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1.
WhileEscherichia coli is common as a commensal organism in the distal ileum and colon, the presence of colonization factors (CF) on pathogenic strains ofE. coli facilitates attachment of the organism to intestinal receptor molecules in a species- and tissue-specific fashion. After the initial adherence, colonization occurs, and the involvement of additional virulence determinants leads to illness. EnterotoxigenicE. coli (ETEC) is the most extensively studied of the five categories ofE. coli that cause diarrheal disease, and has the greatest impact on health worldwide. ETEC can be isolated from domestic animals and humans. The biochemistry, genetics, epidemiology, antigenic characteristics, and cell and receptor binding properties of ETEC have been extensively described. Another major category, enteropathogenicE. coli (EPEC), has virulence mechanisms, primarily effacement and cytoskeletal rearrangement of intestinal brush borders, that are distinct from ETEC. An EPEC CF receptor has been purified and characterized as a sialidated transmembrane glycoprotein complex directly attached to actin, thereby associating CF-binding with host-cell response. Three, additional categories ofE. coli diarrheal disease, their colonization factors and their host cell receptors are discussed. It appears that biofilms exist in the intestine in a manner similar to oral bacterial biofilms, and thatE. coli is part of these biofilms as both commensals and pathogens.Abbreviations CF
colonization factor
- CFA
Colonization Factor Antigen
- CS
coli-surface-associated antigen
- EAggEC
enteroaggregativeE. coli
- ECDD
E. coli diarrheal disease
- EHEC
enterohemorrhagicE. coli
- EIEC
enteroinvasiveE. coli
- EPEC
enteropathogenicE. coli
- ETEC
enterotoxigenicE. coli
- Gal
galactose
- GalNAc
N-acetyl galactosamine
- LT
heat-labile toxin
- NeuAc
N-acetyl neuraminic acid
- PCF
Putative colonization factor
- RBC
red blood cells
- SLT
Shiga-like toxin
- ST
heat-stable toxin 相似文献
2.
Punja Harshitha K. Nanjappa Dechamma Pandyanda Babu Nishith Kalladka Krithika Shanti Priya Dias B. Chakraborty Gunimala Rao Sudhindra M. Chakraborty Anirban 《Molecular biology reports》2021,48(6):5093-5097
Molecular Biology Reports - TP53 functions primarily as a tumor suppressor, controlling a myriad of signalling pathways that prevent a cell from undergoing malignant transformation. This tumor... 相似文献
3.
We examined gazelle peripheral blood leucocytes using the α-Naphthyl acetate esterase (ANAE) staining technique (pH 5.8). Our purpose was to determine the percentage of ANAE positive lymphocytes. The proportion of ANAE positive T-lymphocytes was 72%. T-lymphocytes showed an ANAE positive reaction, but eosinophilic granulocytes and monocytes also showed a positive reaction. By contrast, no reaction was detected in B-lymphocytes, neutrophil granulocytes or platelets. The reaction observed in T-lymphocytes was a red-brown coloration, usually 1–2 granules, but enough granules to fill the cytoplasm were detected rarely. As a result of ANAE enzyme staining, we concluded that the staining technique can be used as a cytochemical marker for gazelle T-lymphocytes. 相似文献
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5.
Aims and Background
The aim was to investigate the diversity and distribution of Glomeromycotan fungi forming arbuscular mycorrhizal associations (AMF) in undisturbed and disturbed habitats in the vicinity of Kakadu National Park in tropical Australia. This is a tropical region with a 7–9 month dry season and a monsoonal wet season. Complimentary methods of fungus detection were used to investigate the diversity and relative dominance of AMF at a regional scale.Methods
Soils were sampled from 32 sites, representing eucalypt savanna woodlands, wetlands, sandstone escarpment, rainforest, and disturbed mine waste rock dumps (overburden or spoil). Populations of AMF were identified and quantified using spores from soil. Morphology patterns of fungi colonising bait plant roots were examined and isolates were obtained by four complimentary pot-culturing methods.Results
Different methods of detecting fungi produced different answers about which AMF were most important in the tested soils. In particular, spore surveys apparently underestimated the importance of Glomus species and overestimated the activity of Acaulospora species with numerous small spores, while calculated spore biovolumes overestimated the importance of Scutellospora and Gigaspora species with large spores, relative to inoculum levels of these fungus categories measured in bioassays. Spore surveys revealed 15 species of fungi and 8 additional fungi were recovered from the same soil samples using pot-culture isolation methods. Pot-cultures were especially important for detecting Glomus species that had high inoculum levels, but rarely produced spores in soils. Spores of AMF increased in abundance as vegetation developed in mine habitats reaching a peak that was higher than in undisturbed plant communities. Spore numbers (but not biovolumes) were well correlated with bioassay measurements of inoculum levels.Conclusions
Most AMF species were widespread, but several were restricted to disturbed habitats or wetland soils. Undisturbed sites had a substantially higher diversity of AMF than partially vegetated mine waste rock dumps. It is recommended that AMF population surveys should not be based entirely on spore occurrence data, to avoid overlooking important fungi that sporulate infrequently. These fungi could be detected by bioassays or pot culture isolation from soil. Major variations in the detectability of AMF correspond to different life history strategies and can mask variations in their abundance. 相似文献6.
Neelagandan Kamariah Sathya Moorthy Ponnuraj Balasubramanian Moovarkumudalvan Mondikalipudur Nanjappa Gounder Ponnuswamy 《Biochemical and biophysical research communications》2014
Hemoglobin (Hb) is in equilibrium between low affinity Tense (T) and high affinity Relaxed (R) states associated with its unliganded and liganded forms, respectively. Mammalian species can be classified into two groups on the basis of whether they express ‘high’ and ‘low’ oxygen affinity Hbs. Although Hbs from former group have been studied extensively, a limited number of structural studies have been performed for the low oxygen affinity Hbs. Here, the crystal structure of low oxygen affinity sheep methemoglobin (metHb) has been determined to 2.7 Å resolution. Even though sheep metHb adopts classical R state like quaternary structure, it shows localized quaternary and tertiary structural differences compared with other liganded Hb. The critical group of residues in the “joint region”, shown as a major source of quaternary constraint on deoxyHb, formed unique interactions in the α1β2/α2β1 interfaces of sheep metHb structure. In addition, the constrained β subunits heme environment and the contraction of N-termini and A-helices of β subunits towards the molecular dyad are observed for sheep metHb structure. These observations provide the structural basis for a low oxygen affinity and blunt response to allosteric effector of sheep Hb. 相似文献
7.
Yu‐Chiang Lai Chandana Kondapalli Ronny Lehneck James B Procter Brian D Dill Helen I Woodroof Robert Gourlay Mark Peggie Thomas J Macartney Olga Corti Jean‐Christophe Corvol David G Campbell Aymelt Itzen Matthias Trost Miratul MK Muqit 《The EMBO journal》2015,34(22):2840-2861
Mutations in the PTEN‐induced kinase 1 (PINK1) are causative of autosomal recessive Parkinson''s disease (PD). We have previously reported that PINK1 is activated by mitochondrial depolarisation and phosphorylates serine 65 (Ser65) of the ubiquitin ligase Parkin and ubiquitin to stimulate Parkin E3 ligase activity. Here, we have employed quantitative phosphoproteomics to search for novel PINK1‐dependent phosphorylation targets in HEK (human embryonic kidney) 293 cells stimulated by mitochondrial depolarisation. This led to the identification of 14,213 phosphosites from 4,499 gene products. Whilst most phosphosites were unaffected, we strikingly observed three members of a sub‐family of Rab GTPases namely Rab8A, 8B and 13 that are all phosphorylated at the highly conserved residue of serine 111 (Ser111) in response to PINK1 activation. Using phospho‐specific antibodies raised against Ser111 of each of the Rabs, we demonstrate that Rab Ser111 phosphorylation occurs specifically in response to PINK1 activation and is abolished in HeLa PINK1 knockout cells and mutant PINK1 PD patient‐derived fibroblasts stimulated by mitochondrial depolarisation. We provide evidence that Rab8A GTPase Ser111 phosphorylation is not directly regulated by PINK1 in vitro and demonstrate in cells the time course of Ser111 phosphorylation of Rab8A, 8B and 13 is markedly delayed compared to phosphorylation of Parkin at Ser65. We further show mechanistically that phosphorylation at Ser111 significantly impairs Rab8A activation by its cognate guanine nucleotide exchange factor (GEF), Rabin8 (by using the Ser111Glu phosphorylation mimic). These findings provide the first evidence that PINK1 is able to regulate the phosphorylation of Rab GTPases and indicate that monitoring phosphorylation of Rab8A/8B/13 at Ser111 may represent novel biomarkers of PINK1 activity in vivo. Our findings also suggest that disruption of Rab GTPase‐mediated signalling may represent a major mechanism in the neurodegenerative cascade of Parkinson''s disease. 相似文献
8.
AB Chang NC Cox J Purcell JM Marchant PJ Lewindon GJ Cleghorn LC Ee GD Withers MK Patrick J Faoagali 《Respiratory research》2005,6(1):1-5
Background and methods
Human metapneumovirus (hMPV) is a recently discovered respiratory virus associated with bronchiolitis, pneumonia, croup and exacerbations of asthma. Since respiratory viruses are frequently detected in patients with acute exacerbations of COPD (AE-COPD) it was our aim to investigate the frequency of hMPV detection in a prospective cohort of hospitalized patients with AE-COPD compared to patients with stable COPD and to smokers without by means of quantitative real-time RT-PCR.Results
We analysed nasal lavage and induced sputum of 130 patients with AE-COPD, 65 patients with stable COPD and 34 smokers without COPD. HMPV was detected in 3/130 (2.3%) AE-COPD patients with a mean of 6.5 × 105 viral copies/ml in nasal lavage and 1.88 × 105 viral copies/ml in induced sputum. It was not found in patients with stable COPD or smokers without COPD.Conclusion
HMPV is only found in a very small number of patients with AE-COPD. However it should be considered as a further possible viral trigger of AE-COPD because asymptomatic carriage is unlikely. 相似文献9.
The presence of bisphenol A (BPA) in consumer products has raised concerns about potential adverse effects on reproductive health. Testicular Leydig cells are the predominant source of the male sex steroid hormone testosterone, which supports the male phenotype. The present report describes the effects of developmental exposure of male rats to BPA by gavage of pregnant and lactating Long-Evans dams at 2.5 and 25 μg/kg body weight from Gestational Day 12 to Day 21 postpartum. This exposure paradigm stimulated Leydig cell division in the prepubertal period and increased Leydig cell numbers in the testes of adult male rats at 90 days. Observations from in vitro experiments confirmed that BPA acts directly as a mitogen in Leydig cells. However, BPA-induced proliferative activity in vivo is possibly mediated by several factors, such as 1) protein kinases (e.g., mitogen-activated protein kinases or MAPK), 2) growth factor receptors (e.g., insulin-like growth factor 1 receptor-beta and epidermal growth factor receptors), and 3) the Sertoli cell-secreted anti-Mullerian hormone (also called Mullerian inhibiting substance). On the other hand, BPA suppressed protein expression of the luteinizing hormone receptor (LHCGR) and the 17beta-hydroxysteroid dehydrogenase enzyme (HSD17B3), thereby decreasing androgen secretion by Leydig cells. We interpret these findings to mean that the likely impact of deficits in androgen secretion on serum androgen levels following developmental exposure to BPA is alleviated by increased Leydig cell numbers. Nevertheless, the present results reinforce the view that BPA causes biological effects at environmentally relevant exposure levels and its presence in consumer products potentially has implication for public health. 相似文献
10.
Tissue Culture Studies of Tomato (Lycopersicon esculentum) 总被引:1,自引:0,他引:1
Poonam Bhatia Nanjappa Ashwath Tissa Senaratna David Midmore 《Plant Cell, Tissue and Organ Culture》2004,78(1):1-21
Tomato is a major vegetable crop that has achieved tremendous popularity over the last century. It is grown in almost every
country of the world. Development of protocols for in vitro selection can provide new advances for the production of stress tolerant cultivars. Techniques have been optimised for the
production of haploids and somatic hybrids. Attempts have also been made to transfer the higher regenerative ability of wild
varieties to cultivated tomatoes. Although, some information is available on the morphogenesis of tomato, the techniques have
not been developed to a level at which they can be utilised in large-scale multiplication of commercially important cultivars.
The morphogenesis response seems to be highly dependent PGRs used in the media, which is again cultivar and genotypic specific.
Somatic embryogenesis in tomato is still at its infancy, and efficient procedures for large-scale production via somatic embryogenesis
are yet to be developed. Genetic stability of the tissue culture raised tomato plants also needs to be addressed. The use
of a combination of molecular and conventional breeding techniques could be the option for the development of cultivars resistant
to biotic and abiotic stresses. This paper reviews the advances made in various aspects of tissue culture in tomato. It also
discusses the issues that still need to be addressed to utilise the full potential of plant tissue culture techniques in genetic
improvement and mass propagation of tomato. 相似文献