Ultrastructure of the marine predatory flagellate <Emphasis Type="Italic">Metromonas simplex</Emphasis> Larsen et Patterson, 1990 (Cercozoa)

The ultrastructure of the marine predatory flagellate Metromonas simplex Larsen et Patterson was studied. The cell is surrounded by a low-contrast fibrous layer composed of thin hairs covered by a thin bilayer membrane and an outer layer of thin short fibers. The plasmalemma lies under these layers. The predator captures whole cells of the prey, usually bodonids or chrysomonads. The cytostome as a cell pocket is undetectable. The long flagellum bears very thin mastigonemes (hairs) with lengths of 0.8–1.0 μm; the short flagellum is naked and reduced in length. The transitional zone lacks spirals or other additional elements. The transversal plate is elevated on the cell surface. The flagellar root system is very simple and has one microtubular band which originates near the kinetosomes. The latter are parallel to each other and interconnected by fibrous bridges. The vesicular nucleus, Golgi apparatus, and endoplasmic reticulum are of typical structures. The oval mitochondria of 0.6–2.5 μm contain lamellar cristae. The cylindrical extrusomes (trichocysts) found in the cytoplasm have lengths of 1.0–1.4 μm and diameters of 0.12–0.08 μm. The trichocysts have a wheel-shaped structure with 13 spokes visible in cross-sections. The contractile vacuole is absent. The similarity that M. simplex shares with Metopion fluens Larsen et Patterson, cryothecomonads, and other predatory flagellates is discussed.     

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.     

Ultrastructure of spermatozoa and spermiogenesis inSpirula spirula (L.): systematic importance and comparison with other cephalopods

Spermatozoa and spermiogenesis in the deep-water cephalopodSpirula sprirula (L.) are examined using transmission electron microscopy. Mature spermatozoa (taken from spermatophores) are elongate cells 115–120 μm long, composed of a conical acrosomal vesicle, cylindrical nucleus (6.8–7 μm long), flagellum and a loose mitochondrial sleeve — the latter concealing the proximal 6–8 μm of the flagellum. The acrosomal vesicle is 2.8 μm long with fibro-granular contents and an electron-lucent apical zone. Subacrosomal material, organized as closely packed granules, fills a basal invagination of the acrosomal vesicle. In early spermatids the flagellum is derived from a triplet substructure centriole positioned close to the developing nuclear invagination. As flagellum formation proceeds, the acrosomal vesicle (produced evidently through Golgi secretion) attaches to the condensing nucleus. Spermatids are connected by cytoplasmic bridges throughout their development, and exhibit a perinuclear sheath of microtubules from the onset of the fibrous stage of nuclear condensation (mid-, late spermatids). In mid-spermatids, mitochondria collect posterior to the nucleus and subsequently are packed into a cylindrical extension of the plasma membrane to form the periflagellar mitochondrial sleeve. These features of spermiogenesis and mature spermatozoa ofSpirula clearly associate the Spirulidae with the Sepiida, Teuthida and Sepiolida — particularly with the latter order. However, pending results of a thorough review of coleoid sperm morphology, the Spirulidae are here included in their own order — Spirulida (of Reitner & Engeser, 1982) — rather than in either the Sepiida or Sepiolida.     

Deep-sea parasitic nematodes of the genus <Emphasis Type="Italic">Trophomera</Emphasis> Rubtsov et Platonova, 1974 (Benthimermithidae) from the Equatorial Atlantic,with the descriptions of two new species

Nematode females of the genus Trophomera (Benthimermithidae) from the collection of the Smithsonian’s National Museum of Natural History (Washington, DC, USA) were examined. Nematodes were collected in different parts of the Western Atlantic (Hatteras Abyssal Plain, Brazil Basin, and Argentina Basin) from depths of 467–5,223 m. Two new species are described. Body length of T. americana sp. n. is 3,250–4,470 μm; posterior end conical with rounded tip; cephalic setae about 3–4 μm long; trophosome consisting of several longitudinal rows of large cells; ovaries reflected; mature eggs 35 μm in diameter. Body length of T. longiovaris sp. n. is 7,870–15,400 μm; posterior end conical with rounded tip; cephalic sensilla 7 μm long; mouth opening vestigial, present as very narrow apical pore; pharynx devoid of internal lumen and muscular envelope; midgut represents a trophosome without internal lumen; trophosomal cells arranged in 3–4 longitudinal rows; rectum and anus vestigial; female reproductive system didelphic, amphidelphic, very long, occupying about 0.8 total body length; ovaries telogonic, outstretched; oviducts very long, repeatedly folded across body axis; proximal parts of oviducts being than distal ones, uterus distinctly formed. New finds of two known species, T. arnauidi and T. marionensis, are also recorded and described.     

Composition and significance of picophytoplankton in Antarctic waters

Filter fractionated picophytoplankton from Antarctic coastal waters (summer 2001) represented only 7–33% of total phytoplankton, even though total stocks were low (average Chl a = 0.32 μg l⁻¹, range = 0.13–1.03 μg l⁻¹). Though all cells passed a 2 μm filter, electron microscopy revealed most cells were over 2 μm, principally Parmales, Phaeocystis sp., and small diatoms. CHEMTAX analysis of HPLC pigment data suggested type 8 haptophytes (e.g. Phaeocystis sp. plus Parmales and pelagophytes) contributed 7–58% of picoplanktonic chlorophyll a, type 6 haptophytes (e.g. coccolithophorids) 18–59%, diatoms 0–18% (mostly type 2 diatoms, e.g. Pseudonitzschia sp., 0–15%), prasinophytes 0–17%, with cell fragments of cryptophytes 0–40%, and dinoflagellates 0–11%. Only stocks of type 8 haptophytes and prasinophytes differed significantly due to successional changes. Zeaxanthin concentrations exceeded estimates from previous cyanobacterial counts and may derive from non-photosynthetic bacteria.     

Effects of different states of sheep fetal fibroblasts as donor cells on the early development in vitro of reconstructed sheep embryos

To investigate the effects of different states of donor cells on the development of reconstructed sheep embryos, we designed five treatments of donor cells, including cell passage, cell size, serum starvation, colchicine treatment and gene transfection. Results are as follows: (Ⅰ) Compared with 16-18 passage cells, the morula/blastocyst rate of 5-7 passage cells as donor nuclei was significantly higher (17.3% vs. 4.9%, P<0.05), suggesting the advantage of short-time cultured cells in supporting the development of reconstructed embryos. (Ⅱ) The morula/blastocyst rate of reconstructed embryos derived from medium cells (15-25μm) as donor nuclei was higher than that from large cells (25-33μm) and small cells (8-15μm)( 20.0% vs. 8.0%, 9.7%), indicating that reconstructed embryos from medium cells had a greater potentiality to develop into morula/blastocysts than those from small or large ones. (Ⅲ) The morula/blastocyst rate of reconstructed embryos from donor cells of SS (serum starvation) was lower than that from donor cells of NSS (non-serum starvation), but no significant difference was detected between SS and NSS(11.8% vs. 18.6%, P>0.05). (Ⅳ) Fetal fibroblasts treated with 0.05μmol/L colchicine exhibited a higher morula/blastocyst rate of reconstructed embryos than those treated with 0.10 μmol/L colchicine and untreated ones (27.5% vs. 12.1%, 17.1%), however, no significant difference among the three treatments was detected (P>0.05). (Ⅴ) The morula/blastocyst rate of reconstructed embryos from fetal fibroblasts transfected with GFP gene only was 3.1%, significantly lower than that from non-transgenic cells (3.1% vs. 20.4%, P<0.05). In conclusion, our results demonstrated that fetal fibroblasts of fewer passages, medium size could ensure a higher morula/blastocyst rate of reconstructed embryos. Serum starvation of donor cells might be unnecessary to the development of reconstructed embryos. Donor cells treated with 0.05μmol/L colchicine could facilitate the development of reconstructed embryos. Additionally, as cells transfected with GFP gene were used as donor nuclei, adverse effect on the development of reconstructed embryos was observed. Therefore, the developmental efficiency of reconstructed embryos could be improved if proper treatments to donor cells were used.     

Isolation and Characterization of Acetate-Utilizing Anaerobes from a Freshwater Sediment

Acetate-degrading anaerobic microorganisms in freshwater sediment were quantified by the most probable number technique. From the highest dilutions a methanogenic, a sulfate-reducing, and a nitrate-reducing microorganism were isolated with acetate as substrate. The methanogen (culture AMPB-Zg) was non-motile and rod-shaped with blunted ends (0.5–1 μm × 3–4 μm long). Doubling times with acetate at 30–35°C were 5.6–8.1 days. The methanogen grew only on acetate. Analysis of the 16S rRNA sequence showed that AMPB-Zg is closely related toMethanosaeta concilii. The isolated sulfate-reducing bacterium (strain ASRB-Zg) was rod-shaped with pointed ends (0.5–0.7 μm × 1.5–3.5 μm long), weakly motile, spore forming, and gram positive. At the optimum growth temperature of 30°C the doubling times with acetate were 3.9–5.3 days. The bacterium grew on a range of organic acids, such as acetate, butyrate, fumarate, and benzoate, but did not grow autotrophically with H₂, CO₂, and sulfate. The closest relative of strain ASRB-Zg isDesulfotomaculum acetoxidans. The nitrate-reducing bacterium (strain ANRB-Zg) was rod-shaped (0.5–0.7 μm × 0.7–1 μm long), weakly motile, and gram negative. Optimum growth with acetate occurred at 20–25°C. The bacterium grew on a range of organic substrates, such as acetate, butyrate, lactate, and glucose, and did grow autotrophically with H₂, CO₂, and oxygen but not with nitrate. In the presence of acetate and nitrate, thiosulfate was oxidized to sulfate. Phylogenetically, the closest relative of strain ANRB-Zg isVariovorax paradoxus.     

Characterization of two “Metabacterium” sp. from the gut of rodents

A new giant Gram-negative non-cultivatable symbiotic endospore-forming bacterium was found in the gut of the European hamster. This “Metabacterium” sp., provisionally named “Metabacterium criceti”, sp. n., has a length of approximately 20 μm and thickness of 4 μm. It forms 1 to 2 cylindrical endospores, approximately 9 μm long and 1.4 μm thick. TEM-micrographs show a cell wall structure characteristic of Gram-negative bacteria. Vegetative cells are filled with granules 0.3 μm in diameter which resemble starch granules. The reproduction occurs with binary fission and by formation of two endospores. Of thirteen biochemical components sought, four,i.e. glycogen, triacylglyceroles, peroxidase and alkaline phosphatase, were not found. Starch, acid mucosubstances, DNA, RNA, lipids, proteins, adenosine triphosphatase and acid phosphatase were found in different patterns, depending on the developmental stage of the bacterium. In the vegetative cell stage all these components, with the exception of starch, were found. In the endospore-bearing cell stage, only the starch-like cell component granulose could be detected. In free endospores only DNA, RNA and acid phosphatase were found. Some of the components,i.e. DNA, lipids, starch-like granulose, were linked to certain cell substructures, the distribution of others,viz. polysaccharides, RNA, adenosine triphosphatase and proteins was diffuse. The lipids, found only in vegetative cells, were associated with the cell wall. Presented in part during the19th Congress of the Czechoslovak Society for Microbiology, Košice (Slovakia) September 14–17, 1992. An erratum to this article is available at .     

Three new <Emphasis Type="Italic">Tomentella</Emphasis> species from West Africa identified by anatomical and molecular data

We used a combination of molecular-phylogenetic inference of 82 ITS rDNA sequences and anatomical approach to describe three new west African thelephoroid species, namely Tomentella afrostuposa, T. guineensis and T. guinkoi. Anatomically, T. afrostuposa is reminiscent of T. stuposa with globose to broadly ellipsoid large basidiospores of 8–14 μm, long aculei of up to 3 μm and prominent apiculi of 2 μm width. Molecular-phylogenetically, it falls within the T. stuposa complex. However, T. afrostuposa deviates by at least 7.80–10.74% from T. stuposa in regard with the ITS rDNA sequences. Tomentella guineensis is characterised by long (up to 85 μm) utriform basidia, the presence of reniform basidiospores in lateral view (up to 9 μm) with aculei not exceeding 1 μm and a strong cyanescent reaction of the subhymenial hyphae and basidia in 2.5% KOH. It forms a sister species of the newly described species Tomentella maroana; however, deviating from the last species by at least 9.75–10.04%. The very short, inflated (up to 14 μm) and thick-walled septate (septa up to 1.5 μm) subhymenial hyphae combined with ellipsoid basidiospores (up to 8 μm) and short aculei not exceeding 0.5 μm characterise Tomentella guinkoi. Anatomically, T. guinkoi recalls T. ellisii. Genetic distance between both species ranges from 12.67 to 13.73% according to ITS rDNA sequences analyses. Tomentella guinkoi forms a sister species of the group composed of T. ellisii, T. hjortstamiana and T. pisoniae. Detailed anatomical comparisons between the newly described species and their close relatives are given.     

Pigmented Nanoflagellates Grazing on <Emphasis Type="Italic">Synechococcus</Emphasis>: Seasonal Variations and Effect of Flagellate Size in the Coastal Ecosystem of Subtropical Western Pacific

We investigated seasonal variation of grazing impact of the pigmented nanoflagellates (PNF) with different sizes upon Synechococcus in the subtropical western Pacific coastal waters using grazing experiments with fluorescently labeled Synechococcus (FLS). For total PNF, conspicuous seasonal variations of ingestion rates on Synechococcus were found, and a functional response was observed. To further investigate the impact of different size groups, we separated the PNF into four categories (<3, 3–5, 5–10, and >10 μm). Our results indicated that the smallest PNF (<3 μm PNF) did not ingest FLS and was considered autotrophic. PNF of 3–5 μm in size made up most of the PNF community; however, their ingestion on Synechococcus was too low (0.1–1.9 Syn PNF⁻¹ h⁻¹) to support their growth, and they had to depend on other prey or photosynthesis to survive. The ingestion rate of the 3–5 μm group exhibited no significant seasonal variation; by contrast, the ingestion rates of 5–10 and >10 μm PNFs showed significant seasonal variation. During the warm season, 3–5 μm PNF were responsible for the grazing of 12% of Synechococcus production, 5–10 μm PNF for 48%, and >10 μm PNF for 2%. Taken together, our results demonstrate that the PNF of 3–10 μm consumed most Synechococcus during the warm season and exhibited a significant functional response to the increase in prey concentration.     

Ultrastructure of feeding tubes formed in giant-cells induced in plants by the root-knot nematodeMeloidogyne incognita

Summary The plant pathogenic nematodeMeloidogyne incognita forms conspicuous tubular structures referred to as feeding tubes in special food cells, called giant-cells, induced and maintained in susceptible host roots by feeding nematodes. Feeding tubes are formed by nematode secretions injected into giant-cells via a stylet and apparently function to facilitate withdrawal of soluble assimilates by the parasite. In giant-cells in roots of the four host species examined in this study, feeding tube morphology was identical. Tubes were straight to slightly curved structures just less than 1 μm wide and up to slightly more than 70 μm long. At the ultrastructural level, each tube consisted of a 190–290 nm thick, electron-dense, crystalline wall surrounding an electron-transparent lumen with a diameter of 340–510 nm. The distal end of the tube was sealed with wall material. Older tubes were found free in the host cytoplasm while the proximal ends of young tubes were attached to the host cell wall via short wall ingrowths through which the nematode's stylet was inserted. An elaborate membrane system was associated with the feeding tubes and was most extensive around newly formed tubes. Contiguous to the feeding tube wall, this membrane system consisted of strands of smooth endoplasmic reticulum while rough endoplasmic reticulum predominated toward the outer margin of the membrane system. Vacuoles and mitochondria were excluded from a zone of cytoplasm surrounding feeding tubes. This zone of exclusion, as well as the membrane system noted above, tended to be less pronounced or absent around older tubes no longer being used by the nematode.     

Change in striation density and systematics ofCocconeis scutellum var.Ornata (Bacillariophyceae)

Cocconeis scutellum var.ornata Grun. from three localities of Japan was studied. The striation density in 10 μm showed a marked tendency to increase with the decrease of the valve length in both raphe and rapheless valves, and this tendency did not vary with locality or environmental condition. The striation densities of rapheless valves were 4–6 in 10 μm for a valve length of 40μm, 4–6.5 for 30 μm, 6–9 for 20μm and 6.5–11 for 15μm. Those of raphe valves were 10–11 in 10μm for a valve length of 40μm, 10–12 for 30μm, 11–14.5 for 20μm and 12.5–17 for 15μm. According to the range of changing value in striation density obtained by the present study,C. scutellum var.schmidti Frenguelli andC. japonica Schmidt are identical withC. scutellum var.ornata. Dedicated to Prof. Munenao Kurogi on the occasion of his academic retirement. Culture experiment in the present study was undertaken at the Institute of Algological Research, Faculty of Science, Hokkaido University at Muroran.     

Aphanomyces infection in juvenile soft-shelled turtle,Pelodiscus sinensis,imported from Singapore

Aphanomyces sp. was isolated from the carapaces of two juvenile soft-shelled turtles with fungal infections imported from Singapore. Their sizes were 2.9–3.5 cm in carapace length. Lesions with integumental necrosis and ulceration looked like white cotton. The fungus exhibited slow growth, hyphae were 7.5–15 μm in diam, coarse, and abundantly branched. Zoosporangia observed in the isolate were complex, its entire thallus being converted into zoosporangial units, with short or long lateral evacuation tubes, and isodiametric, 100–500 μm in length. Clusters of zoospores were also produced at the terminals of hyphae. The production of the primary zoospores was achlyoid. The primary encysted zoospores were spherical, 10–15 μm in diam. No sexual stages were observed on a hemp seed incubated in sterile tap water. The optimal temperature for the fungus was 30° C.     

Cyto- and genotoxicity of a vanadyl(IV) complex with oxodiacetate in human colon adenocarcinoma (Caco-2) cells: potential use in cancer therapy

The complex of vanadyl(IV) cation with oxodiacetate, VO(oda) caused an inhibitory effect on the proliferation of the human colon adenocarcinoma cell line Caco-2 in the range of 25–100 μM (P < 0.001). This inhibition was partially reversed by scavengers of free radicals. The difference in cell proliferation in the presence and the absence of scavengers was statistically significant in the range of 50–100 μM (P < 0.05). VO(oda) altered lysosomal and mitochondria metabolisms (neutral red and MTT bioassays) in a dose–response manner from 10 μM (P < 0.001). Morphological studies showed important transformations that correlated with the disassembly of actin filaments and a decrease in the number of cells in a dose response manner. Moreover, VO(oda) caused statistically significant genotoxic effects on Caco-2 cells in the low range of concentration (5–25 μM) (Comet assay). Increment in the oxidative stress and a decrease in the GSH level are the main cytotoxic mechanisms of VO(oda). These effects were partially reversed by scavengers of free radicals in the range of 50–100 μM (P < 0.05). Besides, VO(oda) interacted with plasmidic DNA causing single and double strand cleavage, probably through the action of free radical species. Altogether, these results suggest that VO(oda) is a good candidate to be evaluated for alternative therapeutics in cancer treatment.     

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.     

The seasonal abundance and vertical distribution of the <3-μm phytoplakton in the north basin of Lake Biwa

The seasonal changes in the size-fractionated chlorophylla concentrations (<3 μm, 3 to 25 μm, and >25 μm) were investigated at a pelagic site of the north basin of Lake Biwa during June to December 1985. Autofluorescing plankton cells in the <3-μm fractions were also examined using the fluorescein isothiocyanate staining epifluorescence microscopic technique. The <3-μm phytoplankton (usually dominated by chroococcoid cyanobacteria except for a few cases dominated by small eukaryotes) showed a clearly different pattern of seasonal change compared with the larger fractions. That is, from August to early September, chlorophylla of the larger fractions declined considerably, while the <3-μm chlorophylla did not decrease significantly. Moreover, cyanobacterial cell density in the <3-μm fraction showed a maximum value (2–3.5×10⁵ cells·ml⁻¹) during this period. The relative contribution of the <3-μm chlorophylla to the total chlorophylla increased from <5% to 45% during the course of this change. No clear vertical trend in the distribution and composition of the <3-μm phytoplankton was found, except that relatively large cyanobacteria (>4 μm³) appeared at a depth of 15m but not at 0,5 and 10 m from late July to August. These large cells were also found in November and December. The drastic seasonal change of phytoplankton size structure occurring in this basin was discussed in relation to grazing, nutrient depletion and sinking. Contribution from Otsu Hydrobiological Station, Kyoto Univeristy (No. 308, foreign language series).     

Vegetative nuclei and differentiation of chromosomes inTrichophyton vanbreuseghemii

The stages of nuclear division were observed inTrichophyton vanbreuseghemii microcultures stained with Giemsa and by the Feulgen reaction. The course of karyokinesis is discussed. It takes the form of mitosis, modified by narrowing of the lumen of the hyphal cell and the movement of the cytoplasm. No spindle or centrioles were found. In vegetative hyphae (1.2–1.5 μm in diameter), the metaphase chromosomes were arranged lineally in a row following the direction of the long axis of the hyphal cell. The distribution of anaphase chromosomes occurs perpendicularly or obliquely to the cell walls. The chromosomes were spherical, with a diameter of about 0.3 μm. A haploid number of chromosomes (five) was found.     

Tracheids in white spruce seedling's long lateral roots in response to nitrogen availability

This study examined how the availability of inorganic nitrogen (N) modified the anatomical characteristics of white spruce (Picea glauca (Moench) Voss) roots related to their hydraulic properties. Seedlings were grown for one growing season in 4 L capacity pots filled with sand under one of three N levels: low (10 ppm), medium (50 ppm) and high (125 ppm). First order lateral roots with intact tips were sampled from dormant seedlings in October. Root segments were collected from 4, 10, and 14 cm distances above the root tip for fixation and sectioning and for maceration. Additional specimens were collected from the 4 and 14 cm distances for maceration and scanning electron microscopy of xylem pits. Root diameter and surface area occupied by the xylem in root cross sections increased basipetally in all treatments but exceptions were found. Higher N-levels significantly increased root diameter and surface area occupied by the xylem. In the two higher N treatments secondary root development was more advanced near the root tip than in the low N treatment. There was a strong positive correlation between root diameter and cross-sectional root area occupied by the xylem (30–50% of the root cross section) but not in portions with little secondary development. Non-conducting space within the xylem occupied 10–13% of its cross-sectional surface. Tracheids of the primary xylem were larger, had larger lumens but thinner cell walls than those of the secondary xylem. Low N treatment seedling tracheids had smaller total cross-sectional area, less lumen, and less cell wall surface area than the two other N treatments. Tracheid diameter means were between 19–20 μm in the high and medium N treatments, and 15.2 μm in the low N treatment. The range was 4.5–51.3 μm. Tracheid length was not significantly affected by N. The average tracheid was about 1000 μm long, and the range was 110–3530 μm. Pit-border diameters ranged between 4.1–20.6 μm (average 10–11 μm) and were not affected by the N treatment. Pit aperture diameters were within 0.62–10.2 μm range (average between 3–4 μm) and were also not significantly affected by the N treatment, although tracheids from the medium N-treatment roots tended to have larger apertures. The pit border diameter equals that of the margo while the aperture size should be similar to that of the torus of the pit membrane. If the capacity for axial water transport in spruce roots is affected by N, it would be by its impact on conduit diameter and, possibly on the pit-membrane pore sizes but not by changes to conduit length and to the size of the pit membrane surface area. This revised version was published online in June 2006 with corrections to the Cover Date.     

Disturbances of energetic metabolism in rat epididymal epithelial cells as a consequence of chronic lead intoxication

Adult male Wistar rats were intoxicated with 1% lead acetate (PbAc) administered in drinking water for nine months, which amounts to a period five times longer than the duration of one spermatogenesis. There were mitochondrial ultrastructure disorders of epididymal epithelial cells observed in PbAc-treated rats; also a significant lead-induced decrease in ATP concentration in epididymal epithelial cells (by 32%, P < 0.05), Adenylate Energy Charge value (AEC) (by 8%, P < 0.05) and an increase in ADP (28.5%, P < 0.05), AMP (27%, P < 0.05) and adenosine (by 56%, P < 0.05). The results were measured using high performance liquid chromatography (HPLC) and detected even at low lead concentrations in whole blood (M:7.03 μg/dL; Q1–Q3: 2.99–7.65). The function of mitochondria in cultured epididymal epithelial cells of control and PbAc-treated animals were evaluated using fluorophores: Mitotracker Green FM and JC-1. After incubation with Mitotracker Green FM, we observed active mitochondria producing bright green fluorescence in the cytoplasm of cultured epididymal epithelial cells, both in the control group and the Pb-treated animals. Incubation of cultured epididymal epithelial cells of animals from both groups produced red-orange fluorescence with the mitochondrial JC-1 probe indicating mitochondria with high membrane potential (ΔΨm > 80–100 mV) and green fluorescence in the mitochondria with low membrane potential (ΔΨm <80 mV). The results showed that a chronic low-level exposure to lead, even without severe clinical symptoms of contamination, disrupted the ultrastructure and energy metabolism of mitochondria in epididymal epithelial cells.