低温对香樟叶肉含晶细胞和溶酶体的影响

为探究低温下香樟叶肉含晶细胞和溶酶体的变化规律,以三年生香樟为试验材料,以常温为对照,通过人工模拟低温,分别于5和0°C条件下处理48 h,经制样切片后,用透射电子显微镜观察叶肉含晶细胞和溶酶体的变化。结果表明:常温处理下,香樟叶肉部分细胞中晶体数量多、体积大,晶体的形态多为柱状晶和方晶;5°C低温处理下,液泡中晶体的数量较常温略有减少,晶体体积也略有变小,晶体形态以柱状晶和方晶为主;0°C低温处理下,细胞液泡内晶体的数量急剧减少,晶体的形态以针晶为主,伴之少许方晶。不同温度处理的香樟叶肉细胞液泡内均有溶酶体,随着处理温度的降低,观察视野内单个细胞中溶酶体的数量略有增加。     

芋营养器官中的草酸钙晶体及其可能的生理作用

利用徒手切片,在光学显微镜下对芋(Colocasia esculenta(L.)Schott)营养器官中晶体的类型和分布进行了观察和研究,并用化学方法对晶体的化学成分进行了鉴定。结果表明,芋营养器官中的晶体为草酸钙结晶体,形态上可以分为针晶和簇晶两大类。含针晶束的异细胞有3种类型:含发射型草酸钙针晶束异细胞(存在于叶片、叶柄、块茎中),含大型草酸钙针晶束异细胞(存在于叶片、叶柄、块茎、块茎皮中),含大量草酸钙针晶的管状异细胞(仅存在于不定根中)。草酸钙针晶也有散乱分布于块茎和不定根中的。草酸钙簇晶在叶片、叶柄、块茎、块茎皮、不定根中均有分布,且叶片、叶柄、块茎皮中的簇晶比块茎和不定根中的尖锐。芋营养器官中的草酸钙晶体很可能是作为一种防御机制,防止动物的取食。     

虎掌（天南星科）中草酸钙晶体的形态和分布

在光学显微镜下对虎掌（Pinellia pedatisecta）营养器官和繁殖器官中晶体的类型和分布进行了观察和分析,探讨晶体的功能与作用机制。结果表明：（1）虎掌各个器官中都发现有晶体,且晶体类型有针晶、簇晶、砂晶和柱晶4种形态,其中针晶最为常见。（2）虎掌叶中的晶体大多以针晶状分布在叶片上表皮下的叶肉中,少数分布在叶下表皮下的叶肉中,其次砂晶和星芒状簇晶也在叶中较常见,叶中也有少量的柱晶。（3）虎掌的块茎中分布有大量的针晶束,在输导组织附近还有一些大的簇晶;虎掌的不定根中分布有不整齐的针晶和排列不规则的针晶束以及少量大的簇晶。（4）虎掌的佛焰苞中分布有针晶、簇晶和砂晶,且在佛焰苞中的针晶主要分布于上、下表皮之下的叶肉中,砂晶多分布在佛焰苞的上、下表皮上。（5）虎掌的花药壁中分布有针晶束,其方向和花药壁表面垂直,而花粉囊中只有小的簇晶。（6）虎掌的果皮和种皮上分布有大量的针晶。根据晶体在酸中的溶解性,虎掌体内所有晶体的化学成分都为草酸钙。研究认为,虎掌各个器官中的各种草酸钙晶体对于保护虎掌免受食草动物取食具有重要的作用。     

植物晶体的形态结构、生物功能及形成机制研究进展

晶体是植物体内产生的一种具有特殊形态结构与生理功能的代谢物,其分布广泛,已在500多种植物中发现有晶体的存在。晶体形态多样,有针晶、柱晶、棱晶、砂晶、簇晶等;类型丰富,有草酸钙晶体、钟乳体、硅质体、硫酸钙晶体及其它类型的晶体;功能特殊,具有钙调节、植物保护和防御、重金属解毒、离子平衡、缓解逆境胁迫及其它多种生物功能。晶体的形成涉及钙离子的体外吸收和体内转运,草酸的生物合成,以及钙离子和草酸的耦合过程;晶体的生长发育涉及液泡、晶异细胞的调控及与其它细胞结构的相互协作。对晶体的研究进行综述,以期为晶体的进一步研究提供基础资料。     

借助细胞晶体鉴别药用植物

在植物的细胞中,最常见是草酸钙结晶,它们是植物的一种自我解毒的过程,即对植物有毒害作用的多量草酸钙离子中和,它对植物的生长发育无明显的作用,通常认为这是植物新陈代谢产生的一种废弃物。草酸钙为无色透明的结晶,并形成不同的形态,其中有簇晶（呈霰星状）、针晶（针状）、方晶（呈斜方形、菱形、长方形）、砂晶（细小的三角形或箭头状）,广泛分布于植物各器官中。一般在一种植物中只能见到一种形态,极少数情况下也有二种或三种形态。在不同的植物中,即使晶体的形态特征相同,而其大小和数量等也不完全相同。另外,即使亲缘关…     

草酸钙晶体与药材植物的鉴别

草酸钙结晶存在于很多植物体中,它是植物生长过程中的代谢产物,在一般显微镜下就能观察到,其形态有方形、针状、多棱状集合体、砂粒状、柱状,分别称方晶、针晶、簇晶、砂晶、柱晶。药材植物种类繁多,已入药的达6千余种。其所含草酸钙结晶的形状、大小、多少、分布疏     

Na2CO3胁迫对星星草叶肉细胞超微结构的影响

利用透射电镜技术对Na2CO3胁迫下星星草叶肉细胞超微结构进行了观察。结果表明：未胁迫的叶肉细胞排列疏松,各种细胞器结构完整,叶绿体含少量淀粉粒和脂质球。轻度盐胁迫（2g/L,4g／LNa2CO3）对叶肉细胞超微结构影响较小。中度盐胁迫（6g／L,8g／L Na2CO3）引起叶肉细胞超微结构的变化,叶绿体类囊体肿胀,基粒紊乱,不含淀粉粒,脂质球数量增加,叶绿体由原来的梭形或椭球形变成圆球状;部分线粒体嵴消失,出现晶体结构;中央大液泡破裂;核逐渐降解。高度盐胁迫（10g／L,12g／LNa2CO3）下,叶绿体片层结构消失,脂质球数量增加,体积变大,被大量的膜片层所包围,叶绿体内、外膜消失,叶肉细胞中看不到叶绿体的存在;膜片层包围线粒体;叶肉细胞中可见大量的泡状结构和膜片层,叶肉细胞死亡。上述结果表明,细胞器特别是叶绿体膜结构的破坏与盐胁迫叶肉细胞最终死亡密切相关。     

草酸钙结晶在几种凤仙花属植物中的特征及其分类学意义

首次研究了7种凤仙花属(ImpatiensL.)植物茎的解剖学及细胞组织中草酸钙结晶的特征.结果表明,7种凤仙花属植物茎的解剖学结构非常近似,而茎中草酸钙结晶特征则差异显著,7种凤仙花属植物茎中均有草酸钙针晶,根据草酸钙结晶形态特征的不同,将针晶分为3种类型,即针晶束、针晶簇和散针晶.其中,黄金凤、长角凤仙花、锐齿凤仙花和红纹凤仙花有针晶束分布,而湖北凤仙花、紫花黄金凤和窄萼凤仙花则无针晶束分布,只有针晶簇或散针晶分布;此外,针晶的形态、长度、排列方式及丰富程度等在不同的物种中亦有差异.草酸钙结晶特征对凤仙花属植物的分类具有一定的科学意义.     

冰川两种藓在超低温胁迫与恢复生长状态下叶肉细胞的超微结构

为了探讨高寒冰缘区的藓类植物在超微水平的抗寒机制,该文对一号冰川下不同基质两种藓类植物水中土生的金黄银藓(Anomobryum auratum)和岩面土生的刺叶墙藓(Tortula desertorum)在常温、超低温胁迫和经胁迫后的恢复状态的超微结构进行对比。结果表明:室温下藓类植物叶肉细胞结构完整、清晰。-80 ℃超低温胁迫处理后叶肉细胞的超微结构的变化为两种藓类植物叶肉细胞大多数未出现质壁分离,但会出现质壁结构模糊,细胞质收缩; 细胞器遭到破坏甚至解体的情况; 淀粉粒、脂滴和液泡数量大大增加。在室温恢复过程中,线粒体数量增加,各个细胞器结构比超低温胁迫状态下完整性增加。根据该文的亚显微结构的分析推测这些变化是为了适应细胞迅速恢复生理功能,-80 ℃超低温胁迫没有完全使藓类植物丧失生理功能,还可以进行恢复。岩面土生刺叶蔷藓的叶细胞胞壁厚度为1 100～1 300 nm,大于水中土生金黄银藓的叶细胞胞壁厚度(200～700 nm),刺叶墙藓叶细胞胞壁比金黄银藓更厚,分析推断刺叶墙藓细胞器的抗胁迫能力也更强。综上结果表明:一号冰川的这两种藓类植物抗寒能力极强,它们独特的抗寒机制不仅与超微结构下植物淀粉粒、细胞器的结构和功能完整有关,还与其生境有关。     

五种C4荒漠植物光合器官中含晶细胞的比较分析

为了探讨荒漠植物适应干旱环境的机理,选择光合器官发生很大变化的5种C4荒漠植物进行了解剖结构的对比研究。结果表明,这5种植物中含晶细胞的数量、大小、形态和分布位置等存在差异。白梭梭（Haloxylon persicum）和梭梭（H.ammodendron）的同化枝普遍具有含晶细胞;沙拐枣（Calligonum mongolicum）的含晶细胞很少,一般只分布在贮水组织或靠近栅栏组织处;木本猪毛菜（Salsola arbuscula）的含晶细胞也不多,主要分布在栅栏组织和表皮细胞之间;猪毛菜（S.collina）的含晶细胞更少,仅在贮水组织中偶尔可见晶簇。比较梭梭、白梭梭和沙拐枣同化枝不同部位的解剖结构发现,梭梭同化枝基部含晶细胞最多,中部次之,顶部最少;白梭梭同化枝项部的含晶细胞数量较多,中部及基部较少;沙拐枣同化枝顶部与基部的粘液细胞较多,中部较少,基部几乎没有栅栏组织,而其维管组织较为发达。综合晶体的酸碱溶解性及硝酸银组化分析结果,并参照能谱仪的分析结果得知,梭梭、白梭梭、沙拐枣和木本猪毛菜的叶片或同化枝中所含晶体的主要成分为草酸钙。通过比较解剖结构发现,梭梭和白梭梭的同化枝中含晶细胞最多,其它3种植物的同化器官中含晶细胞较少,而沙拐枣同化枝中有粘液细胞存在。     

Cell wall sheath surrounding calcium oxalate crystals in mulberry idioblasts

Summary. The distribution and ultrastructural features of idioblasts containing calcium oxalate crystals were studied in leaf tissues of mulberry, Morus alba L. In addition to the calcium carbonate crystals formed in epidermal idioblasts, large calcium oxalate crystals were deposited in cells adjacent to the veins and surrounded by a cell wall sheath which had immunoreactivity with an antibody recognizing a xyloglucan epitope. The wall sheath formation indicates exclusion of the mature crystal from the protoplast. Correspondence: Y. Sugimura, Graduate School of Science and Technology, Kyoto Institute of Technology, Goshokaido, Matsugasaki, Sakyo, Kyoto 606-8585, Japan.     

Biosynthesis of L-ascorbic acid and conversion of carbons 1 and 2 of L-ascorbic acid to oxalic acid occurs within individual calcium oxalate crystal idioblasts

L-Ascorbic acid (AsA) and its metabolic precursors give rise to oxalic acid (OxA) found in calcium oxalate crystals in specialized crystal idioblast cells in plants; however, it is not known if AsA and OxA are synthesized within the crystal idioblast cell or transported in from surrounding mesophyll cells. Isolated developing crystal idioblasts from Pistia stratiotes were used to study the pathway of OxA biosynthesis and to determine if idioblasts contain the entire path and are essentially independent in OxA synthesis. Idioblasts were supplied with various (14)C-labeled compounds and examined by micro-autoradiography for incorporation of (14)C into calcium oxalate crystals. [(14)C]OxA gave heavy labeling of crystals, indicating the isolated idioblasts are functional in crystal formation. Incubation with [1-(14)C]AsA also gave heavy labeling of crystals, whereas [6-(14)C]AsA gave no labeling. Labeled precursors of AsA (L-[1-(14)C]galactose; D-[1-(14)C]mannose) also resulted in crystal labeling, as did the ascorbic acid analog, D-[1-(14)C]erythorbic acid. Intensity of labeling of isolated idioblasts followed the pattern OxA > AsA (erythorbic acid) > L-galactose > D-mannose. Our results demonstrate that P. stratiotes crystal idioblasts synthesize the OxA used for crystal formation, the OxA is derived from the number 1 and 2 carbons of AsA, and the proposed pathway of ascorbic acid synthesis via D-mannose and L-galactose is operational in individual P. stratiotes crystal idioblasts. These results are discussed with respect to fine control of calcium oxalate precipitation and the concept of crystal idioblasts as independent physiological compartments.     

The Occurrence, Type and Location of Calcium Oxalate Crystals in the Leaves of Fourteen Species of Araceae

The occurrence, type and location of calcium oxalate crystalsin the leaves of 14 species belonging to the family Araceaewere studied by light microscopy. The Pizzolato test and theRubeanic acid-silver nitrate test, used to chemically identifyand locate the crystals in cross sections of laminae, showedthe presence of four types of crystals: druses, raphides, prismaticsand crystal sand. Styloids were not observed in any of the species.Crystals identified as calcium oxalate were observed in eachtissue layer of the leaf blade, druses occurring more frequentlyin the palisade mesophyll layers, raphides more often in thespongy mesophyll. Prismatics were sparse, occurring in the mesophyllof only two species. Specialized spindle-shaped crystal idioblasts,located in the spongy mesophyll in all cases, were observedin seven of the 14 aroids. Crystal sand and variations in crystalforms were most frequently observed to be calcium compoundsother than calcium oxalate. Crystals, calcium oxalate, idioblasts, Araceae     

Cell and calcium oxalate crystal growth is coordinated to achieve high-capacity calcium regulation in plants

Summary Crystal idioblasts are cells which are specialized for accumulation of Ca²⁺ as a physiologically inactive, crystalline salt of oxalic acid. Using microautoradiographic, immunological, and ultrastructural techniques, the process of raphide crystal growth, and how crystal growth is coordinated with cell growth, was studied in idioblasts ofPistia stratiotes. Incorporation of⁴⁵Ca²⁺ directly demonstrated that, relative to surrounding mesophyll cells, crystal idioblasts act as high-capacity Ca²⁺ sinks, accumulating large amounts of Ca²⁺ within the vacuole as crystals. The pattern of addition of Ca²⁺ during crystal growth indicates a highly regulated process with bidirectional crystal growth. In very young idioblasts,⁴⁵Ca²⁺ is incorporated along the entire length of the needle-shaped raphide crystals, but as they mature incorporation only occurs at crystal tips in a bidirectional mode. At full maturity, the idioblast stops Ca²⁺ uptake, although the cells are still alive, demonstrating an ability to strictly regulate Ca transport processes at the plasma membrane. In situ hybridization for ribosomal RNA shows young idioblasts are extremely active cells, are more active than older idioblasts, and have higher general activity than surrounding mesophyll cells. Polarizing and scanning electron microscopy demonstrate that the crystal morphology changes as crystals develop and includes morphological polarity and an apparent nucleation point from which crystals grow bidirectionally. These results indicate a carefully regulated process of biomineralization in the vacuole. Finally, we show that the cytoskeleton is important in controlling the idioblast cell shape, but the regulation of crystal growth and morphology is under a different control mechanism.Abbreviation SEM scanning electron microscopy     

五种C4荒漠植物光合器官中含晶细胞的比较分析

 为了探讨荒漠植物适应干旱环境的机理, 选择光合器官发生很大变化的5种C₄荒漠植物进行了解剖结构的对比研究。结果表明, 这5种 植物中含晶细胞的数量、大小、形态和分布位置等存在差异。白梭梭(Haloxylon persicum)和梭梭(H. ammodendron)的同化枝普遍具有含晶细 胞; 沙拐枣(Calligonum mongolicum)的含晶细胞很少, 一般只分布在贮水组织或靠近栅栏组织处; 木本猪毛菜(Salsola arbuscula)的含晶细 胞也不多, 主要分布在栅栏组织和表皮细胞之间; 猪毛菜(S. collina)的含晶细胞更少, 仅在贮水组织中偶尔可见晶簇。比较梭梭、白梭梭和 沙拐枣同化枝不同部位的解剖结构发现, 梭梭同化枝基部含晶细胞最多, 中部次之, 顶部最少; 白梭梭同化枝顶部的含晶细胞数量较多, 中部 及基部较少; 沙拐枣同化枝顶部与基部的粘液细胞较多, 中部较少, 基部几乎没有栅栏组织, 而其维管组织较为发达。综合晶体的酸碱溶解性 及硝酸银组化分析结果, 并参照能谱仪的分析结果得知, 梭梭、白梭梭、沙拐枣和木本猪毛菜的叶片或同化枝中所含晶体的主要成分为草酸钙 。通过比较解剖结构发现, 梭梭和白梭梭的同化枝中含晶细胞最多, 其它3种植物的同化器官中含晶细胞较少, 而沙拐枣同化枝中有粘液细胞存 在。     

Calcium channels are involved in calcium oxalate crystal formation in specialized cells of Pistia stratiotes L

BACKGROUND AND AIMS: Pistia stratiotes produces large amounts of calcium (Ca) oxalate crystals in specialized cells called crystal idioblasts. The potential involvement of Ca(2+) channels in Ca oxalate crystal formation by crystal idioblasts was investigated. METHODS: Anatomical, ultrastructural and physiological analyses were used on plants, fresh or fixed tissues, or protoplasts. Ca(2+) uptake by protoplasts was measured with (45)Ca(2+), and the effect of Ca(2+) channel blockers studied in intact plants. Labelled Ca(2+) channel blockers and a channel protein antibody were used to determine if Ca(2+) channels were associated with crystal idioblasts. KEY RESULTS: (45)Ca(2+) uptake was more than two orders of magnitude greater for crystal idioblast protoplasts than mesophyll protoplasts, and idioblast number increased when medium Ca was increased. Plants grown on media containing 1-50 microM of the Ca(2+) channel blockers, isradipine, nifedipine or fluspirilene, showed almost complete inhibition of crystal formation. When fresh tissue sections were treated with the fluorescent dihydropyridine-type Ca(2+) channel blocker, DM-Bodipy-DHP, crystal idioblasts were intensely labelled compared with surrounding mesophyll, and the label appeared to be associated with the plasma membrane and the endoplasmic reticulum, which is shown to be abundant in idioblasts. An antibody to a mammalian Ca(2+) channel alpha1 subunit recognized a single band in a microsomal protein fraction but not soluble protein fraction on western blots, and it selectively and heavily labelled developing crystal idioblasts in tissue sections. CONCLUSIONS: The results demonstrate that Ca oxalate crystal idioblasts are enriched, relative to mesophyll cells, in dihydropyridine-type Ca(2+) channels and that the activity of these channels is important to transport and accumulation of Ca(2+) required for crystal formation.     

Developmental features of calcium oxalate crystal sand deposition inBeta vulgaris L. Leaves

Summary Sugar beet (Beta vulgaris L.) leaf has a layer of cells extended laterally between the palisade parenchyma and spongy mesophyll that develop numerous small crystals (crystal sand) within their vacuoles. Solubility studies and histochemical staining indicate the crystals are calcium oxalate. The crystals are deposited within the vacuoles early during leaf development, and at maturity the cells are roughly spherical in shape and 2 to 3 times larger than other mesophyll cells. Crystal deposition is preceeded by formation of membrane vesicles within the vacuole. The membranes are synthesizedde novo in the vacuole and have a typical trilaminate structure as viewed with the TEM. The membranes are formed within paracrystalline aggregates of tubular particles (6–8nm outer diameter) as membrane sheets, but are later organized into chambers or vesicles. Calcium oxalate is then precipitated within the membrane chambers. The tubular particles involved in membrane synthesis are usually present in the vacuoles of mature crystal cells, but in very small amounts.     

Morphologies and elemental compositions of calcium crystals in phyllodes and branchlets of Acacia robeorum (Leguminosae: Mimosoideae)

Background and Aims

Formation of calcium oxalate crystals is common in the plant kingdom, but biogenic formation of calcium sulfate crystals in plants is rare. We investigated the morphologies and elemental compositions of crystals found in phyllodes and branchlets of Acacia robeorum, a desert shrub of north-western Australia.

Methods

Morphologies of crystals in phyllodes and branchlets of A. robeorum were studied using scanning electron microscopy (SEM), and elemental compositions of the crystals were identified by energy-dispersive X-ray spectroscopy. Distributional patterns of the crystals were studied using optical microscopy together with SEM.

Key Results

According to the elemental compositions, the crystals were classified into three groups: (1) calcium oxalate; (2) calcium sulfate, which is a possible mixture of calcium sulfate and calcium oxalate with calcium sulfate being the major component; and (3) calcium sulfate · magnesium oxalate, presumably mixtures of calcium sulfate, calcium oxalate, magnesium oxalate and silica. The crystals were of various morphologies, including prisms, raphides, styloids, druses, crystal sand, spheres and clusters. Both calcium oxalate and calcium sulfate crystals were observed in almost all tissues, including mesophyll, parenchyma, sclerenchyma (fibre cells), pith, pith ray and cortex; calcium sulfate · magnesium oxalate crystals were only found in mesophyll and parenchyma cells in phyllodes.

Conclusions

The formation of most crystals was biologically induced, as confirmed by studying the crystals formed in the phyllodes from seedlings grown in a glasshouse. The crystals may have functions in removing excess calcium, magnesium and sulfur, protecting the plants against herbivory, and detoxifying aluminium and heavy metals.     

Calcium oxalate crystals and crystal cells in the leaves ofRhynchosia caribaea (Leguminosae: Papilionoideae)

Summary The development and distribution of calcium oxalate crystals, stomates and hairs were studied in the first trifoliolate leaf ofRhynchosia caribaea (Leguminosae: Papilionoideae, Phaseoleae). Using light and transmission electron microscopy, the crystals were shown to occur in both bundle sheath and mesophyll cells. Crystal distribution and shapes are characteristic forRhynchosia. Crystals develop late in leaf development in contrast to the stomates and hairs. As these latter two structures decrease in number per unit area with leaf age, crystal number increases.     

Calcium-induced patterns of calcium-oxalate crystals in isolated leaflets of Gleditsia triacanthos L. and Albizia julibrissin Durazz

For experimental induction of crystal cells (=crystal idioblasts) containing calcium-oxalate crystals, the lower epidermis was peeled from seedling leaflets of Gleditsia triacanthos L., exposing the crystal-free mesophyll and minor veins to the experimental solutions on which leaflets were floated for up to 10 d under continous light. On 0.3–2.0 mM Ca-acetate, increasing numbers of crystals, appearing 96 h after peeling, were induced. The pattern of crystal distribution changed with Ca²⁺-concentration ([Ca²⁺]): at low [Ca²⁺], crystals formed only in the non-green bundlesheath cells surrounding the veins, believed to have a relatively low Ca²⁺-extrusion capacity; at higher [Ca²⁺], crystals developed in up to 90% of the mesophyll cells, and at supraoptimal [Ca²⁺], large extracellular crystals formed on the tissue surface. By sequential treatments with solutions of different [Ca²⁺], the following three phases were identified in the induction of crystal cells: (1) during the initial 24-h period (adaptive aging), Ca²⁺ is not required and crystal induction is not possible; (2) during the following 48 h (induction period), exposure to 1–2 mM Ca-acetate induces the differentiation of mesophyll cells into crystal cells; (3) crystal growth begins 72 h after the start of induction. In intact leaflets of Albizia julibrissin Durazz., calcium-oxalate crystals are found exclusively in the bundle-sheath cells of the veins, but crystals were induced in the mesophyll of peeled leaflets floating on 1 mM Ca-acetate. Exposure to inductive [Ca²⁺] will thus trigger the differentiation of mature leaf cells into crystal cells; the spatial distribution of crystals is determined by the external [Ca²⁺] and by the structural and functional properties of the cells in the tissue.