RAPID AXOPLASMIC TRANSPORT IN DYSTROPHIC MICE

Abstract— Rapid axoplasmic transport was studied in dystrophic mice of the 129/ReJ-dy strain. Proteins transported in vivo through α-motoneurons of the sciatic nerve were labeled by injections of [³H] or [³⁵S] amino acids into the ventral horn of the lumbar spinal cord. Following an 18 h incubation, axoplasmic transport was quantitated by summing the radioactivity in the 10 mm length of sciatic nerve proximal to a ligation. Although the amount of transported radioactivity was small, transport appeared depressed when adult dystrophic mice were compared to controls. Transport was also studied in the sensory fibers of the sciatic nerve under in vitro conditions, resulting in high levels of transported radioactivity. In this system transport was strongly depressed. The severity of the deficiency varied with age, being small in animals with early clinical signs and becoming maximal (80–90%) in animals over 60 days of age. Proteins transported by adult dy/dy and +/+ animals were compared by gel electrophoresis using double-label techniques. Transport of nearly all proteins was depressed in dy/dy mice, although the possibility exists that small differences occur. The data suggest that the dystrophic state produces a significant deficiency in rapid axoplasmic transport in both motor and sensory fibers, and may interfere with transport processes in all neurons. Since rapid axoplasmic transport has been associated with membranes, the data are consistent with a general alteration of cellular membranes in dystrophic animals.     

A noncycling activity assay for the omega subunit of Escherichia coli RNA polymerase.

We describe a new method for quantitatively assaying the omega subunit of Escherichia coli RNA polymerase. The assay is based on the ability of RNA polymerase holoenzyme to catalyze the continuous synthesis of the dinucleotide pApU on a poly[d(A-T)] . poly[d(A-T)] template when supplied with AMP and UTP as substrates. Core enzyme, lacking omega subunit, catalyzed this reaction at a rate less than 1% that of holoenzyme. The omega subunit was not released from the enzyme/DNA complex during dinucleotide synthesis. Using this assay, a titration of a fixed concentration of core enzyme was observed with increasing concentrations of added omega subunit. Below a 1:1 omega:core ratio the measured activity increased linearly with omega concentration, whereas above a 1:1 ratio the activity remained constant. An immediate application of the assay is in determining the concentration of active omega, or equivalently of active holoenzyme, in any RNA polymerase preparation.     

Effect of Oryzalin and 1,1-Dimethylpiperidinium Chloride on Cotton and Tomato Roots Infected with the Root-knot Nematode,Meloidogyne incognita

Oryzalin (3,5-dinitro-N4,N4-dipropyl-sulfanilamide) and BAS 083 (l,l-dimethylpiperdinium chloride) reduced root-knot infection in tomato roots when respectively applied as a soil drench at 20 ppm and 10,000 ppm. Oryzalin reduced knot counts with various intervals between treatment and inoculation. BAS 083 reduced knot counts only when applied before inoculation. Oryzalin was shown not to be a contact nematicide, and BAS 083 was only a weak one. Neither compound reduced penetration by infective larvae. Postinfection reduction in knot counts by Oryzalin and BAS 083 resulted, in part, from activation of natural defense mechanisms of the host. Giant-cell development in cotton roots inoculated with nematodes was inhibited by Oryzalin. Lateral root development was inhibited by BAS 083.     

Inhibition by styrylpyridines of purified rat and bovine brain choline acetyltransferase

Nine styrylpyridine analogs were tested as inhibitors of choline acetyltransferase which had been highly purified from rat cerebrum and bovine caudate nuclei. In general, concentrations required to achieve 50% inhibiion (I₅₀ values) were in the micromolar range. For some analogs, I₅₀ values were similar to those obtained previously by other investigators who used less purified enzyme preparations. With certain analogs, however, the measured values of I₅₀ changed as the transferase became more purified, which may indicate the presence in the extract of other molecules which can interact with the enzyme. The methods used in purification of the enzyme suggest that the molecule which modifies the activity of CAT is probably a protein. The mode of inhibition by naphthylvinylpyridinium was found to be uncompetitive with respect to both choline and acetyl coenzyme A for both the rat and bovine transferases.     

C-glycosylflavone accumulation in Sandoz 6706-treated barley seedlings is a photocontrolled response

Sandoz 6706 pretreatment of white light grown barley seedlings causes a 60% increase in saponarin (6-C-glucosyl-7-O-glucosylapigenin) but a 300% increase in lutonarin (3′-hydroxysaponarin). Norflurazon has little effect on saponarin levels but is almost as effective as Sandoz 6706 in enhancing lutonarin net synthesis. Barley roots contain saponarin and lutonarin only after herbicide treatment. Mung bean seedlings respond to Sandoz 6706 by accumulating higher levels of rutin and delphinidin 3-glucoside. The results are discussed in relation to the site of action of the herbicides, the High Energy photoresponse, and control of flavonoid 3′-hydroxylation.     

Parallel usage of medicinal plants by africans and their caribbean descendants

Cultivated plants are cited by anthropologists as important indicators of man’s past. Medicinal species, to a large extent, have been overlooked even though in some cases these plants represent some of the social and cultural traditions of the people who use them. A number of cultivated plants have been traced from the Old World to the New World and are generally believed to have been carried there by European explorers and early settlers. However, some evidence has been accumulating to indicate that there may have been contacts other than by European colonists. One trade route that has been neglected is that of the slave trade from west Africa to the Caribbean. Three plant species,Citrus aurantifolia, Ricinus communis andAbrus precatorius, may exemplify the role and use of this route. They also indicate the migration and assimilation of west African Fulani, Hausa, and Mandingo cultures and Obeah religion into Caribbean society.     

Action of the Style Product of the Self-Incompatibility Gene of Nicotiana alata (S-RNase) on in Vitro-Grown Pollen Tubes

The products of the S-locus expressed in female tissues of Nicotiana alata are ribonucleases (S-RNases). The arrest of growth of incompatible pollen tubes in styles may result from entry of the S-RNase into the pollen tube and degradation of pollen tube RNA. We investigated the action of isolated S-RNases on pollen tubes grown in vitro and found that S-RNase is taken up by the pollen without substantial alteration. The S-RNases inhibit incorporation of exogenously added radioactive amino acids into protein by the germinated pollen. The S-RNases also inhibit in vitro translation of pollen tube RNA in a wheat germ cell-free extract. We found no evidence for a specific mRNA substrate for the S-RNases, which implies that if RNase activity is involved in the control of self-incompatibility, allelic specificity is more likely to depend on the selective uptake of S-RNases into pollen tubes or their selective activation or inactivation by pollen factors, rather than cleavage of a specific substrate. Heat treating S2-RNase largely destroys its RNase activity but increases its inhibitory effect on in vitro pollen tube growth. This effect is not due to an increased uptake of S2-RNase by the pollen but is associated with a greatly enhanced accumulation of S2-RNase on the outer surface of the pollen grains.     

Reducing sugars can induce the oxidative inactivation of rhodanese.

The enzyme rhodanese (thiosulfate sulfurtransferase, EC 2.8.1.1) is inactivated on incubation with reducing sugars such as glucose, mannose, or fructose, but is stable with non-reducing sugars or related polyhydroxy compounds. The enzyme is inactivated with (ES) or without (E) the transferable sulfur atom, although E is considerably more sensitive, and inactivation is accentuated by cyanide. Inactivation of E is accompanied by increased proteolytic susceptibility, a decreased sulfhydryl titer, a red-shift and quenching of the protein fluorescence, and the appearance of hydrophobic surfaces. Superoxide dismutase and/or catalase protect rhodanese. Inactive enzyme can be partially reactivated during assay and almost completely reactivated by incubation with thiosulfate, lauryl maltoside, and 2-mercaptoethanol. These results are similar to those observed when rhodanese is inactivated by hydrogen peroxide. These observations, as well as the cyanide-dependent, oxidative inactivation by phenylglyoxal, are explained by invoking the formation of reactive oxygen species such as superoxide or hydrogen peroxide from autooxidation of alpha-hydroxy carbonyl compounds, which can be facilitated by cyanide.     

Recovery of parasitic nematodes from fish by digestion or elution.

Two methods, digestion and elution, were used to recover parasitic nematodes from 470 flatfish belonging to species in the family Pleuronectidae. Samples of similar fish were collected from market lots; half of each sample was subjected to digestion, and half was subjected to elution (sedimentation). The edible (flesh) and the inedible (viscera) portions of each fish were analyzed separately. The total number of nematodes recovered by digestion was 1,110, which was not significantly greater than the 922 nematodes recovered by elution. However, digestion recovered 1,062 nematodes of the anisakine genera Anisakis and Phocanema, which are potentially pathogenic for human consumers of raw of semiraw fish. This number is significantly greater than the 608 pathogenic nematodes recovered by elution. Digestion also recovered 242 more nematodes from the edible flesh than did elution. Conversely, more nonpathogenic nematodes were recovered by elution. Approximately half the fish (240) had been collected in Boston markets, and the other half (230) had been collected in San Francisco markets. Fish from San Francisco each contained an average of eight nematodes, and those from Boston contained an average of less than one nematode per fish.