Physiological Ecology of Sulfide Metabolism in Hydrothermal Vent and Cold Seep Vesicomyid Clams and Vestimentiferan Tube Worms

SYNOPSIS. The primary ecosystem-structuring organisms at manyhydrothermal vents and cold seeps are phylogenetically relatedand quite similar physiologically and anatomically. Vestimentiferantube worms and Vesicomyid clams in particular all rely on chemoautotrophicsulfur-oxidizing symbionts and have blood which binds sulfidewith high affinity and capacity. However, there are significantdifferences between cold seep and hydrothermal vent environments,including large differences in flow rate of the emitted fluidand the chemistry of that fluid. Here we review extant dataon the hydrothermal vent species, present new data on the physiologicallyrelevant chemical microhabitat of cold seep vestimentiferansand vesicomyids, and compare the physiological ecology of theseep species to their hydrothermal vent relatives     

Gamete Recognition and Egg Activation in Sea Urchins

SYNOPSIS. Free-spawning marine invertebrates face the challengeof ensuring that gametes of the same species come into contact,recognize, bind to and fuse with one another once they havebeen released by the adults. Coordinated spawning, chemoattractionand specific cell-cell recognition events help to overcome thischallenge. One marine invertebrate, the sea urchin, has servedas a model system for the study of gamete recognition and fertilizationfor over 100 years. Recent biochemical and molecular advancesin this area have begun to address the questions that have beenraised by the results of elegant physiological observations.The picture of fertilization that is emerging is characterizedby highly specific cell-cell interactions between proteins onthe surfaces of the gametes. These proteins then mediate thebinding and subsequent events that lead to activation of theegg and delivery of the male genetic material. Because of theserecent insights, the sea urchin egg is in a position to provideanswers to one of the central debates in developmental biology—themechanism of egg activation. Does the sperm deliver an activatingfactor? Does sperm binding trigger a receptor-mediated signal?Or is the mechanism a complex combination? With the tools andknowledge gained from the study of sea urchin fertilization,testing of these hypotheses should be feasible in the near future.     

A FURTHER STUDY OF THE TOXICITY OF POTASSIUM CYANIDE TO RAINBOW TROUT (SALMO GAIRDNERII RICHARDSON)

The distributions of the periods of survival of individual rainbow trout in solutions of potassium cyanide are asymmetrical and approximately log-normal within the range of concentration where the relation between log time and log concentration is linear, whereas they are symmetrical and approximately normal at higher concentrations.
Some inherent, persistent features possessed by the fish influence survival time in both the higher and lower ranges of concentration, but other such features exert a significant influence only in the lower concentrations.
Some of the features influencing survival time in the lower concentration range only, are associated with body size.     

FLAVOR THRESHOLDS FOR VANILLIN AND PREDICTIONS OF HIGHER OR LOWER THRESHOLDS

Thesholds for vanillin dissolved in water were determined first by 32 panelists, then by 100 additional panelists. Extreme-value analysis was applied to the results from the first 32 determinations to estimate the likelihood of thresholds later encountered being even lower than those already detected. No threshold among the 100 additional determinations was below the 5% confidence limit for the regression curve based on the 32 determinations originally made. There was evidence that some panelists were ageusic to vanillin in aqueous solution. Although some investigators have suggested that the frequency distribution for threshold values of vanillin is bimodal, application of the Kolmogorov-smirnov test to the distribution of the 132 values, as natural logarithms, gave little cause to reject the hypothesis that the distribution was unimodal.     

Storage of samples infected with lettuce or cucumber mosaic viruses prior to testing by ELISA

Methods of processing and storing lettuce mosaic and cucumber mosaic virus infected tissues prior to ELISA have been examined. Virus antigen detection was highest in samples homogenised in phosphate inoculation buffer (1% K₂HPO₄, 0.1% Na₂SO₃) and stored at either — 20°C or — 196°C. Detection was poor in samples homogenised in phosphate buffered saline prior to storage and in samples of all treatments stored at 4°C. Freeze-dried leaf segments retained a high concentration of antigen, as did freeze-dried homogenates of samples prepared in inoculation buffer. Higher levels of antigen were detected in samples stored as whole leaves at 4°C for 24 h before processing, than in samples stored as leaf segments during this period.     

Cholinesterases in the Carotid Body of the Cat as seen with the Electron Microscope

THE response of the carotid body of the cat to the stimuli of hypoxia and hypercapnia is indicated by a large increase in signal traffic in the afferent nerve, but the transducer mechanism is unknown. There are two principal schools of thought, one proposing the involvement of an adrenergic mechanism, the other a cholinergic mechanism. Among the evidence for the cholinergic mechanism is the response of the carotid body to local injections of acetylcholine, which cause an increase in the afferent nerve impulses¹. Recently acetylcholine, or a very similar substance, has been found in the carotid body in considerable amounts².     

Neuroendocrine Mechanisms of Environmental Integration

SYNOPSIS. In the dwarf Siberian hamster, Phodopus sungorus,the photoperiodic response can be modified by numerous environmentalstimuli, including social interactions, dietary, and climaticchanges. Photoperiodic information is processed in both themedial basal hypothalamus and the preoptic area. Transfer ofanimals from a long summer photoperiod to a short winter photoperiodresults in decreases in the concentration of both norepinephrineand dopamine in both of these brain areas. Results from thesestudies indicate that both dietary supplements and social interactionscan override the effects of day length on changes in brain neurotransmitters.Specifically, social interactions can override the decreasesin norepinephrine and dopamine in the medial basal hypothalamusbut not the preoptic area. Conversely, dietary manipulationsoverride the decreases in the preoptic area but not in the medialbasal hypothalamus. These results suggest that photoperiod isa general stimulus that depresses neurotransmitter activityin multiple brain areas including the medial basal hypothalamus,and preoptic area. Fine tuning information, such as dietaryand social cues, is then processed in very specific areas ofthe brain and can override the photoperiod induced changes inthese specific areas     

Survival and Causes of Mortality of Head-Started Western Pond Turtles on Pierce National Wildlife Refuge,Washington

ABSTRACT The western pond turtle (Actinemys marmorata) is a species of conservation concern over much of its range and is listed as endangered in Washington State. From 2000 to 2004, we used radiotelemetry to document survival and mortality factors of head-started western pond turtles (n = 68) released into Pierce National Wildlife Refuge in southwestern Washington. Survival estimates for first year and older turtles ranged from 86% to 97% and overlapping confidence intervals indicated no detectible differences among age classes or among years. Subadult turtles released at ≥90-mm carapace length apparently avoided capture by most aquatic predators, indicating that terrestrial predators should be the focus of research and management where predation on larger age-classes is a concern. High annual survival combined with the documented nesting by ≥7-year-old female head-started turtles in Washington suggest that recruitment of adults is being achieved; however, head-starting is only practical as an interim solution and strategies for effective removal of aquatic predators must be developed and implemented where natural recruitment is inadequate to maintain populations.     

A unifying study of phenotypic and molecular genetic variability in natural populations of Anadenanthera colubrina var. cebil from Yungas and Paranaense biogeographic provinces in Argentina

Anadenanthera colubrina var. cebil is a discontinuously distributed native tree species in South American subtropical forests. Thirteen quantitative traits and eight nuclear microsatellite loci were examined in individuals from two biogeographic provinces of Argentina to determine the number and composition of genetically distinguishable groups of individuals and explore possible spatial patterns of the phenotypic and genetic variability. Means of reproductive traits were higher in the Yungas than in the Paranaense biogeographic province, whereas five out of eight nonreproductive quantitative traits showed higher mean values in the latter. Variance coefficients were moderate, and there were significant differences between and within provinces. Three clusters were defined based on spatial model for cluster membership for quantitative traits. One cluster grouped the individuals from the Paranaense biogeographic province whereas the individuals from the Yungas biogeographic province grouped regarding its population of origin. Parameters of molecular genetic variability showed higher values in the Yungas than in the Paranaense biogeographic province. Observed heterozygosity was lower than expected heterozygosity in both biogeographic provinces, indicating an excess of homozygosity. The homozygosity test by Watterson and the exact test by Slatkin suggested diversifying selection for locus Ac41.1. Bayesian clustering spatial model for microsatellites loci data were performed for both all loci and for all loci excluding locus Ac41.1. In both analyses two clusters were inferred. Analysis of molecular variance revealed similar results for all genotypes and for all genotypes defined excluding locus Ac41.1. Most of the total variance is attributable to genetic variation within clusters. The presence of homogeneous clusters was detected for both the phenotypic and molecular genetic variability. Two Bayesian clustering analyses were performed according to molecular genetic data, and two clusters were inferred. Individuals were assigned to their provinces of origin. Genetic molecular variation was higher in the populations of the Yungas biogeographic province which translates into highly qualified populations for conservation. Populations from the Paranaense biogeographic province showed the highest mean value of number of seeds per fruit making them valuable as well with regard to the exploitation of management strategies as a means to recover the impacted areas where these populations are located.