Killer-yeast strains with a broad spectrum of action: a search among collection strains and preliminary classification

Killer strains were looked for among certain yeast species belonging to five spore-forming genera (Hansenula, Pichia, Kluyveromyces, Williopsis and Zygowilliopsis) and one imperfect genus (Candida). 171 killers were found among 272 strains, and many of them had a high activity and a broad action spectrum. These as well as S. cerevisiae K1 and K2 killers (173 killers all in ail) were classified according to differences in their activity and the spectra of action on susceptible strains. Thirty-four groups belonging to 13 classes were isolated.     

Ultrastructure of neurohypophysis during autolysis

Autolysis was studied in neurohypophyseal secretory cells by electron microscopy at 30 min, 1-h, 3-h and 6-h intervals. In the first 30 minutes after decapitation mitochondrial slougness phenomenon was observed. "Mosaic" autolytic changes in the ultrastructure of neurohypophyseal cells were found. Severe destructive processes were clearly observed in neurohypophyseal cells when autolysis was continued for 6 hours.     

Calcium ion currents in the smooth muscle of the myometrium

The results of kinetic analysis of Ca liberation from preparations of female rabbit myometrium show that in the uterus smooth muscle there exist three pools of cation with characteristic times of metabolism 182.18 +/- 25.20, 25.56 +/- 1.00 and 2.94 +/- 0.38 min respectively. It was concluded from the compartmentalization analysis and from the data on Na+- and Mg2+--ATP-dependent transport in plasmic membrane fraction of myometrium cells that the fast phase of calcium metabolism reflects the liberation of the cation from extracellular space in the incubation medium, the intermediate one--Ca transfer from myocytes into the extracellular medium, and the slow one--liberation from the subcellular structures into the myoplasm.     

Mitochondrial DNA evolution in the genus Equus

Employing mitochondrial DNA (mtDNA) restriction-endonuclease maps as the basis of comparison, we have investigated the evolutionary affinities of the seven species generally recognized as the genus Equus. Individual species' cleavage maps contained an average of 60 cleavage sites for 16 enzymes, of which 29 were invariant for all species. Based on an average divergence rate of 2%/Myr, the variation between species supports a divergence of extant lineages from a common ancestor approximately 3.9 Myr before the present. Comparisons of cleavage maps between Equus przewalskii (Mongolian wild horse) and E. caballus (domestic horse) yielded estimates of nucleotide sequence divergence ranging from 0.27% to 0.41%. This range was due to intraspecific variation, which was noted only for E. caballus. For pairwise comparisons within this family, estimates of sequence divergence ranged from 0% (E. hemionus onager vs. E. h. kulan) to 7.8% (E. przewalskii vs. E. h. onager). Trees constructed according to the parsimony principle, on the basis of 31 phylogenetically informative restriction sites, indicate that the three extant zebra species represent a monophyletic group with E. grevyi and E. burchelli antiquorum diverging most recently. The phylogenetic relationships of E. africanus and E. hemionus remain enigmatic on the basis of the mtDNA analysis, although a recent divergence is unsupported.      

Nature of the compatible inheritance of hybrid plasmid pAS8 and its deletion mutants with replicon ColE1]

Hybrid plasmid pAS8, that consists of RP4 and ColE1 replicons, is incompatible with RP4 but co-exists with ColE1 replicon. The deletion mutants of pAS8, that replicates under the control of ColE1 replicon only, are incompatible with ColE1 derivatives, although the copy number of pAS8 and its deletion mutants in the cell is the same (1-3 per the chromosome). Incompatibility effect of plasmids is expressed in a sharp decrease in transformant's yield during selection of incoming and resident plasmids markers. In this case incompatibility is a very fast process, that leads to the elimination of resident or incoming plasmid just before plating on the selective medium. On the base of negative control theory, the repressors yield, synthesized in the presence of 1-3 copies of the deletion mutant is enough for the expression of ColE1-specific incompatibility. This ColE1 incompatibility is probably connected with the functional activity of ColE1 replicon. When ColE1 factor replicates under the control of RP4 replicon the expression of ColE1-specific incompatibility does not occur. Possibly, the incompatibility effect takes place when pAS8 deletion mutants cause the synthesis of ColE1-specific repressor. Also, the replicons of ColE1 may competein the membrane attachment site.     

Levels and intracellular distribution of calcium and magnesium in the myometrium

Atom-absorption spectrophotometry have shown that the content of Ca2+ in the rabbit and cow myometrium amounts to 4.54 +/- 0.47 and 2.57 +/- 0.30 and that of Mg2+--3.89 +/- 0.15 and 1.35 +/- 0.17 mmol per 1 kg of wet tissue weight, respectively, The content of Mg2+ in the myometrium is two times lower than in the myocardium and three times lower than in the skeletal muscle. During pregnancy (the day before delivery), delivery and postdelivery period the Ca2+ content in the rabbit myometrium is 1.5-2 times lower than in the state of functional rest, and its specific content in fractions of nuclei, mitochondria, microsomal and plasma membranes is practically the same (100-140 nmol per 1 mg of fraction protein). Distribution of the total Ca content calculated per fraction protein satisfies the following series: soluble fraction (56.4%) greater than nuclei (23.6% greater than mitochondria (7.4%) greater than microsomes (1.9%) greater than or equal to plasma membranes (1.3%). The highest specific content of Mg2+ is observed in the fraction of: plasma membranes--52, then mitochondria--40, microsomes--27 and nuclei--19 nmol per 1 mg of protein. The distribution of the total content of this element is described by a series: soluble fraction (71.8%) greater than nuclei (8.3%) greater than mitochondria (4.6%) greater than plasma membranes (1.7%) greater than microsomes (0.4%).(ABSTRACT TRUNCATED AT 250 WORDS)     

Microcolumn exclusion HPLC of globular proteins with refractive index detection

A method of determination of molecular masses of globular proteins based on microcolumn size-exclusion HPLC on modified silica sorbent (TSK-GEL 3000 SW) with refractometric detection has been developed. Molecular masses in the range 10 to 200 kD were determined with the accuracy of +/- 3%.     

Cassava leaf harvesting as vegetables; a cause of vulnerability of cassava plant to cassava mosaic disease and eventual yield reduction: Ernte von cassavablättern als gemüse; eine ursache für die anfälligkeit der cassavapflanze für die cassava-mosaikkrankheit und für spätere ertragseinbußen

The consequence of harvesting young leaves of cassava as vegetable on the vulnerability of the crop to cassava mosaic disease (CMD) and on storage root yield was investigated using 30 cassava genotypes planted in IITA fields located in the humid forest (Port Harcourt?:?Onne), forest-savannah transition (Ibadan), southern guinea savannah (Mokwa) and northern guinea savannah (Zaria) agroecologies in Nigeria. Tender apical leaves and shoots of the cassava genotypes were removed from forty plants per cassava genotype with the same number of plants considered as control. Whitefly infestation, disease incidence (DI) and symptom severity (ISS) of the disease were assessed at monthly interval for six months and also at the ninth month after planting (MAP). Yield reduction due to this treatment was calculated as percentage harvest index (HI). Whitefly population fluctuated throughout the period of observation at all locations with higher population obtained generally for treated plants compared to control plants. Sprouting leaves of some treated genotypes were observed with severe mosaic symptoms, while corresponding control showed no mosaic symptoms. Contrarily, no remarkable difference was observed in Zaria between the mean ISS of treated and control cassava genotypes. There was a highly significant difference (P?<?0.01) in DI and ISS among cassava genotypes across all locations. Also, there was a highly significant interaction (P?<?0.01) in symptom severity between location (loc) and genotype, genotype and treatment (trt), loc and trt. Interaction between loc, genotypes and trt with regard to DI was highly significant at 2, 3 and 4 MAP, while with ISS, the interaction was highly significant all through the counting period. There was a positive relationship between DI and ISS on plants of genotypes 96/1039 and ISU. The percentage HI (27.4) of treated plants of genotype 95/0166 in Ibadan was remarkably lower than the value obtained for corresponding control (41.9) plants. Also, sharp distinction in% HI of treated (39.5) and control (43.8) ISU was observed in Onne with their respective ISS values as 3.7 and 3.2. Therefore, harvesting tender apical leaves and shoots of cassava as vegetables should be discouraged as it increases the severity of CMD infection in the regenerating shoots of cassava with attendant storage root yield reduction.