Caracterização anatômica da madeira de Eucalyptus benthamii Maiden et Cambage.

The wood anatomy of Eucalyptus benthamii Maiden et Cambage is described. Photomicrographs and photographs in electronic microscope are furnished. Vessels in a diagonal pattern, vasicentric parenchyma, homogeneous rays, libriform and not septated fibers,  pith flecks occasionally were found. The percentage of constituent elements were compared with another species of the family Myrtaceae and the fibers and vascular elements were evaluated in function of the variation in the tree.O presente trabalho trata da descrição dos caracteres gerais e microscópicos da madeira de Eucalyptus benthamii Maiden et Cambage, sendo fornecidas fotomicrografias e fotografias em microscópio eletrônico. Foram encontrados poros em arranjo diagonal, característico do gênero; parênquima vasicêntrico e vasicêntrico confluente; raios homogêneos; fibras libriformes não septadas, e máculas medulares ocasionais. A porcentagem de elementos constituintes foi comparada com outras espécies da família Myrtaceae e as fibras e elementos vasculares avaliados em função da variação dentro da árvore

Diferenciação anatômica da madeira de 4 espécies do gênero Caryocar

An identification key based on anatomic characters is furnished. The species structure was analyzed in relation to wood utilization, taxonomy and filogeny. The results show that Caryocar species are much similar, so its identification is difficult, but the pores diameter and parenchyma can be used for a separation. The graphics shows this variation.Foi elaborada uma chave de identificação baseada em caracteres anatômicos do xilema. A estrutura das espécies foi analisada em relação à taxonomia, filogenia e utilização da madeira. Os resultados obtidos mostraram que as espécies de Caryocar são muito próximas entre si, tornando-se difícil identificação das mesmas pelos caracteres anatômicos qualitativos, entretanto, algumas espécies apresentam caracteres muito peculiares , sendo possível separá-las através do diâmetro dos poros e parênquima axial. Pelos gráficos é possível observar algumas variações no comprimento e diâmetro dos vasos e fibras

Caracterização anatômica da madeira de Grevillea robusta A. Cunn.

The wood anatomy of Grevillea robusta A. Cunn is described. Photomicrographs e photographs in electronic microscope are furnished. Vessels typicaliy in tangential pairs and groups. Parenchyma typicaliy as narrow to wide bands curving inwards between the large rays. Rays of two distinct sizes, usually homogeneous except for occasional sheath cells. Libriform fibers and not septate. Traumatic vertical intercellular canais occasionally present. Stain pith occasionally were found. The constituent elements were analyzed in function of tree position.O presente trabalho trata da descrição dos caracteres gerais e microscópicos da madeira de Grevillea robusta A. Cunn, sendo fornecidas fotomicrografias e fotografias em microscópico eletrônico. Foram encontrados poros múltiplos radiais e tangenciais, associados às faixas de parênquima, formando festões entre os raios; raios homogênios a fracamente heterogêneos, uni e miltisseriados; fibras librioformes não septadas; canais intercelulares radiais e máculas medulares ocasionais. Os elementos constituintes foram avaliados em relação à posição dentro da árvore (base e topo) e dentro do disco (próximo à casca e próximo à medula)

Some like it hot: population-specific adaptations in venom production to abiotic stressors in a widely distributed cnidarian

Background: In cnidarians, antagonistic interactions with predators and prey are mediated by their venom, whose synthesis may be metabolically expensive. The potentially high cost of venom production has been hypothesized to drive population-specific variation in venom expression due to differences in abiotic conditions. However, the effects of environmental factors on venom production have been rarely demonstrated in animals. Here, we explore the impact of specific abiotic stresses on venom production of distinct populations of the sea anemone Nematostella vectensis (Actiniaria, Cnidaria) inhabiting estuaries over a broad geographic range where environmental conditions such as temperatures and salinity vary widely. Results: We challenged Nematostella polyps with heat, salinity, UV light stressors, and a combination of all three factors to determine how abiotic stressors impact toxin expression for individuals collected across this species’ range. Transcriptomics and proteomics revealed that the highly abundant toxin Nv1 was the most downregulated gene under heat stress conditions in multiple populations. Physiological measurements demonstrated that venom is metabolically costly to produce. Strikingly, under a range of abiotic stressors, individuals from different geographic locations along this latitudinal cline modulate differently their venom production levels. Conclusions: We demonstrate that abiotic stress results in venom regulation in Nematostella. Together with anecdotal observations from other cnidarian species, our results suggest this might be a universal phenomenon in Cnidaria. The decrease in venom production under stress conditions across species coupled with the evidence for its high metabolic cost in Nematostella suggests downregulation of venom production under certain conditions may be highly advantageous and adaptive. Furthermore, our results point towards local adaptation of this mechanism in Nematostella populations along a latitudinal cline, possibly resulting from distinct genetics and significant environmental differences between their habitats.publishedVersio

Long-term effect of xylitol chewing gum on dental caries

– About 85% ( n = 269) of the subjects who participated in the Ylivieska follow-up studies on the effect of xylitol chewing gum on dental caries during 1982–84 or 1982–85 were re-examined in 1987 for the analysis of possible long-term preventive effects. Further caries reduction was found 2 or 3 yr after the discontinuation of the use of xylitol. The effect was especially marked in girls; the reduction in caries increment in the post-use years was 60% for the 2-yr users, suggesting that more pronounced caries reduction was associated with the most regular use of xylitol. In teeth erupting during the first year of the use of xylitol gum the long-term preventive effect was greater than in other teeth. Several explanations are suggested: lasting effect of the microbiological changes in the mouth, bacterial colonization on newly erupted teeth by organisms other than S. mutatis , and/or thorough maturation of the teeth under favorable physico-chemical circumstances. The results suggest that the value of xylitol in caries prevention depends on the timing of the treatment in relation to the development of the dentitionPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75700/1/j.1600-0528.1989.tb00611.x.pd

Structure of a putative NTP pyrophosphohydrolase: YP_001813558.1 from Exiguobacterium sibiricum 255-15.

The crystal structure of a putative NTPase, YP_001813558.1 from Exiguobacterium sibiricum 255-15 (PF09934, DUF2166) was determined to 1.78 Å resolution. YP_001813558.1 and its homologs (dimeric dUTPases, MazG proteins and HisE-encoded phosphoribosyl ATP pyrophosphohydrolases) form a superfamily of all-α-helical NTP pyrophosphatases. In dimeric dUTPase-like proteins, a central four-helix bundle forms the active site. However, in YP_001813558.1, an unexpected intertwined swapping of two of the helices that compose the conserved helix bundle results in a `linked dimer' that has not previously been observed for this family. Interestingly, despite this novel mode of dimerization, the metal-binding site for divalent cations, such as magnesium, that are essential for NTPase activity is still conserved. Furthermore, the active-site residues that are involved in sugar binding of the NTPs are also conserved when compared with other α-helical NTPases, but those that recognize the nucleotide bases are not conserved, suggesting a different substrate specificity

Structure of the γ-D-glutamyl-L-diamino acid endopeptidase YkfC from Bacillus cereus in complex with L-Ala-γ-D-Glu: insights into substrate recognition by NlpC/P60 cysteine peptidases.

Dipeptidyl-peptidase VI from Bacillus sphaericus and YkfC from Bacillus subtilis have both previously been characterized as highly specific γ-D-glutamyl-L-diamino acid endopeptidases. The crystal structure of a YkfC ortholog from Bacillus cereus (BcYkfC) at 1.8 Å resolution revealed that it contains two N-terminal bacterial SH3 (SH3b) domains in addition to the C-terminal catalytic NlpC/P60 domain that is ubiquitous in the very large family of cell-wall-related cysteine peptidases. A bound reaction product (L-Ala-γ-D-Glu) enabled the identification of conserved sequence and structural signatures for recognition of L-Ala and γ-D-Glu and, therefore, provides a clear framework for understanding the substrate specificity observed in dipeptidyl-peptidase VI, YkfC and other NlpC/P60 domains in general. The first SH3b domain plays an important role in defining substrate specificity by contributing to the formation of the active site, such that only murein peptides with a free N-terminal alanine are allowed. A conserved tyrosine in the SH3b domain of the YkfC subfamily is correlated with the presence of a conserved acidic residue in the NlpC/P60 domain and both residues interact with the free amine group of the alanine. This structural feature allows the definition of a subfamily of NlpC/P60 enzymes with the same N-terminal substrate requirements, including a previously characterized cyanobacterial L-alanine-γ-D-glutamate endopeptidase that contains the two key components (an NlpC/P60 domain attached to an SH3b domain) for assembly of a YkfC-like active site

The structure of BVU2987 from Bacteroides vulgatus reveals a superfamily of bacterial periplasmic proteins with possible inhibitory function.

Proteins that contain the DUF2874 domain constitute a new Pfam family PF11396. Members of this family have predominantly been identified in microbes found in the human gut and oral cavity. The crystal structure of one member of this family, BVU2987 from Bacteroides vulgatus, has been determined, revealing a β-lactamase inhibitor protein-like structure with a tandem repeat of domains. Sequence analysis and structural comparisons reveal that BVU2987 and other DUF2874 proteins are related to β-lactamase inhibitor protein, PepSY and SmpA_OmlA proteins and hence are likely to function as inhibitory proteins

Possible effect of medically administered antibiotics on the mutans streptococci: implications for reduction in decay

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74585/1/j.1399-302X.1989.tb00103.x.pd