Segregation following interspecific transfer of isolated nuclei between Phytophthora parasitica and P. capsici

2000 ◽  
Vol 46 (5) ◽  
pp. 410-416 ◽  
Author(s):  
Y H Gu ◽  
W H Ko
Keyword(s):  
Nuclear Transfer ◽  
Phytophthora Capsici ◽  
Selective Medium ◽  
Crossing Over ◽  
Phytophthora Parasitica ◽  
Parasexual Cycle ◽  
Different Types ◽  
Average Success Rate ◽  
Fusion Products ◽  
Interspecific Transfer

Nuclei isolated from metalaxyl-resistant (MR) protoplasts of Phytophthora parasitica were transferred into chloroneb-resistant (CnR) protoplasts of Phytophthora capsici and vice versa, with an average success rate of 2.6 × 10-4 (protoplasts with donor nuclei/regenerated protoplasts), using a selective medium containing only the fungicide tolerated by the nuclear donor. No colonies appeared when self-fusion products of donor nuclei or recipient protoplasts were exposed to the selective medium. Colonies produced by the nuclear transfer formed sectors commonly, and differed from the parental types in appearance. All the zoospores produced by the nuclear hybrids were of normal size, and one-fifth of them contained both MR and CnR genes. Since zoospores are mostly uninucleate, these results indicated the occurrence of chromosome re-assortment or mitotic crossing-over following the production of transitory tetraploids, followed by diploidization during zoosporogenesis, thus suggesting the completion of events leading to a parasexual cycle. Hyphal fragment cultures from a nuclear hybrid tested showed considerable variation in growth rate, mycelial morphology, and level of resistance to metalaxyl, indicating uneven distribution and continuous segregation of different types of nuclei in mycelia during vegetative growth.Key words: interspecific nuclear transfer, parasexual cycle, karyogamy, Phytophthora parasitica,Phytophthora capsici.

Transplantation and subsequent behavior of mitochondria in cells of Phytophthora

2000 ◽  
Vol 46 (11) ◽  
pp. 992-997 ◽  
Author(s):  
Y H Gu ◽  
W H Ko
Keyword(s):  
Antibiotic Resistance ◽  
Asexual Reproduction ◽  
Second Generation ◽  
Random Distribution ◽  
Phytophthora Capsici ◽  
Selective Medium ◽  
Phytophthora Parasitica ◽  
Subsequent Behavior ◽  
Hybrid Antibiotic ◽  
Fusion Products

Mitochondria isolated from streptomycin-resistant (Sr) protoplasts of Phytophthora parasitica were transferred into chloramphenicol-resistant (Cpr) protoplasts of P. parasitica or Phytophthora capsici with an average successful rate of 1.7 × 10-4, using a selective medium containing streptomycin. No colonies appeared when self-fusion products of donor mitochondria or recipient protoplasts were exposed to the selective medium. Mitochondria isolated from Cpr protoplasts of P. capsici were also transferred into Sr protoplasts of P. parasitica with a similar success rate using a selective medium containing chloramphenicol. Zoospores produced by the Cpr+Sr intraspecific mitochondrial hybrid gave rise to Sr and Cpr+Sr cultures. The second generation zoospores produced by Sr and Cpr+Sr cultures also gave rise to Sr and Cpr+Sr cultures, suggesting the possible occurrence of fusion between some of the Cpr mitochondria and Sr mitochondria, and the displacement of non-fused Cpr mitochondria in the receptor protoplast by the donor Sr mitochondria. Zoospores produced by the interspecific mitochondrial hybrid gave rise to Cpr, Sr, Cpr+Sr, and Cps +Ss cultures. The second generation zoospores produced by Cpr+Sr or Sr cultures also gave rise to the same four types of cultures, suggesting the existence of residual antibiotic-sensitive mitochondria (Cps+Ss) in the parental isolates and the random distribution of Cpr, Sr, and Cps+Ss mitochondria during asexual reproduction. Results suggest that the phenotype of antibiotic resistance / sensitivity was the end result of the interactions among the three types of mitochondria.Key words: mitochondrial transplantation, mitochondrial hybrid, antibiotic resistance, Phytophthora parasitica, Phytophthora capsici.

Evidence for mitochondrial gene control of mating types in Phytophthora

2005 ◽  
Vol 51 (11) ◽  
pp. 934-940 ◽  
Author(s):  
Yu-Huan Gu ◽  
Wen-Hsiung Ko
Keyword(s):  
Mating Type ◽  
Mitochondrial Gene ◽  
Phytophthora Capsici ◽  
Nuclear Genes ◽  
Gene Control ◽  
Mating Types ◽  
Phytophthora Parasitica ◽  
Decisive Effect ◽  
Mating Type Genes ◽  
Fusion Products

When protoplasts carrying metalaxyl-resistant (Mr) nuclei from the A1 isolate of Phytophthora parasitica were fused with protoplasts carrying chloroneb-resistant (Cnr) nuclei from the A2 isolate of the same species, fusion products carrying Mr nuclei were either the A2 or A1A2 type, while those carrying Cnr nuclei were the A1, A2, or A1A2 type. Fusion products carrying Mr and Cnr nuclei also behaved as the A1, A2, or A1A2 type. The result refutes the hypothesis that mating types in Phytophthora are controlled by nuclear genes. When nuclei from the A1 isolate of P. parasitica were fused with protoplasts from the A2 isolate of the same species and vice versa, all of the nuclear hybrids expressed the mating type characteristics of the protoplast parent. The same was true when the nuclei from the A1 isolate of P. parasitica were fused with the protoplasts from the A0 isolate of Phytophthora capsici and vice versa. These results confirm the observation that mating type genes are not located in the nuclei and suggest the presence of mating type genes in the cytoplasms of the recipient protoplasts. When mitochondria from the A1 isolate of P. parasitica were fused with protoplasts from the A2 isolate of the same species, the mating type of three out of five regenerated protoplasts was changed to the A1 type. The result demonstrated the decisive effect of mitochondrial donor sexuality on mating type characteristics of mitochondrial hybrids and suggested the presence of mating type genes in mitochondria. All of the mitochondrial hybrids resulting from the transfer of mitochondria from the A0 isolate of P. capsici into protoplasts from the A1 isolate of P. parasitica were all of the A0 type. The result supports the hypothesis of the presence of mating type genes in mitochondria in Phytophthora.Key words: mating type, mitochondrial gene, Phytophthora parasitica, Phytophthora capsici.

Creation of hybrid vigor through nuclear transplantation in Phytophthora

2001 ◽  
Vol 47 (7) ◽  
pp. 662-666 ◽  
Author(s):  
Yu-Huan Gu ◽  
Wen-Hsiung Ko
Keyword(s):  
Protoplast Fusion ◽  
Fungicide Resistance ◽  
Phytophthora Capsici ◽  
Hybrid Vigor ◽  
Nuclear Transplantation ◽  
Phytophthora Parasitica ◽  
Isolated Nuclei ◽  
Donor Cells ◽  
Potential Applications ◽  
Fusion Products

When isolated nuclei of a diploid oomycete, Phytophthora parasitica, were fused with protoplasts of another strain of the same species, the regenerated nuclear hybrids grew faster than the parental isolates. Such a phenomenon did not occur in hybrids regenerated from mitochondrion–protoplast or protoplast–protoplast fusion products between these two strains. These results indicate that hybrid vigor is the result of the interaction between two different kinds of nuclei, but not between mitochondria, and they suggest that the presence of mitochondria from nuclear donor cells represses the expression of increased vigor. The nuclear hybrids also expressed increased fungicide resistance and propagule production. Increased vigor in growth was also observed in the interspecific nuclear hybrids when isolated nuclei of P. parasitica were transferred into protoplasts of Phytophthora capsici, and vice versa. This phenomenon may have potential applications, such as the creation of superior fungal strains and plant cultivars with improved commercial traits for usage in industry and agriculture.Key words: hybrid vigor, nuclear transplantation, Phytophthora parasitica, Phytophthora capsici.

scholarly journals MITOTIC CROSSING OVER AND NONDISJUNCTION IN TRANSLOCATION HETEROZYGOTES OF ASPERGILLUS

Genetics ◽  
1976 ◽  
Vol 82 (4) ◽  
pp. 605-627
Author(s):  
Etta Käfer
Keyword(s):  
Selective Advantage ◽  
The Other ◽  
Translocation Chromosome ◽  
Crossing Over ◽  
Selective Marker ◽  
Reciprocal Translocations ◽  
Poor Growth ◽  
Different Types ◽  
Diploid Genotype ◽  
One Step

ABSTRACT To analyze mitotic recombination in translocation heterozygotes of A. nidulans two sets of well-marked diploids were constructed, homo- or heterozygous for the reciprocal translocations T1(IL;VIIR) or T2(IL;VIIIR) and heterozygous for selective markers on IL. It was found that from all translocation heterozygotes some of the expected mitotic crossover types could be selected. Such crossovers are monosomic for one translocated segment and trisomic for the other and recovery depends on the relative viabilities of these unbalanced types. The obtained segregants show characteristically reduced growth rates and conidiation dependent on sizes and types of mono- and trisomic segments, and all spontaneously produce normal diploid sectors. Such secondary diploid types either arose in one step of compensating crossing over in the other involved arm, or—more conspicuously—in two steps of nondisjunction via a trisomic intermediate.—In both of the analyzed translocations the segments translocated to IL were extremely long, while those translocated from IL were relatively short. The break in I for T1(I;VII) was located distal to the main selective marker in IL, while that of T2(I;VIII) had been mapped proximal but closely linked to it. Therefore, as expected, the selected primary crossover from the two diploids with T2(I;VIII) in coupling or in repulsion to the selective marker, showed the same chromosomal imbalance and poor growth. These could however be distinguished visually because they spontaneously produced different trisomic intermediates in the next step, in accordance with the different arrangement of the aneuploid segments. On the other hand, from diploids heterozygous for T1(I;VII) mitotic crossovers could only be selected when the selective markers were in coupling with the translocation; these crossovers were relatively well-growing and produced frequent secondary segregants of the expected trisomic, 2n+VII, type. For both translocations it was impossible to recover the reciprocal crossover types (which would be trisomic for the distal segments of I and monosomic for most of groups VII or VIII) presumably because these were too inviable to form conidia.—In addition to the selected segregants of expected types a variety of unexpected ones were isolated. The conditions of selection used favour visual detection of aneuploid types, even if these produce only a few conidial heads and are not at a selective advantage. For T2(I;VIII) these "non-selected" unbalanced segregants were mainly "reciprocal" crossovers of the same phenotype and imbalance as the selected ones. For T1(I;VII) two quite different types were obtained, both possibly originating with loss of the small VII-Itranslocation chromosome. One was isolated when the selective marker in repulsion to T1(I;VII) was used and, without being homo- or hemizygous for the selective marker, it produced stable sectors homozygous for this marker. The other was obtained from both coupling and repulsion diploids and showed a near-diploid genotype; it produced practically only haploid stable sectors of the type expected from monosomics, 2n-1 for the short translocation chromosome.

Selective Enumeration of Lactobacillus acidophilus for Probiotic Formulations

2014 ◽  
Vol 7 (4) ◽  
pp. 2646-2650
Author(s):  
Barun K Bhattacharyya ◽  
S Chowdhury ◽  
S Das ◽  
P K Saha ◽  
S Mukherjee ◽  
...  
Keyword(s):  
Lactobacillus Acidophilus ◽  
Food Processing ◽  
Health Benefits ◽  
Pharmaceutical Formulations ◽  
Selective Medium ◽  
Bifidobacterium Species ◽  
Different Types ◽  
Agar Media ◽  
Mixed Populations

Probiotic microorganisms have been utilized for many years in food processing, preservations and for nutraceutical health benefits.  There are a large number of pharmaceutical formulations containing probiotic microorganisms available in the market worldwide. Majority of these organisms are the members specifically from genera Lactobacillus, Lactococcus and Bifidobacterium. A number of media have been proposed for selective or differential enumeration of lactobacilli and bifidobacteria in mixed populations. The development of selective medium using different types of ingredients and antibiotic are well practiced. In the present study we have developed a selective medium for the enumeration of Lactobacillus acidophilus by utilizing the antibiotic ofloxacin resistance of the organism in Lactobacilli MRS-agar. Samples were analyzed by determining viable counts in reference Lactobacilli MRS agar and selective Lactobacilli MRS-ofloxacin agar media. The results were statistically analyzed to evaluate the precision, accuracy, reproducibility and selectivity of the method developed.  Thus MRS containing ofloxacin medium can be used for selective enumeration of Lactobacillus acidophilus strains available in commercial formulations containing Bifidobacterium species.

Reduction and Survival ofListeria monocytogenes in Ready-to-Eat Meats after Irradiation

2004 ◽  
Vol 67 (1) ◽  
pp. 77-82 ◽  
Author(s):  
SALLY C. C. FOONG ◽  
GLENDA L. GONZALEZ ◽  
JAMES S. DICKSON
Keyword(s):  
Listeria Monocytogenes ◽  
Pathogenic Bacteria ◽  
Optimal Level ◽  
Selective Medium ◽  
Selective Media ◽  
Preliminary Results ◽  
Log Reduction ◽  
Different Types ◽  
Roast Beef ◽  
Oflisteria Monocytogenes

A five-strain Listeria monocytogenes culture was inoculated onto six different types of ready-to-eat (RTE) meats (frankfurters, ham, roast beef, bologna, smoked turkey with lactate, and smoked turkey without lactate). The meats were vacuum packed and stored at 4°C for 24 h prior to irradiation. Populations of L. monocytogenes were recovered by surface plating on nonselective and selective media. The margins of safety studied include 3-log (3D) and 5-log (5D) reduction of pathogenic bacteria to achieve an optimal level of reduction while retaining organoleptic qualities of the meats. A 3-log reduction of L. monocytogenes was obtained at 1.5 kGy when nonselective plating medium was used. The dosages for 3-log reduction were 1.5 kGy for bologna, roast beef, and both types of turkey and 2.0 kGy for frankfurters and ham on the basis of use of selective medium. The D10-values ranged from 0.42 to 0.44 kGy. A 5-log reduction of L. monocytogenes was obtained at 2.5 kGy with nonselective medium. With selective medium, the dosages were 2.5 kGy for bologna, roast beef, and both types of turkey and 3.0 kGy for frankfurters and ham. Survival of L. monocytogenes in the same RTE meat types after irradiation was also studied. Meats were inoculated with 5 log L. monocytogenes per g and irradiated at doses of 2.0 and 4.0 kGy. Recovery of the surviving organisms was observed during storage at temperatures of 4 and 10°C for 12 weeks. Preliminary results showed no growth in meats irradiated at 4.0 kGy. Survivors were observed for irradiated meats at 2.0 kGy stored at 10°C after the second week. No growth was observed in samples irradiated at 2.0 kGy stored at 4°C until the fifth week.

scholarly journals Modifications of PARP Medium Using Fluazinam, Miconazole, and Nystatin for Detection of Pythium spp. in Soil

Plant Disease ◽  
2007 ◽  
Vol 91 (12) ◽  
pp. 1591-1599 ◽  
Author(s):  
Y. Morita ◽  
M. Tojo
Keyword(s):  
New Media ◽  
Fusarium Oxysporum ◽  
Mycelial Growth ◽  
Antifungal Agents ◽  
Selective Medium ◽  
Plating Technique ◽  
Naturally Occurring ◽  
Different Types ◽  
Soil Dilution ◽  
Better Than

The standard Pythium selective medium PARP (pimaricin + ampicillin + rifampicin + pentachloronitrobenzene [PCNB] agar), was modified by replacing PCNB and pimaricin with other antifungal agents. Several antifungal agents such as fluazinam, miconazole, 2,4,5,6-tetrachloroisophthalonitrile (TPN), iminoctadine triacetate, tolclofos-methyl, captan, and nystatin, initially were screened for effects on Pythium growth. Based on these results, the following three media were developed: PARF (pimaricin + ampicillin + rifampicin + fluazinam agar), NARF (nystatin + ampicillin + rifampicin + fluazinam agar), and NARM (nystatin + ampicillin + rifampicin + miconazole agar). New media were comparable with PARP on yield of naturally occurring Pythium spp. from two different types of soil using the soil-dilution plating technique. PARF and NARF were significantly better than PARP on inhibition of non-pythiaceous microbes on the soil-dilution plates, but were significantly lower than PARP on the rate of mycelial growth of six of eight isolates belonging to seven species of Pythium. NARM was equivalent to PARP on inhibition of non-pythiaceous microbes except for Fusarium oxysporum, and was significantly better than PARP on rate of mycelial growth of five of eight isolates of Pythium.

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