Electron microscopic observations of karyogamy in the fish egg

In the initial step of pronuclear association in fertilized fish eggs, the female and male pronuclei (containing large nucleolus-like bodies) were juxtaposed in the center of the blastodisc and formed nucleoplasmic projections along adjacent surfaces. After contact of the pronuclei, small internuclear bridges joining them were formed by fusion at several regions of the nuclear envelope projections. No specific site of fusion or breakdown of nuclear envelopes was recognized in the pronuclei during karyogamy. In the advanced stage, clumps of condensing chromatin appeared in the nucleoplasm of the newly fused pronuclei. The number and diameter of the internuclear bridges increased gradually by progressive fusion in many regions, finally yielding a spherical zygote nucleus. Following complete formation of the zygote nucleus, the pronuclear envelope began to break down concomitantly with shrinkage of the nucleoplasm, which was highly convoluted around the entire nuclear surface. The nucleoplasm containing chromosomes then mingled with the perinuclear cytoplasm.     

Nuclear envelope projections from pronuclei ofSpirogyra zygotes

Summary Spirogyra zygospores were fixed in buffered 2% osmium tetroxide and embedded in Epon. Serial sectioning established that the pronuclei, in the zygotes studied, had come to lie in very close proximity but had not started to fuse.The pronuclei had interesting projections from their nuclear envelopes. These were regular finger-like structures containing both membranes of the nuclear envelope but lacking nuclear pores. The projections measured 0.22 m in diameter and had an indeterminate length around 2.0 m. They had an inner band on the nucleoplasmic side which appeared to describe a helix along the evagination maintaining a distance of 20 nm from the inner membrane, except for occasional small regions of contact.The possibility that these evaginations were important in nuclear movement or fusion was considered less likely than that they were involved in some kind of nucleocytoplasmic exchange, possibly organellogenesis like that described inPteridium.     

An unusual short flagellum inMallomonas guttata (Synurophyceae,chrysophyta)

A short flagellum bearing unusual appendages inMallomonas guttata is described. These appendages, ca. 0.2 μm in diameter and 10–20 μm long, 7–10 in number, originate from the distal end of the short flagellum. Their membrane is continuous with the flagellar membrane and no particular structure was observed in appendage lumen.     

Spatio-temporal reorganization of intracytoplasmic microtubules is associated with nuclear selection and differentiation during the developmental process in the ciliateTetrahymena thermophila

Summary Indirect immunofluorescence has revealed various intracytoplasmic microtubular structures, which are transiently polymerized in specific subcellular locations during the developmental process of conjugation in the ciliateTetrahymena thermophila. These structures include: (1) micronuclear spindles, (2) perimicronuclear microtubules, (3) microtubular baskets surrounding migrating pronuclei, and (4) microtubules interconnecting the pronuclei with the conjugants' junctional zone. Furthermore, a peripheral network of intracytoplasmic microtubules related to the cell cortex is present in both vegetative cells and in conjugants. Comparative observations made on cells undergoing normal conjugation and defective conjugation (occurring either spontaneously or induced by taxol) has revealed some rules governing the pattern of deployment of conjugation-specific microtubules. The presence of perinuclear microtubular arrays during early postmeiotic stages of development is strictly limited to more anteriorly located nuclei which includes the selected haploid nucleus that further divides to form the stationary and migratory pronuclei. These perinuclear microtubules may be involved in the positional control of nuclear fates leading to effective nuclear selection. Microtubular bundles associated with pronuclei and connecting the junctional zone are only formed in the presence of functional pronuclei, and may be involved in the guidance of pronuclei leading to their fusion. The mechanism of cytoplasmic control of nuclear differentiation of derivatives of the zygotic nucleus appear to be associated with a coordinate action of two microtubular arrays: spindle microtubules of the second postzygotic division and the peripheral intracytoplasmic network of microtubules, leading to a proper subcortical positioning of the postzygotic nuclei at opposite poles of the cell.Abbreviations MTs Microtubules     

Dynamic behaviour of stationary pronuclei during their positioning in Paramecium caudatum

During conjugation of Paramecium caudatum, there are two well-known stages when nuclear migration occurs. What happens to the nuclei is closely related to their localisations in cells. The first of these stages is the entrance of one meiotic product into the paroral region. This nucleus survives, while the remaining three outside this area degenerate. The second stage is the antero-posterior localisation of eight synkaryon division products. Four posterior nuclei are differentiated into macronuclear anlagen, whereas four anterior nuclei remain as the presumptive micronuclei. In this experiment, the process of the third prezygotic division of P. caudatum was studied with the help of protargol staining. Here, a third nuclear migration was discovered. By two spindle turnings and two spindle elongations, stationary pronuclei were positioned near migratory pronuclei. This positioning of stationary pronuclei could shorten the distance for transferred migratory pronuclei to recognise and reach the stationary pronuclei. This fosters the synkaryon formation of P. caudatum.     

Time-course analysis of nuclear events during conjugation in the marine ciliate Euplotes vannus and comparison with other ciliates (Protozoa,Ciliophora)

Ciliates represent a morphologically and genetically distinct group of single-celled eukaryotes that segregate germline and somatic functions into two types of nuclei and exhibit complex cytogenetic events during the sexual process of conjugation, which is under the control of the so-called “mating type systems”. Studying conjugation in ciliates may provide insight into our understanding of the origins and evolution of sex and fertilization. In the present work, we studied in detail the sexual process of conjugation using the model species Euplotes vannus, and compared these nuclear events with those occurring in other ciliates. Our results indicate that in E. vannus: 1) conjugation requires about 75 hours to complete: the longest step is the development of the new macronucleus (ca. 64h), followed by the nuclear division of meiosis I (5h); the mitotic divisions usually take only 2h; 2) there are three prezygotic divisions (mitosis and meiosis I and II), and two of the eight resulting nuclei become pronuclei; 3) after the exchange and fusion of the pronuclei, two postzygotic divisions occur; two of the four products differentiate into the new micronucleus and macronucleus, respectively, and the parental macronucleus degenerates completely; 4) comparison of the nuclear events during conjugation in different ciliates reveals that there are generally three prezygotic divisions while the number of postzygotic divisions is highly variable. These results can serve as reference to investigate the mating type system operating in this species and to analyze genes involved in the different steps of the sexual process.     

Comparison of cytology and distribution of nickel in roots of Ni-hyperaccumulating and non-hyperaccumulating genotypes of Senecio coronatus

Two genotypes of Senecio coronatus (Thunb.) Harv. (Asteraceae) growing on ultramafic outcrops were identified previously: a Ni hyperaccumulator and a non-hyperaccumulator. The aim of the present study was to investigate the cytology of the roots of both genotypes, their Ni content and tissue distribution, and to ascertain whether there was a cytological basis for the differential uptake of Ni. Light and fluorescence microscopy together with histochemical methods were used to study root cytology. X-ray microanalysis by means of a nuclear microprobe—particle-induced X-ray emission (PIXE) and proton backscattering (BS) techniques—was utilized to determine the concentration and distribution of Ni and other elements. Average concentration of Ni and distribution in roots differed significantly between hyperaccumulating and non-hyperaccumulating genotypes. Ni amount in the hyperaccumulating genotype was ca. 60 times higher in the older part of the root (1,760 μg g⁻¹) and ca. 10 times higher (314 μg g⁻¹) in the younger root hair region in comparison with the equivalent parts of the non-accumulating genotype where Ni amounts were 30 μg g⁻¹. Ni distribution pattern was also different in both cases. Cytological differences were observed in the inner cortical region and exodermis of the roots. Distinct groups of specialized cells with an organelle-rich cytoplasm that produced copious numbers of spherical bodies occurred in the inner cortical region of the hyperaccumulator. Such distinct cell groups were absent from the inner cortex of the non-hyperaccumulator. Cortical cells here had a thin parietal cytoplasmic layer and produced fewer spherical bodies. In both genotypes the spherical structures were extruded from the cytoplasm into air spaces between the cells where they coalesced to form amorphous deposits, significantly larger and more abundant in the hyperaccumulator. Histochemical tests identified these deposits as a mixture of lipids, alkaloids and terpenoids. Specialized cells present in the inner cortex of the hyperaccumulating genotype demonstrated significant relative Ni depletion in comparison with the adjacent inner cortex and phloem. Casparian bands were identified in exodermal cell walls of both genotypes but the bands fluoresced more intensely in the non-accumulator suggesting differences in chemical composition and probably also a more efficient apoplastic barrier. This feature was correlated with the observed Ni distribution pattern. The highest Ni enrichment in the hyperaccumulating genotype occurred in the outer cortex; 20 times more than in the adjacent epidermis/exodermis in older portions of roots and 3 times more than in the epidermis/exodermis in younger root hair regions. In contrast, in the non-hyperaccumulating genotype, a higher concentration of nickel was found in the epidermis/exodermis compared to the outer cortex. The Ni ratio between the outer cortex and epidermis/exodermis was about 0.4 in the non-hyperaccumulator. Different cytological features exhibited by the genotypes may represent adaptive responses to the presence of high concentrations of Ni in the soil and subsequent differential uptake of Ni. Basic characteristics and elemental content of soil collected from the close vicinity of roots of two S. coronatus genotypes are reported. Wojciech Przybyłowicz on leave from the Faculty of Physics and Applied Computer Science, AGH University of Science & Technology, Kraków, Poland     

Evidence for Chromosome Endoreduplication in Eudorina californica, a Colonial Alga

Several nuclear events seen during the cleavage period in Eudorina suggest that chromosome endoreduplication, proportional to the number of cells to be produced, may occur in the gonidia prior to cleavage. Presumably the DNA concentration is reduced to the haploid level during rapid, successive divisions of the cleavage period.
To test this hypothesis, I determined DNA content of gonidia as they grew from 4 μm to 38 μm in diameter between cleavage periods. During growth from 4 μm to 8 μm in diameter, the DNA concentration remained at the haploid level of 0.17 pg/cell. As gonidia in 64 cell colonies continued to grow from 8 μm to 33 μm in diameter, their DNA concentrations increased 60-fold.
Analysis of the Eudorina DNA by equilibrium centrifugation in CsCl showed only 2 bands with buoyant densities of 1.721 g/cm³ and 1.699 g/cm³, presumed to be nuclear and chloroplast, respectively, on the basis of labelling with ³H-thymidine and ³H-adenine. The 8: 2 ratio of the two bands did not change with increase in cell size and no other bands were detected, suggesting that both nuclear and chloroplast DNAs were synthesised proportionately prior to the cleavage period.     

The cytology of the gametes and fertilization of Allomyces macrogynus

The gametes and the process of fertilization were examined by light and electron microscopy in the lower eukaryote Allomyces macrogynus. Differences in gamete morphology included the overall larger size and the presence of a larger nuclear apparatus, along with the association of a side-body complex and many more mitochondria in the female gamete. In this species of Allomyces, fertilization was initiated by contact and fusion of specialized regions of the gamete plasma membranes resulting in a binucleate fusion cell surrounded by plasma membrane contributed by both partners. Following plasmogamy, nuclear fusion was initiated by multiple nuclear membrane contacts between adjacent outer membranes. Following inner membrane fusion, small nucleoplasmic bridges were observed which presumably fused with one another and resulted in a single bridge which widened, forming the mature diploid nucleus. After karyogamy, fusion of the nuclear caps did not always occur and zygotes with and without fused caps were observed. Coalescence of the nucleoli completed the events of fertilization, forming a zygote with a single nuclear apparatus (sometimes with two caps) and two flagella. These observations are discussed in relation to fertilization mechanisms and compared to fertilization in other organisms.     

Effect of ultrafine-grained titanium surfaces on adhesion of bacteria

The influence of the ultrafine crystallinity of commercial purity grade 2 (as-received) titanium and titanium modified by equal channel angular pressing (modified titanium) on bacterial attachment was studied. A topographic profile analysis of the surface of the modified titanium revealed a complex morphology of the surface. Its prominent micro- and nano-scale features were 100–200-nm-scale undulations with 10–15 μm spacing. The undulating surfaces were nano-smooth, with height variations not exceeding 5–10 nm. These surface topography characteristics were distinctly different from those of the as-received samples, where broad valleys (up to 40–60 μm) were detected, whose inner surfaces exhibited asperities approximately 100 nm in height spaced at 1–2 μm. It was found that each of the three bacteria strains used in this study as adsorbates, viz. Staphylococcus aureus CIP 68.5, Pseudomonas aeruginosa ATCC 9025 and Escherichia coli K12, responded differently to the two types of titanium surfaces. Extreme grain refinement by ECAP resulted in substantially increased numbers of cells attached to the surface compared to as-received titanium. This enhanced degree of attachment was accompanied with an increased level of extracellular polymeric substances (EPS) production by the bacteria. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Comparison of auditory sense organs in parasitoid Tachinidae (Diptera) hosted by Tettigoniidae (Orthoptera) and homologous structures in a non-hearing Phoridae (Diptera)

The dipteran parasitoids Therobia leonidei and Homotrixa alleni (Tachinidae) use acoustic cues to locate their calling tettigoniid (Ensifera, Orthoptera) hosts. The sexually dimorphic tympanal organs of both fly species are located at the prosternum. For comparison a homologous chordotonal organ in the non-hearing fly Phormia regina, Meigen (Phoridae) is also described. The scolopidial sense organs of the ears have approximately 180 sensory cells in Th. leonidei and 250 cells in H. alleni. Interspecific analysis indicates that the cell number and arrangement might be genus specific in Tachinidae. The mononematic scolopidia, each with one sensory cell, are of different sizes and insert at the tympanal membrane. Large scolopidial units (diameter of sensory cells up to 50 μm) extend longitudinally from the centre of the sensory organ towards the ligament, whereas small units (sensory cell diameter up to 10 μm) are arranged sequentially within the sensory organ. This arrangement is discussed to be a possible basis for frequency discrimination. The ultrastructure of the scolopidia is similar in the hearing and non-hearing flies. In both groups, the majority of scolopales has a diameter from 2 to 2.9 μm, although hearing species have additionally wider scolopales. The homologous chordotonal organ of Ph. regina consists of approximately 55 sensory cells of uniform direction. The data are discussed in comparison to the ears of other Diptera.     

The immunolocalization of plasma membrane H+-ATPase in the transfer cell region of Brassica napus (Brassicaceae) ovules

Unfertilized mature ovules of Brassica L. contain an abundance of starch in the integument cells from the micropyle to a plane approximately at the level of the central cell polar nuclei. Inside the embryo sac central cell, in the coinciding region, there are transfer cell-like wall projections with plasma membranes appressed to their inner surfaces. H⁺-ATPase is present along the inner surfaces of the wall projections as indicated by reactivity with antibody raised against plasma membrane H⁺-ATPase. A number of mitochondria are in close association with wall projections in the region of the egg apparatus. Antibody raised against corn plasma membrane H⁺-ATPase cross reacts with a protein of the same size in extracts of Brassica napus indicating that the two species contain a similar plasma membrane H⁺-ATPase.     

Characteristics of the membranes of the pellicle of the ciliatePseudomicrothorax dubius

Summary The membranes of the pellicle of the ciliatePseudomicrothorax dubius are investigated using thin section electron microscopy and freeze-fracture replicas. The plasma membrane is covered by a surface coat and is connected to the outer alveolar membrane by short, sometimes branched, bridges. The inner alveolar membrane is coated on both sides. The epiplasm lies in intimate contact with the cytoplasmic surface of this membrane, and there is a corresponding deposit on the other surface. This deposit is regularly striated.The epiplasmic layer and the alveoli are interrupted at sites of cytotic activity,e.g., the attachment sites of trichocysts, the cytoproct, and the parasomal sacs. The striated deposit ends where the epiplasm ends, indicating a direct relationship between these two epimembranous layers.There is a deposit along the sides of the first part of the tip of the trichocysts, and in this region the trichocyst membrane is free of intramembranous particles.The membrane of the parasomal sacs has a coat on both surfaces. That on the extraplasmic surface is similar to the surface coat of the plasma membrane. The origin of the cytoplasmic coat is unknown. The cytotic activity of these sacs is indicated by their highly irregular profiles.     

Induction of Blocks in Nuclear Divisions and Overcondensation of Meiotic Chromosomes with Cycloheximide During Conjugation of Tetrahymena thermophila

During conjugation, the micronucleus of Tetrahymena thermophila undergoes five consecutive nuclear divisions: meiosis, third prezygotic division (pregamic mitosis) and two postzygotic mitoses of the synkaryon. The four products of the synkaryon differentiate into macronuclear anlagen and new micronuclei and the old macronucleus is resorbed. The protein synthesis inhibitor cycloheximide, applied during conjugation, induced several developmental blocks. Pairs shifted to the drug during early meiotic prophase (stages I–III) were arrested at prophase. Cycloheximide applied to cells at pachytene (stages IV-VI) to metaphase arrested the conjugants at the stage of modified prometaphase/metaphase with overcondensed, swollen bivalents. In contrast to other systems, in the presence of cycloheximide, separation of chromatids, decondensation of chromosomes and exit from metaphase I were inhibited in both diploid and haploid cells. Pairs shifted to the drug after metaphase I were arrested at postmeiotic interphase after completing one nuclear cycle. The same rule applied to the subsequent cycle; then cells were arrested at the stage of pronuclei, and those pairs with functional pronuclei and synkarya were arrested at the stage of two products of the first postzygotic division (pronuclei were not arrested in nuclear transfer and karyogamy). Only pairs with two products of the first postzygotic division were arrested at the same stage after the cycloheximide treatment. Pairs shifted to cycloheximide during the second postzygotic division were arrested in development of macronuclear anlagen and resorption of old macronuclei. The postmeiotic conjugants pulse-treated with cycloheximide (2 h) yielded heterokaryons retaining parental macronuclei (i.e. they exhibited macronuclear retention).     

Effect of bisabolangelone on development ofCydia pomonella larvae and oviposition of the females

The effects of bisabolangelone on the development of codling moth larvae,Cydia pomonella L., and on ovipositional behaviour of the females were studied under laboratory conditions. Entry of the neonate larvae into apples and their development on a semi-synthetic medium were completely inhibited when the larvae were exposed respectively to 10 μg a.i./cm² and 20 μg a.i./ml of this compound. While concentrations of 1.25 to 5.0 μg a.i./ml bisabolangelone in the medium did not significantly affect larval development, exposure of the larvae to a higher rate (10 μg a.i./ml) resulted in 80% mortality during the first week. Nevertheless, the larvae which survived the treatments underwent further development until emergence of the adults. No significant changes in duration of larval or pupal periods were recorded. Oviposition of the females in plastic beakers, whose inner surfaces were partially painted with two concentrations of bisabolangelone (1.25 to 5.0 μg a.i./cm²), was significantly reduced and the eggs were mainly laid on the parts painted with the ethanol solvent alone. When the inner surface of the cups was completely treated (i.e. top, bottom, and side) with similar concentrations of bisabolangelone, a dramatic reduction in oviposition occurred and the eggs were mostly laid on the bottom of the beakers. While this compound did not significantly influence egg hatch, it inhibited the normal upward movement of the adults in the cups and migration of the newly hatched larvae through perforations of the lids.     

Centrosome attachment to the C. elegans male pronucleus is dependent on the surface area of the nuclear envelope

A close association must be maintained between the male pronucleus and the centrosomes during pronuclear migration. In C. elegans, simultaneous depletion of inner nuclear membrane LEM proteins EMR-1 and LEM-2, depletion of the nuclear lamina proteins LMN-1 or BAF-1, or the depletion of nuclear import components leads to embryonic lethality with small pronuclei. Here, a novel centrosome detachment phenotype in C. elegans zygotes is described. Zygotes with defects in the nuclear envelope had small pronuclei with a single centrosome detached from the male pronucleus. ZYG-12, SUN-1, and LIS-1, which function at the nuclear envelope with dynein to attach centrosomes, were observed at normal concentrations on the nuclear envelope of pronuclei with detached centrosomes. Analysis of time-lapse images showed that as mutant pronuclei grew in surface area, they captured detached centrosomes. Larger tetraploid or smaller histone::mCherry pronuclei suppressed or enhanced the centrosome detachment phenotype respectively. In embryos fertilized with anucleated sperm, only one centrosome was captured by small female pronuclei, suggesting the mechanism of capture is dependent on the surface area of the outer nuclear membrane available to interact with aster microtubules. We propose that the limiting factor for centrosome attachment to the surface of abnormally small pronuclei is dynein.     

Distribution and morphology of the ampullary organs of the estuarine long-tailed catfish, <Emphasis Type="Italic">Euristhmus lepturus</Emphasis> (Plotosidae,Siluriformes)

Ampullary organs of Euristhmus lepturus occur in high densities along the head and in four parallel pathways along the trunk of the body. Large ampullary pores (125–130 μm) are easily distinguishable from other sensory epithelial pores due to the differences in size and the presence of a collar-like structure. Simple, singular ampullary organs of the head region consist of an ampullary pore connected to a long canal with a diameter of 115–175 μm before terminating as a simple ampulla with an external diameter of 390–480 μm. The ampullary canal is composed of 1–2 layers of flattened squamous epithelial cells, the basement membrane and an interlocking collagen sheath. The innermost cells lining the canal wall are adjoined via tight junctions and numerous desmosomes, as are those of the receptor and supportive cells. Canal wall tissue gives rise to a sensory epithelium containing between 242 and 285 total receptor cells, with an average diameter of 11.7 ± 5.3 μm, intermixed with medially nucleated supportive cells. Each receptor cell (21.38 ± 4.41 μm, height) has an apically positioned nucleus and a luminal surface covered with numerous microvilli. Neural terminals abut the basal region of receptor cells opposite multiple presynaptic bodies and dense mitochondria. Supportive cells extend from the ampullary lumen to the basement membrane, which is adjacent to the complex system of collagen fibres.     

Photoreceptor ultrastructure in the Antarctic mussel shrimp Acetabulastoma (Crustacea; Ostracoda), a parasite of Glyptonotus antarcticus (Crustacea; Isopoda)

The ultrastructure of the nauplius eye of the tiny Antarctic ostracode Acetabulastoma sp. is described and conclusions about its possible function are drawn. Each of the three eye-cups measures approximately 20 μm in diameter and is optically isolated from its neighbour by screening pigments, which are contained in pigment cells behind a tapetum of concentrically arranged, ca. 1-μm-long and 0.1-μm-thick, crystals. Three and sometimes four separate rhabdoms with microvilli measuring 50–60 nm in diameter project from the concave side of the tapetum up to 5 μm deep into the eye-cup interior, which is filled by the retinula cell bodies with their spherical nuclei and various organelles. Desmosomes and microtubules are seen and light-induced cell or membrane damage was minimal. The observations suggest that the Acetabulastoma eye has photoreceptors that can tolerate an exposure to bright light and it may be used to inform its owner of the approach of danger, the depth of water, and/or the season. Accepted: 27 August 1998     

Dynamics of spermiogenesis in Drosophila melanogaster

Summary A morphogenetic process that transforms spermatids from a syncytial state to a state in which each spermatid is invested in its own membrane, is initiated at the head region of the spermatid bundle and traverses through the entire length of the bundle in the testis of Drosophila melanogaster. This process not only eliminates the syncytial bridges between spermatids but also removes unneeded organelles and the excess parts of the nuclear membrane, nucleoplasm and cytoplasm. It also brings about structural modifications to flagellar elements. The propagation of this process is seen as the caudal movement of a fusiform swelling of the spermatid bundle, 100 or more in length. Spermatids are individualized in the basal half of the swelling, whereas they remain syncytial in the apical half. The swelling increases its volume as it accumulates cytoplasmic debris while traversing the sperm bundle, from about 15 in maximum diameter in the basal testicular region to as large as 30 at the apical end where it becomes a bag of wastes. A variation of the process in a mutant stock which is known to inactivate up to half of the products of meiosis is briefly described. The morphological change of interspermatid bridges prior to the individualization is also reported.This work was supported by grants from the National Institutes of Health (USPHS-HD 03015 and GM-15971) and a contract from the Atomic Energy Commission, AT(04-3)-34, P.A. 150.Graduate training grant USPHS GM 00702.     

Effect of Cytokinins and Cytokinin Antagonists on in vitro Cultured Gypsophila paniculata L.

This study deals with the effects of two cytokinins [kinetin (Kin) and N-(2-chloro-4-pyridyl)-N-phenylurea (CPPU)] and cytokinin antagonists [2-chloro-4-cyclobutyl-amino-6-ethylamino-1,3,5-triazine (ACK1) and N-(4-pyridyl)-O-(4-chlorophenyl)carbamate (ACK2)] in concentration of 1 μM on in vitro cultured Gypsophila. The application of Kin and CPPU stimulated bud opening and increased fresh and dry masses. Cytokinin antagonists reduced the number of sprouted buds and bud fresh and dry masses. In plants treated with CPPU the chloroplasts possessed well developed membrane system, which covered almost the entire chloroplasts volume. In ACK2 treated plants, the plastid apparatus in each cell was represented by two types of chloroplast in which the inner membrane system was differently organized. Cell wall adjacent chloroplasts possessed structure similar to the controls. In inner located chloroplasts part of thylakoids were semi-concentrically arranged and partially destructed. This revised version was published online in July 2006 with corrections to the Cover Date.