Isolation and characterization of microsatellite markers in the gecko Gekko swinhonis and cross‐species amplification in other gekkonid species

Gekko swinhonis is a gekkonid lizard endemic to China, inhabiting Loess Plateau, Huabei Plain, Huanghuai Plain and areas north of the Yangtze River. We characterized 21 dinucleotide microsatellite loci from an AC/AG‐enriched genomic library of G. swinhonis. The number of alleles per locus ranged from eight to 24 and the observed and expected heterozygosities ranged from 0.160 to 0.834 and from 0.584 to 0.917, respectively. We also tested the utility of these loci in other Gekko and Hemidactylus species; many of these loci can be cross‐amplified.     

Polymorphic microsatellites in largemouth bronze gudgeon (Coreius guichenoti) developed from repeat‐enriched libraries and cross‐species amplifications

Largemouth bronze gudgeon (Coreius guichenoti) is a medium‐sized fish endemic from the upper Yangtze River of China and its survival is threatened by the construction of the Three Gorges Dam. This study reports 20 new polymorphic microsatellites from a repeat‐enriched genomic library with a mean number allele of 5.2, and observed and expected heterozygosities ranging from 0.035 to 1, and from 0.13 to 0.917, respectively. In a cross‐species amplification test, nine of the 37 tested loci were found to be also polymorphic in a congeneric species, brass gudgeon (C. heterodon). In addition, other four loci from common carp (Cyprinus carpio) were also polymorphic in C. guichenoti. Out of these 24 polymorphic microsatellites, only three loci significantly deviated from Hardy–Weinberg equilibrium in the sampled population (P < 0.0025), and all pairwise tests for linkage disequilibrium among loci were nonsignificant after applying sequential Bonferroni correction (P > 0.0026). These novel microsatellites provide sufficient levels of polymorphism for studies on population genetics and conservation in C. guichenoti and its related species.     

Sixteen new simple sequence repeat markers from Brassica juncea expressed sequences and their cross‐species amplification

The availability of expressed sequence data derived from gene discovery programs enables mining for simple sequence repeats (SSR), providing useful genetic markers for crop improvement. These markers are inexpensive, require minimal labour to produce and can frequently be associated with functionally annotated genes. This study presents the development and characterization of 16 expressed sequence tags (EST)‐SSR markers from Brassica juncea and their cross‐amplification across Brassica species. Sixteen primer pairs were assessed for polymorphism in all genomes of the diploid and amphidiploid Brassica species. The markers show reliable amplification, considerable polymorphism and high transferability across species, demonstrating the utility of EST‐SSRs for genetic analysis of brassicas.     

Identification and characterization of simple sequence repeat markers from Brassica napus expressed sequences

The availability of expressed sequence data derived from gene discovery programs enables mining for simple sequence repeats (SSR), providing useful genetic markers for crop improvement. These markers are inexpensive, require minimal labour to produce and can frequently be associated with functionally annotated genes. This study presents the development and characterization of 24 expressed sequence tags (EST)‐SSR markers from Brassica napus and their cross‐amplification across Brassica species. The markers show reliable amplification, genome specificity and considerable polymorphism, demonstrating the utility of EST‐SSRs for genetic analysis of wild Brassica populations and commercial Brassica germplasm.     

A multiplex set of microsatellite markers for the scarlet rosefinch (Carpodacus erythrinus)

Cardueline finches have become important models in studies of sexual selection and evolution of carotenoid‐based ornamentation. Here, we describe eight new polymorphic microsatellites isolated from the Scarlet rosefinch (Carpodacus erythrinus) and four from the House finch (Carpodacus mexicanus). Together with the cross‐species amplification of additional loci, originally published for two species of songbirds, we optimized a multiplex panel for C. erythrinus allowing genotyping of 22 polymorphic loci. Number of alleles and heterozygosity per locus in a sample of 34 individuals ranged from three to 38 and from 0.27 to 0.94, respectively.     

Cross‐taxon congruence of multiple diversity facets of freshwater assemblages is determined by large‐scale processes across China

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Development of 28 EST‐SSR markers based on transcriptome sequences of Gobiobotia filifer and cross‐species amplification

Gobiobotia filifer is a small benthic fish distributed in Yangtze River Basin. The abundance of G. filifer increased after impoundment of Xiluodu Dam and Xiangjiaba Dam. The state of population structure and changes of genetic diversity before and after impoundment of Xiluodu Dam and Xiangjiaba Dam were interesting issues. However, efficient molecular markers were rare, which will limit us to solve above problems. Twenty‐eight expressed sequence tag SSRs (EST‐SSRs) were successfully identified and verified as stable amplification and polymorphic loci by polyacrylamide gel electrophoresis (PAGE) and capillary electrophoresis. The number of alleles at these EST‐SSR loci ranged from 3 to 14, the polymorphism information content values were 0.125–0.897, and the observed and expected heterozygosities were 0.0–0.857 and 0.132–0.928, respectively. Cross‐species amplification of the 28 loci developed in this study was examined in seven individuals of each of the 7 taxa. The amplification efficiency of 28 EST‐SSRs primer pairs is related to the distance of genetic relationship between cross‐species with G. filifer, and same subfamily species (Xenophysogobio boulengeri and Xenophysogobio nudicorpa) showed the highest (50%) amplification efficiency. These EST‐SSR markers could be used to analyse genetic diversity and population structure of G. filifer and related species.     

The progress in insect cross‐resistance among Bacillus thuringiensis toxins

Bt crop pyramids produce two or more Bt proteins active to broaden the spectrum of action and to delay the development of resistance in exposed insect populations. The cross‐resistance between Bt toxins is a vital restriction factor for Bt crop pyramids, which may reduce the effect of pyramid strategy. In this review, the status of the cross‐resistance among more than 20 Bt toxins that are most commonly used against 13 insect pests was analyzed. The potential mechanisms of cross‐resistance are discussed. The corresponding measures, including pyramid RNA interference and Bt toxin, “high dose/refuge,” and so on are advised to be taken for adopting the pyramided strategy to delay the Bt evolution of resistance and control the target pest insect.