Production of Ethanol from d-Xylose by Using d-Xylose Isomerase and Yeasts

d-Xylulose, an intermediate of d-xylose catabolism, was observed to be fermentable to ethanol and carbon dioxide in a yield of greater than 80% by yeasts (including industrial bakers' yeast) under fermentative conditions. This conversion appears to be carried out by many yeasts known for d-glucose fermentation. In some yeasts, xylitol, in addition to ethanol, was produced from d-xylulose. Fermenting yeasts are also able to produce ethanol from d-xylose when d-xylose isomerizing enzyme is present. The results indicate that ethanol could be produced from d-xylose in a yield of greater than 80% by a two-step process. First, d-xylose is converted to d-xylulose by xylose isomerase. d-Xylulose is then fermented to ethanol by yeasts.     

Electron microscopic immunolocalization of seminal vesicle-specific antigen in human seminal vesicle

Seminal vesicle-specific antigen (SVSA) has been shown to be a polymorphic antigen represented by multiple immunoreactive peptides when fresh human semen is probed with monoclonal antibody (MHS-5) on Western blots. Semen samples collected directly into sodium dodecyl sulfate (SDS) demonstrate major immunoreactive peptide bands at 69-71 kDa and 58 kDa as well as a series of peptides of lower molecular mass. As semen liquefies, the higher molecular mass forms of SVSA are transformed into lower molecular mass bands, with 10-13 kDa immunoreactive peptides predominating after 8 h of liquefaction (McGee and Herr, Biol. Reprod. 37:431-439, 1987). In the present study, the 10-13 kDa form of SVSA was purified by preparative electrophoresis from SDS gels and a polyclonal antibody was generated in guinea pigs. Human seminal vesicle was fixed by immersion in combinations of glutaraldehyde and paraformaldehyde and embedded in Araldite or LR Gold. Both the guinea pig polyclonal antibody and the murine monoclonal antibody MHS-5 were employed to localize SVSA in human seminal vesicle by immunoelectron microscopy using Protein-A gold complexes. Gold particles were quantified in various subcellular compartments by a Videoplan computer. With either antibody probe, SVSA was found predominantly in the central electron-dense cores of secretory granules, with no staining evident over the electron lucent halo surrounding the granule core. With preimmune serum, the mean number of gold particles overlying secretory granules was 3/microns2; with polyclonal anti-SVSA, the mean number of particles observed over secretory granules was 182/microns2. This study represents, to our knowledge, the first fine-structural localization of a specific secretory protein to the electron-dense cores of secretory granules in principal cells of the human seminal vesicle.     

A cybernetic view of microbial growth: modeling of cells as optimal strategists

A cybernetic framework is presented which views microbial response in multiple substrate environments as a judicious investment of cellular resources in synthesizing different key proteins according to an optimal regulatory strategy. A mathematical model is developed within the cybernetic framework for the diauxic growth of Klebsiella pneumoniae on a mixture of D-glucose and D-xylose. The "bang-bang" optimal policy describes well the experimental observations obtained using a fermenter coupled to an Apple II microcomputer. Striking variations in respiratory levels are observed experimentally during the switching of the cell's adaptive machinery for the utilization of the less preferred substrate.     

Localization of sperm antigen SP-10 during the six stages of the cycle of the seminiferous epithelium in man

The distribution of the sperm protein SP-10 was investigated in plastic-embedded samples of human testes by light and electron microscopy. An immunogold and silver enhancement technique, in conjunction with a monoclonal antibody (MHS-10) raised against SP-10, was used to localize the protein. SP-10 was detected in spermatids at each of the six stages of the cycle of the seminiferous epithelium. Light microscopy showed immunoreactive material at the circumference of developing acrosomes in the early steps of spermiogenesis. As differentiation proceeded and cell shape changed from round to elongated, immunoreactive material appeared in an arc, which gradually became a V shape bordering the spermatid nucleus. The area of the immunoreactive material and its shape corresponded to that of the developing acrosome. At the electron microscopic level, gold particles indicative of the presence of SP-10 were detected on electron-dense material found within the developing acrosomal vesicle in early steps of spermiogenesis. As the electron density of the acrosome increased, a high concentration of gold particles was seen in the vesicle matrix. The gold particles gradually became associated with the inner and outer acrosomal membranes of the most mature spermatids.     

Three dimensional typological studies using scanning electron microscopy for characterization of Termitomyces pellets obtained from submerged growth conditions

There are gaps in existing understanding of fungal pellet growth dynamics. We used scanning electron microscopy (SEM) for morphological characterization of the biomass organization of Termitomyces pellets for seven species: T. microcarpus (TMI1), T. albuminosus (TAL1, TAL2), T. striatus (TSTR), T. aurantiacus (TAUR), T. heimii (THE1, THE2), T. globulus (TGLO) and T. clypeatus (TCL1, TCL2, TCL3, TCL4, TCL5). We assessed the utility of SEM for morphological and structural characterization of Termitomyces spp. in three dimensional (3D) pellet form to identify ideal pellet morphology for industrial use. Typological classification of Termitomyces species was based on furrows, isotropy, total motifs and fractal dimensions. The pellets formed were entangled and exhibited highly compacted mycelial mass with microheterogeneity and microporosity. The mean density of furrows of Termitomyces species was between 10,000 and 11,300 cm/cm², percentage isotropy was 30?80 and total motifs varied from 300 to 2500. TGLO exhibited the highest furrow mean density, 11243 cm/cm², which indicated a compact, cerebroid structure with complex ridges and furrows, whereas TAL2 exhibited the lowest furrow density. TMI1a exhibited a high percentage isotropic value, 74.6, TSTR exhibited the lowest, 30.9. Total motif number also was used as a typological classification parameter. Fractal values were 2.64?2.78 for various submerged conditions of Termitomyces species. TAL1 exhibited the highest fractal dimension and TAL2 the lowest, which indicates the complexity of branching patterns. Three-dimensional SEM image analysis can provide insight into pellet micromorphology and is a powerful tool for exploring topographical details of pellets.     

A consensus linkage map for swine chromosome 7

The First International Workshop on Swine Chromosome 7 (SSC7) was held in Minnesuing, Wisconsin, USA on 21–24 September 1995. The objective was to develop a comprehensive linkage map for porcine chromosome 7 by combining genotypic data from four swine reference populations. Contributions of genotypic data were made from the US Meat Animal Research Center, the University of Minnesota, the PiGMaP consortium and the Scandinavian consortium. Primers for selected sequence tagged site markers, to be genotyped across the reference populations, were exchanged to integrate individual maps of SSC7. Eighty-six loci were genotyped; these loci represented microsatellite, minisatellite, single-strand conformation polymorphism, restriction fragment length polymorphism, erythrocyte antigen and protein polymorphisms. Eighteen genes were mapped, including 12 markers within class I, class II and class III regions (four markers in each class) of the swine major histocompatibility complex. Forty-two markers were either genotyped on more than one population or were included in a haplotype system and used to develop skeletal linkage maps that spanned 147·6, 212·7 and 179·5 cM for the male, female and sex-average maps, respectively. A comprehensive linkage map was developed incorporating those markers with more than 30 informative meioses. The comprehensive map was slightly longer than the skeletal map, at 153·3, 215·3 and 183·8 cM, respectively, with only three intervals greater than 10 cM. These results significantly improve the genetic resolution of the porcine chromosome 7 map and represent an accurate approach for the merging of genetic maps produced in different reference populations.     

Radioactive labeling of the Golgi apparatus by micro-injection of individual amebae

Individual amebae were injected with a solution of ³H-mannose or ³H-galactose. In electron microscope radioautographs prepared at intervals between 30 min and 2 h after the injection, silver grains were heavily concentrated over the Golgi apparatus. The results show that it is feasible to label amebae with radioactive precursors by micro-injection of single cells. These results also suggest that the Golgi apparatus plays a role in assembly of a carbohydrate-rich substance, possibly part of the ameba surface coat.