Displaying publications 1 - 20 of 21 in total

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  1. Mohd Shukor, N.
    MyJurnal
    Never in the history of modern Malaysia, the general population at all levels are being threatened by food security. Food becoming less available and more expensive. Many factors, both long- and short-term, have contributed to the shortage. At a global level, available data seems to indicate that we have been consuming more than what we produce. Then came the shortfall in global rice production caused by the impact of climate change such as the widespread drought in India and China in 2002, typhoons in the Philippines in 2006, and the major flooding in Bangladesh in 2007. This was followed by the returns of pests such as planthoppers, and the various virus diseases transmitted particularly at regions with growing seasons having abnormally higher temperatures caused by climate change. Since the crisis started, scientists particularly breeders all over the world were requested to strengthen and upgrade the breeding program and facilities for the development of new varieties with increased tolerance to drought, flooding, and salinity as well resistant to insects and diseases. An important pre-requisite for such activities is the free flow of plant genetic resources for food and agriculture (pgrfa). The adoption of the Convention on Biological Diversity (CBD) has drastically slowed down the movement of many plant genetic resources and this has threatened the future supply of food. The International Treaty on Plant Genetic Resource for Food and Agriculture (ITPGRFA or the Treaty) is a global reaction to the rising tide of measures taken by many governments as a result CBD to extend their sovereign control over genetic resources. Many countries felt that those measures are inappropriate for food and agricultural crop genetic resources. The Treaty on the other hand recognizes that access and benefit sharing for agricultural biodiversity must be treated differently from the way it is generally treated under CBD. This paper discusses some of the key points and provisions from the treaty and some issues arising from its negotiation and future implementation in Malaysia.
  2. Nambiar, P., Shukor, N., Tarmidzi, N.R.A., Mohamed, N.H.
    Ann Dent, 2012;19(1):11-18.
    MyJurnal
    To determine the amount of displacement of a structure
    noticed on an image when the tube of a dental X-ray
    machine was shifted vertically and horizontally. In
    addition, various intraoral images were combined with
    dental panoramic images to determine the location of
    structures. Our research is based on the parallax
    technique which requires manipulation of horizontal
    and vertical angulations of the X-ray tube. A metal
    object is positioned on the buccal and palatal side of
    the maxilla on the canine area of a skull. The X-ray
    tube is shifted incrementally to obtain images on
    phosphor plates. Subsequently, panaromic and occlusal
    images were taken to assist in localization of the metal
    object. To obtain a clear image shift of 2-3mm using
    the parallax method, there must be an adequate
    horizontal tube shift of approximately 30-35 degrees.
    When images were used in combination of dental
    panoramic images, it was found that the buccally
    placed structures can be accurately located with the
    periapical or occlusal images. However, the
    displacement of images in the palatally placed
    structures in panoramic imaging is not fully
    appreciated with the principle of parallax method. Tube
    movement of 30-35 degrees horizontally is needed for
    a 2-3 mm image shift. To successfully localize a buccal
    structure, a combination of either periapical or occlusal
    images with a dental panoramic imaging can be
    employed. However, this combination with panoramic
    imaging is limited when looking at palatally placed
    structures.
  3. Harada K, Kinoshita A, Shukor NA, Tachida H, Yamazaki T
    Jpn. J. Genet., 1994 Dec;69(6):713-8.
    PMID: 7857675
    Three species of Shorea (S. leprosula, S. acuminata and S. cursitii) were collected from a natural forest reserve of Malaysia and analyzed for genetic variation using the technique of random amplification of polymorphic DNA (RAPD) by the polymerase chain reaction (PCR). The average number of nucleotide substitutions was estimated. The nucleotide diversities within species were very similar and larger than those found in Drosophila melanogaster. The nucleotide divergences between these species are about 1.5 times the nucleotide diversities within the species, indicating that these species diverged from a common ancestor relatively recently.
  4. Arumugam M, Jamil A, Amiseno RA, Rosli N, Abdul Shukor N
    Malays J Pathol, 2020 Aug;42(2):277-281.
    PMID: 32860382
    INTRODUCTION: Merkel cell carcinoma (MCC) is a rare and aggressive malignancy of the skin, with poor clinical outcomes. Typical conditions include a rapidly growing, solitary dome-shaped, violaceous nodule. Several root causes have been identified - sun exposure, age, lighter skin, immunocompromised state, and polyomavirus infection. Wide local excision is the best treatment. The tumour is radiotherapy-responsive. However, the success rate of the treatment with chemotherapy is rather limited. Immunotherapy has shown promising results. Early detection is important to prevent morbidity and mortality.

    CASE REPORT: In this literature work, we reported on a particular case of MCC, as exhibited by an 84-year-old Chinese woman, and discussed the clinical features and management of MCC.

    DISCUSSION: We highlighted that MCC cases have a link to the polyomavirus 5. Patients who were identified with the Polyomavirus 5, and underwent immunotherapy, were seen to depict much better prognosis.

  5. Kuan, C.H., Ahmad, S. H., Son, R., Yap, E. S. P., Zamri, M. Z., Shukor, N. I. A., et al.
    MyJurnal
    A good temperature management, such as precooling and cold storage, can delay deterioration of fresh produce. In this study, different forced-air precooling times were applied on Musa AAA Berangan to investigate the influence of forced-air precooling time on the changes of quality attributes and consumer acceptance. The banana was subjected to forced-air precooling treatment (5 ± 1°C) for 0, 14, 50, and 120 min and then stored in a cold room (13 ± 1°C) for 2 weeks. Then, all the fruits were transferred to a ripening room (25 ± 2°C) and initiated to ripen with ethylene gas. Quality attributes analyses and sensory evaluations were conducted when the fruits reached maturity index 5. Quality parameters, such as soluble solids concentration, titratable acidity, pulp firmness, and peel colour, showed no significant differences when fruits were precooled at different times. Blackening of peel as a result of chilling injury occurred in fruits treated with forced-air precooling for 50 and 120 min. This blackening significantly influenced consumer acceptance, although it did not affect the pulp colour and taste.
  6. Shahrul AI, Shukor N, Norman NH
    Int J Dent, 2022;2022:2811684.
    PMID: 35103062 DOI: 10.1155/2022/2811684
    Smartphone cameras have advanced at a rapid rate. With this advancement, it is possible to take high quality orthodontic clinical photographs using a smartphone. The aim of this article is to describe the technique to take orthodontic clinical photographs using a smartphone.
  7. Shahrul AI, Mohd Shukor N, Norman NH
    Cureus, 2024 Nov;16(11):e73629.
    PMID: 39677078 DOI: 10.7759/cureus.73629
    High-quality clinical photography is essential in orthodontics, playing a crucial role in diagnosis, treatment planning, patient education, and professional communication. However, capturing consistently clear and detailed orthodontic photographs can be challenging, particularly without knowledge of standardized techniques and equipment. This article provides a comprehensive guide on the key elements of effective orthodontic photography, including camera settings, positioning, and lighting. Illustrating each step in the process aims to equip orthodontists with the skills needed to achieve high-quality, reproducible clinical photos that enhance the quality of patient care and support clinical documentation.
  8. Yahaya A, Wa Kammal WS, Abd Shukor N, Osman SS
    Malays J Pathol, 2019 Apr;41(1):59-63.
    PMID: 31025640
    Alpha-fetoprotein (AFP)-producing carcinoma which microscopically mimics hepatocellular carcinoma (HCC) is a rare entity known as hepatoid adenocarcinoma (HC). They usually arise in the stomach, while oesophageal origin is only occasionally encountered. This tumour is highly aggressive and is associated with a poor prognosis. They frequently metastasise to the liver, thus giving rise to diagnostic difficulty, especially in cases where simultaneous oesophageal and liver mass are present. We reported a case of oesophageal hepatoid carcinoma with multiple liver metastasis, that was associated with an increased serum AFP. The distinction between HCC and HC is important because HC is more aggressive and has a poorer prognosis with limited therapeutic options. An extensive diagnostic work-up which include a thorough clinical history, radiological investigations (computed tomography or magnetic resonance imaging) as well as tissue biopsy supported by a panel of immunohistochemical markers are necessary to aid in the diagnosis of HC.
  9. Ahmad Affandi K, Abd Shukor N, Mohamed Rose I, Raja Ali RA, Masir N
    Malays J Pathol, 2019 Apr;41(1):65-69.
    PMID: 31025641
    INTRODUCTION: Coeliac disease enteropathy is associated with an increased risk of lymphomas. Enteropathy-associated T-cell lymphoma is the principal malignancy related to coeliac disease. However, studies have shown that other types of lymphoma such as diffuse large B-cell lymphoma may also be associated with coeliac disease.

    CASE REPORT: We report a 54-year-old Caucasian man who presented with chronic diarrhoea and weight loss. He was diagnosed with coeliac disease based on positive serology results and duodenal, jejunal, and ileal biopsies that showed villous atrophy. Despite adherence to a gluten-free diet, there was no clinical remission and enteropathy-associated T cell lymphoma was suspected. Repeated endoscopic biopsy showed persistent mucosal disease but no evidence of lymphoma. Several weeks later he presented with a perforated jejunum. Histology of the resected jejunum showed diffuse infiltration of submucosa and muscularis propria by malignant lymphoid cells sparing the mucosa. The cells expressed CD20, CD79α, CD10 and BCL6 and ki67 of 80%, consistent with diffuse large B-cell lymphoma.

    DISCUSSION: It is suspected that the undetected lymphoma may have contributed to the persistent malabsorption syndrome rendering the patient unresponsive to treatment. Despite thorough clinical and endoscopic evaluation and multiple biopsies, histologic diagnosis of DLBCL was only confirmed following resection of the perforated jejunum.

  10. Kamarudin NA, Abd Shukor N, Farouk WI, Muhammad Hanapi NA, Mohammed F
    Malays J Pathol, 2021 Dec;43(3):389-396.
    PMID: 34958060
    INTRODUCTION: Tumour microenvironment (TME) has been postulated to be involved in cancer development and disease progression. Studies have shown CD10 expressed in cancer-associated fibroblasts (CAF) within TME is associated with aggressive biological behaviour and poor prognosis. The aim of this study was to evaluate stromal CD10 expression in invasive breast cancer and its correlation with tumour stage, grade, Estrogen receptor (ER), Progesterone receptor (PR) and HER2 status.

    MATERIALS AND METHODS: A total of 226 invasive breast carcinoma cases were selected and assembled into tissue microarrays (TMAs). The stromal expression of CD10 was immunohistochemically analysed.

    RESULTS: Stromal CD10 was positive in 67 (29.6%) cases of invasive breast carcinoma. The frequency of positive stromal staining was significantly higher in the cases with ER-negative (P=0.000). CD10 stromal negativity was significantly higher in luminaltype cases (P=0.001). However, there was no correlation between stromal CD10 expression with tumour grade, stage, PR and HER2 status.

    CONCLUSION: Positive CD10 stromal expression correlates with ER-negative invasive breast carcinomas, while negative CD10 stromal expression correlates with luminal type invasive breast carcinomas. This demonstrates that stromal CD10 expression within the TME constitutes a potential prognostic marker and therapeutic target. Future studies are necessary to evaluate other stromal markers within the TME immunohistochemically as well as its molecular basis in order to confirm the definite role of stromal CD10.

  11. Abdullah S, Mohtar F, Abdul Shukor N, Sapuan J
    J Hand Surg Asian Pac Vol, 2017 Dec;22(4):429-434.
    PMID: 29117830 DOI: 10.1142/S0218810417500459
    BACKGROUND: Synthetic scaffold has been used for tissue approximation and reconstructing damaged and torn ligaments. This study explores the ability of tendon ingrowth into a synthetic scaffold in vitro, evaluate growth characteristics, morphology and deposition of collagen matrix into a synthetic scaffold.

    METHODS: Upper limb tendons were harvested with consent from patients with crush injuries and non-replantable amputations. These tendons (both extensor and flexor) measuring 1 cm are sutured to either side of a 0.5 cm synthetic tendon strip and cultured in growth medium. At 2, 4, 6 and 8 weeks, samples were fixed into paraffin blocks, cut and stained with haematoxylin-eosin (H&E) and Masson's trichrome.

    RESULTS: Minimal tendon ingrowth were seen in the first 2 weeks of incubation. However at 4 weeks, the cell ingrowth were seen migrating towards the junction between the tendon and the synthetic scaffold. This ingrowth continued to expand at 6 weeks and up to 8 weeks. At this point, the demarcation between human tendon and synthetic scaffold was indistinct.

    CONCLUSIONS: We conclude that tendon ingrowth composed of collagen matrix were able to proliferate into a synthetic scaffold in vitro.

  12. Jalaludin ND, Mohd Dusa N, Hassan MR, Abd Shukor N
    Malays J Pathol, 2017 Dec;39(3):209-216.
    PMID: 29279582 MyJurnal
    Soft tissue tumours are a group of remarkably diverse neoplasms that frequently pose significant diagnostic challenges to general pathologists. This study aimed to compare the agreement of histopathological diagnoses between general pathologists from various referral institutes and the referred soft tissue pathologist in a tertiary centre. The common discrepancies and their causes are also presented here. A retrospective study was conducted on 243 cases of potential soft tissue tumours referred to Hospital Kuala Lumpur, Malaysia over a period of 5 years. Reports by the referring pathologists and the soft tissue pathologist were compared based on tumour classification and tumour behaviour. Overall, there was moderate agreement in soft tissue tumour diagnoses in both tumour classification (weighted κ = 0.423) and tumour behavior (weighted κ = 0.548). The highest agreement of tumour classification was seen in the adipocytic tumours (21/28 cases), Ewing sarcoma (5/7 cases) and smooth-muscle tumours (3/5 cases). The highest rates of discrepancies were the so-called fibrohistiocytic tumours (7/11 cases), vascular tumours (9/15 cases) and undifferentiated/ unclassified sarcomas (19/32 cases). Full agreement for tumour behaviour was seen in 178 cases and there were 21 cases of zero agreement. Liposarcoma, alveolar soft part sarcoma and benign fibrous histiocytoma were the most frequent benign/malignant diagnostic discrepancies. The most common causes of discrepancy were wrong morphological interpretation followed by insufficient immunohistochemical stains performed. In conclusion, review of diagnosis by a pathologist specialized in soft tissue improves the quality of diagnosis in these heterogenous and rare tumours. A good panel of immunohistochemical stains with additional molecular study is crucial in the general hospital laboratories practice.
  13. Mohd-Razali S, Ahmad-Affandi K, Ibrahim S, Abdul-Rashid AH, Abdul-Shukor N
    Malays Orthop J, 2023 Mar;17(1):180-183.
    PMID: 37064633 DOI: 10.5704/MOJ.2303.021
    Purpura fulminans (PF) is a severe clinical manifestation of Neisseria meningitides infection that is associated with high mortality rates in children. Survivors are frequently left with debilitating musculoskeletal sequelae. There is a paucity of reports on the musculoskeletal pathology of purpura fulminans. We report on a 2-year-old boy with purpura fulminans due to meningococcemia. The child developed distal gangrene in both the upper and lower limbs. Amputations were done for both lower limbs. Histological examination of the amputated specimens showed an inflammatory process and features of osteonecrosis. The latest follow-up at the age of 6 years showed a right knee valgus due to asymmetrical growth arrest of the proximal tibia. PF and its complications are challenging to treat and may require a multidisciplinary approach to improve patient's functional ability.
  14. Hanim BS, Rahim RA, Mohd Salleh MF, Zakaria H, Abd Shukor N
    Malays J Pathol, 2023 Dec;45(3):463-471.
    PMID: 38155387
    INTRODUCTION: Chorioamnionitis is the inflammation of the placenta and is histologically defined as the presence of neutrophilic infiltration into the chorio-amnion membrane with and without involvement of the umbilical cord. Currently, the inflammatory mediators involved in the eliciting of inflammatory response is still largely under investigation. CD47 and CD36 are pro-inflammatory molecules that are still under investigation. The aim of this study was to determine the expressions of CD47 and CD36 in the placenta of mothers with chorioamnionitis.

    MATERIALS AND METHODS: This was a cross-sectional study, involving a total of 100 cases that comprised of acute subchorionitis (stage I, n=20), acute chorioamnionitis (stage II, n=20), acute necrotising chorioamnionitis (stage III, n=20) and non-chorioamnionitis placenta as control (n=40). All tissue blocks were retrieved from the archived pathology record over a period of 4 years. CD36 and CD47 immunohistochemistry were performed on all cases and their expression in various cell types on the placenta were analysed.

    RESULTS: CD36 was expressed only on the foetal vascular endothelial cells. Interestingly, CD47 showed positive staining on the neutrophils and its expression was significantly different between maternal inflammatory response stage II chorioamnionitis (n=13/20, p<0.001) with stage I and stage III chorioamnionitis.

    DISCUSSION: Our study showed CD47 was expressed in the neutrophils and it was associated with poorer perinatal outcomes and it may have a role in the pathogenesis of chorioamnionitis.

  15. Dualim DM, Loo GH, Suhaimi SNA, Md Latar NH, Muhammad R, Abd Shukor N
    Ann Med Surg (Lond), 2019 Aug;44:57-61.
    PMID: 31312445 DOI: 10.1016/j.amsu.2019.06.013
    Thyroid carcinoma showing thymic-like differentiation (CASTLE) is a rare malignancy of the thyroid gland, and it accounts for 0.1-0.15% of all thyroid cancers. As the name suggests, it has a histological and immunophenotypic resemblance to thymic carcinoma. Preoperative diagnosis of CASTLE can be difficult as its clinical manifestations, and histological characteristic resembles other aggressive and advanced thyroid carcinomas. It is essential to distinguish CASTLE from other aggressive neoplasms as the former has a more favourable prognosis. Immunohistochemical staining with CD5 can help to differentiate thyroid CASTLE from other aggressive thyroid neoplasms. Due to the rarity of this disease, there is no clear definitive treatment strategy. Surgical resection of CASTLE is usually attempted initially. Nodal involvement and extrathyroidal extension are shown to be the main prognostic factors that influenced the survival of patients. Therefore, complete resection of the tumour is vital to reduce local recurrence rates and to improve the chance of long-term survival. Radiotherapy (RT) for CASTLE is an effective treatment. Curative surgery followed by adjuvant RT should be considered in cases with extrathyroidal extension and nodal metastases. With RT, shrinkage of the tumour and reduction of local recurrence rate is possible. With that in mind, we present a case of CASTLE who presented with airway compression symptoms three years after thyroid surgery. He subsequently underwent tumour debulking surgery and a tracheostomy. The patient refused adjuvant chemoradiotherapy, and during our serial follow-up, he is well and symptom-free.
  16. Wan Ahmad Kammal WS, Azman M, Salleh AA, Md Pauzi SH, Abd Shukor N
    Malays J Pathol, 2020 Aug;42(2):283-286.
    PMID: 32860383
    Oncocytic carcinoma of the salivary gland is an uncommon tumour in the head and neck region. Owing to its rarity, identifying the histopathological features of a malignant tumour can be difficult and challenging. We report a case of a 70-year-old man who presented with a left facial weakness for six months in a background history of left parotid swelling over the past 10 years. Clinical examination revealed a 3x3cm left parotid mass and grade 4 facial nerve palsy. Fine needle aspiration of the mass showed scattered cohesive, monolayered sheets of uniform oncocytic cells. Subsequently, a left total parotidectomy and selective neck dissection were performed. Histological examination showed sheets of small oncocytes with minimal nuclear atypia. Evidence of nerve entrapment, capsular invasion and perivascular permeation were identified in focal areas. Thus, a final diagnosis of oncocytic carcinoma was rendered.
  17. Ab Shukor NS, Abdullah R, Abdul Aziz MZ, Samson DO, Musarudin M
    Appl Radiat Isot, 2023 Jun;196:110751.
    PMID: 36871495 DOI: 10.1016/j.apradiso.2023.110751
    The present study was conducted to elucidate the effects of hip prostheses in 192Ir HDR brachytherapy and determine dose uncertainties introduced by the treatment planning. A gynaecological phantom irradiated using Nucletron 192Ir microSelectron HDR source was modeled using MCNP5 code. Three hip materials considered in this study were water, bone, and metal prosthesis. According to the obtained results, a dose perturbation was observed within the medium with a higher atomic number, which reduced the dose to the nearby region.
  18. Mohd R, Mohammad Kazmin NE, Abdul Cader R, Abd Shukor N, Wong YP, Shah SA, et al.
    PLoS One, 2021;16(4):e0249592.
    PMID: 33831052 DOI: 10.1371/journal.pone.0249592
    INTRODUCTION: IgA nephropathy (IgAN) has a heterogeneous presentation and the progression to end stage renal disease (ESRD) is often influenced by demographics, ethnicity, as well as choice of treatment regimen. In this study, we investigated the long term survival of IgAN patients in our center and the factors affecting it.

    METHODS: This study included all biopsy-proven IgAN patients with ≥ 1year follow-up. Patients with diabetes mellitus at diagnosis and secondary IgAN were excluded. Medical records were reviewed for demographics, clinical presentation, blood pressure, 24-hour urine protein, serum creatinine, renal biopsy and treatment received. The primary outcome was defined as combined event of 50% estimated glomerular filtration rate (eGFR) reduction or ESRD.

    RESULTS: We included 130 (74 females; 56 males) patients of mean age 38.0 ± 14.0 years and median eGFR of 75.2 (interquartile range (IQR) 49.3-101.4) ml/min/1.73m2. Eighty-four (64.6%) were hypertensive at presentation, 35 (26.9%) had nephrotic syndrome and 57 (43.8%) had nephrotic range proteinuria (NRP). Median follow-up duration was 7.5 (IQR 4.0-13.0) years. It was noted that 18 (13.8%) developed ESRD and 34 (26.2%) reached the primary outcome. Annual eGFR decline was -2.1 (IQR -5.3 to -0.1) ml/min/1.73m2/year, with median survival of 20 years. Survival rates from the combined event (50% decrease in eGFR or ESRD) at 10, 20 and 30 years were 80%, 53% and 25%, while survival from ESRD were 87%, 73% and 65%, respectively. In the univariate analysis, time-average proteinuria (hazard ratio (HR) = 2.41, 95% CI 1.77-3.30), eGFR <45ml/min/1.73m2 at biopsy (HR = 2.35, 95% CI 1.03-5.32), hypertension (HR = 2.81, 95% CI 1.16-6.80), mean arterial pressure (HR = 1.02, 95% CI 1.01-1.04), tubular atrophy/interstitial fibrosis score (HR = 3.77, 95% CI 1.84-7.73), and cellular/fibrocellular crescent score (HR = 2.44, 95% CI 1.19-5.00) were found to be significant. Whereas only time-average proteinuria (TA-proteinuria) remained as a significant predictor in the multivariate analysis (HR = 2.23, 95% CI 1.57-3.16).

    CONCLUSION: In our cohort, TA-proteinuria was the most important predictor in the progression of IgAN, irrespective of degree of proteinuria at presentation.

  19. Adam SA, Kamaruddin KN, Abd Shukor N, Abdullah Suhaimi SN, Ismail F, Md Yasin M
    Am J Case Rep, 2023 Dec 04;24:e941448.
    PMID: 38048289 DOI: 10.12659/AJCR.941448
    BACKGROUND Breast squamous cell carcinoma (SCC) is a subtype of metaplastic breast carcinoma (MBC), which is a rare malignancy and accounts for 0.1% of all invasive breast carcinomas. Guidelines on definitive management and treatment of breast SCC are not well established, given its rarity and diverse immunohistochemistry (IHC) profile, and lack of clinical data. Most cases of breast SCC are triple-negative breast cancer - negative for estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2). This case report outlines the clinicopathological profile of a pure breast SCC case with a rare IHC profile; HER2 and ER positive. CASE REPORT A 41-year-old woman presented with a right breast mass that had been growing for 2 months. Biopsy confirmed breast SCC, a rare malignancy with IHC profile as follows: HER2 overexpression, ER positive, and PR negative. She underwent neoadjuvant chemotherapy for 3 months followed by right mastectomy with axillary clearance, adjuvant radiotherapy, and oral tamoxifen therapy. Unfortunately, she did not receive anti-HER2 therapy. She developed early locoregional recurrence at 2 months postoperatively, which was treated with excision of the right chest wall and transverse rectus abdominis musculocutaneous (TRAM) flap. She developed liver and lung metastasis and succumbed to her disease at 15 months post-diagnosis. CONCLUSIONS Breast SCC is a rare and aggressive tumor with heterogeneous clinicopathological features. Available guidelines do not outline the definitive treatment for breast SCC, given its rarity and heterogenous IHC profile, leading to a general lack of clinical data. Hence, due to the challenges in managing this rare condition, treatment modalities need to be individualized.
  20. Oh YM, Kim M, Lee-Cruz L, Lai-Hoe A, Go R, Ainuddin N, et al.
    Microb Ecol, 2012 Nov;64(4):1018-27.
    PMID: 22767122 DOI: 10.1007/s00248-012-0082-2
    It is known that the microbial community of the rhizosphere is not only influenced by factors such as root exudates, phenology, and nutrient uptake but also by the plant species. However, studies of bacterial communities associated with tropical rainforest tree root surfaces, or rhizoplane, are lacking. Here, we analyzed the bacterial community of root surfaces of four species of native trees, Agathis borneensis, Dipterocarpus kerrii, Dyera costulata, and Gnetum gnemon, and nearby bulk soils, in a rainforest arboretum in Malaysia, using 454 pyrosequencing of the 16S rRNA gene. The rhizoplane bacterial communities for each of the four tree species sampled clustered separately from one another on an ordination, suggesting that these assemblages are linked to chemical and biological characteristics of the host or possibly to the mycorrhizal fungi present. Bacterial communities of the rhizoplane had various similarities to surrounding bulk soils. Acidobacteria, Alphaproteobacteria, and Betaproteobacteria were dominant in rhizoplane communities and in bulk soils from the same depth (0-10 cm). In contrast, the relative abundance of certain bacterial lineages on the rhizoplane was different from that in bulk soils: Bacteroidetes and Betaproteobacteria, which are known as copiotrophs, were much more abundant in the rhizoplane in comparison to bulk soil. At the genus level, Burkholderia, Acidobacterium, Dyella, and Edaphobacter were more abundant in the rhizoplane. Burkholderia, which are known as both pathogens and mutualists of plants, were especially abundant on the rhizoplane of all tree species sampled. The Burkholderia species present included known mutualists of tropical crops and also known N fixers. The host-specific character of tropical tree rhizoplane bacterial communities may have implications for understanding nutrient cycling, recruitment, and structuring of tree species diversity in tropical forests. Such understanding may prove to be useful in both tropical forestry and conservation.
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