The association between platelet glycoprotein-specific antibodies and response to short-term high-dose dexamethasone with prednisone maintenance treatment in adult patients with primary immune thrombocytopenia.

OBJECTIVE: The aim of the present study was to detect the association between platelet glycoprotein-specific autoantibodies and the patient response to short-term high-dose dexamethasone (HD-DXM) + prednisone maintenance treatment. METHODS: The data from 112 adult patients newly diagnosed with ITP who were administered first-line HD-DXM + prednisone maintenance therapy between January 2016 and January 2021 were retrospectively analyzed. RESULTS: A total of 72 patients positive for platelet glycoprotein-specific antibodies were enrolled in the antibody-positive group, and 40 patients not positive for platelet glycoprotein-specific antibodies were enrolled in the antibody-negative group. In the antibody-positive group, six platelet glycoprotein-specific antibody types were found: 41.67% of the patients were anti-GP IIb/IIIa-positive only, 5.56% were anti-GP Ib/IX-positive only, 5.56% were anti-P-selectin-positive only, 19.44% were anti-GP IIb/IIIa- and anti-GP Ib/IX-positive, 16.67% were anti-GP Ib/IX- and P-selectin-positive and 11.11% were positive for all three antibodies. There was no significant difference in the overall response rate between the antibody-positive group and the antibody-negative group (94.44 versus 80.00%, p = .221). However, the CR rate was significantly higher in the antibody-positive group than in the antibody-negative group (69.44% versus 40.00%, p = .032). The logistic regression analysis revealed that platelet glycoprotein-specific antibody positivity and age were two factors that could affect patient response. CONCLUSIONS: The present study discovered that adult patients newly diagnosed with ITP who had positive platelet glycoprotein-specific antibody test results were likely to achieve a better response after treatment with HD-DXM + prednisone maintenance.

Isolation and expression analysis of two novel C-repeat binding factor (CBF) genes involved in plant growth and abiotic stress response in mangrove Kandelia obovata.

Kandelia obovata is one of the cold tolerant mangrove plants along the China coast. To reveal the cold tolerant mechanism of K. obovata, the present work isolated two CBF/DREB1 genes (designated KoCBF1 and KoCBF3) from cold-stressed K. obovata and characterized their expression profiles in various organs and in response to multiple abiotic stresses. The deduced proteins of KoCBF1 and 3 all contain specific features of CBFs, and show high similarity to AmCBF1 and 3 from Avicennia marina, respectively. Different expression patterns of the two CBF orthologous under various abiotic stresses and exogenous hormone suggested that they may have different regulators and be involved in different regulatory pathway. The high basal and cold induced expression of the two genes indicated that they may all play important roles in growth and cold resistance of plants. The significant induction of KoCBF3 after salt and lead (Pb2+) treatments suggested that this CBF gene may also participate in response to salinity and heavy metal stresses. This study will provide a better understanding of CBF-regulated stress-resistant mechanism, which may be benefit in mangrove biotechnological breeding, high-latitude transplanting, and bioremediation of heavy metal pollutions.

Isolation and expression analysis of a CBF transcriptional factor gene from the mangrove Bruguiera gymnorrhiza.

The present work isolated a CBF/DREB1 gene from mangrove Bruguiera gymnorrhiza (BgCBF1) and compared its expression levels in various tissues under normal condition and cold stress, and in leaves exposed to various environmental stimuli. Results showed that the BgCBF1 deduced protein showed almost 100% similarities to that of AcCBF1 from Aegiceras corniculatum and AmCBF1 from Avicennia marina. Real-time quantitative PCR analysis showed that BgCBF1 gene displayed constitute expression in leaf, stem and root samples of plantlets under normal condition, but with different expression levels and tissue preference. When exposed to cold, BgCBF1 could be rapidly, slightly and transiently induced in all tissues. Furthermore, the BgCBF1 gene in leaves displayed a transient and small induction after salt and drought (PEG) exposure, while exhibited relatively high up-regulated expression after the phytohormone abscisic acid (ABA) treatment. These results suggest that the BgCBF1 gene may participate in the ABA mediated development and protection of plant against cold and drought. Further studies on its promoters and downstream genes will be needed to better understand its functions.

Identification of suitable reference genes in mangrove Aegiceras corniculatum under abiotic stresses.

Gene expression studies could provide insight into the physiological mechanisms and strategies used by plants under stress conditions. Selection of suitable internal control gene(s) is essential to accurately assess gene expression levels. For the mangrove plant, Aegiceras corniculatum, reliable reference genes to normalize real-time quantitative PCR data have not been previously investigated. In this study, the expression stabilities of five candidate reference genes [glyceraldehydes-3-phosphate dehydrogenase (GAPDH), 18SrRNA, ß-Actin, 60S ribosomal protein L2, and elongation factor-1-A] were determined in leaves of A. corniculatum treated by cold, drought, salt, heavy metals, and pyrene and in different tissues of A. corniculatum under normal condition. Two software programs (geNorm and NormFinder) were employed to analyze and rank the tested genes. Results showed that GAPDH was the most suitable reference gene in A. corniculatum and the combination of two or three genes was recommended for greater accuracy. To assess the value of these tested genes as internal controls, the relative quantifications of CuZnSOD gene were also conducted. Results showed that the relative expression levels of CuZnSOD gene varied depending on the internal reference genes used, which highlights the importance of the choice of suitable internal controls in gene expression studies. Furthermore, the results also confirmed that GAPDH was a suitable reference gene for qPCR normalization in A. corniculatum under abiotic stresses. Identification of A. corniculatum reference gens in a wide range of experimental samples will provide a useful reference in future gene expression studies in this species, particularly involving similar stresses.

Characterization and expression analysis of a gene encoding CBF/DREB1 transcription factor from mangrove Aegiceras corniculatum.

Several transcription factors play important roles in survival of plants under cold, drought and salt stresses by serving as master regulator of sets of downstream stress-responsive genes. A gene encoding CBF/DREB1 transcription factor (C-repeat binding factor/dehydration responsive element-binding factor 1) was isolated from mangrove Aegiceras corniculatum and designated AcCBF1. The full-length cDNA of AcCBF1 was 896 bp containing 618 bp ORF encoding a protein of 205 amino acids. Multiple sequence analysis showed that the corresponding protein had 100 % identity to AmCBF1 (KC776908) from mangrove Avicennia marina, and contains an AP2/ERE DNA-binding domain and two CBF signature sequences. Expression analyses based on quantitative real-time PCR revealed that the AcCBF1 gene was expressed in all tissues of A. corniculatum under normal condition with the highest expression level detected in leaves. When exposed to abiotic stresses, AcCBF1 gene showed different expression patterns in different tissues. Generally, AcCBF1 gene could be rapidly and strongly induced by cold and drought, while slightly induced by abscisic acid and salinity. Furthermore, light could positively regulate the cold-induction level of AcCBF1. These results suggest that the AcCBF1 may be playing important role in the signaling pathway of cold stress and also involved in the cross-talk among abiotic stresses. Further studies focusing on the promotors and downstream stress-responsive genes of AcCBF1 will help to better understand the regulatory mechanisms of mangrove A. corniculatum under abiotic stresses.

Ecophysiological differences between three mangrove seedlings (Kandelia obovata, Aegiceras corniculatum, and Avicennia marina) exposed to chilling stress.

Although the cold-resistant ability of mangroves varies greatly with species, the physiological mechanism remains unclear. The chilling stress effects on morphological changes, photosynthetic pigments, reactive oxygen species (ROS), malondialdehyde (MDA) and several antioxidants, were studied in leaves of three mangrove seedlings (Kandelia obovata, Aegiceras corniculatum and Avicennia marina). Results showed that both K. obovata and A. corniculatum exhibited lighter chilling damage, lower chilling injury rates and higher survival rates compared to A. marina. Reductions of chlorophylls (Chls) were observed in all the three mangroves, and the highest was detected in A. marina. Significant increases in content of ROS (hydrogen peroxide, H2O2; hydroxyl radicals, OH⋅) and MDA were observed in both A. marina and A. corniculatum, whereas chilling stressed K. obovata showed a decrease in H2O2 content, constant OH⋅ level and instantaneous increase of MDA. The contents of proline and water-soluble protein exhibited similar stress-time dependent increases in all mangroves, while A. corniculatum showed the highest increase of proline and relatively higher increase of water-soluble protein. The catalase activities significantly decreased with stress time in all mangroves, while K. obovata showed the least reduction. An increase in ascorbic acid (AsA) content and activities of superoxide dismutase, peroxidase (POD), and ascorbate peroxidase (APX) were also detected in all the three mangroves, while K. obovata showed the highest increases. These results indicate that chilling-tolerance of mangroves is associated with the efficiency of antioxidants, as confirmed by principal component analysis. The AsA, APX and POD in K. obovata may play more important role in control of oxidative stresses than those in the other two species. Furthermore, the higher cold-resistance of A. corniculatum compared to A. marina may be partly associated with its higher proline accumulation. The results indicate that enzymatic and non-enzymatic antioxidants (POD, APX, AsA, proline and Car) play key roles in scavenging of excess ROS in mangroves. Further studies focusing on these stress-responsive genes will enable better understanding of the cold-resistance mechanism from molecular level.

Bacterial polycyclic aromatic hydrocarbon ring-hydroxylating dioxygenases in the sediments from the Pearl River estuary, China.

Bacterial community compositions were characterized using denaturing gradient gel electrophoresis analysis of bacterial 16S rRNA gene in the sediments of the Pearl River estuary. Sequencing analyses of the excised bands indicated that Gram-negative bacteria, especially Gammaproteobacteria, were dominant in the Pearl River estuary. The diversity of polycyclic aromatic hydrocarbon ring-hydroxylating dioxygenase (PAH-RHD) gene in this estuary was then assessed by clone library analysis. The phylogenetic analyses showed that all PAH-RHD gene sequences of Gram-negative bacteria (PAH-RHD[GN]) were closely related to the nagAc gene described for Ralstonia sp. U2 or nahAc gene for Pseudomonas sp. 9816-4, while the PAH-RHD gene sequences of Gram-positive bacteria (PAH-RHD[GP]) at sampling site A1 showed high sequence similarity to the nidA gene from Mycobacterium species. Meanwhile, molecular diversity of the two functional genes was higher at the upstream of this region, while lower at the downstream. Redundancy analysis indicated that environmental factors, such as NH4--N, ∑PAHs, pH, SiO3--Si, and water depth, affected the distribution of the PAH-RHD[GN] gene in the Pearl River estuary.

Characterization and expression analysis of three CBF/DREB1 transcriptional factor genes from mangrove Avicennia marina.

Three CBF/DREB1 (C-repeat binding factor/dehydration responsive element-binding factor 1) homologues were isolated from mangrove Avicennia marina and designated AmCBF1, 2 and 3. Multiple sequence analysis showed that the three deduced proteins all contain an AP2 DNA-binding domain and two CBF signature sequences. According to the phylogenetic analysis, these proteins belong to the A-1 subgroup of the DREB subfamily. Expression analyses based on quantitative real-time PCR revealed that the AmCBF2 displayed relatively high expression under normal conditions, with the highest level in stems, while both AmCBF1 and 3 were weakly expressed without stress. The three genes also showed different responses to various environmental stimuli. The AmCBF2 was inducible by cold, drought, high salinity, heavy metals, as well as abscisic acid (ABA), and exhibited much stronger induction by cold, drought, Pb(2+) or Zn(2+) than by NaCl, ABA or Cd(2+). In contrast, both AmCBF1 and AmCBF3 displayed insignificant changes under these stimuli. These results indicate that the three AmCBF genes play different roles in A. marina and the AmCBF2 might be involved in the signaling pathway of cold, drought and heavy metal stress response.

Effects of three different PAHs on nitrogen-fixing bacterial diversity in mangrove sediment.

Polycyclic aromatic hydrocarbons (PAHs) are of great environmental and human health concerns due to their widespread occurrence, persistence and carcinogenic properties. There is now compelling evidence that the mangrove sediment microbial structure is susceptible to PAHs contamination. The study aimed to assess the effects of PAHs on the nitrogen-fixing bacterial community of mangrove sediment. Three types of PAHs, naphthalene (NAP), a two-ring PAH; fluorene (FLU), a three-ring PAH; and pyrene (PYR), a four-ring PAH; were applied at three doses. After 7 and 24 days of incubation, the nitrogen-fixing bacterial population and diversity were evidenced in the nifH gene polymerase chain reaction denaturing gradient gel electrophoresis profile. DGGE pattern shows that the nitrogen-fixing bacterial community changed significantly with the types and doses of PAHs, and the incubation time. As far as single PAH is concerned, high concentration of PAH has larger impact on the nitrogen-fixing bacteria than low concentration of PAH. Besides, among the three types of PAHs, NAP has the greatest short term toxicity; PYR has the strongest long-term impact, whereas FLU has relatively higher long-time effect. Multidimensional scaling analysis and correspondence analysis are two reliable multivariate analysis methods for investigating the relationship between the nitrogen-fixing bacterial community and PAHs contamination. Investigating the effect of PAHs on the nitrogen-fixing bacterial diversity could yield useful information for understanding the process of biogeochemical cycling of nitrogen in mangrove sediment. The present study reveals that nitrogen-fixing bacterial community can be used as an important parameter indicating the impact of PAHs on mangrove sediment ecosystem.

Effects of pyrene on antioxidant systems and lipid peroxidation level in mangrove plants, Bruguiera gymnorrhiza.

The effects of polycyclic aromatic hydrocarbon (PAH) (pyrene) on superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase, peroxidase, malondialdehyde (MDA) and proline were studied in leaves, stems and roots of Bruguiera gymnorrhiza. The results showed that the responses of enzymatic and non-enzymatic antioxidants varied significantly among the three tissues studied. The activities of antioxidant enzymes in PAH-treated stems and roots fluctuated in different stress levels compared to the controls, while the antioxidant enzymes such as SOD, APX in leaves increased when stressed by PAH with a significant positive relation between PAH and leaf SOD or APX activity. Low PAH treatments could also stimulate proline in leaves and stems. MDA content was obviously accumulated in stems and roots under PAH stress while decreased in leaves, indicating that the increased antioxidant enzymes in leaves may partly alleviate lipid peroxidation. For pollution monitoring purpose, SOD and APX in leaves may be potential biomarkers of PAH pollution in intertidal estuaries.

Influence of N deficiency and salinity on metal (Pb, Zn and Cu) accumulation and tolerance by Rhizophora stylosa in relation to root anatomy and permeability.

Effects of N deficiency and salinity on root anatomy, permeability and metal (Pb, Zn and Cu) translocation and tolerance were investigated using mangrove seedlings of Rhizophora stylosa. The results showed that salt could directly reduce radial oxygen loss (ROL) by stimulation of lignification within exodermis. N deficiency, oppositely, would reduce lignification. Such an alteration in root permeability may also influence metal tolerance by plants. The data indicated that a moderate salinity could stimulate a lignified exodermis that delayed the entry of metals into the roots and thereby contributed to a higher metal tolerance, while N deficiency would aggravate metal toxicity. The results from sand pot trail further confirmed this issue. This study provides a barrier property of the exodermis in dealing with environments. The plasticity of root anatomy is likely an adaptive strategy to regulate the fluxes of gases, nutrients and toxins at root-soil interface.