4-phenylylboronic acid: A new type of enhancer for the horseradish peroxidase catalysed chemiluminescent oxidation of luminol

4-Phenylylboronic acid enhances the light emission from the horseradish peroxidase catalysed oxidation of luminol by hydrogen peroxide. Optimization studies showed that the greatest enhancement was obtained using micromolar concentrations of the new enhancer. The largest degree of enhancement was found with the basic isoenzyme of horseradish peroxidase (Type VIA), and lesser degrees of enhancement were obtained with Type VII and Type IX horseradish peroxidase. The enhancer was also effective in the peroxidase catalysed oxidation of isoluminol by peroxide.     

POLLEN ENERGETICS AND POLLINATION MODES

The caloric content of pollen for several different species was determined by using a semimicro oxygen bomb calorimeter. The species studied were divided into subsets for statistical comparisons. The subsets considered were wind-pollinated dicots, monocots and gymnosperms; insect-pollinated dicots; and taxonomic subclasses of the wind-pollinated angiosperms (Asteridae, Hamamelidae, Caryophyllidae and Commelinidae). The results indicated a statistically significant caloric content difference (0.05 or higher) between wind-pollinated dicots vs. monocots and gymnosperms. There was no statistical difference between wind-pollinated dicots and insect-pollinated dicots. All subclasses were significantly different from one another. A statistically significant difference was found between two tribes in the Asteraceae which have shifted from insect to wind pollination, providing additional evidence for an independent evolution of the two. The need for future research in this area is discussed.     

Genetics of histocompatibility in mice

Twenty-five congenic mouse strains differing at distinguishable minor (non-H?2) histocompatibility loci were paired in 71 different combinations. F₁ offspring were used as skin-graft donors for more than 4000 recipients to test whether immune responses to parental strain antigens were statistically independent. Thirty-four (48 percent) of the 71 combinations were predicted adequately by an independent response hypothesis. A simple additive model was consistent with 39 (55 percent) of the observed responses, although 18 of these were among those in agreement with the independent hypothesis. A synergistic response faster than that predicted by either the independent or additive response model was seen in 12 (17 percent) of the combinations. The remaining 5 percent were not well described by any of these models. No strain was represented with unusual frequency among those involved in synergistic interactions.     

Sequence heterogeneity and anomalous electrophoretic mobility of kinetoplast minicircle DNA from Leishmania tarentolae

Several unit-length minicircles from the kinetoplast DNA of Leishmania tarentolae were cloned into pBR322 and into M13 phage vectors. The complete nucleotide sequences of three different partially homologous minicircles were obtained. The molecules contained a region of approx. 80% sequence homology extending for 160–270 bp and a region unique to each minicircle. A 14-mer was found to be conserved in all kinetoplast minicircle sequences reported to date. The frequency distributions of various minicircle sequence classes in L. tarentolae were obtained by quantitative gel electrophoresis and by examination of the “T ladder” patterns of minicircles randomly cloned into M13 at several sites. By these methods we could assign approx. 50% of the total minicircle DNA into a minimum of five sequence classes. A sequence-dependent polyacrylamide gel migration abnormality was observed with several minicircle fragments both cloned and uncloned. The abnormality was dependent on the presence of a portion of the conserved region of the minicircle.     

Parasternal intercostal muscle remodeling in severe chronic obstructive pulmonary disease.

Studies in experimental animals indicate that chronic increases in neural drive to limb muscles elicit a fast-to-slow transformation of fiber-type proportions and myofibrillar proteins. Since neural drive to the parasternal intercostal muscles (parasternals) is chronically increased in patients with severe chronic obstructive pulmonary diseases (COPDs), we carried out the present study to test the hypothesis that the parasternals of COPD patients exhibit an increase in the proportions of both slow fibers and slow myosin heavy chains (MHCs). Accordingly, we obtained full thickness parasternal muscle biopsies from the third interspace of seven COPD patients (mean +/- SE age: 59 +/- 4 yr) and seven age-matched controls (AMCs). Fiber typing was done by immunohistochemistry, and MHC proportions were determined by SDS-PAGE followed by densitometry. COPD patients exhibited higher proportions of slow fibers than AMCs (73 +/- 4 vs. 51 +/- 3%; P < 0.01). Additionally, COPD patients exhibited higher proportions of slow MHC than AMCs (56 +/- 4 vs. 46 +/- 4%, P < 0.04). We conclude that the parasternal muscles of patients with severe COPD exhibit a fast-to-slow transformation in both fiber-type and MHC proportions. Previous workers have demonstrated that remodeling of the external intercostals, another rib cage inspiratory muscle, elicited by severe COPD is characterized by a slow-to-fast transformation in both fiber types and MHC isoform proportions. The physiological significance of this difference in remodeling between these two inspiratory rib cage muscles remains to be elucidated.     

Identification of Bacilysin, Chlorotetaine, and Iturin A Produced by Bacillus sp. Strain CS93 Isolated from Pozol, a Mexican Fermented Maize Dough

Three antimicrobial compounds produced by Bacillus sp. strain CS93 isolated from pozol were identified by using high-performance liquid chromatography and mass spectrometry. The three compounds were iturin, bacilysin, and chlorotetaine. Production of these compounds by CS93 could account for the medicinal properties attributed to pozol.