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991.
Joice AC Lyda TL Sayce AC Verplaetse E Morris MT Michels PA Robinson DR Morris JC 《International journal for parasitology》2012,42(4):401-409
The majority of the glycolytic enzymes in the African trypanosome are compartmentalised within peroxisome-like organelles, the glycosomes. Polypeptides harbouring peroxisomal targeting sequences (PTS type 1 or 2) are targeted to these organelles. This targeting is essential to parasite viability, as compartmentalisation of glycolytic enzymes prevents unregulated ATP-dependent phosphorylation of intermediate metabolites. Here, we report the surprising extra-glycosomal localisation of a PTS-2 bearing trypanosomal hexokinase, TbHK2. In bloodstream form parasites, the protein localises to both glycosomes and to the flagellum. Evidence for this includes fractionation and immunofluorescence studies using antisera generated against the authentic protein as well as detection of epitope-tagged recombinant versions of the protein. In the insect stage parasite, distribution is different, with the polypeptide localised to glycosomes and proximal to the basal bodies. The function of the extra-glycosomal protein remains unclear. While its association with the basal body suggests that it may have a role in locomotion in the insect stage parasite, no detectable defect in directional motility or velocity of cell movement were observed for TbHK2-deficient cells, suggesting that the protein may have a different function in the cell. 相似文献
992.
Meredith A. Holgerson 《Biogeochemistry》2015,124(1-3):305-318
993.
Linghe Zeng William R. Meredith Jr. Osman A. Gutiérrez Deborah L. Boykin 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2009,119(1):93-103
Genetic improvement in yield and fiber quality is needed for worldwide cotton production. Identification of molecular markers
associated with fiber-related traits can facilitate selection for these traits in breeding. This study was designed to identify
associations between SSR markers and fiber traits using an exotic germplasm population, species polycross (SP), derived from
multiple crosses among Gossypium tetraploid species. The SP population underwent 11 generations of mixed random mating and selfing followed by 12 generations
of selfing. A total of 260 lines were evaluated for fiber-related traits under three environments in 2005 and 2006. Large
genotypic variance components in traits were identified relative to components of genotype × environment. Eighty-six primer
pairs amplified a total of 314 polymorphic fragments among 260 lines. A total of 202 fragments with above 6% allele frequency
were analyzed for associations. Fifty-nine markers were found to have a significant (P < 0.05, 0.01, or 0.001) association with six fiber traits. There were six groups identified within the population using structure
analysis. Allele frequency divergence among six groups ranged from 0.11 to 0.27. Of the 59 marker–trait associations, 39 remained
significant after correction for population structure and kinship using a mixed linear model. The effect of population sub-structure
on associations was most significant in boll weight among the traits analyzed. The sub-structure among the SP lines may be
caused by natural selection, the breeding method applied during development of inbred lines, and unknown factors. The identified
marker–trait associations can be useful in breeding and help determine genetic mechanisms underlying interrelationships among
fiber traits.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
994.
Fischer BM Cuellar JG Diehl ML deFreytas AM Zhang J Carraway KL Voynow JA 《American journal of physiology. Lung cellular and molecular physiology》2003,284(4):L671-L679
In chronic obstructive pulmonary diseases, the airway epithelium is chronically exposed to neutrophil elastase, an inflammatory protease. The cellular response to neutrophil elastase dictates the balance between epithelial injury and repair. Key regulators of epithelial migration and proliferation are the ErbB receptor tyrosine kinases, including the epidermal growth factor receptor. In this context, we investigated whether neutrophil elastase may regulate expression of MUC4, a membrane-tethered mucin that has recently been identified as a ligand for ErbB2, the major heterodimerization partner of the epidermal growth factor receptor. In normal human bronchial epithelial cells, neutrophil elastase increased MUC4 mRNA levels in both a concentration- and time-dependent manner. RNA stability assays revealed that neutrophil elastase increased MUC4 mRNA levels by prolonging the mRNA half-life from 5 to 21 h. Neutrophil elastase also increased MUC4 glycoprotein levels as determined by Western analysis, using a monoclonal antibody specific for a nontandem repeat MUC4 sequence. Therefore, airway epithelial cells respond to neutrophil elastase exposure by increasing expression of MUC4, a potential activator of epithelial repair mechanisms. 相似文献
995.
In humans, the storage and voiding functions of the urinary bladder have a characteristic diurnal variation, with increased voiding during the day and urine storage during the night. However, in animal models, the daily functional differences in urodynamics have not been well-studied. The goal of this study was to identify key urodynamic parameters that vary between day and night. Rats were chronically instrumented with an intravesical catheter, and bladder pressure, voided volumes, and micturition frequency were measured by continuous filling cystometry during the light (inactive) or dark (active) phases of the circadian cycle. Cage activity was recorded by video during the experiment. We hypothesized that nocturnal rats entrained to a standard 12:12 light:dark cycle would show greater ambulatory activity and more frequent, smaller volume micturitions in the dark compared to the light. Rats studied during the light phase had a bladder capacity of 1.44±0.21 mL and voided every 8.2±1.2 min. Ambulatory activity was lower in the light phase, and rats slept during the recording period, awakening only to urinate. In contrast, rats studied during the dark were more active, had a lower bladder capacities (0.65±0.18 mL), and urinated more often (every 3.7±0.9 min). Average bladder pressures were not significantly different between the light and dark (13.40±2.49 and 12.19±2.85 mmHg, respectively). These results identify a day-night difference in bladder capacity and micturition frequency in chronically-instrumented nocturnal rodents that is phase-locked to the normal circadian locomotor activity rhythm of the animal. Furthermore, since it has generally been assumed that the daily hormonal regulation of renal function is a major driver of the circadian rhythm in urination, and few studies have addressed the involvement of the lower urinary tract, these results establish the bladder itself as a target for circadian regulation. 相似文献
996.
The transport of HRP (horseradish peroxidase) from the nasalcavity to the brain by intact olfactory receptor axons was usedto investigate the effectiveness of methods commonly used inbehavioral studies for deafferenting nasal chemoreceptor systems.The HRP experiments demonstrated that routine intranasal lavagewith zinc sulfate solution fails to destroy all olfactory receptorneurons in hamsters, in spite of the distinct behavioral deficitthat this treatment can cause in the male hamster. The intracranialdeafferentation of the accessory olfactory bulb by surgicalsection of the vomeronasal nerves was generally effective butthere was much incidental damage to main olfactory nerves thatwould probably not be detected without the HRP tracer. The distribution pattern of HRP molecules introduced into themammalian nasal cavity, as shown by the uptake of HRP by nasalchemoreceptors and its transport to the brain, was also usedto identify potential pathways for non-volatile stimulus moleculeswithin the nose. HRP reaction product was reliably detectedin the glomeruli of the main olfactory bulb after HRP was depositedat the nostril, demonstrating that nonvolatile materials, oncethey have entered the nasal cavity, can reach the main olfactoryreceptor neurons in the posterior nasal epithelium. Significantamounts of HRP reaction product were never observed in the accessoryolfactory bulbunlessa large dose of epinephrine had been givento activate the vomeronasal organ pumping mechanism, which drawssubstances into the vomeronasal organ lumen. Thus, it seemsthat stimulus access to vomeronasal receptor neurons is controlledindependently of access to main olfactory receptor neurons. 相似文献
997.
Baker-Austin C McArthur JV Lindell AH Wright MS Tuckfield RC Gooch J Warner L Oliver J Stepanauskas R 《Microbial ecology》2009,57(1):151-159
Vibrio vulnificus is a serious opportunistic human pathogen commonly found in subtropical coastal waters, and is the leading cause of seafood-borne
mortality in the USA. This taxon does not sustain prolonged presence in clinical or agricultural settings, where it would
undergo human-induced selection for antibiotic resistance. Therefore, few studies have verified the effectiveness of commonly
prescribed antibiotics in V. vulnificus treatment. Here we screened 151 coastal isolates and 10 primary septicaemia isolates against 26 antimicrobial agents representing
diverse modes of action. The frequency of multiple resistances to antibiotics from all sources was unexpectedly high, particularly
during summer months, and a substantial proportion of isolates (17.3%) were resistant to eight or more antimicrobial agents.
Numerous isolates demonstrated resistance to antibiotics routinely prescribed for V. vulnificus infections, such as doxycycline, tetracycline, aminoglycosides and cephalosporins. These resistances were detected at similar
frequencies in virulent and non-virulent strains (PCR-based virulence typing) and were present in septicaemia isolates, underlying
the public health implications of our findings. Among environmental isolates, there were no consistent differences in the
frequency of resistance between pristine and anthropogenically impacted estuaries, suggesting natural rather than human-derived
sources of resistance traits. This report is the first to demonstrate prevalent antibiotic resistance in a human pathogen
with no clinical reservoirs, implying the importance of environmental studies in understanding the spread, evolution and public
health relevance of antibiotic resistance factors.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
998.
999.
Meredith Pochardt Jennifer M. Allen Ted Hart Sophie D. L. Miller Douglas W. Yu Taal Levi 《Molecular ecology resources》2020,20(2):457-467
Although environmental DNA shed from an organism is now widely used for species detection in a wide variety of contexts, mobilizing environmental DNA for management requires estimation of population size and trends in addition to assessing presence or absence. However, the efficacy of environmental‐DNA‐based indices of abundance for long‐term population monitoring have not yet been assessed. Here we report on the relationship between six years of mark‐recapture population estimates for eulachon (Thaleichthys pacificus) and “eDNA rates” which are calculated from the product of stream flow and DNA concentration. Eulachon are a culturally and biologically important anadromous fish that have significantly declined in the southern part of their range but were historically rendered into oil and traded. Both the peak eDNA rate and the area under the curve of the daily eDNA rate were highly predictive of the mark‐recapture population estimate, explaining 84.96% and 92.53% of the deviance, respectively. Even in the absence of flow correction, the peak of the daily eDNA concentration explained an astonishing 89.53% while the area under the curve explained 90.74% of the deviance. These results support the use of eDNA to monitor eulachon population trends and represent a >80% cost savings over mark‐recapture, which could be further increased with automated water sampling, reduced replication, and focused temporal sampling. Due to its logistical ease and affordability, eDNA sampling can facilitate monitoring a larger number of rivers and in remote locations where mark‐recapture is infeasible. 相似文献
1000.
The role of macroinvertebrates in the process of leaf breakdown is well studied in temperate streams, but less is known about their role in the tropics. We investigated the effect of reducing macroinvertebrate access to leaf material on leaf breakdown rates in a forested headwater stream in the Luquillo Experimental Forest, Puerto Rico. We measured leaf mass loss using fine and coarse mesh bags over 12 weeks for two common riparian species: Cecropia schreberiana (Moraceae) and Dacryodes excelsa (Burseraceae). Coarse mesh allowed freshwater shrimp and other macroinvertebrates to access leaf material, while fine mesh did not. Leaf breakdown rates did not differ between C. schreberiana and D. excelsa in coarse mesh bags (?0.0375/day vs. ?0.0395/day, respectively), but C. schreberiana breakdown was significantly slower than D. excelsa in fine mesh bags (?0.0159/day vs. ?0.0266/day). Additionally, breakdown in fine mesh bags was significantly slower compared to coarse mesh bags for C. schreberiana, but less so for D. excelsa. Breakdown rates for all treatments were fast relative to those in temperate‐zone streams indicating that both macroinvertebrates and macroinvertebrate‐independent processing can strongly influence leaf decomposition in tropical streams. The difference between C. schreberiana and D. excelsa indicates that the effect of macroinvertebrate exclusion can change with leaf type. 相似文献