Biomedical subjects

T G Cooper

Publications and source records attributed to T G Cooper.

At least 37 records · Page 2Linked to original sources

PubMed2003

Developmental changes in signalling transduction factors in maturing sperm during epididymal transit.

Testicular spermatozoa are incapable of fertilising eggs in vivo and the epididymal epithelium is responsible for creating a luminal environment conducive to the acquisition of fertilising capacity by the spermatozoa within it. It does this by modifying sperm membranes so that they can interact with stimuli from the female tract, and by supplying or removing low molecular weight compounds that modify sperm cytoplasmic composition. Both these extracellular and intracellular events associated with signal transduction and second messenger systems in maturing spermatozoa are reviewed here.

Acrosome Reaction↗

PubMed2002

The effect of (R,S)-ornidazole on the fertility of male mice and the excretion and metabolism of 36Cl-(R,S)-ornidazole and 36Cl-(R,S)-alpha-chlorohydrin in male mice and rats.

(R,S)-Ornidazole, an effective antifertility agent for male rats at 400 mg/kg/day, was ineffective at this dose in male mice and at 1000 mg/kg/day caused neural effects. The compound was not excreted unchanged and more polar metabolites and Cl- were detected in 0-8 h urine following a single injection (400 mg/kg). In 8-24 h urine even these metabolites and most Cl ion were absent, indicating rapid metabolism of ornidazole. There was no organ specific accumulation of 36Cl-(R,S)-ornidazole in murine tissues. After injection of 36Cl-(R,S)-alpha-chlorohydrin, another antifertility agent in the rat but not the mouse, there was also no tissue-specific accumulation of radioactivity in the reproductive tract of either species. Urinary excretion rates of alpha-chlorohydrin were twice as rapid in mice as in rats. In mice, alpha-chlorohydrin was the major urinary metabolite, but in the rat metabolites included Cl-, 3-chlorolactate (BCLA) at 5 and 10 h and BCLA only at 24 h. BCLA was the major metabolite detected in most tissues at 10 and 24 h. In the rat cauda (but not caput) epididymidis the glycolytic inhibitor 3-chlorolactaldehyde was present at 5 h (but not 10 h), indicative of early metabolism. These results demonstrate a greater metabolism and excretion of putative antifertility agents in the mouse than the rat, lowering the amount of effective inhibitor circulating in the animal, which may explain why (R,S)-alpha-chlorohydrin and (R,S)-ornidazole are ineffective in this species at the dosages and injection times used, despite their spermatozoa being sensitive to inhibition by (R,S)-alpha-chlorohydrin in vitro.

Amebicides↗

PubMed2002

Lack of antifertility properties of novel halogenated glycolytic inhibitors and the urinary excretion and metabolism of 1,6-dichloro-1,6-dideoxy-D-fructofuranose in the male rat.

The antifertility action of (R,S)-alpha-chlorohydrin administered orally to male rats was compared with that of several novel chlorinated compounds known to inhibit glycolysis and the kinematics of rat sperm in vitro. Oral gavage of 1,6-dichloro-1,6-dideoxy-D-fructofuranose (dichlorodideoxyfructose, DCF), 1-chloro-3-hydroxypropanone, its dimethylketal and bromopyruvate did not reduce the fertility of male rats below that of controls at the equivalent antifertility dose of (R,S)-alpha-chlorohydrin (5 mg/kg/day) or higher. As anticipated for a compound cleaved to products of (S)-chirality even high doses of DCF (200 mg/kg) showed no effect on renal function. 36Cl-Labelled DCF administered orally to male rats was eliminated only slowly in the urine (16% of the ingested dose excreted in 96 h). In the first 8 h, approximately 50% of DCF was excreted unchanged, 30% was excreted as 3-chlorolactate (BCLA), the oxidation product 3-chlorolactaldehyde and 25% as Cl-. By 24 h little DCF remained and the major metabolite (70%) was BCLA and 20% Cl-. The high rate of dechlorination is most likely responsible for the low antifertility action of DCF.

Acetone↗

PubMed2002

Semen analysis and external quality control schemes for semen analysis need global standardization.

One semen analysis laboratory [the Institute of Reproductive Medicine (IRM), Münster, Germany] was enrolled in three external quality assurance programmes in Europe (United Kingdom External Quality Assurance Scheme, European Academy of Andrology, European Society of Human Reproduction) that control for the assessment of sperm concentration, sperm motility and sperm morphology. Agreement between the participating laboratory and the sperm concentrations designated by all three programmes was good. Disagreement between two quality control (QC) programmes providing motility assessment was particularly noticeable in the distinction between motility grades a and b. For the identification of normal sperm morphology, marked differences between the standards set by different QC programmes were apparent. One programme was stricter in its categorization of normal forms, such that an overestimation of normal forms was diagnosed at IRM, whereas agreement with the other programmes was achieved. Variation of results from technicians in the IRM internal QC programme was <13%. The discrepancies between external quality control (EQC) centres demonstrated here are challenging problems to be overcome partly by the andrology laboratories and partly by the providers of EQC services. The introduction of objective, computer-aided sperm assessment in providing designated values may help to rectify this situation. Until this is achieved, EQC programmes should develop an internal programme to monitor their materials and methods for assessment.

Humans↗

PubMed2002

A possible extratubular origin of epididymal basal cells in mice.

The origin of basal cells in mouse epididymis was examined by counting the numbers of basal cells, intratubular mitotic figures and peritubular cells during development of the epididymis. Putative precursors of basal cells were labelled with bromodeoxyuridine and the nuclei of daughter cells were examined. Histochemical localization of cytokines was performed to gauge their involvement in migration of basal cell precursors from extratubular sources. The results indicate that basal cells may arise from extratubular sources as: (i) there was a decrease in the number of mitotic figures as the number of basal cells increased; (ii) no mitotic figures were observed in the base of the epithelium; (iii) the increase in the number of peritubular cells did not parallel the number of basal cells in all epididymal regions; (iv) division of epithelial cells into daughter cells was circumferential and not radial; (v) bromodeoxyuridine-labelled basal cell nuclei were mostly not found in the vicinity of labelled principal cell nuclei and vice versa; and (vi) the percentage of labelled basal cell nuclei was higher than that of the other cells, which is indicative of their arrival from a more highly labelled pool. In addition, no age-dependent correlation was noted between any of the cytokines tested and appearance of basal cells in the epithelium, and basal cells expressed intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1), which provides further evidence of a relationship between basal cells and immunocytes. If basal cells have an immunological function, failure of their recruitment into the epididymal epithelium at about the time of puberty may have repercussions for immunological protection of spermatozoa and, ultimately, for fertility in the adult.

Animals↗

PubMed2002

Cortical activation during rhythmic hand movements performed under three types of control: an fMRI study.

Echoplanar fMRI was used to measure changes in cortical activation during the performance of a simple hand movement task under three types of voluntary control. Each of three imaging series alternated a task with rest: passive (in which the experimenter moved the hand), voluntary against low resistance, and voluntary against higher resistance. Contralateral activation was observed in the supplementary motor area (SMA), the primary motor cortex (M1), and the somatosensory cortex (S1) in all three tasks in each subject, whereas ipsilateral activation differed in each cortical region for each task. SMA had the widest prevalence of ipsilateral activation in all three tasks. In the M1, ipsilateral activation was observed in all but 1 subject in the two voluntary tasks but in only a few subjects in the S1 in any of the tasks. Quantitative changes in signal intensity and spatial extent of activation differentiated the voluntary tasks from the passive task and were most pronounced in the S1.

Adolescent↗

PubMed2001

Gln3p nuclear localization and interaction with Ure2p in Saccharomyces cerevisiae.

Gln3p is one of two well characterized GATA family transcriptional activation factors whose function is regulated by the nitrogen supply of the cell. When nitrogen is limiting, Gln3p and Gat1p are concentrated in the nucleus where they bind GATA sequences upstream of nitrogen catabolite repression (NCR)-sensitive genes and activate their transcription. Conversely, in excess nitrogen, these GATA sequences are unoccupied by Gln3p and Gat1p because these transcription activators are excluded from the nucleus. Ure2p binds to Gln3p and Gat1p and is required for NCR-sensitive transcription to be repressed and for nuclear exclusion of these transcription factors. Here we show the following. (i) Gln3p residues 344-365 are required for nuclear localization. (ii) Replacing Ser-344, Ser-347, and Ser-355 with alanines has minimal effects on GFP-Gln3p localization. However, replacing Gln3p Ser-344, Ser-347, and Ser-355 with aspartates results in significant loss of its ability to be concentrated in the nucleus. (iii) N and C termini of the Gln3p region required for it to complex with Ure2p and be excluded from the nucleus are between residues 1-103 and 301-365, respectively. (iv) N and C termini of the Ure2p region required for it to interact with Gln3p are situated between residues 101-151 and 330-346, respectively. (v) Loss of Ure2p residues participating in either dimer or prion formation diminishes its ability to carry out NCR-sensitive regulation of Gln3p activity.

Amino Acid Sequence↗

PubMed2001

Ammonia regulates VID30 expression and Vid30p function shifts nitrogen metabolism toward glutamate formation especially when Saccharomyces cerevisiae is grown in low concentrations of ammonia.

The GATA family proteins Gln3p and Gat1p mediate nitrogen catabolite repression (NCR)-sensitive transcription in Saccharomyces cerevisiae. When cells are cultured with a good nitrogen source (glutamine, ammonia), Gln3p and Gat1p are restricted to the cytoplasm, whereas with a poor nitrogen source (proline), they localize to the nucleus, bind to the GATA sequences of NCR-sensitive gene promoters, and activate transcription. The target of rapamycin-signaling cascade and Ure2p participate in regulating the cellular localization of Gln3p and Gat1p. Rapamycin, a Tor protein inhibitor, like growth with a poor nitrogen source, promotes nuclear localization of Gln3p and Gat1p. gln3 Delta and ure2 Delta mutants are partially resistant and hypersensitive to growth inhibition by rapamycin, respectively. We show that a vid30 Delta is more rapamycin-sensitive than wild type but less so than a ure2 Delta. VID30 expression is modestly NCR-sensitive, responsive to deletion of URE2, and greatly increases in low ammonia medium. Patterns of gene expression in a vid30 Delta suggest that the Vid30p function shifts the balance of nitrogen metabolism toward the production of glutamate, especially when cells are grown in low ammonia. CAN1, DAL4, DAL5, MEP2, DAL1, DAL80, and GDH3 transcription is down-regulated by Vid30p function with proline as the nitrogen source. An effect, however, that could easily be indirect.

Ammonia↗

PubMed2001

Cis-acting sites contributing to expression of divergently transcribed DAL1 and DAL4 genes in S. cerevisiae: a word of caution when correlating cis-acting sequences with genome-wide expression analyses.

Correlating genome-wide expression profiles with sequence searches of promoter regions is being used as a technique to identify putative binding sites for transacting factors or to refine consensus sequences of those already known. To evaluate the limitations of such an approach in our studies of GATA-mediated transcription in Saccharomyces cerevisiae, we identified the relative contributions made to DAL1 and DAL4 expression by each of five Gln3p-, and/or Gat1p-, and three Dal82p-binding site homologous sequences situated in the 829-bp intergenic region separating these highly related, divergently transcribed genes. Our data suggest that although the correlation of repeated sequences or sequence homologies appearing within promoter regions with expression profiles obtained from genome-wide transcription analyses can provide useful starting points for analyses of cis-acting sites, significant limitations and possibilities for misinterpretation also abound.

Amidohydrolases↗

PubMed2001

Biarticular and monoarticular muscle activation and injury in human quadriceps muscle.

We hypothesized that activation of the quadriceps femoris muscle group during eccentric exercise is related to the increase in magnitude of several markers of muscle injury that developed during the next week. Fourteen male subjects performed six to eight sets of five to ten repetitions of single-leg eccentric-only seated knee extension exercise. Magnetic resonance (MR) images were collected before and immediately after exercise and on days 2-4 and 6 after eccentric exercise. Changes in maximal voluntary contraction (MVC), perceived soreness, muscle volume and muscle transverse relaxation of water protons (T2) were determined for the quadriceps femoris muscle group each day. Changes in muscle volume and T2 were determined every day for each muscle [vastus lateralis (VL), vastus medialis (VM), vastus intermedius (VI), rectus femoris (RF)] of the quadriceps femoris group. Post-exercise T2 was greater than pre-exercise T2 (P < 0.05) for all muscles. The acute deltaT2 (Post-Pre) was similar (P>0.05) among VL, VM, VI, and RF [5.5 (0.3) ms], suggesting that the four muscles were equally activated during eccentric exercise. In the week after eccentric exercise, subjects experienced delayed-onset muscle soreness (DOMS) and all muscles demonstrated a delayed increase in T2 above pre-exercise values (P < 0.05), suggesting that muscle injury had occurred. For the quadriceps femoris muscle group, there was no correlation between acute deltaT2 and delayed (peak T2 during days 2, 3, 4, 6 minus pre-exercise T2) deltaT2 (r=0.04, P>0.05). Similar results were obtained when VL, VM, VI and RF were examined separately. Of the four muscles in quadriceps femoris, the biarticular RF experienced greater muscle injury [delayed deltaT2= 15.2 (2.0) ms] compared to the three monoarticular vasti muscles [delayed deltaT2 = 7.7 (1.3) ms; P< 0.05]. We propose that the disproportionate muscle injury to RF resulted from an ineffective transfer of torque from the knee to hip joint during seated eccentric knee extension exercise, thus causing RF to dissipate greater energy than normal. We conclude that in humans, muscle activation is not a unique determinant of muscle injury.

Adult↗

PubMed2001

Changes of the major sperm maturation-associated epididymal protein HE5 (CD52) on human ejaculated spermatozoa during incubation.

HE5 (CD52) is a glycoprotein which is secreted by the epididymis and which becomes inserted onto maturing spermatozoa. We have previously shown that, in cynomolgus monkey spermatozoa, changes occur upon maturation rendering cryptic the epitope to the monoclonal antibody CAMPATH-1G; the recognition site is then re-exposed during incubation under capacitation conditions. The present study investigated human ejaculated spermatozoa during incubation under similar conditions, using monoclonal antibodies that recognize different epitopes of the HE5 molecule comprising parts of the N-glycan (2E5) or peptide segments, including (CAMPATH-1G) or excluding (097) the glycosylphosphatidylinositol (GPI) anchor, to reveal modifications of sperm surface HE5. Flow cytometric analysis showed equally high percentages (approximately 90%) of viable spermatozoa cross-reacting with the antibodies before and after 6 h incubation. However, during incubation, the staining intensity increased 57% with CAMPATH-1G, 31% with 097, but remained unchanged with 2E5. The lymphocyte CD52 antibody CF1D12 stained only approximately 10% of spermatozoa either before or after incubation. Western blotting of sperm protein extracts using lectins indicated an increase in the exposure of sialic acid residues of HE5 after incubation. These results suggest that during incubation in capacitating conditions, there is an opening up of the HE5 glycoprotein molecule, increasing accessibility of some sialic acid residues and of the core peptide, particularly the GPI anchor.

Antibodies, Monoclonal↗

PubMed2001

Effects of the ion-channel blocker quinine on human sperm volume, kinematics and mucus penetration, and the involvement of potassium channels.

Sperm defects in the infertile c-ros knockout mouse model have recently highlighted the importance of volume regulation in sperm function. In this study, washed human spermatozoa were shown to change size and shape, as detected by flow cytometry and light microscopy, in response to the ion-channel blocker quinine (minimum effective doses at 20 and 125 micromol/l respectively). The increase in sperm volume was accompanied by reduced straight-line velocity (VSL) and linearity (LIN) of the swim-path but increased lateral head displacement and curvilinear velocity, while percentage motility was unaffected. Spermatozoa in semen and in artificial cervical mucus were similarly affected at 0.2 and 0.5 mmol/l quinine, resulting in marked reduction of mucus penetration and migration. The effects of quinine on sperm volume and kinematics were reduced or abolished by the K(+)-ionophores valinomycin (1 and 5 micromol/l) and gramicidin (0.5 and 1 micromol/l). In Ca(2+)-free medium; however, the quinine effects largely persisted. The K(+)-channel blocker, 4-aminopyridine (1 and 4 mmol/l), mimicked the quinine effects in the reduction of VSL and LIN, while the K(+)-channel blocker, tetraethylammonium chloride (TEA, 2.5-10 mmol/l), did not affect kinematics. The K(+)-channel (Kv1.3)-specific inhibitor, margatoxin, and the Ca(2+)-dependent K(+)-channel blocker, charybdotoxin, also had no effects. This study suggests that volume regulation in human spermatozoa and the linear trajectory of their motion may rely on quinine-sensitive and TEA-insensitive, largely calcium-independent, potassium channels, and possibly volume-sensitive organic anion channels. These channels could be targets for contraception.

Calcium↗

PubMed2001

Green fluorescent protein-Dal80p illuminates up to 16 distinct foci that colocalize with and exhibit the same behavior as chromosomal DNA proceeding through the cell cycle of Saccharomyces cerevisiae.

Four GATA family DNA binding proteins mediate nitrogen catabolite repression-sensitive transcription in Saccharomyces cerevisiae. Gln3p and Gat1p are transcriptional activators, while Dal80p and Deh1p repress Gln3p- and Gat1p-mediated transcription by competing with these activators for binding to DNA. Strong Dal80p binding to DNA is thought to result from C-terminal leucine zipper-mediated dimerization. Many Dal80p binding site-homologous sequences are relatively evenly distributed across the S. cerevisiae genome, raising the possibility that Dal80p might be able to "stain" DNA. We demonstrate that cells containing enhanced green fluorescent protein-Dal80p (EGFP-Dal80p) exhibit up to 16 fluorescent foci that colocalize with DAPI (4',6'-diamidino-2-phenylindole)-positive material and follow DNA movement through the cell cycle, suggesting that EGFP-Dal80p may indeed be useful for monitoring yeast chromosomes in live cells and in real time.

Cell Cycle↗

PubMed2001

Fiber type and metabolic dependence of T2 increases in stimulated rat muscles.

This study examined the relationships between muscle fiber type, metabolism, and blood flow vs. the increase in skeletal muscle (1)H-NMR transverse relaxation time (T2) after stimulation. Triceps surae muscles of anesthetized rats were stimulated in situ at 1-10 Hz for 6 min, and T2 was calculated from (1)H-NMR images acquired at 4.7 T immediately after stimulation. At low-to-intermediate frequencies (1-5 Hz), the stimulation-induced T2 increase was greater in the superficial, fast-twitch white portion of the gastrocnemius muscle compared with the deeper, more aerobic muscles of the triceps surae group. Although whole triceps muscle area changed in parallel with T2 after stimulation when blood flow was intact, clamping of the femoral artery during stimulation prevented an increase in muscle area but not an increase in T2. Partial inhibition of lactic acid production with iodoacetate diminished intracellular acidification (measured by (31)P-NMR spectroscopy) during brief (1.5 min) stimulation but had no significant effect either on estimated osmolite accumulation or on muscle T2 after stimulation. Depletion of muscle phosphocreatine content by feeding rats beta-guanidinopropionate decreased both estimated osmolite accumulation and T2 after 1.5-min stimulation. The results are consistent with the hypothesis that the T2 increase in stimulated muscle is related to osmotically driven shifts of fluid into an intracellular compartment.

Anatomy, Cross-Sectional↗

PubMed2001

Synthesis and glycosylation of CD52, the major 'maturation-associated' antigen of rat spermatozoa, in the cauda epididymidis.

A western and lectin blot analysis was performed of the major 'maturation-associated' antigen of rat spermatozoa, which is the rat counterpart of human CD52. In the absence of a suitable antibody, direct study of this approximately 26 kDa antigen, named previously SMemG, had been difficult. In the present study, these problems were overcome by raising a polyclonal antibody against a chemosynthetic peptide predicted from the cDNA sequence of the antigen. The antibody bound to a glycoprotein of rat cauda epididymidal tissue and spermatozoa, this glycoprotein was cleaved by phosphatidylinositol-specific phospholipase C and, after deglycosylation, was reduced to approximately 6 kDa. Northern blot analysis confirmed that the CD52 mRNA was transcribed only post-testicularly, and antibody binding to testicular and sperm proteins of different molecular masses was shown to be nonspecific. Flow cytometry also indicated that the antigen was inserted into the sperm membrane during epididymal transit. Moreover, despite the presence of CD52 mRNA in all parts of the rat epididymis, only the 'long' mRNA molecules of the cauda region were efficiently translated and the antigen glycosylated, indicating that expression of rat CD52 is regulated on a post-transcriptional level. Lectin binding and deglycosylation studies supported the contention that there is extensive mucin-type O-glycosylation of rat CD52. In rats, there was no indication of complex N-linked carbohydrates similar to those described for human CD52.

Animals↗

PubMed2000

Roles of the Dal82p domains in allophanate/oxalurate-dependent gene expression in Saccharomyces cerevisiae.

Allophanate/oxalurate-induced gene expression in Saccharomyces cerevisiae requires at least five transcription factors, four of which act positively (Gln3p, Gat1p, Dal81p, and Dal82p) and one negatively (Dal80p). Gln3p binds to and Gat1p is proposed to bind to single GATA sequences; Dal80p binds to pairs of specifically oriented and spaced GATA sequences, and Dal82p binds to a pathway-specific element, UIS(ALL). Dal82p consists of at least three domains as follows: (i) UIS(ALL) DNA-binding, (ii) transcriptional activation, and (iii) coiled-coil(DAL82). Here we show that the coiled-coil(DAL82) domain possesses two demonstrable functions. (i) It prevents Dal82p-mediated transcription when inducer is absent. (ii) It is a major, although not exclusive, domain through which the inducer signal is received. Supporting the latter conclusion, a 38-amino acid fragment, containing little more than the coiled-coil(DAL82) domain, supports oxalurate-inducible, Dal81p-dependent, reporter gene transcription. Dal81p is required for inducer responsiveness of LexAp-Dal82p and LexAp coiled-coil(DAL82)-mediated transcription but isn't needed for inducer-dependent activation mediated by a Dal82p containing deletions in both the coiled-coil(DAL82), UIS(ALL)-binding domains. There may be an interaction between Dal81p and the coiled-coil(DAL82) domain since (i) Dal81p is required for transcription mediated by LexA-coiled-coil(DAL82)p and (ii) a Dal81p-Dal82p complex is detected by two-hybrid assay.

Bacterial Proteins↗

PubMed2000

Saccharomyces cerevisiae GATA sequences function as TATA elements during nitrogen catabolite repression and when Gln3p is excluded from the nucleus by overproduction of Ure2p.

Saccharomyces cerevisiae selectively uses good nitrogen sources (glutamine) in preference to poor ones (proline) by repressing GATA factor-dependent transcription of the genes needed to transport and catabolize poor nitrogen sources, a physiological process designated nitrogen catabolite repression (NCR). We show that some NCR-sensitive genes (CAN1, DAL5, DUR1,2, and DUR3) produce two transcripts of slightly different sizes. Synthesis of the shorter transcript is NCR-sensitive and that of the longer transcript is not. The longer transcript also predominates in gln3Delta mutants irrespective of the nitrogen source provided. We demonstrate that the longer mRNA species arises through the use of an alternative transcription start site generated by Gln3p-binding sites (GATAAs) being able to act as surrogate TATA elements. The ability of GATAAs to serve as surrogate TATAs, i.e. when synthesis of the shorter, NCR-sensitive transcripts are inhibited, correlates with sequestration of enhanced green fluorescent protein (EGFP)-Gln3p in the cytoplasm in a way that is indistinguishable from that seen with EGFP-Ure2p. However, when the shorter, NCR-sensitive DAL5 transcript predominates, EGFP-Gln3p is nuclear. These data suggest that the mechanism underlying NCR involves the cytoplasmic association of Ure2p with Gln3p, an interaction that prevents Gln3p from reaching it is binding sites upstream of NCR-sensitive genes.

Amino Acid Transport Systems↗

PubMed2000

Nitrogen catabolite repression of DAL80 expression depends on the relative levels of Gat1p and Ure2p production in Saccharomyces cerevisiae.

GATA family activators (Gln3p and Gat1p) and repressors (Dal80p and Deh1p) regulate nitrogen catabolite repression (NCR)-sensitive transcription in Saccharomyces cerevisiae presumably via their competitive binding to the GATA sequences upstream of NCR-sensitive genes. Ure2p, which is not a GATA family member, inhibits Gln3p/Gat1p from functioning in the presence of good nitrogen sources. We show that NCR-sensitive DAL80 transcription can be influenced by the relative levels of GAT1 and URE2 expression. NCR, normally observed with ammonia or glutamine, is severely diminished when Gat1p is overproduced, and this inhibition is overcome by simultaneously increasing URE2 expression. Further, overproduction of Ure2p nearly eliminates NCR-sensitive transcription under derepressive growth conditions, i.e. with proline as the sole nitrogen source. Enhanced green fluorescent protein-Gat1p is nuclear when Gat1p-dependent transcription is high and cytoplasmic when it is inhibited by overproduction of Ure2p.

Base Sequence↗