Modification of nanoscale polymeric adsorbent for the preparative separation and purification of tacrolimus from fermentation broth of Streptomyces tsukubaensis.

Tacrolimus is an important immunosuppressant produced by microbial fermentation. In this study, a modified nanoscale polymeric adsorbent, Ag+-exchanged resin, was prepared and studied for the preparative separation and purification of tacrolimus from fermentation broth of Streptomyces tsukubaensis. The performance and absorption characteristics of the modified nanoscale polymeric adsorbent namely Ag-NPS was evaluated. Notably, Ag-NPS resin displayed the pronounced separation capacities for tacrolimus and its equilibrium adsorption data was well-fitted to the Langmuir isotherm. Moreover, the dynamic adsorption and desorption tests was carried out to obtain the operational parameters for further purification of tacrolimus. Finally, tacrolimus and the two major impurities, ascomycin and dihydrotacrolimus, were separated well in the scale-up purification process. The purity and recovery of tacrolimus was recorded to be 99.12±0.25% and 90.41±2.05%. In conclusion, this method displayed a high potential for separation and purification of tacrolimus and other unsaturated bioactive compounds in high yield from the fermentation broth.

Enhanced Li Storage Stability Induced by Locating Sn in Metal-Organic Frameworks.

By locating elemental Sn in an open anionic framework, the particle cracking arising from huge volume expansion of Sn-based anode materials during lithiation/delithiation is alleviated, and the cycling stability is greatly improved. The Sn-based metal-organic framework anode material shows superior cyclic stability, with a capacity retention >92 % (after 200 cycles) and high lithium storage capacity (610 mAh g-1 ).

Atmospheric occurrence, homologue patterns and source apportionment of short- and medium-chain chlorinated paraffins in Shanghai, China: Biomonitoring with Masson pine (Pinus massoniana L.) needles.

A comprehensive survey was conducted to Masson pine (Pinus massoniana L.) needles widely distributed in Shanghai in order to investigate the levels and homologue group patterns of short- and medium-chain chlorinated paraffins (SCCPs and MCCPs), to identify and quantitatively assess source contributions to the total CPs in pine needle samples. The concentration ranged from not detected (ND) to 13,600ngg(-1) with a geometric mean (GM) value of 63.7ngg(-1) for ΣSCCPs, from 12.4 to 33,500ngg(-1) with a GM value of 677ngg(-1) for ΣMCCPs, and from 14.0 to 45,700ngg(-1) with a GM value of 768ngg(-1) for total CPs. For different sampling units, the pollution levels both for SCCPs and MCCPs in pine needles were in the same orders: Pudong>suburbs>Puxi>Chongming. These significant differences in SCCPs and MCCPs among four sampling units could be associated with difference in industrial activities and to some extent also in population density. All pine needle samples (n=131) were divided into 2 groups by hierarchical cluster analysis (HCA) for SCCPs and MCCPs, the most abundant homologue groups in the bulk of pine needle samples were C11Cl5-7 and C13Cl5-7 for SCCPs, and C14Cl7-8 and C15Cl7-8 for MCCPs. Correlation analysis suggested that SCCPs and MCCPs in pine needles in the studied area may be derived from different sources. Four sources for pine needles were identified by the FA-MLR model; their relative contributions to the total CP burden in pine needles were 18.0% for F1 (attributed to commercial SCCP mixture), 42.2% for F2 (attributed to commercial MCCP mixture), 29.3% for F3 (attributed to LRAT), and 10.5% for F4 (unknown source). CP contamination of atmospheric air by point sources and long-range atmospheric transport in Shanghai should receive more attention by local government.

Two novel amphomycin analogues from Streptomyces canus strain FIM-0916.

Three lipopeptides, the known compound amphomycin, together with two novel compounds named aspartocin D (1) and aspartocin E (2) were obtained from the fermentation broth extraction of Streptomyces canus strain FIM0916 by using various column chromatography techniques. Their structures were elucidated by using spectroscopic methods, mainly by an extensive NMR analysis. It was demonstrated that compounds 1 and 2 are novel analogues of amphomycin, whose structures are similar to aspartocins. Compounds 1 and 2 share the same cyclic decapeptide core of cyclo (Dab2-Pip3-MeAsp4-Asp5-Gly6-Asp7-Gly8-Dab9-Val10-Pro11-), differing only in the side-chain moiety corresponding to Asp1-△3-isohendecenoic acid and Asp1-△3-isododecenoic acid, for aspartocin D and aspartocin E. In bioassays, compounds 1 and 2 exhibited antimicrobial activities against Gram-positive bacteria in the presence of Ca(2+) (1.25 mM); particularly, the activities were enhanced with higher concentrations of calcium.

Xenopus laevis is a potential alternative model animal species to study reproductive toxicity of phytoestrogens.

This study investigated effects of phytoestrogen quercetin on the gonadal development in Xenopus laevis. X. laevis at Nieuwkoop and Faber stage 46/47 were exposed to 50, 100 and 200 microg/L quercetin till 1 month postmetamorphosis. Gonads from frogs at 1 and 3 months postmetamorphosis were examined in gross morphology and histology. The highest dose of quercetin as well as estradiol (E2) significantly increased the percentages of phenotypic females. Exposure to quercetin at all doses induced abnormal testes with certain ovarian characteristics to some degree in gross morphology, including ovotestes. The abnormality rate exceeded 10% in each quercetin treatment. Histologic examination revealed that some abnormal testes exhibited intersexuality with testicular structure and ovarian structure or oocytes interspersed in testicular structure at 1 month postmetamorphosis. At 3 months postmetamorphosis, testicular abnormalities were more obvious, such as necrosis or apoptosis of spermatogonia, occurrence of developed or undeveloped oocytes, delay of the development of seminiferous tubes without or less late stage spermatocytes. The results have shown that quercetin cannot only feminize but also impair testicular development of X. laevis, i.e. X. laevis is sensitive to phytoestrogen. It is suggested that X. laevis might be an alternative model species to study reproductive toxicity of phytoestrogens.

Potential ecotoxic effects of polychlorinated biphenyls on Xenopus laevis.

We examined potential ecotoxic effects of polychlorinated biphenyl (PCB)3, PCB5, Aroclor 1254, and Aroclor 1242 on Xenopus laevis. Tadpoles were exposed to PCBs from stage 46/47 (system of Nieuwkoop and Faber) to the completion of metamorphosis. We demonstrated, to our knowledge for the first time, forelimb malformations caused by PCBs (malformation rate, > 70%). The malformed forelimbs were fixed in the adduction-backward rotation position and could not move. Therefore, malformed male frogs were destined to have no offspring, because they could not grasp the females with their forelimbs to mate. Alcian blue-alizarin red double-staining indicated that the forelimb malformation resulted from the shoulder abnormality. Compared with the normal shoulder joint, the proximal humerus with the humerus inter-rotated 90 degrees in the abnormal shoulder joint. Moreover, testes from more than a third of male frogs with exposed to PCBs exhibited feminization to different degrees at gross morphology and histology, with fewer or abnormal spermatogonia and oocytes. Gonadal abnormalities would lead directly to reproductive dysfunction and population decline. These results suggest that PCBs have potentially ecotoxic effects on amphibian populations. We infer that PCBs could play roles in amphibian malformations and population declines, at least at sites that are polluted heavily with PCBs.

Effects of Chinese domestic polychlorinated biphenyls (PCBs) on gonadal differentiation in Xenopus laevis.

To determine whether polychlorinated biphenyls (PCBs) influence gonadal differentiation in Xenopus laevis, tadpoles were exposed to two Chinese domestic PCBs (PCB3 and PCB5 from Nieuwkoop and Faber stage 46/47 to complete metamorphosis. Gonads were characterized using a dissecting microscope. The control X. laevis had normal ovaries or testes in gross morphology, whereas obviously abnormal testes including ovotestes were found in PCB3- and PCB5-exposed groups. Ovotestes were characterized by morphologic ovaries in the cranial and caudal parts and morphologic testes in the middle part. PCBs did not alter the percentage of females but reduced the percentage of males with morphologically normal testes. The histologic structure of gonads was examined by a series of sections. Morphologically normal and abnormal testes from a few frogs exposed to PCBs were interspersed with oocytes in histologic sections. These testes exhibited looser structure with fewer seminiferous tubes, spermatogonia, and spermatozoa than in controls. The findings suggest that PCB3 and PCB5 have significant feminization effects on gonadal differentiation in X. laevis and that this species is sensitive to endocrine disruption and may be used as a good model to study endocrine disruption.