Relative embryo length as an adaptation to habitat and life cycle in Apiaceae

? The factors driving the evolution of the relative embryo length in Apiaceae were examined. We tested the hypothesis that seeds with large relative embryo length, because of more rapid germination, are beneficial in dry and open habitats and for short-lived species. We also analyzed to what extent delayed germination as a result of embryo growth can be considered a dormancy mechanism. ? Hypotheses were tested by correlating the relative embryo length with other plant traits, habitat and climatic variables. The adaptive nature of the relative embryo length was determined by comparing the performance of a pure drift, Brownian motion (BM) model of trait evolution with that of a selection-inertia, Ornstein-Uhlenbeck (OU) model. ? A positive correlation of the relative embryo length with germination speed and negative correlations with the amount of habitat shade, longevity and precipitation were found. An OU model, in which the evolution of longer embryos corresponded to a transition to habitats of high light, or to a short life cycle, outperformed significantly a BM model. ? The results indicated that the relative embryo length may have evolved as an adaptation to habitat and life cycle, whereas dormancy was mainly related to temperature at the sampling sites.     

CRF-induced calcium signaling in guinea pig small intestine myenteric neurons involves CRF-1 receptors and activation of voltage-sensitive calcium channels

Corticotropin-releasing factor (CRF) is a 41-amino acid peptide with distinct effects on gastrointestinal motility involving both CRF-1 and CRF-2 receptor-mediated mechanisms that are generally claimed to be centrally mediated. Evidence for a direct peripheral effect is rather limited. Electrophysiological studies showed a cAMP-dependent prolonged depolarization of guinea pig myenteric neurons on application of CRF. The current study aimed to test the direct effect of CRF on myenteric neurons and to identify the receptor subtype and the possible mechanisms involved. Longitudinal muscle myenteric plexus preparations and myenteric neuron cultures of guinea pig small intestine were incubated with the calcium indicator Fluo-4. Confocal Ca(2+) imaging was used to visualize activation of neurons on application of CRF. All in situ experiments were performed in the presence of nicardipine 10(-6) M to reduce tissue movement. Images were analyzed using Scion image and a specifically developed macro to correct for residual minimal movements. A 75 mM K(+)-Krebs solution identified 1,076 neurons in 46 myenteric ganglia (16 animals). Administration of CRF 10(-6) M and CRF 10(-7) M during 30 s induced a Ca(2+) response in 22.4% of the myenteric neurons (n = 303). Responses were completely abolished in the presence of the nonselective CRF antagonist astressin (n = 55). The selective CRF-1 receptor antagonist CP 154,526 (n = 187) reduced the response significantly to 2.1%. Stresscopin, a CRF-2 receptor agonist, could not activate neurons at 10(-7) M, and its effect at 10(-6) M (15.3%, n = 59) was completely blocked by CP 154,526. TTX 10(-6) M (n = 70) could not block the CRF-induced Ca(2+) transients but reduced the amplitude of the signals significantly. Removal of extracellular Ca(2+) blocked all responses to CRF (n = 47). L-type channels did not contribute to the CRF-induced Ca(2+) transients. Blocking N- or P/Q-type Ca(2+) channels did not reduce the responses significantly. Combined L- and R-type Ca(2+) channel blocking (SNX-482 10(-8) M, n = 64) abolished nearly all responses in situ. Combined L-, N-, and P/Q-type channel blocking also significantly reduced the response to 8.6%. Immunohistochemical staining for CRF-1 receptors clearly labeled individual cell bodies in the ganglia, whereas the CRF-2 receptor staining was barely above background. CRF induces Ca(2+) transients in myenteric neurons via a CRF-1 receptor-dependent mechanism. These Ca(2+) transients highly depend on somatic calcium influx through voltage-operated Ca(2+) channels, in particular R-type channels. Action potential firing through voltage-sensitive sodium channels increases the amplitude of the Ca(2+) signals. Besides centrally mediated effects, CRF is likely to modulate gastrointestinal motility on the myenteric neuronal level.     

The Ca2+-activated cation channel TRPM4 is regulated by phosphatidylinositol 4,5-biphosphate

Transient receptor potential (TRP) channel, melastatin subfamily (TRPM)4 is a Ca2+-activated monovalent cation channel that depolarizes the plasma membrane and thereby modulates Ca2+ influx through Ca2+-permeable pathways. A typical feature of TRPM4 is its rapid desensitization to intracellular Ca2+ ([Ca2+]i). Here we show that phosphatidylinositol 4,5-biphosphate (PIP2) counteracts desensitization to [Ca2+]i in inside-out patches and rundown of TRPM4 currents in whole-cell patch-clamp experiments. PIP2 shifted the voltage dependence of TRPM4 activation towards negative potentials and increased the channel's Ca2+ sensitivity 100-fold. Conversely, activation of the phospholipase C (PLC)-coupled M1 muscarinic receptor or pharmacological depletion of cellular PIP2 potently inhibited currents through TRPM4. Neutralization of basic residues in a C-terminal pleckstrin homology (PH) domain accelerated TRPM4 current desensitization and strongly attenuated the effect of PIP2, whereas mutations to the C-terminal TRP box and TRP domain had no effect on the PIP2 sensitivity. Our data demonstrate that PIP2 is a strong positive modulator of TRPM4, and implicate the C-terminal PH domain in PIP2 action. PLC-mediated PIP2 breakdown may constitute a physiologically important brake on TRPM4 activity.     

Effect of N,N-dimethylglycine supplementation in parturition feed for sows on metabolism, nutrient digestibility and reproductive performance

The current pilot study assessed the influence of N,N-dimethylglycine (DMG) on insulin sensitivity, glucose and fat metabolism, nutrient digestibility and reproductive performance of sows in the peripartal period. At day 105 of gestation, 25 sows were randomly assigned to the control (n = 13) or the DMG group (n = 12). Sows from the DMG group were supplemented with 1 g DMG/kg feed until day 3 of lactation. After an overnight fast 1 day after farrowing, a blood sample of each sow was drawn. The plasma was analyzed for insulin, glucose, fructosamine, leptin, thiobarbituric acid reactive substances (TBARS), ferric reducing ability of plasma (FRAP), non-esterified fatty acids (NEFA) and triglycerides (TG) and an oral glucose tolerance test was performed. A rectal feces sample was collected and the apparent fecal digestibility (AFD) of crude fat (CFAT), crude protein (CP) and nitrogen-free extract (NFE) was calculated after proximate analyses. Finally, a colostrum sample was collected from each sow and analyzed for the presence of DMG. Reproductive performance parameters were recorded. The results showed an improvement in the AFD of CFAT, CP and NFE when DMG was supplemented. This beneficial effect confirms the hypothesis that DMG acts as an emulsifying agent. The improvement in digestibility in the DMG group was accompanied by a numerical increase in plasma TG (P = 0.067). Plasma NEFA concentrations were not different between treatment groups. DMG supplementation neither affected glucose clearance nor influenced plasma insulin, glucose, fructosamine or leptin levels. TBARS and FRAP also remained unaffected, despite previously reported anti-oxidative properties of DMG. Furthermore, no significant impact on reproductive performance could be recorded. In conclusion, DMG supplementation significantly improved nutrient digestibility. Possible beneficial effects on energy metabolism and reproductive performance of sows should be tested when DMG is supplemented for a longer period of time or at a higher dose.     

Spatial Variation in Denitrification and N2O Emission in Relation to Nitrate Removal Efficiency in a N-stressed Riparian Buffer Zone

Spatial variability in hydrological flowpaths and nitrate-removal processes complicates the overall assessment of riparian buffer zone functioning in terms of water quality improvement as well as enhancement of the greenhouse effect by N₂O emissions. In this study, we evaluated denitrification and nitrous oxide emission in winter and summer along two groundwater flowpaths in a nitrate-loaded forested riparian buffer zone and related the variability in these processes to controlling soil factors. Denitrification and emissions of N₂O were measured using flux chambers and incubation experiments. In winter, N₂O emissions were significantly higher (12.4 mg N m⁻² d⁻¹) along the flowpath with high nitrate removal compared with the flowpath with low nitrate removal (2.58 mg N m⁻² d⁻¹). In summer a reverse pattern was observed, with higher N₂O emissions (13.6 mg N m⁻² d⁻¹) from the flowpath with low nitrate-removal efficiencies. Distinct spatial patterns of denitrification and N₂O emission were observed along the high nitrate-removal transect compared to no clear pattern along the low nitrate-removal transect, where denitrification activity was very low. Results from this study indicate that spots with high nitrate-removal efficiency also contribute significantly to an increased N₂O emission from riparian zones. Furthermore, we conclude that high variability in N₂O:N₂ ratio and weak relationships with environmental conditions limit the value of this ratio as a proxy to evaluate the environmental consequences of riparian buffer zones.     

Patterns of inflammation and the use of reversibility testing in smokers with airway complaints

Background

Although both smoking and respiratory complaints are very common, tools to improve diagnostic accuracy are scarce in primary care. This study aimed to reveal what inflammatory patterns prevail in clinically established diagnosis groups, and what factors are associated with eosinophilia.

Method

Induced sputum and blood plasma of 59 primary care patients with COPD (n = 17), asthma (n = 11), chronic bronchitis (CB, n = 14) and smokers with no respiratory complaints ('healthy smokers', n = 17) were collected, as well as lung function, smoking history and clinical work-up. Patterns of inflammatory markers per clinical diagnosis and factors associated with eosinophilia were analyzed by multiple regression analyses, the differences expressed in odds ratios (OR) with 95% confidence intervals.

Results

Multivariately, COPD was significantly associated with raised plasma-LBP (OR 1.2 [1.04–1.37]) and sTNF-R55 in sputum (OR 1.01 [1.001–1.01]), while HS expressed significantly lowered plasma-LBP (OR 0.8 [0.72–0.95]). Asthma was characterized by higher sputum eosinophilic counts (OR 1.3 [1.05–1.54]), while CB showed a significantly higher proportion of sputum lymphocytic counts (OR 1.5 [1.12–1.9]). Sputum eosinophilia was significantly associated with reversibility after adjusting for smoking, lung function, age, gender and allergy.

Conclusion

Patterns of inflammatory markers in a panel of blood plasma and sputum cells and mediators were discernable in clinical diagnosis groups of respiratory disease. COPD and so-called healthy smokers showed consistent opposite associations with plasma LBP, while chronic bronchitics showed relatively predominant lymphocytic inflammation compared to other diagnosis groups. Only sputum eosinophilia remained significantly associated with reversibility across the spectrum of respiratory disease in smokers with airway complaints.     

Isolation and characterization of drosocrystallin, a lens crystallin gene of Drosophila melanogaster

We have cloned the drosocrystallin gene (dcy) of Drosophila melanogaster, which encodes a major protein of the corneal lens, previously described in part by Komori et al. (1992, J. Cell Sci. 102, 191-201). Synthesis of the DCY protein starts weakly in 2-day-old pupae, reaches a peak at day 3 and day 4 of pupal development, and decreases very fast in young adults. The dcy mRNA is detected in the compound eyes as well as in the ocelli. The presence of a putative signal peptide and the extracellular location of DCY suggest that DCY is a secreted protein. Interestingly, the dcy gene shows sequence similarities to some insect cuticular proteins and is detected as well in two closely related Drosophila species, D. sechellia and D. simulans, and in one more distantly related species, D. virilis. This finding supports the hypothesis that Drosophila used the same strategy as vertebrates and mollusks, namely, recruiting a multifunctional protein for refraction in the lens, by a gene-sharing mechanism. Furthermore, it supports our intercalary evolution hypothesis, which suggests that the development of an elaborate structure (for example, a compound eye) from an original primitive form (an ancestral photoreceptor organ) can be achieved by recruiting novel genes into the original developmental pathway.