Microsatellite markers for the whelk Buccinum undatum

Five microsatellite loci are described for the commercially exploited marine gastropod, Buccinum undatum. Levels of polymorphism were variable with three to 19 alleles per locus and expected heterozygosities of 0.26–0.94 in 60 individuals of the population from which the loci were isolated. Homozygote excess at two of the loci might be attributable to null alleles, and these loci should not be used in, for example, parentage analysis. Nevertheless, because null allele frequencies can be estimated and their effects partitioned, all are useful markers for studies of population differentiation.     

A Sequential Study of Cell Divisions and Expansion Patterns on a Single Developing Shoot Apex of Vinca major

During the growth of a single developing vegetative apex ofVinca major, both the orientation and frequency of cell divisions,and the pattern of cell expansion, were observed using a non-destructivereplica technique. Micrographs taken at daily intervals illustratethat the central region of the apical dome remains relativelyinactive, except for a phase of cell division which occurs after2 d of growth. The majority of growth takes place at the proximalregions of the dome from which develop the successive pairsof leaves. The developing leaf primordia are initiated by aseries of divisions which occur at the periphery of the centraldome and are oriented parallel to the axis of the subsequentleaves. The cells which develop into the outer leaf surfaceof the new leaves undergo expansion and these cells divide allowingfor the formation of the new leaf. This paper describes thefirst high-resolution sequential study of cell patterns in asingle developing plant apex. Sequential development, cell division, expansion patterns, SEM, Vinca major, apical dome, leaf primordium, leaf initiation     

Noninvasive methodology for the sampling and extraction of DNA from free‐ranging Atlantic spotted dolphins (Stenella frontalis)

Genetic sampling and molecular investigations are important parts of studying wild populations. However, collecting tissues from free‐ranging animals can be difficult or impractical. This study develops a sampling and extraction protocol for template DNA from faecal material collected in a marine environment from small cetaceans. DNA was extracted from faecal material of free‐ranging Atlantic spotted dolphins (Stenella frontalis) and subsequently tested for its suitability in molecular investigations by amplifying both mitochondrial and nuclear DNA. The resulting mitochondrial sequences were found to closely match known S. frontalis haplotypes. Three microsatellite loci were amplified and fall within the expected size range for cetaceans. Mother and calf families previously assigned by observation were genetically confirmed using both mitochondrial haplotype and allele sharing between the mother and offspring. The protocol effectively collects and extracts dolphin DNA from faecal samples and enables species identification as well as confirmation of genetic relatedness and should be considered as a noninvasive alternative to current protocols.     

Developmental instability: measures of resistance and resilience using pumpkin (Cucurbita pepo L.)

Fluctuating asymmetry measures random deviations from bilateral symmetry, and thus estimates developmental instability, the loss of ability by an organism to regulate its development. There have been few rigorous tests of this proposition. Regulation of bilateral symmetry must involve either feedback between the sides or independent regulation toward a symmetric set point. Either kind of regulation should decrease asymmetry over time, but only right–left feedback produces compensatory growth across sides, seen as antipersistent growth following perturbation. Here, we describe the developmental trajectories of perturbed and unperturbed leaves of pumpkin, Cucurbita pepo L., grown at three densities. Covering one side of a leaf with aluminium foil for 24 h perturbed leaf growth. Reduced growth on the perturbed side caused leaves to become more asymmetrical than unperturbed controls. After the treatment the size-corrected asymmetry decreased over time. In addition, rescaled range analysis showed that asymmetry was antipersistent rather than random, i.e. fluctuation in one direction was likely to be followed by fluctuations in the opposite direction. Development involves right–left feedback. This feedback reduced size-corrected asymmetry over time most strongly in the lowest density treatment suggesting that developmental instability results from a lack of resilience rather than resistance.   © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 78, 27–41.     

The Effect of Sodium Iodate and Melanin on the Formation of Glyoxylate

Sodium iodate damages retinal pigment epithelium specifically, but the reason for this specificity is not well understood. The work reported here describes an effect of sodium iodate on melanin, a major component of the retinal pigment epithelium. Sodium iodate increases the ability of melanin to convert glycine to glyoxylate. Almost ten times as much glyoxylate is formed when sodium iodate is present compared to the amount formed with melanin alone, although iodate alone does not convert glycine to glyoxylate. A chemical reaction between sodium iodate and melanin is suggested as a partial explanation of the specificity of iodate toxicity towards retinal pigment epithelium.     

Plant functional trait variation in relation to riparian geomorphology: The importance of disturbance

This study examined the patterns of plant functional trait variation in relation to geomorphology, disturbance and a suite of other environmental factors in the riparian margin of the Upper Hunter River, New South Wales, Australia. Vegetation was surveyed on three geomorphic surfaces (point bar, bench and bank) along a 5.5‐km stretch of the Upper Hunter River. Functional traits relating to plant growth and reproduction were collected for the identified species. anova and principal components analysis were used to compare the trait assemblages of species associated with each geomorphic unit. Pearson's correlation coefficients were used to investigate trait variation with respect to environmental variables. There were clear differences in the plant functional trait assemblages associated with the three geomorphic units. Generally the point bar was associated with species that were herbaceous, with small seed mass, a short stature and a high specific leaf area (SLA). Conversely, the bench was associated with grasses that had unassisted seed dispersal and intermediate seed mass and SLA, while species on the bank had tall stature, large seed mass, a high SLA and a perennial life cycle. Variation along the primary gradient of plant functional trait composition was most strongly related to disturbance frequency and to a lesser extent soil nutrients and the proportion of clay and silt, while variation along the secondary gradient was associated with variation in substrate texture as well as soil nutrients.