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Fulltext Malaysia Abridged SimSmoke model - towards achieving 2025 and 2045 smoking prevalence targets

Mohamed Nor N, Ross H, Thinng WBK, Abdul Ghani J, Hassan N, Baharom N

Malaysian Journal of Medicine and Health Sciences, 2018;14(3):8-15.
MyJurnal

Introduction: In respond to the World Health Assembly global NCD target of 30% reduction in the prevalence of adult tobacco use by 2025, Malaysian government called for lowering its smoking prevalence to 15% by 2025. In addition, moving towards the endgame target of less than 5% smoking prevalence in 2045. Methods: Malaysia Abridged SimSmoke model, a simulation model uses specific policy parameters, the most recent smoking prevalence, and population size for Malaysia is developed to estimates and access the impact of MPOWER policies in achieving the targets. Results: The 15% prevalence rate in 2025 can be achieved if the Malaysian government increase tobacco excise tax to 72% of the retail price, implement and enforce comprehensive smoke-free air policies, ban all forms of advertising/promotions and run intensive mass media campaigns. Such approach would reduce the number of smokers by about 2.6 million, averting almost 1.3 million premature deaths in the long term. The tobacco endgame target of less than 5% smoking prevalence by 2045 is achievable if the excise tax is further increased to 86.5% of the retail price while all other tobacco control policies are kept at the enhanced level. Conclusions: Both the targeted smoking prevalence are a realistic proposition if the proposed measures are fully implemented. It requires a whole government approach with the MOH as a leading agency driving the process. It is important to monitor both the compliance with the new measures and smoking prevalence to make sure that Malaysia is on track in achieving its targets.

Matched MeSH terms: Population Density
Fulltext A study of hand, food and moth epidemic in Hulu Langat district, 2000. [Tinjauan wabak penyakit tangan, kaki dan mulut (HFMD) di daerah Hulu Langat, 2000]

Meftahuddin Tarip, Jamsiah Mustafa

Malaysian Journal of Public Health Medicine, 2003;3(1):16-22.
MyJurnal

The aim of this study is to describe the epidemiological features of HFMD outbreak in the Hulu Langat District in 2000. Until November 2000, a total of 60 cases were reported and the worst ever reported to the previous years. The mean age of patients was 3.9; 5.8 years with majority of the cases aged between 1 to 4 years old (53.8 per 100,000 of population), male gender (8.3 per 100,000 of populations), and were of Chinese (12.2 per 11 100,000 of populations) and Malay ethnicity (7.2 per 100.000 of populations). All cases were uncomplicated cases and were diagnosed clinically. Most of the notified cases were front the government facilities, which are 44 cases (73.3%). Thirty-five (35) cases (58.4%) were treated as outpatient and 25 cases (41.6%) as in patients (p>0,05). Only 7 cases (11.7%) have history of contact with HFMD patients. The notified cases were mainly from the densely populated areas which were Cheras, Kajang and Ampang. No differences were noted between HFMD cases which have been breasfed for less than 6 month or more, and twenty nine (29) cases (48.3 %) had completed the immunization schedule. In conclusion, the recent emergence of HFMD brings a new challenge, which have to be faced in the prevention and surveillance activities of public health problems in the district.
Study site: Notified cases from Klinik Kesihatan, hospital, private clinics, Ulu Langat, Selangor, Malaysia

Matched MeSH terms: Population Density
Family Physicians' satisfaction with factors affecting the dynamism of the urban family physician program in the Fars and Mazandaran provinces of Iran

Kabir MJ, Hassanzadeh-Rostami Z, Ashrafian Amiri H, Nasrollapour Shirvani SD, Keshavarzi A, Hosseini S

Malays Fam Physician, 2019;14(3):28-36.
PMID: 32175038

Background and objective: A successful family physician program needs ongoing and full cooperation between people and the organizations in charge. Ensuring the satisfaction of family physicians through improvement of the underlying factors could motivate them to provide high-quality services. This study aimed to determine the family physicians' satisfaction level with the factors affecting the dynamism of the urban family physicians program in the Fars and Mazandaran provinces of Iran.
Method: This cross-sectional study was carried out in urban areas in the Fars and Mazandaran provinces in 2016. The sample consisted of 143 and 96 family physicians, respectively, in Fars and Mazandaran provinces and was selected using the stratified random sampling method. Data were collected using a questionnaire and included both sociodemographic variables and factors assessing the family physicians' satisfaction levels. Each factor was scored based on a Likert scale from 0 to 5 points, and any satisfaction level higher than 3 out of 5 was equated with being satisfied.
Results: The overall satisfaction levels among family physicians in Fars and Mazandaran provinces were 2.77±0.53 and 3.37±0.56, respectively, revealing a statistically significant difference between provinces (p<0.001). Moreover, the mean satisfaction scores for the performances of healthcare centers, insurance companies, specialists, healthcare workers, and the population covered were 2.78±0.1, 2.54±0.9, 2.52±0.8, 4.24±0.07, and 2.96±0.8, respectively. The family physicians' levels of satisfaction were significantly correlated with population size (p=0.02, r= -0.106), and willingness to stay in an urban family physician program (p<0.001, r= +0.398).
Conclusion: This study revealed that family physicians exhibited a low level of satisfaction with the urban family physician program. Given the direct association between family physicians' satisfaction levels and retention in the program, it is expected that family physicians will no longer stay in the program, and it is likely to have subsequent executive problems.

Matched MeSH terms: Population Density
A spatio-temporal overview of urbanization and urban change in Malaysia, with special reference to 1970-1980

Chan Kok Eng

Malays J Reprod Health, 1987 Dec;5(2):127-49.
PMID: 12315183
Matched MeSH terms: Population Density*
An overview of the population dynamics in Malaysia

Arshat H, Tey Nai Peng

Malays J Reprod Health, 1988 Jun;6(1):23-46.
PMID: 12281592
Matched MeSH terms: Population Density
Fulltext The Clinical Effectiveness of School Screening Programme for Idiopathic Scoliosis in Malaysia

Deepak AS, Ong JY, Choon D, Lee CK, Chiu CK, Chan C, et al.

Malays Orthop J, 2017 Mar;11(1):41-46.
PMID: 28435573 MyJurnal DOI: 10.5704/MOJ.1703.018

INTRODUCTION: There is no large population size study on school screening for scoliosis in Malaysia. This study is aimed to determine the prevalence rate and positive predictive value (PPV) of screening programme for adolescent idiopathic scoliosis.
MATERIALS AND METHODS: A total of 8966 voluntary school students aged 13-15 years old were recruited for scoliosis screening. Screening was done by measuring the angle of trunk rotation (ATR) on forward bending test (FBT) using a scoliometer. ATR of 5 degrees or more was considered positive. Positively screened students had standard radiographs done for measurement of the Cobb angle. Cobb angle of >10° was used to diagnose scoliosis. The percentage of radiological assessment referral, prevalence rate and PPV of scoliosis were then calculated.
RESULTS: Percentage of radiological assessment referral (ATR >5°) was 4.2% (182/4381) for male and 5.0% (228/4585) for female. Only 38.0% of those with ATR >5° presented for further radiological assessment. The adjusted prevalence rate was 2.55% for Cobb angle >10°, 0.59% for >20° and 0.12% for >40°. The PPV is 55.8% for Cobb angle >10°, 12.8% for >20° and 2.6% for > 40°.
CONCLUSIONS: This is the largest study of school scoliosis screening in Malaysia. The prevalence rate of scoliosis was 2.55%. The positive predictive value was 55.8%, which is adequate to suggest that the school scoliosis screening programme did play a role in early detection of scoliosis. However, a cost effectiveness analysis will be needed to firmly determine its efficacy.

Matched MeSH terms: Population Density
The geography of diversification in mutualistic ants: a gene's-eye view into the Neogene history of Sundaland rain forests

Quek SP, Davies SJ, Ashton PS, Itino T, Pierce NE

Mol Ecol, 2007 May;16(10):2045-62.
PMID: 17498231

We investigate the geographical and historical context of diversification in a complex of mutualistic Crematogaster ants living in Macaranga trees in the equatorial rain forests of Southeast Asia. Using mitochondrial DNA from 433 ant colonies collected from 32 locations spanning Borneo, Malaya and Sumatra, we infer branching relationships, patterns of genetic diversity and population history. We reconstruct a time frame for the ants' diversification and demographic expansions, and identify areas that might have been refugia or centres of diversification. Seventeen operational lineages are identified, most of which can be distinguished by host preference and geographical range. The ants first diversified 16-20 Ma, not long after the onset of the everwet forests in Sundaland, and achieved most of their taxonomic diversity during the Pliocene. Pleistocene demographic expansions are inferred for several of the younger lineages. Phylogenetic relationships suggest a Bornean cradle and major axis of diversification. Taxonomic diversity tends to be associated with mountain ranges; in Borneo, it is greatest in the Crocker Range of Sabah and concentrated also in other parts of the northern northwest coast. Within-lineage genetic diversity in Malaya and Sumatra tends to also coincide with mountain ranges. A series of disjunct and restricted distributions spanning northern northwest Borneo and the major mountain ranges of Malaya and Sumatra, seen in three pairs of sister lineages, further suggests that these regions were rain-forest refuges during drier climatic phases of the Pleistocene. Results are discussed in the context of the history of Sundaland's rain forests.

Matched MeSH terms: Population Density
Fulltext Migratory behaviour is positively associated with genetic diversity in butterflies

García-Berro A, Talla V, Vila R, Wai HK, Shipilina D, Chan KG, et al.

Mol Ecol, 2023 Feb;32(3):560-574.
PMID: 36336800 DOI: 10.1111/mec.16770

Migration is typically associated with risk and uncertainty at the population level, but little is known about its cost-benefit trade-offs at the species level. Migratory insects in particular often exhibit strong demographic fluctuations due to local bottlenecks and outbreaks. Here, we use genomic data to investigate levels of heterozygosity and long-term population size dynamics in migratory insects, as an alternative to classical local and short-term approaches such as regional field monitoring. We analyse whole-genome sequences from 97 Lepidoptera species and show that individuals of migratory species have significantly higher levels of genome-wide heterozygosity, a proxy for effective population size, than do nonmigratory species. Also, we contribute whole-genome data for one of the most emblematic insect migratory species, the painted lady butterfly (Vanessa cardui), sampled across its worldwide distributional range. This species exhibits one of the highest levels of genomic heterozygosity described in Lepidoptera (2.95 ± 0.15%). Coalescent modelling (PSMC) shows historical demographic stability in V. cardui, and high effective population size estimates of 2-20 million individuals 10,000 years ago. The study reveals that the high risks associated with migration and local environmental fluctuations do not seem to decrease overall genetic diversity and demographic stability in migratory Lepidoptera. We propose a "compensatory" demographic model for migratory r-strategist organisms in which local bottlenecks are counterbalanced by reproductive success elsewhere within their typically large distributional ranges. Our findings highlight that the boundaries of populations are substantially different for sedentary and migratory insects, and that, in the latter, local and even regional field monitoring results may not reflect whole population dynamics. Genomic diversity patterns may elucidate key aspects of an insect's migratory nature and population dynamics at large spatiotemporal scales.

Matched MeSH terms: Population Density
Global status and conservation potential of reef sharks

MacNeil MA, Chapman DD, Heupel M, Simpfendorfer CA, Heithaus M, Meekan M, et al.

Nature, 2020 07;583(7818):801-806.
PMID: 32699418 DOI: 10.1038/s41586-020-2519-y

Decades of overexploitation have devastated shark populations, leaving considerable doubt as to their ecological status1,2. Yet much of what is known about sharks has been inferred from catch records in industrial fisheries, whereas far less information is available about sharks that live in coastal habitats3. Here we address this knowledge gap using data from more than 15,000 standardized baited remote underwater video stations that were deployed on 371 reefs in 58 nations to estimate the conservation status of reef sharks globally. Our results reveal the profound impact that fishing has had on reef shark populations: we observed no sharks on almost 20% of the surveyed reefs. Reef sharks were almost completely absent from reefs in several nations, and shark depletion was strongly related to socio-economic conditions such as the size and proximity of the nearest market, poor governance and the density of the human population. However, opportunities for the conservation of reef sharks remain: shark sanctuaries, closed areas, catch limits and an absence of gillnets and longlines were associated with a substantially higher relative abundance of reef sharks. These results reveal several policy pathways for the restoration and management of reef shark populations, from direct top-down management of fishing to indirect improvement of governance conditions. Reef shark populations will only have a high chance of recovery by engaging key socio-economic aspects of tropical fisheries.

Matched MeSH terms: Population Density
Fulltext Sumatran tiger survival threatened by deforestation despite increasing densities in parks

Luskin MS, Albert WR, Tobler MW

Nat Commun, 2017 12 05;8(1):1783.
PMID: 29208916 DOI: 10.1038/s41467-017-01656-4

The continuing development of improved capture-recapture (CR) modeling techniques used to study apex predators has also limited robust temporal and cross-site analyses due to different methods employed. We develop an approach to standardize older non-spatial CR and newer spatial CR density estimates and examine trends for critically endangered Sumatran tigers (Panthera tigris sumatrae) using a meta-regression of 17 existing densities and new estimates from our own fieldwork. We find that tiger densities were 47% higher in primary versus degraded forests and, unexpectedly, increased 4.9% per yr from 1996 to 2014, likely indicating a recovery from earlier poaching. However, while tiger numbers may have temporarily risen, the total potential island-wide population declined by 16.6% from 2000 to 2012 due to forest loss and degradation and subpopulations are significantly more fragmented. Thus, despite increasing densities in smaller parks, we conclude that there are only two robust populations left with >30 breeding females, indicating Sumatran tigers still face a high risk of extinction unless deforestation can be controlled.

Matched MeSH terms: Population Density
Fulltext Genomic insights into the conservation status of the world's last remaining Sumatran rhinoceros populations

von Seth J, Dussex N, Díez-Del-Molino D, van der Valk T, Kutschera VE, Kierczak M, et al.

Nat Commun, 2021 Apr 26;12(1):2393.
PMID: 33896938 DOI: 10.1038/s41467-021-22386-8

Small populations are often exposed to high inbreeding and mutational load that can increase the risk of extinction. The Sumatran rhinoceros was widespread in Southeast Asia, but is now restricted to small and isolated populations on Sumatra and Borneo, and most likely extinct on the Malay Peninsula. Here, we analyse 5 historical and 16 modern genomes from these populations to investigate the genomic consequences of the recent decline, such as increased inbreeding and mutational load. We find that the Malay Peninsula population experienced increased inbreeding shortly before extirpation, which possibly was accompanied by purging. The populations on Sumatra and Borneo instead show low inbreeding, but high mutational load. The currently small population sizes may thus in the near future lead to inbreeding depression. Moreover, we find little evidence for differences in local adaptation among populations, suggesting that future inbreeding depression could potentially be mitigated by assisted gene flow among populations.

Matched MeSH terms: Population Density
Fulltext Cellular function of satellite cells does not play a role in muscle weakness of adult Ts1Cje mice

Lim, Chai Ling, Usman Bala, Leong, Melody Pui-Yee, Johnson Stanslas, Rajesh Ramasamy, Ling, King-Hwa, et al.

Neuroscience Research Notes, 2018;1(1):3-10.
MyJurnal

Down syndrome (DS) is a genetic condition resulting from triplication of human chromosome (HSA)21. Besides intellectual disability, DS is frequently associated with hypotonia. Satellite cells are the resident cells that provides robust and remarkable regenerative capacity to the skeletal muscles, and its population size has been reported to be disease-associated. However, little is known about the population size of satellite cells in DS and the association of its intrinsic cellular functionality and hypotonia seen in DS. Here, we studied the Ts1Cje mouse, a DS murine model displays the muscle weakness characteristic. Satellite cell populations were immunostained with Pax7 and myonuclei numbers in the Ts1Cje extensor digitorum longus muscle were assessed. Their cellular function was further determined via in vitro assay in high-serum conditioned medium. Subsequently, the in vitro self-renewal, proliferative, and differentiation activities of these myogenic precursor cells were assessed after 24, 48, and 72h using Pax7, MyoD, and Ki67 immunomarkers. Our results showed that the population and functionality of Ts1Cje satellite cell did not differ significantly when compared to the wildtype cells isolated from disomic littermates. In conclusion, our findings indicated that intrinsic cellular functionality of the satellite cells, do not contribute to muscle weakness in Ts1Cje mouse.

Matched MeSH terms: Population Density
Aerial surveys give new estimates for orangutans in Sabah, Malaysia

Ancrenaz M, Gimenez O, Ambu L, Ancrenaz K, Andau P, Goossens B, et al.

PLoS Biol, 2005 Jan;3(1):e3.
PMID: 15630475

Great apes are threatened with extinction, but precise information about the distribution and size of most populations is currently lacking. We conducted orangutan nest counts in the Malaysian state of Sabah (North Borneo), using a combination of ground and helicopter surveys, and provided a way to estimate the current distribution and size of the populations living throughout the entire state. We show that the number of nests detected during aerial surveys is directly related to the estimated true animal density and that a helicopter is an efficient tool to provide robust estimates of orangutan numbers. Our results reveal that with a total estimated population size of about 11,000 individuals, Sabah is one of the main strongholds for orangutans in North Borneo. More than 60% of orangutans living in the state occur outside protected areas, in production forests that have been through several rounds of logging extraction and are still exploited for timber. The role of exploited forests clearly merits further investigation for orangutan conservation in Sabah.

Matched MeSH terms: Population Density
Fulltext Seasonal and Spatial Dynamics of the Primary Vector of Plasmodium knowlesi within a Major Transmission Focus in Sabah, Malaysia

Wong ML, Chua TH, Leong CS, Khaw LT, Fornace K, Wan-Sulaiman WY, et al.

PLoS Negl Trop Dis, 2015;9(10):e0004135.
PMID: 26448052 DOI: 10.1371/journal.pntd.0004135

BACKGROUND: The simian malaria parasite Plasmodium knowlesi is emerging as a public health problem in Southeast Asia, particularly in Malaysian Borneo where it now accounts for the greatest burden of malaria cases and deaths. Control is hindered by limited understanding of the ecology of potential vector species.
METHODOLOGY/PRINCIPAL FINDINGS: We conducted a one year longitudinal study of P. knowlesi vectors in three sites within an endemic area of Sabah, Malaysia. All mosquitoes were captured using human landing catch. Anopheles mosquitoes were dissected to determine, oocyst, sporozoites and parous rate. Anopheles balabacensis is confirmed as the primary vector of. P. knowlesi (using nested PCR) in Sabah for the first time. Vector densities were significantly higher and more seasonally variable in the village than forest or small scale farming site. However An. balabacensis survival and P. knowlesi infection rates were highest in forest and small scale farm sites. Anopheles balabacensis mostly bites humans outdoors in the early evening between 1800 to 2000 hrs.
CONCLUSIONS/SIGNIFICANCE: This study indicates transmission is unlikely to be prevented by bednets. This combined with its high vectorial capacity poses a threat to malaria elimination programmes within the region.

Matched MeSH terms: Population Density
Fulltext Bacterial Larvicide, Bacillus thuringiensis israelensis Strain AM 65-52 Water Dispersible Granule Formulation Impacts Both Dengue Vector, Aedes aegypti (L.) Population Density and Disease Transmission in Cambodia

Setha T, Chantha N, Benjamin S, Socheat D

PLoS Negl Trop Dis, 2016 09;10(9):e0004973.
PMID: 27627758 DOI: 10.1371/journal.pntd.0004973

A multi-phased study was conducted in Cambodia from 2005-2011 to measure the impact of larviciding with the bacterial larvicide, Bacillus thuringiensis israelensis (Bti), a water dispersible granule (WG) formulation on the vector, Aedes aegypti (L.) and the epidemiology. In our studies, all in-use containers were treated at 8 g/1000 L, including smaller containers and animal feeders which were found to contribute 23% of Ae aegypti pupae. The treated waters were subjected to routine water exchange activities. Pupal production was suppressed by an average 91% for 8 weeks. Pupal numbers continued to remain significantly lower than the untreated commune (UTC) for 13 weeks post treatment in the peak dengue vector season (p<0.05). Suppression of pupal production was supported by very low adult numbers in the treated commune. An average 70% of the household harbored 0-5 Ae aegypti mosquitoes per home for 8 weeks post treatment, but in the same period of time >50% of the household in the UTC harbored ≥11 mosquitoes per home. The adult population continued to remain at significantly much lower numbers in the Bti treated commune than in the UTC for 10-12 weeks post treatment (p<0.05). In 2011, a pilot operational program was evaluated in Kandal Province, a temephos resistant site. It was concluded that 2 cycles of Bti treatment in the 6 months monsoon season with complete coverage of the target districts achieved an overall dengue case reduction of 48% in the 6 treated districts compared to the previous year, 2010. Five untreated districts in the same province had an overwhelming increase of 352% of dengue cases during the same period of time. The larvicide efficacy, treatment of all in-use containers at the start of the monsoon season, together with treatment coverage of entire districts interrupted disease transmission in the temephos resistant province.

Matched MeSH terms: Population Density
The ground beetle fauna (Coleoptera: Carabidae) of Kenyir water catchment, Terengganu, Peninsular Malaysia

Abdullah F, Sina I, Fauzee F

Pak J Biol Sci, 2008 Nov 01;11(21):2478-83.
PMID: 19205267

An assemblage of beetle specimens from family Carabidae (ground beetles) was carried out at Kenyir water catchment as an indicator to measure disturbance. The samplings were conducted from 30th July to 1st August 2007 at limestone forest of Teluk Bewah and the dipterocarp forest of Sungai Cicir. 28 individuals from 13 species were collected from Teluk Bewah whereas 54 individuals from ten species was sampled from Sungai Cicir. The carabids were more specious (Simpson Diversity index: 0.97) and more abundant (Margalef index: 5.35) at Teluk Bewah compared to Sungai Cicir (Simpson Diversity index, 0.72: Margalefindex, 2.22). Light trapping was most efficient assembling 97.56% of ground beetles compared to Malaise trap, pitfall and net sweeping. This is the first record of beetle assemblage at Kenyir water catchment, Malaysia. New records for Kenyir, Terengganu, Malaysia are Abacetus sp. 1, Abacetus sp. 2, Acupalpus rectifrotis, Aephnidius adelioides, Dischissus notulatus, Dolichoctis sp., Dolichoctis sp. 2, Dolichoctis straitus, Ophinoea bimaculata, Perigona sp., Pheropsophus piciccollis, Pheropsophus occipitalis, Stenolophus quinquepustulatus, Stenolophus smaragdulus, Stenolophus sp., Tachys coracinus, Casnoidea sp., Orthogonius sp. Seven species coded as Cara C, Cara J, Cara M, Cara N, Cara O, Cara R and Cara S were unidentified and are probably new species to be described in another report. There is moderately high diversity (Simpson Diversity index: 0.846) of Carabidae indicating that ecotourism does not affect diversity of ground beetle at Kenyir Lake.

Matched MeSH terms: Population Density
Population study of Spodoptera exigua (Lepidoptera: Noctuidae) larva and its affecting factors in Sekinchan, Selangor

Azidah AA

Pak J Biol Sci, 2007 Jul 01;10(13):2152-8.
PMID: 19070174

The aim of this study is to determine the Spodoptera exigua larva population in the field and factor affecting their density. Population study of S. exigua larva and its affecting factors was carried out in Sekinchan, Selangor during 2003-2004. The larval density was found fluctuating during the study, where the highest number of larvae was an averaged of 18.17 per m2, while the lowest number was an averaged of 1.5 per m2. The mean number of larvae per plant also varies from 1.83 to 5.42. It was found that the larval density was influenced by the age and availability of the host plant. A total of 1881 larvae were collected, where 18.29 and 20.31% were successfully becoming female and male moths, respectively; 20.63% was being parasitized, where 7.07, 11.43, 0.11 and 2.02% were being parasitized by Microplitis manilae, Chelonus sp., Temelucha sp. and Peribaea orbata, respectively. Besides that, other biotic factors such as fungal or bacterial infection also cause death to the S. exigua larva, where a total of 1.91 and 10.89% were infected by them, respectively. Whilst 16.64% of the collected larvae were dead due to pesticide and 7.44% were not known cause of the death. Besides that, 3.89% of the S. exigua died during pupal stage or emergence. Further, climatic factor was found not influencing the larva populations. There were no correlation between the number of larva collected with the means of temperature, relative humidity and rainfall.

Matched MeSH terms: Population Density
Preliminary Study on Invasive Fish Species Diffusion in Selected Malaysian Freshwater Ecosystems

Ahmad AK, Nur-Hazwani MNR, Aisyah Syed Omar S, Aweng ER, Taweel A

Pak J Biol Sci, 2020 Jan;23(11):1374-1379.
PMID: 33274864 DOI: 10.3923/pjbs.2020.1374.1379

BACKGROUND AND OBJECTIVE: Malaysia reported experiencing serious invasive species intrusion in various rivers and threatening some local species to distinct. A study was undertaken to estimate and compare their composition and species richness in two pristine and two disturbed freshwater ecosystems.
MATERIALS AND METHODS: Invasive and local species growth pattern was also estimated using length-weight analysis. Sampling was conducted using cast net and electric shock in each river twice in 12 months. Fish collected were identified, photo captured and measured for their weight and length. The growth pattern was also estimated using length-weight analysis.
RESULTS: A total of 188 fishes were caught, comprises of 8 families and 15 species (ten local species with 119 individuals and five alien species with 69 individuals). Sistomus binotatus was the most dominant local species, whereas Tilapia nilotica was the most dominant alien species. There is no significant difference in composition between local and invasive species occur indicates the raise of alien species in those ecosystems even local species still dominated. The growth pattern for Sistomus binotatus and Clarias batrachus is isometric in the pristine ecosystem but negative isometric in disturbed rivers. Contrary, Tilapia nilotica has isometric for both ecosystems.
CONCLUSION: This study concluded the capability and potential of colonization of alien species in stress ecosystem especially Tilapia nilotica. Thus, there is potential colonization of alien in Malaysia freshwater systems and a threat to local species due to food competition, site preferences and survival ability.

Matched MeSH terms: Population Density
Flashing light as growth stimulant in cultivation of green microalgae, Chlorella sp. utilizing airlift photobioreactor

Fathurrahman L, Hajar AH, Sakinah DW, Nurhazwani Z, Ahmad J

Pak J Biol Sci, 2013 Nov 15;16(22):1517-23.
PMID: 24511694

One of the main limitations of productivity in photobioreactor is the inefficient conversion of the available light into biomass. Photoautotrophic cells such as microalgae only absorb a small fraction of supplied illumination due to limitation of its photosystem's (PS) absorbing rate. However, phenomenon of Flashing Light Effect (FLE) allows microalgae to utilize strong light exceptionally through intermittent exposure. Exposure of strong light at correct frequency of light and dark photoperiod would allow two pigment-protein complexes, PSI and PSII to be at the equilibrium mid-point potential to allow efficient light conversion. Narrow range of optimum frequency is crucial since overexposure to strong light would injured photosynthetic apparatus whereas longer dark period would contributed to loss of biomass due to triacylglycerol metabolism. The behaviour of microalgae towards various illumination conditions of FLE was determined at batch Photobioreactor (PBR) by varying the aeration flow rate: 16.94, 33.14 and 49.28 mL sec(-1) which yield, respectively the light exposure time of 3.99, 1.71 and 1.1 seconds per cycle. Maximum cell density in FLE-PBR was significantly higher at the exponential phase as compared to the continuously illuminated culture (p = 5.62 x 10(-5), a = 0.05) under the flow rate of 25.07 mL sec(-1). Maximum cell density yield of FLE-PBR and continuously illuminated PBR was, respectively 3.1125 x 10(7) and 2.947 x 10(7) cells mL(-1). Utilization of FLE as an innovative solution to increase the efficiency of microalgae to convert light into chemical energy would revolutionize the microalgae culture, reduce the time for cultivation and produce higher maximum biomass density.

Matched MeSH terms: Population Density
Fulltext Phylogenetics and population genetics of Plotosus canius (Siluriformes: Plotosidae) from Malaysian coastal waters

Khalili Samani N, Esa Y, Amin SM, Fatin Mohd Ikhsan N

PeerJ, 2016;4:e1930.
PMID: 27231645 DOI: 10.7717/peerj.1930

Plotosus canius (Hamilton, 1822) is a significant marine species in Malaysia from nutritional and commercial perspectives. Despite numerous fundamental research on biological characteristics of P. canius, there are various concerns on the level of population differentiation, genomic structure, and the level of genetic variability among their populations due to deficiency of genetic-based studies. Deficiency on basic contexts such as stock identification, phylogenetic relationship and population genetic structure would negatively impact their sustainable conservation. Hence, this study was conducted to characterize the genetic structure of P. canius for the first time through the application of mitochondrial Cytochrome Oxidase I (COI) gene, cross amplification of Tandanus tandanus microsatellites, and a total of 117 collected specimens across five selected populations of Malaysia. The experimental results of the mitochondrial analysis revealed that the haplotype diversity and nucleotide diversity varied from 0.395-0.771 and 0.033-0.65 respectively. Moreover, the statistical analysis of microsatellites addressed a considerable heterozygote insufficiency in all populations, with average observed heterozygosity (Ho ) value of 0.2168, which was lower than the standard heterozygosity in marine populations (Ho = 0.79). This alongside the high Fis values estimation, high pairwise differentiation among populations and low within population variations are supposed to be associated with small sample size, and inbreeding system. Besides, the significant finding of this study was the sharing of common haplotype KR086940, which reflects a historical genetic connectivity between Peninsular Malaysia and Borneo populations due to the geological history of Southeast Asia during Pleistocene era. Demographic analyses showed that all populations were in an equilibrium state with no significant evidence of population expansion. To put it briefly, the current study has managed to provide an initial genomic database toward understanding of the genetic characterization, phylogenetic, molecular diversification and population structure in P. canius, and should be necessary highlighted for appropriate management and conservation of species. Further studies must be carried out involving more geographical and sampling sites, larger population size per site, and utilization of species specific microsatellites loci.

Matched MeSH terms: Population Density

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