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The first species of Rhizopogon subgenus Amylopogon identified from eastern North America is described here as Rhizopogon kretzerae Grubisha, Dowie, & Mill. sp. nov. In nature, R. kretzerae has been identified only from DNA sequences of the nuclear ribosomal internal transcribed spacer region (ITS) from mycorrhizal roots of Pinus strobus L. and Pterospora andromedea Nutt. Phylogenetic analyses and nucleotide divergence estimates of Rhizopogon ITS sequences from Pterospora roots from Quebec, Michigan, New York, and New Hampshire combined with ITS sequences of Rhizopogon subgenus Amylopogon species type collections suggest R. kretzerae is a sister-group to Rhizopogon salebrosus A.H. Sm. An absence of shared mutations, two informative sequence gaps, and 12 fixed nucleotide differences differentiate R. kretzerae and R. salebrosus. Furthermore, ITS sequences of 40 Pterospora root samples from five populations in the province of Quebec provided the first record of the distribution of R. kretzerae, a potentially rare to endangered species, in eastern Canada. Key words: Rhizopogon kretzerae, mycoheterotrophy, Pterospora andromedea, endangered species, rare fungi. La premiere espece de Rhizopogon sous-genre Amylopogon identifiee dans l'est de l'Amerique du Nord est decrite ici comme Rhizopogon kretzerae Grubisha, Dowie, & Mill. sp. nov. Dans la nature, R. kretzerae n'a ete identifie que par les sequences d'ADN de la region de l'espaceur interne transcrit (ITS) nucleaire ribosomal des racines mycorhiziennes de Pinus strobus L. et Pterospora andromedea Nutt. Les analyses phylogenetiques et l'estimation des divergences nucleotidiques des sequences de l'ITS des racines de Pterospora du Quebec, du Michigan, de l'etat de New-York et du New-Hampshire, combinees aux sequences de l'ITS de collections types de l'espece Rhizopogon sous-genre Amylopogon suggerent que R. kretzerae est un groupe-sreur de Rhizopogon salebrosus A.H. Sm. En absence de mutations partagees, deux lacunes en sequences informatives et 12 differences nucleotidiques fixes differencient R. kretzerae et R. salebrosus. De plus, les sequences des ITS de 40 echantillons de racines de Pterospora de cinq populations de la province de Quebec fournissent la premiere compilation de la distribution de R. kretzerae, une espece rare potentiellement menacee, dans l'est du Canada. [Traduit par la Redaction] Mots-cles: Rhizopogon kretzerae, mycoheterotrophie, Pterospora andromedea, especes menacees, champignons rares., Introduction Mycoheterotrophic plants rely on carbon transferred through a mycorrhizal fungus from a photosynthetic host plant. Pterospora (Monotropoideae, Ericaceae) is a monotypic mycoheterotrophic genus composed of a single species, Pterospora [...]

This study documents the changes in nutrient fluxes associated with internal tidal bores arriving on Florida Keys coral reefs and points to biological use of subthermocline nitrate brought onshore by this mechanism. Internal bores on Conch Reef, Florida Keys, are associated with concentrations of 1.0-4.0 [micro]mol [L.sup.-1] nitrate (N[O.sup.-.sub.3]) and 0.1-0.3 [micro]mol [L.sup.-1] soluble reactive phosphate (SRP) and onshore flow velocities of 0.1-0.3 m [s.sup.-1]. The arrival of internal bores causes 10-40 fold increases in nutrient concentrations and 1-2 orders of magnitude increases in nutrient flux relative to ambient, nonbore conditions. The magnitude and duration of cool-water nutrient transport events increases significantly with increasing depth on reef slopes. In June 2001, the gradient of increased exposure to subsurface water with depth corresponded to increased percentage of N and [[delta].sup.15]N and decreased C: N ratio in a common benthic macroalga, Codium isthmocladum. Internal tidal bores are widespread throughout the Florida Keys reef tract, with cool-water episodes influencing reefs up to 10%-25% of the time during summer months and with significant variability among years. Estimated inputs of nitrogen and phosphorus by internal tidal bores to Florida Keys reef slopes are as much as 40-fold larger than published estimates of inputs to near-shore waters from waste water and storm water runoff. Internal tidal upwelling represents an important, previously underestimated, episodic source of nutrients on the Florida Keys reef tract. In order to assess nutrient availability in this system accurately it is essential to understand natural sources of high-frequency variability.

Developmental dyslexia, characterized by unexplained difficulty in reading, is associated with behavioral deficits in phonological processing. Functional neuroimaging studies have shown a deficit in the neural mechanisms underlying phonological processing in children and adults with dyslexia. The present study examined whether behavioral remediation ameliorates these dysfunctional neural mechanisms in children with dyslexia. Functional MRI was performed on 20 children with dyslexia (8-12 years old) during phonological processing before and after a remediation program focused on auditory processing and oral language training. Behaviorally, training improved oral language and reading performance. Physiologically, children with dyslexia showed increased activity in multiple brain areas. Increases occurred in left temporo-parietal cortex and left inferior frontal gyrus, bringing brain activation in these regions closer to that seen in normal-reading children. Increased activity was observed also in right-hemisphere frontal and temporal regions and in the anterior cingulate gyrus. Children with dyslexia showed a correlation between the magnitude of increased activation in left temporo-parietal cortex and improvement in oral language ability. These results suggest that a partial remediation of language-processing deficits, resulting in improved reading, ameliorates disrupted function in brain regions associated with phonological processing and produces additional compensatory activation in other brain regions.

Children with language-based learning impairments (LLIs) have major deficits in their recognition of some rapidly successive phonetic elements and nonspeech sound stimuli. In the current study, LLI children were engaged in adaptive training exercises mounted as computer 'games' designed to drive improvements in their 'temporal processing' skills. With 8 to 16 hours of training during a 20-day period, LLI children improved markedly in their abilities to recognize brief and fast sequences of nonspeech and speech stimuli., Experiments conducted in human 1) and monkey (2) neurological models of perceptual learning have demonstrated that the capacity for segmentation of successive events in sensory input streams can be sharpened, [...]

ALTHOUGH WE AGREE WITH J. M. PANDOLFI et al.'s ('Are U.S. coral reefs on the slippery slope to slime?', Policy Forum, 18 Mar., p. 1725) vision of reversing coral reef [...]

The pathogen for the coral disease that appeared on the Florida Reef Tract in Jun 1995 has been identified as a new species of Sphingomonas. Experiments show that the pathogen is easily transmissible. There was almost no disease recurrence on the reefs of the Florida Keys in 1996 and 1997, but new outbreaks were found in the western section of the Florida Reef Tract in 1996 and on the reefs north of Miami, FL, in 1997.