Drosophila Helical factor is an inducible protein acting as an immune-regulated cytokine in S2 cells

The innate immunity of Drosophila melanogaster is based on cellular and humoral components. Drosophila Helical factor (Hf), is a molecule previously discovered using an in silico approach and whose expression is controlled by the immune deficiency (Imd) pathway. Here we present evidence demonstrating that Hf is an inducible protein constitutively produced by the S2 hemocyte-derived cell line. Hf expression is stimulated by bacterial extracts that specifically trigger the Imd pathway. In absence of any bacterial challenge, the recombinant form of Hf can influence the expression of the antimicrobial peptides (AMPs) defensin but not drosomycin. These data suggest that in vitro Hf is an inducible and immune-regulated factor, with functions comparable to those of secreted vertebrate cytokines.     

Why the stroma matters in breast cancer: Insights into breast cancer patient outcomes through the examination of stromal biomarkers

Survival and recurrence rates in breast cancer are variable for common diagnoses, and therefore the biological underpinnings of the disease that determine those outcomes are yet to be fully understood. As a result, translational medicine is one of the fastest growing arenas of study in tumor biology. With advancements in genetic and imaging techniques, archived biopsies can be examined for purposes other than diagnosis. There is a great deal of evidence that points to the stroma as the major regulator of tumor progression following the initial stages of tumor formation, and the stroma may also contribute to risk factors determining tumor formation. Therefore, aspects of stromal biology are well-suited to be a focus for studies of patient outcome, where statistical differences in survival among patients provide evidence as to whether that stromal component is a signpost for tumor progression. In this review we summarize the latest research done where breast cancer patient survival was correlated with aspects of stromal biology, which have been put into four categories: reorganization of the extracellular matrix (ECM) to promote invasion, changes in the expression of stromal cell types, changes in stromal gene expression, and changes in cell biology signaling cascades to and from the stroma.     

Toward using δ13C of ecosystem respiration to monitor canopy physiology in complex terrain

In 2005 and 2006, air samples were collected at the base of a Douglas-fir watershed to monitor seasonal changes in the delta13CO2 of ecosystem respiration (delta13C(ER)). The goals of this study were to determine whether variations in delta13C(ER) correlated with environmental variables and could be used to predict expected variations in canopy-average stomatal conductance (Gs). Changes in delta13C(ER) correlated weakly with changes in vapor pressure deficit (VPD) measured 0 and 3-7 days earlier and significantly with soil matric potential (psi(m)) (P value <0.02) measured on the same day. Midday G (s) was estimated using sapflow measurements (heat-dissipation method) at four plots located at different elevations within the watershed. Values of midday Gs from 0 and 3-7 days earlier were correlated with delta13C(ER), with the 5-day lag being significant (P value <0.05). To examine direct relationships between delta13C(ER) and recent Gs, we used models relating isotope discrimination to stomatal conductance and photosynthetic capacity at the leaf level to estimate values of stomatal conductance ("Gs-I") that would be expected if respired CO2 were derived entirely from recent photosynthate. We compared these values with estimates of Gs using direct measurement of transpiration at multiple locations in the watershed. Considering that the approach based on isotopes considers only the effect of photosynthetic discrimination on delta13C(ER), the magnitude and range in the two values were surprisingly similar. We conclude that: (1) delta13C(ER) is sensitive to variations in weather, and (2) delta13C(ER) potentially could be used to directly monitor average, basin-wide variations in Gs in complex terrain if further research improves understanding of how delta13C(ER) is influenced by post-assimilation fractionation processes.     

The spindle assembly checkpoint is satisfied in the absence of interkinetochore tension during mitosis with unreplicated genomes

The accuracy of chromosome segregation is enhanced by the spindle assembly checkpoint (SAC). The SAC is thought to monitor two distinct events: attachment of kinetochores to microtubules and the stretch of the centromere between the sister kinetochores that arises only when the chromosome becomes properly bioriented. We examined human cells undergoing mitosis with unreplicated genomes (MUG). Kinetochores in these cells are not paired, which implies that the centromere cannot be stretched; however, cells progress through mitosis. A SAC is present during MUG as cells arrest in response to nocodazole, taxol, or monastrol treatments. Mad2 is recruited to unattached MUG kinetochores and released upon their attachment. In contrast, BubR1 remains on attached kinetochores and exhibits a level of phosphorylation consistent with the inability of MUG spindles to establish normal levels of centromere tension. Thus, kinetochore attachment to microtubules is sufficient to satisfy the SAC even in the absence of interkinetochore tension.     

Effect of electrical stimulation of the LES on LES pressure in a canine model

Gastric electrical stimulation modulates lower esophageal sphincter pressure (LESP). High-frequency neural stimulation (NES) can induce gut smooth muscle contractions. To determine whether lower esophageal sphincter (LES) electrical stimulation (ES) can affect LESP, bipolar electrodes were implanted in the LES of four dogs. Esophageal manometry during sham or ES was performed randomly on separate days. Four stimuli were used: 1) low-frequency: 350-ms pulses at 6 cycles/min; 2) high-frequency-1: 1-ms pulses at 50 Hz; 3) high-frequency-2: 1-ms pulses at 20 Hz; and 4) NES: 20-ms bipolar pulses at 50 Hz. Recordings were obtained postprandially. Tests consisted of three 20-min periods: baseline, stimulation/sham, and poststimulation. The effect of NES was tested under anesthesia and following IV administration of l-NAME and atropine. Area under the curve (AUC) and LESP were compared among the three periods, by ANOVA and t-test, P < 0.05. Data are shown as means +/- SD. We found that low-frequency stimulation caused a sustained increase in LESP: 32.1 +/- 12.9 (prestimulation) vs. 43.2 +/- 18.0 (stimulation) vs. 50.1 +/- 23.8 (poststimulation), P < 0.05. AUC significantly increased during and after stimulation. There were no significant changes with other types of ES. With NES, LESP initially rose and then decreased below baseline (LES relaxation). During NES, N(G)-nitro-l-arginine methyl ester increased both resting LESP and the initial rise in LESP and markedly diminished the relaxation. Atropine lowered resting LESP and abolished the initial rise in LESP. In conclusion, low frequency ES of the LES increases LESP in conscious dogs. NES has dual effect on LESP: an initial stimulation, cholinergically mediated, followed by relaxation mediated by nitric oxide.     

Effects of herbivory, nutrient levels, and introduced algae on the distribution and abundance of the invasive macroalga Dictyosphaeria cavernosa in Kaneohe Bay, Hawaii

Since the 1960s, and possibly earlier, the macroalga Dictyosphaeria cavernosa has overgrown and displaced corals on reef slopes and outer reef flats in Kaneohe Bay, Oahu. This shift in reef community composition is generally attributed to nutrient enrichment resulting from sewage discharge. Following the diversion of most of the sewage effluent in 1977-1978, it was expected that D. cavernosa growth would become nutrient-limited and its abundance would consequently decline, but the alga remains abundant in much of the bay. One explanation for its persistence is that nutrients are once again high enough to support the alga's growth. An alternative explanation is that there has been a reduction in grazing intensity in the bay. In this study we resurveyed the distribution and abundance of D. cavernosa at 120 reef slope sites originally surveyed in 1969. We conducted additional surveys to estimate the biomass of herbivores and the areal coverage of D. cavernosa and other macroalgae on reef slopes and flats. Field experiments were used to determine spatial and temporal patterns of grazing intensity on and growth rates of D. cavernosa and the introduced macroalga Acanthophora spicifera. Laboratory experiments were used to examine preferences among herbivores for some of the most abundant macroalgae on Kaneohe Bay reefs. Twenty years after sewage diversion, D. cavernosa cover on reef slopes has decreased substantially in southern Kaneohe Bay, the site of most of the historical sewage discharge. D. cavernosa cover has changed less in other regions, remaining high in the central bay and low in the north bay. D. cavernosa thalli protected by grazer exclusion cages sustained positive growth rates on reef slopes and flats throughout the bay. Reduced nutrient concentrations may have caused a reduction in D. cavernosa growth rates, and a consequent reduction in D. cavernosa abundance in the south bay shortly after sewage diversion. Measurements of grazing intensity and surveys of herbivorous fish abundance suggest that the continued abundance of D. cavernosa is the result of a reduction in grazing intensity. Reduced grazing intensity on D. cavernosa may in turn be the result of a historical reduction in herbivore biomass or the establishment of several introduced macroalgae on reef flats. The introduced species are preferred by herbivorous fishes over D. cavernosa, as indicated by preference tests. The hypothesis that reduced grazing pressure on D. cavernosa is related to the establishment of introduced species is supported by the observation that D. cavernosa cover is highest on reef slopes where the cover of preferred introduced macroalgae on the adjacent outer reef flat is also high. Conversely, D. cavernosa cover is low or zero on reef slopes where the cover of introduced macroalgae on the adjacent reef flat is low or zero