Size-Frequency Distributions along a Latitudinal Gradient in Middle Permian Fusulinoideans

Geographic gradients in body size within and among living species are commonly used to identify controls on the long-term evolution of organism size. However, the persistence of these gradients over evolutionary time remains largely unknown because ancient biogeographic variation in organism size is poorly documented. Middle Permian fusulinoidean foraminifera are ideal for investigating the temporal persistence of geographic gradients in organism size because they were diverse and abundant along a broad range of paleo-latitudes during this interval (∼275–260 million years ago). In this study, we determined the sizes of Middle Permian fusulinoidean fossils from three different paleo-latitudinal zones in order to examine the relationship between the size of foraminifers and regional environment. We recovered the following results: keriothecal fusulinoideans are substantially larger than nonkeriothecal fusulinoideans; fusulinoideans from the equatorial zone are typically larger than those from the north and south transitional zones; neoschwagerinid specimens within a single species are generally larger in the equatorial zone than those in both transitional zones; and the nonkeriothecal fusulinoideans Staffellidae and Schubertellidae have smaller size in the north transitional zone. Fusulinoidean foraminifers differ from most other marine taxa in exhibiting larger sizes closer to the equator, contrary to Bergmann's rule. Meridional variation in seasonality, water temperature, nutrient availability, and carbonate saturation level are all likely to have favored or enabled larger sizes in equatorial regions. Temporal variation in atmospheric oxygen concentrations have been shown to account for temporal variation in fusulinoidean size during Carboniferous and Permian time, but oxygen availability appears unlikely to explain biogeographic variation in fusulinoidean sizes, because dissolved oxygen concentrations in seawater typically increase away from the equator due to declining seawater temperatures. Consequently, our findings highlight the fact that spatial gradients in organism size are not always controlled by the same factors that govern temporal trends within the same clade

Constitutive and cytokine-induced expression of the ETS transcription factor ESE-3 in the lung.

Family studies of asthma suggest that the genes ESE-2 and ESE-3 contain polymorphisms that contribute to disease susceptibility. Each gene codes for an ETS transcription factor that is characterized by epithelium-restricted constitutive expression and may function as a context-dependent activator or repressor of transcription; however, nothing is known about the role of these genes in lung homeostasis or the pathogenesis of airway disease. In this study, we show that ESE-3 mRNA and protein are constitutively expressed in bronchial and mucous gland epithelial cells. Consistent with these findings, ESE-3 mRNA is constitutively expressed in human bronchial epithelial cells grown in tissue culture. In contrast, ESE-2 mRNA could not be detected in the lung or cultured human bronchial epithelial cells. Human bronchial smooth muscle cells and fibroblasts do not constitutively express ESE-3; however, after stimulation with interleukin-1beta or tumor necrosis factor-alpha, levels of ESE-3 mRNA and protein increase dramatically by 24 h. This cytokine induction is dose-dependent and abrogated by specific inhibitors of the MEK1/2 (U0126) and p38 (SB03580) signal transduction pathways. Overexpression of ESE-3 protein in 3T3 cells and human bronchial smooth muscle cells inhibits MMP-1 promoter activity, suggesting that ESE-3 may function as a transcriptional repressor

Discovery and structures of the cyclotides: novel macrocyclic peptides from plants

Circular disulfide-rich polypeptides were unknown a decade ago but over recent years a large family of such molecules has been discovered, which we now refer to as the cyclotides. They are typically about 30 amino acids in size, contain an N- to C-cyclised backbone and incorporate three disulfide bonds arranged in a cystine knot motif. In this motif, an embedded ring in the structure formed by two disulfide bonds and their connecting backbone segments is penetrated by the third disulfide bond. The combination of this knotted and strongly braced structure with a circular backbone renders the cyclotides impervious to enzymatic breakdown and makes them exceptionally stable. This article describes the discovery of the cyclotides in plants from the Rubiaceae and Violaceae families, their chemical synthesis, folding, structural characterisation, and biosynthetic origin. The cyclotides have a diverse range of biological applications, ranging from uterotonic action, to anti-HIV and neurotensin antagonism. Certain plants from which they are derived have a history of uses in native medicine, with activity being observed after oral ingestion of a tea made from the plants. This suggests the possibility that the cyclotides may be orally bioavailable. They therefore have a range of potential applications as a stable peptide framework