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1.
Effect of postnatal development on calcium currents and slow charge movement in mammalian skeletal muscle 总被引:16,自引:3,他引:13 下载免费PDF全文
Single- (whole-cell patch) and two-electrode voltage-clamp techniques were used to measure transient (Ifast) and sustained (Islow) calcium currents, linear capacitance, and slow, voltage-dependent charge movements in freshly dissociated fibers of the flexor digitorum brevis (FDB) muscle of rats of various postnatal ages. Peak Ifast was largest in FDB fibers of neonatal (1-5 d) rats, having a magnitude in 10 mM external Ca of 1.4 +/- 0.9 pA/pF (mean +/- SD; current normalized by linear fiber capacitance). Peak Ifast was smaller in FDB fibers of older animals, and by approximately 3 wk postnatal, it was so small as to be unmeasurable. By contrast, the magnitudes of Islow and charge movement increased substantially during postnatal development. Peak Islow was 3.6 +/- 2.5 pA/pF in FDB fibers of 1-5-d rats and increased to 16.4 +/- 6.5 pA/pF in 45-50-d-old rats; for these same two age groups, Qmax, the total mobile charge measurable as charge movement, was 6.0 +/- 1.7 and 23.8 +/- 4.0 nC/microF, respectively. As both Islow and charge movement are thought to arise in the transverse-tubular system, linear capacitance normalized by the area of fiber surface was determined as an indirect measure of the membrane area of the t-system relative to that of the fiber surface. This parameter increased from 1.5 +/- 0.2 microF/cm2 in 2-d fibers to 2.9 +/- 0.4 microF/cm2 in 44-d fibers. The increases in peak Islow, Qmax, and normalized linear capacitance all had similar time courses. Although the function of Islow is unknown, the substantial postnatal increase in its magnitude suggests that it plays an important role in the physiology of skeletal muscle. 相似文献
2.
Molecular evolution of voltage-sensitive ion channel genes: on the origins of electrical excitability 总被引:14,自引:0,他引:14
We have analyzed nucleic acid and amino acid sequence alignments of a
variety of voltage-sensitive ion channels, using several methods for
phylogenetic tree reconstruction. Ancient duplications within this family
gave rise to three distantly related groups, one consisting of the Na+ and
Ca++ channels, another the K+ channels, and a third including the cyclic
nucleotide-binding channels. A series of gene duplications produced at
least seven mammalian homologues of the Drosophila Shaker K+ channel;
clones of only three of these genes are available from all three mammalian
species examined (mouse, rat, and human), pointing to specific genes that
have yet to be recovered in one or another of these species. The
Shaw-related K+ channels and the Na+ channel family have also undergone
considerable expansion in mammals, relative to flies. These expansions
presumably reflect the needs of the high degree of physiological and
neuronal complexity of mammals. Analysis of the separate domains of the
four-domain channels (Ca++ and Na+) supports their having evolved by two
sequential gene duplications and implies the historical existence of a
functional two-domain channel.
相似文献
3.
Prashant G. Bhat Ajay M. V. Kumar Balaji Naik Srinath Satyanarayana Deepak KG Sreenivas A. Nair Suryakanth MD Einar Heldal Donald A. Enarson Anthony J. Reid 《PloS one》2013,8(12)
Background
Severe acute malnutrition (SAM) is the most serious form of malnutrition affecting children under-five and is associated with many infectious diseases including Tuberculosis (TB). In India, nutritional rehabilitation centres (NRCs) have been recently established for the management of SAM including TB. The National TB Programme (NTP) in India has introduced a revised algorithm for diagnosing paediatric TB. We aimed to examine whether NRCs adhered to these guidelines in diagnosing TB among SAM children.Methods
A cross-sectional study involving review of records of all SAM children identified by health workers during 2012 in six tehsils (sub-districts) with NRCs (population: 1.8 million) of Karnataka, India.Results
Of 1927 identified SAM children, 1632 (85%) reached NRCs. Of them, 1173 (72%) were evaluated for TB and 19(2%) were diagnosed as TB. Of 1173, diagnostic algorithm was followed in 460 (37%). Among remaining 763 not evaluated as per algorithm, tuberculin skin test alone was conducted in 307 (41%), chest radiography alone in 99 (13%) and no investigations in 337 (45%). The yield of TB was higher among children evaluated as per algorithm (4%) as compared to those who were not (0.3%) (OR: 15.3 [95%CI: 3.5-66.3]). Several operational challenges including non-availability of a full-time paediatrician, non-functioning X-ray machine due to frequent power cuts, use of tuberculin with suboptimal strength and difficulties in adhering to a complex diagnostic algorithm were observed.Conclusion
This study showed that TB screening in NRCs was sub-optimal in Karnataka. Some children did not reach the NRC, while many of those who did were either not or sub-optimally evaluated for TB. This study pointed to a number of operational issues that need to be addressed if this collaborative strategy is to identify more TB cases amongst malnourished children in India. 相似文献4.
X Zhang KW Davenport W Gu HE Daligault AC Munk H Tashima K Reitenga LD Green CS Han 《BioTechniques》2012,53(1):61-62
Advances in sequencing technologies have dramatically reduced costs in producing high-quality draft genomes. However, there are still many contigs and possible misassembled regions in those draft genomes. Improving the quality of these genomes requires an efficient and economical means to close gaps and resequence some regions. Sequencing pooled gap region PCR products with Pacific Biosciences (PacBio) provides a significantly less expensive means for this need. We have developed a genome improvement pipeline with this strategy after decreasing a loading bias against larger PCR products in the PacBio process. Compared with Sanger technology, this approach is not only cost-effective but also can close gaps greater than 2.5 kb in a single round of reactions, and sequence through high GC regions as well as difficult secondary structures such as small hairpin loops. 相似文献
5.
6.
Capturing single cell genomes of active polysaccharide degraders: an unexpected contribution of Verrucomicrobia 总被引:1,自引:0,他引:1
Martinez-Garcia M Brazel DM Swan BK Arnosti C Chain PS Reitenga KG Xie G Poulton NJ Lluesma Gomez M Masland DE Thompson B Bellows WK Ziervogel K Lo CC Ahmed S Gleasner CD Detter CJ Stepanauskas R 《PloS one》2012,7(4):e35314
Microbial hydrolysis of polysaccharides is critical to ecosystem functioning and is of great interest in diverse biotechnological applications, such as biofuel production and bioremediation. Here we demonstrate the use of a new, efficient approach to recover genomes of active polysaccharide degraders from natural, complex microbial assemblages, using a combination of fluorescently labeled substrates, fluorescence-activated cell sorting, and single cell genomics. We employed this approach to analyze freshwater and coastal bacterioplankton for degraders of laminarin and xylan, two of the most abundant storage and structural polysaccharides in nature. Our results suggest that a few phylotypes of Verrucomicrobia make a considerable contribution to polysaccharide degradation, although they constituted only a minor fraction of the total microbial community. Genomic sequencing of five cells, representing the most predominant, polysaccharide-active Verrucomicrobia phylotype, revealed significant enrichment in genes encoding a wide spectrum of glycoside hydrolases, sulfatases, peptidases, carbohydrate lyases and esterases, confirming that these organisms were well equipped for the hydrolysis of diverse polysaccharides. Remarkably, this enrichment was on average higher than in the sequenced representatives of Bacteroidetes, which are frequently regarded as highly efficient biopolymer degraders. These findings shed light on the ecological roles of uncultured Verrucomicrobia and suggest specific taxa as promising bioprospecting targets. The employed method offers a powerful tool to rapidly identify and recover discrete genomes of active players in polysaccharide degradation, without the need for cultivation. 相似文献
7.
Sebastian Pukszta Brenda Schilke Rafal Dutkiewicz Jacek Kominek Kaja Moczulska Barbara Stepien Krista G Reitenga Janusz M Bujnicki Barry Williams Elizabeth A Craig Jaroslaw Marszalek 《EMBO reports》2010,11(5):360-365
Molecular mechanisms by which protein–protein interactions are preserved or lost after gene duplication are not understood. Taking advantage of the well–studied yeast mtHsp70:J–protein molecular chaperone system, we considered whether changes in partner proteins accompanied specialization of gene duplicates. Here, we report that existence of the Hsp70 Ssq1, which arose by duplication of the gene encoding multifunction mtHsp70 and specializes in iron–sulphur cluster biogenesis, correlates with functional and structural changes in the J domain of its J–protein partner Jac1. All species encoding this shorter alternative version of the J domain share a common ancestry, suggesting that all short JAC1 proteins arose from a single deletion event. Construction of a variant that extended the length of the J domain of a ‘short’ Jac1 enhanced its ability to partner with multifunctional Hsp70. Our data provide a causal link between changes in the J protein partner and specialization of duplicate Hsp70. 相似文献
8.
Jean F. Challacombe Sophia Majid Ratnakar Deole Thomas S. Brettin David Bruce Susana F. Delano John C. Detter Cheryl D. Gleasner Cliff S. Han Monica Misra Krista G. Reitenga Natalia Mikhailova Tanja Woyke Sam Pitluck Matt Nolan Miriam L. Land Elizabeth Saunders Roxanne Tapia Alla Lapidus Natalia Ivanova Wouter D. Hoff 《Standards in genomic sciences》2013,8(2):206-214
Halorhodospira halophila is among the most halophilic organisms known. It is an obligately photosynthetic and anaerobic purple sulfur bacterium that exhibits autotrophic growth up to saturated NaCl concentrations. The type strain H. halophila SL1 was isolated from a hypersaline lake in Oregon. Here we report the determination of its entire genome in a single contig. This is the first genome of a phototrophic extreme halophile. The genome consists of 2,678,452 bp, encoding 2,493 predicted genes as determined by automated genome annotation. Of the 2,407 predicted proteins, 1,905 were assigned to a putative function. Future detailed analysis of this genome promises to yield insights into the halophilic adaptations of this organism, its ability for photoautotrophic growth under extreme conditions, and its characteristic sulfur metabolism. 相似文献
9.
Starkenburg SR Reitenga KG Freitas T Johnson S Chain PS Garcia-Pichel F Kuske CR 《Journal of bacteriology》2011,193(17):4569-4570
The filamentous cyanobacterium Microcoleus vaginatusis found in arid land soils worldwide. The genome of M. vaginatus strain FGP-2 allows exploration of genes involved in photosynthesis, desiccation tolerance, alkane production, and other features contributing to this organism's ability to function as a major component of biological soil crusts in arid lands. 相似文献
10.
Pamela Orjuela-Sánchez Nadira D Karunaweera Mônica da Silva-Nunes Natal S da Silva Kézia KG Scopel Raquel M Gonçalves Chanaki Amaratunga Juliana M Sá Duong Socheat Rick M Fairhust Sharmini Gunawardena Thuraisamy Thavakodirasah Gawrie LN Galapaththy Rabindra Abeysinghe Fumihiko Kawamoto Dyann F Wirth Marcelo U Ferreira 《BMC genetics》2010,11(1):65