FITNESS CONSEQUENCES OF VARIATION IN EGG SIZE AND FOOD ABUNDANCE IN BROOK TROUT SALVELINUS FONTINALIS

Relationships between egg size and juvenile survival in brook trout, Salvelinus fontinalis, were determined experimentally at two levels of food abundance and then incorporated into a model that related maternal fitness to egg size and food supply. Egg volume was positively correlated with juvenile size at hatching and size at yolk sac resorption but had no significant effect on embryonic survival or development time. Juvenile survival was linearly related to egg size throughout the first 50 days of exogenous feeding at high and low food levels. The effects of egg size and food abundance on juvenile survival were not additive. Decreased food abundance significantly increased mortality among the smallest eggs but had a negligible effect on the largest eggs. Model simulations indicate that maternal fitness is a curvilinear function of egg size and that food supply influences both the height and the shape of the function. The fitness functions provide empirical support for the hypothesis that selection favors an increase in offspring size with reductions in resource abundance.     

Phylogenetic utility of elongation factor-1 alpha in noctuoidea (Insecta: Lepidoptera): the limits of synonymous substitution

To test its phylogenetic utility, nucleotide sequence variation in a 1,240-bp fragment of the elongation factor-1 alpha (EF-1 alpha) gene was examined in 49 moth species representing the major groups of the superfamily Noctuoidea. Both parsimony and distance analyses supported the monophyly of nearly all groups for which there are clear morphological synapomorphies. Clades of subfamily rank and lower, probably mid-Tertiary and younger, were strongly supported. The third codon position contains 88% of variable sites, and approaches saturation at approximately 20% sequence divergence, possibly due to among-site rate heterogeneity and composition bias; higher divergences occur only in association with shifts in composition. Surprisingly, the few nonsynonymous changes appear no more phylogenetically reliable than synonymous changes. Signal strength for basal divergences is weak and fails to improve with character weighting; thus, dense taxon sampling is probably needed for strong inference from EF-1 alpha regarding deeper splits in Noctuoidea (probably early Tertiary). EF-1 alpha synonymous changes show promise for phylogeny reconstruction within Noctuidae and other groups of Tertiary age.      

Differential response to shading in orthotropic and plagiotropic shoots of the clonal herb Glechoma hirsuta

Previous studies have shown that internodes and petioles of closely related erect and stoloniferous species show marked differences in their response to shading. Vertical structures show strong elongation responses while horizontal structures show significantly smaller elongation responses. This paper reports an experiment designed to test whether internodes and petioles on orthotropic (vertically oriented) and plagiotropic (horizontally oriented) shoots produced by the same plant, also show such differential responses. The study species, Glechoma hirsuta, produces plagiotropic shoots in its vegetative stage and orthotropic shoots during its generative stage. Shoots of G. hirsuta were grown either in full daylight or under simulated canopy shade. Internode and petiole elongation, biomass investment patterns and other growth-related parameters were measured on plants in each light treatment. In orthotropic shoots the length of internodes responded more strongly to shading than the length of petioles, while the opposite was true for plagiotropic shoots, confirming the hypothesis that vertical spacers have higher degrees of shade-induced plasticity than horizontally oriented spacers. Growth and development of horizontally oriented shoots was reduced by shading, whereas that of vertically oriented shoots was unaffected by light treatment. The results are discussed in terms of the differences in function of vertically and horizontally oriented spacers, and the probable benefits of plasticity in enhancing essential activities including photosynthesis, habitat exploration and seed dispersal. Received: 23 December 1996 / Accepted: 19 July 1997     

Human responses to propionic acid. I. Quantification of within- and between-participant variation in perception by normosmics and anosmics

The objective of this study was to fully characterize normosmic perception of stimuli expected to cause widely varying degrees of olfactory and nasal trigeminal stimulation and to directly evaluate the possible role of olfactory nerve stimulation in nasal irritation sensitivity. During each of four identical test sessions, four anosmic and 31 normosmic participants were presented with a range of concentrations extending from peri-threshold for normosmics to supra- threshold for anosmics. For each session, odor (O) and nasal irritation (NI) sensitivities were summarized in terms of the concentrations required to produce four sensation levels ('iso-response' concentrations). Within-participant variation in these iso-response concentrations was < 10-fold for 95% of normosmics, for both O and NI. For O but not NI, these apparent fluctuations in sensitivity were largely accounted for by the uncertainty surrounding the iso-response concentrations calculated for each session. Anosmics exhibited minimal within- and between-participant variation in NI and required, for all but the highest perceptual level, a higher concentration than almost all normosmics. Between-participant variation, expressed in terms of 90% confidence interval widths, was approximately 0.5 log units for both O and NI for the highest perceptual level, but increased to approximately 0.8 and 1.8 log units, respectively, for the lowest (peri- threshold) level. Our findings suggest that: (i) most apparent variation over time in O sensitivity is actually a reflection of the uncertainty surrounding estimates of sensitivity obtained for each session; (ii) within- and between-participant variation in O sensitivity is far less than is commonly reported; and (iii) low to moderate levels of NI in normosmics are the result of relatively weak trigeminal stimulation combined with much greater olfactory activation.      

Monoclonal antibody 91.9H raised against sulfated mucins is specific for the 3'-sulfated Lewisa tetrasaccharide sequence

The IgG1hybridoma antibody, 91.9H, was originally raised against sulfated mucins isolated from normal human colonic mucosa. Previous studies have shown that the 91.9H antigen is expressed on normal colonic epithelial cells and the sulfomucins that they produce, but not in the normal small intestine and stomach. Tissue-specific changes occur in 91.9H antigen expression in disease: the antigen diminishes in colonic carcinomas, whereas in regions of gastric mucosa showing intestinal metaplasia and in gastric carcinomas, the antigen is expressed as a "neo-antigen." This report is concerned with elucidation, by the neoglycolipid technology, of the determinant recognized by antibody 91.9H using sulfated and sialyl oligosaccharides of Lewisa(Lea) and Lextypes, and analogs that lack sulfate, sialic acid, or fucose. Binding experiments with the lipid-linked oligosaccharides immobilized on chromatograms or on microwells, and inhibition of binding experiments with free oligosaccharides based on di-, tri- and tetrasaccharide backbones, show that the 91.9H antigenic determinant is based on a trisaccharide backbone, and consists of the 3'-sulfated Leatetrasaccharide sequence, which is a potent ligand for the E- and L-selectins. The antibody gives a relatively low signal with the 3'-sulfated non-fucosylated backbone, and has no detectable cross- reaction with the 3'-sulfated Lexisomer, nor with sialyl-Leaand - Lexanalogues. Antibody 91.9H is a valuable addition, therefore, to the repertoire of reagents for mapping details of the distribution, and determining the relative importance of sulfated and sialyl oligosaccharides as ligands for the selectins, in normal and pathological epithelia and endothelia.      

Incongruent estimates of population differentiation among brook charr, Salvelinus fontinalis, from Cape Race, Newfoundland, Canada, based upon allozyme and mitochondrial DNA variation

We determined the amount and temporal stability of genetic differentiation among brook cham sampled from five rivers on Cape Race, Newfoundland, with an electrophoretic analysis of 42 protein coding loci. Fish from four of these rivers were analysed for restriction fragment length polymorphisms in mitochondrial DNA (mtDNA). A single mtDNA clone was observed in all rivers sampled, except one, where 47% offish were from a different and relatively divergent clone (0.31 % sequence divergence). In contrast, Cape Race brook charr show large amounts of genetic differentiation at six enzyme coding loci; Nei's genetic distance ranged between 0,020 and 0.048. This differentiation is relatively stable as no significant differences in allele frequencies were detected between fish sampled from two rivers over two consecutive years. The most divergent population based on protein polymorphism is not that with two mtDNA clonal lineages. In contrast to the commonly held view, mtDNA analyses do not necessarily provide greater resolution of population structure than allozyme analyses.     

Temporal variations of macroborers in massive Porites lobata on Moorea,French Polynesia

Massive colonies of Porites lobata on the barrier reef of Tiahura, Moorea, can be divided into four categories: living colonies, colonies consisting of 50% live coral and 50% dead skeleton, 100% dead coral and colonies which have been reduced to a basal plate. Replicate samples of each of these colony types were collected in the same vicinity of the barrier reef during October 1987. The macroborers were extracted, identified, counted and their volumes determined by displacement. Kruskal-Wallis tests showed that three different boring communities occur within these four categories of Porites colonies. Live colonies are characterised by only 3 species, the bivalve, Lithophaga laevigata; the vermetid Dendropoma maximun; and the non boring serpulid polychaete Spirobranchus. The completely dead colonies contain up to 17 boring species, with five to six individuals per 100 cm. Sipunculans are the dominant bioeroders with the most abundant species being Aspidosiphon elegans, sp A and sp B. Colonies of Porites which have been reduced to basal plates contain up to 18 boring species of which the bivalve Lithophaga hanleyana and the sipunculan Aspidosiphon sp. B are the most abundant.The cumulative volume of CaCO₃ lost by boring activity increases from 0.1 cm³ per 100 cm³ in a completely dead Porites colony to 1.4 cm³ per 100 cm³ in the residual basal plates of Porites. These can be extrapolated to minimum losses of 14.2 kg m^-3. We suggest that rates of boring increase with the time which has elapsed since the death of the colony and the dominant agents of boring also change with increasing age of the coral structure. There are significant additional losses of 5.25 kg m^-3 CaCO₃ caused by grazing echinoids and scarids.     

Light and electron microscopic studies of cellular localization of oPL with monoclonal and polyclonal antibodies.

Accurate knowledge of placental lactogen localization is fundamental to any hypothesis of its synthesis and secretion. We used locally generated monoclonal and polyclonal antibodies from three separate sources to localize ovine placental lactogen immunoreactivity on light and electron microscope Lowicryl K4M sections of ovine placentomes of 97-145 days of gestation, using immunogold techniques. All antibodies demonstrated that immunoreactivity was exclusively localized in the trophoectoderm binucleate cell Golgi body and granules and in granules in the syncytium derived from binucleate cell migration. No evidence was found to support a recent claim that monoclonal antibodies to oPL that were produced in Canada indicated a predominant localization of ovine placental lactogen to uninucleate trophectodermal cells.