Interannual patterns of avian diseases in wild New Zealand avifauna near conservation areas

The past few years have seen a noticeable increase in the emergence of infectious diseases in wildlife, especially vector-borne diseases, presenting a challenge for the conservation of endangered species. One such vector-borne disease, avian malaria (Plasmodium spp.) is on the rise in New Zealand avifauna, threatening bird populations that are among the most extinction-prone in the world. Furthermore, recent reports have outlined an increase in deaths of native iconic bird species specifically due to this disease. In order to help manage breakouts of this pathogen at a local scale, we need a better understanding of potential drivers of the emergence of avian malaria in wild New Zealand avifauna. Here, we set to test the role of climatic drivers in synchronizing contacts between avian hosts and vectors, assess the temporal stability of transmission dynamics between years, and determine the role of introduced species in causing spill-over of this pathogen towards native species. Our study focused on three sites that were sampled regularly during two consecutive years in the austral summer, each site being adjacent to a breeding colony of Yellow-eyed penguins (Megadyptes antipodes). Our results reveal an overall temporal stability of avian malaria incidence patterns, with a decrease in infection throughout the austral summer for both sampled years. Moreover, we highlight a phylogenetic signal among sampled bird species, with introduced species being more heavily infected by avian malaria than their native counterparts. In contrast, we found no effect of the two climatic drivers investigated, temperature and rainfall, on mosquito abundance. Our results suggest a strong effect of alien species acting as reservoirs for diseases spilling-over towards immunologically naïve species, and provide conservation managers with a critical timeframe to control avian malaria breakouts.     

Refractive index measurement in viable cells using quantitative phase-amplitude microscopy and confocal microscopy.

BACKGROUND: The refractive index (RI) of cellular material provides fundamental biophysical information about the composition and organizational structure of cells. Efforts to describe the refractive properties of cells have been significantly impeded by the experimental difficulties encountered in measuring viable cell RI. In this report we describe a procedure for the application of quantitative phase microscopy in conjunction with confocal microscopy to measure the RI of a cultured muscle cell specimen. METHODS: The experimental strategy involved calculation of cell thickness by using confocal optical sectioning procedures, construction of a phase map of the same cell using quantitative phase microscopy, and selection of cellular regions of interest to solve for the cell RI. RESULTS: Mean cell thickness and phase values for six cell regions (five cytoplasmic and one nuclear) were determined. The average refractive index calculated for cytoplasmic and nuclear regions was 1.360 +/- 0.004. The uncertainty in the final RI value represents the technique measurement error. CONCLUSIONS: The methodology we describe for viable cell RI measurement with this prototype cell has broad generic application in the study of cell growth and functional responses. The RI value we report may be used in optical analyses of cultured cell structure and morphology.     

Production of potato monohaploids (2n=x=12) through prickle pollination

Summary Data are presented on the potential of gynogenesis for the production of monohaploids and on factors affecting their frequency and relative vigour. Diploid Solanum tuberosum L. and S. tuberosumxS. phureja Juz et Buk hybrids were used as maternal parents and selected S. phureja clones as prickle pollinators with embryo-spot and nodal band as dominant seed and plant marker. About 2 million seeds were screened for absence of embryo-spot. After raising plants from phenotypically spotless seeds, further screening for absence of nodal bands and for ploidy level was carried out. Finally more than 500 monohaploid plants from three genetically different groups of maternal parents were obtained. Frequency and vigour of the monohaploids were clearly dependent on their maternal genotypes. The data also indicated an effect of the pollinator genotype, the physiological stage of the maternal plant and the environment on monohaploid frequency. On the basis of these results the possibility of breeding for a higher monohaploid production rate and for more stable and vigorous monohaploids is discussed. Furthermore, gynogenesis and androgenesis are compared. It is suggested that both should be used in order to obtain monohaploids from sufficiently various diploid breeding material.     

Intragenic NF1 deletions in sinonasal mucosal malignant melanoma

Mucosal malignant melanoma (MMM) is a rare and aggressive tumor. Despite effective local therapies, tumor recurrence and metastasis remain frequent. The genetics of MMM remain incompletely understood. This study is aimed to identify actionable genetic alterations by next-generation sequencing. Fifteen MMM samples were analyzed by next-generation and Sanger sequencing. Gene copy number alterations were analyzed by MLPA. Mutation status was correlated with pERK, pAKT, and Ki-67 expression and follow-up data. Inactivating mutations and intragenic deletions in neurofibromatosis type-1 (NF1) were identified in 3 and 2 cases, respectively, (in total 5/15, 33%) and activating mutations in NRAS and KRAS (3/15, 20%) cases. Other mutated genes included CDKN2A, APC, ATM, MITF, FGFR1, and FGFR2. BRAF and KIT mutations were not observed. Cases with NF1 alterations tended to have worse overall survival. The mutational status was not associated with pERK, pAKT, or Ki-67 immunostaining. MMM carries frequent gene mutations activating the MAPK pathway, similar to cutaneous melanoma. In contrast, NF1 is the most frequently affected gene. Intragenic NF1 deletions have not been described before and may go undetected by sequencing studies. This finding is clinically relevant as NF1-mutated melanomas have worse survival and could benefit from therapy with immune checkpoint and MEK inhibitors.     

An Alternative Mode of Early Land Plant Colonization by Putative Endomycorrhizal Fungi

Rhizomatous axes of Nothia aphylla, a land plant from the 400-myr-old Rhynie chert, host a fungus that closely resembles Glomites rhyniensis (Glomeromycota), the endomycorrhizal fungus of the Rhynie chert plant Aglaophyton major. However, G. rhyniensis is an intercellular endophyte that becomes intracellular exclusively within a well-defined region of the cortex, while the fungus in N. aphylla initially is intracellular but later becomes intercellular in the cortex. We hypothesize that N. aphylla displays an alternative mode of colonization by endomycorrhizal fungi, perhaps related to the peculiar internal anatomy of the lower portion of the rhizomatous axis, in which the radial arrangement of cells, along with the virtual absence of intercellular spaces, provides no intercellular infection pathway into the cortex.Key Words: Aglaophyton major, endomycorrhiza, Glomeromycota, Nothia aphylla, Early Devonian, Rhynie chertThe Early Devonian (c. 400 Ma) Rhynie chert is an in situ silicified hot springs environment that has become significant in our understanding of the complexity of life in early terrestrial ecosystems because of the extraordinary preservation of plants, animals, and microorganisms.¹ Moreover, various associations and interactions between different organisms can be directly examined,² including the earliest fossil examples of arbuscular endomycorrhizae.^3,4 The Rhynie chert land plant Aglaophyton major is characterized by arching, stomatiferous prostrate axes that grow along the substrate surface, and form rhizoid-bearing bulges, usually around stomata, upon contact with the substrate. Extramatrical hyphae of the mycorrhizal fungal enter the axes through these stomata, and spread out through the intercellular system of the hypodermis and cortex, subsequently penetrating individual cells within a well-defined region of the cortex (i.e., the mycorrhizal arbuscule-zone) to form arbuscules.⁴A recently published study⁵ reports on three fungal endophytes that (co-)occur in the Rhynie chert plant Nothia aphylla. This plant consists of upright aerial axes arising from a system of non-stomatiferous, subterranean rhizomatous axes characterized by a prominent ventral rhizoidal ridge.^6,7 The rhizoidal ridge, which is unique among Rhynie chert land plants, consists of a rhizoid-bearing epidermis, a multi-layered hypodermis, files of parenchyma cells that connect to the stele, and extra-stelar conducting elements (Fig. 1A); intercellular spaces are virtually absent.Open in a separate windowFigure 1Nothia aphylla from the Lower Devonian Rhynie chert. (A) Ventral portion of a rhizomatous axis with rhizoidal ridge (cross section); bar = 250 µm. (B) Fungal hypha [arrows] entering the axis through a rhizoid; bar = 30 µm. (C) Sheathed intracellular hyphae [arrows] in hypodermal cells (transverse section); bar = 20 µm. (D) Intercellular hyphae and vesicles in the cortex (longitudinal section); bar scale = 50 µm. (E) Hyphae, vesicles and a thick-walled spore in the cortex (longitudinal section); bar = 100 µm. All images from the original paper; reproduced with permission.One of the fungal endophytes in N. aphylla closely resembles Glomites rhyniensis (Glomeromycota), the endomycorrhizal fungus of A. major.⁴ In N. aphylla, this fungus occurs as an intracellular endophyte in rhizoids and tissues of the rhizoidal ridge. Moreover, it is abundant in the intercellular system of the cortex of both prostrate and proximal portions of aerial axes. The fungus enters the axes through rhizoids (Fig. 1B). Once in the hypodermis, hyphae become sheathed by cell wall material (Fig. 1C). In the cortex, the fungus produces intercellular vesicles (Fig. 1D) and thick-walled spores (Fig. 1E). Based on the presence of vesicles that are similar to those of G. rhyniensis, and spores like those in extant Glomeromycota, we hypothesize that this fungus is an endomycorrhizal member of the Glomeromycota; however, arbuscules have not been observed to date.If this interpretation is accurate, N. aphylla displays an alternative pattern of colonization by endomycorrhizal fungi. Although the morphology of the fungus and distribution in N. aphylla correspond to that of G. rhyniensis in A. major, the infection pathway is distinctly different. While G. rhyniensis is an intercellular endophyte that penetrates individual cells exclusively within the mycorrhizal arbuscule-zone,⁴ the fungus of N. aphylla enters the plant as an intracellular endophyte, and remains intracellular until it reaches the cortex. The host plant apparently does not respond to the invading fungus because infected rhizoids are not altered morphologically. Once in the hypodermis, however, hyphae become separated from the host cell protoplast. This feature suggests a shift from (i) uncontrolled intracellular occurrence of the fungus in the rhizoids, to (ii) controlled intracellular occurrence in the rhizoidal ridge, to (iii) intercellular occurrence in the cortex.The fact that the rhizomatous axes of N. aphylla are subterranean, along with the peculiar internal anatomy of the rhizoidal ridge, may have provided the selective pressure for an alternative mode of colonization by endomycorrhizal fungi. The fungus probably enters the plant through rhizoids because the axes are non-stomatiferous. Moreover, the morphology and radial arrangement of cells in the rhizoidal ridge, along with the virtual absence of intercellular spaces, perhaps does not provide an intercellular infection pathway into the cortex. We speculate that N. aphylla tolerated intracellular penetration in the rhizoids and within the tissues of the rhizoidal ridge in order to become inoculated. Tolerating (or even facilitating) intracellular penetration within a limited area of the axis may simultaneously have provided the plant with a means of recognizing and subsequently distinguishing the endomycorrhizal fungus from potentially harmful parasites (e.g., by surface features of the hyphae or chemical signals). Once recognized, the endomycorrhizal fungi become sheathed and “guided” through the ridge without being able to extract nutrients from the host, and into the cortex where intracellular penetration is not longer possible. The parasites, once recognized, are confined in the tissues of the rhizoidal ridge by specific or unspecific host responses, e.g., secondarily thickened cell walls.⁵ Conversely, if the endomycorrhizal fungus entered the plant through surface openings, and spread out exclusively through the intercellular system, the mechanisms that might confine simultaneous parasite infections were probably much more limited.Endomycorrhizal relationships are believed to have evolved from parasitic interactions.⁸ It has been postulated that modern enodomycorrhizal fungi in some way control parasites because both compete for the same resources.⁹ It may be that, during the evolution of fungal endophytism, the initial benefits of mycorrhizae included protection of the host from pathogenic fungi.¹⁰ Nothia aphylla from the Lower Devonian Rhynie chert adds support to this hypothesis, and may demonstrate that more than a single pattern of colonization by endomycorrhizal fungi occurred during the early evolution of land plants.     

A Novel Inhibitor of Amyloid β (Aβ) Peptide Aggregation: FROM HIGH THROUGHPUT SCREENING TO EFFICACY IN AN ANIMAL MODEL OF ALZHEIMER DISEASE*

Compelling evidence indicates that aggregation of the amyloid β (Aβ) peptide is a major underlying molecular culprit in Alzheimer disease. Specifically, soluble oligomers of the 42-residue peptide (Aβ42) lead to a series of events that cause cellular dysfunction and neuronal death. Therefore, inhibiting Aβ42 aggregation may be an effective strategy for the prevention and/or treatment of disease. We describe the implementation of a high throughput screen for inhibitors of Aβ42 aggregation on a collection of 65,000 small molecules. Among several novel inhibitors isolated by the screen, compound D737 was most effective in inhibiting Aβ42 aggregation and reducing Aβ42-induced toxicity in cell culture. The protective activity of D737 was most significant in reducing the toxicity of high molecular weight oligomers of Aβ42. The ability of D737 to prevent Aβ42 aggregation protects against cellular dysfunction and reduces the production/accumulation of reactive oxygen species. Most importantly, treatment with D737 increases the life span and locomotive ability of flies in a Drosophila melanogaster model of Alzheimer disease.     

Deadlock, a novel protein of Drosophila, is required for germline maintenance, fusome morphogenesis and axial patterning in oogenesis and associates with centrosomes in the early embryo

The deadlock gene is required for a number of key developmental events in Drosophila oogenesis. Females homozygous for mutations in the deadlock gene lay few eggs and those exhibit severe patterning defects along both the anterior-posterior and dorsal-ventral axis. In this study, we analyzed eggs and ovaries from deadlock mutants and determined that deadlock is required for germline maintenance, stability of mitotic spindles, localization of patterning determinants, oocyte growth and fusome biogenesis in males and females. Deadlock encodes a novel protein which colocalizes with the oocyte nucleus at midstages of oogenesis and with the centrosomes of early embryos. Our genetic and immunohistological experiments point to a role for Deadlock in microtubule function during oogenesis.