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[On the identity of Candida utilis and Pichia jadinii yeast species].

Life cycles of Candida utilis (Henneberg) Lodder et Kreger-van Rij imperfect yeast (13 strains) used in industry were the study subject. When the strains were mated, we detected one of the stages of sexual process--conjugation of cells of the opposite mating type. Most of the studied cultures conjugated on the 2d-3d day. No ascospores were formed. Haploidy and heterothallism of the studied C. utilis strains were confirmed by hybridization of auxotrophic mutants. Based on PCR assay results, the yeasts are demonstrated to belong to the ascospore perfect yeast species of Pichia jadinii (A. et R. Sartory. We ill et Meyer, Wickerham) Kurtzman.

Candida↗
PubMed2003

Major transitions in evolution by genome fusions: from prokaryotes to eukaryotes, metazoans, bilaterians and vertebrates.

The major transitions in human evolution from prokaryotes to eukaryotes, from protozoans to metazoans, from the first animals to bilaterians and finally from a primitive chordate to vertebrates were all accompanied by increases in genome complexity. Rare fusion of divergent genomes rather than continuous single gene duplications could explain these jumps in evolution. The origin of eukaryotes was proposed to be due to a symbiosis of Archaea and Bacteria. Symbiosis is clearly seen as the source for mitochondria. A fundamental difference of higher eukaryotes is the cycle from haploidy to diploidy, a well-regulated genome duplication. Of course, self-fertilization exists, but the potential of sex increases with the difference of the haploid stages, such as the sperm and the egg. What should be the advantage of having two identical copies of a gene? Still, genes duplicate all the time and even genomes duplicate rather often. In plants, polyploidy is well recognized, but seems to be abundant in fungi and even in animals, too. However, hybridization, rather than autopolyploidy, seems to be the potential mechanism for creating something new. The problem with chimaeric, symbiotic or reticulate evolution events is that they blur phylogenetic lineages. Unrecognized paralogous genes or random loss of one of the paralogs in different lineages can lead to false conclusions. Horizontal genome transfer, genome fusion or hybridization might be only truly innovative combined with rare geological transitions such as change to an oxygen atmosphere, snowball Earth events or the Cambrian explosion, but correlates well with the major transitions in evolution.

Animals↗
PubMed2004

[The relationship between malignant transformation and fertilization types of hydatidiform moles].

OBJECTIVE: To study the relationship between malignant transformation and fertilization types of hydatidiform moles (HM). METHODS: Fifty four HM specimens were analyzed by using multiplex STR-PCR (9 loci) to determine the fertilization types and all patients were followed-up for the human chorionic gonadotropin (hCG) over 1 year. RESULTS: Total malignant transformation cases were 10 in all the 54 HM. Ggenetics complete hydatidiform moles (g-CHM) with DNA from only paternal origin, were observed in 38 cases including 28 homozygote and 10 heterozygote cases. In homozygote and heterozygote cases,malignant transformation occurred in 8 cases of the empty eggs fertilized by single sperms and 2 by double sperms respectively. In all the 54 HMs, 16 cases of DNA from parents were genetic partial hydatidiform moles (g-PHM), and no malignant transformation occurred in each haploidy egg fertilized by double sperms. CONCLUSION: (1)Genetic complete hydatidiform moles (g-CHM) showed a higher malignant transformation risk than genetic partial hydatidiform moles (g-PHM) (P=0.024 2); (2)There was no significant difference in malignant transformation between homozygote and heterozygote of g-CHM (P=0.699).

Cell Transformation, Neoplastic↗
PubMed2005

Compensatory evolution of interacting gene products through multifunctional intermediates.

When two mutations are singly deleterious but neutral or beneficial together, compensatory evolution can occur. The accumulation of derived, compensated genotypes contributes to the evolution of genetic incompatibilities between diverging populations or species. Previous two locus/two allele models have shown that compensatory evolution is appreciable only with tight linkage, the possibility of nearly simultaneous mutations, and/or a way to overcome negative selection against the singly mutated genotype. These conditions are often not met. Even when they are met, compensatory evolution is still predicted to be extremely slow, and in many scenarios selective advantage of the compensated genotype does little to accelerate it. Despite these obstacles, empirical studies suggest that it occurs readily. We describe here a set of related two locus/three allele models that invoke plausible neutral intermediates capable of productive interaction with both ancestral and compensated products of the interacting locus. These models are explored with analytical and computer simulation methods. The effect of these stepping-stone alleles on the evolution of ancestor-descendant incompatibilities is often profound, making the difference between evolution and stasis in several situations, including in small populations, when codominance or haploidy prevents shielding of mismatched genotypes, and in the absence of positive selection on the derived genotype. However, in large populations these intermediates can either speed or slow the evolution of incompatible genotypes relative to the two-allele case, depending on the specific fitness model. These results suggest that population size, the source of adaptive benefit, and the structural details of heteromeric gene product complexes interact to influence the path by which intergenic incompatibility evolves.

Computer Simulation↗
PubMed1990

[In vitro regeneration and applications using vegetable cell and tissue culture].

Plant cells by means of their totipotency and aided by in vitro culture techniques can be induced to perform morphogenesis leading to somatic embryoids and massive clonal multiplication; microspores or pollen can be triggered to recover haploid plants, then characters expressed via haploidy can be selected and fixed. Protoplasts from different species can lead to recombinations. We report here work done on Carica pubescens, where somatic embryoids were obtained from cells; in Prunus avium androgenesis leading to pollen calli was triggered, while plants were recovered from Nicotiana tabacum anthers. Fusion products were obtained using C. pubescens and C. papaya protoplasts, leading up to calli and shoots.

In Vitro Techniques↗
PubMed1980

[A new genetic concept: the uniparental disomy and its potential effect, the isodisomy (author's transl)].

In recent years, cytogenetic studies of spontaneous abortion products have disclosed the relatively high frequency of aneuploid embryos. These karyotypic anomalies chiefly stem from meiotic errors affecting the distribution of the chromosomes in one of the two gametes fused into a zygote. The gathered information not only implies the remarkable frequency of gonocyte aneusomy, it also reveals the prevalence of certain types of errors. It follows that gametal haploidy is often altered by the loss (nullisomy) or the addition (disomy) of certain members, in particular the X, the Y and chromosomes 15, 16, 21 and 22. It is therefore to be expected that, for some exceptional zygotes, the preservation of euploidy could result from the random union of a disomic gamete with a gamete nullisomic for a same member. To this hypothetical phenomenon, which is however statistically likely and foreseeable, we have ascribed the name of uniparental disomy, owing to the fact that both members of such a pair arise only from one parent, the mother or the father, instead of both. Furthermore, such a mechanism implies the major probability of introducing into the genome pairs of chromosomes with whole sequences of identical alleles, a consequence which we describe by the neologism of isodisomy. Such an extended homozygosity for series of colinear alleles implies from the genetic standpoint risks and advantages akin to those of parental consanguinity. An analogous mechanism could also modulate and modify the consequences of trisomies in which entire segments of two or the three implicated chromosomes, including the supernumerary one, could as well be iso-allelic (isodisomic trisomy or di-isotrisomy). The article briefly states some other predictions steming from the concept of uniparental disomy, whose confirmation should serve as a test of the proposed hypothesis.

Aneuploidy↗
PubMed1993

[Cytogenetic study of fragmented embryos not transferred in in vitro fertilization].

A cytogenetic analysis was performed on a sample of 411 human grade IV embryos (i.e. poor morphological quality embryos, never transferred in our in vitro fertilization (IVF) pro Gram) in order to investigate the chromosomal status of these embryos. One hundred eighteen were successfully karyotyped from at least one metaphase. Only 10% displayed normal diploid metaphases. Aneuploidy was the most frequently observed abnormality, with a rate of 36.4%. Six cases of single chromatids were noted and 9 embryos showed structural aberrations. Polyploidy (from 3n to 7n) and haploidy were also observed, suggesting parthenogenetic activation, polyspermy or chromosomal duplication. Mosaicism constituted 6% of the abnormalities. Thirty embryos exhibited fragmented chromosome sets which might result from in vitro delayed fertilization.

Chromosome Aberrations↗
PubMed1996

[A comparison of the amount of DNA in the sporoplasm nuclei of the myxosporidian and actinosporidian phases of the life cycle of the parasitic protozoan Zschokkella nova--a representative of the Myxozoa type].

Average DNA amounts in sporoplasm nuclei of the actinosporean and myxosporean developmental phases of Z. nova were compared. The average DNA amount per one, presumably diploid, sporoplasm nucleus of the actinosporean phase spores was twice as large as the average summarized DNA amount in two, presumably haploid, nuclei of the myxospsorean phase spores of Z. nova. It is suggested that sporoplasm nuclei in the actinosporean phase spores of Z. nova are diploid postsynthetic, whereas sporoplasm nuclei of the myxosporean phase spores are haploid. The data do not contradict the earlier supposition (Uspenskaya, 1955a, 1955b), that the investigated spores may be developmental stages of the same organism. The data support the idea of haploidy of the myxosporean phase spores (Uspenskaya, 1984) and diploidy of the actinosporean phase spores (Marques, 1984) in Myxozoa.

Animals↗
PubMed1984

Familial alopecia areata. HLA antigens and autoantibody formation in an American family.

Ten members of a white American family, spanning three generations, were studied. Three family members from two different generations were affected with hair loss. Two had alopecia universalis; one had alopecia areata. All subjects were HLA-typed using 131 antiserum samples obtained from multiparous female donors defining 41 HLA-A and HLA-B antigen specificities. Six haplotypes were identified. The affected persons and four other family members shared a common haplotype, HLA-A2,B40. The OKT4 (helper), OKT8 (suppressor-cytotoxic) cells, OKT4-OKT8 (helper-suppressor-cytotoxic) ratios and the percentage of B cells found were comparable for both the 12 control subjects and the family members studied. However, family members showed increased autoantibody formation, decreased T-cell percentages, and concanavalin A-induced suppression of the normal lymphocyte response to mitogens.

Adolescent↗
PubMed1985

HLA-Bw54 and glaucomatocyclitic crisis.

Twenty-two Japanese patients with glaucomatocyclitic crisis were typed for HLA-A, HLA-B, and HLA-C antigens to detect the immunogenetic factors in this disease. It was shown that HLA-Bw54 was present in nine (41%) of 22 patients, a significant increase even after correcting the P value for the number of antigens studied. The haplotype frequency of HLA-Bw54-Cw1 showed a significant association, and it was not due to linkage disequilibrium in the Japanese. Our results suggest that immunogenetic factors closely associated with the major histocompatibility complex may play an important role in the pathogenesis of glaucomatocyclitic crisis.

Adolescent↗
PubMed1997

Hypopigmentation in the Prader-Willi syndrome correlates with P gene deletion but not with haplotype of the hemizygous P allele.

The Prader-Willi syndrome (PWS) usually results from a paternal deletion of 15q11-q13 or maternal disomy for chromosome 15. Reduced pigmentation of skin, hair, and eyes is common in PWS and was suggested previously to be associated with the 15q11-q13 deletion. The P gene, located in this same region, is associated with OCA2, an autosomal recessive disorder that is the most frequent form of tyrosinase-positive oculocutaneous albinism. We studied 28 individuals with PWS and found that hemizygosity for the P gene was significantly correlated with the occurrence of hypopigmentation among PWS patients. However, we found little or no relationship between the occurrence of hypopigmentation and the polymorphism haplotype of the intact P allele. Thus, our results indicate that hypopigmentation is likely the result of deletion of the P gene in the context of PWS but do not support the linked hypothesis that hypopigmentation results from hemizygosity for variant P alleles with reduced function.

Alleles↗
PubMed1997

Human D(IIIa) erythrocytes: RhD protein is associated with multiple dispersed amino acid variations.

As a partial D antigen of the Rh blood group system, the D category IIIa phenotype occurs mainly in Blacks, but its molecular basis has not been defined. Here we describe studies of the D category D(IIIa) and VS+ red blood cells (RBC) from two unrelated probands by Southern blot, cDNA PCR, and nucleotide sequencing. Rh haplotyping by Sph I restriction fragment length polymorphisms indicated that the two probands carried Dce/dCe and Dce/DcE genotypes, respectively. Sequence analysis of Rh cDNAs showed that their erythroid cells expressed both D and CE transcripts. Nevertheless, the D transcripts were found to contain four nucleotide changes scattered in three exons: nt455 A-to-C (exon 3), nt602 C-to-G (exon 4), nt 654 C-to-G (exon 5), and nt667 T-to-G (exon 5). These variations resulted in the following amino acid substitutions characteristic of RhCE polypeptides: 152 Asn-to-Thr, 201 Thr-to-Arg, 218 Ile-to-Met, and 223 Phe-to-Val. The 152Thr and 223Val residues were predicted to reside in proximity to the third and fourth extracellular loops, respectively. Together, these results establish a correlation of the four amino acid changes in the RhD protein with the expression of D(IIIa) as a partial D antigen on the RBC membrane. Since the varied nucleotides identified in D(IIIa) all pre-exist in CE, they are likely to have originated from CE by templated micro-conversion event(s). The identification of a specific nt736 C-to-G transversion in CE in the two probands suggests that 245Val may involve the expression of VS antigen.

Amino Acids↗
PubMed1996

Genotype/phenotype correlations in Wilms' tumor.

Study of genotype/phenotype relationships involving the Wilms' tumor (WT) gene, WT1, in WT patients has provided insights into the function of the WT1 protein, a transcriptional regulator, and has suggested possible mutational mechanisms important in the etiology of WT. For example, the identification of deletion/insertion mutations in the first exon implicates a deletion hotspot consensus sequence in the etiology of these mutations. The disproportionate number of WT/aniridia patients with such mutations further suggest that this genetic mechanism may be enhanced by the hemizygous state. WT1 mutations are observed throughout the gene and, as predicted by the two hit mutational model, germline mutations predominantly occur in patients with congenital genitourinary (GU) anomalies and/or bilateral disease. The presence of hemizygous mutations in tumors from individuals with germline 11p13 deletions encompassing WT1 supports the hypothesis that inactivation of both WT1 alleles is important in tumorigenesis. Analyses of WT1 mutations in individuals with WT-associated Drash syndrome and WT patients with GU anomalies in the absence of Drash syndrome indicate that Drash patients almost invariably carry germline missense mutations in the zinc finger domains whereas WT/GU patients carry germline mutations that delete the WT1 gene or encode truncated proteins. These data suggest a functional difference between mutant WT1 protein carrying a single amino acid substitution versus mutant WT1 protein that is grossly truncated or WT1 haploinsufficiency. These and other genotype/phenotype correlations in WT patients will be discussed in more detail.

Alleles↗
PubMed1999

Development of an efficient method to produce uniformly haploid parthenogenones.

Bovine ovaries (paired by cow) were obtained from a local abattoir and cumulus oocyte complexes were aspirated within six hours of slaughter. Two methods for activation [(1) calcium ionophore (ionomycin) alone (n = 191); and (2) ionomycin followed by the protein synthesis inhibitor cycloheximide (n = 207)] were evaluated for production of bovine parthenogenones. Activation with ionomycin alone resulted in a development rate of 33%, while activation with ionomycin and cycloheximide sequentially resulted in a development rate to two-cell stage of 49%. A procedure was developed to expedite accurate evaluation of activated oocytes for uniformly haploid development. Uniformly haploid parthenogenones that cleaved at least once in four days of in vitro culture were individually prepared for genetic analysis. Three techniques: (1) phosphate buffered saline; (2) TL-HEPES with 0.2% ovine serum albumin; and (3) TL-HEPES with 0.2% polyvinyl pyrrolidone were compared to harvest parthenogenones for genetic analysis. The only effective method that did not create spurious results during later genetic analysis was TL-HEPES with 0.2% polyvinyl pyrrolidone. Based on the results of this study, we estimate that an average of 5-7 uniformly haploid bovine parthenogenones can be realized from each donor (using pairs of ovaries). These parthenogenones, when maintained as family units, will be valuable for accomplishment of female-specific genetic linkage analysis.

Animals↗
PubMed1999

Mutation analyses of North American APS-1 patients.

Autoimmune polyendocrinopathy syndrome type 1 (APS-1; MIM# 240300) is a rare autosomal recessively inherited disease characterised by destructive autoimmune diseases of endocrine glands. The gene responsible for APS-1, known as AIRE (for autoimmune regulator), was recently identified and contains motifs suggestive of a transcription regulator. To date, nine APS-1-associated mutations have been identified in the AIRE gene, including two common mutations R257X and 1094-1106del. In addition to these two mutations, we report seven novel mutations in 16 APS-1 patients from North America. We found that 1094-1106del and R257X were the most common mutations in this population of mixed geoethnic origin, accounting for 17/32 and 4/32 alleles, respectively. Haplotype analyses suggest that both are recurrent mutations, occurring on several different haplotypes with closely linked markers. All the novel mutations appear to be rare, occurring in only single APS-1 families. After examining all coding sequences and exon/intron boundaries of the AIRE gene, the other APS-1 allele remained unidentified in three patients. Genotype-phenotype correlations for APS-1 remain difficult, suggesting that other genetic or environmental factors, or both, influence the clinical presentation and disease progression in individual APS-1 patients.

DNA Mutational Analysis↗
PubMed1999

Numerical and structural chromosomal abnormalities detected in human sperm with a combination of multicolor FISH assays.

A pair of multicolor FISH assays (X-Y-21 and A-M-16) was developed for human sperm to simultaneously measure sex ratios; aneuploidies involving chromosomes 1, 16, 21, X, and Y; meiotic diploidies; and structural aberrations involving chromosome 1p. Sex ratios in sperm were not significantly different from unity among healthy men. Baseline frequencies of disomic sperm for chromosomes 1, 8, and 21 were similar (6.7 per 10(4) sperm, 95% CI of 5.6-8.1), suggesting that among these three chromosomes, chromosome 21 was not especially prone to nondisjunction. Frequencies of disomy 16 sperm were significantly lower, however (3.5 per 10(4) sperm, 95% CI of 2.0-6.2; P < 0.02). The baseline frequencies of sperm disomy by FISH for chromosomes 16 and 21 were validated against aneuploidy data obtained by the hamster-egg technique for human sperm cytogenetics. The frequencies of X-X, Y-Y, X-Y ("Klinefelter") sperm and sex-null ("Turner") sperm were 5.5, 5.1, 5.5, and 7.8 per 10(4) sperm, respectively. For chromosomes 16 and 21, the frequencies of nullisomic and disomic sperm were similar, suggesting that gain and loss events occurred symmetrically. However, more gain than loss was reported for chromosomes 1, X, and Y. The frequency of MI and MII diploid sperm (with flagella) was approximately 12 per 10(4) (range 8.3-16.7 per 10(4) sperm). Based on flagella data, the frequency of somatic cells in the semen was estimated to be approximately 1.8 per 10(4) sperm. Loss or gain of a portion of chromosome-arm 1p occurred in 5.5 per 10(4) sperm, and the percentage of sperm carrying structural aberrations within the haploid genome as calculated from FISH (1.4%), was similar to that obtained with the hamster-egg technique. These complementary sperm FISH assays have promising applications in studies of chromosomally abnormal sperm after exposure to occupational, medical, and environmental toxicants.

Adult↗