Recent population estimates and trends in numbers of albatrosses and giant petrels breeding at the sub-Antarctic Prince Edward Islands

The second mid-summer survey of surface-nesting seabirds at the Prince Edward Island group (Marion and Prince Edward islands) was conducted during December 2008, seven years after the initial mid-summer survey. Wandering albatrosses Diomedea exulans may have decreased slightly at Prince Edward Island, mirroring a decrease of  roughly 2% per year at Marion Island from 1998 to 2005, a decline that has since reversed. Numbers of grey-headed albatrosses Thalassarche chrysostoma on Marion Island have remained stable, whereas the population on Prince Edward Island decreased by 20% from 2001 to 2008 (3% per year). The estimate of Indian yellow-nosed albatrosses T. carteri at Prince Edward Island was similar in 2001 and 2008. Counts of both sooty albatrosses Phoebetria spp. were substantially higher at Prince Edward Island in 2008, possibly as a result of better coverage compared to 2001. Dark-mantled sooty albatrosses P. fusca on Marion Island have decreased by almost 2% per year since 1996, continuing a negative trend from the early 1980s, whereas light-mantled sooty albatrosses P. palpebrata have increased by almost 6% per year at Marion Island since 1996. Counts of both giant petrels increased at Prince Edward Island (northern Macronectes halli by 44%; southern M. giganteus by 28%), whereas their numbers have remained stable at Marion Island. Current best estimates for annual breeding populations (pairs) at the two islands are 3 650 wandering albatrosses, 9 500 grey-headed albatrosses, 7 000 Indian yellow-nosed albatrosses, 2 900  dark-mantled sooty albatrosses, 800 lightmantled sooty albatrosses, 750 northern giant petrels and 2 800 southern giant petrels, confirming the global importance of the Prince Edward Islands for these seven species. Apart from the dark-mantled sooty albatross, their populations are reasonably healthy despite fishing mortality.Keywords: Diomedea; Macronectes; Marion Island; population size; population trends; Phoebetria; Prince Edward Island; ThalassarcheAfrican Journal of Marine Science 2009, 31(3): 409–41

Cross-Sectional Validity Study of Compressive Leg Checking in Measuring Artificially Created Leg Length Inequality

For most metabolic pathways, the uptake of the substrate into the cell represents the first step. This transport reaction can exert a large control on the flux through the pathway, in particular when the substrate concentration becomes limiting. Besides serving a role in the uptake of nutrients and the excretion of metabolic (end)products or drugs, transport systems can have one or more other functions in the physiology of the cell. Two of these functions, control of carbohydrate utilization and regulation of cell volume, have been well established in lactic acid bacteria (LAB). The first example concerns the phosphoenolpyruvate-dependent phosphotransferase system (PTS), which serves a role in the transport of sugars into the cell but also regulates the activity of metabolic pathways, either through regulation of transcription and/or (in)activation of transporters and key enzymes already present. The regulation by the PTS results in a hierarchy in the utilization of sugars and/or adjustment of the first step(s) of a metabolic pathway to the metabolic capacity of the cell and the availability of a particular substrate. The second example relates to the activation of transporters (and mechanosensitive channels), which represents the first mechanism of defence against osmotic stress. The activation by osmotic-upshift of the ATP-binding Cassette (ABC) transporter OpuA from Lactococcus lactis is compared with the activation by osmotic-downshift of mechanosensitive channels. The mechanosensitive channels have been best studied in organisms other than LAB, but the presence of similar systems in LAB, and their conservation of structure, suggest that the postulated functions and mechanisms generally hold.