oscillation

振荡
  • 文章类型: Journal Article
    复杂血管网络的形成和组织依赖于各种生物物理力,然而,在不同的机械输入下内皮细胞-细胞相互作用的机制尚不清楚。以斑马鱼背侧纵行吻合血管(DLAV)为模型,我们研究了多种生物物理输入和脑海绵状畸形(CCM)相关基因在血管生成中的作用.我们的研究确定了heg1和krit1(ccm1)对于吻合过程中内皮细胞-细胞界面的形成至关重要。在这些基因的突变体中,细胞-细胞界面与片段化的顶端结构域纠缠在一起。Heg1活报告子证明Heg1动态参与沿细胞-细胞连接的振荡收缩,而Myosin的活记者表明,heg1和krit1突变体在这些连接点上缺乏肌动球蛋白的收缩性。在野生型胚胎中,连接处的振荡收缩力通过拉直连接处并消除过多的细胞-细胞界面来改善内皮细胞-细胞相互作用。相反,在没有交界收缩力的情况下,细胞-细胞界面变得纠缠在两个突变体中容易崩溃,防止形成连续的管腔。通过光遗传学激活RhoA来恢复交界收缩性,扭曲的连接被拉直和解开。此外,血液动力学力在解决野生型和突变胚胎中纠缠的细胞-细胞界面时补充了肌动球蛋白的收缩力。总的来说,我们的研究表明,由Heg1和Krit1控制的振荡收缩力对于维持适当的内皮细胞-细胞界面至关重要,因此对于形成连续的管腔空间,这对产生功能性脉管系统至关重要。
    The formation and organization of complex blood vessel networks rely on various biophysical forces, yet the mechanisms governing endothelial cell-cell interactions under different mechanical inputs are not well understood. Using the dorsal longitudinal anastomotic vessel (DLAV) in zebrafish as a model, we studied the roles of multiple biophysical inputs and cerebral cavernous malformation (CCM)-related genes in angiogenesis. Our research identifies heg1 and krit1 (ccm1) as crucial for the formation of endothelial cell-cell interfaces during anastomosis. In mutants of these genes, cell-cell interfaces are entangled with fragmented apical domains. A Heg1 live reporter demonstrated that Heg1 is dynamically involved in the oscillatory constrictions along cell-cell junctions, whilst a Myosin live reporter indicated that heg1 and krit1 mutants lack actomyosin contractility along these junctions. In wild-type embryos, the oscillatory contractile forces at junctions refine endothelial cell-cell interactions by straightening junctions and eliminating excessive cell-cell interfaces. Conversely, in the absence of junctional contractility, the cell-cell interfaces become entangled and prone to collapse in both mutants, preventing the formation of a continuous luminal space. By restoring junctional contractility via optogenetic activation of RhoA, contorted junctions are straightened and disentangled. Additionally, haemodynamic forces complement actomyosin contractile forces in resolving entangled cell-cell interfaces in both wild-type and mutant embryos. Overall, our study reveals that oscillatory contractile forces governed by Heg1 and Krit1 are essential for maintaining proper endothelial cell-cell interfaces and thus for the formation of a continuous luminal space, which is essential to generate a functional vasculature.
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  • 文章类型: Journal Article
    了解疼痛同理心(EFP)和工作记忆(WM)相互作用背后的机制,特别是它们如何受到社会因素的影响,如感知的社会距离(SD),对于理解人类如何动态适应复杂的社会生活至关重要。然而,人们对这些机制知之甚少。因此,我们招募了116名健康参与者来调查WM和EfP之间的双向影响和电生理反应,包括SD的作用。我们的研究结果表明,WM负荷与SD之间的相互作用显着影响了EfP的处理。具体来说,高WM负荷和远距离SD促进了EFP的早期处理。相反,低WM负荷和接近SD促进了EFP的后期处理。Further,EfP和SD之间的相互作用显着影响正在进行的WM任务的性能。具体来说,亲属的痛苦,与亲属的非疼痛相比,提高了参与者在低WM负载任务上的性能;然而,它降低了参与者在具有高WM负载的任务上的性能。总的来说,这些结果在行为和神经层面为WM和EFP在同一时间过程中的相互影响提供了证据,在这些相互影响中,SD成为一个关键的调节因素。
    Understanding the mechanisms behind the interaction of empathy for pain (EfP) and working memory (WM), particularly how they are influenced by social factors like perceived social distance (SD), is vital for comprehending how humans dynamically adapt to the complexities of social life. However, there is very little known about these mechanisms. Accordingly, we recruited 116 healthy participants to investigate the bidirectional influence and electrophysiological responses between WM and EfP, including the role of SD. Our research results revealed that the interaction between WM load and SD significantly influenced the processing of EfP. Specifically, high WM load and distant SD facilitated early processing of EfP. Conversely, low WM load and close SD promoted late processing of EfP. Further, the interaction between EfP and SD significantly influenced the performance of ongoing WM tasks. Specifically, the kin\'s pain, compared to kin\'s non-pain, improved participant\'s performance on low WM load tasks; however, it diminished participant\'s performance on tasks with high WM load. Overall, these results provide evidence at both behavioral and neural levels for the mutual influence of WM and EfP during the same temporal process, and SD emerged as a crucial moderating factor during these mutual influences.
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  • 文章类型: Journal Article
    正在进行的神经振荡反映了局部神经群体的兴奋和抑制循环,单个神经元或多或少可能会激发,具体取决于振荡阶段。因此,振荡可以确定是否感知到声音和/或其神经表示是否进入后期处理阶段。虽然对这一想法的经验支持来自声音检测研究,关于声音事件的记忆,知识仍然存在很大的差距。在目前的研究中,研究了感觉夹带如何影响音高的工作记忆表示的保真度。在两个独立的实验中,在f0在270至715Hz之间的多音调复合物之前,出现了8Hz幅度调制(AM)的夹带刺激。该“目标”声音可以在相对于先前AM的0至2π弧度的相位处呈现。在4s(实验1;n=26)或2s(实验2;n=28)的保留间隔后,听众的任务是通过沿响应板的水平轴移动手指来再现目标声音的音调。假设如果夹带调节听觉工作记忆保真度,当目标与夹带同相呈现时,目标螺距的再现将更加准确和精确。两个实验的平均数据的余弦拟合显示,音调匹配的准确性存在显着夹带“回声”。在匹配精度中没有明显的回声。个体数据准确性的拟合表明,最佳相位在个体之间是一致的,如果AM继续,则在下一个AM峰值附近对齐。结果表明,除了刺激检测外,感觉夹带还可以调节听觉工作记忆,与正在进行的神经振荡活动调节高阶听觉过程的提议一致。
    Ongoing neural oscillations reflect cycles of excitation and inhibition in local neural populations, with individual neurons being more or less likely to fire depending upon the oscillatory phase. As a result, the oscillations could determine whether or not a sound is perceived and/or whether its neural representation enters into later processing stages. While empirical support for this idea has come from sound detection studies, large gaps in knowledge still exist regarding memory for sound events. In the current study, it was investigated how sensory entrainment impacts the fidelity of working memory representations for pitch. In two separate experiments, an 8 Hz amplitude modulated (AM) entraining stimulus was presented prior to a multitone complex having an f0 between 270 and 715 Hz. This \"target\" sound could be presented at phases from 0 to 2π radians in relation to the previous AM. After a retention interval of 4 s (Experiment 1; n = 26) or 2 s (Experiment 2; n = 28), listeners were tasked to reproduce the target sound\'s pitch by moving their finger along the horizontal axis of a response pad. It was hypothesized that if entrainment modulates auditory working memory fidelity, reproductions of a target\'s pitch would be more accurate and precise when targets were presented in phase with the entrainment. Cosine fits of the average data for both experiments showed a significant entrainment \"echo\" in the accuracy of pitch matches. There was no apparent echo in the matching precision. Fitting of the individual data accuracy showed that the optimal phase was consistent across individuals, aligning near the next AM peak had the AM continued. The results show that sensory entrainment modulates auditory working memory in addition to stimulus detection, consistent with the proposal that ongoing neural oscillatory activity modulates higher-order auditory processes.
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  • 文章类型: Journal Article
    背景:最近对神经振荡如何反映通过大脑的信息流的兴趣导致将脑电图(EEG)记录划分为周期性(即,振荡)和非周期性(即,非振荡)组件。虽然两者都有助于组成EEG记录的频率内的常规功率测量,周期性方面表征了真正的振荡-其速度被认为是神经系统有效运作的关键。鉴于精神分裂症患者脑电图功率异常的证据,我们试图确定精神分裂症患者(SCZ)脑电图的周期性方面是否异常,并可作为脑效率的一般衡量标准.
    方法:收集104名SCZ和105名健康对照参与者的静息状态脑电图。我们使用了拟合-振荡-1-over-f(FOOOF)工具箱来去除非周期性的神经活动。我们计算了单个参与者的功率谱与所有参与者的平均功率谱之间的互相关,以量化神经振荡的相对速度。
    结果:在闭眼休息期间,与对照参与者相比,SCZ中的周期性活动向较低频率移动。平均而言,SCZ在频谱上向振荡减慢的方向偏移了0.55Hz,这预测了感知推理的恶化。较慢的神经振荡与SCZ内较弱的感知推理有关。
    结论:在精神分裂症中,静息时的周期性活动缓慢是明显的,并且可能代表神经回路的低效功能,这反映在较差的感知推理中。较慢的神经振荡可能是对大脑内信息传输的一般限制。
    BACKGROUND: Recent interest in how neural oscillations reflect the flow of information through the brain has led to partitioning electroencephalography (EEG) recordings into periodic (i.e., oscillatory) and aperiodic (i.e., non-oscillatory) components. While both contribute to conventional measures of power within the frequencies that compose EEG recordings, the periodic aspect characterizes true oscillations - the speed of which is thought to be critical to efficient functioning of neural systems. Given evidence of EEG power abnormalities in schizophrenia, we sought to determine if the periodic aspect of EEG was aberrant in people with schizophrenia (SCZ) and could serve as a general measure of brain efficiency.
    METHODS: Resting state EEGs were gathered from 104 SCZ and 105 healthy control participants. We used the fitting-oscillations-and-one-over-f (FOOOF) toolbox to remove aperiodic neural activity. We computed the cross-correlation between power spectra for individual participants and the mean power spectrum for all participants to quantify the relative speed of neural oscillations.
    RESULTS: Periodic activity in SCZ was shifted toward lower frequencies compared to control participants during eyes closed rest. On average SCZ had a 0.55 Hz shift toward oscillatory slowing across the frequency spectrum which predicted worse perceptual reasoning. Slower neural oscillations were associated with weaker perceptual reasoning within SCZ.
    CONCLUSIONS: Slowed periodic activity at rest is evident in schizophrenia and may represent inefficient functioning of neural circuits as reflected in worse perceptual reasoning. A slower pace of neural oscillations may be a general limitation on the transmission of information within the brain.
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  • 文章类型: Journal Article
    慢性神经性疼痛(CNP)仍然是一个重要的临床挑战,具有尚未完全理解的复杂神经生理学基础。识别与疼痛感知和干扰相关的特定神经振荡模式可以增强我们对CNP的理解和管理。分析来自慢性神经性疼痛患者的静息脑电图数据,以探索与疼痛强度相关的可能的神经特征。疼痛干扰,和特定的神经性疼痛特征。我们使用先前研究的脑电图数据从横断面研究中进行了二次分析,36例慢性神经性疼痛患者的疼痛简表。为了进行统计分析,我们通过每个模型的因变量对线性或逻辑回归进行建模。作为独立变量,我们使用脑电图数据与这种大脑振荡:作为三角洲,theta,阿尔法,还有beta,以及低阿尔法振荡,高阿尔法,低贝塔,和高贝塔,对于中央来说,额叶,和顶叶区域。所有模型都测试了混杂因素,如年龄和药物。一般活动中没有明显的疼痛干扰模型,走路,工作,关系,睡眠,和生活的享受。然而,过去四周的疼痛强度模型显示α振荡减少,增加的δ和θ振荡与疼痛水平降低有关,尤其是在中部地区。就疼痛对情绪的干扰而言,该模型显示额叶和中央区的高振荡Alpha信号与疼痛导致的心境障碍相关.我们的模型证实了最近的发现,提出较低的振荡频率,可能与皮质下疼痛有关,可能与大脑代偿机制有关,因此可能与疼痛水平降低有关。另一方面,更高的频率,包括阿尔法振荡,可能会破坏自上而下的补偿机制。
    Chronic neuropathic pain (CNP) remains a significant clinical challenge, with complex neurophysiological underpinnings that are not fully understood. Identifying specific neural oscillatory patterns related to pain perception and interference can enhance our understanding and management of CNP. To analyze resting electroencephalography data from individuals with chronic neuropathic pain to explore the possible neural signatures associated with pain intensity, pain interference, and specific neuropathic pain characteristics. We conducted a secondary analysis from a cross-sectional study using electroencephalography data from a previous study, and Brief Pain Inventory from 36 patients with chronic neuropathic pain. For statistical analysis, we modeled a linear or logistic regression by dependent variable for each model. As independent variables, we used electroencephalography data with such brain oscillations: as delta, theta, alpha, and beta, as well as the oscillations low alpha, high alpha, low beta, and high beta, for the central, frontal, and parietal regions. All models tested for confounding factors such as age and medication. There were no significant models for Pain interference in general activity, walking, work, relationships, sleep, and enjoyment of life. However, the model for pain intensity during the past four weeks showed decreased alpha oscillations, and increased delta and theta oscillations were associated with decreased levels of pain, especially in the central area. In terms of pain interference in mood, the model showed high oscillatory Alpha signals in the frontal and central regions correlated with mood impairment due to pain. Our models confirm recent findings proposing that lower oscillatory frequencies, likely related to subcortical pain sources, may be associated with brain compensatory mechanisms and thus may be associated with decreased pain levels. On the other hand, higher frequencies, including alpha oscillations, may disrupt top-down compensatory mechanisms.
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  • 文章类型: Journal Article
    尿道平滑肌细胞(USMC)在膀胱充盈期间收缩以闭塞尿道内括约肌。间质细胞也存在于尿道平滑肌中,据推测会影响USMC的行为和神经反应。这些细胞类似于Kit+Cajal间质细胞(ICC),它们是胃肠起搏器和神经效应器。分离的尿道ICC样细胞(ICC-LC)表现出自发的细胞内Ca2+信号传导行为,表明这些细胞可以作为起搏器或神经调节剂,类似于肠道ICC,尽管在完整的尿道组织中缺乏对ICC-LC的观察和直接刺激。我们使用了细胞特异性表达Ca2+指示剂的小鼠,GCaMP6f,去除Kit(Kit-GCaMP6f小鼠)的内源性启动子,以鉴定尿道肌肉内的ICC-LC,并表征自发和神经诱发的Ca2信号传导。ICC-LC自发产生平均传播40.1±0.7μm的Ca2波,随着振幅的变化,持续时间,和空间传播。这些事件起源于细胞中的多个激发位点,位点之间的活动不协调。尿道中的ICC-LC形成簇,但未形成互连网络。没有获得在ICC-LC之间夹带Ca2+信号传导的证据。ICC-LC中的Ca2事件不受硝苯地平的影响,但被环吡嗪酸消除,并被OraiCa2通道的拮抗剂(GSK-7975A)减少。去氧肾上腺素增加Ca2+事件频率,但一氧化氮供体(DEA-NONOate)没有作用。电场刺激(EFS,10Hz)的内在神经,在USMC中引起尿道环的收缩和增加的Ca2事件放电,未能在ICC-LC中唤起响应。我们的数据表明,尿道ICC-LC是自发活动的,但不受自主神经元的调节。
    Urethral smooth muscle cells (USMC) contract to occlude the internal urethral sphincter during bladder filling. Interstitial cells also exist in urethral smooth muscles and are hypothesized to influence USMC behaviours and neural responses. These cells are similar to Kit+ interstitial cells of Cajal (ICC), which are gastrointestinal pacemakers and neuroeffectors. Isolated urethral ICC-like cells (ICC-LC) exhibit spontaneous intracellular Ca2+ signalling behaviours that suggest these cells may serve as pacemakers or neuromodulators similar to ICC in the gut, although observation and direct stimulation of ICC-LC within intact urethral tissues is lacking. We used mice with cell-specific expression of the Ca2+ indicator, GCaMP6f, driven off the endogenous promoter for Kit (Kit-GCaMP6f mice) to identify ICC-LC in situ within urethra muscles and to characterize spontaneous and nerve-evoked Ca2+ signalling. ICC-LC generated Ca2+ waves spontaneously that propagated on average 40.1 ± 0.7 μm, with varying amplitudes, durations, and spatial spread. These events originated from multiple firing sites in cells and the activity between sites was not coordinated. ICC-LC in urethra formed clusters but not interconnected networks. No evidence for entrainment of Ca2+ signalling between ICC-LC was obtained. Ca2+ events in ICC-LC were unaffected by nifedipine but were abolished by cyclopiazonic acid and decreased by an antagonist of Orai Ca2+ channels (GSK-7975A). Phenylephrine increased Ca2+ event frequency but a nitric oxide donor (DEA-NONOate) had no effect. Electrical field stimulation (EFS, 10 Hz) of intrinsic nerves, which evoked contractions of urethral rings and increased Ca2+ event firing in USMC, failed to evoke responses in ICC-LC. Our data suggest that urethral ICC-LC are spontaneously active but are not regulated by autonomic neurons.
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  • 文章类型: Journal Article
    化学反应和它的反应环境是有内在联系的,特别是在狭窄的细胞空间内。传统的化学反应模型通常使用以浓度为主要变量的微分方程,忽略了溶液中的密度异质性以及反应与其环境之间的相互作用。我们模拟了在几何空间内化学反应与其环境之间的相互作用,比如在牢房里,通过分子簇的大小来代表环境。在没有波动的情况下,团簇大小变化与分子的激活和失活之间的相互作用会引起振荡。然而,在不稳定的环境中,系统达到波动稳定状态。当一种酶被引入这种稳定状态时,类似于动作电位尖峰序列的振荡出现。我们检查了这些尖峰序列的行为,并证明了它们可用于实现逻辑门。我们讨论了化学反应与其环境之间相互作用产生的振荡和计算,探索他们为化学智能做出贡献的潜力。
    A chemical reaction and its reaction environment are intrinsically linked, especially within the confines of narrow cellular spaces. Traditional models of chemical reactions often use differential equations with concentration as the primary variable, neglecting the density heterogeneity in the solution and the interaction between the reaction and its environment. We model the interaction between a chemical reaction and its environment within a geometrically confined space, such as inside a cell, by representing the environment through the size of molecular clusters. In the absence of fluctuations, the interplay between cluster size changes and the activation and inactivation of molecules induces oscillations. However, in unstable environments, the system reaches a fluctuating steady state. When an enzyme is introduced to this steady state, oscillations akin to action potential spike trains emerge. We examine the behavior of these spike trains and demonstrate that they can be used to implement logic gates. We discuss the oscillations and computations that arise from the interaction between a chemical reaction and its environment, exploring their potential for contributing to chemical intelligence.
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  • 文章类型: Journal Article
    基底外侧杏仁核在调节恐惧和焦虑中起着关键作用,这些过程受到情绪唤醒期间招募的不同神经调节系统的深刻调节。最近的研究表明,BLA中间神经元的活动和BLA主细胞中的抑制性突触传递受神经调节剂的调节,以影响BLA的输出和振荡网络状态。最终是恐惧和焦虑的行为表达。在这次审查中,我们首先总结了BLA抑制性突触中糖皮质激素和内源性大麻素信号相互作用介导的应激诱导焦虑发生的细胞机制。然后,我们讨论了神经调节剂在BLA外周小白蛋白表达(PV)和胆囊收缩素表达(CCK)篮状细胞中聚集在Gq信号通路上诱导的细胞类型特异性活性模式及其对BLA网络振荡和恐惧学习的影响。
    The basolateral amygdala plays pivotal roles in the regulation of fear and anxiety and these processes are profoundly modulated by different neuromodulatory systems that are recruited during emotional arousal. Recent studies suggest activities of BLA interneurons and inhibitory synaptic transmission in BLA principal cells are regulated by neuromodulators to influence the output and oscillatory network states of the BLA, and ultimately the behavioral expression of fear and anxiety. In this review, we first summarize a cellular mechanism of stress-induced anxiogenesis mediated by the interaction of glucocorticoid and endocannabinoid signaling at inhibitory synapses in the BLA. Then we discuss cell type-specific activity patterns induced by neuromodulators converging on the Gq signaling pathway in BLA perisomatic parvalbumin-expressing (PV) and cholecystokinin-expressing (CCK) basket cells and their effects on BLA network oscillations and fear learning.
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  • 文章类型: Journal Article
    神经干细胞(NSC)通过细胞分裂分化为神经元命运的中间祖细胞(IPC)。虽然从NSC到IPC的分化是一个离散的过程,最近的转录组分析确定了在这个过程中连续的转录轨迹,提出了如何调和这些相互矛盾的观察的问题。在小鼠NSC中,Hes1表达振荡,调节前神经基因Neurog2的振荡表达,而IPC中Hes1的表达消失。因此,从Hes1振荡到抑制的转变参与了神经干细胞向IPC的分化。这里,我们发现Neurog2振荡诱导Tbr2的积累,抑制Hes1表达,在NSC中产生IPC样基因表达状态。在没有Tbr2的情况下,Hes1表达上调,减少IPC的形成。这些结果表明,Neurog2-Tbr2轴在NSC中形成了一个连续的转录轨迹到IPC样神经发生状态,然后通过细胞分裂分化为IPC。
    Neural stem cells (NSCs) differentiate into neuron-fated intermediate progenitor cells (IPCs) via cell division. Although differentiation from NSCs to IPCs is a discrete process, recent transcriptome analyses identified a continuous transcriptional trajectory during this process, raising the question of how to reconcile these contradictory observations. In mouse NSCs, Hes1 expression oscillates, regulating the oscillatory expression of the proneural gene Neurog2, while Hes1 expression disappears in IPCs. Thus, the transition from Hes1 oscillation to suppression is involved in the differentiation of NSCs to IPCs. Here, we found that Neurog2 oscillations induce the accumulation of Tbr2, which suppresses Hes1 expression, generating an IPC-like gene expression state in NSCs. In the absence of Tbr2, Hes1 expression is up-regulated, decreasing the formation of IPCs. These results indicate that the Neurog2-Tbr2 axis forms a continuous transcriptional trajectory to an IPC-like neurogenic state in NSCs, which then differentiate into IPCs via cell division.
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  • 文章类型: Journal Article
    MP的AA谱影响奶牛的乳腺代谢和乳N效率。Further,膳食蛋白质补充的频率可能会影响N分配,导致N排泄减少。这项研究调查了瘤胃保护(RP)蛋白质补充的来源和频率对表观总道消化率的影响,牛奶生产,乳腺AA代谢,和奶牛的氮平衡。在随机完全区组设计中使用了28头荷斯坦-弗里斯奶牛(2.3±0.9泌乳;牛奶93±27d;平均值±SD),并饲喂了由41%玉米青贮饲料组成的基础总混合日粮(TMR),32%草青贮,和27%的浓缩物(DM基础),并配制以满足100%和95%的净能量和MP要求,分别。奶牛在免费的摊位谷仓中适应基础TMR7天,搬到单独的领带摊位,适应饮食治疗13天,然后进入气候呼吸室进行4天的测量。处理包括基础TMR(CON;159gCP/kgDM)或基础TMR,包括3种异MP补充剂中的1种:1)每日饲喂的RP豆粕和RP菜籽粕的315克混合物(ST-RPSR),2)384克RPHis混合物,RPLys,和RP每天喂食(ST-RPAA),和3)768-gRPHis混合物,RPLys,和RP每隔一天见面(OS-RPAA)。添加治疗补充剂的基础TMR设计为在48小时内提供100%的所需MP。他的混合物,Lys,并配制Met以相对于其在酪蛋白中的浓度的量递送可消化的AA。与ST-RPSR相比,ST-RPAA增加牛奶蛋白质和脂肪浓度,增加了总His的动脉浓度,Lys,和大都会(HLM),HLM的乳腺清除率下降,增加了Phe的清除,Leu和Tyr(倾向于Leu和Tyr)。瘤胃保护的蛋白质来源不影响N平衡,但ST-RPAA的边际利用效率(RP蛋白补充剂向乳蛋白的转移效率)(67%)高于ST-RPSR(17%)。与ST-RPAA相比,OS-RPAA降低了牛奶蛋白浓度。与OS-RPAA补充日相比,HLM的动脉浓度在未补充日增加,使用ST-RPAA的各组动脉HLM浓度没有差异。与OS-RPAA补充日相比,HLM的乳腺摄取在未补充日趋于增加。RPAA的补充频率不影响N平衡或整体牛奶N效率,但OS-RPAA的边际使用效率(49%)低于ST-RPAA。总的来说,乳腺对他的供应增加做出了反应,Lys,并在RPHis时通过减少其他EAA的外排来实现,RPLys,与RP植物蛋白相比,补充了RPMet。在OS-RPAA的非补充日,乳腺增加了EAA(主要是HLM)的隔离,但是根据24小时的振荡模式补充RPAA并没有比静态补充增加N效率。
    The AA profile of MP affects mammary gland metabolism and milk N efficiency of dairy cattle. Further, the frequency of dietary protein supplementation may influence N partitioning leading to reduced N excretion. This study investigated the effect of source and frequency of rumen-protected (RP) protein supplementation on apparent total-tract digestibility, milk production, mammary gland AA metabolism, and N balance of dairy cattle. Twenty-eight Holstein-Friesian cows (2.3 ± 0.9 lactations; 93 ± 27 DIM; mean ± SD) were used in a randomized complete block design and fed a basal TMR consisting of 41% corn silage, 32% grass silage, and 27% concentrate (DM basis) and formulated to meet 100% and 95% of net energy and MP requirements, respectively. Cows were adapted to the basal TMR in a freestall barn for 7 d, moved to individual tiestalls for 13 d of adaptation to dietary treatments, and then moved into climate respiration chambers for a 4-d measurement period. Treatments consisted of the basal TMR (CON; 159 g CP/kg DM) or the basal TMR including 1 of 3 iso-MP supplements: (1) 315-g mixture of RP soybean meal and RP rapeseed meal fed daily (ST-RPSR), (2) 384-g mixture of RP His, RP Lys, and RP Met fed daily (ST-RPAA), and (3) 768-g mixture of RP His, RP Lys, and RP Met fed every other day (OS-RPAA). The basal TMR with the addition of treatment supplements was designed to deliver 100% of required MP over a 48-h period. The mixture of His, Lys, and Met was formulated to deliver digestible AA in amounts relative to their concentration in casein. Compared with ST-RPSR, ST-RPAA increased milk protein and fat concentration, increased the arterial concentration of total His, Lys, and Met (HLM), decreased mammary clearance of HLM, and increased clearance of Phe, Leu, and Tyr (tendency for Leu and Tyr). Rumen-protected protein source did not affect N balance, but the marginal use efficiency (efficiency of transfer of RP protein supplement into milk protein) of ST-RPAA (67%) was higher than that of ST-RPSR (17%). Milk protein concentration decreased with OS-RPAA compared with ST-RPAA. Arterial concentration of HLM increased on the nonsupplemented day compared with the supplemented day with OS-RPAA, and there was no difference in arterial HLM concentration across days with ST-RPAA. Mammary uptake of HLM tended to increase on the nonsupplemented day compared with the supplemented day with OS-RPAA. Supplementation frequency of RP AA did not affect N balance or overall milk N efficiency, but the marginal use efficiency of OS-RPAA (49%) was lower compared with ST-RPAA. Overall, mammary glands responded to an increased supply of His, Lys, and Met by reducing efflux of other EAA when RP His, RP Lys, and RP Met were supplemented compared with RP plant proteins. Mammary glands increased sequestration of EAA (primarily HLM) on the nonsupplemented day with OS-RPAA, but supplementing RP AA according to a 24-h oscillating pattern did not increase N efficiency over static supplementation.
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