摘要:

A new mutant ofParamecium letraureliahas been isolated with a profound defect in the regulation of membrane potential. This mutant,restless, hyperpolarizes as a potassium electrode below 8 mM external K+whereas wild-type cells can maintain a constant resting cell potential independent of low external K+concentration,restlessdies in solutions of low K+concentration in which wild-type can survive indefinitely.restlessis not allelic to mutations that affect the depolarization-dependent Ca2+current, the Ca2+-activated K+current, and the Ca2+-activated Na+current. The results suggest thatrestlessis a new class of mutant affecting a K+conductance hitherto not characterized genetically inParamecium.

ISSN:0167-7063    

DOI:10.3109/01677068509102321

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

Intracellular microelectrode recordings from the cervical giant fiber of normalDrosophilashow a characteristic action potential waveform for this identified neuron. The action potential has a rapid initial spike followed by a prominent depolarizing afterpotential. Pharmacological experiments suggest that the giant fiber action potential depends on inward currents carried by Na+and outward currents carried by K+.Abnormal action potentials are seen inShaker (Sh)mutantDrosophila. This study compares the effects of sixShalleles. In each case, abnormalities are limited to action potential repolarization. There are, however, allelic differences. Five alleles cause delayed repolarization and increased action potential durations. Going from most to least extreme, these alleles are:Sh102>ShKS133>ShM>ShE62>ShrKO120. Compared to normal action potentials, durations in the extreme mutants are longer by an order of magnitude or more. One mutant allele,Sh5appears to cause an incompletely repolarized action potential, rather than a repolarization delay.

ISSN:0167-7063    

DOI:10.3109/01677068509102322

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

Among the several methods that have been used to investigate the impact of environmental enrichment, on the behavior of an animal, the use of behaviorally deficient mutant mice has been especially useful. The use of this model allows one to investigate functional recovery compared to a known baseline (the normal animal) without the trauma and imprecision associated with surgical intervention.The present study extends a previous investigation that demonstrated a significant improvement in certain measures of the gait of the cerebellar mutant mouse staggerer, as a result of daily vestibular, muscular and visual stimulation. The results of the present study concerned the durability of that observed improvement. No clear-cut conclusion as to the permanency of the stimulation's effects could be drawn, because results differed according to the measures used. When tested two months after the end of the stimulation period the mutants ran more slowly, with as many“errors”as unstimulated mutants, leading one to infer a deletorious effect of the stimulation. On the other hand, if one considers only the number of“errors”during the test, one may conclude that early stimulation has a permanent advantageous effect of increasing the staggerer's receptivity to further stimulation. Other measures lead to more ambiguous conclusions.Finally, it is argued that even though true improvement in the staggerer's gait can be inferred from these results, and that at least some aspects of that improvement seem to be long-lasting, the generality of the findings cannot validly be extended beyond the precise experimental conditions.

ISSN:0167-7063    

DOI:10.3109/01677068509102323

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

A microlymphocytotoxicity test determined serologically the frequency of HLA antigens in 32 patients with Guillain-Barre syndrome and in 234 healthy control subjects. The results demonstrated significantly increased frequencies of A3 and B8. The relative risk was estimated to be 9.6 and 4.6 for the A3 and B8 antigens, respectively. Study of the gametic association revealed weak positive linkage disequilibrium and biological association. The results are discussed, and it is concluded that the aberrant genetic make-up of the patients makes them more susceptible to develop the syndrome after exposure to the environmental factor(s).

ISSN:0167-7063    

DOI:10.3109/01677068509102324

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor