The effect of the nature of the iron sources on the growth of different Corynebacterium diphtheriae strains

In the study of the influence of organic and inorganic sources of iron on the growth of 5 C. diphtheriae clinical isolates bacterial growth was found to depended on the nature of the source of iron and its concentration. Differences between the strains in the level of growth, observed when ferric sulfate was used as the only source of iron in the medium, were established. Quantitative differences in the concentrations of inorganic and organic sources of iron, necessary for growth, were determined. The influence of three chemical chelators on the growth of C. diphtheriae under the conditions of iron deficiency in the culture medium was studied. The results of the study are indicative of the possibility of the differentiation of C. diphtheriae isolated according to the level of iron consumption.     

Cortisol stress response and histopathological alteration index in Clarias gariepinus exposed to sublethal concentrations of Qua Iboe crude oil and rig wash

The histological effect on and stress response of post juvenile Clarias gariepinus exposed to Qua Iboe crude oil and rig wash were investigated. Fish weighing 60–90 g and measuring 16–18 cm were exposed for 7–28 days to 8.00 ml^?1 Qua Iboe crude oil and 0.0018 ml^–1 rig wash, both being 0.1 of the 96 hr LC₅₀. Blood samples of C. gariepinus were collected every seven days and evaluated for stress by measuring cortisol concentration. The gills and liver were studied and scored for Gill Alteration Index (GAI) and Hepatic Alteration Index (HAI), respectively. There was an increase in cortisol level up to the 7th and 14th day among the group exposed to Qua Iboe crude oil, with a decrease on the 21st and 28th day. The rig wash group increased in cortisol level up to the 7th day and decreased slightly on the 14th day, after which the trend became irregular. The toxic effects of the Qua Iboe crude oil and rig wash were time dependent, as shown by the histopathological alteration index (HAI) of gill and liver. After 28 days of exposure, the gills had irreparable damage due to high frequency of cellular necrosis and degeneration, whereas the liver had from moderate to severe damage due to the high frequency of cellular degeneration and inflammation. Qua Iboe crude oil and rig wash are both toxic to C. gariepinus, therefore their indiscriminate discharge to the environment must be discouraged.     

Baeocytes in the cyanobacterium <Emphasis Type="Italic">Pleurocapsa</Emphasis> sp.: Characterization of the differentiated cells produced by multiple fission

Electron microscopy of cyanobacterium Pleurocapsa sp. CALU 1126 revealed that multiple fission proceeds by successive binary fissions. The cultivation conditions were determined when the number of baeocytes (products of multiple fission) was comparable with that of macrocytes (products of binary fission), and cell sorting was achieved for the first time. Juvenile baeocytes were shown to differ from macrocytes in: (1) the absence of sheath; (2) the linear-peripheral configuration of their lamellar system; (3) lower content of phycobiliproteins and higher content of carotenoids; (4) the set of PSII polypeptides. Baeocytes can therefore be considered differentiated cells characterized by the uncoupling between energy and biosynthetic metabolism.     

Anonymous nuclear DNA markers in the American oyster and their implications for the heterozygote deficiency phenomenon in marine bivalves

A puzzling population-genetic phenomenon widely reported in allozyme surveys of marine bivalves is the occurrence of heterozygote deficits relative to Hardy-Weinberg expectations. Possible explanations for this pattern are categorized with respect to whether the effects should be confined to protein-level assays or are genomically pervasive and expected to be registered in both protein- and DNA-level assays. Anonymous nuclear DNA markers from the American oyster were employed to reexamine the phenomenon. In assays based on the polymerase chain reaction (PCR), two DNA-level processes were encountered that can lead to artifactual genotypic scorings: (a) differential amplification of alleles at a target locus and (b) amplification from multiple paralogous loci. We describe symptoms of these complications and prescribe methods that should generally help to ameliorate them. When artifactual scorings at two anonymous DNA loci in the American oyster were corrected, Hardy-Weinberg deviations registered in preliminary population assays decreased to nonsignificant values. Implications of these findings for the heterozygote-deficit phenomenon in marine bivalves, and for the general development and use of PCR-based assays, are discussed.      

Isolation and Study of Some Properties of Laccase from the Basidiomycetes Cerrena maxima

A new strain producing extracellular laccase (Cerrena maxima 0275) was found by screening of isolates of Basidiomycetes, and the dynamics of laccase biosynthesis by this strain was studied. The enzyme was purified to homogeneity. The molecular weight of the enzyme is 57 kD, and its pI is 3.5. The activity is constant at pH values in the range 3.0-5.0. The temperature optimum for activity is 50°C. The thermal stability of the laccase was studied. The catalytic and Michaelis constants for catechol, hydroquinone, sinapinic acid, and K₄ Fe(CN)₆ were determined. The standard redox potential of type 1 copper in the enzyme is 750 ± 5 mV. Thus, the investigated laccase is a high redox potential laccase.     

Growth, adipose, brain, and skin alterations resulting from targeted disruption of the mouse peroxisome proliferator-activated receptor beta(delta)

To determine the physiological roles of peroxisome proliferator-activated receptor beta (PPARbeta), null mice were constructed by targeted disruption of the ligand binding domain of the murine PPARbeta gene. Homozygous PPARbeta-null term fetuses were smaller than controls, and this phenotype persisted postnatally. Gonadal adipose stores were smaller, and constitutive mRNA levels of CD36 were higher, in PPARbeta-null mice than in controls. In the brain, myelination of the corpus callosum was altered in PPARbeta-null mice. PPARbeta was not required for induction of mRNAs involved in epidermal differentiation induced by O-tetradecanoylphorbol-13-acetate (TPA). The hyperplastic response observed in the epidermis after TPA application was significantly greater in the PPARbeta-null mice than in controls. Inflammation induced by TPA in the skin was lower in wild-type mice fed sulindac than in similarly treated PPARbeta-null mice. These results are the first to provide in vivo evidence of significant roles for PPARbeta in development, myelination of the corpus callosum, lipid metabolism, and epidermal cell proliferation.     

Effect of streptomycin on the stoichiometry of GTP hydrolysis in a poly(U)-dependent cell-free translation system

The technique of Sepharose-bound template translation has been used to estimate the stoichiometry of GTP hydrolysis during peptide elongation in the presence of streptomycin. The presence of streptomycin has been shown to have no great effect on the elongation rate and the stoichiometry of GTP hydrolysis during codon-specific peptide elongation in the poly(U)-directed translation system: the molar ratio of hydrolysed GTP to incorporated phenylalanine was about 2. At the same time streptomycin exerted a significant effect during misreading when a ribosome-bound peptide in the poly(U)-programmed system was elongated by leucine or isoleucine residues: the miselongation was stimulated and hence the ratio of hydrolysed GTP per peptide bond was strongly reduced, as compared with the excessive GTP hydrolysis which is characteristic of the misreading system in the absence of streptomycin [(1984) FEBS Lett. 178, 283-287]. The conclusion has been made that streptomycin blocks the stage of correction ('proof-reading') following GTP hydrolysis during EF-Tu-dependent aminoacyl-tRNA binding.     

Laccase-based biosensor for determination of polyphenols: determination of catechols in tea.

A new method of amperometric determination of phenolic compounds using an enzyme electrode is proposed. The latter represents the combination of the oxygen electrode and immobilized laccase. Analytical systems of flow injection and batch types were considered. A method of immobilization was developed that provided an increase in the stability of the enzyme. Optimal conditions for biosensor operation were found. The time needed for analysis in the flow injection mode was below 100 s. A column with immobilized enzyme could be used for up to 500 determinations of phenolic compounds without decrease of the enzyme activity. The practical validity of the method was demonstrated by tannin analysis in tea of different brands.