Reassessing Neotropical angiosperm distribution patterns based on monographic data: a geometric interpolation approach

Monographic data rely on specimens deposited in herbaria and museums, which have been thoroughly revised by experts. However, monographic data have been rarely used to map species richness at large scale, mainly because of the difficulties caused by spatially heterogeneous sampling effort. In this paper we estimate patterns of species richness and narrow endemism, based on monographic data of 4,055 Neotropical angiosperm species. We propose a geometric interpolation method to derive species ranges at a 1° grid resolution. To this we apply an inverse distance-weighted summation scheme to derive maps of species richness and endemism. In the latter we also adjust for heterogeneous sampling effort. Finally, we test the robustness of the interpolated species ranges and derived species richness by applying the same method but using a leave-one-out-cross-validation (LOOCV). The derived map shows four distinct regions of elevated species richness: (1) Central America, (2) the Northern Andes, (3) Amazonia and (4) the Brazilian Atlantic coast (‘Mata Atlantica’). The region with the highest estimated species richness is Amazonia, with Central America following closely behind. Centers of narrow endemism are located over the entire Neotropics, several of them coinciding with regions of elevated species richness. Sampling effort has a minor influence on the interpolation of overall species richness, but it substantially influences the estimation of regions of narrow endemism. Thus, in order to improve maps of narrow endemism and resulting conservation efforts, more collection and identification activity is required.     

Expression of Mitochondrial Regulators PGC1α and TFAM as Putative Markers of Subtype and Chemoresistance in Epithelial Ovarian Carcinoma

Epithelial ovarian carcinoma (EOC), the major cause of gynaecological cancer death, is a heterogeneous disease classified into five subtypes. Each subtype has distinct clinical characteristics and is associated with different genetic risk factors and molecular events, but all are treated with surgery and platinum/taxane regimes. Tumour progression and chemoresistance is generally associated with major metabolic alterations, notably altered mitochondrial function(s). Here, we report for the first time that the expression of the mitochondrial regulators PGC1α and TFAM varies between EOC subtypes; furthermore, we have identified a profile in clear-cell carcinoma consisting of undetectability of PGC1α/TFAM, and low ERα/Ki-67. By contrast, high-grade serous carcinomas were characterised by a converse state of PGC1α/TFAM, ERα positivity and a high Ki-67 index. Interestingly, loss of PGC1α/TFAM and ERα was found also in a non-clear cell EOC cell line made highly resistant to platinum in vitro. Similar to clear-cell carcinomas, these resistant cells also showed accumulation of glycogen. Altogether, our data provide mechanistic insights into the chemoresistant nature of ovarian clear-cell carcinomas. Furthermore, these findings corroborate the need to take into account the diversity of EOC and to develop subtype specific treatment strategies.     

Influence of ionic strength and pH on the interaction between high-affinity heparin and antithrombin

Binding constants for the binding of high-affinity heparin to antithrombin at different ionic strengths were determined by fluorescence titrations and were also estimated from dissociation curves of the heparin-antithrombin complex. These curves were monitored by near-ultraviolet circular dichroism or fluorescence. The dependence of the binding constant on the activity of NaCl suggested that maximally 5–6 charged groups are directly involved in the interaction between the two macromolecules. Major pH-dependent changes of the interaction, as evident by changes of the spectroscopic properties of the complex between the molecules, were found to occur below pH 5.5 and above pH 8.5. The acid change, which was irreversible, was most likely caused by an irreversible conformational change of antithrombin. At alkaline pH, however, the gross conformation of antithrombin was stable up to pH 12, while the affinity of high-affinity heparin for antithrombin began to decrease markedly at pH 8.5. The dissociation curve, which was reversible, had a midpoint around pH 9.5. This is compatible with the loss of affinity being caused by either a local conformational change, by ionization of tyrosine or by titration of one or more amino groups.     

Arginase,an s-phase enzyme in a human cell line

Suspension cultures of ‘Chang liver’ cells were synchronized by preincubation in a glutamine-deficient medium or by thymidine blockade. Specific arginase activity varied in the synchronized cultures, being high when the number of S-phase cells was maximal. A relationship between high arginase activity and a high percentage of (S+G₂) cells was also found when unsynchronized cells were separated by velocity sedimentation. The increase in arginase activity near the G₁/S border was totally inhibited in the presence of cycloheximide. The rate of decrease in activity after addition of the drug indicated that the variations in the rate of synthesis of the enzyme, while the rate of degradation was more or less constant, corresponding to 4–6% per h. The role of arginase in cells lacking a urea cycle and the regulation of arginase activity in ‘Chang liver’ cells is discussed.     

Pathogenicity for Chickens of a Paramyxovirus Type 1, Isolated from Racing Pigeons in Sweden

Strains of paramyxovirus type 1 (PMV-1) have been isolated from diseased racing pigeons in Sweden. One of these isolates was selected for studies of the pathogenicity and contagiousness in chickens. The same isolate was previously found to have a high intravenous pathogenicity index (IVPI) in 6 weeks old chickens. In three experiments it was found that the PMV-1 isolate was very pathogenic for 1 week old chickens but not pathogenic for 120 day old pullets inoculated intranasally and ocularly. Symptoms in the young chickens were similar to those seen in the neurotropic form of Newcastle disease. The mortality was high and the incubation period 5–11 days. The disease easily spread to young chickens kept in contact with diseased birds. The microscopic examination revealed an interstitial nonpurulent pneumonia and a nonpurulent encephalitis in the young chickens. In the pullets the only finding was a mild encephalitis. PMV-1 was recovered from all young chickens but not from the pullets. Both the chickens and the inoculated pullets developed antibodies to PMV-1.     

Environmental stability affects phenotypic evolution in a globally distributed marine picoplankton

Marine phytoplankton can evolve rapidly when confronted with aspects of climate change because of their large population sizes and fast generation times. Despite this, the importance of environment fluctuations, a key feature of climate change, has received little attention—selection experiments with marine phytoplankton are usually carried out in stable environments and use single or few representatives of a species, genus or functional group. Here we investigate whether and by how much environmental fluctuations contribute to changes in ecologically important phytoplankton traits such as C:N ratios and cell size, and test the variability of changes in these traits within the globally distributed species Ostreococcus. We have evolved 16 physiologically distinct lineages of Ostreococcus at stable high CO₂ (1031±87 μatm CO₂, SH) and fluctuating high CO₂ (1012±244 μatm CO₂, FH) for 400 generations. We find that although both fluctuation and high CO₂ drive evolution, FH-evolved lineages are smaller, have reduced C:N ratios and respond more strongly to further increases in CO₂ than do SH-evolved lineages. This indicates that environmental fluctuations are an important factor to consider when predicting how the characteristics of future phytoplankton populations will have an impact on biogeochemical cycles and higher trophic levels in marine food webs.     

Physiology of the ECL cells.

The enterochromaffin-like (ECL) cells of the oxyntic mucosa (fundus) of the stomach produce, store and secrete histamine, chromogranin A-derived peptides such as pancreastatin, and an unanticipated but as yet unidentified peptide hormone. The cells are stimulated by gastrin and pituitary adenylate cyclase activating peptide and suppressed by somatostatin and galanin. Choline esters and histamine seem to be without effect on ECL cell secretion. The existence of a gastrin-ECL cell axis not only explains how gastrin stimulates acid secretion but also may help to explore the functional significance of the ECL cells with respect to the nature and bioactivity of its peptide hormone. From the results of studies of gastrectomized/fundectomized and gastrin-treated rats, it has been speculated that the anticipated ECL-cell peptide hormone acts on bone metabolism.