Triggers of phytoplankton bloom dynamics in permanently eutrophic waters of a South African estuary

The permanently eutrophic Sundays Estuary experiences recurrent harmful algal blooms (HABs) of Heterosigma akashiwo (Raphidophyceae). This study aimed to identify the environmental variables shaping phytoplankton community composition and succession patterns during a typical spring/summer harmful algal bloom (HAB) period. Monitoring of abiotic and phytoplankton variables was undertaken over the period of a month in 2016. Surface water salinity corresponding to mesohaline conditions (9 to 12) was a prerequisite for site selection. During the study, two HABs (>550 µg Chl a l^?1) of H. akashiwo occurred, each lasting for approximately a week in duration. Analyses highlighted nutrient depletion (i.e. nitrate and phosphate concentrations) as the key constraint on bloom duration. When the density of H. akashiwo decreased, the community composition became more diverse with species belonging to Bacillariophyceae and Dinophyceae becoming more abundant; albeit to a lesser degree (<180 µg Chl a l^?1). Dissolved oxygen shifted from super-saturated conditions (>14 mg l^?1) during peak HAB conditions, to instances of bottom water oxygen depletion (2–4 mg l^?1) during the decay phase. These findings highlight the potential severity of transforming a catchment from natural to one that is highly regulated by agricultural practices, while also emphasising the need for management intervention.     

Serum/glucocorticoid-induced protein kinase-1 facilitates androgen receptor-dependent cell survival

Androgen receptor (AR) is a critical factor in the development and progression of prostate cancer. We and others recently demonstrated that eliminating AR expression leads to apoptotic cell death in AR-positive prostate cancer cells. To understand the mechanisms of AR-dependent survival, we performed a genome-wide search for AR-regulated survival genes. We found that serum/glucocorticoid-induced protein kinase-1 (SGK-1) mRNA levels were significantly upregulated after androgen stimulation, which was confirmed to be AR dependent. Promoter analysis revealed that the AR interacted with the proximal and distal regions of the sgk1 promoter, leading to sgk-1 promoter activation after androgen stimulation. Functional assays demonstrated that SGK-1 was indispensable for the protective effect of androgens on cell death induced by serum starvation. SGK-1 overexpression not only rescued cells from AR small-interfering RNA (siRNA)-induced apoptosis, but also enhanced AR transactivation, even in the absence of androgen. Additionally, SGK-1 siRNA reduced AR transactivation, indicating a positive feedback effect of SGK-1 expression on AR-mediated gene expression and cellular survival. Taken together, our data suggest that SGK-1 is an androgen-regulated gene that plays a pivotal role in AR-dependent survival and gene expression.     

Weight loss is not mandatory for exercise-induced effects on health indices in females with metabolic syndrome

The aim of this study was to investigate the impact of moderate aerobic training on functional, anthropometric, biochemical, and health-related quality of life (HRQOL) parameters on women with metabolic syndrome (MS). Fifteen untrained women with MS performed moderate aerobic training for 15 weeks, without modifications of dietary behaviours. Functional, anthropometric, biochemical, control diet record and HRQOL parameters were assessed before and after the training. Despite body weight maintenance, the patients presented decreases in waist circumference (P = 0.001), number of MS components (P = 0.014), total cholesterol (P = 0.049), HDL cholesterol (P = 0.004), LDL cholesterol (P = 0.027), myeloperoxidase activity (P = 0.002) and thiobarbituric acid-reactive substances levels (P = 0.006). There were no differences in total energy, carbohydrate, protein and lipid intake pre- and post-training. Furthermore, improvements in the HRQOL subscales of physical functioning (P = 0.03), role-physical (P = 0.039), bodily pain (P = 0.048), general health (P = 0.046) and social functioning scoring (P = 0.011) were reported. Despite the absence of weight loss, aerobic training induced beneficial effects on functional, anthropometric, biochemical and HRQOL parameters in women with MS.     

Molecular evolution of P transposable elements in the genus Drosophila. I. The saltans and willistoni species groups

A phylogenetic survey using the polymerase chain reaction (PCR) has identified four major P element subfamilies in the saltans and willistoni species groups of Drosophila. One subfamily, containing about half of the sequences studied, consists of elements that are very similar to the canonical (and active) P element from D. melanogaster. Within this subfamily, nucleotide sequence differentiation among different copies from the same species and among elements from different species is relatively low. This observation suggests that the canonical elements are relatively recent additions to the genome or, less likely, are evolving slowly relative to the other subfamilies. Elements belonging to the three noncanonical lineages are distinct from the canonical elements and from one another. Furthermore, there is considerably more sequence variation, on the average, within the noncanonical subfamilies compared to the canonical elements. Horizontal transfer and the coexistence of multiple, independently evolving element subfamilies in the same genome may explain the distribution of P elements in the saltans and willistoni species groups. Such explanations are not mutually exclusive, and each may be involved to varying degrees in the maintenance of P elements in natural populations of Drosophila.      

Bone marrow-derived IFN-producing killer dendritic cells account for the tumoricidal activity of unpulsed dendritic cells

The CD11c(int)B220(+)NK1.1(+)CD49(+) subset of cells has recently been described as IFN-producing killer dendritic cells (IKDC), which share phenotypic and functional properties of dendritic cells and NK cells. Herein we show that bone marrow-derived murine dendritic cell preparations contain abundant CD11c(int)B220(+)NK1.1(+)CD49(+) cells, the removal of which results in loss of tumoricidal activity of unpulsed dendritic cells in vivo. Moreover, following s.c. injection, as few as 5 x 10(3) highly pure bone marrow-derived IKDC cells are capable of shrinking small contralateral syngeneic tumors in C57BL/6 mice, but not in immunodeficient mice, implying the obligate involvement of host effector cells in tumor rejection. Our data suggest that bone marrow-derived IKDC represent a population that has powerful tumoricidal activity in vivo.     

Baroreceptors, baroreceptor unloading, and the long-term control of blood pressure

Whether arterial baroreceptors play a role in setting the long-term level of mean arterial pressure (MAP) has been debated for more than 75 years. Because baroreceptor input is reciprocally related to efferent sympathetic nerve activity (SNA), it is obvious that baroreceptor unloading would cause an increase in MAP. Experimental proof of concept is evident acutely after baroreceptor denervation. Chronically, however, baroreceptor denervation is associated with highly variable changes in MAP but not sustained hypertension. The ability of baroreceptors to buffer imposed increases in MAP appears limited by a process termed "resetting," in which the threshold to fire shifts in the direction of the pressure change and if the pressure elevation is maintained, it leads to a rightward shift in the relationship between baroreceptor firing and MAP. The most common hypothesis linking baroreceptors to changes in MAP proposes that reduced vascular distensibility in baroreceptive areas would cause reduced firing at the same pulsatile pressure and, thus, reflexively increase SNA. This review focuses on effects of baroreceptor denervation in the regulation of MAP in human subjects compared with animal studies; the relationship between vascular compliance, MAP, and baroreceptor resetting; and, finally, the effect of chronic baroreceptor unloading on the regulation of MAP.     

Unloading arterial baroreceptors causes neurogenic hypertension

We developed a new model to examine the role of arterial baroreceptors in the long-term control of mean arterial pressure (MAP) in dogs. Baroreceptors in the aortic arch and one carotid sinus were denervated, and catheters were implanted in the descending aorta and common carotid arteries. MAP and carotid sinus pressure (CSP) averaged 104 +/- 2 and 102 +/- 2 mmHg (means +/- 1 SE), respectively, during a 5-day control period. Baroreceptor unloading was induced by ligation of the common carotid artery proximal to the innervated sinus (n = 6 dogs). MAP and CSP averaged 127 +/- 7 and 100 +/- 3 mmHg, respectively, during the 7-day period of baroreceptor unloading. MAP was significantly elevated (P < 0.01) compared to control, but CSP was unchanged. Heart rate and plasma renin activity increased significantly in response to baroreceptor unloading. Removal of the ligature to restore normal flow through the carotid resulted in normalization of all variables. Ligation of the carotid below a denervated sinus (n = 4) caused a significant decrease in CSP but no systemic hypertension. These results indicate that chronic unloading of carotid baroreceptors can produce neurogenic hypertension and provide strong evidence that arterial baroreceptors are involved in the long-term control of blood pressure.     

Myogenic cell proliferation and generation of a reversible tumorigenic phenotype are triggered by preirradiation of the recipient site

Environmental influences have profound yet reversible effects on the behavior of resident cells. Earlier data have indicated that the amount of muscle formed from implanted myogenic cells is greatly augmented by prior irradiation (18 Gy) of the host mouse muscle. Here we confirm this phenomenon, showing that it varies between host mouse strains. However, it is unclear whether it is due to secretion of proliferative factors or reduction of antiproliferative agents. To investigate this further, we have exploited the observation that the immortal myogenic C2 C12 cell line forms tumors far more rapidly in irradiated than in nonirradiated host muscle. We show that the effect of preirradiation on tumor formation is persistent and dose dependent. However, C2 C12 cells are not irreversibly compelled to form undifferentiated tumor cells by the irradiated muscle environment and are still capable of forming large amounts of muscle when reimplanted into a nonirradiated muscle. In a clonal analysis of this effect, we discovered that C2 C12 cells have a bimodal propensity to form tumors; some clones form no tumors even after extensive periods in irradiated graft sites, whereas others rapidly form extensive tumors. This illustrates the subtle interplay between the phenotype of implanted cells and the factors in the muscle environment.     

Selenium concentration in the prostate

Samples of healthy tissue were taken from each of six prostatectomy specimens (55–72 yr), digested with acids, and analyzed for selenium by atomic fluorescence spectroscopy. The concentrations for five specimens were 1.32±0.09 μg Se/g dry wt (range 1.24–1.42) and 0.213±0.012 μg Se/g wet wt (range 0.200–0.229). The other specimen, from a 58-yr-old man who was the only one within this study to take a 200-μg Se/d dietary supplement, contained 2.72 μg Se/g dry wt and 0.421 μg Se/g wet wt.