Microsatellite DNA Variation of the Gametophyte Clones Isolated from Introduced Laminaria japonica （Phaeophyta） and L. Iongissima of China and Varieties Derived from them

The variation of 90 Laminaria gametophyte clones representing the introduced Laminaria japonica （Group 1） and Laminaria Iongissima （Group 2）, the varieties of L. japonica （Group 3） and the varieties derived from interspecific hybrids （Group 4） was determined with 18 microsatellite markers. The allelic diversity and Nei＇s gene diversity of Group 1 were significantly higher than those of Group 2 （2.9 vs. 1.8 and 0.414 vs. 0.161, respectively）, demonstrating that the variation of the introduced L. japonica is richer than that of L. Iongissima. Both allelic diversity and Nei＇s gene diversity of Group 3 were lower than those of Group 1, indicating that only a portion of variation of L. japonica was incorporated into the varieties of L. japonica. Significant genetic differentiation was detected between four groups and between female （Population 1 ） and male （Population 2） gametophyte clones in each group. The variation among groups accounted for 39.95%, while that among populations accounted for 21.65% of the total. The genetic distance between Group 1 and Group 4 was obviously longer than that between Group 2 and Group 4 （0.686 vs. 0.291）, indicating that maternal gametophyte clone contributed more variation to the hybrids than the paternal gametophyte clone did.     

Isolation of polymorphic microsatellite markers for British Euphrasia L.

Euphrasia species in Britain attract a large amount of conservation attention due to the recognition of numerous endemic taxa in what is essentially a species‐poor flora. To develop a set of research tools to investigate the evolutionary processes underlying this diversification, a membrane enrichment procedure has been used to isolate five polymorphic microsatellite loci from Euphrasia nemorosa (Pers.) Wallr. These loci amplify polymorphic products in several other British Euphrasia species.     

Mariculture of Laminaria japonica (Laminariales, Phaeophyceae) using protoplast regeneration

The conditions for culture of viable protoplasts from Laminaria japonica were investigated and the regenerative processes were observed in detail. As a result of culturing at four water temperatures (5, 10, 15, and 18°C), we found that low water temperature was better for survival, division and rhizoidal formation of protoplast‐derived cells. Only epidermis‐derived protoplasts developed into normal sporophytes through a direct developmental process. Protoplast‐derived cells divided after 5 days and 2–10 celled germlings formed the first rhizoids after 15 days. Only initial sporophytes with the first rhizoids grew to normal sporophytes with multilayered blades, stipes and holdfasts. When these young sporophytes were transplanted into the sea, they grew to normal fertile sporophytes.     

Characterization of 17 polymorphic microsatellite loci in the Anise swallowtail,Papilio zelicaon (Lepidoptera: Papilionidae), and their amplification in related species

Fifteen polymorphic dinucleotide and two trinucleotide microsatellite loci were identified in the Anise swallowtail, Papilio zelicaon, from DNA genomic libraries enriched for simple sequence repeats. Allele numbers varied from eight to 29, with an excess of homozygotes observed for nine loci. This homozygosity is a feature of other lepidopteran microsatellites and is probably due to null alleles. Sixteen markers were amplified successfully in other representatives of Papilio with 11 loci retaining polymorphism in at least one species. These results suggest that the microsatellites reported here may be appropriate for measuring population genetic structure in a number of Papilio species.     

微卫星DNA标记技术及其在昆虫学上的应用

微卫星DNA标记作为一种多态性和稳定性高、重复性好、呈共显性的分子遗传标记技术,目前已被广泛应用于昆虫学的研究中。本文介绍了微卫星DNA标记的基本原理和特点,并综述了近年来该技术在昆虫种群遗传结构及分化、生物学特性与习性、遗传图谱的构建、基因定位以及系统发生等领域中的应用。     

Development of microsatellite markers in the toxic dinoflagellate Alexandrium tamarense (Dinophyceae)

Outbreaks of paralytic shellfish poisoning caused by the toxic dinoflagellate Alexandrium tamarense (Dinophyceae) are currently a serious problem from an economic and food hygiene point of view throughout the world. We isolated 13 polymorphic microsatellite loci from this species. These loci provided microsatellite markers with high polymorphism ranging from four to 15 alleles per locus and gene diversity between 0.632 and 0.974. The markers are available for more detailed investigations of genetic structure and gene flow of A. tamarense populations.     

Plant regeneration from protoplasts of Laminaria japonica Areschoug (Laminariales, Phaeophyceae) in a continuous-flow culture system

A continuous-flow culture system was developed for culturing Laminaria japonica protoplasts. Protoplasts were settled on 5-μm pore size nylon mesh fixed inside a 50-ml plastic syringe, and cultured in Provasoli's enriched seawater with iodine medium with a gentle upward flow generated by a peristaltic pump. In the culture system, 50% of the protoplasts regenerated their cell wall within 24 hours and almost all protoplasts regenerated a cell wall after 3 days culture. After cell wall regeneration, a number of cells divided and regenerated into sheet-shaped thalli. The thalli transferred to a tissue culture flask developed into sporophyte-like plantlets within 1 month. Plantlets then differentiated into blade, stipe, and holdfast, with a proper mucilage canal. Received: 21 April 1997 / Revision received: 27 June 1997 / Accepted: 5 July 1997     

Development of 15 polymorphic genic microsatellite DNA markers of Pacific abalone Haliotis discus hannai

Fifteen polymorphic genic microsatellite DNA markers were developed based on the expressed sequence tags of Pacific abalone Haliotis discus hannai we ourselves generated, which were used to type 32 individuals representing a cultured population. The number of alleles each locus ranged from two to 12. The observed and expected heterozygosities ranged from 0.094 to 0.969 and from 0.091 to 0.878, respectively. Among 15 loci, four were found to deviate significantly from Hardy–Weinberg equilibrium (P_HW < 0.001). No linkage disequilibrium was found between these loci. It is certain that these markers will facilitate the management and exploitation of the genetic resource of Pacific abalone.     

Development and characterization of microsatellite markers for Arenaria grandiflora L. (Caryophyllaceae)

Genomic libraries of Arenaria grandiflora enriched for di- and trinucleotide repeats were used for the development of novel microsatellite markers. The subset of 13 polymorphic markers was characterized on 40 individuals of A. grandiflora originating from lowland locations in France. The loci amplified 3 to 10 alleles per locus and expected heterozygosities ranged from 0.46 to 0.83. The newly developed markers will be used for population genetic studies and for assessing genetic composition of a restoration experiment of lowland A. grandiflora populations that are protected in France.     

Identification and characterization of (GA/CT) n - microsatellite loci from Quercus petraea

In this study a size selected genomic library from Quercus petraea was screened for (GA/CT)_n-microsatellite sequences. The resulting loci were analysed by PCR for their usefulness as molecular markers in Q. petraea and Q. robur. 17 out of 52 tested primer pairs resulted in the amplification of a polymorphic single-locus pattern. The number of alleles found per locus varied from 6 to 16. Combining the genetic variation observed for the characterized loci provides a unique genotype for all the individuals tested. Using intraspecific controlled crosses of Q. robur trees Mendelian inheritance could be shown for five loci.     

Characterization of microsatellite markers in a threatened species,the White Sands pupfish (Cyprinodon tularosa)

We report the characterization of nine new microsatellite markers for a threatened species, the White Sands pupfish (Cyprinodon tularosa), using an enriched library method. These markers show moderate levels of variation (two to five alleles per locus) in the two native populations of this species and reveal substantial divergence between these two populations as indicated by a high percentage of private alleles. These markers will prove very useful in the conservation management of this rare species.     

Characterization of 42 polymorphic microsatellite loci in Mimulus ringens (Phrymaceae) using Illumina sequencing

• Premise of the study: Microsatellite markers were isolated and characterized in Mimulus ringens (Phrymaceae), a herbaceous wetland perennial, to facilitate studies of mating patterns and population genetic structure. • Methods and Results: A total of 42 polymorphic loci were identified from a sample of 24 individuals from a single population in Ohio, USA. The number of alleles per locus ranged from two to nine, and median observed heterozygosity was 0.435. • Conclusions: This large number of polymorphic loci will enable researchers to quantify male fitness, patterns of multiple paternity, selfing, and biparental inbreeding in large natural populations of this species. These markers will also permit detailed study of fine-scale patterns of genetic structure.     

Characterization of 12 polymorphic microsatellite markers for a facultatively eusocial sweat bee (Megalopta genalis)

We developed a library of twelve polymorphic di- and tri-nucleotide microsatellite markers for Megalopta genalis, a facultatively eusocial sweat bee. We tested each locus in a panel of 23 unrelated females and found 7-20 alleles per locus. Observed and expected heterozygosities ranged from 0.65 to 0.96 and from 0.69 to 0.95 respectively. None of the loci deviated from Hardy-Weinberg equilibrium proportions or was found to be in gametic disequilibrium.     

Development of microsatellite markers in white birch (Betula platyphylla var. japonica)

Betula platyphylla var. japonica is a typical pioneer tree species in the secondary succession in northern Japan. We describe the cloning and characterization of 13 polymorphic, codominant microsatellite loci isolated from this species. These polymorphic loci had 2–8 alleles per locus and a range of expected heterozygosities from 0.050 to 0.808.     

Development and mapping of SSR markers for maize

Microsatellite or simple sequence repeat (SSR) markers have wide applicability for genetic analysis in crop plant improvement strategies. The objectives of this project were to isolate, characterize, and map a comprehensive set of SSR markers for maize (Zea mays L.). We developed 1051 novel SSR markers for maize from microsatellite-enriched libraries and by identification of microsatellite-containing sequences in public and private databases. Three mapping populations were used to derive map positions for 978 of these markers. The main mapping population was the intermated B73 × Mo17 (IBM) population. In mapping this intermated recombinant inbred line population, we have contributed to development of a new high-resolution map resource for maize. The primer sequences, original sequence sources, data on polymorphisms across 11 inbred lines, and map positions have been integrated with information on other public SSR markers and released through MaizeDB at URL:www.agron.missouri.edu. The maize research community now has the most detailed and comprehensive SSR marker set of any plant species.     

Development of microsatellite DNA markers of silver carp (Hypophthalmichthys molitrix) and their cross‐species application in bighead carp (Aristichthys nobilis)

Forty‐four microsatellite DNA markers were developed for silver carp, and used to investigate polymorphisms of 41 wild silver carps and seven wild bighead carps collected from Jingzhou fragment of Yangtze River. In silver carp, 40 markers were polymorphic. A total of 297 alleles were detected at 40 polymorphic loci. The number of alleles per locus varied from two to 16 with an average of 7.4 and the expected heterozygosities of each locus ranged from 0.07 to 0.91 with an average of 0.69. All markers amplified both silver carp and bighead carp DNAs.     

Development of polymorphic microsatellite markers in sesame (Sesamum indicum L.)

Fifty microsatellite sequences (SSRs) were isolated from an enriched library of sesame (Sesamum indicum L.) using a modified protocol. After screening, 10 polymorphic microsatellites were used to determine their usefulness in diversity analysis among 16 sesame accessions. The number of alleles ranged from three to six alleles per locus with an average of 4.6 alleles. The fragment size varied from 150 bp to 307 bp. Expected heterozygosites (H_E) and polymorphism information contents (PICs) ranged from 0.437 to 0.858 and 0.34 to 0.80, respectively, which indicates the highly informative nature of the microsatellites reported here. These microsatellite markers will be very useful in diversity analysis among a large germplasm collection of sesame present in our Korean gene bank and also in the establishment of its core collection.