Validation of the new combination <Emphasis Type="Italic">Mattirolomyces austroafricanus</Emphasis>

An error in correcting page proofs of a previous paper led to an invalid new combination, Mattirolomyces westraliensis. Here the correct new combination, Mattirolomyces austroafricanus, is validated.     

Synthesis of N-glycan oxazolines: donors for endohexosaminidase catalysed glycosylation

Oxazoline mono-, di-, tri- and hexasaccharides, corresponding to the core components of N-linked glycoprotein high mannose glycans, are synthesised as potential glycosyl donors for endohexosaminidase catalysed glycosylation of glycopeptides and glycoprotein remodelling. The crucial beta-D-Manp-(1-->4)-D-GlcpNAc linkage is synthesised via epimerisation of gluco disaccharide substrates by sequential triflation and nucleophilic substitution. Oxazolines are formed directly from the anomeric OPMP protected N-acetyl glucosamine derivatives. Efficient endohexosaminidase catalysed glycosylation of a synthetic beta-D-GlcpNAcAsn glycosyl amino acid is demonstrated with the trisaccharide oxazoline donor.     

Palatability and efficacy to possums and rats of pest control baits containing bird repellents

Repellents used to reduce by-kill of birds during pest control must not compromise acceptance by target species. Two repellents combined, anthraquinone (AQ; 0.4 g kg^?1) and d-pulegone (DP; 1.0) did not reduce the palatability of blue-coloured carrot baits to laboratory rats (Rattus norvegicus); nor did DP (2.0). Green-coloured carrot baits coated with AQ, DP or AQ + DP were taken from bait stations by wild possums (Trichosurus vulpecula) and rats. Toxic (1080) bait coated with AQ (0.4) and peanut oil (0.1) had reduced palatability but was accepted by laboratory rats. However, laboratory rats did not consume enough baits coated with AQ and bacon, peanut butter, cinnamon or DP to be killed. Anthraquinone (0.4 or 0.8) plus cinnamon and DP (0.5) did not affect palatability or lethality to captive ship rats (R. rattus) or possums. Anthraquinone and DP as surface coatings on baits are therefore acceptable to possums and possibly rats, at concentrations that deter some bird species.     

INTERCHANGE AND ISOLATION OF HUMPBACK WHALES OFF CALIFORNIA AND OTHER NORTH PACIFIC FEEDING GROUNDS

Humpback whales feed in several high-latitude areas of the North Pacific. We examined the interchange of humpback whales between one of these areas, off California, and those in other feeding grounds in the eastern North Pacific:. Fluke photographs of 597 humpback whales identified off California between 1986 and 1992 were compared with those off Oregon and Washington (29); British Columbia (81); southeastern Alaska (343); Prince William Sound, Alaska (141); Kodiak Island, Alaska (104); Shumagin Islands, Alaska (22); and in the Bering Sea (7). A high degree of interchange, both inter-and intrayear, was found among humpback whales seen off California, Oregon, and Washington., A low rate of interchange was found between British Columbia and California.: two whales seen near the British Columbia/Washington border were photographed off California in a different year, No interchange was found between California and the three feeding areas in Alaska. Humpback whales off California, Oregon, and Washington form a single intermixing feeding aggregation with only limited interchange with areas farther north. These findings are consistent with photographic identification studies in the North Atlantic and with genetic studies in both the North Atlantic and North Pacific.     

Oxidative degradation of bilirubin produces vasoactive compounds.

Subarachnoid haemorrhage is often followed by haemolysis and concomitant oxidative stress, and is frequently complicated by pathological vasoconstriction or cerebral vasospasm. It is known that upregulation of haem oxygenase (HO-1) is induced by oxidative stress and results in release of biliverdin and bilirubin (BR), which are scavengers of reactive oxygen species (ROS). Here we report biomimetic studies aimed at modelling pathological conditions leading to oxidative degradation of BR. Oxidative degradation products of BR, formed by reaction with hydrogen peroxide (an ROS model system), demonstrated biological activity by stimulating oxygen consumption and force development in vascular smooth muscle from porcine carotid artery. Analogous biological activity was observed with vasoactive cerebrospinal fluid from subarachnoid haemorrhage patients. Three degradation products of BR were isolated: two were assigned as isomeric monopyrrole (C9H11N2O2) derivatives, 4-methyl-5-oxo-3-vinyl-(1, 5-dihydropyrrol-2-ylidene)acetamide and 3-methyl-5-oxo-4-vinyl-(1, 5-dihydropyrrol-2-ylidene)acetamide and the third was 4-methyl-3-vinylmaleimide (MVM), a previously isolated photodegradation product of biliverdin. Possible mechanisms of oxidative degradation of BR are discussed. Tentative assignment of these structures in the cerebrospinal fluid (CSF) of cerebral vasospasm patients has been made. It is proposed that one or more of the degradation products of biliverdin or bilirubin are involved in complications such as vasospasm and or pathological vasoconstriction associated with haemorrhage.     

Mechanistic insights into the inhibition of serine proteases by monocyclic lactams.

Although originally discovered as inhibitors of pencillin-binding proteins, beta-lactams have more recently found utility as serine protease inhibitors. Indeed through their ability to react irreversibly with nucleophilic serine residues they have proved extraordinarily successful as enzyme inhibitors. Consequently there has been much speculation as to the reason for the general effectiveness of beta-lactams as antibacterials or inhibitors of hydrolytic enzymes. The interaction of analogous beta- and gamma-lactams with a serine protease was investigated. Three series of gamma-lactams based upon monocyclic beta-lactam inhibitors of elastase [Firestone, R. A. et al. (1990) Tetrahedron 46, 2255-2262.] but with an extra methylene group inserted between three of the bonds in the ring were synthesized. Their interaction with porcine pancreatic elastase and their efficacy as inhibitors were evaluated through the use of kinetic, NMR, mass spectrometric, and X-ray crystallographic analyses. The first series, with the methylene group inserted between C-3 and C-4 of the beta-lactam template, were readily hydrolyzed but were inactive or very weakly active as inhibitors. The second series, with the methylene group between C-4 and the nitrogen of the beta-lactam template, were inhibitory and reacted reversibly with PPE to form acyl-enzyme complexes, which were stable with respect to hydrolysis. The third series, with the methylene group inserted between C-2 and C-3, were not hydrolyzed and were not inhibitors consistent with lack of binding to PPE. Comparison of the crystal structure of the acyl-enzyme complex formed between PPE and a second series gamma-lactam and that formed between PPE and a peptide [Wilmouth, R. C., et al. (1997) Nat. Struct. Biol. 4, 456-462.] reveals why the complexes formed with this series were resistant to hydrolysis and suggests ways in which stable acyl-enzyme complexes might be obtained from monocyclic gamma-lactam-based inhibitors.     

The synthesis of oligomers of oxetane-based dipeptide isosteres derived from L-rhamnose or D-xylose.

Routes to oligomers (dimers, tetramers, hexamers) of five oxetane-based dipeptide isosteres have been established. Methyl 2,4-anhydro-5-azido-5-deoxy-L-rhamnonate 'monomer' led, by coupling the corresponding carboxylic acid and amine, to a 'dimer'. Reverse-aldol ring-opening occurred on attempted saponification of the dimer, so all further oligomerization was performed using TBDMS C-3 hydroxyl protection. The silyl protected L-rhamnonate monomer led in turn to the dimer (via the monomer acid and amine), the tetramer (via the dimer acid and amine) and finally the hexamer (via the tetramer acid and dimer amine). In each case the acids were obtained through saponification of the respective methyl esters and the amines were obtained by hydrogenation of the azides; coupling was TBTU-mediated. Essentially the same strategy was employed on equivalent D-lyxonate, 6-deoxy-L-altronate, 6-deoxy-D-gulonate and D-fuconate dipeptide isosteres to give the respective dimers, tetramers and hexamers.     

Oxygen consumption, ventilatory frequency and heart rate of lampreys (Lampetra fluviatilis) during their spawning run.

1. The standard rate of oxygen consumption, ventilatory frequency and heart rate of adult Lampetra fluviatilis were measured during the light phase of the photoperiod and at times corresponding to various stages in the upstream migration. 2. All three parameters increased during the spawning run but only in mature individuals were significant differences found between the sexes. 3. The regression coefficients for the logarithmic relationship between oxygen consumption and body weight of immature animals were 0.912 and 0.925 at 9.5 and 16 degrees C respectively. 4. Both the standard rate of oxygen consumption and the amount of oxygen taken up during activity increased greatly during the hours of darkness. 5. Oxygen consumption, ventilatory frequency and, to a lesser extent, heart rate increased significantly at 9.5 degrees C over the 100-20% range of saturation with air. 6. Below 20% saturation with air, lampreys no longer remained attached by their oral disc for prolonged periods and the ventilatory frequency rose even more rapidly to reach a maximum of 175 beats/min at 12.5%. Exposure to 7.5% resulted in death within 5-8 h.