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1.
A theoretical analysis of two models of the vestibulo-ocular and optokinetic systems was performed. Each model contains a filter element in the vestibular periphery to account for peripheral adaptation, and a filter element in the central vestibulooptokinetic circuit to account for central adaptation. Both models account for1 adaptation, i.e. a response decay to a constant angular acceleration input, in both peripheral vestibular afferent and vestibulo-ocular reflex (VOR) responses and2 the reversal phases of optokinetic after-nystagmus (OKAN) and the VOR and3 oscillatory behavior such as periodic alternating nystagmus. The two models differ regarding the order of their VOR transfer function. Also, they predict different OKAN patterns following a prolonged optokinetic stimulus. These models have behavioral implications and suggest future experiments. 相似文献
2.
High voltage electrical pulses were used to introduce the CAT reporter gene into cultured protoplasts of breadwheat,Triticum aestivum. Four DNA constructs harboring the CAT gene and the 35S or mannipine synthase promoter were tested for levels of CAT activity 40–45 hr after electroporation of protoplasts. One construct, containing a maize intron sequence between 35S and CAT sequences, conferred 30 to 185 fold greater CAT activity over the other three constructs. Data from these experiments suggest that a maize intron or sequences with similar effects may be required in DNA constructs for efficient heterologous gene expression in cultured cells of breadwheat.Abbreviations CAT
Chloramphenicol acetyl transferase
- NPT II
neomycin phosphotransferase
- 35S
the 35S promoter of Cauliflower Mosaic Virus
- PEG
Polyethylene glycol
- MES
2-[N-morpholino] ethanesulfonic acid 相似文献
3.
Keith Paige Melanie Palomares Patricia A. D’Amore Susan J. Braunhut 《In vitro cellular & developmental biology. Animal》1991,27(2):151-157
Summary The growth of the endothelial cell (EC) is tightly regulated throughout the body. Many factors have been implicated in modulating
EC growth including diffusible compounds, cell-to-cell interactions, and the extracellular matrix (ECM). Retinol, or vitamin
A alcohol, has recently been shown to inhibit the growth of bovine capillary ECs, in vitro. Retinoids are known to modify
ECM in other cell systems, and pure ECM components have been shown to effect EC growth rates. We, therefore, examined the
role of the matrix in the retinol-induced inhibition of ECs. Cell-free matrices from control and vitamin A-treated ECs were
prepared by removing cells with EGTA treatment after 7 d of culture. Matrix proteins were analyzed by solubilizing the matrices
in 5M quanidine-HCl and performing Western blot analysis using specific antibodies to matrix proteins. In isolating the ECM, we
observed that retinol-treated cultures of ECs were resistant to EGTA removal; retinol-treated ECs required twice the exposure
time to EGTA to detach from their matrix than did controls cells. Western blot analysis of matrix proteins derived from control
and retinol-treated EC cultures demonstrated a 1.6-fold increase in lamininβ chains and a 2.5-fold increase in fibronectin in the ECM of retinol-treated EC compared to control cell matrix. Functional
properties of these matrices were assessed by plating control and Day 6 retinol-treated ECs onto the matrices and measuring
attachment and growth by determining cell numbers at 24, 72, and 144 h. These studies revealed that control cells attached
in greatest numbers to a control matrix whereas retinol-treated ECs preferentially attached to a matrix derived from retinol-treated
cells. Furthermore, control ECs which grew rapidly on a control matrix were growth inhibited on a retinol-derived matrix.
These data indicate that vitamin A treatment of ECs effects both their phenotype and influences the composition and the functional
properties of their underlying ECM. These studies also demonstrate that alterations of the matrix are at least in part responsible
for the growth inhibition of EC by retinol. 相似文献
4.
Metabolic activation of 2-substituted derivatives of myristic acid to form potent inhibitors of myristoyl CoA:protein N-myristoyltransferase 总被引:1,自引:0,他引:1
The importance of myristoylation for the proper biological functioning of many acylated proteins has generated interest in the enzymes of the myristoylation pathway and their interactions with substrates and inhibitors. Previous observations that S-(2-oxopentadecyl)-CoA, a nonhydrolyzable methylene-bridged analogue of myristoyl-CoA, was a potent inhibitor of myristoyl-CoA:protein N-myristoyltransferase (NMT) [Paige, L. A., Zheng, G.-q., DeFrees, S. A., Cassady, J. M., & Geahlen, R. L. (1989) J. Med. Chem. 32, 1665] prompted a closer examination of the effect of substituents at the 2-position on the interactions of myristic acid and myristoyl-CoA analogues with NMT. As an initial approach, three myristic acid derivatives bearing different substituents at the 2-position, 2-fluoromyristic acid, 2-bromomyristic acid, and 2-hydroxymyristic acid, were selected for study. Both 2-bromomyristic acid and 2-hydroxymyristic acid were available commercially; 2-fluoromyristic acid was prepared synthetically. All three compounds were found to be only weak inhibitors of NMT in vitro. Of the three, 2-bromomyristic acid was the most potent (Ki = 100 microM). In cultured cells, however, 2-hydroxymyristic acid was by far the more effective inhibitor of protein myristoylation. Neither 2-hydroxymyristic acid nor 2-bromomyristic acid significantly inhibited protein palmitoylation in cultured cells, indicating that inhibition was not occurring at the level of acyl-CoA synthetase. Activation of the 2-substituted myristic acid derivatives to their corresponding acyl-CoA thioesters by acyl-CoA synthetase resulted in inhibitors of greatly increased potency. The 2-substituted acyl-CoA analogues, 2-hydroxymyristoyl-CoA, 2-bromomyristoyl-CoA, and 2-fluoromyristoyl-CoA, were synthesized and shown to be competitive inhibitors of NMT in vitro (Ki's = 45, 450, and 200 nM, respectively). These data suggested that the enhanced inhibitory potency of 2-hydroxymyristic acid seen in cells was most probably a result of its metabolic activation to the CoA thioester. The presence of substituents at the 2-position also affected the ability of the acyl group to be transferred by NMT to a peptide substrate. Of the three acyl-CoA analogues, only 2-fluoromyristoyl-CoA served as a substrate for NMT. 相似文献
5.
James Skelton Michelle A. Jusino Paige S. Carlson Katherine Smith Mark T. Banik Daniel L. Lindner Jonathan M. Palmer Jiri Hulcr 《Molecular ecology》2019,28(22):4971-4986
A prevailing paradigm in forest ecology is that wood‐boring beetles facilitate wood decay and carbon cycling, but empirical tests have yielded mixed results. We experimentally determined the effects of wood borers on fungal community assembly and wood decay within pine trunks in the southeastern United States. Pine trunks were made either beetle‐accessible or inaccessible. Fungal communities were compared using culturing and high‐throughput amplicon sequencing (HTAS) of DNA and RNA. Prior to beetle infestation, living pines had diverse fungal endophyte communities. Endophytes were displaced by beetle‐associated fungi in beetle‐accessible trees, whereas some endophytes persisted as saprotrophs in beetle‐excluded trees. Beetles increased fungal diversity several fold. Over forty taxa of Ascomycota were significantly associated with beetles, but beetles were not consistently associated with any known wood‐decaying fungi. Instead, increasing ambrosia beetle infestations caused reduced decay, consistent with previous in vitro experiments that showed beetle‐associated fungi reduce decay rates by competing with decay fungi. No effect of bark‐inhabiting beetles on decay was detected. Platypodines carried significantly more fungal taxa than scolytines. Molecular results were validated by synthetic and biological mock communities and were consistent across methodologies. RNA sequencing confirmed that beetle‐associated fungi were biologically active in the wood. Metabarcode sequencing of the LSU/28S marker recovered important fungal symbionts that were missed by ITS2, though community‐level effects were similar between markers. In contrast to the current paradigm, our results indicate ambrosia beetles introduce diverse fungal communities that do not extensively decay wood, but instead reduce decay rates by competing with wood decay fungi. 相似文献
6.
Long-term (including gestational and lactational) restriction of protein (8% of diet) significantly lowered the absolute and relative consumption of 6% ethanol (EtOH) in a two-bottle, free-choice (H2O vs EtOH) situation during a 76-day test period. This difference in response between rats fed the low protein diet and those fed an isocaloric normal protein (24%) diet became non-significant in two subsequent 100-day test periods. Statistical analysis of observations on individual performance indicated that regularity, cyclicity, and duration of drinking in each animal was random over all three time intervals for both groups. The early, significantly lower EtOH consumption by the protein-restricted group may be due to a paucity of EtOH-metabolizing enzymes in brain and liver, thereby prolonging the CNS effects of lower doses of EtOH consumed. The disappearance of this difference in subsequent test periods may reflect either a behavioral or metabolic adaptation in the developing protein-deficient rat. 相似文献
7.
8.
Alfredo Seiiti Urashima Tatiane de Fátima Mistura Lis Natali Rodrigues Porto Paige Dariel Austin Renee Silvia Arias 《Journal of Phytopathology》2020,168(10):581-590
The use of resistant genotypes is the preferred method to control orange rust of sugarcane (Saccharum spp) caused by Puccinia kuehnii. This approach has been adopted in Brazil but outbreaks of the disease on previously resistant varieties showed that the efficacy of this method is limited and requires a better understanding of pathogen diversity. Nevertheless, adequate molecular markers for examining pathogen diversity at population level are not available, which limits the success of orange rust control by genetic resistance. Therefore, two independent investigations were conducted to examine genetic diversity of P. kuehnii from São Paulo state, the most important sugarcane growing state of Brazil. First, simple-sequence repeat (SSR) markers were developed in the present work and genotypic diversity of orange rust isolates from different locations investigated. Second, phenotypic diversity was examined by the single-pustule inoculation technique on P. kuehnii isolates retrieved from three susceptible commercial sugarcane cultivars. A total of 96 SSR markers were generated and tested for this species. Subsequently, 29 isolates of P. kuehnii were fingerprinted with nine SSR markers to estimate the genotypic diversity by neighbour-joining and 3D principal coordinates. The 29 isolates of the pathogen clustered into four main groups, which were identified by three SSR markers (NPRL_PK_108a, NPRL_PK_162_spka and NPRL_PK_221_spka). Phenotypic data at 21 days after the single-pustule inoculation showed that P. kuehnii from highly susceptible commercial cultivars harboured a small proportion of variants capable of causing disease on resistant cultivars. A differential reaction was demonstrated for the most virulent variant in a repeated experiment confirming the existence of races within P. kuehnii in Brazil. 相似文献
9.
Maren de Vries Adil S. Mohamed Rachel A. Prescott Ana M. Valero-Jimenez Ludovic Desvignes Rebecca OConnor Claire Steppan Joseph C. Devlin Ellie Ivanova Alberto Herrera Austin Schinlever Paige Loose Kelly Ruggles Sergei B. Koralov Annaliesa S. Anderson Joseph Binder Meike Dittmann 《Journal of virology》2021,95(10)
10.
Marcelo Marcet-Palacios Eduardo Reyes-Serratos Aron Gonshor Robert Buck Paige Lacy A. D. Befus 《Journal of cellular biochemistry》2020,121(12):4945-4958
Recently, we detected a novel biomarker in human saliva called calcium-binding protein, spermatid-associated 1 (CABS1). CABS1 protein had previously been described only in testis, and little was known of its characteristics other than it was considered a structurally disordered protein. Levels of human CABS1 (hCABS1) in saliva correlate with stress, whereas smaller sized forms of hCABS1 in saliva are associated with resilience to stress. Interestingly, hCABS1 also has an anti-inflammatory peptide sequence near its carboxyl terminus, similar to that of a rat prohormone, submandibular rat 1. We performed phylogenetic and sequence analysis of hCABS1. We found that from 72 CABS1 sequences currently annotated in the National Center for Biotechnology Information protein database, only 14 contain the anti-inflammatory domain “TxIFELL,” all of which are primates. We performed structural unfoldability analysis using PONDER and FoldIndex and discovered three domains that are highly disordered. Predictions of three-dimensional structure of hCABS1 using RaptorX, IonCom, and I-TASSER software agreed with these findings. Predicted neutrophil elastase cleavage density also correlated with hCABS1 regions of high structural disorder. Ligand binding prediction identified Ca2+, Mg2+, Zn2+, leucine, and thiamine pyrophosphate, a pattern observed in enzymes associated with energy metabolism and mitochondrial localization. These new observations on hCABS1 raise intriguing questions about the interconnection between the autonomic nervous system, stress, and the immune system. However, the precise molecular mechanisms involved in the complex biology of hCABS1 remain unclear. We provide a detailed in silico analysis of relevant aspects of the structure and function of hCABS1 and postulate extracellular and intracellular roles. 相似文献