Crown-gall tumors possess tumor-specific antigenic sites on their cell walls

Rabbits were injected with cell walls obtained from crown-gall tumor tissue or the corresponding cell walls from normal potato tissue. The serum obtained from rabbits 53 days after they were injected with tumor cell walls contained immunoglobins that reacted with both tumor and normal cell walls as well as with the cells from the inciting strain of Agrobacterium tumefaciens. When this serum was repeatedly absorbed against normal cell walls and the cells of the inciting strain of Agrobacterium tumefaciens, only tumor-specific immunoglobins remained. These immunoglobins did not react with cell walls obtained from meristematic (nontumorous) potato tissue. Yet this same serum reacted with crown-gall tumor cell walls obtained from turnip and carrot discs.     

Length variation and secondary structure of introns in the Mlc1 gene in six species of Drosophila

A nearly universal feature of intron sequences is that even closely related species exhibit a large number of insertion/deletion differences. The goal of the analysis described here is to test whether the observed pattern of insertion/deletion events in the genealogy of the myosin alkali light chain (Mlc1) gene is consistent with neutrality, and if not, to determine the underlying forces of evolutionary change. Mlc1 pre-mRNA is alternatively spliced, and one constraint is that signals necessary for tissue-specificity of directed splicing must be conserved. If the total length of an intron is functionally constrained, then the distribution of indels on branches of the gene genealogy should reflect a departure from randomness. Here we perform a phylogenetic analysis, inferring ancestral states wherever possible on a phylogeny of 29 alleles of Mlc1 from six species of Drosophila. Observed patterns of indels on the genealogy were compared to those from simulated data, with the result that we cannot reject the null hypothesis of neutrality. A clear departure from a neutral prediction was seen in the excess folding free energy predicted for the introns flanking the alternatively spliced exon. Relative rate tests also suggest a retardation in the rate of Mlc1 sequence evolution in the simulans clade.      

Conservation of alternative splicing and genomic organization of the myosin alkali light-chain (Mlc1) gene among Drosophila species

The Mlc1 gene of Drosophila melanogaster encodes two MLC1 isoforms via developmentally regulated alternative pre-mRNA splicing. In larval muscle and tubular and abdominal muscles of adults, all of the six exons are included in the spliced mRNA, whereas, in the fibrillar indirect flight muscle of adult, exon 5 is excluded from the mRNA. We show that this tissue-specific pattern of alternative splicing of the Mlc1 pre-mRNA is conserved in D. simulans, D. pseudoobscura, and D. virilis. Isolation and sequencing of the Mlc1 genes from these three other Drosophila species have revealed that the overall organization of the genes is identical and that the genes have maintained a very high level of sequence identity within the coding region. Pairwise amino acid identities are 94%-99%, and there are no charge changes among the proteins. Total nucleotide divergence within the coding region of the four genes supports the accepted genealogy of these species, but the data indicate a significantly higher rate of amino acid replacement in the branch leading to D. pseudoobscura. A comparison of nucleotide substitutions in the coding portions of exon 5 and exon 6, which encode the alternative carboxyl termini of the two MLC1 isoforms, suggests that exon 5 is subject to greater evolutionary constraints than is exon 6. In addition to the coding sequences, there is significant sequence conservation within the 5' and 3' noncoding DNA and two of the introns, including one that flanks exon 5. These regions are candidates for cis- regulatory elements. Our results suggest that evolutionary constraints are acting on both the coding and noncoding sequences of the Mlc1 gene to maintain proper expression and function of the two MLC1 polypeptides.      

Role of interleukin-7 in degenerative and inflammatory joint diseases

IL-7 is known foremost for its immunostimulatory capacities, including potent T cell-dependent catabolic effects on bone. In joint diseases like rheumatoid arthritis and osteoarthritis, IL-7, via immune activation, can induce joint destruction. Now it has been demonstrated that increased IL-7 levels are produced by human articular chondrocytes of older individuals and osteoarthritis patients. IL-7 stimulates production of proteases by IL-7 receptor-expressing chondrocytes and enhances cartilage matrix degradation. This indicates that IL-7, indirectly via immune activation, but also by a direct action on cartilage, contributes to joint destruction in rheumatic diseases.     

The action of cyclic-AMP on GA3 controlled responses V. Similarities in the induction of isocitrate lyase in hazel seeds by gibberellic acid and cyclic 3',5'-adenosine monophosphate

Cyclic-AMP was found to promote the induction of isocitratelyase in hazel seeds. Similarities in the induction of thisenzyme by GA₃ and cyclic-AMP were found in the (1) total amountof enzyme produced, (2) the time course for the production ofthis enzyme, (3) the amount of enzyme secreted into the medium,and (4) the inhibition of enzyme production induced by ABA,cycloheximide and 6-methyl purine. Of a variety of nucleotidestested only cyclic-AMP consistently promoted high levels ofisocitrate lyase. Cyclic-AMP also promoted a similar increase in the fresh weightof the embryo to that obtained with GA₃ treated seeds. Thisinitial study is suggestive of the possibility that cyclic-AMPmay be involved in GA₃ mediated responses in hazel seeds. (Received May 4, 1973; )     

Cupin: A candidate molecular structure for the Nep1-like protein family

Background  

NEP1-like proteins (NLPs) are a novel family of microbial elicitors of plant necrosis. Some NLPs induce a hypersensitive-like response in dicot plants though the basis for this response remains unclear. In addition, the spatial structure and the role of these highly conserved proteins are not known.     

PROMOTION OF PERITHECIAL INITIALS IN MONACROSPORIUM DOEDYCOIDES BY 6–METHYL PURINE

The promotion of perithecial initials in the imperfect fungus Monacrosporium doedycoides is enhanced by the addition of the RNA synthesis inhibitor 6-methyl purine (6-MP). The addition of two other RNA inhibitors (8-azaguanine and actinomycin-D) causes the promotion of initials but not at the magnitude observed with 6-MP. Application of a protein synthesis inhibitor (cycloheximide), a base analog (5-fluorouracil), or an amino acid analog (p-fluorophenyl-alanine) are not promotive on initial formation and can be inhibitory. The apparent cause for the promotion of perithecial initials in the imperfect fungus is that sexual structures are inhibited by mRNA's synthesized by the organism and the addition of 6-MP prohibits their synthesis.     

Effects of cyclic-AMP on the formation of crown-gall tumors on the primary leaves of Phaseolus vulgris var. Pinto

Cyclic-AMP was found to inhibit the number of crown-gall tumorsthat developed on the primary leaves of Pinto beans by 30 to50%. A significant amount of inhibition was still observed whenthis nucleotide was added to the leaves up to 24 hr after theaddition of the bacterium. (Received September 17, 1974; )