Unreported yet massive deforestation driving loss of endemic biodiversity in Indian Himalaya

Deforestation is a primary driver of biotic extinctions in the tropics. The impacts of deforestation in tropical biodiversity hotspots are of particular concern because these regions contain high concentrations of globally endemic species. However, the effects of large-scale deforestation on native biotas within the biodiversity hotspot of Himalaya remain poorly documented. Here we report on an alarming trend of deforestation in the Indian Himalaya and project the likely consequential extinctions of endemic taxa (species and subspecies) by 2100 across a broad range of taxonomic groups, including gymnosperms, angiosperms, fishes, amphibians, reptiles, birds, and mammals. With the current level of deforestation, by 2100 only about 10% of the land area of the Indian Himalaya will be covered by dense forest (>40% canopy cover)—a scenario in which almost a quarter of the endemic species could be wiped out, including 366 endemic vascular plant taxa and 35 endemic vertebrate taxa. We also show that inaccurate reporting of forest cover data by governmental institutions can result in underestimations of the biological impacts of deforestation, as well as potential miscalculations in land-use decisions (e.g., the construction of hydroelectric dams). Large-scale conservation efforts, including forest protection and reforestation, are urgently needed to avoid the impending deforestation-driven biodiversity losses in the Himalaya.     

Rac1 GTPase is activated by hepatitis B virus replication--involvement of HBX

Hepatitis B virus (HBV) is a causative agent for liver diseases including hepatocellular carcinoma. Understanding its interactions with cellular proteins is critical in the elucidation of the mechanisms of disease progression. Using a cell-based HBV replication system, we showed that HBV replication in HepG2 cells resulted in a cellular morphological changes displaying membrane rufflings and lamellipodia like structures reminiscent of cells expressing constitutively activated Rac1. We also showed that activated Rac1 resulted in increased viral replication. HBV replication specifically activated wild type Rac1, but not Cdc42. The Rac1 activation by HBV replication also resulted in the phosphorylation of ERK1/2 and AKT, the downstream targets of Rac1 signaling cascade. The smallest HBV viral protein, HBX, was able to activate the endogenous Rac1 and induce membrane ruffling when transfected into cells. Significantly, HBX was found to directly interact with a Rac1 nucleotide exchange factor (betaPIX) through a SH3 binding motif. Taken together, we have shown the interaction of HBV with the Rho GTPase, affecting cell morphology through the Rac1 activation pathway. HBV may possibly make use of an activated Rac1 signaling pathway for increased replication and resultant metastatic effects.     

NIR fluorescent ytterbium compound for in vivo fluorescence molecular imaging

We have developed a new NIR fluorescent probe based on an ytterbium(III) (E)‐1‐(pyridin‐2‐yl‐diazenyl)naphthalen‐2‐ol (PAN) complex. This probe emits near‐infrared luminescence derived from the Yb ion through excitation of the PAN moiety with visible light (λ_ex = 530 nm, λ_em = 975 nm). The results support the possible utility of the probe for in vivo fluorescence molecular imaging. Copyright © 2009 John Wiley & Sons, Ltd.     

Binding of FAD to cytochrome b558 is facilitated during activation of the phagocyte NADPH oxidase, leading to superoxide production

The superoxide-producing phagocyte NADPH oxidase can be reconstituted in a cell-free system. The activity of NADPH oxidase is dependent on FAD, but the physiological status of FAD in the oxidase is not fully elucidated. To clarify the role of FAD in NADPH oxidase, FAD-free full-length recombinant p47(phox), p67(phox), p40(phox), and Rac were prepared, and the activity was reconstituted with these proteins and purified cytochrome b(558) (cyt b(558)) with different amounts of FAD. A remarkably high activity, over 100 micromol/s/micromol heme, was obtained in the oxidase with purified cyt b(558), ternary complex (p47-p67-p40(phox)), and Rac. From titration with FAD of the activity of NADPH oxidase reconstituted with purified FAD-devoid cyt b, the dissociation constant K(d) of FAD in cyt b(558) of reconstituted oxidase was estimated as nearly 1 nm. We also examined addition of FAD on the assembly process in reconstituted oxidase. The activity was remarkably enhanced when FAD was present during assembly process, and the efficacy of incorporating FAD into the vacant FAD site in purified cyt b(558) increased, compared when FAD was added after assembly processes. The absorption spectra of reconstituted oxidase under anaerobiosis showed that incorporation of FAD into cyt b(558) recovered electron flow from NADPH to heme. From both K(d) values of FAD and the amount of incorporated FAD in cyt b(558) of reconstituted oxidase, in combination with spectra, we propose the model in which the K(d) values of FAD in cyt b(558) is changeable after activation and FAD binding works as a switch to regulate electron transfer in NADPH oxidase.     

Enhancement of the endotoxin recognition pathway by ventilation with a large tidal volume in rabbits

Ventilation with a small tidal volume (V(t)) is associated with better clinical outcomes than with a large V(t), particularly in critical settings, including acute lung injury. To determine whether V(t) influences the lipopolysaccaharide (LPS) recognition pathway, we studied CD14 expression in rabbit lungs and the release of TNF-alpha by cultured alveolar macrophages after 240 min of ventilation with a large (20 ml/kg) vs. a small (5 ml/kg) V(t). We also applied small or large V(t) to lungs instilled with 50 microg/kg of LPS. The alveolar macrophages collected after large V(t) ventilation revealed a 20-fold increase in LPS-induced TNF-alpha release compared with those collected after small V(t) ventilation, whereas TNF-alpha was undetectable without LPS stimulation. In animals ventilated with a large V(t), the expression of CD14 mRNA in whole lung homogenates and the expression of CD14 protein on alveolar macrophages, assessed by immunohistochemistry, were both significantly increased in the absence of LPS stimulation. A large V(t) applied to LPS-instilled lungs increased the pulmonary albumin permeability and TNF-alpha release into the plasma. These results suggest that mechanical stress caused by a large V(t) sensitizes the lungs to endotoxin, a phenomenon that may occur partially via the upregulation of CD14.     

Pitcher plant facilitates prey capture in a sympatric congener

Carnivorous plants avoid below-ground competition for nitrogen by utilizing an alternative nitrogen resource—invertebrate prey, but it remains unclear if sympatric carnivorous plants compete for prey resources. The aim of this study was to investigate if exploitative prey-resource competition occurs between the two sympatric pitcher plant species, Nepenthes rafflesiana and N. gracilis in Singapore. We first investigated if prey-resource partitioning occurs between these two species, and then investigated niche shift in N. gracilis by examining its pitcher contents along an in situ gradient of N. rafflesiana interspecific competition. Our results showed clear evidence of resource partitioning between the two species, but contrary to the expectation of competition, proximity to N. rafflesiana pitchers correlated with higher total prey numbers in N. gracilis pitchers. Our multivariate model of prey assemblages further suggested that N. rafflesiana facilitates N. gracilis prey capture, especially in several ant taxa that are trapped by both species. Concurrently, we found strong evidence for intraspecific competition between N. gracilis pitchers, suggesting that prey resources are exhaustible by pitcher-predation. Our results show that resource partitioning can be associated with facilitative interactions, instead of competition as is usually assumed. Facilitation is more typically expected between phylogenetically distant species, but divergences in resource acquisition strategies can permit facilitation between congeners.