growth

增长
  • 文章类型: Journal Article
    农业工业副产品的利用,如水果残留物,在价格上涨和传统粗饲料供应有限的情况下,为反刍动物提供替代饲料的策略。在这项研究中,我们研究了刺梨残留物的影响,中国贵州当地的水果残留物,关于增长,血液代谢产物,瘤胃发酵,和胡羊的屠宰性能。将96只绵羊随机分为四组,即控制,处理1,处理2和处理3,以及饲喂含有0,10,20和30%刺梨残留物的日粮,分别。饲喂不同水平的刺梨残留物在干物质摄入量方面没有显着差异,平均每日收益,或干物质摄入量与平均日增重的比率。然而,饲喂30%刺梨Tratt残留物的组中的绵羊显示出最高的毛利润。与对照组相比,饲喂含有刺梨残留物的饮食组的血浆白蛋白含量较低(p<0.05)。此外,与对照组和治疗1相比,饮食治疗3降低了血浆肌酐水平(p<0.05)。治疗2和治疗3的绵羊血浆高密度脂蛋白水平高于对照组和治疗1(p<0.05),以及总胆固醇水平与对照组相比增加(p<0.05)。其他血浆代谢物没有显著差异。瘤胃pH,N-NH3,挥发性脂肪酸,甲烷水平在四组之间没有显着差异。然而,与对照和处理1相比,饲喂饮食处理2和处理3导致持水能力降低和剪切力增加(p<0.05)。此外,pH值,红色色度(a*),黄度指数(b*),在四组绵羊中,亮度(L*)不受影响。总之,包含高达30%的刺梨Tratt残留物对生长性能没有不利影响,允许在不影响瘤胃发酵参数的情况下节省饲料成本。刺梨残留物还显示出改善血浆蛋白效率和增强脂质代谢的益处,尽管对肉质的影响有限。考虑到它的承受能力,刺梨残留物是低成本饮食的实用选择,确保经济回报。
    The utilization of agro-industrial by-products, such as fruit residues, presents a promising strategy for providing alternative feed to ruminants amidst rising prices and limited availability of traditional roughage. In this study, we investigated the effects of Rosa roxburghii tratt residue, a local fruit residue in Guizhou province of China, on the growth, blood metabolites, rumen fermentation, and slaughter performance of Hu sheep. Ninety-six sheep were randomly divided into four groups, namely control, treatment 1, treatment 2, and treatment 3, and fed diets containing 0, 10, 20, and 30% Rosa roxburghii Tratt residue, respectively. Feeding varying levels of Rosa roxburghii Tratt residue showed no significant differences in dry matter intake, average daily gain, or the ratio of dry matter intake to average daily gain. However, sheep in the group fed with 30% Rosa roxburghii Tratt residue showed the highest gross profit. Plasma albumin content was lower in groups fed with Rosa roxburghii Tratt residue-containing diets compared to the control group (p < 0.05). Additionally, diet treatment 3 decreased plasma creatinine levels compared to control and treatment 1 (p < 0.05). Sheep in treatment 2 and treatment 3 exhibited higher plasma high-density lipoprotein level than control and treatment 1 (p < 0.05), as well as increased total cholesterol levels compared to control (p < 0.05). There were no significant differences in other plasma metabolites. Rumen pH, N-NH3, volatile fatty acids, and methane levels did not differ significantly among the four groups. However, feeding diets treatment 2 and treatment 3 resulted in decreased water holding capacity and increased shear force compared to control and treatment 1 (p < 0.05). Furthermore, pH, red chromaticity (a*), yellowness index (b*), and luminance (L*) were unaffected among the four groups of sheep. In conclusion, the inclusion of up to 30% Rosa roxburghii Tratt residue had no adverse effects on growth performance, allowing for feed cost savings without impacting rumen fermentation parameters. Rosa roxburghii tratt residue also showed benefits in improving plasma protein efficiency and enhancing lipid metabolism, albeit with limited effects on meat quality. Considering its affordability, Rosa roxburghii Tratt residue presents a practical choice for low-cost diets, ensuring economic returns.
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  • 文章类型: Journal Article
    目的:Rett综合征是一种与甲基CpG结合蛋白2(MECP2)基因突变相关的罕见神经发育障碍。我们旨在描述大量全国患者中Rett综合征的长期营养和胃肠道病程。
    方法:我们对1991-2021年在国家Rett综合征中心随访的患者进行了一项回顾性队列研究。检索到的数据包括临床特征,实验室和遗传分析。连续的人体测量测量计算了与中位年龄最接近的访问:2.5、7.5、12.5和17.5岁。KaplanMeier曲线用于描述随访期间的临床表现。使用广义估计方程模型来比较重复测量。
    结果:包括141名患者(139名女性),首次就诊的平均年龄为3.2岁(四分位距[IQR]2.3-5.7),中位随访时间为94.5个月(IQR28.6-153.3)。平均体重,身高和BMIZ评分分别为-1.09、-1.03和-0.56,在中位年龄2.5岁时;分别恶化到-3.95、-3.01和-1.19,中位年龄17.5岁(P<0.001)。胃肠道特征包括便秘(47.5%,67/141)和咀嚼/喂养困难(20%,28/141)提交;另外47(33.3%)和24(17.0%),分别,在后续。28例患者(20%)发生吞气症和44例(31.2%)胃食管反流。基因突变类型与临床表现无相关性。胃肠道表现在典型形式的Rett综合征患者中更为普遍。
    结论:人体测量参数显示随着年龄的增长而恶化,无论具体的基因突变。咀嚼/喂食困难,便秘和胃食管反流在Rett患者中很常见。
    OBJECTIVE: Rett syndrome is a rare neurodevelopmental disorder associated with methyl CpG binding protein 2 (MECP2) gene mutations. We aimed to characterize the long-term nutritional and gastrointestinal course of Rett syndrome in a large national patient population.
    METHODS: We conducted a retrospective cohort study of patients followed during 1991-2021 at a national center for Rett syndrome. The data retrieved included clinical features, laboratory and genetic analyses. Continuous anthropometric measurements were calculated for the closest visit to the median ages: 2.5, 7.5, 12.5 and 17.5 years. Kaplan Meier curves were used to describe the appearance of clinical manifestations during the follow up period. Generalized estimating equation models were used to compare repeated measurements.
    RESULTS: Included were 141 patients (139 females), the median age at the first visit was 3.2 years (interquartile range [IQR] 2.3-5.7), and the median length of follow-up was 94.5 months (IQR 28.6-153.3). Mean weight, height and BMI Z-scores were -1.09, -1.03 and -0.56, respectively, at median age 2.5 years; and deteriorated to -3.95, -3.01 and -1.19, respectively, at median age 17.5 years (P < 0.001). Gastrointestinal features included constipation (47.5%, 67/141) and chewing/feeding difficulties (20%, 28/141) at presentation; and an additional 47 (33.3%) and 24 (17.0%), respectively, during follow up. Twenty-eight patients (20%) developed aerophagia and 44 (31.2%) gastroesophageal reflux. No relation was found between genetic mutation types and clinical manifestations. GI manifestations were more prevalent in patients with typical form of Rett syndrome.
    CONCLUSIONS: Anthropometric parameters were shown to deteriorate with age, regardless of the specific genetic mutation. Chewing/feeding difficulties, constipation and gastroesophageal reflux are common in Rett patients.
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  • 文章类型: Journal Article
    已经广泛测量了脆弱性曲线(VC),以描述植物对空化的脆弱性。虽然水力传导率的作用(Ks,最大)和液压安全(P50,抗栓塞),两者都是VC的参数(“S形”类型),在不同森林的树木人口统计中,风险投资与树木人口之间的直接联系很少被探索。在这项研究中,我们将测量的VC和巴拿马季节性热带森林中16个树种的地块数据相结合,以调查VC和树木死亡率之间的联系,招聘和成长。我们发现,常绿物种的死亡率和招募率与P50呈最显著的正相关。然而,落叶树种的死亡率和招募率仅与参数a呈显著正相关,它描述了VC的陡度,并指出了电导率损失对水势下降的敏感性,但经常被忽视。常绿和落叶物种之间的这些差异可能导致现有数量关系(例如所有16个物种的拟合关系)在捕获树木死亡率和招募动态方面表现不佳。此外,常绿物种的相对生长速率(RGR)与Ks呈显著正相关,max,而落叶物种没有表现出这种关系。常绿和落叶物种的RGR也与P50和a没有显着相关性。进一步的分析表明,具有较陡的VC的物种往往具有较高的死亡率和招募率,而具有较平坦VC的物种通常是死亡率和招募率较低的物种。我们的结果强调了参数a在树木人口统计中的重要作用,尤其是落叶物种。鉴于VC是工厂水力模型的关键组成部分,整合测得的VC而不是优化其参数将有助于提高模拟和预测森林对水可利用性的响应的能力。
    Vulnerability curves (VCs) have been measured extensively to describe the differences in plant vulnerability to cavitation. Although the roles of hydraulic conductivity (Ks,max) and hydraulic safety (P50, embolism resistance), both of which are parameters of VCs (\'sigmoidal\' type), in tree demography have been evaluated across different forests, the direct linkages between VCs and tree demography are rarely explored. In this study, we combined measured VCs and plot data of 16 tree species in Panamanian seasonal tropical forests to investigate the connections between VCs and tree mortality, recruitment and growth. We found that the mortality and recruitment rates of evergreen species were most significantly positively correlated with P50. However, the mortality and recruitment rates of deciduous species only exhibited significant positive correlations with parameter a, which describes the steepness of VCs and indicates the sensitivity of conductivity loss with water potential decline, but is often neglected. These differences among evergreen and deciduous species may contribute to the poor performance of existing quantitative relationships (such as the fitting relationships for all 16 species) in capturing tree mortality and recruitment dynamics. Additionally, evergreen species presented a significant positive relationship between relative growth rate (RGR) and Ks,max, while deciduous species did not display such relationship. The RGR of both evergreen and deciduous species also displayed no significant correlations with P50 and a. Further analysis demonstrated that species with steeper VCs tended to have high mortality and recruitment rates, while species with flatter VCs were usually those with low mortality and recruitment rates. Our results highlight the important role of parameter a in tree demography, especially for deciduous species. Given that VC is a key component of plant hydraulic models, integrating measured VC rather than optimizing its parameters will help improve the ability to simulate and predict forest response to water availability.
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  • 文章类型: Journal Article
    同一鱼类物种内的遗传变异可以在某些个体中赋予豆粕(SBM)耐受性,从而有利于增长。这项研究调查了差异表达基因(DEGs)中的单核苷酸多态性(SNP),这些基因有利于高生长斑马鱼(Daniorerio)的SBM耐受性。在以前的工作中,斑马鱼的19个家庭饲喂鱼粉饮食(100FM对照饮食)或基于SBM的饮食,并补充了皂苷(50SBM2SPN实验饮食),从青少年到成人阶段。从相对于100FM,在50SBM2SPN上具有更高(170±18mg)或更低(76±10mg)的基因型与环境相互作用的家庭中选择个体。使用RNA-seq进行的肠道转录组学分析显示,饲喂50SBM2SPN饮食的高生长鱼中有六百六十五个差异表达基因。在这项工作中,利用这些结果,选择DEG中的47个SNP。这些SNP通过Sequenom在用50SBM+2SPN饮食或100FM饮食喂养的340条斑马鱼中进行基因分型。标记性状分析显示4个与3个免疫相关基因生长相关的SNP(aif1l,arid3c,和cst14b.2)响应50SBM+2SPN饮食(p值<0.05)。属于aif1lyarid3c的两个SNP对鱼类生长产生阳性(19mg)和阴性(-26mg)影响,分别。这些SNP可以用作标记以改善对SBM饮食或其他基于植物的饮食的耐受性鱼的早期选择。这些基因可以用作生物标志物来识别商业鱼类中的SNP,从而促进水产养殖的可持续性。
    Genetic variability within the same fish species could confer soybean meal (SBM) tolerance in some individuals, thus favoring growth. This study investigates the single-nucleotide polymorphisms (SNPs) in differentially expressed genes (DEGs) favoring SBM tolerance in higher-growth zebrafish (Danio rerio). In a previous work, nineteen families of zebrafish were fed a fish meal diet (100FM control diet) or SBM-based diets supplemented with saponin (50SBM + 2SPN-experimental diet), from juvenile to adult stages. Individuals were selected from families with a genotype-by-environment interaction higher (170 ± 18 mg) or lower (76 ± 10 mg) weight gain on 50SBM + 2SPN in relation to 100FM. Intestinal transcriptomic analysis using RNA-seq revealed six hundred and sixty-five differentially expressed genes in higher-growth fish fed 50SBM + 2SPN diet. In this work, using these results, 47 SNPs in DEGs were selected. These SNPs were genotyped by Sequenom in 340 zebrafish that were fed with a 50SBM + 2SPN diet or with 100FM diet. Marker-trait analysis revealed 4 SNPs associated with growth in 3 immunity-related genes (aif1l, arid3c, and cst14b.2) in response to the 50SBM + 2SPN diet (p-value < 0.05). Two SNPs belonging to aif1l y arid3c produce a positive (+19 mg) and negative (-26 mg) effect on fish growth, respectively. These SNPs can be used as markers to improve the early selection of tolerant fish to SBM diet or other plant-based diets. These genes can be used as biomarkers to identify SNPs in commercial fish, thus contributing to the aquaculture sustainability.
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  • 文章类型: Journal Article
    本研究分析了培养基成分中Ca2金属离子对小球藻DSCG150菌株细胞生长的影响。C.sorokiniana菌株DSCG150菌株基于多个裂变细胞周期生长,并且在培养基中没有金属离子的情况下生长停滞,特别是Ca2+。流式细胞术和共聚焦显微图像分析结果表明,在无Ca2+,细胞生长停滞,因为细胞积累成四个自孢子,不能转化为子细胞。遗传分析表明,Ca2+缺失导致钙调蛋白(calA)和细胞分裂控制蛋白2(CDC2_1)基因上调,以及复制起点复合物亚基6(ORC6)和双特异性蛋白磷酸酶CDC14A(CDC14A)基因的下调。通过qRT-PCR对基因表达模式的分析显示,Ca2+的缺乏不会影响细胞周期进程高达4n的自孢子,但它抑制了小球藻细胞的裂变(自孢子的释放)。在不存在Ca2+的情况下培养的细胞中添加Ca2+导致n细胞群增加,导致C.sorokiniana恢复生长。这些发现表明,Ca2在小球藻的裂变过程中起着至关重要的作用。
    This study analyzed the effects of Ca2+ metal ions among culture medium components on the Chlorella sorokiniana strain DSCG150 strain cell growth. The C. sorokiniana strain DSCG150 strain grew based on a multiple fission cell cycle and growth became stagnant in the absence of metal ions in the medium, particularly Ca2+. Flow cytometry and confocal microscopic image analysis results showed that in the absence of Ca2+, cell growth became stagnant as the cells accumulated into four autospores and could not transform into daughter cells. Genetic analysis showed that the absence of Ca2+ caused upregulation of calmodulin (calA) and cell division control protein 2 (CDC2_1) genes, and downregulation of origin of replication complex subunit 6 (ORC6) and dual specificity protein phosphatase CDC14A (CDC14A) genes. Analysis of gene expression patterns by qRT-PCR showed that the absence of Ca2+ did not affect cell cycle progression up to 4n autospore, but it inhibited Chlorella cell fission (liberation of autospores). The addition of Ca2+ to cells cultivated in the absence of Ca2+ resulted in an increase in n cell population, leading to the resumption of C. sorokiniana growth. These findings suggest that Ca2+ plays a crucial role in the fission process in Chlorella.
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  • 文章类型: Journal Article
    野生玛瑙,中国受国家二类保护的物种,缺乏用于圈养的特定复合饲料。了解膳食氨基酸模式对于最佳饲料配方至关重要。本研究旨在探讨4种不同氨基酸模式对饲粮的影响,即,凤尾鱼鱼粉蛋白(FMP,对照组)和肌肉蛋白(MP),全身蛋白(WBP),鱼卵蛋白(FEP),关于增长表现,身体成分,肠道形态学,酶活性,gh的表达水平,igf,青少年的mtor基因。在一项为期12周的240只幼鱼喂养试验中(3.46±0.04g),MP组在增长绩效方面表现出优异的结果(FBW,WGR,SGR),饲料利用效率(PER,PRE,FCR)。值得注意的是,它在全身鱼类中表现出更高的粗蛋白含量,增强肝脏中的氨基酸组成,和有利的脂肪酸健康指数(AI,TI,h/h)在肌肉中与其他组相比(P<0.05)。形态学上,MP和FMP组表现出健康特征。此外,MP组显示出较高的TPS活性,ALP,和SOD,随着gh表达水平的升高,igf,mtor基因,将其与其他组区分开(P<0.05)。这项研究表明,MP的氨基酸模式已成为青少年大甲鱼的合适饮食氨基酸模式。此外,这些发现为在保护和可持续养殖受保护物种中制定有效的饲料提供了宝贵的见解,加强研究的更广泛的生态和水产养殖意义。
    The wild Onychostoma macrolepis, a species under national class II protection in China, lacks a specific compound feed for captive rearing. Understanding the dietary amino acid pattern is crucial for optimal feed formulation. This study aimed to investigate the effects of the four different dietary amino acid patterns, i.e., anchovy fishmeal protein (FMP, control group) and muscle protein (MP), whole-body protein (WBP), fish egg protein (FEP) of juvenile Onychostoma macrolepis, on the growth performance, body composition, intestinal morphology, enzyme activities, and the expression levels of gh, igf, mtor genes in juveniles. In a 12-week feeding trial with 240 juveniles (3.46±0.04g), the MP group demonstrated superior outcomes in growth performance (FBW, WGR, SGR), feed utilization efficiency (PER, PRE, FCR). Notably, it exhibited higher crude protein content in whole-body fish, enhanced amino acid composition in the liver, and favorable fatty acid health indices (AI, TI, h/H) in muscle compared to other groups (P < 0.05). Morphologically, the MP and FMP groups exhibited healthy features. Additionally, the MP group displayed significantly higher activities of TPS, ALP, and SOD, along with elevated expression levels of gh, igf, mtor genes, distinguishing it from the other groups (P < 0.05). This study illustrated that the amino acid pattern of MP emerged as a suitable dietary amino acid pattern for juvenile Onychostoma macrolepis. Furthermore, the findings provide valuable insights for formulating effective feeds in conserving and sustainably farming protected species, enhancing the research\'s broader ecological and aquacultural significance.
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  • 文章类型: Journal Article
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  • 文章类型: Journal Article
    杂种优势在农业生产中得到了广泛的利用。尽管进行了一个多世纪的广泛研究,杂种优势的潜在机制仍然难以捉摸。大多数假设和研究都集中在杂种优势的遗传基础上。然而,肠道菌群在杂种优势中的潜在作用在很大程度上被忽略。这里,我们精心设计了一个具有两个不同肉鸡品种的杂交实验,并进行了16SrRNA扩增子和转录组测序,以研究肠道菌群和宿主基因在驱动杂种优势中的协同作用。我们发现杂种的胸肌重量表现出很高的杂种优势,高于中亲值6.28%。在杂种及其父母之间的盲肠微生物群的组成和潜在功能中观察到显着差异。超过90%的差异定植的微生物群和差异表达的基因表现出非加性模式。整合分析揭示了非加性基因和非加性微生物群之间的关联,包括细胞信号通路和代谢相关基因的表达与Odoribacter的丰度之间的联系,镰刀菌,和混血儿中的Alistipes。此外,这些微生物群的丰度更高与更好的肉类产量有关。总之,这些发现强调了肠道菌群在杂种优势中的重要性,作为调节鸡杂种优势表达的关键因素。
    Heterosis has been widely utilized in agricultural production. Despite over a century of extensive research, the underlying mechanisms of heterosis remain elusive. Most hypotheses and research have focused on the genetic basis of heterosis. However, the potential role of gut microbiota in heterosis has been largely ignored. Here, we carefully design a crossbreeding experiment with two distinct broiler breeds and conduct 16S rRNA amplicon and transcriptome sequencing to investigate the synergistic role of gut microbiota and host genes in driving heterosis. We find that the breast muscle weight of the hybrids exhibits a high heterosis, 6.28% higher than mid-parent value. A notable difference is observed in the composition and potential function of cecal microbiota between hybrids and their parents. Over 90% of the differentially colonized microbiota and differentially expressed genes exhibit nonadditive patterns. Integrative analyses uncover associations between nonadditive genes and nonadditive microbiota, including a connection between the expression of cellular signaling pathway and metabolism-related genes and the abundance of Odoribacter, Oscillibacter, and Alistipes in hybrids. Moreover, higher abundances of these microbiota are related to better meat yield. In summary, these findings highlight the importance of gut microbiota in heterosis, serving as crucial factors that modulate heterosis expression in chickens.
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  • 文章类型: Journal Article
    在温室中进行了一项实验,以研究在不同粉煤灰浓度(0-30%)上种植蚕豆并接种根瘤菌和丛枝菌根真菌(AMF)的可行性。在播种后45天进行取样以分析植物生长参数。光合属性(总叶绿素和类胡萝卜素含量),蛋白质含量,氮(N)和磷(P)含量,防御因子(抗氧化活性和脯氨酸含量)和损伤标志物(脂质过氧化,活性氧和细胞活力)。结果表明,单独施用粉煤灰(FA)不会导致生长的任何显着改善,生化和生理参数。然而,双重接种对豆类生长表现出协同影响,光合色素,蛋白质,脯氨酸,和细胞活力。根瘤菌,AMF和10%FA在所有提到的属性中显示出最大的增强。20%和30%的苍蝇剂量显示生长减少,光合作用和抗氧化剂,并通过脂质过氧化引起氧化应激。结果表明,共生关系的所有三个变量(根瘤菌-豆科植物-AMF)之间的协同或联合相互作用提高了植物生产力。
    An experiment was conducted in the greenhouse to investigate the feasibility of Vicia faba grown on different fly ash concentrations (0-30%) and dual inoculation with Rhizobium and arbuscular mycorrhizal fungi (AMF). Sampling was done 45 days after sowing to analyse the plant growth parameters, photosynthetic attributes (total chlorophyll and carotenoids content), protein content, nitrogen (N) and phosphorus (P) content, defensive factors (antioxidant activity and proline content) and damage markers (lipid peroxidation, reactive oxygen species and cell viability). The results revealed that the application of fly ash (FA) alone did not result in any significant improvement in growth, biochemical and physiological parameters. However, dual inoculation showed a synergistic impact on legume growth, photosynthetic pigments, protein, proline, and cell viability. Rhizobium, AMF and 10% FA showed maximum enhancement in all attributes mentioned. 20% and 30% fly doses showed a reduction in growth, photosynthesis and antioxidants and caused oxidative stress via lipid peroxidation. The results showed that the synergistic or combined interactions between all three variables of the symbiotic relationship (Rhizobium-legume-AMF) boosted plant productivity.
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  • 文章类型: Journal Article
    人类大脑的大部分折叠发生在妊娠的第三个三个月。尽管许多研究已经调查了大脑折叠的物理机制,对这一复杂过程的全面了解尚未实现。在机械方面,“差异生长假说”表明,褶皱的形成是由皮质层和皮质下层之间的膨胀率差异引起的,最终导致类似于屈曲的机械不稳定性。还观察到轴突,皮质下组织的重要组成部分,可以在拉伸或压缩应力下伸长或收缩,分别。先前的工作提出,这种细胞规模的行为总体上可以在皮质下层产生压力依赖性生长。当前的研究调查了应力依赖性生长对皮质表面形态的潜在作用,特别是折叠方向和曲率在发展过程中的变化。根据四种不同初始几何形状的三维折叠的有限元模拟,计算了沟方向和中部皮质表面曲率的演变:(i)球体;(ii)轴对称扁球;(iii)轴对称扁球;和(iv)三轴球体。将结果与四名早产人类婴儿的中部皮质表面重建进行比较,在大脑折叠期间的四个时间点进行成像和分析。结果表明,结合皮质下压力依赖性生长的模型预测的折叠模式更接近于发育中的人脑。
    皮质折叠是人脑发育的关键过程。异常折叠与自闭症和精神分裂症等疾病有关,然而,我们对折叠的物理机制的理解仍然有限。最终,机械力必须塑造大脑。一个重要的问题是机械力是否简单地使组织弹性变形,或者组织中的应力是否调节生长。来自这篇论文的证据,由发育中的人脑折叠模式和模拟中的相应模式之间的定量比较组成,支持皮质折叠中压力依赖性生长的关键作用。
    The majority of human brain folding occurs during the third trimester of gestation. Although many studies have investigated the physical mechanisms of brain folding, a comprehensive understanding of this complex process has not yet been achieved. In mechanical terms, the \"differential growth hypothesis\" suggests that the formation of folds results from a difference in expansion rates between cortical and subcortical layers, which eventually leads to mechanical instability akin to buckling. It has also been observed that axons, a substantial component of subcortical tissue, can elongate or shrink under tensile or compressive stress, respectively. Previous work has proposed that this cell-scale behavior in aggregate can produce stress-dependent growth in the subcortical layers. The current study investigates the potential role of stress-dependent growth on cortical surface morphology, in particular the variations in folding direction and curvature over the course of development. Evolution of sulcal direction and mid-cortical surface curvature were calculated from finite element simulations of three-dimensional folding in four different initial geometries: (i) sphere; (ii) axisymmetric oblate spheroid; (iii) axisymmetric prolate spheroid; and (iv) triaxial spheroid. The results were compared to mid-cortical surface reconstructions from four preterm human infants, imaged and analyzed at four time points during the period of brain folding. Results indicate that models incorporating subcortical stress-dependent growth predict folding patterns that more closely resemble those in the developing human brain.
    UNASSIGNED: Cortical folding is a critical process in human brain development. Aberrant folding is associated with disorders such as autism and schizophrenia, yet our understanding of the physical mechanism of folding remains limited. Ultimately mechanical forces must shape the brain. An important question is whether mechanical forces simply deform tissue elastically, or whether stresses in the tissue modulate growth. Evidence from this paper, consisting of quantitative comparisons between patterns of folding in the developing human brain and corresponding patterns in simulations, supports a key role for stress-dependent growth in cortical folding.
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