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71.
K. BITENCOURTH M. AMORIM S. V. DE OLIVEIRA R. L. CAETANO C. M. VOLOCH G. S. GAZÊTA 《Medical and veterinary entomology》2017,31(4):427-437
Amblyomma sculptum (Ixodida: Ixodidae) Berlese, 1888 is the most important tick vector in Brazil, transmitting the bioagent of the most severe form of spotted fever (SF) in part of the Cerrado (in the states of Minas Gerais and São Paulo). In another part of the Cerrado (Central‐West region of Brazil), a milder form of SF has been recorded. However, neither the rickettsia nor the vector involved have been characterized. The aim of the current study was to analyse genetic variation and the presence of rickettsia in A. sculptum in Cerrado, from silent areas and with the milder form of SF. Samples were subjected to DNA extraction, amplification and sequencing of 12S rDNA, cytochrome oxidase subunit II and D‐loop mitochondrial genes (for tick population analyses), and gltA, htrA, ompA and gene D (sca4) genes for rickettsia researches. Exclusive haplotypes with low frequencies, high haplotype diversity and low nucleotide diversity, star‐shaped networks and significant results in neutrality tests indicate A. sculptum population expansions in some areas. Rickettsia amblyommatis, Candidatus Rickettsia andeanae and Rickettsia felis were detected. The A. sculptum diversity is not geographically, or biome delimited, pointing to a different potential in vector capacity, possibly associated with differing tick genetic profiles. 相似文献
72.
The transduction of sodium salts occurs through a variety of mechanisms,
including sodium influx through amiloride-sensitive sodium channels,
anion-dependent sodium movement through intercellular junctions and
unidentified amiloride-insensitive mechanisms. Characterizations of sodium
transport in lingual epithelium mounted in Ussing chambers have focused
almost exclusively on epithelia containing only fungiform taste buds. In
the present study we have investigated sodium transport by measuring
NaCl-induced short-circuit current from lingual epithelia containing
fungiform, foliate, vallate and palatine taste buds in the hamster and the
rat. All areas show measurable sodium transport, yet significant
differences were noted between the epithelia from the rat and the hamster
and among the different epithelia within a single species in terms of
current density, transepithelial resistance and mucosal amiloride
sensitivity. In general, epithelia from the anterior tongue were of a lower
resistance and transported sodium more effectively than from the posterior
tongue. Moreover, fungiform- and vallate-containing epithelia in the rat
had a greater current density than did the corresponding tissues in the
hamster. Amiloride sensitivity also differed between the rat and the
hamster. In the hamster all gustatory areas showed some amiloride
sensitivity, while in the rat the vallate-containing epithelia were devoid
of amiloride- sensitive sodium transport. The results are consistent with
the interpretation that all chemosensitive areas may participate in the
detection of salts but the degree of salt transport and the mechanism of
transport is variable among different lingual epithelia and different
species.
相似文献
73.
An empirical adjustment to the likelihood ratio statistic 总被引:2,自引:0,他引:2
74.
Noncontact dipole effects on channel permeation. III. Anomalous proton conductance effects in gramicidin 总被引:3,自引:2,他引:1
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LR Phillips CD Cole RJ Hendershot M Cotten TA Cross DD Busath 《Biophysical journal》1999,77(5):2492-2501
Proton transport on water wires, of interest for many problems in membrane biology, is analyzed in side-chain analogs of gramicidin A channels. In symmetrical 0.1 N HCl solutions, fluorination of channel Trp(11), Trp-(13), or Trp(15) side chains is found to inhibit proton transport, and replacement of one or more Trps with Phe enhances proton transport, the opposite of the effects on K(+) transport in lecithin bilayers. The current-voltage relations are superlinear, indicating that some membrane field-dependent process is rate limiting. The interfacial dipole effects are usually assumed to affect the rate of cation translocation across the channel. For proton conductance, however, water reorientation after proton translocation is anticipated to be rate limiting. We propose that the findings reported here are most readily interpreted as the result of dipole-dipole interactions between channel waters and polar side chains or lipid headgroups. In particular, if reorientation of the water column begins with the water nearest the channel exit, this hypothesis explains the negative impact of fluorination and the positive impact of headgroup dipole on proton conductance. 相似文献