Computed tomography in dystrophia myotonica

The calves and thighs of ten patients with dystrophia myotonica and four normal controls were studied by CT. The morphology of the anterior and posterior muscle groups of the calf and the extensor, flexor and adductor groups of the thigh were studied and their attenuation values analysed. Clinical measurement of muscle force was compared with attenuation values in each muscle group. The principal morphological change observed in diseased muscle was fatty infiltration. The amount of fatty infiltration in the calf muscles paralleled the severity of clinically apparent disease. However, in the thigh, fatty infiltration was observed in the extensors of three of the five patients who clinically had involvement of calf muscles alone. Detailed analysis of attenuation values was no better in detecting diseased muscle except of the adductor group of the thigh in those patients with both proximal and distal lower limb involvement. Comparison between muscle force and attenuation values showed a significant correlation in only the anterior muscle group of the calf in the normal controls and in those patients with clinically apparent disease of the calf muscles alone.

Classification of several tobamoviruses isolated in China on the basis of the amino acid composition of their virion proteins

The amino acid compositions of the virion proteins of several tobamoviruses isolated in China were determined. A classification computed from these and published data of other tobamoviruses was compared with published data of their relatedness assessed using the cDNA:RNA molecular hybridization technique. The classifications are clearly congruent; that based on amino acid composition appears to be best for determining the hierarchical relationships of members within a taxonomic group, rather than for distinguishing between closely related members, whereas nucleic acid hybridization unequivocally places a virus into the appropriate subgroup but is less useful for determining distant relationships.

Studies on alfalfa mosaic virus and alfalfa aphids

Alfalfa mosaic virus (AMV), the only sap-transmissible virus detected in a limited survey of lucerne crops in New South Wales and the Australian Capital Territory, is more common and widespread now than 10 years ago. Twenty-four of 35 lucerne crops and test plots we sampled were infected; from 25 % to over 55 % of plants were infected in plots and crops at Ginninderra, A.C.T. Seven of 10 commercial lucerne seed lots (eight of them imported directly from the U.S.A.) contained seedborne AMV, which infected from 0.4 to 1.9% of seedlings. The three lucerne aphids, the bluegreen aphid (Acyrthosiphon kondoi), pea aphid (A. pisum) and the spotted alfalfa aphid (Therioaphis trifolii f. maculata), all transmitted AMV in the non-persistent manner. Feeding-preference tests indicate that spotted alfalfa aphids prefer to feed on AMV-infected Siriver lucerne than on healthy Siriver, but they do not discriminate between healthy and AMV-infected Hunter River lucerne. The implications of these results are discussed.

Intrabronchial metastases from renal carcinoma with recurrent tumour expectoration

Three patients are described who presented to their doctors with a history of coughing up pieces of tissue. These took the form of large bronchial casts and consisted of intrabronchial deposits of clear cell carcinoma. In one patient the pulmonary symptoms preceded the finding of a primary renal carcinoma by four years. The other two patients had undergone nephrectomy for renal carcinoma 13 and four years previously. Expectoration of intrabronchial tumour should alert the physician to the possibility of metastasis from clear cell carcinoma of the kidney.

The effect of white clover mosaic virus on nodulation of white clover (Trifolium repens L. cv. Ladino)

White clover mosaic virus infection of Ladino clover seedlings resulted in decreased plant weight and a 71 % decrease in the number of nodules per plant without the decrease in nodule size which is usually observed when legumes are virus-infected. Nodule numbers decreased both on plants nodulated with an effective strain and on those with an ineffective strain of Rhizobium.

How ancient are the tobamoviruses?

The amino acid sequences of the virion proteins of 7 definitive tobamoviruses have been compared. The results show that the proteins may be arranged unequivocally in a single dendrogram which, by analogy with similar comparisons of other sets of homologous proteins, probably reflects their phylogeny. The magnitude of the differences between these sequences suggests that the tobamoviruses are at least as old as flowering plants. The sequence differences are significantly correlated with serological differences and with differences in amino acid composition, and so the latter was used to compute a classification of 13 tobamoviruses that also probably reflects their phylogeny. The possible ages of several other virus groups are discussed.

The relationship of certain tymoviruses assessed from the amino acid composition of their coat proteins

The amino acid composition of the coat proteins of the following viruses is reported: Andean potato latent, clitoria yellow vein, desmodium yellow mottle, dulcamara mottle, eggplant mosaic, okra mosaic, ononis yellow mosaic, scrophularia mottle, and, as controls, cocksfoot mild mosaic and cocksfoot mottle viruses. These data, together with some already published, were used to compute classifications of the tymoviruses. These classifications show a general similarity to Koenig's serological classification of the tymoviruses, but the correlation is poor, unlike similar comparisons of tobamovirus classifications. Several possible reasons for the poor correlation have been examined and excluded, and its implications are discussed.

A plant virus that partially protects its wild legume host against herbivores

Seedlings of Kennedya rubicunda were manually inoculated with Kennedya yellow mosaic virus and planted along with comparable virus-free seedlings in a coastal bushland site where the plant and virus were common. Virus infection decreased the growth rate of the plants by about one-third; however, virus-free plants disappeared more than twice as quickly as infected plants as a result of grazing by herbivores. In palatability trials using grated carrot bait, caged young rabbits preferred bait mixed with powdered virus-free K.rubicunda leaves to that mixed with virus-infected leaf powder. However, 'polyamine extracts' of the leaves did not have a comparable effect.

Particles produced during a mixed infection by two tobamoviruses contain coat proteins of both viruses

Particles from plants mixedly infected with two tobamoviruses, whose particles differ in density, were all of a single, intermediate density, suggesting that they contain both coat proteins and that the proteins occur in the same proportion in all particles. Plants inoculated with the genome-containing particles of one of the tobamoviruses together with the noninfective, short, coat protein messenger-containing particles of the other yielded only particles with the density of the first;.there was no evidence of complementation.

Mixed infection with two tobamoviruses: the formation of particles containing the coat protein messenger RNAs of either virus

Plants mixedly infected with the U2 strain of tobacco mosaic virus (T2MV) and sunnhemp mosaic virus (SHMV) and grown at 35 degrees, yield particles of the same modal lengths (300 and 40 nm) as those found in plants singly infected with SHMV, but not in plants infected with T2MV, which yield only the long particles. At least some of the particles produced in mixedly infected plants contain coat proteins of both viruses. When RNAs from these particles are translated in vitro the coat proteins of both viruses are produced, although when a mixture of RNAs from particles of SHMV and T2MV, grown separately, are translated in vitro only SHMV protein is produced. These and other results suggest that the short particles produced in mixedly infected plants contain both coat protein messengers.

Translation in vitro of artificially produced fragments of a tobamovirus genome

Particles of the U2 strain of tobacco mosaic virus (TMV) were partly disassembled by SDS, treated with RNases and then phenol, and yielded RNA molecules one quarter to half the size of the intact virus genome. These molecules, when translated in vitro, produced the coat protein of the virus. Reassembly experiments indicated that the active messenger molecules were those that most rapidly reassembled with coat protein; the rate of reassembly was greatly diminished by treatment with spleen phosphodiesterase. Particles of sunnhemp mosaic virus (the bean strain of TMV) resist disassembly by detergent much more than those of the U2 strain of TMV.

On the nature of the difference in the densities of the particles of two tobamoviruses

Particles of sunnhemp mosaic virus (SHMV) are denser than those of the U2 strain of tobacco mosaic virus (T2MV) when their densities are estimated by equilibrium centrifugation in gradients of either cesium chloride or Metrizamide; in cesium chloride the densities are 1.318 and 1.307 g/ml, and in Metrizamide they are 1.249 and 1.240 g/ml. Experiments with particles reassembled from homologous or heterologous mixtures of the RNAs and coat proteins of the viruses show that the difference in their densities is determined by their coat proteins. The disassembled coat proteins of the two viruses have the same density, but polymerized SHMV protein is less dense than polymerized T2MV protein. Particles reassembled from homologous or heterologous mixtures of the RNAs and coat proteins of the viruses have the density of the nucleoprotein particles used as the source of protein. The density difference of the two virus nucleoproteins therefore reflects the different behavior of the two proteins on assembly with RNA.

A correlation between the genome compositions of bacteriophages and their hosts

The base composition of the genomes of bacteriophages and other viruses is, in a very general way, related to the base composition of the genomes of their hosts by the statistically significant linear regression: (phage GC%)=9.12 + 0.74 (host GC%). The significance and possible use of this relationship is discussed.

In vitro translation of polyribosome-associated RNAs from tobamovirus-infected plants

RNAs associated with polyribosomes in plants infected with the U2 strain of tobacco mosaic virus (TMV) or with sunnhemp mosaic virus have been isolated. Most are about 0.35 X 10(6) daltons in weight. They translate efficiently in vitro to produce their respective coat proteins which were identified by their serological behavior and peptide composition. They also reassemble in vitro with coat protein. The coat protein of sunnhemp mosaic virus reassembles more quickly than that of TMV U2.

Soybean virus Z: its characteristics and taxonomy

Soybean virus Z is a hitherto undescribed virus of soybeans found in Australia. It has a limited host range, attains a low concentration in plants and has a thermal inactivation point of 65 degrees. It has flexuous filamentous particles with a modal length of 610 nm and forms amorphous inclusions, but no pinwheels, in infected cells. It has not been transmitted by aphids or by seed. Its genome is RNA with the composition G23, A26, C25, U26, and its coat protein weights about 2.7 X 104. This virus seems to be unrelated to previously described viruses of soybeans, and does not fall into any of the described virus groups with similar particles.

Stimulation of liver 5-aminolaevulinate synthetase by drugs and its relevance to drug-induced accumulation of cytochrome P-450. Studies with phenylbutazone and 3,5-diethoxycarbonyl-1,4-dihydrocollidine

The relevance of the stimulation of 5-aminolaevulinate synthetase to the accumulation of cytochrome P-450 after administration of drugs was examined in rats treated with phenylbutazone and with 3,5-diethoxycarbonyl-1,4-dihydrocollidine. 3,5-Diethoxycarbonyl-1,4-dihydrocollidine alone stimulated 5-aminolaevulinate synthetase without increasing the concentration of cytochrome P-450, whereas phenylbutazone alone increased the microsomal cytochrome P-450 without significantly affecting the activity of the enzyme. When the two drugs were given together both effects were found. It is concluded that if an increased amount of 5-aminolaevulinate and haem must be made to provide for the accumulation of cytochrome P-450, it need only be a small amount. It is also concluded from these findings that stimulation of the drug-metabolizing system on the one hand and marked enhancement of 5-aminolaevulinate synthetase activity and porphyria on the other are likely to result from different actions of the drugs. Evidence is presented suggesting that porphyrogenic drugs stimulate markedly the activity of 5-aminolaevulinate synthetase by lowering the concentration of haem in the liver, thereby decreasing the normal feedback control. With 3,5-diethoxycarbonyl-1,4-dihydrocollidine a rapid inhibition of mitochondrial ferrochelatase and of liver haem synthesis may be the primary mechanism involved.