Ligation sequencing V14 — single-cell transcriptomics with 3' cDNA prepared using 10X Genomics on PromethION (SQK-LSK114)

概览

Single-cell transcriptomics method:

  • Requires cDNA amplicons produced using the 10X Genomics Next GEM Single Cell 3' Kit (V3.1)
  • Library preparation time ~205 minutes
  • High output
  • PCR required

For Research Use Only

Document version: SST_9198_v114_revH_06Dec2023

1. Overview of the protocol

Introduction to the single-cell 3' transcriptomics protocol

This application allows the sequencing of full-length 3' cDNA transcripts, which provides a complete view of the expressed isoforms and allows detection of alternative splicing and fusion events in individual cells. Additionally, it enables the detection of SNPs anywhere in the transcript, as well as identification of cell sub-types in a population based on isoform expression levels.

This protocol describes how to carry out sequencing of cDNA from single cells using the Ligation Sequencing Kit V14 (SQK-LSK114) and the PCR Expansion (EXP-PCA001). You will need to have reverse-transcribed single-cell mRNA into cDNA using the 10X Genomics Next GEM Single Cell 3' Kit (V3.1) to then biotin tag your cDNA before PCR amplification with custom-ordered oligos. Next, pull-down of the amplicons on streptavidin beads is performed before a second PCR using the PCR Primers (PRM). Finally, a standard Ligation Sequencing Kit V14 library preparation is completed to prepare the cDNA ends for sequencing on a PromethION device.

This is an optimised protocol adapted from Lebrigand, K., Magnone, V., Barbry, P. et al. High throughput error corrected Nanopore single cell transcriptome sequencing. Nat Commun 11, 4025 (2020) to sequence full-length transcripts, deplete cDNA synthesis artifacts and to correct for strand bias.

Note: This protocol is compatible and fully supported with the 10X Genomics Next GEM Single Cell 3' Kit (V3.1) and the Visium Spatial Gene Expression Kit (V1). Other versions of the kits are not supported.
For the 10X Genomics Next GEM Single Cell 5' Kit (V2), please visit our Ligation sequencing V14 - Single-cell transcriptomics with 5' cDNA prepared using 10X Genomics on PromethION (SQK-LSK114) protocol.

Steps in the sequencing workflow:

Prepare for your experiment

You will need to:

  • Have previously prepared single-cell barcoded cDNA using the 10X Genomics Next GEM Single Cell 3' Kit (V3.1). The quality checks performed during the protocol are essential in ensuring experimental success.
  • Ensure you have your sequencing kit, the correct equipment and third-party reagents.
  • Download the MinKNOW software for acquiring and analysing your data.
  • Perform a flow cell check to ensure it has enough pores for a good sequencing run.

Library preparation
Protocol step Process Time Stop option
Pre-pull down PCR Biotin tag your cDNA and amplify by PCR 60 minutes -
Pull-down Pull-down the amplicons on streptavidin beads 40 minutes -
Post-pull-down PCR Amplify the amplicons by PCR with PCR Primers (PRM) 50 minutes -
End-prep Prepare the cDNA ends for adapter attachment 30 minutes 4°C overnight
Adapter ligation and clean-up Attach sequencing adapters to the cDNA 20 minutes 4°C for short-term storage or for repeated use, such as for reloading your flow cell
–80°C for long-term storage
Priming and loading the flow cell Prime the flow cell and load the prepared library for sequencing 5 minutes

Sequencing and analysis

You will need to:

  • Start a sequencing run using the MinKNOW software, which will collect raw data from the device and basecall the reads.
  • Analyse the data using the EPI2ME wf-single-cell pipeline.
重要

Compatibility of this protocol

This protocol should only be used in combination with:

  • Ligation Sequencing Kit V14 (SQK-LSK114)
  • PCR Expansion (EXP-PCA001)
  • R10.4.1 flow cells (FLO-PRO114M)
  • Flow Cell Wash Kit (EXP-WSH004)
  • PromethION device - PromethION IT Requirements document

2. Equipment and consumables

材料
  • 10 ng of cDNA amplicons prepared using 10X Genomics Next GEM Single Cell 3' Kits (V3.1)
  • Custom-ordered oligo at 10 μM: [Btn]Fwd_3580_partial_read1_defined_for_3'_cDNA (sequence provided below)
  • Custom-ordered oligo at 10 μM: Rev_PR2_partial_TSO_defined_for_3'_cDNA (sequence provided below)
  • Ligation Sequencing Kit V14 (SQK-LSK114)
  • PCR Expansion (EXP-PCA001)

耗材
  • PromethION Flow Cell (FLO-PRO114M)
  • LongAmp Hot Start Taq 2X Master Mix (NEB, M0533)
  • NEBNext® Ultra II 末端修复/ dA尾添加模块(NEB,E7546)
  • Salt-T4® DNA Ligase (NEB, M0467)
  • Qubit 1x dsDNA HS Assay(双链DNA高灵敏度检测)试剂盒(ThermoFisher,Q33230)
  • Agilent Technologies DNA 12000 Kit
  • M280 streptavidin, 10 μg/μl (Invitrogen, 11205D)
  • Agencourt AMPure XP beads (Beckman Coulter™, A63881)
  • 1 M Tris-HCl, pH 7.5
  • 5 M NaCl (Sigma, 71386)
  • 0.5 M EDTA, pH 8 (Thermo Scientific, R1021)
  • 新制备的80%乙醇(用无核酸酶水配制)
  • Nuclease-free water (e.g. ThermoFisher, AM9937)
  • 15 ml Falcon tubes
  • 1.5 ml Eppendorf DNA LoBind tubes
  • 0.2 ml thin-walled PCR tubes
  • Qubit™ 分析管(Invitrogen, Q32856)

仪器
  • PromethION 测序芯片遮光片
  • PromethION 测序设备
  • Agilent Bioanalyzer (or equivalent)
  • Hula混匀仪(低速旋转式混匀仪)
  • Magnetic rack (e.g. Invitrogen DynaMag-2 Magnet, Cat # 12321D)
  • 迷你离心机
  • 涡旋混匀仪
  • 热循环仪
  • P1000 移液枪和枪头
  • P200 移液枪和枪头
  • P100 移液枪和枪头
  • P20 移液枪和枪头
  • P10 移液枪和枪头
  • P2移液枪和枪头
  • 盛有冰的冰桶
  • 计时器
  • Qubit荧光计(或用于质控检测的等效仪器)

For this protocol, you will need 10 ng amplified cDNA amplicons prepared using 10X Genomics Next GEM Single Cell 3' Kits (V3.1).

重要

10X Genomics kits

Note: This protocol is compatible and fully supported with 10X Genomics Next GEM Single Cell 3' Kit (V3.1) and the Visium Spatial Gene Expression Kit (V1). Other versions of the kits are not supported.

The 10X Genomics Next GEM Single Cell 5' Kit (V2) is compatible with our Ligation sequencing V14 - Single-cell transcriptomics with 5' cDNA prepared using 10X Genomics on PromethION (SQK-LSK114) protocol.

Custom-ordered oligo sequences

Order the following HPLC-purified oligos at 100 μM, and dilute to 10 μM in TE buffer for use in the Pre-pull-down step of the library prep.

Name Sequence
[Btn]Fwd_3580_partial_read1_defined_for_3'_cDNA 5'-/5Biosg/CAGCACTTGCCTGTCGCTCTATCTTC
CTACACGACGCTCTTCCGATCT-3'
Rev_PR2_partial_TSO_defined_for_3'_cDNA 5'-CAGCTTTCTGTTGGTGCTGATATTGCAAGCAGTGGTA
TCAACGCAGAG-3'

AMPure XP beads

Extra AMPure XP Beads will be required for the first steps when preparing the cDNA amplicons. From the end-prep step, the AMPure XP Beads (AXP) from the Ligation Sequencing Kit V14 (SQK-LSK114) can be used.

起始DNA

DNA质控

选择符合质量和浓度要求的起始DNA至关重要的。使用过少或过多的DNA,或者质量较差的DNA(如,高度碎片化、含有RNA或化学污染物的DNA)都会影响文库制备。

有关如何对DNA样品进行质控,请参考起始DNA/RNA质控实验指南

化学污染物

从原始样本中提取DNA的方法不同,可能会导致经纯化的DNA中所残留的化学污染物不同。这会影响文库的制备效率和测序质量。请在牛津纳米孔社区的 Contaminants(污染物)页面 了解更多信息。

第三方试剂

Oxford Nanopore Technologies推荐您使用本实验指南中提及的所有第三方试剂,并已对其加以验证。我们尚未对其它替代试剂进行测试。

我们建议您按制造商说明准备待用的第三方试剂.

测序芯片质检

我们强烈建议您在开始测序实验前,对测序芯片的活性纳米孔数进行质检。质检需在您收到MinION /GridION /PremethION测序芯片三个月之内进行,或者在您收到Flongle测序芯片四周内进行。Oxford Nanopore Technologies会对活性孔数量少于以下标准的芯片进行替换** :

测序芯片 芯片上的活性孔数确保不少于
Flongle 测序芯片 50
MinION/GridION 测序芯片 800
PromethION 测序芯片 5000

** 请注意:自收到之日起,芯片须一直贮存于Oxford Nanopore Technologies推荐的条件下。且质检结果须在质检后的两天内递交给我们。请您按照 测序芯片质检文档中的说明进行芯片质检。

PCR Expansion (EXP-PCA001) contents

Note: For this protocol, only PCR Primers (PRM) are required.

PCR expansion pack

连接测序试剂盒V14(SQK-LSK114)内容物

请注意: 我们正在将部分试剂的包装形式由单次管装改为瓶装。

单次管装试剂: SQK-LSK114 v2

部分试剂改为瓶装: SQK-LSK114 v3

声明: 本产品包含由贝克曼库尔特公司(Beckman Coulter, Inc)生产的 AMPure XP 试剂,并可与试剂盒一起于-20°C 下储存(试剂稳定性将不受损害)。

请注意: DNA参照(DCS)是一段可比对到Lambda基因组的3'端、长度为3.6 kb 的标准扩增子。

3. Pre-pull-down PCR

材料
  • 10 ng of cDNA amplicons prepared using 10X Genomics Next GEM Single Cell 3' Kits (V3.1)
  • Custom ordered-oligo at 10 μM: [Btn]Fwd_3580_partial_read1_defined_for_3'_cDNA (sequence provided in Equipment and Consumables)
  • Custom-ordered oligo at 10 μM: Rev_PR2_partial_TSO_defined_for_3'_cDNA (sequence provided in Equipment and Consumables)

耗材
  • LongAmp Hot Start Taq 2X Master Mix (NEB, M0533)
  • Agencourt AMPure XP beads (Beckman Coulter™ cat # A63881)
  • 新制备的80%乙醇(用无核酸酶水配制)
  • Nuclease-free water (e.g. ThermoFisher, cat #AM9937)
  • 1.5 ml Eppendorf DNA LoBind 离心管
  • 0.2 ml thin-walled PCR tubes

仪器
  • 热循环仪
  • 迷你离心机
  • Hula混匀仪(低速旋转式混匀仪)
  • Magnetic rack (e.g. Invitrogen DynaMag-2 Magnet, Cat # 12321D)
  • 盛有冰的冰桶
  • P1000移液枪和枪头
  • P200 移液枪和枪头
  • P100移液枪和枪头
  • P20 pipette and tips
  • P2 移液枪和枪头
CHECKPOINT

测序芯片质检

我们强烈建议您在开始文库制备前,对测序芯片的活性纳米孔数进行质检,以确保测序实验顺利运行。

详情请参阅 MinKNOW 实验指南中的 测序芯片质检说明

Prepare the cDNA amplicons in nuclease-free water:

  • Transfer 10 ng of cDNA amplicons into a 0.2 ml thin-walled PCR tube.
  • Adjust the volume to 21 µl with nuclease-free water.
  • Mix thoroughly by flicking the tube to avoid unwanted shearing.
  • Spin down briefly in a microfuge.

In the same 0.2 ml thin-walled PCR tube, set up the following biotin tagging reaction:

Reagent Stock Final Volume
cDNA template 0.48 ng/μl 0.2 ng/μl 21 μl
[Btn]Fwd_3580_partial_read1_defined_for_3'_cDNA 10 μM 0.4 μM 2 μl
Rev_PR2_partial_TSO_defined_for_3'_cDNA 10 μM 0.4 μM 2 μl
LongAmp Hot Start Taq 2X Master Mix 2X 1X 25 μl
Total - - 50 μl

Mix by pipetting and spin down.

Amplify using the following cycling conditions:

Cycle step Temperature Ramp rate Time No. of cycles
Initial denaturation 94°C max 3 min 1
Denaturation

Annealing ramp-down

Annealing

Extension
94°C

66°C down to 58°C

58°C

65°C
max

0.2°C/s

max

max
30 sec

40 sec

50 sec

6 mins


4
Final extension 65°C max 10 min 1
Hold 4°C - -

Below is a schematic of the cycling conditions. image (1)

将样品转至干净的1.5 ml Eppendorf DNA LoBind 离心管中。

Resuspend the AMPure XP beads by vortexing.

Add 40 µl of resuspended AMPure XP beads to the reaction and mix by flicking the tube.

将离心管置于Hula混匀仪(低速旋转式混匀仪)上室温孵育5分钟。

准备500μl新制备的80%乙醇(用无核酸酶水配制)。

将样品瞬时离心,并静置于磁力架上待磁珠和液相分离。保持离心管在磁力架上不动,用移液枪吸去清液。

Keep the tube on the magnet and wash the beads with 200 µl of freshly prepared 80% ethanol in nuclease-free water without disturbing the pellet. Remove the ethanol using a pipette and discard.

Repeat the previous step.

Briefly spin down and place the tubes back on the magnet. Pipette off any residual ethanol. Allow to dry for 30 seconds, but do not dry the pellet to the point of cracking.

Remove the tube from the magnetic rack and resuspend the pellet in 10 µl nuclease-free water. Spin down and incubate for 2 minutes at room temperature.

Pellet the beads on a magnet until the eluate is clear and colourless.

Remove and retain 10 µl of eluate into a clean 1.5 ml Eppendorf DNA LoBind tube.

步骤结束

Take forwards 10 µl of biotinylated cDNA into the pull-down step.

4. Pull-down

材料
  • 10 μl of biotinylated cDNA

耗材
  • 1 M Tris-HCl, pH 7.5
  • 5 M NaCl (Sigma, 71386)
  • 0.5 M EDTA, pH 8 (Thermo Scientific, R1021)
  • M280 streptavidin, 10 μg/μl (Invitrogen, 11205D)
  • 无核酸酶水(如ThermoFisher,AM9937)
  • 15 ml Falcon tubes
  • 1.5 ml Eppendorf DNA LoBind 离心管
  • 0.2 ml thin-walled PCR tubes

仪器
  • Vortex mixer
  • 迷你离心机
  • Hula混匀仪(低速旋转式混匀仪)
  • Magnetic rack (e.g. Invitrogen DynaMag-2 Magnet, Cat # 12321D)
  • 盛有冰的冰桶
  • P1000移液枪和枪头
  • P200 移液枪和枪头
  • P100移液枪和枪头
  • P20 pipette and tips
  • P2 移液枪和枪头

Prepare 200 μl of 10 mM Tris-HCl pH 7.5 for later use.

Prepare 4 ml of 2X wash/bind buffer (10 mM Tris-HCl pH 7.5, 2 M NaCl, 1 mM EDTA).

Reagent Stock concentration Final concentration Volume
Tris-HCl pH 7.5 1 M 10 mM 40 μl
NaCl 5 M 2 M 1600 μl
EDTA 0.5 M 1 mM 8 μl
Nuclease-free water - - 2352 μl
Total - - 4000 μl

Transfer 3.5 ml of 2X wash/bind buffer (5 mM Tris-HCl pH 7.5, 1 M NaCl, 0.5 mM EDTA) to a clean 15 ml Falcon tube.

Add 3.5 ml of nuclease-free water to the same 15 ml Falcon tube to make 7 ml of 1X wash/bind buffer.

Resuspend the M280 streptavidin beads (10 μg/μl) by vortexing.

Transfer 5 μl of the streptavidin beads to a clean 1.5 ml Eppendorf DNA LoBind tube.

Add 1 ml of 1X wash/bind buffer and vortex the beads with buffer for 5 seconds.

Spin down the tube and pellet the beads on a magnet for two minutes, then pipette off the supernatant.

Repeat steps 7 and 8 two more times for a total of three washes.

重要

It is critical that 2X buffer is used for the next step. Using 1X buffer will result in inefficient binding.

Resuspend the beads in 10 μl of 2X wash/bind buffer to achieve a final bead concentration of 5 μg/μl.

Add 10 μl of 5 μg/μl prepared beads (50 μg beads total) to the tube with 10 μl of biotinylated cDNA.

Incubate on a Hula mixer (rotator mixer) for 20 minutes at room temperature.

重要

In the next steps, it is critical to pellet the beads on the magnet for the specified timings to ensure none are left in solution as the beads are difficult to see.

Add 1 ml of 1X wash/bind buffer and vortex the DNA and beads with buffer for 5 seconds.

Spin down the tube and pellet the beads on a magnet for three minutes, then pipette off the supernatant. Take care to not aspirate any of the beads.

Repeat the steps 13 and 14 two more times for a total of three washes.

Add 200 μl of 10 mM Tris-HCl pH 7.5 and vortex the beads for 5 seconds.

Spin down and place the tube back on the magnet for three minutes. Pipette off the supernatant.

Remove the tube from the magnetic rack and resuspend the pellet in 20 μl of nuclease-free water.

Vortex for 5 seconds and briefly spin down to collect the amplicon-bead conjugate.

步骤结束

Take forwards 20 μl of the amplicon-bead conjugate into the post-pull-down PCR step.

5. Post-pull-down PCR

材料
  • 20 μl of the amplicon-bead conjugate
  • PCR Primers (PRM)

耗材
  • LongAmp Hot Start Taq 2X Master Mix (NEB, M0533)
  • Agencourt AMPure XP beads (Beckman Coulter™ cat # A63881)
  • Qubit 1x dsDNA HS Assay(双链DNA高灵敏度检测)试剂盒(ThermoFisher,Q33230)
  • Agilent Technologies DNA 12000 Kit
  • 新制备的80%乙醇(用无核酸酶水配制)
  • Nuclease-free water (e.g. ThermoFisher, cat #AM9937)
  • 0.2 ml thin-walled PCR tubes
  • 1.5 ml Eppendorf DNA LoBind 离心管
  • Qubit™ 分析管(Invitrogen, Q32856)

仪器
  • 热循环仪
  • Vortex mixer
  • Hula混匀仪(低速旋转式混匀仪)
  • Magnetic rack (e.g. Invitrogen DynaMag-2 Magnet, Cat # 12321D)
  • 迷你离心机
  • 盛有冰的冰桶
  • P1000 移液枪和枪头
  • P200 移液枪和枪头
  • P100移液枪和枪头
  • P20 移液枪和枪头
  • P10 移液枪和枪头
  • P2移液枪和枪头
  • Qubit荧光计(或用于质控检测的等效仪器)
可选仪器
  • Agilent Bioanalyzer (or equivalent)

Thaw the PCR Primers (PRM) at room temperature, then spin down and place on ice.

In a 0.2 ml thin-walled PCR tube, prepare the following PCR reaction:

Reagent Stock Final Volume
PCR Primer (PRM) 10 μM 0.2 μM 1 μl
Nuclease-free water - - 4 μl
LongAmp Hot Start Taq 2X Master Mix 2X 1X 25 μl
Total - - 30 μl

吹打混匀。

Resuspend the amplicon-bead conjugate by pipetting and then transfer 20 μl of the conjugate into the 0.2 ml thin-walled PCR tube containing the PCR reaction. Mix by pipetting.

重要

Do not allow the amplicon-bead conjugate to precipitate or pellet before transferring to the thermal cylcer.

Avoid leaving the amplicon-bead conjugate standing for long before transferring to the thermal cycler.

Ensure you DO NOT spin down or centrifuge the amplicon-bead conjugate.

Do not spin down the tube; transfer immediately to the thermal cycler and amplify using the following cycling conditions:

Cycle step Temperature Time No. of cycles
Initial denaturation 94°C 3 min 1
Denaturation

Annealing

Extension
94°C

56°C

65°C
15 sec

15 sec

6 min


4
Final extension 65°C 10 min 1
Hold 4°C -

Resuspend the AMPure XP beads by vortexing.

将样品转至干净的1.5 ml Eppendorf DNA LoBind 离心管中。

Add 40 µl of resuspended AMPure XP beads to the reaction and mix by flicking the tube.

将离心管置于Hula混匀仪(低速旋转式混匀仪)上室温孵育5分钟。

准备500μl新制备的80%乙醇(用无核酸酶水配制)。

将样品瞬时离心,并静置于磁力架上待磁珠和液相分离。保持离心管在磁力架上不动,用移液枪吸去清液。

Keep the tube on the magnet and wash the beads with 200 µl of freshly prepared 80% ethanol in nuclease-free water without disturbing the pellet. Remove the ethanol using a pipette and discard.

Repeat the previous step.

将离心管瞬时离心后置于磁力架上。用移液枪吸走残留的乙醇。让磁珠在空气中干燥30秒,但不要干至表面开裂。

Remove the tube from the magnetic rack and resuspend the pellet in 15 µl nuclease-free water.

Pellet the beads on the magnet until the eluate is clear and colourless.

Remove and retain 15 µl of eluate into a clean 1.5 ml Eppendorf DNA LoBind tube.

Dispose of the pelleted beads

Quantify 1 µl of eluted sample using a Qubit fluorometer - recovery aim >50 ng total.

Quantify 200 fmol of cDNA from the average fragment size identified using an Agilent Bioanalyzer.

Alternatively, assume an average fragment size of 1 kbp.

3- post PCR Frag analyser

Figure: Example amplicon fragment length distribution: 3 biological replicates of 3' cDNA from PBMCs prepared using the 10x genomics 3' gene expression v3.1 kit, processed using the Oxford Nanopore Technologies 3' 10x cDNA protocol. Here the amplicons have been analysed using the Agilent Bioanalyzer 2100 and DNA 12000 kit.

步骤结束

Take forwards 200 fmol of cDNA into the end-prep step.

6. DNA修复和末端制备 (4)

材料
  • 200 fmol cDNA amplicons
  • AMPure XP 磁珠(AXP)

耗材
  • NEBNext® Ultra II End Prep Enzyme Mix from NEBNext® Ultra II End Repair Module (NEB, E7546)
  • NEBNext® Ultra II End Prep Reaction Buffer from NEBNext® Ultra II End Repair Module (NEB, E7546)
  • Qubit dsDNA HS Assay(双链DNA高灵敏度检测)试剂盒(Invitrogen, Q32851)
  • 无核酸酶水(如ThermoFisher,AM9937)
  • 新制备的80%乙醇(用无核酸酶水配制)
  • 0.2 ml薄壁PCR管
  • 1.5 ml Eppendorf DNA LoBind 离心管
  • Qubit™ 分析管(Invitrogen, Q32856)

仪器
  • P1000 移液枪和枪头
  • P100 移液枪和枪头
  • P10 移液枪和枪头
  • 热循环仪
  • 迷你离心机
  • Hula混匀仪(低速旋转式混匀仪)
  • 磁力架
  • 盛有冰的冰桶
  • Qubit荧光计(或用于质控检测的等效仪器)

Prepare the NEBNext Ultra II End Repair / dA-tailing Module reagents in accordance with manufacturer's instructions, and place on ice:

For optimal performance, NEB recommend the following:

  1. Thaw all reagents on ice.

  2. Ensure the reagents are well mixed.
    Note: Do not vortex the Ultra II End Prep Enzyme Mix.

  3. Always spin down tubes before opening for the first time each day.

  4. The NEBNext Ultra II End Prep Reaction Buffer may contain a white precipitate. If this occurs, allow the mixture(s) to come to room temperature and pipette the buffer several times to break up the precipitate, followed by a quick vortex to mix.

Transfer 200 fmol of cDNA amplicons into a clean 0.2 ml thin-walled PCR tube and adjust the volume to 50 µl with nuclease-free water.

In the same 0.2 ml thin-walled PCR tube, mix the following:

Between each addition, pipette mix 10-20 times.

Reagent Volume
cDNA amplicons 50 µl
Ultra II End-prep Reaction Buffer 7 µl
Ultra II End-prep Enzyme Mix 3 µl
Total 60 µl

轻轻吹打以充分混匀,并瞬时离心。

使用热循环仪,在20℃下孵育5分钟,然后在65℃下孵育5分钟。

将DNA样本转至干净的1.5 ml Eppendorf DNA LoBind离心管中。

涡旋振荡以重悬AMPure XP磁珠(AXP)。

将60µl重悬的AMPure XP磁珠(AXP)加入DNA末端修复反应体系中,轻弹试管以充分混合。

将离心管置于Hula混匀仪(低速旋转式混匀仪)上室温孵育5分钟。

准备500μl新制备的80%乙醇(用无核酸酶水配制)。

将样品瞬时离心,并静置于磁力架上待磁珠和液相分离。保持离心管在磁力架上不动,用移液枪吸去清液。

保持离心管在磁力架上不动,以200µl新鲜制备的80%乙醇洗涤磁珠。小心不要吹散磁珠。用移液枪将乙醇吸走并弃掉。

重复上述步骤。

将离心管瞬时离心后置于磁力架上。用移液枪吸走残留的乙醇。让磁珠在空气中干燥约30秒,但不要干至表面开裂。

将离心管从磁力架上移开。将磁珠重悬于61µl无核酸酶的水中。室温下孵育2分钟。

将离心管静置于磁力架上至少一分钟,直到磁珠和液相分离,且洗脱液澄清无色。

将61µl洗脱液转移至一支新的1.5ml Eppendorf DNA LoBind管中。

CHECKPOINT

取1µl洗脱样品,用Qubit荧光计定量。

步骤结束

经过末端修复的DNA可用于稍后的接头连接。如需要,您也可以此时将样品置于4℃储存过夜。

7. Adapter ligation and clean-up

材料
  • 连接接头(LA)
  • 连接测序试剂盒内的连接缓冲液(LNB)
  • 短片段缓冲液(SFB)
  • AMPure XP 磁珠(AXP)
  • Oxford Nanopore测序试剂盒中的洗脱缓冲液(EB)

耗材
  • Qubit dsDNA HS Assay(双链DNA高灵敏度检测)试剂盒(Invitrogen, Q32851)
  • 耐盐T4 DNA连接酶(NEB, M0467)
  • 1.5 ml Eppendorf DNA LoBind 离心管
  • Qubit™ 分析管(Invitrogen, Q32856)

仪器
  • 磁力架
  • Hula混匀仪(低速旋转式混匀仪)
  • 迷你离心机
  • 涡旋混匀仪
  • P1000 移液枪和枪头
  • P100 移液枪和枪头
  • P20 移液枪和枪头
  • P10 移液枪和枪头
  • Qubit荧光计(或用于质控检测的等效仪器)
提示

我们推荐您使用耐盐T4 DNA连接酶(NEB, M0467)。

耐盐 T4 DNA 连接酶(NEB,M0467)可单独购买,也包括在用于 Oxford Nanopore Technologies® 连接测序的 NEBNext® 配套模块 v2(货号 E7672S 或 E7672L)中。

虽然之前版本的 NEBNext® 配套模块(NEB,E7180S或E7180L)中的快速T4 DNA 连接酶(NEB,E6057)也可使用,但我们推荐的新试剂提供了更高的效率和更佳的连接效果。

重要

尽管第三方连接酶产品可能也附带缓冲液,但使用连接测序试剂盒中提供的连接缓冲液(LNB)时,连接接头(LA)的连接效率会更高。

瞬时离心连接接头(LA)和耐盐T4 DNA连接酶,置于冰上。

于室温下解冻连接缓冲液(LNB),解冻后瞬时离心,并用移液枪吹打混匀。该缓冲液的黏度较高,涡旋振荡会很难混匀。解冻并混匀后,请立即置于冰上。

将洗脱缓冲液(EB)于室温下解冻,涡旋振荡混匀后,再瞬时离心,置于冰上。

Thaw the Short Fragment Buffer (SFB) at room temperature and mix by vortexing. Then spin down and place on ice.

在一支1.5ml Eppendorf DNA LoBind离心管内,将所有试剂按以下顺序混合:

每添加一样试剂后,请吹打混匀10-20次,再添加下一样试剂。

试剂 体积
前一步骤所得DNA样品 60 µl
连接缓冲液(LNB) 25 µl
NEBNext快速T4 DNA连接酶 10 µl
连接接头(LA) 5 µl
总体积 100 µl

轻轻吹打以充分混匀,并瞬时离心。

室温下孵育10分钟。

涡旋振荡以重悬AMPure XP磁珠(AXP)。

将40µl 重悬的AMPure XP磁珠加入反应体系中,轻弹离心管以充分混合。

将离心管置于Hula混匀仪(低速旋转式混匀仪)上室温孵育5分钟。

将样品瞬时离心,并静置于磁力架上待磁珠和液相分离。保持离心管在磁力架上不动,用移液枪吸去上清液。

Wash the beads by adding 250 μl of Short Fragment Buffer (SFB). Flick the beads to resuspend, spin down, then return the tube to the magnetic rack and allow the beads to pellet. Remove the supernatant using a pipette and discard.

Note: Take care when removing the supernatant, the viscosity of the buffer can contribute to loss of beads from the pellet.

重复上述步骤。

将离心管瞬时离心后置于磁力架上。用移液枪吸走残留的上清液。让磁珠在空气中干燥约30秒,但不要干至表面开裂。

Remove the tube from the magnetic rack and resuspend the pellet in 34 µl Elution Buffer (EB).

Spin the sample down briefly and incubate for 10 minutes at room temperature.

Note: For high molecular weight DNA, incubating at 37°C can improve the recovery of long fragments.

将离心管静置于磁力架上至少一分钟,直到磁珠和液相分离,且洗脱液澄清无色。

Remove and retain 34 µl of eluate containing the DNA library into a clean 1.5 ml Eppendorf DNA LoBind tube.

CHECKPOINT

Quantify 1 µl of eluted sample using a Qubit fluorometer.

Prepare 50–100 fmol of your final library to 32 µl with Elution Buffer (EB).

Alternatively, assume an average fragment length of 1 kbp and proceed with 33 ng of library.

Note: If your DNA library is below the required concentration, take forward the full volume of 32 µl eluted DNA for sequencing.

Caution: Please note, very low recovery could be indicative of library preparation failiure.

If required, we recommend using a mass to mol calculator such as the NEB calculator.

重要

We recommend loading 50–100 fmol of this final prepared library onto the R10.4.1 flow cell.

Loading the recommended concentration onto the flow cell will ensure optimal pore occupancy for high sequencing output. Dilute the library in Elution Buffer if required.

步骤结束

构建好的文库即可用于测序芯片上样。在上样前,请将文库置于冰上或4℃条件下保存。

提示

文库保存建议

若为 短期 保存或重复使用(例如在清洗芯片后再次上样),我们建议将文库置于Eppendorf LoBind 离心管中 4℃ 保存。 若为一次性使用且储存时长 __超过3个月__,我们建议将文库置于Eppendorf LoBind 离心管中 -80℃ 保存。

8. PromethION 测序芯片的预处理及上样

材料
  • 测序缓冲液(SB)
  • 文库颗粒(LIB)
  • 文库溶液(LIS)
  • 测序芯片系绳(FCT)
  • 测序芯片冲洗液(FCF)

耗材
  • PromethION 测序芯片
  • 1.5 ml Eppendorf DNA LoBind 离心管

仪器
  • PromethION 测序设备
  • PromethION 测序芯片遮光片
  • P1000 移液枪和枪头
  • P200 移液枪和枪头
  • P20 移液枪和枪头
重要

本试剂盒仅兼容R10.4.1测序芯片(FLO-PRO114M)。

于室温下解冻测序缓冲液(SB)、文库颗粒(LIB)或文库溶液(LIS)、测序芯片系绳(FCT)和一管测序芯片冲洗液(FCF)。完全解冻后,涡旋振荡混匀,然后瞬时离心并置于冰上。

按下表制备测序芯片的预处理液,室温下涡旋振荡混匀。

请注意: 我们正在将部分试剂的包装形式由单次管装改为瓶装。请按照与您所用试剂盒包装相对应的说明操作。

单次使用管装: 向一整管测序芯片冲洗液(FCF)中加入30µl 测序芯片系绳(FCT)。

瓶装: 请另拿一支适当体积的离心管制备测序芯片预处理液:

试剂 体积(每张芯片)
测序芯片冲洗液 (FCF) 1,170 µl
测序芯片系绳 (FCT) 30 µl
总体积 1,200 µl
重要

将芯片从冰箱中取出后,请将其置于室温环境孵育20分钟再插入PromethION测序仪。潮湿环境下的测序芯片上可能会形成冷凝水。因此,请检查测序芯片顶部和底部的金色连接器引脚处是否有水凝结。如有,请使用无纤维布擦干。请确保测序芯片底部有热垫(黑色)覆盖。

对 PromethION 2 Solo,请按以下步骤为测序芯片上样:

  1. 将测序芯片平放在金属板上。

  2. 将测序芯片推入对接端口,直至金色引脚或绿色电路板不可见。

J2068 FC-into-P2-animation V5

对PromethION 24/48,将测序芯片插入相应卡槽的对接端口:

  1. 将测序芯片与连接器横竖对齐,以便顺利卡入。

  2. 用力下压芯片至卡槽,并确认卡夹位置归位。

Prom Flowcell Loading 1a 中文

Prom Flowcell Loading 1b 中文

重要

如插入配置测试芯片的角度出现偏差,可能会损坏PromethION上的引脚并影响测序结果。如您发现 PromethION测序仪芯片位置上的引脚损坏,请通过电子邮件(support@nanoporetech.com)或微信公众号在线支持(NanoporeSupport)联系我们的技术支持团队。

Screenshot 2021-04-08 at 12.08.37

顺时针滑动加液孔孔盖,将其打开。

Prom Flowcell Loading 2 中文

重要

从测序芯片中反旋排出缓冲液。请勿吸出超过20-30µl的缓冲液,并确保芯片上的纳米孔阵列一直有缓冲液覆盖。将气泡引入阵列会对纳米孔造成不可逆转地损害。

在加液孔打开的状态下,按下述步骤吸取少量液体,同时避免引入气泡:

  1. 将P1000移液枪转至200µl刻度。
  2. 将枪头垂直插入加液孔中。
  3. 反向转动移液枪量程调节转纽,直至移液枪刻度在220-230 µl之间,或直至您看到有少量缓冲液进入移液枪枪头。

Prom Flowcell Loading 3 中文

使用P1000移液枪向芯片的加液孔中加入500 µl芯片预处理溶液。加入过程中,请避免引入气泡。等待5分钟,与此同时,您可按以下步骤准备上样文库。

Prom Flowcell Loading 4 中文

将含有文库颗粒的LIB管用移液枪吹打混匀。

重要

LIB管内的文库颗粒分散于悬浮液中。由于颗粒沉降速度非常快,因此请在混匀颗粒后立即使用。

对于大多数测序实验,我们建议您使用文库颗粒(LIB)。但如文库较为粘稠,您可考虑使用文库溶液(LIS)。

在一支新的1.5ml Eppendorf DNA LoBind离心管内,将所有试剂按以下顺序混合:

试剂 每张测序芯片的上样体积
测序缓冲液 (SB) 100 µl
文库颗粒 (LIB),使用前充分混匀;或文库溶液 (LIS) 68 µl
DNA 文库 32 µl
总体积 200 µl

请注意: 此处增大了文库的上样量,以增强纳米孔阵列的覆盖度。

缓慢向芯片的加液口中加入500 µl预处理液,完成芯片的预处理。

Prom Flowcell Loading 5 中文

临上样前,用移液枪轻轻吹打混匀制备好的文库。

使用 P1000 移液枪向加液孔中加入200 µl 文库。

Prom Flowcell Loading 6 中文

合上加液孔孔盖。

Prom Flowcell Loading 7 中文

重要

为获得最佳测序产出,在文库样本上样后,请立即在测序芯片上安装遮光片。

我们建议在清洗芯片并重新上样时,将遮光片保留在测序芯片上。一旦文库从测序芯片中吸出,即可取下遮光片。

如遮光片不在测序芯片上,请您按照以下步骤安装:

  1. 将遮光片的中空部分(空槽)与测序芯片的加液孔孔盖对齐。确保遮光片的前沿位于测序芯片ID的上方。
  2. 用力下压遮光片的卡垫部分,遮光片空槽边缘会随卡垫卡入加液孔孔盖下方。

Prom Flowcell Loading 8a 中文

Prom Flowcell Loading 8b 中文

步骤结束

准备就绪后,合上PromethION设备上盖。

请在为PromethION芯片上样后,等待10分钟再启动实验,以提高芯片产出。

9. Data acquisition and basecalling

How to start sequencing

Once you have loaded your flow cell, the sequencing run can be started on MinKNOW, our sequencing software that controls the device, data acquisition and real-time basecalling. For more detailed information on setting up and using MinKNOW, please see the MinKNOW protocol.

MinKNOW can be used and set up to sequence in multiple ways:

  • On a computer either direcly or remotely connected to a sequencing device.
  • Directly on a PromethION 24/48 sequencing device.

For more information on using MinKNOW on a sequencing device, please see the device user manuals:

Open the MinKNOW software using the desktop shortcut and log into the MinKNOW software using your Community credentials.

Click on your connected device.

prom 48

Set up a sequencing run by clicking Start sequencing.

Edit 1

Type in the experiment name, select the flow cell postition and enter sample ID. Choose FLO-PRO114M flow cell type from the drop-down menu.

Click Continue to kit selection.

Flow cell selection

Select the Ligation Sequencing Kit V14 (SQK-LSK114).

An expansion kit does not need to be selected.

Click Continue to Run Options to continue.

kit selection

Set the run options to a 72 hour run length and 200 bp minimum read length.

Click Continue to basecalling to continue.

Edit 4

Set up basecalling using the following parameters:

  1. Ensure the basecalling is switched ON.
  2. Next to "Models", click Edit options and choose Super accurate basecaller (SUP) from the drop-down menu. Note: If multiple flow cell are being run on the device, we recommend using the High-accuracy baseceller (HAC) and rebasecalling with SUP post-run.
  3. Ensure barcoding is OFF.

Click Continue to output and continue.

Picture1

Keep the output format and filtering options to their default settings.

However, .fast5 output can be used if you cannot use .pod5 output files.

Click Continue to final review to continue.

output setting

Click Start to start sequencing.

You will be automatically navigated to the Sequencing Overview page to monitor the sequencing run.

final review

Data analysis after sequencing

After sequencing has completed on MinKNOW, the flow cell can be reused or returned, as outlined in the Flow cell reuse and returns section.

After sequencing and basecalling, the data can be analysed, as outlined in the Downstream analysis section.

10. 结束实验

材料
  • 测序芯片清洗剂盒(EXP-WSH004)

完成测序实验后,如您希望再次使用测序芯片,请按照测序芯片清洗试剂盒的说明进行操作,并将清洗后的芯片置于2-8℃保存。

您可在纳米孔社区获取 测序芯片清洗试剂盒实验指南

请按照“回收程序”清洗好芯片,以便送回Oxford Nanopore。

您可在 此处找到回收测序芯片的说明。

请注意: 在将测序芯片寄回之前,请使用去离子水对每张芯片进行冲洗。

重要

如果您遇到问题或对测序实验有疑问,请参阅本实验指南在线版本中的“疑难解答指南”一节。

11. Downstream analysis

EPI2ME provides a Nextflow-based workflow for the analysis of single-cell sequencing data.

The workflow, wf-single-cell, processes the FASTQ format sequence data prepared by the MinKNOW software. The workflow screens each sequence read for 10X cell barcode information and assigns reads to a cell of origin. A subset of sequences from “true” cells are dynamically filtered on the basis of the number of assigned sequence reads. These sequences are mapped to the reference genome, and tables of both gene and transcript abundance are prepared for each cell. These "cell barcode x gene" or transcript abundance information are used to prepare the familiar UMAP plots that may show the stratification of the cell types present within the sample.

For more information on this workflow, follow the link to the GitHub documentation.

12. DNA/RNA提取和文库制备过程中可能出现的问题 (1)

以下表格列出了常见问题,以及可能的原因和解决方法。

我们还在 Nanopore 社区的“Support”板块 提供了常见问题解答(FAQ)。

如果以下方案仍无法解决您的问题,请通过电邮(support@nanoporetech.com))或微信公众号在线支持(NanoporeSupport)联系我们。

低质量样本 (1)

现象 可能原因 措施及备注
低纯度DNA(Nanodrop测定的DNA吸光度比值260/280<1.8,260/230 <2.0-2.2) 用户所使用的DNA提取方法未能达到所需纯度 您可在 污染物专题技术文档 中查看污染物对后续文库制备和测序实验的影响。请尝试其它不会导致污染物残留的 提取方法

请考虑将样品再次用磁珠纯化。
RNA完整度低(RNA完整值(RIN)<9.5,或rRNA在电泳凝胶上的条带呈弥散状) RNA在提取过程中降解 请尝试其它 RNA 提取方法。您可在 RNA完整值专题技术文档 中查看更多有关RNA完整值(RIN)的介绍。更多信息,请参阅 DNA/RNA 操作 页面。
RNA的片段长度短于预期 RNA在提取过程中降解 请尝试其它 RNA 提取方法。 您可在 RNA完整值专题技术文档中查看更多有关RNA完整值(RIN)的介绍。更多信息,请参阅DNA/RNA 操作 页面。

我们建议用户在无RNA酶污染的环境中操作,并确保实验设备没有受RNA酶污染.

经AMPure磁珠纯化后的DNA回收率低

现象 可能原因 措施及备注
低回收率 AMPure磁珠量与样品量的比例低于预期,导致DNA因未被捕获而丢失 1. AMPure磁珠的沉降速度很快。因此临加入磁珠至样品前,请确保将磁珠重悬充分混匀。

2. 当AMPure磁珠量与样品量的比值低于0.4:1时,所有的DNA片段都会在纯化过程中丢失。
低回收率 DNA片段短于预期 AMPure磁珠量与样品量的比值越低,针对短片段的筛选就越严格。每次实验时,请先使用琼脂糖凝胶(或其他凝胶电泳方法)确定起始DNA的长度,并据此计算出合适的AMPure磁珠用量。 SPRI cleanup
末端修复后的DNA回收率低 清洗步骤所用乙醇的浓度低于70% 当乙醇浓度低于70%时,DNA会从磁珠上洗脱下来。请确保使用正确浓度的乙醇。

13. Issues during the sequencing run

以下表格列出了常见问题,以及可能的原因和解决方法。

我们还在 Nanopore 社区的“Support”板块 提供了常见问题解答(FAQ)。

如果以下方案仍无法解决您的问题,请通过电邮(support@nanoporetech.com))或微信公众号在线支持(NanoporeSupport)联系我们。

Mux扫描在测序起始时报告的活性孔数少于芯片质检时报告的活性孔数

现象 可能原因 措施及备注
MinKNOW Mux 扫描在测序起始时报告的活性孔数少于芯片质检时报告的活性孔数 纳米孔阵列中引入了气泡 在对通过质控的芯片进行预处理之前,请务必排出预处理孔附近的气泡。否则,气泡会进入纳米孔阵列对其造成不可逆转地损害。 视频中演示了避免引入气泡的最佳操作方法。
MinKNOW Mux 扫描在测序起始时报告的活性孔数少于芯片质检时报告的活性孔数 测序芯片没有正确插入测序仪 停止测序,将芯片从测序仪中取出,再重新插入测序仪内。请确保测序芯片被牢固地嵌入测序仪中,且达到目标温度。如用户使用的是GridION/PromethION测序仪,也可尝试将芯片插入仪器的其它位置进行测序。
inKNOW Mux 扫描在测序起始时报告的活性孔数少于芯片质检时报告的活性孔数 文库中残留的污染物对纳米孔造成损害或堵塞 在测序芯片质检阶段,我们用芯片储存缓冲液中的质控DNA分子来评估活性纳米孔的数量。而在测序开始时,我们使用DNA文库本身来评估活性纳米孔的数量。因此,活性纳米孔的数量在这两次评估中会有约10%的浮动。

如测序开始时报告的孔数明显降低,则可能是由于文库中的污染物对膜结构造成了损坏或将纳米孔堵塞。用户可能需要使用其它的DNA/RNA提取或纯化方法,以提高起始核酸的纯度。您可在 污染物专题技术文档中查看污染物对测序实验的影响。请尝试其它不会导致污染物残留的 提取方法

MinKNOW脚本失败

现象 可能原因 措施及备注
MinKNOW显示 "Script failed”(脚本失败)
重启计算机及MinKNOW。如问题仍未得到解决,请收集 MinKNOW 日志文件 并联系我们的技术支持。 如您没有其他可用的测序设备,我们建议您先将装有文库的测序芯片置于4°C 储存,并联系我们的技术支持团队获取进一步储存上的建议。

Pore occupancy below 40%

Observation Possible cause Comments and actions
Pore occupancy <40% Not enough library was loaded on the flow cell Ensure you load the recommended amount of good quality library in the relevant library prep protocol onto your flow cell. Please quantify the library before loading and calculate mols using tools like the Promega Biomath Calculator, choosing "dsDNA: µg to pmol"
Pore occupancy close to 0 The Ligation Sequencing Kit was used, and sequencing adapters did not ligate to the DNA Make sure to use the NEBNext Quick Ligation Module (E6056) and Oxford Nanopore Technologies Ligation Buffer (LNB, provided in the sequencing kit) at the sequencing adapter ligation step, and use the correct amount of each reagent. A Lambda control library can be prepared to test the integrity of the third-party reagents.
Pore occupancy close to 0 The Ligation Sequencing Kit was used, and ethanol was used instead of LFB or SFB at the wash step after sequencing adapter ligation Ethanol can denature the motor protein on the sequencing adapters. Make sure the LFB or SFB buffer was used after ligation of sequencing adapters.
Pore occupancy close to 0 No tether on the flow cell Tethers are adding during flow cell priming (FLT/FCT tube). Make sure FLT/FCT was added to FB/FCF before priming.

读长短于预期

现象 可能原因 措施及备注
读长短于预期 DNA样本降解 读长反映了起始DNA片段的长度。起始DNA在提取和文库制备过程中均有可能被打断。

1. 1. 请查阅纳米孔社区中的 提取方法 以获得最佳DNA提取方案。

2. 在进行文库制备之前,请先跑电泳,查看起始DNA片段的长度分布。DNA gel2 在上图中,样本1为高分子量DNA,而样本2为降解样本。

3. 在制备文库的过程中,请避免使用吹打或/和涡旋振荡的方式来混合试剂。轻弹或上下颠倒离心管即可。

大量纳米孔处于不可用状态

现象 可能原因 Comments and actions
大量纳米孔处于不可用状态 (在通道面板和纳米孔活动状态图上以蓝色表示)

image2022-3-25 10-43-25 上方的纳米孔活动状态图显示:状态为不可用的纳米孔的比例随着测序进程而不断增加。
样本中含有污染物 使用MinKNOW中的“Unblocking”(疏通)功能,可对一些污染物进行清除。 如疏通成功,纳米孔的状态会变为"测序孔". 若疏通后,状态为不可用的纳米孔的比例仍然很高甚至增加:

1. 用户可使用 测序芯片冲洗试剂盒(EXP-WSH004)进行核酸酶冲洗 can be performed, 操作,或
2. 使用PCR扩增目标片段,以稀释可能导致问题的污染物。

大量纳米孔处于失活状态 (1)

现象 可能原因 措施及备注
大量纳米孔处于失活状态(在通道面板和纳米孔活动状态图上以浅蓝色表示。膜结构或纳米孔遭受不可逆转地损伤) 测序芯片中引入了气泡 在芯片预处理和文库上样过程中引入的气泡会对纳米孔带来不可逆转地损害。请观看 测序芯片的预处理及上样 视频了解最佳操作方法。
大量纳米孔处于失活/不可用状态 文库中存在与DNA共纯化的化合物 与植物基因组DNA相关的多糖通常能与DNA一同纯化出来。

1. 请参考 植物叶片DNA提取方法
2. 使用QIAGEN PowerClean Pro试剂盒进行纯化。
3. 利用QIAGEN REPLI-g试剂盒对原始gDNA样本进行全基因组扩增。
大量纳米孔处于失活/不可用状态 样本中含有污染物 您可在 污染物专题技术文档 中查看污染物对测序实验的影响。请尝试其它不会导致污染物残留的提取方法。

温度波动

现象 可能原因 措施及备注
温度波动 测序芯片和仪器接触不良 检查芯片背面的金属板是否有热垫覆盖。重新插入测序芯片,用力向下按压,以确保芯片的连接器引脚与测序仪牢固接触。如问题仍未得到解决,请联系我们的技术支持。

未能达到目标温度

现象 可能原因 措施及备注
MinKNOW显示“未能达到目标温度” 测序仪所处环境低于标准室温,或通风不良(以致芯片过热) MinKNOW会限定测序芯片达到目标温度的时间。当超过限定时间后,系统会显示出错信息,但测序实验仍会继续。值得注意的是,在错误温度下测序可能会导致通量和数据质量(Q值)降低。请调整测序仪的摆放位置,确保其置于室温下、通风良好的环境中后,再在MinKNOW中继续实验。有关MinION MK1B温度控制的更多信息,请参考此 FAQ (常见问题)文档。

Last updated: 8/21/2024

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