scholarly journals Linkage and mapping analyses of the no glue egg gene Ng in the silkworm (Bombyx mori L.) using simple sequence repeats (SSR) markers

2011 ◽  
Vol 10 (47) ◽  
pp. 9549-9556 ◽  
Author(s):  
Zhao Xiao ming ◽  
Wei Guo qing ◽  
Liu Chao liang ◽  
Zou Chang rui ◽  
Zhu Bao jian
Genome ◽  
2005 ◽  
Vol 48 (5) ◽  
pp. 802-810 ◽  
Author(s):  
Muwang Li ◽  
Li Shen ◽  
Anying Xu ◽  
Xuexia Miao ◽  
Chengxiang Hou ◽  
...  

To determine genetic relationships among strains of silkworm, Bombyx mori L., 31 strains with different origins, number of generations per year, number of molts per generation, and morphological characters were studied using simple sequence repeat (SSR) markers. Twenty-six primer pairs flanking microsatellite sequences in the silkworm genome were assayed. All were polymorphic and unambiguously separated silkworm strains from each other. A total of 188 alleles were detected with a mean value of 7.2 alleles/locus (range 2–17). The average heterozygosity value for each SSR locus ranged from 0 to 0.60, and the highest one was 0.96 (Fl0516 in 4013). The mean polymorphism index content (PIC) was 0.66 (range 0.12–0.89). Unweighted pair group method with arithmetic means (UPGMA) cluster analysis of Nei's genetic distance grouped silkworm strains based on their origin. Seven major ecotypic silkworm groups were analyzed. Principal components analysis (PCA) for SSR data support their UPGMA clustering. The results indicated that SSR markers are an efficient tool for fingerprinting cultivars and conducting genetic-diversity studies in the silkworm.Key words: silkworm, Bombyx mori L., microsatellites, simple sequence repeat (SSR), genetic diversity.


Genome ◽  
2006 ◽  
Vol 49 (4) ◽  
pp. 397-402 ◽  
Author(s):  
Muwang Li ◽  
Qiuhong Guo ◽  
Chengxiang Hou ◽  
Xuexia Miao ◽  
Anying Xu ◽  
...  

In the silkworm Bombyx mori, non-susceptibility to the Zhenjiang (China) strain of the densonucleosis virus (DNV-Z) is controlled by the recessive gene nsd-Z (non-susceptible to DNV-Z), which is located on chromosome 15. Owing to a lack of crossing over in females, reciprocal backcrossed F1 (BC1) progeny were used for linkage analysis and mapping of the nsd-Z gene using silkworm strains Js and L10, which are classified as being highly susceptible and non-susceptible to DNV-Z, respectively. BC1 larvae were inoculated with the DNV-Z virus at the first instar, and DNA was extracted from the individual surviving pupae and analyzed for simple sequence repeat (SSR) markers. The nsd-Z gene was found to be linked to 7 SSR markers, as all the surviving larvae in the BC1♀ (F1♀ × L10♂) showed the homozygous profile of strain L10, and the sick larvae in the BC1♀ (F1♀ × L10♂) showed the heterozygous profile of Js × L10 F1 hybrids. Using a reciprocal BC1♂ (L101♀ × F1♂) cross, we constructed a linkage map of 80.6 cM, with nsd-Z mapped at 30 cM and the closest SSR marker at a distance of 4.4 cM.Key words: SSR markers, densonucleosis virus, non-susceptible gene, silkworm, Bombyx mori.


2008 ◽  
Vol 90 (2) ◽  
pp. 151-156 ◽  
Author(s):  
XUE-XIA MIAO ◽  
WEI-HUA LI ◽  
MU-WANG LI ◽  
YUN-PO ZHAO ◽  
XIAN-RU GUO ◽  
...  

SummaryMicrosatellites or simple sequence repeats (SSRs) are co-dominant molecular markers. When we used fluorescent SSR markers to construct a linkage map for the female heterogametic silkworm (Bombyx mori, ZW), we found that some loci did not segregate in a Mendelian ratio of 1:1 in a backcross population. These loci segregated in a 3:1 ratio of single bands compared with double bands. Further examination of band patterns indicated that three types of SSR bands were present: two homozygotes and one heterozygote. In the beginning, we considered to discard these markers. By scoring male and female F1 individuals, we confirmed that these loci were located on the Z chromosome. Using the sex-linked visible mutation sch (K05) and its wild-type (C108), we constructed an F1 male backcross (BC1M) mapping population. The combination of sch backcross and SSR data enabled us to map the SSR markers to the Z chromosome. By adjusting input parameters based on these data, we were able to use Mapmaker software to construct a linkage map. This strategy takes advantage of co-dominant markers for positional cloning of genes on the Z chromosome. We localized sch to the Z chromosome relative to six SSR markers and one PCR marker, covering a total of 76·1 cM. The sch mutation is an important sex-linked visible mutation widely used in breeding of commercial silkworms (e.g. male silkworm selection rearing). Localization of the sch gene may prove helpful in cloning the gene and developing strains for marker-assisted selection in silkworm breeding.


1964 ◽  
Vol 10 (2) ◽  
pp. 225-238 ◽  
Author(s):  
Toshio Ito ◽  
Kenya Kawashima ◽  
Motoko Nakahara ◽  
Koji Nakanishi ◽  
Akira Terahara

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