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991.
James J. Smith Thomas H.Q. Powell Luis Teixeira William O. Armstrong Robert J. McClowry Rufus Isaacs Glen R. Hood Jeffrey L. Feder Larry Gut 《Entomologia Experimentalis et Applicata》2014,150(2):157-165
The cherry fruit fly (CFF), Rhagoletis cingulata Loew (Diptera: Tephritidae: Trypetini), is endemic to eastern North America and Mexico, where its primary native host is black cherry [Prunus serotina Ehrh. (Rosaceae)]. Cherry fruit fly is also a major economic pest of the fruit of cultivated sweet (Prunus avium L.) and tart (Prunus cerasus L.) cherries. Adult CFF that attack wild black cherry and introduced, domesticated cherries in commercial and abandoned orchards are active at different times of the summer, potentially generating allochronic isolation that could genetically differentiate native from sweet and tart CFF populations. Here, we test for host‐related genetic differences among CFF populations in Michigan attacking cherries in managed, unmanaged, and native habitats by scoring flies for 10 microsatellite loci. Little evidence for genetic differentiation was found across the three habitats or between the northern and southern Michigan CFF populations surveyed in the study. Local gene flow between native black cherry, commercial, and abandoned orchards may therefore be sufficient to overcome seasonal differences in adult CFF activity and prevent differentiation for microsatellites not directly associated with (tightly linked to) genes affecting eclosion time. The results do not support the existence of host‐associated races in CFF and imply that flies attacking native, managed, and unmanaged cherries should be considered to represent a single population for pest management purposes. 相似文献
992.
Telomeres are specialized nucleoprotein complexes that provide protection to the ends of eukaryotic chromosomes. Telomeric DNA consists of tandemly repeated G-rich sequences that terminate with a 3′ single-stranded overhang, which is important for telomere extension by the telomerase enzyme. This structure, as well as most of the proteins that specifically bind double and single-stranded telomeric DNA, are conserved from yeast to humans, suggesting that the mechanisms underlying telomere identity are based on common principles. The telomeric 3′ overhang is generated by different events depending on whether the newly synthesized strand is the product of leading- or lagging-strand synthesis. Here, we review the mechanisms that regulate these processes at Saccharomyces cerevisiae and mammalian telomeres. 相似文献
993.
It is well understood that helminth infections modulate the immune responses of their hosts but the mechanisms involved in this modulation are not fully known. Macrophages and dendritic cells appear to be consistently affected during this type of infection and are common target cells for helminth-derived molecules. In this report, we show that macrophages obtained from chronically Taenia crassiceps-infected mice displayed an impaired response to recombinant murine IFN-γ, but not to recombinant murine IL-4, as measured based on the phosphorylation of STAT1 and STAT6, respectively. These macrophages expressed high levels of SOCS3. However, the inhibition of phosphatase activity by orthovanadate restored the IFN-γ response of these macrophages by increasing STAT1 phosphorylation without affecting SOCS3 expression. Therefore, we aimed to identify the phosphatases associated with IFN-γ signaling inhibition and found that macrophages from T. crassiceps-infected mice displayed enhanced SHP-1 expression. Interestingly, the exposure of naïve macrophages to T. crassiceps excreted/secreted products similarly interfered with IFN-γ-induced STAT1 phosphorylation. Moreover, macrophages exposed to T. crassiceps excreted/secreted products expressed high levels of SOCS3 as well as SHP-1. Strikingly, human peripheral blood mononuclear cells that were exposed to T. crassiceps excreted/secreted products in vitro also displayed impaired STAT1 phosphorylation in response to IFN-γ; again, phosphatase inhibition abrogated the T. crassiceps excreted/secreted product-altered IFN-γ signaling. These data demonstrate a new mechanism by which helminth infection and the products derived during this infection target intracellular pathways to block the response to inflammatory cytokines such as IFN-γ in both murine and human cells. 相似文献
994.
Renata Plocinska Luis Martinez Purushotham Gorla Emmanuel Pandeeti Krishna Sarva Ewelina Blaszczyk Jaroslaw Dziadek Murty V. Madiraju Malini Rajagopalan 《Journal of bacteriology》2014,196(23):4120-4129
The septal association of Mycobacterium tuberculosis MtrB, the kinase partner of the MtrAB two-component signal transduction system, is necessary for the optimal expression of the MtrA regulon targets, including ripA, fbpB, and ftsI, which are involved in cell division and cell wall synthesis. Here, we show that MtrB, irrespective of its phosphorylation status, interacts with Wag31, whereas only phosphorylation-competent MtrB interacts with FtsI. We provide evidence that FtsI depletion compromises the MtrB septal assembly and MtrA regulon expression; likewise, the absence of MtrB compromises FtsI localization and, possibly, FtsI activity. We conclude from these results that FtsI and MtrB are codependent for their activities and that FtsI functions as a positive modulator of MtrB activation and MtrA regulon expression. In contrast to FtsI, Wag31 depletion does not affect MtrB septal assembly and MtrA regulon expression, whereas the loss of MtrB increased Wag31 localization and the levels of PknA/PknB (PknA/B) serine-threonine protein kinase-mediated Wag31 phosphorylation. Interestingly, we found that FtsI decreased levels of phosphorylated Wag31 (Wag31∼P) and that MtrB interacted with PknA/B. Overall, our results indicate that MtrB interactions with FtsI, Wag31, and PknA/B are required for its optimal localization, MtrA regulon expression, and phosphorylation of Wag31. Our results emphasize a new role for MtrB in cell division and cell wall synthesis distinct from that regulating the MtrA phosphorylation activities. 相似文献
995.
Laureano Castro Luis Castro-Nogueira Miguel A. Castro-Nogueira Miguel A. Toro 《Biology & philosophy》2010,25(3):347-360
Humans have developed the capacity to approve or disapprove of the behavior of their children and of unrelated individuals.
The ability to approve or disapprove transformed social learning into a system of cumulative cultural inheritance, because
it increased the reliability of cultural transmission. Moreover, people can transmit their behavioral experiences (regarding
what can and cannot be done) to their offspring, thereby avoiding the costs of a laborious, and sometimes dangerous, evaluation
of different cultural alternatives. Our thesis is that, during ontogeny, the evaluative communication (approval/disapproval)
between parents and offspring is substituted by other evaluative communications among peers, like individuals of the same
generation. Each person belongs to a reference social group with individuals that interact more intensively. Humans have developed
psychological mechanisms that enable cultural transmission by being receptive to parental advice as well as their reference
social group. The selective pressure that promoted these new evaluative interactions arose to facilitate the establishment
of efficient cooperative relationships. In short, the social control of behavior is essential to understand human cultural
transmission. 相似文献
996.
Leonardo D. Bacigalupe Diego M. Bustamante Francisco Bozinovic Roberto F. Nespolo 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2010,180(2):293-299
A major goal of evolutionary physiology is to understand the intrinsic and the extrinsic factors that impose limitations on
an animal’s energy budget. Although natural selection acts upon organismal traits such as performance (e.g., burst, sustained
metabolic rates), from a mechanistic perspective, organismal performance results from the integrated functioning of different
levels of biological organization. Hence, a better understanding of whole-animal performance must necessarily incorporate
an explicit analysis of the integration between those different levels. Although this topic has been under intense scrutiny,
overall there have been very few consistent patterns. Here, we explore the phenotypic integration between organ masses and
the overall energy budget under routine capacities by statistically decomposing the covariance matrix (using path analysis
and canonical correlation analysis) between organ masses and thermoregulatory burst and sustained metabolisms in cold acclimated
individuals of Phyllotis darwini. Our results suggest that (a) central organs associated with the processing of food (cecum and liver), residuals (kidneys)
and pumping of O2 (heart) are tightly integrated to sustained expenditure and between themselves; (b) with the exception of the heart, central
energy supplying organs are weakly related to burst expenditures; (c) sustained and burst metabolisms refer to complete different
strategies and (d) basal metabolic rate is not related to any of the physiological or morphological traits considered in this
study. Overall, our results support the hypothesis of an economic phenotype: animals maintain their excess capacities to face
those critical extreme events, but their physiology and internal morphology are tightly integrated to function under routine
needs. 相似文献
997.
Marta Rodríguez-Sáiz Juan Luis de la Fuente José Luis Barredo 《Applied microbiology and biotechnology》2010,88(3):645-658
Astaxanthin is a red xanthophyll (oxygenated carotenoid) with large importance in the aquaculture, pharmaceutical, and food
industries. The green alga Haematococcus pluvialis and the heterobasidiomycetous yeast Xanthophyllomyces dendrorhous are currently known as the main microorganisms useful for astaxanthin production at the industrial scale. The improvement
of astaxanthin titer by microbial fermentation is a requirement to be competitive with the synthetic manufacture by chemical
procedures, which at present is the major source in the market. In this review, we show how the isolation of new strains of
X. dendrorhous from the environment, the selection of mutants by the classical methods of random mutation and screening, and the rational
metabolic engineering, have provided improved strains with higher astaxanthin productivity. To reduce production costs and
enhance competitiveness from an industrial point of view, low-cost raw materials from industrial and agricultural origin have
been adopted to get the maximal astaxanthin productivity. Finally, fermentation parameters have been studied in depth, both
at flask and fermenter scales, to get maximal astaxanthin titers of 4.7 mg/g dry cell matter (420 mg/l) when X. dendrorhous was fermented under continuous white light. The industrial scale-up of this biotechnological process will provide a cost-effective
method, alternative to synthetic astaxanthin, for the commercial exploitation of the expensive astaxanthin (about $2,500 per
kilogram of pure astaxanthin). 相似文献
998.
999.
Torregrosa-Hetland CJ Villanueva J López-Font I Garcia-Martinez V Gil A Gonzalez-Vélez V Segura J Viniegra S Gutiérrez LM 《Cellular and molecular neurobiology》2010,30(8):1315-1319
In chromaffin cells, SNARE proteins, forming the basic exocytotic machinery are present in membrane clusters of 500–600 nm
in diameter. These microdomains containing both SNAP-25 and syntaxin-1 are dynamic and the expression of altered forms of
SNAREs modifies not only their motion but also the mobility of the associated granules. It is also clear that SNARE microdomain
location defines the place for individual vesicle fusion and that the alteration of cluster dynamics affects the fusion process
itself. Interestingly, these SNARE patches colocalize with the borders of F-actin cages forming the cytoskeletal cortical
network, and these borders also contain clusters of L- and P/Q type calcium channels. The organization of the secretory machinery
in association with the borders of cytoskeletal cages seems to be an effective way to promote fast coupling between calcium
entry and catecholamine release as demonstrated with the use of mathematical secretory models. 相似文献
1000.