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M D Marks

Publications and source records attributed to M D Marks.

26 records · Page 2Linked to original sources
PubMed1987

A Dinitroaniline-Resistant Mutant of Eleusine indica Exhibits Cross-Resistance and Supersensitivity to Antimicrotubule Herbicides and Drugs.

A dinitroaniline-resistant (R) biotype of Eleusine indica (L.) Gaertner. (goosegrass) is demonstrated to be cross-resistant to a structurally non-related herbicide, amiprophosmethyl, and supersensitive to two other classes of compounds which disrupt mitosis. These characteristics of the R biotype were discovered in a comparative test of the effects of 24 different antimitotic compounds on the R biotype and susceptible (S) wild-type Eleusine. The compounds tested could be classified into three groups based upon their effects on mitosis in root tips of the susceptible (S) biotype. Class I compounds induced effects like the well known mitotic disrupter colchicine: absence of cortical and spindle microtubules, mitosis arrested at prometaphase, and the formation of polymorphic nuclei after arrested mitosis. The R biotype was resistant to treatment with some class I inhibitors (all dinitroaniline herbicides and amiprophosmethyl) but not all (e.g. colchicine, podophyllotoxin, vinblastine, and pronamide). Roots of the R biotype, when treated with either dinitroaniline herbicides or amiprophosmethyl, exhibited no or only small increases in the mitotic index nor were the spindle and cortical microtubules affected. Compounds of class II (carbamate herbicides and griseofulvin) cause misorientation of microtubules which results in multinucleated cells. Compounds of class III (caffeine and structually related alkaloids) cause imcomplete cell walls to form at telophase. Each of these last two classes of compounds affected the R biotype more than the S biotype (supersensitivity). The cross-resistance and high levels of resistance of the R biotype of Eleusine to the dinitroaniline herbicides and the structurally distinct herbicide, amiprophosmethyl, indicate that a mechanism of resistance based upon metabolic modification, translocation, or compartmentation of the herbicides is probably not operative.

Journal Article↗
PubMed1985

Quantitative analysis of the accumulation of Zein mRNA during maize endosperm development.

In order to characterize the heterogeneity and expression of maize zein genes, we constructed and characterized a cDNA library of endosperm mRNAs. Clones from the library that were of sufficient size to be full-length or near full-length copies of zein mRNA were characterized by restriction enzyme mapping and cross-hybridization analysis. Based on these comparisons we found three classes of zein sequences corresponding to proteins of Mr 22,000, five corresponding to proteins of Mr 19,000, and a single one corresponding to a protein of Mr 15,000. Representative clones from these nine groups were used as probes to measure levels of the corresponding mRNAs in developing endosperms. It was found that these groups represent varying amounts of transcripts that range from 2 to 20% of the total endosperm mRNA population. For the Mr 19,000 and Mr 22,000 zein clones there is a correlation between the amount of mRNAs and the apparent number of genes in the genome. The relative level of mRNA for the Mr 15,000 zein was found to be 3 times that of the Mr 22,000 and Mr 19,000 zeins, suggesting that these genes are transcribed at a higher rate during endosperm development or that their mRNAs are more stable.

DNA↗
PubMed1985

Nucleotide sequence analysis of zein mRNAs from maize endosperm.

A comparison of the DNA and protein sequences of a group of zein cDNA clones reveals that they share extensive sequence homology and probably originated from a common ancestral gene. A comparison of clones corresponding to Mr 22,000 polypeptides shows they are 92% homologous, while five clones corresponding to the Mr 19,000 zeins vary in homology from 75 to 95%. The clones corresponding to the Mr 22,000 proteins are 60-65% homologous to clones encoding the Mr 19,000 zein proteins. A clone corresponding to the Mr 15,000 zein has little homology to either the Mr 22,000 or 19,000 zeins. Clones corresponding to both the Mr 22,000 and 19,000 zeins have two putative polyadenylation signals. S1 nuclease mapping indicates that the first polyadenylation signal following the stop codon is utilized by the Mr 22,000 sequences, while primarily the second polyadenylation signal is utilized by the Mr 19,000 sequences.

Amino Acid Sequence↗
PubMed1985

Assignment of the temperature-sensitive lesion in the replication mutant A1 of vesicular stomatitis virus to the N gene.

The replication defect in the temperature-sensitive mutant A1 of the New Jersey serotype (Hazelhurst subtype) of vesicular stomatitis virus was confirmed by the absence of intracellular nucleocapsids in infected cells incubated at the restrictive temperature. After preamplification, the relative yield of the A1 N protein accumulated intracellularly after 1 h of incubation at the restrictive temperature was decreased by 50% that of the wild-type or revertant A1 N protein. This difference was not as apparent in pulse-chase experiments. The functional lesion in A1 was correlated with a structural alteration in the N protein on the basis of the thermolability of the template activity of the A1 N protein-RNA complex in in vitro transcription reactions and the covariance of this phenotype with the temperature-sensitive phenotype in a spontaneous A1 revertant. This correlation was consistent with a direct role of the N protein in replication and allowed the assignment of the N gene to complementation group A.

Animals↗
PubMed1984

Functional relationships within the New Jersey serotype of vesicular stomatitis virus: genetic and physiological comparisons of the Hazelhurst and Concan subtypes.

Seventeen temperature-sensitive mutants of the Concan subtype of the New Jersey serotype of vesicular stomatitis virus have been isolated following mutagenesis and assigned to two complementation groups: CC/A, containing three mutants, and CC/B, containing 14 mutants. Prototype mutants of these two Concan groups efficiently complemented prototype mutants of the Hazelhurst complementation groups (with the exception of the corresponding group) which correspond to genes specifying the L, N, M and NS proteins. The pattern of intersubtypic complementation allowed the correlation of the Concan CC/B group with the Hazelhurst B group (L gene) and of the Concan CC/A group with the Hazelhurst A group (N gene). In contrast, the Concan prototype mutants failed to complement the prototype mutant of each of the five Indiana complementation groups for which genetic assignments have been made. The partitioning of intracellular nucleocapsids of the Concan and Hazelhurst subtypes during isolation was identical, and distinct from that of Indiana serotype intracellular nucleocapsids. The M protein of the Concan, but not of the Hazelhurst, subtype was observed to migrate as a doublet on SDS-polyacrylamide gels electrophoresed in a phosphate buffer.

Animals↗
PubMed1982

Analysis of sequence microheterogeneity among zein messenger RNAs.

We have synthesized cDNA clones for maize zein proteins using mRNAs purified from developing endosperm. Analysis of these clones by in vitro translation of hybrid-selected mRNAs suggested differences in sequence homology among the mRNAs for the different molecular weight zein polypeptides. These differences were also apparent in restriction maps of clones corresponding to the Mr = 22,000, 19,000, and 15,000 zeins. Using radioactive cDNA inserts as probes, we measured the extent of sequence homology among zein clones with a sensitive dot hybridization procedure. By this analysis, it was possible to distinguish clones corresponding to the different molecular weight zeins at low (Tm - 49 degrees C) to moderate (Tm - 35 degrees C) criteria, while under more stringent conditions (Tm - 20 degrees C), distinctions could be made between zein sequences within a molecular weight group. This analysis distinguish three different mRNAs for each of the Mr = 22,000 and Mr = 19,000 zeins, but only one was detected for the Mr = 15,000 zein. Comparison of the nucleotide sequences of clones for the Mr = 22,000 and Mr = 19,000 zeins showed about 60% homology throughout the coding regions. This analysis also revealed the presence of short repetitive nucleotide sequences corresponding to tandem repeats of approximately 20 amino acids in both groups of proteins.

Amino Acid Sequence↗
PubMed1982

A structural model for maize zein proteins.

With the knowledge of the amino acid sequences of two maize zein proteins (apparent molecular weights of 19,000 and 22,000), a structural model is proposed for their molecular conformation. The circular dichroic spectrum taken in the 190-240 nm range for a zein protein mixture in methanol solution showed the zein secondary structure to be largely helical. The polar, hydrophobic, and turn characteristics of the zein residues, as well as the homologous repeat units in their primary sequences, suggested a structure with nine adjacent, topologically antiparallel helices clustered within a distorted cylinder. Polar residues distributed along the helical surfaces allowed intra- and intermolecular hydrogen bonding such that the zein molecules could be arranged in planes. The proposed glutamine-rich turns located between the helices and at the cylindrical caps would favor side chain interactions resulting in stacking of the molecular planes. Physical properties observed for the zein proteins are explained by the model.

Amino Acid Sequence↗