摘要:

SummaryA recessive temperature-sensitive paralytic mutation,tip-E, is associated with reduced binding of [3H]saxitoxin to voltage-sensitive sodium channels in membranes from adultDrosophilaheads. There is a decrease of 30-40% in the number of [3H]saxitoxin-binding sites per mg protein (Bmax), but the dissociation constant (Kd) for [3H]saxitoxin binding is normal in the remaining population of binding sites. This decrease is not due to a general hypotrophy of neural tissue since the number ofα-bungarotoxin binding sites is normal intip-Emutants. Although saxitoxin binding is reduced in vitro, pharmacological experiments suggest thattip-Emutants have close to the wild-type number of sodium channels in vivo. This suggestion is supported by the observation that at permissive temperaturestip-Eonly marginally suppresses a mutation which causes enhanced membrane excitability. However, even at permissive temperaturestip-Einteracts synergistically with mutations that decrease membrane excitability. In this case, the double mutants exhibit reduced viability and/or longevity. We postulate that either the structure of sodium channels or their microenvironment is altered intip-Emutants resulting in an increased lability of binding sites in vitro.

ISSN:0167-7063    

DOI:10.3109/01677068609106891

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

SummaryIn previous work it was shown thatparats(paralyzed, temperature-sensitive,I-53.9) andnapts(no action potential, temperature-sensitive, 2-56.2), two temperature-sensitive paralytic mutations that block nerve conduction at restrictive temperatures, interact synergistically in double mutants causing unconditional lethality. This interaction is now shown to includetip-E(temperature-induced paralysis, 3-13.5), another temperature-sensitive paralytic mutation. There is an allele-dependent interaction betweentip-Eand variousparaalleles resulting in the unconditional lethality of the most extreme double mutant combinations. The pattern of this allele-dependency is strikingly different from that previously reported fornaptsandparain that theparaalleles that interact strongest withnaptsinteract weakest withtip-Eand vice-versa. Double mutants oftip-Ewithnaptsalso display greatly reduced viability. Surviving double mutants oftip-Ewith eitherparats1ornaptsare weak and exhibit enhanced temperature sensitivity for both paralysis and nerve conduction failure. In addition, in atip-Ebackground, mutantparaalleles enhance temperature-sensitive paralysis even when heterozygous withpara+. The results of these studies suggest thattip-Eshares related function withparaandnapIt is proposed thattip-E, likeparaandnapexerts an effect at some level on the structure, function, or stability of sodium channels.

ISSN:0167-7063    

DOI:10.3109/01677068609106892

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

SummaryGuided by genetic recombination experiments that placed the gene for theDrosophilamemory mutantamnesiacproximal toforkednearcarnation, we screened 7 deficiencies of the proximal X in an effort to more precisely localize theamnesiacmutation. After training with a classical conditioning procedure, two deficiency chromosomes,mal8andmal12, producedamnesiac-like memory deficits inDf/amnflies but not inDf/+ controls. In contrast, themal13,mal10,mal11,16-3-22andDCBIdeficiencies, in combination with eitheramnor + chromosomes, did not produceamnesiacmemory scores. These results indicate that theamnesiacgene lies between the left breakpoint ofmal12(19A1) and the left breakpoint ofmal13(19A1 or A2). This conclusion is supported by the fact thatamnmales carrying the Y-linked X-chromosome duplicationy+Ymal106(which spans 18F4-5 to 20A) produce wild-type learning and memory scores. Finally, the data suggest thatamnesiacis a complete loss of function (amorphic) mutation, becauseamn/amnandamn/Dfflies have similar learning and memory scores.

ISSN:0167-7063    

DOI:10.3109/01677068609106893

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

SummaryIn a previous report, it was shown that erythrocyte membranes from mice with muscular dystrophy of strain129/ReJ-dymanifest a unique antigen. In the current study, this antigen was enriched from solubilized membranes by a two-step solid phase immunoadsorbent. The enriched fraction retained antigenicity as well as a reduced set of electrophoretic forms of protein over that seen in solubilized membranes. The enriched fraction contained no novel molecular weight species but several were noticeably enriched, particularly at 54,000 daltons.

ISSN:0167-7063    

DOI:10.3109/01677068609106894

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor

摘要:

SummaryJoseph disease (JD) has only rarely been described in families of non-Portuguese ancestry. Two Indian families with an autosomal dominant inherited ataxia are described in this report. The clinical picture resembled the spectrum seen in JD. An interesting feature was the very early manifestation of the disease process in the third generations. Considerable phenotypic variation within one family was another important aspect. These families had always lived in northern India for the past many generations.

ISSN:0167-7063    

DOI:10.3109/01677068609106895

出版商:Taylor&Francis    

年代:1986

数据来源: Taylor