A Comparison of the Efficacy of Nuclear Polyhedrosis and Granulosis Viruses in Spray and Bait Formulations for the Control of Agrotis segetum (Lepidoptera: Noctuidae) in Maize

Agrotis segetum nuclear polyhedrosis virus (AsNPV) and granulosis virus (AsGV), propagated in laboratory cultures of A. segetum in England and A. ipsilon in Spain, respectively, were applied to plots of maize plants at the one‐ to four‐leaf stage of growth. Plots were arranged in a 6 x 6 Latin square design and infested with second‐instar A. segetum larvae (the common cutworm). Each virus was applied in separate treatments by two application methods; as an aqueous spray containing 0.1% Agral as a wetting agent, and as a bran bait. The NPV was applied at a rate of 4 X 10¹² polyhedra/ha, and the GV at 4 X 10¹³ granules/ha. Soil and plants were sampled for larvae on three occasions following virus treatment: 24 h, 4 days and 11 days. The larvae were reared on diet in the laboratory, until death or pupation, to examine the rate and level of viral infection. Infection data showed 87.5% and 91% NPV infection and 12.5% and 55% GV infection in spray and bait treatments, respectively, in larvae sampled 24 h after treatment. In larvae sampled 4 days after treatment, the results were 78% and 100% NPV infection, and 13% and 6% GV infection. A total of only six larvae were retrieved on day 11. In both treatments larvae infected with AsNPV died significantly more rapidly and at an earlier instar than those infected with AsGV, indicating that AsNPV appears to have better potential as a control agent for A. segetum.     

Cytogenetic effects of pesticides. III. Induction of micronuclei in mouse bone marrow by the insecticides cypermethrin and rotenone

The production of micronuclei in mouse bone marrow by the pyrethroid insecticide, cypermethrin and the botanical insecticide, rotenone was examined. Three routes of administration were used for the insecticides: intraperitoneal, oral and dermal. The different routes of treatment with cypermethrin and rotenone caused toxicity of marrow as indicated by a significant increase in the percentage of polychromatic erythrocytes (PEs) over that of the control. Cypermethrin showed mutagenic potential as evidenced by a positive response in the micronucleus assay. Oral administration of the insecticide at a dietary level of 900 ppm for 7 and 14 consecutive days as well as double and multiple (total 4) dermal treatments (360 mg/kg body wt.) induced a statistically significant increase in the frequency of PEs with micronuclei. The conducted intraperitoneal (i.p.) treatments with cypermethrin: single injection at 60 and 180 mg/kg body wt., double and multiple injections (total 3) at 60 mg/kg body wt. did not affect the percentage of PEs with micronuclei. The different treatments with rotenone: single, double and multiple (i.p.) injections (total 3) at 2 and 3 mg/kg body wt., oral administration for 14 consecutive days at dietary level of 225 ppm and multiple dermal treatments (total 4) with 135 mg/kg body wt. showed no effect on the frequency of micronuclei in PEs.     

The phagosome containing Legionella pneumophila within the protozoan Hartmannella vermiformis is surrounded by the rough endoplasmic reticulum.

Legionella pneumophila is an intracellular parasite of protozoa and human phagocytes. To examine adaptation of this bacterium to parasitize protozoa, the sequence of events of the intracellular infection of the amoeba Hartmannella vermiformis was examined. The previously described uptake phenomenon of coiling phagocytosis by human monocytes was not detected. A 1 h postinfection with wild-type strain AA100, mitochondria were observed within the vicinity of the phagosome. At 2.5 h postinfection, numerous vesicles surrounded the phagosomes and mitochondria were in close proximity to the phagosome. At 5 h postinfection, the bacterium was surrounded by a ribosome-studded multilayer membrane. Bacterial multiplication was evident by 8 h postinfection, and the phagosome was surrounded by a ribosome-studded multilayer membrane until 15 h postinfection. The recruitment of organelles and formation of the ribosome-studded phagosome was defective in an isogenic attenuated mutant of L. pneumophila (strain AA101A) that failed to replicate within amoebae. At 20 h postinfection with wild-type strain AA100, numerous bacteria were present in the phagosome and ribosome were not detected around the phagosome. These data showed that, at the ultrastructural level, the intracellular infection of protozoa by L. pneumophila is highly similar to that of infection of macrophages. Immunocytochemical studies provided evidence that at 5 h postinfection the phagosome containing L. pneumophila acquired an abundant amount of the endoplasmic reticulum-specific protein (BiP). Similar to phagosomes containing heat-killed wild-type L. pneumophila, the BiP protein was not detectable in phagosomes containing the mutant strain AA101A. In addition to the absence of ribosomes and mitochondria, the BiP protein was not detected in the phagosomes at 20 h postinfection with wild-type L. pneumophila. The data indicated that the ability of L. pneumophila to establish the intracellular infection of amoebae is dependent on its capacity to reside and multiply within a phagosome surrounded by the rough endoplasmic reticulum. This compartment may constitute a rich source of nutrients for the bacteria and is probably recognized as cellular compartment. The remarkable similarity of the intracellular infections of macrophages and protozoa by L. pneumophila strongly supports the hypothesis that adaptation of the bacterium to the intracellular environment of protozoa may be the mechanism for its ability to adapt to the intracellular environment of human alveolar macrophages and causes pneumonia.     

Growth kinetics of Lactobacillus acidophilus under ohmic heating

Lactobacillus acidophilus OSU133 was inoculated into MRS broth in a fermenter vessel and incubated at 30, 35, or 45 degrees C with agitation. Incubation temperatures were attained by conventional or ohmic heating. An electrical current at low (15 V) or high (40 V) voltage was used to heat the culture directly during fermentations under ohmic heating. The growth parameters (lag period, minimum generation time, and maximum growth) and changes in pH were determined during fermentation. Metabolic activities (consumption of glucose and production of lactic acid and bacteriocin) were determined during fermentation at 35 degrees C under both heating methods. Lag period for L. acidophilus was affected appreciably by the method of heating, but the magnitude of these changes depended on the fermentation temperature. When fermentation was done at 30 degrees C, lag period decreased by 94% under low-voltage ohmic, compared with conventional, heating methods. Ohmic heating did not change the generation time significantly and caused slight, but significant (p < 0.01) decrease in maximum growth. Therefore, the electric current enhances the early stages, but it inhibits the late stages of growth. Ohmic, compared with conventional, heating resulted in higher final pH and lower bacteriocin activity in the fermented medium. However, ohmic heating at 35 degrees C had minimal effect on glucose utilization and lactic acid production by L. acidophilus. Results show that measurement of the electric current when ohmic heating is done at a constant voltage may be used in monitoring such fermentations. In conclusion, ohmic heating is potentially useful in certain applications related to fermented foods. (c) 1996 John Wiley & Sons, Inc.     

Lipid Production,Oxidative Status,Antioxidant Enzymes and Photosynthetic Efficiency of <i>Coccomyxa chodatii</i> SAG 216-2 in Response to Calcium Oxide Nanoparticles

The extensive use of nanoparticles (NPs) in diverse applications causes their localization to aquatic habitats, affecting the metabolic products of primary producers in aquatic ecosystems, such as algae. Synthesized calcium oxide nanoparticles (CaO NPs) are of the scarcely studied NPs. Thus, the current work proposed that the exposure to CaO NPs may instigate metabolic pathway to be higher than that of normally growing algae, and positively stimulate algal biomass. In this respect, this research was undertaken to study the exposure effect of CaO NPs (0, 20, 40, 60, 80, and 100 µg mL⁻¹ ) on the growth, photosynthesis, respiration, oxidative stress, antioxidants, and lipid production of the microalga Coccomyxa chodatii SAG 216-2. The results showed that the algal growth concomitant with chlorophyll content, photosynthesis, and calcium content increased in response to CaO NPs. The contents of biomolecules such as proteins, amino acids, and carbohydrates were also promoted by CaO NPs with variant degrees. Furthermore, lipid production was enhanced by the applied nanoparticles. CaO NPs induced the accumulation of hydrogen peroxide, while lipid peroxidation was reduced, revealing no oxidative behavior of the applied nanoparticles on alga. Also, CaO NPs have a triggering effect on the antioxidant enzymes such as superoxide dismutase, catalase, ascorbate peroxidase, and guaiacol peroxidase. The results recommended the importance of the level of 60 µg mL⁻¹ CaO NPs on lipid production (with increasing percentage of 65% compared to control) and the highest dry matter acquisition of C. chodatii. This study recommended the feasibility of an integrated treatment strategy of CaO NPs in augmenting biomass, metabolic up-regulations, and lipid accumulation in C. chodatii.     

Low genetic diversity and population connectivity fuel vulnerability to climate change for the Tertiary relict pine Pinus bungeana

Endemic species are important components of regional biodiversity and hold the key to understanding local adaptation and evolutionary processes that shape species distributions. This study investigated the biogeographic history of a relict conifer Pinus bungeana Zucc. ex Endl. confined to central China. We examined genetic diversity in P. bungeana using genotyping-by-sequencing and chloroplast and mitochondrial DNA markers. We performed spatial and temporal inference of recent genetic and demographic changes, and dissected the impacts of geography and environmental gradients on population differentiation. We then projected P. bungeana's risk of decline under future climates. We found extremely low nucleotide diversity (average π 0.0014), and strong population structure (global F_ST 0.234) even at regional scales, reflecting long-term isolation in small populations. The species experienced severe bottlenecks in the early Pliocene and continued to decline in the Pleistocene in the western distribution, whereas the east expanded recently. Local adaptation played a small (8%) but significant role in population diversity. Low genetic diversity in fragmented populations makes the species highly vulnerable to climate change, particularly in marginal and relict populations. We suggest that conservation efforts should focus on enhancing gene pool and population growth through assisted migration within each genetic cluster to reduce the risk of further genetic drift and extinction.     

Systematics of Mukdenia and Oresitrophe (Saxifragaceae): Insights from genome skimming data

Oresitrophe and Mukdenia (Saxifragaceae) are epilithic sister genera used in traditional Chinese medicine. The taxonomy of Mukdenia, especially of M. acanthifolia, has been controversial. To address this, we produced plastid and mitochondrial data using genome skimming for Mukdenia acanthifolia and Mukdenia rossii, including three individuals of each species. We assembled complete plastomes, mitochondrial CDS and nuclear ribosomal ETS/ITS sequences using these data. Comparative analysis shows that the plastomes of Mukdenia and Oresitrophe are relatively conservative in terms of genome size, structure, gene content, RNA editing sites and codon usage. Five plastid regions that represent hotspots of change (trnH-psbA, psbC-trnS, trnM-atpE, petA-psbJ and ccsA-ndhD) are identified within Mukdenia, and six regions (trnH-psbA, petN-psbM, trnM-atpE, rps16-trnQ, ycf1 and ndhF) contain a higher number of species-specific parsimony-informative sites that may serve as potential DNA barcodes for species identification. To infer phylogenetic relationships between Mukdenia and Oresitrophe, we combined our data with published data based on three different datasets. The monophyly of each species (Oresitrophe rupifraga, M. acanthifolia and M. rossii) and the inferred topology ((M. rossii, M. acanthifolia), O. rupifraga) are well supported in trees reconstructed using the complete plastome sequences, but M. acanthifolia and M. rossii did not form a separate clade in the trees based on ETS + ITS data, while the mitochondrial CDS trees are not well-resolved. We found low recovery of genes in the Angiosperms353 target enrichment panel from our unenriched genome skimming data. Hybridization or incomplete lineage sorting may be the cause of discordance between trees reconstructed from organellar and nuclear data. Considering its morphological distinctiveness and our molecular phylogenetic results, we strongly recommend that M. acanthifolia be treated as a distinct species.     

First chemical synthesis of a scorpion alpha-toxin affecting sodium channels: the Aah I toxin of Androctonus australis hector.

Aah I is a 63-residue alpha-toxin isolated from the venom of the Buthidae scorpion Androctonus australis hector, which is considered to be the most dangerous species. We report here the first chemical synthesis of Aah I by the solid-phase method, using a Fmoc strategy. The synthetic toxin I (sAah I) was renatured in DMSO-Tris buffer, purified and subjected to thorough analysis and comparison with the natural toxin. The sAah I showed physico-chemical (CD spectrum, molecular mass, HPLC elution), biochemical (amino-acid composition, sequence), immunochemical and pharmacological properties similar to those of the natural toxin. The synthetic toxin was recognized by a conformation-dependent monoclonal anti-Aah I antibody, with an IC50 value close to that for the natural toxin. Following intracerebroventricular injection, the synthetic and the natural toxins were similarly lethal to mice. In voltage-clamp experiments, Na(v) 1.2 sodium channel inactivation was inhibited by the application of sAah I or of the natural toxin in a similar way. This work describes a simple protocol for the chemical synthesis of a scorpion alpha-toxin, making it possible to produce structural analogues in time.