Lichen Communities on White Oaks in East-Central Illinois

This study was conducted as a survey of epiphytic lichen communities occurring on white oak trees at Walnut Point State Park (Douglas Co.) and Fox Ridge State Park (Coles Co.). Using a system of cover classes to estimate lichen cover, quantitative data on the distribution and abundance of epiphytic lichens was obtained. These data were used to calculate summary statistics of each community including total cover, species richness, and Shannon diversity. A total of ten taxa representing six genera were found. The foliose lichen Physcia millegrana had the highest cover in the open canopy habitats while all other taxa had average coverages of less than one percent. Open canopy habitats had consistantly higher cover than the closed canopy habitats although the Fox Ridge open and closed canopy habitats and the Walnut Point open canopy habitats were similar in species richness and Shannon diversity. The Walnut Point closed canopy habitat was almost completely devoid of lichen cover with only Candelaria concolor occuring on ten percent of white oaks sampled

Lichen Communities on White Oaks in East-Central Illinois

This study was conducted as a survey of epiphytic lichen communities occurring on white oak trees at Walnut Point State Park (Douglas Co.) and Fox Ridge State Park (Coles Co.). Using a system of cover classes to estimate lichen cover, quantitative data on the distribution and abundance of epiphytic lichens was obtained. These data were used to calculate summary statistics of each community including total cover, species richness, and Shannon diversity. A total of ten taxa representing six genera were found. The foliose lichen Physcia millegrana had the highest cover in the open canopy habitats while all other taxa had average coverages of less than one percent. Open canopy habitats had consistantly higher cover than the closed canopy habitats although the Fox Ridge open and closed canopy habitats and the Walnut Point open canopy habitats were similar in species richness and Shannon diversity. The Walnut Point closed canopy habitat was almost completely devoid of lichen cover with only Candelaria concolor occuring on ten percent of white oaks sampled

Elementary Functional Properties of Single HCN2 Channels

AbstractHyperpolarization-activated cyclic-nucleotide-gated (HCN) channels are tetramers that evoke rhythmic electrical activity in specialized neurons and cardiac cells. These channels are activated by hyperpolarizing voltage, and the second messenger cAMP can further enhance the activation. Despite the physiological importance of HCN channels, their elementary functional properties are still unclear. In this study, we expressed homotetrameric HCN2 channels in Xenopus oocytes and performed single-channel experiments in patches containing either one or multiple channels. We show that the single-channel conductance is as low as 1.67 pS and that channel activation is a one-step process. We also observed that the time between the hyperpolarizing stimulus and the first channel opening, the first latency, determines the activation process alone. Notably, at maximum hyperpolarization, saturating cAMP drives the channel to open for unusually long periods. In particular, at maximum activation by hyperpolarization and saturating cAMP, the open probability approaches unity. In contrast to other reports, no evidence of interchannel cooperativity was observed. In conclusion, single HCN2 channels operate only with an exceptionally low conductance, and both activating stimuli, voltage and cAMP, exclusively control the open probability

Evolutionary-conserved telomere-linked helicase genes of fission yeast are repressed by silencing factors, RNAi components and the telomere-binding protein Taz1

In Schizosaccharomyces pombe the RNAi machinery and proteins mediating heterochromatin formation regulate the transcription of non-coding centromeric repeats. These repeats share a high sequence similarity with telomere-linked helicase (tlh) genes, implying an ancestral relationship between the two types of elements and suggesting that transcription of the tlh genes might be regulated by the same factors as centromeric repeats. Indeed, we found that mutants lacking the histone methyltransferase Clr4, the Pcu4 cullin, Clr7 or Clr8, accumulate high levels of tlh forward and reverse transcripts. Mutations and conditions perturbing histone acetylation had similar effects further demonstrating that the tlh genes are normally repressed by heterochromatin. In contrast, mutations in the RNAi factors Dcr1, Ago1 or Rdp1 led only to a modest derepression of the tlh genes indicating an alternate pathway recruits heterochromatin components to telomeres. The telomere-binding protein Taz1 might be part of such a redundant pathway, tlh transcripts being present at low levels in Δtaz1 mutants and at higher levels in Δtaz1 Δdcr1 double mutants. Surprisingly, the chromodomain protein Chp1, a component of the Ago1-containing RITS complex, contributes more to tlh repression than Ago1, indicating the repressive effects of Chp1 are partially independent of RITS. The tlh genes are found in the subtelomeric regions of several other fungi raising the intriguing possibility of conserved regulation and function

Photochemistry of glycolaldehyde in cryogenic matrices

International audienceThe photochemistry of glycolaldehyde (GA) upon irradiation at 266 nm is investigated in argon, nitrogen, neon, and para-hydrogen matrices by IR spectroscopy. Isomerization and fragmentation processes are found to compete. The hydrogen-bonded Cis-Cis form of GA is transformed mainly to the open Trans-Trans conformer and to CO and CH3OH fragments and their mixed complexes. Different photo-induced behaviours appear depending on the matrix. In nitrogen, small amounts of Trans-Gauche and Trans-Trans conformers are detected after deposition and grow together upon irradiation. The Trans-Gauche conformer is characterized for the first time. In para-hydrogen due to a weaker cage effect additional H2CO and HCO fragments are seen. Calculations of the potential energy surfaces of S0, S1, and T1 states – to analyse the torsional deformations which are involved in the isomerization process – and a kinetic analysis are presented to investigate the different relaxation pathways of GA. Fragmentation of GA under UV irradiation through the CO+CH3OH molecular channel is a minor process, as in the gas phase

Management Response to the Tsunami, Surin Marine National Park, Thailand

Surin Marine National Park lies northwest of Phuket. Before the 26 December 2004 tsunami, its reputation as the best shallow-water reef in Thailand attracted more than 30000 visitors per year to the 8km2 of fringing reef. Visitor management included fees, permits, specific activities management, a zoning plan and an information centre. Zoning plan exclusion areas included the area of highest biodiversity and a coral bleached area (for natural recovery). While management faced many long-term challenges, it was generally appropriate for the visitation level and threats to the reef system. The tsunami demolished all park infrastructure and effectively destroyed the capacity to manage. Major tourist operators were reduced, currently, from four to two, although dive-boats were largely unaffected. The biodiverse exclusion area and the area most used for snorkelling (near the park headquarters) were destroyed. While tourist arrivals were decimated, rapid recovery is expected with associated demand to access unaffected sites. The problem for management is to re-establish an effective presence and define a regime that is supportive of tourism-recovery, but meets long-term conservation objectives. This paper documents pre and post tsunami reef condition, visitor and operator expectations of management and possible approaches to short and long term management

Novel G-protein-coupled receptor-like proteins in the plant pathogenic fungus Magnaporthe grisea

BACKGROUND: The G-protein-coupled receptors (GPCRs) are one of the largest protein families in human and other animal genomes, but no more than 10 GPCRs have been characterized in fungi. Do fungi contain only this handful or are there more receptors to be discovered? We asked this question using the recently sequenced genome of the fungal plant pathogen Magnaporthe grisea. RESULTS: Proteins with significant similarity to fungus-specific and other eukaryotic GPCRs were identified in M. grisea. These included homologs of known fungal GPCRs, the cAMP receptors from Dictyostelium, and a steroid receptor mPR. We also identified a novel class of receptors typified by PTH11, a cell-surface integral membrane protein required for pathogenicity. PTH11 has seven transmembrane regions and an amino-terminal extracellular cysteine-rich EGF-like domain (CFEM domain), a characteristic also seen in human GPCRs. Sixty-one PTH11-related proteins were identified in M. grisea that shared a common domain with homologs in Neurospora crassa and other fungi belonging to this subphylum of the Ascomycota (the Pezizomycotina). None was detected in other fungal groups (Basidiomycota or other Ascomycota subphyla, including yeasts) or any other eukaryote. The subclass of PTH11 containing the CFEM domain is highly represented in M. grisea. CONCLUSION: In M. grisea we identified homologs of known GPCRs and a novel class of GPCR-like receptors specific to filamentous ascomycetes. A member of this new class, PTH11, is required for pathogenesis, thus suggesting roles in pathogenicity for other members. The identified classes constitute the largest number of GPCR-like proteins reported in fungi to date

Etude de la répartition du grillon des bois Nemobius sylvestris (Rosc) dans un habitat naturel — I. les larves

The spatial distribution of a larval population of wood- crickets (Nemobius sylvestris) has been studied into two obser vation quadrats, located close to the edges of an oak wood near Toulouse (fig. 1). In both study areas, population density varied seasonally, with peak numbers during summer and autumn, depending upon climatic conditions. Whereas larval distribution was clumped all the year round in quadrat A located near the E-W edge of the wood, the situation was different in quadrat B located near the NNe-SSw border of the same wood. The observed difference in larval distribution pattern between the two quadrats can be explained by the effect of forest border orientation upon the aggregation of wood-cricket larvae. At any time of the year, their numbers increased progressively, from the edge of the wood to 15 metres inside, in quadrat A. The situation was different in quadrat B, except in winter time. Larval distribution was also influenced by the proximity of trees. In quadrat A, the wood-cricket larvae were more numerous close to the base of the trees. This also occured in quadrat B, but only during the summer and the autumn. The various factors influencing the spatial distribution of Nemobius sylvestris larvae can act synergically or antagonistically, according to local conditions. However the proximity of a forest border and its orientation appear to play the major roles

New insights into the evolution and structure of Colletotrichum plant-like subtilisins (CPLSs)

The Colletotrichum plant-like subtilisins (CPLSs) are a family of proteins found only in species of the phytopathogenic fungus Colletotrichum. CPLSs have high similarity to plant subtilisins and our previous work has shown that they were acquired by an ancient horizontal gene transfer event from plants. The rapid growth of sequence data in public databases enabled us to reexamine the structure and evolution of the CPLSs. A new plant subtilisin structural model aided us in refining the tertiary structure of CPLSs. Also, new information about protein interactions of plant subtilisin has provided new insights into the putative function of CPLSs. The availability of new genome sequences of members of the genus Colletotrichum gave us the opportunity to further validate our hypothesis that the CPLSs are unique to the Colletotrichum lineage. Together, this information furthers our knowledge of the potential role of the CPLSs in pathogenicity and the role of HGT in the genome evolution of plant pathogenic fungi.Fil: Armijos Jaramillo, Vinicio. Universidad de Salamanca; EspañaFil: Vargas, Walter Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Centro de Estudios Fotosintéticos y Bioquímicos (i); Argentina. Universidad de Salamanca; EspañaFil: Sukno, Serenella A.. Universidad de Salamanca; EspañaFil: Thon, Michael R.. Universidad de Salamanca; Españ