[Food diversity analysis based on data of food purchasing in supermarket chain].

Diversity in nutrition is of fundamental importance for health. According to research in recent decades, the diversity of the population's diet has greatly decreased, which carries health risks. The aim of the study was to analyze food diversity in population based on their purchasing activity in large trading network. Material and methods. From the depersonalized data of 1 800 319 loyalty program unique members of the retail network in Moscow, 201 904 buyers were selected according to the following criteria: the presence of a dense segment of purchases (more than 4 weeks, where there was at least 1 purchase in 2 weeks), in which the total cost of purchases was not less than 4700 rubles and at least 4 different food groups were purchased. Data from the cashier's receipts for 12 months (median 124 days) as well as the food labels for extracting the data about ingredients were used. Food diversity was analyzed by using count-base score method in which absolute number of different foods in every of 6 food groups (grains, fish and meat, fats, dairy products, vegetables, fruits and berries) was calculated. Total score as a sum of all scores from all food groups was also calculated. Results. According to the food diversity analysis, 73.9% of buyers purchased 2 or less types of grains. Only 31.4% of buyers purchased more than 4 types of vegetables, only 36.2% purchased more than 2 types of fruits and berries, 41.9% purchased less than 2 types of meat and fish, 61.3% purchased only 1 type of fat, and at least 2 types of dairy products was purchased by 53,3% of buyers. Acceptable rate of food diversity of 20 different types of food per week was achieved only in 11.4% of buyers. Conclusion. Food diversity in buyers of trading network is low, with the lowest scores in buying different grains, vegetables, fruits and berries, meat and fish as well as fats. Better diversity was demonstrated in buying dairy products, as they traditionally are accounted as healthy by consumers.

[Spectrum of food diversity of megapolis' inhabitants obtained by the analysis of buying activity].

The food diversity is a significant indicator of a healthy diet. The aim of the study was to assess the indicators of food diversity in the metropolis (Moscow) based on the analysis of consumer activity in a large retail chain. Material and methods. 201 904 holders of loyalty cards of the retail network were selected from the depersonalized purchase data for 2016-2018 according to the following selection criteria: the presence of a dense segment of purchases (more than 4 weeks, where there was at least 1 purchase in 2 weeks), where the total cost of purchases was at least 4700 rubles and at least 4 different products were purchased. From of these, 111 136 buyers have data available by gender, 43 046 by age. The classification of a set of purchased products and dishes by food groups was carried out, and complex dishes were transformed into a set of their ingredients and the distribution of the unique values of the corresponding food groups was carried out. Counting the number of unique preferences (count base diversity) by the number of positions in each of the 6 food groups (cereals, fish and meat, fat products, dairy products, vegetables, fruits and berries) allowed us to estimate the amount of food diversity. The total number of food categories in all subgroups was also calculated. Results. The low value of food diversity in the category of cereals and cereals was found in 2/3 of buyers, in the category of vegetables and fruits in 60% of buyers, in the category of meat and fish products in half of buyers, in the category of fat-and-oil products in 63.7% and in 44.2% of buyers of dairy products. An acceptable total number of categories of purchased products (more than 20 per week) was achieved only in 14.5% of men and 16.7% of women from our sample. In general, lower indicators of dietary diversity are typical for men and young people (up to 45 years old). Conclusion. Thus, it can be concluded that the importance of food diversity as a factor of health protection is underestimated by the population, especially by young people, which can lead to an increase in the burden on healthcare due to the earlier debut of a wide range of chronic diseases.

[Results of percutaneous nephrolithotomy using two accesses in the treatment of patients with staghorn stones].

INTRODUCTION: In order to improve clinical efficiency and reduce the risk of postoperative complications in patients with staghorn stones, we compared the results of original technique of biportal percutaneous nephrolithotomy (PCNL) with the standard PCNL. MATERIALS AND METHODS: The total of 221 patients with staghorn stones of K3-K4 was included in the study. The biportal PCNL was used in 109 patients, while the control group consisted of 112 patients. Inclusion criteria were stone size more or equal 2 cm, age over 18 years, absence of coagulopathy and width of the renal parenchyma more or equal 1 cm. On 1st postoperative day, ultrasound or plain urography was performed, while in patient with radiolucent stones, multi-slice computed tomography was used. In addition, complete blood count and biochemical profile were done. The main difference from the standard PCNL with sequential renal tracts is the simultaneous creation of the main and additional accesses when performing biportal PCNL. This method allowed two surgeons to simultaneously and synergistically perform lithotripsy and stone extraction from two accesses using a standard nephroscope in the main tract of 24 Ch and a miniaturized nephroscope in the additional tract of 16.5 Ch. RESULTS: The stone-free rate in the group of biportal PCNL was 80.7% (n=88), compared to 72.3% in the control group (n=81). Secondary interventions and additional procedures were required in 29 (26.6%) and 40 (39.2%) cases, respectively. The total number of infectious and hemorrhagic complications was higher in the control group. DISCUSSION: According to our data, significant advantages are observed in the group of biportal PCNL compared to the standard technique. CONCLUSION: Biportal PCNL can be recommended as a promising advancement of the technique traditionally used in the clinical practice.

[Prevention of bleeding during tubeless percutaneous nephrolithotomy].

INTRODUCTION: Nephrostomy tube placed after percutaneous removal of kidney stones can cause pain and discomfort in the early postoperative period [1, 2]. A tubeless percutaneous nephrolithotomy (PCNL) is considered as alternative approach. However, the most serious complication after tubeless procedure is a development of active uncontrolled bleeding from percutaneous tract in the early postoperative period. AIM: To improve the results of surgical treatment of kidney stones by evaluation of efficiency of using hemostatic matrix during tubeless PCNL. MATERIALS AND METHODS: A total of 113 patients with large kidney stones undergone to the tubeless PCNL for the past 9 years in our clinic. The external or internal stent was put for the drainage of upper urinary tract for 2 and 14 days, respectively. All patients were divided into 2 groups, depending on severity of bleeding (group 1 - no bleeding vs. group 2 - mild bleeding). Each group was further divided into two subgroups based on the technique and type of drainage of upper urinary tract at the end of the surgery. In the main group (n=74) the hemostatic matrix based on lyophilized thrombin 2000 IU was injected in percutaneous tract at the end of the surgery. The control group included 39 patients who underwent mini-PCNL without using hemostatic matrix. The blood loss, intensity of urine leakage from percutaneous tract (duration, visual analog scale) and degree of fluid extravasation in pararenal fat estimated by US were evaluated. RESULTS: The mean operative time was 47.5+/-3.6 min (52, 58, 38 and 49 min in subgroup I, II, III and control group, respectively). Hemoglobin drop was 9.3+/-4.1, 12.1+/-7.5, 14.6+/-11.2 and 10.6+/-5.9 in subgroups I, II, III and in the control group, respectively, while duration of hematuria was 16.1, 20.3, 28.5 and 22.9 hours, respectively. Fluid extravasation in pararenal space was found in 1 out 7 patients in subgroup III and control group, respectively (p<0.05). The dilatation of collection system (after double-J) persisted in 18.1%, 20% 22.2% and 13.3% cases in subgroup I, II, III and control group, respectively. There were no significant differences in other evaluated parameters. In 1 case in the control group there was severe bleeding which required selective embolization of the renal artery. CONCLUSION: The use of hemostatic matrix is an additional important measure which allows to prevent active bleeding from the percutaneous tract in early postoperative period. Moreover, the hemostatic matrix contributes to the sealing of tract and reduces the risk of fluid extravasation in pararenal space after mini-PCNL.

Yeast red pigment modifies cloned human α-synuclein pathogenesis in Parkinson disease models in Saccharomyces cerevisiae and Drosophila melanogaster.

Recently, we identified the yeast red pigment (RP), a polymer of 1-(5'-Phosphoribosyl)-5-aminoimidazole, as a novel potential anti-amyloid agent for the therapy of neurodegenerative diseases. The purpose of this study was to further validate RP for treatment of Parkinson's disease (PD) and to clarify molecular mechanisms involved in the reduction of amyloid cytotoxicity. We investigated RP effects in vivo using Saccharomyces cerevisiae and Drosophila melanogaster PD models. Western blot analysis revealed reduction in the levels of insoluble α-synuclein in both models, while soluble α-synuclein decreased only in Drosophila. In both models RP significantly reduced α-synuclein cytotoxicity, as was revealed by immunohistochemistry in Drosophila (p < 0.001, n = 27 flies per genotype/assay) and by flow cytometry in yeast (p < 0.05). Data obtained from the yeast PD model suggests that RP antitoxic effects are associated with a drop in ROS accumulation, and slower cellular transition from the early to late apoptotic stage. Using Drosophila brain tissue sections, we have demonstrated that RP helps to compensate for an α-synuclein-mediated reduction in the number of dopaminergic neurons and leads to better performance in animal climbing tests (p < 0.001, n = 120-150 flies per genotype/assay). Taken together, these results demonstrate the potential of RP for the treatment of PD, at least in model systems.

[Multi-tract percutaneous nephrolithotomy in the management of staghorn stones].

AIM: To compare the results of a single tract versus multi-tract percutaneous nephrolithotomy (PNL) MATERIALS AND METHODS: Over a period of 6 years, a total of 2,264 PNLs was performed at the N.A. Lopatkin Scientific Research Institute of Urology and Interventional Radiology, of which 875 PNLs were done for stage K3-K4 staghorn calculi. Among them, 244 (27.7%) patients underwent multi-tract PNL. We included 873 patients in our study. The median stone size was 59 (46; 88) mm. Two, three and four percutaneous tracts were used in 165 (67.6%), 63 (25.8%) and 14 (5.7%) patients, respectively. In 126 of 244 (52%) patients, a set for mini-percutaneous surgery with 14.5 and 15.5 Ch tubes was used as additional access. RESULTS: The effectiveness of single and multi-track PNL was 53.6%, and 83.8%, respectively. The mean operating time for PNL using one, two, three and four percutaneous tracts was 77.2+/-29.9, 85.7+/-26.9, 116.6+/-28, and 144.0+/-12.2 min, respectively. The median length of hospital stay for single and multi-track PNL was 6.6 (5.4, 8.7) vs. 10.2 (8.6, 12.3) days. Intra- and early postoperative infectious complications occurred in 101 (16.1%) and 54 (22.4%) patients, who underwent single and multi-track PNL, respectively. Bleeding occurred in 88 (13.9%) and 50 (20.8%) patients, respectively. After single and multi-track PNL, 54 (8.6%) and 21 (8.8%) patients needed a blood transfusion, respectively. CONCLUSION: Multi-track PNL is highly effective as a treatment modality for patients with complex forms of nephrolithiasis. Using the mini-tool significantly reduces the risk of bleeding when performing the additional access.

Differential miRNA expression in the three-spined stickleback, response to environmental changes.

miRNAs play important role in the various physiological and evolutionary processes, however, there is no data allowing comparison of evolutionary differences between various ecotypes adapted to different environmental conditions and specimen demonstrating immediate physiological response to the environmental changes. We compared miRNA expression profiles between marine and freshwater stickleback populations of the three-spined stickleback to identify the evolutionary differences. To study the immediate physiological response to foreign environment, we explored the changes induced by transfer of marine sticklebacks into freshwater environment and vice versa. Comparative analysis of changes in miRNA expression suggested that they are driven by three independent factors: (1) non-specific changes in miRNA expression under different environmental conditions; (2) specific response to freshwater conditions in the marine stickleback ecotype; (3) specific response to extreme osmotic conditions for both marine and freshwater ecotypes during the contact with non-native environment. Gene Ontology enrichment analysis of differential expressed miRNA targets supports our current hypothesis.

[CRISPR/Cas9-editing-based modeling of hypoxia in renal cancer cells].

Uncontrolled growth in the cell mass of malignant tumors induces intensive angiogenesis. However, the demands of the cancer cells for nutrients and oxygen remain only partially met. Hypoxia is a process that accompanies malignant transformation and evokes changes in the DNA methylation profile in solid tumors. To a certain extent, these changes, including the hypermethylation of tumor suppressor gene promoters, are related to the decrease in the activity of Tet proteins under the conditions of oxygen and free radical deficit. Stabilization, accumulation, and nuclear translocation of the transcription factor HIF1α are the key molecular events in hypoxia. We modified the clear-cell renal cancer cell line Caki1 to stabilize the HIF1α protein and characterized a model cell line that will enable the studies of the mechanisms of changes of the DNA methylation level at a constant activity of Tet proteins and a gene transcription profile characteristic of hypoxia. The CRISPR/Cas9 DNA editing system was used to edit the VHL gene. The mutant VHL protein contained a disrupted alpha-helix at the C-terminus and could not participate in the molecular pathway of proteasomal degradation of the HIF1α factor; therefore, the latter accumulated in the nucleus and activated the specific target genes. An analysis of gene transcription revealed the induction of hypoxia-associated genes in the modified cell line. The developed Сaki-1/VHLmut model can be used to discriminate between the effects evoked by oxygen-suppressed hydroxylases of the Tet family and other hypoxia-associated mechanisms of DNA methylation/demethylation.

[Analysis of clinical effectiveness and risk factors for complication of percutaneous nephrolototripsia in patients with a solitary kidney].

RELEVANCE: Management of patients with large and staghorn stones of a solitary kidney is widely debated among urologists and has not been sufficiently investigated, which determined the relevance of this study. MATERIALS AND METHODS: The study comprised 80 patients with large (>20 mm) and staghorn stones of an anatomically or functionally solitary kidney. Of them, 58 patients underwent percutaneous nephrolithotripsy (PNL), and 22 had open surgery. The criterion of the treatment effectiveness was the complete stone clearance or small residual fragments sized less than 3 mm. The safety criterion was the absence of intra- and postoperative complications, according to Clavien-Dindo grading system. The study analyzed the following factors influencing the effectiveness and safety of PNL: the number of accesses; nephroscope diameter; use of a nephroscope sheath; type of lithotripter; size, density, type and composition of the stone. RESULTS: Percutaneous nephrolithotripsy demonstrated statistically significantly better safety results compared with open surgery with comparable effectiveness. Long-term stone recurrence rate after PNL and open surgery was 10.4 and 18.2%, respectively. PNL resulted in a statistically significant improvement in the kidney function while it worsened after open surgery. The effectiveness of PNL depends on the stone type and size and the kind of lithotripter. It was 7.5 times greater for a large stone than for staghorn calculi and 4.6 times higher for stones sized less or equal 45 mm than for those sized > 45 mm. Ultrasonic lithotripter was 2.2 times more effective than another type of lithotripter. The safety of PNL depends on the nephroscope diameter, of a sheath, the number of accesses, the type of lithotripter and the type of stone. Using a 24-Ch nephroscope was 3.6 times safer than that with a diameter greater than 24-Ch; not using a sheath was 3.2 times safer than using it; one access was 3 times safer than at multiple ones; using an ultrasound lithotripter was 2.7 times safer than with another type of lithotripter; treating a large stone was 2.1 times safer than a staghorn stone. CONCLUSION: The study findings can be used to optimize the treatment of patients with large and staghorn stones of a solitary kidney.

[MRI diagnosis of spinal metastasis of medulloblastoma. A clinical case and literature review].

OBJECTIVE: the study objective was to improve the quality of detection of medulloblastoma metastases. MATERIAL AND METHODS: Magnetic resonance imaging (MRI) of the spinal cord in a child with medulloblastoma of the posterior cranial fossa, which was performed on the first day after surgery, detected contrast-positive thickenings of the meninges in the cervical, thoracic, and lumbar spinal cord that might be erroneously diagnosed as metastasis. These lesions spontaneously regressed within 3 weeks, which was verified by control MRI. CONCLUSION: In the case of misinterpretation of a MRI picture of contrast-positive thickenings of the meninges, a patient is erroneously regarded as having tumor metastases and is subject to more intensive treatment. However, the lesions spontaneously disappear or greatly reduce after 2-3 weeks. The article presents a case of this phenomenon, describes the putative mechanisms of its development, and provides recommendations for its differential diagnosis from metastases.

[THE USE OF THE COMMERCIAL APPARATUS DUAL GEL MODULE FOR THE TWO-DIMENSIONAL POLYACRYLAMIDE GEL ELECTROPHORESIS].

Two-dimensional gel electrophoresis, continues to be one of the fundamental methods to study the biological protein diversity. This method described by O'Farrell in 1975 includes two following steps: isoelectric focusing in the first dimension and polyacrylamide gel electrophoretic fractionation of proteins according to their molecular weight in the second dimension. In this manuscript we described several technical parameters of the commercial apparatus Dual Gel Module for the gel electrophoresis by means of which it is possible to accomplish the electrophoretic protein fractionation in both dimensions. The distribution of the highly purified commercial proteins used as molecular standards in the detection system of the apparatus Dual Gel Module was identical to the commercial strips of the device GE Healthcare, USA.

[Mitomycin in the complex treatment of strictures of vesicourethral anastomosis after radical prostatectomy].

The study involved 189 patients aged 40 to 80 years, which underwent retropubic radical prostatectomy for localized prostate cancer in the period from 2009 to 2013. 26 (13.8%) patients required repeated surgery due to the deterioration of urination. In primary detection or recurrent nature of the cicatrical process in vesico-urethral anastomosis, in places of dissection by urethrotomic knife (or transurethral resection), surgery was complemented by submucosal injection of mitomycin, previously diluted in saline to a concentration of not more than 0.2 mg/ml. Effectiveness of additional interstitial administration of mitomycin in primary application was 85%. Systemic infusion reactions have not been reported, that allows to consider this method as safe method for prevention of cicatricial complications.

[Comparative analysis of methods for purification and concentration of 26S proteasomes isolated from rat liver].

The 26S proteasome is a multi-subunit protein complex that consists of the catalytic 20S and regulatory 19S sub-complexes. The most well studied function of proteasomes is specific degradation of proteins. There are several purification schemes for obtaining the preparations of 26S proteasomes. An important step in purification of 26S proteasomes is concentration of the purified material for subsequent analysis of its biochemical functions. In this report we showed that the subunits composition of 26S proteasomes that have been concentrated by the different modes at the latest stage of their preparation is identical. However, the concentrating mode differently affects the functional activity of these complexes.

[Comparative structural and functional characteristics of different forms of Saccharomyces cerevisiae red pigment and its synthetic analogue].

Structural and functional characteristics of the yeast red pigment (product of polymerization of N1-(beta-D-ribofuranosyl)-5-aminoimadazole), isolated from adel 1 mutant cells of Saccharomyces cerevisiae, its deribosylated derivatives (obtained by acid hydrolysis) and its synthetic pigment analogue (product of polymerization of N1-methyl-5-aminoimadazole in vitro) has been obtained. Products of in vitro polymerization were identified using mass spectrometry. The ability of these pigments to inhibit amyloid formation using insulin fibrils was compared. The entire compounds studied were able to interact with amyloids and inhibit their growth. Electron and atomic force microscopy revealed a common feature inherent in the insulin fibrils formed in presence of these compounds--they were merged into conglomerates that were more stable and resistant to the effects of ultrasound in comparison with insulin aggregates grown without pigments. We speculate that all these compounds can cause coalescence of fibrils, partially block their loose ends and, thereby, inhibit the attachment of new monomers to growing fibrils.

[The effect of red pigment of Saccharomyces cerevisiae on insulin fibril formation in vitro].

The effect of the yeast red pigment, the result of polymerization of AIR, and of its low molecular weight derivative (presumably devoid of phosphoribosyl moiety) on the formation of amyloid fibrils in vitro was studied. Both the red pigment and its derivative, the result of acid hydrolysis of the original pigment, were shown to diminish the intensity of amyloid bound Thioflavine T fluorescence. Correlation between the decrease of the intensity of Thioflavine T fluorescence and the concentration of both forms of the red pigment was demonstrated. Both forms were also able to compete with Thioflavine T for amyloid fibrils. Electron microscopy permitted to visualize a drop of fibril size in the case of red pigments presence during their formation.

[The effect of red pigment on amyloidization of yeast proteins].

Amyloid bound thioflavine T fluorescence was studied in the lysates of yeast strains carrying mutations in genes ADE1 or ADE2 and accumulating red pigment, a result of polymerization of aminoimidazoleribotide (an intermediate of adenine biosynthesis). The fluorescence is drastically enhanced in the case of cells grown in media containing high concentration of adenine (100 mg/l) that blocks accumulation of red pigment. Blocks at first stages of purine biosynthesis de novo also impede red pigment and lead to the same effect on thioflavine fluorescence. At the same time induction of mutations in genes ADE1 or ADE2 in originally white prototrophic strains leads to considerable drop of fluorescence. A fraction of protein polymers was studied by agarose gel electrophoresis and this permitted to conclude that lowering of fluorescence intensity is indeed connected with the decrease of amyloid amount in cells accumulating red pigment. Model experiments with insulin fibers demonstrate that red pigment binds fibrils and blocks their interaction with Thioflavine T. 2D-electrophoretic comparison of pellet proteins of red and white isogenic strains, followed by MALDI, allowed identification of 23 pigment-dependent proteins. These proteins mostly belong to functional classes of chaperones and proteins, involved in glucose metabolism, closely corresponding to prion-dependent proteins characterized in our previous work. We suppose that, binding amyloid fibrils, red pigment hinders formation of prion aggregates and also, blocking fibril contact with chaperones, impedes prion propagation.

[Comparison of crude lysate pellets of isogenic strains of yeast with different prion composition: identification of a set of prion-associated proteins].

A new approach: comparative analysis of proteins of the pellets of crude cell lysates of isogenic strains of Saccharomyces cerevisiae differing by their prion composition permitted to identify a large group of prion-associated proteins in yeast cells. 2D-electrophoresis followed by MALDI-analysis of a recipient [psi-] strain and of [PSI+] cytoductant led to identification of 35 proteins whose aggregation state responded to a shift of prion(s) content. Approximately half of these proteins belonged to functional groups of chaperones and enzyme involved in glucose metabolism. Notable were also proteins involved in translation, in oxidative stress response and in protein degradation. The data obtained are compared with the results of other groups who used other approaches to detecting proteins involved in prion aggregates.

[Estimating of changes in the amyloid and prion content of yeast cells].

An attempt was made at estimating the overall amyloid content of yeast cells by treating crude cellular lysates with thioflavin T, the agent specifically staining amyloid fibrils. We demonstrated that overproduction of the yeast chaperone Hsp104p, as well as GuHCI treatment of the [PSI+] cells led both to elimination of the [PSI+] factor and to a stable decrease of the overall amyloid content estimated by intensity of fluorescence (IF) of the thioflavin T. At the same time, overexpression of gene SUP35, coding the protein prionizable to [PSI+], led to generation of [PSI+] clones with higher IF of thioflavin T. Cytoduction in the crosses involving PSI factor leads to considerable enhancement of IF; cytoductants with the nucleus of the recipient [psi-] strain not only got [PSI+] factor from the donor strain but also increased their amyloid content. In these model experiments all treatments modifying one of the yeast prions, [PSI+] factor, led to a predictable shift of IF of thioflavin T that behaved like a cytoplasmic hereditary determinant. The data obtained show that IF of thioflavin T staining gives reliable estimates of cellular amyloid content and that mitotically stable shift of IF after a battery of treatments modifying cellular prion set provides quantitative estimate of the input of prionizable protein molecules to the amyloid pool. The combination of thioflavin staining and prionotropic treatments applied here can be possibly used for future attempts of checking yeast strains for cryptic prions.

[Expression of recombinant actin 5C from Drosophila in the methylotrophic yeast Pichia pastoris].

A system for actin expression in cells of yeast Pichia pastoris was constructed. Drosophila actin 5C, by 90% homologous to beta-actin of higher eukaryotes, was used as a target protein. To improve the procedures of target protein biosynthesis in yeast cells and of extraction and purification of recombinant actin the fusion protein GFP-actin 5C, having fluorescence protein GFP as a reporter part, was expressed and purified. The dimensions and resistance of yeast cells producing recombinant actin were characterized. It was shown that the size and form of cells depended on the accumulation of recombinant protein. The purified fusion protein was used for obtaining polyclonal antibody for testing recombinant actin.

[Detection of concealed "illegitimate" nuclei in tetrad analysis of the diploid progeny of heterokaryons in Saccharomyces cerevisiae]. / Vyiavlenie skrytykh "nezakonnykh" iaderpri tetradnom analize diploidnogo potomstva geterokarionov u Saccharomyces cerevisiae.

In this work, the studies on the previously detected phenomenon of concealed heterokaryosis in Saccharomyces cerevisiae were continued. In genetic and Southern blotting experiments, one of the nuclei in the heterokaryon was shown to be active (capable of division and ensuring the corresponding cell phenotype), whereas the other was not expressed until the heterokaryotic clone was transferred to the medium selective for this concealed nucleus. Moreover, the concealed nucleus was able to assume the active state after fusion with the second parental nucleus. It was analyzed whether the nuclei with new marker combinations occurring in meiosis can behave as exceptional nuclei. Tetrad analysis of hybrids carrying the kar1 mutation in their nuclei revealed the relatively high percentage of exceptional tetrads (more than 10%). One spore in these tetrads usually formed diploid cells capable of sporulation. The presented data of genetic and molecular biological studies testify in favor of the assumption that abnormal spores contain two nuclei, which form an "illegitimate" hybrid after fusion. An extraneous spore (termed x) has usually a genotype close to that of one of the spores in this tetrad. Thus, it was assumed that the additional DNA replication round occurs in the absence of cell division during one of meiotic divisions. Results of cytological analysis conducted by the method of specific DNA staining confirmed the existence of exceptional tetrads, one spore of which contains two nuclei.