Rice caryopsis development I: Dynamic changes in different cell layers

Rice caryopsis as one of the most important food sources for humans has a complex structure that is composed of maternal tissues including the pericarp and testa and filial tissues including the endosperm and embryo. Although rice caryopsis studies have been conducted previously, a systematic characterization throughout the entire developmental process is still lacking. In this study, detailed morphological examinations of caryopses were made during the entire 30‐day developmental process. We observed some rapid changes in cell differentiation events and cataloged how cellular degeneration processes occurred in maternal tissues. The differentiations of tube cells and cross cells were achieved by 9 days after pollination (DAP). In the testa, the outer integument was degenerated by 3 DAP, while the outer layer of the inner integument degenerated by 7 DAP. In the nucellus, all tissues with the exception of the nucellar projection and the nucellar epidermis degenerated in the first 5 DAP. By 21 DAP, all maternal tissues, including vascular bundles, the nucellar projection and the nucellar epidermal cells were degenerated. In summary, this study provides a complete atlas of the dynamic changes in cell differentiation and degeneration for individual maternal cell layers of rice caryopsis.     

Daily cuticular growth layers and the teneral stage in adult insects: A review

This paper reviews the first twenty years of progress on the occurrence and applications of daily growth layers in cuticle and daily growth bands on muscle apodemes. The methods can be used for finding the age of an insect in the teneral stage of the adult instar, in either laboratory or field material. Existing as well as potential applications are summarized with reference to teneral development and biochemistry; physiology and behaviour; and ecology (including pest ecology).     

Entwicklungsgeschichte und Ultrastruktur von Pollenkitt und Exine bei nahe verwandten entomophilen und anemophilen Angiospermensippen derAlismataceae,Liliaceae, Juncaceae,Cyperaceae, Poaceae undAraceae

Some closely related members of the monocotyledonous familiesAlismataceae, Liliaceae, Juncaceae, Cyperaceae, Poaceae andAraceae with variable modes of pollination (insect- and wind-pollination) were studied in relation to the ultrastructure of pollenkitt and exine (amount, consistency and distribution of pollenkitt on the surface of pollen grains). The character syndromes of pollen cementing in entomophilous, anemophilous and intermediate (ambophilous or amphiphilous) monocotyledons are the same in principal as in dicotyledons. Comparing present with former results one can summarize: 1) The pollenkitt is always produced in the same manner by the anther tapetum in all angiosperm sub-classes. 2) The variable stickiness of entomophilous and anemophilous pollen always depends on the particular distribution and consistency of the pollenkitt, but not its amount on the pollen surface. 3) The mostly dry and powdery pollen of anemophilous plants always contains a variable amount of inactive pollenkitt in its exine cavities. 4) A step-by step change of the pollen cementing syndrome can be observed from entomophily towards anemophily. 5) From the omnipresence of pollenkitt in all wind-pollinated angiosperms studied one can conclude that the ancestors of anemophilous angiosperms probably have been zoophilous (i.e. entomophilous) throughout.

     

Synthesis and deposition of oocyte envelopes in the Colorado beetle,Leptinotarsa decemlineata say

Summary Electron microscopical and autoradiographic methods demonstrate that the secretion vesicles (SV), which are condensed by the Golgi-complexes of the follicle cells of the Colorado beetle, contain proteins which can be labelled with ³H-leucine. The labelled proteins are transported to the oocyte during vitellogenesis. At the end of yolk deposition, a few SV, situated just above the microvilli, disintegrate and give rise to the two layers of the vitelline membrane (VM). During the laying down of the VM or perhaps at a slightly earlier stage a layer is deposited beneath the basement membrane of the follicle cells. This layer may be important in inducing the formation of the egg membranes. Once the VM has formed, the follicle cells degenerate completely. The chorionic inner layer arises from the breakdown of SV, while the chorionic outer layer is formed from the degenerated follicle cells.Dr. A. de Loof gratefully acknowledges a mandate as Aangesteld Navorser of the National Foundation of Scientific Research in Belgium. He also thanks Prof. Dr. A. Gillard for his very helpfull criticism, Dr. W. Mordue (Cambridge) for his help in correcting the language, Prof. Dr. A. Lagasse, for supplying facilities in his laboratory of EM, Mr. W. Bohyn for operating the EM and Mr. G. Maes for photography. Special thanks to Drs. G. Vrensen (Nijmegen) for the introduction in autoradiographic techniques.     

山明桐小孢子败育及与小孢子囊壁发育异常的关系

作者研究了山明桐(Paulownia sp.)小孢子败育及小孢子囊壁异常发育的过程,并探讨了两者之间的关系。结果表明:小孢子败育发生在减数分裂至单核小孢子期间。在小孢子有丝分裂前小孢子已全部敗育拚辈惴⒂斐V饕硐衷诒3只疚唇到饣虬虢到庾刺敝脸墒旎ㄒ┦逼凇R┦夷诒谙赴┓只鎏踝丛龊裣赴凇P℃咦幽冶诜⒂械恼庑┮斐O窒蟮氖抵适瞧湔7⒂瘫恢型就V?而以幼态保持至花药最后干缩。观察表明小孢子囊壁发育异常不是小孢子败育的原因,而可能是其结果。     

Correlations between pollen exine sculpturing and angiosperm self-incompatibility systems — a reply

The exine morphology and pore size of pollen from diverse angiosperm taxa with homomorphic gametophytic, homomorphic sporophytic, and heteromorphic self-incompatibility have been studied. The results indicate that correlations alleged to exist between the type of self-incompatibility system and the nature of the pollen wall morphology should be treated with considerable caution.     

Fine structure and distribution of contractile layers inAmoeba proteus preincubated at high temperature

Summary Ultrastructural and immunocytochemical studies allow the localization and identification of a microfilament cortex in heat-shockedAmoeba proteus at different stages of recovery to room temperature. Immediately after heating the cortex is in close contact with the cytoplasmic face of the plasma membrane; however, during cooling it detaches from the membrane and shifts toward the cell centre thus separating a region of peripheral hyaloplasm from central granuloplasm. After polymerization of a new submembrane cortex several detachment and reformation cycles rhythmically repeated for 2–3 hours until a multitude of stratified layers has been formed in the hyaloplasm.Electron micrographs reveal that the cortical layer at the plasma membrane is merely composed of a network of actin filaments, whereas the retracted contractile layers in the hyaloplasm and at the granuloplasmic border contain both, thick and thin filaments often arranged in bundles. The heat-shock induced activities of the microfilament cortex are based on the highly contractile properties of this system in conjunction with controlled displacements in the equilibrium between F- and G-actin.     

In vitro flower formation from thin epidermal cell layers of a partial somatic hybrid between Petunia hybrida (Hort.) and Nicotiana plumbaginifolia (Viv.)

In vitro flowers have been obtained by culturing thin epidermal cell layers of a partial somatic intergeneric hybrid. The phenotype of these flowers differs from that of flowers formed on seed-grown plants (in situ flowers) and from that of flowers of either parental line. In addition, modifications in the phenotype were observed when cultures were sustained for more than four months. Dimorphic leaves present in juvenile and adult stages of mother plants of Nicotiana plumbaginifolia and the somatic hybrid were formed on different ends of the thin epidermal cell layers. No anomalies were observed during microsporogenesis and in the meiotic and mitotic figures of the somatic hybrid, which resembled those of Nicotiana plumbaginifolia.     

Changes with time in the H+ concentration of the culture medium influences morphogenesis in tobacco thin cell layers

Different types of morphogenesis in thin cell layers of Nicotiana tabacum cv. Samsun were studied in relation to changes in the external H⁺ concentration during cluture. Different initial pHs of the medium, ranging from 3.83 to 6.35, were tested under unbuffered and MES-buffered conditions, in combination with various amounts of indolyl-3-butyric acid and kinetin. The explants were sequentially transferred from MES-free media to MES-supplemented media, as well as reciprocally, to determine possible periods during the morphogenic process that showed a particular sensitivity to the external pH. Starting from pH 3.83, 36 m M MES induced the formation of limited callus and of vegetative and floral shoots as flowers in the control. MES at 50 m M inhibited rhizogenesis and either prevented morphogenesis or induced vegetative buds or flowers, depending on the initial pH. The 4th day of culture was a determining period in the induction of roots and flowers. Rhizogenesis, but not floral or vegetative organogenesis, was related to the theoretical intracellular concentration of indolyl-3-butyric acid. H⁺ transport might be involved in the regulation of morphogenesis.