Locations In Asia Research Articles

Genomics, Molecular Epidemiology and Diagnostics of Infectious hypodermal and hematopoietic necrosis virus

Infectious hypodermal and hematopoietic necrosis virus (IHHNV) is one of the major viral pathogens of penaeid shrimps worldwide, which has resulted in severe mortalities of up to 90% in cultured Penaeus (Litopenaeus) stylirostris from Hawaii and hence designated Penaeus stylirostris densovirus (PstDNV). IHHNV is distributed in shrimp culture facilities worldwide. It causes large economic loss to the shrimp farming industry. Our knowledge about the natural reservoirs of IHHNV is still scarce. Recent studies suggest that there is sufficient sequence variation among the isolates from different locations in Asia, suggesting multiple geographical strains of the virus. Four complete genomes and several partial sequences of the virus are available in the GenBank. Complete genome information would be useful for assessing the specificity of diagnostics for viruses from different geographical areas. Comparisons of complete genome sequences will help us gain insights into point mutations that can affect virulence of the virus. In addition, because of unavailability of shrimp cell lines for culturing IHHNV in vitro, quantification of virus is difficult. The recent progress in research regarding clinical signs, geographical distribution, complete genome sequence and genetic variation, transmission has made it possible to obtain information on IHHNV. A comprehensive understanding of IHHNV infection process, pathogenesis, structural proteins and replication is essential for developing prevention measures. To date, no effective prophylactic measure for IHHNV infection is available for shrimp to reduce its impact. This review provides an overview of key issues regarding IHHNV infection and disease in commercially important shrimp species.

Autosomal genetic diversity in non‐breed horses from eastern Eurasia provides insights into historical population movements

Many events in the history of eastern Eurasia, including the process of domestication itself, the initial spread of domestic horses and subsequent movements, are believed to have affected the genetic structure of domestic horse populations in this area. We investigated levels of within- and between-population genetic diversity in 'non-breed horses' (working horses sampled in remote areas) from 17 locations in Asia and parts of Eastern Europe, using 26 autosomal microsatellite loci. Non-breed horses have not been subject to the same intensity of artificial selection and closed breeding as have most breed animals and are thus expected to better reflect the population history of domestic horses. Despite geographic distances of between 300 and 7000 km between sampling locations, pairwise F (ST) was very low (range: <0.001 to -0.033), suggesting historically high levels of gene flow. Our analyses of non-breed horses revealed a pattern of isolation by distance and a significant decline in genetic diversity (expected heterozygosity and allelic richness) from east to west, consistent with a westward expansion of horses out of East Asia. Although the timing of this putative expansion is unclear, our results highlight the benefit of studying animals that do not belong to particular breeds when investigating aspects of a population's history.

Validation of MODIS 16 global terrestrial evapotranspiration products in various climates and land cover types in Asia

Evapotranspiration (ET), or the sum of water released to the atmosphere from ground surfaces, intercepts canopy precipitation through evaporation and plant transpiration and is one of the most significant components in the water cycle. In this study, Moderate Resolution Imaging Spectroradiometer (MODIS) 16 global terrestrial ET products were validated at 17 flux tower locations in Asia. Overall, overestimations due to energy balance misclosure distorted the trend of the data at nine locations [r: 0.27–0.82; bias: −21.41–2.38 mm 8-d−1; Root Mean Square Error (RMSE): 6.12–21.81 mm 8-d−1]. Regardless of variation in the scattering patterns, good agreements between MODIS-based ET and ET measured at the flux towers were observed at five locations (r: 0.50–0.76; bias: −1.42–1.99 mm 8-d−1; RMSE: 1.99–8.96 mm 8-d−1). Underestimation at one site (r = 0.28, bias = −17.00 mm 8-d−1, RMSE = 17.41 mm 8-d−1) was accompanied by mismatches at two sites (r = 0.12–0.18; bias = −4.19 — −0.04 mm 8-d−1, RMSE = 5.76–7.66 mm 8-d−1). The best performances of the MOD16 ET algorithm were observed at sites with forested land cover, but no substantial differences were found under a variety of climate conditions. This study is the first comprehensive trial to validate global terrestrial MODIS ET in Asia, showing that a MODIS global terrestrial ET product can estimate actual ET with reasonable accuracy. We believe that our results can be used as baseline ET values for satellite image-based ET mapping research in South Korea.

International Collaboration on Air Pollution and Pregnancy Outcomes (ICAPPO)

Reviews find a likely adverse effect of air pollution on perinatal outcomes, but variation of findings hinders the ability to incorporate the research into policy. The International Collaboration on Air Pollution and Pregnancy Outcomes (ICAPPO) was formed to better understand relationships between air pollution and adverse birth outcomes through standardized parallel analyses in datasets from different countries. A planning group with 10 members from 6 countries was formed to coordinate the project. Collaboration participants have datasets with air pollution values and birth outcomes. Eighteen research groups with data for approximately 20 locations in Asia, Australia, Europe, North America, and South America are participating, with most participating in an initial pilot study. Datasets generally cover the 1990s. Number of births is generally in the hundreds of thousands, but ranges from around 1,000 to about one million. Almost all participants have some measure of particulate matter, and most have ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide. Strong enthusiasm for participating and a geographically-diverse range of participants should lead to understanding uncertainties about the role of air pollution in perinatal outcomes and provide decision-makers with better tools to account for pregnancy outcomes in air pollution policies.

Estimation of N*0 for the Two-Scale Gamma Raindrop Size Distribution Model and Its Statistical Properties at Several Locations in Asia

Abstract An automatic estimation method is developed to detect stepwise changes in the amplitude parameter of the normalized raindrop size distribution (DSD) N*0. To estimate N*0, it is also assumed that the variation of three DSD parameters follows the two-scale gamma DSD model; this is defined as a DSD model in which one DSD parameter is fixed, the second is allowed to vary rapidly, and the third is constant over a certain space or time domain and sometimes exhibits stepwise transitions. For this study, it is assumed that N*0 is the third DSD parameter. To estimate this stepwise-varying parameter automatically, a non-Gaussian state-space model is used for the time series of log10N*0. The smoothed time series of log10N*0 fit well to the stepwise transition of log10N*0 when it was assumed that the state transition probability follows a Cauchy distribution. By analyzing the long-term disdrometer data using this state-space model, statistical properties for log10N*0 are obtained at several Asian locations. It is confirmed that the N*0 thus estimated is useful to improve the rain-rate estimation from the measurement of radar reflectivity factor.

A model for simulating plant N accumulation, growth and yield of diverse rice genotypes grown under different soil and climatic conditions

The objective of this study was to develop a whole-process model for explaining genotypic and environmental variations in the growth and yield of irrigated rice by incorporating a newly developed sub-model for plant nitrogen (N) uptake into a previously reported model for simulating growth and yield based on measured plant N. The N-uptake process model was developed based on two hypotheses: (1) the rate of root system development in the horizontal direction is proportional to the rate of leaf area index (LAI) development, and (2) root N-absorption activity depends on the amount of carbohydrate allocated to roots. The model employed two empirical soil parameters characterizing indigenous N supply and N loss. Calibration of the N-uptake process sub-model and validation of the whole-process model were made using plant N accumulation, and growth and yield data obtained from a cross-locational experiment on nine rice genotypes at seven locations in Asia, respectively. Calibration of the N-uptake process sub-model indicated that a large genotypic difference exists in the proportionality constant between rate of root system development and that of LAI development during early growth stages. The whole-process model simultaneously explained the observed genotypic and environmental variation in the dynamics of plant N accumulation ( R 2 = 0.91 for the entire dataset), above-ground biomass growth ( R 2 = 0.94), LAI development ( R 2 = 0.78) and leaf N content ( R 2 = 0.79), and spikelet number per unit area ( R 2 = 0.78) and rough grain yield ( R 2 = 0.81). The estimated value of the site (field)-specific soil parameter representing the rate of N loss was negatively correlated with cation exchange capacity of the soil and was approximated by a logarithmic function of cation exchange capacity for seven sites ( R 2 = 0.95). Large yearly and locational variations were estimated in the soil parameter for representing the rate of indigenous N supply at 25 °C. With the use of these two soil parameters, the whole-system model explained the observed genotypic and environmental variations in plant N accumulation, growth and yield of rice in Asia.

A process model for explaining genotypic and environmental variation in growth and yield of rice based on measured plant N accumulation

The objective of this study was to develop a mechanistic model for simulating the genotypic and environmental variation in rice growth and yield based on measured plant N accumulation. The model calibrations and evaluations were conducted for rice growth and yield data obtained from a cross-locational experiment on 9 genotypes at 7 climatically different locations in Asia. The rough dry grain yield measured in the experiment ranged from 71 to 1044 g m −2 over the genotypes and locations. An entire process model was developed by integrating sub-models for simulating the processes of leaf area index development, partitioning of nitrogen within plant organs, vegetative biomass growth, spikelet number determination, and yield. The entire process model considered down-regulation of photosynthesis caused by limited capacity for end-product utilization in growing sink organs by representing canopy photosynthetic rate as a function of sugar content per unit leaf nitrogen content. The model well explained the observed genotypic and environmental variation in the dynamics of above-ground biomass growth (for validation dataset, R 2 = 95), leaf area index development ( R 2 = 0.82) and leaf N content ( R 2 = 0.85), and spikelet number per unit area ( R 2 = 0.67) and rough grain yield ( R 2 = 0.66), simultaneously. The model calibrations for each sub-model and the entire process model against observed data identified 10 genotype-specific model parameters as important traits for determining genotypic differences in the growth attributes. Out of the 10 parameters, 5 were related to the processes of phenological development and spikelet sterility, considered to be major determinants of genotypic adaptability to climate. The other 5 parameters of stomatal conductance, radiation extinction coefficient, nitrogen use efficiency in spikelet differentiation, critical leaf N causing senescence, and potential single grain mass had significant influence on the yield potential of genotypes under given climate conditions.

Stabilization of the Mass Absorption Cross Section of Black Carbon for Filter-Based Absorption Photometry by the use of a Heated Inlet

In principle, mass concentrations of black carbon (BC) (M BC) can be estimated by the measurement of the light absorption coefficient of BC. Filter-based methods, which quantify the absorption coefficient (b abs) from the change in transmission through a filter loaded with particles, have been widely used to measure M BC. However, reliable determination of M BC has been very difficult because of the large variability in the mass absorption cross section (C abs), which is the conversion factor from b abs to M BC. Coating of BC by volatile compounds and the co-existence of light-scattering particles contribute to the variability of C abs. In order to overcome this difficulty, volatile aerosol components were removed before collection of BC particles on filters by heating a section of the inlet to 400°C. We made simultaneous measurements of b abs by two types of photometers (Particle Soot Absorption Photometer (PSAP) and Continuous Soot Monitoring System (COSMOS)) together with M BC by an EC-OC analyzer to determine C abs at 6 locations in Asia. C abs was stable at 10.5 ± 0.7 m2 g −1 at a wavelength of 565 nm for BC strongly impacted by emissions from vehicles and biomass burning. The stable C abs value provides a firm basis for its use in estimating M BC by COSMOS and PSAP with an accuracy of about 10%. For the quantitative interpretation of the ratio of the C abs to the model-calculated C abs∗, we measured C abs for mono-disperse nigrosin particles in the laboratory. The C abs/C abs∗ ratio was 1.4–1.9 at the 100–200 nm diameters, explaining the ratio of 1.8 for ambient BC.

Disentangling the effect of environmental factors on yield and nitrogen uptake of irrigated rice in Asia

Abstract Rice yield is the result of the interaction between genotype (cultivar characteristics), environment (climate and soil conditions), and management. Few studies have attempted to isolate the contribution of each of these factors. Here the rice growth model ORYZA2000 was used to analyse the variation in yield, nitrogen (N) uptake, and internal N use efficiency (INUE, grain yield per unit total crop N uptake) of rice in different environments. First, ORYZA2000 was calibrated and evaluated using an empirical data set that spanned three varieties, three years, and eight locations in Asia. Next, we used the model to investigate the relative contribution of indigenous soil N and external N supply and of the weather factors temperature and radiation to observed variation in yield. With normalized root mean square errors (RMSE n ) of 6–16%, ORYZA2000 satisfactorily simulated crop biomass, yield, N uptake, and INUE, that strongly varied among genotypes and locations. Environmental factors contributed differentially to yield, N uptake, and INUE, and their contributions were modified by N management. Indigenous soil N supply affected yield and INUE more strongly than weather conditions at low fertilizer N rates, but its influence was less pronounced at higher fertilizer N rates. Under both, low and high fertilizer N rates, indigenous soil N supply affected N uptake more than weather conditions did. Temperature contributed more than radiation to the variation in yield, N uptake, and INUE. Results suggest that N fertilizer management should take into account indigenous soil N supply, while temperature is the major factor in the selection of genotypes and sowing dates in maximizing rice yield.

Carbonaceous aerosol composition over various regions of China during 2006

The elemental (EC) and organic carbon (OC) fractions of ambient aerosols were determined by thermo‐chemical analysis of 24‐h samples collected during 2006 at 18 stations in China located at various rural, urban and remote locations. The annual mean concentration levels are found to be 0.35 ± 0.01 μg EC m−3 and 3.0 ± 0.21 μg OC m−3 for the remote background sites; 3.6 ± 0.93 μg EC m−3 and 16.1 ± 5.2 μg OC m−3 for the regional sites; and 11.2 ± 2.0 μg EC m−3 and 33.1 ± 9.6 μg OC m−3 for the urban sites, respectively. At rural sites representing regionally dispersed aerosols, levels are comparable to other locations in Asia. At all sites, both EC and OC show a consistent seasonal variation with a peak in winter, dropping in spring, reaching a minimum in summer and then increasing in autumn. The ratio of OC to EC is on the order of 3 for the urban locations, but can reach as high as 6 at the rural sites. This may partly be due to the open biomass burning in field of rural area, but may also indicate the presence of a regional background of secondary organic carbon (SOC) in China. These high ratios of OC/EC complicate the assessment of the climatic impacts of carbonaceous aerosols in China, as optical scattering from the high OC concentrations may lead to a cooling effect that counteracts the possible warming caused by EC optical absorption.

A model for explaining genotypic and environmental variation in vegetative biomass growth in rice based on observed LAI and leaf nitrogen content

The objectives of this study are to propose a model for explaining the genotypic and environmental variation in above-ground biomass growth via photosynthesis and respiration processes from transplanting to heading for different rice genotypes grown under a wide range of environments, and to identify the physiological traits associated with genotypic difference in the biomass growth based on model analysis. Cross-locational experiments were conducted with nine different rice genotypes at eight locations in Asia covering a wide climate range under irrigated conditions with sufficient nitrogen application. The crop growth rate observed during the period from transplanting to heading ranged from 3.4 to 19.4 g m −2 d −1 among the genotypes grown at the eight locations. About one-third of the data sets were utilized for model calibration and the remaining sets were used for model validation. An above-ground biomass growth model was developed by integrating processes of single leaf photosynthesis as a function of stomatal conductance and leaf nitrogen content, growth and maintenance respiration and crop development. To rigorously examine the validity of this process model, measured data were input as external variables for leaf area index (LAI) development and leaf nitrogen content per unit leaf area. The model well explained the observed dynamics in above-ground biomass growth ( R 2 = 0.95*** for validation dataset) of nine rice genotypes grown under a variety of environments in Asia. The model simulation suggested that genotypic difference in the biomass growth was closely related to the difference in the stomatal conductance and leaf nitrogen content, as well as to LAI. This paper proposes the model structure, algorithms and all parameter values contained in the model, and discuss its effectiveness as a component of a more comprehensive model for simulating dynamics of biomass growth, LAI development and nitrogen uptake as a function of genotypic coefficients and environments.

A model explaining genotypic and environmental variation in leaf area development of rice based on biomass growth and leaf N accumulation

Leaf area index (LAI) is one of the major determinants of crop photosynthesis. The objectives of this study were to clarify the relationship between LAI development and crop growth in diverse rice genotypes grown under widely different climate conditions and to develop a model explaining genotypic and environmental variation in LAI dynamics based on environmental and plant factors. Cross-locational experiments were conducted with nine different rice genotypes at eight locations in Asia covering a wide climate range under irrigated conditions with sufficient nitrogen application. The LAI observed at the heading stage ranged from 0.85 to 8.77 among the genotypes grown at the eight locations. A fairly stable allometric relationship was observed between LAI development and above-ground biomass growth during the period from transplanting to 2 weeks before heading over all the genotypes, sites and years ( r = 0.91). The allometric relationship was, however, under the influence of leaf nitrogen content per unit leaf area (LNC, g m −2 leaf) and air temperature. On the basis of these results, we modeled the LAI development as a function of relative crop growth rate (RGR), LNC and air temperature. The rate of LAI decrease associated with leaf senescence was also described as a function of LNC. The observed genotypic and environmental variations in dynamics of LAI development were well explained ( R 2 = 0.95) by the model with only one genotype-specific parameter to represent the critical LNC below which leaves start senescing. The genotypic difference in the rate of LAI development was effectively explained by the variation in LNC and RGR under various environments, while that of LAI decrease with leaf senescence was explained by the variation in LNC and a genotype-specific coefficient of the critical LNC. It was suggested that genotypic difference in LNC was derived from the difference in crop N uptake at a given RGR.

An examination of summer precipitation over Asia based on TRMM/TMI

A 6-year dataset of summer monthly mean precipitation derived from Tropical Precipitation Measurement Mission (TRMM)-Microwave Imager (TMI) was used to delineate the spatial distribution patterns of precipitation throughout Asian areas, which indicates that there are three rainfall centers located at the northern coast of the Bay of Bengal, the South China Sea and the western equatorial Pacific Warm Pool, respectively. Based upon the analysis of horizontal distribution, the capability of TMI for characterizing terrestrial and maritime precipitation has been evaluated and compared with Global Precipitation Climatology Project (GPCP) dataset. It was found that TMI and GPCP are well consistent with each other, while a few significant differences occur at several regions over land. By investigating rainfall estimates over six specific locations in Asia, a systematic underestimation of TMI was demonstrated, which could be explained by the inherent deficiency within TMI terrestrial algorithm relying on scattering signal from ice particles in a precipitation system. A further analysis shows that the highly inhomogeneous distribution of rain gauges employed by GPCP contributes a great deal to the significant discrepancy between GPCP and TMI, especially over regions surrounding the Tibetan Plateau where rain gauges are quite scarce.

Describing and measuring ethno-entomological knowledge of rice pests: tradition and change among Asian rice farmers

The paper presents a methodology that guided several ethnoentomo- logical research projects and goes on to examine and compare the results from two independent research locations in Asia. The first location is in the Philippines, a Green Revolution area that has been heavily impacted by extension messages and insecticide use. The second location is in Nepal which has a traditional subsistence orientation and has remained widely unaffected by agricultural modernization. The paper emphasizes the differences and similarities of the results from the two sites and discusses the role of the methodology and methods used in capturing ethno- entomological knowledge, particularly with regard to insect pests in rice. The results of both investigations share the importance of agronomic criteria among farmers in insect classification and sorting criteria, thus highlighting the relevance of functional criteria. Farmers at both research sites have difficulties in identifying the lifecycles of insects. We discuss the issues of tradition and change in farmer entomological knowledge and providing support to the knowledge base of farmers though pro- grams like IPM-Farmer Field Schools as opposed to broad-based recommendations for crop pest management.

A model explaining genotypic and environmental variation of rice spikelet number per unit area measured by cross-locational experiments in Asia

Rice ( Oryza sativa L.) yield is closely related to the number of spikelets per unit area which varies with the genotype and environment. The objectives were to identify plant factors associated with genotypic and environmental variations in spikelet number and to develop a model that may explain the variations based on plant factors. Two-year cross-location experiments were conducted with nine widely different rice genotypes at eight locations in Asia, which covered a wide climate range from the cool temperate zone in northern Japan to the tropics in Thailand. We determined the spikelet density, crop biomass and plant nitrogen (N) content at different development stages. The spikelet density of the genotypes grown at the eight locations ranged from 5130 to 71,480 m −2. Spikelet density was related ( R 2 = 0.58) to N accumulation in plants up to the late spikelet differentiation stage, i.e., 2 weeks before heading. The spikelet production per unit crop-N content, however, was under the additional influence of crop growth rate (CGR) during 2-week period preceding heading. On the basis of these results and previous studies, we modeled the spikelet number per unit area as a function of plant N accumulation up to 2 weeks before heading and CGR during the 2-week period preceding heading. Approximately half of the data sets were used for parameter estimation by a SIMPLEX method and the rest for model validation. The observed genotypic and environmental variation in spikelet number was well explained ( R 2 = 0.85) by the model with only one genotype-dependent parameter to represent the number of juvenile spikelets produced per unit plant N. The other three parameters were genotype-independent. Quite a large genotypic difference was recognized in the spikelet number produced per unit plant N; the efficiency was higher in improved indica genotypes, lower in unimproved indica and javanica genotypes, and intermediate in japonica genotypes. These results suggested that the primary plant factors for increased spikelet number per unit area in rice are: (1) larger accumulation of plant N up to 2 weeks before heading to increase spikelet differentiation, (2) higher CGR during 2-week period preceding heading to suppress degeneration of juvenile spikelets and (3) high spikelet production efficiency per unit N of genotypes.

Sustained transmission of dengue virus type 1 in the Pacific due to repeated introductions of different Asian strains

Outbreaks of dengue due to dengue virus type 1 (DENV-1) occurred almost simultaneously in 2001 in Myanmar and at multiple sites almost 10,000 km away in the Pacific. Phylogenetic analyses of the E protein genes of DENV-1 strains recovered from Asia and the Pacific revealed three major viral genotypes (I, II, and III) with distinct clades within each. The majority of strains from the Pacific and Myanmar, and a number of other Asian strains fell into genotype I. Genotype II comprised a smaller set of Asian and Pacific strains, while genotype III contained viruses from diverse geographical localities. These analyses suggested that the continuing outbreak of dengue in the Pacific has been due to multiple, direct, introductions of dengue viruses from a variety of locations in Asia followed by local transmission. There was no evidence that the introduction of these viruses into the Pacific was associated with any adaptive changes in the E protein of the viruses.

Morphological and Phenological Variation in World Collections of Velvetleaf (Abutilon theophrasti)

Our lab characterized the growth and development of 83 velvetleaf accessions, collected from locations in Asia, India, Europe, Eastern Africa and North America, to test the hypothesis that two biotypes (“crop” and “weedy”) exist and are easily differentiated. Measurements taken to gauge morphological and phenological variability include: initial seed weight, stem height at 3, 7, and 11 weeks, leaf size at 3, 7, and 11 weeks, stem and petiole color, time to flowering, time to first capsule maturity, stem height at flowering, height to first mature capsule, basal stem diameter, number of capsules, and capsule size and color. Analyses indicate that accessions producing yellow-colored seed capsules were taller, produced fewer nodes, and were longer-lived than their brown-colored counterparts. This finding supports previous assertions that the yellow-colored varieties were originally selected for use as a fiber crop: i.e., increased stem yield resulted in longer lengths of lignified tissue. The accessions producing brown-colored capsules exhibited greater reproductive output, as measured by the number of capsules and the number of seed-containing valves per capsule, a desirable trait for weedy species. Using capsule color as an independent variable, Discriminant Analysis was able to correctly classify 96% of the observations by the remaining characters, further affirming that the yellow- and brown-capsuled accessions varied, significantly, with respect to their morphology and phenology. Velvetleaf is believed to have originated in China, where it was eventually domesticated. Early records suggest that velvetleaf, a noxious weed in modern agricultural production, was introduced to colonial America to serve as a fiber source for the burgeoning rope-making industry.

Identification of QTL for growth- and grain yield-related traits in rice across nine locations of Asia.

Rice double-haploid (DH) lines of an indica and japonica cross were grown at nine different locations across four countries in Asia. Genotype-by-environment (G x E) interaction analysis for 11 growth- and grain yield-related traits in nine locations was estimated by AMMI analysis. Maximum G x E interaction was exhibited for fertility percentage number of spikelets and grain yield. Plant height was least affected by environment, and the AMMI model explained a total of 76.2% of the interaction effect. Mean environment was computed by averaging the nine environments and subsequently analyzed with other environments to map quantitative trait loci (QTL). QTL controlling the 11 traits were detected by interval analysis using mapmaker/qtl. A threshold LOD of >/=3.20 was used to identify significant QTL. A total of 126 QTL were identified for the 11 traits across nine locations. Thirty-four QTL common in more than one environment were identified on ten chromosomes. A maximum of 44 QTL were detected for panicle length, and the maximum number of common QTL were detected for days to heading detected. A single locus for plant height (RZ730-RG810) had QTL common in all ten environments, confirming AMMI results that QTL for plant height were affected the least by environment, indicating the stability of the trait. Two QTL were detected for grain yield and 19 for thousand-grain weight in all DH lines. The number of QTL per trait per location ranged from zero to four. Clustering of the QTL for different traits at the same marker intervals was observed for plant height, panicle number, panicle length and spikelet number suggesting that pleiotropism and or tight linkage of different traits could be the possible reason for the congruence of several QTL. The many QTL detected by the same marker interval across environments indicate that QTL for most traits are stable and not essentially affected by environmental factors.

Variation in mitochondrial DNA of Vietnamese pigs: relationships with Asian domestic pigs and Ryukyu wild boars.

Mitochondrial DNA (mtDNA) sequences (574 bp) of 30 Vietnamese pigs (large and small) were examined and compared with those of 61 haplotypes from wild boars and domestic pigs from various locations in Asia. The large Vietnamese pigs had genetic links to Ryukyu wild boars in southern Japan. The small Vietnamese pigs were closely related to other East Asian domestic pigs. These results indicate that Vietnamese pigs are genetically diverse and may be descendents of wild and domestic pigs from other regions of Asia.

Effects of Executive Share Option Plans on Shareholder Wealth and Firm Performance: The Singapore Evidence

AbstractThe main purpose of our paper is to study the institutional nature and characteristics of executive share option plans (ESOPs) in Singapore, a fast‐growing economy and an important investment location in Asia. Our study provides an interesting comparison between the characteristics of ESOPs in Singapore and those in the US. Our paper also investigates the short‐term market reaction to ESOP announcements and the long‐run stock and operating performance of the sample firms following the adoption of the ESOPs. Results indicate weak evidence of a positive abnormal return on the days surrounding the announcement of the ESOPs. However, there is no evidence of long‐term superior stock and operating performance for the ESOP firms relative to benchmarks. The lack of significant incentive effects for the sample firms reflects mainly the unique regulatory environment in Singapore.