Dot-blot procedure with [32P]DNA probes for the sensitive detection of avocado sunblotch and other viroids in plants.

Avocado sunblotch viroid (ASBV) has been detected down to a level of about 20 pg per gram fresh weight of leaves by the use of a dot-blot hybridization procedure and partially purified nucleic acid extracts. Three [32P]DNA probes were compared, two prepared from full-length ASBV clones in the single-strand M13mp93 vector and the other by primer extension on purified ASBV. All three probes gave the same sensitivity of detection of ASBV.

The occurrence of the feline A blood group antigen on lymphocytes.

Sera from 300 cats were tested for the presence of anti-lymphocytic antibodies. One hundred and nineteen sera showed some activity with the majority (79) reacting only with lymphocytes from blood group A cats. Absorption of two such sera with A, AB and B erythrocytes and absorption of AB system reagents with lymphocytes from A and B blood group cats demonstrated that the A antigen is expressed on both erythrocytes and lymphocytes.

Nucleotide sequence of cucumber-mosaic-virus RNA 2 reveals a translation product significantly homologous to corresponding proteins of other viruses.

The nucleotide sequence of the 3035 residues of RNA 2 (Mr 1.03 X 10(6) ) of the Q strain of cucumber mosaic virus (CMV) was determined by sequencing M13 clones of the RNA 2 cDNA and by dideoxy sequencing using primers prepared either from M13 clones or by chemical synthesis. A single long open reading frame starts at the second AUG from the 5' end of RNA 2 and encodes 839 amino acids (Mr 94333).

Comparative sequence and structure of different isolates of citrus exocortis viroid.

The nucleotide sequences of two new Australian isolates of citrus exocortis viroid (CEV), CEV-DE25 and CEV-DE26, have been determined and compared with the previously sequenced Australian isolate, CEV-A (J. E. Visvader, A.

Acute changes in thyroid function tests following ingestion of thyroxine.

The timing of blood sample collection in relation to ingestion of thyroxine has been thought to be of no consequence in the assessment of patients receiving thyroxine medication. We have investigated changes in serum thyroid hormones after oral ingestion of thyroxine. Therapeutic doses of thyroxine (100-300 micrograms) were given to five normal, euthyroid subjects and eleven patients receiving long-term thyroxine-replacement medication.

Hormones in saliva: mode of entry and consequent implications for clinical interpretation.

Assay of hormones in saliva would be more convenient than assay in blood, but there is no information on the route by which hormones enter saliva, information that would provide insight into the clinical value of such assays. We have examined the mode of entry of various hormones into saliva. The results suggest that unconjugated steroids enter saliva by diffusing through the cells of the salivary glands and that their concentration in saliva does not depend on the rate of saliva production.

Studies on the accuracy of a quantitative kit radioimmunoassay for free thyroxine.

Experiments designed to determine the accuracy of the Corning Immophase Free T4 assay revealed that there was a marked perturbation of thyroxine binding to the serum proteins during the assay; binding of 125I-T4 to the immobilised T4 antibody in the absence of merthiolate increased considerably with buffer dilution of serum; and the free thyroxine concentration declined significantly during pregnancy. These changes in measured fT4 were not observed with an equilibrium dialysis-radioimmunoassay procedure. The assay was precise, easily performed, and as effective as the free thyroxine index (FTI) in diagnosing thyroid disease.

Satellite RNA of cucumber mosaic virus forms a secondary structure with partial 3'-terminal homology to genomal RNAs.

Sat-RNA is one of several replicating satellite RNAs which have been isolated from RNA encapsidated in cucumber mosaic virus (CMV) and which are totally dependent on CMV for replication. The 336 residue sequence of Sat-RNA obtained using the dideoxynucleotide chain termination and partial enzymic digestion procedures shows only a few short stretches (up to 11 residues) of sequence homology with one of the three CMV genomal RNAs so far sequenced. Sat-RNA has 88% sequence homology with another, previously sequenced, satellite RNA of CMV, CARNA 5.

Highly purified cucumber mosaic virus-induced RNA-dependent RNA polymerase does not contain any of the full length translation products of the genomic RNAs.

The extensively purified RNA-dependent RNA polymerase (RNA replicase) induced by infection of cucumber seedlings with cucumber mosaic virus (CMV) was investigated to determine whether the enzyme contains full-length translation products of the CMV genomal RNAs. Two experimental approaches were used. (1) RNA replicase preparations from plants infected with three strains of CMV (Q, P, and T) all had almost identical polypeptide compositions, which included a major polypeptide of relative mobility on sodium dodecyl sulfate-polyacrylamide gels of Mr, 100,000, and two other proteins, Mr 110,000 and Mr, 35,000, present in smaller, varying amounts.

Cucumber mosaic virus RNA 3. Determination of the nucleotide sequence provides the amino acid sequences of protein 3A and viral coat protein.

The complete sequence of the 2193 residues of RNA 3 (Mr 746000) of cucumber mosaic virus (Q strain) was determined by a combination of chemical and enzymic sequencing techniques utilizing cloned DNA fragments. The nucleotide sequence of RNA 3 also gave the complete sequence of 1027 residues of RNA 4 (Mr 349000), which codes for the viral coat protein and is derived from the 3' end; there are 53 untranslated nucleotides at the 5' end of RNA 4. The nucleotide sequence provided the amino acid sequences of the two proteins coded for by RNA 3: the 5'-terminal 3A protein with 333 amino acids (Mr 36700) and the 3'-terminal viral coat protein with 236 amino acids (Mr 26200).

Comparative sequence and structure of viroid-like RNAs of two plant viruses.

A newly discovered group of spherical plant viruses contains a bipartite genome consisting of a single-strand linear RNA molecule (RNA 1, Mr 1.5 x 10(6) ), and a single-strand, covalently closed circular viroid-like RNA molecule (RNA 2, Mr approximately 125,000). The nucleotide sequences of the RNA 2 of two of these, velvet tobacco mottle virus and solanum nodiflorum mottle virus, have been determined.

Effectiveness of analysis of free thyroxin concentration in serum for diagnosis of covert thyroid disease.

The indirect indices of free-thyroxin concentration (fT4) are of limited effectiveness in diagnosing covert (mild) thyroid disease. We compared measurements of fT4 and of normalized T4 (NT4, the effective thyroxin ratio) in a group of patients being treated for thyroid disease, most of whom were clinically euthyroid. Although fT4 values correlated well with NT4, many of the patients (34% in one of the comparisons) had fT4 and NT4 values that gave different indications of thyroid status.

Avocado sunblotch viroid: primary sequence and proposed secondary structure.

The sequence of the 247 nucleotide residues of the single strand circular RNA of avocado sunblotch viroid (ASBV) was determined using partial enzymic cleavage methods on overlapping viroid fragments obtained by partial ribonuclease digestion followed by 32p-labelling in vitro at their 5'-ends. ASBV is much smaller than potato spindle tuber viroid (PSTV; 359 residues) and chrysanthemum stunt viroid (CSV; 356 residues). A secondary structure model for ASBV is proposed and contains 67% of its residues base paired.

Cucumber mosaic virus-induced RNA replicase: solubilization and partial purification of the particulate enzyme.

Cucumber seedlings infected with cucumber mosaic virus (CMV) contain a virus-induced RNA-dependent RNA polymerase (RNA replicase) in both soluble and particulate fractions of plant extracts; no such activity is found in uninfected plants. The extensive purification and characterization of the soluble RNA replicase has been described (R. Kumarasamy and R.

The RNAs of cucumoviruses: 3'-terminal sequence analysis of two strains of tomato aspermy virus.

The sequences of 189 residues from the 3' terminus of three RNAs of one strain and two RNAs of another strain of tomato aspermy virus have been determined; there was almost complete sequence homology between the RNAs. A base-paired transfer RNA-like structure is proposed for tomato aspermy virus RNAs which is similar in many aspects to the structure proposed for the 3'-terminal 172 residues of RNA 4 of the Q-strain of cucumber mosaic virus (R. H.

Chrysanthemum stunt viroid: primary sequence and secondary structure.

The sequence of the 356 nucleotide residues of chrysanthemum stunt viroid (CSV) has been determined. Overlapping linear viroid fragments were obtained by partial ribonuclease digestion, radiolabelled in vitro at their 5'-ends, and sequenced using partial enzymic cleavage methods. Of the CSV sequence, 69% is contained in the published sequence of potato spindle tuber viroid (PSTV).

Nucleotide sequence homology of thirteen tobamovirus RNAs as determined by hybridization analysis with complementary DNA.

The extent of RNA sequence homology between 13 isolates of tobamoviruses has been estimated by hybridization analysis using radioactive complementary DNA. Hybrid formation between complementary [3H]DNA prepared against 7 of the tobamovirus RNAs and the RNAs of the 13 isolates was assayed with the single-strand-specific S1 nuclease. The presence of mismatched regions in the DNA: RNA hybrids was shown by variation of the stringency of the conditions for the hybridization and S1 nuclease assay.

Cleavage of DNA.RNA hybrids by type II restriction enzymes.

The action of a number of restriction enzymes on DNA.RNA hybrids has been examined using hybrids synthesised with RNAs of cucumber mosaic virus as templates. The enzymes EcoRI, HindII, SalI, MspI, HhaI, AluI, TaqI and HaeIII cleaved the DNA strand of the hybrids (and possible also the RNA strand) into specific fragments.

The effects of iopodate on the serum iodothyronine pattern in normal subjects.

The ingestion by normal subjects of 3 g of sodium iopodate, which is widely used in routine oral cholecystography, resulted in significant decreases of serum total and free T3 to a nadir on day 4 which averaged 43% and 40%, respectively, below initial mean values. Total and free rT3 increased markedly to a peak on day 3, 244% and 189%, respectively, above initial mean values. Total and free T4 and free T4 index rose to a maximum on day 4, but these changes were not statistically significant.

Characterization of a viroid associated with avocado sunblotch disease.

A viroid has been purified from avocado leaves infected by sunblotch disease and designated the avocado sunblotch viroid. It is a covalently closed circular RNA molecule with a molecular weight lower than that of chrysanthemum stunt viroid and citrus exocortis viroid while hybridization analysis with 32P-labeled complementary DNA indicated that it is a single RNA species. It could be detected as a stainable RNA band on polyacrylamide tube gel electrophoresis of partially purified extracts of only two of four avocado isolates with positive symptoms of sunblotch disease.