Fur seals at Macquarie Island: post-sealing colonisation,trends in abundance and hybridisation of three species

Commercial sealers exterminated the original fur seal population at Macquarie Island in the early 1800s. The first breeding record since the sealing era was not reported until March 1955. Three species of fur seal now occur at Macquarie Island, the Antarctic (Arctocephalus gazella), subantarctic (A. tropicalis) and New Zealand (A. forsteri) fur seal. Census data from 54 breeding seasons in the period 1954–2007 were used to estimate population status and growth for each species. Between the 1950s and 1970s, annual increases in pup production for the species aggregate were low. Between 1986 and 2007, pup production of Antarctic fur seals increased by about 8.8% per year and subantarctic fur seals by 6.8% per year. The New Zealand fur seal, although the most numerous fur seal species on Macquarie Island, has yet to establish a breeding population, due to the absence of reproductively mature females. Hybridisation among species is significant, but appears to be declining. The slow establishment and growth of fur seal populations on Macquarie Island appears to have been affected by its distance from major population centres and hence low immigration rates, asynchronous colonisation times of males and females of each species, and extensive hybridisation.     

Response of breeding duck pairs to predator reduction in North Dakota

Predator management regularly improves waterfowl nesting success, often beyond levels believed necessary for population maintenance. If recruitment, survival of breeding females, and/or breeding site fidelity is increased on predator-reduced sites, then local breeding populations may increase in subsequent years. During 2005–2008, we annually conducted breeding pair surveys on >600 wetlands at 6 township-sized (93.2 km²) trapped sites and 4 non-trapped sites for the 5 most common upland nesting ducks in eastern North Dakota, USA. For each species, we developed a series of competing regression models that related breeding pair abundance to wetland size, predator management, and upland habitats adjacent to sampled wetlands. In contrast to previous studies, we found limited and equivocal evidence that breeding populations increased following predator management. We discuss multiple potential explanations for this lack of effect and suggest that managers should not assume that increased production as a product of elevated nest success will be compounded over years. © The Wildlife Society, 2013     

922. LINDERA OBTUSILOBA

Lindera obtusiloba Blume is illustrated. Its distribution in China, Japan and Korea is reported. The synonyms are listed and discussed. Instructions for its cultivation are given.     

The dynamics of the flavour precursors, the S-alk(en)yl-L-cysteine sulphoxides, during leaf blade and scale development in the onion (Allium cepa)

This study was undertaken to determine the patterns of accumulation and loss of the flavour precursors. (+) S-1-propyl-L-cysteine sulphoxide, (+) trans-S-1-propenyl-L-cysteine sulphoxide, and (+) S-1-methyl-L-cysteine sulphoxide, during the development and senescence of the leaf blades and scales of a brown onion ( Allium cepa L. cv. Pukekohe Longkeeper).
The levels of the flavour precursors were related to the ontogeny of the individual leaf blade and scale, and the ontogeny of the entire plant. Leaf blades which developed on a young or bulbing onion contained all 3 flavour precursors (total of about 50–70 mg leaf⁻¹); but as each attached scale developed, the leaf blades lost their flavour precursors. All 3 flavour precursors increased in the developing scales and decreased in the senescing scales. Leaf blades which developed on an older, ripening onion contained, and then lost, only (+) S-1-propyl-L-cysteine sulphoxide, whilst the scales accumulated only (+) S-1-propyl-L-cysteine sulphoxide; (+) S-1-methyl-L-cysteine sulphoxide and (+) trans-S-1-propenyl-L-cysteine sulphoxide were minimal. In the main scales of the onion, which did not senesce during ripening, there was a transition between these two patterns. These scales accumulated all 3 flavour precursors with (+) S-1-propyl-L-cysteine sulphoxide remaining constant at about 30 mg/scale; however there was a 10 fold loss of the other 2 flavour precursors (from 20 to about 2 mg/scale). The base plate (true stem) contained mainly (+) S-1-propyl-L-cysteine sulphoxide, which increased 5 fold in amount during bulbing. The other 2 flavour precursors were present at much lower levels.
A recycling of flavour precursors is suggested, with the leaf blades supplying flavour precursors to scales, and in turn older senescing scales recycling their flavour precursors to developing younger scales.     

Identification of histidine residues in Wolinella succinogenes hydrogenase that are essential for menaquinone reduction by H2

The cytochrome b subunit (HydC) of Wolinella succinogenes hydrogenase binds two haem B groups. This is concluded from the haem B content of the isolated hydrogenase and is confirmed by the response of its cytochrome b to redox titration. In addition, three of the four haem B ligands were identified by characterizing mutants with the corresponding histidine residues replaced by alanine or methionine. Substitution in HydC of His-25, His-67 or His-186, which are, in addition to His-200, predicted to be haem B ligands, caused the loss of quinone reactivity of the hydrogenase, while the activity of benzylviologen reduction was retained. The corresponding mutants did not grow with H₂ as electron donor and either fumarate or polysulphide as terminal electron acceptor. The mutants grown with formate and fumarate did not catalyse electron transport from H₂ to fumarate or to polysulphide, or quinone reduction by H₂, in contrast to the wild-type strain. Cytochrome b was not reduced by H₂ in the Triton X-100 extract of the mutant membranes, which contained wild-type amounts of the mutated HydC protein. Substitution in HydC of His-122, His-158 or His-187, which are predicted not to be haem B ligands, yielded mutants with wild-type properties. Substitution in HydA of His-188 or of His-305 resulted in mutants with the same properties as those lacking one of the haem B ligands of HydC. His-305 is located in the membrane-integrated C-terminal helix of HydA. His-188 of HydA is predicted to be a ligand of the distal iron–sulphur centre that may serve as the direct electron donor to the haem B groups of HydC. The results suggest that each of the three predicted haem B ligands of HydC tested (out of four) is required for electron transport from H₂ to either fumarate or polysulphide, and for quinone reactivity. This also holds true for the two conserved histidine residues of HydA.     

Nutritional evaluation of buffalo gourd: Elemental analysis of seed

Cucurbita foetidissima is a native American wild plant with potential as a protein food and oil source. Research has previously been done on the composition of its amino acids and oils and on methods for cultivating it. This paper provides a comprehensive mineral analysis of the seeds and whole gourds and demonstrates that nutritional qualities of the buffalo gourd compare favorably with dry cow-feed. Buffalo gourd seed was also found to contain a trypsin inhibitor.     

Inhibition of lignin peroxidase H2 by sodium azide.

The oxidation of veratryl alcohol (3,4-dimethoxybenzyl alcohol) by lignin peroxidase H2 from Phanerochaete chrysosporium and H2O2 was strongly inhibited by sodium azide. Inhibition was competitive with respect to veratryl alcohol (Ki = 1-2 microM) and uncompetitive with respect to H2O2. In contrast, sodium azide bound to the native enzyme at pH 6.0 with an apparent dissociation constant (KD) of 126 mM. Formation of azidyl radicals was detected by ESR spin trapping techniques. The enzymes is nearly completely inactivated in four turnovers. The H2O2-activated enzyme intermediate (compound I) reacted with sodium azide to form a new species rather than be reduced to the enzyme intermediate compound II. The new species has absorption maxima at 418, 540, and 570 nm, suggesting the formation of a ferrous-lignin peroxidase-NO complex. Confirmation of this assignment was obtained by low-temperature ESR spectroscopy. An identical complex could be simulated by the addition of nitrite to the reduced enzyme. The enzyme intermediate compound II is readily reduced by sodium azide to native enzyme with essentially no loss of activity.     

Production of cloned carboxypeptidase G2 by Escherichia coli: Genetic and environmental considerations

Summary The optimum production of cloned carboxypeptidase G₂ from plasmid pNM21 byEscherichia coli was found to be strongly strain- and temperature-dependent. The superior host was strain RV308 and the preferred growth temperature 28°C. Copy number, which decreased during exponential growth of all strains examined, did not relate in these studies to the level of enzyme production: the strain with the highest enzyme yield also having the lowest overall copy number.