A Comparative study on pollen exine ultrastructure of Nothofagus and the other genera of Fagaceae

The genus Nothofagus is mainly distributed in South America and New Zealand. The present paper describes its pollen exine ultrastructure and compares the exine ultrastructure with that of the other genera of Fagaceae. The pollen grains were examined using ultrathin sectioning technique under transmission electron microscope. The study shows that the pollen exine ultrastructure of Nothofagus differs from that of the other genera of Fagaceae by its exine structure and thickness, type of aperture, and ornamentation. The pollen exine of Nothofagus is thin and possesses granular bacules, regular foot layer and tectum, spinulate ornamentation, and the endexine is usually visible at poral area, and 5～8 colpate. The pollen exine of the other genera of Fagaceae possesses entire bacules, irregular foot layer and tectum, granulate and tuberculate ornamentation, thicker endexine, and is 3-colporate ( 3-colpate or 3-colporoidate). The pollen exine ultrastructure of Nothofagus may belong to primitive type. The pollen exine ultrastructure data support Kuprianova’s opinion that Nothofagus should be separated from Fagaceae and established as a monogenetic family, i.e. Nothofa-gaceae.     

The ultrastructure of micropropagated and greenhouse rose plant stomata

Stomata of leaves from in vitro grown rose plantlets remain opened in the dark. The ultrastructure of their guard cells was studied after a 7 h light and a 7 h dark period, and compared to that of functional stomata from plants which have been acclimatized to greenhouse conditions. Qualitative and quantitative observations concerning the shape of the guard cells, mitochondria, plastids and starch grains, demonstrated the similarity in guard cell ultrastructure. The peculiarity of guard cell ultrastructure of in vitro cultured plants was the inability to close in the dark; vacuolar area was 40% of the whole guard cell area during both light and dark period whereas, in guard cells from greenhouse plants, the vacuolar area was 40% of the whole guard cell area during the light and only 25% during the dark period. These results indicate that stomata from in vitro plants are duly developed and possess an ultrastructure suitable for a typical functioning. The inability to close in the dark results from atypical water relation.     

Ultrastructure of Hendra virus and Nipah virus within cultured cells and host animals

The ultrastructure of Hendra and Nipah viruses is described in cultured cells, pigs, horses and humans. Differences in ultrastructure between the viruses are evident within infected cell cultures and lungs from infected amplifier hosts. These differences are important in viral identification and differentiation and understanding the pathogenesis of disease.     

Observations on the peritrichous ciliate Scyphidia ubiquita from the west coast of Wales and a description of a new species

The peritrichous ciliate, Scyphidia ubiquita Hirshfield has been recorded on the west coast of Wales from the mantle cavity of snails belonging to the genus Littorina. The ultrastructure is similar to that described for specimens from the Pacific coast of the United States, but the scopula lacks a pellicular crest. Scyphidia acanthophora sp.n. from the mantle cavity of the top shells, Gibbula umbilicalis (da Costa) and Monodonta lineata (da Costa) is described on the basis of light, surface and transmission electron microscopy. It is distinguished from other scyphidians principally by the general body shape, form of the macronucleus and the ultrastructure of the scopula disc. Comparisons are made between this species and S. ubiquita particularly with respect to the ultrastructure of the scopula and the mode of attachment to the host.     

Ultrastructure of wheat coleoptile mitochondria at short-term anoxia and post-anoxia

Abstract. Mitochondrial ultrastructure in the cells of coleoptiles of 4 d seedlings was investigated under conditions of a 1.5, 3, and 36 h anoxia and with subsequent transfer of the seedlings, after a 1.5 h anoxia, from the anaerobic into an aerobic medium. Even with short-term anoxia (1.5 h) destructive changes take place in the ultrastructure of mitochondria, which are reversible not only following the transfer of these seedlings from the anaerobic into aerobic conditions, but also with their continued maintenance under strict anoxia. Irreversible changes in the ultrastructure of mitochondria were seen only with a more prologed (36 h and longer) anoxia. The observed phenomena are discussed from the viewpoint of energy provision of the seedling cells in anoxia and post-anoxia.     

Rifampicin action on the ultrastructure of E. coli cells]

The ultrastructure of Coli bacteria exposed to rifampicin was studied. Dependence of the level of the ultrastructural changes on the antibiotic concentration and the time of incubation with the antibiotic was shown. After exclusion of the antibiotic from the medium the organism growth with normal ultrastructure was observed.     

Morphology and wall ultrastructure of leiosphaeric and acanthomorphic acritarchs from the Ediacaran of Australia

Acritarchs are a group of organic-walled microfossils with unknown biological affinities. The wall ultrastructure of the unornamented, smooth Leiosphaeridia sp. and the acanthomorphic Gyalosphaeridium pulchrum from the Ediacaran Dey Dey Mudstone in the Officer Basin, South Australia, was studied by use of transmission and scanning electron microscopy, and transmitted light microscopy. The study of the ultrastructure reveals a complexity in the cell wall not seen in prokaryotes. Wall ultrastructures range from single-layered to three- or four-layered and from homogeneous to porous. Acritarchs with different wall ultrastructures may be different organisms, but may also reflect different stages in a life cycle. In this paper I review previous ultrastructure studies and discuss possible algal and metazoan affinities for the specimens studied herein.     

Kidney morphology in sturgeons: a microdissectional and ultrastructural study

The anatomy and ultrastructure of nephrons were studied in various euryhaline and freshwater sturgeons. Microdissection failed to reveal marked differences in the nephron structure between freshwater and euryhaline fishes which might be considered as specific adaptations to the salinity of the environment. Some adaptive changes in the nephron structure were revealed by electron microscopic examination. The glomerular basal membrane is thicker in euryhaline sturgeons than in the freshwater sterlet. The processes of mesangial cells penetrating the basal membrane are much more numerous in fishes caught in the sea than in those from fresh water. Euryhaline sturgeons exhibit a great variability in the ultrastructure of epithelial cells of proximal and distal tubules. The number of mitochondria-rich cells possessing well-developed basolateral foldings is significantly higher in fishes caught in the sea. In the freshwater sterlet the ultrastructure of the epithelium of proximal and distal tubules resembles that in freshwater teleosts.
Comparison was made of the kidney morphology and ultrastructure in sturgeons, elasmo branchs and bony fishes. It is speculated that in sturgeons the adaptation to varying salinity is achieved by changes in the ultrastructure of glomeruli and differentiation of the cells of the tubular epithelium.     

线粒体超微结构及其调控机制的研究进展

线粒体超微结构是用电子显微镜观察到的精细结构,其可以根据不同能量需求和生理环境变化而变化,对线粒体功能具有关键调节作用.线粒体嵴结构是一种重要的线粒体超微结构,对多种线粒体疾病产生影响.因此,研究线粒体超微结构的调节机制,理解线粒体超微结构功能,对研究线粒体疾病的发病机理及寻找相关疾病的治疗靶点具有重要指导意义.本文详细介绍了线粒体嵴结构的主要调节机制,重点关注线粒体超微结构组成成分、线粒体超微结构对线粒体功能的影响、线粒体超微结构与线粒体疾病关系方面的研究进展,以期为制定更有效的线粒体疾病治疗方案提供理论参考.     

Exine ultrastructure of in situ peltasperm pollen from the Rhaetian of Germany and its implications

Morphology and exine ultrastructure of pollen grains of Triassic peltasperms have been studied for the first time. Pollen grains of Antevsia zeilleri from the Rhaetian of Germany are of the Cycadopites-type and monosulcate; the sculpturing is the same in the apertural and non-apertural areas. The proximal exine includes a row of lacunae covered by a solid, thick tectum and underlined by a foot layer. Pillars are hanging from the tectum between the lacunae. The exine is thinning to a homogeneous layer in the apertural region. The latter is bordered by thicker alveolate areas of the exine, in places resembling a saccus-like ultrastructure. The endexine includes white-line-centred lamellae. The exine ultrastructure is compared with that of pollen of Permian peltasperms. Although pollen types ascribed to Permian peltasperms are completely different in their general morphology, a transformation can be hypothesized by ultrastructural data from Permian Vesicaspora into Triassic Cycadopites extracted from pollen sacs of Antevsia. Comparison with Cycadopites of non-peltaspermalean (Ginkgoalean, Cycadophyte) and unknown affinities has been accomplished. The exine ultrastructure is distinctive enough to differentiate among peltaspermalean, cycadalean and bennettitalean Cycadopites; some ultrastructural features are shared with pollen of modern Ginkgo biloba. More ultrastructural data are needed as well as numerous sections of pollen grains are necessary to reveal original unchanged ultrastructure.     

The new insight on ultrastructure of C-type starch granules revealed by acid hydrolysis

C-type starch granule could be considered as the mixture of A- and B-polymorphs. The ultrastructure of C-type starch granules has not been elucidated detailedly by comparison with that of A- or B-type starch. To better understand the ultrastructure of C-type starch granules, Environment Scanning Electron Microscope (ESEM) and Field Emission Gun Transmission Electron Microscope (FEG-TEM) have been used to analyze the conformation and ultrastructure of C-type starch granule from Rhizoma Dioscorea during acid hydrolysis. SEM results showed that the amorphous areas were mainly located interior part of C-type starch granules whereas the crystalline regions were found mostly in the peripheral region of the granules. The grain size can be confirmed to be about 4.5-9 nm from the HR-TEM micrographs. The nanocrystals from acid-thinned starch displayed the typical face-centered cubic structure. This selected area electron diffraction patterns showed that individual C-type starch granule consisted of A- and B-type polymorphs.     

Protective action of serotonin on changes in the ultrastructure of the Retzius neuron induced by acetylcholine

A combined action of acetylcholine and serotonin is demonstrated to produce, in ultrastructure of the Retzius neuron of the leech, changes similar to those resulted from synaptic activation. Nevertheless, acetylcholine alone produces much deeper morphological shifts. A conclusion is made that serotonin not only retards impulse activity of the neuron, but it "slows down" development of rather great changes in its ultrastructure.     

NaCl对小麦幼苗叶肉细胞超微结构的影响

在含NaCl的培养液中培养小麦幼苗,3天后取样观察叶肉细胞,其超微结构基本正常,细胞核和细胞壁没有明显变化。但线粒体结构普遍受到损害,表现在外膜、内膜和嵴膨胀,结构模糊。叶绿体被膜和片层结构仍保持完整,仅有部分叶绿体的片层排列方向发生改变,由原来平行排列扭转为近于垂直排列。     

Changes in the Ultrastructure of Adrenocortical Cells Induced by Cholinergic Agonists

The role of cholinergic neurotransmitters in the changes in ultrastructure of adrenocortical cells remains to a great extent unexplored. We studied the influence of acetylcholine (ACh) and pilocarpine, agonists of muscarinic ACh (mACh) receptors, on the ultrastructure of adrenocortical secretory cells derived from the rat adrenal cortex. Both agonists were found to stimulate fragmentation of the mitochondria and lipid droplets and reconstruction of the peroxisomal compartment. At the same time, assembling of the smooth endoplasmic reticulum (sER) membranes was observed after ACh application, while pilocarpine action was not always prominent. Thus, we conclude that activation of mACh receptors by its agonists influence the ultrastructure of the adrenocortical cells, and the respective ACh-induced effects are more intensive.     

Age-related alterations of mitochondria from muscle tissue

The ultrastructure of mitochondria of cross-striated muscles during aging was studied by electron microscopy. Mitochondrial ultrastructure was analyzed in the flight muscle of D. melanogaster (1- and 36-day-old) and in the cardiomyocytes and skeletal muscle of young and senile Wistar and OXYS rats (3- and 25-month-old). The mitochondria in the flight muscle samples of senile D. melanogaster flies were shown to have several types of peculiar age-related mitochondrial abnormalities corresponding to those described previously. Previously unknown changes were revealed in the ultrastructure of cardiomyocyte mitochondria in senile rats (both Wistar and OXYS). Substantial changes in the ultrastructure of subsarcolemmal mitochondria were found in the fibers of red skeletal muscle of senile OXYS rats. It has been shown that the subsarcolemmal mitochondria of red muscle fibers are a peculiar population of mitochondria with atypical ultrastructure. Initial changes in the ultrastructure of subsarcolemmal mitochondria were revealed even in 3-month-old OXYS rats. At the same time, the skeletal muscle mitochondria of senile Wistar rats maintain their morphological characteristics, and their ultrastructure corresponds to that of skeletal muscle mitochondria in 3-month-old Wistar rats.     

二氮嗪对大鼠供心心肌线粒体结构及通透性的影响

目的:探讨线粒体ATP敏感性钾离子通道(mitoKATPC)开放剂二氮嗪(DE)对离体大鼠供心长时程低温保存时线粒体超微结构及线粒体渗透性转换孔(MPTP)开放的影响。方法:利用Langendorff离体鼠心灌注法,观察供心在4℃含不同浓度DE(15、30、45μmol/L)的Celsior保存液中保存9h后,复灌期心脏作功量(RPP)变化情况。比色法测定MPTP开放情况;透射电子显微镜观察心肌细胞线粒体超微结构的变化。结果:①Celsior保存液中加入30μmol/L的DE对促进长时程低温保存后供心收缩功能的恢复、减轻心肌细胞线粒体超微结构损伤和抑制MPTP开放的作用最显著。②DE的上述作用可分别被mitoKATP特异性阻断剂5-羟基葵酸盐(5-HD)及MPTP开放剂苍术苷(Atr)所取消。结论:DE可通过抑制MPTP开放而减轻由长时程低温保存导致的大鼠供心心肌线粒体超微结构的损伤。     

Effect of hexachlorobenzene and acetone on algal growth: physiology and ultrastructure

The effect of hexachlorobenzene (HCB) and acetone on growth and ultrastructure of the freshwater alga Chlorella pyrenoidosa was studied. The algal cells were grown for 76 h under continuous light in 10 ppm HCB with 0.33% acetone or in 0.33% acetone alone; the control cells were grown in nutrient solution only. As was deduced from determinations of dry matter, carbohydrates, chlorophyll content and total nitrogen, 0.33% acetone in nutrient solution slightly decreased the growth of the cells without having any influence on their ultrastructure while 3.33% acetone affected the ultrastructure of the cells severely. An incubation of Chlorella with 10 ppm HCB in nutrient sultion containing 0.33% acetone led to a drastic decrease of all growth parameters studied, total nitrogen and chlorophyll content being affected most strongly. These latter observations were in accord with the changes in ultrastructure showing damage to the cell membranes, disintegrated cytoplasm and sometimes even break down of cell organells leaving only starch grains, the pyrenoid and some endomembranes. In addition to these cells with severe lesions, quite normal cells were found.     

Fine structure of the fat body and nephrocytes in the life-stages ofDermacentor variabilis

The fine structure of the fat body and associated nephrocytes of the American dog tick,Dermacentor variabilis (Say), was described in unfed larvae, unfed nymphs, and in unfed and fed adults of both sexes. The fat body consisted of one type of cell, the trophocyte. Morphological changes that occured in the trophocytes of both sexes were dependent on feeding. The ultrastructure of feeding male trophocytes was distinct from trophocytes of feeding females. In the feeding female, the trophocyte developed an ultrastructure characteristic of cells that produce secretory proteins. A type of scalariform cell junction was found associated with rough endoplasmic reticulum of the trophocytes. Nephrocytes were closely associated with trophocytes but were not part of the fat body. Nephrocyte ultrastructure was unaltered throughout the life-stages we examined, except at the end of oviposition. Organelles in the nephrocytes were not randomly distributed, but were found in distinct regions of the cytoplasm. Slit diaphragms at the surface of the nephrocytes were extracellular specializations that had a periodic ultrastructure.     

The ultrastructure of fossil dispersed monosulcate pollen from the Early Cretaceous of Transbaikalia,Russia

The general morphology, surface sculpturing, and exine ultrastructure have been studied in dispersed monosulcate pollen from the Early Cretaceous of Transbaikalia, Russia. The pollen grains dominate the palynological assemblage extracted from coal deposits of the Khilok Formation in the Buryat Republic, which also contain ginkgoalean leaves of Baierella averianovii as the only constituent of the assemblage of plant megafossils. The relationship between the pollen grains and ginkgoalean leaves from this autochthonous burial is hypothesised on the basis of taphonomical analysis and palaeobiogeographical data. It is shown that the ectexine of the pollen grains includes a thick solid tectum, a thin granular infratectum and a thin foot layer; the endexine is fine-grained, slightly more electron-dense than the ectexine, and is preserved only in places. The distal aperture is formed by a thinning of the exine. No analogous ultrastructure has been described so far in fossil pollen grains of this morphotype studied ultrastructurally from in situ material. For comparison, we also studied the exine ultrastructure of pollen grains Ginkgo biloba. The fossil pollen is not identical to pollen of extant G. biloba, but shows several significant similarities in the exine ultrastructure, which does not contradict the presumable ginkgoalean affinity of the fossil pollen.     

The morphology and ultrastructure of Jurassic in situ ginkgoalean pollen

A fragmentary pollen organ with four to six microsporangia is discovered from the Middle Jurassic of the Irkutsk coal basin, Siberia. The in situ pollen grains are boat-shaped, monosulcate, and with a nearly psilate surface. The non-aperture ectexine is composed of a thick solid tectum, a thin infratectum, and a thin foot layer. The infratectum includes one row of small rare alveolae. The supposedly poorly preserved endexine is thin and grainy. The ectexine reduces greatly in the aperture area, where only homogeneous ectexinal patches are present over the endexine. The pollen grains under study resemble in their exine ultrastructure pollen grains of the modern Ginkgo biloba and pollen grains from dispersed seeds of a presumably ginkgoalean affinity from the Middle Jurassic of Uzbekistan. This suggests that the ginkgoalean exine ultrastructure of the modern type existed as early as the Middle Jurassic. The exine ultrastructure under study is also similar, though to lesser degree, to that of dispersed pollen grains of a presumed ginkgoalean affinity from the Cretaceous of the Russian Far East. The diversity of such a long-living group as ginkgoaleans is apparently reflected in the diversity of their exine ultrastructure. To the present knowledge, ginkgoalean pollen grains can be differentiated from similar boat-shaped monosulcate pollens by the following co-occurring characters: a thick homogeneous tectum, a thin infratectum with one row of structural elements, a thin foot layer, and an ectexine that is reduced in the aperture region to patches.