需求：构建13个物种的13个基因的系统进化树

• 下载需要比对的12个物种
• 将13个物种中13个基因分别分开到单独的文件
• 比对每一个基因
• 拼接比对结果
• 使用mage构建系统发育树

一、下载需要比对的12个物种

from Bio import Entrez
import os
Entrez.email = "1749748955@qq.com"

def downloadByNucleotide(ids,path,file_type,endName):
    if not os.path.exists(path):
         os.makedirs(path) 

    print("共下载序列",len(ids),"条")
    for id in ids:
        print("准备下载",id,"....")
        hd_efetch_fa = Entrez.efetch(db='nucleotide', id=id, rettype=file_type)
        read_efetch_fa = hd_efetch_fa.read()
        with open("{0}/{1}.{2}".format(path,id,endName),"w") as file:
            file.write(read_efetch_fa)
        print(id,"下载完成....")
        
# download genbank sequencess
def downloadByNucleotideAndGenbank(ids,path):
    downloadByNucleotide(ids,path,"gb","gb")

if __name__ == "__main__":
    ids=["NC_037234.1","NC_029326.1","NC_024028.1","NC_030265.1","KY689117.1","KY689119.1","NC_034282.1","NC_037207.1","NC_037235.1","NC_030266.1","KY689125.1","NC_037205.1"]
    downloadByNucleotideAndGenbank(ids,"temp/source")

• 下载的结果：

.
├── KY689117.1.gb
├── KY689119.1.gb
├── KY689125.1.gb
├── NC_024028.1.gb
├── NC_029326.1.gb
├── NC_030265.1.gb
├── NC_030266.1.gb
├── NC_034282.1.gb
├── NC_037205.1.gb
├── NC_037207.1.gb
├── NC_037234.1.gb
└── NC_037235.1.gb

拷贝需要比对的基因到 temp/source

二、将13个物种中13个基因分别分开到单独的文件

from Bio import SeqIO
import os
list_sort=["ND2","COX1","COX2","ATP8","ATP6","COX3","ND3","ND5","ND4","ND4L","ND6","CYTB","ND1"]

def linkGene(input_path,output_path):
    # 如果不存在就创建文件夹
    if not os.path.exists(input_path):
         os.makedirs(input_path) 
    if not os.path.exists(output_path):
         os.makedirs(output_path) 
  
    # 遍历该目录下的每一个文件夹
    for file_name in os.listdir(input_path):
        # 使用biopython读取genbank文件的完整序列
        records = SeqIO.read("{0}/{1}".format(input_path,file_name),"genbank")
        #从Genbank获取完整序列
        complete_seq = str(records.seq)
        # 打印基因名称
        print(">"+records.annotations["source"]+" "+records.id)
        gene_dict = {}
        for feature in  records.features:
            if feature.type == "CDS":
                # print(feature.qualifiers.get("gene"))
                # 获取基因的名称eg.[ND1、ND2]
                gene_name = feature.qualifiers.get("gene")[0]
                # print(type(feature.location.parts))
                gene_seq=""
                for gene in  feature.location.parts:
                    # print(complete_seq[gene.start:gene.end])
                    # 获取对应的基因序列
                    gene_seq = gene_seq + complete_seq[gene.start:gene.end]
                # 
                gene_dict[gene_name]=gene_seq

        #按照顺序遍历基因
        print("定义了",len(list_sort),"个基因","序列有",len(gene_dict),"个基因")
        for gene in list_sort:	
            # 第一次循环创建文件
            f = open("{0}/{1}.fasta".format(output_path,gene),"a")
           
            if gene in gene_dict:
                # 添加基因到文件，有12个物种，1个基因文件有12个序列
                print("找到基因：",gene,"长度为：",len(gene_dict[gene]))
                f.write(">"+records.annotations["source"]+" "+records.name+"\n"+gene_dict[gene]+"\n")
            else:
                print("error----------","没有找到基因：",gene)

        print("*******写入完成*******")

if __name__ == "__main__":
    linkGene("temp/source","temp/result")

• 运行的结果：

.
├── ATP6.fasta
├── ATP8.fasta
├── COX1.fasta
├── COX2.fasta
├── COX3.fasta
├── CYTB.fasta
├── ND1.fasta
├── ND2.fasta
├── ND3.fasta
├── ND4.fasta
├── ND4L.fasta
├── ND5.fasta
└── ND6.fasta

三、比对每一个基因

• 这里使用命令行工具megacc
• megacc -a temp/mao/clustal_align_nucleotide.mao -d [输入文件] -f Fasta -o [输出文件夹]

.mao文件的的生成见： https://www.megasoftware.net/web_help_10/index.htm#t=Quick_Start_Tutorial.htm

import os

def alignFasta(input_seq,output_seq):
    # 如果不存在就创建文件夹
    if not os.path.exists(input_seq):
         os.makedirs(input_seq) 
    if not os.path.exists(output_seq):
         os.makedirs(output_seq) 
    os.system("megacc -a temp/mao/clustal_align_nucleotide.mao -d {0}  -f Fasta -o {1}".format(input_seq,output_seq))

def generate_align():
     for file_name in os.listdir("temp/result"):
         print("比对："+file_name+"...........")
         alignFasta("temp/result/{0}".format(file_name),"temp/align_output/")  
         

if __name__ == "__main__":
      generate_align()

• 运行结果：

.
├── ATP6-10469.fasta
├── ATP6-10469_summary.txt
├── ATP8-10415.fasta
├── ATP8-10415_summary.txt
├── COX1-10259.fasta
├── COX1-10259_summary.txt
├── COX2-10525.fasta
├── COX2-10525_summary.txt
├── COX3-10055.fasta
├── COX3-10055_summary.txt
├── CYTB-10197.fasta
├── CYTB-10197_summary.txt
├── ND1-10421.fasta
├── ND1-10421_summary.txt
├── ND2-10556.fasta
├── ND2-10556_summary.txt
├── ND3-10653.fasta
├── ND3-10653_summary.txt
├── ND4-10095.fasta
├── ND4-10095_summary.txt
├── ND4L-10418.fasta
├── ND4L-10418_summary.txt
├── ND5-10646.fasta
├── ND5-10646_summary.txt
├── ND6-10386.fasta
└── ND6-10386_summary.txt

四、拼接比对结果

import os

def alignFasta(input_seq,output_seq):
       # 如果不存在就创建文件夹
    if not os.path.exists(input_seq):
         os.makedirs(input_seq) 
    if not os.path.exists(output_seq):
         os.makedirs(output_seq) 
    os.system("megacc -a temp/mao/clustal_align_nucleotide.mao -d {0}  -f Fasta -o {1}".format(input_seq,output_seq))

def generate_align():
     for file_name in os.listdir("temp/result"):
         print("比对："+file_name+"...........")
         alignFasta("temp/result/{0}".format(file_name),"temp/align_output/")  
         
if __name__ == "__main__":
      generate_align()

• 运行结果：

align_result.fasta

五、使用mage构建系统发育树