Different kinds of male flowers in the dioecious plant Asparagus of officinalis L.

Summary In the dioecious plant Asparagus officinalis L. the female plants bear flowers that are all strictly of the same type, with well-developed pistils and collapsed and consistently sterile rudiments of anthers, while male plants, on the contrary, show a great variety of vestigial female organs, from small, rudimentary ovaries with no style and stigma, up to pistils provided with a rather long style that is often enlarged in a stigma. In our investigations, we used homozygous male and female doubled haploid plants obtained from in vitro anther culture, the all-male F₁ progeny and male individuals from subsequent backcrosses. The results showed that: (1) the character length of the style is genetically inherited and involves at least two genes, the influence of the environment being quite negligible; (2) in male pistils provided with style and stigmatic papillae, the pollination and growth of the pollen tubes up to the ovules do actually occur as a rule, the only barrier to fertilization being the absence of normal embryo sacs inside the ovules; (3) the character length of the style is a very reliable marker of the trend towards hermaphroditism in Asparagus, since a correlation always exist between length of the style, size of the ovary, tendency to self-pollination, vascularization and rate of development of the ovules inside the male ovaries. On the whole, most of our observations, together with the high inbreeding depression observed when occasional andromonoecious plants are selfed, are consistent with the hypothesis of the origin of dioecy in Asparagus from hermaphroditism via the gynodioecy pathway.     

Dynamics of cytokine production during coccidial infections in chickens: colony-stimulating factors and interferon

Abstract We assayed two classes of immunoregulatory cytokines, colony-stimulating factors (CSF) and interferon (IFN), during and immediately after a primary coccidial infection in chickens. Coccidial infection induces significant alterations in serum colony-stimulating activity (CSA) and these alterations immediately precede the characteristic biphasic leukocytosis. CSA rose sharply during the first 24 h post-inoculation (PI), but returned to control levels by 48 h PL. At this time, we detected an increase in peripheral blood leukocytes which peaked at 96 h PI. A second phase of CSA increase began 96 h PI and peaked at 120–144 h PI which again preceded the second phase of leukocytosis. We also examined the production of IFN during the first 20 days PI. Splenic T cells from Eimeria maxima -infected chickens produced significantly less IFN on day 5 PI compared to T cells from the coccidia-free controls. By days 10 and 15 PI, there was no significant difference in IFN production between the T cells of infected and non-infected chickens. However, by day 20 PI, IFN production by the T cells of the infected birds produced significantly more IFN than the control T cells. The results of our studies indicated the differential production of two different cytokines by chickens during and following a primary coccidial infection. Based on these experiments, CSF may be some of the first cytokines produced during an E. maxima -infection, while IFN may be one of the later cytokines produced.     

亮斑扁角水虻幼虫酶解制备蛋白胨工艺优化及蛋白胨性质

【背景】用于餐厨垃圾等有机废弃物处理的亮斑扁角水虻(Hermetia illucens, HI)含有丰富的氨基酸和营养物质,是一种优质、经济的蛋白来源。【目的】利用亮斑扁角水虻幼虫(Hermetia illucens larvae, HIL)制备蛋白胨用于细菌培养,为亮斑扁角水虻的应用方式提供新的思路。【方法】以亮斑扁角水虻幼虫为原料,利用单因素试验确定最佳酶解条件,对比分析HIL蛋白胨和市售胰蛋白胨的基本性质和功能性状,并进行细菌培养、生物化学试验,利用两种蛋白胨分别培养大肠杆菌(Escherichia coli) ATCC 25922模式细菌并通过生长动力学分析评价应用效果。【结果】制备HIL蛋白胨的最佳酶解工艺为按1.3%(质量分数)添加复合酶(胰酶:碱性蛋白酶质量比为1:1),在pH 7.0、54℃条件下反应4 h,此时HIL的水解度为(19.34±0.15)%。HIL蛋白胨和市售胰蛋白胨的功能性状和生物化学试验差异不显著(P>0.05)。大肠杆菌ATCC25922在HIL蛋白胨培养基中生长的X_max和λ分别为6.44和2.45,在市售胰蛋白胨生长的...     

PDGF-AA activates AKT and ERK signaling for testicular interstitial Leydig cell growth via primary cilia

Testes control the development of male reproductive system. The testicular interstitial Leydig cells (Leydig cells) synthesize testosterone for promoting spermatogenesis and secondary sexual characteristics. Type A platelet-derived growth factor (PDGF-AA) is one of the most important growth factors in regulating Leydig cell growth and function. Knockout of PDGF-AA or its congenital receptor PDGFR-α leads to poor testicular development caused by reducing Leydig cell numbers, supporting PDGF-AA/PDGFR-α signaling regulates Leydig cell development. Primary cilium is a cellular antenna that functions as an integrative platform to transduce extracellular signaling for proper development and differentiation. Several receptors including PDGFR-α are observed on primary cilia for initiating signaling cascades in distinct cell types. Here we showed that PDGF-AA/PDGFR-α signaling promoted Leydig cells growth, migration, and invasion via primary cilia. Upon PDGF-AA treatment, AKT and ERK signaling were activated to regulate these cellular events. Interestingly, active AKT and ERK were detected around the base of primary cilia. Depletion of ciliary genes (IFT88 and CEP164) alleviated PDGF-AA-activated AKT and ERK, thus reducing Leydig cell growth, migration, and invasion. Thus, our study not only reveals the function of PDGF-AA/PDGFR-α signaling in maintaining testicular physiology but also uncovers the role of primary cilium and downstream signaling in regulating Leydig cell development.     

盐磷胁迫对木麻黄和台湾相思种子萌发及幼苗生长的影响

恶劣环境下,人工海防林因面临养分胁迫而经营困难。为探讨盐、磷胁迫对主要海防林树种木麻黄和台湾相思种子萌发及生长的影响,该研究分别用不同浓度的NaCl(盐)和KH₂PO₄(磷)溶液处理种子和浇灌幼苗,测定种子萌发和幼苗生长指标。结果表明：(1)高盐胁迫显著抑制种子萌发,对幼苗生长有一定影响,但两种植物影响程度不同;台湾相思种子萌发耐盐性高于木麻黄,前者相对盐害率最大值为23.03%,后者为89.15%;随着盐浓度增加,木麻黄和台湾相思种子的发芽率、发芽势、发芽指数和活力指数均降低,对应最大值分别为38.70%、34.67%、18.70、0.055和76.67%、62.22%、48.46、6.11。(2)两种植物的株高和根长随盐浓度增加而降低,木麻黄和台湾相思株高分别为12.29～6.01 mm和48.27～17.33 mm,根长分别为8.57～1.45 mm和33.41～5.88 mm;台湾相思根、茎、叶生物量及根冠比均随盐浓度的增加逐渐减小,木麻黄各处理差异较小。(3)台湾相思的种子和幼苗较木麻黄更耐低磷环境,二者最适磷浓度存在差异;木麻黄种...     

海水酸化及升温对刺参生长及能量收支的影响

以东亚浅海生态系统中的关键种——刺参(Apostichopus japonicus)为实验对象,研究了CO₂驱动的海水酸化及升温对其生长及能量收支的影响。实验设置对照组(大连近海水温, pCO₂ 400μatm)、升温组(大连近海水温+3℃, pCO₂ 400μatm)、酸化组(大连近海水温, pCO₂ 1100μatm)和酸化升温组(大连近海水温+3℃,pCO₂ 1100μatm)。结果表明:与对照组相比,温度升高3℃对刺参的生长无显著影响;酸化组刺参的特定生长率最低,较对照组降低0.19%/d,个体体重的变异系数最大;酸化升温组刺参的终末体重和特定生长率与对照组相较无显著差异,但其摄食率和排粪率均显著高于对照组。升温组和酸化组的刺参能量的分配模式与对照组相比未发生明显改变,但酸化升温组刺参的能量分配模式发生显著变化,其粪便能所占摄食能的比例显著升高。研究表明,海水酸化抑制了刺参的生长但未改变其能量的分配,生长的降低主要取决于摄食减少;而海水酸化与温度升高的共同作用可能会通过...     

温度条件对麦田土壤溶液养分浓度的影响

本文用实测资料分析了温度对麦田土壤溶液养分浓度的影响。研究表明,在农田土壤水分不亏缺的条件下,温度与麦田土壤溶液浓度呈正相关关系。随着太阳辐射增强,温度升高,土壤溶液中NO_3-N浓度增大,到14:00—15:00时,出现极大值。土壤溶液中钾浓度的高峰期基本是在中午温度高的时刻,低峰期在夜晚和午前10:00—11:00左右。10:00—11:00时的低值,可能与根系的同化吸收有关。土壤溶液养分浓度日较差大,光合面积增长快,营养生长旺盛。     

基于拉曼技术的单细胞生长检测方法

目的 单细胞生长检测可以更加科学地揭示微生物代谢变化的规律,为后期微生物工程应用提供指导。针对微生物生长应用于食品安全期和最佳食用期的精准检测问题,本文提出一种基于拉曼技术的单细胞生长检测方法。方法 首先,通过同步培养实验采集了枯草芽孢杆菌两个批次共900个单细胞拉曼光谱（SCRS）数据,其中600个用于训练和测试,另一批次300个用于模型验证。其次,基于主成分分析的特征关系矩阵,提出CP-SP特征评估方法以筛选SCRS特征用于模型检测。再基于XGBoost构建检测模型,并应用网格搜索和交叉验证对检测模型进行调优。最后,应用混淆矩阵、ROC曲线评估模型对细胞滞后期、对数期和稳定期的检测准确率、敏感性和特异性。结果 选用CP-SP筛选的第一、第二和第四主成分较特征贡献率前3个主成分的分类性能提高了3.1%,调优后的细胞生长检测模型测试准确率为96.0%,验证准确率为92.3%。结论 基于拉曼技术的单细胞生长检测方法能准确识别单细胞生长状态且具有较高的泛化能力,可为食品安全和保鲜制定精准调控机制提供科学指导。     

叶面喷施褪黑素对低温胁迫下南瓜幼苗生长和生理特性的影响

以南瓜品种‘永安2号’幼苗为试验材料,采用室内盆栽实验,在叶面喷施不同浓度(0、50、100、150、200和300μmol·L^(-1))褪黑素(MT)后进行低温(10℃/7℃)胁迫处理,考察幼苗生长指标以及相对电导率、抗氧化酶活性、渗透调节物质含量等抗逆生理指标的变化,初步探讨外源褪黑素缓解南瓜幼苗低温冷害的生理机制。结果表明:(1)在低温胁迫条件下,南瓜幼苗出现叶片萎蔫失水、边缘失绿褪色、向内卷曲等冷害症状;幼苗株高、茎粗、鲜重、干重和壮苗指数等生长指标及叶片相对叶绿素含量均显著降低;叶片相对电导率、MDA含量和O^(-)·_(2)产生速率显著升高50%以上,超氧化物歧化酶、过氧化物酶、过氧化氢酶、抗坏血酸过氧化物酶、谷胱甘肽还原酶、脱氢抗坏血酸还原酶活性以及可溶性糖、可溶性蛋白和脯氨酸含量也大多显著升高。(2)与低温胁迫处理相比,叶面喷施不同浓度褪黑素后,南瓜幼苗叶片冷害症状均得到不同程度恢复,并以100μmol·L^(-1) MT处理生长状态最好,植株形态表型与对照已没有明显差异;幼苗生长指标以及叶片相对叶绿素含量、6种抗氧化酶活性、3种渗透调节物质含量均不同程度提高,并随着MT浓度升高均先升后降,且均在100μmol·L^(-1) MT处理最高。研究发现,外源褪黑素能通过提高叶片叶绿素含量、增强抗氧化酶活性、增加渗透调节物质积累,显著降低低温冷害造成的膜质过氧化程度,有效减轻低温胁迫对南瓜幼苗的伤害,增强其抵抗低温能力,恢复幼苗的正常生长,且喷施浓度为100μmol·L^(-1)时效果最佳。