Displaying publications 181 - 200 of 243 in total

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  1. Fulltext Role of oil palm breeding in wealth creation and quality of life
    Ahmad Kushairi
    Buletin Persatuan Genetik Malaysia, 2010;16(1):6-9.
    MyJurnal
    Quality of planting materials determines future successes of plantations and subsequent endeavours in the life cycle. Oil palm (Elaeis guineensis) breeding triggered an industry in Malaysia through “Plant Introduction” with the establishment of the first oil palm plantation. At the wake of the oil palm industry, plantations utilised the dura planting material. The hallmark discovery of the single gene inheritance for shell thickness led to the prolific dura x pisifera (DxP) derived tenera planting material. Subsequent parental inbred lines developed in recurrent selections, crossed and progeny tested exploiting heterosis had boosted yields. Further improvements were foresighted and executed in the widening of the genetic pool and collections of germplasm in centres of origin/diversity in Africa and Latin America. Field Genebank of the Malaysian Palm Oil Board (MPOB) forms the world’s largest ex situ oil palm conservation programme. This programme enabled the developments of elite breeding populations harbouring specialty oils and products. Meanwhile, opening of large oil palm areas by the Federal Land Development Authority (Felda) set the momentum in rapid expansion of the industry. Felda is an exemplary in wealth creation and quality of life (QOL). Resettlements of landless farmers into Felda schemes, employing modern farming, mainly in oil palm has helped eradicate poverty and uplifting QOL among settlers, employees and their families. Impacts of the success in wealth creation and its distribution leading to better QOL, rooted from breeding through the supply of quality planting materials. Phenotypic expressions of the planting materials were realised through genotypic and environment interactions; the former through breeding, the latter through agronomic practices. Efforts in oil palm breeding helped paved the way to a mammoth industry, contributing to the nation economic growths, impacting livelihood of the people. Further progress in yield is expected from clones, where breeding has a role in the supply of quality ortets. Genetic potential of planting materials can be further exploited through interdisciplinary approach in breeding, biotechnology and genomics. With continuing wealth creation, the oil palm saga continues. Once wealth is created, QOL will follow.
    Matched MeSH terms: Breeding
  2. Fulltext Effects of Genotype by Environment Interaction on Genetic Gain and Genetic Parameter Estimates in Red Tilapia (Oreochromis spp.)
    Nguyen NH, Hamzah A, Thoa NP
    Front Genet, 2017;8:82.
    PMID: 28659970 DOI: 10.3389/fgene.2017.00082
    The extent to which genetic gain achieved from selection programs under strictly controlled environments in the nucleus that can be expressed in commercial production systems is not well-documented in aquaculture species. The main aim of this paper was to assess the effects of genotype by environment interaction on genetic response and genetic parameters for four body traits (harvest weight, standard length, body depth, body width) and survival in Red tilapia (Oreochromis spp.). The growth and survival data were recorded on 19,916 individual fish from a pedigreed population undergoing three generations of selection for increased harvest weight in earthen ponds from 2010 to 2012 at the Aquaculture Extension Center, Department of Fisheries, Jitra in Kedah, Malaysia. The pedigree comprised a total of 224 sires and 262 dams, tracing back to the base population in 2009. A multivariate animal model was used to measure genetic response and estimate variance and covariance components. When the homologous body traits in freshwater pond and cage were treated as genetically distinct traits, the genetic correlations between the two environments were high (0.85-0.90) for harvest weight and square root of harvest weight but the estimates were of lower magnitudes for length, width and depth (0.63-0.79). The heritabilities estimated for the five traits studied differed between pond (0.02 to 0.22) and cage (0.07 to 0.68). The common full-sib effects were large, ranging from 0.23 to 0.59 in pond and 0.11 to 0.31 in cage across all traits. The direct and correlated responses for four body traits were generally greater in pond than in cage environments (0.011-1.561 vs. -0.033-0.567 genetic standard deviation units, respectively). Selection for increased harvest body weight resulted in positive genetic changes in survival rate in both pond and cage culture. In conclusion, the reduced selection response and the magnitude of the genetic parameter estimates in the production environment (i.e., cage) relative to those achieved in the nucleus (pond) were a result of the genotype by environment interaction and this effect should be taken into consideration in the future breeding program for Red tilapia.
    Matched MeSH terms: Breeding
  3. Fulltext Genomic Selection in Commercial Perennial Crops: Applicability and Improvement in Oil Palm (Elaeis guineensis Jacq.)
    Kwong QB, Ong AL, Teh CK, Chew FT, Tammi M, Mayes S, et al.
    Sci Rep, 2017 06 06;7(1):2872.
    PMID: 28588233 DOI: 10.1038/s41598-017-02602-6
    Genomic selection (GS) uses genome-wide markers to select individuals with the desired overall combination of breeding traits. A total of 1,218 individuals from a commercial population of Ulu Remis x AVROS (UR x AVROS) were genotyped using the OP200K array. The traits of interest included: shell-to-fruit ratio (S/F, %), mesocarp-to-fruit ratio (M/F, %), kernel-to-fruit ratio (K/F, %), fruit per bunch (F/B, %), oil per bunch (O/B, %) and oil per palm (O/P, kg/palm/year). Genomic heritabilities of these traits were estimated to be in the range of 0.40 to 0.80. GS methods assessed were RR-BLUP, Bayes A (BA), Cπ (BC), Lasso (BL) and Ridge Regression (BRR). All methods resulted in almost equal prediction accuracy. The accuracy achieved ranged from 0.40 to 0.70, correlating with the heritability of traits. By selecting the most important markers, RR-BLUP B has the potential to outperform other methods. The marker density for certain traits can be further reduced based on the linkage disequilibrium (LD). Together with in silico breeding, GS is now being used in oil palm breeding programs to hasten parental palm selection.
    Matched MeSH terms: Plant Breeding
  4. Genetic variation and correlated changes in reproductive performance of a red tilapia line selected for improved growth over three generations
    Thoa NP, Hamzah A, Nguyen NH
    Anim. Reprod. Sci., 2017 Sep;184:94-101.
    PMID: 28709735 DOI: 10.1016/j.anireprosci.2017.07.003
    The present study examines genetic variation and correlated changes in reproductive performance traits in a red tilapia (Oreochromis spp.) population selected over three generations for improved growth. A total of 328 breeding females (offspring of 111 sires and 118 dams) had measurements of body weight prior to spawning (WBS), number of fry at hatching (NFH), total fry weight (TFW) and number of dead fry (NDF) or mortality of fry including unhatched eggs at hatching (MFH). Restricted maximum likelihood (REML) analysis in a multi-trait model showed that there are heritable genetic components for all traits studied. The heritability for WBS was very high (0.80). The estimates for traits related to fecundity (NFH, TFW) and survival (NDF) were low and they were associated with high standard errors. Genetic correlations of WBS with other reproductive performance traits (NFH, TFW and NDF) were generally positive. However, NFH was negatively correlated genetically with TFW. As expected, body measurements during growth stage exhibited strong positive genetic correlations with WBS. The genetic correlations between body traits and reproductive performance (NFH, TFW, NDF) were not significant. Correlated responses in reproductive traits were measured as changes in least squares means between generations or spawning years. Except for WBS that increased with the selection programs, the phenotypic changes in other reproductive traits observed were not statistically significant (P>0.05). It is concluded that the selection program for red tilapia has resulted in very little changes in reproductive performance of the animals after three generations. However, periodic monitoring of genetic changes in fecundity and fitness related traits such as NDF or MFH should be made in selective breeding programs for red tilapia.
    Matched MeSH terms: Breeding
  5. Fulltext Breeding for robustness: investigating the genotype-by-environment interaction and micro-environmental sensitivity of Genetically Improved Farmed Tilapia (Oreochromis niloticus)
    Agha S, Mekkawy W, Ibanez-Escriche N, Lind CE, Kumar J, Mandal A, et al.
    Anim. Genet., 2018 Oct;49(5):421-427.
    PMID: 30058152 DOI: 10.1111/age.12680
    Robustness has become a highly desirable breeding goal in the globalized agricultural market. Both genotype-by-environment interaction (G × E) and micro-environmental sensitivity are important robustness components of aquaculture production, in which breeding stock is often disseminated to different environments. The objectives of this study were (i) to quantify the degree of G × E by assessing the growth performance of Genetically Improved Farmed Tilapia (GIFT) across three countries (Malaysia, India and China) and (ii) to quantify the genetic heterogeneity of environmental variance for body weight at harvest (BW) in GIFT as a measure of micro-environmental sensitivity. Selection for BW was carried out for 13 generations in Malaysia. Subsets of 60 full-sib families from Malaysia were sent to China and India after five and nine generations respectively. First, a multi-trait animal model was used to analyse the BW in different countries as different traits. The results indicate a strong G × E. Second, a genetically structured environmental variance model, implemented using Bayesian inference, was used to analyse micro-environmental sensitivity of BW in each country. The analysis revealed the presence of genetic heterogeneity of both BW and its environmental variance in all environments. The presence of genetic variation in residual variance of BW implies that the residual variance can be modified by selection. Incorporating both G × E and micro-environmental sensitivity information may help in selecting robust genotypes with high performance across environments and resilience to environmental fluctuations.
    Matched MeSH terms: Breeding
  6. Genetic analysis and identification of SSR markers associated with rice blast disease in a BC2F1 backcross population
    Hasan N, Rafii MY, Abdul Rahim H, Nusaibah SA, Mazlan N, Abdullah S
    Genet. Mol. Res., 2017 Jan 23;16(1).
    PMID: 28128411 DOI: 10.4238/gmr16019280
    Rice (Oryza sativa L.) blast disease is one of the most destructive rice diseases in the world. The fungal pathogen, Magnaporthe oryzae, is the causal agent of rice blast disease. Development of resistant cultivars is the most preferred method to achieve sustainable rice production. However, the effectiveness of resistant cultivars is hindered by the genetic plasticity of the pathogen genome. Therefore, information on genetic resistance and virulence stability are vital to increase our understanding of the molecular basis of blast disease resistance. The present study set out to elucidate the resistance pattern and identify potential simple sequence repeat markers linked with rice blast disease. A backcross population (BC2F1), derived from crossing MR264 and Pongsu Seribu 2 (PS2), was developed using marker-assisted backcross breeding. Twelve microsatellite markers carrying the blast resistance gene clearly demonstrated a polymorphic pattern between both parental lines. Among these, two markers, RM206 and RM5961, located on chromosome 11 exhibited the expected 1:1 testcross ratio in the BC2F1 population. The 195 BC2F1 plants inoculated against M. oryzae pathotype P7.2 showed a significantly different distribution in the backcrossed generation and followed Mendelian segregation based on a single-gene model. This indicates that blast resistance in PS2 is governed by a single dominant gene, which is linked to RM206 and RM5961 on chromosome 11. The findings presented in this study could be useful for future blast resistance studies in rice breeding programs.
    Matched MeSH terms: Breeding
  7. Winged bean (Psophocarpus tetragonolobus (L.) DC.) for food and nutritional security: synthesis of past research and future direction
    Tanzi AS, Eagleton GE, Ho WK, Wong QN, Mayes S, Massawe F
    Planta, 2019 Sep;250(3):911-931.
    PMID: 30911885 DOI: 10.1007/s00425-019-03141-2
    MAIN CONCLUSION: Winged bean is popularly known as "One Species Supermarket" for its nutrient-dense green pods, immature seeds, tubers, leaves, and mature seeds. This underutilised crop has potential beneficial traits related to its biological nitrogen-fixation to support low-input farming. Drawing from past knowledge, and based on current technologies, we propose a roadmap for research and development of winged bean for sustainable food systems. Reliance on a handful of "major" crops has led to decreased diversity in crop species, agricultural systems and human diets. To reverse this trend, we need to encourage the greater use of minor, "orphan", underutilised species. These could contribute to an increase in crop diversity within agricultural systems, to improve human diets, and to support more sustainable and resilient food production systems. Among these underutilised species, winged bean (Psophocarpus tetragonolobus) has long been proposed as a crop for expanded use particularly in the humid tropics. It is an herbaceous perennial legume of equatorial environments and has been identified as a rich source of protein, with most parts of the plant being edible when appropriately prepared. However, to date, limited progress in structured improvement programmes has restricted the expansion of winged bean beyond its traditional confines. In this paper, we discuss the reasons for this and recommend approaches for better use of its genetic resources and related Psophocarpus species in developing improved varieties. We review studies on the growth, phenology, nodulation and nitrogen-fixation activity, breeding programmes, and molecular analyses. We then discuss prospects for the crop based on the greater understanding that these studies have provided and considering modern plant-breeding technologies and approaches. We propose a more targeted and structured research approach to fulfil the potential of winged bean to contribute to food security.
    Matched MeSH terms: Plant Breeding
  8. Fulltext Combination of Plant Growth Regulators, Maltose, and Partial Desiccation Treatment Enhance Somatic Embryogenesis in Selected Malaysian Rice Cultivar
    Ming NGJ, Binte Mostafiz S, Johon NS, Abdullah Zulkifli NS, Wagiran A
    Plants (Basel), 2019 May 30;8(6).
    PMID: 31151227 DOI: 10.3390/plants8060144
    The development of efficient tissue culture protocol for somatic embryo would facilitate the genetic modification breeding program. The callus induction and regeneration were studied by using different parameters i.e., auxins, cytokinins, and desiccation treatment. Scanning electron microscopy and histological analysis were performed to identify the embryogenic callus for regeneration. The callus percentage results showed that MS (Murashige and Skoog) basal medium supplemented with 3 mg/L 2, 4-D and 30g/L maltose were the optimal callus induction medium for MR220 (80%) and MR220-CL2 (95%). The morphology of the embryogenic callus was confirmed by the SEM (Scanning Electron Microscopy) (presence of extracellular matrix surface network) and later by histological analysis. Finally, MS media supplemented with 0.5 mg/L NAA (Naphthalene Acetic Acid), 2 mg/L kin, and 1 mg/L BAP were selected as the optimum regeneration media treatment while callus desiccated for 48 h was proved to produce more plantlets in MR220 (60%) and MR220-CL2 (73.33%) compared to control treatment (without desiccation). The protocol presented here showed the necessity for the inclusion of partial desiccation as an important step in the tissue culture protocol of Malaysian indica rice genotypes in order to enhance their regeneration potential.
    Matched MeSH terms: Breeding
  9. Identification of drought tolerant maize genotypes and seedling based morpho-physiological selection indices for crop improvement
    Fahad Masoud Wattoo, Rashid Mehmood Rana, Sajid Fiaz, Syed Adeel Zafar, Mehmood Ali Noor, Shoaib ur Rehman, et al.
    Sains Malaysiana, 2018;47:295-302.
    Maize is an imperative grain crop used as a staple food in several countries around the world. Water deficiency is a serious
    problem limiting its growing area and production. Identification of drought tolerant maize germplasm is comparatively
    easy and sustainable approach to combat this issue. Present research was conducted to evaluate 50 maize genotypes
    for drought tolerance at early growth stage. Drought tolerance was assessed on the basis of several morphological
    and physiological parameters. Analysis of variance showed significant variation among the tested maize genotypes for
    recorded parameters. Principal component analysis revealed important morpho-physiological traits that were playing
    key role in drought tolerance. Correlation studies depicted significant positive correlation among the attributes such as
    fresh shoot length (FSL), fresh root length (FRL), dry shoot weight (DSW), dry root weight (DRW), relative water contents
    (RWC) and total dry matter (TDM) while a strongly negative correlation was observed among RWC and excised leaf
    water loss. Results concluded that the parameters fresh shoot weight, fresh root weight, FRL, DRW, TDM, cell membrane
    thermo stability (CMT) and RWC can be useful for rapid screening of maize germplasm for drought tolerance at early
    growth stages. Furthermore, the genotypes 6, 16, 18, 40, 45 and 50 can be used as a drought tolerant check in breeding
    programs. Moreover, biplot analysis along with other indices was proved to be a useful approach for rapid and cost
    efficient screening of large number of genotypes against drought stress condition.
    Matched MeSH terms: Breeding
  10. Fulltext The association between climatic factors and dengue fever: a study in Subang Jaya and Sepang, Selangor
    Nik Syaza Lina Nik Ruzman, Haliza Abdul Rahman
    Malaysian Journal of Public Health Medicine, 2017;17 Special(1):140-150.
    Dengue fever is one of the most dangerous vector-borne diseases. According to the World Health Organization (WHO), dengue fever is a mosquito-borne infection caused by virus serotype DEN-1, DEN-2, DEN-3 and DEN-4. In Malaysia, dengue fever cases are on the rise from 6,000 cases in 1995 to over 40,000 in 2010, and this number is still rising. In 2014, the increase of dengue fever cases was alarming. It was reported that up to the end of the year 2014, there were 108,698 notified cases, indicating an increment of 151% compared to the same period of time in 2013 with only 43,346 reported cases. Selangor was the highest contributor of dengue fever cases in 2014. The objective of this paper is to study the relationship between climatic factors namely temperature, rainfall and humidity to the prevalence of dengue fever in Subang Jaya and Sepang district, Selangor. Data on monthly average temperature, precipitation, relative humidity and dengue fever cases for each month in 2014 and 2013 were collected. Data collection was dealt with a few institutions such as Malaysian Meteorological Department, Subang Jaya and Sepang Municipal Council and health district offices. Data were analysed using SPSS (Statistical Package for the Social Sciences) Version 20. General linear model analysis was used to investigate the relationship between the climatic variables and dengue prevalence. Results and Discussion: Based on the general linear model, rainfall and humidity were found to have significant relationships to monthly dengue fever cases (p= <0.001, p= 0.002). Rainfall was identified as the most significant predictor because rainfall can provide more breeding places for Aedes mosquitoes. As for humidity, higher relative humidity had been associated with increased Aedes aegypti feeding activity, survival and egg development. Temperature was not significantly related to monthly dengue fever cases (p= 0.561) in this study. However, this could be due to the short period of study. Conclusion: Climatic factors play an important role in the prevalence of dengue fever. However, there are many other factors of dengue fever that should be considered such as urbanisation as well as community knowledge, attitude and practice.
    Matched MeSH terms: Breeding
  11. Fulltext Proline Homeostasis in Saccharomyces cerevisiae: How Does the Stress-Responsive Transcription Factor Msn2 Play a Role?
    Mat Nanyan NSB, Takagi H
    Front Genet, 2020;11:438.
    PMID: 32411186 DOI: 10.3389/fgene.2020.00438
    Overexpression of MSN2, which is the transcription factor gene in response to stress, is well-known to increase the tolerance of the yeast Saccharomyces cerevisiae cells to a wide variety of environmental stresses. Recent studies have found that the Msn2 is a feasible potential mediator of proline homeostasis in yeast. This result is based on the finding that overexpression of the MSN2 gene exacerbates the cytotoxicity of yeast to various amino acid analogs whose uptake is increased by the active amino acid permeases localized on the plasma membrane as a result of a dysfunctional deubiquitination process. Increased understanding of the cellular responses induced by the Msn2-mediated proline incorporation will provide better comprehension of how cells respond to and counteract to different kinds of stimuli and will also contribute to the breeding of industrial yeast strains with increased productivity.
    Matched MeSH terms: Breeding
  12. Fulltext Semen characteristics, extension, and cryopreservation of Rusa deer (Rusa timorensis)
    Fitri WN, Wahid H, Rosnina Y, Jesse FFA, Aimi-Sarah ZA, Mohd-Azmi ML, et al.
    Vet World, 2017 Jul;10(7):779-785.
    PMID: 28831222 DOI: 10.14202/vetworld.2017.779-785
    AIM: The objective of this research is to report parameters for breeding soundness evaluation, semen extension, and cryopreservation in Rusa timorensis.

    MATERIALS AND METHODS: Seven healthy stags were chosen for semen collection using an electroejaculator. The collections were performed twice in a breeding season between February and June 2016. Samples were collected between 2 and 3 weeks interval, collected twice for each animal. Semen was evaluated, extended, and cryopreserved using four different extenders; Andromed®, BioXcell®, Triladyl®, and a modified Tris-egg yolk combined with Eurycoma longifolia Jack.

    RESULTS: R. timorensis semen characteristics according to volume (ml), color, sperm concentration (106/ml), general motility (%), progressive motility (%), and % morphology of normal spermatozoa are 0.86±0.18 ml, thin milky to milky, 1194.2±346.1 106/ml, 82.9±2.8%, 76.1±4.8%, and 83.9±4.8%, respectively.

    CONCLUSION: Semen characteristics of R. timorensis collected by electroejaculation is good allowing for cryopreservation and future artificial insemination work. The most suitable extender for Rusa deer semen is Andromed®.

    Matched MeSH terms: Breeding
  13. Genetic diversity analysis in Malaysian giant prawns using expressed sequence tag microsatellite markers for stock improvement program
    Atin KH, Christianus A, Fatin N, Lutas AC, Shabanimofrad M, Subha B
    Genet. Mol. Res., 2017 Aug 17;16(3).
    PMID: 28829885 DOI: 10.4238/gmr16035685
    The Malaysian giant prawn is among the most commonly cultured species of the genus Macrobrachium. Stocks of giant prawns from four rivers in Peninsular Malaysia have been used for aquaculture over the past 25 years, which has led to repeated harvesting, restocking, and transplantation between rivers. Consequently, a stock improvement program is now important to avoid the depletion of wild stocks and the loss of genetic diversity. However, the success of such an improvement program depends on our knowledge of the genetic variation of these base populations. The aim of the current study was to estimate genetic variation and differentiation of these riverine sources using novel expressed sequence tag-microsatellite (EST-SSR) markers, which not only are informative on genetic diversity but also provide information on immune and metabolic traits. Our findings indicated that the tested stocks have inbreeding depression due to a significant deficiency in heterozygotes, and FIS was estimated as 0.15538 to 0.31938. An F-statistics analysis suggested that the stocks are composed of one large panmictic population. Among the four locations, stocks from Johor, in the southern region of the peninsular, showed higher allelic and genetic diversity than the other stocks. To overcome inbreeding problems, the Johor population could be used as a base population in a stock improvement program by crossing to the other populations. The study demonstrated that EST-SSR markers can be incorporated in future marker assisted breeding to aid the proper management of the stocks by breeders and stakeholders in Malaysia.
    Matched MeSH terms: Selective Breeding
  14. High density SNP and DArT-based genetic linkage maps of two closely related oil palm populations
    Gan ST, Wong WC, Wong CK, Soh AC, Kilian A, Low EL, et al.
    J Appl Genet, 2018 Feb;59(1):23-34.
    PMID: 29214520 DOI: 10.1007/s13353-017-0420-7
    Oil palm (Elaeis guineensis Jacq.) is an outbreeding perennial tree crop with long breeding cycles, typically 12 years. Molecular marker technologies can greatly improve the breeding efficiency of oil palm. This study reports the first use of the DArTseq platform to genotype two closely related self-pollinated oil palm populations, namely AA0768 and AA0769 with 48 and 58 progeny respectively. Genetic maps were constructed using the DArT and SNP markers generated in combination with anchor SSR markers. Both maps consisted of 16 major independent linkage groups (2n = 2× = 32) with 1399 and 1466 mapped markers for the AA0768 and AA0769 populations, respectively, including the morphological trait "shell-thickness" (Sh). The map lengths were 1873.7 and 1720.6 cM with an average marker density of 1.34 and 1.17 cM, respectively. The integrated map was 1803.1 cM long with 2066 mapped markers and average marker density of 0.87 cM. A total of 82% of the DArTseq marker sequence tags identified a single site in the published genome sequence, suggesting preferential targeting of gene-rich regions by DArTseq markers. Map integration of higher density focused around the Sh region identified closely linked markers to the Sh, with D.15322 marker 0.24 cM away from the morphological trait and 5071 bp from the transcriptional start of the published SHELL gene. Identification of the Sh marker demonstrates the robustness of using the DArTseq platform to generate high density genetic maps of oil palm with good genome coverage. Both genetic maps and integrated maps will be useful for quantitative trait loci analysis of important yield traits as well as potentially assisting the anchoring of genetic maps to genomic sequences.
    Matched MeSH terms: Plant Breeding
  15. Fulltext Dual Actions of Mammalian and Piscine Gonadotropin-Inhibitory Hormones, RFamide-Related Peptides and LPXRFamide Peptides, in the Hypothalamic-Pituitary-Gonadal Axis
    Ubuka T, Parhar I
    Front Endocrinol (Lausanne), 2017;8:377.
    PMID: 29375482 DOI: 10.3389/fendo.2017.00377
    Gonadotropin-inhibitory hormone (GnIH) is a hypothalamic neuropeptide that decreases gonadotropin synthesis and release by directly acting on the gonadotrope or by decreasing the activity of gonadotropin-releasing hormone (GnRH) neurons. GnIH is also called RFamide-related peptide in mammals or LPXRFamide peptide in fishes due to its characteristic C-terminal structure. The primary receptor for GnIH is GPR147 that inhibits cAMP production in target cells. Although most of the studies in mammals, birds, and fish have shown the inhibitory action of GnIH in the hypothalamic-pituitary-gonadal (HPG) axis, several in vivo studies in mammals and many in vivo and in vitro studies in fish have shown its stimulatory action. In mouse, although the firing rate of the majority of GnRH neurons is decreased, a small population of GnRH neurons is stimulated by GnIH. In hamsters, GnIH inhibits luteinizing hormone (LH) release in the breeding season when their endogenous LH level is high but stimulates LH release in non-breeding season when their LH level is basal. Besides different effects of GnIH on the HPG axis depending on the reproductive stages in fish, higher concentration or longer duration of GnIH administration can stimulate their HPG axis. These results suggest that GnIH action in the HPG axis is modulated by sex-steroid concentration, the action of neuroestrogen synthesized by the activity of aromatase stimulated by GnIH, estrogen membrane receptor, heteromerization and internalization of GnIH, GnRH, and estrogen membrane receptors. The inhibitory and stimulatory action of GnIH in the HPG axis may have a physiological role to maintain reproductive homeostasis according to developmental and reproductive stages.
    Matched MeSH terms: Breeding
  16. Differential preferences of oviposition by Aedes mosquitos in man-made containers under field conditions
    Chua KB, Chua IL, Chua IE, Chua KH
    Southeast Asian J Trop Med Public Health, 2004 Sep;35(3):599-607.
    PMID: 15689073
    A study was made of the oviposit behavior of gravid female Aedes mosquitos in man-made habitats under field conditions. The study showed that the gravid female Aedes mosquitos preferred containers with relatively easy access but not too open to external environmental influence. The dark surface of the containers served as the initial and long-range attractant to the breeding sites. Volatile chemicals generated by the decaying vegetation in the container may serve as a close-range attractant. Finally, the water quality and the quantity of 'food' derived from decaying vegetative matter in the water determined the amount of eggs deposited in each container. The study confirmed previous findings that each gravid female Aedes mosquito had the tendency to lay her eggs in more than one container. However, the results of the study suggests that under favorable conditions, each gravid female Aedes mosquito could be encouraged to lay all her eggs in a single breeding site.
    Matched MeSH terms: Breeding
  17. Fulltext The ecology of anopheline mosquitos in northwest coastal Malaysia: larval habitats and adult seasonal abundance
    Jaal Z, Macdonald WW
    Southeast Asian J Trop Med Public Health, 1993 Sep;24(3):522-9.
    PMID: 8160063
    Collections of anopheline mosquitos were made twice monthly for 13 months from a cow-baited trap in two villages, Kampung Permatang Rawa and Sungai Udang Kecil, on mainland coastal Penang, Malaysia. Each collection period was six hours from sunset. Unquantified larval collections were made regularly in each area. Although the villages were only about 50km apart, and each had extensive, irrigated rice-fields in its vicinity, the species abundance and the seasonal fluctuations differed significantly. In Kampung Permatang Rawa Anopheles sinensis and An. peditaeniatus were dominant in prevalence, whereas in Sungai Udang Kecil An. indefinitus and An. lesteri paraliae were most common and An. peditaeniatus was relatively rare. The rice growing schedules in the two areas differed, but there was a moderate correlation between the abundance of several species and the rice-growing pattern. There was no correlation at either site with rainfall.
    Matched MeSH terms: Breeding
  18. Fulltext The deadly ebola threat in the midst of an overwhelming dengue epidemic
    Besari AM, Md Noor SS, Lee YY
    Malays J Med Sci, 2014 Nov-Dec;21(6):9-13.
    PMID: 25897277 MyJurnal
    The recent death tolls and morbidities associated with two deadly viral haemorrhagic fevers (VHFs), i.e., Ebola and dengue, are simply shocking. By the end of August 2014, 65 672 people were afflicted with dengue fever (DF) in Malaysia, with 9505 from Kelantan, and there were 128 reported deaths. More astounding are the death tolls associated with Ebola: 3091 deaths from 6574 reported cases so far. It is not difficult to imagine the potential disaster if Ebola spreads beyond Africa. VHFs are characterised by an acute onset of fever, vascular disruption and a rapid progression to shock and death. The revised World Health Organization (WHO) 2012 classification (dengue with and without warning signs and severe dengue) is more clinically relevant and allows more streamlined admission. With good administrative support and public health and governmental efforts, the dengue epidemic in Malaysia is now more contained. However, there should be no laxity with the imminent lethal Ebola threat. Human-to-human transmission is an important mechanism for the spread of Ebola, and this calls for strict precautions regarding contact with any suspected cases. In contrast, the control and elimination of dengue would require successful control of the vectors and their breeding sites.
    Matched MeSH terms: Breeding
  19. Fulltext Improvement of Drought Tolerance in Rice (Oryza sativa L.): Genetics, Genomic Tools, and the WRKY Gene Family
    Sahebi M, Hanafi MM, Rafii MY, Mahmud TMM, Azizi P, Osman M, et al.
    Biomed Res Int, 2018;2018:3158474.
    PMID: 30175125 DOI: 10.1155/2018/3158474
    Drought tolerance is an important quantitative trait with multipart phenotypes that are often further complicated by plant phenology. Different types of environmental stresses, such as high irradiance, high temperatures, nutrient deficiencies, and toxicities, may challenge crops simultaneously; therefore, breeding for drought tolerance is very complicated. Interdisciplinary researchers have been attempting to dissect and comprehend the mechanisms of plant tolerance to drought stress using various methods; however, the limited success of molecular breeding and physiological approaches suggests that we rethink our strategies. Recent genetic techniques and genomics tools coupled with advances in breeding methodologies and precise phenotyping will likely reveal candidate genes and metabolic pathways underlying drought tolerance in crops. The WRKY transcription factors are involved in different biological processes in plant development. This zinc (Zn) finger protein family, particularly members that respond to and mediate stress responses, is exclusively found in plants. A total of 89 WRKY genes in japonica and 97 WRKY genes in O. nivara (OnWRKY) have been identified and mapped onto individual chromosomes. To increase the drought tolerance of rice (Oryza sativa L.), research programs should address the problem using a multidisciplinary strategy, including the interaction of plant phenology and multiple stresses, and the combination of drought tolerance traits with different genetic and genomics approaches, such as microarrays, quantitative trait loci (QTLs), WRKY gene family members with roles in drought tolerance, and transgenic crops. This review discusses the newest advances in plant physiology for the exact phenotyping of plant responses to drought to update methods of analysing drought tolerance in rice. Finally, based on the physiological/morphological and molecular mechanisms found in resistant parent lines, a strategy is suggested to select a particular environment and adapt suitable germplasm to that environment.
    Matched MeSH terms: Plant Breeding
  20. Fulltext Development of a New Molecular Marker for the Resistance to Tomato Yellow Leaf Curl Virus
    Nevame AYM, Xia L, Nchongboh CG, Hasan MM, Alam MA, Yongbo L, et al.
    Biomed Res Int, 2018;2018:8120281.
    PMID: 30105248 DOI: 10.1155/2018/8120281
    Tomato yellow leaf curl virus (TYLCV) responsible for tomato yellow leaf curl disease (TYLCD) causes a substantial decrease in tomato (Solanum lycopersicum L.) yield worldwide. The use of resistant variety as a sustainable management strategy has been advocated. Tremendous progress has been made in genetically characterizing the resistance genes (R gene) in tomato. Breeding tomato for TYLCV resistance has been based mostly on Ty-3 as a race-specific resistance gene by introgression originating from wild tomato species relatives. Improvement or development of a cultivar is achievable through the use of marker-assisted selection (MAS). Therefore, precise and easy use of gene-targeted markers would be of significant importance for selection in breeding programs. The present study was undertaken to develop a new marker based on Ty-3 gene sequence that can be used for MAS in TYLCV resistant tomato breeding program. The new developed marker was named ACY. The reliability and accuracy of ACY were evaluated against those of Ty-3 linked marker P6-25 through screening of commercial resistant and susceptible tomato hybrids, and genetic segregation using F2 population derived from a commercial resistant hybrid AG208. With the use of bioinformatics and DNA sequencing analysis tools, deletion of 10 nucleotides was observed in Ty-3 gene sequence for susceptible tomato variety. ACY is a co-dominant indel-based marker that produced clear and strong polymorphic band patterns for resistant plant distinguishing it from its susceptible counterpart. The obtained result correlates with 3:1 segregation ratio of single resistant dominant gene inheritance, which depicted ACY as gene-tag functional marker. This marker is currently in use for screening 968 hybrids varieties and one thousand breeding lines of tomato varieties stocked in Jiangsu Green Port Modern Agriculture Development Company (Green Port). So far, ACY has been used to identify 56 hybrids and 51 breeding lines. These newly detected breeding lines were regarded as potential source of resistance for tomato breeding. This work exploited the sequence of Ty-3 and subsequently contributed to the development of molecular marker ACY to aid phenotypic selection. We thus recommend this marker to breeders, which is suitable for marker-assisted selection in tomato.
    Matched MeSH terms: Plant Breeding
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