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81.
Piwi-interacting RNAs (piRNAs) are a recently discovered class of small non-coding RNA found in animals. PiRNAs are primarily expressed in the germline where their best understood function is to repress transposable elements. Unlike previous studies that investigated the evolution of piRNA-generating loci at the level of nucleotide substitutions, here we studied the evolution of piRNA-generating loci at the level of copy number variation (i.e. duplications and deletions) using genome-wide copy number variation data from three human populations. Our analysis shows that at the level of copy number variation there is strong selective constraint and a very high mutation rate in human piRNA-generating loci. Our results differ from a model of positive selection on copy number variation in piRNA-generating loci previously proposed in rodents. We discuss possible reasons for this difference based on the transposable element insertion histories in the rodent and primate lineages. 相似文献
82.
Nisevic I Dinic J Nikolic A Djordjevic V Lukic S Ugljesic M Andjelic-Jelic M Petrovic-Stanojevic N Radojkovic D 《Cell biochemistry and function》2008,26(6):659-663
Chronic pancreatitis and pancreatic adenocarcinoma are extensively studied as common and potentially lethal disorders. However, their causes and genetic background in most cases remain unclear. The C677T polymorphism in 5',10'-methylenetetrahydrofolate reductase (MTHFR) gene may modulate the risk of pancreatic disorders. In this study, we tested whether MTHFR C677T polymorphism is associated with chronic pancreatitis and pancreatic adenocarcinoma in the Serbian population. DNA was extracted from blood samples of 51 chronic pancreatitis patients, 21 pancreatic adenocarcinoma patients, and a control group consisting of 50 healthy smokers. The MTHFR C677T polymorphism was analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. Although, no statistically significant differences were observed in the distribution of MTHFR genotype or allele frequencies between patients and control groups, the results showed an increased frequency of homozygotes for MTHFR C677T polymorphism in chronic pancreatitis patients (14%) and a decreased frequency in pancreatic adenocarcinoma patients (5%) in comparison to the control group (8%). We speculate that the MTHFR C677T polymorphism could act as a possible risk factor for chronic pancreatitis and a possible protective factor in pancreatic adenocarcinoma. This observation needs further investigation in prospective studies on a larger number of patients, in which the effect of other genetic and environmental factors should also be taken into consideration. 相似文献
83.
Plastids are functionally and structurally diverse organelles responsible for numerous biosynthetic reactions within the plant cell. Plastids from embryos have a range of properties depending upon the plant source but compared to other plastid types are poorly understood and therefore, we term them embryoplasts. Isolating intact plastids from developing embryos is challenging due to large starch granules within the stroma and the prevalence of nonplastid, storage organelles (oil bodies and protein storage vacuoles) which compromise plastid integrity and purity, respectively. To characterize rapeseed embryoplasts it was necessary to develop an improved isolation procedure. A new method is presented for the isolation of intact plastids from developing embryos of Brassica napus seeds. Intactness and purity of embryoplast preparations was determined using phase-contrast and transmission electron microscopy, immunoblotting, and multidimensional protein identification technology (MudPIT) MS/MS. Eighty nonredundant proteins were identified by MudPIT analysis of embryoplast preparations. Approximately 53% of these proteins were components of photosystem, light harvesting, cytochrome b/f, and ATP synthase complexes, suggesting ATP and NADPH production are important functions for this plastid type. 相似文献
84.
Milisavljevic MDj Timotijevic GS Radovic SR Konstantinovic MM Maksimovic VR 《Journal of plant physiology》2008,165(9):983-990
Two types of aspartic proteinase (AP) genes have been isolated from the cDNA library of developing buckwheat seeds. Analysis of their sequences showed that one of these, FeAP9, resembled the structure and shared high homology with the so-called typical plant APs characterized by the presence of a plant-specific insert (PSI), an element unique among APs. The other cDNA, FeAPL1, encoded an AP-like protein lacking that domain. Different expression profiles were observed for FeAP9 and FeAPL1. FeAPL1 mRNAs were restricted to the seeds only, whereas FeAP9 mRNAs were also present in the other plant tissues - leaves, roots, and flowers. Higher levels of FeAP9 were observed in senescent leaves compared with green leaves. The differential expression pattern of these two unique APs raises the interesting possibility that these proteinases have unique substrate specificity and may have different roles in plant development and other physiological processes. 相似文献
85.
The aim of the study was to assess maternal perception of family impact on the course and outcome of rehabilitation in children with cerebral motor impairment. The study included 135 children with cerebral motor impairment. Their motor development was followed-up over a one-year period by use of structured interview with the children's mothers after 12-month rehabilitation. The course of rehabilitation was assessed by the method of locomotor system functional evaluation. The improvement achieved in motor development was significantly better in the group of children whose mothers found their relationships with extended family excellent than in those whose mothers considered it good or poor. The study showed that mothers to children with cerebral motor impairment frequently feel the lack of extended family support, being it real or perceived as such by the mothers due to their emotional sensitivity, suggesting the need of additional studies of the reasons for this. These findings indicate that greater attention should be paid by health professionals to the psychological support offered to these mothers. 相似文献
86.
We examined the influence of parental age on life history traits of their offspring in the lines of bean weevil that have
evolved different rates of senescence. Measurements included preadult traits (egg size, embryonic developmental time, total
preadult developmental time, preadult viability) and adult traits (body weight, total realized fecundity of females, first
day of egg laying, early fecundity, late fecundity and longevity). The negative parental age effects were observed for all
traits except for the early and total realized fecundity. We did not detect statistically significant line×parental age interactions
for either preadult- or adult-survival, so offspring survival did not change with parental age after selection for early vs.
late reproduction. It seems that selection acting on the quality of offspring produced by parents of different ages has not
been responsible for the evolution of senescence in bean weevil.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
87.
The human copper-transporting ATPases (Cu-ATPases) are essential for dietary copper uptake, normal development and function of the CNS, and regulation of copper homeostasis in the body. In a cell, Cu-ATPases maintain the intracellular concentration of copper by transporting copper into intracellular exocytic vesicles. In addition, these P-type ATPases mediate delivery of copper to copper-dependent enzymes in the secretory pathway and in specialized cell compartments such as secretory granules or melanosomes. The multiple functions of human Cu-ATPase necessitate complex regulation of these transporters that is mediated through the presence of regulatory domains in their structure, posttranslational modification and intracellular trafficking, as well as interactions with the copper chaperone Atox1 and other regulatory molecules. In this review, we summarize the current information on the function and regulatory mechanisms acting on human Cu-ATPases ATP7A and ATP7B. Brief comparison with the Cu-ATPase orthologs from other species is included. 相似文献
88.
Effects of Alkylphosphates and Nitrous Oxide on Microbial Degradation of Polycyclic Aromatic Hydrocarbons 总被引:2,自引:0,他引:2
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Bill W. Bogan Lisa M. Lahner Vesna Trbovic Ann M. Szajkovics J. Robert Paterek 《Applied microbiology》2001,67(5):2139-2144
We conducted a series of liquid-culture experiments to begin to evaluate the abilities of gaseous sources of nitrogen and phosphorus to support biodegradation of polycyclic aromatic hydrocarbons (PAHs). Nutrients examined included nitrous oxide, as well as triethylphosphate (TEP) and tributylphosphate (TBP). Cultures were established using the indigenous microbial populations from one manufactured gas plant (MGP) site and one crude oil-contaminated drilling field site. Mineralization of phenanthrene was measured under alternative nutrient regimes and was compared to that seen with ammoniacal nitrogen and PO4. Parallel cultures were used to assess removal of a suite of three- to five-ring PAHs. In summary, the abilities of the different communities to degrade PAH when supplemented with N2O, TEP, and TBP were highly variable. For example, in the MGP soil, organic P sources, especially TBP, supported a considerably higher degree of removal of low-molecular-weight PAHs than did PO4; however, loss of high-molecular-weight compounds was impaired under these conditions. The disappearance of most PAHs was significantly less in the oil field soil when organophosphates were used. These results indicate that the utility of gaseous nutrients for PAH bioremediation in situ may be limited and will very likely have to be assessed on a case-by-case basis. 相似文献
89.
90.
Chromium uptake bySaccharomyces cerevisiae and isolation of glucose tolerance factor from yeast biomass 总被引:2,自引:0,他引:2
Vlatka Gulan Zetic Vesna Stehlik-Tomas Slobodan Grba Lavoslav Lutilsky Damir Kozlek 《Journal of biosciences》2001,26(2):217-223
Fermentations with yeastSaccharomyces cerevisiae in semiaerobic and in static conditions with the addition of chromic chloride into the used molasses medium were analysed.
It was proved that the addition of optimal amounts of CrCl3 into the basal medium enhanced the kinetics of alcohol fermentations. The addition of 200 mg/l CrCl3 into the medium stimulated both the yeast growth and the ethanol production in all experimental conditions. On the other
hand, the results showed that Cr3+ ions were incorporated into yeast cells during fermentation. Under these conditions the accumulation of Cr3+ ions was performed by yeast cells during the exponential growth phase, and with enriched amounts of 30–45 (μg/gd.m. of cells.
Yeast biomass enriched with chromium ions was extracted with 01 mol/l NH4OH assuming that the extracts had the glucose tolerance factor (GTF). Then the extracts were passed through a gel-filtration
column in order to isolate and purify the GTF. The presence of GTF in the purified fractions was determined by measuring the
absorbance at 260 nm.
It is evident from the obtained results that the added purified fractions enhanced the rates of CO2 production as well as the glucose utilization during alcoholic fermentation. As expected, the enhancement of both rates depended
on the amounts of extracts added to the fermentation substrate. Thus, it is evident that purified extracts contained the GTF
compound, and that Cr3+ ions were bonded to the protein molecule. 相似文献