MtZR1, a PRAF protein,is involved in the development of roots and symbiotic root nodules in Medicago truncatula

PRAF proteins are present in all plants, but their functions remain unclear. We investigated the role of one member of the PRAF family, MtZR1, on the development of roots and nitrogen‐fixing nodules in Medicago truncatula. We found that MtZR1 was expressed in all M. truncatula organs. Spatiotemporal analysis showed that MtZR1 expression in M. truncatula roots was mostly limited to the root meristem and the vascular bundles of mature nodules. MtZR1 expression in root nodules was down‐regulated in response to various abiotic stresses known to affect nitrogen fixation efficiency. The down‐regulation of MtZR1 expression by RNA interference in transgenic roots decreased root growth and impaired nodule development and function. MtZR1 overexpression resulted in longer roots and significant changes to nodule development. Our data thus indicate that MtZR1 is involved in the development of roots and nodules. To our knowledge, this work provides the first in vivo experimental evidence of a biological role for a typical PRAF protein in plants.     

Impact of portal glucose delivery on glucose metabolism in conscious, unrestrained mice

Previous studies in mice suggest that portal venous infusion of glucose at a low rate paradoxically causes hypoglycemia; this does not occur in dogs, rats, and humans. A possible explanation is that fasting status in the mouse studies may have altered the response. We sought to determine whether the response to portal glucose delivery in the mouse was similar to that seen in other species and whether it was dependent on fasting status. Studies were performed on chronically catheterized conscious mice. Catheters were placed into the portal and jugular veins and carotid artery 5 days before study. After a 5- or 16-h fast, glucose was infused into either the portal (PO) or the jugular vein (JU) for 6 h at 25 microg.g(-1).min(-1). [3-(3)H]glucose was infused into the JU to measure glucose turnover. In 5-h-fasted mice, PO and JU exhibited similar increases in arterial blood glucose from 155 +/- 11 to 173 +/- 19 and 147 +/- 8 to 173 +/- 10 mg/dl, respectively. Endogenous glucose production decreased and arterial insulin increased to the same extent in both PO and JU. A similar response was observed in 16-h-fasted mice; however, the proportion of hepatic glycogen synthesis occurring by the indirect pathway was increased by fasting. In summary, portal glucose delivery in the mouse did not cause hypoglycemia even when the duration of the fast was extended. The explanation of the differing response from previous reports in the mouse is unclear.     

Effect of polyclonal antisera to recombinant tNOX protein on the growth of transformed cells

Previous reports have described a tumor-associated NADH oxidase (tNOX) and its continuous activation in transformed culture cells. Certain anticancer drugs have been shown to inhibit preferentially both the tNOX activity and the growth of transformed culture cells and the cytotoxicity is associated with the induction of apoptosis. To investigate the biological function of tNOX protein, we have raised polyclonal antisera against bacterial expressed tNOX protein and the antisera are able to recognize protein bands in transformed cells but not the non-transformed cells tested. With tNOX antisera treatment, the survival in transformed cell lines is decreased but not the non-transformed cells. In addition, tNOX antisera-induced cytotoxicity is accompanied by the induction of apoptosis. However, slightly higher amount of PARP cleavage and activation of caspase-9 are observed in tNOX antisera treated HCT116 cells. Further experiments have demonstrated the activation of JNK and phosphorylation of p53 by treatment. In addition, tNOX antisera treatment leads to an impressive increase in reactive oxygen species in COS cells but not the control sera. Our data suggest that (a) tNOX antisera treatment may inhibit the growth of transformed cells by inducing apoptosis and (b) the apoptotic mechanism might be through modulating ROS production and JNK pathway.     

Advantages of dynamic “closed loop” stable isotope flux phenotyping over static “open loop” clamps in detecting silent genetic and dietary phenotypes

In vivo insulin sensitivity can be assessed using “open loop” clamp or “closed loop” methods. Open loop clamp methods are static, and fix plasma glucose independently from plasma insulin. Closed loop methods are dynamic, and assess glucose disposal in response to a stable isotope labeled glucose tolerance test. Using PPARα^−/− mice, open and closed loop assessments of insulin sensitivity/glucose disposal were compared. Indirect calorimetry done for the assessment of diurnal substrate utilization/metabolic flexibility showed that chow fed PPARα^−/− mice had increased glucose utilization during the light (starved) cycle. Euglycemic clamps showed no differences in insulin stimulated glucose disposal, whether for chow or high fat diets, but did show differences in basal glucose clearance for chow fed PPARα^−/− versus SV129J-wt mice. In contrast, the dynamic stable isotope labeled glucose tolerance tests reveal enhanced glucose disposal for PPARα^−/− versus SV129J-wt, for chow and high fat diets. Area under the curve for plasma labeled and unlabeled glucose for PPARα^−/− was ≈1.7-fold lower, P < 0.01 during the stable isotope labeled glucose tolerance test for both diets. Area under the curve for plasma insulin was 5-fold less for the chow fed SV129J-wt (P < 0.01) but showed no difference on a high fat diet (0.30 ± 0.1 for SV129J-wt vs. 0.13 ± 0.10 for PPARα^−/−, P = 0.28). This study demonstrates that dynamic stable isotope labeled glucose tolerance test can assess “silent” metabolic phenotypes, not detectable by the static, “open loop”, euglycemic or hyperglycemic clamps. Both open loop and closed loop methods may describe different aspects of metabolic inflexibility and insulin sensitivity.     

Glycosylated Hemoglobin and Albumin-Corrected Fructosamine Are Good Indicators for Glycemic Control in Peritoneal Dialysis Patients

Purpose

Diabetes mellitus (DM) is the most common cause of end-stage renal disease and is an important risk factor for morbidity and mortality after dialysis. However, glycemic control among such patients is difficult to assess. The present study examined glycemic control parameters and observed glucose variation after refilling different kinds of fresh dialysate in peritoneal dialysis (PD) patients.

Methods

A total of 25 DM PD patients were recruited, and continuous glucose monitoring system (CGMS) was applied to measure interstitial fluid (ISF) glucose levels at 5-min intervals for 3 days. Patients filled out diet and PD fluid exchange diaries. The records measured with CGMS were analyzed and correlated with other glycemic control parameters such as fructosamine, albumin-corrected fructosamine (AlbF), glycosylated hemoglobin (HbA1c), and glycated albumin levels.

Results

There were significant correlations between mean ISF glucose and fructosamine (r = 0.45, P<0.05), AlbF (r = 0.54, P<0.01), and HbA1c (r = 0.51, P<0.01). The ISF glucose levels in glucose-containing dialysate increased from approximately 7–8 mg/dL within 1 hour of exchange in contrast to icodextrin dialysate which kept ISF glucose levels unchanged.

Conclusion

HbA1c and AlbF significantly correlated with the mean ISF glucose levels, indicating that they are reliable indices of glycemic control in DM PD patients. Icodextrin dialysate seems to have a favorable glycemic control effect when compared to the other glucose-containing dialysates.     

SIMPLE: implementation of recommendations from international evidence-based guidelines on caesarean sections in the Netherlands. Protocol for a controlled before and after study

Background

Caesarean section (CS) rates are rising worldwide. In the Netherlands, the most significant rise is observed in healthy women with a singleton in vertex position between 37 and 42 weeks gestation, whereas it is doubtful whether an improved outcome for the mother or her child was obtained. It can be hypothesized that evidence-based guidelines on CS are not implemented sufficiently. Therefore, the present study has the following objectives: to develop quality indicators on the decision to perform a CS based on key recommendations from national and international guidelines; to use the quality indicators in order to gain insight into actual adherence of Dutch gynaecologists to guideline recommendations on the performance of a CS; to explore barriers and facilitators that have a direct effect on guideline application regarding CS; and to develop, execute, and evaluate a strategy in order to reduce the CS incidence for a similar neonatal outcome (based on the information gathered in the second and third objectives).

Methods

An independent expert panel of Dutch gynaecologists and midwives will develop a set of quality indicators on the decision to perform a CS. These indicators will be used to measure current care in 20 hospitals with a population of 1,000 women who delivered by CS, and a random selection of 1,000 women who delivered vaginally in the same period. Furthermore, by interviewing healthcare professionals and patients, the barriers and facilitators that may influence the decision to perform a CS will be measured. Based on the results, a tailor-made implementation strategy will be developed and tested in a controlled before-and-after study in 12 hospitals (six intervention, six control hospitals) with regard to effectiveness, experiences, and costs.

Discussion

This study will offer insight into the current CS care and into the hindering and facilitating factors influencing obstetrical policy on CS. Furthermore, it will allow definition of patient categories or situations in which a tailor-made implementation strategy will most likely be meaningful and cost effective, without negatively affecting the outcome for mother and child.

Trial registration

http://www.clinicaltrials.gov: NCT01261676     

The influence of air temperature on the starting dates of the pollen season of alnus and populus

In this work we have studied the influence of air temperature on the starting dates of Alnus and Populus pollination in two different climatic regions in Europe: central Italy and The Netherlands. The start of the Alnus pollen season varied between 27th January and 16th February in the Italian stations while in The Netherlands it showed an average delay of about one month. For Populus the beginning of the pollen season was delayed on an average 15 days at Dutch places compared to central Italy. In the former it varied between 14th March and 21st April while in the latter between 28th February and 24th March. Significant correlations exist between the beginning of pollination for these taxa and temperature conditions in the preceding periods. The highest correlations found were with daily mean decade temperature for three decades before the average starting dates of the pollen season. These correlations were better for The Netherlands than for central Italy perhaps because the temperature in Holland is the more prominent meteorological factor (relative to precipitation) compared with central Italy, where precipitation has much influence in winter. This study indicated correlations between the pollination and temperature also during the dormant period in the preceding season.     

Multimodal signals in male European treefrog (Hyla arborea) and the influence of population isolation on signal expression

In nocturnal treefrogs, mate choice implies the use of acoustic and visual signals. Multimodality is suspected to have evolved for either information redundancy or information complementariness. It is essential to explore multimodality in a natural context to understand the selection pressures operating on the signals. In the present study, we investigated calling and coloration in relation to male biometry and condition in four populations of European treefrog (Hyla arborea) varying in size and genetic isolation. We compared the signal intensity between core and satellite populations to estimate the impact of genetic diversity on male secondary sexual traits. The results obtained show important regional variations in both traits, likely as a result of local adaptations. Call and coloration are weakly correlated within an individual, implying that these traits likely convey different information about the signaller's identity or quality, thus supporting the hypothesis of complementariness of multiple messages. By contrast to the experimental evidence, we find that call and coloration are not related to male condition (as estimated by the residual of mass over size), suggesting that the condition‐dependence of these traits may be mediated by complex mechanisms not accurately reflected by the chosen estimator. Finally, male call and colour phenotypes present no robust pattern of variation with isolation status, probably because of variation in local selective pressures and in history of population dynamics. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 103 , 633–647.     

Relationships between lake ecology and morphological characters in Icelandic Arctic charr,Salvelinus alpinus

The common occurrence of parallel phenotypic patterns suggests that a strong relationship exists between ecological dynamics and micro‐evolution. Comparative studies from a large number of populations under varying sets of ecological drivers could contribute to a better understanding of this relationship. We used data on morphology of arctic charr (Salvelinus alpinus) and ecological factors from 35 Icelandic lakes to test the hypothesis that morphological patterns among monomorphic charr populations from different lakes are related to interlake variation in ecological characteristics. There is extensive phenotypic diversity among populations of Icelandic charr, and populations are easily distinguished based on overall body morphology. The results obtained in the present study showed that the morphological diversity of charr was related to large‐scale diversity in lake ecology. Variation in charr morphology was related to water origin (e.g. spring fed versus run‐off), bedrock age, and fish community structure. The present study shows how various ecological factors can shape the biological diversity that we observe. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 103 , 761–771.