Two experiments were conducted to investigate the kinetics of manganese (Mn) transport in Caco-2 cell monolayers and the gene expressions of Mn transport carriers in apical (AP) and basolateral (BL) membranes. In experiment 1, the cells were treated with the medium containing 146 μmol/L of Mn (MnSO4·H2O). Both the uptake and transport of Mn from AP-BL or from BL-AP at different time-points were assessed to determine the optimal time for kinetics of Mn transport. The transport of Mn increased linearly with higher efficiency values in AP-BL than in BL-AP direction, however, the uptake of Mn revealed an asymptotic pattern within 120 min. In experiment 2, the kinetics of Mn transport in AP-BL was determined with media containing Mn concentrations from 0 to 2,500 μmol/L at 40 and 120 min, respectively, and mRNA levels of divalent metal transporter 1 (DMT1) and ferroportin (FPN1) were determined in Caco-2 cells treated with the medium containing 0 or 800 μmol/L of Mn for 120 min. The kinetics of Mn transport showed a carrier-mediated process when Mn concentrations were lower than 1,000 μmol/L and a linear increment when Mn concentrations exceeded 1,000 μmol/L at either 40 or 120 min. Mn treatment decreased (P < 0.01) DMT1 mRNA level and increased (P < 0.01) FPN1 mRNA level. The results from the present study suggested that Mn transport in AP-BL fit both carrier-mediated saturable and non-saturable diffusion processes, and Mn transport carriers DMT1 and FPN1 mediate the apical uptake and basolateral exit of Mn in Caco-2 cells.

DNA samples from 737 tick pools, representing 6,850 Haemaphysalis longicornis and 51 Dermacentor nuttalli collected from Hebei Province, China, were analyzed by polymerase chain reaction (PCR) for the presence of spotted fever group Rickettsia. Fifty (6.9%) of 724 H. longicornis in the tick pool were positive, but no positive samples were found in 13 D. nuttalli. Sequence analysis of the partial outer membrane protein A (ompA) genes from the 10 positive samples showed 97.4-99.8% identity, but were different from the homologous sequence of Rickettsia previously deposited in GenBank. Phylogenetic analysis of ompA genes indicated that the Rickettsia detected in this study belonged to a novel haplotype, and formed a clade distinct from Rickettsia heilongjiangii, Rickettsia sibirica, and Rickettsia hulinii in China. The new strain, named Candidatus Rickettsia hebeiii, appears to represent a distinct lineage and could constitute a new species with a minimum prevalence of about 0.7% in H. longicornis from Hebei Province, China.

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A total of 3696 Ixodid ticks, collected from Hebei Province, China, were examined by a nested polymerase chain reaction for the presence of Anaplasma phagocytophilum. Forty-three (15.4%) of 280 pools tested, including 39 (14.6%) of 267 Haemaphysalis longicornis and four (30.8%) of 13 Dermacentor nuttalli, were positive, but no significant difference was found between D. nuttalli and H. longicornis (p>0.05). Sequence and phylogenetic analyses of 16S rRNA gene indicated that A. phagocytophilum in China is genetically diverse. To our knowledge, this is the first evidence of A. phagocytophilum in ticks from Hebei Province, China, and the first documentation of Anaplasma infection in D. nuttalli.

Anaplasma phagocytophilum is an emerging pathogen known to cause human granulocytic anaplasmosis (HGA). Here we determined the prevalence and genetic characterization of A. phagocytophilum in Hebei Province, China. A total of 253 samples were taken from goats and sheep in Hebei Province, and 52 (20.6%) were positive for A. phagocytophilum. There was a higher positive rate in sheep (23.8%, 20/84) than in goats (18.9%, 32/169). Analysis of the partial 16S RNA gene sequences of A. phagocytophilum revealed that the isolates in this study were members of the same clade and were 100% homologous with each other. This study provides information on the epidemiologic features of A. phagocytophilum.