The genetic effective and adult census size of an Australian population of tiger prawns (Penaeus esculentus)

This study compares estimates of the census size of the spawning population with genetic estimates of effective current and long-term population size for an abundant and commercially important marine invertebrate, the brown tiger prawn (Penaeus esculentus). Our aim was to focus on the relationship between genetic effective and census size that may provide a source of information for viability analyses of naturally occurring populations. Samples were taken in 2001, 2002 and 2003 from a population on the east coast of Australia and temporal allelic variation was measured at eight polymorphic microsatellite loci. Moments-based and maximum-likelihood estimates of current genetic effective population size ranged from 797 to 1304. The mean long-term genetic effective population size was 9968. Although small for a large population, the effective population size estimates were above the threshold where genetic diversity is lost at neutral alleles through drift or inbreeding. Simulation studies correctly predicted that under these experimental conditions the genetic estimates would have non-infinite upper confidence limits and revealed they might be overestimates of the true size. We also show that estimates of mortality and variance in family size may be derived from data on average fecundity, current genetic effective and census spawning population size, assuming effective population size is equivalent to the number of breeders. This work confirms that it is feasible to obtain accurate estimates of current genetic effective population size for abundant Type III species using existing genetic marker technology.     

The Hepatitis C virus NS5A protein activates a phosphoinositide 3-kinase-dependent survival signaling cascade

Hepatitis C virus (HCV) establishes a persistent infection, with up to 80% of infected individuals proceeding to chronic hepatitis, which in many cases may result in liver cirrhosis and hepatocellular carcinoma (HCC); indeed HCV infection is increasingly associated with the development of HCC. The long time period (up to 30 years) between primary infection and the onset of HCC implies that HCV is not directly oncogenic but in some way predisposes patients to develop tumors, though the mechanism for this is unclear as yet. We report here that NS5A binds directly to the Src homology 3 domain of the p85 regulatory subunit of phosphoinositide 3-kinase (PI3K), and this interaction is mediated by a novel (non-proline-rich) motif within NS5A. Coimmunoprecipitation analysis revealed that NS5A bound native heterodimeric PI3K and enhanced the phosphotransferase activity of the catalytic (p110) subunit both in vitro and in human cell lines harboring a subgenomic HCV replicon or expressing NS5A alone. NS5A-mediated activation of PI3K resulted in increased phosphorylation and activity of Akt/protein kinase B and concomitantly provided protection against the induction of apoptosis in both replicon-harboring cells and cells stably expressing NS5A alone. These data suggest that stimulation of PI3K by NS5A may represent an indirect mechanism for development of HCC in HCV-infected patients and further suggests potential therapeutic strategies to counteract the occurrence of HCV-related HCC.     

The dependence of protein release from Bacillus amyloliquefaciens on the growth phase in batch culture

For the recovery of intracellular material from bacteria it is often necessary to disrupt the cells. Much work has been done on the kinetics of protein release in beadmills,(1) homogenizers,(2) and by ultrasonication.(3) In this paper we report how the growth phase of Bacillus amyloliquefaciens grown in batch culture affects the rate of protein release by ball milling, ultrasonication, and autolysis. We further suggest that autolysis is a feasible method for disrupting Bacillus.     

A systems biology approach: new insights into fetal growth restriction using Bayesian Networks

IL-6, IGF-II and IGFBP-2 concentrations in placental lysates were previously shown to be associated with foetal growth. This study aimed to apply a Bayesian Network (BN) model in order to investigate complex dependencies among biochemical and clinical factors and fetal growth outcome. Twenty-one Intra-Uterine Growth Restricted (IUGR) and 25 Appropriate for Gestational Age (AGA) pregnancies were followed throughout pregnancy. Information was collected on maternal and gestational age, neonatal gender, previous gynaecological history. Total protein content, IGF-II, IGFBP-1, IGFBP-2, IL-6, and TNF-alpha concentrations in placental lysates were measured, and IGF-I, IGF-II, IGFBP-1, IGFBP-2 and IL-6 relative gene expression in placenta assessed. A BN and a hybrid forecasting system were implemented: BN revealed a key role of maternal age and TNF-alpha on IUGR and confirmed a close relationship among IGF-II, IL-6 and foetal growth. A relationship between duration of gestation, appropriateness for gestational age, and placental IL-6 concentration was also confirmed. Compared with other techniques, BN showed a better accuracy. Findings confirmed a major role of maternal age in addition to IGF-II, IL-6 and TNF-alpha in IUGR. A direct role of IGFBP-2 was not shown. BN confirmed to be useful in understanding the system's biology and graphically representing variable relationships and hierarchy, particularly where, as in IUGR, many interactions among predictors exist.