Multivariate analysis compares and evaluates drought and flooding tolerances of maize germplasm.

Drought and flooding are the two most important environmental factors limiting maize (Zea mays L.) production globally. This study aimed to investigate the physiological mechanisms and accurate evaluation indicators and methods of maize germplasm involved in drought and flooding stresses. The twice replicated pot experiments with 60 varieties, combined with the field validation experiment with 3 varieties, were conducted under well-watered, drought, and flooding conditions. Most varieties exhibited stronger tolerance to drought than flooding due to higher antioxidant enzyme activities, osmotic adjustment substances, and lower reactive oxygen species. In contrast, flooding stress resulted in higher levels of reactive oxygen species (particularly O2-), ascorbate peroxidase, catalase, peroxidase, and soluble sugars but lower levels of superoxide dismutase, proline, and soluble protein compared with well-watered conditions. Superoxide dismutase, peroxidase, catalase, ascorbate peroxidase, proline, soluble sugars, and protein contents, in addition to plant height, leaf area/plant, and stem diameter, were accurate and representative indicators for evaluating maize tolerance to drought and flooding stresses and could determine a relatively high mean forecast accuracy of 100.0% for the comprehensive evaluation value. A total of 4 principal components were extracted, in which different principal components played a vital role in resisting different water stresses. Finally, the accuracy of the 3 varieties screened by multivariate analysis was verified in the field. This study provides insights into the different physiological mechanisms and accurate evaluation methods of maize germplasm involved in drought and flooding stresses, which could be valuable for further research and breeding.

Straw return and nitrogen fertilization regulate soil greenhouse gas emissions and global warming potential in dual maize cropping system.

Abundant nitrogen (N) fertilization is needed for maize (Zea mays L.) production in China because of its huge residual biomass return. However, excessive N fertilization has a negative impact on the soil ecosystem and environment, which contributes to climate change. Soil incorporation of maize residues is a well-known practice for reducing chemical N fertilization without compromising maize yield and soil fertility. Thus, residues incorporation has the capacity to minimize N fertilization uses and hence mitigate soil greenhouse gas emissions by improving plant N uptake and use efficiency. There is still a research gap regarding the effects of maize residues incorporation on maize yield, soil fertility, greenhouse gas emissions, and plant N and carbon (C) contents. Therefore, we conducted a field experiment during spring and autumn involving four different N fertilization rates (N0, N200, N250, and N300 kg N ha-1), with and without maize residues incorporation, to evaluate grain yield, soil fertility, plant N and C contents, and greenhouse gas emissions (GHGs). Compared to N0, N fertilizer application at 300 kg N ha-1 with residues incorporation significantly increased area-scaled global warming potential (GWP) compared to other N fertilization rates in both spring and autumn seasons, but soil nutrient contents and plant N and C contents were not statistically different from the N250 treatment. In contrast, the N recovery use efficiency (NRUE), physiological N use efficiency (PNUE), and agronomic N use efficiency (ANUE) were significantly lower in the N300 treatment than in the lower N treatment groups. Nitrous oxide (N2O) and carbon dioxide (CO2) fluxes, area-scaled GWP, and greenhouse gas intensity (GHGI) were significantly lower in the N200 treatment with straw incorporation than the N250 and N300 treatments of the traditional planting system. Thus, we concluded that N200 treatment with residues incorporation is optimal for improving grain yield, soil fertility, plant N uptake, and mitigating greenhouse gas emissions.

Down-regulation of kappa opioid receptor promotes ESCC proliferation, invasion and metastasis via the PDK1-AKT signaling pathway.

BACKGROUND: As a class of the opioid receptors, the kappa opioid receptor (KOR) has been verified to be a potential biomarker and therapeutic target for human malignant tumors. However, a thorough understanding of whether KOR affects progression of esophageal squamous cell carcinoma (ESCC) is still lacking. This study focused on exploring the effect of knocking down KOR in ESCC and its underlying mechanism. METHODS: Bioinformatics analysis was used to compare the different expression level of OPRK1 (KOR gene) in tumor and adjacent normal tissues, and predict the relationship between KOR expression and overall survival. RNA-sequence analysis was performed to detect the altered functions and mechanisms after down regulating KOR. The in vitro and in vivo assays were used to detect the effects of down-regulated KOR on cell proliferation, migration and invasion. Substrate gel zymography and 3D cell culture assays were used to find the effect of KOR knockdown on the degradation of extracellular matrix (ECM), and immunefluorescence was performed to detect the altered cytoskeleton. Western blotting and immunohistochemistry were used to explore the underlying mechanism pathway. RESULTS: Bioinformatics analysis revealed that the expression of OPRK1 was lower in tumor tissue than that in adjacent normal tissues, and lowered expression of KOR was associated with poorer overall survival. The in vitro assays demonstrated that down-regulation of KOR enhanced ESCC proliferation, metastasis and invasion. Western blotting revealed that down-regulation of KOR could activate PDK1-AKT signaling pathway, which actively regulated the cancer progression. Down-regulation of KOR enhanced the formation of invadopodia, secretion of matrix metalloproteinase-2 (MMP2) and rearrangement of cytoskeleton, which were positively related with the invasion of ESCC. KOR knockdown enhanced the tumor invasion and elevated the AKT phosphorylation in nude mice. The AKT kinase inhibition could reverse the effect of down-regulation of KOR. CONCLUSION: KOR might act as a tumor suppressor in ESCC and down-regulation of KOR could enhance the ESCC tumor phenotype. Video Abstract.

Interactive Effects of Melatonin and Nitrogen Improve Drought Tolerance of Maize Seedlings by Regulating Growth and Physiochemical Attributes.

Melatonin plays an important role in numerous vital life processes of animals and has recently captured the interests of plant biologists because of its potent role in plants. As well as its possible contribution to photoperiodic processes, melatonin is believed to act as a growth regulator and/or as a direct free radical scavenger/indirect antioxidant. However, identifying a precise concentration of melatonin with an optimum nitrogen level for a particular application method to improve plant growth requires identification and clarification. This work establishes inimitable findings by optimizing the application of melatonin with an optimum level of nitrogen, alleviating the detrimental effects of drought stress in maize seedlings. Maize seedlings were subjected to drought stress of 40-45% field capacity (FC) at the five-leaf stage, followed by a soil drenching of melatonin 100 µM and three nitrogen levels (200, 250, and 300 kg ha-1) to consider the changes in maize seedling growth. Our results showed that drought stress significantly inhibited the physiological and biochemical parameters of maize seedlings. However, the application of melatonin with nitrogen remarkably improved the plant growth attributes, chlorophyll pigments, fluorescence, and gas exchange parameters. Moreover, melatonin and nitrogen application profoundly reduced the reactive oxygen species (ROS) accumulation by increasing maize antioxidant and nitrogen metabolism enzyme activities under drought-stress conditions. It was concluded that the mitigating potential of 100 µM melatonin with an optimum level of nitrogen (250 kg N ha-1) improves the plant growth, photosynthetic efficiency, and enzymatic activity of maize seedling under drought-stress conditions.

Melatonin and KNO3 Application Improves Growth, Physiological and Biochemical Characteristics of Maize Seedlings under Waterlogging Stress Conditions.

Waterlogging is one of the serious abiotic stresses that inhibits crop growth and reduces productivity. Therefore, investigating efficient waterlogging mitigation measures has both theoretical and practical significance. The objectives of the present research were to examine the efficiency of melatonin and KNO3 seed soaking and foliar application on alleviating the waterlogging inhibited growth performance of maize seedlings. In this study, 100 µM melatonin and different levels (0.25, 0.50 and 0.75 g) of potassium nitrate (KNO3) were used in seed soaking and foliar applications. For foliar application, treatments were applied at the 7th leaf stage one week after the imposition of waterlogging stress. The results showed that melatonin with KNO3 significantly improved the plant growth and biochemical parameters of maize seedlings under waterlogging stress conditions. However, the application of melatonin with KNO3 treatments increased plant growth characteristics, chlorophyll content, and the net photosynthetic rate at a variable rate under waterlogging stress. Furthermore, melatonin with KNO3 treatments significantly reduced the accumulation of hydrogen peroxide (H2O2) and malondialdehyde (MDA), and it decreased the activity of pyruvate decarboxylase and alcohol dehydrogenase, while increasing enzymatic activities and soluble protein content of maize seedlings under waterlogging stress conditions. Overall, our results indicated that seed soaking with 100 µM melatonin and 0.50 g KNO3 was the most effective treatment that significantly improved the plant growth characteristics, chlorophyll content, photosynthetic rate, and enzymatic activity of maize seedling under waterlogging conditions.

Ameliorative effect of melatonin improves drought tolerance by regulating growth, photosynthetic traits and leaf ultrastructure of maize seedlings.

BACKGROUND: Melatonin is considered a potential plant growth regulator to enhance the growth of plants and increase tolerance to various abiotic stresses. Nevertheless, melatonin's role in mediating stress response in different plant species and growth cycles still needs to be explored. This study was conducted to understand the impact of different melatonin concentrations (0, 50, 100, and 150 µM) applied as a soil drench to maize seedling under drought stress conditions. A decreased irrigation approach based on watering was exposed to maize seedling after drought stress was applied at 40-45% of field capacity. RESULTS: The results showed that drought stress negatively affected the growth behavior of maize seedlings, such as reduced biomass accumulation, decreased photosynthetic pigments, and enhanced the malondialdehyde and reactive oxygen species (ROS). However, melatonin application enhanced plant growth; alleviated ROS-induced oxidative damages by increasing the photosynthetic pigments, antioxidant enzyme activities, relative water content, and osmo-protectants of maize seedlings. CONCLUSIONS: Melatonin treatment also enhanced the stomatal traits, such as stomatal length, width, area, and the number of pores under drought stress conditions. Our data suggested that 100 µM melatonin application as soil drenching could provide a valuable foundation for improving plant tolerance to drought stress conditions.

Laparoscopic Sacrocolpopexy With a Mesh for Sigmoid Neovaginal Prolapse: A Case Report.

BACKGROUND: Creating a functional neovagina is a practical therapeutic intervention for women with congenital vaginal agenesis and sexual needs. Although the incidence of neovaginal prolapse (NP) is low, it is inconvenient for patients and is a challenging problem for gynecologists. CASE: A 32-year-old woman who had undergone transabdominal sigmoid vaginoplasty 10 years previously at another hospital visited our clinic for evaluation and treatment of NP. Gynecological examination showed exstrophy of the vaginal apex, 4 cm beyond the hymen. Laparoscopic sacrocolpopexy was performed using a mesh. The mesh was sutured at the anterior wall and apex of the neovagina and suspended in the anterior sacral region without blood vessels. SUMMARY AND CONCLUSION: Laparoscopic sacrocolpopexy might be an effective and safe treatment for NP.

Construction of an anchoring SSR marker genetic linkage map and detection of a sex-linked region in two dioecious populations of red bayberry.

Red bayberry (Morella rubra) is an evergreen fruit tree found in southern China whose whole-genome sequence has recently been published. We updated the linkage map of the species by adding 118 SSR markers and the female-specific marker MrFT2_BD-SEX. The integrated map included eight linkage groups and spanned 491 cM. Eleven sex-associated markers were identified, six of which were located in linkage group 8, in agreement with the previously reported location of the sex-determining region. The MrFT2_BD-SEX marker was genotyped in 203 cultivated accessions. Among the females of the accessions, we found two female-specific alleles, designated W-b (151 bp) and W-d (129 bp). We previously found that 'Dongkui', a female cultivar, could produce viable pollen (we refer to such plants 'Dongkui-male') and serve as the paternal parent in crosses. The genotypes of the MrFT2_BD-SEX marker were W-b/Z in 'Biqi' and W-d/Z in 'Dongkui-male'. The progeny of a cross between these parents produced a 3:1 female (W-) to male (ZZ) ratio and the expected 1:1:1:1 ratio of W-b/W-d: W-b/Z: W-d/Z: Z/Z. In addition, the flowering and fruiting phenotypes of all the F1 progeny fit their genotypes. Our results confirm the existence of ZW sex determination and show that the female phenotype is controlled by a single dominant locus (W) in a small genomic region (59 kb and less than 3.3 cM). Furthermore, we have produced a homozygous "super female" (WW) that should produce all-female offspring in the F2 generation, providing a foundation for commercial use and presenting great potential for use in modern breeding programs.

Genome-wide identification and analysis of the MADS-box gene family and its potential role in fruit development and ripening in red bayberry (Morella rubra).

The MADS-box gene family encodes transcription factors and plays an important role in plant growth and the development of flower and fruit. A perennial dioecious plant, the red bayberry genome has been published recently, providing the opportunity to analyze the MADS-box gene family and its role in fruit development and ripening. Here, we identified 54 MADS-box genes in the red bayberry genome, and classified them into two types based on phylogenetic analysis. Thirteen Type I MADS-box genes were subdivided into three subfamilies and 41 Type II MADS-box genes into 13 subfamilies. A total of 46 MADS-box genes were distributed across eight red bayberry chromosomes, and the other eight genes were located on the unmapped scaffolds. Transcriptome analysis suggested that the expression of most Type II genes was higher than Type I in five female tissues. Moreover, 26 MADS-box genes were expressed during red bayberry fruit development and ten of them showed high expression. qRT-PCR showed that the expression of MrMADS01 (SEP, MIKCC), with differences between the pale pink and red varieties, increased significantly at the final ripening stage, suggesting it may participate in ripening as positive regulator and related to anthocyanin biosynthesis. These results provide some clues for future study of MADS-box genes in red bayberry, especially in ripening process.

High-density genetic map construction and QTL mapping of first flower node in pepper (Capsicum annuum L.).

BACKGROUND: First flower node (FFN) is an important trait for evaluating fruit earliness in pepper (Capsicum annuum L.). The trait is controlled by quantitative trait loci (QTL); however, studies have been limited on QTL mapping and genes contributing to the trait. RESULTS: In this study, we developed a high density genetic map using specific-locus amplified fragment sequencing (SLAF-seq), a high-throughput strategy for de novo single nucleotide polymorphism discovery, based on 146 recombinant inbred lines (RILs) derived from an intraspecific cross between PM702 and FS871. The map contained 9328 SLAF markers on 12 linkage groups (LGs), and spanned a total genetic distance of 2009.69 centimorgan (cM) with an average distance of 0.22 cM. The sequencing depth for the map was 72.39-fold in the male parent, 57.04-fold in the female parent, and 15.65-fold in offspring. Using the genetic map, two major QTLs, named Ffn2.1 and Ffn2.2, identified on LG02 were strongly associated with FFN, with a phenotypic variance explanation of 28.62 and 19.56%, respectively. On the basis of the current annotation of C. annuum cv. Criollo de Morelos (CM334), 59 candidate genes were found within the Ffn2.1 and Ffn2.2 region, but only 3 of 59 genes were differentially expressed according to the RNA-seq results. Eventually we identified one gene associated with the FFN based on the function through GO, KEGG, and Swiss-prot analysis. CONCLUSIONS: Our research showed that the construction of high-density genetic map using SLAF-seq is a valuable tool for fine QTL mapping. The map we constructed is by far the most saturated complete genetic map of pepper, and using it we conducted fine QTL mapping for the important trait, FFN. QTLs and candidate genes obtained in this study lay a good foundation for the further research on FFN-related genes and other genetic applications in pepper.

The red bayberry genome and genetic basis of sex determination.

Morella rubra, red bayberry, is an economically important fruit tree in south China. Here, we assembled the first high-quality genome for both a female and a male individual of red bayberry. The genome size was 313-Mb, and 90% sequences were assembled into eight pseudo chromosome molecules, with 32 493 predicted genes. By whole-genome comparison between the female and male and association analysis with sequences of bulked and individual DNA samples from female and male, a 59-Kb region determining female was identified and located on distal end of pseudochromosome 8, which contains abundant transposable element and seven putative genes, four of them are related to sex floral development. This 59-Kb female-specific region was likely to be derived from duplication and rearrangement of paralogous genes and retained non-recombinant in the female-specific region. Sex-specific molecular markers developed from candidate genes co-segregated with sex in a genetically diverse female and male germplasm. We propose sex determination follow the ZW model of female heterogamety. The genome sequence of red bayberry provides a valuable resource for plant sex chromosome evolution and also provides important insights for molecular biology, genetics and modern breeding in Myricaceae family.

Genetic diversity of male and female Chinese bayberry (Myrica rubra) populations and identification of sex-associated markers.

BACKGROUND: Chinese bayberry (Myrica rubra Sieb. & Zucc.) is an important subtropical evergreen fruit tree in southern China. Generally dioecious, the female plants are cultivated for fruit and have been studied extensively, but male plants have received very little attention. Knowledge of males may have a major impact on conservation and genetic improvement as well as on breeding. Using 84 polymorphic SSRs, we genotyped 213 M. rubra individuals (99 male individuals, 113 female varieties and 1 monoecious) and compared the difference in genetic diversity between the female and the male populations. RESULTS: Neighbour-joining cluster analysis separated M. rubra from three related species, and the male from female populations within M. rubra. By structure analysis, 178 M. rubra accessions were assigned to two subpopulations: Male dominated (98) and Female dominated (80). The well-known cultivars 'Biqi' and 'Dongkui', and the landraces 'Fenhong' are derived from three different gene pools. Female population had a slightly higher values of genetic diversity parameters (such as number of alleles and heterozygosity) than the male population, but not significantly different. The SSR loci ZJU062 and ZJU130 showed an empirical Fst value of 0.455 and 0.333, respectively, which are significantly above the 95 % confidence level, indicating that they are outlier loci related to sex separation. CONCLUSION: The male and female populations of Chinese bayberry have similar genetic diversity in terms of average number of alleles and level of heterozygosity, but were clearly separated by genetic structure analysis due to two markers associated with sex type, ZJU062 and ZJU130. Zhejiang Province China could be the centre of diversity of M. rubra in China, with wide genetic diversity coverage; and the two representative cultivars 'Biqi' and 'Dongkui', and one landrace 'Fenhong' in three female subpopulations. This research provides genetic information on male and female Chinese bayberry and will act as a reference for breeding programs.

Effect of human umbilical cord mesenchymal stem cells transplantation on nerve fibers of a rat model of endometriosis.

BACKGROUND: Endometriosis is a common, benign, oestrogen-dependent, chronic gynaecological disorder associated with pelvic pain and infertility. Some researchers have identified nerve fibers in endometriotic lesions in women with endometriosis. Mesenchymal stem cells (MSCs) have attracted interest for their possible use for both cell and gene therapies because of their capacity for self-renewal and multipotentiality of differentiation. We investigated how human umbilical cord-MSCs (hUC-MSCs) could affect nerve fibers density in endometriosis. MATERIALS AND METHODS: In this experimental study, hUC-MSCs were isolated from fresh human umbilical cord, characterized by flow cytometry, and then transplanted into surgically induced endometriosis in a rat model. Ectopic endometrial implants were collected four weeks later. The specimens were sectioned and stained immunohistochemically with antibodies against neurofilament (NF), nerve growth factor (NGF), NGF receptor p75 (NGFRp75), tyrosine kinase receptor-A (Trk-A), calcitonin gene-related peptide (CGRP) and substance P (SP) to compare the presence of different types of nerve fibers between the treatment group with the transplantation of hUC-MSCs and the control group without the transplantation of hUC-MSCs. RESULTS: There were significantly less nerve fibers stained with specific markers we used in the treatment group than in the control group (p<0.05). CONCLUSION: MSC from human umbilical cord reduced nerve fiber density in the treatment group with the transplantation of hUC-MSCs.

Development of 107 SSR markers from whole genome shotgun sequences of Chinese bayberry (Myrica rubra) and their application in seedling identification.

Chinese bayberry (Myrica rubra Sieb. et Zucc.) is one of the important subtropical fruit crops native to the South of China and Asian countries. In this study, 107 novel simple sequence repeat (SSR) molecular markers, a powerful tool for genetic diversity studies, cultivar identification, and linkage map construction, were developed and characterized from whole genome shotgun sequences. M13 tailing for forward primers was applied as a simple method in different situations. In total, 828 alleles across 45 accessions were detected, with an average of 8 alleles per locus. The number of effective alleles ranged from 1.22 to 10.41 with an average of 4.08. The polymorphic information content (PIC) varied from 0.13 to 0.89, with an average of 0.63. Moreover, these markers could also be amplified in their related species Myrica cerifera (syn. Morella cerifera) and Myrica adenophora. Seventy-eight SSR markers can be used to produce a genetic map of a cross between 'Biqi' and 'Dongkui'. A neighbor-joining (NJ) tree was constructed to assess the genetic relationships among accessions, and the elite accessions 'Y2010-70', 'Y2012-140', and 'Y2012-145', were characterized as potential new genotypes for cultivation.

Effect of siRNA against ß-NGF on nerve fibers of a rat model with endometriosis.

OBJECTIVE: This study examines whether silencing specific ß-nerve growth factor small interfering RNA (ß-NGF siRNA) can affect the growth of ectopic endometriotic implants, generalized hyperalgesia, and nerve fiber density in endometriosis. METHODS: Four specific ß-NGF siRNAs were detected by Western blot analysis, and the most efficient specific siRNA was transferred into rats with surgically induced endometriosis through gene transfer. The length × width × height of each ectopic transplant that survived from 2 groups were measured at pre-and postbombardment after 2 weeks. The transplants were collected 2 weeks after bombardment. Warm-water tail flick test was performed before the rats were sacrificed. The specimens were sectioned and stained immunohistochemically with antibodies against the types of nerve fibers to compare the presence of different nerve fibers in the treatment and control groups. The serums and supernatants of the peritoneal washings in the treatment and control groups were collected for enzyme-linked immunosorbent assay (ELISA) analysis. The extra rats were successfully induced with endometriosis and through gene transfer as described above. The spherical volumes of the transplants and tail flick latency post-bombardment after 4, 6, 8, and 10 weeks were measured. RESULTS: The spherical volumes in the treatment group were much smaller than those in the control group, and tail flick latency significantly increased in the treatment group postbombardment after 2 weeks. The ELISA analysis showed that the concentrations of ß-NGF in the serums and supernatants of the peritoneal fluid decreased in the treatment group unlike in the control group. Less sympathetic and sensory innervation was observed in the treatment group postbombardment after 2 weeks. The outcomes of the spherical volumes of the transplants and tail flick latency postbombardment after 4, 6, 8, and 10 weeks showed that the sizes of the transplants did not return to their previous size and that the treatment had some effects on generalized hyperalgesia. CONCLUSION: Specific siRNA-mediated silencing of the ß-NGF gene expression after gene transfer suppressed the growth of ectopic endometriotic implants resulted in a significant improvement in generalized hyperalgesia as well as reduced sympathetic and sensory nerve fiber density in the treatment group.

Development of simple sequence repeat (SSR) markers from a genome survey of Chinese bayberry (Myrica rubra).

BACKGROUND: Chinese bayberry (Myrica rubra Sieb. and Zucc.) is a subtropical evergreen tree originating in China. It has been cultivated in southern China for several thousand years, and annual production has reached 1.1 million tons. The taste and high level of health promoting characters identified in the fruit in recent years has stimulated its extension in China and introduction to Australia. A limited number of co-dominant markers have been developed and applied in genetic diversity and identity studies. Here we report, for the first time, a survey of whole genome shotgun data to develop a large number of simple sequence repeat (SSR) markers to analyse the genetic diversity of the common cultivated Chinese bayberry and the relationship with three other Myrica species. RESULTS: The whole genome shotgun survey of Chinese bayberry produced 9.01Gb of sequence data, about 26x coverage of the estimated genome size of 323 Mb. The genome sequences were highly heterozygous, but with little duplication. From the initial assembled scaffold covering 255 Mb sequence data, 28,602 SSRs (≥5 repeats) were identified. Dinucleotide was the most common repeat motif with a frequency of 84.73%, followed by 13.78% trinucleotide, 1.34% tetranucleotide, 0.12% pentanucleotide and 0.04% hexanucleotide. From 600 primer pairs, 186 polymorphic SSRs were developed. Of these, 158 were used to screen 29 Chinese bayberry accessions and three other Myrica species: 91.14%, 89.87% and 46.84% SSRs could be used in Myrica adenophora, Myrica nana and Myrica cerifera, respectively. The UPGMA dendrogram tree showed that cultivated Myrica rubra is closely related to Myrica adenophora and Myrica nana, originating in southwest China, and very distantly related to Myrica cerifera, originating in America. These markers can be used in the construction of a linkage map and for genetic diversity studies in Myrica species. CONCLUSION: Myrica rubra has a small genome of about 323 Mb with a high level of heterozygosity. A large number of SSRs were identified, and 158 polymorphic SSR markers developed, 91% of which can be transferred to other Myrica species.

Biological characteristics of human placental mesenchymal stem cells and their proliferative response to various cytokines.

The placenta is an attractive new source of mesenchymal stem cells (MSCs), but the biological characteristics of placenta-derived MSCs (P-MSCs) have not yet been characterized. We successfully isolated, cultured and expanded P-MSCs using routine methods. Under appropriate induction conditions, these cells can differentiate into bone, cartilage, fat and hepatocyte-like cells. In addition, the proliferative response of P-MSCs to different cytokines was monitored using the MTT assay. The results show that low concentrations of proinflammatory cytokines, e.g. RANTES, interleukin (IL)-1, IL-6 and IL-8 can stimulate the proliferation of P-MSCs in a dose-dependent manner, peaking at concentrations of 40 ng/ml of RANTES, 10 ng/ml of IL-1 and IL-6, and 150 ng/ml of IL-8 (p < 0.01). The level of proliferation decreased when the concentration of these four cytokines increased beyond these values. On the other hand, anti-inflammatory cytokines hepatocyte growth factor and IL-4 had an inhibitory effect on P-MSCs. In conclusion, the placenta contains MSCs that are consistent with the characteristics of bone marrow MSCs. Low concentrations of proinflammatory chemokines stimulated the proliferation of P-MSCs while anti-inflammatory cytokines inhibited the growth of P-MSCs in a dose-dependent manner.

[Changes in respiratory rate, ethylene production rate and quality of postharvest Chinese bayberry fruits with different maturities].

Harvested fruits of three Chinese bayberry (Myrica rubra Sieb. & Zucc.) varieties, i.e. "Biqi", "Dongkui" and "Zaodamei" which were divided into three maturities (designated as "Immature", "Mature" and "Ripe") according to fruit colour, were investigated for the changes in climacteric pattern and quality at 20 degrees C. Respiration rate and ethylene production rate were underwent 3 h during 48 h storage. Our result showed that both Immature and Mature fruits underwent rises in respiration and ethylene production rate of a climacteric rise, but no such peak was observed in Ripe fruit (Fig.1 and 2). Total soluble solids (TSS) contents increased with maturity and decreased over the 48 h at 20 degrees C (Fig.3); titratable acidity (TA) decreased with the maturity and throughout 48 h storage period (Fig.4). In "Biqi" Chinese bayberry fruit, PAL activities increased in Immature and Mature fruit, but, it decreased in Ripe fruit during the storage period; the change in Cy-3-Glu with fruit ripening was consistent with PAL activities (Table 1); there was significant positive correlation between CIRG (Color Index for Red Grape) values and Cy-3-Glu content (r=0.96**). This study provides important information on the postharvest behaviour of Chinese bayberry fruit, and our result shows that it is climacteric fruit.