Biochemical and antigenic characterization of the structural proteins and their post-translational modifications in purified SARS-CoV-2 virions of an inactivated vaccine candidate.

In the face of COVID-19 pandemic caused by the newly emerged SARS-CoV-2, an inactivated, Vero cell-based, whole virion vaccine candidate has been developed and entered into phase III clinical trials within six months. Biochemical and immunogenic characterization of structural proteins and their post-translational modifications in virions, the end-products of the vaccine candidate, would be essential for the quality control and process development of vaccine products and for studying the immunogenicity and pathogenesis of SARS-CoV-2. By using a panel of rabbit antisera against virions and five structural proteins together with a convalescent serum, the spike (S) glycoprotein was shown to be N-linked glycosylated, PNGase F-sensitive, endoglycosidase H-resistant and cleaved by Furin-like proteases into S1 and S2 subunits. The full-length S and S1/S2 subunits could form homodimers/trimers. The membrane (M) protein was partially N-linked glycosylated; the accessory protein 3a existed in three different forms, indicative of cleavage and dimerization. Furthermore, analysis of the antigenicity of these proteins and their post-translationally modified forms demonstrated that S protein induced the strongest antibody response in both convalescent and immunized animal sera. Interestingly, immunization with the inactivated vaccine did not elicit antibody response against the S2 subunit, whereas strong antibody response against both S1 and S2 subunits was detected in the convalescent serum. Moreover, vaccination stimulated stronger antibody response against S multimers than did the natural infection. This study revealed that the native S glycoprotein stimulated neutralizing antibodies, while bacterially-expressed S fragments did not. The study on S modifications would facilitate design of S-based anti-SARS-CoV-2 vaccines.

Low toxicity and high immunogenicity of an inactivated vaccine candidate against COVID-19 in different animal models.

The ongoing COVID-19 pandemic is causing huge impact on health, life, and global economy, which is characterized by rapid spreading of SARS-CoV-2, high number of confirmed cases and a fatality/case rate worldwide reported by WHO. The most effective intervention measure will be to develop safe and effective vaccines to protect the population from the disease and limit the spread of the virus. An inactivated, whole virus vaccine candidate of SARS-CoV-2 has been developed by Wuhan Institute of Biological Products and Wuhan Institute of Virology. The low toxicity, immunogenicity, and immune persistence were investigated in preclinical studies using seven different species of animals. The results showed that the vaccine candidate was well tolerated and stimulated high levels of specific IgG and neutralizing antibodies. Low or no toxicity in three species of animals was also demonstrated in preclinical study of the vaccine candidate. Biochemical analysis of structural proteins and purity analysis were performed. The inactivated, whole virion vaccine was characterized with safe double-inactivation, no use of DNases and high purity. Dosages, boosting times, adjuvants, and immunization schedules were shown to be important for stimulating a strong humoral immune response in animals tested. Preliminary observation in ongoing phase I and II clinical trials of the vaccine candidate in Wuzhi County, Henan Province, showed that the vaccine is well tolerant. The results were characterized by very low proportion and low degree of side effects, high levels of neutralizing antibodies, and seroconversion. These results consistent with the results obtained from preclinical data on the safety.

Differential proteomic analysis reveals the mechanism of Musa paradisiaca responding to salt stress.

Salinity is one of the most important abiotic stresses, which affects the yield and quality of banana (Musa paradisiaca). To understand the salinity tolerance mechanisms of banana, the iTRAQ technique is employed to reveal the proteomic response of Brazil banana under different durations of 60 mmol/L NaCl stress. We have identified 77 DEPs and classified them into nine functional categories, compared with control (0 mmol/L NaCl treatment). The four major categories involve protein synthesis and degradation, photosynthesis, defense response, and energy and carbohydrate metabolism. The results indicate that photosynthesis, protein synthesis and degradation, lipid metabolism and secondary metabolism are promoted to limit damage to a repairable level. The accumulation of ROS under salt stress is harmful to cells and causes up-regulation of antioxidant systems. Furthermore, to cope with cells injured by salt stress, PCD is used to remove the damaged. Additionally, the cytoskeleton can play an important role in maintaining cellular and redox homeostasis. Different categories of functional proteins by changing the abundance ratio shows that plants have different mechanisms of response to salinity. Conclusively, Function of the observed changes in protein expression objective is to establish a new metabolic process of steady-state balance. To my knowledge, this is the first report that investigates responses of M. paradisiaca to salt stress by proteomic analysis.

SRPK1 gene silencing promotes vascular smooth muscle cell proliferation and vascular remodeling via inhibition of the PI3K/Akt signaling pathway in a rat model of intracranial aneurysms.

OBJECTIVE: Intracranial aneurysm (IA) is a life threatening cerebrovascular disease characterized by phenotypic modulation of vascular smooth muscle cells (VSMCs) and loss of vessel cells. In addition to environmental factors, genetic factors have been proposed to be a critical factor in the onset and progression of IA. The present study investigates the effects of serine-arginine protein kinase 1 (SRPK1) on VSMC proliferation and apoptosis both in vivo and in vitro, as well as its role in vascular remodeling in vivo through PI3 K/Akt signaling in IA. METHODS: Differentially expressed genes related to IA were initially identified using microarray analysis. Immunohistochemistry was conducted to determine SRPK1 expression in the vascular walls in IA and normal cerebral vascular walls. TUNEL staining were applied to observe cell apoptosis patterns of VSMCs. VSMC proliferation and apoptosis in vitro were detected by cell counting kit-8 (CCK8) assay and flow cytometry. The expressions of SRPK1, PI3 K/Akt signaling pathway- and apoptosis-related genes were evaluated by RT-qPCR and Western blot analysis. RESULTS: Microarray data of GSE36791 and GSE54083 were analyzed to determine the selection of SRPK1 gene. The vascular walls in IA rat models produced high levels of SRPK1 expression and an activated PI3 K/Akt signaling pathway. VSMCs treated with siRNA-SRPK1 exhibited enhanced cell proliferation, repressed cell apoptosis, and increased vascular remodeling, all of which suggest the inhibition of the PI3 K/AKT pathway. Notably, PI3 K/AKT pathway reversed the effect of SRPK1 silencing. CONCLUSION: Our results show that siRNA-mediated silencing of SRPK1 gene inhibits VSMC apoptosis, and increases VSMCs proliferation and vascular remodeling in IA via the PI3 K/Akt signaling pathway. Our findings provide a novel intervention target for the molecular treatment of IA.

[Effects of spraying paclobutrazol at different stages on physiological characteristics, yield and quality of peanut]. / 不同时期喷施多效唑对花生生理特性、产量和品质的影响.

To explore the optimum stage of spraying with paclobutrazol (PBZ) for different peanut cultivars under high yield condition, we investigated the effects of spraying PBZ at different stages on chlorophyll content, root activity, protective enzymes, nitrogen and carbon metabolism enzymes of leaves, pod yield and kernel quality of peanut, with Huayu 20 and Huayu 25 as materials. The results showed that spraying PBZ at different stages increased root activity, chlorophyll content, SOD, POD, CAT, SS, SPS, PEPC activities and decreased the MDA content, NR, GS, GDH and GOGAT activities for pod setting stage of two cultivars. These results suggested that the effects would be more obvious at earlier spray time. For HY25, the most significant effects of spraying PBZ on those parameters of pod filling stage could be obtained when the main stem height was 25 cm. For HY20, spraying PBZ when the main stem height was 25 cm decreased the activities of protective enzymes. Earlier spraying time to HY20 would lead to early senescence, lower chlorophyll content, root activity and carbon metabolism enzyme activity. For HY20, the most significant effects of spraying PBZ on those parameters of pod filling stage could be obtained when the main stem height was 30 cm. Our results indicated that PBZ treatments at the optimum stage could improve pod yield and economic coefficient of both cultivars and enhance the fat content and the relative content of oleic acid and the O/L. Under high yield condition, the optimum stage of spraying PBZ was 25 cm height of the main stem for HY25 and 30 cm for HY20.

Enhanced osteogenesis of multilayered pore-closed microsphere-immobilized hydroxyapatite scaffold via sequential delivery of osteogenic growth peptide and BMP-2.

Since many complex physiological processes are controlled by multiple biomolecules, comprehensive regulation of bone tissue regeneration may be more effectively achieved by administering more than one type of biofactor. Thus, we propose a novel bone tissue engineering scaffold incorporating a multiple peptide-based drug delivery vehicle for accelerated bone regeneration. Pore-closed poly(lactic-co-glycolic acid) (PLGA) microspheres with a surface structure of multilayer polyelectrolytes ((Ha-Cs)2-Hep-BMP-2-Hep-(Cs-Ha)2) were prepared as multi-barrier microcarriers for osteogenic growth peptide (OGP). In addition, BMP-2 loading was achieved via a pore-closing process and layer-by-layer (LbL) assembly technique, followed by immobilization on the surface of a highly interconnected porous hydroxyapatite (HA) scaffold. On the basis of such a construction, sequential delivery of OGP and BMP-2 occurred in a coordinated manner through an orchestrated sequence of spatial changes, targeting different bone healing stages. The in vitro studies showed that OGP release was minimal (<11.7%) in the first 15 d but accelerated remarkably thereafter, while at least 56.3% of BMP-2 payload was released at this time and subsequent release was only marginal. In addition, scaffolds carrying dual-biofactor exhibited a stronger ability to induce bone marrow mesenchymal stem cell (BMSC) differentiation toward osteoblasts than those incorporating OGP or BMP-2 alone and factor-free scaffolds in terms of alkaline phosphatase (ALP) activity and osteogenic gene and protein (Runx2, COL I, and OCN) expression. The results of in vitro cell culturing demonstrated the roles of BMP-2 in osteogenic differentiation early as well as the effect of OGP on accelerated proliferation and maturation of osteoblast precursors at a later stage. Further in vivo osteogenesis studies also revealed that the dual biofactor-loaded scaffold manifested the best repair efficacy due to a potential synergistic effect of BMP-2 and OGP. Collectively, our findings suggested that such a dual delivery system may provide a therapeutic strategy sequentially targeting multiple events or mechanisms during bone healing and was proved to be a promising therapeutic scaffold for future use in bone tissue regeneration.

[Effects of exogenous Ca2+ on growth and development, physiology and yield of peanut under salt stress]. / 盐胁迫下外源Ca2+对花生生长发育、生理及产量的影响.

Huayu 22, one of the peanut (Arachis hypogaea) cultivars, was used as material in this study. Peanuts, which grew under normal conditions and 100 mmol·L-1 NaCl stress, were treated with 0, 6, 12 mmol·L-1 Ca(NO3)2 respectively to elucidate the effects of exogenous calcium on peanut salt tolerance. The effects of different Ca2+ concentrations on the physiological indices and yield of peanut during the whole growth period under salt stress were investigated in potted plants, with the aim to provide theoretical basis for the growth and production of peanut in saline soil. The results showed that, under salt stress, the activities of superoxide dismutase (SOD), catalase (CAT), and chlorophyll content increased whereas the MDA content and electrolytes decreased when treated with different concentrations of exogenous calcium. Calcium also improved root activity, biomass, improved agronomic traits, and finally increased peanut yield. Among all the exogenous calcium treatments, the effect of 12 mmol·L-1 Ca2+ treatment was the most significant. These results indicated that exogenous calcium could alleviate the salt stress on peanut plants and enhance the yield of pods by enhancing the scavenging ability of active oxygen, maintaining the stability and integrity of cell membrane.

Peanut violaxanthin de-epoxidase alleviates the sensitivity of PSII photoinhibition to heat and high irradiance stress in transgenic tobacco.

KEY MESSAGE: This is the first study on peanut VDE, which led to multiple biochemical and physiological changes to heat and HI stress by improving de-epoxidation of the xanthophylls cycle. A peanut (Arachis hypogaea L.) violaxanthin de-epoxidase gene (AhVDE) was isolated by RT-PCR and RACE methods. The deduced amino acid sequence of AhVDE showed high identities with violaxanthin de-epoxidase of other plant species. The expression of AhVDE was obviously upregulated by 4, 40 °C and high light, NaCl, and abscisic acid. Sense and RNAi transgenic tobaccos were further used to investigate the physiological effects and functional mechanism of AhVDE. Compared with WT, the content of Z, the ratio of (A + Z)/(V + A + Z) and the non-photochemical quenching were higher in sense plants, and lower in the RNAi lines under heat and high irradiance (HI) stress, respectively. Additionally, photoinhibition of photosystem II (PSII) reflected by the maximal photochemical efficiency in WT lines was more severe, and in the RNAi lines was the most severe compared with that in the sense lines. Meanwhile, overexpressing AhVDE also led to multiple biochemical and physiological changes under heat and HI stress. Higher activities of superoxide dismutase and ascorbate peroxidase, lower content of reactive oxygen species and slighter membrane damage were observed in sense lines after heat and HI stress. These results suggested that, peanut VDE can alleviate PSII photoinhibition to heat and HI stress by improving the xanthophyll cycle-dependent energy dissipation.

[Effects of single-seed sowing on canopy microenvironment, photosynthetic characteristics and pod yield of peanut (Arachis hypogaca)].

The large-seed peanut cultivar of Huayu 22 was used to study the differences of canopy microenvironment, photosynthetic characteristics, and pod yield at three single-seed sowing densities, i.e., 225000 (S1), 195000 (S2) and 165000 (S3) holes per hectare, in field experiments. The results showed that the canopy light transmittance, canopy air temperature and canopy CO2concentration all increased at these three single-seed sowing densities compared with those of double-seed sowing pattern (150000 holes per hectare), while the canopy humidity decreased. It seemed that single-seed sowing was helpful to improve microenvironment and the growth of peanut, especially at late growth stage. Meanwhile, the photosynthetic pigment contents and the net photosynthetic rate of peanut under single-seed sowing, especially in S2 and S3, were remarkably higher than those under traditional double-seed sowing. S2 had the optimum population size with an equal distribution of individuals, which reduced the contradiction between individuals and population, optimized the canopy microenvironment, enhanced the photosynthetic characteristics, and increased the synthesis and accumulation of photosynthetic products to maximize the yield production of peanut.

Isolation and functional characterisation of CDPKs gene from Arachis hypogaea under salt stress.

One of salt-induced calcium-dependent protein kinases (CDPKs) gene was isolated from Arachis hypogeae L. by RACE method. The cDNA full length was 2241bp deposited in GenBank (number KF437909), designated as AhCDPK. The coding region sequence of AhCDPK was 1629bp and encoded a protein of 542 amino acids. The molecular weight and the theoretical isoelectric point of AhCDPK was 60.96kDa and 5.61 respectively. Amino acid sequence analysis indicated that AhCDPK has highest similarity and homology with Glycine max L. In addition, the AhCDPK amino acids were predicted to encode a hydrophilic protein which localised in the endoplasmic reticulum. AhCDPK seemed to transcript in all peanut organs, and had the highest expression in seeds. The expression of AhCDPK could be strongly induced by both Ca2+ and NaCl. When exposed to salt stress, overexpressing AhCDPK in tobacco could alleviate PSII photoinhibition by improving physiological states, such as reducing the accumulation of reactive oxygen species (ROS), improving the activity of antioxidant defence system enzymes and improving the accumulation of osmotic regulation substance. These results showed that AhCDPK has the same functions as that of G. max, and it could play an important role for peanut to resist salt stress.

Calcium contributes to photoprotection and repair of photosystem II in peanut leaves during heat and high irradiance.

In this study, we investigated the effects of exogenous calcium nitrate on photoinhibition and thylakoid protein level in peanut plants under heat (40°C) and high irradiance (HI) (1,200 µmol/m(2) per s) stress. Compared with control seedlings (cultivated in 0 mmol/L Ca(NO3 )2 medium), the maximal photochemical efficiency of photosystem II (PSII) in Ca(2+) -treated plants showed a slight decrease after 5 h stress, accompanied by lower degree of PSII closure (1-qP), higher non-photochemical quenching, and lower level of membrane damage. Ca(2+) inhibitors were used to analyze the varieties of antioxidant enzymes activity and PSII proteins. These results indicated that Ca(2+) could protect the subunits of PSII reaction centers from photoinhibition by reducing the generation of reactive oxygen species. In the presence of both ethyleneglycol-bis(2-aminoethylether)-tetraacetic acid and ascorbic acid (AsA), the net degradation of the damaged D1 protein was faster than that only treated with AsA. Our previous study showed that either the transcriptional or the translational level of calmodulin was obviously higher in Ca(2+) -treated plants. These results suggested that, under heat and HI stress, the Ca(2+) signal transduction pathway can alleviate the photoinhibition through regulating the protein repair process besides an enhanced capacity for scavenging reactive oxygen species.

Exogenous calcium alleviates photoinhibition of PSII by improving the xanthophyll cycle in peanut (Arachis hypogaea) leaves during heat stress under high irradiance.

Peanut is one of the calciphilous plants. Calcium (Ca) serves as a ubiquitous central hub in a large number of signaling pathways. The effect of exogenous calcium nitrate [Ca(NO3)2] (6 mM) on the dissipation of excess excitation energy in the photosystem II (PSII) antenna, especially on the level of D1 protein and the xanthophyll cycle in peanut plants under heat (40°C) and high irradiance (HI) (1 200 µmol m(-2) s(-1)) stress were investigated. Compared with the control plants [cultivated in 0 mM Ca(NO3)2 medium], the maximal photochemical efficiency of PSII (Fv/Fm) in Ca(2+)-treated plants showed a slighter decrease after 5 h of stress, accompanied by higher non-photochemical quenching (NPQ), higher expression of antioxidative genes and less reactive oxygen species (ROS) accumulation. Meanwhile, higher content of D1 protein and higher ratio of (A+Z)/(V+A+Z) were also detected in Ca(2+)-treated plants under such stress. These results showed that Ca(2+) could help protect the peanut photosynthetic system from severe photoinhibition under heat and HI stress by accelerating the repair of D1 protein and improving the de-epoxidation ratio of the xanthophyll cycle. Furthermore, EGTA (a chelant of Ca ion), LaCl3 (a blocker of Ca(2+) channel in cytoplasmic membrane), and CPZ [a calmodulin (CaM) antagonist] were used to analyze the effects of Ca(2+)/CaM on the variation of (A+Z)/(V+A+Z) (%) and the expression of violaxanthin de-epoxidase (VDE). The results indicated that CaM, an important component of the Ca(2+) signal transduction pathway, mediated the expression of the VDE gene in the presence of Ca to improve the xanthophyll cycle.

Microsurgical management of cerebral parenchymal cysticercosis.

OBJECTIVE: Microsurgery is an optional way to treat parenchymal neurocysticercosis. The aim of this study is to evaluate the therapeutic efficacy of microsurgery in cerebral parenchymal cysticercosis. MATERIALS AND METHODS: A retrospective analysis was performed of the clinical data and outcomes of microsurgery in 20 cases of cerebral parenchymal cysticercosis. RESULTS: All head segments found in cysticercus cysts were removed completely. Total resection of the cystic wall was achieved in 16 cases and subtotal resection in 4 cases. Twelve patients recovered from intracranial hypertension soon after the operation. No novel complications or deaths occurred postoperatively. The patients were followed up for 3 months to 10 years; among them, 14 patients who had epilepsy before surgery were markedly improved and controlled, 4 of 5 patients recovered from hemiparesis within 6 months after surgery, and 2 patients with cerebellar ataxia showed improvement. Two patients were lost to follow-up. CONCLUSIONS: Despite a high rate of misdiagnosis of cerebral parenchymal cysticercosis, microsurgery is associated with satisfactory clinical outcomes in appropriately selected patients.

17Beta-estradiol differentially protects cortical pericontusional zone from programmed cell death after traumatic cerebral contusion at distinct stages via non-genomic and genomic pathways.

Pericontusional zone (PCZ) of traumatic cerebral contusion is a target of pharmacological intervention. Our previous study indicated that 17beta-estradiol has a protective role in PCZ after traumatic cerebral contusion via the upregulation of estrogen receptor (ER) alpha mRNA induction and protein expression as well as inhibition of caspase-3 activation, suggesting that genomic signaling pathway is implicated in the protective effect of 17beta-estrodiol. Recent findings demonstrated that 17beta-estradiol also acts on the extranuclear/membrane ER to activate non-genomic signaling pathway to regulate cellular functions and exert the protective effect in the brain. It is still unclear how and whether genomic and non-genomic pathways of 17beta-estradiol are involved in the neuroprotection in PCZ. Our current study demonstrates that 17beta-estradiol activates ERK1/2 and Akt at the early stage and induces ERalpha and survivin mRNA at the late stage to modulate its protection via the suppression of caspase-3 activation in PCZ. These findings suggest that 17beta-estrodiol differentially plays its protective roles via genomic and non-genomic signaling pathways in PCZ after traumatic cerebral contusion.

Development of the nine X-STR loci typing system and genetic analysis in three nationality populations from China.

This study is to develop a new multiplex polymerase chain reaction (PCR) system that simultaneously amplifies the nine X-chromosome short tandem repeats loci in the same PCR reaction, and to explore their polymorphism and mutation rate among three nationality populations from China. These loci included DXS6854, DXS9902, DXS6809, GATA172D05, HPRTB, DXS7423, DXS6807, DXS8378, and DXS8377. The samples of 890 (484 males and 406 females) unrelated individuals from Guangdong Han population, Xinjiang Uigur, and Inner-Mongolia Mongol were successfully analyzed using this multiplex system. The allele frequencies and mutation rates of the nine loci were investigated, and the comparison of allele frequency distribution among different populations was performed. There were 87 alleles for all the loci, and six to 18 alleles for each locus observed by our new multiplex PCR system. Polymorphism information content was 0.4998-0.9101, and power of discrimination in females was 0.6518-0.9846. Five cases with mutation of above loci were detected in 5,310 meioses. Pair-wise comparisons of allele frequencies distribution showed significant differences for most loci among different populations. Our results indicate that this multiplex system is very useful for identification analysis, and that the information about polymorphism and mutation rate is necessary for forensic application in three nationality populations from China.

[Expression of EVEC in ovarian carcinoma and its biological significance].

OBJECTIVE: To investigate the expression of EVEC in ovarian carcinoma and explore its biological significance. METHODS: The expression of EVEC in 22 specimens of normal ovarian tissues and 63 specimens of ovarian cancers was detected by RT-PCR and Western blotting analysis, respectively. RESULTS: RT-PCR showed that the expression level of EVEC in stage I-II ovarian cancer (0.199 ± 0.014) was significantly higher than that in stage III-IV ovarian cancer (0.155 ± 0.015, P < 0.05), and significantly lower than that in normal ovarian tissues (0.415 ± 0.055, P < 0.05). There was no significant difference between the expression levels of EVEC in primary sites and that in corresponding metastatic sites of ovarian cancer (P > 0.05). Furthermore, the results of Western blot also showed that the protein expression level of EVEC in stage I-II ovarian cancer was also significantly lower than that in normal ovarian tissues (0.179 ± 0.026 vs. 0.543 ± 0.032, P < 0.05), and higher than that in stage III-IV ovarian cancer (0.179 ± 0.026 vs. 0.115 ± 0.023, P < 0.05). The EVEC expression level in the epiploic metastasis of stage I-II ovarian cancer was significantly higher than that of stage III-IV ovarian cancer (0.201 ± 0.028 vs. 0.101 ± 0.037, P < 0.05). The expression of EVEC in ovarian carcinoma had no correlation with age, pathologic classification and histological grade (P > 0.05). CONCLUSIONS: EVEC is closely related with carcinoma metastasis. The expression of EVEC in ovarian cancer and its metastatic sites was remarkably decreased. EVEC may play a negative role in the development and metastasis of ovarian cancer and may be a valuable marker in estimation of the prognosis for patients.

Overexpression of Arabidopsis CBF1 gene in transgenic tobacco alleviates photoinhibition of PSII and PSI during chilling stress under low irradiance.

A known arabidopsis cDNA clone, the CRT/DRE binding factor 1 (CBF1), was isolated and introduced into tobacco plants. It has been reported that CBF1 is one member of CBF gene family related to low temperature and enhancing low temperature tolerance of plants. In the present work, the transcripts could be detected in the transgenic lines. The photochemical efficiency of PSII (F(v)/F(m)) and the photo-oxidizable P700 in the transgenic lines overexpressing CBF1 were higher than that in the wild type plants during the chilling stress under low irradiance. Similarly, the higher NPQ, higher qf, lower Phi(NF), higher activity of SOD, and lower content of MDA were also detected in the transgenic tobacco lines. Additionally, higher expression levels of Nicotiana tabacum copper/zinc superoxide dismutase (Cu/Zn SOD) were also detected in the transgenic lines. These results suggest that CBF1 protein plays an important role in protection of PSII and PSI during the chilling stress under low irradiance.

[Effects of different calcium salts on freezing resistance of satsuma mandarin].

The study on the effects of foliar spraying 20 mmol x L(-1) of CaCl2, Ca (NO3)2 and CaAc2 on the freezing resistance of satsuma mandarin (Citrus unshiu Marc. cv. Guoqing No. 1) showed that after treated with these Ca salts, the leaves of test plant had a lower half lethal temperature (LT50) than the control (sprayed with distilled water). The LT50 after treated with CaCl2 was 0.54 degrees C lower, whereas that after treated with CaAc2 and Ca (NO3)2 was 1.34 degrees C and 1.35 degrees C lower, respectively, implying that the latter two Ca salts were more effective in enhancing the freezing resistance of satsuma mandarin. Moreover, foliar spraying Ca salts increased the superoxidase (SOD) and peroxidase (POD) activities and the contents of soluble proteins, soluble sugars and praline in leaves, and decreased the leaf MDA content.

[Mechanism and effect of selective cyclooxygenase-2 inhibitor NS-398 on human cervical carcinoma cells].

OBJECTIVE: To investigate the effect and mechanism of the selective COX-2 inhibitor NS-398 and carboplatin on the human cervical carcinoma cell line Hela. METHODS: The effect of NS-398, carboplatin, and both on the proliferation of Hela cells was assessed by methyl-thiazolyl tetrazolium (MTT) method, and the apoptosis assay and cell cycle distribution were analyzed by flow cytometry. RESULTS: NS-398, and carboplatin inhibited the growth of Hela cells in a dose and time-dependent manner. When combining carboplatin with NS-398, the combined inhibition rate was increased, which nearly equaled the inhibition rate of the double concentrations of carboplatin. Flow cytometry demonstrated that the cell cycle was redistributed: the G(1)-phase cell fraction was increased while the S-phase cell fraction was significantly decreased after the cells were treated with NS-398 (P<0.05), However,the result was just the opposite after being treated with carboplatin. The apoptotic rate was 1.48%+/-0.03% and 3.43%+/-0.02% for pre-treatment and post-treatment with NS-398 respectively (P>0.05) while the apoptotic rate was 9.32%+/-0.02% after the treatment with carboplatin (P<0.05). CONCLUSION: NS-398 can inhibit the growth of Hela cells. The effect of NS-398 on Hela cells may not be related to the apoptosis. NS-398 and carboplatin can bring about synergistic effect in chemotherapy on Hela cells.

Overexpression of CaHSP26 in transgenic tobacco alleviates photoinhibition of PSII and PSI during chilling stress under low irradiance.

A sweet pepper cDNA clone, CaHSP26 encoding the chloroplast (CP)-localized small heat shock protein (sHSP), was isolated and characterized with regard to its sequence, response to various temperatures and function in transgenic tobacco plants. The deduced amino acid sequence contained three highly conserved regions, showing high identities with other plant sHSPs. Expression of the CaHSP26 gene showed that the mRNA accumulation of CaHSP26 was induced by heat stress. Higher transcript levels were observed when sweet pepper leaves were treated at 42 degrees C for 3h. However, the expression of the CaHSP26 gene was not induced by chilling stress (4 degrees C) in the absence of heat shock (HS). But the transcripts were still detected at 48h at 4 degrees C after HS while not at 25 degrees C. The photochemical efficiency of PSII (Fv/Fm) and the oxidizable P700 in transgenic tobacco overexpressing CaHSP26 were higher than that in wild type tobacco during chilling stress under low irradiance. These results suggest that CP sHSP protein plays an important role in protection of PSII and PSI during chilling stress under low irradiance.