cid: a rapid and efficient bioinformatic tool for the detection of SSRs from genomic libraries

Microsatellite loci characterized in the leaf-cutter ant Atta laevigata

BACKGROUND

The leaf-cutter ant Atta laevigata (Formicidae: Attini) is an agricultural pest largely distributed in the Neotropics and a model organism for studies of evolution, speciation and population genetics. Microsatellites are a very powerful tool for these kind of studies, but such markers are not available for studies on A. laevigata. In the present report, we describe the isolation and characterization of nine microsatellite loci in A. laevigata and the testing of these markers across other species of leaf-cutter ants.

FINDINGS

Nine microsatellite loci, consisting of six dinucloeotide, one trinucleotide, one tetranucleotide, and one di/trinucleotide repeat motifs, were isolated and characterized. Primers and protocols were successfully designed to selectively amplify these markers. To test effectiveness of these markers for detailed population genetic studies, we genotyped female workers collected from 36 monogynic nests of A. laevigata and found that eight loci were within Hardy-Weinberg expectations, while the remaining locus had a deficiency of heterozygotes. Micro-Checker analysis of individuals from 55 monogynic nests indicated that loci Alae11, Alae24, Alae18 showed signs of null alleles. For the remaining six loci, the number of alleles per locus ranged between 2 and 11, with expected heterozygosity ranging between 0.07 and 0.88. All of these loci cross-amplified in other species of Atta.

CONCLUSIONS

These six polymorphic microsatellite loci should prove useful for future genetic investigations of the pest species Atta laevigata, as well as studies of other species of leaf-cutter ants in the genus Atta.

Isolation and characterization of microsatellite DNA markers for the Oriental White stork, Ciconia boyciana

Following FIASCO protocol and across-amplification approach, we present eleven microsatellite primers of the Oriental White stork, Ciconia boyciana in this article. All loci were polymorphic, except for locus Cbo235, which possessed two alleles but was homozygous in all 23 individuals of C. boyciana used in this study. The number of the alleles per locus ranged from two to eight, and the observed heterozygosity (H(o)) and expected heterozygosity (H(E)) ranged from 0 to 0.857 and 0.222 to 0.851, respectively. These markers are proved useful in genetic study of C. boyciana.

Isolation and characterization of microsatellite loci in the Chinese Cobra Naja atra (Elapidae)

We characterize thirteen polymorphic microsatellite loci isolated from Naja atra genomic libraries, which were enriched for AC-motif microsatellites. The thirteen loci were screened on a group of 48 individuals from two populations, one in Yong’an and the other in Ganzhou. These markers revealed a relatively high degree of genetic diversity (4–12 alleles per locus) and heterozygosity (Ho ranged from 0.213–0.854 and He ranged from 0.301–0.838). Tests for departure from Hardy-Weinberg equilibrium and for linkage disequilibrium were conducted for each of the two populations separately. After sequential Bonferroni correction, none of the 13 loci showed significant departures from Hardy-Weinberg equilibrium. Hierarchical analysis of molecular variance indicated that a small but significant (P < 0.001) proportion (16.0%) of the total variation in the microsatellite DNA data were attributable to differences among populations, indicating geographical structuring and restricted gene flow. It could be attributable to the Wuyi mountains in the area having a sufficiently isolating effect to significantly reduce gene flow. Our microsatellite data also showed a low N_m (1.31) value in the two populations from mainland China. Thus, the Yong’an and Ganzhou populations could be treated as distinct evolutionarily significant units (ESUs). The high level of polymorphism revealed by these microsatellite markers will be useful for the study of gene flow, population structure and evolutionary history of N. atra.

Polymorphic chloroplast microsatellite markers in the octoploid Lepidium meyenii (Brassicaceae) and cross-species amplification in Lepidium

PREMISE OF THE STUDY

As a crop and medicinal plant, the octoploid Andean endemic Lepidium meyenii suffers from taxonomic uncertainty. Few molecular markers are available to genotype individuals or track gene flow in wild and cultivated material. •

METHODS AND RESULTS

Using available sequence data, eight cpSSR primer pairs were developed for L. meyenii. Levels of polymorphism checked in 56 individual L. meyenii, including cultivated and wild material, revealed that the number of alleles per locus ranged from three to five, and intrapopulation allele frequencies ranged from 0.071 to 1.0. Polymerase-chain-reaction screens using our cpSSR primers in 27 other Lepidium species and three Coronopus species suggested a high degree of interspecific amplification. •

CONCLUSIONS

These polymorphic cpSSR markers should prove useful in characterizing genetic variation among cultivated and wild L. meyenii. Additionally, interspecific amplifications suggest that these markers will be useful for the study of related taxa.

Polymorphic microsatellite loci for the common marmoset (Callithrix jacchus) designed using a cost- and time-efficient method

We describe a cost- and time-efficient method for designing new microsatellite markers in any species with substantial genomic DNA sequence data available. Using this technique, we report 14 new polymorphic dinucleotide microsatellite loci isolated from the common marmoset. The relative yield of new polymorphisms was higher with less labor than described in previous marmoset studies. Of 20 loci initially evaluated, 14 were polymorphic and amplified reliably (70% success rate). The number of alleles ranged from 3 to 9 with heterozygosity varying from 0.48 to 0.83.