The Knotted leaf blade is a mosaic of blade,sheath, and auricle identities

The dominant Knotted-1 mutations in maize alter development of the leaf blade. Sporadic patches of localized growth, or knots, and fringes of ectopic ligule occur along lateral veins of mutant leaf blades. In addition, bundle sheaths do not completely encircle lateral veins on mutant leaf blades. We have compared mutant leaf blades with wild-type leaves to determine the precise nature of the perturbed regions. Our analysis includes characterization of epidermal cell shapes, localization of photosynthetic proteins and histology of the leaf. We show that mutant leaf blades are a mosaic of leaf organ components. Affected regions of mutant leaf blades resemble either sheath or auricle tissue in both external and internal features. This conversion of blade cells represents an acropetal shift of more basal parts of the leaf blade region and correlates with previously identified ectopic expression of the Knotted-1 protein in the leaf blade. We propose that inappropriate expression of Kn1 interferes with the process of establishment of cell identities, resulting in early termination of the normal blade development program or precocious expression of the sheath and auricle development programs. © 1994 Wiley-Liss, Inc.     

Hormonal regulation of the leaf blade movement of Drosera capensis

Several Drosera species show a bending of the leaf blade as a slow reaction to a prey. In Drosera capensis L. this bending is enhanced by a simultaneous application of IAA either to the prey or to the leaf tip, and IAA alone can induce a curvature of the leaf. This curvature is always to the upper side of the leaf independent of the side of IAA application. PCIB (1 m M ), and TIBA (0.1 m M ) inhibit the bending reversibly. The inhibition by ABA (1 m M ) is not reversible. A TIBA barrier between the prey and the tip of the leaf reduces the bending reaction, whereas application of TIBA to the basal part of the leaf has no effect. In the former case 35% of the leaves showed a strong bending just on the apical side of the TIBA barrier. It is concluded that the bending is a consequence of an internal auxin stream from the tip of the leaf to the bending point, induced by the prey.     

桃树叶片的角质蒸腾实验

折枝处理降低了叶片下表皮蒸腾速率，提高了上表皮角质蒸腾占叶总蒸腾的比值，使角质蒸腾的上下振幅增大。２ ｍ 高度叶片低于１ ｍ 高度叶片的上表皮角质蒸腾。位于黑纸套内及阴处的叶片上表皮角质蒸腾占叶总蒸腾的比值均增大，而全日上表皮角质蒸腾的振幅却减少。     

Abscission: the initial effect of ethylene is in the leaf blade

The leaf blade of cotton (Gossypium hirsutum L. cv. Stoneville 213) was investigated as the initial site of ethylene action in abscission. Ethylene applied at 14 μl/l to intact 3-week-old plants caused abscission of the third true leaf within 3 days. However, keeping only the leaf blade of this leaf in air during ethylene treatment of the rest of the plant completely prevented its abscission for up to 7 days. This inhibition of abscission was apparently the result of continued auxin production in the blade since (a) the application of an auxin transport inhibitor to the petiole of the air-treated leaf blade restored ethylene sensitivity to the leaf in terms of abscission; (b) repeated applications of naphthaleneacetic acid to the leaf blade of the third true leaf, when the entire plant was exposed to ethylene, had the same preventive effect on abscission of this leaf as keeping its leaf blade in air; and (c) the inhibitory effect of ethylene on auxin transport in the petiole, which is reduced by auxin treatment, was also reduced by placing the leaf blade in air.     

Ontogeny of the vascular bundles and contiguous tissues in the maize leaf blade

The patterns of initiation and early development of the minor and major veins in the flat portion of the leaf blade of maize (Zea mays L.) follow similar patterns. The veins and their associated bundle sheath cells commonly arise from cell assemblages derived from a single cell lineage, or longitudinal file of cells, rather than from two “half vein units” derived from different cell lineages. In addition, apparently, none of the vascular cells derived from the procambium is directly related ontogenetically to a bundle sheath cell. In veins derived from larger cell assemblages, the lateral bundle sheath cells are more closely related ontogenetically to the mesophyll cells, which are derived from the ground meristem, than to the vascular cells, which are derived from procambium. The bundle sheath cells, accordingly, are interpreted as being ground meristem in origin.     

韩国旧石器时代晚期石叶工业的年代与特征

本文介绍了韩国石叶组合的区域特征,并在近期研究的基础上对人类向朝鲜半岛的迁移进行了概述。除了西伯利亚的阿尔泰地区等及华北的水洞沟外,石叶组合在东亚地区的旧石器遗址中十分罕见。1990年底,韩国密阳市的Koreri遗址发现了一个典型的石叶石器工业遗存。在过去的十年间,韩国还发现了数个重要的遗址。朝鲜半岛的砾石石器工业一直持续到旧石器时代晚期的较早阶段,而在大约40kaBP,朝鲜半岛出现了石叶组合。在这些典型的石叶地点中,未发现大多数种类的重型工具。这些特征表明,朝鲜半岛的石叶工业可能是人类迁移的结果。目前还没有证据表明韩国的石叶工具工业在25~10 kaBP被细石叶工业取代,相反,这两种文化可能是由移居朝鲜半岛的不同人群产生的,在细石叶的使用用群体迅速扩散到整个朝鲜半岛时,石叶工业仍然延续,在25~15 kaBP的时间里与细石叶工业并存。     

Salinity-induced decrease in NADPH oxidase activity in the maize leaf blade elongation zone

We reported previously that salinity-induced elongation constraints in the expansion zone of maize leaves are associated with reduced reactive oxygen species (ROS) production and could be alleviated by the addition of ROS. The NaCl effect was salt-specific and not osmotic. This paper explores the causes for such reduction. The decrease in ROS levels under salinity was not accompanied by increases in soluble apoplastic antioxidant activities such as superoxide dismutase, peroxidases and ascorbate. In experimental systems devoid of cell walls (protoplasts and membrane fractions) superoxide anion (O(2)(-)) production was inhibited by 50 and 100 mM NaCl, 50 microM DPI, 10 mM EGTA, and 5mM verapamil, a Ca(2+) channel inhibitor. Inhibitory effects of NaCl and reduced Ca(2+) supply were also observed in in gel assessment of O(2)(-) -generating activity. The main activity band excised from the ND-PAGE was recognized by an antibody against the C-terminal portion of the tomato gp91(phox) homolog. These results indicate the *O(2)(-) -generating activity negatively affected by NaCl was compatible with that of plasma membrane NADPH oxidase.     

Key proliferative activity in the junction between the leaf blade and leaf petiole of Arabidopsis

Leaves are the most important, fundamental units of organogenesis in plants. Although the basic form of a leaf is clearly divided into the leaf blade and leaf petiole, no study has yet revealed how these are differentiated from a leaf primordium. We analyzed the spatiotemporal pattern of mitotic activity in leaf primordia of Arabidopsis (Arabidopsis thaliana) in detail using molecular markers in combination with clonal analysis. We found that the proliferative zone is established after a short interval following the occurrence of a rod-shaped early leaf primordium; it is separated spatially from the shoot apical meristem and seen at the junction region between the leaf blade and leaf petiole and produces both leaf-blade and leaf-petiole cells. This proliferative region in leaf primordia is marked by activity of the ANGUSTIFOLIA3 (AN3) promoter as a whole and seems to be differentiated into several spatial compartments: activities of the CYCLIN D4;2 promoter and SPATULA enhancer mark parts of it specifically. Detailed analyses of the an3 and blade-on-petiole mutations further support the idea that organogenesis of the leaf blade and leaf petiole is critically dependent on the correct spatial regulation of the proliferative region of leaf primordia. Thus, the proliferative zone of leaf primordia is spatially differentiated and supplies both the leaf-blade and leaf-petiole cells.     

Engrailed expression in the anterior lineage compartment of the developing wing blade of Drosophila.

The developing wing of Drosophila melanogaster was examined at larval and pupal stages of development to determine whether the anterior-posterior lineage boundary, as identified by lineage restrictions, was congruent with the boundaries defined by the expression of posterior-specific (engrailed, invected), and anterior-specific (cubitus interruptus-D) genes. The lineage boundary was identified by marking mitotic recombinant clones, using an enhancer trap line with ubiquitous beta-gal expression in imaginal tissues; clones of +/+ cells were identified by their lack of beta-gal expression. Domains of gene expression were localized using antibodies and gene specific lacZ constructs. Surprisingly, it was found that engrailed expression extended a small distance into the anterior lineage compartment of the wing blade, as identified with anti-en/inv mAb, anti-en polyclonal antiserum, or an en-promoter-lacZ insert, ryxho25. This anterior expression was not present in early third instar discs, but appeared during subsequent larval and pupal development. In contrast, the expression of cubitus interruptus-D, as identified using the ci-Dplac insert, appeared to be limited to the anterior lineage compartment. Thus, en expression is not limited to cells from the posterior lineage compartment, and en and ci-D activities can overlap in a region just anterior to the lineage compartment boundary in the developing wing. The lineage boundary could also be identified by a line of aligned cells in the prospective wing blade region of wandering third instar discs. A decapentaplegic-lacZ construct was expressed in a stripe several cells anterior to the lineage boundary, and did not define or overlap into the posterior lineage compartment.     

旋割法制备气管螺旋条评价

目的通过改进螺旋剪法建立制备气管螺旋条的旋割法。方法 40只豚鼠,用旋割法和螺旋剪法制备离体豚鼠气管螺旋条,在Kreb＇s液中平衡孵育2 h后,以组胺histamine（浴槽浓度2.0×10-3g/L）和乙酰胆碱acetylcholine（浴槽浓度2.0×10-4g/L）引发气管螺旋条收缩,用BL420生物信号采集系统与张力传感器测定标本张力变化值。数据采用SPSS11.5软件在α=0.05的信度下进行t检验。结果 2 g负荷下,旋割法标本histamine引发收缩幅度是螺旋剪法制备标本的1.31倍,乙酰胆碱引发收缩幅度旋割法是螺旋剪法制备标本的1.208倍,经t检验,P〈0.05,差异均具有显著性;旋割法标本,histamine引发2 g负荷标本收缩幅度是1 g负荷的1.48倍,乙酰胆碱引发2 g负荷标本的收缩幅度是1 g负荷的1.38倍,经t检验,P〈0.05,差异均具有显著性;旋割法标本经hista-mine或acetylcholine激发收缩,洗净药物重复激发6次收缩幅度的RSD值分别为19.8%和19.1%,螺旋剪法标本经histamine或acetylcholine 6次重复引发诱发收缩幅度的RSD值分别35.3%和33.7%。结论与螺旋剪法制备气管螺旋条标本比较,旋割法制备螺旋条标本对收缩诱导剂histamine与acetylcholine的敏感性高,标本负荷以2 g较好,旋割法标本重复利用收缩幅度变化值较螺旋剪法标本小。