A review on the antibiotic florfenicol: Occurrence, environmental fate, effects, and health risks.

Florfenicol, as a replacement for chloramphenicol, can tightly bind to the A site of the 23S rRNA in the 50S subunit of the 70S ribosome, thereby inhibiting protein synthesis and bacterial proliferation. Due to the widespread use in aquaculture and veterinary medicine, florfenicol has been detected in the aquatic environment worldwide. Concerns over the effects and health risks of florfenicol on target and non-target organisms have been raised in recent years. Although the ecotoxicity of florfenicol has been widely reported in different species, no attempt has been made to review the current research progress of florfenicol toxicity, hormesis, and its health risks posed to biota. In this study, a comprehensive literature review was conducted to summarize the effects of florfenicol on various organisms including bacteria, algae, invertebrates, fishes, birds, and mammals. The generation of antibiotic resistant bacteria and spread antibiotic resistant genes, closely associated with hormesis, are pressing environmental health issues stemming from overuse or misuse of antibiotics including florfenicol. Exposure to florfenicol at µg/L-mg/L induced hormetic effects in several algal species, and chromoplasts might serve as a target for florfenicol-induced effects; however, the underlying molecular mechanisms are completely lacking. Exposure to high levels (mg/L) of florfenicol modified the xenobiotic metabolism, antioxidant systems, and energy metabolism, resulting in hepatotoxicity, renal toxicity, immunotoxicity, developmental toxicity, reproductive toxicity, obesogenic effects, and hormesis in different animal species. Mitochondria and the associated energy metabolism are suggested to be the primary targets for florfenicol toxicity in animals, albeit further in-depth investigations are warranted for revealing the long-term effects (e.g., whole-life-cycle impacts, multigenerational effects) of florfenicol, especially at environmental levels, and the underlying mechanisms. This will facilitate the evaluation of potential hormetic effects and construction of adverse outcome pathways for environmental risk assessment and regulation of florfenicol.

[Identification and pedigree analysis for an A(W)37B subtype due to c.940A>G variant of ABO gene].

OBJECTIVE: To delineate the serological and molecular profiles of a patient with A(w)37B subtype. METHODS: The ABO bloodtypes of the proband, his wife and daughter were determined with a standard serological method. Their ABO genotypes were determined by sequence-specific primer polymerase chain reaction (PCR-SSP). All exons of the ABO gene were directly sequenced. Exons 6 and 7 of the ABO gene were further analyzed by cloning and sequencing. RESULTS: The red blood cells of the proband showed a weak B phenotype. His serum sample contained weak reactive anti-A antibody, which was defined as A(w)B blood group based on the serological characteristics. The A and B alleles were detected by blood group genotyping. Gene cloning and sequencing have identified a characteristic c.940A>G variant (ABO*AW.37) in exon 7 of the ABO gene, which resulted in substitution of Lysine by Glutamate at position 314. The proband's daughter has inherited the ABO*AW.37 allele. CONCLUSION: The c.940A>G variant in exon 7 of the ABO gene probably underlay the decreased activity of GTA transferase and resulted in the Aw37 phenotype.

[Study of a Chinese pedigree carrying a novel variant of α-1, 3-N-acetyl galactosaminyl transferase gene].

OBJECTIVE: To explore the genetic basis for a Chinese pedigree with a novel ABO subtype. METHODS: The proband and his family members were subjected to serological analysis, and their genotypes were determined by fluorescence PCR and direct sequencing of the coding regions of the ABO gene. Exons 6 to 7 of the ABO gene were also subjected to clone sequencing for haplotype analysis. RESULTS: The proband was determined as an AxB subtype. By fluorescence PCR, he was typed as A/B. Clone sequencing has revealed a insertional mutation c.797_798 insT in exon 7 of the ABO gene, which yielded a novel allele. Pedigree analysis confirmed that the novel ABO*A1.02 allele carried by the proband and his sister was inherited from their father. The c.797_798insT mutation has been submitted to GenBank with an accession number of MK125137. CONCLUSION: The c.797_798insT mutation of exon 7 of the ABO gene probably has led to weakened expression of A antigen.