11,198 research outputs found
Evolution and diversity of secretome genes in the apicomplexan parasite Theileria annulata
<b>BACKGROUND</b>: Little is known about how apicomplexan parasites have evolved to infect different host species and cell types. Theileria annulata and Theileria parva invade and transform bovine leukocytes but each species favours a different host cell lineage. Parasite-encoded proteins secreted from the intracellular macroschizont stage within the leukocyte represent a critical interface between host and pathogen systems. Genome sequencing has revealed that several Theileria-specific gene families encoding secreted proteins are positively selected at the inter-species level, indicating diversification between the species. We extend this analysis to the intra-species level, focusing on allelic diversity of two major secretome families. These families represent a well-characterised group of genes implicated in control of the host cell phenotype and a gene family of unknown function. To gain further insight into their evolution and function, this study investigates whether representative genes of these two families are diversifying or constrained within the T. annulata population. <b>RESULTS</b>: Strong evidence is provided that the sub-telomerically encoded SVSP family and the host-nucleus targeted TashAT family have evolved under contrasting pressures within natural T. annulata populations. SVSP genes were found to possess atypical codon usage and be evolving neutrally, with high levels of nucleotide substitutions and multiple indels. No evidence of geographical sub-structuring of allelic sequences was found. In contrast, TashAT family genes, implicated in control of host cell gene expression, are strongly conserved at the protein level and geographically sub-structured allelic sequences were identified among Tunisian and Turkish isolates. Although different copy numbers of DNA binding motifs were identified in alleles of TashAT proteins, motif periodicity was strongly maintained, implying conserved functional activity of these sites. <b>CONCLUSIONS</b>: This analysis provides evidence that two distinct secretome genes families have evolved under contrasting selective pressures. The data supports current hypotheses regarding the biological role of TashAT family proteins in the management of host cell phenotype that may have evolved to allow adaptation of T. annulata to a specific host cell lineage. We provide new evidence of extensive allelic diversity in representative members of the enigmatic SVSP gene family, which supports a putative role for the encoded products in subversion of the host immune response
Development and Composition of the Warty Layer in Balsam Fir. I. Development
The deposition and ultrastructure of the warty layer in developing tracheids of balsam fir [Abies balsamea (L.) Mill.] were studied by means of transmission electron microscopy. The wart structure gradually was developed external to the plasma membrane after secondary wall deposition and the greater part of lignification were complete. Warts were synthesized first in the cell corners and pit cavities and then on the remainder of the cell walls. No cytoplasmic organelle was found to be associated specifically with wart formation. After the warty layer was elaborated, the cytoplasm disappeared from the cell, leaving no discernible trace of disorganized residue. The bulk of the wart structure exhibited staining properties similar to those of lignin. However, the basal portions of individual warts were sometimes less darkly stained than the outer portions, indicating possible heterogeneous composition
Development and Composition of the Warty Layer in Balsam Fir. II. Composition
From its response to various chemical, physical, fungal, and enzymatic treatments, it was concluded that the warty layer in balsam fir consisted largely of a ligninlike material that was visibly more resistant to extraction than a large fraction of other lignin in the fiber cell wall. Since the warts were the cell-wall component most accessible to the treatment solutions, it is probable that the material in the warty layer was more concentrated and condensed than lignin in other parts of the wall. Vacuum drying at 105 C appeared to condense the wart structure still further, making it even more resistant to most treatments. Gel filtration indicated that the warty layer was extracted as a high molecular weight material by certain treatments. The warty layer may act as a barrier that slows the penetration of liquids into the cell wall and thereby may cause different rates of delignification for different wood species. The basal component of individual warts and some of the accompanying encrustant on the inner surface of the cell wall were found to contain an amorphous carbohydrate, probably a pentosan or a pectic substance. Attempts at physical isolation of the warts were largely unsuccessful
Early Ceramics in Anatolia: Implications for the Production and Use of the Earliest Pottery. The Evidence from Boncuklu Höyük
Fragments of possible fired clay found at Boncuklu Höyük, central Turkey, appear to derive from rudimentary vessels, despite the later ninth- and early eighth-millennium cal. bc and thus ‘Aceramic’ dates for the site. This paper will examine the evidence for such fired clay vessels at Boncuklu and consider their implications as examples of some of the earliest pottery in Anatolia. The discussion will examine contextual evidence for the role of these fragments and consider their relative rarity at the site and the implications for the marked widespread adoption of pottery in southwest Asia c. 7000–6700 cal. bc
A serological investigation of caseous lymphadenitis in four flocks of sheep
A double antibody sandwich ELISA developed by ID-DLO, Lelystad to detect Corynebocterium pseudotuberculosis infection was used on 329 sheep from four pedigree Suffolk flocks in which clinical cases of caseous lymphadenitis (CLA) had occurred. At subsequent necropsy, typical CLA lesions were seen in 133 sheep, and the diagnosis was confirmed on culture. Lesions were most commonly seen in lungs (n = 46), parotid lymph nodes (n = 44), prescapular lymph nodes (n = 38) and mediastinal lymph nodes (n = 31). The sensitivity of the ELISA test for detecting culture-positive sheep was 0.88, while the specificity of the test was 0.55. The antibody ELISA detected 87.5 per cent of sheep that had CLA lesions restricted to internal organs only. It was concluded that the ELISA test has a valuable role in detecting sheep with both clinical and subclinical CLA
DynPeak : An algorithm for pulse detection and frequency analysis in hormonal time series
The endocrine control of the reproductive function is often studied from the
analysis of luteinizing hormone (LH) pulsatile secretion by the pituitary
gland. Whereas measurements in the cavernous sinus cumulate anatomical and
technical difficulties, LH levels can be easily assessed from jugular blood.
However, plasma levels result from a convolution process due to clearance
effects when LH enters the general circulation. Simultaneous measurements
comparing LH levels in the cavernous sinus and jugular blood have revealed
clear differences in the pulse shape, the amplitude and the baseline. Besides,
experimental sampling occurs at a relatively low frequency (typically every 10
min) with respect to LH highest frequency release (one pulse per hour) and the
resulting LH measurements are noised by both experimental and assay errors. As
a result, the pattern of plasma LH may be not so clearly pulsatile. Yet,
reliable information on the InterPulse Intervals (IPI) is a prerequisite to
study precisely the steroid feedback exerted on the pituitary level. Hence,
there is a real need for robust IPI detection algorithms. In this article, we
present an algorithm for the monitoring of LH pulse frequency, basing ourselves
both on the available endocrinological knowledge on LH pulse (shape and
duration with respect to the frequency regime) and synthetic LH data generated
by a simple model. We make use of synthetic data to make clear some basic
notions underlying our algorithmic choices. We focus on explaining how the
process of sampling affects drastically the original pattern of secretion, and
especially the amplitude of the detectable pulses. We then describe the
algorithm in details and perform it on different sets of both synthetic and
experimental LH time series. We further comment on how to diagnose possible
outliers from the series of IPIs which is the main output of the algorithm.Comment: Nombre de pages : 35 ; Nombre de figures : 16 ; Nombre de tableaux :
SARS-CoV-2 antibodies detected in human breast milk postvaccination
Importance The SARS-CoV-2 pandemic has infected over a hundred million people worldwide, with almost 2.5 million deaths at the date of this publication. In the United States, Pfizer-BioNTech and Moderna vaccines were first administered to the public starting in December 2020, and no lactating women were included in the initial trials of safety/efficacy. Research on SARS-CoV-2 vaccination in lactating women and the potential transmission of passive immunity to the infant through breast milk is needed to guide patients, clinicians and policy makers during the worldwide effort to curb the spread of this virus. Objective To determine whether SARS-CoV-2 specific immunoglobins are found in breast milk post-vaccination, and to characterize the time course and types of immunoglobulins present. Design Prospective cohort study Setting Providence Portland Medical Center, Oregon, USA Participants Six lactating women who planned to receive both doses of the Pfizer-BioNTech or Moderna vaccine between December 2020 and January 2021. Breast milk samples were collected pre-vaccination and at 11 additional timepoints, with last sample at 14 days post 2nd dose of vaccine. Exposure Two doses of Pfizer-BioNTech or Moderna SARS-CoV-2 vaccine. Main Outcome(s) and Measure(s) Levels of SARS-CoV-2 specific IgA and IgG immunoglobulins in breast milk. Results In this cohort of 6 lactating women who received 2 doses of SARS-CoV-2 vaccine, we observed significantly elevated levels of SARS-CoV-2 specific IgG and IgA antibodies in breast milk beginning at Day 7 after the initial vaccine dose, with an IgG-dominant response. Conclusions and Relevance We are the first to show that maternal vaccination results in SARS-CoV-2 specific immunoglobulins in breast milk that may be protective for infants. Competing Interest Statement The authors have declared no competing interest. Funding Statement This work was supported by generous grants from Nancy Lematta (BAF) and the Chiles Foundation (BAF)
Entrepreneurship in a Transition Economy: An Examination of Venture Creation in Hungary
This study examines entrepreneurs and new ventures in a transition economy, Hungary, and identifies what variables distinguish between Hungarian entrepreneurs and their new ventures in the pre-1988 transition period from that which followed. The variables that discriminate most strongly are their business strategies. The newer firms had a concentration strategy while the older firms had a new product development strategy. Other variables that discriminated between the groups include reacting to the political environment, satisfaction with firm performance, encouragement from investors, recent investment in building improvement, and family history of entrepreneurship. The newer entrepreneurs had more family role models of entrepreneurship
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