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131.
Antonella De Jaco Michael Z. Lin Noga Dubi Davide Comoletti Meghan T. Miller Shelley Camp Mark Ellisman Margaret T. Butko Roger Y. Tsien Palmer Taylor 《The Journal of biological chemistry》2010,285(37):28674-28682
Despite great functional diversity, characterization of the α/β-hydrolase fold proteins that encompass a superfamily of hydrolases, heterophilic adhesion proteins, and chaperone domains reveals a common structural motif. By incorporating the R451C mutation found in neuroligin (NLGN) and associated with autism and the thyroglobulin G2320R (G221R in NLGN) mutation responsible for congenital hypothyroidism into NLGN3, we show that mutations in the α/β-hydrolase fold domain influence folding and biosynthetic processing of neuroligin3 as determined by in vitro susceptibility to proteases, glycosylation processing, turnover, and processing rates. We also show altered interactions of the mutant proteins with chaperones in the endoplasmic reticulum and arrest of transport along the secretory pathway with diversion to the proteasome. Time-controlled expression of a fluorescently tagged neuroligin in hippocampal neurons shows that these mutations compromise neuronal trafficking of the protein, with the R451C mutation reducing and the G221R mutation virtually abolishing the export of NLGN3 from the soma to the dendritic spines. Although the R451C mutation causes a local folding defect, the G221R mutation appears responsible for more global misfolding of the protein, reflecting their sequence positions in the structure of the protein. Our results suggest that disease-related mutations in the α/β-hydrolase fold domain share common trafficking deficiencies yet lead to discrete congenital disorders of differing severity in the endocrine and nervous systems. 相似文献
132.
Hoover SE Higo HA Winston ML 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2006,176(1):55-63
We examined the effect of larval and adult nutrition on worker honey bee (Apis mellifera L.) ovary development. Workers were fed high or low-pollen diets as larvae, and high or low-protein diets as adults. Workers
fed low-protein diets at both life stages had the lowest levels of ovary development, followed by those fed high-protein diets
as larvae and low- quality diets as adults, and then those fed diets poor in protein as larvae but high as adults. Workers
fed high-protein diets at both life stages had the highest levels of ovary development. The increases in ovary development
due to improved dietary protein in the larval and adult life stages were additive. Adult diet also had an effect on body mass.
The results demonstrate that both carry-over of larval reserves and nutrients acquired in the adult life stage are important
to ovary development in worker honey bees. Carry-over from larval development, however, appears to be less important to adult
fecundity than is adult nutrition. Seasonal trends in worker ovary development and mass were examined throughout the brood
rearing season. Worker ovary development was lowest in spring, highest in mid-summer, and intermediate in fall. 相似文献
133.
134.
Winnier DA Rainwater DL Cole SA Dyer TD Blangero J Maccluer JW Mahaney MC 《Human biology; an international record of research》2006,78(3):341-352
Paraoxonase 1 (PON1), a high-density-lipoprotein-associated enzyme known to protect against cellular damage from toxic agents, may also have antioxidant properties. Although the importance of the influence of the PON1 structural locus on chromosome 7q21-22 for variation in the concentration and activity of the enzyme is well-documented, the contribution of other loci is poorly understood. Based on the recent observations of at least one additional quantitative trait locus (QTL) for PON1 activity in pedigreed baboons, we conducted a whole-genome linkage screen for QTLs other than the PON1 structural locus that may influence PON1 activity in humans. We measured PON1 activity in frozen serum for 1,406 individuals in more than 40 extended pedigrees from the San Antonio Family Heart Study (SAFHS). We used a maximum-likelihood-based variance decomposition approach implemented in SOLAR to test for QTLs that may influence PON1 activity. In addition to a QTL for which we detected the strongest, significant evidence (LOD = 31.41) at or near the PON1 structural locus on chromosome 7q21-22, we also localized at least one additional significant QTL on chromosome 12 (LOD = 3.56). Furthermore, we detected suggestive evidence for two more PON-related QTLs on chromosomes 17 and 19. We have provided evidence that other genes, in addition to the well-known ones on chromosome 7, play a role in influencing normal variation in PON1 activity. 相似文献
135.
Nutrient limitation of phytoplankton communities in Subarctic lakes and ponds in Wapusk National Park, Canada 总被引:1,自引:0,他引:1
We determined the limiting nutrient of phytoplankton in 21 lakes and ponds in Wapusk National Park, Canada, using nutrient
enrichment bioassays to assess the response of natural phytoplankton communities to nitrogen and phosphorus additions. The
goal was to determine whether these Subarctic lakes and ponds were nutrient (N or P) limited, and to improve the ability to
predict future impacts of increased nutrient loading associated with climate change. We found that 38% of lakes were not limited
by nitrogen or phosphorus, 26% were co-limited by N and P, 26% were P-limited and 13% were N-limited. TN/TP, DIN/TP and NO3
−/TP ratios from each lake were compared to the Redfield ratio to predict the limiting nutrient; however, these predictors
only agreed with 29% of the bioassay results, suggesting that nutrient ratios do not provide a true measure of nutrient limitation
within this region. The N-limited lakes had significantly different phytoplankton community composition with more chrysophytes
and Anabaena sp. compared to all other lakes. N and P limitation of phytoplankton communities within Wapusk National Park lakes and ponds
suggests that increased phytoplankton biomass may result in response to increased nutrient loading associated with environmental
change. 相似文献
136.
137.
David Spooner Shelley Jansky Andrea Clausen Maria del Rosario Herrera Marc Ghislain 《Economic botany》2012,66(1):12-21
The Enigma of
Solanum maglia
in the Origin of the Chilean Cultivated Potato,
Solanum tuberosum
Chilotanum Group. Landrace potato cultivars occur in two broad geographic regions: the high Andes from western Venezuela south to northern
Argentina (Solanum tuberosum Andigenum Group, “Andigenum”), and lowland south-central Chile (S. tuberosum Chilotanum Group, “Chilotanum”), with a coastal desert and 560 km between southernmost populations of Andigenum and Chilotanum.
Unlike Andigenum landraces, Chilotanum landraces are adapted to long days and carry a 241 base pair plastid DNA deletion.
However, Andigenum and Chilotanum landraces are morphologically similar. We investigated a hypothesis that Chilotanum landraces
arose from Solanum maglia, a rare tuber-bearing species found in Chile and Argentina. This hypothesis was formulated first based on morphological analyses
of starch grains of extant and preserved (12,500 years before present) S. maglia, and on putative sympatry of extant S. maglia and Chilotanum landraces. Our new starch grain analyses fail to support this hypothesis; we could find no evidence of current
sympatric distributions, and S. maglia lacks the 241-bp plastid deletion. However, microsatellite data group all accessions of S. maglia exclusively with Chilotanum, which is supported by our previous observation at the single locus of the waxy gene. These results
could be interpreted in various ways, but all explanations have problems. One explanation is that S. maglia is a progenitor of Chilotanum. However, the plastid deletion in Chilotanum but not S. maglia cannot be easily explained. Another explanation is that Chilotanum was formed by hybridization between S. maglia and pre-Chilotanum, but this conflicts with prior cladistic analyses. These new data shed light on aspects of this question
and highlight various evolutionary scenarios, but the origin of Chilotanum and the involvement of S. maglia in its origin remain an enigma. 相似文献
138.
139.
140.
Sontag JM Nunbhakdi-Craig V White CL Halpain S Sontag E 《The Journal of biological chemistry》2012,287(18):14984-14993
The predominant brain microtubule-associated proteins MAP2 and tau play a critical role in microtubule cytoskeletal organization and function. We have previously reported that PP2A/Bα, a major protein phosphatase 2A (PP2A) holoenzyme, binds to and dephosphorylates tau, and regulates microtubule stability. Here, we provide evidence that MAP2 co-purifies with and is dephosphorylated by endogenous PP2A/Bα in bovine gray matter. It co-localizes with PP2A/Bα in immature and mature human neuronal cell bodies. PP2A co-immunoprecipitates with and directly interacts with MAP2. Using in vitro binding assays, we show that PP2A/Bα binds to MAP2c isoforms through a region encompassing the microtubule-binding domain and upstream proline-rich region. Tau and MAP2 compete for binding to and dephosphorylation by PP2A/Bα. Remarkably, the protein-tyrosine kinase Fyn, which binds to the proline-rich RTPPKSP motif conserved in both MAP2 and tau, inhibits the interaction of PP2A/Bα with either tau or MAP2c. The corresponding synthetic RTPPKSP peptide, but not the phosphorylated RpTPPKSP version, competes with Tau and MAP2c for binding to PP2A/Bα. Significantly, down-regulation of PP2A/Bα and deregulation of Fyn-Tau protein interactions have been linked to enhanced tau phosphorylation in Alzheimer disease. Together, our results suggest that PP2A/Bα is part of segregated MAP2 and tau signaling scaffolds that can coordinate the action of key kinases and phosphatases involved in modulating neuronal plasticity. Deregulation of these compartmentalized multifunctional protein complexes is likely to contribute to tau deregulation, microtubule disruption, and altered signaling in tauopathies. 相似文献