GDF‐9 promotes the growth of prostate cancer cells by protecting them from apoptosis

Bone morphogenetic proteins (BMPs) have long been implicated in the process of prostate cancer progression and bone metastasis. This current study investigates the role of GDF‐9, a BMP member, in prostate cancer. GDF‐9 was over‐expressed in PC‐3 cells using a mammalian expression construct. Additionally, GDF‐9 ribozyme transgenes were generated in order to knock down the expression of GDF‐9 in PC‐3 and DU‐145 cells. These cells were then used in in vitro growth assays in order to determine the effect of GDF‐9 on prostate cancer cell growth. Recombinant GDF‐9 was also generated and used to treat both cell lines before carrying out further growth assays. Levels of apoptosis were subsequently analyzed using flow cytometry. Cell growth was significantly increased in the GDF‐9 over‐expressing cells compared to the two controls. The cell growth rate at day 5 was significantly greater in the PC‐3^GDF‐9exp. (1,131.1 ± 79.1%) compared to both PC‐3^WT (563.9 ± 90.6%) and PC‐3^pEF (763.3 ± 82.0%), P ≤ 0.001 versus both controls. The opposite effect was seen in both PC‐3 and DU‐145 GDF‐9 knockdown cells. The PC‐3^WT cells treated with rh‐GDF‐9 (1.35 ± 0.28) had a significantly increased absorbance and hence growth rate compared to the untreated PC‐3 cells (0.79 ± 0.05), P = 0.026. Finally, flow cytometry and Hoechst 33342 DNA staining demonstrated decreased apoptosis and caspase‐3 expression levels in PC‐3^GDF‐9exp. cells and rh‐GDF‐9‐treated PC‐3^WT cells. This study shows that GDF‐9 can promote the growth rate of both PC‐3 and DU‐145 cells by protecting the cells from caspase‐3‐mediated apoptosis, and suggests that GDF‐9 may aid in the progression of prostate cancer by acting as a survival factor. J. Cell. Physiol. 225: 529–536, 2010. © 2010 Wiley‐Liss, Inc.     

Uterine peristalsis-induced stresses within the uterine wall may sprout adenomyosis

Adenomyosis is a disease in which ectopic endometrial glands and stromal cells appear in the uterine myometrium. This pathology is common among women of reproductive age, and in addition to chronic pelvic pain and heavy periods it may also cause infertility. The ‘tissue injury and repair’ mechanism in response to increased intrauterine pressures was proposed as the etiology for migration of fragments of basal endometrium into the myometrial wall. In order to investigate this mechanism, a conceptual two-dimensional model of the uterine wall subjected to intrauterine pressures was implemented using ADINA commercial software. The stress field within the uterine wall was examined for a variety of intrauterine sinusoidal pressure waves with varying frequencies. The results revealed that: (1) as the wavelength of the subjected pressure wave decreased, high concentration of stresses developed near the inner uterine cavity; (2) as the pressure wave frequency increased, high gradients of the stresses were obtained; (3) at menstrual phase, the highest stresses obtained at the endometrial–myometrial interface. Therefore, increased uterine activity results in high stresses which may lead to tissue lesions and detachment of endometrial cells.     

Methanogens rapidly transition from methane production to iron reduction

Methanogenesis, the microbial methane (CH₄) production, is traditionally thought to anchor the mineralization of organic matter as the ultimate respiratory process in deep sediments, despite the presence of oxidized mineral phases, such as iron oxides. This process is carried out by archaea that have also been shown to be capable of reducing iron in high levels of electron donors such as hydrogen. The current pure culture study demonstrates that methanogenic archaea (Methanosarcina barkeri) rapidly switch from methanogenesis to iron‐oxide reduction close to natural conditions, with nitrogen atmosphere, even when faced with substrate limitations. Intensive, biotic iron reduction was observed following the addition of poorly crystalline ferrihydrite and complex organic matter and was accompanied by inhibition of methane production. The reaction rate of this process was of the first order and was dependent only on the initial iron concentrations. Ferrous iron production did not accelerate significantly with the addition of 9,10‐anthraquinone‐2,6‐disulfonate (AQDS) but increased by 11–28% with the addition of phenazine‐1‐carboxylate (PCA), suggesting the possible role of methanophenazines in the electron transport. The coupling between ferrous iron and methane production has important global implications. The rapid transition from methanogenesis to reduction of iron–oxides close to the natural conditions in sediments may help to explain the globally‐distributed phenomena of increasing ferrous concentrations below the traditional iron reduction zone in the deep ‘methanogenic’ sediment horizon, with implications for metabolic networking in these subsurface ecosystems and in past geological settings.     

Dynamics of Fst for the island model

F(st) is a measure of genetic differentiation in a subdivided population. Sewall Wright observed that F(st)=1/1+2Nm in a haploid diallelic infinite island model, where N is the effective population size of each deme and m is the migration rate. In demonstrating this result, Wright relied on the infinite size of the population. Natural populations are not infinite and therefore they change over time due to genetic drift. In a finite population, F(st) becomes a random variable that evolves over time. In this work we ask, given an initial population state, what are the dynamics of the mean and variance of F(st) under the finite island model? In application both of these quantities are critical in the evaluation of F(st) data. We show that after a time of order N generations the mean of F(st) is slightly biased below 1/1+2Nm. Further we show that the variance of F(st) is of order 1/d where d is the number of demes in the population. We introduce several new mathematical techniques to analyze coalescent genealogies in a dynamic setting.     

INTRASPECIFIC TRANSFER OF HERBICIDE RESISTANCE IN THE RED MICROALGA PORPHYRIDIUM SP. (RHODOPHYCEAE) VIA PROTOPLAST FUSION

Stable progeny doubly resistant to the herbicides sulfometuron methyl (SMM) and diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] (DCMU) were obtained at a frequency of 2% on fusion of protoplasts derived from mutants of Porphyridium sp. (UTEX 637) that were resistant only to SMM (strain SMR) or DCMU (strain DC-2). In the presence of both herbicides, only the fusion progeny could grow; both parental mutants were inhibited. In the absence of SMM, the activity of acetohydroxy acid synthase (AHAS) in the wild-type strain was similar to that in DC-2, exceeding that of SMR by up to 4.5-fold. AHAS activities of all fusion progeny were lower than those of the wild-type strain and DC-2 but higher than that of SMR. In the presence of SMM, AHAS activities of all tested fusion progeny ranged between those of the two parental mutants. This result indicates that both types of AHAS, the type resistant to SMM and the sensitive type, originating from SMR and DC-2, respectively, were expressed in the fusion progeny. In the presence of DCMU, the photosynthetic activity of SMR was completely inhibited, whereas that of DC-2 was unaffected. The photosynthetic activity of the fusion progeny in the presence of DCMU was slightly lower than that of DC-2. Both the cell volume and the DNA content of the fusion progeny were similar to those of the parents. However, the genetic nature of the fusion products has not yet been elucidated. To the best of our knowledge, this is the first report on transfer of herbicide resistance via protoplast fusion in algae.     

Identification of chironomid species as natural reservoirs of toxigenic Vibrio cholerae strains with pandemic potential

Vibrio cholerae causes the fatal cholera diarrhea. Chironomids (Diptera; Chironomidae) are abundant in freshwater aquatic habitats and estuaries and are natural reservoirs of V. cholerae. Until now, only the non-O1/O139 serogroups of V. cholerae were identified in chironomids. Here, we explored whether chironomids are natural reservoirs of V. cholerae O1/O139 serogroups, which are associated with cholera endemics and pandemics. All four life stages of chironomids were sampled from two rivers, and a laboratory culture in Pune, India, and from a pond in Israel. In total, we analyzed 223 chironomid samples. The presence of V. cholerae O1/O139 serogroups was verified using molecular tools. Nine chironomid species were identified; of them, Chironomus circumdatus was the most abundant. The presence of V. cholerae serogroup O1 and the cholera toxin genes were detected in samples from all chironomid species. However, serogroup O139 was detected in only two chironomid species. Besides PCR to detect specific genes, a metagenomic analysis that was performed in three selected C. ramosus larvae, identified a list of virulence genes associated with V. cholerae. The findings provide evidence that chironomids are natural reservoirs of toxigenic V. cholerae O1/O139. Chironomid populations and V. cholerae show biannual peak patterns. A similar pattern is found for cholera epidemics in the Bengal Delta region. Thus, we hypothesize that monitoring chironomids in endemic areas of the disease may provide a novel tool for predicting and preventing cholera epidemics. Moreover, serogroup O139 was detected only in two chironomid species that have a restricted distribution in the Indian subcontinent, possibly explaining why the distribution of the O139 serogroup is limited.     

Antifibrotic action of Cu/Zn SOD is mediated by TGF-beta1 repression and phenotypic reversion of myofibroblasts

Skin fibrosis is characterized by the proliferation and accumulation of activated fibroblasts called myofibroblasts. They exhibit specific cytoskeletal differentiation, overexpress the fibrogenic cytokine TGF-beta1, synthesize excess extracellular matrix compounds and exhibit a depleted antioxidant metabolism. Recently, SOD was successfully used as an antifibrotic agent in vivo, thus challenging the postulate of established fibrosis irreversibility. We postulated that myofibroblasts could be a direct target for this therapeutic effect. To test this hypothesis, we used three-dimensional co-culture models of skin, in which specific phenotypes of normal fibroblasts versus myofibroblasts are retained. These 3-D models were treated with liposomal and carrier-free Cu/Zn SOD, and examined for their effects on cell number, cell death, and phenotypic differentiation. The results show that SOD did not induce myofibroblast cell death, whereas it significantly reduced TGF-beta1 expression, thus demonstrating that SOD might be proposed as a potent antagonist of this major fibrogenic growth factor. We also found that SOD significantly lowered the levels of the myofibroblast marker alpha-sm actin, of beta-actin, and of the extracellular matrix components alpha1(I) collagen and tenascin-C. In conclusion, our results suggest that SOD antifibrotic action occurred in vitro through the reversion of myofibroblasts into normal fibroblasts.     

Biofilm production by clinical strains of Acinetobacter baumannii isolated from patients hospitalized in two tertiary care hospitals

Microbial biofilms are considered as virulence factors. During the present study, 34 clinical strains of Acinetobacter baumannii, isolated from patients hospitalized in two tertiary care hospitals, were examined for biofilm formation. These strains showed high variability in biofilm formation. Furthermore, no relation could be found between the ability of biofilm production and molecular type, carbapenem resistance, site of isolation of the clinical strains of A. baumannii and disease severity. Interestingly, in two cases an increase in biofilm formation could be detected in A. baumannii isolates cultured from the same patient upon prolonged hospitalization.     

The effect of a moving foveal target on the subjective sensation of motion

In this paper, we report on two experiments concerning the effect of the visual field of fovea on the subjective estimation of angular velocity. Experiment 1 investigates the effect of a slow moving target on the perception of self motion. The result of this experiment can be summarized as follows: a slow moving target seen in the visual field of fovea by a stationary person generates in this person a sensation of self rotation in the same direction as the motion of the target. This phenomenon will be called foveal induced ego motion. Experiment 2 investigates the latency for the detection of a self angular acceleration when the person focusses his fovea on a slowly moving target. From the results of this experiment we conclude that the latency for detection of a small self angular acceleration is shorter if the person sees a small foveal target moving with respect to the person in the direction of self rotation than if that small foveal target is moving (with respect to the person) in the opposite direction. The results of these experiments help us in refining existing models of visual-vestibular interaction, by providing a model which accounts for the phenomenon of oculogyral illusion.This research was conducted while serving as a Visiting Professor at the Man Vehicle Laboratory, Department of Aeronautics and Astronautics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA