Translocation of 14C-glyphosate in johnsongrass (Sorghum halepense L. Pers.) as affected by growth stage and rhizome length

Studies were conducted in the green house on ¹⁴C-methyllabelled glyphosate translocation in johnsongrass as affected by rhizome length and growth stage. The amount of ¹⁴C measured by the liquid scintillation technique in the rhizomes (2-8%) increased with rhizome length (10, 20 or 30 cm) and tended to increase with growth stage (15-30 cm tall, 45-60 cm tall, or at seedhead), but the amount of ¹⁴C per g fresh rhizome weight was almost similar in all cases. Of the total amount applied per plant (0·2 μCi) about 1/3 or less remained on the treated leaf area, while another 1/3 was a absorbed into the treated leaves. Autoradiographs showed that the ¹⁴C label moved to all plant parts, basipetally and acropetally. Migration du glyphosate ¹⁴ C chez le sorgho d'Alep (Sorghum halepense L. Pers.) en relation avec le stage de croissance et la longueur du rhizome Des recherches ont été effectuées en serru sur la migration du glyphosate marqué au ¹⁴C sur le méthyle, chez le sorgho d'Alep, en relation avec la longueur du rhizome et le stade de croissance. La quantité de ¹⁴C mesurée par la technique de scintillation liquide dans les rhizomes (2 à 8%) s'est accrue avec la longueur du rhizome (10, 20 ou 30 cm) et elle a eu tendance à augmenter avec le stade de croissance (Hauteur 15-30 cm, hauteur 45-60 cm ou épiaison), mais la quantité de ¹⁴C par gramme de poids frais de rhizome est restée Presque identique dans tous les cas. Environ 1/3, ou moins, de la quantitéà la surface des feuilles traitées par plante (0,2 μCi), est restéà la surface des feuilles traitées cependant qu'un autre 1/3 a été absorbé dans less feuilles traitées Les autoradiographies ont montré que le ¹⁴C marqueur a migré dans toutes les parties de la plante, dans le sens basipète et dans le sens acropète. Translokation von ¹⁴C-Glyphosat in Johnsongras (Sorghum halepense L. Pers.) in Abhängigkeit vom Wachstumsstadium der Pflanzen und der Rhizomlänge Im Gewächshaus wurden Versuche über die Translokation von ¹⁴C-Glyphosat in Johnsongras (Sorghum halepense L. Pers.) in Abhängigkeit vom Wachstumsstadium der Pflanzen und der Rhizomlänge durchgeführt. An den Rhizomen stieg der Gehalt von ¹⁴C(2–8%), gemessen mit der Flüssig-Szintillationstechnik, mit zunehmender Rhizomlänge (10, 20 oder 30 cm) an und nahm tendenziell auch mit fortschreitendem Pflanzenwachstum zu (15–30 cm und 45–60 cm Sprosslänge oder nach dem Rispenschieben); jedoch blieb die Menge pro g Rhizomfrischgewicht beinahe konstant. Von der insgesamt ausgebrachten Menge pro Pflanze (0.2 μCi) blieben bis zu 1/3 auf der behandelten Blättern absorbiert wurde. Die Autoradiographie zeigte, dass der ¹⁴C markierte Teil in alle Pflanzenteile sowohl basipetal wie auch akropetal transportiert wurde.     

Melanin biosynthesis in Pyricularia oryzae: Site of tricyclazole inhibition and pathogenicity of melanin-deficient mutants

Tricyclazole (5-methyl-1,2,4-triazolo[3,4-b]benzothiazole) inhibits melanin synthesis in Pyricularia oryzae at concentrations less than 0.01 μg/ml. The primary site of inhibition in the biosynthetic pathway occurs between scytalone and vermelone. Accumulation of several metabolites derived from melanin precursors along branch pathways is associated with inhibition of melanin biosynthesis. At low tricyclazole concentrations (0.01–1 μg/ml), predominant accumulation of 2-hydroxyjuglone and 3,4-dihydro-3,4,8-trihydroxy-1-(2H)-naphthalenone (3,4,8-DTN) occurs as a result of the primary block between 1,3,8-trihydroxynaphthalene and vermelone. As the concentration of tricyclazole is increased from 1 to 10 μg/ml, flaviolin accumulation is markedly enhanced, whereas that of 3,4,8-DTN and 3,4-dihydro-4,8-dihydroxy-1-(2H)-naphthalenone is depressed, indicating possible secondary sites of inhibition in the main and branch pathways. Five melanin-deficient mutants of P. oryzae that phenotypically resemble the tricyclazole-treated wild-type strain were nonpathogenic or rarely infected two rice varieties. Three of the mutants studied were genetically defective in the melanin biosynthetic pathway at the site blocked by tricyclazole in the wild type. The wild-type strain converted both scytalone and vermelone to melanin; whereas the three mutants and the tricyclazole-treated wild type converted only vermelone to melanin. The data suggest a relationship between melanin biosynthesis and pathogenicity in P. oryzae.     

Comparative inhibition of the juvenile hormone esterases from Trichoplusia ni,Tenebrio molitor, and Musca domestica

Twenty-seven compounds were screened as potential inhibitors of juvenile hormone esterases. Of these compounds O-ethyl-S-phenyl phosphoramidothiolate provided the best inhibition for the cabbage looper, Trichoplusia ni (Hubner), and the yellow mealworm, Tenebrio molitor L., while the juvenile hormone esterases of the house fly, Musca domestica L., were best inhibited by a juvenoid carbamate (1-(m-phenoxy-N-ethyl carbamate)-3,7-dimethyl-7-methoxy-2E-octene). The inhibition patterns of T. ni and T. molitor are similar, while those of M. domestica are relatively different. Further studies on the juvenile hormone and α-napthyl acetate esterases of T. ni showed that they could be differentially inhibited. Diisopropyl phosphorofluoridate and an alkyl trifluoromethyl ketone selectively inhibit the hydrolysis of α-naphthyl acetate and juvenile hormone, respectively, while O-ethyl-S-phenyl phosporamidothiolate inhibits both enzymes. The juvenile hormone esterases of T. ni also appear to be unique enzymes that are selective for juvenile-hormone-like molecules. The in vivo inhibition of T. ni juvenile hormone esterases by O-ethyl-S-phenyl phosphoramidothiolate slows the in vivo hydrolysis of juvenile hormone and results in delayed pupation and malformed larvae that resemble larval-pupal intermediates. Thus, the esterases involved in juvenile hormone metabolism appear to be important in juvenile hormone regulation.     

Physiological actions of dinoterb,a phenol derivative: 2. Effects on isolated plant mitochondria and chloroplasts

Dinoterb, a contact herbicide, affects respiration and photosynthesis of mitochondria and chloroplasts. On mitochondria, at low concentrations, it acts as an uncoupler of oxidative phosphorylation; at higher concentrations, it inhibits the electron transport chains, probably before cytochrome c. On chloroplasts, dinoterb has a stimulatory effect on oxygen uptake in the reduced dichlorophenol-indophenol→methyl viologen couple; however, it is also an inhibitor of the Hill reaction and its site of inhibition is located before plastoquinone, near photosystem II.     

The influence of temperature and photoperiod on growth and development of Parthenium hysterophorus L.

Germination, growth and flowering were investigated in Parthenium hysterophoms (Asteraceae), a species introduced to Australia and at present occurring as a weed in central Queensland. Combinations of day/night temperature regimes from 15/4 to 36/31 and day length of 10, 13 and 16 h in controlled conditions were examined to find the effects of any environmental restraints to growth and development. Results showed that individuals are able to germinate, grow and flower over a wide range of temperatures and photoperiods and established plants can survive at least one mild frost of — 2. We conclude that the potential distribution of P. hyslerophorus in Australia is much wider than at present. Future distribution of the species may be limited seasonally by the inability of seed to germinate in soils of low water potential and by the inability of seedlings to establish and grow at low light intensities.     

Field experiments to investigate long-term effects of repeated applications of MCPA, tri-allate, simazine and linuron: II. Crop performance and residues 1969–78

In four field experiments begun in 1963, each of four herbicides was applied to plots planted wilh the same crop each year. The annual treatments were: MCPA at 17 kg/ha to barley (Hordeum sativa Jess) and wheat (Triticum aestivum L.) at growth stage 15. tri-allate at 17 kg/ha pre-emergcnce to barley and wheat, simazine at l7kg/ha pre-emergence to maize (Zea mays L.) and linuron in two applications of 084 kg/ha pre- and post-emergence to carrots (Daucus carota L.). MCPA did not affect growth or yield of either barley or wheat. In general tri-allate also did not aftect the crops although wheat yield was depressed in 1978, wheat 1000 grain weight was reduced in 1972 and barley germination percentage was increased in 1973. Simazine did not influence the height, yield or appearance of maize. Linuron normally produced no effect on carrot yield, density and size. However, in 2 years when the post-emergence application was late, density but not yield was lower than in control plots. There was no accumulation of residues of any of these compounds in the soil. Rates of loss were similar to those predicted on ihe basis of laboratory experiments. In a fifth experiment these herbicides were applied twice per year (3 times in the case of linuron) at double the rales above on each occasion to bare plots. These applications ceased in 1968 (1969 for MCPA) but residues were monitored until 1972 except in the case of MCPA. Disappearance rates were similar to those in the cropped plots and residues were largely confined to the top 10 cm. The plots treated with MCPA had developed an enhanced ability lo degrade il prior to 1968. This persisted for 5 years after the final application.     

Corynebacterium equi in cattle and pigs

Summary The cervical lymph nodes of pigs, the retropharyngeal and submandibular lymph nodes of cattle and faecal samples from both animal species were examined for the presence of Corynebacterium equi. The organism was recovered from 19 (35 per cent) of 54 porcine cervical lymph nodes and from 0 of 54 bovine retropharyngeal and submandibular lymph nodes. Fifteen (50 per cent) of 30 bovine faecal and 11 (35 per cent) of 31 porcine faecal samples yielded C. equi.     

Experimental infection of calves with two strains of bovine virus diarrhoea virus: certain immunological reactions

Certain immunological responses of 4-6 month old calves experimentally inoculated with either cytopathic or non-cytopathic bovine virus diarrhoea virus (BVDV) were compared with those of uninfected control calves. The tests used to demonstrate the immunological responses were the transformation of lymphocytes by PHA mitogen, the percentage of lymphocytes with surface immunoglobulin, and the antibody titres induced by an intravenous inoculation of killed Brucella abortus. There were no significant differences between the two groups of calves and therefore, the mild experimental disease produced by BVDV did not appear to affect adversely the immunological response.     

The use of immunochemically purified anti-brucella antibody in a direct fluorescent antibody test for Brucella abortus

Antibodies specific for Brucella abortus were purified from the serum of hyperimmunized sheep using immunochemical procedures. They were conjugated to fluorescein isothiocyanate and used in a fluorescent antibody (FA) test for B. abortus. The conjugate did not stain any heterologous bacterial or fungal species tested and background fluorescence associated with its use on smears and sections of abortion materials was particularly low. Of 239 cases of abortion examined fluorescent microscopy demonstrated B. abortus in all 12 cases in which the organism was isolated. A few areas of fluorescence typical of B. abortus were also seen in 3 cases from which the organism was not cultured. B. abortus was demonstrated in lymph nodes from 6 of 36 Brucella reactor cows by culture and 7 by the FA test. However, only very low numbers of B. abortus were isolated or seen and sampling errors would have been significant. Use of the FA test allows diagnosis of Brucellosis to be made in 2 hours, compared to 6 days by the usual cultural procedures.     

Precocene II metabolism: Comparative in vivo studies among several species of insects,and structure elucidation of two major metabolites

Several species of insects, exhibiting varying responsiveness to the juvenile hormone antagonist precocene II (6,7-dimethoxy-2,2-dimethylchromene), were challenged topically with a tritiated preparation of the title compound. Metabolism of [³H]precocene II was subsequently examined by withdrawing hemolymph samples from treated animals at appropriate time intervals and characterizing the extractable radiolabel chromatographically. Quantitative (or qualitative) differences observed between the respective metabolic profiles were found not correlative with specimen sensitivity to precocene. Production of two heretofore unreported metabolites, identified by spectral and chemical means as O-β-glucosides of 6- and 7-monodemethylated precocene II, was demonstrated in both sensitive and insensitive species. No evidence for the presence of a hemolymphborne, biologically effective “activated metabolite” produced in vivo by precocene-susceptible insects could be found. The latter finding may well argue for in situ bioactivation of precocene at the target tissue(s) by these sensitive insects.