Letter to Editor: Alpo Bites Back

The author critiques the article in IJSAP (1983, 4(2)101-107) addressing the question of the correct amount of protein in a dog’s diet and notes that one of the critics of high protein diets has close ties to a different pet food company that manufactures and sells low protein diets

Molecular phylogeny of brachiopods and phoronids based on nuclear-encoded small subunit ribosomal RNA gene sequences

Brachiopod and phoronid phylogeny is inferred from SSU rDNA sequences of 28 articulate and nine inarticulate brachiopods, three phoronids, two ectoprocts and various outgroups, using gene trees reconstructed by weighted parsimony, distance and maximum likelihood methods. Of these sequences, 33 from brachiopods, two from phoronids and one each from an ectoproct and a priapulan are newly determined. The brachiopod sequences belong to 31 different genera and thus survey about 10% of extant genus-level diversity. Sequences determined in different laboratories and those from closely related taxa agree well, but evidence is presented suggesting that one published phoronid sequence (GenBank accession UO12648) is a brachiopod-phoronid chimaera, and this sequence is excluded from the analyses. The chiton, Acanthopleura, is identified as the phenetically proximal outgroup; other selected outgroups were chosen to allow comparison with recent, non-molecular analyses of brachiopod phylogeny. The different outgroups and methods of phylogenetic reconstruction lead to similar results, with differences mainly in the resolution of weakly supported ancient and recent nodes, including the divergence of inarticulate brachiopod sub-phyla, the position of the rhynchonellids in relation to long- and short-looped articulate brachiopod clades and the relationships of some articulate brachiopod genera and species. Attention is drawn to the problem presented by nodes that are strongly supported by non-molecular evidence but receive only low bootstrap resampling support. Overall, the gene trees agree with morphology-based brachiopod taxonomy, but novel relationships are tentatively suggested for thecideidine and megathyrid brachiopods. Articulate brachiopods are found to be monophyletic in all reconstructions, but monophyly of inarticulate brachiopods and the possible inclusion of phoronids in the inarticulate brachiopod clade are less strongly established. Phoronids are clearly excluded from a sister-group relationship with articulate brachiopods, this proposed relationship being due to the rejected, chimaeric sequence (GenBank UO12648). Lineage relative rate tests show no heterogeneity of evolutionary rate among articulate brachiopod sequences, but indicate that inarticulate brachiopod plus phoronid sequences evolve somewhat more slowly. Both brachiopods and phoronids evolve slowly by comparison with other invertebrates. A number of palaeontologically dated times of earliest appearance are used to make upper and lower estimates of the global rate of brachiopod SSU rDNA evolution, and these estimates are used to infer the likely divergence times of other nodes in the gene tree. There is reasonable agreement between most inferred molecular and palaeontological ages. The estimated rates of SSU rDNA sequence evolution suggest that the last common ancestor of brachiopods, chitons and other protostome invertebrates (Lophotrochozoa and Ecdysozoa) lived deep in Precambrian time. Results of this first DNA-based, taxonomically representative analysis of brachiopod phylogeny are in broad agreement with current morphology-based classification and systematics and are largely consistent with the hypothesis that brachiopod shell ontogeny and morphology are a good guide to phylogeny

Origins and Effects of Spartina Wrack in a Virginia Salt Marsh

Movements of mats of tidal wrack (dead Spartina alterniflora) and impacts of the wrack were followed in color infrared aerial photographs of a sloping foreshore salt marsh on Wallops Island, Virginia. Tidal wrack may be stranded in high marsh, where it decomposes, or it may be temporarily stranded at lower elevations. The wrack kills underlying Spartina alterniflora in low marsh and in the transition zone from low to high marsh. Wrack is the major cause of devegetated areas within the marsh, but these areas eventually revegetate, and do not evolve into pans. There are substantial short-term reductions in S. alterniflora marsh productivity. Other effects of wrack are discussed

Origins and Effects of Spartina Wrack in a Virginia Salt Marsh

Movements of mats of tidal wrack (dead Spartina alterniflora) and impacts of the wrack were followed in color infrared aerial photographs of a sloping foreshore salt marsh on Wallops Island, Virginia. Tidal wrack may be stranded in high marsh, where it decomposes, or it may be temporarily stranded at lower elevations. The wrack kills underlying Spartina alterniflora in low marsh and in the transition zone from low to high marsh. Wrack is the major cause of devegetated areas within the marsh, but these areas eventually revegetate, and do not evolve into pans. There are substantial short-term reductions in S. alterniflora marsh productivity. Other effects of wrack are discussed

Distribution of the Marsh Periwinkle Littorina irrorata (Say) in a Virginia Salt Marsh

Littorina irrorata varies over its geographic range in maximum size, preferred elevations relative to tidal datum planes, and in the type of vegetation it inhabits. On Wallops Island, Virginia, postlarvae of Littorina irrorata with shell lengths \u3c 5 mm long live almost exclusively in dead, curled-up leaves of Spartina alterniflora at elevations near mean tide level, below elevations occupied by larger conspecifics. Snails longer than 5 mm in length increase in average size with decreasing elevation. This distribution is opposite to that found by Hamilton (1978) in a marsh in Florida. No difference was found in our study area in growth rate of marked snails at two different elevations, so the size-elevation gradient probably is not caused by differences in growth rate. Snails 15 to 19 mm long are more active when exposed to reduced salinities than snails \u3e 21 mm long. The lowest salinities recorded in the marsh occurred at the highest elevations. This salinity effect, together with mortality from known size-selective predators, may account, at least in part, for the seaward increase in mean shell size

Distribution of the Marsh Periwinkle Littorina irrorata (Say) in a Virginia Salt Marsh

Littorina irrorata varies over its geographic range in maximum size, preferred elevations relative to tidal datum planes, and in the type of vegetation it inhabits. On Wallops Island, Virginia, postlarvae of Littorina irrorata with shell lengths \u3c 5 mm long live almost exclusively in dead, curled-up leaves of Spartina alterniflora at elevations near mean tide level, below elevations occupied by larger conspecifics. Snails longer than 5 mm in length increase in average size with decreasing elevation. This distribution is opposite to that found by Hamilton (1978) in a marsh in Florida. No difference was found in our study area in growth rate of marked snails at two different elevations, so the size-elevation gradient probably is not caused by differences in growth rate. Snails 15 to 19 mm long are more active when exposed to reduced salinities than snails \u3e 21 mm long. The lowest salinities recorded in the marsh occurred at the highest elevations. This salinity effect, together with mortality from known size-selective predators, may account, at least in part, for the seaward increase in mean shell size

Size-Specific Emergence of the Marsh Snail, Littorina irrorata: Effect of Predation by Blue Crabs in a Virginia Salt Marsh

Marsh periwinkles of 5 to 7 mm in shell height were eaten regularly by blue crabs. Fractures marking unsuccessful crab attacks were present in about 25% of medium-sized (10-16 mm) snails and over 60% of larger snails (over 16 mm). Medium-sized snails, subject to predation, leave the water more frequently than larger snails, but only about a quarter of the snail population leaves the water during high tide. We found no evidence that the snails leave the water because they sense blue crabs in the water

Disorders of Fatty Acid Oxidation in the Era of Tandem Mass Spectrometry in Newborn Screening

With recent advances in laboratory technology with tandem mass spectrometry (MS/MS), the number of infants identified with a fatty acid oxidation disorder has increased dramatically. Disorders of fatty acid oxidation comprise one of the most rapidly growing groups within the field of errors of metabolism. This review will explore the recent developments in newborn screening related to the use of tandem mass spectrometry and disorders of fatty acid oxidation

Elevational Variations in the Lowest Limit of Spartina Colonization in a Virginia Salt Marsh

Elevations of lowest colonization of smooth cordgrass, Spartina alterniflora, were surveyed along the edge of a juvenile salt marsh at Wallops Island, Virginia. This lowest limit of Spartina varied over one-third of the local mean tidal range, with lowest occurrences between mean low water and mean low water neaps. Four geographical factors appeared to influence the lowest limit of Spartina: (1) tidal scouring in areas where tidal channels were constricted, (2) scalloping of the marsh edge over a sloping substrate, (3) patterns of historical development of the marsh, and (4) ice scouring of previously colonized Spartina over winter. Marsh edge scallops occurred only in areas of former Spartina thatch islands, and probably resulted from lateral spreading of those islands

Short-Term Accretional and Erosional Patterns in a Virginia Salt Marsh

We estimated 3-year average rates of accretion and erosion in different vegetation zones of a juvenile Spartina alterniflora salt marsh at Wallops Island, Virginia, by precise releveling of a fixed grid. Seaward of the marsh there was extremely variable accretion and erosion in tidal flat, as a result of winter ice scouring and transport. At the lower limit of the marsh, tall Spartina edge marsh accreted at about 6.2 mm yr-1, well in excess of relative sea level rise, supplied by mineral sediments. At the upper limit, levee Spartina and high marsh accreted at about 1.6 mm yr-1, in equilibrium with sea level rise. Accretion there was supplemented by organic sediments from tidal wrack. At mid-elevations, medium Spartina middle marsh eroded slightly at about -0.6 mm yr-1, and low-density Spartina and bare soil eroded rapidly at about -5.3 mm yr-1. These zones may be relatively sediment-starved. The most severe erosion resulted from vegetation diebacks beneath tidal wrack. Patterns of accretion and erosion show that this site is maturing topographically from a juvenile foreshore marsh to a creek-drained marsh