the PCD process. A continuous channel was formed between perinuclear space and cytoplasm membrane lumen, and calcium flowed freely between nuclear membrane and plasma membrane. At certain time and locations, calcium precipitates was newly appeared at some organelles like endoplasimic reticulum, mitochondria and peroxisomes. This calcium redistribution in cells might trigger and regulate the process of PCD. In male flowers, style cells containing no calcium precipitation soon began to degenerate.

[Changes in cell ultrastructure during sexual determination of litchi staminate flower].

The ultrastructural changes of meristematic cell during the degeneration of gynoecium primordium leading to the formation of staminate flower of litchi were followed. Degradation of the cells and transport of the dissolved cytoplasmic components were well ordered. Configurations of rough endoplasmic reticulum (RER) changed significantly. ER played an important role in degenerative processes of gynoecium primordiuml cells. The degenerative processes started with the appearance of long RER cisternae throughout the cytoplasm. Some long RER cut or enclosed the cytoplasm. Some RER connected nucleus and mitochondria of adjacent cells, formed a ridge-like connection. Later the RER formed concentric patterns and then became irregular stacks. RER and golgiosome produced many vesicles, which were importance to protoplasmic degradation and intercellular transport of the cellular debris. The number of mitochondria increased up to the time when they began to degrade in batches. Peroxisomes appeared temporarily at the middle stage near the nucleus. The nucleolus disintegrated at the beginning of degeneration of nucleus. Then fragments of chromatin aggregated at the periphery of nuclear membrane and diffused outward. In some nuclei the perinuclear membrane became dilated and puffs were formed. As cell degeneration progressed, the protoplasm disintegrated and dissipated in an orderly fashion, i.e. ribosomes became disorganized first, followed by peroxisomes, ER, golgiosoms, mitochondria and nucleus. Eventually, gynoecium primordium cells digested all of the cytoplasm, leaving only cell wall with high electron density. Most of the products of degeneration of gynoecium primordium cells were removed through either symplastic or apoplastic pathways. Programmed cell death (PCD) may be involved in the degeneration of meristematic cells at the gynoecium primodium.