Late-successional and old-growth forests in the northeastern United States: Structure, dynamics, and prospects for restoration.

Abstract Restoration of old-growth forest structure is an emerging silvicultural goal, especially in those regions where old-growth abundance falls below the historic range of variability. However, longitudinal studies of old-growth dynamics that can inform silvicultural and policy options are few. We analyzed the change in structure, including stand density, diameter distribution, and the abundance of large live, standing dead, and downed dead trees on 58 late-successional and old-growth plots in Maine, USA, and compared these to regional data from the U.S. Forest Inventory and Analysis program. Structural dynamics on the late-successional plots reflected orderly change associated with density-dependent growth and mortality, but dynamics on the old-growth plots were more variable. Some plots experienced heavy mortality associated with beech bark disease. Diameter distributions conformed poorly to a classic exponential distribution, and did not converge toward such a distribution at the plot scale. Although large live trees showed a broad trend of increasing density in regional forests, recent harvesting patterns offset a considerable fraction of those gains, while mean diameter was static and the number of large dead trees was weakly declining. Even though forests of the northeast are aging, changes in silviculture and forest policy are necessary to accelerate restoration of old-growth structure

Human gut Bacteroides capture vitamin B12 via cell surface-exposed lipoproteins.

Human gut Bacteroides use surface-exposed lipoproteins to bind and metabolize complex polysaccharides. Although vitamins and other nutrients are also essential for commensal fitness, much less is known about how commensal bacteria compete with each other or the host for these critical resources. Unlike in Escherichia coli, transport loci for vitamin B12 (cobalamin) and other corrinoids in human gut Bacteroides are replete with conserved genes encoding proteins whose functions are unknown. Here we report that one of these proteins, BtuG, is a surface-exposed lipoprotein that is essential for efficient B12 transport in B. thetaiotaomicron. BtuG binds B12 with femtomolar affinity and can remove B12 from intrinsic factor, a critical B12 transport protein in humans. Our studies suggest that Bacteroides use surface-exposed lipoproteins not only for capturing polysaccharides, but also to acquire key vitamins in the gut

Endochin-like quinolones (ELQs) and bumped kinase inhibitors (BKIs): Synergistic and additive effects of combined treatments against Neospora caninum infection in vitro and in vivo.

The apicomplexan parasite Neospora caninum is an important causative agent of congenital neosporosis, resulting in abortion, birth of weak offspring and neuromuscular disorders in cattle, sheep, and many other species. Among several compound classes that are currently being developed, two have been reported to limit the effects of congenital neosporosis: (i) bumped kinase inhibitors (BKIs) target calcium dependent protein kinase 1 (CDPK1), an enzyme that is encoded by an apicoplast-derived gene and found only in apicomplexans and plants. CDPK1 is essential for host cell invasion and egress; (ii) endochin-like quinolones (ELQs) are inhibitors of the cytochrome bc1 complex of the mitochondrial electron transport chain and thus inhibit oxidative phosphorylation. We here report on the in vitro and in vivo activities of BKI-1748, and of ELQ-316 and its respective prodrugs ELQ-334 and ELQ-422, applied either as single-compounds or ELQ-BKI-combinations. In vitro, BKI-1748 and ELQ-316, as well as BKI-1748 and ELQ-334, acted synergistically, while this was not observed for the BKI-1748/ELQ-422 combination treatment. In a N. caninum-infected pregnant BALB/c mouse model, the synergistic effects observed in vitro were not entirely reproduced, but 100% postnatal survival and 100% inhibition of vertical transmission was noted in the group treated with the BKI-1748/ELQ-334 combination. In addition, the combined drug applications resulted in lower neonatal mortality compared to treatments with single drugs

Infected Cell Killing by HIV-1 Protease Promotes NF-κB Dependent HIV-1 Replication

Acute HIV-1 infection of CD4 T cells often results in apoptotic death of infected cells, yet it is unclear what evolutionary advantage this offers to HIV-1. Given the independent observations that acute T cell HIV-1 infection results in (1) NF-κB activation, (2) caspase 8 dependent apoptosis, and that (3) caspase 8 directly activates NF-κB, we questioned whether these three events might be interrelated. We first show that HIV-1 infected T cell apoptosis, NF-κB activation, and caspase 8 cleavage by HIV-1 protease are coincident. Next we show that HIV-1 protease not only cleaves procaspase 8, producing Casp8p41, but also independently stimulates NF-κB activity. Finally, we demonstrate that the HIV protease cleavage of caspase 8 is necessary for optimal NF-κB activation and that the HIV-1 protease specific cleavage fragment Casp8p41 is sufficient to stimulate HIV-1 replication through NF-κB dependent HIV-LTR activation both in vitro as well as in cells from HIV infected donors. Consequently, the molecular events which promote death of HIV-1 infected T cells function dually to promote HIV-1 replication, thereby favoring the propagation and survival of HIV-1

Direct evidence for cancer-cell-autonomous extracellular protein catabolism in pancreatic tumors

Mammalian tissues rely on a variety of nutrients to support their physiological functions. It is known that altered metabolism is involved in the pathogenesis of cancer, but which nutrients support the inappropriate growth of intact malignant tumors is incompletely understood. Amino acids are essential nutrients for many cancer cells that can be obtained through the scavenging and catabolism of extracellular protein via macropinocytosis. In particular, macropinocytosis can be a nutrient source for pancreatic cancer cells, but it is not fully understood how the tumor environment influences metabolic phenotypes and whether macropinocytosis supports the maintenance of amino acid levels within pancreatic tumors. Here we utilize miniaturized plasma exchange to deliver labeled albumin to tissues in live mice, and we demonstrate that breakdown of albumin contributes to the supply of free amino acids in pancreatic tumors. We also deliver albumin directly into tumors using an implantable microdevice, which was adapted and modified from ref. 9. Following implantation, we directly observe protein catabolism and macropinocytosis in situ by pancreatic cancer cells, but not by adjacent, non-cancerous pancreatic tissue. In addition, we find that intratumoral inhibition of macropinocytosis decreases amino acid levels. Taken together, these data suggest that pancreatic cancer cells consume extracellular protein, including albumin, and that this consumption serves as an important source of amino acids for pancreatic cancer cells in vivo.National Science Foundation (U.S.) (Grant T32GM007287)National Cancer Institute (U.S.) (Grant F30CA183474)National Institute of General Medical Sciences (U.S.) (Award T32GM007753)National Institutes of Health (U.S.) (Grant P30CA1405141)National Institutes of Health (U.S.) (Grant R01CA168653

A short-term treatment with BKI-1294 does not protect foetuses from sheep experimentally infected with Neospora caninum tachyzoites during pregnancy.

The Neospora caninum Calcium-dependent protein kinase 1 (NcCDPK1) inhibitor BKI-1294 had demonstrated excellent efficacy in a pregnant mouse model of neosporosis, and was also highly efficacious in a pregnant sheep model of toxoplasmosis. In this work, we present the efficacy of BKI-1294 treatment (dosed 5 times orally every 48 h) starting 48 h after intravenous infection of sheep with 105 Nc-Spain7 tachyzoites at mid-pregnancy. In the dams, BKI-1294 plasma concentrations were above the IC50 for N. caninum for 12-15 days. In treated sheep, when they were compared to untreated ones, we observed a minor increase in rectal temperature, higher IFNγ levels after blood stimulation in vitro, and a minor increase of IgG levels against N. caninum soluble antigens through day 28 post-infection. Additionally, the anti-NcSAG1 and anti-NcSAG4 IgGs were lower in treated dams on days 21 and 42 post-infection. However, BKI-1294 did not protect against abortion (87% foetal mortality in both infected groups, treated and untreated) and did not reduce transplacental transmission, parasite load or lesions in placentomes and foetal brain. The lack of foetal protection was likely caused by short systemic exposure in the dams and suboptimal foetal exposure to this parasitostatic drug, which was unable to reduce replication of the likely established N. caninum tachyzoites in the foetus at the moment of treatment. New BKIs with a very low plasma clearance and good ability to cross the blood-brain and placental barriers need to be developed

The Significance of African Lions for the Financial Viability of Trophy Hunting and the Maintenance of Wild Land

Recent studies indicate that trophy hunting is impacting negatively on some lion populations, notably in Tanzania. In 2004 there was a proposal to list lions on CITES Appendix I and in 2011 animal-welfare groups petitioned the United States government to list lions as endangered under their Endangered Species Act. Such listings would likely curtail the trophy hunting of lions by limiting the import of lion trophies. Concurrent efforts are underway to encourage the European Union to ban lion trophy imports. We assessed the significance of lions to the financial viability of trophy hunting across five countries to help determine the financial impact and advisability of the proposed trade restrictions. Lion hunts attract the highest mean prices (US$24,000–US$71,000) of all trophy species. Lions generate 5–17% of gross trophy hunting income on national levels, the proportional significance highest in Mozambique, Tanzania, and Zambia. If lion hunting was effectively precluded, trophy hunting could potentially become financially unviable across at least 59,538 km2 that could result in a concomitant loss of habitat. However, the loss of lion hunting could have other potentially broader negative impacts including reduction of competitiveness of wildlife-based land uses relative to ecologically unfavourable alternatives. Restrictions on lion hunting may also reduce tolerance for the species among communities where local people benefit from trophy hunting, and may reduce funds available for anti-poaching. If lion off-takes were reduced to recommended maximums (0.5/1000 km2), the loss of viability and reduction in profitability would be much lower than if lion hunting was stopped altogether (7,005 km2). We recommend that interventions focus on reducing off-takes to sustainable levels, implementing age-based regulations and improving governance of trophy hunting. Such measures could ensure sustainability, while retaining incentives for the conservation of lions and their habitat from hunting

HIV gp120 Induces, NF-κB Dependent, HIV Replication that Requires Procaspase 8

HIV envelope glycoprotein gp120 causes cellular activation resulting in anergy, apoptosis, proinflammatory cytokine production, and through an unknown mechanism, enhanced HIV replication.We describe that the signals which promote apoptosis are also responsible for the enhanced HIV replication. Specifically, we demonstrate that the caspase 8 cleavage fragment Caspase8p43, activates p50/p65 Nuclear Factor kappaB (NF-kappaB), in a manner which is inhibited by dominant negative IkappaBalpha. This caspase 8 dependent NF-kappaB activation occurs following stimulation with gp120, TNF, or CD3/CD28 crosslinking, but these treatments do not activate NF-kappaB in cells deficient in caspase 8. The Casp8p43 cleavage fragment also transactivates the HIV LTR through NF-kappaB, and the absence of caspase 8 following HIV infection greatly inhibits HIV replication.Gp120 induced caspase 8 dependent NF-kappaB activation is a novel pathway of HIV replication which increases understanding of the biology of T-cell death, as well as having implications for understanding treatment and prevention of HIV infection