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1.
The parasporal body of the mosquitocidal isolate (PG-14) of Bacillus thuringiensis subsp. morrisoni (BTM) contains five major proteins with molecular masses of, respectively, 27.3, 65, 128, 135, and 144 kDa. Proteins corresponding in mass to the first four of these also occur in the mosquitocidal strain, B. thuringiensis subsp. israelensis (BTI), and it is thought therefore that the mosquitocidal activity of both strains is due to these four proteins. In other studies it has been shown that each of these proteins exhibits from moderate to high toxicity to mosquitoes, though the specific toxicity of the 144 kDa protein in PG-14 to mosquitoes remains unknown. In the present study, two parasporal body mutants (M146 and M242) of PG-14 were developed growing the wild-type strain at 42 degrees C. The parasporal body of M146 contained less of the 65-kDa protein and was less toxic (LC50 = 108 ng/ml) to mosquitoes than the wild-type strain (LC50 = 8.3 ng/ml). The parasporal body of M242 consisted of a bipyramidal crystal composed of a 144-kDa protein that was not toxic to the mosquito, Aedes aegypti, but exhibited substantial toxicity (LC50 = 2.5 micrograms/ml) to the lepidopteran. Trichoplusia ni. Because the parasporal bodies of BTI and BTM PG-14 are similar in mosquitocidal toxicity on a weight basis, the latter results suggest the 144-kDa protein, though not mosquitocidal alone, can contribute to mosquitocidal, activity when in the presence of other mosquitocidal proteins. 相似文献
2.
Payant V; Abukashawa S; Sasseville M; Benkel BF; Hickey DA; David J 《Molecular biology and evolution》1988,5(5):560-567
Nuclear DNA was extracted from each of the eight species comprising the
Drosophila melanogaster species subgroup. Southern hybridization of this
DNA by using a molecular probe specific for the alpha-amylase coding region
showed that the duplicated structure of the amylase locus, first found in
D. melanogaster, is conserved among all species of the melanogaster
subgroup. Evidence is also presented for the concerted evolution of the
duplicated genes within each species. In addition, it is shown that the
glucose repression of amylase gene expression, which has been extensively
studied in D. melanogaster, is not confined to this species but occurs in
all eight members of the species subgroup. Thus, both the duplicated gene
structure and the glucose repression of Drosophila amylase gene activity
are stable over extended periods of evolutionary time.
相似文献
3.
2''-Deoxycoformycin Inhibition of Adenosine Deaminase in Rat Brain: In Vivo and In Vitro Analysis of Specificity, Potency, and Enzyme Recovery 总被引:1,自引:0,他引:1
2'-Deoxycoformycin (DCF), a potent inhibitor of adenosine deaminase (ADA), is increasingly used as a tool to investigate adenosine metabolism and neuromodulation. To advance further the usefulness of DCF for studies of purines in the CNS, we determined the inhibitory potency of this compound against ADA and adenylate deaminase (AMPDA) in brain, the rate of ADA recovery in various brain regions after single or repeated intraperitoneal DCF administrations, and the effect of DCF on several neurotransmitter synthetic enzymes. In vitro, the Ki values for inhibition of ADA and AMPDA were found to be 23 pM and 233 microM, respectively. In vivo, DCF inhibited ADA with ED50 values ranging from 155 to 280 micrograms/kg at 2 h posttreatment, and 98% inhibition was achieved with 1 mg/kg. AMPDA activity was not affected by doses up to 5.0 mg/kg. In contrast to the greater than 95% inhibition of ADA seen 1 day after DCF at 5 mg/kg, the effectiveness of a second similar DCF treatment on the activity that had recovered by 14 days was dramatically reduced. Eight days after DCF treatment with doses of 5-50 mg/kg, the degree of ADA activity recovery in 10 brain regions examined was similar; it averaged 35% of control values at the low dose but showed some heterogeneity, ranging from 15 to 54% of control values, at the higher doses. Forty days after treatment with a single dose of 5 mg/kg, ADA activity recovered by 68-78% of control values in brain regions with normally high levels of activity and by 44-59% of control values in other regions. The activities of choline acetyltransferase, glutamic acid decarboxylase, and histidine decarboxylase (an enzyme colocalized with ADA in hypothalamic neurons) were unaffected by DCF treatment, a result suggesting the lack of a generalized neurotoxic effect. The very low doses of DCF required for ADA inhibition in vivo are consistent with the high potency of this drug against ADA in vitro, and any physiological effects observed at low doses might therefore be ascribed to inhibition of ADA. 相似文献
4.
JOÃO BATISTA TAVARES DA SILVA ISAAC ROITMAN 《The Journal of eukaryotic microbiology》1990,37(6):521-523
ABSTRACT. Three strains of Phytomonas serpens two from tomatoes, Lycopersicon esculentum one from the insect Phtia picta (Hemiptera, Coreidae), were cultivated in a chemically defined medium developed from a defined medium for cultivating insect flagellates. Besides organic growth factors required by other insect trypanosomatids this flagellate requires, serine and inositol. Glutamine stimulates growth, and, surprisingly, does not require heme. 相似文献
5.
Abstract: [3H]Ryanodine binding to, as well as functions of, ryanodine receptor intracellular Ca2+ release channel complexes are modulated by several adenosine-based compounds. In this study, we determined the effects of endogenous compounds termed diadenosine polyphosphates (ApnAs; n = 2–6 phosphate groups) on [3H]ryanodine binding to membranes prepared from rat brain and skeletal and cardiac muscle. Under low ionic strength buffer conditions, [3H]ryanodine binding to brain membranes was significantly increased by 171% with 333 µMP1,P5-di(adenosine-5′) pentaphosphate (Ap5A) and by 209% with the same concentration of the metabolism-resistant ATP analogue βγ-methyleneadenosine 5′-triphosphate (AMP-PCP) compared with control values for [3H]ryanodine binding of 9.6 ± 1.8 fmol/mg of protein. Dose-related increases in [3H]ryanodine binding were observed for all five ApnAs tested [P1,P2-di(adenosine-5′) pyrophosphate (Ap2A), P1,P3-di(adenosine-5′) triphosphate (Ap3A), P1,P4-di(adenosine-5′) tetraphosphate (Ap4A), Ap5A, and P1,P6-di(adenosine-5′) hexaphosphate (Ap6A)] as well as AMP-PCP; oxidized salts of ApnAs stimulated [3H]ryanodine binding to a greater degree than did nonoxidized ApnAs. The apparent rank order for the capacity of these agents to increase [3H]-ryanodine binding was oxidized Ap4A = oxidized Ap5A > oxidized Ap3A > Ap6A > AMP-PCP > Ap5A > Ap2A. Addition of the approximate EC50 dose of oxidized Ap4A (37 µM) increased the affinity (KD) of ryanodine receptors from 34 ± 7 to 12 ± 2 nM; the apparent binding site density (Bmax) was not significantly different from control values of 107 ± 33 fmol/mg of protein. Increases in [3H]-ryanodine binding by either oxidized Ap4A or nonoxidized Ap5A were not further enhanced by coincubation with AMP-PCP, which suggests a similar site of action for the ApnAs and AMP-PCP. [3H]Ryanodine binding to skeletal and cardiac muscle membranes was enhanced by addition of oxidized Ap4A, Ap5A, and AMP-PCP. Oxidized Ap4A increased the specific binding by ninefold in skeletal muscle and by threefold in cardiac muscle. These results suggest that ApnAs, at physiologically relevant concentrations, may serve as endogenous modulators of ryanodine receptor-gated Ca2+ release channels. 相似文献
6.
MARC J. FAZIO ALBA C. DA SILVA THOM K. ROSIERE G. BENJAMIN BOUCK 《The Journal of eukaryotic microbiology》1995,42(5):570-580
ABSTRACT. Proteins of the membrane skeleton of Euglena gracilis were extensively phosphorylated in vivo and in vitro after incubation with [32 P]-orthophosphate or γ-[32 P] ATP. Endogenous protein threonine/serine activity phosphorylated the major membrane skeletal proteins (articulins) and the putative integral membrane protein (IP39) anchor for articulins. The latter was also the major target for endogenous protein tyrosine kinase activity. A cytoplasmic domain of IP39 was specifically phosphorylated, and removal of this domain with papain eliminated the radiolabeled phosphoamino acids and eliminated or radically shifted the PI of the multiple isoforms of IP39. In gel kinase assays IP39 autophosphorylated and a 25 kDa protein which does not autophosphorylate was identified as a threonine/serine (casein) kinase. Plasma membranes from the membrane skeletal protein complex contained threonine/serine (casein) kinase activity, and cross-linking experiments suggested that IP39 was the likely source for this membrane activity. pH optima, cation requirements and heparin sensitivity of the detergent solubilized membrane activity were determined. Together these results suggest that protein kinases may be important modulators of protein assembly and function of the membrane skeleton of these protistan cells. 相似文献
7.
Borrelia burgdorferi is a spirochete pathogen transmitted among warm-
blooded hosts by ixodid ticks. Frequency-dependent selection for variant
outer-surface proteins might be expected to arise in this species, since
rare variants are more likely to avoid immune surveillance in previously
infected hosts. We sequenced the OspA and OspB genes of nine North American
strains and compared them with nine strains previously described. For each
gene, the mean number of synonymous substitutions per synonymous site and
the mean number of nonsynonymous substitutions per nonsynonymous site show
only a twofold excess of silent mutations. Synonymous rates vary widely
along the OspB protein. Some regions show a significant excess of silent
substitutions, while divergence in other regions is constrained by biased
base composition or selection. The presence, in antigenically important
regions of the protein, of significant variation among strains, as well as
evidence for recombination among strains, should be considered in attempts
to develop vaccines against this disease.
相似文献
8.
M P ROBINSON G BUTCHER R H CURTIS K G DA VIES K EVANS 《The Annals of applied biology》1993,123(2):337-347
Two monoclonal antibodies, which differentially recognise the two species of potato cyst nematodes (PCN), Globodera pallida and G. rostochiensis, are described. They have been shown to have potential for quantification of these two species, recognising proteins of the same molecular weight (34 kD) in both species. Further investigation showed these proteins to have isoelectric points at pH values of 5.7 in G. pallida and 5.9 in G. rostochiensis, in common with the proteins used by Fleming & Marks (1983) to differentiate the species of PCN. They are likely to be structurally very similar, with the same physiological function (and therefore similar concentrations) in the two species. In cross-reactivity tests with a wide range of soil nematode species, the antibodies reacted strongly only with species of the genus Globodera, and thereby confirmed their potential as the basis of a quantitative immunoassay likely to be useful in management of PCN populations. 相似文献
9.
10.