How have US colorectal cancer mortality trends changed in the past 20 years?

In the last two decades, colorectal cancer (CRC) mortality has been decreasing in the United States. However, the mortality trends for the different subtypes of CRC, including different sides of colon, rectosigmoid, and rectal cancer remain unclear. We analyzed the mortality trends of different subtypes of CRC based on Centers for Disease Control and Prevention's Wide-Ranging Online Data for Epidemiologic Research data from 1999 to 2020. We calculated age-adjusted mortality rates (AAMR) per 100,000 individuals and examined the trends over time by estimating the average annual percent change (AAPC) using the Joinpoint Regression Program. Our study shows that the overall CRC rates decreased significantly from 26.42 to 15.98 per 100,000 individuals, with an AAPC of -2.41. However, the AAMR of rectosigmoid cancer increased significantly from 0.82 to 1.08 per 100,000 individuals, with the AAPC of +1.10. Men and Black individuals had the highest AAMRs respectively (23.90 vs. 26.93 per 100,000 individuals). The overall AAMR of CRC decreased for those aged ≥50 years but increased significantly from 1.02 to 1.58 per 100,000 individuals for those aged 15-49 years, with an AAPC of +0.75. Rural populations had a higher AAMR than the urban populations (22.40 vs. 19.60 per 100,000 individuals). Although overall CRC mortality declined, rising trends in young-onset CRC and rectosigmoid cancer warrant attention. Disparities persist in terms of sex, race, and geographic region, and urbanization level, emphasizing the need for targeted public health measures.

Gender, Racial, and Geographical Disparities in Malignant Brain Tumor Mortality in the United States.

Introduction Malignant brain tumors are malignancies which are known for their low survival rates. Despite advancements in treatments in the last decade, the disparities in malignant brain cancer mortality among the US population remain unclear. Methods We analyzed death certificate data from the U.S. CDC WONDER from 1999 to 2020 to determine the longitudinal trends of malignant brain tumor mortality. Malignant brain tumor (ICD-10 C71.0-71.9) was listed as the underlying cause of death. Age-adjusted mortality rates (AAMRs) per 100,000 individuals were calculated by standardizing the AAMR to the year 2000 U.S. population. Results From 1999 to 2020, there were 306,375 deaths due to malignant brain tumor. The AAMR decreased from 5.57 (95% CI, 5.47 - 5.67) per 100,000 individuals in 1999 to 5.40 (95% CI, 5.31-5.48) per 100,000 individuals in 2020, with an annual percent decrease of -0.05 (95% CI, -0.22, 0.12). Whites had the highest AAMR (6.05 [95% CI, 6.02- 6.07] per 100,000 individuals), followed by Hispanics (3.70 [95% CI, 3.64-3.76]) per 100,000 individuals, Blacks (3.09 [95% CI, 3.04-3.14] per 100,000 individuals), American Indians (2.82 [95% CI, 2.64-3.00] per 100,000 individuals), and Asians (2.44 [95% CI, 2.38-2.50] per 100,000 individuals). The highest AAMRs were reported in the Midwest region (5.58 [95% CI, 5.54-5.62]) per 100,000 individuals) and the rural regions (5.66 [95% CI, 5.61 - 5.71] per 100,000 individuals). Conclusions Our study highlights the mortality disparity among different races, geographic regions, and urbanization levels. The findings underscore the importance of addressing the disparities in malignant brain tumors that existed among males, white individuals, and rural populations.

The Effect of Exercise on Cardiotoxicity in Women with Breast Cancer Receiving Anthracycline-Based Chemotherapy: A Systematic Review and Meta-Analysis.

INTRODUCTION: Breast cancer is the most common cancer in women with a 5-year survival over 90%. However, anthracycline-based chemotherapy causes significant cardiotoxicity often requiring discontinuation of chemotherapeutic regimen among breast cancer survivors. We conducted a systematic review and meta-analysis to evaluate the efficacy of exercise training in mitigating anthracycline-related cardiotoxicity among women with breast cancer. METHODS: We searched PubMed, Embase, Cochrane Central Register of Controlled Trials, Web of Science, and Scopus databases. The outcomes of interest were left ventricular ejection fraction (LVEF), global longitudinal strain (GLS), early to atrial filling velocity (E/A) ratio, maximal oxygen consumption (VO2 max), and cardiac output (CO). We used the Cochrane risk-of-bias tool for randomized trials (RoB 2) to assess the risk of bias in individual studies. RESULTS: We identified a total of 596 articles with 5 trials included in the final analysis. Exercise training was associated with an increase in VO2 max compared with no exercise training (mean difference, 3.95 [95% CI, 0.63-7.26]; I2 = 99.68%). Other cardiovascular outcomes such as LVEF (mean difference, 1.76 [95% CI, -1.95 to 5.46]; I2 = 99.44%), GLS (mean difference, 0.30 [95% CI, -0.49 to 1.10]; I2 = 96.63%), E/A ratio (mean difference, 0.05 [95% CI, -0.05 to 0.15]; I2 = 94.16%), and CO (mean difference, 0.38 [95% CI, -0.91 to 1.66]; I2 = 99.73%) are similar between patients who underwent exercise training and those who did not. CONCLUSIONS: Exercise was associated with an improvement in maximal oxygen uptake among women with breast cancer receiving anthracycline-based chemotherapy.

Lappaol F regulates the cell cycle by activating CDKN1C/p57 in human colorectal cancer cells.

CONTEXT: Lappaol F (LAF), a natural lignan from Arctium lappa Linné (Asteraceae), inhibits tumor cell growth in vitro and in vivo. The underlying mechanism involves the suppression of the Yes-associated protein. However, the specific role of LAF in cell cycle regulation remains unknown. OBJECTIVE: This study determined the molecular mechanism by which LAF regulates cell cycle progression. MATERIALS AND METHODS: Various colon cancer cell lines (SW480, HCT15, and HCT116) were treated with LAF (25, 50, and 75 µmol/L) for 48 h. The effects of LAF on cell proliferation and cell cycle were determined using sulforhodamine B and flow cytometry assays. Differentially expressed proteins (DEPs) were identified using quantitative proteomics. Bioinformatic analysis of DEPs was conducted via Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. Expression levels of DEPs in the cell cycle pathway were analyzed using RT-qPCR and western blotting. RESULTS: LAF suppressed the proliferation of SW480, HCT15, and HCT116 cells (IC50 47.1, 51.4, and 32.8 µmol/L, respectively) and induced cell cycle arrest at the S phase. A total of 6331 proteins were identified and quantified, of which 127 were differentially expressed between the LAF-treated and untreated groups. GO and KEGG enrichment analyses revealed that DEPs mainly participated in the cell cycle. CDKN1C/p57 showed the most significant differential expression, with the highest fold-change (3.155-fold). Knockdown of CDKN1C/p57 attenuated the S phase cell cycle arrest and proliferation inhibition induced by LAF. CONCLUSION: LAF exerts antitumor effects via S phase arrest by activating CDKN1C/p57 in colorectal cancer cells.

Formicincola oecophyllae gen. nov. sp. nov., a novel member of the family Acetobacteraceae isolated from the weaver ant Oecophylla smaragdina.

In this study, a novel bacterium designated F3b2T was isolated from the gut sample of weaver ant Oecophylla smaragdina and characterised. Strain F3b2T was a Gram-negative, aerobic, non-motile, ovoid-shaped bacterium and grows optimally at 28-30 °C. Its major respiratory quinone is ubiquinone 10 (Q-10) and the major fatty acids are C18:1 ω7c, C19:0 cyclo ω8c and C16:0, representing 85% of the total fatty acids. The 16S rRNA gene sequence of strain F3b2T was highest in similarity to that of Oecophyllibacter saccharovorans DSM106907T and Swingsia samuieinsis NBRC 107927T at 94.35% and 91.96%, respectively. A 16S rRNA gene-based phylogenetic analysis and a core genes-based phylogenomic analysis placed strain F3b2T in a distinct lineage in the family Acetobacteraceae. The phylogenetic placement was supported by lower than species delineation threshold average nucleotide identity (ANI) (≤ 70.2%), in silico DNA-DNA hybridization (DDH) (≤ 39.5%) and average amino acid identity (AAI) (≤ 63.5%) values between strain F3b2T and closest neighbours. These overall genome relatedness indices also supported the assignment of strain F3b2T to a novel genus within Acetobacteraceae. The genome of strain F3b2T was 1.96 Mb with 60.4% G + C DNA content. Based on these results, strain F3b2T represented a novel taxon of Acetobacteraceae, for which we proposed the name Formicincola oecophyllae gen. nov. sp. nov., and strain F3b2T (= LMG 30590T = DSM 106908T = NBRC 113640T = KCTC 62951T) as the type strain.

A Cross-Sectional Evaluation of Complementary and Alternative Medicine Use in a Non-urban Malaysian Population.

Complementary and alternative medicine (CAM) therapies have been an integral part of Malaysia culture for many centuries. In recent years influences from other parts of the world have gained a foot-hold in Malaysian popular culture. We investigated the engagement with CAM in a non-urban, Malaysian population. We investigated the association of CAM use with cultural influence, perceived health status, gender and age. We recruited 700 adult participants to this study across three sites in central Malaysia. We found massage, Vitamin supplements, Herbal medicine and traditional Chinese medicine to be the most popular CAM modalities with participation at 67.7%, 55.7%, 55.5% and 26.3% respectively. CAM use was equally high at 67% among those people who claimed a predominantly Malay or Chinese cultural influence. The use of vitamins and participation in yoga were at higher prevalence among female participants compared to males. There was no gender difference for other CAM modalities. There were differences between age groups for most CAM modalities, and those over 50 years tended to be the highest frequency users for most modalities. There is a high rate of CAM use in non-urban Malaysia with younger people being more engaged with less traditional modalities such as aromatherapy, yoga and music therapy.

Impact of sense of coherence, resilience and loneliness on quality of life amongst older adults in long-term care: A correlational study using the salutogenic model.

AIMS: This study aimed to identify the predicting factors of quality of life (QoL) from a set of psychosocial, sociodemographic and clinical variables amongst older adults in a long-term care setting. DESIGN: A cross-sectional, descriptive correlational study. METHOD: The study was conducted in a nursing home and a day care centre from July to December 2019. Two hundred older adults were recruited. Guided by the salutogenic model, the sense of coherence (SOC) scale, Connor-Davidson resilience scale, de Jong Gierveld loneliness scale and World Health Organization quality of life instrument-older adults (WHOQOL-OLD) were used. The sociodemographic and clinical profiles of participants were collected. Descriptive statistics, Pearson product-moment correlation coefficient, independent-samples t test, one-way analysis of variance and stepwise regression were utilised in the analysis. RESULTS: The mean score for WHOQOL-OLD was 94.42 ± 19.55. The highest mean score was observed in the "Death and Dying" facet, while the lowest mean scores were reflected in the "Autonomy" and "Intimacy" facets of QoL. Regardless of resident type, most QoL scores were similar across different variables. Based on the stepwise regression, higher manageability and meaningfulness in SOC, higher resilience, lower social loneliness, lower emotional loneliness and hearing impairments are significantly associated with higher QoL. CONCLUSION: Manageability, meaningfulness and resilience should be enhanced while ameliorating feelings of loneliness to improve the QoL amongst older adults receiving long-term care. Age, marital status, educational level, care arrangement, body mass index, performance in activities of daily living, comorbidities and hearing and mobility impairments could influence QoL and thus warrant more attention. IMPACT: Future interventions can be conducted in group sessions to facilitate social interaction and alleviate loneliness. More resources should be allocated to enhance older adults' care arrangements and coping mechanisms to provide them with the support, as they face challenges in daily life due to mobility impairment and other restrictions.

Lappaol F, an anticancer agent, inhibits YAP via transcriptional and post-translational regulation.

CONTEXT: Lappaol F (LAF), a natural lignan from Arctium lappa Linné (Asteraceae), inhibits tumour cell growth by inducing cell cycle arrest. However, its underlying anticancer mechanism remains unclear. OBJECTIVE: The effects of LAF on the Hippo-Yes-associated protein (YAP) signalling pathway, which plays an important role in cancer progression, were explored in this study. MATERIALS AND METHODS: Cervical (HeLa), colorectal (SW480), breast (MDA-MB-231) and prostate (PC3) cancer cell lines were treated with LAF at different concentrations and different durations. BALB/c nude mice bearing colon xenografts were intravenously injected with vehicle, LAF (10 or 20 mg/kg) or paclitaxel (10 mg/kg) for 15 days. The expression and nuclear localisation of YAP were analysed using transcriptome sequencing, quantitative PCR, western blotting and immunofluorescence. RESULTS: LAF suppressed the proliferation of HeLa, MDA-MB-231, SW480 and PC3 cells (IC50 values of 41.5, 26.0, 45.3 and 42.9 µmol/L, respectively, at 72 h), and this was accompanied by significant downregulation in the expression of YAP and its downstream target genes at both the mRNA and protein levels. The expression of 14-3-3σ, a protein that causes YAP cytoplasmic retention and degradation, was remarkably increased, resulting in a decrease in YAP nuclear localisation. Knockdown of 14-3-3σ with small interfering RNA partially blocked LAF-induced YAP inhibition and anti-proliferation effects. In colon xenografts, treatment with LAF led to reduced YAP expression, increased tumour cell apoptosis and tumour growth inhibition. CONCLUSION: LAF was shown to be an inhibitor of YAP. It exerts anticancer activity by inhibiting YAP at the transcriptional and post-translational levels.

Planococcus versutus sp. nov., isolated from soil.

A taxonomic study was performed on a novel Gram-stain-positive, coccus-shaped, orange-pigmented motile bacterium, designated as strain L10.15T. The organism was isolated from a soil sample collected in Lagoon Island (close to Adelaide Island, western Antarctic Peninsula) using a quorum-quenching enrichment medium. Growth occurred at 4-30 °C, pH 6-11 and at moderately high salinity (0-15 %, w/v, NaCl), with optimal growth at 26 °C, at pH 7-8 and with 6 % (w/v) NaCl. 16S rRNA gene sequence analysis showed that strain L10.15T belonged to the genus Planococcus and was closely related to Planococcus halocryophilus Or1T (99.3 % similarity), Planococcus donghaensis JH1T (99.0 %), Planococcus antarcticus DSM 14505T (98.3 %), Planococcus plakortidis AS/ASP6 (II)T (97.6 %), Planococcus maritimus TF-9T (97.5 %), Planococcus salinarum ISL-6T (97.5 %) and Planococcus kocurii NCIMB 629T (97.5 %). However, the average nucleotide identity-MUMmer analysis showed low genomic relatedness values of 71.1-81.7 % to the type strains of these closely related species of the genus Planococcus. The principal fatty acids were anteiso-C15 : 0, C16 : 1ω7c and anteiso-C17 :  0, and the major menaquinones of strain L10.15T were MK-5 (48 %), MK-6 (6 %) and MK-7 (44 %). Polar lipid analysis revealed the presence of phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol and aminophospholipid. The DNA G+C content was 39.4 mol%. The phenotypic and genotypic data indicate that strain L10.15T represents a novel species of the genus Planococcus, for which the name Planococcus versutus sp. nov. is proposed. The type strain is L10.15T (=DSM 101994T=KACC 18918T).

Quorum sensing activity of Hafnia alvei isolated from packed food.

Quorum sensing (QS) is a mechanism adopted by bacteria to regulate expression of genes according to population density. N-acylhomoserine lactones (AHLs) are a type of QS signalling molecules commonly found in Gram-negative bacteria which have been reported to play a role in microbial spoilage of foods and pathogenesis. In this study, we isolated an AHL-producing Hafnia alvei strain (FB1) from spherical fish pastes. Analysis via high resolution triple quadrupole liquid chromatography/mass spectrometry (LC/MS) on extracts from the spent supernatant of H. alvei FB1 revealed the existence of two short chain AHLs: N-(3-oxohexanoyl) homoserine lactone (3-oxo-C6-HSL) and N-(3-oxo- octanoyl) homoserine lactone (3-oxo-C8-HSL). To our knowledge, this is the first report of the production of AHLs, especially 3-oxo-C8-HSL, by H. alvei.

EXPRESS: Non-Hodgkin Lymphoma Mortality Disparities Across Different Sexes, Races, and Geographic Locations.

Non-Hodgkin lymphoma (NHL) is one of the common hematological cancers in the United States (U.S.). The mortality rate of NHL in the U.S. is the sixth highest among all cancers. Our study aims to examine the trends and disparity in NHL mortality. We analyzed death certificate data from the Centers for Disease Control and Prevention's Wide-Ranging Online Data for Epidemiologic Research (CDC WONDER) U.S. to determine the NHL mortality trends among the U.S. population aged ≥ 15 years. NHL (ICD-10 C82-85) was listed as the underlying cause of death. Age-adjusted mortality rates (AAMRs) per 100,000 individuals and joinpoint trend analysis were performed to determine the average annual percent change (AAPC) in AAMR trends. From 1999 to 2020, NHL accounted for 457,143 deaths in the United States, of which 54% are men and 46% are women. The NHL AAMR decreased significantly from 10.59 to 6.21 per 100,000 individuals with the AAPC of -2.55. Men had a higher AAMR than women (10.10 vs. 6.29 per 100,000 individuals). Whites recorded the highest AAMR (8.43 per 100,000 individuals), followed by Blacks (5.71 per 100,000 individuals), Hispanics (6.32 per 100,000 individuals), American Indians (5.31 per 100,000 individuals), and Asians (5.10 per 100,000 individuals). Those who lived in the Midwest and the rural areas had the highest AAMR at 8.60 and 8.35 per 100,000 individuals respectively. Despite the declining NHL mortality rate, this study calls for targeted intervention to improve outcomes for susceptible individuals affected by NHL.

Virus Propagation and Cell-Based Colorimetric Quantification.

Zika virus (ZIKV) is a mosquito-borne virus belonging to the genus Flavivirus. ZIKV infection has been associated with congenital brain abnormalities and potentially Guillain-Barré syndrome in adults. Research on ZIKV to understand the disease mechanisms is important to facilitate vaccine and treatment development. The method of quantifying viruses is crucial and fundamental in the field of virology. The focus forming assay (FFA) is a virus quantification assay that detects the viral antigen with antibodies and identifies the infection foci of cells using the peroxidase immunostaining technique. The current study describes the virus propagation and quantification protocol using both 24-well and 96-well (high throughput) formats. Compared with other similar studies, this protocol has further described foci size optimization, which can serve as a guide to expand the use of this assay for other viruses. Firstly, ZIKV propagation is performed in Vero cells for 3 days. The culture supernatant containing ZIKV is harvested and quantitated using the FFA. Briefly, the virus culture is inoculated onto Vero cells and incubated for 2-3 days. Foci formation is then determined after optimized staining processes, including cell fixation, permeabilization, blocking, antibody binding, and incubation with peroxidase substrate. The stained virus foci are visualized using a stereo microscope (manual counting in 24-well format) or software analyzer (automated counting in 96-well format). The FFA provides reproducible, relatively fast results (3-4 days) and is suitable to be used for different viruses, including non-plaque-forming viruses. Subsequently, this protocol is useful for the study of ZIKV infection and could be used to detect other clinically important viruses.

SARS-CoV-2 genomic surveillance in Malaysia: displacement of B.1.617.2 with AY lineages as the dominant Delta variants and the introduction of Omicron during the fourth epidemic wave.

OBJECTIVES: This study reported SARS-CoV-2 whole genome sequencing results from June 2021 to January 2022 from seven genome sequencing centers in Malaysia as part of the national surveillance program. METHODS: COVID-19 samples that tested positive by reverse transcription polymerase chain reaction and with cycle threshold values <30 were obtained throughout Malaysia. Sequencing of SARS-CoV-2 complete genomes was performed using Illumina, Oxford Nanopore, or Ion Torrent platforms. A total of 6163 SARS-CoV-2 complete genome sequences were generated over the surveillance period. All sequences were submitted to the Global Initiative on Sharing All Influenza Data database. RESULTS: From June 2021 to January 2022, Malaysia experienced the fourth wave of COVID-19 dominated by the Delta variant of concern, including the original B.1.617.2 lineage and descendant AY lineages. The B.1.617.2 lineage was identified as the early dominant circulating strain throughout the country but over time, was displaced by AY.59 and AY.79 lineages in Peninsular (west) Malaysia, and the AY.23 lineage in east Malaysia. In December 2021, pilgrims returning from Saudi Arabia facilitated the introduction and spread of the BA.1 lineage (Omicron variant of concern) in the country. CONCLUSION: The changing trends of circulating SARS-CoV-2 lineages were identified, with differences observed between west and east Malaysia. This initiative highlighted the importance of leveraging research expertise in the country to facilitate pandemic response and preparedness.

Emergence of B.1.524(G) SARS-CoV-2 in Malaysia during the third COVID-19 epidemic wave.

The COVID-19 pandemic first emerged in Malaysia in Jan 2020. As of 12th Sept 2021, 1,979,698 COVID-19 cases that occurred over three major epidemic waves were confirmed. The virus contributing to the three epidemic waves has not been well-studied. We sequenced the genome of 22 SARS-CoV-2 strains detected in Malaysia during the second and the ongoing third wave of the COVID-19 epidemic. Detailed phylogenetic and genetic variation analyses of the SARS-CoV-2 isolate genomes were performed using these newly determined sequences and all other available sequences. Results from the analyses suggested multiple independent introductions of SARS-CoV-2 into Malaysia. A new B.1.524(G) lineage with S-D614G mutation was detected in Sabah, East Malaysia and Selangor, Peninsular Malaysia on 7th October 2020 and 14th October 2020, respectively. This new B.1.524(G) group was not the direct descendant of any of the previously detected lineages. The new B.1.524(G) carried a set of genetic variations, including A701V (position variant frequency = 0.0007) in Spike protein and a novel G114T mutation at the 5'UTR. The biological importance of the specific mutations remained unknown. The sequential appearance of the mutations, however, suggests that the spread of the new B.1.524(G) lineages likely begun in Sabah and then spread to Selangor. The findings presented here support the importance of SARS-CoV-2 full genome sequencing as a tool to establish an epidemiological link between cases or clusters of COVID-19 worldwide.

Oecophyllibacter saccharovorans gen. nov. sp. nov., a bacterial symbiont of the weaver ant Oecophylla smaragdina.

In this study, bacterial strains Ha5T, Ta1, and Jb2 were isolated from different colonies of weaver ant Oecophylla smaragdina. They were identified as bacterial symbionts of the ant belonging to family Acetobacteraceae and were distinguished as different strains based on distinctive random-amplified polymorphic DNA (RAPD) fingerprints. Cells of these bacterial strains were Gram-negative, rod-shaped, aerobic, non-motile, catalase-positive and oxidase-negative. They were able to grow at 15-37°C (optimum, 28-30°C) and in the presence of 0-1.5% (w/v) NaCl (optimum 0%). Their predominant cellular fatty acids were C18:1ω7c, C16:0, C19:0ω8c cyclo, C14:0, and C16:0 2-OH. Strains Ha5T, Ta1, and Jb2 shared highest 16S rRNA gene sequence similarity (94.56-94.63%) with Neokomagataea tanensis NBRC106556T of family Acetobacteraceae. Both 16S rRNA gene sequence-based phylogenetic analysis and core gene-based phylogenomic analysis placed them in a distinct lineage in family Acetobacteraceae. These bacterial strains shared higher than species level thresholds in multiple overall genome-relatedness indices which indicated that they belonged to the same species. In addition, they did not belong to any of the current taxa of Acetobacteraceae as they had low pairwise average nucleotide identity (< 71%), in silico DNA-DNA hybridization (< 38%) and average amino acid identity (< 67%) values with all the type members of the family. Based on these results, bacterial strains Ha5T, Ta1, and Jb2 represent a novel species of a novel genus in family Acetobacteaceae, for which we propose the name Oecophyllibacter saccharovorans gen. nov. sp. nov., and strain Ha5T as the type strain.

Current attempts to implement microRNA-based diagnostics and therapy in cardiovascular and metabolic disease: a promising future.

MicroRNAs (miRNAs) are small, noncoding RNAs regulating gene expression at the post-translational level. miRNA-based therapeutic agents are important because of the functionality of miRNAs in regulating lipid and glucose metabolism and their role in the pathogenesis of metabolic disorders such as diabetes and obesity, where dysregulation leads to disease; they are also important in angiogenesis. miRNAs additionally serve as biomarkers in the diagnosis, prognosis and risk assessment of disease and in monitoring the response to treatment. Here, we provide a brief overview of progress in miRNA-based therapeutics in the preclinical and clinical setting and highlight the novel outcomes and opportunities in the diagnosis and treatment of metabolic conditions. In addition, we present the role of miRNAs in stem cell therapy which could have great potential in regenerative medicine.

Cloning and Characterization of the Autoinducer Synthase Gene from Lipid-Degrading Bacterium Cedecea neteri.

The process of intercellular communication among bacteria, termed quorum sensing (QS), is mediated by small diffusible molecules known as the autoinducers. QS allows the population to react to the change of cell density in unison, in processes such as biofilm formation, plasmid conjugation, virulence, motility and root nodulation. In Gram-negative proteobacteria, N-acyl homoserine lactone (AHL) is the common "language" to coordinate gene expression. This signaling molecule is usually synthesized by LuxI-type proteins. We have previously discovered that a rare bacterium, Cedecea neteri, exhibits AHL-type QS activity. With information generated from genome sequencing, we have identified the luxIR gene pair responsible for AHL-type QS and named it cneIR. In this study, we have cloned and expressed the 636 bp luxI homolog in an Escherichia coli host for further characterization. Our findings show that E. coli harboring cneI produced the same AHL profile as the wild type C. neteri, with the synthesis of AHL known as N-butyryl-homoserine lactone. This 25 kDa LuxI homolog shares high similarity with other AHL synthases from closely related species. This work is the first documentation of molecular cloning and characterization of luxI homolog from C. neteri.