Environmental Costs of Government-Sponsored Agrarian Settlements in Brazilian Amazonia

Brazil has presided over the most comprehensive agrarian reform frontier colonization program on Earth, in which ~1.2 million settlers have been translocated by successive governments since the 1970's, mostly into forested hinterlands of Brazilian Amazonia. These settlements encompass 5.3% of this ~5 million km2 region, but have contributed with 13.5% of all land conversion into agropastoral land uses. The Brazilian Federal Agrarian Agency (INCRA) has repeatedly claimed that deforestation in these areas largely predates the sanctioned arrival of new settlers. Here, we quantify rates of natural vegetation conversion across 1911 agrarian settlements allocated to 568 Amazonian counties and compare fire incidence and deforestation rates before and after the official occupation of settlements by migrant farmers. The timing and spatial distribution of deforestation and fires in our analysis provides irrefutable chronological and spatially explicit evidence of agropastoral conversion both inside and immediately outside agrarian settlements over the last decade. Deforestation rates are strongly related to local human population density and road access to regional markets. Agrarian settlements consistently accelerated rates of deforestation and fires, compared to neighboring areas outside settlements, but within the same counties. Relocated smallholders allocated to forest areas undoubtedly operate as pivotal agents of deforestation, and most of the forest clearance occurs in the aftermath of government-induced migration

Ecological implications of a flower size/number trade-off in tropical forest trees

Peer reviewedPublisher PD

Non-Native R1 Substitution in the S4 Domain Uniquely Alters Kv4.3 Channel Gating

The S4 transmembrane domain in Shaker (Kv1) voltage-sensitive potassium channels has four basic residues (R1–R4) that are responsible for carrying the majority of gating charge. In Kv4 channels, however, R1 is replaced by a neutral valine at position 287. Among other differences, Kv4 channels display prominent closed state inactivation, a mechanism which is minimal in Shaker. To determine if the absence of R1 is responsible for important variation in gating characteristics between the two channel types, we introduced the V287R mutant into Kv4.3 and analyzed its effects on several voltage sensitive gating transitions. We found that the mutant increased the voltage sensitivity of steady-state activation and altered the kinetics of activation and deactivation processes. Although the kinetics of macroscopic inactivation were minimally affected, the characteristics of closed-state inactivation and recovery from open and closed inactivated states were significantly altered. The absence of R1 can only partially account for differences in the effective voltage sensitivity of gating between Shaker and Kv4.3. These results suggest that the S4 domain serves an important functional role in Kv4 channel activation and deactivation processes, and also those of closed-state inactivation and recovery

Enhancing Egress Drills: Preparation and Assessment of Evacuee Performance

This article explores how egress drills-specifically those related to fire incidents-are currently used, their impact on safety levels, and the insights gained from them. It is suggested that neither the merits of egress drills are well understood, nor the impact on egress performance well characterized. In addition, the manner in which they are conducted varies both between and within regulatory jurisdictions. By investigating their strengths and limitations, this article suggests opportunities for their enhancement possibly through the use of other egress models to support and expand upon the benefits provided. It is by no means suggested that drills are not important to evacuation safety-only that their inconsistent use and the interpretation of the results produced may mean we (as researchers, practitioners, regulators, and stakeholders) are not getting the maximum benefit out of this important tool

Roles of the Amino Terminal Region and Repeat Region of the Plasmodium berghei Circumsporozoite Protein in Parasite Infectivity

The circumsporozoite protein (CSP) plays a key role in malaria sporozoite infection of both mosquito salivary glands and the vertebrate host. The conserved Regions I and II have been well studied but little is known about the immunogenic central repeat region and the N-terminal region of the protein. Rodent malaria Plasmodium berghei parasites, in which the endogenous CS gene has been replaced with the avian Plasmodium gallinaceum CS (PgCS) sequence, develop normally in the A. stephensi mosquito midgut but the sporozoites are not infectious. We therefore generated P. berghei transgenic parasites carrying the PgCS gene, in which the repeat region was replaced with the homologous region of P. berghei CS (PbCS). A further line, in which both the N-terminal region and repeat region were replaced with the homologous regions of PbCS, was also generated. Introduction of the PbCS repeat region alone, into the PgCS gene, did not rescue sporozoite species-specific infectivity. However, the introduction of both the PbCS repeat region and the N-terminal region into the PgCS gene completely rescued infectivity, in both the mosquito vector and the mammalian host. Immunofluorescence experiments and western blot analysis revealed correct localization and proteolytic processing of CSP in the chimeric parasites. The results demonstrate, in vivo, that the repeat region of P. berghei CSP, alone, is unable to mediate sporozoite infectivity in either the mosquito or the mammalian host, but suggest an important role for the N-terminal region in sporozoite host cell invasion

Physiological roles for ecto-5’-nucleotidase (CD73)

Nucleotides and nucleosides influence nearly every aspect of physiology and pathophysiology. Extracellular nucleotides are metabolized through regulated phosphohydrolysis by a series of ecto-nucleotidases. The formation of extracellular adenosine from adenosine 5’-monophosphate is accomplished primarily through ecto-5’-nucleotidase (CD73), a glycosyl phosphatidylinositol-linked membrane protein found on the surface of a variety of cell types. Recent in vivo studies implicating CD73 in a number of tissue protective mechanisms have provided new insight into its regulation and function and have generated considerable interest. Here, we review contributions of CD73 to cell and tissue stress responses, with a particular emphasis on physiologic responses to regulated CD73 expression and function, as well as new findings utilizing Cd73-deficient animals