280 research outputs found
Maternal serum levels of pregnancy—associated murine-l (PAMP—l) during pregnancy in the rabbit
An ELISA was developed to measure for the first time serum levels of Pregnancy—Associated Murine Protein- 1 (PAMP—l) throughout pregnancy in the rabbit. In rodents serum levels of PAMP-l are regulated by growth hormone Unlike the pregnancy-assoeiated rise in serum levels in pregnant mice and rats, PAMP-l did not increase significantly during pregnancy in the rabbit
Revealing natural relationships among arbuscular mycorrhizal fungi: culture line BEG47 represents Diversispora epigaea, not Glomus versiforme
Background: Understanding the mechanisms underlying biological phenomena, such as evolutionarily conservative trait inheritance, is predicated on knowledge of the natural relationships among organisms. However, despite their enormous ecological significance, many of the ubiquitous soil inhabiting and plant symbiotic arbuscular mycorrhizal fungi (AMF, phylum Glomeromycota) are incorrectly classified.
Methodology/Principal Findings:
Here, we focused on a frequently used model AMF registered as culture BEG47. This fungus is a descendent of the ex-type culture-lineage of Glomus epigaeum, which in 1983 was synonymised with Glomus versiforme. It has since then been used as ‘G. versiforme BEG47’. We show by morphological comparisons, based on type material, collected 1860–61, of G. versiforme and on type material and living ex-type cultures of G. epigaeum, that these two AMF species cannot be conspecific, and by molecular phylogenetics that BEG47 is a member of the genus Diversispora.
Conclusions: This study highlights that experimental works published during the last >25 years on an AMF named ‘G. versiforme’ or ‘BEG47’ refer to D. epigaea, a species that is actually evolutionarily separated by hundreds of millions of years from all members of the genera in the Glomerales and thus from most other commonly used AMF ‘laboratory strains’. Detailed redescriptions substantiate the renaming of G. epigaeum (BEG47) as D. epigaea, positioning it systematically in the order Diversisporales, thus enabling an evolutionary understanding of genetical, physiological, and ecological traits, relative to those of other AMF. Diversispora epigaea is widely cultured as a laboratory strain of AMF, whereas G. versiforme appears not to have been cultured nor found in the field since its original description
The tyrosine phosphatase CD148 is an essential positive regulator of platelet activation and thrombosis
Platelets play a fundamental role in hemostasis and thrombosis. They are also involved in pathologic conditions resulting from blocked blood vessels, including myocardial infarction and ischemic stroke. Platelet adhesion, activation, and aggregation at sites of vascular injury are regulated by a diverse repertoire of tyrosine kinase–linked and G protein–coupled receptors. Src family kinases (SFKs) play a central role in initiating and propagating signaling from several platelet surface receptors; however, the underlying mechanism of how SFK activity is regulated in platelets remains unclear. CD148 is the only receptor-like protein tyrosine phosphatase identified in platelets to date. In the present study, we show that mutant mice lacking CD148 exhibited a bleeding tendency and defective arterial thrombosis. Basal SFK activity was found to be markedly reduced in CD148-deficient platelets, resulting in a global hyporesponsiveness to agonists that signal through SFKs, including collagen and fibrinogen. G protein–coupled receptor responses to thrombin and other agonists were also marginally reduced. These results highlight CD148 as a global regulator of platelet activation and a novel antithrombotic drug targe
Redefinition of Aureobasidium pullulans and its varieties
Using media with low water activity, a large numbers of aureobasidium-like
black yeasts were isolated from glacial and subglacial ice of three
polythermal glaciers from the coastal Arctic environment of Kongsfjorden
(Svalbard, Spitsbergen), as well as from adjacent sea water, sea ice and
glacial meltwaters. To characterise the genetic variability of
Aureobasidium pullulans strains originating from the Arctic and
strains originating pan-globally, a multilocus molecular analysis was
performed, through rDNA (internal transcribed spacers, partial 28 S rDNA), and
partial introns and exons of genes encoding β-tubulin (TUB),
translation elongation factor (EF1α) and elongase
(ELO). Two globally ubiquitous varieties were distinguished: var.
pullulans, occurring particularly in slightly osmotic substrates and
in the phyllosphere; and var. melanogenum, mainly isolated from
watery habitats. Both varieties were commonly isolated from the sampled Arctic
habitats. However, some aureobasidium-like strains from subglacial ice from
three different glaciers in Kongsfjorden (Svalbard, Spitsbergen), appeared to
represent a new variety of A. pullulans. A strain from dolomitic
marble in Namibia was found to belong to yet another variety. No molecular
support has as yet been found for the previously described var.
aubasidani. A partial elongase-encoding gene was successfully used as
a phylogenetic marker at the (infra-)specific level
Prevention of Diabetes in NOD Mice by Repeated Exposures to a Contact Allergen Inducing a Sub-Clinical Dermatitis
BACKGROUND: Type 1 diabetes is an autoimmune disease, while allergic contact dermatitis although immune mediated, is considered an exposure driven disease that develops due to epicutaneous contact with reactive low-molecular chemicals. The objective of the present study was to experimentally study the effect of contact allergens on the development of diabetes in NOD mice. As the link between contact allergy and diabetes is yet unexplained we also examined the effect of provocation with allergens on Natural Killer T (NKT) cells, since involvement of NKT cells could suggest an innate connection between the two diseases. METHOD: NOD mice 4 weeks of age were exposed, on the ears, to two allergens, p-phenylenediamine and 2,4-dinitrochlorobenzene respectively, to investigate the diabetes development. The mice were followed for a maximum of 32 weeks, and they were either repeatedly exposed to the allergens or only sensitized a week after arrival. The stimulation of NKT cells by the two allergens were additionally studied in C57BL/6 mice. The mice were sensitized and two weeks later provocated with the allergens. The mice were subsequently euthanized at different time points after the provocation. RESULTS: It was found that repeated application of p-phenylenediamine reduced the incidence of diabetes compared to application with water (47% vs. 93%, P = 0.004). Moreover it was shown that in C57BL/6 mice both allergens resulted in a slight increment in the quantity of NKT cells in the liver. Application of the allergens at the same time resulted in an increased number of NKT cells in the draining auricular lymph node, and the increase appeared to be somewhat allergen specific as the accumulation was stronger for p-phenylenediamine. CONCLUSION: The study showed that repeated topical application on the ears with a contact allergen could prevent the development of diabetes in NOD mice. The contact allergens gave a non-visible, sub-clinical dermatitis on the application site. The preventive effect on diabetes may be due to stimulation of peripheral NKT cells, as shown for provocation with p-phenylenediamine in the C57BL/6 mouse. This epicutaneous procedure may lead to new strategies in prevention of type 1 diabetes in humans
Patterns of Early Gut Colonization Shape Future Immune Responses of the Host
The most important trigger for immune system development is the exposure to microbial components immediately after birth. Moreover, targeted manipulation of the microbiota can be used to change host susceptibility to immune-mediated diseases. Our aim was to analyze how differences in early gut colonization patterns change the composition of the resident microbiota and future immune system reactivity. Germ-free (GF) mice were either inoculated by single oral gavage of caecal content or let colonized by co-housing with specific pathogen-free (SPF) mice at different time points in the postnatal period. The microbiota composition was analyzed by denaturing gradient gel electrophoresis for 16S rRNA gene followed by principal component analysis. Furthermore, immune functions and cytokine concentrations were analyzed using flow cytometry, ELISA or multiplex bead assay. We found that a single oral inoculation of GF mice at three weeks of age permanently changed the gut microbiota composition, which was not possible to achieve at one week of age. Interestingly, the ex-GF mice inoculated at three weeks of age were also the only mice with an increased pro-inflammatory immune response. In contrast, the composition of the gut microbiota of ex-GF mice that were co-housed with SPF mice at different time points was similar to the gut microbiota in the barrier maintained SPF mice. The existence of a short GF postnatal period permanently changed levels of systemic regulatory T cells, NK and NKT cells, and cytokine production. In conclusion, a time window exists that enables the artificial colonization of GF mice by a single oral dose of caecal content, which may modify the future immune phenotype of the host. Moreover, delayed microbial colonization of the gut causes permanent changes in the immune system
Delimitation of Neonectria and Cylindrocarpon (Nectriaceae, Hypocreales, Ascomycota) and related genera with Cylindrocarpon-like anamorphs
Neonectria is a cosmopolitan genus and it is, in part, defined by
its link to the anamorph genus Cylindrocarpon. Neonectria
has been divided into informal groups on the basis of combined morphology of
anamorph and teleomorph. Previously, Cylindrocarpon was divided into
four groups defined by presence or absence of microconidia and chlamydospores.
Molecular phylogenetic analyses have indicated that Neonectria
sensu stricto and Cylindrocarpon sensu stricto are
phylogenetically congeneric. In addition, morphological and molecular data
accumulated over several years have indicated that Neonectria sensu
lato and Cylindrocarpon sensu lato do not form a
monophyletic group and that the respective informal groups may represent
distinct genera. In the present work, a multilocus analysis (act,
ITS, LSU, rpb1, tef1, tub) was applied to representatives of
the informal groups to determine their level of phylogenetic support as a
first step towards taxonomic revision of Neonectria sensu
lato. Results show five distinct highly supported clades that correspond
to some extent with the informal Neonectria and
Cylindrocarpon groups that are here recognised as genera: (1) N.
coccinea-group and Cylindrocarpon groups 1 & 4
(Neonectria/Cylindrocarpon sensu stricto); (2) N.
rugulosa-group (Rugonectria gen. nov.); (3) N.
mammoidea/N. veuillotiana-groups and Cylindrocarpon group 2
(Thelonectria gen. nov.); (4) N. radicicola-group and
Cylindrocarpon group 3 (Ilyonectria gen. nov.); and (5)
anamorph genus Campylocarpon. Characteristics of the anamorphs and
teleomorphs correlate with the five genera, three of which are newly
described. New combinations are made for species where their classification is
confirmed by phylogenetic data
Phylogeny and ecology of the ubiquitous saprobe Cladosporium sphaerospermum, with descriptions of seven new species from hypersaline environments
Saprobic Cladosporium isolates morphologically similar to C.
sphaerospermum are phylogenetically analysed on the basis of DNA
sequences of the ribosomal RNA gene cluster, including the internal
transcribed spacer regions ITS1 and ITS2, the 5.8S rDNA (ITS) and the small
subunit (SSU) rDNA as well as β-tubulin and actin gene introns and exons.
Most of the C. sphaerospermum-like species show halotolerance as a
recurrent feature. Cladosporium sphaerospermum, which is
characterised by almost globose conidia, is redefined on the basis of its
ex-neotype culture. Cladosporium dominicanum, C.
psychrotolerans, C. velox, C. spinulosum and C.
halotolerans, all with globoid conidia, are newly described on the basis
of phylogenetic analyses and cryptic morphological and physiological
characters. Cladosporium halotolerans was isolated from hypersaline
water and bathrooms and detected once on dolphin skin. Cladosporium
dominicanum and C. velox were isolated from plant material and
hypersaline water. Cladosporium psychrotolerans, which grows well at
4 °C but not at 30 °C, and C. spinulosum, having
conspicuously ornamented conidia with long digitate projections, are currently
only known from hypersaline water. We also newly describe C. salinae
from hypersaline water and C. fusiforme from hypersaline water and
animal feed. Both species have ovoid to ellipsoid conidia and are therefore
reminiscent of C. herbarum. Cladosporium langeronii (=
Hormodendrum langeronii) previously described as a pathogen on human
skin, is halotolerant but has not yet been recorded from hypersaline
environments
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