A radioactive assay for acetylcholinesterase using anion-exchange disk

A radioactive assay for acetylcholinesterase is described. The assay is based on the separation of [¹⁴C]acetate from [¹⁴C]acetylcholine by differential adsorption of the former on DEAE anion-exchange disks. The procedure is simple and sensitive and eliminates the use of ion-exchange resin columns or organic extractions. Moreover, when unpurified enzyme preparations are assayed, linear steady-state kinetics can be observed with this method as contrasted to the nonlinear colorimetric method using acetylthiocholine and dithiobisnitrobenzoate. This method also permits the detection in biological samples of low levels of acetylcholinesterase activity, which is not detectable by the colorimetric method. Using the present radioactive method, cellular levels of acetylcholinesterase have been surveyed in N4TG1 neuroblastoma cells, NG108-15 neuroblastoma x glioma hybrid cells, H9c2 myoblasts, and 3T3-L1 and 3T3-C2 fibroblasts.     

A two-state recurrent stochastic model with time-dependent transition rates.

The two-state recurrent stochastic model with time-independent transition rates is generalized to a model with time-dependent transition rates. The rates can be any general function of external time, that is, any general function of the calendar time in which the process unfolds. Formulas for the state transition probabilities, the proportion of individuals in a particular state at time t, the distribution function, and the expectation of the number of individuals in a particular state at time t are derived.     

Enzyme loading in a solid support with nonuniform pore size distribution

The concept of pore size distribution is incorporated into the Clark model of enzyme immobilization in the present study. This refined model predicted that in the case of small harmonic pore radius with the same surface area and porosity of the support, more enzyme could be loaded in a support with nonuniform pores than that with uniform pores. In comparing the enzyme loading efficiency of the support with two different pore size distributions, the one with Gaussian distribution had the greater amount of enzyme immobilized than the other one with Rajagopalan's distribution. Furthermore, more enzyme could be loaded in a support with wider Gaussian pore size distribution than that with narrower distribution. The immobilized enzyme profile in the solid support with pore size distribution displayed a stepwise pattern which differed appreciably from the sigmoidal profile predicted for the support with uniform pore size. This stepwise enzyme distribution profile became sigmoidal with decreasing h(T) or increasing k. The new model could be used for designing protocols for an enzyme immobilization process.     

Seasonal history ofMacrocentrus grandii [Hym.: Braconidae] andEriborus terebrans [Hym.: Ichneumonidae], two parasitoids of the European corn borer,Ostrinia nubilalis [Lep.: Pyralidae]

The seasonal histories and phenological relationships of European corn borer,Ostrinia nubilalis (Hübner), and its 2 parasitoids,Macrocentrus grandii (Goidanich) andEriborus terebrans (Gravenhorst) were studied in southcentral Minnesota. Both parasitoids overwintered in mature borer larvae, broke diapause, completed development, and emerged at the same time as did borer adults. Thus the 1st generation parasitoids coincided with the peak abundance of their preferred larval instars of the 1st host generation. Both parasitoids had a 2nd generation, matching the bivoltinism ofO. nubilatis in Minnesota. The activity of 2nd generationE. terebrans was before the peak 2nd generation borer moth flight and was not synchronized with the peak abundance of 2nd generation borer larvae. The peak activity of 2nd generationM. grandii occurred after the peak 2nd generation borer moth flight and was fully synchronized with the peak abundance of 2nd generation borer larvae. Thus,M. grandii has both generations synchronized with the host seasonal history, and was the more effective of the 2 parasitoids.     

Location of ribosome-binding sites in the nin5 region of bacteriophage lambda

Seven ribosome-binding sites on DNA have been located within the region defined by the nin5 deletion as well as several ribosome-binding sites on each side of the nin5 region. These were mapped by electron microscopy relative to the end points of the nin5 deletion and two Tn903 transposons, one inserted into gene Rz and another inserted near gene Q. These ribosomes binding sites within the nin5 region may correspond to polypeptide initiation sites for up to seven new dispensible lambda genes.     

Anti-viral activity of 3-deazaadenosine and 5'-deoxy-5'-isobutylthio-3-deazaadenosine (3-deaza-SIBA)

3-Deazaadenosine and 5′-deoxy-5′-isobutylthio-3-deazaadenosine (3-deaza-SIBA) inhibits replication of both herpes simplex type 1 virus and the RNA type C virus, HL-23. Oncogenic transformation caused by SV40 and HL-23 are also blocked by either compound. Both compounds exhibit relatively low cytotoxicity at the anti-viral concentrations.     

Genetics of glucosephosphate isomerase in Aedes togoi (Diptera: Culicidae)

The genetics of glucosephosphate isomerase (E.C. 5.3.1.9) in two strains (Malaysian and Taiwan) of Aedes togoi is reported. Three electrophoretic phenotypes were present in both sexes. The zymogram patterns were identical in both strains of A. togoi. The phenotypes were governed by a pair of codominant alleles. The allele frequency of the slow-moving band was 0.63 in the Malaysian strain and was 0.86 and 0.82 in F161 and F169 generations, respectively, of the Taiwan strain. The sample studied was in good accord with Hardy-Weinberg expectations.