Barriers and facilitators to HIV care linkage and retention among older adults diagnosed with HIV in Malaysia: a qualitative study.

INTRODUCTION: Older adults newly diagnosed with HIV experience poorer prognosis and higher mortality compared to those diagnosed at younger ages. We explored the barriers and facilitators in HIV care linkage and retention among newly diagnosed older persons living with HIV (OPLWH) in Malaysia. METHODS: We conducted in-depth interviews with OPLWH and focus group discussions with healthcare providers (HCPs) from five specialties (primary care medicine, psychological medicine, gynecology, geriatrics and infectious disease) at a tertiary hospital between September 2021 to April 2022. All sessions were audio-recorded, transcribed verbatim and analysed thematically. RESULTS: We recruited 16 OPLWH and 7 HCPs. Thirteen OPLWH were male. Eight of them self-identified as men who have sex with men (MSM) and the rest were heterosexual. Diagnosis of HIV was between the ages of 50-61 years old. Barriers and facilitators could be categorized into three levels: individual, interpersonal and institutional. Individual barriers included misinformation about HIV treatment, unable to afford HIV-related services, and belief that life was futile. Interpersonal barriers were HIV-related stigma, poor social and family support, and social prejudice towards MSM. Lastly, institutional barriers were the need for frequent hospital visits, high cost for HIV-related services, a lack of guidance following diagnosis and poor communication with HCPs. Facilitators included doctor or friend support and positive institutional reputation. CONCLUSIONS: Multiple challenges hindered optimal care for OPLWH after HIV diagnosis. Issues like high costs, belief that treatment is futile, and a lack of family support need to be addressed as part of long-term support services for OPLWH.

Interventions to promote colorectal cancer screening among people with a family history of colorectal cancer: A scoping review.

BACKGROUND: The global incidence of colorectal cancer (CRC) is rising, with people having a family history of CRC (PFH-CRC) facing double the risk compared to the average-risk population. Despite this, CRC screening uptake among PFH-CRC remains low. There is a lack of systematic mapping of interventions promoting CRC screening in this high-risk population. OBJECTIVE: We conducted a scoping review to identify the types of interventions targeting PFH-CRC, their effectiveness in increasing CRC screening uptake, and the elements associated with the outcomes. METHODS: The Joanna Briggs Institute methodology for scoping review was followed. The search for eligible articles was conducted from the inception of each database until 17 July 2024 in PubMed, EMBASE, CINAHL, Cochrane, PsycINFO and Web of Science with no restrictions on language. RESULTS: Thirty studies from 1995 to 2023 across 13 countries were included; mostly from high-income countries. There was considerable variability in study design, intervention characteristics, and screening outcomes. Eleven studies used theoretical frameworks in intervention development. Fourteen studies reported statistically significant increases in screening uptake among PFH-CRC, most using complex, multiple-component interventions. Tailored print materials and patient navigation more consistently demonstrated increased screening uptake, while counselling yielded mixed results. CONCLUSION: Interventions for promoting CRC screening uptake in PFH-CRC commonly incorporate print material, patient navigation and counselling, often combined into complex interventions. Future research should include more implementation studies to translate these interventions into real-world settings. Additionally, there are gaps in research from low- and middle-income countries, highlighting the need for further research in these resource-limited settings.

"I suppose in our culture, old means no sex": PLWH and healthcare provider views on factors influencing late HIV testing and diagnosis among older adults in Malaysia.

The proportion of new HIV diagnoses among older adults aged ≥50 years continues to rise. Older adults are at higher risk of late diagnosis which is associated with higher treatment complexity and poorer health outcomes. Few studies in the Asia-Pacific region have explored factors contributing to late presentation and diagnosis in this population. Thus, our study aimed to explore factors influencing late HIV diagnosis among older adults ≥50 years in Malaysia. We conducted in-depth interviews with 16 older adults newly diagnosed with HIV (OPLWH) and focus group discussions with seven healthcare providers (HCPs) from different specialties in an academic tertiary hospital in Malaysia. All sessions were audio-recorded, transcribed verbatim and analysed thematically. Three main themes related to late diagnosis among OPLWH emerged: (1) challenge in recognizing HIV symptoms among older persons, (2) older persons and HCPs having low index of suspicion of HIV and (3) poor acceptance of HIV testing among older persons due to perceived personal and social identities. HCPs often missed HIV symptoms and these collectively culminated in OPLWH experiencing complex diagnostic journeys resulting in late HIV diagnosis. To reduce delays in HIV diagnosis, strategies are needed to improve HIV knowledge and risk perception among both older adults and HCPs.

The use of a multi-disciplinary geriatric telemedicine service (TELEG) and its acceptance at a tertiary care centre in Malaysia.

BACKGROUND: The COVID-19 pandemic has fueled the widespread adoption of telemedicine in healthcare, particularly in Sarawak, Malaysia. This study investigates the use and acceptance of Sarawak's inaugural multidisciplinary geriatric telemedicine service, TELEG. METHODS: This cross-sectional study took place at the Sarawak Heart Centre's geriatric department from July 1, 2021, to April 30, 2022. Convenient sampling included all TELEG-enrolled patients during this period, to achieve minimum sample size of 148. TELEG's utilization was assessed in terms of medication therapy and treatment plan optimization, as well as enhanced healthcare accessibility. Participants' acceptance of TELEG was measured using the Service User Technology Acceptability Questionnaire (SUTAQ) administered through Google Forms. Descriptive statistics percentages illustrated the proportion of participants who found TELEG moderately to highly acceptable. Associations between baseline characteristics and overall acceptance were explored through bivariate analyses, including Pearson's correlation test, independent t-test, and ANOVA. The influence of six SUTAQ dimensions on overall acceptance, multivariable linear regression using enter method was employed. Statistical significance was determined by p-values less than 0.5. RESULTS: Among 180 geriatric patients enrolled in TELEG during the study period, 149 agreed to participate. TELEG led to medication therapy optimization for 88.6% of participants, primarily involving dose adjustment (44.7%), de-prescribing (31.8%), and prescribing (15.9%). Additionally, 53.8% received treatment plan optimization, predominantly in the form of self-care education (56.3%), referrals for further treatment (33.8%), additional laboratory investigations (29.6%), and increased monitoring (26.8%). Among those educated in self-care (n = 40), dietary intake (27.5%), lower limb exercise (25.0%), and COVID-19 vaccination (12.5%) were the most common topics. All participants expressed moderate to high acceptance of TELEG (mean = 4.9, SD = 0.65, on a scale of 1 to 6). Notably, care personnel concern (B = 0.256; p < 0.001) had the most significant impact on overall acceptance. CONCLUSION: This pioneering study evaluates the utilization and user acceptance of a geriatric telemedicine service in the region, providing valuable insights to support its expansion. Follow-up surveys or interviews to gain insights into users' experiences are crucial to further enhance acceptance.

Acceptability and tolerability of alcohol-based hand rubs among health workers and concessionaires in Malaysia during the COVID pandemic: a hospital-wide cross-sectional study using a modified WHO protocol.

This study evaluated the acceptability and tolerability of three alcohol-based hand rubs (ABHRs) at Sarawak General Hospital, Malaysia. Conducted from 12-26 November 2021 using a modified WHO Protocol, it involved a survey among health workers and concessionaires, with a 35% response rate (1,598 of 4,628 participants). The majority were nurses (60.8%), with the medical division most represented (28.4%). Most respondents (93.2%) used ABHRs at least five days a week and found them easily accessible (72.3%). Product B was the preferred ABHR (65%), primarily for its color and fragrance, surpassing WHO's 50% approval rate in these aspects. However, no other product features met WHO criteria. There were no significant differences in self-reported skin tolerability across the products, and none achieved overall WHO approval. These results offer important insights for ABHR selection in developing countries and highlight the value of the WHO Protocol in assessing product acceptability and tolerability.

Decision-making for Risk-reducing Salpingo-oophorectomy (RRSO) in Southeast Asian BRCA Mutation Carriers With Breast Cancer: A Qualitative Study.

BACKGROUND: The uptake of risk-reducing salpingo-oophorectomy (RRSO) in Asian countries is variable despite being the most effective option for ovarian cancer risk reduction in BRCA mutation carriers. Exploration of factors which may impact the RRSO decision-making of BRCA mutation carriers from Malaysia, a developing country in Southeast Asia, was undertaken. METHODS: In-depth interviews with 28 Malaysian BRCA mutation carriers with a history of breast cancer were conducted in addition to observing their RRSO decision-making consultations in the clinic. RESULTS: The decision-making considerations among the carriers were centered around the overarching theme of "Negotiating cancer risk and womanhood priorities," with the following themes: (1) risk perception, (2) self-preservation, (3) motherhood obligation, and (4) the preciousness of marriage. Cognitive knowledge of BRCA risk was often conceptualized based on personal and family history of cancer, personal beliefs, and faith. Many women reported fears that RRSO would affect them physically and emotionally, worrying about the post-surgical impact on their motherhood responsibilities. Nevertheless, some reported feeling obliged to choose RRSO for the sake of their children. For some, their husband's support and approval were critical, with emotional well-being and sexuality reportedly perceived as important to sustaining married life. Despite reporting hesitancy toward RRSO, women's decisions about choosing this option evolved as their priorities changed at different stages of life. CONCLUSIONS: Recognizing during clinic encounters with Malaysian women that RRSO decision-making involves negotiating the likelihood of developing cancer with the societal priorities of being a woman, mother, and wife may serve to support their decision-making.

Tailoring an online breastfeeding course for Southeast Asian paediatric trainees- A qualitative study of user experience from Malaysia and Thailand.

BACKGROUND: This study explored the user experiences of paediatric postgraduate trainees in Malaysia and Thailand in using a 2 h and 15 min online module for breastfeeding developed for Southeast Asia, which was adapted from existing European online modules for European and German Continuing Medical Education (CME) credits. METHODS: A qualitative study using focus group discussions (FGDs) was conducted with paediatric postgraduate trainees who used an online English-language breastfeeding module in two Thai universities (May 2020, done online) and two Malaysian universities (Sept- Nov 2019, in-person). FGDs explored module usability and utility. Sessions were transcribed verbatim and analysed thematically. The process of coding was done collaboratively by Thai and Malaysian researchers. RESULTS: Twenty Six resident trainees participated (Thai, n = 13; Malaysian, n = 13). Ages ranged from 29-34 years old, with 21 females. Nineteen participants had never used online learning modules prior to this. Participants took between 1 to 5 sessions to complete the breastfeeding module. Four themes emerged from their experience. 1) The online learning module was more engaging and detailed than previous lectures, courses and/or books, but lacked hands-on training. 2) Using an online platform facilitated learning as eased navigation and resource searching, however, problems were encountered navigating the module on some devices. 3) Learners preferred less words and more graphics, as this helped them capture key messages. 4) Regionally tailored content elicited a mixed reaction from participants. CONCLUSIONS: Users found that the adapted module compared favourably with previous learning experiences. However, online learning modules lack hands-on training, and implementation should ideally incorporate a mix of both. Consideration of device diversity and preferences for how content was adapted for local settings are needed for tailoring.

Factors Associated with Intention to Donate Hematopoietic Stem Cells among Blood Donors.

INTRODUCTION: Past studies pay little attention to the intention to donate hematopoietic stem cells (HSC) among blood donors. This study investigated the level of and the influence of socio-demographic characteristics, knowledge, attitude, subjective norm and self-efficacy on the intention to donate HSC among blood donors. METHODS: This cross-sectional study recruited blood donors at selected public hospitals in the Malaysian State of Sarawak in 2019. A structured questionnaire was developed based on the review of relevant literature. It gathered information on socio-demographic characteristics, knowledge, attitude, subjective norm and self-efficacy on the intention to donate HSC. Variables with a p value <0.200 in bivariate analysis were included in the variable selection for regression modeling to examine their associations with the intention to donate HSC. RESULTS: A total of 569 blood donors participated (94.5% response rate). Overall, 87.1% reported a positive intention to donate HSC. In the regression model, the factor with the greatest association with intention to donate HSC was subjective norms about HSC donation (ß = 0.35, 95% CI 0.27-0.42), followed by attitude about regulations of HSC donation (ß= 0.21, 95% CI 0.13-0.35), self-efficacy on HSC donation (ß = 0.15, 95% CI 0.09-0.32), attitude about the potential side effects of HSC donation (ß = 0.14, 95% CI 0.02-0.10) and highest education level (ß = 0.10, 95% CI 0.03-0.44). CONCLUSIONS: The findings can be used to formulate a better strategy in promoting HSC donation among blood donors in the region.

Proteomics Analysis of Candida albicans dnm1 Haploid Mutant Unraveled the Association between Mitochondrial Fission and Antifungal Susceptibility.

Candida albicans is a major fungal pathogen, accounting for approximately 15% of healthcare infections with associated mortality as high as 40% in the case of systemic candidiasis. Antifungal agents for C. albicans infections are limited, and rising resistance is an inevitable problem. Therefore, understanding the mechanism behind antifungal responses is among the top research focuses in combating Candida infections. Herein, the recently developed C. albicans haploid model is employed to examine the association between mitochondrial fission, regulated by Dnm1, and the pathogen's response to antifungals. Proteomic analysis of dnm1Δ and its wild-type haploid parent, GZY803, reveal changes in proteins associated with mitochondrial structures and functions, cell wall, and plasma membrane. Antifungal susceptibility testing revealed that dnm1Δ is more susceptible to SM21, a novel antifungal, than GZY803. Analyses of reactive oxygen species release, antioxidant response, lipid peroxidation, and membrane damages uncover an association between dnm1Δ and the susceptibility to SM21. Dynasore-induced mitochondrial inhibition in SC5314 diploids corroborate the findings. Interestingly, Dynasore-primed SC5314 cultures exhibit increased susceptibility to all antifungals tested. These data suggest an important contribution of mitochondrial fission in antifungal susceptibility of C. albicans. Hence, mitochondrial fission can be a potential target for combined therapy in anti-C. albicans treatment.

Quantitative Proteomics of Strong and Weak Biofilm Formers of Enterococcus faecalis Reveals Novel Regulators of Biofilm Formation.

Enterococcus faecalis is a bacterial pathogen associated with both endodontic and systemic infections. The biofilm formation ability of E. faecalis plays a key role in its virulence and drug resistance attributes. The formation of E. faecalis biofilms on implanted medical devices often results in treatment failure. In the present study, we report protein markers associated with the biofilm formation ability of E. faecalis using iTRAQ-based quantitative proteomics approach. In order to elucidate the biofilm-associated protein markers, we investigated the proteome of strong and weak biofilm-forming E. faecalis clinical isolates in comparison with standard American Type Culture Collection (ATCC) control strains. Comparison of E. faecalis strong and weak biofilm-forming clinical isolates with ATCC control strains showed that proteins associated with shikimate kinase pathway and sulfate transport were up-regulated in the strong biofilm former, while proteins associated with secondary metabolites, cofactor biosynthesis, and tetrahydrofolate biosynthesis were down-regulated. In the weak biofilm former, proteins associated with nucleoside and nucleotide biosynthesis were up-regulated, whereas proteins associated with sulfate and sugar transport were down-regulated. Further pathway and gene ontology analyses revealed that the major differences in biofilm formation arise from differences in metabolic activity levels of the strong and weak biofilm formers, with higher levels of metabolic activity observed in the weak biofilm former. The differences in metabolic activity could therefore be a major determinant of the biofilm ability of E. faecalis The new markers identified from this study can be further characterized in order to understand their exact role in E. faecalis biofilm formation ability. This, in turn, can lead to numerous therapeutic benefits in the treatment of this oral and systemic pathogen. The data has been deposited to the ProteomeXchange with identifier PXD006542.

Targeting autophagy enhances the anticancer effect of artemisinin and its derivatives.

Artemisinin and its derivatives, with their outstanding clinical efficacy and safety, represent the most effective and impactful antimalarial drugs. Apart from its antimalarial effect, artemisinin has also been shown to exhibit selective anticancer properties against multiple cancer types both in vitro and in vivo. Specifically, our previous studies highlighted the therapeutic effects of artemisinin on autophagy regulation. Autophagy is a well-conserved degradative process that recycles cytoplasmic contents and organelles in lysosomes to maintain cellular homeostasis. The deregulation of autophagy is often observed in cancer cells, where it contributes to tumor adaptation to nutrient-deficient tumor microenvironments. This review discusses recent advances in the anticancer properties of artemisinin and its derivatives via their regulation of autophagy, mitophagy, and ferritinophagy. In particular, we will discuss the mechanisms of artemisinin activation in cancer and novel findings regarding the role of artemisinin in regulating autophagy, which involves changes in multiple signaling pathways. More importantly, with increasing failure rates and the high cost of the development of novel anticancer drugs, the strategy of repurposing traditional therapeutic Chinese medicinal agents such as artemisinin to treat cancer provides a more attractive alternative. We believe that the topics covered here will be important in demonstrating the potential of artemisinin and its derivatives as safe and potent anticancer agents.

Artemisinin-(Iso)quinoline Hybrids by C-H Activation and Click Chemistry: Combating Multidrug-Resistant Malaria.

A substantial challenge worldwide is emergent drug resistance in malaria parasites against approved drugs, such as chloroquine (CQ). To address these unsolved CQ resistance issues, only rare examples of artemisinin (ART)-based hybrids have been reported. Moreover, protein targets of such hybrids have not been identified yet, and the reason for the superior efficacy of these hybrids is still not known. Herein, we report the synthesis of novel ART-isoquinoline and ART-quinoline hybrids showing highly improved potencies against CQ-resistant and multidrug-resistant P. falciparum strains (EC50 (Dd2) down to 1.0 nm; EC50 (K1) down to 0.78 nm) compared to CQ (EC50 (Dd2)=165.3 nm; EC50 (K1)=302.8 nm) and strongly suppressing parasitemia in experimental malaria. These new compounds are easily accessible by step-economic C-H activation and copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) click reactions. Through chemical proteomics, putatively hybrid-binding protein targets of the ART-quinolines were successfully identified in addition to known targets of quinoline and artemisinin alone, suggesting that the hybrids act through multiple modes of action to overcome resistance.

Quantitative Proteomics Study Reveals Changes in the Molecular Landscape of Human Embryonic Stem Cells with Impaired Stem Cell Differentiation upon Exposure to Titanium Dioxide Nanoparticles.

The increasing number of nanoparticles (NPs) being used in various industries has led to growing concerns of potential hazards that NP exposure can incur on human health. However, its global effects on humans and the underlying mechanisms are not systemically studied. Human embryonic stem cells (hESCs), with the ability to differentiate to any cell types, provide a unique system to assess cellular, developmental, and functional toxicity in vitro within a single system highly relevant to human physiology. Here, the quantitative proteomics approach is adopted to evaluate the molecular consequences of titanium dioxide NPs (TiO2 NPs) exposure in hESCs. The study identifies ≈328 unique proteins significantly affected by TiO2 NPs exposure. Proteomics analysis highlights that TiO2 NPs can induce DNA damage, elevated oxidative stress, apoptotic responses, and cellular differentiation. Furthermore, in vivo analysis demonstrates remarkable reduction in the ability of hESCs in teratoma formation after TiO2 NPs exposure, suggesting impaired pluripotency. Subsequently, it is found that TiO2 NPs can disrupt hESC mesoderm differentiation into cardiomyocytes. The study unveils comprehensive changes in the molecular landscape of hESCs by TiO2 NPs and identifies the impact which TiO2 NPs can have on the pluripotency and differentiation properties of human stem cells.

Target identification with quantitative activity based protein profiling (ABPP).

As many small bioactive molecules fulfill their functions through interacting with protein targets, the identification of such targets is crucial in understanding their mechanisms of action (MOA) and side effects. With technological advancements in target identification, it has become possible to accurately and comprehensively study the MOA and side effects of small molecules. While small molecules with therapeutic potential were derived solely from nature in the past, the remodeling and synthesis of such molecules have now been made possible. Presently, while some small molecules have seen successful application as drugs, the majority remain undeveloped, requiring further understanding of their MOA and side effects to fully tap into their potential. Given the typical promiscuity of many small molecules and the complexity of the cellular proteome, a high-flux and high-accuracy method is necessary. While affinity chromatography approaches combined with MS have had successes in target identification, limitations associated with nonspecific results remain. To overcome these complications, quantitative chemical proteomics approaches have been developed including metabolic labeling, chemical labeling, and label-free methods. These new approaches are adopted in conjunction with activity-based protein profiling (ABPP), allowing for a rapid process and accurate results. This review will briefly introduce the principles involved in ABPP, then summarize current advances in quantitative chemical proteomics approaches as well as illustrate with examples how ABPP coupled with quantitative chemical proteomics has been used to detect the targets of drugs and other bioactive small molecules including natural products.

Mismatch between health-care professionals' and patients' views on a diabetes patient decision aid: a qualitative study.

BACKGROUND: Malaysia is an Asian country with population of diverse culture and health perceptions. Patient decision aid (PDA) is a new tool in Malaysia. Patients' and health-care professionals' (HCPs) expectation of a PDA is unknown. AIM: We aimed to explore patients' and health-care professionals'(HCPs) views on the information needed in a patient decision aid (PDA) on insulin initiation developed for patients with type 2 diabetes mellitus (T2DM). DESIGN: We used a qualitative design and thematic approach. SETTING: Three main primary health-care settings in Malaysia: public university-based primary care clinics, public health-care clinics and private general practices. METHOD: We conducted focus groups and one-to-one interviews with a purposive sample of health professionals and patients with type 2 diabetes. RESULTS: We interviewed 18 patients and 13 HCPs. Patients viewed the content of the PDA as simple and clear. However, HCPs felt the PDA might be difficult for patients with low literacy to understand. HCPs thought the PDA was too lengthy. Nevertheless, patients would prefer more information. HCPs tended to focus on benefits of insulin, while patients wanted to know the impact of insulin on their quality of life and practical issues regarding insulin and its side-effects. Patients preferred numbers to weigh the risks and benefits of treatment options. HCPs' views that presenting numbers in a PDA would be too complex for patients to understand. CONCLUSION: It is important to consider including issues related to psycho-social impact of treatment to patients when developing a patient decision aid.

Global DNA hypermethylation in down syndrome placenta.

Down syndrome (DS), commonly caused by an extra copy of chromosome 21 (chr21), occurs in approximately one out of 700 live births. Precisely how an extra chr21 causes over 80 clinically defined phenotypes is not yet clear. Reduced representation bisulfite sequencing (RRBS) analysis at single base resolution revealed DNA hypermethylation in all autosomes in DS samples. We hypothesize that such global hypermethylation may be mediated by down-regulation of TET family genes involved in DNA demethylation, and down-regulation of REST/NRSF involved in transcriptional and epigenetic regulation. Genes located on chr21 were up-regulated by an average of 53% in DS compared to normal villi, while genes with promoter hypermethylation were modestly down-regulated. DNA methylation perturbation was conserved in DS placenta villi and in adult DS peripheral blood leukocytes, and enriched for genes known to be causally associated with DS phenotypes. Our data suggest that global epigenetic changes may occur early in development and contribute to DS phenotypes.

Mechanism-Guided Design and Synthesis of a Mitochondria-Targeting Artemisinin Analogue with Enhanced Anticancer Activity.

Understanding the mechanism of action (MOA) of bioactive natural products will guide endeavor to improve their cellular activities. Artemisinin and its derivatives inhibit cancer cell proliferation, yet with much lower efficiencies than their roles in killing malaria parasites. To improve their efficacies on cancer cells, we studied the MOA of artemisinin using chemical proteomics and found that free heme could directly activate artemisinin. We then designed and synthesized a derivative, ART-TPP, which is capable of targeting the drug to mitochondria where free heme is synthesized. Remarkably, ART-TPP exerted more potent inhibition than its parent compound to cancer cells. A clickable probe ART-TPP-Alk was also employed to confirm that the attachment of the TPP group could label more mitochondrial proteins than that for the ART derivative without TPP (AP1). This work shows the importance of MOA study, which enables us to optimize the design of natural drug analogues to improve their biological activities.

Homologous sense and antisense expression of a gene in Dunaliella tertiolecta.

MAIN CONCLUSION: Dunaliella transformation using antisense and sense technology developed in this study will provide powerful tools for functional analysis and pathway-specific metabolic engineering in Dunaliella for industrial applications. Our aim was to investigate the potential of antisense expression and overexpression of a specific gene, the carotenoid biosynthesis-related (CBR) gene, in the microalgae Dunaliella. DNA amplified from sense and antisense vector constructs was used to transform Dunaliella tertiolecta. The Gateway vector for plant transformation was used to make an expression cassette, and the essential region for Dunaliella transformation was amplified by PCR and used for transformation. The transformation efficiency using a 3.2 kb PCR product was 130 transformants/µg DNA for both sense and antisense transformations. Among 200 BASTA-resistant colonies from the sense transformation and antisense transformation, separately, nine positive transformants for sense expression and five positive transformants for the antisense expression were obtained by genomic DNA PCR. The insertion was also verified by genomic Southern analysis. Among five positive sense transformants, one transformant was tested and verified for the overexpression of CBR-GFP fusion protein by Western blot analysis. One of the five antisense transformants showed almost complete inhibition of gene expression under light stress conditions (400 µmol photons m(-2) s(-1)) as determined by quantitative RT-PCR and Western blot analysis. Although there was no difference in the growth patterns or photosynthetic parameters between the wild type (including the vector control) and transformants, the zeaxanthin content of the antisense CBR mutant was lowered under light stress conditions. Thus, we show that the sense and antisense RNA technology can be easily and strategically used for the functional analysis of interesting gene in D. tertiolecta.

Brassinazole resistant 1 (BZR1)-dependent brassinosteroid signalling pathway leads to ectopic activation of quiescent cell division and suppresses columella stem cell differentiation.

Previous publications have shown that BRI1 EMS suppressor 1 (BES1), a positive regulator of the brassinosteroid (BR) signalling pathway, enhances cell divisions in the quiescent centre (QC) and stimulates columella stem cell differentiation. Here, it is demonstrated that BZR1, a BES1 homologue, also promotes cell divisions in the QC, but it suppresses columella stem cell differentiation, opposite to the action of BES1. In addition, BR and its BZR1-mediated signalling pathway are shown to alter the expression/subcellular distribution of pin-formed (PINs), which may result in changes in auxin movement. BR promotes intense nuclear accumulation of BZR1 in the root tip area, and the binding of BZR1 to the promoters of several root development-regulating genes, modulating their expression in the root stem cell niche area. These BZR1-mediated signalling cascades may account for both the ectopic activation of QC cell divisions as well as the suppression of the columella stem cell differentiation. They could also inhibit auxin-dependent distal stem cell differentiation by antagonizing the auxin/WOX5-dependent pathway. In conclusion, BZR1-/BES1-mediated BR signalling pathways show differential effects on the maintenance of root apical meristem activities: they stimulate ectopic QC division while they show opposite effects on the differentiation of distal columella stem cells in a BR concentration- and BZR1-/BES1-dependent manner.

An intracellular antifreeze protein from an Antarctic microalga that responds to various environmental stresses.

The structure and function of the Antarctic marine diatom Chaetoceros neogracile antifreeze protein (Cn-AFP), as well as its expression levels and characteristics of the ice-binding site, were analyzed in the present study. In silico analysis revealed that the Cn-AFP promoter contains both light- and temperature-responsive elements. Northern and Western blot analyses demonstrated that both Cn-AFP transcript and protein expression were strongly and rapidly stimulated by freezing, as well as temperature and high light stress. Immunogold labeling revealed that Cn-AFP is preferentially localized to the intracellular space near the chloroplast membrane. Recombinant Cn-AFP had clear antifreeze activity. Protein-folding simulation was used to predict the putative ice-binding sites in Cn-AFP, and site-directed mutagenesis of the Cn-AFP b-face confirmed their identification.