Associations of meeting 24-h movement guidelines and metabolic syndrome in Korean adults during the COVID-19 pandemic.

OBJECTIVES: This study aimed to investigate the association between adherence to 24-h movement guidelines and metabolic syndrome (MetS) before and during the COVID-19 pandemic. STUDY DESIGN: Repeated cross-sectional design. METHODS: We selected 10,882 adults (2019: n = 5710; 2020: n = 5172) aged ≥20 years from the Korea National Health and Nutrition Examination Survey. Domain-specific physical activity and sedentary behavior were assessed using a global physical activity questionnaire. We also measured the typical sleep duration (h/day) on weekdays and weekends. MetS was defined as the presence of more than three risk factors. RESULTS: During the COVID-19 pandemic, transportation-related physical activity decreased, while the prevalence of abdominal obesity (+3.3 %) and low HDL-C levels (+3.1 %) increased significantly. An elevated risk of MetS was observed in the lower aerobic (odds ratio [OR], 1.28; 95% confidence interval [CI], 1.04-1.58; P = 0.019) and muscular exercise (OR, 1.31; 95% CI, 1.04-1.66; P = 0.023) groups and in the high sedentary behavior (OR, 1.23; 95% CI, 1.00-1.51; P = 0.049) during the pandemic. Sensitivity analysis stratified by sex showed similar patterns with more pronounced changes in MetS components in males. The models also showed significant associations between aerobic physical activity, strength exercises, and sedentary behavior with MetS in males and females. CONCLUSIONS: Although sedentary behavior and sleep time remained unchanged, a significant decrease in transportation-related physical activity was observed during the pandemic. Moreover, our findings revealed that aerobic physical activity, strength exercise, and sedentary time during the pandemic were associated with an increased MetS risk. These results highlight the importance of promoting physical activity, particularly during periods of social restriction, to mitigate the pandemic's negative effects on metabolic health.

[Differential proteomic screening of plasma exosomes before and after magnesium isoglycyrrhizinate treatment in chronic hepatitis B].

Objective: To screen the differential proteomic of plasma exosomes before and after magnesium isoglycyrrhizinate (MgIG) treatment in chronic hepatitis B patients. Methods: Plasma samples were collected from 36 cases with chronic hepatitis B before and after MgIG treatment (2 ml/case). Plasma exosomes were extracted by ultracentrifugation. Exosomal particles concentration and inner diameter were detected by Nanosight NS300 particle size analyzer. Three cases of plasma exosomes were randomly selected before and after MgIG treatment. Proteins were extracted after lysis and digested with trypsin. Label-free differential proteomics analysis was performed by liquid chromatography-tandem mass spectrometry to screen out differential proteins that changed more than 1.5 times. Enzyme linked immunosorbent assay (ELISA) was used to verify the quantitative differential protein expression (n = 30). Measurement data were compared by paired sample t-test. Results: The average particle concentration of the extracted exosomes was 2.2×10(9)/ml, and the average size was (107 ± 52) nm, which was consistent with the theoretical value of plasma exosome size, proving that the plasma exosomes were successfully extracted. Proteomics results showed that before and after MgIG treatment in chronic hepatitis B patients, a total of 153 differentially expressed proteins were screened, including 85 up-regulated and 68 down-regulated proteins. Enzyme-linked immunosorbent assay results showed that compared with the MgIG before and after treatment group of chronic hepatitis B patients, the differences in the concentrations of hepatocyte growth factor activator and hepatocyte growth factor like protein in plasma exosomes were statistically significant (P < 0.05). Hepatocyte growth factor activator concentration in the plasma exosomes before and after MgIG treatment group was (45.9 ± 9.4) µg/ml and (13.9 ± 2.0) µg/ml, respectively, and it was down-regulated by about 3 times. Hepatocyte growth factor-like protein concentration in the plasma exosomes before and after MgIG treatment group was (23.4 ± 4.9) µg/ml and (13.8 ± 2.2) µg/ml, respectively, and it was down-regulated by about 2 times. Enzyme-linked immunosorbent assay results had consistency with the proteomics results. Conclusion: This study successfully screened the differential proteomic of plasma exosomes before and after MgIG treatment in chronic hepatitis B, and provided experimental basis for studying the molecular mechanism of MgIG treatment for chronic hepatitis B.

Upregulation of KCNMA1 facilitates the reversal effect of verapamil on the chemoresistance to cisplatin of esophageal squamous cell carcinoma cells.

OBJECTIVE: This study aimed to investigate the reversal effect of verapamil (VER) on the chemoresistance to cisplatin of esophageal squamous cell carcinoma (ESCC) cells. PATIENTS AND METHODS: The reversal effect of VER on cisplatin resistance in ESCC cells was evaluated via CCK-8 assay, colony formation assessment, and flow cytometry. The key genes that mediate this effect were screened via high-throughput transcriptome se¬quencing. The mRNA and protein expression levels of potassium calcium-activated channel subfamily M alpha 1 (KCNMA1) in ESCC cells were examined via quantitative real-time PCR and Western blot analysis, respectively. The protein expressions of KCNMA1 in tissue samples from patients with either positive or negative responses to the therapeutic regimen of VER were determined via immunohistochemistry assay. Cell models with KCNMA1 knockdown and overexpression were es¬tablished to examine the role of KCNMA1 in mediating the reversal effect of VER on the chemoresistance to cisplatin of ESCC cells. RESULTS: Results revealed that VER significantly decreased the 50% inhibitory concentration of cisplatin, inhibited colony formation, and induced apoptosis in ESCC cells. The curative effects of VER combined with chemotherapeutic drugs in KCNMA1-positive patients were better than those in KCNMA1-negative patients. KCNMA1 upregulation enhanced the reversal effect of VER on the chemoresistance to cisplatin of ESCC cells. CONCLUSIONS: KCNMA1 facilitated the reversal effect of VER on cisplatin resistance in ESCC cells.

Identity and virulence properties of Aeromonas isolates from healthy Northern snakehead (Channa argus) in China.

Members of the genus Aeromonas are opportunistic pathogen of a variety of aquatic animals that exhibits multidrug resistance, phenotypes, virulence genes and virulence. The present study described the species distribution and the potential pathogenicity of Aeromonas isolated from healthy Northern snakehead (Channa argus) in China. Molecular identification revealed that A. veronii biovar veronii (69/167; 41·3%) and A. hydrophila (41/167; 24·6%) were the most common species found in Northern snakehead intestine based on sequencing of the 16S rRNA gene and DNA gyrase subunit B protein. The distribution of seven virulence factors including aer (84·4%), act (80·8%), ser (40·1%), Aha (27·5%), lip (23·4%), exu (15·0%) and LuxS (12·6%) were determined exclusively in Aeromonas isolates. All the seven virulence genes were present in 9·6% (16/167), among which 11 strains were identified as A. veronii biovar veronii. For the strains harbouring seven virulence genes, the 50% lethal doses (LD50 ) of isolates were lower compared to the isolates carrying two virulence genes. The challenge tests revealed that isolate W31 had the lowest lethal dose, causing 50% mortality at 4·5 × 103 colony-forming units (CFU) per ml. Furthermore, histopathology of Northern snakehead infected with Aeromonas strains showed necrosis and congestion in liver, spleen and kidney and also damage to the intestine. This study confirms that the Aeromonas strains isolated from healthy Northern snakehead may be a cause of concern for public health. SIGNIFICANCE AND IMPACT OF THE STUDY: Aeromonas species are widely distributed in aquatic environments and have considerable virulence potential. The aim of this study was to identify Aeromonas strains isolated from healthy Northern snakehead, and to investigate if Aeromonas species isolated from healthy fish potential pathogenicity with special reference to virulence and epidemiology studies.

[Clinical significance of ascitic interleukin-7 expression levels in cirrhotic patients complicated with spontaneous bacterial peritonitis].

Objective: To observe ascitic interleukin-7 expression level in cirrhotic patients complicated with spontaneous bacterial peritonitis, and to detect the effect of recombinant human IL-7 on CD4(+) and CD8(+)T lymphocyte function. Methods: A total of 84 patients with liver cirrhosis who were hospitalized from August 2017 to April 2018 were selected. Among them, 51 cases were complicated with cirrhosis and untainted ascites, and 33 cases were cirrhosis complicated with spontaneous bacterial peritonitis. Peripheral blood and ascites were collected routinely. The levels of IL-7 in peripheral blood and ascites were measured by enzyme-linked immunosorbent assay. CD4(+)T cells and CD8(+)T cells were purified from ascites, and were stimulated with recombinant IL-7. Cellular proliferation, key transcription factors for mRNA, and cytokines production by CD4(+)T cells in response to IL-7 stimulation was measured. mRNA expression corresponding to perforin, granzyme B, and granulysin as well as cytokines production by CD8(+)T cells was also measured in response to IL-7 stimulation. Cytolytic and non-cytolytic activity of CD8(+)T cells in response to IL-7 stimulation was also investigated in both direct and indirect contact co-culture system. Measurement data of the normal distribution were compared between the two groups by Student's t-test and the data before and after stimulation were compared by paired t-test. Measurements that did not conform to normal distribution were compared between the two groups using Mann-Whitney U test, and data before and after stimulation were compared using Wilcoxon paired test. Results: There was no significant statistical difference in serum IL-7 levels between the two groups [(5 001 ± 1 458) pg/ml vs. (4 768 ± 1 128) pg/ml, P = 0.41]. The level of ascitic IL-7 in cirrhotic patients complicated with SBP was significantly lower than cirrhosis patients with untainted ascites [(966.4 + 155.8) pg/ml vs. (792.1 + 126.4) pg/ml, P < 0.01]. Recombinant IL-7 stimulation promoted the proliferation of CD4(+) and CD8(+)T cells from ascites in patients with liver cirrhosis complicated by SBP. T-bet mRNA relative expression and IFN-γ secretion in CD4(+)T cells was also elevated in response to IL-7 stimulation in vitro. Moreover, IL-7 stimulation also increased the mRNA expressions of perforin, granzyme B, and granulysin as well as productions of IFN-γ and TNF-α by CD8(+)T cells. Recombinant IL-7 stimulation elevated cytolytic and non-cytolytic activity of CD8(+)T cells from ascites in patients with liver cirrohosis complicated by SBP, which manifested as increased target cell death and IFN-γ production in both direct and indirect contact co-culture system. Conclusion: Ascitic IL-7 promotes T lymphocyte function in patients with liver cirrhosis complicated with SBP.

Circ-ITCH regulates triple-negative breast cancer progression through the Wnt/ß-catenin pathway.

Recent studies indicate that circular RNA (circRNA) is involved in tumorigenesis, but its role in triple-negative breast cancer (TNBC) remains largely unknown. In this study, we characterized the role of circ-ITCH in TNBC and found that circ-ITCH was significantly down-regulated in TNBC tissues and cell lines and closely associated with poor prognosis. We therefore constructed the MDA-MB-231 and BT-549 TNBC cell lines stably expressing circ-ITCH by lentiviral vectors to determine its underlying mechanisms in TNBC progression. Most importantly, over-expression of circ-ITCH remarkably inhibited TNBC proliferation, invasion and metastasis both in vitro and in vivo. Mechanistically, we found that circ-ITCH acts as a sponge for miR-214 and miR-17 to increase expression of its ITCH linear isoform, thereby inactivating Wnt/ß-catenin signaling. Our combined results show for the first time that circ-ITCH is a tumor suppressor, a promising prognostic biomarker in TNBC and that its restoration could well be a successful strategy in TNBC.

High-Level Ciprofloxacin-Resistant Campylobacter jejuni Isolates Circulating in Humans and Animals in Incheon, Republic of Korea.

Campylobacter jejuni is one of the major causative pathogens of outbreaks or sporadic cases of diarrhoeal diseases worldwide. In this study, we compared the phenotypic and genetic characteristics of C. jejuni isolates of human and food-producing animal origins in Korea and examined the genetic relatedness between these two groups of isolates. Regardless of isolation source, all C. jejuni isolates harboured four virulence genes, cadF, cdtB, ciaB and racR, whereas the wlaN and virB11 genes were more frequently observed in human isolates. Antimicrobial susceptibility testing showed that the majority of C. jejuni isolates displayed high-level resistance to fluoroquinolone (95.2%) or tetracycline (76.2%) antibiotics, and 12.4% of isolates exhibited multidrug resistance (more than three classes of antibiotics tested). Pulsed-field gel electrophoresis (PFGE) of all Campylobacter isolates revealed 51 different SmaI-PFGE patterns and six major clusters containing both human and animal isolates. These results indicate that genetically diverse strains of C. jejuni with antimicrobial drug-resistance and virulence properties have prevailed in Incheon. Nevertheless, some particular populations continue to circulate within the community, providing the evidence for an epidemiological link of C. jejuni infections between humans and food-producing animals. Therefore, the continued monitoring and surveillance of C. jejuni isolates of human and food-producing animal origins are required for public health and food safety.

Andrographolide radiosensitizes human esophageal cancer cell line ECA109 to radiation in vitro.

To explore the radiosensitivity of andrographolide on esophageal cancer cell line ECA109. The inhibition effects of andrographolide were measured using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium (MTT) assay. Clonogenic survival assay was used to evaluate the effects of andrographolide on the radiosensitivity of esophageal cancer cells. Immunofluorescence was employed to examine Bax expression. The changes in cell cycle distribution and apoptosis were assayed using flow cytometry. The expression of NF-κb/Cleaved-Caspase3/Bax/Bcl-2 was measured using Western blot analysis. DNA damage was detected via γ-H2AX foci counting. With a clear dose and time effects, andrographolide was found to inhibit the proliferation of esophageal cell line ECA109. The results of the clonogenic survival assay show that andrographolide could markedly enhance radiosensitivity (P < 0.05) with a sensitizing enhancement ratio of 1.28. Andrographolide caused a dose-dependent increase in Cleaved-Caspase3/Bax protein expression and a decrease in Bcl-2/NF-κb expression. Apoptosis in andrographolide-treated ECA-109 increased significantly compared with the apoptosis in the simple drug and radiation combined with drug groups (P < 0.001; P < 0.05). Moreover, compared with the independent radiation group, the andrographolide combined with radiation group increased the number of DNA double chain breaks. Andrographolide can increase the radiosensitivity of esophageal cell line ECA109. This result may be associated with the decrease in the NF-κb level and the induced apoptosis of esophageal cancer cells.

MAIT cells are licensed through granzyme exchange to kill bacterially sensitized targets.

Mucosal-associated invariant T (MAIT) cells are an innate-like T-cell population restricted by the non-polymorphic, major histocompatibility complex class I-related protein 1, MR1. MAIT cells are activated by a broad range of bacteria through detection of riboflavin metabolites bound by MR1, but their direct cytolytic capacity upon recognition of cognate target cells remains unclear. We show that resting human MAIT cells are uniquely characterized by a lack of granzyme (Gr) B and low perforin expression, key granule proteins required for efficient cytotoxic activity, but high levels of expression of GrA and GrK. Bacterial activation of MAIT cells rapidly induced GrB and perforin, licensing these cells to kill their cognate target cells. Using a novel flow cytometry-based killing assay, we show that licensed MAIT cells, but not ex vivo MAIT cells from the same donors, can efficiently kill Escherichia coli-exposed B-cell lines in an MR1- and degranulation-dependent manner. Finally, we show that MAIT cells are highly proliferative in response to antigenic and cytokine stimulation, maintaining high expression of GrB, perforin, and GrA, but reduced expression of GrK following antigenic proliferation. The tightly regulated cytolytic capacity of MAIT cells may have an important role in the control of intracellular bacterial infections, such as Mycobacterium tuberculosis.

High prevalence of nasal carriage of ß-lactamase-negative ampicillin-resistant Haemophilus influenzae in healthy children in Korea.

This study investigated the carriage of antimicrobial resistant Haemophilus influenzae in 582 healthy children attending kindergarten or elementary school at four intervals over a 9-month period in Seoul, Korea. Diverse colonization patterns and a lower level of long-term persistent carriage by H. influenzae status were evident in this study. Colonizing H. influenzae isolates showed a high rate of resistance to ß-lactams including ampicillin (51·9%), cefaclor (52·1%), and amoxicillin/clavulanate (16·3%). Based on the ampicillin resistance mechanism, H. influenzae isolates were categorized as ß-lactamase-negative, ampicillin-susceptible (BLNAS) (48·1%), ß-lactamase-positive, ampicillin-resistant (BLPAR) (22·6%), ß-lactamase-negative, ampicillin-resistant (BLNAR) (22·8%), and ß-lactamase-positive, amoxicillin/clavulanate-resistant (BLPACR) strains (6·5%). This study provides the first evidence of a high prevalence (22·8%) of BLNAR strains of H. influenzae nasal carriage in healthy children attending kindergarten or the first 2 years of elementary school in Korea. The high carriage of these resistant strains in overcrowded urban settings may create reservoirs for development of H. influenzae-resistant strains.

Visual pathway-related horizontal reference plane for three-dimensional craniofacial analysis.

OBJECTIVES: To construct three-dimensional (3D) horizontal reference planes based on visual pathway and to determine their stability and reliability by analyzing the structural patterns of normal and dysmorphology for 3D craniofacial analysis. SETTING AND SAMPLE POPULATION: Thirty-six subjects with maxillofacial dysmorphology and malocclusion, and eight normal controls. MATERIALS AND METHODS POPULATION: On the 3D computed tomographic images of the subjects, the visual pathway-based planes, including the orbital axis plane (OAP), visual axis plane (VAP), and the optical axis plane (OpAP), were constructed and evaluated. RESULTS: The OAP, but not the VAP and OpAP, showed the ideal relationship between the midsagittal and posterior maxillary plane, and properly described the different patterns of maxillofacial dysmorphology with craniofacial plane 1 of Delaire's analysis and the occlusal plane. CONCLUSIONS: The proposed visual pathway-related horizontal reference planes, and in particular the OAP, seem to correctly express the visual axis and the position of the head in natural head position and can be used as a horizontal reference plane for the 3D analysis of craniofacial dysmorphology and anthropology.

GABA(A) and GABA(B) receptors have opposite effects on synaptic glutamate release on the nucleus tractus solitarii neurons.

Cranial visceral afferent nerve transfers information about visceral organs to nucleus tractus solitarii (NTS) by releasing the excitatory neurotransmitter glutamate. Various endogenous modulators affect autonomic reflex responses by changing glutamatergic responses in the NTS. Although the expression of GABA(A) and GABA(B) receptors in glutamatergic terminals is known, their functional contribution on glutamate release is poorly characterized. Here, we used mechanically isolated NTS neurons to examine the mechanisms by which presynaptic GABA(A) and GABA(B) receptors modulate glutamatergic excitatory postsynaptic currents (EPSCs). EPSC were isolated by clamping voltage at equilibrium potential for chloride (-49 mV) without any GABA receptors antagonists. In all neurons, GABA(A) agonist, muscimol (1 and 10 µM), increased EPSC frequency (284.1±57% and 278.4±87% of control, respectively), but the GABA(B) agonist, baclofen (10 µM), decreased EPSC frequency (43±8% of control). The GABA(A) antagonist, gabazine (18 µM), decreased EPSC frequency in 50% of tested neurons, whereas GABA(B) antagonist, CGP (5 µM), increased the EPSC frequency in 36% of tested neurons. External application of GABA (1 and 30 µM) facilitating the EPSC frequency. The facilitation of the GABA(A) receptor-mediated release of glutamate was blocked by Na⁺-K⁺-Cl⁻ cotransporter type 1 antagonist or Na⁺ and Ca²âº channel inhibitors indicating GABA(A) presynaptic depolarization. Thus, tonically released GABA activates GABA(A) and GABA(B) receptors to modulate the release of glutamate. These findings provide cellular mechanisms of heterosynaptic GABA-glutamate integration of peripheral visceral afferent signals in the NTS.

Developmental immunolocalization of heat shock protein 70 (HSP70) in epithelial cell of rat kidney.

During renal development the cells in the medulla are exposed to elevated and variable interstitial osmolality. Heat shock protein 70 (HSP70) is a major molecular chaperone and plays an important role in the protection of cells in the renal medulla from high osmolality. The purpose of this study was to establish the time of immunolocalization and distribution of HSP70 in developing and adult rat kidney. In addition, changes in HSP70 immunolocalization following the infusion of furosemide were investigated. In adult animals, the HSP70 was expressed in the medullary thin ascending limb of Henle's loop (ATL) and inner medullary collecting duct (IMCD). In developing kidney, HSP70 immunoreactivity was first detected in the IMCD of the papillary tip on postnatal day 1. From four to 14 days of age, HSP70 was detected in the ATL after transformation from thick ascending limb, beginning at the papillary tip and ascending to the border between the outer and inner medulla. The immunolocalization of HSP70 in both the ATL and IMCD gradually increased during two weeks. The gradual increase in HSP70 was associated with an increase in its mRNA abundance. However, furosemide infusion resulted in significantly reduced HSP70 immunolocalization in the IMCD and ATL. These data demonstrated that the expression of HSP70 was closely correlated with changes in interstitial osmolality during the development of the kidney. We suggest that HSP70 protects ATL and IMCD cells in the inner medulla from the stress of high osmolality and may be involved in the transformation of the ATL of the long loop of Henle during renal development.

Roasted licorice extracts dampen high glucose-induced mesangial hyperplasia and matrix deposition through blocking Akt activation and TGF-beta signaling.

Diabetic nephropathy (DN) characterized as nephrotic syndrome and diffuse glomerulosclerosis can cause renal failure and end-stage kidney disease. Expansion of mesangial matrix around capillaries in the kidney glomeruli is a prominent feature of DN. This study investigated whether licorice extracts inhibited mesangial cell (MC) proliferation and matrix accumulation induced by high glucose (HG). Human renal MC were cultured in media containing 5.5 mM glucose plus 27.5 mM mannitol as an osmotic control or 33 mM glucose for 3 d in the presence of water or ethanol extracts from raw licorice (LW, LE) or roasted licorice (RLW, RLE). Non-polar components including glycyrrhetic acid were elevated during licorice roasting, whereas polar components soluble in water extracts were diminished. Exposure of cells to HG caused significant increases in collagen IV secretion and connective tissue growth factor (CTGF) expression, which was appeased by RLW and RLE at transcriptional levels. The inhibitory potency was high in the order of RLE > or = RLW > or = LE > > LW. Non-polar glycyrrhetic acid but not glycyrrhizin retarded HG-stimulated mesangial matrix deposition through diminishing CTGF expression. In addition, RLW and RLE but not LW modulated membrane type matrix metalloproteinase-1 (MT-1 MMP) expression, MMP-2 activity and tissue inhibitor of MMP-2 (TIMP-2), which facilitated the degradation of mesangial matrix. Furthermore, the augmented expression of CTGF and TIMP-2 in HG-exposed cells was mediated by Akt activation and TGF-beta/Smad signaling through PKCbeta2-responsive signaling pathways. However, HG-down-regulated MT-1 MMP expression was independent of activation of ERK1/2 and Akt when using their inhibitors of DB98059 (ERK1/2) and LY294002 (Akt) alone or in combination. These results demonstrate that extracts from roasted licorice may be highly potent therapeutic agents for the prevention and treatment of mesangial fibrosis and glomerulosclerosis leading to diabetes nephropathy due to longstanding diabetes mellitus.

An outbreak of skin and soft tissue infection caused by Mycobacterium abscessus following acupuncture.

Although outbreaks of Mycobacterium abscessus infection have been reported, none of these reports has identified the potential sources of infection and modes of transmission. In April 2008, we identified and investigated an outbreak of M. abscessus skin and soft tissue infections following acupuncture among the patients who visited an oriental medical clinic. Active surveillance of patients who had visited the clinic was conducted to define the extent of the outbreak. Environmental cultures and a case-control study were performed to elucidate the source of infection and mode of transmission. From 1002 patients interviewed, 109 patients were identified as having suffered M. abscessus skin and soft tissue infections at acupuncture sites. A single strain of M. abscessus was isolated from the wounds of 31 patients and nine environmental samples, including a diluted glutaraldehyde solution. The case-control study revealed that a higher numbers of visits to the clinic for acupuncture (adjusted OR (aOR) 20.12; 95% CI 4.34-93.35) and the use of interferential current therapy or low-frequency therapy (aOR 36.12; 95% CI 5.54-235.44) were associated with the development of M. abscessus infection. The contaminated diluted glutaraldehyde solution that was used to disinfect the physical therapy devices may have been the source of the outbreak of M. abscessus infection in the 109 patients who underwent acupuncture.

Stockholm Convention organochlorine pesticides and polycyclic aromatic hydrocarbons in Hong Kong air.

Organochlorine pesticides (OCPs) including eight of the original nine pesticides listed in the Stockholm Convention on Persistent Organic Pollutants, and polycyclic aromatic hydrocarbons (PAHs) were measured in 90 air samples collected from January 2004 to March 2005, and in 304 air samples collected from January 1998 to December 2005 in Hong Kong, respectively. The annual average OCP concentrations at Tap Mun, Yuen Long and Tsuen Wan were 135+/-140 (ND-482), 186+/-183 (ND-656), and 190+/-239 fg m(-3) (ND-966), respectively, while annual (January 1998 to December 2005) average concentrations of total PAHs at Tsuen Wan, and Central/Western were 578+/-261 (117-938) and 588+/-248ngm(-3) (103-874), respectively. No seasonal and spatial variations in OCP concentrations were observed due to trace levels, and estimation of carcinogenic risks of OC pesticides was low. Naphthalene (>70%) was the dominant PAH in terms of concentrations measured. The sum of three-ring PAHs, including acenaphthene, acenaphthylene, anthracene, fluorene and phenanthrene, contributed to around 20% of the total PAH concentration while the contribution of heavier PAHs (sum of four-, five- and six-rings) was less than 5%. t-Values of the paired samples T-test for the individual PAHs showed that the concentrations of benzo(a)pyrene, the relative high cancer risk PAH, and most of the PAHs detected at Tsuen Wan and Central/Western were significantly different (p<0.01), with higher concentrations detected at Tsuen Wan. Several PAHs exhibited strong seasonality with higher concentrations in winter. Sources of PAHs were determined by investigating PAH isomer ratios which suggested petrogenic sources as primary sources of PAHs in Hong Kong air.

Enhancement of algicidal activity by immobilization of algicidal bacteria antagonistic to Stephanodiscus hantzschii (Bacillariophyceae).

AIMS: Enhancement of algicidal activity by immobilization of algicidal bacteria antagonistic to Stephanodiscus hantzschii. METHODS AND RESULTS: In laboratory studies, A diatom-lysing bacterium, Pseudomonas fluorescens HYK0210-SK09 showed strong algicidal activity against S. hantzschii, but a natural mesocosm study revealed that this bacterium failed to fully control natural blooms of Stephanodiscus at the low water temperatures that favour these blooms. Here, we sought to develop an effective immobilization strategy for enhancing the algicidal activity of HYK0210-SK09 in the natural setting. Bacterium HYK0210-SK09 was immobilized with various carriers including agar, alginate, polyurethane and cellulose sponge. The bacterial cells immobilized with cellulose sponge (CIS) induced more rapid and complete lysis of S. hantzschii than other carriers, and had a higher packing ability than polyurethane. Furthermore, CIS-immobilized cells showed higher lysis of S. hantzschii at the same concentrations as that of free cells (< or =1 x 10(7) cells ml(-1)), and had especially strong algicidal activity at the low temperatures (<10 degrees C). Based on these laboratory studies, we assessed the possible application of HYK0210-SK09 cells in the field by performing a mesocosm study during the winter season. The CIS-immobilized cells with species-specific activity towards the genera Stephanodiscus showed extremely high algicidal activity (up to 95%) against a bloom of Stephanodiscus hantzschii even at low water temperatures, because of high cell packing and subsequent cell protection against low temperatures and predators, whereas free cells showed negligible algicidal activities under these conditions. CONCLUSION: Immobilizing cells of HYK0210-SK09 in CIS foam, rather than in the other matrices tested, could achieve more efficient control of Stephanodiscus blooms and showed a significant algicidal activity on in vitro and in vivo blooms, even at low water temperature. SIGNIFICANCE AND IMPACT OF THE STUDY: Collectively, these results indicate that CIS of algicidal bacteria may form an important strategy for effective management of Stephanodiscus blooms at low water temperatures.

AtBAG6, a novel calmodulin-binding protein, induces programmed cell death in yeast and plants.

Calmodulin (CaM) influences many cellular processes by interacting with various proteins. Here, we isolated AtBAG6, an Arabidopsis CaM-binding protein that contains a central BCL-2-associated athanogene (BAG) domain. In yeast and plants, overexpression of AtBAG6 induced cell death phenotypes consistent with programmed cell death (PCD). Recombinant AtBAG6 had higher affinity for CaM in the absence of free Ca2 + than in its presence. An IQ motif (IQXXXRGXXXR, where X denotes any amino-acid) was required for Ca2 +-independent CaM complex formation and single amino-acid changes within this motif abrogated both AtBAG6-activated CaM-binding and cell death in yeast and plants. A 134-amino-acid stretch, encompassing both the IQ motif and BAG domain, was sufficient to induce cell death. Agents generating oxygen radicals, which are known to be involved in plant PCD, specifically induced the AtBAG6 transcript. Collectively, these results suggest that AtBAG6 is a stress-upregulated CaM-binding protein involved in plant PCD.

Cytokinesis regulator ECT2 changes its conformation through phosphorylation at Thr-341 in G2/M phase.

The Rho activator ECT2 functions as a key regulator in cytokinesis. ECT2 is phosphorylated during G2/M phase, but the physiological significance of this event is not well known. In this study, we show that phosphorylation of ECT2 at threonine-341 (T341) affects the autoregulatory mechanism of ECT2. In G2/M phase, ECT2 was phosphorylated at T341 most likely by Cyclin B/Cyclin-dependent kinase 1 (Cdk1), and then dephosphorylated before cytokinesis. Depletion of ECT2 by RNA interference (RNAi) efficiently induced multinucleate cells. Expression of the phospho-deficient mutant of ECT2 at T341 suppressed the multinucleation induced by RNAi to ECT2, indicating that ECT2 is biologically active even when it is not phosphorylated at T341. However, the phospho-mimic mutation at T341 weakly stimulates the catalytic activity of ECT2 as detected by serum response element reporter gene assays. As T341 is located at the hinge region of the N-terminal regulatory domain and C-terminal catalytic domain, phosphorylation of T341 may help accessing downstream signaling molecules to further activate ECT2. We found that the phospho-mimic mutation T341D increases binding with itself or the N-terminal half of ECT2. These results suggest a conformational change of ECT2 upon phosphorylation at T341. Therefore, ECT2 activity might be regulated by the phosphorylation status of T341. We propose that T341 phosphorylation by Cyclin B/Cdk1 could be a trigger for further activation of ECT2.

Isolation and characterization of a bio-agent antagonistic to diatom, Stephanodiscus hantzschii.

AIMS: Identification of bacterium HYK0203-SK02 and its lysis of Stephanodiscus hantzschii. METHODS AND RESULTS: In an effort to identify a bio-agent capable of controlling S. hantzschii blooms, we used the algal lawn method to identify 76 bacteria in relevant water samples. Of these, the seven isolate showed algicidal activity against S. hantzschii; isolate HYK0203-SK02 exhibited the strongest algicidal activity, and was used for further analysis. 16S rDNA sequencing of this isolate allowed us to identify HYK0203-SK02 as a strain of Pseudomonas putida (99.2%). Growth of S. hantzschii was strongly suppressed by bacteria in all growth phases, with the strongest algicidal activity noted against diatoms in the exponential stage (5-18 days). Host range assays revealed that isolate HYK0203-SK02 also strongly inhibited the growth of Microcystis aeruginosa, but stimulated growth of the diatom Cyclotella sp., which has a similar structure to that of S. hantzschii. Biochemical assays revealed that the algicidal substance seemed to be localized in the cytoplasmic membrane of this newly identified algicidal bacterium. CONCLUSION: The algicidal bacteria P. putida HYK0203-SK02 caused cell lysis and death of not only diatom S. hantzschii but also cyanobacteria M. aeruginosa, dramatically. Algicidal substance might be located at the compartment of cytoplasmic membrane. SIGNIFICANCE AND IMPACT OF THE STUDY: Taken together, our results indicate that P. putida HYK0203-SK02 may be a potential bio-agent for future use in controlling freshwater diatomic blooms.