Requirements for the application of protein sodium dodecyl sulfate-polyacrylamide gel electrophoresis and randomly amplified polymorphic DNA analyses to product speciation

Genetic Identification of Antimonate Respiratory Reductase in Shewanella sp. ANA-3

Microbial antimonate [Sb(V)] respiratory reduction is an important process regulating Sb redox transformation in the environment. However, little is known about the microbial respiratory reductase for Sb(V). Herein, we report Sb(V)-respiring reduction by Shewanella sp. ANA-3 through an arsenate respiratory reductase encoded by arrAB. Incubation experiments showed that Shewanella sp. ANA-3 mediated Sb(V)-respiring reduction, which was dependent on the cell concentration. Both protein analysis and reverse transcriptase-polymerase chain reaction results revealed that arrAB was highly expressed in Sb(V)-respiring reduction. In vivo evidence with mutants indicated that neither ANA-3-ΔarrA nor ANA-3-ΔarrB was capable of reducing Sb(V) as efficiently as the wild type, whereas complementation by the wild-type sequences of arrA and arrB rescued the mutants' ability. Our in vitro results showed that ArrAB purified by His-Tag was able to mediate Sb(V) reduction, though with much suppressed catalytic kinetics compared with As(V) reduction. The cell-concentration-dependent reduction of Sb(V) was regulated by quorum sensing via the luxS gene. This study opens a new chapter in the mechanistic understanding of microbial Sb(V) respiratory reduction.

Identification of grouper (Epinephelus guaza), wreck fish (Polyprion americanus), and Nile perch (Lates niloticus) fillets by polyclonal antibody-based enzyme-linked immunosorbent assay

An indirect enzyme-linked immunosorbent assay (ELISA) has been developed for the species identification of grouper (Epinephelus guaza), wreck fish (Polyprion americanus), and Nile perch (Lates niloticus) fillets. The assay was performed in two different formats, microtiter plates and immunostick tubes, and uses polyclonal antibodies raised in rabbits against muscle-soluble proteins of grouper (anti-GSP), wreck fish (anti-WSP), and Nile perch (anti-PSP). The antibodies were made species-specific by blocking them with the heterologous soluble muscle proteins. Immunorecognition of polyclonal antibodies adsorbed to their specific fish samples was made with swine antirabbit immunoglobulins conjugated to the enzyme horseradish peroxidase. Subsequent enzymatic conversion of the substrate allowed unequivocal identification of the species studied.