Hoechst 33342

The nucleic acid stain Hoechst 33342 (Ex/Em: 350/461 nm) is frequently utilized as a cell-permeable nuclear counterstain that emits a blue fluorescence upon binding to dsDNA. Hoechst 33342 is commonly employed in various studies related to cell counting, cell cycle analysis, and cell replication. It is particularly useful in identifying condensed nuclei in apoptotic cells, as well as in combination with BrdU staining for cell-cycle studies.

Hoechst dyes are also useful for monitoring cell viability by tracking changes in their emission spectra. As minor groove-binding DNA stains with AT selectivity, the Hoechst dyes are able to bind to all nucleic acids, but they show a greater fluorescence enhancement for AT-rich double-stranded DNA strands compared to GC-rich strands [1]. This property has been exploited to identify Q-bands in chromosomes, which are regions rich in AT base pairs that fluoresce brightly when stained with the quinacrine dye [2].

Fig. Fluorescence excitation and emission spectra of Hoechst 33342 bound to DNA

References:
[1]. Portugal J, Waring MJ. Assignment of DNA binding sites for 4′, 6-diamidine-2-phenylindole and bisbenzimide (Hoechst 33258). A comparative footprinting study. Biochimica et Biophysica Acta (BBA)-Gene Structure and Expression. 1988 Feb 28;949(2):158-68.
[2]. Weisblum B, Haenssler E. Fluorometric properties of the bibenzimidazole derivative Hoechst 33258, a fluorescent probe specific for AT concentration in chromosomal DNA. Chromosoma. 1974 Sep;46(3):255-60.

核酸染色剂Hoechst 33342 (Ex/Em: 350/461 nm) 常被用作细胞可渗透的核染色剂,与双链DNA结合后发出蓝色荧光。Hoechst 33342常被用于与细胞计数、细胞周期分析和细胞复制相关的各种研究中。它特别有用于鉴定凋亡细胞中的紧缩细胞核,并与BrdU染色结合在一起进行细胞周期研究。

Hoechst染料还可通过跟踪其发射光谱的变化来监测细胞活力。作为小沟结合DNA染料,具有AT选择性,Hoechst染料能够结合所有核酸,但与GC富集的双链DNA链相比,它们对富含AT碱基的链显示出更大的荧光增强[1]。这种特性已被利用于鉴定染色体中的Q带,这些区域富含AT碱基对,当用quinacrine染料染色时会发出明亮的荧光[2]。