Ecosystem size structure response to 21st century climate projection: large fish abundance decreases in the central North Pacific and increases in the California Current

Output from an earth system model is paired with a size‐based food web model to investigate the effects of climate change on the abundance of large fish over the 21st century. The earth system model, forced by the Intergovernmental Panel on Climate Change (IPCC) Special report on emission scenario A2, combines a coupled climate model with a biogeochemical model including major nutrients, three phytoplankton functional groups, and zooplankton grazing. The size‐based food web model includes linkages between two size‐structured pelagic communities: primary producers and consumers. Our investigation focuses on seven sites in the North Pacific, each highlighting a specific aspect of projected climate change, and includes top‐down ecosystem depletion through fishing. We project declines in large fish abundance ranging from 0 to 75.8% in the central North Pacific and increases of up to 43.0% in the California Current (CC) region over the 21st century in response to change in phytoplankton size structure and direct physiological effects. We find that fish abundance is especially sensitive to projected changes in large phytoplankton density and our model projects changes in the abundance of large fish being of the same order of magnitude as changes in the abundance of large phytoplankton. Thus, studies that address only climate‐induced impacts to primary production without including changes to phytoplankton size structure may not adequately project ecosystem responses.     

A Fine-Structure Map of Spontaneous Mitotic Crossovers in the Yeast Saccharomyces cerevisiae

Homologous recombination is an important mechanism for the repair of DNA damage in mitotically dividing cells. Mitotic crossovers between homologues with heterozygous alleles can produce two homozygous daughter cells (loss of heterozygosity), whereas crossovers between repeated genes on non-homologous chromosomes can result in translocations. Using a genetic system that allows selection of daughter cells that contain the reciprocal products of mitotic crossing over, we mapped crossovers and gene conversion events at a resolution of about 4 kb in a 120-kb region of chromosome V of Saccharomyces cerevisiae. The gene conversion tracts associated with mitotic crossovers are much longer (averaging about 12 kb) than the conversion tracts associated with meiotic recombination and are non-randomly distributed along the chromosome. In addition, about 40% of the conversion events have patterns of marker segregation that are most simply explained as reflecting the repair of a chromosome that was broken in G1 of the cell cycle.     

Cutaneous anthrax associated with handling carcasses of animals that died suddenly of unknown cause: Arua District,Uganda, January 2015–August 2017

BackgroundAnthrax is a zoonotic disease that can be transmitted to humans from infected animals. During May–June 2017, three persons with probable cutaneous anthrax were reported in Arua District, Uganda; one died. All had recently handled carcasses of livestock that died suddenly and a skin lesion from a deceased person tested positive by PCR for Bacillus anthracis. During July, a bull in the same community died suddenly and the blood sample tested positive by PCR for Bacillus anthracis. The aim of this investigation was to establish the scope of the problem, identify exposures associated with illness, and recommend evidence-based control measures.MethodsA probable case was defined as acute onset of a papulo-vesicular skin lesion subsequently forming an eschar in a resident of Arua District during January 2015–August 2017. A confirmed case was a probable case with a skin sample testing positive by polymerase chain reaction (PCR) for B. anthracis. Cases were identified by medical record review and active community search. In a case-control study, exposures between case-patients and frequency- and village-matched asymptomatic controls were compared. Key animal health staff were interviewed to learn about livestock deaths.ResultsThere were 68 case-patients (67 probable, 1 confirmed), and 2 deaths identified. Cases occurred throughout the three-year period, peaking during dry seasons. All cases occurred following sudden livestock deaths in the villages. Case-patients came from two neighboring sub-counties: Rigbo (attack rate (AR) = 21.9/10,000 population) and Rhino Camp (AR = 1.9/10,000). Males (AR = 24.9/10,000) were more affected than females (AR = 0.7/10,000). Persons aged 30–39 years (AR = 40.1/10,000 population) were most affected. Among all cases and 136 controls, skinning (OR_M-H = 5.0, 95%CI: 2.3–11), butchering (OR_M-H = 22, 95%CI: 5.5–89), and carrying the carcass of livestock that died suddenly (OR_M-H = 6.9, 95%CI: 3.0–16) were associated with illness.ConclusionsExposure to carcasses of animals that died suddenly was a likely risk factor for cutaneous anthrax in Arua District during 2015–2017. The recommendations are investigation of anthrax burden in livestock, prevention of animal infections through vaccinations, safe disposal of the carcasses, public education on risk factors for infection and prompt treatment of illness following exposure to animals that died suddenly.     

Elucidation of the first definitively identified life cycle for a marine turtle blood fluke (Trematoda: Spirorchiidae) enables informed control

Blood flukes of the family Spirorchiidae are significant pathogens of both free-ranging and captive marine turtles. Despite a significant proportion of marine turtle mortality being attributable to spirorchiid infections, details of their life cycles remain almost entirely unknown. Here we report on the molecular elucidation of the complete life cycle of a marine spirorchiid, identified as Amphiorchis sp., infecting vermetid gastropods and captive hatched neonate Caretta caretta in the Oceanogràfic Aquarium, in Valencia, Spain. Specimens of a vermetid gastropod, Thylaeodus cf. rugulosus (Monterosato, 1878), collected from the aquarium filtration system housing diseased C. caretta, were infected with sporocysts and cercariae consistent with the family Spirorchiidae. We generated rDNA sequence data [internal transcribed spacer 2 (ITS2) and partial 28S rDNA] from infections from the vermetid which were identical to sequences generated from eggs from the serosa of the intestine of neonate C. caretta, and an adult spirorchiid from the liver of a C. caretta from Florida, USA. Given the reliability of these markers in the delineation of trematode species, we consider all three stages to represent the same species and tentatively identify it as a species of Amphiorchis Price, 1934. The source of infection at the Oceanogràfic Foundation Rehabilitation Centre, Valencia, Spain, is inferred to be an adult C. caretta from the western Mediterranean being rehabilitated in the same facility. Phylogenetic analysis suggests that this Amphiorchis sp. is closely related to other spirorchiids of marine turtles (species of Carettacola Manter & Larson, 1950, Hapalotrema Looss, 1899 and Learedius Price, 1934). We discuss implications of the present findings for the control of spirorchiidiasis in captivity, for the better understanding of epidemiology in wild individuals, and the elucidation of further life cycles.     

Inferring gene expression dynamics from reporter protein levels

We present a mathematical method for inferring the dynamics of gene expression from time series of reporter protein assays and cell populations. We show that estimating temporal expression dynamics from direct visual inspection of reporter protein data is unreliable when the half-life of the protein is comparable to the time scale of the expression dynamics. Our method is simple and general because it is designed only to reconstruct the pattern of protein synthesis, without assuming any specific regulatory mechanisms. It can be applied to a wide range of cell types, patterns of expression, and reporter systems, and is implemented in publicly available spreadsheets. We show that our method is robust to a several possible types of error, and argue that uncertainty about the decay kinetics of reporter proteins is the limiting factor in reconstructing the temporal pattern of gene expression dynamics from reporter protein assays. With improved estimates of reporter protein decay rates, our approach could allow for detailed reconstruction of gene expression dynamics from commonly used reporter protein systems.     

Finding edging genes from microarray data

MOTIVATION: A set of genes and their gene expression levels are used to classify disease and normal tissues. Due to the massive number of genes in microarray, there are a large number of edges to divide different classes of genes in microarray space. The edging genes (EGs) can be co-regulated genes, they can also be on the same pathway or deregulated by the same non-coding genes, such as siRNA or miRNA. Every gene in EGs is vital for identifying a tissue's class. The changing in one EG's gene expression may cause a tissue alteration from normal to disease and vice versa. Finding EGs is of biological importance. In this work, we propose an algorithm to effectively find these EGs. RESULT: We tested our algorithm with five microarray datasets. The results are compared with the border-based algorithm which was used to find gene groups and subsequently divide different classes of tissues. Our algorithm finds a significantly larger amount of EGs than does the border-based algorithm. As our algorithm prunes irrelevant patterns at earlier stages, time and space complexities are much less prevalent than in the border-based algorithm. AVAILABILITY: The algorithm proposed is implemented in C++ on Linux platform. The EGs in five microarray datasets are calculated. The preprocessed datasets and the discovered EGs are available at http://www3.it.deakin.edu.au/~phoebe/microarray.html.     

Discovery of a novel series of 6-azauracil-based thyroid hormone receptor ligands: potent,TR beta subtype-selective thyromimetics

In this communication, we wish to describe the discovery of a novel series of 6-azauracil-based thyromimetics that possess up to 100-fold selectivities for binding and functional activation of the beta(1)-isoform of the thyroid receptor family. Structure-activity relationship studies on the 3,5- and 3'-positions provided compounds with enhanced TR beta affinity and selectivity. Key binding interactions between the 6-azauracil moiety and the receptor have been determined through of X-ray crystallographic analysis.