Effect of pectin on pectinases in autolysis of Botrytis cinerea

Pectic activity in autolyzed cultures of Botrytis cinerea in a medium with and without pectin was similar, but in the medium with pectin maximal activities occurred in younger cultures. The pectic activities found were polygalacturonase, polymethylgalacturonase, endo activity (pectin as substrate) and pectin lyase. The molecular weights of polygalacturonase, polymethylgalacturonase and endo activity (pectin as substrate) were 36000, 33000 and 30200 daltons respectively, and the molecular weight of pectin lyase was 18200 daltons. By gel electrophoresis four different pectic activities were detected, three in the top of the gel and one in the bottom. Two enzymes were characterized, the polygalacturonase activity (first band in the top) inhibited by Ca⁺⁺ and the pectin lyase activity (in the bottom) which was not inhibited by Ca⁺⁺. These enzymes are not induced by the presence of pectin in the medium during degradation of Botrytis cinerea.     

Rehabilitation in the Philippines

The international community has perspective and experience that will freshen our approaches to rehabilitation. Martin Grabois, MD^*, editor of this special section, has gathered articles written by experts from other countries. The intention is to stimulate thought, discussion, and action—and to broaden horizons.     

Microtubule-associated protein MAP2 preferentially binds to a dA/dT sequence present in mouse satellite DNA

Microtubule-associated protein MAP2 binds to the Sau96.1 restriction monomer fragment of mouse satellite DNA. This fragment is also present in a lower proportion in bulk DNA. The digestion of MAP2-Sau96.1 fragment complex by DNase results in the protection of certain nucleotide sequences. The sequence poly(dA)4/poly(dT)4 is mainly protected against DNase digestion.     

High-frequency conversion to a "fluffy" developmental phenotype in Aspergillus spp. by 5-azacytidine treatment: evidence for involvement of a single nuclear gene.

Transient exposure of mycelia from Aspergillus niger and Aspergillus nidulans to the cytidine analog 5-azacytidine, leading to no more than 0.3 to 0.5% substitution for cytosine by 5-azacytosine in A. nidulans DNA, resulted in the conversion of a high fraction of the cell population (more than 20%) to a mitotically and meiotically stable "fluffy" developmental phenotype. The phenotypic variants are characterized by the developmentally timed production of a profuse fluffy network of undifferentiated aerial hyphae that seem to escape signals governing vegetative growth. Genetic analysis with six different fluffy clones reveals that this trait is not cytoplasmically coded, is recessive in heterozygous diploids but codominant in heterokaryons, and exhibits a 1:1 Mendelian segregation pattern upon sexual sporulation of heterozygous diploids. Complementation and mitotic haploidization studies indicated that all variants are affected in the same gene, which can be tentatively located on chromosome VIII of A. nidulans. Molecular analysis to search for modified bases showed that DNA methylation is negligible in in both A. niger and A. nidulans and that no differences could be detected among DNAs from wild-type cells, fluffy clones, or mycelia exposed to 5-azacytidine. It thus appears that high-frequency conversion of fungal mycelia to a stable, variant developmental phenotype by 5-azacytidine is the result of some kind of target action on a single nuclear gene and that this conversion can occur in organisms virtually devoid of DNA methylation.     

Electron microscopy of thin sections of Candida utilis: The structure of the cell wall

Summary Details of the structure of the Candida utilis cell wall were described. Using intact cells, cell walls, about 0.02 m thick, have been resolved into three electron dense layers, each about 700 Å thick, made up of materials of very similar electron opacity. The central and the inner layers of the wall seem to be closely packed forming a slightly more compact structure of somewhat greater electron density. Laminations were observed in some of the inner layers of the sections, particularly in some areas where the cell wall had separated: The possibility of this lamination being associated with the presence of chitin in the framework of the cell wall is discussed. Interesting observations have also been made in the sections of the heat-killed cells confirming the existence of a central electron dense cell wall layer, differing from the inner and the outer ones. Underlying the cell wall is the cytoplasmic membrane, a not too well defined sinous structure with some invaginations.     

Establishment of transformed root cultures of Perezia cuernavacana producing the sesquiterpene quinone perezone

Summary The sesquiterpene quinone currently known as perezone is abundantly produced by the roots of Perezia cuernavacana. This compound is of biotechnological interest since it may be used as a pigment and has several pharmacological properties. In this work we demonstrate that perezone is also produced in transformed root cultures of P. cuernavacana. Hairy roots were induced by inoculation of internodal segments of sterile plants of P. cuernavacana with Agrobacterium rhizogenes AR12 strain. The axenic liquid MS medium cultures of the hairy roots isolated from the internodes showed active growth in the absence of growth regulators. The transformed nature of the tissue was confirmed by genomic integration (PCR and slot blot hybridization) and expression (enzyme activity) of the marker gus-gene. The production of perezone by a transformed root culture was evidenced by IR spectroscopy. Our results offer an alternative for enhanced production of perezone and represent an advantage over its extraction from natural plant populations which present problems in their agronomic culture.     

Behaviour of Candida utilis during growth in relation to Mg2+ and K+ concentration in sugar cane molasses

Magnesium and potassium ions are present in sugar cane molasses in a concentration of about 0.3% and 2.5%, respectively, which is high enough to support biomass production from Candida utilis. Culture broth with 40 g/l of total reducing substances supplemented by the addition of 1 ppm of Mg²⁺ leads to a higher yield (Y x/s) in batch fermentation experiments. The subsequent addition of Mg²⁺ up to 10 ppm decreases the yield coefficient from 0.53 to 0.42 without affecting the growth rate. Fermentation media supplemented with 1 to 10 ppm of K⁺ decreased both the yield coefficient and the specific growth rate. A Mg/K ratio of about 0.1 seems to be optimal for yeast biomass propagation.     

Partial trisomy 16q resulting from maternal translocation 11p/16q

A 3 1/2-year-old male with partial trisomy of the long arm of chromosome 16 resulting from a maternal balanced translocation 11p;16q is described. Clinical findings are compared with similar case reports from the literature.     

Naltrexone effects on pituitary neurointermediate lobe and median eminence

The long-acting opiate antagonist naltrexone hydrochloride was administered by intraperitoneal injection, in a dose response protocol, to adult rats. The drug was used to observe effects of opiate receptor blockade on cells of the pituitary gland and adjacent hypothalamus. At higher drug doses (5mg/kg or 10mg/kg), neurites directly innervating pars intermedia cells contained swollen vesicles and disrupted membranous elements. Fibers within the median eminence of the hypothalamus appeared swollen, and contained myelin figures. Despite the consistent degenerative changes appearing in neurites, measurements of levels of dopamine, norepinephrine, and epinephrine in striatum, and hypothalamus did not differ significantly between naltrexone-treated or control animals, although there was a significant elevation of norepinephrine in the pituitary after drug treatment. At all drug dose levels administered, supraependymal neuron-like cells appeared atop the ependyma of the third ventricle above the median eminence. These observations suggest that naltrexone produces specific neurotoxic effects on neurites of the tuberoinfundibular system, and may induce changes in the ventricular environment which stimulate the appearance of supraependymal neurons.