Problems in estimating growth rates of marine phytoplankton from short-term14C assays

Growth rate estimates () of phytoplankton populations that were sampled from nitrogen-limited continuous cultures and then incubated for short durations in batch culture with added¹⁴C-HCO₃ ^– were significantly different than steady-state growth rates () for 3 of 5 marine phytoplankton species. Two diatoms,Thalassiosira weissflogii andChaetoceros simplex, displayed virtually identical growth rates (=) over a wide range of, whereas for a third diatom,Phaeodactylum tricornutum, was overestimated by an average of 40% compared to. In contrast, was underestimated by the¹⁴C technique for the two remaining species: up to 40% at a steady-state of 1.0 day^–1 for the chlorophyteDunaliella tertiolecta and up to 100% at of 1.4 day^–1 for the haptophytePavlova lutheri. For the latter two species the divergence between and appeared to increase with increasing steady-state. A simple model of labeled and total carbon flow between the aqueous phase and cellular biomass was constructed to demonstrate that respiration was negligible when=, but was significant when>. In the cases in which<, a rapid physiological alteration presumably took place once the steady state was disturbed and cells were placed in the incubation chambers, which perhaps was related to the nutritional state of the cultures at the time of sampling. Questions thus are raised regarding our ability to measure accurately primary productivity from shipboard experiments with confined samples of phytoplankton from nutrient-impoverished waters that probably are less hardy than the laboratory cultures used in these studies.     

Karyometry of nuclei in liver cells

Summary In untreated adult male albino rats nuclear volume and the percentage of binucleate cells were determined in the first layer of hepatocytes adjacent to hepatic venous branches of varying diameters (<40 m, 40 m–80 m, 80 m–120m, 120 m–160 m, >160 m), and in the third and fourth layer of hepatocytes in the remainder of the perivenous parenchyma. In the first layer of hepatocytes adjacent to the vascular structures means of nuclear volume are significantly lower and percentage of binucleate cells significantly higher than in the cells of the remainder of the perivenous parenchyma. Within each area measured distribution curves of nuclear volume classes were homogeneous but showed heterogeneity in comparison with each other. The morphometric data presented in this study strongly support the opinion of the heterogeneity of liver cells in the perivenous zone, as previously postulated on the basis of histochemical investigations.Supported by the Deutsche Forschungsgemeinschaft (Hi 318/2-1)     

Electron microscopy of double-stranded RNA induced by turnip yellow mosaic virus and tobacco mosaic virus

Summary Double-stranded RNA isolated by phenol extraction from turnip yellow mosaic virus-infected chinese cabbage leaves and from tobacco mosaic virus-9nfected tobacco leaves was rotary shadowed and examined in the electron microscope. The TYMV and TMV molecules are similar in appearance, having uniform width and a linear configuration similar to that previously described for double-stranded RNA and double-stranded DNA molecules. More than 99.5% of the molecules of each virus fall within the range 0.1 to 2.2 , there being a predominance of smaller molecules in both cases (TYMV mean=0.24 , TMV mean 0.42 ). The mode of the larger molecules of TYMV 1.92 and of TMV 1.8 . These values are close to the expected lengths of whole molecules, calculated from biophysical data. Apparently branched molecules were observed in preparations of both TYMV and TMV double-stranded RNA. It was found, however, that the number of such branches per unit length of RNA decreases with a decrease in density of the RNA in the fields examined.     

Artemisia annua L.: dedifferentiated and differentiated cultures

Dedifferentiated and differentiated tissue cultures ofArtemisia annua L. for artemisinin production were carried out. The calluses were initiated on MS medium supplemented with sucrose (30 g l^-1), myoinositol (100 mg l^-1) and RT vitamins. The auxins used were naphtaleneacetic acid (NAA), indoleacetic acid (IAA), indolebutyric acid (IBA) and 2,4-dichlorophenoxyacetic acid (2,4-d). These were added to the basal medium either singly or in combination. The best results were obtained with 2.4-d (4.5 M : 0.02 d^-1) and NAA (5.4 M : 0.06 d^-1). Cell suspensions were established on the same media without agar. Suspension cultures showed different morphological characteristics according to the plant growth regulator supplied. Organized cultures were initiated from callus obtained on 2,4-d (4.5 M) and from bud cultures. Medium containing 6-benzylaminepurine (BA) (8.9 M)+NAA (0.54 M); Zeatin (45.62 M)+NAA (5.37 M) or BA (8.9 M) stimulated both organogenesis in callus (frequency of induction =50%) and semi-organized tissue in shoot buds. BA (13.32 M)+NAA (1.08 M) or BA (13.32 M) only stimulated multiple shoot cultures (frequency of induction =80%). Regarding artemisinin content, while the values obtained were 1.13 and 0.78 mg gDW^-1 in primary callus, artemisinin was not detected in cell suspension and only traces of it were found in multiple shoot cultures.     

Procedures for the axenic isolation of conchocelis and monospores from the red seaweed Porphyra yezoensis

In order to maintain axenic seedstock cultures axenically of thecommercially important red seaweed, Porphyra yezoensis, aprocedure was developed for axenic isolation and culture of conchocelis andmonospores. For axenic isolation of the conchocelis, contaminated microalgaewere most effectively removed by filtering contaminated samples through a100-m mesh after sonication. Removal of bacteria and otheralgaewas accomplished using a mixture of 5 agents (0.02% chitosan, 100 gml^–1 GeO₂, 10 gml^–1 ampicillin, 40 gml^–1 kanamycin and 200 gml^–1 streptomycin). Axenic single colonies wereisolatedfrom a semi-solid medium prepared from 1% transfer gel. After collectingmonospores from the 40–50% density layer on a percoll-gradient, removalofbacteria and fungi from the monospores was accomplished using a mixture of 5antibiotics (3.5 g ml^–1 nystatin, 2 mgml^–1 ampicillin, 400 gml^–1 kanamycin, 50 gml^–1 neomycin and 800 gml^–1 streptomycin). Axenic single juvenile blades wereisolated from a semi-solid medium prepared from 0.5% transfer gel.     

Organogenesis versus embryogenesis from long-term suspension cultures of cucumber (Cucumis sativus L.)

Suspension cultures were initiated from leaf explant-derived callus of cucumber,Cucumis sativus cv. Hokus, and maintained under two different conditions; (I) continuously in medium with 5 M 2,4-D + 5 M BA, and (II) alternately three cultures in medium containing 5 M NAA + 5 M BA and one culture in 5 M 2,4-D + 5 M BA. After plating on solid medium with 0.5 M KIN + 0.1 M IAA, suspension aggregates from long-term culture in medium with 2,4-D developed into callus, and subsequently formed somatic embryos. These embryos, however, hardly developed into plants. They showed growth arrest and several structural abnormalities. In contrast, organogenesis took place when suspension aggregates from NAA containing medium were plated on solid medium with 0.5 M KIN + 0.1 M IAA. Numerous adventitious buds were regenerated, which quite normally developed into plants. Sucrose at low concentration of 1% improved plant formation. On the average thirty complete plants were obtained from each ml of suspension. It is discussed why adventitious buds develop into plants so well, whereas somatic embryos are prone to growth arrest and abnormal development.Abbreviations BA 6-benzylaminopurine - KIN kinetin - IAA indole-3-acetic acid - NAA 1-naphthaleneacetic acid - 2,4-D 2,4-dichlorophenoxyacetic acid     

Differences of the electrical and nicotinic receptor stimulation-evoked liberation of norepinephrine from chicken sympathetic neurons in culture: Possible involvement of different pools of the transmitter

We studied the release of [³H]norepinephrine from chicken sympathetic neurons in culture evoked by nicotinic and electrical stimulation with an intention to establish functional identity or nonidentity of the two stimuli in investigations of neurotransmitter release. Nicotinic stimulation evoked extracellular calcium dependent release of [³H]norepinephrine and the rise of intracellular calcium concentration. The release was completely blocked by nicotinic antagonists hexamethonium (100 mol/l) and mecamylamine (10 mol/l), and decreased by tetrodotoxin (0.3 mol/l) and -conotoxin (0.1 mol/l) to 17% and 27%, resp. The intracellular calcium response was decreased by nicotinic antagonists and tetrodotoxin, but not changed by -conotoxin. The electrical stimulation-evoked release was blocked by both tetrodotoxin and -conotoxin, and decreased by previous electrical, but not nicotinic, stimulation. The differential sensitivity to -conotoxin and tetrodotoxin, and the inability of nicotinic stimulation to decrease the liberation by following electrical stimulation may suggest the mobilization of different pools of the transmitter.     

Silver nitrate and aminoethoxyvinylglycine affect <Emphasis Type="Italic">Agrobacterium</Emphasis>-mediated apple transformation

In Fuji, the production of ethylene was increased with the addition of AgNO₃ and inhibited with the addition of 10 M aminoethoxyvinylglycine (AVG). The addition of 80 M AgNO₃ to transformed explants of Fuji cultured on selection medium resulted in increased ethylene production (20 l l^–1) at 3 weeks. Under examining the effect of AgNO₃ in Fuji, the 40 M AgNO₃ showed with higher 33.8% and 6.5% in the efficiency of regeneration and transformation. However, ethylene production in Gala explants treated with 10M AgNO₃ (3 l l^–1) decreased after 2 weeks compared with the control (5 l l^–1). Although the regeneration efficiency of Gala with 10 M AgNO₃ was higher (41.1%) than the control (20.1%), there was no significant difference in the transformation efficiency at the same concentration. Shoot regeneration of Fuji and Gala was completely inhibited with 10 M AVG. These results suggest that the addition of AgNO₃ affects the efficiency of Agrobacterium-mediated gene transfer in Fuji.Eun Soo Seong, Ill Min Chung- These two Authors Contributed equally to this work     

The effect of monoterpenes on astaxanthin production by a mutant ofPhaffia rhodozyma

Summary The total pigment and astaxanthin content ofPhaffia rhodozyma increased with increasing concentrations -pinene up to 500 l -pinene/l. Above this concentration the total pigment and astaxanthin content as well as the biomass production decreased. The addition of 500 l -pinene/l increased the total pigment content from 1652 g/g to 2201 g/g and the astaxanthin content from 1554 g/g to 1883 g/g. A sharp decrease in maximum specific growth rate occurred above 150 l -pinene/l.     

Zinc protects against arsenic-induced apoptosis in a neuronal cell line,measured by DEVD-caspase activity

Acute and chronic arsenic exposure results in toxicity in humans and causes many neurological and other manifestations. For the first time the present study reports that zinc decreases arsenic-induced apoptosis and also confirms a single report of apoptosis induced by arsenic in a neuronal cell line. Apoptosis measured by DEVD-caspase activity peaked between 10 M and 20 M of arsenic trioxide. Higher concentrations of arsenic up to 40 M caused increasing cell death with diminishing DEVD-caspase activity. The beneficial effect of zinc was proportional to its concentration with a significant decrease in arsenic-induced DEVD-caspase activity at 50 M and 75 M zinc (P<0.05). This finding may be of therapeutic benefit in people suffering from chronic exposure to arsenic from natural sources, a global problem especially relevant to millions of people on the Indian subcontinent.     

Coccidia of Brazilian edentates: Eimeria cyclopei n.sp. from the silky anteater,Cyclopes didactylus (Linn.) and Eimeria choloepi n.sp. from the two-toed sloth,Choloepus didactylus (Linn.)

Summary Eimeria cyclopei n.sp. is described from the silky anteater, Cyclopes didactylus, from Pará State, north Brazil. Undifferentiated oocysts, passed in the faeces, complete sporulation in seven days at 26 to 28°C. Oocysts are ellipsoidal to sub-spherical, with a mean size of 28.1 × 23.6 m: the wall is 1.5 to 2.0 m thick, apparently with an outer thin, colourless membrane and two inner, thicker, striated and yellowish layers. There is no micropyle, oocyst residuum or polar body. The mean measurements of sporocysts are 19.0 × 9.0 m, and they are slightly asymmetrical, elongate pear-shape, with a plug-shaped Steida body projecting beyond the end of the sporocyst. Sporozoites are as long as or longer than the sporocysts: The sporocyst residuum is scattered between sporozoites in younger specimens and becomes condensed into rounded mass in older ones. The endogenous stages occur in the epithelial cells of the ileum, on the lumenal side of the host-cell nucleus. Uninucleate meront, microgamont and macrogamont precursors are recognizable morphologically. Mature meronts are 20.0 × 15.7 m some produce 12 to 20 merozoites which are 8.7 × 2.0 m, and others 10 to 26 merozoites which are 11.4 × 2.0 to 15.0 × 3.0 m. Mature microgamonts which are 27.5 × 24.1 m, produce from 150 to 170 microgametes of 7.1 × 1.0 m: microgametes have two flagella of unequal length. Mature macrogamonts are 28.4 × 24.5 m Eimeria choloepi n.sp. is recorded from the two-toed sloth, Choloepus didactylus, from the same area of Brazil. Undifferentiated oocysts, passed in the faeces, complete sporulation in 23 days at 26 to 28°C. Oocysts with a mean size of 23.0 × 20.3 m, have a wall 2.0 to 2.5 m thick which is composed of two thick, yellowish and striated outer layers and a delicate, colourless inner one. There is no micropyle, oocyst residuum or polar granule. Mature sporocysts with a mean size of 11.3 × 7.1 m, are ellipsoidal to egg-shaped and have a poorly developed Steida body. The sporocyst residuum is composed of a small number of large globules: The sporozoites are longer than the sporocyst and strongly recurved. The endogenous stages occur in epithelial cells of the ileum, on the lumenal side of the host-cell nucleus. Dimorphic meronts produce 8 to 18 merozoites which are either 13.0 × 2.0 m or 13.0 × 3.0 m. Microgamonts produce 50 to 80 microgametes of 8.0 × 1.0 m. Mature macrogamonts are 18.3 × 17.9 m. ac]19820212     

Endogenous phosphorylation of rat brain synaptosomal plasma membranes in vitro: Some methodological aspects

The time course of endogenous phosphorylation in vitro of total or separted synaptic plasma membrane proteins (SPM) has been correlated with that of hydrolysis of the phosphate donor (ATP) in the incubation medium. The ATP/SPM ratio in the medium was varied. In a low-ratio medium (7.5 M ATP; 2.2 g SPM/l) a complete hydrolysis of ATP occurred almost instantaneously as was measured by the release of free phosphate in and the disappearance of ATP from the medium. As a consequence, only a very short peak of phosphorylation, followed by dephosphorylation was observed. However, when higher ATP/SPM ratios were used (200 M ATP; 0.4 g SPM/l and 500 M ATP; 0.4 g SPM/l), the incorporation of phosphate into SPM proteins was linear for 20 sec, and the maximum level of phosphate incorporation was increased. Similar results were obtained after separation of³²P-labeled phosphoproteins by slab gel electrophoresis. However, analysis of the autoradiographs obtained fromone SPM preparation under different ATP/SPM ratios revealed dependence of phosphorylation of individual protein bands on the conditions used.     

Das Cytostom von Lankesterella garnhami

Zusammenfassung Die Nahrungsaufnahme der Merozoiten von Lankesterella garnhami in den Milzzellen von Hamburger Hausspatzen (Passer d. domesticus) wurde elektronenmikroskopisch untersucht. Teile des Wirtszytoplasmas gelangen durch Abschnürung zahlreicher, etwa 20–30 m. großer Pinozytosevesikel in das Lumen der periparasitären Vakuole. Von dem Inhalt der periparasitären Vakuole werden Teile mit Hilfe mehrerer Cytostomstrukturen in Nahrungskanäle aufgenommen, von denen sich 100–200 m große Nahrungsvakuolen abschnüren, in denen die weitere Verdauung stattfindet. Das Cytostom ist durch zwei intensiv kontrastierte, konzentrische Zylinder charakterisiert, die sich von den beiden Pelliculamembranen ableiten. Der innere Durchmesser beträgt ca. 80m, der äußere Durchmesser ca. 150 m und die Tiefe im Ruhestadium mindestens 50–100 m. Die Bedeutung des Cytostoms als taxonomisches Merkmal wird diskutiert.

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The cytostome of Lankesterella garnhami

Summary The feeding mechanism of merozoites of Lankesterella garnhami in the cells of the spleen of young sparrows (Passer d. domesticus), which were captured in Hamburg, was studied by means of electron microscopy. The cytoplasm of the host cell permeates the membrane of the periparasitic vacuole by means of pinocytosis of vesicles with a diameter of 20–30 m. The parasite takes up parts of the content of the periparasitic vacuole with several cytostome structures. This structure consists of two electron dense, concentric cylinders, which originate from the two membranes of the pellicle. The cytostome is 80 m in the inner diameter and 150 m in the outer diameter. The depth of the inactive cytostomal cavity is about 50–100 m, whereas it is much prolonged in the stage of active feeding. In this stage the cytostome opens into a channel of 400–800 m and more, from which food vacuoles of 100–200 m are pinched off. Digestion occurs in the food vacuole. These findings are compared with observations of the cytostome and the micropyle in other sporozoa. Sometimes long, V-shaped invaginations of unknown signification are noticed.

     

Aluminum-induced secretion of both citrate and malate in rye

Aluminum (Al)-resistant mechanisms responsible for Al-induced secretion of organic acids are poorly understood. In this study, we characterized the Al-induced secretion of both citrate and malate from rye (Secale cereale L. cv. King). Secretion of organic acids increased with increasing concentration (10, 30 and 50 M) and duration of Al treatments. Neither phosphorous (P) deficiency up to 15 days nor addition of 50M lanthanum, 50 M lead, 10 M cadmium, or 200 M manganese caused secretion of organic acids, suggesting that this secretion was a specific response to Al stress. Aluminum activated citrate synthase, the main enzyme for the synthesis of citrate, but its activation occurred only in the root tip. The elongation of roots of an Al-sensitive cultivar of wheat (Tritium aestivum L. cv. Scout 66) was not inhibited by 50 M Al in the presence of externally applied 50 M citrate or 400 M malate. The secretion of citrate and malate from intact rye roots exposed to 50 M Al corresponded to 31.3 ± 1.7 M and 11.5 ± 2.5 M, respectively, in the rhizosphere based on an assumption of a 2 mm thick unstirred layer around root tips. This result indicated that Al-resistance in rye was achieved by the Al-induced synthesis of citrate in root apices followed by Al-induced specific secretion of citrate from root tips.     

Determination of copper, manganese and zinc in human liver

Autopsied liver tissue samples collected from 42 males and 31 females were analyzed for copper, manganese and zinc using atomic absorption spectrometry (AAS). With the exception of two liver samples for which the copper levels were determined to be 74.8 and 104.0 g/g (dry weight), hepatic copper concentrations were found to range from 1.7 to 32.4 g/g with a mean concentration of 14.2 g/g and standard deviation of 7.0 g/g. Manganese concentrations (with the exception of one sample having 12.9 g/g) ranged from 0.22 to 4.6 g/g with a mean of 2.26 ± 1.00 g/g. Hepatic zinc levels averaged 118.3 ± 44.4 g/g and ranged from 38.5 to 231.3 g/g. There were no apparent trends for the levels of any metals versus age nor were there any differences in average hepatic metal concentrations for males and females. © Rapid Science 1998.     

Development of an L6 myoblast in vitro model of moniliformin toxicosis

L6 myoblasts were used as an in vitro model to investigate the role of moniliformin and its interaction with monensin in turkey knockdown syndrome and sudden death syndromes in poultry. Cell viability and microscopic and ultrastructural alterations noted in L6 myoblasts cultured in the presence of moniliformin (0.0–0.3 g/l) were compared to those observed in parallel cultures also containing one of the following compounds: selenium (0–0.004 ng/l), thiamine (0–0.3 g/l), or pyruvate (0–0.46 g/l). Marked dilation of the RER, membranous whorls, glycogen deposition, membrane-bound cytoplasmic inclusions and necrosis were observed in myoblasts exposed to 0.03/2-0.30 g moniliformin/l medium. Supplementation of medium with thiamine and pyruvate, or selenium, provided significant protection to cells exposed to 0.0–0.3 g/l or 0.0–0.15 g moniliformin/l, respectively. Dose-dependent differences in protein and ATP production were not detected. Myoblasts grown in medium containing 0–0.15 g moniliformin/l and 7.5–50.0 M A23187, beauvericin or monensin had degrees of cytotoxicity similar to parallel cultures receiving only an ionophore. L6 myoblasts were a useful model of moniliformin toxicosis. The findings of this study suggest cytotoxicity due to moniliformin in L6 myoblasts may be due in part to oxidative damage and altered pyruvate metabolism, and that moniliformin does not predispose myoblasts to ionophore toxicosis. This study supports the results of in vivo investigations in poultry that moniliformin and monensin do not act synergistically to induce knockdown or monensin toxicosis.     

Location of ethylene production in cotton flowers and dehiscing fruits

Summary Over half of the ethylene produced by 1-day-old cotton flowers came from the combined stigma, style, and stamens. These tissues produced 0.0050 l/flower·h compared to 0.0024 and 0.0010 l/flower·h produced by the petals and ovary, respectively. Walls of dehiscing cotton fruits produced 0.052 l ethylene/fruit·h. This was approximately 50% more than seeds plus fiber which produced 0.033 l/fruit·h.     

In vitro micropropagation of Piper longum – an important medicinal plant

Efficient and rapid tissue culture systems were developed for Piper longum, an important medicinal plant, through shoot tip multiplication and direct regeneration. Multiple shoots were induced from shoot tips cultured on agar-based Murashige and Skoog (MS) medium containing 4.44–22.19 M benzyladenine (BA) and 4.64–13.9 M kinetin (K). Maximum number of shoots were induced with 8.9 M BA and 4.64 M K. Adventitious shoot regeneration from leaf segments was achieved on MS containing 3.6–22.19 M BA along with 3.31–12.4 M picloram (P). Shoot differentiation occurred directly from the leaf bases without intermediale callus formation. Maximum shoot buds were obtained on MS medium with 17.76 M BA and 8.28 M P. Elongated shoots were separated and rooted in MS supplemented with 2.46 M indole butyric acid (IBA). Plantlets, thus developed were established in soil.     

Plasma α- and γ-tocopherol have different pattern during normal human pregnancy

Plasma - and -tocopherol were monitored in pregnant women throughout healthy gestational periods and after delivery and were compared with that of non pregnant women. The mean plasma -tocopherol and -tocopherol concentrations in non pregnant Saudi women (15.2 ± 1.3 and 1.8 ± 0.2 ol/l respectively) were found within normal range. The maternal plasma -tocopherol level steadily increased reaching maximum level (19.1 ± 1.6 mol/l) at late gestation and then gradually decreased after delivery. On the contrary, the optimum level of -tocopherol (2.1 ± 0.2 mol/l) was at mid gestation, followed by a progressive decrease until one month after delivery (1.5 ± 0.1 ol/l). This study shows that the maternal plasma - and -tocopherol have different profiles that may be attributed to their different responses to the changes in maternal lipids during pregnancy.     

Respiration rates of Chiloplacus sp. and other arctic nematodes at low and high temperatures

Summary Respiration of an undescribed species of soil nematode of the genus Chiloplacus from the Canadian High Arctic was measured at 2°, 5°, 10°, 15°, 20° and 25°C. The corresponding metabolic rates were 0.2697×10^-3 l, 0.3406×10^-3 l, 0.8408×10^-3 l, 0.8539×10^-3 l, 1.8420×10^-3 l and 2.9360×10^-3 l O₂ ind^-1 h^-1, respectively, for a nematode of 1.0 g dry weight. The relationship between respiration and dry weight for Chiloplacus sp. at 10°C is described by the function log R=-3.0693+0.8844 log W. Q₁₀ values for the 2°–5°, 5°–10°, 10°–15°, 15°–20° and 20°–25°C temperature intervals were 2.18, 6.09, 1.03, 4.65 and 2.54, respectively. Chiloplacus sp. showed raised metabolic rates at low tempetatures compared with species from warmer environments. Metabolic rates of representative samples of the soil, nematode fauna (dominated by individuals of the genus Plectus) from the same location were 0.1593×10^-3 l, 0.3603×10^-3 l and 0.5332×10^-3 l O₂ ind^-1 h^-1 at 5°, 10° and 15°C for an average nematode of 0.4297 g dry weight.