An Algorithm to Automate Yeast Segmentation and Tracking

Our understanding of dynamic cellular processes has been greatly enhanced by rapid advances in quantitative fluorescence microscopy. Imaging single cells has emphasized the prevalence of phenomena that can be difficult to infer from population measurements, such as all-or-none cellular decisions, cell-to-cell variability, and oscillations. Examination of these phenomena requires segmenting and tracking individual cells over long periods of time. However, accurate segmentation and tracking of cells is difficult and is often the rate-limiting step in an experimental pipeline. Here, we present an algorithm that accomplishes fully automated segmentation and tracking of budding yeast cells within growing colonies. The algorithm incorporates prior information of yeast-specific traits, such as immobility and growth rate, to segment an image using a set of threshold values rather than one specific optimized threshold. Results from the entire set of thresholds are then used to perform a robust final segmentation.     

Complex belongings: Racialization and migration in a small English city

The article explores how long-term residents in a small city with rural links in the East of England related to new migrants at a time of changing patterns and increased volume of migration. Based on in-depth interviews and observations in 2005–6, the article shows dynamic, complex, and nuanced constructions of belonging and governmentalities of belonging. Long-term Peterborians felt proud that their city attracted migrants and became more multicultural. Many saw this as a normative aspect of being modern. Yet, the arrival of migrants also led to tensions and re-inscribed the racialization of Peterborough's ethnic minorities, articulated through the theme of neighbourliness. Through the figures of ‘uncaring migrant neighbours’ and ‘ruthless Pakistani landlords’, migrants and ethnic minority Peterborians were portrayed as refusing injunctions to care for the neighbourhood and the nation. Ethnic minority Peterborians were positioned ambivalently as hosts of and – at times – targets of racism by new migrants.     

The Evaluation of the Oxidant Injury as a Function of Time Following Brain Irradiation in a Rat Model

This study presents the evaluation of the oxidant injury as a function of time following brain irradiation in a rat model. Thirty-five Wistar rats were divided into seven groups. The rats in Group 1 through Group 6 underwent irradiation, whereas the rats in Group 7 underwent sham irradiation. The rats in Group 1 through Group 6 underwent euthanasia at 1 through 48 h following irradiation, whereas the rats in Group 7 underwent euthanasia immediately following sham irradiation. At the time of euthanasia, the brain tissue was dissected for evaluation of the malondialdehyde (MDA) level and the superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSHPX) activities. The mean MDA levels were increased and the mean SOD, CAT and GSHPX activities were decreased at all of the time points for evaluation for the rats that underwent irradiation as compared to the rats that underwent sham irradiation, substantial for Group 1 and gradually leveling out through Group 6. This study confirms that the oxidant injury is evaluated at its best through the first several hours following brain irradiation.     

Expression patterns of genes encoding proteins with peritrophin A domains and protein localization in Mamestra configurata

Genes encoding three proteins (McPPAD1-3) with peritrophin A chitin-binding domains (PADs) were identified from a Mamestra configurata larval midgut cDNA library. In addition to midgut, McPPAD1-3 and a previously identified gene encoding the peritrophin, McPM1, were expressed in foregut, hindgut, Malpighian tubules, tracheae, fat body and cuticle; however, the corresponding McPPAD proteins exhibited different localization patterns. McPPAD1 was restricted to the digestive tract and Malpighian tubules, McPPAD2 to Malpighian tubules, and McPPAD3 to the foregut, midgut, hindgut, tracheae and cuticle. Protein fold recognition analysis using tachycitin as a guide structure modelled the McPPAD1 PADs, but not McPPAD2 or McPPAD3 PADs. The McPPAD1 PADs were predicted to contain three anti-parallel β-sheets and a hevein-like fold that form a chitin-binding pocket containing two hydrophobic R-groups in a sandwich-like orientation.     

Ectodomain shedding of the EGF-receptor ligand epigen is mediated by ADAM17

All ligands of the epidermal growth factor receptor (EGFR), which has important roles in development and disease, are made as transmembrane precursors. Proteolytic processing by ADAMs (a disintegrin and metalloprotease) regulates the bioavailability of several EGFR-ligands, yet little is known about the enzyme responsible for processing the recently identified EGFR ligand, epigen. Here we show that ectodomain shedding of epigen requires ADAM17, which can be stimulated by phorbol esters, phosphatase inhibitors and calcium influx. These results suggest that ADAM17 might be a good target to block the release of bioactive epigen, a highly mitogenic ligand of the EGFR which has been implicated in wound healing and cancer.     

Characterization of the Mamestra configurata (Lepidoptera: Noctuidae) larval midgut protease complement and adaptation to feeding on artificial diet,Brassica species,and protease inhibitor

The midgut protease profiles from 5th instar Mamestra configurata larvae fed various diets (standard artificial diet, low protein diet, low protein diet with soybean trypsin inhibitor [SBTI], or Brassica napus) were characterized by one‐dimensional enzymography in gelatin gels. The gut protease profile of larvae fed B. napus possessed protease activities of molecular masses of approximately 33 and 55 kDa, which were not present in the guts of larvae fed artificial diet. Similarly, larvae fed artificial diet had protease activities of molecular masses of approximately 21, 30, and 100 kDa that were absent in larvae fed B. napus. Protease profiles changed within 12 to 24 h after switching larvae from artificial diet to plant diet and vice versa. The gut protease profiles from larvae fed various other brassicaceous species and lines having different secondary metabolite profiles did not differ despite significant differences in larval growth rates on the different host plants. Genes encoding putative digestive proteolytic enzymes, including four carboxypeptidases, five aminopeptidases, and 48 serine proteases, were identified in cDNA libraries from 4th instar M. configurata midgut tissue. Many of the protease‐encoding genes were expressed at similar levels on all diets; however, three chymoptrypsin‐like genes (McSP23, McSP27, and McSP37) were expressed at much higher levels on standard artificial diet and diet containing SBTI as was the trypsin‐like gene McSP34. The expression of the trypsin‐like gene McSP50 was highest on B. napus. The adaptation of M. configurata digestive biochemistry to different diets is discussed in the context of the flexibility of polyphagous insects to changing diet sources. Published 2010 Wiley Periodicals, Inc.