In vitro bioassay of sheep gastrointestinal mucus for nematode paralysing activity mediated by substances with some properties characteristic of SRS-A

A bioassay is described for determining the inhibition of nematode larval migration from agar by substances exerting a paralysing action.In the assay, larval migration was completely inhibited by the anthelmintic levamisole (25 μg/ml) whereas biogenic amines, and prostaglandins E₁ and E₂ at 50 μg/ml, were without effect. Mucus from the gastrointestinal tract of sheep resistant to nematode infection inhibited larval migration by up to 93% whereas mucus from heavily infected sheep or sheep reared helminth free did not significantly inhibit larval migration. Mucus from sheep resistant to Trichostrongylus colubriformis inhibited the migration of larvae of other nematode species.The larval migration inhibitory (LMI) activity of mucus from resistant sheep was associated with components having some properties of slow reacting substance of anaphylaxis (SRS-A).Faecal samples from resistant sheep possessed significantly more LMI activity than faecal samples from heavily infected sheep or sheep reared helminth free. The level of LMI activity in the faeces of sheep undergoing challenge infection may be a useful indicator of the sheep's resistance status.The presence of the larval migration inhibitory activity in sheep mucus is discussed in relation to resistance to infection.     

Crassula helmsii: attempts at elimination using herbicides

The high resistance to control by herbicides of stands of the aggressively-invasive water plant Crassula helmsii (Australian swamp stone crop or New Zealand Pygmy Weed, also sold as Tillaea recurva) was shown during a series of tank and field trials aimed at:firstly, selecting the most appropriate UK-approved herbicide showed that diquat, either directly or in alginate form was effective on submerged plants particularly at low biomass, whereas for emergent stands, although glyphosate was initially selected as effective, diquat was subsequently recommended;secondly, the efficacy of the herbicides selected under a range of conditions of biomass, season of application and, particularly, field conditions showed that whilst low biomasses could be controlled and the plant could probably be eliminated, elevated or multiple applications would be necessary at the very high biomasses (up to 45 kg fresh weight per m²) achieved by this plant, unless the bulk of the biomass could be physically reduced prior to herbicide application; further trials were considered necessary to meet legal current constraints.     

Effects of different kinases and phosphatases on nuclear and cytoplasmic maturation of bovine oocytes

Phosphorylation is considered as a common post-translational modification implicated in the control of various key enzymes. In somatic and germinal cells, important regulators of the cell cycle are controlled by their phosphorylation status, and some act as kinases or phosphatases themselves. Bovine oocytes are blocked in the germinal vesicle (GV) stage until either an LH surge occurs or until oocytes are released from the inhibitory influence of the follicle. Meiotic resumption in vitro is therefore an excellent model for the study of phosphorylation events that occur in the G2/M transition, a control point of the cellular cycle. To better understand this transition, we have modulated, either directly or indirectly, kinases using known effectors (epidermal growth factor, EGF; isobutyl-methylxanthine-forskolin, Bx-Fk; 6-dimethylaminopurine, 6-DMAP) or phosphatases (okadaic acid, OA) or cycloheximide, which is known to inhibit maturation through protein synthesis suppression. With this procedure, influence on meiotic resumption and phosphoprotein patterns was verified. Both EGF and OA accelerated nuclear maturation after 9 hr of culture. Only 23% (n = 140) and 9% (n = 111) of oocytes were still at GV stage with EGF and OA, respectively, compared to 41% (n = 105) of control oocytes. The different treatments changed the protein patterns in oocytes. In cumulus cells, the patterns were especially modified by the OA treatment. Characteristic changes that occur in germ cells were also identified. Nuclear maturation was inhibited by modulators of kinase (6-DMAP, GV = 74%, n = 126; cAMP dependent protein kinase (PKA) stimulators, Bx-Fk, GV = 71%, n = 129) likewise, phosphoprotein patterns were affected, especially in oocytes. The cycloheximide treatment was able to maintain nearly all oocytes in GV after 9 hr of culture (GV = 92%, n = 131). This analysis allowed the identification of substrates for the different effectors used in this study and also helped in determining the levels of phosphorylation required for nuclear maturation. © 1995 wiley-Liss, Inc.     

Histopathology of chromoblastomycosis

Summary A study aimed at determining the histopathologic appearance of chromoblastomycotic lesions was undertaken. Biopsies from 26 patients with the disease were examined. It was found that 23 cases (88.46%) exhibited the organized mixed mycotic granuloma — OMMA —, a granuloma modified by the presence polymorphonuclear neutrophils — PMN's. An equal proportion of cases exhibited pseudoepitheliomatous hyperplasia, with the epithelium playing an important role in the transepidermic elimination of the fungus. Healing of the lesions took place by fibrosis which was observed in 21 (80.77%) patients; this type of reaction was more common in the deeper areas of the dermis.     

The depsipeptide technique applied to peptide segment condensation: scope and limitations.

A promising application of the depsipeptide technique has recently been proposed to provide ideal conditions for segment condensation, in that coupling of peptides bearing a C-terminal depsipeptide unit occurs without giving rise to epimerization at the activated amino acid. This is due to the low tendency of the activated depsipeptide units, in contrast to the corresponding peptide segments, to form optically labile oxazolones. In this work we demonstrate that coupling of depsipeptides via base-assisted activation using HBTU occurs not only without loss of configuration, but even much faster than the coupling of the corresponding all-amide segments. Nevertheless, when the coupling of long depsipeptide segments proceeds slowly, we uncovered the occurrence of beta-elimination at the activated depsipeptide unit, in an extent dependent on the presence of base in the system and on the type of the solvent. Beta-elimination was completely suppressed by using carbodiimide/HOBt activation in a non-polar solvent (DCM), and in more polar media it was limited by substituting TMP for DIEA during HBTU activation, or using particular solvent mixtures (such as DMSO/toluene) for activation via carbodiimide. Finally, we show the application of C-terminal pseudoprolines, in comparison with that of depsipeptide units, to segment coupling.     

Stoichiometric aerobic aminohydroxylation of ethylene mediated by dpms-platinum complexes (dmps = di(2-pyridyl)methanesulfonate)

Chloro di(2-pyridyl)methanesulfonate ethylene platinum(II) complex was converted to corresponding N-alkylplatina(II)azetidines by reacting the former with primary amines, MeNH₂ and tert-BuNH₂, to produce 2-ammonioethyl chloro platinum(II) species and their subsequent cyclization in the presence of NaOH in methanol. The N-alkylplatina(II)azetidines are oxidized under air or the atmosphere of pure O₂ to the corresponding N-alkylplatina(IV)azetidines in water or in methanol solution in the presence of one equivalent of a strong acid under ambient pressure at 22 °C. The resulting N-alkylplatina(IV)azetidines undergo C-O reductive elimination in acidic aqueous solutions to produce 2-(N-alkylamino)ethanols.     

An improved procedure for the synthesis of dehydroamino acids and dehydropeptides from the carbonate derivatives of serine and threonine using tetrabutylammonium fluoride

Dehydroamino acids are important precursors for the synthesis of a number of unnatural amino acids and are structural components in many biologically active peptide derivatives. However, efficient synthetic procedures for their production in large amounts and without side reactions are limited. We report here an improved procedure for the synthesis of dehydroalanine and dehydroamino butyric acid from the carbonate derivatives of serine and threonine using TBAF. The antiselective E₂ elimination of the carbonate derivatives of serine and threonine using TBAF is milder and more efficient than other available procedures. The elimination reaction is completed in less than 10 min with various carbonate derivatives studied and the methodology is very efficient for the synthesis of dehydroamino acids and dehydropeptides. The procedure thus provides an easy access to key synthetic precursors and can be used to introduce interesting structural elements to designed peptides. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd.     

Characterization of aLycopersicon esculentum xSolanum lycopersicoides somatic hybrid lacking a glutamate oxaloacetate transaminase isozyme

Morphological, cytological, isozyme and chloroplast DNA analyses were used to determine possible mechanism(s) for the loss of glutamate oxaloacetate transaminase-4 (GOT-4) isozyme activity in a somatic hybrid. Plant 204-1, derived by cell fusion between tomato (Lycopersicon esculentum) andSolanum lycopersicoides, was characterized for bothGot-4 and acid phosphatase-2 (Aps-2), two isozyme loci which are closely linked (recombination 2.5 cM). This hybrid was determined to be chimeric for bothGot-4 andAps-2. TheS. lycopersicoides plant used to provide cells for the fusion was determined to be heterozygous for bothGot-4 andAps-2. Only oneS. lycopersicoides allelic form ofAps-2 andGot-4 was found in plant 204-1. This observation indicated that either the alternative copy of theS. lycopersicoides chromosome region encodingGot-4 andAps-2 is deleted or the entire chromosome is absent. Plant 204-1 was cytologically determined to be aneuploid with approximately 62 chromosomes. Sixty-two somatic hybrids of separate callus origin were analysed for GOT-4 and a high proportion (27%) lacked theS. lycopersicoides form ofGot-4. The loss of this allele and the linkedAps allele most likely occurred in the suspension culture ofS. lycopersicoides used to provide cells for fusion.