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Nucleotide sequence analysis of the human salivary protein genes HIS1 and HIS2, and evolution of the STATH/HIS gene family 总被引:1,自引:0,他引:1
Human histatins are a family of low-M(r), neutral to very basic,
histidine-rich salivary polypeptides. They probably function as part of the
nonimmune host defense system in the oral cavity. A 39-kb region of DNA
containing the HIS1 and HIS2 genes was isolated from two human genomic
phage libraries as a series of overlapping clones. The nucleotide sequences
of the HIS1 gene and part of the HIS2(1) gene were determined. The
transcribed region of HIS1 spans 8.5 kb and contains six exons and five
introns. The HIS1 and HIS2(1) genes exhibit 89% overall sequence identity,
with exon sequences exhibiting 95% identity. The two loci probably arose by
a gene duplication event approximately 15-30 Mya. The HIS1 sequence data
were also compared with that of STATH. Human statherin is a low-M(r) acidic
phosphoprotein that acts as an inhibitor of precipitation of calcium
phosphate salts in the oral cavity. The HIS1 and STATH genes show nearly
identical overall gene structures. The HIS1 and STATH loci exhibit 77%-81%
sequence identity in intron DNA and 80%-88% sequence identity in noncoding
exons but only 38%-43% sequence identity in the protein-coding regions of
exons 4 and 5. These unusual data suggest that HIS1, HIS2, and STATH belong
to a single gene family exhibiting accelerated evolution between the HIS
and STATH coding sequences.
相似文献
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An exception to the generally conservative nature of plastid gene evolution
is the gene coding for the beta" subunit of RNA polymerase, rpoC2. Previous
work by others has shown that maize and rice have an insertion in the
coding region of rpoC2, relative to spinach and tobacco. To assess the
distribution of this extra coding sequence, we surveyed a broad
phylogenetic sample comprising 55 species from 17 angiosperm families by
using Southern hybridization. The extra coding sequence is restricted to
the grasses (Poaceae). DNA sequence analysis of 11 species from all five
subfamilies within the grass family demonstrates that the extra sequence in
the coding region of rpoC2 is a repetitive array that exhibits more than a
twofold increase in nucleotide substitution, as well as a large number of
insertion/deletion events, relative to the adjacent flanking sequences. The
structure of the array suggests that slipped-strand mispairing causes the
repeated motifs and adds to the mechanisms through which the coding
sequence of plastid genes are known to evolve. Phylogenetic analyses based
on the sequence data from grass species support several relationships
previously suggested by morphological work, but they are ambiguous about
broad relationships within the family.
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Background
The Burkholderia cepacia complex (Bcc) is a collection of nine genotypically distinct but phenotypically similar species. They show wide ecological diversity and include species that are used for promoting plant growth and bio-control as well species that are opportunistic pathogens of vulnerable patients. Over recent years the Bcc have emerged as problematic pathogens of the CF lung. Pseudomonas aeruginosa is another important CF pathogen. It is able to synthesise hydrogen cyanide (HCN), a potent inhibitor of cellular respiration. We have recently shown that HCN production by P. aeruginosa may have a role in CF pathogenesis. This paper describes an investigation of the ability of bacteria of the Bcc to make HCN. 相似文献45.
Katarina EA Nostell Birgitta Essén-Gustavsson Johan T Bröjer 《Acta veterinaria Scandinavica》2012,54(1):7
Background
The branched chain amino acid leucine is a potent stimulator of insulin secretion. Used in combination with glucose it can increase the insulin response and the post exercise re-synthesis of glycogen in man. Decreased plasma amino acid concentrations have been reported after intravenous or per oral administration of leucine in man as well as after a single per oral dose in horses. In man, a negative correlation between the insulin response and the concentrations of isoleucine, valine and methionine have been shown but results from horses are lacking. This study aims to determine the effect of repeated per oral administration with a mixture of glucose and leucine on the free amino acid profile and the insulin response in horses after glycogen-depleting exercise. 相似文献46.
Kumar Narayanan Mohammed Omer Mohammed Arif Papani Sridhar Nitin Annarapu Shivaprasad Naidu Pankaj Jariwala Narasaraju Kavalipati Mukharjee Madivada Ramagiri Balaji Premchand M Sharath Reddy A Anil Krishna G Padmakumar EA 《Indian pacing and electrophysiology journal》2021,21(1):5-10
BackgroundLeft-sided ablation, targeting left inferior AV nodal extensions, is thought to be necessary for success in a small proportion of atrioventricular nodal re-entrant tachycardia (AVNRT) ablations; however Indian data are scarce in this regard.MethodsConsecutive cases of AVNRT undergoing slow pathway ablation in a single centre over an 18-month period were retrospectively analyzed. Left-sided ablation at the posteroseptal mitral annulus was performed if right-sided ablation failed to abolish AVNRT.ResultsFrom January 2017 to June 2018, out of 215 consecutive supraventricular tachycardia (SVT) cases, 154 (71.6%) were AVNRT (47.1 ± 13.1 years, 46.1% male). Trans-septal ablation was required in 5 (3.2%) cases (mean age 48.8 ± 9.4 years; 4 female, 1 male); all with typical (slow-fast) form of AVNRT. Compared with cases needing only right-sided ablation, radiofrequency time (50.8 ± 16.9 vs. 9.9 ± 8.5 min; p = 0.005) and procedure time (166.0 ± 35.0 vs 79.6 ± 35.9 min; p = 0.004) were significantly longer for trans-septal cases, while baseline intervals and tachycardia cycle length were not significantly different. Junctional ectopy was seen in only 2 of the 5 cases during left-sided ablation, but acute success (non-inducibility) was obtained in 3 cases. There were no instances of AV block. Over mean follow-up of 12.2 ± 4.0 months, clinical recurrence of AVNRT occurred in one case, while others remained arrhythmia-free without medication.ConclusionLeft-sided ablation was required in a small proportion of AVNRT ablations. Trans-septal approach targeting the posteroseptal mitral annulus was safe and yielded good mid-term clinical success. 相似文献
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Floris EA Udink ten Cate Nathalie Wiesner Uwe Trieschmann Markus Khalil Narayanswami Sreeram 《Indian pacing and electrophysiology journal》2010,10(6):248-256
A subset of children and adults with Wolff-Parkinson-White (WPW) syndrome develop dilated cardiomyopathy (DCM). Although DCM may occur in symptomatic WPW patients with sustained tachyarrhythmias, emerging evidence suggests that significant left ventricular dysfunction may arise in WPW in the absence of incessant tachyarrhythmias. An invariable electrophysiological feature in this non-tachyarrhythmia type of DCM is the presence of a right-sided septal or paraseptal accessory pathway. It is thought that premature ventricular activation over these accessory pathways induces septal wall motion abnormalities and ventricular dyssynchrony. LV dyssynchrony induces cellular and structural ventricular remodelling, which may have detrimental effects on cardiac performance. This review summarizes recent evidence for development of DCM in asymptomatic patients with WPW, discusses its pathogenesis, clinical presentation, management and treatment. The prognosis of accessory pathway-induced DCM is excellent. LV dysfunction reverses following catheter ablation of the accessory pathway, suggesting an association between DCM and ventricular preexcitation. Accessory pathway-induced DCM should be suspected in all patients presenting with heart failure and overt ventricular preexcitation, in whom no cause for their DCM can be found. 相似文献
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Xiuhong Feng Dayana Rodriguez-Contreras Cosmo Buffalo H. G. Archie Bouwer Elizabeth Kruvand Stephen M. Beverley Scott M. Landfear 《Molecular microbiology》2009,71(2):369-381
A glucose transporter null mutant of the parasitic protozoan Leishmania mexicana , in which three linked glucose transporter genes have been deleted by targeted gene replacement, is unable to replicate as amastigote forms within phagolysomes of mammalian host macrophages and is avirulent. Spontaneous suppressors of the null mutant have been isolated that partially restore replication of parasites within macrophages. These suppressor mutants have amplified the gene for an alternative hexose transporter, the LmGT4 permease (previously called the D2 permease), on a circular extrachromosomal element, and they overexpress LmGT4 mRNA and protein. The suppressors have also regained the ability to transport hexoses, and they have reverted other phenotypes of the null mutant exhibiting enhanced resistance to oxidative killing, heat shock and starvation for nutrients, as well as augmented levels of the storage carbohydrate β-mannan, increased cell size and increased growth as insect stage promastigotes compared with the unsuppressed mutant. Complementation of the null mutant with the LmGT4 gene on a multicopy episomal expression vector also reverted these phenotypes, confirming that suppression results from amplification of the LmGT4 gene. These results underscore the importance of hexose transporters for the infectious stage of the parasite life cycle. 相似文献
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