Parasitic chytrids could promote copepod survival by mediating material transfer from inedible diatoms

Diatoms form large spring blooms in lakes and oceans, providing fuel for higher trophic levels at the start of the growing season. Some of the diatom blooms, however, are not grazed by filter-feeding zooplankton like Daphnia due to their large size. Several of these large diatoms are susceptible to chytrid infections. Zoospores of chytrids appeared to be excellent food for Daphnia, both in terms of size, shape, and quality (PUFAs and cholesterol). Thus, zoospores of chytrids can bridge the gap between inedible diatoms and Daphnia. In order to examine the effects of diatoms and chytrids on the survival of copepods, we performed one grazing and one survival experiment. The grazing experiment revealed that the diatom, Asterionella formosa, was not grazed by the copepod, Eudiaptomus gracilis, even after being infected by the chytrid Zygorhizidium planktonicum. However, carbon and nitrogen concentrations were significantly reduced by E. gracilis only when A. formosa was infected by Z. planktonicum, indicating that the chytrids might facilitate material transfer from inedible diatoms to the copepods. The survival experiment revealed that E. gracilis lived shorter with A. formosa than with the cryptophyta Cryptomonas pyrenoidifera. However, the survival of E. gracilis increased significantly in the treatment where A. formosa cells were infected by Z. planktonicum. Since E. gracilis could not graze A. formosa cells due to their large colonial forms, E. gracilis may acquire nutrients by grazing on the zoospores, and were so able to survive in the presence of the A. formosa. This provides new insights into the role of parasitic fungi in aquatic food webs, where chytrids may improve copepod survival during diatom blooms.

Derivation of CPT resonance signals from density-matrix equations with all relevant sublevels of Cs atoms and confirmation of experimental results

Coherent-population-trapping resonance is a quantum interference effect that appears in the two-photon transitions between the ground-state hyperfine levels of alkali atoms and is often utilized in miniature clock devices. To quantitatively understand and predict the performance of this phenomenon, it is necessary to consider the transitions and relaxations between all hyperfine Zeeman sublevels involved in the different excitation processes of the atom. In this study, we constructed a computational multi-level atomic model of the Liouville density-matrix equation for 32 Zeeman sublevels involved in the $D_1$ line of $^{133}$Cs irradiated by two frequencies with circularly polarized components and then simulated the amplitude and shape of the transmitted light through a Cs vapor cell. We show that the numerical solutions of the equation and analytical investigations adequately explain a variety of the characteristics observed in the experiment.Comment: 24 pages, 8 figure

Encircled Angular Flux Representation of the Modal Power Distribution and its Behavior in a Step Index Multimode Fiber

The optical properties of in-line optical components inserted at the input to a multimode optical fiber (MMF) strongly affect the propagating modal power distribution (MPD). To realize stable systems with predictable reproducible performance and to encourage widespread use of MMF systems, improvements to the system design process and to the characterization process need to be made and new interface standards need to be defined. To this end, we have developed a new reproducible MPD measurement and representation together with its theoretical definition. By modifying the encircled flux (EF) representation, which is based on the near-field pattern of a graded-index multimode optical fiber (GI-MMF), we define the encircled angular flux (EAF) for step-index multimode optical fibers (SI-MMFs) based on their far-field patterns (FFPs). Using a SI-MMF, which is used for low cost short distance interconnects, as an example, we show the changes in the MPD along the fiber, reveal an unusual insertion loss-increasing phenomenon due to the evanescent tails of the core modes extending into the cladding, and characterize the equilibrium mode distribution (EMD) in the fiber. The EAF representation enables these phenomena to be quantified. We also propose an EAF template that consists of the target EMD and its tolerance. If device system designers use the EAF template to set the launch conditions, they can perform a fair assessment of the components, and they can design the system performance even if some components are replaced with others from a different supplier manufactured by a different method. We call this concept “Total MPD Management.

Ground-state electric quadrupole moment of 31Al

Ground-state electric quadrupole moment of 31Al (I =5/2+, T_1/2 = 644(25) ms) has been measured by means of the beta-NMR spectroscopy using a spin-polarized 31Al beam produced in the projectile fragmentation reaction. The obtained Q moment, |Q_exp(31Al)| = 112(32)emb, are in agreement with conventional shell model calculations within the sd valence space. Previous result on the magnetic moment also supports the validity of the sd model in this isotope, and thus it is concluded that 31Al is located outside of the island of inversion.Comment: 5 page

Transforming growth factor-β1 stimulates collagen matrix remodeling through increased adhesive and contractive potential by human renal fibroblasts

AbstractRenal tubulointerstitial fibrosis is the common final pathway leading to end-stage renal failure. Tubulointerstitial fibrosis is characterized by fibroblast proliferation and excessive matrix accumulation. Transforming growth factor-β1 (TGF-β1) has been implicated in the development of renal fibrosis accompanied by α-smooth muscle actin (α-SMA) expression in renal fibroblasts. To investigate the molecular and cellular mechanisms involved in tubulointerstitial fibrosis, we examined the effect of TGF-β1 on collagen type I (collagen) gel contraction, an in vitro model of scar collagen remodeling. TGF-β1 enhanced collagen gel contraction by human renal fibroblasts in a dose- and time-dependent manner. Function-blocking anti-α1 or anti-α2 integrin subunit antibodies significantly suppressed TGF-β1-stimulated collagen gel contraction. Scanning electron microscopy showed that TGF-β1 enhanced the formation of the collagen fibrils by cell attachment to collagen via α1β1 and α2β1 integrins. Flow cytometry and cell adhesion analyses revealed that the stimulation of renal fibroblasts with TGF-β1 enhanced cell adhesion to collagen via the increased expression of α1 and α2 integrin subunits within collagen gels. Fibroblast migration to collagen was not up-regulated by TGF-β1. Furthermore, TGF-β1 increased the expression of a putative contractile protein, α-SMA, by human renal fibroblasts in collagen gels. These results suggest that TGF-β1 stimulates fibroblast–collagen matrix remodeling by increasing both integrin-mediated cell attachment to collagen and α-SMA expression, thereby contributing to pathological tubulointerstitial collagen matrix reorganization in renal fibrosis

Integrating chytrid fungal parasites into plankton ecology: research gaps and needs

Chytridiomycota, often referred to as chytrids, can be virulent parasites with the potential to inflict mass mortalities on hosts, causing e.g. changes in phytoplankton size distributions and succession, and the delay or suppression of bloom events. Molecular environmental surveys have revealed an unexpectedly large diversity of chytrids across a wide range of aquatic ecosystems worldwide. As a result, scientific interest towards fungal parasites of phytoplankton has been gaining momentum in the past few years. Yet, we still know little about the ecology of chytrids, their life cycles, phylogeny, host specificity and range. Information on the contribution of chytrids to trophic interactions, as well as co‐evolutionary feedbacks of fungal parasitism on host populations is also limited. This paper synthesizes ideas stressing the multifaceted biological relevance of phytoplankton chytridiomycosis, resulting from discussions among an international team of chytrid researchers. It presents our view on the most pressing research needs for promoting the integration of chytrid fungi into aquatic ecology

Streptococcus mutans strains harboring collagen-binding adhesin

http://jdr.iadrjournals.org/cgi/content/full/83/7/53

Regular Spectra and Universal Directionality of Emitted Radiation from a Quadrupolar Deformed Microcavity

We have investigated quasi-eigenmodes of a quadrupolar deformed microcavity by extensive numerical calculations. The spectral structure is found to be quite regular, which can be explained on the basis of the fact that the microcavity is an open system. The far-field emission directions of the modes show unexpected similarity irrespective of their distinct shapes in phase space. This universal directionality is ascribed to the influence from the geometry of the unstable manifolds in the corresponding ray dynamics.Comment: 10 pages 11 figure

Seasonality of parasitic and saprotrophic zoosporic fungi: linking sequence data to ecological traits

Zoosporic fungi of the phylum Chytridiomycota (chytrids) regularly dominate pelagic fungal communities in freshwater and marine environments. Their lifestyles range from obligate parasites to saprophytes. Yet, linking the scarce available sequence data to specific ecological traits or their host ranges constitutes currently a major challenge. We combined 28 S rRNA gene amplicon sequencing with targeted isolation and sequencing approaches, along with cross-infection assays and analysis of chytrid infection prevalence to obtain new insights into chytrid diversity, ecology, and seasonal dynamics in a temperate lake. Parasitic phytoplankton-chytrid and saprotrophic pollen-chytrid interactions made up the majority of zoosporic fungal reads. We explicitly demonstrate the recurrent dominance of parasitic chytrids during frequent diatom blooms and saprotrophic chytrids during pollen rains. Distinct temporal dynamics of diatom-specific parasitic clades suggest mechanisms of coexistence based on niche differentiation and competitive strategies. The molecular and ecological information on chytrids generated in this study will aid further exploration of their spatial and temporal distribution patterns worldwide. To fully exploit the power of environmental sequencing for studies on chytrid ecology and evolution, we emphasize the need to intensify current isolation efforts of chytrids and integrate taxonomic and autecological data into long-term studies and experiments.Alliance of German Science Organizations///AlemaniaUCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de Biologí

Imprinting disorders: a group of congenital disorders with overlapping patterns of molecular changes affecting imprinted loci.

Congenital imprinting disorders (IDs) are characterised by molecular changes affecting imprinted chromosomal regions and genes, i.e. genes that are expressed in a parent-of-origin specific manner. Recent years have seen a great expansion in the range of alterations in regulation, dosage or DNA sequence shown to disturb imprinted gene expression, and the correspondingly broad range of resultant clinical syndromes. At the same time, however, it has become clear that this diversity of IDs has common underlying principles, not only in shared molecular mechanisms, but also in interrelated clinical impacts upon growth, development and metabolism. Thus, detailed and systematic analysis of IDs can not only identify unifying principles of molecular epigenetics in health and disease, but also support personalisation of diagnosis and management for individual patients and families.All authors are members of the EUCID.net network, funded by COST (BM1208). TE is funded by the German Ministry of research and education (01GM1513B). GPdN is funded by I3SNS Program of the Spanish Ministry of Health (CP03/0064; SIVI 1395/09), Instituto de Salud Carlos III (PI13/00467) and Basque Department of Health (GV2014/111017).This is the final version of the article. It first appeared from BioMed Central via http://dx.doi.org/10.1186/s13148-015-0143-