Effects of superovulated heifer diet type and quantity on relative mRNA abundances and pyruvate metabolism in recovered embryos

This study investigated the effects of quantity and type of diet fed to superovulated donor heifers on molecular and metabolic indices of embryonic development. These effects included the relative abundances of mRNAs for the alpha 1 subunit of Na/K-ATPase and the antioxidant enzyme Cu/Zn-SOD, as well as pyruvate utilization in bovine morulae and blastocysts developed in vivo. Heifers were fed a daily ration of either grass silage and a citrus-beet pulp-based concentrate or grass silage and a barley-based concentrate for 116 days, both at 3 kg per day or ad libitum. In embryos derived from heifers fed the pulp-based diets, the relative abundances of the transcripts were not affected by either day of collection or quantity of diet. In embryos derived from heifers fed the barley-based diets, the relative abundances of the Na/K-ATPase transcripts were also not changed by these main effects, while the relative abundances of the Cu/Zn-SOD transcripts were affected by day of collection and by the quantity of diet. Pyruvate metabolism was affected by day of collection, and was significantly increased in day 8 embryos compared with day 7 and day 6 embryos. Diet quantity did not affect pyruvate utilization, whereas diet type did increase pyruvate metabolism in the barley group when compared with the pulp group. The results of this study show for the first time that molecular and metabolic variations may exist in embryos derived in vivo and developed in donor heifers on nutritional regimens differing in type and quantity. Differences in embryos collected on different developmental days may be attributed to varying cell numbers. Alterations in the relative abundances of the Cu/Zn-SOD transcripts and pyruvate metabolism caused by the quantity of diet fed to the donor animal were likely to have been due to alterations in metabolic end products that accumulate in reproductive tract fluids, whereas differences in embryonic metabolism caused by type of diet are related to the composition of the diet. These findings characterize embryos produced in vivo at the molecular level, indicating that the molecular markers used in the present study can differentiate between populations of embryos produced under different nutritional regimens and determine conditions conductive to the production of good quality embryos.

A prospective study examining the association between the symptoms of anxiety and depression and severity of urinary incontinence

OBJECTIVE

To investigate the association of the presence or absence of the symptoms of anxiety and depression compared with the 48 h pad test as an objective measure of incontinence.

DESIGN

Prospective study.

SETTING

Urodynamics clinic in a large teaching hospital.

SUBJECTS

All patients with urinary incontinence attending for urodynamic assessment from 23.4.96 to 29.10.96.

INTERVENTIONS

48 h pad test, Hospital Anxiety and Depression scale (HAD scale).

MAIN OUTCOME MEASURES

Urodynamic diagnosis of cause of incontinence. Urinary loss over 48 h as measured by weight change in pads. Presence of symptoms of anxiety or depression as defined by HAD scale score of 8 or more.

RESULTS

Urodynamic investigation was performed for incontinence on 133 patients. Of these 127 (95.4%) completed the HAD scale questionnaire. Of the 43 patients (32.2%) who returned the pads 18 (41.8%) patients were found to have symptoms of anxiety and six patients (13.9%) had symptoms of depression. Patients with symptoms of anxiety had lower mean measured urinary loss over a 48 h period compared to women with no symptoms of anxiety (median loss 44.2 ml range 6.8-622.4 versus 97.1 ml range 8.2-4384.4 ml) (P=0.05). There was no significant association between symptoms of depression and pad test results.

CONCLUSIONS

Patients presenting with incontinence who have symptoms of anxiety are on average less incontinent compared to than those without symptoms of anxiety. It suggests that anxious patients present with a lesser degree of incontinence than nonanxious patients.

Pyrrolidinedithiocarbamate increases the therapeutic index of 5-fluorouracil in a mouse model

BACKGROUND & AIMS

The thiol-containing antioxidant pyrrolidinedithiocarbamate (PDTC) enhances the cytotoxic efficacy of 5-fluorouracil (5-FU) against human colorectal cancer cell lines in vitro and in vivo. This process appears to be mediated by a sustained increase in p21 expression, independent of p53 function, resulting in growth arrest and apoptosis. We determined whether PDTC augmented 5-FU intestinal toxicity in non-tumor-bearing mice.

METHODS

Apoptotic and mitotic indices were measured in the small and large intestine on a cell positional basis at intervals throughout the 72-hour period after administration of 5-FU (40 mg/kg) and PDTC (250 mg/kg). The proportion of crypts regenerating after 5-FU (600-1200 mg/kg) and PDTC (500 mg/kg) was also measured.

RESULTS

5-FU therapy induces substantial apoptotic cell death with simultaneous inhibition of mitotic activity within the small and large intestinal epithelium. PDTC reduces 5-FU-induced apoptotic events in the colon by 49%, predominantly among clonogenic stem and transit cells while promoting the early recovery of mitotic activity. As a consequence, PDTC increased the proportion of regenerating colonic crypts after 5-FU therapy. PDTC did not, however, significantly modulate 5-FU toxicity in the small intestine.

CONCLUSIONS

PDTC does not augment the intestinal toxicity of 5-FU and actually protects the colonic mucosa. These results support further investigation of PDTC and related compounds as treatments for colorectal cancer.

Effects of superovulated heifer diet type and quantity on relative mRNA abundances and pyruvate metabolism in recovered embryos

This study investigated the effects of quantity and type of diet fed to superovulated donor heifers on molecular and metabolic indices of embryonic development. These effects included the relative abundances of mRNAs for the alpha 1 subunit of Na/K-ATPase and the antioxidant enzyme Cu/Zn-SOD, as well as pyruvate utilization in bovine morulae and blastocysts developed in vivo. Heifers were fed a daily ration of either grass silage and a citrus-beet pulp-based concentrate or grass silage and a barley-based concentrate for 116 days, both at 3 kg per day or ad libitum. In embryos derived from heifers fed the pulp-based diets, the relative abundances of the transcripts were not affected by either day of collection or quantity of diet. In embryos derived from heifers fed the barley-based diets, the relative abundances of the Na/K-ATPase transcripts were also not changed by these main effects, while the relative abundances of the Cu/Zn-SOD transcripts were affected by day of collection and by the quantity of diet. Pyruvate metabolism was affected by day of collection, and was significantly increased in day 8 embryos compared with day 7 and day 6 embryos. Diet quantity did not affect pyruvate utilization, whereas diet type did increase pyruvate metabolism in the barley group when compared with the pulp group. The results of this study show for the first time that molecular and metabolic variations may exist in embryos derived in vivo and developed in donor heifers on nutritional regimens differing in type and quantity. Differences in embryos collected on different developmental days may be attributed to varying cell numbers. Alterations in the relative abundances of the Cu/Zn-SOD transcripts and pyruvate metabolism caused by the quantity of diet fed to the donor animal were likely to have been due to alterations in metabolic end products that accumulate in reproductive tract fluids, whereas differences in embryonic metabolism caused by type of diet are related to the composition of the diet. These findings characterize embryos produced in vivo at the molecular level, indicating that the molecular markers used in the present study can differentiate between populations of embryos produced under different nutritional regimens and determine conditions conductive to the production of good quality embryos.

Characterization of a bovine cDNA encoding citrate synthase, and presence of citrate synthase mRNA during bovine pre-attachment development

Citrate synthase is a key regulatory metabolic enzyme that catalyzes the first step in the tricarboxylic acid (TCA) cycle, the synthesis of citrate from acetyl coenzyme A and oxaloacetate. Aerobic metabolism via the TCA cycle is high in bovine embryos at the 4-cell stage then decreases until the compact morula stage before increasing at the expanded blastocyst stage. This study characterizes the presence of citrate synthase mRNA in bovine pre-attachment embryos to determine if a variation in mRNA transcript expression patterns is associated with previous reports of the patterns of TCA cycle activity. The reverse transcription-polymerase chain reaction (RT-PCR) method was used to detect citrate synthase mRNA from the 1-cell to blastocyst stage of bovine embryo development, and in embryos cultured under either an atmosphere of 5% CO(2) in air or 5% CO(2)/5% O(2)/90%N(2). The nucleotide sequence encoding citrate synthase was determined from bovine heart cDNA by the rapid amplification of cDNA ends (RACE) technique. This 1455-bp nucleotide fragment contained an open reading frame that encoded a deduced protein of 466 amino acids. The bovine nucleotide sequence was 92.1% and 93.8% identical to the human and porcine coding sequence, respectively. The amino acid sequence predicted from the bovine sequence is 95.1% identical to the human sequence and 96.3% identical to the porcine sequence. The porcine sequence contains a stop codon that results in a peptide truncated by 2 amino acids. The detection of citrate synthase transcripts from the 1-cell to blastocyst stage demonstrates that the decrease in TCA cycle activity observed following the 4-cell stage is not associated with an absence of citrate synthase mRNA.

Role of MAP kinase pathways in mediating IL-6 production in human primary mesangial and proximal tubular cells

BACKGROUND

Both interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) are pleiotropic cytokines that have been implicated in the development of glomerular and tubular injury in various forms of immune-mediated renal disease, including glomerulonephritis. Although TNF-alpha has been shown to stimulate IL-6 production in renal cells in culture, the signaling mechanisms that regulate IL-6 production are not fully understood. The aim of this study was to examine the role of the p38 and extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase (MAPK) pathways in regulating TNF-alpha-mediated IL-6 production from both primary human mesangial cells (HMCs) and human proximal tubular (HPT) cells.

METHODS

Primary mesangial and proximal tubular cells were prepared from nephrectomized human kidney tissue. Cells were treated for 24 hours with TNF-alpha in the presence and absence of the specific p38 and ERK1,2 MAPK inhibitors SB203580 and PD98059, respectively, either alone or in combination. IL-6 levels in the cell culture media were measured by enzyme-linked immunosorbent assay. MAPK activation was demonstrated by immunoblot for the active kinase (tyrosine/threonine phosphorylated) in whole cell extracts using phospho-specific antibodies. p38 MAPK activity in HPT cells was measured using an in vitro immunokinase assay using ATF2 as the substrate.

RESULTS

TNF-alpha (0.1 to 100 ng/ml) stimulated a dose-dependent increase in IL-6 production in both renal cell types. The activation of the p38 and the ERK1,2 MAPKs occurred following TNF-alpha stimulation. The role of these activations in IL-6 production was confirmed by the ability of both inhibitors SB203580 (1 to 30 microM) and PD98059 (0.01 to 10 microM) to inhibit basal and TNF-alpha-stimulated IL-6 production in both cell types. The addition of both inhibitors in combination caused greater decreases in IL-6 production compared with either inhibitor alone. Pretreatment with SB203580 (10 microM) had no effect on basal or TNF-alpha-stimulated phosphorylation of p38 MAPK but completely abolished TNF-alpha-stimulated p38 MAPK activity. PD98059 decreased both basal and TNF-alpha-stimulated phosphorylation of ERK1,2.

CONCLUSIONS

This study provides evidence that both the p38 and ERK MAPK pathways are important for the regulation of the production of IL-6 from the proximal tubular and glomerular mesangial regions of the nephron. In response to TNF-alpha, the activation of both pathways leads to IL-6 production. These findings could aid in an understanding of the cellular mechanisms that regulate IL-6 production and could provide insights into possible pharmacological strategies in inflammatory renal disease.

Factors produced by activated leukocytes alter renal epithelial cell differentiation

The development of tubulointerstitial fibrosis in inflammatory renal diseases has been linked to disease progression to end-stage renal failure. Understanding the interactions of the factors influencing inflammation and activating the fibrotic process, that is, the inflammatory infiltrate and the resident proximal tubular cells, may lead to a determination of the mechanisms that regulate tubulointerstitial fibrosis. We used an in vitro model of human proximal tubule cells that were stimulated with supernatant from activated peripheral blood mononuclear cells (leukocytes) to study the alterations in cellular phenotype, and examined the signaling pathways mediating epithelial-fibroblast like transdifferentiation. Our hypothesis of the proposed sequence of events leading to tubulointerstitial fibrosis is explained.

Apoptosis in multinucleated skeletal muscle myotubes

Several recent studies report endonuclease-mediated DNA degradation as evidence of apoptotic degeneration of skeletal muscle in the muscular dystrophies and other muscle disorders. Interpretation of the results of such studies is complicated by the ubiquitous presence of non-muscle cells within muscle in vivo and by a lack of knowledge concerning the nature of the process of apoptosis in postmitotic, multinucleated skeletal muscle and the potential mechanisms involved. Staurosporine treatment of C2C12 skeletal muscle myotubes induced several classic features of apoptosis, including cell and nuclear shrinkage with initial preservation of cellular membranes. Externalization of phosphatidylserine occurred within 2 hours of treatment, and myotubes contained procaspase 3, which seemed to be activated within 4 hours. DNA degradation was identified by transferase uridine triphosphate nick-end labeling within 4 hours, and DNA ladders were identified on agarose electrophoresis of genomic DNA within 8 hours. Thus, the process of apoptosis in postmitotic multinucleated skeletal muscle shares many of the characteristics of apoptosis in mononuclear mitotic cells. However, the pattern of degeneration does not seem to be compatible with that seen in the muscular dystrophies.

Immunization against SIVmne in macaques using multigenic DNA vaccines

All structural and regulatory genes of SIVmne were cloned into mammalian expression vectors to optimize expression in vitro and immunogenicity in mice. Macaca fascicularis were immunized four times with plasmid DNA (n = 4), or two DNA priming inoculations followed by two boosts of recombinant gp160 plus Gag-Pol particles (n = 4). Following intrarectal challenge with SIVmne, all macaques became infected. Three monkeys immunized with DNA alone maintained low plasma virus loads by 1 year post-challenge; the fourth exhibited high virus loads and significant CD4+ cell decline. Two of the DNA plus boost and three control macaques had high virus loads and associated CD4+ cell decline. Both vaccine protocols elicited antibodies and comparable helper T-cell proliferative responses to gp160. Cytokine mRNA levels in activated peripheral blood mononuclear cells (PBMC) taken at time of challenge suggested a dominant T helper (Th) 1 state in three DNA-immunized and one protein-boosted macaque, which correlated with low virus loads and high CD4+ cell counts post-challenge.

Cytoplasmic acidification is not an effector mechanism of VP16 or DEX-induced apoptosis in CEM T leukaemia cells

The role of intracellular acidification in the execution phase of apoptosis is not well understood. Here we examine the effect of Bcl-2 over-expression on intracellular acidification occurring during apoptosis. We found, that in CEM cells, neither DEX nor VP16-induced apoptosis lead to a significant change in intracellular pH (pHi). Furthermore, we found that shifting pHi away from physiological values was unable to induce chromatin condensation or poly(ADP-ribose) polymerase (PARP) cleavage in the presence of Bcl-2 over-expression. However, it was found that maximum chromatin condensation and PARP cleavage occurred at near physiological pHi values. Taken together these data suggest that intracellular acidification does not trigger the effector phase of CEM apoptosis.

Identification and characterisation of the Drosophila melanogaster O6-alkylguanine-DNA alkyltransferase cDNA

The protein O 6-alkylguanine-DNA alkyltransferase(alkyltransferase) is involved in the repair of O 6-alkylguanine and O 4-alkylthymine in DNA and plays an important role in most organisms in attenuating the cytotoxic and mutagenic effects of certain classes of alkylating agents. A genomic clone encompassing the Drosophila melanogaster alkyltransferase gene ( DmAGT ) was identified on the basis of sequence homology with corresponding genes in Saccharomyces cerevisiae and man. The DmAGT gene is located at position 84A on the third chromosome. The nucleotide sequence of DmAGT cDNA revealed an open reading frame encoding 194 amino acids. The MNNG-hypersensitive phenotype of alkyltransferase-deficient bacteria was rescued by expression of the DmAGT cDNA. Furthermore, alkyltransferase activity was identified in crude extracts of Escherichia coli harbouring DmAGT cDNA and this activity was inhibited by preincubation of the extract with an oligonucleotide containing a single O6-methylguanine lesion. Similar to E.coli Ogt and yeast alkyltransferase but in contrast to the human alkyltransferase, the Drosophila alkyltransferase is resistant to inactivation by O 6-benzylguanine. In an E.coli lac Z reversion assay, expression of DmAGT efficiently suppressed MNNG-induced G:C-->A:T as well as A:T-->G:C transition mutations in vivo. These results demonstrate the presence of an alkyltransferase specific for the repair of O 6-methylguanine and O 4-methylthymine in Drosophila.

A prospective placebo controlled double blind randomised study to investigate the use of indoramin to prevent post-operative voiding disorders after surgical treatment for genuine stress incontinence

A prospective placebo controlled double blind randomised study was undertaken to investigate the use of indoramin an alpha blocker to prevent post-operative voiding disorders after surgical treatment for genuine stress incontinence. Fifty-six patients were randomised to receive indoramin 20 mg orally twice a day or identical placebo from the first post-operative day until discharge from hospital. After seven exclusions, 49 patients were included in the study. There was no significant difference between the treatment (indoramin) group and placebo group for any of the outcomes measured. The routine use of indoramin to prevent post-operative voiding problems cannot be justified on the basis of these data.

Protection from pathogenic SIV challenge using multigenic DNA vaccines

To assess DNA immunization as a strategy for protecting against HIV infection in humans, we utilized SIVmne infection of Macaca fascicularis as a vaccine challenge model with moderate pathogenic potential. We compared the efficacy of DNA immunization alone and in combination with subunit protein boosts. All of the structural and regulatory genes of SIVmne clone 8 were cloned into mammalian expression vectors under the control of the CMV IE-1 promoter. Eight M. fascicularis were immunized twice with 3 mg of plasmid DNA divided between two sites; intramuscular and intradermal. Four primed macaques received a further two DNA immunizations at weeks 16-36, while the second group of four were boosted with 250 microg recombinant gp160 plus 250 microg recombinant Gag-Pol particles formulated in MF-59 adjuvant. Half of the controls received four immunizations of vector DNA; half received two vector DNA and two adjuvant immunizations. As expected, humoral immune responses were stronger in the macaques receiving subunit boosts, but responses were sustained in both groups. Significant neutralizing antibody titers to SIVmne were detected in one of the subunit-boosted animals and in none of the DNA-only animals prior to challenge. T-cell proliferative responses to gp160 and to Gag were detected in all immunized animals after three immunizations, and these responses increased after four immunizations. Cytokine profiles in PHA-stimulated PBMC taken on the day of challenge showed trends toward Thl responses in 2/4 macaques in the DNA vaccinated group and in 1/4 of the DNA plus subunit vaccinated macaques; Th2 responses in 3/4 DNA plus subunit-immunized macaques; and Th0 responses in 4/4 controls. In bulk CTL culture, SIV specific lysis was low or undetectable, even after four immunizations. However, stable SIV Gag-Pol- and env-specific T-cell clones (CD3+ CD8+) were isolated after only two DNA immunizations, and Gag-Pol- and Nef-specific CTL lines were isolated on the day of challenge. All animals were challenged at week 38 with SIVmne uncloned stock by the intrarectal route. Based on antibody anamnestic responses (western, ELISA, and neutralizing antibodies) and virus detection methods (co-culture of PBMC and LNMC, nested set PCR- of DNA from PBMC and LNMC, and plasma QC-PCR), there were major differences between the groups in the challenge outcome. Surprisingly, sustained low virus loads were observed only in the DNA group, suggesting that four immunizations with DNA only elicited more effective immune responses than two DNA primes combined with two protein boosts. Multigenic DNA vaccines such as these, bearing all structural and regulatory genes, show significant promise and may be a safe alternative to live-attenuated vaccines.

Tetrazepinones are equally cytotoxic to Mer+ and Mer- human tumor cell lines

Human brain and colon tumor cell lines SF-188 (Mer+) and WiDR (Mer+), which express the DNA repair protein O6-methylguanine-DNA methyl transferase (MGMT), were 3- to 30-fold less sensitive to temozolomide, mitozolomide, and N, N'-bis(2-chloroethyl)-N-nitrosourea (BCNU) than the MGMT-deficient tumor cells SF-126 (Mer-) and BE (Mer-). This differential sensitivity was not observed when these cells were exposed to the novel tetrazepinones PYRZ, NIME, QUINCL, and PYRCL, which contain, like temozolomide and mitozolomide, a ureido-triazene moiety. Flow cytometric studies revealed that temozolomide induced G2-M arrest in the Mer- cells, but exerted a minor effect on the cycle of the Mer+ cells. Similarly, mitozolomide (25-100 microM) induced a stronger S-phase arrest in the SF-126 cells than in the SF-188 cells. In the same dose range (25-100) BCNU induced a significant cell cycle accumulation in G22-M in the SF-126 cells but little in the SF-188 cell line. In contrast, the cell cycle effects of the tetrazepinones were independent of the cell phenotypes. When O6-benzylguanine (O6-BG) was used to deplete MGMT activity in the SF brain tumor cell lines, significant potentiation of temozolomide (67-fold), mitozolomide (7-fold), and BCNU (3-fold) was observed in the SF-188 cell line. By contrast, O6-BG did not potentiate PYRZ, PYRCL, QUINCL, and NIME. Moreover, an MGMT inhibitory assay showed that all the tetrazepinones were capable of inactivating MGMT in the SF-188 cell line, the strongest inhibitor being PYRCL. The results suggest that, unlike temozolomide, mitozolomide, and BCNU, the cytotoxicity of the tetrazepinones does not correlate with the alkylation of the O6 position of guanine and that the mechanism of MGMT inactivation by tetrazepinones may differ from that of hitherto known inhibitors.

Gene expression regulating blastocyst formation

Development of embryos to the blastocyst stage is a critical event in the early lives of all eutherian mammalian species. Blastocyst formation is essential for implantation and is the principal morphological determinant of embryo quality prior to embryo transfer. The physiological events and roles of specific gene families that regulate blastocyst formation are subjects of intense research Recent findings have demonstrated that bovine embryos express multiple members of the Na/K-ATPase ion transporter gene family. Two members of this family have been co-localized to bovine trophectoderm, but each becomes largely confined to opposing cell membrane margins. Bovine blastocysts display a greater sensitivity to ouabain (potent inhibitor of the Na/K-ATPase) than murine blastocysts, and enzyme activity (ouabain sensitive 86Rb+ uptake) undergoes a 9-fold increase from the bovine morula to the blastocyst stage. Disruption of Na/K-ATPase gene expression by antisense oligodeoxynucleotide inhibition abolishes blastocyst formation. These results have implicated the Na/K-ATPase as a key regulator of bovine blastocyst formation and have provided insights necessary for the production of healthy bovine embryos by the application of in vitro maturation, in vitro fertilization and in vitro culture methods.

Homologs of aflatoxin biosynthesis genes and sequence of aflR in Aspergillus oryzae and Aspergillus sojae

The presence, but not expression, of homologs of three structural genes and a regulatory gene necessary for aflatoxin biosynthesis in Aspergillus parasiticus and A. flavus was shown for A. oryzae and A. sojae. Homologs of the regulatory gene aflR were cloned and sequenced from A. oryzae and A. sojae.

O (6)-Alkylguanine-DNA Alkyltransferase Assay

Alkylating agents exert a wide range of biological effects in both pro- and eukaryotes and there is ever increasing evidence that these effects are mediated via alkylation at the O (6)position of guanine in DNA (1-4). Repair of such adducts can be mediated by O (6)-alkylguanine-DNA alkyltransferase (ATase) (3,4). Both pro- and eukaryote ATases transfer alkyl groups from the O (6)-position of guanine in alkylated DNA (or from other low molecular weight substrates); (5) to a cysteine residue located at the active site of the protein: the reaction is stoichiometric and the protein is autoinactivated (6). This mechanism has been exploited in the design of several different radioactivity-based assays for the enzyme. These involve either measurement of methyl group transfer to protein or the analysis (e.g., by HPLC) of methylated substrate DNA before and after exposure to cell or tissue extracts or restriction endonuclease (RE) site deprotection of synthetic oligonucleotide substrates containing O (6)-methylguanine.

Inactivation of O6-alkylguanine-DNA alkyltransferase. 1. Novel O6-(hetarylmethyl)guanines having basic rings in the side chain

A number of novel guanine derivatives containing heterocyclic moieties at the O6-position have been synthesized using a purine quaternary salt which reacts with alkoxides under mild conditions. Initially O6-substituents were investigated in which the benzene ring of the known agent, O6-benzylguanine, was replaced by unsubstituted heterocyclic rings. The ability of these agents to inactivate the DNA repair protein O6-alkylguanine-DNA alkyltransferase (ATase), both as pure recombinant protein and in the human lymphoblastoid cell line Raji, has been compared with that of O6-benzylguanine. The present paper focuses on O6-substituents with basic rings, and under standard conditions several of them proved more effective than benzyl for inactivation of both recombinant and Raji ATase. Among the pyridine derivatives, the 2-picolyl compound 7 is not very active in contrast to the 3- and 4-picolyl compounds, and this influenced our choice of isomers of other basic ring systems for study. Since halogen substitution in the thiophene ring considerably increased the activity (17 versus 6), similar modifications in the pyridine series were examined. The more polar O6-substituents in this study are on the whole compatible with the stereochemical requirements of the ATase protein, and their pharmacological properties may be valuable in subsequent in vivo investigations, particularly the thenyl (6), 5-thiazolylmethyl (12), 5-bromothenyl (17), and 2-chloro-4-picolyl (21) derivatives.

Blood cells with reduced mitochondrial membrane potential and cytosolic cytochrome C can survive and maintain clonogenicity given appropriate signals to suppress apoptosis

Reduction of mitochondrial membrane potential (Psim) and release of cytochrome c from mitochondria appear to be key events during apoptosis. Apoptosis was induced in IC.DP premast cells by the withdrawal of interleukin-3 (IL-3). Psim decreased by 12 hours and cytochrome c was detected in the cytosol at 18 hours. Despite these changes in the mitochondria after 18 hours of IL-3 deprivation, clonogenicity was unaffected when IL-3 was replenished at 18 hours. Activation of v-Abl tyrosine kinase (v-Abl TK) in IC.DP cells before IL-3 depletion led to increased levels of Bcl-XL, prevented reduction of Psim and the release of mitochondrial cytochrome c, and suppressed apoptosis. Activation of v-Abl TK 18 hours after withdrawal of IL-3 when </=10% of the cells had died restored Psim in the remaining cells. More than 40% of cells thus rescued by v-Abl TK between 18 and 42 hours could subsequently form colonies in the presence of IL-3. These data suggest that reduction in Psim precedes loss of mitochondrial cytochrome c in IC.DP cells; that v-Abl TK activation, probably via upregulation of Bcl-XL, prevents loss of Psim and blocks the release of cytochrome c from mitochondria; and that neither of these mitochondrial events is sufficient for commitment to apoptosis.

Trophectoderm differentiation in the bovine embryo: characterization of a polarized epithelium

Blastocytst formation is dependent on the differentiation of a transporting epithelium, the trophectoderm, which is coordinated by the embryonic expression and cell adhesive properties of E-cadherin. The trophectoderm shares differentiative characteristics with all epithelial tissues, including E-cadherin-mediated cell adhesion, tight junction formation, and polarized distribution of intramembrane proteins, including the Na-K ATPase. The present study was conducted to characterize the mRNA expression and distribution of polypeptides encoding E-cadherin, beta-catenin, and the tight junction associated protein, zonula occludens protein 1, in pre-attachment bovine embryos, in vitro. Immunocytochemistry and gene specific reverse transcription--polymerase chain reaction methods were used. Transcripts for E-cadherin and beta-catenin were detected in embryos of all stages throughout pre-attachment development. Immunocytochemistry revealed E-cadherin and beta-catenin polypeptides evenly distributed around the cell margins of one-cell zygotes and cleavage stage embryos. In the morula, detection of these proteins diminished in the free apical surface of outer blastomeres. E-cadherin and beta-catenin became restricted to the basolateral membranes of trophectoderm cells of the blastocyst, while maintaining apolar distributions in the inner cell mass. Zonula occludens protein 1 immunoreactivity was undetectable until the morula stage and first appeared as punctate points between the outer cells. In the blastocyst, zonula occludens protein 1 was localized as a continuous ring at the apical points of trophectoderm cell contact and was undetectable in the inner cell mass. These results illustrate that the gene products encoding E-cadherin, beta-catenin and zonula occludens protein 1 are expressed and maintain cellular distribution patterns consistent with their predicted roles in mediating trophectoderm differentiation in in vitro produced bovine embryos.

Transient expression of a translation initiation factor is conservatively associated with embryonic gene activation in murine and bovine embryos

In the present study the abundance of mRNAs for eukaryotic translation initiation factors eIF-1A (formerly known as eIF-4C), -2alpha, -4A, -4E, and -5 was examined in in vivo-derived mouse embryos throughout preimplantation development using a semiquantitative reverse transcription-polymerase chain reaction assay. Although the mRNA profile for each gene is unique, only mRNA for eIF-1A transiently increases during embryonic gene activation (EGA) at the 2-cell stage, and this was confirmed by an independent hybridization-based assay. In in vitro-developed bovine embryos, mRNA for eIF-1A was transiently detected at the 8-cell stage, when the major activation of the genome occurs in this species. As in the mouse, detection in 8-cell bovine embryos was sensitive to the transcriptional inhibitor alpha-amanitin. It was also observed at the same time relative to cleavage in embryos cultured in defined medium under a reduced oxygen environment, and in medium supplemented with serum and somatic cells in 5% CO2 in air. Neither the chronology of early cleavage divisions nor the yield of bovine blastocysts differed in these culture media. Our results suggest that transient expression of eIF-1A in the mouse and cow is a conserved pattern of gene expression associated with EGA in mammals.

Effects of colony stimulating factor-1 on human extravillous trophoblast growth and invasion

Colony stimulating factor (CSF)-1 has been localized in a variety of tissues and shown to influence proliferation and differentiation of numerous cell types. Messenger RNA and protein products of CSF-1 and its receptor (c-fms) have been identified in the human placenta and decidua. We examined whether CSF-1 and c-fms mRNA and protein are expressed by normal human first trimester invasive extravillous trophoblast (EVT) cells propagated in culture and whether CSF-1 influences proliferation and/or invasion of these cells. CSF-1 mRNA and protein expression was determined by RT-PCR and immunofluorescence microscopy. Proliferation was assessed by the cellular uptake of tritiated thymidine and invasion was evaluated by Matrigel invasion assay as well as Northern blot analysis of mRNA expression for invasion-associated enzymes and their inhibitors. Results revealed that normal invasive EVT cells in culture express both CSF-1 and c-fms mRNA and protein. Under serum-free conditions, exogenous CSF-1 greatly stimulated the proliferation of these cells. CSF-1 neutralizing and c-fms receptor blocking antibody (Ab) each abolished the growth stimulatory effects of CSF-1, indicating that CSF-1 and c-fms interaction was responsible for these effects. In fact, c-fms Ab alone reduced proliferation to below background levels. While exogenous CSF-1 failed to influence EVT cell invasiveness, Northern blot analysis of mRNA indicated a slight upregulation of the invasion-associated enzyme 72 kDa type IV collagenase as well as its natural inhibitor tissue inhibitor of metalloprotease (TIMP)-1, so that the balance between the two remained unaltered. These findings suggest that CSF-1 may represent an autocrine (and possibly paracrine) growth stimulatory factor for the invasive trophoblast cells in situ with no net effect on their invasiveness.

Alkylpurine-DNA-N-glycosylase knockout mice show increased susceptibility to induction of mutations by methyl methanesulfonate

Alkylpurine-DNA-N-glycosylase (APNG) null mice have been generated by homologous recombination in embryonic stem cells. The null status of the animals was confirmed at the mRNA level by reverse transcription-PCR and by the inability of cell extracts of tissues from the knockout (ko) animals to release 3-methyladenine (3-meA) or 7-methylguanine (7-meG) from 3H-methylated calf thymus DNA in vitro. Following treatment with DNA-methylating agents, increased persistence of 7-meG was found in liver sections of APNG ko mice in comparison with wild-type (wt) mice, demonstrating an in vivo phenotype for the APNG null animals. Unlike other null mutants of the base excision repair pathway, the APNG ko mice exhibit a very mild phenotype, show no outward abnormalities, are fertile, and have an apparently normal life span. Neither a difference in the number of leukocytes in peripheral blood nor a difference in the number of bone marrow polychromatic erythrocytes was found when ko and wt mice were exposed to methylating or chloroethylating agents. These agents also showed similar growth-inhibitory effects in primary embryonic fibroblasts isolated from ko and wt mice. However, treatment with methyl methanesulfonate resulted in three- to fourfold more hprt mutations in splenic T lymphocytes from APNG ko mice than in those from wt mice. These mutations were predominantly single-base-pair changes; in the ko mice, they consisted primarily of AT-->TA and GC-->TA transversions, which most likely are caused by 3-meA and 3- or 7-meG, respectively. These results clearly show an important role for APNG in attenuating the mutagenic effects of N-alkylpurines in vivo.