Hello fellow Xenopus Researchers,
The EXRC team hopes you are all well and that your experiments are being successful.
First the good news, the EXRC core funding grant application was successful in a dreadfully competitive round and BBSRC now supports your centre for the next three years (until August 2026). It does so alone since the Wellcome Trust no longer supports Resources. This has necessitated us proposing a new cost recovery structure to the BBSRC, which together with significant inflation, has meant that the costs of resources were increased from September 1 this year.
Individual prices are available on our website but the overall agreement with BBSRC is that UK-based academic users pay cost, non-UK academic users cost +50% and all non-academic users cost +300%.
The pricing for embryos is more complex as we realised how much work is required to produce a satisfactory batch of eggs for shipping. For a full OECD assay using embryos, we need to inject seven females and the whole process requires half a day of work for one of our technicians.
Please bear in mind that prices have not changed in the last 5 years and that we now have to recover all of the consumables costs for the centre from user income.
Frog and frog “by-products” shipments
We are now sending frogs and frog “by-products” (officially known as animal by-products or ABPs) regularly to mainland Europe although the paperwork remains “challenging”.
Below is a list of countries we have supplied our resources to in 2023:
United Arab Emirates
We have also received enquiries from Kuwait, Uruguay and Argentina, which show continuous and growing interest in using Xenopus as a model organism.
Cut-off date for animal by-product deliveries during Christmas period
In line with our commitment to ethical considerations and recognising the fragile nature of the samples, we recently communicated our decision to implement a cut-off date for sending any animal by-products.
The cut-off date for shipping samples before Christmas is 6th December (Wednesday). After this date, deliveries become increasingly unreliable due to the holiday season’s impact on logistics and transport services, therefore we will not be supplying any resources unless you are willing to collect them in person from our facility in Portsmouth, UK.
Please be advised that our shipping services are scheduled to resume on the week commencing 8th January. To ensure that your requirements are met promptly, we strongly encourage you to pre-book any necessary samples for that week as soon as possible as we may not be able to fulfil all requests.
We understand the importance of our services to your operations and aim to provide the best possible support. Thank you for your understanding and cooperation.
In summary, the EXRC has almost completed the process of expansion and is up and running normally again.
We are happy to take in new lines of frogs so if you have lines that are not yet deposited, please contact us to arrange collection – we can hold them “invisible” until they are published.
Please remember it is your centre and we run it to support your research, so it is critical that we understand your needs. Therefore, please do not hesitate to contact us if you need to discuss any requirements or require any assistance.
Live frogs are generally available so we can accommodate more requests than we were previously able to. The centre is being heavily used though, which we are thrilled about, so any prior notice you can give regarding your requirements would be appreciated.
20th International Xenopus Conference
We are proud to announce that the EXRC will host the next International Xenopus Conference in Portsmouth in 2025.
Save the Date: 17-21 August 2025 (Sunday to Thursday)
To keep this conference as accessible as possible, we will be offering different packages, which will include accommodation at the University of Portsmouth.
Xenopus welfare meeting in London
We are currently in the process of co-organising a Xenopus welfare meeting in London in the first week of June 2024. More information will follow nearer the time.
List of new transgenic lines
For transgenic lines the availability varies a lot so please contact us on EXRC@xenopusresource.org. If you need a knockout or transgenic line made, we are now able to take orders again.
We are very happy to have a number of new lines submitted from Elly Tanaka’s group (thank you!). These are:
Xla.Tg(CAG:eGFP,mCherry)Tanaka : When mated with CreER transgenic lines, the CreER/loxP-double-positive offspring will express mCherry in the cells where the recombination of loxP sites occurs upon 4OHT treatment. Made using REMI. Lin, T.Y., Gerber, T. et al., Dev Cell (2021), PMID: 34004152.
Xla.Tg(CAG:mTFP1-nls)Tanaka : Fluorescence signal all over the animal could be observed under CFP or GFP channel. The fluorescent signal is the most obvious in the muscle tissues of tail or froglet legs. Fluorescent puncta could be observed in the tail under high magnification. Made using REMI. Lin, T.Y., Gerber, T. et al., Dev Cell (2021), PMID: 34004152.
Xla.Tg(prrx1s:prrx1s*-T2A-mCherry)Tanaka : The plasmid contained an X. laevis prrx1.S cDNA fused with a T2A-mCherry-b-globin poly A signal cassette directly downstream. The plasmid was injected into fertilized X. laevis embryos together with Cas9 protein and a gRNA (5’-CCAGTCTGGACAATTTAC-3’) targeted at the 5’ end of the prrx1 cDNA sequence. The result was an integration of the prrx1.ScDNA-T2A-mCherry 75 nucleotides downstream of the start codon followed by a 12-nt in-frame deletion. The best way to find the positive animals is to find the mCherry fluorescence in the mesenchyme of stage 49-51 limb buds. CRISPR/Cas9-mediated knock-in.
Xla.Tg(cryg.1:mCherry;Mmu.Prrx1:TFPnls,Cre-ERT2)Tanaka : A plasmid containing a mouse Prrx1 promoter directly upstream nuclear TFP (TFPnls) and a Cre-ERT2 (CreER) fusionprotein. A self-cleaving 2A peptide sequence was placed between the TFPnls and the CreER sequences. A secondary cassette containing an mCherry sequence driven by the X. laevis gamma-crystallin 1 (cryg1) promoter was cloned upstream of the Mmu.Prrx1:TFPnls,CreER cassette in the opposite direction. An unambiguous red fluorescence in the lens can be observed from 7-8 days after hatching, while the rest of the body should be red-fluorescence negative. When mated with the loxP reporter line(Xla.Tg.(CAG:eGFP,mCherry), the CreER-/loxP-double-positive tadpoles will express mCherry in the limb mesenchyme after 4OHT treatment. The mCherry signal could also be observed in the brain region. A very weak teal fluorescence signal could be found in the stage 50-52 limb bud. Made by REMI. Dev Growth Differ. 64(5):243-253.
Xla.Tg(CAG:mCherry)Tanaka : Fluorescence signals all over the animal could be observed under the RFP channel. The fluorescent signal is the most obvious in the muscle tissues of tail or froglet legs. Lin, T.Y., Gerber, T. et al., Dev Cell (2021), PMID: 34004152.
Xla.Tg(CAG:TFPnls,ERT2-Cre-ERT2;CAG:mCherry)Tanaka : Two plasmids were co-injected in the REMI transgenesis protocol. 1) a CAG promoter upstream of the DNA sequences of a nuclear TFP (TFPnls) and a ERT2-Cre-ERT2 (ERCreER) fusion protein with a self-cleaving 2A sequence between the TFPnls and the ERCreER sequences. 2) a CAG promoter directly upstream of a loxP-floxed cassette. The first position of the cassette is a stop codon series (TAATTAATTAA) with a triple SV40 polyA sequence. The second position is mCherry with a rabbit beta-globin polyA sequence. There is a nuclear blue-green signal all over the body. The fluorescent nuclei are most obvious in the tail. It is best to screen the animals at tadpole stages. Dev Growth Differ. 64(5):243-253.
If you need these lines in the next 12 months please tell us now since this will dictate how we breed and freeze down the lines.
Transport of amphibia and amphibian products essential for biomedical research from the UK to EU countries.
We can now apply for an Export Health certificate (EHC) specifically for amphibia for the following countries:
● Czech Republic
● Northern Ireland
All shipments that require an EHC will likely incur an additional fee (£404) due to the mandatory requirement for the official vet’s signature. No document can be signed by the official vet (OV) unless it has been issued by the UK government.
All shipments of live animals and animal by-products outside of the UK must be accompanied by a commercial invoice specifying the Harmonised Tariff Code (HS), which classifies the commodity sent. Those we use are:
Recommended commodity code
You should however check that these are suitable for your transport needs before using them.
Animal by-product shipments are booked with our trusted courier Express International which uses Fedex (or DHL on request) to fulfil the international part of the delivery.