The Influence of Short-Term Events on the Hydrographic and Biological Structure of the Southwestern Ross Sea

Relative to the rest of the Southern Ocean, the Ross Sea continental shelf experiences very high productivity and phytoplankton biomass, which supports an extensive food web including high concentrations of upper trophic level biomass. Conventional observational methods, including ship-based sampling, instrumented moorings, satellite imagery, and computer-based modelling, have illustrated the seasonal progression of the phytoplankton bloom over the past four decades. While we have been sampling phytoplankton variability in the Ross Sea on a variety of relatively large scales, with observations at specific locations or times, over spans of time, or at specific depths, our understanding of smaller scales of variability (on the order of a few hours or several kilometers) is still poor. Utilizing two seasons (2010-2011 and 2012-2013) of high-resolution autonomous glider deployments in the southwestern Ross Sea, I examined the mechanisms driving both the transitions between stages of the phytoplankton bloom and the short-term perturbations in average 0-50 m chlorophyll. By including the available raw fluorescence data from both glider seasons and three mooring seasons, I determined that the 2012-2013 season had greater than average variability, with greater levels of variability observed in only two other seasons. Differences in the timing of bloom transitions were relatively constrained; the transition from bloom to post-bloom levels occurred within a temporal span of 6 d. These findings were likely the result of the location of the 2012-2013 glider adjacent to Ross Island and the Ross Ice Shelf, where complex bathymetry, turbulent flows, and the presence of an ice field contributed to the greater observed variability. To investigate the mechanisms driving the short-term perturbations in chlorophyll, I examined the relationships between average chlorophyll, average temperature, and mixed layer depth measured by the gliders and wind speed measured by two automatic weather stations atop the Ross Ice Shelf. Over the course of the 2012-2013 season, perturbations or responses in chlorophyll were heavily influenced by the degree of temporal coupling between wind events and the depth of mixing. Longer delays of 12-24 h observed prior to the biomass maximum shortened following the transition to biomass dissipation to 2-12 h. Furthermore, by causing aggregate formation and rapid vertical flux, physical forcing factors contributed to the observed short-term perturbations through reductions in biomass in surface layers and the appearance of chlorophyll in deeper layers. These results suggest that the small-scale observing capabilities of autonomous gliders allow for an improved understanding of the mechanisms that drive variability and short-term perturbations in shallow chlorophyll in the southwestern Ross Sea

Development of a protocol for maintaining viability while shipping organoid-derived retinal tissue.

Retinal organoid technology enables generation of an inexhaustible supply of three-dimensional retinal tissue from human pluripotent stem cells (hPSCs) for regenerative medicine applications. The high similarity of organoid-derived retinal tissue and transplantable human fetal retina provides an opportunity for evaluating and modeling retinal tissue replacement strategies in relevant animal models in the effort to develop a functional retinal patch to restore vision in patients with profound blindness caused by retinal degeneration. Because of the complexity of this very promising approach requiring specialized stem cell and grafting techniques, the tasks of retinal tissue derivation and transplantation are frequently split between geographically distant teams. Delivery of delicate and perishable neural tissue such as retina to the surgical sites requires a reliable shipping protocol and also controlled temperature conditions with damage-reporting mechanisms in place to prevent transplantation of tissue damaged in transit into expensive animal models. We have developed a robust overnight tissue shipping protocol providing reliable temperature control, live monitoring of the shipment conditions and physical location of the package, and damage reporting at the time of delivery. This allows for shipping of viable (transplantation-competent) hPSC-derived retinal tissue over large distances, thus enabling stem cell and surgical teams from different parts of the country to work together and maximize successful engraftment of organoid-derived retinal tissue. Although this protocol was developed for preclinical in vivo studies in animal models, it is potentially translatable for clinical transplantation in the future and will contribute to developing clinical protocols for restoring vision in patients with retinal degeneration

Acquisition of children's addition strategies: A model of impasse-free, knowledge-level learning

When children learn to add, they count on their fingers, beginning with the simple Sum Strategy and gradually developing the more sophisticated and efficient Min strategy. The shift from Sum to Min provides an ideal domain for the study of naturally occurring discovery processes in cognitive skill acquisition. The Sum -to- Min transition poses a number of challenges for machine-learning systems that would model the phenomenon. First, in addition to the Sum and Min strategies, Siegler and Jenkins (1989) found that children exhibit two transitional strategies, but not a strategy proposed by an earlier model. Second, they found that children do not invent the Min strategy in response to impasses, or gaps in their knowledge. Rather, Min develops spontaneously and gradually replaces earlier strategies. Third, intricate structural differences between the Sum and Min strategies make it difficult, if not impossible, for standard, symbol-level machine-learning algorithms to model the transition. We present a computer model, called Gips , that meets these challenges. Gips combines a relatively simple algorithm for problem solving with a probabilistic learning algorithm that performs symbol-level and knowledge-level learning, both in the presence and absence of impasses. In addition, Gips makes psychologically plausible demands on local processing and memory. Most importantly, the system successfully models the shift from Sum to Min , as well as the two transitional strategies found by Siegler and Jenkins.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46917/1/10994_2004_Article_BF00993172.pd

Anaplastic Lymphoma Kinase Immunocytochemistry on Cell-Transferred Cytologic Smears of Lung Adenocarcinoma

Background: Anaplastic lymphoma kinase (ALK) immunohistochemical staining on formalin-fixed paraffin-embedded tissue or cell blocks (CB) has been reported as an effective alternative to fluorescence hybridization in situ (FISH) for the detection of ALK gene rearrangement. However, CB frequently lack adequate cellularity even when the direct smears are cellular. This study aims to assess the utility of ALK immunocytochemical (ICC) staining on direct smears using the cell transfer (CT) technique for the detection of ALK rearrangement. Methods: Fine-needle aspiration (FNA) cases of lung adenocarcinoma in which the ALK status had been determined by FISH on CB or a concurrent biopsy were identified. ICC staining for ALK was performed on alcohol-fixed Papanicolaou-stained direct smears using the CT technique. ALK immunoreactivity was evaluated using a modified semiquantitative scale. Results were compared with those of FISH. Results: A total of 47 FNA specimens were included. Five of 7 FISH-positive cases showed positive ALK ICC staining (71.4%), and 39 of 40 FISH-negative cases were negative on ALK ICC staining (97.5%). The overall correlation between ALK ICC and FISH was 93.6%. Conclusion: ICC performed on FNA smears using the CT technique is an alternative method for the assessment of ALK rearrangement, especially when CB lack adequate cellularity

Persistence of Pathogens with Short Infectious Periods in Seasonal Tick Populations: The Relative Importance of Three Transmission Routes

BACKGROUND: The flaviviruses causing tick-borne encephalitis (TBE) persist at low but consistent levels in tick populations, despite short infectious periods in their mammalian hosts and transmission periods constrained by distinctly seasonal tick life cycles. In addition to systemic and vertical transmission, cofeeding transmission has been proposed as an important route for the persistence of TBE-causing viruses. Because cofeeding transmission requires ticks to feed simultaneously, the timing of tick activity may be critical to pathogen persistence. Existing models of tick-borne diseases do not incorporate all transmission routes and tick seasonality. Our aim is to evaluate the influence of seasonality on the relative importance of different transmission routes by using a comprehensive mathematical model. METHODOLOGY/PRINCIPAL FINDINGS: We developed a stage-structured population model that includes tick seasonality and evaluated the relative importance of the transmission routes for pathogens with short infectious periods, in particular Powassan virus (POWV) and the related "deer tick virus," emergent encephalitis-causing flaviviruses in North America. We used the next generation matrix method to calculate the basic reproductive ratio and performed elasticity analyses. We confirmed that cofeeding transmission is critically important for such pathogens to persist in seasonal tick populations over the reasonable range of parameter values. At higher but still plausible rates of vertical transmission, our model suggests that vertical transmission can strongly enhance pathogen prevalence when it operates in combination with cofeeding transmission. CONCLUSIONS/SIGNIFICANCE: Our results demonstrate that the consistent prevalence of POWV observed in tick populations could be maintained by a combination of low vertical, intermediate cofeeding and high systemic transmission rates. When vertical transmission is weak, nymphal ticks support integral parts of the transmission cycle that are critical for maintaining the pathogen. We also extended the model to pathogens that cause chronic infections in hosts and found that cofeeding transmission could contribute to elevating prevalence even in these systems. Therefore, the common assumption that cofeeding transmission is not relevant in models of chronic host infection, such as Lyme disease, could lead to underestimating pathogen prevalence

Soil Resources Area Affects Herbivore Health

Soil productivity effects nutritive quality of food plants, growth of humans and animals, and reproductive health of domestic animals. Game-range surveys sometimes poorly explained variations in wildlife populations, but classification of survey data by major soil types improved effectiveness. Our study evaluates possible health effects of lower condition and reproductive rates for wild populations of Odocoileus virginianus Zimmerman (white-tailed deer) in some physiographic regions of Mississippi. We analyzed condition and reproductive data for 2400 female deer from the Mississippi Department of Wildlife, Fisheries, and Parks herd health evaluations from 1991–1998. We evaluated age, body mass (Mass), kidney mass, kidney fat mass, number of corpora lutea (CL) and fetuses, as well as fetal ages. Region affected kidney fat index (KFI), which is a body condition index, and numbers of fetuses of adults (P ≤ 0.001). Region affected numbers of CL of adults (P ≤ 0.002). Mass and conception date (CD) were affected (P ≤ 0.001) by region which interacted significantly with age for Mass (P ≤ 0.001) and CD (P < 0.04). Soil region appears to be a major factor influencing physical characteristics of female deer

Volatile profiling reveals intracellular metabolic changes in Aspergillus parasticus: veA regulates branched chain amino acid and ethanol metabolism

Background: Filamentous fungi in the genus Aspergillus produce a variety of natural products, including aflatoxin, the most potent naturally occurring carcinogen known. Aflatoxin biosynthesis, one of the most highly characterized secondary metabolic pathways, offers a model system to study secondary metabolism in eukaryotes. To control or customize biosynthesis of natural products we must understand how secondary metabolism integrates into the overall cellular metabolic network. By applying a metabolomics approach we analyzed volatile compounds synthesized by Aspergillus parasiticus in an attempt to define the association of secondary metabolism with other metabolic and cellular processes. Results: Volatile compounds were examined using solid phase microextraction - gas chromatography/mass spectrometry. In the wild type strain Aspergillus parasiticus SU-1, the largest group of volatiles included compounds derived from catabolism of branched chain amino acids (leucine, isoleucine, and valine); we also identified alcohols, esters, aldehydes, and lipid-derived volatiles. The number and quantity of the volatiles produced depended on media composition, time of incubation, and light-dark status. A block in aflatoxin biosynthesis or disruption of the global regulator veA affected the volatile profile. In addition to its multiple functions in secondary metabolism and development, VeA negatively regulated catabolism of branched chain amino acids and synthesis of ethanol at the transcriptional level thus playing a role in controlling carbon flow within the cell. Finally, we demonstrated that volatiles generated by a veA disruption mutant are part of the complex regulatory machinery that mediates the effects of VeA on asexual conidiation and sclerotia formation. Conclusions: 1) Volatile profiling provides a rapid, effective, and powerful approach to identify changes in intracellular metabolic networks in filamentous fungi. 2) VeA coordinates the biosynthesis of secondary metabolites with catabolism of branched chain amino acids, alcohol biosynthesis, and b-oxidation of fatty acids. 3) Intracellular chemical development in A. parasiticus is linked to morphological development. 4) Understanding carbon flow through secondary metabolic pathways and catabolism of branched chain amino acids is essential for controlling and customizing production of natural products