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Biochemical Genetics (v.35, #5-6)

Malate Dehydrogenase Isozymes (MDH; EC 1.1.1.37) in Long-Term Callus Culture of Cereus peruvianus (Cactaceae) Exposed to Sugar and Temperature Stress by I. C. Jorge; C. A. Mangolin; M. F. P. S. Machado (pp. 155-164).

Malate dehydrogenase (MDH; EC 1.1.1.37) isozymes in long-term callus tissue culture of Cereus peruvianus were studied in starch gel electrophoresis to investigate the control of differential Mdh gene expression under sugar and temperature stress. While two cytosol MDH isozymes showed an unchanged phenotype when the callus tissues were transferred to medium maintained at 22 or 37°C and containing different concentrations of sucrose, glucose, and fructose, the different combinations of five mitochondrial MDH (mtMDH) and two microbody MDH (mbMDH) showed different MDH isozyme patterns in the callus populations. Differential expression of mtMDH isozymes seems to be modulated at the posttranslational level in callus tissues exposed to different concentrations and types of sugar and to high-temperature and low-temperature stress. An inductor effect on the expression of mbMDH isozymes was observed under stress conditions and in long-term callus tissue, and they may also present different responses.

Keywords: malate dehydrogenase isozymes; long-term callus cultures; temperature stress; carbon source stress; mechanical stress

Proboscidean DNA from Museum and Fossil Specimens: An Assessment of Ancient DNA Extraction and Amplification Techniques by Hong Yang; Edward M. Golenberg; Jeheskel Shoshani (pp. 165-179).

Applications of reliable DNA extraction and amplification techniques to postmortem samples are critical to ancient DNA research. Commonly used methods for isolating DNA from ancient material were tested and compared using both soft tissue and bones from fossil and contemporary museum proboscideans. DNAs isolated using three principal methods served as templates in subsequent PCR amplifications, and the PCR products were directly sequenced. Authentication of the ancient origin of obtained nucleotide sequences was established by demonstrating reproducibility under a blind testing system and by phylogenetic analysis. Our results indicate that ancient samples may respond differently to extraction buffers or purification procedures, and no single method was universally successful. A CTAB buffer method, modified from plant DNA extraction protocols, was found to have the highest success rate. Nested PCR was shown to be a reliable approach to amplify ancient DNA templates that failed in primary amplification.

Keywords: ancient DNA; cetyltrimethylammonium bromide extraction; nested polymerase chain reaction; proboscideans

A Unique cDNA Coding for Subunits 8 and 6 of Mitochondrial Adenosine Triphosphatase of the Lancelet Branchiostoma lanceolatum, an Ancestor of Vertebrates by Christiane Delarbre; Gabriel Gachelin (pp. 181-187).

A cDNA encoding subunits 8 and 6 of mitochondrial ATPase of the cephalochordate lancelet (Branchiostoma lanceolatum), a direct ancestor of vertebrates, has been cloned and sequenced. A unique transcript encodes the 8 and 6 subunits. In the course of isolation of the 5′ end of the ATPase 8 subunit gene, we also determined the sequence of the 5′ adjacent tRNA-Lys gene. The anticodon used by mitochondrial tRNA-Lys is TTT.

Keywords: cephalochordate; amphioxus; mitochondrial DNA; tRNA-Lys

Isozyme Variability in Plants Regenerated from Calli of Cereus peruvianus (Cactaceae) by C. A. Mangolin; A. J. Prioli; M. F. P. S. Machado (pp. 189-204).

Morphological and isozyme variation was observed among plants regenerated from callus cultures of Cereus peruvianus. Different morphological types of shoots (68%) were observed in 4-year-old regenerated plants, while no distinct morphological variants were observed in plants grown from germinated seeds. Isozyme patterns of 633 plants regenerated from calli and of 261 plants grown from germinated seeds showed no variation in isocitrate dehydrogenase isozyme, and the differential sorbitol dehydrogenase, alcohol dehydrogenase, malate dehydrogenase, acid phosphatase, and peroxidase isozyme patterns observed in regenerated plants were attributed to nonallelic variation. Allelic variation was detected at three isoesterase loci. The proportion of polymorphic loci for both populations was 13.6% and the deviation from Hardy–Weinberg equilibrium for the Est-1 and Est-7 loci observed in somaclones was attributed to the manner in which the regenerant population was established. The high values for genetic identity among regenerant and seed-grown plant populations are in accordance with the low levels of interpopulation genetic divergence. In somaclones of C. peruvianus, morphological divergence was achieved within a short time but was not associated with any isozyme changes and also was not accompanied by biochemical genetic divergence.

Keywords: somaclonal variation; tissue culture; isozymes; cactus; genetic diversity

Isozyme Extraction from Shoot Tissue of Cereus peruvianus (Cactaceae) for Electrophoretic Analysis by C. A. Mangolin; M. F. P. S. Machado (pp. 205-210).

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Biochemical Genetics (v.35, #5-6)

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Biochemical Genetics (v.35, #5-6)