A novel "prime and pull" strategy mediated by the combination of two dendritic cell-targeting designs induced protective lung tissue-resident memory T cells against H1N1 influenza virus challenge

Vaccination is still the most promising strategy for combating influenza virus pandemics. However, the highly variable characteristics of influenza virus make it difficult to develop antibody-based universal vaccines, until now. Lung tissue-resident memory T cells (TRM), which actively survey tissues for signs of infection and react rapidly to eliminate infected cells without the need for a systemic immune reaction, have recently drawn increasing attention towards the development of a universal influenza vaccine. We previously designed a sequential immunization strategy based on orally administered Salmonella vectored vaccine candidates. To further improve our vaccine design, in this study, we used two different dendritic cell (DC)-targeting strategies, including a single chain variable fragment (scFv) targeting the surface marker DC-CD11c and DC targeting peptide 3 (DCpep3). Oral immunization with Salmonella harboring plasmid pYL230 (S230), which displayed scFv-CD11c on the bacterial surface, induced dramatic production of spleen effector memory T cells (TEM). On the other hand, intranasal boost immunization using purified DCpep3-decorated 3M2e-ferritin nanoparticles in mice orally immunized twice with S230 (S230inDC) significantly stimulated the differentiation of lung CD11b+ DCs, increased intracellular IL-17 production in lung CD4+ T cells and elevated chemokine production in lung sections, such as CXCL13 and CXCL15, as determined by RNAseq and qRT‒PCR assays, resulting in significantly increased percentages of lung TRMs, which could provide efficient protection against influenza virus challenge. The dual DC targeting strategy, together with the sequential immunization approach described in this study, provides us with a novel "prime and pull" strategy for addressing the production of protective TRM cells in vaccine design.

Chicken dendritic cell-targeting nanobodies mediated improved protective effects against H9N2 influenza virus challenge in a homologous sequential immunization study

Global poultry production is still severely affected by H9N2 avian influenza virus (AIV), and the development of a novel universal AIV vaccine is still urgently needed. Neuraminidase (NA) has recently been shown to be an efficient conserved protective antigen. In this study, we fused the extracellular region of the NA gene with a ferritin cassette (pYL281), which resulted in self-assembled 24-mer nanoparticles with the NA protein displayed outside the nanoparticles. In addition, a chicken dendritic cell-targeting nanobody-phage74 was also inserted ahead of the NA protein to yield pYL294. Incubation with chicken bone marrow-derived dendritic cells (chBMDCs) showed that the DC-targeting nanoparticles purified from the pYL294 strain significantly increased the maturation of chBMDCs, as shown by increased levels of CCL5, CCR7, CD83 and CD86 compared with nontargeting proteins. Then, a chicken study was performed using Salmonella oral administration together with intranasal boost with purified proteins. Compared with the other groups, oral immunization with Salmonella harboring pYL294 followed by intranasal boost with purified DC-targeting nanoparticles dramatically increased the humoral IgY and mucosal IgA antibody response, as well as increased the cellular immune response, as shown by elevated splenic lymphocyte proliferation and intracellular mRNA levels of IL-4 and IFN-γ. Finally, sequential immunization with DC-targeting nanoparticles showed increased protection against G57 subtype H9N2 virus challenge compared with other groups, as shown by significantly decreased virus RNA copy numbers in oropharyngeal washes (Days 3, 5 and 7 post challenge) and cloacal washes (Day 7), significantly decreased lung virus titers on Day 5 post challenge and increased body weight gains during the challenge.

Homologous Sequential Immunization Using Salmonella Oral Administration Followed by an Intranasal Boost with Ferritin-Based Nanoparticles Enhanced the Humoral Immune Response against H1N1 Influenza Virus

The influenza virus continues to pose a great threat to public health due to the frequent variations in RNA viruses. Vaccines targeting conserved epitopes, such as the extracellular domain of the transmembrane protein M2 (M2e), a nucleoprotein, and the stem region of hemagglutinin proteins, have been developed, but more efficient strategies, such as nanoparticle-based vaccines, are still urgently needed. However, the labor-intensive in vitro purification of nanoparticles is still necessary, which could hinder the application of nanoparticles in the veterinary field in the future. To overcome this limitation, we used regulated lysis Salmonella as an oral vector with which to deliver three copies of M2e (3M2e-H1N1)-ferritin nanoparticles in situ and evaluated the immune response. Then, sequential immunization using Salmonella-delivered nanoparticles followed by an intranasal boost with purified nanoparticles was performed to further improve the efficiency. Compared with 3M2e monomer administration, Salmonella-delivered in situ nanoparticles significantly increased the cellular immune response. Additionally, the results of sequential immunization showed that the intranasal boost with purified nanoparticles dramatically stimulated the activation of lung CD11b dendritic cells (DCs) and elevated the levels of effector memory T (TEM) cells in both spleen and lung tissues as well as those of CD4 and CD8 tissue-resident memory T (TRM) cells in the lungs. The increased production of mucosal IgG and IgA antibody titers was also observed, resulting in further improvements to protection against a virus challenge, compared with the pure oral immunization group. Salmonella-delivered in situ nanoparticles efficiently increased the cellular immune response, compared with the monomer, and sequential immunization further improved the systemic immune response, as shown by the activation of DCs, the production of TEM cells and TRM cells, and the mucosal immune response, thereby providing us with a novel strategy by which to apply nanoparticle-based vaccines in the future. IMPORTANCE Salmonella-delivered in situ nanoparticle platforms may provide novel nanoparticle vaccines for oral administration, which would be beneficial for veterinary applications. The combination of administering Salmonella-vectored, self-assembled nanoparticles and an intranasal boost with purified nanoparticles significantly increased the production of effector memory T cells and lung resident memory T cells, thereby providing partial protection against an influenza virus challenge. This novel strategy could open a novel avenue for the application of nanoparticle vaccines for veterinary purposes.

Protective effects of E. coli Nissle 1917 on chickens infected with Salmonella pullorum

The probiotic E. coli Nissle 1917 (EcN) plays an important role in regulating the microbial components of the gut and preventing inflammation of the gastrointestinal tract. Currently, the long-term use of antibiotics for the treatment of lethal white diarrhea in chicks caused by Salmonella has led to increased morbidity and mutation rates. Therefore, we want to use EcN as an antibiotic alternative as an alternative approach to prevent Salmonella-induced white diarrhea in chickens. To date, there are no reports of EcN being used for the prevention and control of Salmonella pullorum (S. pullorum) in chickens. In vitro, pretreatment with EcN significantly decreased the cellular invasion of S. pullorum CVCC533 in a chicken fibroblast (DF-1) cell model. Then, 0-day-old egg-laying chickens were orally inoculated with EcN at a dose of 10⁹ CFU/100 μL at either Day 1 (EcN1) or both Day 1 and Day 4 (EcN2). Then, S. pullorum CVCC533 was used to challenge the cells at a dose of 1.0 × 10⁷ CFU/100 μL on Day 8. Next, the body weights and survival rates were recorded for 14 consecutive days, and the colonization of S. pullorum in the spleen and liver at 7 days post-challenge (dpc) was determined. Chicken feces were also collected at 2, 4, 6 and 8 dpc to evaluate the excretion of pathogenic bacteria in feces. The liver, duodenum and rectum samples were collected and analyzed by pathological histology at 7 dpc to evaluate the protective effect of EcN on the mucosa, villi and crypts of the small intestine. The spleen and bursa were collected, and the immune organ index was calculated. In addition, the contents of the cecum of chicks were collected at 7 dpc for 16S rRNA sequencing to detect the distribution of microbial communities in the intestine. The results showed that EcN was able to protect against CVCC533 challenge, as shown by decreased body weight loss, mortality and shedding of pathogenic bacteria in fecal samples in the EcN1 plus Salmonella challenge group (EcN1S) but not the EcN2 plus Salmonella challenge group (EcN2S). The pathogenic changes in the liver, duodenum and rectum also demonstrated that one dose but not two doses of EcN effectively prolonged the length of the pilus with decreased crypt depth, indicating its protective effects against S. pullorum. In addition, the 16S rRNA sequencing results suggested that EcN could enlarge the diversity of intestinal flora, decrease the abundance of pathogenic bacteria and increase the abundance of beneficial bacteria, such as Lactobacillus. In conclusion, EcN has shown moderate protection against S. pullorum challenge in chickens.

[Clinicopathological features of spinal solitary fibrous tumor]

Objective: To investigate the clinicopathological, molecular genetic, immunohistochemical and prognostic features of spinal solitary fibrous tumor (SFT). Methods: The clinical data of 12 cases of spinal SFT in Beijing Tsinghua Changgung Hospital, Affiliated to Tsinghua University, diagnosed from January 2015 to December 2021 were collected and reclassified. The clinical data, histopathology, immunohistochemistry and molecular genetics were analyzed. Follow-up and related literature reviews were conducted. Results: Among the 12 patients, there were 5 males and 7 females; the age ranged from 31 to 73 years, with a median age of 50.5 years. All 12 cases were primary tumors, including 4 cases diagnosed at the first time and 8 recurrent cases. Among the 12 cases, 8 were WHO grade 1, 3 were WHO grade 2, and 1 was WHO grade 3. Microscopically, the spinal SFT appeared as a spindle cell tumor, the stroma was rich in many thin-walled blood vessels with various histological features such as cell morphology and necrosis according to the different tumor grade. All (12/12) of the cases expressed vimentin and STAT6 (diffuse and strong nuclear stain), 11 cases (11/12) expressed both CD34 and bcl-2, and 7 cases (7/12) expressed CD99. Next-generation sequencing showed that 12 (12/12) of the patients had NAB2-STAT6 gene fusion. The 12 patients were followed up for 6 to 80 months. There were no recurrences or metastases in the 4 first cases after operation. Among the 8 recurrent cases, 2 of the patients relapsed and 2 died. Conclusions: Spinal SFT is rare and has a high recurrence tendency. Many aspects need to be considered in the diagnosis process. STAT6 is a relatively specific marker for the diagnosis of this tumor. Complete surgical resection is the preferred treatment while postoperative radiotherapy is recommended to reduce tumor recurrence.

[Induction of peripheral blood mononuclear cells to hepatocyte-like cells and preliminary study of cell response to injury under the effect of acetaminophen]

Objective: To establish a method for the induction of peripheral blood mononuclear cells to hepatocyte-like cells, and preliminarily investigate cell response to injury under the effect of acetaminophen (APAP). Methods: The surface marker CD45 of peripheral blood mononuclear cells wase detected cells by using flow cytometry and immunofluorescence methods. The cellular morphology of induced hepatocyte-like cells was observed under an inverted microscope. Real-time fluorescent quantitative PCR (RT-PCR) was used to detect the expression level of hepatocyte-specific genes, such as cytochrome (CY) P1A2, CYP3A4, CYP2C9, albumin (ALB), alpha-fetoprotein (AFP), and hepatocyte nuclear factor (HNF)4α mRNA. Immunofluorescence method was used to detect intracellular hepatocyte markers AFP, HNF4α, and ALB expression at the protein level. Biochemical analyzer was used to detect hepatocyte-specific secretory functions of AFP, ALB, and urea. Luciferase chemiluminescence method was used to detect the activity of key drug metabolizing enzyme CYP3A4. Colorimetric assay was used to detect the effect of the drug acetaminophen on hepatocyte-like cells, and alanine aminotransferase (ALT) was used as an indicator of liver cell injury. The statistical differences between the data were compared with t-test and rank-sum test. Results: The positive expression rate of CD45 cell surface markers isolated from peripheral blood mononuclear cells was about 98%, and hepatocyte-like cell morphology changes appeared on 15th day of induction. Compared with isolated mononuclear cells, CYP1A2, CYP3A4, CYP2C9, ALB, AFP and HNF4α mRNA was markedly elevated. The expression level of AFP, ALB and HNF4α protein were equally increased, and the secretory function of AFP, ALB and urea were enhanced. Compared with primary hepatocytes, CYP1A2, CYP2C9, AFP, HNF4α mRNA, and CYP3A4 mRNA did not decrease. The expression levels of AFP, ALB, and HNF4α proteins in the cells did not decrease, and the secretory function of AFP, ALB, and urea did not decrease. In addition, the CYP3A4 enzyme activity produced by hepatocyte-like cells was similar to that of primary hepatocytes. Compared with hepatocyte-like cells incubated without APAP, hepatocyte-like cells incubated with APAP had higher ALT level. Under the effect of APAP, the ALT level of hepatocyte-like cells was higher than isolated mononuclear cells. Conclusion: Peripheral blood mononuclear cells can be induced into hepatocyte-like cells with partial characteristics of hepatocytes, including the activity of CYP3A4, a key enzyme of hepatocyte drug metabolism. Additionally, preliminarily ALT secretory features reflect the hepatocytes injury under the effect of acetaminophen.

Role of Discoidin Domain Receptor 2 in Craniofacial Bone Regeneration

Bone loss caused by trauma, neoplasia, congenital defects, or periodontal disease is a major cause of disability and human suffering. Skeletal progenitor cell-extracellular matrix interactions are critical for bone regeneration. Discoidin domain receptor 2 (DDR2), an understudied collagen receptor, plays an important role in skeletal development. Ddr2 loss-of-function mutations in humans and mice cause severe craniofacial and skeletal defects, including altered cranial shape, dwarfing, reduced trabecular and cortical bone, alveolar bone/periodontal defects, and altered dentition. However, the role of this collagen receptor in craniofacial regeneration has not been examined. To address this, calvarial subcritical-size defects were generated in wild-type (WT) and Ddr2-deficient mice. The complete bridging seen in WT controls at 4 wk postsurgery was not observed in Ddr2-deficient mice even after 12 wk. Quantitation of defect bone area by micro-computed tomography also revealed a 50% reduction in new bone volume in Ddr2-deficient mice. Ddr2 expression during calvarial bone regeneration was measured using Ddr2-LacZ knock-in mice. Expression was restricted to periosteal surfaces of uninjured calvarial bone and, after injury, was detected in select regions of the defect site by 3 d postsurgery and expanded during the healing process. The impaired bone healing associated with Ddr2 deficiency may be related to reduced osteoprogenitor or osteoblast cell proliferation and differentiation since knockdown/knockout of Ddr2 in a mesenchymal cell line and primary calvarial osteoblast cultures reduced osteoblast differentiation while Ddr2 overexpression was stimulatory. In conclusion, Ddr2 is required for cranial bone regeneration and may be a novel target for therapy.

Endocrine and genetic factors affecting egg laying performance in chickens: a review

1. Egg-laying performance reflects the overall reproductive performance of breeding hens. The genetic traits for egg-laying performance have low or medium heritability, and, depending on the period involved, usually ranges from 0.16 to 0.64. Egg-laying in chickens is regulated by a combination of environmental, endocrine and genetic factors. 2. The main endocrine factors that regulate egg-laying are gonadotropin-releasing hormone (GnRH), prolactin (PRL), follicle-stimulating hormone (FSH) and luteinising hormone (LH). 3. In the last three decades, many studies have explored this aspect at a molecular genetic level. Recent studies identified 31 reproductive hormone-based candidate genes that were significantly associated with egg-laying performance. With the development of genome-sequencing technology, 64 new candidate genes and 108 single nucleotide polymorphisms (SNPs) related to egg-laying performance have been found using genome-wide association studies (GWAS), providing novel insights into the molecular genetic mechanisms governing egg production. At the same time, microRNAs that regulate genes responsible for egg-laying in chickens were reviewed. 4. Research on endocrinological and genetic factors affecting egg-laying performance will greatly improve the reproductive performance of chickens and promote the protection, development, and utilisation of poultry. This review summarises studies on the endocrine and genetic factors of egg-laying performance in chickens from 1972 to 2019.

The Role of Discoidin Domain Receptor 2 in Tooth Development

Collagen signaling is critical for proper bone and tooth formation. Discoidin domain receptor 2 (DDR2) is a collagen-activated tyrosine kinase receptor shown to be essential for skeletal development. Patients with loss of function mutations in DDR2 develop spondylo-meta-epiphyseal dysplasia (SMED), a rare, autosomal recessive disorder characterized by short stature, short limbs, and craniofacial anomalies. A similar phenotype was observed in Ddr2-deficient mice, which exhibit dwarfism and defective bone formation in the axial, appendicular, and cranial skeletons. However, it is not known if Ddr2 has a role in tooth formation. We first defined the expression pattern of Ddr2 during tooth formation using Ddr2-LacZ knock-in mice. Ddr2 expression was detected in the dental follicle/sac and dental papilla mesenchyme of developing teeth and in odontoblasts and the periodontal ligament (PDL) of adults. No LacZ staining was detected in wild-type littermates. This Ddr2 expression pattern suggests a potential role in the tooth and surrounding periodontium. To uncover the function of Ddr2, we used Ddr2^slie/slie mice, which contain a spontaneous 150-kb deletion in the Ddr2 locus to produce an effective null. In comparison with wild-type littermates, Ddr2^slie/slie mice displayed disproportional tooth size (decreased root/crown ratio), delayed tooth root development, widened PDL space, and interradicular alveolar bone defects. Ddr2^slie/slie mice also had abnormal collagen content associated with upregulation of periostin levels within the PDL. The delayed root formation and periodontal abnormalities may be related to defects in RUNX2-dependent differentiation of odontoblasts and osteoblasts; RUNX2-S319-P was reduced in PDLs from Ddr2^slie/slie mice, and deletion of Ddr2 in primary cell cultures from dental pulp and PDL inhibited differentiation of cells to odontoblasts or osteoblasts, respectively. Together, our studies demonstrate odontoblast- and PDL-specific expression of Ddr2 in mature and immature teeth, as well as indicate that DDR2 signaling is important for normal tooth formation and maintenance of the surrounding periodontium.

Changes and analysis of anti-HBs titres after primary immunization in 1- to 16-year-old Chinese children: A hospital-based study

Immunization with the hepatitis B vaccine is the most effective measure to prevent Hepatitis B Virus (HBV) infection. The aim of this study was to investigate the change in antibody levels induced by administration of the hepatitis B vaccine in children aged 1-16 year old in a large sample sized investigation. HBV markers were determined in 93 326 1- to 16-year-old hospitalized children who completed primary immunization as infants from south-west China, Chongqing. Analyses were performed on anti-HBs titre changes with increasing age, and the revaccination effect was evaluated in children aged 7-14. The percentage of protective antibody was between 45.29% and 63.33% in all age groups, but was higher in the 1-, 2- and 3-year-old groups (90.31%, 83.95% and 71.82%, respectively), and the rate of high-responder was 5.03%-10.56%, except in the 1-year-old group (23.33%). Additionally, 3.33%-25.79% of subjects had not seroconverted. There was no significant difference in antibody levels between girls and boys (P > .05). The Geometric Mean Titers in children with confirmed revaccination history were significantly higher than those with unknown or no revaccination history (P < .0001). In conclusion, the overall rate of protective anti-HBs was 67.10% with consecutive age groups from 1 to 16, it decreased from 90.31% to 45.29% for 1- to 8-year-old individuals, and interestingly, the rate increased from 45.46% to 63.33% for subjects aged 9-15. Anti-HBs titres were significantly improved after revaccination. Booster doses are recommended for those without seroconversion, especially children who live in school with other students or have family members with positive HBsAg.

Selective Role of Discoidin Domain Receptor 2 in Murine Temporomandibular Joint Development and Aging

Temporomandibular joint (TMJ) disorders are often associated with development of osteoarthritis-like changes in the mandibular condyle. Discoidin domain receptor 2 (DDR2), a collagen receptor preferentially activated by type I and III collagen found in the TMJ and other fibrocartilages, has been associated with TMJ degeneration, but its role in normal joint development has not been previously examined. Using Ddr2 LacZ-tagged mice and immunohistochemistry, we found that DDR2 is preferentially expressed and activated in the articular zone of TMJs but not knee joints. To assess the requirement for Ddr2 in TMJ development, studies were undertaken to compare wild-type and smallie ( slie) mice, which contain a spontaneous deletion in Ddr2 to produce an effective null allele. Analysis of TMJs from newborn Ddr2^slie/slie mice revealed a developmental delay in condyle mineralization, as measured by micro-computed tomography and histologic analysis. In marked contrast, knee joints of Ddr2^slie/slie mice were normal. Analysis of older Ddr2^slie/slie mice (3 and 10 mo) revealed that the early developmental delay led to a dramatic and progressive loss of TMJ articular integrity and osteoarthritis-like changes. Mutant condyles had a rough and flattened bone surface, accompanied by a dramatic loss of bone mineral density. Mankin scores showed significantly greater degenerative changes in the TMJs of 3- and 10-mo-old Ddr2^slie/slie mice as compared with wild-type controls. No DDR2-dependent degenerative changes were seen in knees. Analysis of primary cultures of TMJ articular chondrocytes from wild-type and Ddr2^slie/slie mice showed defects in chondrocyte maturation and mineralization in the absence of Ddr2. These studies demonstrate that DDR2 is necessary for normal TMJ condyle development and homeostasis and that these DDR2 functions are restricted to TMJ fibrocartilage and not seen in the hyaline cartilage of the knee.

Identification and characterization of a phospholipase A1 activity type three secreted protein, PP_ExoU from Pseudomonas plecoglossicida NB2011, the causative agent of visceral granulomas disease in large yellow croaker (Larimichthys crocea)

Pseudomonas plecoglossicida NB2011, the causative agent of visceral granulomas disease in farmed Larimichthys crocea in China, encodes a predicted type three effector PP_ExoU, a homolog of the cytotoxin ExoU of Pseudomonas aeruginosa. In this study, secretion of PP_ExoU was tested in various broth, the protein was expressed with the pET30a prokaryotic system, the phospholipase A (PLA) activity of the recombinant protein was determined with fluorogenic phospholipid substrates, fusion expression with green fluorescent protein in transfected HeLa cells was investigated, and the lactate dehydrogenase (LDH) level was measured. The results showed the protein was type three secreted in several media; the recombinant protein displayed significant PLA1 activity with ubiquitin. Fluorescence was observed on the cell membrane and scattered in the cytoplasm of HeLa cells expressing catalytic wild-type PP_ExoU, blebbing and stretching developed in the cell membranes indicating of membrane damage. Fluorescence scattered in the cytoplasm of cells expressing the catalytic inactive protein. A significant LDH level was detected in HeLa cells expressing wild-type PP_exoU, but not in the Ser/Asp-mutated protein, suggestion mutation of predicted catalytic residues abolished the PLA activity. This is the first report on the function of a secreted type three protein from P. plecoglossicida.

Abstract P4-03-03: Microenvironment induced DDR2 mediates stromal-cancer interactions and metastasis growth in breast cancer

This abstract was not presented at the symposium.

ZnO nanosheet-assisted immobilization of Ag nanoparticles on graphene/Ni foam for highly efficient reduction of 4-nitrophenol

ZnO nanosheet-assisted immobilization of Ag nanoparticles on graphene/Ni foam forming a novel hybrid structure for catalysis.

Healing Cranial Defects with AdRunx2-transduced Marrow Stromal Cells

Marrow stromal cells (MSCs) include stem cells capable of forming all mesenchymal tissues, including bone. However, before MSCs can be successfully used in regeneration procedures, methods must be developed to stimulate their differentiation selectively to osteoblasts. Runx2, a bone-specific transcription factor, is known to stimulate osteoblast differentiation. In the present study, we tested the hypothesis that Runx2 gene therapy can be used to heal a critical-sized defect in mouse calvaria. Runx2-engineered MSCs displayed enhanced osteogenic potential and osteoblast-specific gene expression in vitro and in vivo. Runx2-expressing cells also dramatically enhanced the healing of critical-sized calvarial defects and increased both bone volume fraction and bone mineral density. These studies provide a novel route for enhancing osteogenesis that may have future therapeutic applications for craniofacial bone regeneration.

Unusually high soil nitrogen oxide emissions influence air quality in a high-temperature agricultural region

Fertilized soils have large potential for production of soil nitrogen oxide (NO_x=NO+NO₂), however these emissions are difficult to predict in high-temperature environments. Understanding these emissions may improve air quality modelling as NO_x contributes to formation of tropospheric ozone (O₃), a powerful air pollutant. Here we identify the environmental and management factors that regulate soil NO_x emissions in a high-temperature agricultural region of California. We also investigate whether soil NO_x emissions are capable of influencing regional air quality. We report some of the highest soil NO_x emissions ever observed. Emissions vary nonlinearly with fertilization, temperature and soil moisture. We find that a regional air chemistry model often underestimates soil NO_x emissions and NO_x at the surface and in the troposphere. Adjusting the model to match NO_x observations leads to elevated tropospheric O₃. Our results suggest management can greatly reduce soil NO_x emissions, thereby improving air quality.

Soil NO_x emissions can significantly impact air quality in agricultural regions, particularly high temperature fertilized systems. Here, the authors investigate NO_x emissions in one such system in California and suggest that the NO_x emissions are the highest ever observed, with implications for air quality.

Inactivation of internalized Salmonella Typhimurium in lettuce and green onion using ultraviolet C irradiation and chemical sanitizers

AIMS

The internalized human pathogens in fresh produce are not effectively removed during conventional washing, and therefore, it may cause foodborne illness when the produce is consumed raw. Thus, effective nonthermal processes are needed to prevent this risk.

METHODS AND RESULTS

Green fluorescence protein-tagged Salmonella Typhimurium was either sprayed on the surface of iceberg lettuce or injected into the bottom part (bulb) of green onions to induce bacterial internalization. The contaminated vegetables were collected after 2 days and subjected to surface disinfection. Different fluencies of UV-C radiation (75-900 mJ cm(-2)) and two fluencies of UV-C (450, 900 mJ cm(-2)) combined with chlorine and peracetic acid (PAA) were applied to the produce to examine the inactivation efficiency of internalized bacteria. A range of 1·96-2·52 log reduction in the internalized Salmonella was achieved when the lettuce was treated with higher UV-C fluency (150, 450, 900 mJ cm(-2)) or UV-C combined with chemical disinfectants. Significant reduction (1·00-1·49 log CFU g(-1)) in internalized Salmonella was observed in green onion treated with UV-C with the fluency of 150 or 900 mJ cm(-2) or UV-C-chlorine/PAA. No significant reduction was observed in either lettuce or green onion treatments when chlorine or PAA was used alone. The food quality measured with firmness was not changed during any treatments. However, a slight colour change was observed in lettuce only when UV-C was used at 900 mJ cm(-2).

CONCLUSION

High fluency UV-C can significantly inactivate the internalized Salmonella in lettuce and green onion while maintaining the food quality.

SIGNIFICANCE AND IMPACT OF THE STUDY

This research provides applicable research outcomes for developing nonthermal methods to inactivate internalized pathogens in fresh produce.

Ozonation as a clean technology for fresh produce industry and environment: sanitizer efficiency and wastewater quality

AIMS

Inactivating microbial contaminants in fresh produce commonly uses chlorine washing. The effectiveness of ozone was explored as an alternative to chlorine in produce washing for ensuring microbial safety while maximizing water reusability.

METHODS AND RESULTS

An ozone washing system was designed to permit continuous addition of contaminated produce and the reuse of washing water. The effectiveness of ozonation (<2 mg l(-1) ) was determined using Bacillus subtilis spores as a stricter measure of efficiency with processing time of 10 min. As a comparison, chlorine (c. 100 mg l(-1) ) was tested in parallel. Water quality characteristics, including chemical oxygen demand, total suspended solids, disinfectants concentration and microbial reduction were measured. Ozonation showed an average of 1·56 log reduction of B. subtilis spores on lettuce, while chlorination achieved a 1·30 log reduction. The effluents after ozonation demonstrated improved water quality, both in physicochemical quality and microbial quality compared to chlorination.

CONCLUSION

Aqueous ozone treatment is effective against microbial contaminants on fresh produce and enables extended use of washing water.

SIGNIFICANCE AND IMPACT OF THE STUDY

The results provide significant data about ozone disinfection efficacy and its impact on the water reusability, which can facilitate the ozone utilization in the fresh produce production as an environmental friendly alternative.

Factors associated with occupational strain among Chinese teachers: a cross-sectional study

OBJECTIVES

With the reform of the education system in China, teachers are suffering from more occupational strain, which is believed to impair their working state indirectly and affect their health. This study assessed occupational strain and explored the related factors among Chinese teachers.

STUDY DESIGN

Cross-sectional with cluster sampling.

METHODS

The study population was composed of 3570 school teachers working in 64 primary and middle schools in Heping District in Shenyang, China. Data were collected using a self-administered questionnaire (the Chinese version of the Occupational Stress Inventory scale). Multivariate linear regression analyses were performed to study the factors related to occupational strain.

RESULTS

The average score on the Personal Strain Questionnaire (PSQ) for the whole study population was 106.5 (107.5 in men and 106.3 in women). Teachers with chronic disease, a greater number of days of sick leave, recent experience of a stressful life event and divorced/separated/widowed status tended to suffer greater strain than their peers. Regression analyses showed that the PSQ score was significantly associated with role overload, role boundary, responsibility and physical environment, and inversely associated with recreation and rational coping. The most crucial predictors of occupational strain were chronic disease, days of sick leave, recent experience of a stressful life event and marital status. Being a class teacher was the strongest indicator of interpersonal strain. Self-care was associated with vocational strain and psychological strain, and inversely associated with physical strain.

CONCLUSIONS

Most teachers in this study experienced a high degree of occupational strain. Chronic disease, days of sick leave, recent experience of a stressful life event and divorced/separated/widowed status played prominent roles in occupational strain. In addition, role overload, role boundary, responsibility and physical environment induce occupational strain, while recreation and rational coping have a positive effect on occupational strain. Interventions such as proper management of chronic diseases and establishment of a balanced work-family life are crucial to reduce occupational strain. Recreation and training in coping abilities are needed to enhance positive working environments and attenuate the occupational strain imposed on teachers.

Relationship between quality of life and occupational stress among teachers

OBJECTIVES

With major changes in the education system and limited resources supplied by the Government, Chinese teachers have been suffering from greater occupational stress in recent years, which is believed to affect their physical and mental health. The aim of this study was to explore the relationship between quality of life and occupational stress in primary and middle school teachers.

STUDY DESIGN

Originals.

METHODS

A cross-sectional study was conducted using cluster sampling. The study population was composed of 3570 school teachers working in 64 primary and middle schools in Heping District in Shenyang, China. A demographic questionnaire, the 36-item Short-Form Health Survey (SF-36) and the Occupational Stress Inventory Revised Edition were employed to collect demographic variables and assess quality of life and occupational stress. Multivariate stepwise linear regression analyses were performed to study the relationship between quality of life and occupational stress.

RESULTS

The mean scores for both male and female teachers in this study were significantly lower than those for the Chinese general population for all dimensions of quality of life, except mental health and vitality (P<0.05). Male teachers scored significantly higher than female teachers for physical functioning, bodily pain, vitality and physical health (P<0.05). Age, role overload, role insufficiency, vocational strain, psychological strain, physical strain, recreation and rational coping were significantly associated with both the physical and mental component summaries of the SF-36 (P<0.05). Gender, physical environment and self-care appeared to be robust indicators of physical health (P<0.05), while role insufficiency, interpersonal strain and social support were strong indicators of mental health (P<0.05).

CONCLUSIONS

In China, teachers have a lower health status than the general population. The quality of life of female teachers is worse than that of male teachers, and deteriorates with age. Occupational stress and strain induce worsening physical and mental conditions for teachers, while coping resources could promote their health. This study suggests that having adequate coping resources, especially social support, in workplaces may be an important factor for improving teachers' quality of life. Moreover, psychological interventions should be set up for teachers, and psychological counselling should be provided to relieve stress and enhance quality of life.

Spectroscopic study on the enhanced excitation of an electron cyclotron resonance nitrogen plasma by pulsed laser ablation of an aluminum target

The influence of pulsed laser ablation of an aluminum target on the nitrogen plasma produced by electron cyclotron resonance (ECR) microwave discharge has been studied by optical emission spectroscopy (OES) with time and space resolution. The continuous wave (CW) feature of the optical emissions from the ECR nitrogen plasma turns to vary with time and space due to pulsed laser ablation and the expansion of the ablation-induced aluminum plume in the nitrogen plasma. The optical emissions from the nitrogen plasma increase significantly and the emission intensity of nitrogen molecular ions is observed to be more than 20 times higher with the target being ablated in comparison to the case without target ablation. The comparison of the optical emissions from the nitrogen plasma with those from the aluminum plume indicates that the excitation enhancement of the nitrogen plasma occurs in the region where the aluminum plume is expanding, revealing that the expansion of the aluminum plume leads to the excitation enhancement of the nitrogen plasma. Relevant mechanisms responsible for the excitation enhancement of the nitrogen plasma through hybrid processes of ECR microwave discharge and pulsed laser ablation are also discussed.

A clinical investigation on garlicin injectio for treatment of unstable angina pectoris and its actions on plasma endothelin and blood sugar levels

To investigate the therapeutic effects and mechanisms of garlicin for treatment of unstable angina pectoris (UAP), garlicin injectio was intravenously dripped 60 mg/day in 34 cases for 10 days. Nitroglycerine was used in 21 cases of the control group. The results showed that the total effective rates in improving symptoms and electrocardiogram after garlicin treatment were respectively 82% and 62%, and that the plasma endothelin and blood sugar levels were markedly lowered in cases with hyperglycemia.

c-Src signaling induced by the adapters Sin and Cas is mediated by Rap1 GTPase

Oncogenic Src proteins have been extensively studied to gain insight into the signaling mechanisms of Src. To better understand signaling through wild-type Src, we used an approach that involves activation of Src signaling through the binding of physiologic ligands to the Src SH3 domain. To this end, we used full-length and truncated versions of the multiadapter molecules Cas and Sin to activate c-Src, and we examined the intracellular pathways that mediate Src signaling under these conditions. We show that although all proteins bind to and are phosphorylated by c-Src, quantitative differences exist in the ability of the different ligands to activate c-Src signaling. In addition, we show that Sin- and Cas-induced Src signaling, as assayed by transcriptional activation, is exclusively mediated through a pathway that involves the adapter Crk and the GTP-binding protein Rap1. These data are in contrast to previous observations showing Ras to mediate signaling downstream of transforming Src alleles. In our system, we found that signaling through the oncogenic SrcY527 mutant is indeed mediated by Ras. In addition, we found that Rap1 also mediates oncogenic Src signaling. Our results show for the first time that Rap1 mediates c-Src kinase signaling and reveal mechanistic differences in the signaling properties of wild-type and transforming Src proteins.

Altered expression of Gi-protein and adenylyl cyclase activity in hearts from one kidney one clip hypertensive rats: effect of captopril

OBJECTIVE

To investigate whether one kidney one clip (1K-1C) hypertensive rats associated with high levels of angiotensin II (Ang II) exhibit enhanced expression and functions of G proteins in the heart and whether the enhanced expression can be attributed to Ang II.

METHODS

The levels of G protein and G protein mRNA in hearts from 1K-1C hypertensive rats were determined by immunoblotting and Northern blotting techniques using specific antibodies and cDNA probes, respectively, for different isoforms of G proteins. Adenylyl cyclase activity, stimulated or inhibited by agonists, was determined to examine the function of G proteins.

RESULTS

The levels of Gialpha-2 and Gialpha-3 proteins and mRNA were significantly increased in hearts from 1K-1C hypertensive rats compared with control rats, whereas the levels of Gsalpha were unchanged. Guanosine 5'-[3'-thio] triphosphate (GTPgammaS), isoproterenol, glucagon, sodium fluoride (NaF) and forskolin (FSK) stimulated adenylyl cyclase activity in hearts from control and hypertensive rats to varying degrees; however, the stimulations were significantly less in hypertensive rats compared with control rats. On the other hand, the inhibitory effect of low concentrations of GTPgammaS on FSK-stimulated adenylyl cyclase activity (an index of Gi function) was significantly enhanced in hearts from 1K-1C hypertensive rats, whereas the inhibitory effect of C-ANF4-23 on adenylyl cyclase was increased and that of Ang II was decreased in hearts from 1K-1C hypertensive rats. Captopril, an angiotensin-converting enzyme inhibitor, restored the augmented levels of Gi proteins and also the altered stimulation and inhibition of adenylyl cyclase by GTPgammaS, stimulatory and inhibitory hormones, respectively, in hearts from hypertensive rats.

CONCLUSION

These data suggest that 1K-1C hypertensive rats exhibit enhanced expression of Gialpha proteins and associated functions that may be attributable to the enhanced levels of Ang II in this model of hypertension.

Stage-specific expression of alpha1,2-fucosyltransferase and alpha1, 3-fucosyltransferase (FT) during mouse embryogenesis

Lex [Galbeta1-4(Fucalpha1-3)GlcNAc] and Ley [Fucalpha1-2Galbeta1-4(Fucalpha1-3)GlcNAc] are both stage-specific embryonic antigens. Lex is first detected on the blastomeres of the 8-cell stage embryo, which correlates with the onset of blastomere compaction. Ley is highly expressed on the surface of the blastocyst, which has been shown to be involved in blastocyst attachment in the mouse. In the present study, mouse alpha1,2-FT (also known as FUT1) and alpha1,3-FT (also known as Fuc-TIV), which were responsible for Lex and Ley formation, were examined in preimplantation stage embryos by reverse transcription-PCR and in situ hybridization. alpha1,3-FT mRNA was detected in all embryos of preimplantation stage, while alpha1,2-FT mRNA emerged in the later stage embryos from 8-cell to 16-cell to the blastocyst. These results indicated the expression of Ley was regulated by alpha1,2-FT. In situ hybridization showed that these two enzyme mRNAs were detected only in morula and blastocyst stage embryos. The alpha1,2-FT and alpha1, 3-FT mRNAs were located in both the inner cell mass and the trophoblast cells. 2-Cell and 4-cell embryos were isolated from the oviduct and cultured in vitro to the 8-cell, morula and blastocyst stage. The expression of alpha1,2-FT and alpha1,3-FT were observed in these embryos developed in vitro; immunohistochemical analysis also showed that Ley expression was positive. These results suggested the stage-specific expression of Ley on the embryos was synthesized by endogenous alpha1,2-FT and alpha1,3-FT rather than transfer from other sources. In addition, the expression of alpha1, 2-FT was differentially regulated and the uterine factor was not prerequisite of the expression of Ley.

[Analysis of bone mineral density and relevant factors in 781 healthy people aged 15 to 50]

OBJECTIVE

To determine further the age to form peak bone mass (PBM) and the factor influencing it and bone mineral density (BMD) and to find an effective way to prevent from osteoporosis in the elderly.

METHODS

BMD was measured in 781 people aged 15 to 50 years and relevant factors in lifestyle were investigated. Multivariate regression was used to analyze the relationship between BMD and lifestyles and to identify both risk and benefit factors for osteoporosis.

RESULTS

For every ten-kilogram increase in body weight, BMD at varied sites increased by an amount of 0.028 - 0.056 g/cm(2) for males and 0.050 - 0.086 g/cm(2) for females, respectively. During their adolescence for males, for every increase of one grade in physical exercise, BMD at varied sites increased by an amount of 0.034 - 0.078 g/cm(2) in males and BMD at lumbar vertebra in males aged 15 - 24 correlated negatively with their total amount of alcohol drinking, and that at lumbar vertebra and of the whole body increased by about 0.035 g/cm(2) in females, which correlated negatively with their total amount of cigarette smoking. Female BMD at lumbar vertebra correlated reversely with their age of menarche and correlated positively with their average time of breast feeding.

CONCLUSION

Increase in physical exercise during puberty could increase PBM for the adolescents and keeping adequate body weight and reducing cigarette smoking and alcohol drinking would benefit for the prevention from age-related osteoporosis.

[Genetic diversity among Chinese peanut rhizobia by rep-PCR analysis]

Repetitive sequences(repetitive extragenic palindromic[REP], and enterobacterial repetitive intergenic consensus [ERIC]) with the polymerase chain reaction(PCR) were used to fingerprint pure DNA extracted from 79 bradyrhizobial strains. These strains included 59 peanut rhizobia [Bradyrhizobium sp. (Arachis)] isolated from root nodules of 24 peanut (Arachis hypogaea L) cultivars from 23 sites in 11 provinces in China, 6 peanut rhizobial strains from other nations, and 14 reference strains of other bradyrhizobia. All the strains were clustered at the level of 11%, 2%, and 11, 24 clusters were obtained at the similarity of 50% with REP-PCR and ERIC-PCR fingerprints, respectively. The results showed that significant genomic diversity exists within the peanut rhizobia from China. Also they suggested that there are different distributions of REP and ERIC in genomic DNA of the peanut rhizobia. The combined results, REP plus ERIC data, were found between the both above. The genomic diversity seems not to correlate with their host and geographic origins. Our results supported this technique is a useful tool for genotypic characterization and identification of rhizobia as well as ecological studies.

[Origin and progress of myelodysplastic syndrome with hypoplasia]

OBJECTIVE

To study the origin and progress of myelodysplastic syndrome (MDS) with hypoplasia.

METHODS

The data of twenty-five cases of hypomyeloplastic MDS diagnosed by our department in the last ten years were analyzed. 17 of the 25 cases were followed up for a long time.

RESULTS

(1) The percentage of hypomyeloplastic MDS was 11.4% of the total 219 MDS patients. The median age of the 25 cases was (44.8 +/- 14.7) years. (2) FAB subtype: There were 11 cases of RA and 14 of RAEB. (3) Hypomyeloplastic MDS seems to be a developmental phase in the clinical course in some of the patients and not a special type of MDS. Hyper- and hypo-myeloplasia could be transformed from one to another. The transformation of myelodysplasia could occur either in the same or and different FAB subtype. (4) Seven of the seventeen cases transformed to acute leukemia (41.2%), 6 cases were AML and 1 was ALL. 3 of the 7 cases transformed to hypomyeloplastic leukemia and the remaining 4 transformed to hypermyeloplastic leukemia. (5) The median time from the diagnosis of RAEB to leukemia transformation, was 27 months in 7 cases with hypoplastic RAEB. (6) No relationship was found between therapeutic medicines and development of hypomyeloplastic MDS.

CONCLUSION

It is suggested that hypomyeloplastic MDS is probably a developmental phase in the clinical course of MDS, but not a special type.

Angiotensin II enhances the expression of Gialpha in A10 cells (smooth muscle): relationship with adenylyl cyclase activity

In the present studies, we have investigated the effect of angiotensin II (AII) on guanine nucleotide regulatory protein (G protein) expression and functions in A10 smooth muscle cells. AII treatment of A10 cells enhanced the levels of inhibitory guanine nucleotide regulatory protein (Gi) as well as Gi mRNA and not of stimulatory guanine nucleotide regulatory protein (Gs) in a concentration-dependent manner as determined by immunoblot and Northern blot analysis, respectively. AII-evoked increased expression of Gialpha-2 and Gialpha-3 was inhibited by actinomycin D treatment (RNA synthesis inhibitor). The increased expression of Gialpha-2 and Gialpha-3 by AII was not reflected in functions, because the GTPgammaS-mediated inhibition of forskolin-stimulated adenylyl cyclase and the receptor-mediated inhibition of adenylyl cyclase by AII and C-ANP4-23 [des(Gln18, Ser19, Gln20, Leu21, Gly22) ANP4-23-NH2] were not augmented but attenuated in AII-treated A10 cells. The attenuation was prevented by staurosporine (a protein kinase C inhibitor) treatment. On the other hand, AII treatment did not affect the expression and functions of stimulatory guanine nucleotide regulatory protein (Gs), however, the stimulatory effects of 5'-O-(3-thiotriphosphate), isoproterenol, and N-ethylcarboxamide adenosine (NECA) on adenylyl cyclase activity were inhibited to various degrees by AII treatment. Staurosporine reversed the AII-evoked attenuation of isoproterenol- and NECA-stimulated enzyme activity. From these results, it can be suggested that AII, whose levels are increased in hypertension, may be one of the possible contributing factors responsible for exhibiting an enhanced expression of Gi protein in hypertension.

Involvement of phosphatidylinositol 3-kinase and mitogen-activated protein kinase pathways in AII-mediated enhanced expression of Gi proteins in vascular smooth muscle cells

We have previously demonstrated that angiotensin II increased Gialpha-2 and Gialpha-3 expression at both protein and mRNA levels in vascular smooth muscle cell (VSMC). The present study was undertaken to investigate the mechanisms responsible for AII-induced enhanced expression of Gi proteins. The levels of Gi protein were determinated by immunoblotting techniques using specific antibodies against Gialpha-2 and Gialpha-3. AII treatment of VSMC increased the levels of Gialpha-2 and Gialpha-3 proteins and actinomycin D, an inhibitor of RNA synthesis attenuated the AII-evoked enhanced expression of Gialpha-2 and Gialpha-3 proteins. In addition, wortmannin, an inhibitor of phosphatidylinositol 3-kinase (PI-3-K), rapamycin, an inhibitor of p70(S6K) and PD 098059, an inhibitor of mitogen-activated protein kinase (MAPK) kinase were able to inhibit AII-induced enhanced expression of Gialpha-2 and Gialpha-3 to various degrees. The attenuation of AII-evoked enhanced levels of Gialpha-2 and Gialpha-3 by PD 098059 was concentration dependent. At 50 microM, PD 098059 was able to completely attenuate the enhanced levels of Gialpha-2 and Gialpha-3 caused by AII treatment. These data suggest that the enhanced expression of Gi-proteins by AII treatment may be attributed to increased RNA synthesis of Gi-proteins, and MAPK kinase, PI-3-Kinase and p70(S6K) may be involved in AII-mediated increased expression of Gi-proteins in VSMC.

Angiotensinogen gene expression is stimulated by the cAMP-responsive element binding protein in opossum kidney cells

It has been reported previously that the addition of isoproterenol or forskolin stimulates the expression of the angiotensinogen (ANG) gene in opossum kidney (OK) 27 cells, an OK cell line with a fusion gene containing the 5'-flanking regulatory sequence of the rat ANG gene fused with a human growth hormone (hGH) gene as a reporter, pOGH (ANG N-1498/+18), permanently integrated into their genomes. To investigate whether the effect of isoproterenol or forskolin on the expression of the ANG gene is mediated via the nuclear 43-kD cAMP-responsive element binding protein (CREB), OK 27 cells were transiently transfected with an expression plasmid containing the cDNA for the 43-kD CREB (pRSV/CREB). The level of expression of the pOGH (ANG N-1498/+18) in OK 27 cells was estimated by the amount of immunoreactive hGH secreted into the culture medium. Transfection of pRSV/CREB alone stimulated the expression of pOGH (ANG N-1498/+18). The addition of isoproterenol or forskolin further enhanced the stimulatory effect of pRSV/ CREB on the expression of pOGH (ANG N-1498/+18). The enhancing effect of isoproterenol was inhibited by the presence of propranolol (an inhibitor of beta-adrenoceptors) and (R)-p-adenosine 3'5'-cyclic monophospho-orthioate (Rp)-cAMP (an inhibitor of cAMP-dependent protein kinase A I and II). Transfection of pRSV/CREB had no effect on the expression of thymidine kinase growth hormone in OK 13 cells, an OK cell line with a fusion gene containing the promoter/enhancer DNA sequence of the viral thymidine-kinase gene fused with an hGH gene as a reporter, thymidine kinase growth hormone, permanently integrated into their genomes. These studies demonstrate that isoproterenol stimulates the expression of ANG gene via the cAMP-dependent protein kinase A and probably via the interaction of the 43-kD CREB with the 5'-flanking region of the ANG gene. Our data indicate that the nuclear 43-kD CREB may have a modulatory role on the expression of the ANG gene in OK cells.

[DNA quantitative analysis of small bowel carcinoma and its clinical significance]

By using computer cytophotometric analysis, aneuploid as well as other 12 parameters of tissue DNA content were measured in 28 cases of small bowel cancer, 5 cases of intestinal adenoma, 6 cases of normal intestinal tissues. The number of aneuploid tumors in intestinal cancer was much higher than in intestinal adenoma. 7 DNA parameters (Entropy of DNA, 2CDI, DNA- grade of neoplasia, 5C Exceeding Rate, 9C Exceeding Rate, Diploid Deviation Quotient and Mean Ploidy) were the valuable indexes that could determine the quality of intestinal lesions, benign or malignant. DNA content didn't correlate with the clinically differentiated degree of pathological tissues, but aneuploid intestinal cancers had a higher malignant degree than non-aneuploid ones, and were more liable to invade and metastasize with low postoperative survival-rate and poor prognosis. 5 DNA parameters (DNA-Index, Medal Value, DNA-grade of neoplasia, Stemline Ploid and 9C Exceeding Rate) had close relation to the prognosis of intestinal cancer, possessing important value to the prognostic analysis of intestinal cancer.

[Study of p53 protein expression in cancers of small intestine and its relationship to clinical course and prognosis]

In order to study the relationship of p53 gene mutation with the occurrence and prognosis of cancer of small intestine, expression of p53 protein was examined. The results showed that p53 protein expression was high in 75% of small intestine cancer, and 21.1% positive in tissues close to cancer. In 7 cases of small intestinal adenoma only one was positive. Sixteen cases of normal tissue of intestine showed negative expression of p53 protein. The study also found that the degree of p53 protein expression was significantly correlated with the degree of tumor cell differention, invasion, metastasis and prognosis.

Bradyrhizobium liaoningense sp. nov., isolated from the root nodules of soybeans

Seventeen strains of extra-slowly growing (ESG) soybean rhizobia isolated from root nodules of Glycine soja and Glycine max growing in five provinces (Liaoning, Heilongjiang, Shanxi, Hubei, and Anhui) in the People's Republic of China were compared with 48 reference strains belonging to the genera Bradyrhizobium, Rhizobium, and Agrobacterium by performing a numerical analysis of 191 phenotypic features. Our results showed that all of the ESG strains examined clustered closely in the genus Bradyrhizobium but were separated from Bradyrhizobium japonicum at the species level and that they could be differentiated from Rhizobium and Agrobacterium species at the genus level. On the basis of the results of our numerical taxonomy analysis, a genomic DNA G & C content analysis, DNA-DNA hybridization experiments, a partial 16S rRNA sequence analysis, a serological analysis, an N and C content analysis, and an N/C ratio analysis of members of the three groups of soybean rhizobia, we propose the name Bradyrhizobium liaoningense sp. nov. for the ESG strains; the type strain of this species is strain 2281.

Alphamethrin-impregnated bed nets for malaria and mosquito control in China

A community-based intervention trial was carried out to evaluate the effectiveness of alphamethrin-impregnated bed nets for control of Plasmodium vivax malaria and its vector in an area of moderate endemicity in southern Henan province, central China in 1990. Malaria incidence was significantly lower in the intervention group than in the comparison group (2.03 vs. 3.57 per 100 person-years at risk). The protective efficacy for malaria incidence was 43%. The prevalence of malaria parasitaemia among children under 10 years old in the intervention group was about one-quarter of that in the comparison group (0.93% vs. 3.25% and 0.71% vs. 1.96% after one and 4 months use of impregnated nets, respectively). Alphamethrin-impregnated bed nets had a mass killing effect on vector mosquitoes. The outdoor person-biting density of Anopheles anthropophagus and A. sinensis decreased by 70.3% and 29.3% respectively. The density of these 2 mosquito species found resting inside treated nets was close to zero. No side effect was found among users of impregnated bed nets. Impregnation with alphamethrin was more effective on polyester than on cotton netting and residual effects lasted at least one year. Use of alphamethrin is less expensive than permethrin and deltamethrin.

[Cytological study on Eclipta prostrata L]

The authors report that the karyotype formula of Eclipta prostrata is K(2n) = 22 = 16m + 6sm, which belongs to "1A" of stebbins, the chromosome composition based on relative length is 2n = 22 = 10M2 + 12M1, and the total length of the chromosome is 29.3 microns. The chromosome volume of E. prostrata has also been calculated.

[Cytologic study of Bidens bipinnata L]

The author reports that the karyotype formula of Bidens bipinnata is K (2n) = 3X = 36 = 27m + 3sm + 6sm (SAT), which belongs to "2A", and that the chromosome composition based on relative length is 2n = 36 = 6L + 9M2 + 18M1 + 3S. The chromosome volume of B. bipinnata is also calculated.