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Another Pathway (another + pathway)

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Life Sciences	50%

Selected Abstracts

High-nickel insects and nickel hyperaccumulator plants: A review

INSECT SCIENCE, Issue 1 2009
Robert S. Boyd
Abstract Insects can vary greatly in whole-body elemental concentrations. Recent investigations of insects associated with Ni hyperaccumulator plants have identified insects with relatively elevated whole-body Ni levels. Evaluation of the limited data available indicates that a whole-body Ni concentration of 500 ,g Ni/g is exceptional: I propose that an insect species with a mean value of 500 ,g Ni/g or greater, in either larval/nymphal or adult stages, be considered a "high-Ni insect". Using the 500 ,g Ni/g criterion, 15 species of high-Ni insects have been identified to date from studies in Mpumalanga (South Africa), New Caledonia and California (USA). The highest mean Ni concentration reported is 3 500 ,g Ni/g for nymphs of a South African Stenoscepa species (Orthoptera: Pyrgomorphidae). The majority of high-Ni insects (66%) are heteropteran herbivores. Studies of high-Ni insect host preference indicate they are monophagous (or nearly so) on a particular Ni hyperaccumulator plant species. Much of the Ni in bodies of these insects is in their guts (up to 66%,75%), but elevated levels have also been found in Malpighian tubules, suggesting efficient elimination as one strategy for dealing with a high-Ni diet. Tissue levels of Ni are generally much lower than gut concentrations, but up to 1200 ,g Ni/g has been reported from exuviae, suggesting that molting may be another pathway of Ni elimination. One ecological function of the high Ni concentration of these insects may be to defend them against natural enemies, but to date only one experimental test has supported this "elemental defense" hypothesis. Community-level studies indicate that high-Ni insects mobilize Ni into food webs but that bioaccumulation of Ni does not occur at either plant-herbivore or herbivore-predator steps. Unsurprisingly, Ni bioaccumulation indices are greater for high-Ni insects compared to other insect species that feed on Ni hyperaccumulator plants. There is some evidence of Ni mobilization into food webs by insect visitors to flowers of Ni hyperaccumulator plants, but no high-Ni insect floral visitors have been reported. [source]

Skp2 and p27kip1 expression in melanocytic nevi and melanoma: an inverse relationship,

JOURNAL OF CUTANEOUS PATHOLOGY, Issue 10 2004
Qing Li
Background:, S-phase kinase associated protein-2 (Skp2) ubiquitin ligase p45SKP2 is important in the degradation of p27kip1 (a cyclin dependent kinase inhibitor) and progression through the G1-S cell-cycle checkpoint. Low levels of p27 and high levels of Skp2 are related to poor prognosis in some cancers. Methods:, Clinicopathologic features and immunohistochemical expression of Skp2 and p27kip1 were investigated in 198 melanocytic proliferations: 21 melanocytic nevi, 23 melanoma in situ, 119 primary melanoma, and 35 metastatic melanoma samples. Comparative and survival analyses were performed. Results:, Progressive and significant increases and decreases in the nuclear expression of Skp2 and p27kip1, respectively, was identified moving from melanocytic nevi (0.05 ± 0.2/85 ± 15) to melanoma in situ (3 ± 2/45 ± 20) to primary cutaneous melanoma (12 ± 9/30 ± 25) to metastatic melanoma (25 ± 15/15 ± 20) (p , 0.006). Expression of these proteins also significantly correlated with increasing American Joint Committee on Cancer (AJCC) T (tumor) classification and AJCC stage (p , 0.01). Moreover, the level of these two proteins exhibited a significant inverse relationship (r = ,0.4, p = 0.0001). Skp2 cytoplasmic labeling index of >20% predicted worse 10-year overall survival (38% vs. 86%, p = 0.04) in primary melanoma. Neither p27 nor Skp2 nuclear expression impacted significantly on prognosis. Conclusions:, Gain of Skp2 and loss of p27kip1 protein expression are implicated in melanoma progression where the level of p27kip1 may be regulated by targeted proteolysis via Skp2. Cytoplasmic expression of Skp2 defines a subset of aggressive melanomas and could represent another pathway of deregulation of the cell cycle. [source]

Steam reactivation of a spent sorbent for enhanced SO2 capture in FBC

AICHE JOURNAL, Issue 12 2006
Fabio Montagnaro
Abstract The regeneration by steam hydration of the sulfur capture ability of spent sorbent particles from Fluidized Bed Combustion (FBC) is addressed. The process is characterized in terms of effectiveness of sorbent reactivation, hydration degree, particle sulfation pattern, development of accessible porosity, and extent of particle attrition and fragmentation. Steam reactivation experiments were carried out in a lab-scale atmospheric FBC at 250°C for 10, 30, and 180 min with 0.05 MPa steam partial pressure. The effectiveness of sorbent reactivation was assessed by reinjecting the reactivated material into the FB reactor operated at 850°C under simulated desulfurization conditions and following the degree of calcium conversion and the attrition rate along with resulfation. The experimental results indicated that steam reactivation is effective in renewing the SO2 uptake ability of the exhausted sorbent particles. The regeneration mechanism based on the swelling upon hydration of the unreacted core, the generation of fissures and cracks, and the consequent development of accessible porosity is confirmed for the limestone under scrutiny. In addition to this, a remarkable result was that steam hydration induces, for the sorbent under investigation, a pronounced sulfur redistribution throughout the particle cross-section, which provides another pathway to the enhancement of the sulfur capture ability of the reactivated sorbent. © 2006 American Institute of Chemical Engineers AIChE J, 2006 [source]

Notching up another pathway

BIOESSAYS, Issue 5 2002
Keith Brennan
The Notch proteins play a vital role in cell fate decisions in both invertebrate and vertebrate development. Careful analysis of this role has led to a model of signalling downstream of these receptors, via the CSL (CBF1, Suppressor of Hairless, Lag-1) family of transcription factors. There have been suggestions, however, that Notch can signal through other pathways. In the current paper, Ramain et al.1 provide compelling evidence for Notch signalling through a CSL-independent pathway and they demonstrate that the cytoplasmic protein, Deltex, is required for this signal. In addition, they show that Wnt signalling may regulate this Deltex-dependent signal. BioEssays 24:405,410, 2002. © 2002 Wiley Periodicals, Inc. [source]