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151.
Molecular evolution of the period gene in Drosophila athabasca 总被引:1,自引:0,他引:1
We measured nucleotide variability within and between the three semispecies
of the Drosophila athabasca complex, at the period (per) gene by using a
polymerase chain reaction-based four-cutter restriction- enzyme analysis.
The levels of polymorphism varied considerably between the three
semispecies. Our results for per, combined with previous data for X-linked
allozymes, suggest that the X chromosome in the western- northern
semispecies is less variable than expected under an equilibrium-neutral
model. Both the pattern of divergence between the semispecies and a
cladistic clustering of per haplotypes support the previously hypothesized
grouping of eastern A and eastern B as the two most recently diverged
semispecies. A 21-bp in-frame segment in the region of per which shares
sequence similarity with the neuronal development gene single minded is
deleted in all eastern A and eastern B flies examined but is present in all
of the western-northern flies and all other published per sequences.
Despite these hints that there may be significant differences at the per
gene between the semispecies, especially the western-northern group versus
the two eastern groups, there is no compelling evidence that per is
involved in the mating song differences between the semispecies.
相似文献
152.
The benefits of programmed cell death by apoptosis are the safe and efficient clearance of damaged, infected, or surplus cells,
primarily mediated by tissue-resident macrophages or tissue-infiltrating blood monocytes that differentiate into macrophages.
Microglial cells are macrophages of the brain parenchyma, important immune surveillance cells that respond to various injuries
and diseases of the brain. It is often stated that how a macrophage interacts with an apoptotic cell defines subsequent inflammatory
responses, i.e., will engulfment be beneficial or detrimental for tissue repair, regeneration, and immunity. Our focus has
been to better understand how macrophages discriminate between living and dying cells. Following our initial findings with
platelet endothelial cell adhesion molecule (PECAM)-1, our studies have revealed a key role for potassium ion permeability
in regulating integrin-dependent binding of apoptotic cells by macrophages and their subsequent response to proinflammatory
stimuli. Specifically, apoptotic cells represent a depolarizing stimulus for macrophages where PECAM-1-mediated cell–cell
interactions delay subsequent membrane repolarization. It is salient that potassium leak represents an early feature of cells
destined to die by apoptosis that could trigger depolarization of macrophages that lie in close apposition. We speculate that
how a tissue-resident macrophage responds to strong depolarizing stimuli has wider implications for inflammation and autoimmunity. 相似文献
153.
154.
Temporal separation of steps in the biosynthesis of verruculogen 总被引:2,自引:0,他引:2
A mixture of 2[3H] mevalonate and U[14C] proline, given to Penicillium simplicissimum on days 2, 3, 4, 5 or 6 of stationary liquid culture, gave rise to radiolabelled verruculogen in which the ratio of 3H to 14C measured on day 8 increased from 2.0:1 to 9.5:1 over the period of administration of radiolabelled precursors. This suggests temporal separation of the formation of the diketopiperazine moiety and its subsequent prenylation. The putative precursor diketopiperazine, cyclo-L-tryptophanyl-L-proline, was isolated from 21 day culture broth. 相似文献
155.
Post-translational modifications (PTMs) such as phosphorylation and ubiquitination are well-studied events with a recognized importance in all aspects of cellular function. By contrast, protein S-acylation, although a widespread PTM with important functions in most physiological systems, has received far less attention. Perturbations in S-acylation are linked to various disorders, including intellectual disability, cancer and diabetes, suggesting that this less-studied modification is likely to be of considerable biological importance. As an exemplar, in this review, we focus on the newly emerging links between S-acylation and the hormone insulin. Specifically, we examine how S-acylation regulates key components of the insulin secretion and insulin response pathways. The proteins discussed highlight the diverse array of proteins that are modified by S-acylation, including channels, transporters, receptors and trafficking proteins and also illustrate the diverse effects that S-acylation has on these proteins, from membrane binding and micro-localization to regulation of protein sorting and protein interactions. 相似文献
156.
Cyclins are indispensable elements of the cell cycle and derangement of their function can lead to cancer formation. Recent studies have also revealed more mechanisms through which cyclins can express their oncogenic potential. This review focuses on the aberrant expression of G1/S cyclins and especially cyclin D and cyclin E; the pathways through which they lead to tumour formation and their involvement in different types of cancer. These elements indicate the mechanisms that could act as targets for cancer therapy. 相似文献
157.
Annemijn Vis Jan CAM Lammers Roel de Vroege Martijn MJ van Nieuwburg Marlijn S Jansen Joyce MJ Visser Bart Meuris Paul F Gründeman Jolanda Kluin 《Comparative medicine》2021,71(3):235
Sheep are a commonly used and validated model for cardiovascular research and, more specifically, for heart valve research. Implanting a heart valve on the arrested heart in sheep is complex and is often complicated by difficulties in restarting the heart, causing significant on-table mortality. Therefore, optimal cardioprotective management during heart valve implantation in sheep is essential. However, little is known about successful cardioprotective management techniques in sheep. This article reports our experience in the cardioprotective management of 20 female sheep that underwent surgical aortic valve replacement with a stented tissue-engineered heart valve prosthesis. During this series of experiments, we modified our cardioprotection protocol to improve survival. We emphasize the importance of total body hypothermia and external cooling of the heart. Furthermore, we recommend repeated cardioplegia administration at 20 min intervals during surgery, with the final dosage of cardioplegia given immediately before the de-clamping of the aorta. To reduce the number of defibrillator shocks during a state of ventricular fibrillation (VF), we have learned to restart the heart by reclamping the aorta, administering cardioplegia until cardiac arrest, and de-clamping the aorta thereafter. Despite these encouraging results, more research is needed to finalize a protocol for this procedure.Sheep are a commonly used and well-validated model for cardiovascular research, particularly for heart valve research, as blood pressure, heart rate, cardiac output, and intracardiac pressures are similar between sheep and humans. Sheep are particularly useful for heart valve research because observable changes in implanted heart valve bioprostheses that would take several years to develop in humans are apparent after only a few months in sheep.3,11 This feature allows the ovine model to provide relevant and important information about heart valve prostheses in a relatively short time span. The first preclinical step in developing novel heart valves is to test the valve in the pulmonary position in sheep. This surgical technique is relatively easy, as the procedure can be performed on a beating heart in a low-pressure circulation. However, aortic valve surgery is the most frequently performed valvular surgical intervention in human patients.12 Thus, an important next step is to prove the clinical applicability of a new valve by testing the valve in-vivo in the aortic position in an animal model. In contrast to pulmonary valve replacement, aortic valve replacement must be performed on an arrested heart, which makes the surgical procedure significantly more complex. The sheep is a difficult model for aortic valve replacements due to its narrow annulus, short distance between the annulus and coronary ostia, a short ascending aorta, and difficulty in de-airing of the heart prior to suturing the aortotomy.19 Consequently, high on-table mortality rates, ranging from 9% to 33%, have been reported.1,18,21,24 Furthermore, the incidence of mortality during the first 30 d after surgery, directly related to the surgical procedure, is often high, ranging from 17% to 50%.1,2,16,18,21 Therefore, optimizing cardioprotective strategies during surgery would improve postoperative survival. However, little is known about protective strategies in sheep. In the current series of experiments, we implanted stented, tissue engineered, aortic heart valve prostheses in 20 adult domestic sheep and developed cardioprotective techniques to increase survival rates. In this observational study, we share our experience and insights regarding cardioprotective management to potentially improve the outcome of future surgeries that require an arrested heart in sheep. 相似文献