The effects of various aphids as larval prey on the development ofMetasyrphus corollae [Dipt.: Syrphidae]

The suitability of thirteen aphid species for the polyphagous larvae ofMetasyrphus corollae (Fabr.) was investigated in laboratory tests. The length of larval and pupal development, weight of puparia, mortality during larval and pupal stages were compared. Cannibalism was not observed in the larvae reared in groups on suitable food.Aphis sambuci Linneaus was not a suitable prey for the larvae.Cavariella theobaldi (Gillette Bragg) collected fromPastinaca sativa L. was toxic to larvae ofM. corollae, although it was possible to rear the larvae onAphis fabae Scopoli orAnuraphis subterranea (Walker) from the same host plant.     

Insecticidal activity ofBacillus thuringiensis strains against the egyptian cotton leaf wormSpodoptera littoralis [Lep.: Nocutidae]

Among more than 50 isolates ofBacillus thuringiensis Berliner (B.t.) tested, 7 incited 100% mortality when 2nd instar larvae ofSpodoptera littoralis Boisduval were fed on alfalfa leaves dipped in a spore-crystal suspension of 10⁸ colony forming units/ml. Among those isolates,B.t. 24 demonstrated the highest activity. Larvae of instars 1 and 2 were the most susceptible toB.t. Susceptibility decreased with larval development. However, larvae of all instars were killed by isolateB.t. 24. Larvae that survived after feeding withB.t. 24 were retarded and fed less. Their weight relative to the controls was lower as the spore concentration on the leaves on which they fed was higher. Survival of the spores in the field dropped drastically to 2% after 4 days. Insecticidal activity of the sprayed suspension on those leaves, however, remained significant.B.t. 24 was also effective against larvae on cotton plants in the greenhouse and in a preliminary field experiment. Numbers of colony forming units recovered from leaves dipped in suspension of various spore concentrations showed significant correlation with the initial concentrations as did sprayed leaves. However, colony forming units recovered from sprayed leaves were 5–7.5 fold lower than from dipped leaves. Dipped cotton leaves showed 3.1×10^?5 ml attached to 1 mm² leaf surface whereas sprayed ones had 6×10^?6 ml. Those data are important for the determination of spore concentrations in suspensions required for spraying. The isolateB.t. 24 was serotyped byH. de Barjac as H-6B. thuringiensis entomocidus.     

Efficacy of two nuclear polyhedrosis viruses againstOstrinia nubilalis [Lep.: Pyralidae] in the laboratory and field

Nuclear polyhedrosis viruses isolated from the alfalfa looper,Autographa californica (Speyer) (AcMNPV), and a mint looper,Rachiplusia ou (Guenée) (RoMNPV), were assayed against the European corn borer,Ostrinia nubilalis Hübner), and applied to field corn for suppression of this insect. Fourteen days post-treatment, LC₅₀ values were 46.50 abd 0.95×10⁵ PIB/ml diet for AcMNPV and RoMNPV, respectively. Both viruses caused significant reductions in number of larvae per plant and in plant damage when the material was applied with a backpack sprayer. Data indicate that RoMNPV kills in less time than AcMNPV. When the viruses were applied with a commercial highboy applicator, the centimeters of damage to cornstalks was reduced by 65% with RoMNPV during the 1st generation and by 32.9% in the 2nd generation.     

Characterization of uptake and release processes ford- andl-aspartate in primary cultures of astrocytes and cerebellar granule cells

The uptake ofl-andd-aspartate was studied in astrocytes cultured from prefrontal cortex and in granule cells cultured from cerebellum. A high affinity uptake system forl- andd-aspartate was found in both cell types, and the two stereoisomers exhibited essentially the sameK _m - andV _max -values in bouth astrocytes (l-aspartate:K _m 77 μM;V _max 11.8 nmol×min^?1×mg^?1;d-aspartate:K _m 83 μM;V _max 14.0 nmol×min^?1×mg^?1) and granule cells (l-aspartate:K _m 32 μM;V _max 2.8 nmol ×min^?1×mg^?1;d-aspartate:K _m 26 μM;V _max 3.0 nmol×min^?1×mg^?1). To investigate whetherl-glutamate,l-aspartate andd-aspartate use the same uptake system a detailed kenetic analysis was performed. The uptake kinetics of each one of the three amino acids was studied in the presence of the two other amino acids, and no essential differences between the uptake characteristics of the amino acids were found. In addition to the uptake studies the release ofD-aspartate from cerebellar granule cells was investigated and compared withl-glutamate release. A Ca²⁺-dependent, K⁺-induced release was found for both amino acids.     

Mechanisms of cell volume regulation in the proximal segment of the Malpighian tubule of Rhodnius neglectus

The cell volume regulation of the lower segment cells of the Malpighian tubule of Rhodnius neglectus in anisosmotic media was evaluated by using videooptic techniques. When the medium osmolality was increased with addition of 100 mm mannitol the cells shrank to a minimum of 16.84±2.62% and subsequently swelled towards their initial volume undergoing a typical regulatory volume increase (RVI). Replacement of either K⁺ or Cl^? or HCO ₃ ^? by Na⁺, gluconate and phosphate, respectively, abolished the RVI response. Furthermore, the substitution of Na⁺ by tetramethylammonium (TMA⁺) in isosmotic conditions led to cellular swelling and death. Addition of either amiloride 10^?4 m, anthracene-9-COOH 5×10^?4 m, furosemide 5×10^?4 m or ethacrynic acid 5×10^?5 m, also abolished RVI. On the other hand, addition of either Ba²⁺ 10^?3 m, SITS 5× 10^?4 m, ouabain 10^?3 m or vanadate 10^?3 m, did not change the RVI response. When the tubules were incubated in hyperosmotic media with EGTA 2 mm or verapamil 10^?6 m, the RVI response was abolished. In contrast, a decrease of NaCl concentration from 129 to 79 mm induced a cell swelling to a maximum of 33.11+1.73%, but the cells maintained swollen, only partially regulating their volume. These results show that the proximal cells of Malpighian tubule of R. neglectus are able to regulate their volume in hyperosmotic but only partially regulating in hyposmotic solutions. The mechanisms in RVI involve Na⁺, K⁺, Cl^?, Ca²⁺ and HCO ₃ ^? transport pathways and a ouabain-insensitive ATPase stimulated by Na⁺. This work was supported by grants from the Fundação de Amparo à Pesquisa do Estado de São Paulo—FAPESP; Conselho Nacional de Desenvolvimento Científico e Tecnológico—CNPq e Financiadora de Projetos e Pesquisas-FINEP.     

Parasites of rice stemborers in Sarawak (Malaysian Borneo)

Observations on parasites were made during a study of the following rice stem-borers in Sarawak (Malaysian Borneo):Tryporyza incertulas (Walker),T. innotata (Walker),Chilo suppressalis (Walker)C. auricilia (Dudgeon), andSeamia inferens (Walker). Egg-parasitism was often high, but that of the larval and pupal stages generally very low. Between 40–80% of theTryporyza eggs were parasitised byTelenomus rowani (Gahan), while 30–50% were attacked byTetrastichus schoenobii Ferrière. About 40–90% of the eggs ofChilo were parasitised byTrichogramma? japonicum Ashmead and 5–26% byTelenomus dignus (Gahan). Only 0.4–3% of theTryporyza larvae were parasitised by a Braconid,Rhaconotus schoenobivorus (Rohwer), whileBracon chinensis Szepligeti attacked 0.2–0.7% of the larvae ofC. suppressalis. Parasitism ofSesamia larvae byApanteles flavipes Cameron was equally low, never exceeding 2%. Pupal parasitism was somewhat higher.Tetrastichus israeli (Mani & Kurian) attacked 8% and 18% of the pupae ofC. suppressalis andS. inferens, respectively, while the Ichneumonid,Xanthopimpla stemmator (Thunberg) attacked up to 3% of the pupae of the former species. The immature stages of some of these parasites are described.     

Biotransformation of l-ornithine from l-arginine using whole-cell recombinant arginase

A recombinant arginase was generated for a whole-cell biotransformation system to convert l-arginine to l-ornithine in Escherichia coli. The gene ARG1 coding arginase from Bos taurus liver was synthesized and expressed in E. coli BL21 (DE3) via pETDuet-1. The recombinant arginase was used to catalyze l-arginine to l-ornithine and urea. The reaction was optimal at pH 9.5 and 37 °C. Manganese (10^?5 M) and Emulsifier OP-10 [0.033 % (v/v)] could promote arginase activity. In a scale up study, l-arginine conversion rate reached 98 % with a final concentration of 111.52 g l-ornithine/l.     

Zoophthora phytonomi andConidiobolus osmodes [Zygomycetes:Entomophthoraceae], two pathogens ofHypera species [Col.: Curculionidae] coincidental in time and place

Two entomophthoraceous species, found at different localities in Israel, caused epizootics onHypera variabilis Herbst. larvae during spring of 1976 and 1977.Zoophthora phytonomi (Arthur) Batko, emend.Ben-Ze’ev & Kenneth (syn.Entomophthora phytonomi Arthur) produced in the field only conidia, whereasConidiobolus osmodes Drechsler formed only dark, rough-walled resting spores that had been erroneously thought in the past to belong toZ. phytonomi. In culture,Z. phytonomi, isolated from conidia, produced subhyaline, smooth resting spores, whereasC. osmodes from resting spores produced rotund conidia, which proved pathogenic toH. variabilis larvae and adult houseflies. All species connected by different authors withZ. phytonomi are discussed, includingE. elateridiphaga, transferred here toZoophthora.     

Uptake of amino acids by actidione-treated yeast cells

The active uptake ofl-aspartic acid, glycine andl-lysine by actidione-treated cells ofSaccharomyces cerevisiae was found to be inhibited by anaerobic conditions in the absence of a source of energy, only facilitated diffusion persisting. Similarly, metabolic inhibitors (iodoacetamide, sodium fluoride and potassium sorbate) inhibited the uptake very substantially. 2,4-Dinitrophenol and sodium azide appeared to inhibit the movement of the transport carrier itself, while uranyl ions showed a complex interaction pattern, ranging from inhibition at concentrations of 10^?6–10^?4 m, to stimulation at concentrations of 3×10^?4–10^?3 m, to pronounced inhibition at higher concentrations. The uptake was pH-dependent with optima forl-aspartic acid near pH 4, for glycine near pH 5, forl-lysine near pH 6.5.     

Hybriden vonPyrus spinosa

Three hybrids are described whose common parent wasPyrus spinosa Forsk.: 1.Pyrus × bardoënsis Dostálek (P.elaeagrifolia Pall. ×P. spinosa Forsk.).—2.Pyrus × velenovskyi Dostálek (P.pyraster Burgsd. ×P. spinosa Forsk.).—3.Pyrus × jordanovii Dostálek (P. communis L. ×P. spinosa,Forsk.). Notes are given about five other hybrids whose existence has not been conclusively confirmed or which are less important.     

Two hybrids ofThymus hyemalis Lange (Labiatae) from Southeastern Spain

Two new hybrids in the genusThymus, Th. × indalicus Blanca et al., nothosp. nov. [=Th. baeticus Boiss. exLacaita ×Th. hyemalis Lange subsp.hyemalis] andTh. × enicensis Blanca et al., nothosp. nov. [=Th. hyemalis Lange subsp.hyemalis × Th. zygis Loefl. ex L. subsp.gracilis (Boiss.)R. Morales] are described. Until now no hybrids ofTh. hyemalis have been described, due to its early period of flowering and because it hybridizes with closely related species, making rather difficult the detection of such hybrids.     

Metabolic engineering of Escherichia coli for biosynthesis of d-galactonate

d-galactose is an attractive substrate for bioconversion. Herein, Escherichia coli was metabolically engineered to convert d-galactose into d-galactonate, a valuable compound in the polymer and cosmetic industries. d-galactonate productions by engineered E. coli strains were observed in shake flask cultivations containing 2 g L^?1 d-galactose. Engineered E. coli expressing gld coding for galactose dehydrogenase from Pseudomonas syringae was able to produce 0.17 g L^?1 d-galactonate. Inherent metabolic pathways for assimilating both d-galactose and d-galactonate were blocked to enhance the production of d-galactonate. This approach finally led to a 7.3-fold increase with d-galactonate concentration of 1.24 g L^?1 and yield of 62.0 %. Batch fermentation in 20 g L^?1 d-galactose of E. coli ?galK?dgoK mutant expressing the gld resulted in 17.6 g L^?1 of d-galactonate accumulation and highest yield of 88.1 %. Metabolic engineering strategy developed in this study could be useful for industrial production of d-galactonate.     

Parasitism ofPhthorimaea operculella [Lep.: Gelechiidae] larvae in Queensland

Parasitism ofPhthorimaea operculella (Zeller) larvae on potato foliage was examined intensively in the Lockyer Valley, south-eastern Queensland from 1975–78 and extensively from other hosts and areas of Queensland. The % parasitism in the Lockyer Valley exceeded 50% in 29 of the 36 collections. The parasite species were dominated by the introducedCopidosoma desantisi Annecke & Mynhardt (Encyrtidae) andOrgilus lepidus Muesebeck (Braconidae) which together accounted for 92.6% of parasite numbers recorded. In more northern areas of Queensland, the dominant parasite species found was the introducedApanteles subandinus Blanchard (Braconidae). Other hymenopterous parasites found wereMicrochelonus curvimaculatus Cameron (Braconidae), Elasmus funereus Riek (Elasmidae) andTemelucha minuta (Morley) (Ichneumonidae).     

Evaluation of the E. coli d-serine ammonia lyase gene (Ec. dsdA) for use as a selectable marker in maize transformation

In this study, the d-serine ammonia lyase (dsdA) gene from Escherichia coli was evaluated as a selectable marker for maize transformation. Plants are incapable of utilizing the D-form of most amino acids, and d-serine has recently been demonstrated to be phytoinhibitory to plant growth. d-Serine ammonia lyase detoxifies d-serine via a substrate-specific reaction to pyruvate, ammonia, and water. d-Serine inhibits germination of isolated maize immature embryos and growth of embryogenic callus from wild-type plants at concentrations about approx. 2?C15 mM. Transgenic plants were recovered in the presence of d-serine in tissue culture media with dsdA as the selection marker at efficiencies comparable to using a mutated acetohydroxy acid synthase selection marker gene and selection in the presence of imidazolinone herbicides. Immature embryos infected with an Agrobacterium strain containing an acetohydroxy acid synthase gene construct without dsdA did not yield any transgenic events on the selection medium with 10 mM d-serine, indicating that d-serine provided selection tight enough to prevent escapes. Molecular analysis confirmed the integration of the dsdA gene into the genome of the transgenic plants. No adverse phenotypes were observed in the greenhouse, and expression of the dsdA marker had no affect on agronomic characteristics or grain yield in multi-location field trials. Seed compositional analysis demonstrated no significant differences in the contents of seed protein, starch, fatty acids, fiber, phytic acid, and free amino acids between transgenic and non-transgenic control plants. These data indicate that the dsdA gene is properly expressed in maize and the d-serine ammonia lyase (DSDA) enzyme functions appropriately to metabolize d-serine during in vitro selection. Preliminary safety assessments indicated that no adverse affects would be expected if humans were exposed to the DSDA protein in the diet from an allergenicity or toxicity perspective. The dsdA gene in combination with phytoinhibitory levels of d-serine represents a new and effective selectable marker system for maize transformation.     

The parasitoid complex of three noctuids [Lep.] in a northern Florida cropping system: Seasonal occurrence,parasitization, alternate hosts,and influence of host-habitat

Parasitoids of the cabbage looper,Trichoplusia ni (Hübner), the soybean looper,Pseudoplusia includens (Walker), and the tobacco budworm,Heliothis virescens (F.) were characterized in a 3.2-ha model of a north Florida (U.S.A.) cropping system (including tobacco (Nicotiana tabacum L.), soybeans (Glycine max (L.)Merr. and 18 other crops) not treated with chemical pesticides. The study was for a 2 yr-period; a minimum of three 0.0004-ha sections of row, or 0.0001-ha sections in broadcast or drilled crops were sampled weekly. In addition, sweeps with a net and some other sampling techniques were used in some crops.Litomastix truncatella (Dalman),Meteorus autographae Muesebeck, andVoria ruralis Fallen were the most important larval parasitoids recovered from cabbage loopers;Trichogramma spp. were by far the major egg parasitoid. Parasitization of eggs and larvae in crucifers (Brassica oleracea L.) ranged from 0 to 55% and 0 to 100%, respectively, and was generally highest during the spring and fall. Parasitization of cabbage looper immatures was highest in tomatoes (Lycopersicon esculentum Mill.). Parasitism by the parasitoid complex for the soybean looper larvae was high but eggs in soybeans were seldomly attacked by parasitoids. Tobacco budworm eggs were rarely parasitized in tobacco but were frequently parasitized in tomatoes and okra (Abelmoschus esculentus (L.)Medik). Parasitization of tobacco budworm larvae in tobacco was usually over 50% and was mostly byCardiochiles nigriceps Viereck; fewC. nigriceps were found from the other plants.     

Activation of the human red cell calcium ATPase by calcium pretreatment

Some kinetic parameters of the human red cell Ca²⁺-ATPase were studied on calmodulin-free membrane fragments following preincubation at 37°C. After 30 min treatment with EGTA(1 mm) plus dithioerythritol (1 mm), a V _max of about 0.4 μmol P_i/mg × hr and a K _s of 0.3 μm Ca²⁺ were found. When Mg²⁺ (10 mm) or Ca²⁺(10 μm) were also added during preincubation, V _maxbut not Kwas altered. Ca²⁺ was more effective than Mg²⁺, thus increasing V _max to about 1.3 μmol P_i/mg × hr. The presence of both Ca²⁺ and Mg²⁺ during pretreatment decreasedKto 0.15 μm, while having no apparent effect on V _max. Conversely, addition of ATP (2 mm) with either Ca²⁺ or Ca²⁺ plus Mg²⁺increased V_max without affecting K. Preincubation with Ca²⁺ for periods longer than 30 min further increased V_maxand reduced Kto levels as low as found with calmodulin treatment. The Ca²⁺ activation was not prevented by adding proteinase inhibitors (iodoacetamide, 10 mm; leupeptin, 200 μm; pepstatinA, 100 μm; phenylmethanesulfonyl fluoride, 100 μm). The electrophoretic pattern of membranes preincubated with or without Mg²⁺, Ca²⁺ or Ca²⁺ plus Mg²⁺ did not differ significantly from each other. Moreover, immunodetection of Ca²⁺-ATPase by means of polyclonal antibodiesrevealed no mobility change after the various treatments. The above stimulation was not altered by neomycin (200 μm), washing with EGTA (5 mm) or by both incubating and washing with delipidized serum albumin (1 mg/ml), or omitting dithioerythritol from the preincubation medium. On the other hand, the activation elicited by Ca²⁺ plus ATP in the presence of Mg²⁺ was reduced 25–30% by acridine orange (100 μm), compound 48/80 (100 μm) or leupeptin (200 μm) but not by dithio-bis-nitrobenzoic acid (1 mm). The fluorescence depolarization of 1,6-diphenyl-and l-(4-trimethylammonium phenyl)-6-phenyl 1,3,5-hexatriene incorporated into membrane fragments was not affected after preincubating under the different conditions. The results show that proteolysis, fatty acid production, an increased phospholipid metabolism or alteration of membrane fluidity are not involved in the Ca²⁺ effect. Ca²⁺ preincubation may stimulate the Ca²⁺-ATPase activity by stabilizing or promoting the E₁ conformation.     

Notes on the genusOenothera subsect.Oenothera (Onagraceae) in the Czech Republic

Up-to-date results of taxonomic and phytogeographic studies ofOenothera subsect.Oenothera in the eastern part of the Czech Republic (Moravia and Silesia) are presented. A new hybridogenous species,Oe. moravica Jehlík etRostański (=Oe. fallax × Oe. victorini), is described from S Moravia. Several taxa and hybrids are reported for the first time for the Czech Republic:Oe. victorini Gates etCatcheside (=Oe. rostanskii Jehlík),Oe. × wienii Renner exRostański,Oe. acutifolia × Oe. victorini. Other taxa are recorded from the eastern part of the Czech Republic for the first time:Oe. acutifolia Rostański,Oe. hoelscheri Renner exRostański,Oe. parviflora L.,Oe. subterminalis Gates. The taxonomy ofOe. pycnocarpa Atkinson etBartlett is discussed. A survey of species and hybrids ofOenothera subsect.Oenothera in the Czech Republic is added.     

d-Tagatose production in the presence of borate by resting Lactococcus lactis cells harboring Bifidobacterium longum l-arabinose isomerase

Bifidobacterium longum NRRL B-41409 l-arabinose isomerase (l-AI) was overexpressed in Lactococcus lactis using a phosphate depletion inducible expression system. The resting L. lactis cells harboring the B. longum l-AI were used for production of d-tagatose from d-galactose in the presence of borate buffer. Multivariable analysis suggested that high pH, temperature and borate concentration favoured the conversion of d-galactose to d-tagatose. Almost quantitative conversion (92 %) was achieved at 20 g L^?1 substrate and at 37.5 °C after 5 days. The d-tagatose production rate of 185 g L^?1 day^?1 was obtained at 300 g L^?1 galactose, at 1.15 M borate, and at 41 °C during 10 days when the production medium was changed every 24 h. There was no significant loss in productivity during ten sequential 24 h batches. The initial d-tagatose production rate was 290 g L^?1 day^?1 under these conditions.     

K+-dependent 3H-d-glucose transport by hepatopancreatic brush border membrane vesicles of a marine shrimp

The effects of sodium, potassium, sugar inhibitors, and membrane potential on ³H-d-glucose uptake by hepatopancreatic epithelial brush border membrane vesicles (BBMV) of the Atlantic marine shrimp, Litopenaeus setiferus, were investigated. Brush border membrane vesicles were prepared using a MgCl₂/EGTA precipitation method and uptake experiments were conducted using a high speed filtration technique. ³H-d-Glucose uptake was stimulated by both sodium and potassium and these transport rates were almost doubled in the presence of an inside-negative-induced membrane potential. Kinetics of ³H-d-glucose influx were hyperbolic functions of both external Na⁺ or K⁺, and an induced membrane potential increased influx J _max and lowered K_m in both salts. ³H-d-Glucose influx versus [glucose] in both Na⁺ or K⁺ media also displayed Michaelis–Menten properties that were only slightly affected by induced membrane potential. Phloridzin was a poor inhibitor of 0.5 mM ³H-d-glucose influx, requiring at least 5 mM in NaCl and 10 mM in KCl to significantly reduce hexose transport. Several sugars (d-galactose, α-methyl-d-gluco-pyranoside, unlabeled d-glucose, d-fructose, and d-mannose) were used at 75 mM as potential inhibitors of 0.1 mM ³H-d-glucose influx. Only unlabeled d-glucose, d-fructose, and d-mannose significantly (p < 0.05) reduced labeled glucose transport. An additional experiment using increasing concentrations of d-mannose (0, 10, 25, 75, and 100 mM) showed this hexose to be an effective inhibitor of 0.1 mM ³H-d-glucose uptake at concentrations of 75 mM and higher. As a whole these results suggest that ³H-d-glucose transport by hepatopancreatic BBMV occurs by a carrier system that is able to use both Na⁺ and K⁺ as drivers, is enhanced by membrane potential, is relatively refractory to phloridzin, and is only inhibited by itself, d-fructose, and d-mannose. These properties are similar to those exhibited by the mammalian SLC5A9/SGLT4 transporter, suggesting that an invertebrate analogue of this protein may occur in shrimp.     

Improved method for the identification of the fluoride-resistant plasmacholinesterase genotypes

This investigation was prompted by the findings that (1) dibucaine-resistant homozygotes and heterozygotes for plasmacholinesterase also exhibit resistance to fluoride inhibition, (2) the differentiation of dibucaine-resistant from the fluoride-resistant genotypes is ambiguous with the method of Harris and Whittaker, (3) the plasmacholinesterase inhibition by Na fluoride (FN) is markedly influenced by the temperature. Therefore, we modified their method by increasing (1) the temperature of the reaction from 25C to 37C and (2) the concentration of Na fluoride from 5.0×10^?5 m to 2.5×10^?4 m. With this method, genetically normal individuals have a mean FN±sd=77.0±3.22 while atypical dibucaine-resistant homozygotes have a mean FN±sd=43.0±10.0 and atypical dibucaine-resistant heterozygotes 67.0±5.37. Since a linear correlation was observed between DN and FN by our new method, a fluoride number 2 sd lower than the predicted FN from the DN can distinctly identify the fluoride-resistant plasmacholinesterase genotype E ₁ ^f .