Biomedical subjects

T G Cooper

Publications and source records attributed to T G Cooper.

At least 91 records · Page 5Linked to original sources

PubMed1998

The Saccharomyces cerevisiae GATA factors Dal80p and Deh1p can form homo- and heterodimeric complexes.

GATA family proteins Gln3p, Gat1p, Dal80p, and Deh1p mediate the regulation of nitrogen catabolite repression (NCR)-sensitive gene expression in Saccharomyces cerevisiae. Thus far, Gln3p, Dal80p, and Deh1p have been shown to bind to GATA sequences in NCR-sensitive promoters, in some cases to exactly the same GATA sequences. A minimal Gln3p binding site consists of a single GATA sequence, whereas a Dal80p binding site consists of two GATA sequences in specific orientation, 15 to 35 bp apart, suggesting that Dal80p may bind to DNA as a dimer. Additionally, both Dal80p and Deh1p are predicted to contain a leucine zipper motif near their C termini. Therefore, we tested whether they could form homo- and/or heterodimers in two-hybrid assays. We show that Dal80p-Dal80p, Dal80p-Dal80pLZ (leucine zipper), Dal80pLZ-Dal80pLZ, Dal80p-Deh1pLZ, Dal80pLZ-Deh1pLZ, and Deh1pLZ-Deh1pLZ complexes can form. Dal80p-Dal80p and Dal80pLZ-Dal80pLZ complexes yield 5- to 10-fold stronger signals than the other possible dimers. If Dal80p and Deh1p bind to DNA only after dimerization, then the difference in ability to form complexes could significantly affect their affinity for binding DNA and thus the degree of regulation exerted by each of the two factors.

Dimerization↗

PubMed1998

Interactions between epididymal secretions and spermatozoa.

The interactions between spermatozoa and epididymal secretions are reviewed with respect to the nature of the interactions, the maturity of the spermatozoa and the environment in which spermatozoa mature. The estimated ionic strength of epididymal fluid is low enough for all peripheral proteins to be in close contact with the membrane. Two sorts of interactions are evident, those dependent on the state of the maturity of the spermatozoa (for example peripheral proteins and some integral proteins) and those independent of it (many integral proteins). For the former, a change in the sperm membrane charge must occur to permit recognition of peripheral proteins and the insertion of secreted charged integral membrane proteins may precede the interaction with more distally secreted products. For integral proteins, partition into the membrane may depend on the composition of the plasma membrane. Changes in the sterol content of particular domains have been documented and an array of lipid-binding proteins secreted by the epididymis may mediate these changes. The dependence of the transfer of lipid-anchored proteins to spermatozoa on membranous vesicles invites reassessment of the situation of spermatozoa within the epididymis and their contact with membranous vesicles and merocrine secretions that may be crucial to promoting physiological changes in spermatozoa.

Animals↗

PubMed1998

Receptor tyrosine kinase c-ros knockout mice as a model for the study of epididymal regulation of sperm function.

Despite recent advances in understanding sperm function and characterization of epididymal secretion products, little is known about the mechanisms regulating the fertilizing capacity of spermatozoa during maturation. The recently produced receptor tyrosine kinase c-ros knockout mouse has provided the first transgenic model for such study. The only abnormalities in these transgenic mice are shown in homozygous mutant males whose epididymis fails to develop the initial segment. Normal matings by these mice do not result in oocyte fertilization, but in vitro fertilization is successful. Detailed analysis of the development of sperm motility per se did not reveal any gross abnormalities that could explain infertility in vivo. Studies on c-ros, which is expressed temporarily in a few embryonic organs but solely and at high levels in the epididymis in adults, are few and nothing is known about its putative ligand or substrates. Review of the literature on other family members of receptor tyrosine kinases throws hardly any light on its role in epididymal function affecting sperm maturation. The preliminary observations that the majority of motile spermatozoa exhibit angulation in the tail and further findings suggest a defect in the volume regulation mechanism which would normally develop during sperm maturation. This finding has provided a starting point for further research to establish the link between abnormal epididymides and sterility.

Animals↗

PubMed1997

Interaction of the human epididymal protein CD52 (HE5) with epididymal spermatozoa from men and cynomolgus monkeys.

A monoclonal antibody (CAMPATH-1 G) against the human lymphocyte surface protein CD52, which is similar to the epididymal secretion HE5, was used to ascertain the presence of this protein on maturing primate spermatozoa by flow cytometry. The percentage of human viable spermatozoa stained specifically with this antibody increased from sperm in spermatocoeles (0.5%), to the efferent ducts (3.8%), corpus (47.2%), and cauda (85.7%) epididymidis. Positive cells revealed staining mainly over the whole tail and postacrosomal region of the sperm head. Spermatozoa (approximately 10%) from both the efferent ducts and corpus epididymidis took up additional antigen when incubated with human distal cauda epididymidal plasma as a source of CD52, and 12-22% of human testicular sperm (from spermatocoeles) took up CD52 from human seminal plasma. In the cynomolgus monkey, nonspecific binding of control IgG was greater than that in human males and net CD52 staining was measurable only on approximately 30% of corpus sperm where it was mainly on the principal piece. Neither caput nor cauda sperm took up human CD52 upon incubation with human seminal plasma, but an additional 27% of corpus sperm expressed CD52. Such uptake of CD52 was drastically reduced, or did not occur, when seminal plasma had been fractionated by filtration through 0.1 microns filters (filtrate II) or 300,000 Da cutoff filters (filtrate III), respectively. Western blots revealed that CD52 contents were much reduced in filtrate II and nondetectable in filtrate III of seminal plasma. Similar reduction of CD52 in the filtrate of cauda epididymidal plasma indicates the association of this epididymal secretion with large molecular factors and suggests their involvement as carriers in the in vivo transfer of the secretion onto the epididymal sperm surface. The in vitro uptake of CD52 by some but not all immature sperm and the detection by Western blotting of much less CD52 in the corpus than the cauda luminal plasma suggest that the acquisition of this epididymal secretion by spermatozoa depends on their maturation status as well as the availability of the protein in the epididymal lumen.

Animals↗

PubMed1997

Regionalized expression of CD52 in rat epididymis is related to mRNA poly(A) tail length.

The regional pattern of CD52 expression in the rat epididymis was followed by Northern analyses and carbohydrate-labelling of glycoconjugates on Western blots. CD52 mRNA showed a novel aspect of regionalization, namely region-dependent length differences in its poly(A) tail. 'Short' CD52 mRNA molecules were present in all parts of this organ and also in the seminal vesicles. Additionally, the cauda epididymidis contained mRNA molecules with an extended poly(A) tail. Their appearance coincided with the occurrence of the principal M(r) approximately 26 kDa glycopeptide in the cauda region, representing the CD52 product. CD52 expression seemed to be regulated or modulated synergistically by androgens, temperature, and (an) unknown testicular factor(s), depending on the poly(A) tail length of its mRNA. Androgens alone exerted an effect only on molecules with 'short' poly(A) tails. They were down-regulated in castrated animals, and restored to normal levels upon testosterone supplementation. However, 'long' CD52 mRNA molecules were not affected. Only if combined with the exposure of the epididymis to the elevated temperature of the abdomen, castration of animals resulted in a complete loss of the CD52 mRNA, including the 'long' cauda species. Loss of 'long' CD52 mRNA molecules was also observed when the abdominal location was combined with efferent duct ligation. This combination of treatments, however, did not affect 'short' CD52 mRNA levels. Loss of the 'long' CD52 mRNA molecules by any treatment coincided with a loss of the principal M(r) approximately 26 kDa glycopeptide from caudal protein extracts.

Animals↗

PubMed1997

Different effects of exercise and edema on T2 relaxation in skeletal muscle.

The hypothesis that increased muscle T2 after exercise is caused by increased extracellular fluid volume was tested by comparing the effects of exercise versus external leg negative pressure on muscle T2 relaxation in normal human subjects. T2 in lower leg muscles was measured by echo-planar imaging at 63 echo times from 24 to 272 ms, and the relaxation spectrum was calculated by using a non-negative least squares algorithm. T2 relaxation in anterior leg muscle before exercise was characterized by a single component with mean T2 = 29.3 +/- 0.7 (SE, n = 5). After ankle dorsiflexion exercise, this single component broadened, and mean T2 increased to 38.3 +/- 0.7 ms. In contrast, after leg negative pressure, which increased the total leg muscle cross-sectional area by 21% (range 12-32% n = 6), there was a variable appearance of much slower-relaxing components (60-500 ms). The results suggest that increased extracellular fluid can account for only a minor portion of the increase in muscle T2 observed during exercise.

Body Fluid Compartments↗

PubMed1997

A technique for standardization and quality control of subjective sperm motility assessments in semen analysis.

OBJECTIVE: To establish a quality control method to monitor and eventually to standardize the subjective assessment of sperm motility in conventional semen analysis. DESIGN: Quality control study running over 2 years. SETTING: University infertility clinic and andrology laboratory. PATIENT(S): Randomly chosen patients attending the clinic. MAIN OUTCOME MEASURE(S): Conventional semen analysis with sperm motility assessed by grading according to the World Health Organization (WHO) criteria and analysis of individual sperm tracks with a computer-aided sperm analysis (CASA) system. Formulas were established to identify, from the track data, the threshold velocity values for distinguishing between motility grades a and b and motility grades b and c for each technician. RESULT(S): The subjective thresholds above which technicians categorized sperm as WHO grades a and b were determined by CASA to be 61 +/- 1 and 11 +/- 1 micron/s (straight-line velocity), respectively. Agreement among three to five technicians over 2 years was reasonable (coefficient of variation < 20%), but threshold values were variable. CONCLUSION(S): Agreement within and between laboratories in the assessment of sperm motility grades could be achieved by agreeing on designated values for threshold velocities for grade a and b sperm. On the basis of such values, CASA analysis could be used to provide the expected percentages of grades a, b, and c forms for quality control samples recorded and distributed on videotapes, against which technicians could adjust their subjective assessments.

Analysis of Variance↗

PubMed1997

Microvascular permeability to the F(ab')2 fragment of IgG in the male rat reproductive tract at puberty.

Development of contraceptive vaccines has recently raised much interest following the cloning of the sperm and oocyte components involved in the sperm-oocyte interaction. The main difficulty of immunocontraception in the male is the poor access of antibodies to the luminal compartment. As recent literature suggests that many substances are transported to the testis by receptor-mediated or fluid-phase transcytosis, the dependence of the transport of IgG on the Fc receptor was studied in the present investigation by comparing the penetration of whole IgG and the F(ab')2 fragment of IgG to the testis and epididymis. The maximum volume of distribution (Veq) for the F(ab')2 fragment was significantly higher than that for whole IgG in the testis of 30-60-day old rats, in the caput and cauda of 30- and 45-day old rats and the corpus of 45-day old rats. The speeds at which equilibrium between tissue extracellular fluid and serum was reached (K) for the F(ab')2 fragment and whole IgG were significantly different in the testicular capsule of the 60-day old, in the caput and corpus of the 45- and 60-day old and in the cauda of the 45-day old rats. The microvascular permeabilities (PE) to the F(ab')2 fragment were more than 2-fold higher than those to whole IgG in the testis of the 20-, 45- and 60-day old, in the testicular capsule of the 20- and 45-day old, in the caput of 20-, 30- and 60-day old and in the corpus of 20-day old rats. The PE to whole IgG was more than 2-fold higher than that to the F(ab')2 fragment in the cauda of the 45-day-old rats. The PE to the F(ab')2 fragment increased steadily from 20 to 60 days of age in the testis and caput, but in the corpus there was a more abrupt increase between 30 and 45 days of age. In the cauda, PE remained in the same range of magnitude throughout pubertal development. These results suggest that the F(ab')2 fragment reaches the lumen of the reproductive tract more easily than whole IgG from 30 days of age onwards in the testis, whereas in the caput, corpus and cauda epididymidis the rate at which F(ab')2 fragment reaches the lumen increases only temporarily at the time of appearance of spermatozoa in the lumen. Transport of IgG to the male reproductive tract is thus unlikely to be mediated by Fc receptors.

Aging↗

PubMed1997

Successful lowering of epididymal carnitine by administration of pivalate to rats.

This study was designed to lower the epididymal content of carnitine in male rats and to examine subsequent effects on fertility and sperm motility. As carnitine is transported from serum into the epididymal lumen a method to lower serum carnitine was sought. Administration of 20 mmol/L sodium pivalate in the drinking water for up to 5 weeks substantially lowered serum carnitine (to 20% of control levels within 1 week) and reduced epididymal carnitine content (to 25% of control levels in the proximal and 52% of control in distal regions) within 2 weeks. Carnitine in distal cauda epididymal fluid was also reduced (to 30% of control levels) but no changes were observed in the sperm carnitine content. The percentage motility and kinematic parameters of spermatozoa released from four epididymal regions and diluted into artificial medium were unaltered by the treatment, and all males retained their fertility in mating tests performed at weekly intervals. Increasing the dose of sodium pivalate administered to 60 mmol/L for 2 weeks lowered serum carnitine concentration more but did not further decrease epididymal carnitine content and altered neither sperm motility nor male fertility. The rat epididymis secretes an excessive amount of carnitine into its lumen so that substantially lowering the tissue content does not reduce sperm carnitine or affect their motility or fertilizing ability.

Animals↗

PubMed1997

Toxicity of ornidazole and its analogues to rat spermatozoa as reflected in motility parameters.

Ornidazole, a 5-nitro-imidazole derivative, has contraceptive properties in rats. As some ornidazole passes through the body unmetabolized after administration, the aim of this study was to investigate if ornidazole itself has a direct effect on sperm motility and whether these effects are limited or potentiated by the epididymal epithelium or structural changes to the molecule. Cauda epididymal spermatozoa or cauda epididymal tubules were incubated with ornidazole or ornidazole analogues, and motility parameters were subsequently measured by means of a computer-assisted sperm analysis (CASA) system. Incubation of spermatozoa in 2.5 mmol/L ornidazole for 4 h reduced their motility significantly, whereas incubation of epididymal tubules for 8 h in 10 mmol/L ornidazole was required to alter the velocity parameters of the enclosed spermatozoa upon release, suggesting that extratubular non-metabolized ornidazole can participate in inhibiting the motility in vivo. The in vitro toxicity of ornidazole derivatives depends on the halogen present and on the position of the nitro-group. The putatively inactive (R)- and the active (S)-ornidazole exhibited equivalent depression of sperm motility by direct incubation. This observation, and the differences between the in vitro and the in vivo efficacies of various ornidazole analogues, indicates distinct mechanisms of motility inhibition in the two experimental systems.

Animals↗

PubMed1997

Metabolism of 36Cl-ornidazole after oral application to the male rat in relation to its antifertility activity.

1. The antimycotic ornidazole (a male antifertility agent in rats) was synthesized incorporating 36Cl in the chloropropyl sidechain and its metabolism was investigated in the male rat after oral ingestion. 2. Blood levels of radioactivity were low over the first 24 h and there was no tissue accumulation of radioactivity over 48 h. 3. Most of the excreted radioactivity (20% of the ingested dose) appeared in the urine within the first 24 h. 4. Three major compounds were detected in 0-24-h urine samples and were characterized as ornidazole (13% of total radioactivity), Cl- (22%) and 3-chlorolactate (30%), the oxidation product of 3-chlorolactaldehyde. 5. No polyuria or glucosuria was observed following the oral administration of ornidazole, suggesting that any (R)-3-chlorolactate produced was insufficient to affect renal metabolism. 6. Conversion of ornidazole initially to (R, S)-alpha-chlorohydrin or ultimately to the glycolytic inhibitor (S)-3-chlorolactaldehyde could explain its antifertility action in the male rat.

Administration, Oral↗

PubMed1997

Human epididymal secreted protein CD52 on ejaculated spermatozoa: correlations with semen characteristics and the effect of its antibody.

CD52 is a glycosylphosphatidylinositol-anchored glycoprotein secreted by the epididymis where it is incorporated into sperm membranes. The antigen is common to spermatozoa and lymphocytes, and its role is not known. Quantitative analysis using immunostaining with the monoclonal antibody CAMPATH-1G and flow cytometry indicated positive signals from approximately 80% of viable, washed ejaculated spermatozoa. Staining intensity increased after capacitation overnight, and decreased after short incubation with high density lipoprotein. After incubation of Percoll-washed spermatozoa with CAMPATH-1G, motility was reduced from 83 to 74% after 5 min and from 73 to 52% after 3.5 h. Swimming velocities were reduced by approximately 30% and linearity by 15% in 5 min, but no further decreases were observed over 3.5 h. After 20 min incubation with the antibody, cell viability was decreased by 10 and 20% in freshly washed and capacitated spermatozoa respectively. Comparison of fertile and infertile patients revealed no difference in the percentages of immunostained spermatozoa or in staining intensity and there were no differences in sperm labelling between normozoospermia and teratozoospermia. Compared with normozoospermia, percentages of stained spermatozoa were lower by 20 and 27% in asthenozoospermia and oligozoospermia respectively, whereas staining intensity in asthenozoospermia was less than half that in oligozoospermia. The correlation of percentages of stained spermatozoa with percentages of motile cells suggests the involvement of epididymal CD52 in the maturation of sperm function.

Alemtuzumab↗

PubMed1997

Epididymal maturation of chromatin in spermatozoa from control monkeys (Macaca fascicularis) and those treated with Cetrorelix, a gonadotropin-releasing hormone antagonist.

In order to examine changes in sperm chromatin upon epididymal maturation in the macaque epididymis (Macaca fascicularis), spermatozoa were obtained from six regions of the duct and examined for the state of their chromatin condensation by flow cytometry after staining with acridine orange. To see whether changes were affected by androgens, tissue was obtained from five monkeys treated with the gonadotropin releasing hormone (GnRH) antagonist Cetrorelix. Spermatozoa were recovered from treated and control animals after 16 days (at hemicastration) and another 9 days of treatment. Chromatin condensation of epididymal spermatozoa from controls displayed an increase upon maturation. After 16 days of GnRH-antagonist treatment, spermatozoa in the caput epididymidis displayed greater fluorescence than those from controls, but this was reduced during epididymal transit to values found in the distal epididymal regions of the controls. It is concluded that epididymal chromatin condensation 1) is normal in GnRH-antagonist-treated monkeys as long as sperm are being produced and 2) can compensate for poor testis function so that spermatozoa with normal states of chromatin condensation are found in the distal cauda epididymidis and probably the ejaculate.

Animals↗

PubMed1997

Cross regulation of four GATA factors that control nitrogen catabolic gene expression in Saccharomyces cerevisiae.

Nitrogen catabolic gene expression in Saccharomyces cerevisiae has been reported to be regulated by three GATA family proteins, the positive regulators Gln3p and Gat1p/Nil1p and the negative regulator Dal80p/Uga43p. We show here that a fourth member of the yeast GATA family, the Dal80p homolog Deh1p, also negatively regulates expression of some, but not all, nitrogen catabolic genes, i.e., GAP1, DAL80, and UGA4 expression increases in a deh1 delta mutant. Consistent with Deh1p regulation of these genes is the observation that Deh1p forms specific DNA-protein complexes with GATAA-containing UGA4 and GAP1 promoter fragments in electrophoretic mobility shift assays. Deh1p function is demonstrable, however, only when a repressive nitrogen source such as glutamine is present; deh1 delta mutants exhibit no detectable phenotype with a poor nitrogen source such as proline. Our experiments also demonstrate that GATA factor gene expression is highly regulated by the GATA factors themselves in an interdependent manner. DAL80 expression is Gln3p and Gat1p dependent and Dal80p regulated. Moreover, Gln3p and Dal80p bind to DAL80 promoter fragments. In turn, GAT1 expression is Gln3p dependent and Dal80p regulated but is not autogenously regulated like DAL80. DEH1 expression is largely Gln3p independent, modestly Gat1p dependent, and most highly regulated by Dal80p. Paradoxically, the high-level DEH1 expression observed in a dal80::hisG disruption mutant is highly sensitive to nitrogen catabolite repression.

Base Sequence↗

PubMed1997

Nitrogen GATA factors participate in transcriptional regulation of vacuolar protease genes in Saccharomyces cerevisiae.

The expression of most nitrogen catabolic genes in Saccharomyces cerevisiae is regulated at the level of transcription in response to the quality of nitrogen source available. This regulation is accomplished through four GATA-family transcription factors: two positively acting factors capable of transcriptional activation (Gln3p and Gat1p) and two negatively acting factors capable of down-regulating Gln3p- and/or Gat1p-dependent transcription (Dal80p and Deh1p). Current understanding of nitrogen-responsive transcriptional regulation is the result of extensive analysis of genes required for the catabolism of small molecules, e.g., amino acids, allantoin, or ammonia. However, cells contain another, equally important source of nitrogen, intracellular protein, which undergoes rapid turnover during special circumstances such as entry into stationary phase, and during sporulation. Here we show that the expression of some (CPS1, PEP4, PRB1, and LAP4) but not all (PRC1) vacuolar protease genes is nitrogen catabolite repression sensitive and is regulated by the GATA-family proteins Gln3p, Gat1p, and Dal80p. These observations extend the global participation of GATA-family transcription factors to include not only well-studied genes associated with the catabolism of small nitrogenous compounds but also genes whose products are responsible for the turnover of intracellular macromolecules. They also point to the usefulness of considering control of the nitrogen-responsive GATA factors when studying the regulation of the protein turnover machinery.

DNA-Binding Proteins↗

PubMed1997

The minimal transactivation region of Saccharomyces cerevisiae Gln3p is localized to 13 amino acids.

Regulated nitrogen catabolic gene transcription in Saccharomyces cerevisiae is mediated by four positive (Gln3p and Gat1p/Nil1p) and negative (Dal80p/Uga43p and Deh1p/Nil2p/GZF3p) regulators which function in opposition to one another. All four proteins contain GATA-type zinc finger domains, and three of them (Gln3p, Dal80p, and Deh1p) have been shown to bind to GATA sequences situated upstream of genes whose expression is sensitive to nitrogen catabolite repression (NCR). The positive regulators, Gln3p and Gat1p, are able to support transcriptional activation when tethered by LexAp to the promoter of a reporter gene whose upstream activation sequences have been replaced with one or more lexA operator sites. Existing data suggest that these four proteins regulate transcription by competing with one another for binding to the GATA sequences which mediate NCR-sensitive gene expression. We show that the minimal Gln3p domain mediating transcriptional activation consists of 13 amino acids with a predicted propensity to form an alpha-helix. Genetic analysis of this region (Gln3p residues 126 to 138, QQNGEIAQLWDFN) demonstrated that alanine may be substituted for the aromatic and acidic amino acids without destroying transcriptional activation potential. Similar substitution of alanine for the two hydrophobic amino acids, isoleucine and leucine, however, destroys activation, as does introduction of basic amino acids in place of the acidic residues or introduction of proline into the center of the sequence. A point mutation in the Gln3p activation region destroys its in vivo ability to support NCR-sensitive DAL5 expression. We find no convincing evidence that NCR regulates Gln3p function by modulating the functioning of its activation region.

Amino Acid Sequence↗

PubMed1997

Ticlopidine-carbamazepine interaction in a coronary stent patient.

Neurological symptoms occurred in association with increased carbamazepine levels because of a probable drug interaction between ticlopidine and carbamazepine in an epileptic patient undergoing coronary stenting. Physicians should be aware of this possible drug interaction.

Aged↗

PubMed1996

The S. cerevisiae nitrogen starvation-induced Yvh1p and Ptp2p phosphatases play a role in control of sporulation.

Starvation for nitrogen in the absence of a fermentable carbon source causes diploid Saccharomyces cerevisiae cells to leave vegetative growth, enter meiosis, and sporulare; the former nutritional condition also induces expression of the YVH1 gene that encodes a protein phosphatase. This correlation prompted us to determine whether the Yvh1p phosphatase was a participant in the network that controls the onset of meiosis and sporulation. We found that expression of the IME2 gene, encoding a protein kinase homologue required for meiosis- and sporulation-specific gene expression, is decreased in a yvh1 disrupted strain. We also observed a decrease, albeit a smaller one, in the expression of IME1 which encodes an activator protein required for IME2 expression. Under identical experimental conditions, expression of the MCKI and IME4 genes (which promote sporulation but do not require Ime1p for expression) was not affected. These results demonstrate the specificity of the yvh1 disruption phenotype. They suggest that decreased steady-state levels of IME1 and IME2 mRNA were not merely the result of non-specific adverse affects on nucleic acid metabolism caused by the yvh1 disruption. Sporulation of a homozygous yvh1 disruption mutant was delayed and less efficient overall compared to an isogenic wild-type strain, a result which correlates with decreased IME1 and IME2 gene expression. We also observed that expression of the PTP2 tyrosine phosphatase gene (a negative regulator of the osmosensing MAP kinase cascade), but not the PTP1 gene (also encoding a tyrosine phosphatase) was induced by nitrogen-starvation. Although disruption of PTP2 alone did not demonstrably affect sporulation or IME2 gene expression, sporulation was decreased more in a yvh1, ptp2 double mutant than in a yvh1 single mutant; it was nearly abolished in the double mutant. These data suggest that the YVH1 and PTP2 encoded phosphatases likely participate in the control network regulating meiosis and sporulation. Expression of YVH1 and PTP2 was not affected by nitrogen source quality (asparagine compared to proline) suggesting that nitrogen starvation-induced YVH1 and PTP2 expression and sensitivity to nitrogen catabolite repression are on two different branches of the nitrogen regulatory network.

Cell Cycle Proteins↗