No abstract

4-Nonylphenol (4-NP) is a known endocrine disrupting chemical and a persistent environmental contaminant. However, the 4-NP caused mechanism of reproductive toxicity still remains largely unknown in birds. In this study, female chickens (Hy-Line Variety White) were dosed via oral gavage in the early laying period with 0, 50, 100, and 200 mg 4-NP/kg/d for 60 days. Food intake and weight increase were monitored in this organism to investigate chicken growth and development. Moreover, pathological changes of reproductive organs, serum hormone, and mRNA changes on the HPOA were detected. The results showed that gonad development and maturity were retarded in female chickens, and the circulating concentrations of sex hormones were disordered in 4-NP-treated chicken. In 4-NP exposed animals, the mRNA expressions of GnRH and PRLH in hypothalamus and FSH and LH in pituitary were significantly unregulated by 4-NP. In addition, expressions of FSHR and LHR were down-regulated in ovaries of the 4-NP-treatment group, while the levels of stAR, P450scc, P450arom, 3β-HSD, and 17β-HSD were up-regulated in ovaries. Furthermore, expression of ERα in the ovaries of chicken was up-regulated, however, no significant change was observed for ERβ expression. Our results suggest that granulosa cells were an important target and severely disturbed by 4-NP.

Methicillin resistant Staphylococcus aureus (MRSA) is one of the most prevalent pathogens that account for severe nosocomial infections in millions of patients annually [1]. High resistance to beta-lactam antibiotics exhibited by this organism can be majorly attributed to its ability to produce a class of enzymes called beta-lactamases. Our team investigated the protective effect of a group of charged metallopolymers on antibiotics like penicillin, which are usually hydrolyzed by betalactamases, thus making them ineffective. For this purpose, we employed several biochemical and structural approaches to study interactions of these recombinant enzymes with conjugate complexes of penicillin and metallopolymers in vitro [2]. Recombinant enzymes are often modified in order to improve their expression, yield and structural studies. This study analyzed the effects of different modifications of recombinant beta-lactamases on their stability and activity in vitro. Comparison of enzymatic characteristics and the interactions of modified enzymes with conjugates of penicillin and metallopolymers is discussed.