Description and quantification of pteropod shell dissolution: a sensitive bioindicator of ocean acidification

Anthropogenic ocean acidification is likely to have negative effects on marine calcifying organisms, such as shelled pteropods, by promoting dissolution of aragonite shells. Study of shell dissolution requires an accurate and sensitive method for assessing shell damage. Shell dissolution was induced through incubations in CO₂‐enriched seawater for 4 and 14 days. We describe a procedure that allows the level of dissolution to be assessed and classified into three main types: Type I with partial dissolution of the prismatic layer; Type II with exposure of underlying crossed‐lamellar layer, and Type III, where crossed‐lamellar layer shows signs of dissolution. Levels of dissolution showed a good correspondence to the incubation conditions, with the most severe damage found in specimens held for 14 days in undersaturated condition (Ω ~ 0.8). This methodology enables the response of small pelagic calcifiers to acidified conditions to be detected at an early stage, thus making pteropods a valuable bioindicator of future ocean acidification.     

A cAMP signalosome in primary cilia drives gene expression and kidney cyst formation

The primary cilium constitutes an organelle that orchestrates signal transduction independently from the cell body. Dysregulation of this intricate molecular architecture leads to severe human diseases, commonly referred to as ciliopathies. However, the molecular underpinnings how ciliary signaling orchestrates a specific cellular output remain elusive. By combining spatially resolved optogenetics with RNA sequencing and imaging, we reveal a novel cAMP signalosome that is functionally distinct from the cytoplasm. We identify the genes and pathways targeted by the ciliary cAMP signalosome and shed light on the underlying mechanisms and downstream signaling. We reveal that chronic stimulation of the ciliary cAMP signalosome transforms kidney epithelia from tubules into cysts. Counteracting this chronic cAMP elevation in the cilium by small molecules targeting activation of phosphodiesterase‐4 long isoforms inhibits cyst growth. Thereby, we identify a novel concept of how the primary cilium controls cellular functions and maintains tissue integrity in a specific and spatially distinct manner and reveal novel molecular components that might be involved in the development of one of the most common genetic diseases, polycystic kidney disease.     

Coordinate Based Meta-Analysis of Functional Neuroimaging Data; False Discovery Control and Diagnostics

Coordinate based meta-analysis (CBMA) is widely used to find regions of consistent activation across fMRI studies that have been selected for their functional relevance to a given hypothesis. Only reported coordinates (foci), and a model of their spatial uncertainty, are used in the analysis. Results are clusters of foci where multiple studies have reported in the same spatial region, indicating functional relevance. There are several published methods that perform the analysis in a voxel-wise manner, resulting in around 10⁵ statistical tests, and considerable emphasis placed on controlling the risk of type 1 statistical error. Here we address this issue by dramatically reducing the number of tests, and by introducing a new false discovery rate control: the false cluster discovery rate (FCDR). FCDR is particularly interpretable and relevant to the results of CBMA, controlling the type 1 error by limiting the proportion of clusters that are expected under the null hypothesis. We also introduce a data diagnostic scheme to help ensure quality of the analysis, and demonstrate its use in the example studies. We show that we control the false clusters better than the widely used ALE method by performing numerical experiments, and that our clustering scheme results in more complete reporting of structures relevant to the functional task.     

Dissimilarity of stream insect assemblages: effects of multiple scales and spatial distances

In addition to the effects of environmental conditions, biotic assemblages may exhibit spatial structure depending on the scale of study. We tested whether the dissimilarity of stream insect assemblages is related to two types of spatial distances (stream corridor and overland distance), and evaluated the relative importance of diversity components at multiple spatial scales. Field data included assemblages of Ephemeroptera, Plecoptera, and Trichoptera found in 16 streams in four microbasins. We evaluated the relationship of the dissimilarity of assemblages with the distance types, using Mantel tests. In addition, we evaluated the relationships among the diversity components at multiple spatial scales, using additive partitioning analysis. The biological dissimilarities were correlated only with the geographical distances. Additive partitioning showed that the values of richness observed in the β1 (among Surber), β2 (among riffles), β3 (among streams), and β4 (among microbasins) were higher than those expected. The highest variation of the richness was found in β3 (30.6%). We conclude that stream faunas are distributed in patches all over the studied spatial extent, causing a weak relationship of biological dissimilarity with distance but important beta components when compared to a completely homogenous distribution of the fauna.     

Continuous intravenous insulin therapy with a miniaturized open-loop system.

For the continuous intravenous application of insulin, a portable open-loop system was developed consisting of a delivery unit with a miniaturized pump and an insulin reservoir which is connected with an electronic control unit. The infusion rates were either preprogrammed or patient-controlled. Blood glucose control with both systems was tested in eight juvenile-type diabetics, among them two of the brittle type. Diabetic control during a 1-2-day pre-infusion period was compared with 2-3 days of continuous insulin infusion; as judged by the mean blood glucose value (MBG), the mean amplitude of glycemic excursions (MAGE), and glucosuria, all patients were significantly better controlled by the open-loop systems than by conventional therapy with subcutaneous insulin. The use of portable open-loop systems offers a promising approach to an improvement of metabolic control in insulin-requiring diabetics.     

Expression and regulation of aromatase and 17β-hydroxysteroid dehydrogenase type 4 in human THP 1 leukemia cells

Estradiol is active in proliferation and differentiation of sex-related tissues like ovary and breast. Glandular steroid metabolism was for a long time believed to dominate the estrogenic milieu around any cell of the organism. Recent reports verified the expression of estrogen receptors in “non-target” tissues as well as the extraglandular expression of steroid metabolizing enzymes. Extraglandular steroid metabolism proved to be important in the brain, skin and in stromal cells of hormone responsive tumors. Aromatase converts testosterone into estradiol and androstenedione into estrone, thereby activating estrogen precursors. The group of 17β-hydroxysteroid dehydrogenases catalyzes the oxidation and/or reduction of the forementioned compounds, e.g. estradiol/estrone, thereby either activating or inactivating estradiol. Aromatase is expressed and regulated in the human THP 1 myeloid leukemia cell line after vitamin D/GMCSF-propagated differentiation. Aromatase expression is stimulated by dexamethasone, phorbolesters and granulocyte/macrophage stimulating factor (GMCSF). Exons I.2 and I.4 are expressed in PMA-stimulated cells only, exon I.3 in both PMA- and dexamethasone-stimulated cells. Vitamin D-differentiated THP 1 cells produce a net excess of estradiol in culture supernatants, if testosterone is given as aromatase substrate. In contrast, the 17β-hydroxysteroid dehydrogenase type 4 (17β-HSD 4) is abundantly expressed in unstimulated THP 1 cells and is further stimulated by glucocorticoids (2-fold). The expression is unchanged after vitamin D/GMCSF-propagated differentiation. 17β-HSD 4 expression is not altered by phorbolester treatment in undifferentiated cells but is abolished after vitamin D-propagated differentiation along with downregulation of β-action. Protein kinase C activation therefore appears to dissociate the expression of aromatase and 17β-HSD 4 in this differentiation stage along the monocyte/phagocyte pathway of THP 1 myeloid cells. The expression of steroid metabolizing enzymes in myeloid cells is able to create a microenvironment which is uncoupled from dominating systemic estrogens. These findings may be relevant in the autocrine, paracrine or iuxtacrine cellular crosstalk of myeloid cells in their respective states of terminal differentiation, e.g. in bone metabolism and inflammation.     

A comparative investigation of the antimitotic action of 2-mercaptoethanol and colcemid on V-79 Chinese hamster cells

Abstract. The current study was performed to characterize the antimitotic action of 2-mercaptoethanol (MET) on mammalian cells.
At concentrations of 2.5 × 10^-2 M, MET arrests V-79 Chinese hamster cells in metaphase. Smaller concentrations (from 5 × 10^-3 M) only produce a mitotic block after several hours, only arresting those mitoses which have gone through one cell cycle in the presence of MET. The accumulation of mitoses by MET is smaller in comparison with colcemid, explained by an effect reducing the number of cells which enter mitosis. In contrast to colcemid, MET-concentrations which do not lead to a mitotic block cause a delay in proliferation. It was shown, by means of the BUdR-labelling method that cells in the presence of colcemid concentrations which arrest mitosis again enter interphase and become polyploid, whereas MET leads to an irreversible arrest of mitosis and does not produce polyploidy in V-79 cells.     

Genetic regulation of the antibody response to H-2Db alloantigens in mice

The cytotoxic antibody response to the H-2D^b alloantigen has been investigated in ten strains of the C57BL/10 background. Three types of responses could be distinguished: no detectable response, an IgM response, and an IgG response. The IgG response is influenced by the D and probably the I-A region of the H-2 complex, whereas the IgM response is dependent on the allele for the E chain. The hypothesis is proposed that regulatory T cells, which recognize the antigen in context of self MHC molecules, determine the outcome of an anti-H-2D^b immunization in which the I-E molecule restricts the IgM response and the I-A molecule restricts the IgG response; the D molecule is probably responsible for activation of suppressor T cells which suppress only the IgG response.     

UV-light induced sister chromatid exchanges in xeroderma pigmentosum lymphocytes

Summary Cultured lymphocytes from 9 patients with clinically different types of xeroderma pigmentosum were exposed to ultraviolet light at 24 h. An increased rate of sister chromatid exchanges was observed in 6 patients (128–148% increase in three, 34–51% in three), but not in three patients with deSanctis-Cacchione syndrome (xeroderma pigmentosum with mental defect), compared to simultaneously cultured controls. A positive result could be useful as preliminary cytogenetic diagnostic test. The results are interpreted as an expression of UV-light induced chromosomal instability due to impaired DNA repair.