Effects of Spring Breakup on Microscale Air Temperatures in the Mackenzie River Delta

The effects of spring breakup on microscale air temperatures in the Mackenzie River delta were investigated by means of intervention analysis. Small but statistically significant increases in temperatures were detected for some areas within the delta and appeared to be related to ice breakup events in nearby channels and lake systems. The magnitude of the temperature increase appeared to be correlated with the severity of winter conditions preceding breakup and with the rate at which breakup progressed. The relative importance of changes in surface albedo and river heat input in causing air temperature rises is discussed. Temperature increases due to breakup are small in comparison to seasonal warming trends and diurnal temperature fluctuations.Key words: Mackenzie River, delta, breakup, climate, air temperature, intervention analysis, time-seriesMots clés: Fleuve Mackenzie, delta, débâcle, climat, température de l'air, analyse d'intervention, séries chronologique

Habitat Selection by Large Wild Ungulates and Some Aspects of the Energy Flow in a Sub-tropical African Savanna Woodland Ecosystem

A study of habitat selection by large wild ungulates was carried out on a 50 cm2 area in the sub-tropical Lowveld region of eastern Transvaal province, South Africa. Estimations were made of herbaceous forage net productivity and ungulate secondary productivity on the same area. Fourteen vegetation types, varying in composition and structure from open savanna to dense woodland, were delineated by association analysis. Structural and vegetational characteristics which were considered to influence ungulate distribution were measured within each vegetation type. The study area supported resident populations of seven ungulate species during the wet season; drv season densities were higher due to population influxes from surrounding areas. Densities ranged from 13 to 67 animals per km2, with impala making up from 40 to 70 percent of the total population, wildebeest 10 to 40 percent, and lesser proportions of giraffe, zebra, kudu, warthog and waterbuck. Savanna vegetation types supported total densities of up to 185 animals/km2, while wooded types support fewer animals. Waterbuck were the most selective of the ungulates and concentrated mainly in the riparian woodland. Wildebeest, zebra and giraffe made variable use of savanna and open woodland types. Warthog preferred savanna types and avoided woodland. Impala were less selective, and kudu showed no habitat preferences. Ungulate distribution was related to several habitat characteristics, and the key factors were found to differ in each case. Each species had a unique combination of habitat characteristics to which it responded in linear fashion, and this was considered to be the way in which ungulates avoided competition by achieving spatial separation. Herbaceous forage standing crops and net production were functions of vegetation composition, soil types, rainfall and extent of ungulate utilization. Standing crops ranged from 350 to 4104 kgs/ha air-dried forage. Net primary production ranged from zero to 2719 kgs/ha; vegetation types on sandy soils did not produce in years with poor precipitation. Ungulates consumed about one-fourth of the herbaceous net primary production during the wet season and more than four-fifths during the course of a full year. Ungulate biomass on the area averaged about 40 kg/ha during the wet season and 65 kg/ha in the dry season, but biomasses varied a great deal with vegetation type, ungulate population species coMposition and seasonal densities. Ungulate secondary product ion varied correspondingly and ranged from 1.3 x 10-3 kcal/m2 per day to 4.8 x 10-3 kcals/m2 per day. Overall secondary production rate for the 2-year study period was 0.97 kcals/m2 per year, produced from a mean standing crop of 7.46 kcal/m2

INSGFP/w human embryonic stem cells facilitate isolation of in vitro derived insulin-producing cells

AIMS/HYPOTHESIS: We aimed to generate human embryonic stem cell (hESC) reporter lines that would facilitate the characterisation of insulin-producing (INS⁺) cells derived in vitro. METHODS: Homologous recombination was used to insert sequences encoding green fluorescent protein (GFP) into the INS locus, to create reporter cell lines enabling the prospective isolation of viable INS⁺ cells. RESULTS: Differentiation of INS(GFP/w) hESCs using published protocols demonstrated that all GFP⁺ cells co-produced insulin, confirming the fidelity of the reporter gene. INS-GFP⁺ cells often co-produced glucagon and somatostatin, confirming conclusions from previous studies that early hESC-derived insulin-producing cells were polyhormonal. INS(GFP/w) hESCs were used to develop a 96-well format spin embryoid body (EB) differentiation protocol that used the recombinant protein-based, fully defined medium, APEL. Like INS-GFP⁺ cells generated with other methods, those derived using the spin EB protocol expressed a suite of pancreatic-related transcription factor genes including ISL1, PAX6 and NKX2.2. However, in contrast with previous methods, the spin EB protocol yielded INS-GFP⁺ cells that also co-expressed the beta cell transcription factor gene, NKX6.1, and comprised a substantial proportion of monohormonal INS⁺ cells. CONCLUSIONS/INTERPRETATION: INS(GFP/w) hESCs are a valuable tool for investigating the nature of early INS⁺ progenitors in beta cell ontogeny and will facilitate the development of novel protocols for generating INS⁺ cells from differentiating hESCs

Differentiating Embryonic Stem Cells Pass through ‘Temporal Windows’ That Mark Responsiveness to Exogenous and Paracrine Mesendoderm Inducing Signals

BACKGROUND: Mesendoderm induction during embryonic stem cell (ESC) differentiation in vitro is stimulated by the Transforming Growth Factor and Wingless (Wnt) families of growth factors. PRINCIPAL FINDINGS: We identified the periods during which Bone Morphogenetic Protein (BMP) 4, Wnt3a or Activin A were able to induce expression of the mesendoderm marker, Mixl1, in differentiating mouse ESCs. BMP4 and Wnt3a were required between differentiation day (d) 1.5 and 3 to most effectively induce Mixl1, whilst Activin A induced Mixl1 expression in ESC when added between d2 and d4, indicating a subtle difference in the requirement for Activin receptor signalling in this process. Stimulation of ESCs with these factors at earlier or later times resulted in little Mixl1 induction, suggesting that the differentiating ESCs passed through 'temporal windows' in which they sequentially gained and lost competence to respond to each growth factor. Inhibition of either Activin or Wnt signalling blocked Mixl1 induction by any of the three mesendoderm-inducing factors. Mixing experiments in which chimeric EBs were formed between growth factor-treated and untreated ESCs revealed that BMP, Activin and Wnt signalling all contributed to the propagation of paracrine mesendoderm inducing signals between adjacent cells. Finally, we demonstrated that the differentiating cells passed through 'exit gates' after which point they were no longer dependent on signalling from inducing molecules for Mixl1 expression. CONCLUSIONS: These studies suggest that differentiating ESCs are directed by an interconnected network of growth factors similar to those present in early embryos and that the timing of growth factor activity is critical for mesendoderm induction

Liquid facets-Related (lqfR) Is Required for Egg Chamber Morphogenesis during Drosophila Oogenesis

Clathrin interactor 1 [CLINT1] (also called enthoprotin/EpsinR) is an Epsin N-terminal homology (ENTH) domain-containing adaptor protein that functions in anterograde and retrograde clathrin-mediated trafficking between the trans-Golgi network and the endosome. Removal of both Saccharomyces cerevisiae homologs, Ent3p and Ent5p, result in yeast that are viable, but that display a cold-sensitive growth phenotype and mistrafficking of various vacuolar proteins. Similarly, either knock-down or overexpression of vertebrate CLINT1 in cell culture causes mistrafficking of proteins. Here, we have characterized Drosophila CLINT1, liquid-facets Related (lqfR). LqfR is ubiquitously expressed throughout development and is localized to the Golgi and endosome. Strong hypomorphic mutants generated by imprecise P-element excision exhibit extra macrochaetae, rough eyes and are female sterile. Although essentially no eggs are laid, the ovaries do contain late-stage egg chambers that exhibit abnormal morphology. Germline clones reveal that LqfR expression in the somatic follicle cells is sufficient to rescue the oogenesis defects. Clones of mutant lqfR follicle cells have a decreased cell size consistent with a downregulation of Akt1. We find that while total Akt1 levels are increased there is also a significant decrease in activated phosphorylated Akt1. Taken together, these results show that LqfR function is required to regulate follicle cell size and signaling during Drosophila oogenesis

Brachyury and Related Tbx Proteins Interact with the Mixl1 Homeodomain Protein and Negatively Regulate Mixl1 Transcriptional Activity

Mixl1 is a homeodomain transcription factor required for mesoderm and endoderm patterning during mammalian embryogenesis. Despite its crucial function in development, co-factors that modulate the activity of Mixl1 remain poorly defined. Here we report that Mixl1 interacts physically and functionally with the T-box protein Brachyury and related members of the T-box family of transcription factors. Transcriptional and protein analyses demonstrated overlapping expression of Mixl1 and Brachyury during embryonic stem cell differentiation. In vitro protein interaction studies showed that the Mixl1 with Brachyury associated via their DNA-binding domains and gel shift assays revealed that the Brachyury T-box domain bound to Mixl1-DNA complexes. Furthermore, luciferase reporter experiments indicated that association of Mixl1 with Brachyury and related T-box factors inhibited the transactivating potential of Mixl1 on the Gsc and Pdgfrα promoters. Our results indicate that the activity of Mixl1 can be modulated by protein-protein interactions and that T-box factors can function as negative regulators of Mixl1 activity

Multiplatform Analysis of 12 Cancer Types Reveals Molecular Classification within and across Tissues of Origin

Recent genomic analyses of pathologically-defined tumor types identify “within-a-tissue” disease subtypes. However, the extent to which genomic signatures are shared across tissues is still unclear. We performed an integrative analysis using five genome-wide platforms and one proteomic platform on 3,527 specimens from 12 cancer types, revealing a unified classification into 11 major subtypes. Five subtypes were nearly identical to their tissue-of-origin counterparts, but several distinct cancer types were found to converge into common subtypes. Lung squamous, head & neck, and a subset of bladder cancers coalesced into one subtype typified by TP53 alterations, TP63 amplifications, and high expression of immune and proliferation pathway genes. Of note, bladder cancers split into three pan-cancer subtypes. The multi-platform classification, while correlated with tissue-of-origin, provides independent information for predicting clinical outcomes. All datasets are available for data-mining from a unified resource to support further biological discoveries and insights into novel therapeutic strategies

Association of common maternal infections with birth outcomes:a multinational cohort study

PurposeIt is unclear whether common maternal infections during pregnancy are risk factors for adverse birth outcomes. We assessed the association between self-reported infections during pregnancy with preterm birth and small-for-gestational-age (SGA) in an international cohort consortium.MethodsData on 120,507 pregnant women were obtained from six population-based birth cohorts in Australia, Denmark, Israel, Norway, the UK and the USA. Self-reported common infections during pregnancy included influenza-like illness, common cold, any respiratory tract infection, vaginal thrush, vaginal infections, cystitis, urinary tract infection, and the symptoms fever and diarrhoea. Birth outcomes included preterm birth, low birth weight and SGA. Associations between maternal infections and birth outcomes were first assessed using Poisson regression in each cohort and then pooled using random-effect meta-analysis. Risk ratios (RR) and 95% confidence intervals (CI) were calculated, adjusted for potential confounders.ResultsVaginal infections (pooled RR, 1.10; 95% CI, 1.02–1.20) and urinary tract infections (pooled RR, 1.17; 95% CI, 1.09–1.26) during pregnancy were associated with higher risk of preterm birth. Similar associations with low birth weight were also observed for these two infections. Fever during pregnancy was associated with higher risk of SGA (pooled RR, 1.07; 95% CI, 1.02–1.12). No other significant associations were observed between maternal infections/symptoms and birth outcomes.ConclusionVaginal infections and urinary infections during pregnancy were associated with a small increased risk of preterm birth and low birth weight, whereas fever was associated with SGA. These findings require confirmation in future studies with laboratory-confirmed infection diagnosis