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101.
102.
Evolution of the selfing syndrome: Anther orientation and herkogamy together determine reproductive assurance in a self‐compatible plant 下载免费PDF全文
Per Toräng Linus Vikström Jörg Wunder Stefan Wötzel George Coupland Jon Ågren 《Evolution; international journal of organic evolution》2017,71(9):2206-2218
Capacity for autonomous self‐fertilization provides reproductive assurance, has evolved repeatedly in the plant kingdom, and typically involves several changes in flower morphology and development (the selfing syndrome). Yet, the relative importance of different traits and trait combinations for efficient selfing and reproductive success in pollinator‐poor environments is poorly known. In a series of experiments, we tested the importance of anther–stigma distance and the less studied trait anther orientation for efficiency of selfing in the perennial herb Arabis alpina. Variation in flower morphology among eight self‐compatible European populations was correlated with efficiency of self‐pollination and with pollen limitation in a common‐garden experiment. To examine whether anther–stigma distance and anther orientation are subject to directional and/or correlational selection, and whether this is because these traits affect pollination success, we planted a segregating F2 population at two native field sites. Selection strongly favored a combination of introrse anthers and reduced anther–stigma distance at a site where pollinator activity was low, and supplemental hand‐pollination demonstrated that this was largely because of their effect on securing self‐pollination. The results suggest that concurrent shifts in more than one trait can be crucial for the evolution of efficient self‐pollination and reproductive assurance in pollinator‐poor habitats. 相似文献
103.
We describe two new, mainly North European species of basidiomycetous fungi. Cortinarius stjernegaardii belongs to the section Percomes containing several similar species with greenish-yellow, anthraquinonoid pigments and peculiar smells. The species has hitherto been identified as” C. bulbopodius” in the Nordic countries, an epithet which, however, is reduced to a synonym of C. aurilicis. Cortinarius kristinae belongs to the section Calochroi, which includes many morphologically similar species with sharply marginate bulbose stipes and yellow pileus colours. The species are distinguished from related taxa by molecular data (ribosomal ITS region), and typical specimens can be identified by a combination of basidiocarp coloration, stature, microscopy, reactions with KOH, and habitat. 相似文献
104.
Karl A Franklin Christer Janson Thórarinn Gíslason Amund Gulsvik Maria Gunnbj?rnsdottir Birger N Laerum Eva Lindberg Eva Norrman Lennarth Nystr?m Ernst Omenaas Kjell Torén Cecilie Svanes 《Respiratory research》2008,9(1):63
Background
To our knowledge, no studies of the possible association of early life environment with snoring in adulthood have been published. We aimed to investigate whether early life environment is associated with snoring later in life.Methods
A questionnaire including snoring frequency in adulthood and environmental factors in early life was obtained from 16,190 randomly selected men and women, aged 25–54 years, in Sweden, Norway, Iceland, Denmark and Estonia (response rate 74%).Results
A total of 15,556 subjects answered the questions on snoring. Habitual snoring, defined as loud and disturbing snoring at least 3 nights a week, was reported by 18%. Being hospitalized for a respiratory infection before the age of two years (adjusted odds ratio (OR) = 1.27; 95% confidence interval (CI) 1.01–1.59), suffering from recurrent otitis as a child (OR = 1.18; 95%CI 1.05–1.33), growing up in a large family (OR = 1.04; 95%CI 1.002–1.07) and being exposed to a dog at home as a newborn (OR = 1.26; 95%CI 1.12–1.42) were independently related to snoring later in life and independent of a number of possible confounders in adulthood. The same childhood environmental factors except household size were also related with snoring and daytime sleepiness combined.Conclusion
The predisposition for adult snoring may be partly established early in life. Having had severe airway infections or recurrent otitis in childhood, being exposed to a dog as a newborn and growing up in a large family are environmental factors associated with snoring in adulthood. 相似文献105.
Jillian R. Brown Feng Yang Anjana Sinha Boopathy Ramakrishnan Yitzhak Tor Pradman K. Qasba Jeffrey D. Esko 《The Journal of biological chemistry》2009,284(8):4952-4959
The disaccharide peracetylated
GlcNAcβ1–3Galβ-O-naphthalenemethanol (disaccharide 1)
diminishes the formation of the glycan sialyl Lewis X
(Neu5Acα2–3Galβ1–4(Fucα1–3) GlcNAc;
sLeX) in tumor cells. Previous studies showed that the mechanism of
action of disaccharide 1 involves three steps: (i) deacetylation by
carboxyesterases, (ii) action as a biosynthetic intermediate for downstream
enzymes involved in sLeX assembly, and (iii) generation of several
glycans related to sLeX. In this report, we show that
GlcNAcβ1–3Galβ-O-naphthalenemethanol binds to the
acceptor site of human β1–4-galactosyltransferase much like the
acceptor trisaccharide, GlcNAcβ1–2Manβ1–6Man, which is
present on N-linked glycans. The 4′-deoxy analog, in which the
acceptor hydroxyl group was replaced by -H, did not act as a substrate but
instead acted as a competitive inhibitor of the enzyme. The acetylated form of
this compound inhibited sLeX formation in U937 monocytic leukemia
cells, suggesting that it had inhibitory activity in vivo as well. A
series of synthetic acetylated analogs of 1 containing -H, -F, -N3,
-NH2, or -OCH3 instead of the hydroxyl groups at
C-3′- and C-4′-positions of the terminal
N-acetylglucosamine residue also blocked sLeX formation in
cells. The reduction of sLeX by the 4′-deoxy analog also
diminished experimental tumor metastasis by Lewis lung carcinoma in
vivo. These data suggest that nonsubstrate disaccharides have therapeutic
potential through their ability to bind to glycosyltransferases in
vivo and to alter glycan-dependent pathologic processes.The sialylated, fucosylated tetrasaccharide,
sLeX,3 is a
common carbohydrate determinant present in many O-GalNAc-linked
mucins and N-linked glycans that act as selectin ligands (see Ref.
1 and references therein).
Expression of sLeX endows tumor cells with the capacity to bind to
platelets and endothelial cells in the vasculature via P- and E-selectins,
thus facilitating hematogenous metastasis possibly through protection against
innate immune cells and by adhesion to the blood vessel wall. Strategies for
blocking selectin-carbohydrate interactions include (i) competition by soluble
recombinant forms of selectins, glycoprotein ligands, and glycolipids, (ii)
peptides based on the primary sequence of the carbohydrate binding site, (iii)
anti-selectin antibodies, (iv) oligosaccharides related to LewisX,
(v) inositol polyanions and sulfated sugars, (vi) heparin, and (vii) molecular
mimics of sLeX, including oligonucleotides (reviewed in Refs.
2 and
3). Analogs of acceptor
substrates of the various glycosyltransferases involved in glycan biosynthesis
provide another class of potential inhibitors (reviewed in Refs.
4 and
5). Although many of these
analogs are effective in vitro, they generally do not exhibit
inhibitory activity in cells due to poor membrane permeability. The large
number of polar hydroxyl groups and the lack of membrane transporters for
oligosaccharides in most cells presumably prevent their uptake
(6).In contrast to many of the inhibitors described above, peracetylated
disaccharides (e.g. acetylated
Galβ1–4GlcNAcβ-O-naphthalenemethanol (NM), acetylated
Galβ1–3GalNAcα-O-NM, and acetylated
GlcNAcβ1–3Galβ-O-NM) inhibit sLeX biosynthesis in
cells
(6–9).
These compounds are taken up by cells by passive diffusion and acted on by
cytoplasmic or membrane-associated carboxyesterases, which remove the acetyl
groups. The compounds gain access to the biosynthetic enzymes located in the
Golgi complex, where they serve as substrates, priming oligosaccharide
synthesis and generating products related to O-GalNAc-linked mucin
oligosaccharides. Priming in this manner diverts the assembly of the
O-linked chains from endogenous glycoproteins, resulting in
inhibition of expression of terminal Lewis antigens that are recognized by
selectins. Inhibition occurs at a much lower dose than for
monosaccharide-based agents, such as GalNAcβ-O-benzyl (∼25
μm versus 1–2 mm, respectively)
(10,
11). Furthermore, the
disaccharides appear to selectively affect sLeX formation, since
sLea expression was unaffected
(12). By blocking selectin
ligand expression, these compounds block both experimental and spontaneous
metastasis (12,
13).In this study, we have examined acetylated disaccharide analogs that have
been modified so that after deacetylation their activity as substrates would
be altered. Characterization of the 4′-deoxy derivative using
β1–4-galactosyltransferase 1 as a model showed that it acts by
competitively inhibiting the enzyme. Interestingly, the peracetylated form of
this analog maintains the capacity to inhibit sLeX expression in
U937 lymphoma cells and Lewis lung carcinoma (LLC) cells and block tumor
formation in vivo. Thus, the deoxy analog presumably inhibits one or
more galactosyltransferases in vivo, thereby blocking sLeX
formation and experimental tumor cell metastasis without generation of
oligosaccharide products. 相似文献
106.
Background
As more inhaled corticosteroid (ICS) devices become available, there may be pressure for health-care providers to switch patients with asthma to cheaper inhaler devices. Our objective was to evaluate impact on asthma control of inhaler device switching without an accompanying consultation in general practice.Methods
This 2-year retrospective matched cohort study used the UK General Practice Research Database to identify practices where ICS devices were changed without a consultation for ≥5 patients within 3 months. Patients 6–65 years of age from these practices whose ICS device was switched were individually matched with patients using the same ICS device who were not switched. Asthma control over 12 months after the switch was assessed using a composite measure including short-acting β-agonist and oral corticosteroid use, hospitalizations, and subsequent changes to therapy.Results
A total of 824 patients from 55 practices had a device switch and could be matched. Over half (53%) of device switches were from dry powder to metered-dose inhalers. Fewer patients in switched than matched cohort experienced successful treatment based on the composite measure (20% vs. 34%) and more experienced unsuccessful treatment (51% vs. 38%). After adjusting for possible baseline confounding factors, the odds ratio for treatment success in the switched cohort compared with controls was 0.29 (95% confidence interval [CI], 0.19 to 0.44; p < 0.001) and for unsuccessful treatment was 1.92 (95% CI, 1.47 to 2.56; p < 0.001).Conclusion
Switching ICS devices without a consultation was associated with worsened asthma control and is therefore inadvisable. 相似文献107.
Chen Ying Klingen Tor A Wik Elisabeth Aas Hans Vigeland Einar Liestøl Knut Garred Øystein Mæhlen Jan Akslen Lars A Lømo Jon 《Diagnostic pathology》2014,9(1):1-2
Squamous cell carcinomas (SCCs) are uncommon, high-grade tumors, predominantly composed of round cells in the prepuce. The aim of this study is to better define the clinicopathologic features of this neoplasm. We conducted cyto-histopathologic analysis on the manifestations of the prepuce SCC by H &; E staining in a terrier mix dog. Grossly, tumor was large, multiple erythematous patch, and ulcerated masses frequently affecting the prepuce and deeply invading to distal prepuce out from the ventro-lateral of penis and the tumor covered by a necrotic discharge. Cytological evaluation of fine-needle aspirates from the cutaneous mass from the prepuce comprised of round nuclei, coarse chromatin pattern, distinct nucleoli and nuclear pleomorphism. Furthermore, the neoplastic cells were pleomorphic, round to caudate in shape, exhibiting prominent anisokaryosis and anisocytosis with rare mitotic features. Microscopically, the lesions were predominantly composed of atypical round cells disposed in interlacing fascicles. Frequent findings include keratin formation, horn pearls, mitoses and cellular atypia. The cells showed distinct borders, ranged from polygonal to round or elongate and had moderate amounts of eosinophilic cytoplasm. The histopathologic features coupled with the cytopathology findings led to a diagnosis of squamous cell carcinoma. To the authors’ knowledge, this is the first time that multiple erythematous plaques have undergone malignant transformation in a terrier mix dog. The virtual slide(s) for this article can be found here:
http://www.diagnosticpathology.diagnomx.eu/vs/5748771971272873 相似文献
108.
Alisha J. Beirl Tor H. Linbo Marea J. Cobb Cynthia D. Cooper 《Pigment cell & melanoma research》2014,27(2):178-189
We characterized a zebrafish mutant that displays defects in melanin synthesis and in the differentiation of melanophores and iridophores of the skin and retinal pigment epithelium. Positional cloning and candidate gene sequencing link this mutation to a 410‐kb region on chromosome 6, containing the oculocutaneous albinism 2 (oca2) gene. Quantification of oca2 mutant melanophores shows a reduction in the number of differentiated melanophores compared with wildtype siblings. Consistent with the analysis of mouse Oca2‐deficient melanocytes, zebrafish mutant melanophores have immature melanosomes which are partially rescued following treatment with vacuolar‐type ATPase inhibitor/cytoplasmic pH modifier, bafilomycin A1. Melanophore‐specific gene expression is detected at the correct time and in anticipated locations. While oca2 zebrafish display unpigmented gaps on the head region of mutants 3 days post‐fertilization, melanoblast quantification indicates that oca2 mutants have the correct number of melanoblasts, suggesting a differentiation defect explains the reduced melanophore number. Unlike melanophores, which are reduced in number in oca2 mutants, differentiated iridophores are present at significantly higher numbers. These data suggest distinct mechanisms for oca2 in establishing differentiated chromatophore number in developing zebrafish. 相似文献
109.
Tor F. Næsje Amber-Robyn Childs Paul D. Cowley Warren M. Potts Eva B. Thorstad Finn Økland 《Hydrobiologia》2007,582(1):25-34
The purpose of this study was to test the hypothesis that an estuarine species as the spotted grunter Pomadasys commersonnii is evenly distributed within the estuary and uniformly exploited by different groups of fishers. This was done by investigating
the movements and area use of spotted grunter in relation to the fisheries. The position of 20 acoustically tagged fish was
recorded during 36 days in February and March 2003, by manual tracking and automated data logging receivers. Information on
the fisheries in the estuary was collected through visual registration of fishing effort and interviews. The spotted grunter
moved on average 1.0 km (SD ± 0.7) between positional fixes. Most of the fish were positioned in the lower part of the 12
km long estuary, as 70% of the positional fixes were within the first 3 km, and 89% within the first 6 km. Approximately half
(49%) of all the fixes were between 1.0 and 1.5 km from the estuary mouth. The spotted grunter used on average 4.9 km (SD
± 4.9) of the length of the estuary, and there was no significant relationship between the length of the estuary used and
the body length of the fish (26–39 cm TL). Subsistence fishers accounted for 73% of fishing lines in the water, while recreational
fishers accounted for the rest. Ninety-three percent of the lines were recorded within the first 6 km from the estuary mouth,
of which 80% were recorded within the first 3 km. Almost 1/3 of the fishing effort was recorded between 1.0 and 1.5 km from
the mouth. The hypothesis that the estuarine dependent species spotted grunter was evenly distributed within the estuary was
rejected. However, there was a significant relationship between the distribution of the fishing effort of the subsistence
fishers and the fish, indicating that the spotted grunter was uniformly exploited within the estuary by this group of fishers.
In contrast, there was no relationship between the distribution of fish and recreational anglers. 相似文献
110.
Par J. Garegg Tor Regberg Jacek Stawinski Roger Strömberg 《Nucleosides, nucleotides & nucleic acids》2013,32(1-2):429-432
Abstract Oxidation of nucleoside H-phosphonate diesters has been investigated using dipyridyl disulphide, hexachloroacetone and iodine, under various reaction conditions. 相似文献