BAC (Bacterial Artificial Chromosome) libraries are a compilation of vectors carrying segments of DNA which make up the whole genome. These have been created to aid the sequencing of the genome by breaking it up into manageable pieces. BAC clones carry bacterial DNA of up to 200 000 bp that can be identified and copied within the cell. These fragments of the genome can be easily sequenced and aligned to make up the complete genome and manipulated for BAC transgenesis.
To be able to isolate and re-identify these DNA segments when aligning them to form a complete genome, the starting DNA sequences need to be as similar as possible. For Xla, the J-Line was created by inbreeding single pairs of frogs initially for 21 generations. The homozygosity of the J-line was tested by skin transplants. After the 11th generation the frogs showed no “short-term skin rejection”, and after the 21st generation they showed no “long-term skin rejection”. This indicates that most of the genes were homozygous. These animals were bred for a further 11-13 generations and used as starting material from the construction of BAC and Fosmid libraries, FISH analysis and RNA-seq. The J-Line frogs were distributed from Japan to USA and UK, and are now available to the community via us or the NXR (37th generation). (Gantress, et al 2003; Robert and Ohta, 2009; Tochinai and Katagiri, 1975)
At the EXRC we hold two BAC libraries: Xla from the Institute for Amphibian Biology, Hiroshima University; and Xtr library from the Department of Biology, University of Virginia.
BAC clones are stored on 384 well plates. The clone number indicates the plate number and its position in each plate as follows (PLEASE PROVIDE US WITH THIS INFORMATION WHEN ORDERING):
(example) XLB1-277N11 –
Plate number: 277
Guidelines on how to access BAC and Fosmid information on Xenbase can be found here.
BAC clones will be shipped as agar stabs. For more informatiohttps://xenopusresource.org/wp-content/uploads/2017/12/Accessing-and-Ordering-BACs-2017.pdfn about agar stabs please visit this page.
For more information please follow the links below:
- Xenopus laevis J-Line genome sequencing and assembly – BioProject Accession: PRJNA313213 https://www.ncbi.nlm.nih.gov/bioproject?term=313213
- Nucleotide data https://www.ncbi.nlm.nih.gov/nuccore?term=313213%5BBioProject%5D
- BAC mapping on Xenbase genome browser http://gbrowse.xenbase.org/fgb2/gbrowse/xl9_1/
- BAC mapping on NIG (National Institute of Genetics, Japan) genome browser https://xenopus.lab.nig.ac.jp/cgi-bin/gb2/gbrowse/xl_v9_1m_p/
- Genome evolution in the allotetraploid frog Xenopus laevis http://www.nature.com/doifinder/10.1038/nature19840
- Supplementary information for the above paper https://images.nature.com/original/nature-assets/nature/journal/v538/n7625/extref/nature19840-s1.pdf