Studi ketoksikan dinoflagelata spesies Prorocentrum minimum (Dinophyceae) Schiller (Pavillard)

This study was carried out to determine the toxicity of the dinoflagellate Prorocentrum minimum species that formed massive blooms in Lido Beach, Johor Bahru in July 2002. Clone cultures were established in ES-DK medium at 26o C under a 14:10 hour light dark cycle. Species toxicity was determined by intra peritoneal (i.p) injection of culture extract into mice. Cultured cell extracts were toxic to mice. The major symptoms were muscular paralysis and diarrhea. However no mouse mortality was observed even after 13 hours.  Extracts of cultured cells were also hemolytic on rabbit red blood cells. Keywords: Dinoflagellate, HAB, Prorocentrum minimum, Red Tide dan Toxicity Kajian dilakukan untuk menentukan ketoksikan dinoflagelata spesies Prorocentrum minimum yang menyebabkan kejadian pasang merah besar-besaran di perairan Pantai Lido, Johor Bahru pada Juli tahun 2002. Kultur klon telah dibuat dalam medium ES-DK pada suhu 26o C dan siklus pencahayaan 14:10 jam terang gelap. Ketoksikan spesies diuji dengan penyuntikan ekstrak kultur secara intra peritoneal (i.p.) terhadap tikus. Hasil pengamatan menunjukan ekstrak sel yang dikultur memberikan pengaruh racun kepada tikus. Gejala utama adalah kejang otot dan menceret/diare. Walau bagaimanapun tidak didapati tikus yang mati setelah dilakukan pengamatan selama 13 jam. Ekstrak toksin spesies ini juga menunjukkan pengaruh hemolitik terhadap eritrosit kelinci. Kata kunci: Dinoflagellata, HAB, Prorocentrum minimum, Red Tide dan Toxicit

Studi Ketoksikan Dinoflagelata Spesies Prorocentrum Minimum (Dinophyceae) Schiller (Pavillard)

This study was carried out to determine the toxicity of the dinoflagellate Prorocentrum minimum species that formed massive blooms in Lido Beach, Johor Bahru in July 2002. Clone cultures were established in ES-DK medium at 26o C under a 14:10 hour light dark cycle. Species toxicity was determined by intra peritoneal (i.p) injection of culture extract into mice. Cultured cell extracts were toxic to mice. The major symptoms were muscular paralysis and diarrhea. However no mouse mortality was observed even after 13 hours. Extracts of cultured cells were also hemolytic on rabbit red blood cells. Keywords: Dinoflagellate, HAB, Prorocentrum minimum, Red Tide dan Toxicity Kajian dilakukan untuk menentukan ketoksikan dinoflagelata spesies Prorocentrum minimum yang menyebabkan kejadian pasang merah besar-besaran di perairan Pantai Lido, Johor Bahru pada Juli tahun 2002. Kultur klon telah dibuat dalam medium ES-DK pada suhu 26o C dan siklus pencahayaan 14:10 jam terang gelap. Ketoksikan spesies diuji dengan penyuntikan ekstrak kultur secara intra peritoneal (i

Phylogeny of sea cucumber (echinodermata: holothuroidea) as inferred from 16s mitochondrial rRNa gene sequences

This study aimed to determine phylogenetic relationship between and among selected species of sea cucumbers (Echinodermata: Holothuroidea) using 16S mitochondrial ribosomal RNA (rRNA) gene. Phylogenetic analyses of 37 partial sequences of 16S mitochondrial rRNA gene using three main methods namely neighbour joining (NJ), maximum parsimony (MP) and maximum likelihood (ML) showed the presence of five main genera of sea cucumbers: Molpadia from order Molpadiida and four genera of order Aspidochirotida namely Holothuria, Stichopus, Bohadschia and Actinopyga. All of the 17 species obtained from Malaysia distributed among the main genera except within Actinopyga. Interestingly, Holothuria excellens was out of Holothuria group causing Holothuria to be paraphyletic. High bootstrap value and consistent clustering made Molpadia, Stichopus, Bohadschia and Actinopyga monophyletic. The relationship of Actinopyga with the other genera was unclarified and Stichopus was sister to Molpadia. The latter finding caused the resolution at order level unclear. The pairwise genetic distance calculated using Kimura 2-parameter model further supported and verified findings from the phylogenetic trees. Further studies with more samples and different mitochondrial DNA genes need to be done to get a better view and verification on the molecular phylogeny of sea cucumber

Particle Size Distribution of Copper Mine Tailings from Lohan Ranau Sabah and its Relationship with Heavy Metal Content

Particle size analyses were carried out on copper mine tailings from Lohan, Ranau Sabah. About 99.64% of the tailing particles were < 1000 /lm in size while 52.23%,15.72% and 4.87% were < 125 j.l.m, < 62.5 pm and < 38 j.l.m/respectively. The amount of heavy metal extracted by 0.5 HCI was in the order Mn > Cu > Ni > Zn > Co > Cd and is relatively higher in the finer tailing particles

Phylogeny of sea cucumber (echinodermata: holothuroidea) as inferred from 16s mitochondrial rRNa gene sequences

This study aimed to determine phylogenetic relationship between and among selected species of sea cucumbers (Echinodermata: Holothuroidea) using 16S mitochondrial ribosomal RNA (rRNA) gene. Phylogenetic analyses of 37 partial sequences of 16S mitochondrial rRNA gene using three main methods namely neighbour joining (NJ), maximum parsimony (MP) and maximum likelihood (ML) showed the presence of five main genera of sea cucumbers: Molpadia from order Molpadiida and four genera of order Aspidochirotida namely Holothuria, Stichopus, Bohadschia and Actinopyga. All of the 17 species obtained from Malaysia distributed among the main genera except within Actinopyga. Interestingly, Holothuria excellens was out of Holothuria group causing Holothuria to be paraphyletic. High bootstrap value and consistent clustering made Molpadia, Stichopus, Bohadschia and Actinopyga monophyletic. The relationship of Actinopyga with the other genera was unclarified and Stichopus was sister to Molpadia. The latter finding caused the resolution at order level unclear. The pairwise genetic distance calculated using Kimura 2-parameter model further supported and verified findings from the phylogenetic trees. Further studies with more samples and different mitochondrial DNA genes need to be done to get a better view and verification on the molecular phylogeny of sea cucumber

Antimicrobial activities of some marine actinonycetes isolated from Malaysians waters

Marine actinobacteria were isolated from sediment and water samples from Malaysian waters using starch-yeast extract agar with seawater and marine agar (Difco) as a selective medium to isolate the actinomycetes. Ten isolates were selected from a collection of 300 isolates for further investigations based on colony morphology and pigment production. Genomic DNA from these isolates were extracted and subjected to polymerase chain reaction (PCR) to detect the presence of polyketide synthase type I (PKS-I) and non-ribosomal peptide syntethases (NRPS) [1]. Molecular identification was also performed using 16S rRNA gene partial sequencing. A phylogenetic tree based on 16S rRNA gene sequences was constructed using MEGA version 4 [2]. Scanning electron microscopy (SEM) was also performed on these isolates. Evaluation of antimicrobial activity was performed for isolates that exhibited the presence of both PKS-I and NRPS genes, and NRPS gene only. These isolates were challenged against of 5 Gram negative bacteria - E.coli, P. vulgaris, P. aeruginosa, P. mirabilis and S. marcescens; 3 Gram positive bacteria – Methicillin-resistant S. aureus (MRSA), B.subtilis and S. aureus; and 3 fungi - Candida parapsilosis, A. niger and Candida albican. The antimicrobial test was conducted by placing the isolates on trypticase soy agar (TSA) which had been inoculated with the test organisms. The antimicrobial activity was determined as a clear zone of inhibition surrounding the isolate. Eight isolates exhibited the presence of both PKS-I and NRPS genes of which 5 isolates belong to the genus Streptomyces, while another 2 isolates displayed only NRPS gene. Five isolates, mostly Streptomyces species demonstrated high antimicrobial activity against most of the test organisms which could be related to the presence of PKS-I and NRPS genes. Streptomycetes produce approximately 75% of commercially and medically useful antibiotics worldwide [3] therefore, it was anticipated that the Streptomycetes isolates in this study would display high antimicrobial activities. However, 2 isolates displayed no antimicrobial activity at all even though both genes were detected in them. Based on 16S rRNA gene sequencing, these isolates were presumed to belong to the genus Rhodococcus and Pseudonocardia. The presence PKS-I and NRPS genes might not necessarily result in antimicrobial activities since the function of polyketides is not confined to antimicrobial activities but may have other useful properties such as antihelmintics, anticancer or immunosuppressive agents [4].Nevertheless, early evaluation of these isolates based on the presence of both genes would allow to focus the screening of isolates that possessed high metabolic potential. In conclusion, Malaysian waters have the potential as important natural resources for exploration of marine actinomycetes that possess the ability to produce a relatively high rate of new antimicrobial bioactive agents

Occurrence of potentially toxic benthic marine dinoflagellate in Malaysia

Malaysia is one of the maritime countries affected by seafood poisoning events associated with toxins produced by marine dinoflagellates

Contribution to the current list of Nitzschia species (Bacillariophyceae) in Malaysia

Current occurrence of Nitzschia Hassall from marine and freshwater environment in Malaysia is compiled from current and previously published materials. Phytoplankton was collected using a 20 µm plankton net from waterfronts of Peninsular Malaysia and Borneo. Some Nitzschia cells were successfully isolated and established into clonal cultures. For morphology observation, organic matters of the net samples and cultures were oxidized and removed through acid treatment. Cleaned specimens were observed using light and electron microscopes. The morphology of the Nitzschia cells was described and micrographs are included. In addition to current field sampling, Nitzschia spp. records and distributions in Malaysia had also been compiled from secondary data. Sources of references whereby the Nitzschia species were listed in this article were cited accordingly. This article compiles a total of 11 Nitzschia spp. found in Malaysia including a few revisions and new records. This article could serve as an important reference for Nitzschia taxonomic and distributional study particularly in tropical region.Keywords: distribution, morphology, taxonomy, tropica