Catalase activity in developing seedling of opium poppyPapaver somniferum L

Catalase is an enzyme unique to glyoxysomes in developing poppy seedlings. Catalase activity is very low in endosperm and in embryo of germinating poppy seeds. During postgerminative growth and development the enzyme activity increases rapidly with maximum in endosperm on day 2 and in developing seedling on day 3. A rapid decline of enzyme activity parallells the extension growth of poppy seedlings. Three electrophoretic forms of catalase have been detected in isolated glyoxysomes and partially purified catalase preparation. Electron microscopic observation indicates the presence of catalase in glyoxysomes of parenchyma cells of poppy seedling cotyledons. Numerous lipid bodies and electron-dense deposits in vacuoles are the most characteristic feature of these cells.     

Ethionine regulates cell motile activity through LPA receptor-3 in liver epithelial WB-F344 cells

Lysophosphatidic acid (LPA) receptors (LPA₁ to LPA₆) indicate a variety of cellular responses, such as cell proliferation, migration, differentiation, and morphogenesis. However, the role of each LPA receptor is not functionally equivalent. Ethionine, an ethyl analog of methionine, is well known to be one of the potent liver carcinogens in rats. In this study, to assess whether ethionine may regulate cell motile activity through LPA receptors, rat liver epithelial (WB-F344) cells were treated with ethionine for 48 h. In cell motility assay with a cell culture insert, the treatment of ethionine at 1.0 and 10 μM enhanced significantly high cell motile activity, compared with untreated cells. The expression levels of LPA receptor genes in cells treated with ethionine were measured by quantitative real time RT-PCR analysis. The expression of the Lpar3 gene in ethionine-treated cells was significantly higher than that in untreated cells. Furthermore, to confirm an involvement of LPA₃ on cell motility increased by ethionine, the Lpar3 knockdown cells were also used. The cell motile activity by ethionine was completely suppressed in the Lpar3 knockdown cells. These results suggest that LPA signaling through LPA₃ may be involved in cell motile activity stimulated by ethionine in WB-F344 cells.     

A Small Multidrug Resistance-like Transporter Involved in the Arabinosylation of Arabinogalactan and Lipoarabinomannan in Mycobacteria

The biosynthesis of the major cell envelope glycoconjugates of Mycobacterium tuberculosis is topologically split across the plasma membrane, yet nothing is known of the transporters required for the translocation of lipid-linked sugar donors and oligosaccharide intermediates from the cytoplasmic to the periplasmic side of the membrane in mycobacteria. One of the mechanisms used by prokaryotes to translocate lipid-linked phosphate sugars across the plasma membrane relies on translocases that share resemblance with small multidrug resistance transporters. The presence of an small multidrug resistance-like gene, Rv3789, located immediately upstream from dprE1/dprE2 responsible for the formation of decaprenyl-monophosphoryl-β-d-arabinose (DPA) in the genome of M. tuberculosis led us to investigate its potential involvement in the formation of the major arabinosylated glycopolymers, lipoarabinomannan (LAM) and arabinogalactan (AG). Disruption of the ortholog of Rv3789 in Mycobacterium smegmatis resulted in a reduction of the arabinose content of both AG and LAM that accompanied the accumulation of DPA in the mutant cells. Interestingly, AG and LAM synthesis was restored in the mutant not only upon expression of Rv3789 but also upon that of the undecaprenyl phosphate aminoarabinose flippase arnE/F genes from Escherichia coli. A bacterial two-hybrid system further indicated that Rv3789 interacts in vivo with the galactosyltransferase that initiates the elongation of the galactan domain of AG. Biochemical and genetic evidence is thus consistent with Rv3789 belonging to an AG biosynthetic complex, where its role is to reorient DPA to the periplasm, allowing this arabinose donor to then be used in the buildup of the arabinan domains of AG and LAM.     

Biological and structural characterization of the Mycobacterium smegmatis nitroreductase NfnB,and its role in benzothiazinone resistance

Tuberculosis is still a leading cause of death in developing countries, for which there is an urgent need for new pharmacological agents. The synthesis of the novel antimycobacterial drug class of benzothiazinones (BTZs) and the identification of their cellular target as DprE1 (Rv3790), a component of the decaprenylphosphoryl‐β‐d ‐ribose 2′‐epimerase complex, have been reported recently. Here, we describe the identification and characterization of a novel resistance mechanism to BTZ in Mycobacterium smegmatis. The overexpression of the nitroreductase NfnB leads to the inactivation of the drug by reduction of a critical nitro‐group to an amino‐group. The direct involvement of NfnB in the inactivation of the lead compound BTZ043 was demonstrated by enzymology, microbiological assays and gene knockout experiments. We also report the crystal structure of NfnB in complex with the essential cofactor flavin mononucleotide, and show that a common amino acid stretch between NfnB and DprE1 is likely to be essential for the interaction with BTZ. We performed docking analysis of NfnB‐BTZ in order to understand their interaction and the mechanism of nitroreduction. Although Mycobacterium tuberculosis seems to lack nitroreductases able to inactivate these drugs, our findings are valuable for the design of new BTZ molecules, which may be more effective in vivo.     

Comparison of sampling tabanids (Diptera: Tabanidae) by four different potential attractants

Synthetic and natural attractants in traps are used in many parts of the world to attract female tabanids. Certain attractants in different geographic regions may be ineffective or effective under different environmental conditions for horseflies. One‐octen‐3‐ol, as a compound present in bovine emanations, has a behavioural effect on many horsefly species and together with other phenolic compounds makes very effective attractant for this group of insects. As the attractiveness of the mixture of three chemicals (1‐octen‐3‐ol, acetone and ammonia solution in the proportions 5 : 3 : 2), aged donkey urine, lactic acid and fresh human urine is not yet known, it was studied in Eastern Croatia. The combination of those three chemicals and efficiency of natural attractants offers promising results. Tabanus was the most represented genus with 83% of the total collected tabanids. The chi‐squared analyses of the trapping data for canopy traps revealed that each of the attractants (mixture of three chemicals, aged donkey urine, lactic acid and fresh human urine) significantly increased the number of collected horseflies in comparison to those collected in unbaited canopy traps. Some species differences in relative response to different attractants were noted. Significantly, more specimens of Haematopota pluvialis were collected from canopy traps baited with the mixture of three chemicals when compared with traps baited with other attractants. Canopy traps baited with aged donkey urine collected significantly more Atylotus loewianus females than did traps baited with the mixture. The F‐test analysis of the trapping data for the genus Tabanus showed that there is significant difference between average number of collected specimens between mixture of three chemicals and other used attractants (lactic acid and human urine) except aged donkey urine. Finally, traps baited with the mixture of three chemicals (1‐octen‐3‐ol, acetone and ammonia solution) collected 14.5 times more tabanids than unbaited traps, whereas aged donkey urine, lactic acid, and fresh human urine‐baited traps collected 12, 3.9 and 2.5 times as many tabanids, respectively, than did unbaited traps. The mixture of three chemicals (1‐octen‐3‐ol, acetone and ammonia solution) and aged donkey urine appear to be very effective attractants for tabanids.     

Radicle ofEchinocactus platyacanthus (Cactaceae)

Radicle of matureEchinocactus platyacanthus embryo is approximately 320 m long and represents less then 1/7 of the embryonal axis length. The radicle-hypocotyl boundary can be distinguished according to the striking difference in the size and shape of cells in protoderm and procambium, as well as discontinuity and different number of the cell files in the ground meristem. The root cap is small, consists of 4 layers of cells covering the apex of the radicle. The upper limit of the root cap is approximately 100 m closer towards the radicle tip than the radicle-hypocotyl boundary. Ultrastructure of radicle cells showed numerous lipid bodies as is typical for other oily seeds. Protein bodies of variable structure were also present together with other cell structures. Striking differences in protein body structure were found when protoderm and ground meristem were compared. Several small globoid crystals were present in each protein body of the protoderm, while protein bodies in the radicle ground meristem mostly contained one large globoid crystal. X-ray microanalysis revealed presence of P, K and Mg in all analyzed globoid crystals. Fe, Ca and Zn were detected in some of them.Abbreviations EDX microanalysis energy-dispersive X-ray microanalysis - GC(s) globoid crystals - ICP spectroscopy ion-coupled plasma spectroscopy - LM light microscopy - PB(s) protein bodies - SEM scanning electron microscopy - TEM transmission electron microscopy     

Somatic embryogenesis of <Emphasis Type="Italic">Gentiana cruciata</Emphasis> (L.): Histological and ultrastructural changes in seedling hypocotyl explant

Summary Structure and ultrastructure changes that occurred during tissue culture of upper explants of hypocotyl (adjacent to cotyledons) of 10-d-old seedlings of Gentiana cruciata were studied. The explants were cultured on Murashige and Skoog induction medium supplemented with 1.0 mg l⁻¹ dicamba +0.1 mg l⁻¹ naphthaleneacetic acid +2.0 mg l⁻¹ benzyladenine +80.0 mg l⁻¹ adenine sulfate. The initial response of the explant and callus formation were ultrastructurally analyzed during the first 11 d of culture. After 6–8 wk, various methods were employed to collect evidence of indirect somatic embryogenesis. After 48 h of culture, the earliest cell response was cell division of epidermis and primary cortex. There were numerous disturbances of karyo- and cytokinesis, leading to formation of multinuclear cells. With time, the divisions ceased, and cortex cells underwent strong expansion, vacuolization and degradation. About the 6th day of culture, callus tissue proliferated and the initial divisions of vascular cylinder cells were observed. Their division appeared normal. Cells originating from that tissue were small, weakly vacuolated, with dense cytoplasm containing active-looking cell organelles. Numerous divisions occurred in the vascular cylinder, which led to its expansion and the formation of embryogenic callus tissue. During the 6–8th wk of culture, in the proximal end of the explant, masses of somatic embryos were formed from outer parts of intensively proliferating tissue.     

Genetic Characteristics of Japanese Clinical Listeria monocytogenes Isolates

Listeria monocytogenes causes foodborne illnesses through consumption of ready-to-eat foods. Although 135-201annual listeriosis cases have been estimated in Japan, the details regarding the clinical isolates such as infection source, virulence level, and other genetic characteristics, are not known. In order to uncover the trends of listeriosis in Japan and use the knowledge for prevention measures to be taken, the genetic characteristics of the past human clinical isolates needs to be elucidated. For this purpose, multilocus tandem-repeat sequence analysis (MLTSA) and multi-virulence-locus sequence typing (MVLST) were used in this study. The clinical isolates showed a variety of genetically distant genotypes, indicating they were from sporadic cases. However, the MVLST profiles of 7 clinical isolates were identical to those of epidemic clone (EC) I isolates, which have caused several serious outbreaks in other countries, suggesting the possibility that they have strong virulence potential and originated from a single outbreak. Moreover, 6 Japanese food isolates shared their genotypes with ECI isolates, indicating that there may be risks for listeriosis outbreak in Japan. This is the first investigational study on genetic characteristics of Japanese listeriosis isolates. The listeriosis cases happened in the past are presumably sporadic, but it is still possible that some isolates with strong virulence potential have caused listeriosis outbreaks, and future listeriosis risks also exist.     

Social interactions of juvenile brown boobies at sea as observed with animal-borne video cameras

While social interactions play a crucial role on the development of young individuals, those of highly mobile juvenile birds in inaccessible environments are difficult to observe. In this study, we deployed miniaturised video recorders on juvenile brown boobies Sula leucogaster, which had been hand-fed beginning a few days after hatching, to examine how social interactions between tagged juveniles and other birds affected their flight and foraging behaviour. Juveniles flew longer with congeners, especially with adult birds, than solitarily. In addition, approximately 40% of foraging occurred close to aggregations of congeners and other species. Young seabirds voluntarily followed other birds, which may directly enhance their foraging success and improve foraging and flying skills during their developmental stage, or both.     

A novel Ca2+-signal transduction inhibitor,kujigamberol C,isolated from Kuji amber

ABSTRACT

A novel labdane type diterpenoid, 15-nor-8-labden-13-ol, named kujigamberol C, was isolated from Kuji amber using a modified isolation method to increase the yield of biologically active compounds. The structure was determined using HREIMS, 1D and 2D NMR. Kujigamberol C showed growth-restoring activity against mutant yeast via Ca²⁺-signal transduction.