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11.
Membrane resistance change of the frog taste cells in response to water and Nacl 总被引:2,自引:0,他引:2 下载免费PDF全文
The electrical properties of the frog taste cells during gustatory stimulations with distilled water and varying concentrations of NaCl were studied with intracellular microelectrodes. Under the Ringer adaptation of the tongue, two types of taste cells were distinguished by the gustatory stimuli. One type, termed NaCl-sensitive (NS) cells, responded to water with hyperpolarizations and responded to concentrated NaCl with depolarizations. In contrast, the other type of cells, termed water-sensitive (WS) cells, responded to water depolarizations and responded to concentrated NaCl with hyperpolarizations. The membrane resistance of both taste cell types increased during the hyperpolarizing receptor potentials and decreased during the depolarizing receptor potentials, Reversal potentials for the depolarizing and hyperpolarizing responses in each cell type were a few millivolts positive above the zero membrane potential. When the tongue was adapted with Na-free Ringer solution for 30 min, the amplitude of the depolarizing responses in the NS cells reduced to 50% of the control value under normal Ringer adaptation. On the basis of the present results, it is concluded (a) that the depolarizing responses of the NS and WS cells under the Ringer adaptation are produced by the permeability increase in some ions, mainly Na+ ions across the taste cell membranes, and (b) that the hyperpolarizing responses of both types of taste cells are produced by a decrease in the cell membrane permeability to some ions, probably Na+ ions, which is slightly enhanced during the Ringer adaptation. 相似文献
12.
Molecular evidence for the rapid propagation of mouse t haplotypes from a single, recent, ancestral chromosome 总被引:11,自引:0,他引:11
Silver LM; Hammer M; Fox H; Garrels J; Bucan M; Herrmann B; Frischauf AM; Lehrach H; Winking H; Figueroa F 《Molecular biology and evolution》1987,4(5):473-482
Mouse t haplotypes are variant forms of chromosome 17 that exist at high
frequencies in worldwide populations of two species of commensal mice. To
determine both the relationship of t haplotypes to each other and the
species within which they exist, 35 representative t haplotypes were
analyzed by means of 10 independent molecular probes, including five DNA
clones and five polypeptide spots identified by means of two- dimensional
gel electrophoresis. All of the tested haplotypes were found to share
restriction fragments and polypeptide spots that are absent in mice
carrying wild-type forms of chromosome 17. This observation provides the
first direct evidence that all of the known t haplotypes are descendents of
a single ancestral chromosome. The absence of variation among t haplotypes
could mean that this ancestral chromosome existed relatively recently, in
which case it would be necessary to postulate introgressions of t
haplotypes across species lines to explain their presence in both Mus
domesticus and M. musculus. Alternatively, it is possible that the
ancestral chromosome existed prior to the split between M. domesticus and
M. musculus and that, by chance, our probes fail to detect polymorphisms
that exist among the t haplotypes. A further result of our analysis is the
characterization of a partial t haplotype in a wild population of Israeli
mice.
相似文献
13.
14.
Voloschin LM Althabe O Olivé H Diena V Repezza B 《Journal of reproduction and fertility》1998,114(2):219-224
The Fourier series was used to analyse the oral movements recorded by the orokinetogram during breastfeeding in human babies. This is a new method that allows recording of oral movements without introducing any extrinsic element between the nipple and the mouth of the baby. The advantage of displaying suckling activity after fast Fourier transform (FFT) is that this algorithm allows storage, quantification and frequency analysis of the oral movements throughout a suckling bout, which enables the total oral activity to be measured. Two types of oral movements are found: slow high amplitude (SHA) and fast low amplitude (FLA). FLA movements may be derived from peristaltic movements of the tongue that result in tickling stimuli to the mechanoreceptors of the nipple and milk expression. The frequency bandwidth of oral movements is wider (0-8 Hz) than has been described previously (0-3 Hz) and this is due to the presence of the FLA oral movements. An indirect measurement of the energy of oral movements during suckling is obtained by the pattern of energy distribution used in each individual frequency band by oral movements. This pattern changes in relation to the periods of continuous and intermittent suckling activity. SHA and FLA oral movements are more intense during continuous suckling. Statistical analysis showed a correlation between the energy of SHA and FLA waves throughout the suckling bout, and also that the highest level of energy during suckling activity is displayed during the first 2 min. The novel tools described in this paper allow investigation of the role of suckling stimulus in reflex hormone release and other mother-infant interactions. 相似文献
15.
16.
A parsimony analysis was performed on restriction sites at the Hba-ps4
pseudogene locus within one of four inversions associated with mouse t
haplotypes. The results suggest that all t haplotypes form a monophyletic
group and that the in (17)4 inversion originated before the radiation of
the Mus musculus species complex but after the divergence of the lineages
leading to M. spretus, M. abbotti, and M. hortulanus. A time frame based on
the evolutionary rate of mouse pseudogenes places the origin of this t
haplotype inversion at 1.5 Mya, or approximately 1.5 Myr after the origin
of the more proximal t complex inversion, in (17)2. The accumulated
evidence indicates that complete t haplotypes have been assembled in a
stepwise manner, with each of these inversions occurring on separate
chromosomal lineages and at different evolutionary times. In addition, the
evolutionary relationships of pseudogene sequences resulting from genetic
exchange between wild-type and t haplotype alleles were examined. Analysis
of sequences from the 5' and 3' sides of a putative site of recombination
resulted in cladograms with different topologies. The implications for
hypotheses concerning the evolutionary forces acting on t haplotypes and
their rapid propagation throughout worldwide populations of mice are
discussed.
相似文献
17.
Claribel Cruz-García Alison E Murray Jorge LM Rodrigues Jeffrey A Gralnick Lee Ann McCue Margaret F Romine Frank E Löffler James M Tiedje 《BMC microbiology》2011,11(1):64
Background
EtrA in Shewanella oneidensis MR-1, a model organism for study of adaptation to varied redox niches, shares 73.6% and 50.8% amino acid sequence identity with the oxygen-sensing regulators Fnr in E. coli and Anr in Pseudomonas aeruginosa, respectively; however, its regulatory role of anaerobic metabolism in Shewanella spp. is complex and not well understood. 相似文献18.
Carlos G PinheiroJr Eduardo LM Naves Pierre Pino Etienne Losson Adriano O Andrade Guy Bourhis 《Biomedical engineering online》2011,10(1):31
We have now sufficient evidence that using electrical biosignals in the field of Alternative and Augmented Communication is
feasible. Additionally, they are particularly suitable in the case of people with severe motor impairment, e.g. people with
high-level spinal cord injury or with locked-up syndrome. Developing solutions for them implies that we find ways to use sensors
that fit the user's needs and limitations, which in turn impacts the specifications of the system translating the user's intentions
into commands. After devising solutions for a given user or profile, the system should be evaluated with an appropriate method,
allowing a comparison with other solutions. This paper submits a review of the way three bioelectrical signals - electromyographic,
electrooculographic and electroencephalographic - have been utilised in alternative communication with patients suffering
severe motor restrictions. It also offers a comparative study of the various methods applied to measure the performance of
AAC systems. 相似文献
19.
20.
Hernández Pérez A E Cerna Chávez JC Delgado Ortiz M Beltrán Beache LM Tapia Vargas YM Ochoa Fuentes 《Phyton》2019,88(1):11-13
Mexico is the main producer, consumer and exporter
of avocado in the world, being Michoacan the main producer state
contributing more than 80% of the national production. There
are phytopathogens that decimate the production causing the
death of the tree. Root samples were collected in avocado trees
that showed the characteristic symptomatology of the disease
known as avocado sadness, the sampling was carried out in four
of the main avocado producing towns, in the state of Michoacan,
Mexico. The isolation consisted in sowing root tissue in Petri
dishes with V8®-PARPH culture medium, subsequently they were
identified morphologically and for species level it was determined
by molecular biology, with the PCR-ITS technique. Pathogenicity
tests were performed in triplicate with avocado seedlings with more
than six leaves. After 24 hours, the inoculated plants expressed
decay in the apical part, after 120 hours the leaves showed yellowing
and after 15 days there was a generalized wilt on the stem and
leaves, re-isolating the phytopathogen Phytopythium vexans.
This study confirms the first report of the oomycete P. vexans
affecting avocado trees in the most important producing region of
the Mexican Republic. 相似文献