Export performance of major cultured shrimp producers in the Japanese and US markets

Increase in shrimp farming was stimulated by growth in world market for high-value shrimp products in the 1980s. The major cultured shrimp producers are located in Asia-Pacific and Latin American regions. The revealed comparative advantage (RCA) method is used to provide insights into the export performance of nine selected shrimp producers in the Japan and United States markets, separately. Shrimp is marketed in a wide variety of product forms, and prices vary according to various product attributes including species, size, taste, quality and origin. The results show that vertical product differentiation concerning different varieties of a good in terms of both quality and price plays an important role on the relative export competition of shrimp products among major shrimp-exporting countries. As a result of the geographical advantage, Asia-Pacific producers enjoy comparative advantage in the Japanese imported shrimp market. Joint ventures with the United States provide great benefits to Ecuador and Mexico in exporting fresh shrimp into the United States market.     

Genetic diversity and relatedness of selected Iranian rice cultivars and disease resistance donors assayed by simple sequence repeats and candidate defense gene markers

As a prerequisite to improving diseaseresistance and grain quality in Iranianrice cultivars, we determined the geneticrelatedness of popular local cultivars andblast-resistance donor germplasm usingfingerprints derived from simple sequencerepeat (SSR) and plant defense genemarkers. Fifty SSR markers and 28 defensecandidate genes were used to assess thegenetic diversity among popular ricecultivars from Iran and donors of blastresistance from breeding programs in Asia.Gene diversity estimate of the 16 corebreeding lines was 0.440 ± 0.028 basedon SSR markers. Genetic relationships amongthe cultivars were determined by clusteranalysis using SSR and candidate genedatasets. DNA fingerprints derived fromSSR and defense gene markers gave similargroupings of cultivars consistent withtheir genetic background: a) Iranian localvarieties, b) improved varieties in Iranplus donor indica germplasm from Asia, andc) japonica germplasm. Within-groupsimilarities for the traditional andimproved cultivars were greater than 80%and 75%, respectively. The traditional andimproved cultivars showed differentialreaction to blast pathogen isolates; alltraditional varieties were susceptible toblast pathogen isolates in Iran butresistant to isolates in the Philippines,whereas the improved varieties showedopposite reaction to pathogen isolates inIran and the Philippines. Both molecularand phenotypic data suggest a narrowgenetic basis in local and improvedcultivars in Iran and the need forincluding more diversity for the breedingprogram. The high degree of polymorphismobserved between local cultivars and donorsof blast resistance provide the neededinformation to follow the transmission ofresistance alleles from the donors inadvancing breeding lines.     

Movements of the ricefield rat,Rattus argentiventer,near a trap-barrier system in rice crops in West Java,Indonesia

The movements of the ricefield rats ( Rattus argentiventer ) near a trap-barrier system (TBS) were assessed in lowland flood-irrigated rice crops in West Java, Indonesia, to test the hypothesis that a TBS with a 'trap-crop' modifies the movements of rats within 200 m from the trap-crop. The home range use and locations of rat burrows were assessed using radiotelemetry at two sites, one with a TBS with trap-crop (Treatment site, the crop inside the fence was planted 3 weeks earlier than the surrounding crop) and the other with a TBS without trap-crop (Control site, the crop inside the fence was planted at the same time as the surrounding crop). Each TBS was a 50 2 50 m plastic fence with eight multiple-capture rat traps set at the base. More than 700 rats were caught in the TBS with trap-crop, whereas only 10 rats were caught in the TBS without trap-crop. The home range size of females was significantly smaller at the Treatment site (0.96 ha) than the Control site (2.99 ha), but there was no difference for males. Seventy-eight per cent of rats caught in the TBS and fitted with radiocollars had their daytime burrow locations within 200 m of the TBS. We could not determine if the rats caught in the TBS were residents or transients according to demographic parameters. Our results support the hypothesis that a TBS with a trap-crop protects the surrounding rice crop out to a distance of at least 200 m.     

Orientational ordering of polymers by atomic force microscope tip-surface interaction

Results of studies on the interaction between the tip of an atomic force microscope and polystyrene molecules in a film spread on a surface are reported. The tip produces a persistent deformation on the film; some of the polymer molecules are eventually pulled up by the tip. Nanometer-size structures are induced, resulting in a pattern that is periodic and is oriented perpendicular to the scan direction.     

Toward direct measurement of atmospheric nucleation

Atmospheric aerosol formation is known to occur almost all over the world, and the importance of these particles to climate and air quality has been recognized. Although almost all of the processes driving aerosol formation take place below a particle diameter of 3 nanometers, observations cover only larger particles. We introduce an instrumental setup to measure atmospheric concentrations of both neutral and charged nanometer-sized clusters. By applying the instruments in the field, we come to three important conclusions: (i) A pool of numerous neutral clusters in the sub-3 nanometer size range is continuously present; (ii) the processes initiating atmospheric aerosol formation start from particle sizes of approximately 1.5 nanometers; and (iii) neutral nucleation dominates over the ion-induced mechanism, at least in boreal forest conditions.     

Genomics and agriculture. Collaborations in rice

Advances in rice genomics will contribute to gene discovery and rice productivity, but many of the products with high potential for alleviating poverty and improving human nutrition may not be those that attract private investment. Although most genetic resources and biological expertise for functional genomics are in the public, many proprietary technologies are owned by the private sector. A public resource platform is needed for the application of genomic technology to accelerate gene discovery. We present a model and general principles in collaboration that can serve the poor and encourage innovation by both the public and private sectors.     

Transmission dynamics of the etiological agent of SARS in Hong Kong: impact of public health interventions

We present an analysis of the first 10 weeks of the severe acute respiratory syndrome (SARS) epidemic in Hong Kong. The epidemic to date has been characterized by two large clusters-initiated by two separate "super-spread" events (SSEs)-and by ongoing community transmission. By fitting a stochastic model to data on 1512 cases, including these clusters, we show that the etiological agent of SARS is moderately transmissible. Excluding SSEs, we estimate that 2.7 secondary infections were generated per case on average at the start of the epidemic, with a substantial contribution from hospital transmission. Transmission rates fell during the epidemic, primarily as a result of reductions in population contact rates and improved hospital infection control, but also because of more rapid hospital attendance by symptomatic individuals. As a result, the epidemic is now in decline, although continued vigilance is necessary for this to be maintained. Restrictions on longer range population movement are shown to be a potentially useful additional control measure in some contexts. We estimate that most currently infected persons are now hospitalized, which highlights the importance of control of nosocomial transmission.     

Targeted Large-Scale Genome Mining and Candidate Prioritization for Natural Product Discovery

Large-scale genome-mining analyses have identified an enormous number of cryptic biosynthetic gene clusters (BGCs) as a great source of novel bioactive natural products. Given the sheer number of natural product (NP) candidates, effective strategies and computational methods are keys to choosing appropriate BGCs for further NP characterization and production. This review discusses genomics-based approaches for prioritizing candidate BGCs extracted from large-scale genomic data, by highlighting studies that have successfully produced compounds with high chemical novelty, novel biosynthesis pathway, and potent bioactivities. We group these studies based on their BGC-prioritization logics: detecting presence of resistance genes, use of phylogenomics analysis as a guide, and targeting for specific chemical structures. We also briefly comment on the different bioinformatics tools used in the field and examine practical considerations when employing a large-scale genome mining study.