Evaluating restoration trajectories using DNA metabarcoding of ground-dwelling and airborne invertebrates and associated plant communities

Invertebrates are important for restoration processes as they are key drivers of many landscape‐scale ecosystem functions; including pollination, nutrient cycling and soil formation. However, invertebrates are often overlooked in restoration monitoring because they are highly diverse, poorly described, and time‐consuming to survey, and require increasingly scarce taxonomic expertise to enable identification. DNA metabarcoding is a relatively new tool for rapid survey that is able to address some of these concerns, and provide information about the taxa with which invertebrates are interacting via food webs and habitat. Here, we evaluate how invertebrate communities may be used to determine ecosystem trajectories during restoration. We collected ground‐dwelling and airborne invertebrates across chronosequences of mine‐site restoration in three ecologically disparate locations in Western Australia and identified invertebrate and plant communities using DNA metabarcoding. Ground‐dwelling invertebrates showed the clearest restoration signals, with communities becoming more similar to reference communities over time. These patterns were weaker in airborne invertebrates, which have higher dispersal abilities and therefore less local fidelity to environmental conditions. Although we detected directional changes in community composition indicative of invertebrate recovery, patterns observed were inconsistent between study locations. The inclusion of plant assays allowed identification of plant species, as well as potential food sources and habitat. We demonstrate that DNA metabarcoding of invertebrate communities can be used to evaluate restoration trajectories. Testing and incorporating new monitoring techniques such as DNA metabarcoding is critical to improving restoration outcomes.

The Identification of Potential Therapeutic Targets for Cutaneous Squamous Cell Carcinoma

We performed a small interfering RNA screen to identify targets for cutaneous squamous cell carcinoma (cSCC) therapy in the ubiquitin/ubiquitin-like system. We provide evidence for selective anti-cSCC activity of knockdown of the E3 ubiquitin ligase MARCH4, the ATPase p97/VCP, the deubiquitinating enzyme USP8, the cullin-RING ligase (CRL) 4 substrate receptor CDT2/DTL, and components of the anaphase-promoting complex/cyclosome (APC/C). Specifically attenuating CRL4^CDT2 by CDT2 knockdown can be more potent in killing cSCC cells than targeting CRLs or CRL4s in general by RBX1 or DDB1 depletion. Suppression of the APC/C or forced APC/C activation by targeting its repressor EMI1 are both potential therapeutic approaches. We observed that cSCC cells can be selectively killed by small-molecule inhibitors of USP8 (DUBs-IN-3/compound 22c) and the NEDD8 E1 activating enzyme/CRLs (MLN4924/pevonedistat). A substantial proportion of cSCC cell lines are very highly MLN4924-sensitive. Pathways that respond to defects in proteostasis are involved in the anti-cSCC activity of p97 suppression. Targeting USP8 can reduce the expression of growth factor receptors that participate in cSCC development. EMI1 and CDT2 depletion can selectively cause DNA re-replication and DNA damage in cSCC cells.

Contralateral prophylactic mastectomy in young women with breast cancer: a population-based analysis of predictive factors and clinical impact

Background and Objectives

Contralateral prophylactic mastectomy (cpm) has been increasingly common among women with unilateral invasive breast cancer (ibca) even though the data that support it are limited. Using a population-based cohort, the objectives of the present study were to describe factors predictive of cpm in young women (≤35 years) with ibca and to evaluate the impact of the procedure on mortality.

Methods

All women diagnosed during 1994-2003 and treated with cpm were identified from the Ontario Cancer Registry. Logistic regression was used to identify patient and tumour factors associated with the use of cpm. Multivariate analyses were used to assess the effect of cpm on recurrence and mortality.

Results

Of 614 women identified, 81 underwent cpm (13.2%). On multivariable analysis, factors associated with cpm included negative lymph node status, negative estrogen receptor status, and initial breast-conserving surgery with re-excision. At follow-up, breast cancer-specific mortality was similar for women who did and did not undergo cpm.

Conclusions

Use of cpm in young women with ibca (compared with non-use) was not associated improved breast cancer-specific mortality. Factors found to be predictive of cpm were negative lymph node status, negative estrogen receptor status, and initial breast-conserving surgery followed by re-excision.

Preclinical comparison of proteasome and ubiquitin E1 enzyme inhibitors in cutaneous squamous cell carcinoma: the identification of mechanisms of differential sensitivity

Proteasome inhibitors have distinct properties and the biochemical consequences of suppressing ubiquitin E1 enzymes and the proteasome differ. We compared the effects of the proteasome inhibitors bortezomib, ixazomib and carfilzomib and the ubiquitin E1 enzyme inhibitor MLN7243/TAK-243 on cell viability and cell death in normal keratinocytes and cutaneous squamous cell carcinoma (cSCC) cell lines. The effects of both a pulse of treatment and more extended incubation were investigated. This is relevant to directly-delivered therapy (topical treatment/intratumoral injection) where the time of exposure can be controlled and a short exposure may better reflect systemically-delivered inhibitor pharmacokinetics. These agents can selectively kill cSCC cells but there are variations in the pattern of cSCC cell line sensitivity/resistance. Variations in the responses to proteasome inhibitors are associated with differences in the specificity of the inhibitors for the three proteolytic activities of the proteasome. There is greater selectivity for killing cSCC cells compared to normal keratinocytes with a pulse of proteasome inhibitor treatment than with a more extended exposure. We provide evidence that c-MYC-dependent NOXA upregulation confers susceptibility to a short incubation with proteasome inhibitors by priming cSCC cells for rapid BAK-dependent death. We observed that bortezomib-resistant cSCC cells can be sensitive to MLN7243-induced death. Low expression of the ubiquitin E1 UBA1/UBE1 participates in conferring susceptibility to MLN7243 by increasing sensitivity to MLN7243-mediated attenuation of ubiquitination. This study supports further investigation of the potential of proteasome and ubiquitin E1 inhibition for cSCC therapy. Direct delivery of inhibitors could facilitate adequate exposure of skin cancers.

The Effect of a Surgery-Specific Cardiac Output–Guided Haemodynamic Algorithm on Outcomes in Patients Undergoing Pancreaticoduodenectomy in a High-Volume Centre: A Retrospective Comparative Study

In this retrospective observational study performed in a high-volume hepatobiliary–pancreatic unit, we evaluated the effect of a surgery-specific goal-directed therapy (GDT) physiologic algorithm on complications and length of hospital stay. We compared patients who underwent pancreaticoduodenectomy with either a standardised Enhanced Recovery After Surgery program (usual care group), or a standardised Enhanced Recovery After Surgery program in combination with a surgery-specific cardiac output–guided algorithm (GDT group). We included 145 consecutive patients: 47 in the GDT group and 98 in the usual care group. Multivariable associations between GDT and lengths of stay and complications were investigated using negative binomial regression. Postoperative complications were common and occurred at similar frequencies amongst the GDT and usual care groups: 64% versus 68% respectively, P=0.71; odds ratio 0.82; (95% confidence interval 0.39–1.70). There were fewer cardiorespiratory complications in the GDT group. Median (interquartile range) length of hospital stay was ten days (8.0–14.0) in the GDT group compared to 13 days (8.8–21.3) in the usual care group, P=0.01. Median (interquartile range) total intraoperative fluid was 3,000 ml (2,050–4,175) in the GDT group compared to 4,500 ml (3,275–5,325) in the usual care group, P <0.0001; but by day one, the median (interquartile range) fluid balance was similar (1,198 ml [700–1,729] in the GDT group versus 977 ml [419–2,044] in the usual care group, P=0.96). Use of vasoactive medications was higher in the GDT group. In our patients undergoing pancreaticoduodenectomy, GDT was associated with restrictive intraoperative fluid intervention, fewer cardiorespiratory complications and a shorter hospital length of stay compared to usual care. However, we could not exclude an influence of surgical caseload, which we have previously found to be an important variable. We also could not relate the increased hospital length of stay to cardiorespiratory complications in individual patients. Therefore, these observational retrospective findings would require confirmation in a prospective randomised study.

TP53 drives invasion through expression of its Δ133p53β variant

TP53 is conventionally thought to prevent cancer formation and progression to metastasis, while mutant TP53 has transforming activities. However, in the clinic, TP53 mutation status does not accurately predict cancer progression. Here we report, based on clinical analysis corroborated with experimental data, that the p53 isoform Δ133p53β promotes cancer cell invasion, regardless of TP53 mutation status. Δ133p53β increases risk of cancer recurrence and death in breast cancer patients. Furthermore Δ133p53β is critical to define invasiveness in a panel of breast and colon cell lines, expressing WT or mutant TP53. Endogenous mutant Δ133p53β depletion prevents invasiveness without affecting mutant full-length p53 protein expression. Mechanistically WT and mutant Δ133p53β induces EMT. Our findings provide explanations to 2 long-lasting and important clinical conundrums: how WT TP53 can promote cancer cell invasion and reciprocally why mutant TP53 gene does not systematically induce cancer progression.

DOI:http://dx.doi.org/10.7554/eLife.14734.001

Most cancers are caused by a build-up of mutations that are acquired throughout life. One gene in particular, called TP53, is the most commonly mutated gene in many types of human cancers. This suggests that TP53 mutations play an important role in cancer development.

It is widely considered that the TP53 gene normally stops tumors from forming, while mutant forms of the gene somehow promote cancer growth. Evidence from patients with cancer has shown, however, that the relationship between TP53 mutations and cancer is not that simple. Some very aggressive cancers that resist treatment and spread have a normal TP53 gene. Some cancers with a mutated gene do not spread and respond well to cancer treatments. Recent studies have shown that the normal TP53 gene produces many different versions of its protein, and that some of these naturally occurring forms are found more often in tumors that others. However, it was not clear if certain versions of TP53’s proteins contributed to the development of cancer.

Now, Gadea, Arsic, Fernandes et al. show that Δ133p53β, one version of the protein produced by the TP53 gene in human cells, helps tumor cells to spread to other organs. Tests of 273 tumors taken from patients with breast cancer revealed that tumors with the Δ133p53β protein were more likely to spread. Patients with these Δ133p53β-containing tumors were also more likely to develop secondary tumors at other sites in the body and to die within five years.

Next, a series of experiments showed that removing Δ133p53β from breast cancer cells grown in the laboratory made them less likely to invade, while adding it back had the opposite effect. The same thing happened in colon cancer cells grown in the laboratory. The experiments showed that Δ133p53β causes tumor cells with the normal TP53 gene or a mutated TP53 gene to spread to other organs.

Together the new findings help explain why some aggressive cancers develop even with a normal version of the tumor-suppressing TP53 gene. They also help explain why not all cancers with a mutant version of the TP53 gene go on to spread. Future studies will be needed to determine whether drugs that prevent the production of the Δ133p53β protein can help to treat aggressive cancers.

DOI:http://dx.doi.org/10.7554/eLife.14734.002

Modulation of p53β and p53γ expression by regulating the alternative splicing of TP53 gene modifies cellular response

In addition to the tumor suppressor p53 protein, also termed p53α, the TP53 gene produces p53β and p53γ through alternative splicing of exons 9β and 9γ located within TP53 intron 9. Here we report that both TG003, a specific inhibitor of Cdc2-like kinases (Clk) that regulates the alternative splicing pre-mRNA pathway, and knockdown of SFRS1 increase expression of endogenous p53β and p53γ at mRNA and protein levels. Development of a TP53 intron 9 minigene shows that TG003 treatment and knockdown of SFRS1 promote inclusion of TP53 exons 9β/9γ. In a series of 85 primary breast tumors, a significant association was observed between expression of SFRS1 and α variant, supporting our experimental data. Using siRNA specifically targeting exons 9β/9γ, we demonstrate that cell growth can be driven by modulating p53β and p53γ expression in an opposite manner, depending on the cellular context. In MCF7 cells, p53β and p53γ promote apoptosis, thus inhibiting cell growth. By transient transfection, we show that p53β enhanced p53α transcriptional activity on the p21 and Bax promoters, while p53γ increased p53α transcriptional activity on the Bax promoter only. Moreover, p53β and p53γ co-immunoprecipitate with p53α only in the presence of p53-responsive promoter. Interestingly, although p53β and p53γ promote apoptosis in MCF7 cells, p53β and p53γ maintain cell growth in response to TG003 in a p53α-dependent manner. The dual activities of p53β and p53γ isoforms observed in non-treated and TG003-treated cells may result from the impact of TG003 on both expression and activities of p53 isoforms. Overall, our data suggest that p53β and p53γ regulate cellular response to modulation of alternative splicing pre-mRNA pathway by a small drug inhibitor. The development of novel drugs targeting alternative splicing process could be used as a novel therapeutic approach in human cancers.

Extending the longevity of a complicated arteriovenous fistula using endovascular intervention

A brachiocephalic arteriovenous fistula was complicated by a central venous stenosis, which could not be relieved. A cephalojugular bypass was performed using an interpositoned graft, which later developed tight stenoses at both ends of the graft. This was successfully treated with endovascular intervention, extending the longevity of the vascular access.

Detecting p53 isoforms at protein level

The human p53 protein isoforms are expressed in several cell lines and modulate p53 tumor suppressor -activity, mainly through modulation of gene expression (1-4). Thus, identifying the pattern of p53 isoforms expression in cell lines is a key step for future studies of the p53 network (5). At the moment, the detection of p53 protein isoforms is based on the use of a panel of antibodies allowing their identification by comparing their molecular weights and their detection pattern by different antibodies (6). Here, classical protocols supplemented with technical know-how are described to detect p53 protein isoforms at protein level by Western blotting and immunoprecipitation. Furthermore, a simple method to study the impact of p53 protein isoforms on p53 transcriptional activity through luciferase reporter gene assays is provided.

The p53 isoforms are differentially modified by Mdm2

The discovery that the single p53 gene encodes several different p53 protein isoforms has initiated a flurry of research into the function and regulation of these novel p53 proteins. Full-length p53 protein level is primarily regulated by the E3-ligase Mdm2, which promotes p53 ubiquitination and degradation. Here, we report that all of the novel p53 isoforms are ubiquitinated and degraded to varying degrees in an Mdm2-dependent and -independent manner, and that high-risk human papillomavirus can degrade some but not all of the novel isoforms, demonstrating that full-length p53 and the p53 isoforms are differentially regulated. In addition, we provide the first evidence that Mdm2 promotes the NEDDylation of p53β. Altogether, our data indicates that Mdm2 can distinguish between the p53 isoforms and modify them differently.

Is it possible to get adequate dose coverage of a clinical target volume (CTV) to account for the possible extra capsular extension in early-stage prostate cancer by low dose rate (LDR) brachytherapy?

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Background: There is no consensus for the definition and evaluation of CTV in post-implant setting for LDR prostate brachytherapy to account for extra capsular extension in clinically localized prostate cancer. In this study, we defined a CTV and evaluated its dosimetry in the post implant CT/MR scans done at 1 month after the LDR brachytherapy procedure.

Methods: The initial consecutive 71 patients who underwent LDR brachytherapy under a single physician at Princess Margaret Hospital from June 2009 to July 2010 were included in this retrospective study. On the post implant MRI, the CTV was created by adding 3mm uniform margins around the prostate but respecting the anatomical boundaries like bone, bladder and rectum. Post implant dosimetry was based on CT/MR fusion using the dosimetric parameters V80, V90, V100, V150, V200, D80, D90 and D100. Implants were qualified as optimal if their V100 was >85% and D90 was >90% for both prostate and CTV. Univariate analysis was performed to evaluate associations of factors with V100 and D90 for the CTV using Wilcoxon rank sum test and Fisher's exact test.

Results: The mean (SD) prostate V100 and D90 were 95.5% (4.2) and 117% (10) respectively with only 1 patient having sub optimal implant (V100 <85% and D90 <90%). The mean (SD) V100 and D90 for the CTV were also acceptable at 90.6% (4.9) and 103% (9), respectively. Six patients had V100 <85% and 7 patients had D90 <90% for the CTV. On univariate analysis, edema and seed implantation technique correlated with sub-optimal implant for the CTV. The mean (SD) edema for patients with V100 <85% was 18% (10) and with D90 <90% was 15% (12). The corresponding values for the optimal implants both in terms of V100 and D90 were 3% (13). Patients implanted with exclusively loose seeds (15 patients only) had higher incidence of sub-optimal implants (26%) compared to patients who had strands on the antero-lateral margins (56 patients; 3.5%).

Conclusions: In this study, adequate dose coverage of CTV was achieved in most patients with current technique but implants with optimal dosimetry to prostate still may have sub-optimal D90 and V100 for the CTV.

No significant financial relationships to disclose.

Dose to regions within the prostate during the learning curve phase in low dose rate (LDR) brachytherapy: Sector analysis of 71 consecutive patients at Princess Margaret Hospital

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Background: It is important to evaluate the dose distribution within the prostate in highly conformal and operator dependent treatment like brachytherapy, especially in the learning curve phase when technical skill is evolving. We report detailed dosimetric analysis of prostate sectors in the initial 71 consecutive implants performed by a physician in the first year of practice.

Methods: Implants were done based on a pre plan but intra-operative adjustments were made to account for actual seed positions and addition of seeds and the final dose distribution to the prostate was documented as Intra-operative (IO) plan. Post-implant assessment was at 1 month using fused MRI/CT scans. Twelve prostate sectors were generated by division into 4 quadrants (anterior, posterior, laterals) and 3 segments (base, middle and apex). IO and post-implant (PI) V100 and D90 for sectors and whole prostate were recorded. Comparative (Wilcoxon Rank Sum) and association (Spearman's rank correlation) testing was performed for univariate analysis. Optimal dosimetry values for the entire prostate and sectors were defined as D90 >90% and V100 >85%.

Results: Seventy implants were optimal (out of 71) with mean prostate PI V100 and D90 of 95.5% and 117.1%. Only 1 sector had suboptimal mean PI V100 and D90 (70.3% and 85.9%), significantly lower than IO (p<0.001), contributing to lower PI V100 for the base (88%) and anterior sectors (86.9%). The mean IO D90 of apical sectors (126%) was lower than base and mid gland (131% and 132% respectively) and lateral sectors was (134%) higher than anterior and posterior sectors (123% and 126%) consistent with a modified peripheral loading approach. D90 decreased from IO to PI plan in anterior (123% vs 106%, p<0.001) and base sectors (132% vs 108%, p<0.001) while increase was noted in apical (126% vs 133%, p<0.001) and posterior sectors (126% vs 131%, p=0.006).

Conclusions: Results are encouraging with optimal dosimetry in 11/12 sectors in most patients, and sector analysis provided insight into planning factors and provided useful data for refinement in practice. Further study correlating sector analysis with clinical outcomes is required.

No significant financial relationships to disclose.

p53 mutant breast cancer patients expressing p53γ have as good a prognosis as wild-type p53 breast cancer patients

INTRODUCTION

Normal function of the p53 network is lost in most cancers, often through p53 mutation. The clinical impact of p53 mutations in breast cancer remains uncertain, especially where p53 isoforms may modify the effects of these p53 mutations.

METHODS

Expression of p53β and p53γ isoforms, the isoforms identified in normal breast tissue, was detected by reverse transcription polymerase chain reaction from a cohort of 127 primary breast tumours. Expression of p53β and p53γ isoforms was analysed in relation to clinical markers and clinical outcomes (5 years) by binary logistic regression, Cox proportional hazards regression and Kaplan-Meier survival analyses.

RESULTS

p53β and p53γ were not randomly expressed in breast cancer. p53β was associated with tumour oestrogen receptor (ER) expression, and p53γ was associated with mutation of the p53 gene. The patient group with the mutant p53 breast tumour-expressing p53γ isoform had low cancer recurrence and an overall survival as good as that of patients with wild-type p53 breast cancer. Conversely, patients expressing only mutant p53, without p53γ isoform expression, had a particularly poor prognosis.

CONCLUSIONS

The determination of p53γ expression may allow the identification, independently of the ER status, of two subpopulations of mutant p53 breast cancer patients, one expressing p53γ with a prognosis as good as the wild-type p53 breast cancer patients and a second one not expressing p53γ with a particularly poor prognosis. The p53γ isoform may provide an explanation of the hitherto inconsistent relationship between p53 mutation, treatment response and outcome in breast cancer.

Δ160p53 is a novel N-terminal p53 isoform encoded by Δ133p53 transcript

p53 gene expresses several protein isoforms modulating p53-mediated responses through regulation of gene expression. Here, we identify a novel p53 isoform, Δ160p53, lacking the first 159 residues. By knockdown experiments and site-directed mutagenesis, we show that Δ160p53 is encoded by Δ133p53 transcript using ATG160 as translational initiation site. This hypothesis is supported by endogenous expression of Δ160p53 in U2OS, T47D and K562 cells, the latter ones carrying a premature stop codon that impairs p53 and Δ133p53 protein expression but not the one of Δ160p53. Overall, these results show that the Δ133p53 transcript generates two different p53 isoforms, Δ133p53 and Δ160p53.

Δ160p53 is a novel N-terminal p53 isoform encoded by Δ133p53 transcript

p53 gene expresses several protein isoforms modulating p53-mediated responses through regulation of gene expression. Here, we identify a novel p53 isoform, Δ160p53, lacking the first 159 residues. By knockdown experiments and site-directed mutagenesis, we show that Δ160p53 is encoded by Δ133p53 transcript using ATG160 as translational initiation site. This hypothesis is supported by endogenous expression of Δ160p53 in U2OS, T47D and K562 cells, the latter ones carrying a premature stop codon that impairs p53 and Δ133p53 protein expression but not the one of Δ160p53. Overall, these results show that the Δ133p53 transcript generates two different p53 isoforms, Δ133p53 and Δ160p53.

Tumor susceptibility and apoptosis defect in a mouse strain expressing a human p53 transgene

Activation of apoptosis is believed to be critical for the role of p53 as a tumor suppressor. Here, we report a new mouse strain carrying a human p53 transgene in the mouse p53-null background. Expression of human p53 in these mice was comparable with wild-type murine p53; however, transactivation, induction of apoptosis, and G(1)-S checkpoint, but not transrepression or regulation of a centrosomal checkpoint, were deregulated. Although multiple functions of p53 were abrogated, mice carrying the human p53 transgene did not show early onset of tumors as typically seen for p53-null mice. In contrast, human p53 in the p53-null background did not prevent accelerated tumor development after genotoxic or oncogenic stress. Such behavior of human p53 expressed at physiologic levels in transgenic cells could be explained by unexpectedly high binding with Mdm2. By using Nutlin-3a, an inhibitor of the interaction between Mdm2 and p53, we were able to partially reconstitute p53 transactivation and apoptosis in transgenic cells. Our findings indicate that the interaction between p53 and Mdm2 controls p53 transcriptional activity in homeostatic tissues and regulates DNA damage- and oncogene-induced, but not spontaneous, tumorigenesis.

p53 isoforms can regulate p53 transcriptional activity

The recently discovered p53-related genes, p73 and p63, express multiple splice variants and N-terminally truncated forms initiated from an alternative promoter in intron 3. To date, no alternative promoter and multiple splice variants have been described for the p53 gene. In this study, we show that p53 has a gene structure similar to the p73 and p63 genes. The human p53 gene contains an alternative promoter and transcribes multiple splice variants. We show that p53 variants are expressed in normal human tissue in a tissue-dependent manner. We determine that the alternative promoter is conserved through evolution from Drosophila to man, suggesting that the p53 family gene structure plays an essential role in the multiple activities of the p53 family members. Consistent with this hypothesis, p53 variants are differentially expressed in human breast tumors compared with normal breast tissue. We establish that p53beta can bind differentially to promoters and can enhance p53 target gene expression in a promoter-dependent manner, while Delta133p53 is dominant-negative toward full-length p53, inhibiting p53-mediated apoptosis. The differential expression of the p53 isoforms in human tumors may explain the difficulties in linking p53 status to the biological properties and drug sensitivity of human cancer.

Conservation of IGF2-H19 and IGF2R imprinting in sheep: effects of somatic cell nuclear transfer

In different mammalian species, in vitro culture and manipulation can lead to aberrant fetal and peri-natal development. It has been postulated that these diverse abnormalities are caused by epigenetic alterations and that these could affect genes that are regulated by genomic imprinting. To explore this hypothesis relative to somatic cell nuclear transfer in sheep, we investigated whether the ovine H19-IGF2 and IGF2R loci are imprinted and analysed their DNA methylation status in cloned lambs. A comparison between parthenogenetic and control concepti established that imprinting at these two growth-related loci is evolutionarily conserved in sheep. As in humans and mice, IGF2R and H19 comprise differentially methylated regions (DMRs) that are methylated on one of the two parental alleles predominantly. In tongue tissue from 12 out of 13 cloned lambs analysed, the DMR in the second intron of IGF2R had strongly reduced levels of DNA methylation. The DMR located upstream of the ovine H19 gene was found to be similarly organised as in humans and mice, with multiple CTCF binding sites. At this DMR, however, aberrant methylation was observed in only one of the cloned lambs. Although the underlying mechanisms remain to be determined, our data indicate that somatic cell nuclear transfer procedures can lead to epigenetic deregulation at imprinted loci.

In vivo metabolism and clearance of substance P and co-expressed tachykinins in rat striatum

Neurons expressing the preprotachykinin A gene, which encodes the sequences of substance P, neurokinin A, neuropeptide gamma and neuropeptide K, exemplify peptide co-existence. Furthermore, there is also evidence that substance P fragments have biological activity. However, the relative contribution of each of these peptides to tachykinin signalling is still poorly understood. An important factor which will determine the characteristics of the signal mediated by co-localised peptides is their clearance from the extracellular space. The striatum, in which tachykinins are present and exert neuromodulatory roles, can be used as a model to investigate this aspect. Therefore, in this study we characterised in vivo in the striatum the metabolism and clearance of substance P and of the other three co-expressed peptides. After intrastriatal administration of 1 pmol, tritiated substance P disappeared too rapidly for metabolites to be detected. However, when 10 nmol substance P and 1 pmol tritiated substance P were co-injected, substance P(1-4) and substance P(1-7), which are biologically active, were detected as major metabolites. Under these conditions, the rate of decay of tritiated substance P was 0.2 nmol/min. The effects of the peptidase inhibitors thiorphan, bestatin and captopril suggested that neutral endopeptidase 24.11 and aminopeptidases were involved in primary substance P cleavages, whereas angiotensin-converting enzyme was involved in secondary cleavages. The monitoring of the decay of unlabelled substance P by high-performance liquid chromatography gave a rate of 0.16 nmol/min. Using high-performance liquid chromatography with capillary electrophoresis, the rates of decay of 10 nmol neurokinin A or neuropeptide gamma were five and seven times faster than that of substance P. In contrast, over the time course of the experiment, no significant decay of neuropeptide K was detected. These results show that substance P disappears rapidly from the extracellular space, and supports the formation in vivo of major N-terminal active substance P metabolites. Our study also highlights significant differences in the clearance of co-expressed tachykinins and suggests that certain species may disappear relatively slowly from the extracellular space, and thus may make a significant temporal and spatial contribution to signalling.

Epigenetic change in IGF2R is associated with fetal overgrowth after sheep embryo culture

Manipulation or non-physiological embryo culture environments can lead to defective fetal programming in livestock. Our demonstration of reduced fetal methylation and expression of ovine IGF2R suggests pre-implantation embryo procedures may be vulnerable to epigenetic alterations in imprinted genes. This highlights the potential benefits of epigenetic diagnostic screening in developing embryo procedures.

T(84) epithelial cells respond to 5-hydroxytryptamine when grown in serum-free media

The aim of this study was to establish the cause of insensitivity of T(84) human colonic epithelial cells to 5-hydroxytryptamine (5-HT). Monolayers of T(84) cells were placed in modified Ussing chambers for measurement of short-circuit current, an index of secretion. When grown in serum-supplemented media, T(84) cells gave secretory responses to acetylcholine and forskolin but not to 5-HT. When grown in AIM V serum-free media, T(84) cells responded to 5-HT. Chromatographic analysis with fluorimetric detection showed high levels of 5-HT (1.8 microM) in the serum. This contamination is probably responsible for subsequent desensitization of T(84) cells to 5-HT.

Axonal transport of activating transcription factor-2 is modulated by nerve growth factor in nociceptive neurons

The aim of this study was to determine whether axonal transport of activating transcription factor-2 (ATF2) occurs in adult sensory neurons, and whether this process is under neurotrophin control. Antisera to both total ATF2 and to the activated (i.e., phosphorylated) form were used for immunocytochemistry and Western blotting. ATF2 was localized to predominantly nociceptive dorsal root ganglion cells in adult rats and shown to accumulate proximal and distal to a sciatic nerve ligature as a result of axonal transport. Subcutaneous injection of nerve growth factor (NGF) decreased the levels of fast retrograde axonal transport of activated ATF2 by 97% (p < 0.05) and elevated levels of retrograde axonal transport of total ATF2 by twofold (p < 0.02). In contrast, blocking endogenous NGF using an anti-NGF antibody induced an elevation in retrograde axonal transport of activated ATF2 of 4. 5-fold (p < 0.05) and decreased retrograde axonal transport of total ATF2 by 72% (p < 0.05). NGF or anti-NGF treatment had no effect on the anterograde transport levels of total or activated ATF2. This study shows that signaling by target-derived NGF to the cell bodies of sensory neurons consists, in part, of the modulation of levels and activation status of a retrogradely transported transcription factor, ATF2.

NMDA receptor activation modulates evoked release of substance P from rat spinal cord

The possible modulation exerted by glutamate on substance P (SP) release from the rat spinal cord has been investigated. The N-methyl-D-aspartate (NMDA) receptor agonist, NMDA (1 microM), increased SP basal outflow by 46.5+/-10.9% (n = 3, P<0.01) without changing the evoked release of the peptide. Conversely, NMDA antagonists but not 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) inhibited both electrically-evoked and capsaicin-induced release of SP. In particular, D-2-amino-5-phosphonopentanoate (D-AP5; 50 microM) inhibited electrically-evoked and capsaicin-induced release of SP by 93+/-2.4% and 93.2+/-3.8% (n = 12, P<0.01), respectively. Functional pharmacological evidence is provided for glutamate exerting a positive feedback on SP release evoked by C fibre stimulation via NMDA receptor activation.

Stimulation of nerve growth-factor and substance P expression in the iris-trigeminal axis of diabetic rats--involvement of oxidative stress and effects of aldose reductase inhibition

In rats with streptozotocin-induced diabetes, we measured increased (by 61%; P < 0.05) mRNA for nerve growth factor (NGF) in the iris together with increased (by 82%; P < 0.05) mRNA for preprotachykinin (the substance P precursor) in the trigeminal ganglion, suggesting that increased NGF was driving increased substance P gene expression. In other diabetic rats, these changes were prevented by treatment with either an antioxidant (butylated hydroxytoluene; 1% by diet) or an aldose reductase inhibitor (ARI) (sorbinil; 25 mg/kg/day p.o.) and the sorbinil treatment was associated with significant inhibition of polyol pathway intermediates in both lens and sciatic nerve. This suggests that polyol pathway activity in the lens may translate to oxidative stress-driving stimulation of NGF gene expression in the iris. The change is selective for NFG, because expression of the analogous neurotrophin, neurotrophin-3 (NT-3), was unaltered in the same irises. These changes suggest that oxidative stress and/or inflammation can drive up NGF expression in diabetes--a mechanism that might participate in iritis.

Developmental expression and 5' end cDNA cloning of the porcine 2x and 2b myosin heavy chain genes

Muscle research on farm animals suffers from a lack of basic molecular probes and immunochemical reagents. To complete the cloning of a comprehensive range of isoform-specific postnatal myosin heavy chain (MyHC) probes from the pig, we report here on the 5 '-end cDNA isolation, identification, and in vivo characterization of the porcine equivalent of the 2x (fast oxidative-glycolytic) and 2b (fast glycolytic) MyHC isoforms. Comparative analyses of primary nucleotide and deduced amino acid sequences of the porcine slow, 2a, 2x, and 2b cDNAs showed that the 2x and 2b isoforms were most homologous with each other and the slow isoform was the least similar. At or just after birth, at least 3 postnatal muscle fiber types (slow/beta, 2a, and 2x) were present. MyHC 2x expressing fibers were arranged distinctively as large outer rings, each surrounding an inner ring of 2a fibers, which in turn circumscribed one or more central slow fibers. Subsequently, different muscles expressed at different times the MyHC 2b isoform such that by 10 weeks, 2b fibers became the most dominant fiber type, in size and number in nearly all muscles examined except for its notable absence in the soleus muscle. Co-expression of two or more MyHC isoforms within the same fiber was not a feature of porcine muscles unlike that observed in rat and human muscles. For the first time, porcine muscle fibers can now be classified into 4 adult phenotypes (slow/beta 2a, 2x, and 2b) according to the expression of specific MyHC isoforms.

Cloning and in vivo expression of the pig MyoD gene

The complete sequence of the pig MyoD gene has been determined through the isolation and characterization of a 17 kb genomic clone. The deduced amino acid sequence shows relative conservation of about 90% with the MyoD sequences determined in other mammalian species, though there are several non-conservative changes scattered throughout the C-terminus. In situ hybridization on pig embryos (20-30 days post coitum) showed that MyoD expression was confined to myotomes and skeletal muscle masses.

Molecular characterization of a developmentally regulated porcine skeletal myosin heavy chain gene and its 5′ regulatory region

Members of the myosin heavy chain (MyHC) gene family show developmental stage- and spatial-specificity of expression. We report on the characterization and identification of a porcine skeletal fast MyHC gene, including its corresponding 5′ end cDNA and 5′ regulatory region. This MyHC isoform was found exclusively in skeletal muscles from about the last quarter of gestation through to adulthood. Expression of this isoform was higher postnatally and its spatial distribution resembled a rosette cluster; each with a ring of fast fibres surrounding a central slow fibre. This rosette pattern was absent in the adult diaphragm but about 20% of the fibres continued to express this MyHC isoform. Further in vivo expression studies, in a variety of morphologically and functionally diverse muscles, showed that this particular skeletal MyHC isoform was expressed in fast oxidative-glycolytic fibres, suggesting that it was the equivalent of the fast IIA isoform. Two domains in the upstream regulatory region were found to confer differentiation-specific expression on C2 myotubes (−1007 to -828 and -455 to -101), based on in vitro transient expression assays using the chloramphenicol acetyltransferase (CAT) reporter gene. Interestingly, for high levels of CAT expression to occur, a 3′ region, extending from the transcriptional start site to part. of intron 2, must be present in all the DNA constructs used.

Age-related changes in collagen gene expression in the muscles of mdx dystrophic and normal mice

It has been shown that there is a marked accumulation of collagen (notably type III) in the muscles of Duchenne muscular dystrophy patients. Although not as marked, there is also an accumulation of collagen in normal skeletal muscle with age. To attempt to determine whether dystrophy-related and/or age-related collagen accumulation are the result of increased collagen gene expression, sections from muscles of mdx and control mice at different ages were subjected to in situ hybridization with cRNA probes for procollagen I and III to estimate changes in specific mRNA levels. Greater amounts of collagen I and III mRNA were noted in skeletal muscles and the diaphragm of the mdx mice than in the same muscles of age matched controls. The over-expression of these collagen genes was particularly noticeable in the mdx diaphragm and may possibly be explained by the greater activity of this muscle as compared to the limb muscles of these dystrophic mice. There was, however, an age-related decline of collagen expression in both normal and dystrophic muscle and this strongly suggests that the increased fibrosis of skeletal muscle with age is not the result of increased collagen gene expression but is most likely due to an impairment of degradation. In contrast, the excess accumulation of collagen in dystrophic muscle compared to normal muscle is related to increased gene expression, probably triggered by an injured tissue response induced by muscle fibre damage due to the lack of dystrophin.

In vivo expression and molecular characterization of the porcine slow-myosin heavy chain

We report on the molecular characterization of the porcine slow-myosin heavy chain (HC) beta gene and the isolation of its 5′ end cDNA. In vivo expression study, by in situ hybridization and histochemistry, revealed a highly regular rosette pattern of fiber arrangement, with a slow fiber occupying the central core, in all the skeletal muscles examined. This feature can be advantageous in the distinction of primary and secondary fibers in myogenic lineage studies. In the neonatal heart, beta isoform expression is diffuse, with higher expression occurring in the ventricle than in the atrium. Transient transfection assays showed the porcine promoter functions in a muscle- and differentiation stage-specific manner. In the 5′ regulatory region are several putative positive and negative regulatory elements, including a positive and a negative element in close proximity to each other in intron 1.

Determination of paracetamol (acetaminophen) in blood and plasma using high performance liquid chromatography with dual electrode coulometric quantification in the redox mode

A simple, but sensitive, micro-assay for paracetamol in blood and plasma is described. Samples were prepared by precipitation with trichloroacetic assay solution and the drug quantified by reversed phase liquid chromatography with dual electrode electrochemical detection in the redox mode (oxidation at +0.25 V followed by reduction at -0.15 V). The limit of detection was 0.1 mg/L for a 10 microL sample of blood or plasma, the coefficient of variation at this concentration being 11.4%. The method was applied to a study of gastric emptying in patients before and after cardiac surgery.

Strong expression of foreign genes following direct injection into fish muscle

We report here for the first time direct injection of genes into fish muscle in vivo. Plasmids used contain either SV40 early promoter, rabbit beta-cardiac myosin heavy chain promoter, human MxA promoter or an artificial promoter, fused to a chloramphenicol acetyltransferase (CAT) or beta-galactosidase reporter gene. CAT assays revealed that most gene constructs were highly expressed. Histochemical analysis showed that beta-galactosidase was strongly expressed at the site of injection within muscle fibres. This method provides an excellent system for testing expression of gene constructs, including those of mammalian origin, in fish muscle in vivo and has the potential for fish vaccination.

The influenza resistance murine Mx1 gene is constitutively expressed in the epithelia of the gastrointestinal, respiratory and uterine tracts

The murine Mx1 gene confers specific resistance against influenza in the inbred A2G mice and in vitro have been shown to be inducible with type I but not type II interferons. Contrary to expectation, we found by in situ hybridisation widespread Mx1 expression along the epithelia of the gastrointestinal, uterine and respiratory tracts in uninduced A2G mice. Several lines of evidence, including further enhancement of Mx1 expression during organ culture and gnotobiotic mice analyses, indicated that this apparent constitutive epithelial Mx1 expression was a locally induced response to stimuli present in the respective lumina. This phenomenon may be a feature found in other interferon-inducible and interferon genes.