Individual features of circulatory power spectra in man

Rhythms of resting fluctuations of circulatory parameters in man reveal a considerable interindividual variability. We posed the question whether these rhythms are long-term individual characteristics. In nine healthy subjects aged 19-23 years the blood pressure and the finger blood flow were recorded by indirect continuous methods, together with cardiac intervals and respiratory movements. These recordings were repeated in each subject after 1 year. The power spectra of all the parameters recorded were calculated for 5-min periods. The shape of spectra and the division of power into four ranges of frequencies were compared to the spectra recorded after 1 year in each subject and the degree of similarity was evaluated by means of correlation analysis. The average measures of similarity (correlation coefficients) were high, cardiac intervals 0.527, systolic pressure 0.782, pulse pressure 0.755, diastolic pressure 0.709, mean blood pressure 0.673, blood flow 0.818 and respiration 0.627. All these values were higher than values obtained by comparison of spectra of two individuals chosen randomly. The differences were statistically significant for cardiac intervals (Wilcoxon test: P less than 0.05), pulse pressure (P less than 0.05) and respiration (P less than 0.01). These results have shown that interindividual variability of circulatory and respiratory spectra was greater than the intraindividual one. The resting circulatory rhythms are very stable individual features.     

Ovarian cysts in high-yielding dairy cows

We examined the hormonal and morphologic changes associated with ovarian cyst formation in high-yielding dairy cows. Follicle fluid was aspirated from 90 cysts and 15 preovulatory and 18 subordinate follicles and used for hormonal determination. Pieces of cystic wall were subjected to morphologic and immunohistochemical evaluation. Cysts were characterized by low concentrations of insulin, insulin-like growth factor-I (IGF-I), and glucose and high activity of IGF binding proteins (IGFBPs). Insulin and IGF-I levels were (mean ± SEM) 205 ± 22 pg/mL and 146 ± 42 ng/mL in preovulatory follicles and 3 ± 1 pg/mL and 61 ± 6 ng/mL in cysts, respectively (P < 0.001). Insulin-like growth factor-binding proteins activity was about 10 times higher in cysts than in preovulatory follicles. Cysts were classified into three types according to their estradiol-to-progesterone (E/P) ratio. Type 1 cysts (n = 23) exhibited the highest E/P ratio (10.8 ± 2.3), partial loss of granulosa cells, and severe morphologic changes in the theca interna. Expression of P₄₅₀ side-chain cleavage and P₄₅₀ 17α-hydroxylase was noted in theca cells and expression of inhibin-α in granulosa cells. Type 2 cysts (n = 35) had a low E/P ratio (0.07 ± 0.02), and patches of luteal-like tissue in the cystic wall. Type 3 cysts (n = 32) had an E/P ratio of 0.91 ± 0.17, and no recognizable granulosa or theca cells. In summary, intrafollicular steroid levels as expressed by E/P ratio, together with IGF-I and insulin levels and morphologic changes in the follicular wall, may serve as accurate cyst-classification parameters. Because IGF-I and/or insulin play an essential role in the final stage of follicle development, it can be speculated that abnormal levels of these metabolic hormones might lead to follicle dysfunction, resulting in follicular regression or cyst formation.     

Habituation and dehabituation to dichlobenil: Simply the equivalent of Penélope's weaving and unweaving process?

The habituation of cell cultures to cellulose biosynthesis inhibitors constitutes a valuable method for learning more about the plasticity of plant cell wall composition and structure. The subculture of habituated cells in the absence of an inhibitor (dehabituation) offers complementary information: some habituation-associated modifications revert, whereas others remain, even after longterm (3–5 years) dehabituation processes. However, is dehabituation simply the opposite to the process of habituation, in the same way that the cloth woven by Penélope during the day was unwoven during the night? Principal Component Analysis applied to Fourier Transformed Infrared (FTIR) spectra of cell walls from dichlobenil-habituated and dehabituated bean cell lines has shown that dehabituation follows a different pathway to that of habituation. Principal component loadings show that dehabituated cells have more pectins, but that these display a lower degree of methyl-esterification, than those of habituated ones. Further analysis of cell walls focusing on the first steps of habituation would serve to identify which specific modifications in pectins are responsible to the fine modulation of cell wall architecture observed during the habituation/dehabituation process.Key words: cell-wall, cellulose, dichlobenil, habituation-dehabituation, Fourier transform infrared spectroscopy, principal component analysisThe habituation of cell cultures to the presence of lethal concentrations of cellulose biosynthesis inhibitors illustrates the ability of cells to survive with a modified cell wall and is therefore a valuable experimental technique for gaining an insight into the plasticity of plant cell wall composition and structure. Dichlobenil-habituated cultures usually display some common features: slower growth rates, irregularly shaped cells, a trend to grow in clumps when cultured in suspension and compensation of reduced cell wall cellulose content with other cell wall components.^1–3Most of the cell wall changes induced during the habituation to dichlobenil reverted when cells were dehabituated by culturing them in an inhibitor-free medium.^4–7 However, even in long term (3–5 years) dehabituated cell cultures, some habituation-induced cell wall modifications remain, such as altered extractability of pectins, a decrease in arabinogalactan proteins and hydroxyproline-rich glycoproteins epitopes, and the presence of a soluble β-(1,4)-glucan, although cellulose levels were restored.^5–7 Most remarkably, in addition to these stable changes in cell wall architecture, bean dehabituated cells retained a high capacity to cope with lethal concentrations of dichlobenil, as dehabituated cells were forty times more tolerant to dichlobenil than non-habituated cells.⁵ In an attempt to explain the dichlobenil resistance of dehabituated cells it was found that they had a constitutively increased peroxidase activity, indicating a positive relationship between habituation to dichlobenil and antioxidant capacity.⁷If most of the cell wall modifications induced during the habituation to dichlobenil eventually revert to those of non-habituated cells during the dehabituation process, a question arises: is dehabituation simply the inverse of habituation, in the same way that the cloth woven by Penelope during the day was unwoven during the night, as narrated in Homer''s The Odyssey?Principal Component Analysis applied to Fourier Transformed InfraRed spectra of cell walls has been demonstrated to be a powerful technique for conducting comparative analysis of a wide range of cell wall samples.^3,8 Therefore, a suitable approach to answering this question consists in comparison of cell walls from dichlobenil-habituated and dehabituated bean cell lines using this technique.Clearly, FTIR spectra of cell walls from dehabituated cells with few subcultures in the absence of the herbicide resemble those from cultures habituated to high dichlobenil concentrations.⁵ However, the spectra from cells habituated to low inhibitor concentrations and from cells dehabituated for long periods of time⁷ were more similar to those from non-habituated ones. In fact, when Principal Component Analysis is applied to the entire range, Principal Component 2 (PC2) discriminates between Sh₁₂ (corresponding to cells habituated to high dichlobenil concentration) and the rest of the spectra, which is indicative of the above-mentioned similarity (Fig. 1). Nevertheless, PC1 clearly discriminates between spectra from long-term dehabituated cell walls (located at the positive side) and those from cells habituated to low dichlobenil concentrations (at the negative side). This indicates that progression towards dehabituation follows a different path to that of habituation.Open in a separate windowFigure 1Principal Component Analysis of spectra of cell walls from different calluses. A plot of the first two Principal Components scores is represented based on the FTIR spectra of cell walls from non-habituated cells (Snh, ○), cells habituated to different dichlobenil concentrations (Sh, ▲), and cells previously habituated to 12 µm dichlobenil, with a different number of subcultures in the absence of the herbicide (Sd, ◆). Subindexes indicate dichlobenil concentrations in the growth media of habituated cells (0.3, 0.4 or 12 µm); superindexes indicate number of subcultures in the same media. Arrows indicate the different pathways followed by dichlobenil habituation and dehabituation: black arrows, from non-habituated to habituated cells (habituation), and white arrows, from habituated to non-habituated cells (dehabituation).With the aim of identifying those factors which determine this different pathway, PC1 and PC2 loading factors were analyzed (Fig. 2). This analysis indicated that PC2 (explaining 26.4% of total variance) has a positive correlation with wavenumbers attributed to uronic acids (1,420 and 1,600 cm⁻¹) and galactose (950 cm⁻¹), and a negative correlation with wavenumbers associated with cellulose (1,040, 1,060, 1,175, 1,320 and 1,370 cm⁻¹) and xyloglucan (1,125 cm⁻¹). Thus, Sh₁₂ cell walls (clearly located at the positive side of PC2) are pectin enriched and cellulose/xyloglucan impoverished. As explained above, PC1 discriminates between cell walls from dehabituated cell lines and those from cells habituated to low concentrations of dichlobenil. PC1 (accounting for 42.55% of total variance) has a negative correlation with wavenumbers associated with methylester groups (negative peaks at 1,250 and 1,720 cm⁻¹), and a positive correlation with the so called “fingerprint” region (980–1,200 cm⁻¹). Therefore, cell walls from dehabituated cells (those located at the positive side of PC1) would have lower methyl-esterified pectins when compared with cells habituated to low concentrations of dichlobenil.Open in a separate windowFigure 2Loadings for PC1 and PC2 corresponding to Figure 1. White arrowheads point wavenumbers associated with methyl-esterification; black arrowheads, those associated with cellulose and hemicelluloses, and grey arrowheads indicate wavenumbers associated with uronic acids and galactose.Previous results had revealed that dichlobenil habituated cells experienced a progressive reversion in their cell wall composition when they were subcultured in an inhibitor-free medium, gradually increasing their xyloglucan and cellulose content,^5,6 and that both dichlobenil habituated and dehabituated cells showed changes in the distribution of pectin among cell wall fractions: cell suspensions with a low habituation level had cell walls with a higher amount of pectins, and these were more methyl-esterified.⁶Now, FTIR spectroscopy in association to Principal Component Analysis has shown that, although some of the changes observed in the first steps of habituation and in the last steps of dehabituation are common (i.e., reversion of cellulose content), some other changes affect habituated and dehabituated cells differently, and that these changes involve mainly pectin composition and organization. A more detailed analysis of cell walls focusing on the first steps of habituation will serve to identify which specific modifications are responsible for the differences observed in the pectic component and, consequently, responsible for the fine modulation of cell wall architecture.     

The phenolic profile of maize primary cell wall changes in cellulose-deficient cell cultures

Cultured maize cells habituated to grow in the presence of the cellulose synthesis inhibitor dichlobenil (DCB) have a modified cell wall in which the amounts of cellulose are reduced and the amounts of arabinoxylan increased. This paper examines the contribution of cell wall-esterified hydroxycinnamates to the mechanism of DCB habituation. For this purpose, differences in the phenolic composition of DCB-habituated and non-habituated cell walls, throughout the cell culture cycle and the habituation process were characterized by HPLC. DCB habituation was accompanied by a net enrichment in cell wall phenolics irrespective of the cell culture phase. The amount of monomeric phenolics was 2-fold higher in habituated cell walls. Moreover, habituated cell walls were notably enriched in p-coumaric acid. Dehydrodimers were 5–6-fold enhanced as a result of DCB habituation and the steep increase in 8,5′-diferulic acid in habituated cell walls would suggest that this dehydrodimer plays a role in DCB habituation. In summary, the results obtained indicate that cell wall phenolics increased as a consequence of DCB habituation, and suggest that they would play a role in maintaining the functionality of a cellulose impoverished cell wall.     

Development and validation of a TaqMan PCR assay for the Australian abalone herpes-like virus

The recent emergence of a herpes-like virus in both farmed and wild populations of abalone in Victoria, Australia, has been associated with high mortality rates in animals of all ages. Based on viral genome sequence information, a virus-specific real-time TaqMan assay was developed for detection and identification of the abalone herpes-like virus (AbHV). The assay was shown to be specific as it did not detect other viruses from either the Herpesvirales or the Iridovirales orders which have genome sequence similarities. However, the TaqMan assay was able to detect DNA from the Taiwanese abalone herpes-like virus, suggesting a relationship between the Taiwanese and Australian viruses. In addition, the assay detected < 300 copies of recombinant plasmid DNA per reaction. Performance characteristics for the AbHV TaqMan assay were established using 1673 samples from different abalone populations in Victoria and Tasmania. The highest diagnostic sensitivity and specificity were 96.7 (95% CI: 82.7 to 99.4) and 99.7 (95% CI: 99.3 to 99.9), respectively, at a threshold cycle (C(T)) value of 35.8. The results from 2 separate laboratories indicated good repeatability and reproducibility. This molecular assay has already proven useful in confirming presumptive diagnosis (based on the presence of ganglioneuritis) of diseased abalone in Victorian waters as well as being a tool for surveillance of wild abalone stocks in other parts of Australia.     

Stable isotope views on ecosystem function: challenging or challenged?

Stable isotopes and their potential for detecting various and complex ecosystem processes are attracting an increasing number of scientists. Progress is challenging, particularly under global change scenarios, but some established views have been challenged. The IX meeting of the Spanish Association of Terrestrial Ecology (AAET, Úbeda, 18–22 October 2009) hosted a symposium on the ecology of stable isotopes where the linear mixing model approach of partitioning sinks and sources of carbon and water fluxes within an ecosystem was challenged, and new applications of stable isotopes for the study of plant interactions were evaluated. Discussion was also centred on the need for networks that monitor ecological processes using stable isotopes and key ideas for fostering future research with isotopes.     

Geographical patterns of adaptation within a species' range: interactions between drift and gene flow

We use individual-based stochastic simulations and analytical deterministic predictions to investigate the interaction between drift, natural selection and gene flow on the patterns of local adaptation across a fragmented species' range under clinally varying selection. Migration between populations follows a stepping-stone pattern and density decreases from the centre to the periphery of the range. Increased migration worsens gene swamping in small marginal populations but mitigates the effect of drift by replenishing genetic variance and helping purge deleterious mutations. Contrary to the deterministic prediction that increased connectivity within the range always inhibits local adaptation, simulations show that low intermediate migration rates improve fitness in marginal populations and attenuate fitness heterogeneity across the range. Such migration rates are optimal in that they maximize the total mean fitness at the scale of the range. Optimal migration rates increase with shallower environmental gradients, smaller marginal populations and higher mutation rates affecting fitness.     

When random sampling does not work: standard design falsely indicates maladaptive host preferences in a butterfly

In experiments that investigate species' interactions, individuals are often chosen at random to represent their populations. However, this practice can generate misleading results when individuals of different species do not interact at random. We illustrate this effect by examining oviposition preferences of Euphydryas aurinia butterflies from three populations using three different plant genera. We first offered each insect a randomly chosen member of its own host population and a foreign host ( Succisa pratensis ) not present in the insect's habitat. The butterflies uniformly preferred the foreign Succisa over their own hosts. Preferences were apparently maladaptive because insects wasted time searching for a nonexistent plant. We repeated the experiment using individual hosts that had naturally received eggs in the field. The overall preference for Succisa and the appearance of maladaptation both disappeared. In the original experiments, our random choice of experimental host individuals had combined with strong within-species discrimination by the butterflies and with overlap of acceptability between host species to obscure the true nature of host preference.     

22-Oxocholestanes SPGP4 and SPGP8: in Silico and in Vitro Study as Activators of Plant Growth Promotion

The 22-oxocholestanes compounds have shown an outstanding plant growth promoting activity; they have similar bioactivity as brassinosteroids, so they are normally named as brassinosteroid analogs thinking that they also impact on the known receptor BRI1. However, in silico studies allow us to predict interactions with other receptors and thus it's possible to evaluate them, through receptors of gibberellins, auxins, jasmonates, strigolactones and the protein associated with the BRI1 gene. This article describes the bioactivity of structures SPGP4 and SPGP8 as plant growth-promoting compounds. Both structures present coupling energies and interactions at the same level as epibrassinolide in the protein associated with BRI1 gene. Additionally, interactions through the auxin pathway and to strigolactone receptor were found using selected tests. In the rice lamina tilt, a higher effect was obtained when SPGP4 and SPGP8 were compared to epibrassinolide, although in a lesser level vis à vis to homobrassinolide. In the same way, when SPGP4 and SPGP8 were tested in the Growth Root Model an activity as strigonolactones was observed, enhancing the relationship between the main and secondary roots. However, the growth of coleptiles, when applying auxins, compounds SPGP4 and SPGP8 did not reach the same level as controls. In the tests associated to gibberellins and jasmonic acid, an increased bioactivity was observed, although this behavior was not reflected from the in silico study, possibly due to secondary signaling cascades. This work demonstrates that the 22-oxocolestane compounds SPGP4 and SPGP8 could be used as plant growth hormones, promoting several pathways.